Metal-organic frameworks (MOFs) are a new class of microporous materials that possess framework flexibility, large surface areas, “tailor-made” framework functionalities, and tunable pore sizes. These features empower MOFs superior performances and broader application spectra than those of zeolites and phosphine-based molecular sieves. In parallel with designing new structures and new chemistry of MOFs, the observation of unique breathing behaviors upon adsorption of gases or solvents stimulates their potential applications as host materials in gas storage for renewable energy. This has attracted intense research energy to understand the causes at the atomic level, using in situ X-ray diffraction, calorimetry, Fourier transform infrared spectroscopy, and molecular dynamics simulations. This article is developed in the following order: first to introduce the definition of MOFs and the observation of their framework flexibility. Second, synthesis routes of MOFs are summarized with the emphasis on the hydrothermal synthesis, owing to the environmental-benign and economically availability of water. Third, MOFs exhibiting breathing behaviors are summarized, followed by rationales from thermodynamic viewpoint. Subsequently, effects of various functionalities on breathing behaviors are appraised, including using post-synthetic modification routes. Finally, possible framework spatial requirements of MOFs for yielding breathing behaviors are highlighted as the design strategies for new syntheses.

• Synchrotron X-ray imaging and in situ visualization of microbubble cavitation. • Microbubble characteristics and cavitation dynamics at different US frequencies. • A higher number of bubbles with smaller size were created at higher US frequency. • Bubbles with the size close to the resonance size moved slower. • The majority of small bubbles moved toward the US transducer (antinode)

Biodegradable membranes with innovative antifouling properties are emerging as possible substitutes for conventional membranes. These types of membranes have the potential to be applied in a wide range of applications, from water treatment to food packaging and energy production. Nevertheless, there are several existing challenges and limitations associated with the use of biodegradable membranes in large scale applications, and further studies are required to determine the degradation mechanisms and their scalability. Biodegradable membranes can be produced from either renewable natural resources or synthesized from low-molecular monomers that increase the number of possible structures and, as a result, greatly expand the membrane application possibilities. This study focused on bio-sourced and synthesized biodegradable polymers as green membrane materials. Moreover, the article highlighted the excellent antifouling properties of biodegradable membranes that assist in improving membrane lifetime during filtration processes, preventing chemical/biological disposal due to frequent cleaning processes and ultimately reducing the maintenance cost. The industrial and biomedical applications of biodegradable membranes were also summarized, along with their limitations. Finally, an overview of challenges and future trends regarding the use of biodegradable membranes in various industries was thoroughly analyzed.