Glassfrogs conceal blood in their liver to maintain transparency

Abstract

Transparency in animals is a complex form of camouflage involving mechanisms that reduce light scattering and absorption throughout the organism. In vertebrates, attaining transparency is difficult because their circulatory system is full of red blood cells (RBCs) that strongly attenuate light. Here, we document how glassfrogs overcome this challenge by concealing these cells from view. Using photoacoustic imaging to track RBCs in vivo, we show that resting glassfrogs increase transparency two- to threefold by removing ~89% of their RBCs from circulation and packing them within their liver. Vertebrate transparency thus requires both see-through tissues and active mechanisms that “clear” respiratory pigments from these tissues. Furthermore, glassfrogs’ ability to regulate the location, density, and packing of RBCs without clotting offers insight in metabolic, hemodynamic, and blood-clot research.

Multi‐Scale Volumetric Dynamic Optoacoustic and Laser Ultrasound (OPLUS) Imaging Enabled by Semi‐Transparent Optical Guidance

“…[81 ] More importantly, the layer-by-layer coating approach enables precise control of the transparency level of a silica substrate and can be easily scaled to facilitate the development of hybrid OPLUS endoscopic imaging systems or miniaturized fiberoptic-based intravascular probes . [82 ] It can also be combined with laser-interferometry-based detectors of the US to enable remote operation. [83,84 ] The intensity of the US waves generated via light absorption in the thin film coating of the optical fibers can be increased by reducing the specific heat per unit area, increasing the thermal expansion coefficient, or enlarging the active surface of the emitter .…”

Non-monotonic Information and Shape Evolution of Polymers Enabled by Spatially Programmed Crystallization and Melting

“…In the natural world, many creatures have evolved the ability to respond to the surrounding environment for survival. , For example, the octopus can alter its body shape and surface pattern to mimic various environments and other creatures. As inspired by biological systems, many intelligent polymer materials that can sense and respond to the external environment have been developed.…”

High-Entropy Laminates with High Ion Conductivities for High-Power All-Solid-State Lithium Metal Batteries

“…All-solid-state lithium metal batteries (ASSLMBs) based on solid-state electrolytes (SSEs) have emerged as one of the newly generated energy storage devices as they offer a substantial improvement in high energy densities and high safety by eliminating the heavy and flammable organic solvents. , The features of high thermal degradation temperature, solvent-free, and convenient for large-scale production make SSEs develop rapidly in recent years. − However, current SSEs are still unable to be used commercially, mainly ascribed to slow Li + transfer kinetics and unsatisfactory mechanical strength.…”

“…To solve the above problem of slow Li + transfer kinetics of the SSEs, a great deal of work is mainly focused on the exploration of enhancing the ionic conductivity by introducing aliovalent atoms into the crystal structure of inorganic SSEs. − Li 7 La 3 Zr 2 O 12 (LLZO), as a typical SSE, exhibits higher ionic conductivity (2.4 × 10 –4 S cm –1 ) in cubic phase than that of its counterpart in tetragonal phase (2.3 × 10 –5 S cm –1 ), while the cubic phase is unstable at room temperature. − Recently, many types of aliovalent ions (Ta 5+ , W 6+ , Te 6+ , and Nb 5+ ) are introduced into the crystal structure of LLZO, creating additional vacancies at Li + sites and further reducing the free energy of Li + transfer. , Through aliovalent atoms doping and vacancy regulation, Li 7– x La 3 Zr 2– x M x O 12 (M = Nb and Ta) delivers a higher ionic conductivity of 4 × 10 –4 S cm –1 than LLZO at room temperature, benefited from the stabilized phase with high conductivity and fast transport of lithium ions . However, current inorganic SSEs including LLZO and Li 1.3 Al 0.3 Ti 1.7 P 3 O 12 (LATP) are inevitably limited by their poor mechanical properties and complicated processing conditions, greatly hampering the practical applications. − On this occasion, polymers or their monomers are introduced into inorganic SSEs to fabricate composite electrolytes by physical-mechanical mixing, guaranteeing the ion transport properties and enhancing the mechanical strength to a certain extent. ,, For instance, poly­(propylene oxide) (PEO) elastomer is introduced into the LLZO, greatly improving its mechanical strength (∼1.0 MPa) and meanwhile improving the movement of PEO segments and the transport of Li + .…”