Thin film modeling of crystal dissolution and growth in confinement

We present a continuum model describing dissolution and growth of a crystal contact confined against a substrate. Diffusion and hydrodynamics in the liquid film separating the crystal and the substrate are modeled within the lubrication approximation. The model also accounts for the disjoining pressure and surface tension. Within this framework, we obtain evolution equations which govern the non-equilibrium dynamics of the crystal interface. Based on this model, we explore the problem of dissolution under an external load, known as pressure solution. We find that in steady-state, diverging (power-law) crystal-surface repulsions lead to flat contacts with a monotonic increase of the dissolution rate as a function of the load. Forces induced by viscous dissipation then surpass those due to disjoining pressure at large enough loads. In contrast, finite repulsions (exponential) lead to sharp pointy contacts with a dissolution rate independent on the load and on the liquid viscosity. Ultimately, in steady-state the crystal never touches the substrate when pressed against it, independently from the nature of the crystal-surface interaction due to the combined effects of viscosity and surface tension

A 3D Cd(II) Coordination Polymer With SRA Topology

<div><p>One new cadmium(II) coordination polymer, [Cd(pzdc)(H₂O)] (<b>1</b>) (H₂pzdc = pyrazine-2,3-dicarboxylic acid) has been synthesized by the reaction of Cd(II) ions with H₂pzdc under the solvothermal condition and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that <b>1</b> (C₆H₄CdN₂O₅) crystallizes in the orthorhombic crystal system, space group <i>Pnma</i>. In compound <b>1</b>, the pzdc ligands link Cd(II) ions into a 3D 4-connected {4².6³.8}(SRA) topological net.</p></div

A 2D Cd(II) Coordination Polymer Constructed From 1,3-di(4-pyridyl)propane and 2,7-naphthalenedisulfonate

<div><p>A new coordination polymer [Cd(2,7-nds)(bpp)₂]·2DMA·4H₂O (<b>1</b>) (2,7-nds = 2,7-naphthalene disulfonic acid, bpp = 1,3-di(4-pyridyl)propane, DMA = N,N-Dimethylacetamide) has been synthesized by assembly of Cd(II) with 2,7-nds and bpp ligands and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that <b>1</b> crystallizes in the monoclinic crystal system, space group <i>C2</i>. Topological analysis of <b>1</b> discloses an uninodal 4-connected net with the sql topology.</p></div

Highly Alloyed PtRu Nanoparticles Confined in Porous Carbon Structure as a Durable Electrocatalyst for Methanol Oxidation

The state-of-the-art carbon-supported PtRu catalysts are widely used as the anode catalysts in polymer electrolyte fuel cells (PEMFCs) but suffer from instability issues. Severe ruthenium dissolution occurring at potentials higher than 0.5 V vs NHE would result in a loss of catalytic activity of PtRu hence a worse performance of the fuel cell. In this work, we report an ultrastable PtRu electrocatalyst for methanol oxidation by confining highly alloyed PtRu nanoparticles in a hierarchical porous carbon structure. The structural characteristics, e.g., the surface composition and the morphology evolution, of the catalyst during the accelerated degradation test were characterized by the Cu-stripping voltammetry and the TEM/SEM observations. From the various characterization results, it is revealed that both the high alloying degree and the pore confinement of PtRu nanoalloys play significant roles in suppressing the degradation processes, including Ru dissolution and particle agglomeration/migration. This report provides an opportunity for efficient design and fabrication of highly stable bimetallic or trimetallic electrocatalysts in a large variety of applications

GR blockade prior to brief context re-exposure has no effect on subsequent fear expression.

<p>A) Behavioral procedure for the experiment. B) Freezing behavior decreased in only vehicle treated mice on day 3 compared to day 2. Treating mice with RU486 or vehicle (on day 2) resulted in comparable freezing behavior over time. <b>^#</b> reflects P<0.05 when compared to freezing on day 2 (n = 7 mice per group).</p

GR blockade prior to six-tone re-exposure has no effect on subsequent fear expression.

<p>A) Behavioral procedure for the experiment. B) Freezing behavior in vehicle treated mice decreased both on day 3 and one month later when compared to the first tone exposure on day 2. RU486 treated mice displayed reduced freezing one month later. No difference in freezing behavior was found between vehicle and RU486 treated animals. <b>^#</b>and<b>^##</b> reflect P<0.05 and P<0.01 respectively when compared to day 2 (n = 6 mice per group).</p

MR blockade without context re-exposure has no effect on subsequent fear expression.

<p>A) Behavioral procedure for the experiment. B) Spironolactone was injected 23 hours after training in the absence of re-exposure to the fearful context on day 2. No effect of spironolactone on contextual memory retention was found twenty four hours (day 3) or one month later (n = 6 mice per group).</p

MR blockade immediately after brief context re-exposure has no effect on subsequent fear expression.

<p>A) Behavioral procedure for the experiment. B) Freezing behavior during brief retrieval was comparable between the two groups. Treating animals with spironolactone immediately after brief re-exposure did not affect contextual memory retention on day 3 or one month after retrieval (n = 6 mice per group).</p

Diarylheptanoids from the fresh pericarps of <i>Juglans sigillata</i>

<p>One new diarylheptanoid (3<i>S</i>)-3′, 4″-epoxy-1-(4′-hydroxylphenyl)-7-(3″-hydroxylphenyl) heptane-3-hydroxy (<b>1</b>), together with eleven known ones (<b>2</b>–<b>12</b>), was isolated from the fresh pericarps of <i>Juglans sigillata</i>. Their structures were elucidated on the basis of extensive spectroscopic methods, including HR-ESI-MS, 1D and 2D-NMR. All isolates were evaluated for their cytotoxic activities <i>in vitro</i> against the growth of human cancer cells lines HT-29 and MCF-7 by MTT assay.</p

GR blockade prior to one tone re-exposure has no effect on subsequent fear expression.

<p>A) Behavioral procedure for the experiment. B) Freezing behavior in vehicle treated mice decreased on day 3 compared to day 2. Treatment with RU486 resulted in less freezing one month later compared to day 2. No significant RU486 effect was found. <b>^#</b> reflects P<0.05 when compared to day 2 (n = 6 mice per group).</p