After traumatic brain injury (TBI), neurons surviving the initial insult can undergo chronic (secondary) degeneration via poorly understood mechanisms, resulting in long-term cognitive impairment. Although a neuroinflammatory response is promptly activated after TBI, it is unknown whether it has a significant role in chronic phases of TBI (Ͼ1 year after injury). Using a closed-head injury model of TBI in mice, we showed by MRI scans that TBI caused substantial degeneration at the lesion site within a few weeks and these did not expand significantly thereafter. However, chronic alterations in neurons were observed, with reduced dendritic spine density lasting Ͼ1 year after injury. In parallel, we found a long-lasting inflammatory response throughout the entire brain. Deletion of one allele of CX 3 CR1, a chemokine receptor, limited infiltration of peripheral immune cells and largely prevented the chronic degeneration of the injured brain and provided a better functional recovery in female, but not male, mice. Therefore, targeting persistent neuroinflammation presents a new therapeutic option to reduce chronic neurodegeneration.
Increasingly stringent regulations and new applications require selecting improved refrigerants for heat pumps. The selected refrigerants should be environmentally friendly and maximize the performance of the heat pump process. Systematic refrigerant selection methods usually model the compressor with one fixed isentropic efficiency identical for all refrigerants. However, compressor studies indicate that the isentropic efficiency may be highly refrigerant‐dependent. Herein, the need for a refrigerant‐dependent compressor model for refrigerant selection is investigated. For this purpose, a refrigerant‐dependent compressor model is combined with an integrated design of refrigerant and heat pump process. To guarantee a comparable nominal heating power among refrigerants, the compressor design is tailored to the refrigerant by expanding the refrigerant‐dependent compressor model toward compressor sizing. Integrating compressor design into systematic refrigerant selection is enabled by a computationally efficient model implementation. Accounting for refrigerant‐dependent compression substantially changes the resulting refrigerant ranking compared to the widely used assumption of identical isentropic efficiencies for all refrigerants: The best‐performing refrigerant is not even identified among the best ten refrigerants when assuming identical isentropic efficiencies. Consequently, compression is identified as the main driver for differences in refrigerant performance. Therefore, integrating refrigerant‐dependent compressor models is crucial for systematic refrigerant selection.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.