Adenosine deaminase acting on RNA 2 (ADAR2), an RNA editing enzyme is involved in a site‐selective modification of adenosine (A) to inosine (I) in double‐stranded RNA (dsRNA). Its role in the lungs is unknown. The phenotypic characterization of Adarb1 mice that lacked ADAR2 auto‐regulation due to the deletion of editing complementary sequence (ΔECS mice) determined the functional role of ADAR2 in the lungs. ADAR2 protein expression increased in the ΔECS mice. These mice display immune cell infiltration and alveolar disorganization. The lung wet by dry ratio indicates there is no lung edema in ΔECS mice. Bronchoalveolar lavage (BAL) analysis of ΔECS mice reveals a significant increase in neutrophils. Interestingly, ΔECS mice spontaneously develop lung fibrosis as indicated by Sirius red staining of collagen fibers in the lung sections and a significant increase in hydroxyproline level in their lungs. ADAR2 expression increased significantly in a bleomycin mouse model, implicating a role of ADAR2 in lung fibrosis. Furthermore, there is a likely possibility that the genetically modified ΔECS mice does not model the physiological or pathophysiological process of lung fibrosis. Nevertheless, this model is useful in interrogating the role of ADAR2 in the lungs. The Ctgf mRNA and connective tissue growth factor (CTGF) protein significantly increased in ΔECS lungs and occurs in bronchial epithelial cells. There is a significant increase in Human antigen R (ELAVL1; HuR) protein levels in ΔECS lungs and suggests a role in stabilizing Ctgf mRNA. Lung mechanics such as total respiratory resistance, Newtonian resistance and tissue damping were increased, whereas inspiratory capacity was decreased in the ΔECS mice. Taken together, these data indicate that overexpression of ADAR2 causes spontaneous lung fibrosis via HuR‐mediated CTGF signaling and implicate a role for ADAR2 auto‐regulation in lung homeostasis. The identification of ADAR2 target genes in ΔECS mice would facilitate a mechanistic understanding of the role of ADAR2 in the lungs and provide a therapeutic strategy for lung fibrosis.
As the energy sector shifts from fossil fuels to renewable energy, there is a need for long-duration energy storage solutions to handle the intermittency of renewable electricity. Electrofuels, or fuels synthesized from excess electricity, are an emerging medium poised to meet long-duration energy storage requirements. Ammonia as an electrofuel is potentially ideal because ammonia has a relatively low liquefaction pressure, indicating that ammonia can be easily stored and transported. Here, we develop a framework to optimize the electrochemical production of ammonia powered by intermittent photovoltaic power. We also explore various buyback policies to understand the impact that policy has on the cost of intermittent ammonia and optimal sizing ratios. The optimal ratio of the photovoltaic to the electrolyzer is ~3.7 MW$_{PV}$/MW$_{ELEC}$ for an system that is completely powered by renewable photovoltaic power and operates intermittently. The optimal ratio of the photovoltaic to the electrolyzer is ~3.3 MW _PV/MW_Elec for a system that uses photovoltaics in conjunction with grid electricity and operates continuously. For the purchase price at the avoided cost of electricity, the optimal ratio of the solar panel to the electrolyzer increases to ~4 MW _PV/MW_Elec for a system that can only sell to the grid and ~5 MW_PV/MW_Elect for a system that can buy and sell electricity to the grid at the avoided cost. Optimizing energy management by setting auxiliary battery size limits is essential to reduce ammonia cost, and the optimal battery size decreases as the buyback price of electricity increases. Finally, we find that systems connected to the grid and operating continuously have emissions comparable to the Haber-Bosch process because of the current emissions tied to the United States electricity generation. Thus, unless the grid is completely decarbonized, it is essential to create electro-fuels that rely minimally on grid electricity.
As the energy sector shifts from fossil fuels to renewable energy sources, there is a need for robust energy storage solutions to handle the intermittency of renewable electricity. With the rise of the electric vehicle, electrochemical storage in the form of lithium-ion batteries has gained significant attention. Lithium-ion batteries are a good solution for short-term and small-scale energy storage. However, they are not optimal for large-scale energy storage due to their high price and low power density. Green fuels, such as ammonia, are ideal for storing large quantities of energy to tackle renewable electricity intermittency. Ammonia has an energy density comparable to certain fossil fuels, and if produced through renewable methods, it can serve as a zero-emission energy vector. For ammonia to serve as an energy storage solution, it has to be available at low costs and in a decentralized manner. However, the prevalent use of ammonia in the fertilizer industry hinders its use as an energy vector.State-of-the-art ammonia synthesis plants (Haber-Bosch process) achieve high energy efficiencies and low product cost through a high temperature and pressure thermochemical process. The process is responsible for feeding half of the global population, but it also emits 450 million tons of carbon dioxide per year. Thus, while this process is deemed efficient and affordable, there are many environmental concerns regarding the sustainability of the Haber-Bosch process. Furthermore, the scale at which these facilities must operate to achieve these low costs limits the locations where a Haber-Bosch plant can be built. Centralized manufacturing of ammonia indirectly impacts a developing country’s ability to access fertilizers. With the strong correlation between fertilizer usages and agricultural yield, access to fertilizers is essential to mitigate global hunger. This has motivated a strong interest in rethinking how we manufacture fertilizer-based feedstocks such as ammonia.Electrochemical manufacturing of ammonia is one approach being explored for ammonia production, as electrochemical systems can operate at relatively low temperature and pressure. Additionally, electrochemical technologies are scalable and can enable manufacturing at a range of scales to meet large and small agricultural and energy storage demands. However, there are significant challenges associated with electrochemical manufacturing. Electrocatalysts suffer from poor nitrogen reduction selectivity, resulting in low product yield, low energy efficiency, and high capital and operational cost. Since cost ultimately will be the primary driver for technology adoption, it is critical to begin to determine what role system and catalyst design play in reducing the cost of ammonia to meet Haber-Bosch parity.Here, we present a detailed techno-economic study on low-temperature electrochemical ammonia production. Techno-economic analyses are valuable to determine the cost of the performance targets to achieve economic feasibility and identify possible roadblocks...
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