Self-Assembly of Archimedean Tilings with Enthalpically and Entropically Patchy Polygons

Considerable progress in the synthesis of anisotropic patchy nanoplates (nanoplatelets) promises a rich variety of highly ordered two-dimensional superlattices. Recent experiments of superlattices assembled from nanoplates confirm the accessibility of exotic phases and motivate the need for a better understanding of the underlying self-assembly mechanisms. Here, we present experimentally accessible, rational design rules for the self-assembly of the Archimedean tilings from polygonal nanoplates. The Archimedean tilings represent a model set of target patterns that (i) contain both simple and complex patterns, (ii) are comprised of simple regular shapes, and (iii) contain patterns with potentially interesting materials properties. <i>Via</i> Monte Carlo simulations, we propose a set of design rules with general applicability to one- and two-component systems of polygons. These design rules, specified by increasing levels of patchiness, correspond to a reduced set of anisotropy dimensions for robust self-assembly of the Archimedean tilings. We show for which tilings entropic patches alone are sufficient for assembly and when short-range enthalpic interactions are required. For the latter, we show how patchy these interactions should be for optimal yield. This study provides a minimal set of guidelines for the design of anisostropic patchy particles that can self-assemble all 11 Archimedean tilings

Summary of the statistical analyses performed from ΔLinearity measurements carried out on cross-section images from MPAM-SHGM or histopathology.

<p>SHGM: Second Harmonic generation Microscopy, SD: Standard Deviation, AUC: Area Under the Curve, TP: True Positive, FP: False Positive, TN: True Negative, FN: False Negative.</p><p>Summary of the statistical analyses performed from ΔLinearity measurements carried out on cross-section images from MPAM-SHGM or histopathology.</p

Mechanistic Investigation of the Generation of a Palladium(0) Catalyst from a Palladium(II) Allyl Complex: A Combined Experimental and DFT Study

Cross-coupling reactions can be efficiently catalyzed using palladium complexes. The formation of low-coordinated, highly reactive Pd(0), which is believed to be the catalytic species, is critical. The mechanism of the reduction of a stable and readily available allyl Pd­(II) complex into Pd(0) by a combination of K₂CO₃ and PhB­(OH)₂ has been studied. We report on the characterization of the associated reactive solution using a combination of density functional theory and experimental methods. First, the stoichiometric reaction of an (allyl)­(phosphine)­palladium­(II) complex with K₂CO₃ was first investigated using trandem mass spectrometry. A palladium–carbonate complex could be characterized in the electrospray mass spectrum of the reactive solution. Gas-phase infrared spectra of mass-selected complexes have been recorded, giving further information on the coordination mode (κ¹) of the carbonate ligand. This structural information derived from spectroscopy is critical because the relative energy of the two κ¹- and κ²-carbonate isomers is difficult to determine theoretically, presumably because of the charge transfers at play between the carbonate and the palladium. Second, the product of the stoichiometric addition of PhB­(OH)₂ to this carbonate complex was investigated. Both ³¹P and ¹H NMR data provide compelling evidence for the formation of the desired 14-electron Pd(0) complex

ROC curve at 95% confidence for ΔLinearity calculated from MPAM-SHGM (Blue) and histological (Green) images.

<p>ROC curve at 95% confidence for ΔLinearity calculated from MPAM-SHGM (Blue) and histological (Green) images.</p

Mechanistic Investigation of the Generation of a Palladium(0) Catalyst from a Palladium(II) Allyl Complex: A Combined Experimental and DFT Study

Cross-coupling reactions can be efficiently catalyzed using palladium complexes. The formation of low-coordinated, highly reactive Pd(0), which is believed to be the catalytic species, is critical. The mechanism of the reduction of a stable and readily available allyl Pd­(II) complex into Pd(0) by a combination of K₂CO₃ and PhB­(OH)₂ has been studied. We report on the characterization of the associated reactive solution using a combination of density functional theory and experimental methods. First, the stoichiometric reaction of an (allyl)­(phosphine)­palladium­(II) complex with K₂CO₃ was first investigated using trandem mass spectrometry. A palladium–carbonate complex could be characterized in the electrospray mass spectrum of the reactive solution. Gas-phase infrared spectra of mass-selected complexes have been recorded, giving further information on the coordination mode (κ¹) of the carbonate ligand. This structural information derived from spectroscopy is critical because the relative energy of the two κ¹- and κ²-carbonate isomers is difficult to determine theoretically, presumably because of the charge transfers at play between the carbonate and the palladium. Second, the product of the stoichiometric addition of PhB­(OH)₂ to this carbonate complex was investigated. Both ³¹P and ¹H NMR data provide compelling evidence for the formation of the desired 14-electron Pd(0) complex

Early events during neoplastic transformation.

<p>Schematic representation of the current understanding of cellular and layer-based changes with neoplasia (a-c), MPAM-SHGM micrographs (d-f) and histological sections (g-i) of hamster oral mucosa for normal (a, d, g), mild dysplasia (b, e, h) and severe dysplasia (c, f, i) are shown. <i>In-vivo</i> autofluorescence from MPAM (Red) co-registered with SHG (Green) are overlaid to produce cross-sectional MPAM-SHGM micrographs (d-f) comparable to histology (g-i). K: Keratinizing layer; E: Epithelial layer, M: Lamina propria or ECM. White and black arrows point towards ECTI and “*” shows enlarged nuclei in dysplastic epithelium. Scale bar: 50μm.</p

Cytological features visible in <i>in-vivo</i> MPAM are shown from normal (a), and dysplastic (b,c) epithelium of hamster oral mucosa.

<p>White boxes in “a” and “b” shows comparison of nuclear density between a normal (0.25 nuclei/100 μm²) and dysplastic epithelium (0.12 nuclei/100 μm²). “*” shows presence of keratin pearls (b) and arrows point towards enlarged nuclei (c) in dysplastic epithelium.</p

Cross-sectional x-z SHGM micrograph is shown in (a). Figure (b) shows an ECTI (solid white line) extracted from (a) after the FeatureJ: Edges plugin in ImageJ was applied.

<p>The dashed line represents the reference linear distance between the two ends of the image. The equations on the right were used to calculate ΔLinearity (ΔL_norm). Scale bar: 50 μm.</p

Consumption of carotenoids not increased by bacterial infection in brown trout embryos (<i>Salmo trutta</i>)

<div><p>Carotenoids are organic pigment molecules that play important roles in signalling, control of oxidative stress, and immunity. Fish allocate carotenoids to their eggs, which gives them the typical yellow to red colouration and supports their resistance against microbial infections. However, it is still unclear whether carotenoids act mainly as a shield against infection or are used up during the embryos’ immune defence. We investigated this question with experimental families produced from wild-caught brown trout (<i>Salmo trutta</i>). Singly raised embryos were either exposed to the bacterial pathogen <i>Pseudomonas fluorescens</i> or sham-treated at one of two stages during their development. A previous study on these experimental families reported positive effects of egg carotenoids on embryo growth and resistance against the infection. Here, we quantified carotenoid consumption, i.e. the active metabolization of carotenoids into compounds that are not other carotenoid types, in these infected and sham-infected maternal sib groups. We found that carotenoid contents mostly decreased during embryogenesis. However, these decreases were neither linked to the virulence induced by the pathogen nor dependent on the time point of infection. We conclude that egg carotenoids are not significantly used up by the embryos’ immune defence.</p></div

Epithelial Thickness measurements from MPAM-SHGM (a) and histology (b) show statistically significant increase in thickness of mild, moderate and severe dysplasia from normal mucosa.

<p>Box plot analyses show the median, 25^th and 75^th percentiles, and outliers for both MPAM-SHGM and histology. “*” and “**” represent statistical difference between groups at p<0.05 and 0.01 significance respectively.</p