Partial differentiation of Europa and implications for the origin of materials in the Jupiter system
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Metabolic control analysis of biogeochemical systems
Many reactive systems involve processes operating at different scales, such as hydrodynamic transport and diffusion, abiotic chemical reactions, microbial metabolism, and population dynamics. Determining the influence of these processes on system dynamics is critical for model design and for prioritizing parameter estimation efforts. Metabolic control analysis is a framework for quantifying the role of enzymes in cellular biochemical networks, but its applicability to biogeochemical and other reactive systems remains unexplored. Here I show how the core concepts of metabolic control analysis can be generalized to much more complex reactive systems, enabling insight into the roles of physical transport, population dynamics, and chemical kinetics at organismal to planetary scales. I demonstrate the power of this framework for two systems of importance to ocean biogeochemistry: A simplified (mostly didactic) model for the sulfate methane transition zone in Black Sea sediments, and a more comprehensive model for the oxygen minimum zone in Saanich Inlet near steady state. I find that physical transport is by far the greatest rate-limiting factor for sulfate-driven methane oxidation in the first system and for fixed nitrogen loss in the second system.
The evolution of lithium-ion battery recycling
Demand for lithium-ion batteries (LIBs) is increasing owing to the expanding use of electrical vehicles and stationary energy storage. Efficient and closed-loop battery recycling strategies are therefore needed, which will require recovering materials from spent LIBs and reintegrating them into new batteries. In this Review, we outline the current state of LIB recycling, evaluating industrial and developing technologies. Among industrial technologies, pyrometallurgy can be broadly applied to diverse electrode materials but requires operating temperatures of over 1,000 °C and therefore has high energy consumption. Hydrometallurgy can be performed at temperatures below 200 °C and has material recovery rates of up to 93% for lithium, nickel and cobalt, but it produces large amounts of wastewater. Developing technologies such as direct recycling and upcycling aim to increase the efficiency of LIB recycling and rely on improved pretreatment processes with automated disassembly and cleaner mechanical separation. Additionally, the range of materials recovered from spent LIBs is expanding from the cathode materials recycled with established methods to include anode materials, electrolytes, binders, separators and current collectors. Achieving an efficient recycling ecosystem will require collaboration between recyclers, battery manufacturers and electric vehicle manufacturers to aid the design and automation of battery disassembly lines.
Novel function of TREK-1 in regulating adipocyte differentiation and lipid accumulation
K2P (two-pore domain potassium) channels, a diversified class of K+-selective ion channels, have been found to affect a wide range of physiological processes in the body. Despite their established significance in regulating proliferation and differentiation in multiple cell types, K2P channels’ specific role in adipogenic differentiation (adipogenesis) remains poorly understood. In this study, we investigated the engagement of K2P channels, specifically KCNK2 (also known as TREK-1), in adipogenesis using primary cultured adipocytes and TREK-1 knockout (KO) mice. Our findings showed that TREK-1 expression in adipocytes decreases substantially during adipogenesis. This typically causes an increased Ca2+ influx and alters the electrical potential of the cell membrane in 3T3-L1 cell lines. Furthermore, we observed an increase in differentiation and lipid accumulation in both 3T3-L1 cell lines and primary cultured adipocytes when the TREK-1 activity was blocked with Spadin, the specific inhibitors, and TREK-1 shRNA. Finally, our findings revealed that mice lacking TREK-1 gained more fat mass and had worse glucose tolerance when fed a high-fat diet (HFD) compared to the wild-type controls. The findings demonstrate that increase of the membrane potential at adipocytes through the downregulation of TREK-1 can influence the progression of adipogenesis.
Pilot-scale partial nitrification and anaerobic ammonium oxidation system for nitrogen removal from municipal wastewater
Partial nitrification has the advantages of saving energy and reducing the need for carbon sources in municipal wastewater treatment. However, for municipal wastewater with low ammonia, start-up and maintenance of partial nitrification is a worldwide challenge. Here we developed a pilot-scale double sludge system consisting of two sequencing batch reactors for partial nitrification (12 m2) and denitrification/anaerobic ammonium oxidation (denitrification/anammox, 8.4 m2) to treat municipal wastewater. Partial nitrification was maintained at no ammonium remaining with a nitrite accumulation rate of 87.7%. This study found that partial nitrification system effluent chemical oxygen demand increased from 24.8 mg L−1 to 64.9 mg L−1 accompanied by transformation from complete nitrification to partial nitrification. In the denitrification/anammox system, the reduction of nitrite to nitrogen required about 40% less carbon consumption than nitrate. High nitrogen removal was achieved with effluent total inorganic nitrogen of 2.7 mg L−1 without carbon addition. This work provided a pilot-scale demonstration of low-carbon high-nitrogen removal.
Personalized bioceramic grafts for craniomaxillofacial bone regeneration
The reconstruction of craniomaxillofacial bone defects remains clinically challenging. To date, autogenous grafts are considered the gold standard but present critical drawbacks. These shortcomings have driven recent research on craniomaxillofacial bone reconstruction to focus on synthetic grafts with distinct materials and fabrication techniques. Among the various fabrication methods, additive manufacturing (AM) has shown significant clinical potential. AM technologies build three-dimensional (3D) objects with personalized geometry customizable from a computer-aided design. These layer-by-layer 3D biomaterial structures can support bone formation by guiding cell migration/proliferation, osteogenesis, and angiogenesis. Additionally, these structures can be engineered to degrade concomitantly with the new bone tissue formation, making them ideal as synthetic grafts. This review delves into the key advances of bioceramic grafts/scaffolds obtained by 3D printing for personalized craniomaxillofacial bone reconstruction. In this regard, clinically relevant topics such as ceramic-based biomaterials, graft/scaffold characteristics (macro/micro-features), material extrusion-based 3D printing, and the step-by-step workflow to engineer personalized bioceramic grafts are discussed. Importantly, in vitro models are highlighted in conjunction with a thorough examination of the signaling pathways reported when investigating these bioceramics and their effect on cellular response/behavior. Lastly, we summarize the clinical potential and translation opportunities of personalized bioceramics for craniomaxillofacial bone regeneration.
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