Metaplasia of respiratory and digestive tissues in the eastern oyster Crassostrea virginica associated with the Deepwater Horizon oil spill

Metaplasia is a well documented and deleterious effect of crude oil components on oysters. This reversible transformation of one cell type to another is a common response to petroleum-product exposure in molluscs. It has been shown experimentally in previous work that eastern oysters (Crassostrea virginica) exposed to petroleum products will exhibit metaplasia of digestive tissues. Here we document for the first time that wild adult oysters inhabiting coastal waters in the northern Gulf of Mexico during and in the aftermath of the Deepwater Horizon oil spill (2010) exhibited metaplasia in both ctenidial (respiratory and suspension feeding) and digestive tract tissues at significantly higher frequencies than geographic controls of C. virginica from Chesapeake Bay. Metaplasia included the loss of epithelial cilia, transformations of columnar epithelia, hyperplasia and reduction of ctenidial branches, and vacuolization of digestive tissues. Evidence for a reduction of metaplasia following the oil spill (2010-2013) is suggestive but equivocal.

A Reconfigurable Perovskite/Polymer Composite Film for Real-Time Detection of Agricultural Spraying

Responsive composites that can display sophisticated responses under environmental stimuli are of paramount importance for developing smart materials and systems. However, the hierarchical design of their multiscale constituents to achieve such response remains a challenge. Here, we report a responsive polymer composite obtained by integrating hierarchical interactions between the polymer network meshes, perovskite nanoinclusion, and a microstructured layout. More specific, a layered composite film has been made with perovskite nanoparticles embedded in a hydratable polymer network as the top layer. The perovskites inclusions can undergo a reversible transformation between a nanocrystalline state and a dissociated ion state, triggered by spraying aqueous solutions on the polymer top layer, resulting in an on/off switch of fluorescence at 510 nm. Meanwhile, the surface layer experiences a reconfigurable micro-wrinkling that can gradually change the film transmittance between 90% and 10%. The two orthogonal responses show a good reversibility for at least 15 cycles. They can be manipulated independently as they respond differently to the amount of water applied. We demonstrate the use of such film by real-time, quantitative, and repeatable detection of spraying and subsequent droplet distribution. Such a sensing capability is urgently needed in precision agriculture for fast assessing the deposition quality of pesticides and fertilizers, yet still not available. Our findings enable the design of perovskite-based responsive composites with multiple functions as well as novel device applications in sensors, actuators, and optoelectronics.

New Photoresponsive Poly(meth)acrylates Bearing Azobenzene Moieties Obtained via ATRP Polymerization Exhibiting Liquid-Crystalline Behavior

Here, we report our studies on photoresponsive poly(meth)acrylates containing azobenzene groups connected to a polymer backbone via a short methylene linker. A series of side-chain azobenzene polymers was synthesized via the atom transfer radical polymerization (ATRP) technique using several catalytic systems. The polymers synthesized under the optimized conditions were characterized by a narrow polydispersity (Đ ≤ 1.35), and they underwent a reversible transformation of their structure under light illumination. The fabricated polymers can store and release energy accumulated during the UV-light illumination by the thermal cis-trans isomerization of the chromophore groups. The enthalpy of the process (determined from DSC) was relatively high and equaled 61.9 J∙g−1 (17 Wh∙kg−1), indicating a high potential of these materials in energy storage applications. The liquid-crystalline behavior of the synthesized poly(meth)acrylates was demonstrated by the birefringent optical textures as observed in thin-films and X-ray scattering studies.

Stationarization and Multithermalization in spin glasses

We develop further the study of a system in contact with a multibath having different temperatures at widely separated timescales. We consider those systems that do not thermalize in finite times when in contact with an ordinary bath but may do so in contact with a multibath. Thermodynamic integration is possible, thus allowing one to recover the stationary distribution on the basis of measurements performed in a `multi-reversible' transformation. We show that following such a protocol the system is at each step described by a generalization of the Boltzmann-Gibbs distribution, that has been studied in the past. Guerra's bound interpolation scheme for spin-glasses is closely related to this: by translating it into a dynamical setting, we show how it may actually be implemented in practice. The phase diagram plane of temperature vs ``number of replicas", long studied in spin- glasses, in our approach becomes simply that of the two temperatures the system is in contact with. We suggest that this representation may be used to directly compare phenomenological and mean-field inspired models. Finally, we show how an approximate out of equilibrium probability distribution may be inferred experimentally on the basis of measurements along an almost reversible transformation.

A Pneumatic Generator Based on Gas-Liquid Reversible Transition for Soft Robots

The soft robots actuated by pressure, cables, thermal, electrosorption, combustion and smart materials are usually faced with the problems of poor portability, noise, weak load capacity, small deformation and high driving voltages. In this paper, a novel pneumatic generator for soft robots based on the gas-liquid reversible transition is proposed, which has the advantages of large output force, easy deformation, strong load capacity and high flexibility. The pressure of the pneumatic generator surges or drops flexibly through the reversible transformation between liquid and gas phase, making the soft actuator stretch or contract regularly, without external motors, compressors and pressure-regulating components. The gas-liquid reversible-transition actuation process is modeled to analyze its working mechanism and characteristics. The pressure during the pressurization stage increases linearly with a rate regulated by the heating power and gas volume. It decreases exponentially with the exponential term as a quadratic function of time at the fast depressurization stage, while with the exponential term as a linear function of time at the slow depressurization stage. The drop rate can be adjusted by changing the gas volume and cooling conditions. Furthermore, effectiveness has been verified through experiments of the prototype. The pressure reaches 25 bar with a rising rate of +3.935 bar/s when 5 mL weak electrolyte solution is heated at 800 W, and the maximum depressurization rate in air cooling is –3.796 bar/s. The soft finger actuated by the pneumatic generator can bend with an angular displacement of 67.5°. The proposed pneumatic generator shows great potential to be used for the structure, driving and sensing integration of artificial muscles.

Is Configurational Entropy the Main Stabilizing Term in Rock-Salt Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O High-Entropy Oxide?

We question the conclusions reported in the paper "Entropy-stabilized Oxides, by C. Rost et al., by looking into the role of configurational entropy as the stabilization of the rock-salt cubic structure of the Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (HEO) solid solution (SS). First, we demonstrate that configurational entropy can be reduced from 1.61R for HEO to 0.5R for a two-member SS, still obtaining a single-phase material if the molar fractions of ZnO and CuO are 0.2. These SSs behave identically as HEO regarding the reversible transformation between a multi- and single-phase states when temperatures are cycled between 800 and 1000 °C. Second, we demonstrate that the different SSs presenting a configurational entropy significantly lower than HEO, are less prone to the cubic to tetragonal structural distortion, suggesting that the configurational entropy has not the central role as stabilizing factor of the rock-salt structure.<br>