Compressively Strained Fe3O4 in Core-Shell Oxygen Reduction Electrocatalyst Boosts Zinc-Air Battery Performance.

Fe3O4 is barely taken into account as an electrocatalyst for oxygen reduction reaction (ORR), an important reaction for metal-air batteries and fuel cells, due to its sluggish catalytic kinetics and poor electron conductivity. Herein, how strain engineering can be employed to regulate the local electronic structure of Fe3O4 for high ORR activity is reported. Compressively strained Fe3O4 shells with 2.0% shortened Fe─O bond are gained on the Fe/Fe4N cores as a result of lattice mismatch at the interface. A downshift of the d-band center occurs for compressed Fe3O4, leading to weakened chemisorption energy of oxygenated intermediates, and lower reaction overpotential. The compressed Fe3O4 exhibits greatly enhanced electrocatalytic ORR activity with a kinetic current density of 27 times higher than that of pristine one at 0.80 V (vs reversible hydrogen electrode), as well as potential application in zinc-air batteries. The findings provide a new strategy for tuning electronic structures and improving the catalytic activity of other metal catalysts.

Continuous Flow Electrochemical Synthesis of Olivine-Structured NaFePO4 Cathode Material for Sodium-Ion Batteries from Recycle LiFePO4.

To mitigate the environmental impact of the improper disposal of spent LiFePO4 batteries and reduce resource waste, the development of LiFePO4 recycling technologies is of paramount importance. Meanwhile, olivine-structured NaFePO4 in sodium-ion batteries has received great attention, due to its high theoretical specific capacity of 154 mAh g-1 and excellent stability. However, olivine NaFePO4 only can be synthesized from olivine LiFePO4. Accordingly, in this proposal, developing the continuous flow electrochemical solid-liquid reactor-based metal ion insertion technology is to utilize the olivine FePO4, recycled from LiFePO4, and to synthesize NaFePO4. Additionally, by employing I- as the reducing agent, NaFePO4 is successfully synthesized with a discharge-specific capacity of 134 mAh g-1 at 0.1C and a remarkable capacity retention rate of 86.5% after 100 cycles at 0.2C. And the reasons for sodium deficiency in the synthesized NFP are elucidated through first-principles calculations. Furthermore, the kinetics of the solid-solution reaction 2 (Na2/3+ßPO4→ Na1-αFePO4) mechanism improve with cycling and are sensitive to temperature. Utilizing a minimal amount of reducing agent in the electrochemical reactor, NaFePO4 synthesis is successfully achieved. This innovative approach offers a new, cost-effective, and environmentally friendly strategy for preparing NaFePO4 from recycling LiFePO4.

LiF/Li3N-Rich Electrode-Electrolyte Interfaces Enabled by Multi-Functional Electrolyte Additive to Achieve High-Performance Li/LiNi0.8Co0.1Mn0.1O2 Batteries.

LiPF6-based carbonate electrolytes have been extensively employed in commercial Li-ion batteries, but they face numerous interfacial stability challenges while applicating in high-energy-density lithium-metal batteries (LMBs). Herein, this work proposes N-succinimidyl trifluoroacetate (NST) as a multifunctional electrolyte additive to address these challenges. NST additive could optimize Li+ solvation structure and eliminate HF/H2O in the electrolyte, and preferentially be decomposed on the Ni-rich cathode (LiNi0.8Co0.1Mn0.1O2, NCM811) to generate LiF/Li3N-rich cathode-electrolyte interphase (CEI) with high conductivity. The synergistic effect reduces the electrolyte decomposition and inhibits the transition metal (TM) dissolution. Meanwhile, NST promotes the creation of solid electrolyte interphase (SEI) rich in inorganics on the Li metal anode (LMA), which restrains the growth of Li dendrites, minimizes parasitic reactions, and fosters rapid Li+ transport. As a result, compared with the reference, the Li/LiNi0.8Co0.1Mn0.1O2 cell with 1.0 wt.% NST exhibits higher capacity retention after 200 cycles at 1C (86.4% vs. 64.8%) and better rate performance, even at 9C. In the presence of NST, the Li/Li symmetrical cell shows a super-stable cyclic performance beyond 500 h at 0.5 mA cm-2/0.5 mAh cm-2. These unique features of NST are a promising solution for addressing the interfacial deterioration issue of high-capacity Ni-rich cathodes paired with LMA.

Atomic Engineering Modulates Oxygen Reduction of Hollow Carbon Matrix Confined Single Metal-Nitrogen Sites for Zinc-Air Batteries.

The systematical understanding of metal-dependent activity in electrocatalyzing oxygen reduction reaction (ORR), a vital reaction with sluggish kinetics for zinc-air batteries, remains quite unclear. An atomic and spatial engineering modulating ORR activity over hollow carbon quasi-sphere (HCS) confined in a series of single M-N (M = Cu, Mn, Ni) sites is reported here. Based on the theoretical prediction and experimental validation, Cu-N4 site with the lowest overpotential shows a better ORR kinetics than Mn-N4 and Ni-N4 . The ORR activity of single-atom Cu center can be further improved by decreasing the coordination number of N to two, namely Cu-N2 , due to the enhancement of electrons with lower coordination structure. Benefitting from the unique spatial confinement effect of the HCS structure in modulating electronic feature of active sites, the Cu-N2 site confined in HCS also delivers highly improved ORR kinetics and activity relative to that on planner graphene. Additionally, the best catalyst holds excellent promise in the application of zinc-air batteries. The findings will pave a new way to atomically and electronically tune active sites with high efficiency for other single-atom catalysts.

Weakened Contractile Performance and Mitochondrial Respiratory Complex Activity in Skeletal Muscle Improve during Interbout Arousal in Hibernating Daurian Ground Squirrel, Spermophilus dauricus.

Mammalian hibernation is composed of multiple episodes of torpor bout, separated by phases of interbout arousal. During torpor, the skeletal muscles of mammals are undoubtedly inactive, but it has been proven to mitigate disuse atrophy. While interbout arousal has been implicated in the prevention of muscle atrophy, the underlying mechanisms sustaining muscle contraction remain to be explored. In the present study, Daurian ground squirrels (Spermophilus dauricus) were divided into four groups: pre-hibernation (PRE), torpor (TOR), interbout arousal (IBA), and post-hibernation (POST). The contractile performance of slow-twitch soleus muscle (SOL) and fast-twitch extensor digitorum longus muscle (EDL) was detected both in situ and in vitro. Concurrently, mitochondrial respiratory chain complex activity in these muscles was quantified. Our findings revealed that in situ contractile properties of both muscles, including force, power output, time duration, and force development/relaxation rates of twitch contraction, and force and power output of tetanic contraction declined in the TOR group compared to the PRE group, but improved in the IBA and POST groups. Fatigue resistance of muscles, determined by the power output of repetitive tetanic contractions in situ, decreased in the TOR group but recovered in the IBA and POST groups. In vitro studies demonstrated that tetanic contraction power output in isolated muscles increased with muscle temperature in both TOR and IBA groups. However, at the same temperature, power output was consistently lower in the TOR group compared to the IBA group. Moreover, the activity of the mitochondrial respiratory chain complex, especially Complexes I and II, decreased in the TOR group but showed recovery in the IBA and POST groups. These findings suggest that both the contractile performance and fatigue resistance of mammalian skeletal muscle are compromised during torpor but can be improved during interbout arousal and post-hibernation. The rebound in body temperature and rise in mitochondrial respiratory chain complex activity in skeletal muscle are involved in enhancing contractile performance and fatigue resistance. This study suggests that interbout arousal functions as a vital temporal interval during which skeletal muscles can transition from the inactivity induced by torpor to a state of restored contractile functionality. Thus, interbout arousal serves as a behavioral safeguard against disuse-induced damage to skeletal muscles during hibernation.

Remarkable Plasticity of Bone Iron Homeostasis in Hibernating Daurian Ground Squirrels (Spermophilus dauricus) May Be Involved in Bone Maintenance.

Iron overload is an independent risk factor for disuse osteoporosis. Hibernating animals are natural models of anti-disuse osteoporosis; however, whether iron metabolism is involved in bone adaptation and maintenance during hibernation is unclear. To investigate this question, Daurian ground squirrels (Spermophilus dauricus) (n = 5-6/group) were used to study changes in bone iron metabolism and its possible role in anti-disuse osteoporosis during hibernation. Iron content in the femur and liver first decreased in the torpor group (vs. summer group, -66.8% and -25.8%, respectively), then recovered in the post-hibernation group, suggesting remarkable plasticity of bone iron content. The expression of ferritin in the femur and hepcidin in the liver also initially decreased in the torpor group (vs. summer group, -28.5% and -38.8%, respectively), then increased in the inter-bout arousal (vs. torpor group, 126.2% and 58.4%, respectively) and post-hibernation groups (vs. torpor group, 153.1% and 27.1%, respectively). In conclusion, bone iron metabolism in hibernating Daurian ground squirrels showed remarkable plasticity, which may be a potential mechanism to avoid disuse bone loss during extended periods of inactivity. However, the specific location of iron during low-iron hibernation and the source of iron in post-hibernation recovery need to be further explored.

Differential protein metabolism and regeneration in hypertrophic diaphragm and atrophic gastrocnemius muscles in hibernating Daurian ground squirrels.

NEW FINDINGS: What is the central question of this study? The aim was to investigate whether diaphragm hypertrophy and gastrocnemius atrophy during hibernation of Daurian ground squirrels involve differential regulation of protein metabolism and regeneration. What is the main finding and its importance? We clarified the differences in protein metabolism and muscle regenerative potential in the diaphragm and gastrocnemius of hibernating ground squirrels, reflecting the different adaptability of muscles. ABSTRACT: Are differences in the regulation of protein metabolism and regeneration involved in the different phenotypic adaptation mechanisms of muscle hypertrophy and atrophy in hibernators? Two fast-type muscles (diaphragm and gastrocnemius) in summer active and hibernating Daurian ground squirrels were selected to detect changes in cross-sectional area (CSA) and protein expression indicative of protein synthesis metabolism (protein expression of P-Akt, P-mTORC1, P-S6K1 and P-4E-BP1), protein degradation metabolism (MuRF1, atrogin-1, calpain-1, calpain-2, calpastatin, desmin, troponin T, Beclin1 and LC3-II) and muscle regeneration (MyoD, myogenin and myostatin). In the hibernation group compared with the summer active group, the CSA of the diaphragm muscle increased significantly by 26.1%, whereas the CSA of the gastrocnemius muscle decreased significantly by 20.4%. Our study also indicated that increased protein synthesis, decreased protein degradation and increased muscle regenerative potential contributed to diaphragm muscle hypertrophy, whereas decreased protein synthesis, increased protein degradation and decreased muscle regenerative potential contributed to gastrocnemius muscle atrophy. In conclusion, the differences in muscle regeneration and regulatory pattern of protein metabolism might contribute to the different adaptive changes observed in the diaphragm and gastrocnemius muscles of ground squirrels.

Different fuel regulation in two types of myofiber results in different antioxidant strategies in Daurian ground squirrels (Spermophilus dauricus) during hibernation.

We previously showed that different skeletal muscles in Daurian ground squirrels (Spermophilus dauricus) possess different antioxidant strategies during hibernation; however, the reason for these varied strategies remains unclear. To clarify this issue, we studied REDD1, FOXO4, PGC-1α, FOXO1 and atrogin-1 proteins to determine the potential cause of the different antioxidant strategies in Daurian ground squirrels during hibernation, and to clarify whether different strategies affect atrophy-related signals. Results showed that the soleus (SOL) muscle experienced intracellular hypoxia during interbout arousal, but no oxidative stress. This may be due to increased PGC-1α expression enhancing antioxidant capacity in the SOL under hypoxic conditions. Extensor digitorum longus (EDL) muscle showed no change in oxidative stress, hypoxia or antioxidant capacity during hibernation. The FOXO1 and PGC-1α results strongly suggested differentially regulated fuel metabolism in the SOL and EDL muscles during hibernation, i.e. enhanced lipid oxidation and maintained anaerobic glycolysis, respectively. Atrogin-1 expression did not increase during hibernation in either the SOL or EDL, indicating that protein synthesis was not inhibited by atrogin-1. Thus, our results suggest that different fuel regulation may be one mechanism related to antioxidant defense strategy formation in different kinds of skeletal muscle fibers of Daurian ground squirrels during hibernation.

Different fuel regulation in two types of myofiber results in different antioxidant strategies in Daurian ground squirrels (Spermophilus dauricus) during hibernation.

We previously showed that different skeletal muscles in Daurian ground squirrels (Spermophilus dauricus) possess different antioxidant strategies during hibernation; however, the reason for these varied strategies remains unclear. To clarify this issue, we studied REDD1, FOXO4, PGC-1α, FOXO1, and atrogin-1 proteins to determine the potential cause of the different antioxidant strategies in Daurian ground squirrels during hibernation, and to clarify whether different strategies affect atrophy-related signals. Results showed that the soleus (SOL) muscle experienced intracellular hypoxia during interbout arousal, but no oxidative stress. This may be due to increased PGC-1α expression enhancing antioxidant capacity in the SOL under hypoxic conditions. Extensor digitorum longus (EDL) muscle showed no change in oxidative stress, hypoxia, or antioxidant capacity during hibernation. The FOXO1 and PGC-1α results strongly suggested differentially regulated fuel metabolism in the SOL and EDL muscles during hibernation, i.e., enhanced lipid oxidation and maintained anaerobic glycolysis, respectively. Atrogin-1 expression did not increase during hibernation in either the SOL or EDL, indicating that protein synthesis was not inhibited by atrogin-1. Thus, our results suggest that different fuel regulation may be one mechanism related to antioxidant defense strategy formation in different kinds of skeletal muscle fibers of Daurian ground squirrels during hibernation.

Prosurvival roles mediated by the PERK signaling pathway effectively prevent excessive endoplasmic reticulum stress-induced skeletal muscle loss during high-stress conditions of hibernation.

Stress conditions like hypoxia, ischemia, and ischemia/reperfusion can trigger excessive endoplasmic reticulum stress (ERS), which can lead to cell apoptosis-induced skeletal muscle atrophy in non-hibernators. However, although hibernators experience multiple stress conditions during hibernation, their skeletal muscles appear to be well protected. We hypothesize that hibernators effectively avoid cell apoptosis, at least partially, by controlling ERS level. Here, we focused on the potential occurrence of ERS and how hibernators cope with it during different hibernation states. Results indicated that the protein expression levels of glucose-regulated protein 78 (GRP78), phosphorylated PKR-like ER protein kinase, phosphorylated eukaryotic translation initiation factor 2α (p-eIF2α), and activating transcription factor 4 were significantly increased during hibernation, but primarily recovered in posthibernation. In the torpor-arousal cycle, the expression levels of the above indicators were lower during inter-bout arousal (IBA) than that during late torpor (LT). However, there was no change in C/EBP homologous protein expression and no apoptosis in skeletal muscles during the different hibernation states. In conclusion, the upregulation of p-eIF2α and GRP78 were identified as two crucial mechanisms mediated by the PERK signaling pathway to alleviate elevated ERS. The downregulation of ERS during IBA may be a unique countermeasure for hibernating squirrels to prevent excessive ERS. Thus, these special anti-excessive ERS abilities of ground squirrels contribute to the prevention of skeletal muscle cell apoptosis during hibernation.

Novel findings on ultrastructural protection of skeletal muscle fibers during hibernation of Daurian ground squirrels: Mitochondria, nuclei, cytoskeleton, glycogen.

We examined ultrastructure protective phenomena and mechanisms of slow and fast muscles in hibernating Daurian ground squirrels (Spermophilus dauricus). Some degenerative changes such as slightly decreased sarcomere length and vacuolization occurred in hibernation, but periaxonal capsular borders in intrafusal fibers remained distinct and the arrangement of extrafusal fibers and Z-lines unscathed. In soleus samples, the number of glycogenosomes more than tripled during hibernation. The expression of phosphorylated glycogen synthase remained unaltered while that of glycogen phosphorylase decreased during hibernation. The number of extensor digitorum longus glycogenosomes decreased and the expression of phosphorylated glycogen synthase decreased, while glycogen phosphorylase expression remained unaltered. The nuclei number remained unchanged. Kinesin and desmin, preventors of nuclear loss and damage, were maintained or just slightly reduced in hibernation. The single-fiber mitochondrial concentration and sub-sarcolemmal mitochondrial number increased in both muscle types. The expression of vimentin, which anchors mitochondria and maintains Z-line integrity, was increased during and after hibernation. Also, dynamin-related protein 1, mitochondrial fission factor, and adenosine triphosphate synthase were elevated in both muscle types. These findings confirm a remarkable ultrastructure preservation and show an unexpected increase in mitochondrial capacity in hibernating squirrels.

Stress-responsive microRNAs are involved in re-programming of metabolic functions in hibernators.

Mammalian hibernation includes re-programing of metabolic capacities, partially, encouraged by microRNAs (miRNAs). Albeit much is known about the functions of miRNAs, we need learning on low temperature miRNAs target determination. As hibernators can withstand low body temperatures (TB) for a long time without anguish tissue damage, understanding the means and mechanisms that empower them to do as such are of restorative intrigue. Nonetheless, these mechanisms by which miRNAs and the hibernators react to stressful conditions are not much clear. It is evident from recent data that the gene expression and the translation of mRNA to protein are controlled by miRNAs. The miRNAs also influence regulation of major cellular processes. As the significance of miRNAs in stress conditions adaptation are getting clearer, this audit article abridges the key alterations in miRNA expression and the mechanism that facilitates stress survival.

Unexpected regulation pattern of the IKKß/NF-κB/MuRF1 pathway with remarkable muscle plasticity in the Daurian ground squirrel (Spermophilus dauricus).

As a typical hibernator, the Daurian ground squirrel (Spermophilus dauricus) spends considerable time in a state of reduced activity with prolonged fasting. Despite this, they experience little muscle atrophy and have thus become an interesting anti-disuse muscle atrophy model. The IKKß/NF-κB signaling pathway is significant to muscle atrophy due to the protein degradation resulting from the upregulation of the E3 ubiquitin ligase MuRF1. The current study showed that the IKKß/NF-κB signaling pathway and MuRF1 maintained relatively steady mRNA and protein expression levels, with little muscle atrophy observed in the soleus (slow-twitch, SOL) or extensor digitorum longus (fast-twitch, EDL) during hibernation (HIB); however, mRNA expression significantly increased in the SOL and EDL muscle during interbout arousal (IBA), as did the MuRF1 mRNA level in the SOL and MuRF1 protein level in the EDL. Interestingly, the expressions of p50 and MuRF1 significantly increased during HIB in the gastrocnemius (mixed muscle, GAS) and showed moderate atrophy, but dramatically decreased during IBA. Elevated IKKß and p50 mRNA and protein expression in the cardiac muscle (CM) during HIB did not accompany increased MuRF1 expression or muscle wasting. Importantly, almost all increased or decreased indicators in the tested tissues recovered to pre-hibernation levels after HIB. This is the first study to report on the unexpected regulation of the IKKß/NF-κB/MuRF1 pathway with remarkable muscle plasticity in Daurian ground squirrels during hibernation. Furthermore, we found that different types of muscles exhibited different strategies to cope with prolonged hibernation-induced disuse muscle atrophy.

iTRAQ-based proteomic analysis of myofibrillar contents and relevant synthesis and proteolytic proteins in soleus muscle of hibernating Daurian ground squirrels (Spermophilus dauricus).

BACKGROUND: Daurian ground squirrels (Spermophilus dauricus) deviate from significant increase of protein catabolism and loss of myofibrillar contents during long period of hibernation inactivity. METHODS: Here we use iTRAQ based quantitative analysis to examine proteomic changes in the soleus of squirrels in pre-hibernation, hibernation and post-hibernation states. The total proteolysis rate of soleus was measured by the release of the essential amino acid tyrosine from isolated muscles. Immunofluorescent analysis was used to determine muscle fiber cross-sectional area. Western blot was used for the validation of the quantitative proteomic analysis. RESULTS: The proteomic responses to hibernation had a 0.4- to 0.8-fold decrease in the myofibrillar contractile protein levels of myosin-3, myosin-13 and actin, but a 2.1-fold increase in myosin-2 compared to pre-hibernation group. Regulatory proteins such as troponin C and tropomodulin-1 were 1.4-fold up-regulated and 0.7-fold down-regulated, respectively, in hibernation compared to pre-hibernation group. Moreover, 10 proteins with proteolytic function in hibernation, which was less than 14 proteins in the post-hibernation group, were up-regulated relative to the pre-hibernation group. The total proteolysis rates of soleus in hibernation and post-hibernation groups were significantly inhibited as compared with pre-hibernation group. CONCLUSION: These findings suggest that the myofibrillar remodeling and partial suppression of myofibrillar proteolysis were likely responsible for preventing skeletal muscle atrophy during prolonged disuse in hibernation. This is the first study where the myofibrillar contents and relevant synthesis and proteolytic proteins in slow soleus was discussed based on proteomic investigation performed on wild Daurian ground squirrels. Our results lay the foundation for further research in preventing disuse-induced skeletal muscle atrophy in mammals.

[Effect of two Pi deficiency syndrome models on the configuration and function of the skeletal muscle in mice].

OBJECTIVE: To observe the relation between Pi deficiency syndrome (PDS) and the configuration and functions of extensor digitorum longus (EDL)and soleus (SOL). METHODS: Totally 36 ICR mice were randomly divided into 3 groups according to weight matching principle, the control group, the exhausted group, and the rhubarb group, 12 in each group. Two PDS models were established by either purgation with rhubarb diarrhea (as Group A) or exhausted swimming plus sleep deprivation (as Group B).The cross sectional area (CSA) of type I and II fibers of extensor digitorum longus (EDL) and soleus (SOL), relative proportions of type I and II fibers were measured by m-ATPase histochemical method. The isotonic contraction and the maximum tetanus contraction of EDL and SOL were detected by PowerLab system. RESULTS: Compared with the control group, the body weight, body temperature, and the general health condition of PDS model rats obviously decreased; the spleen index and the thymus index were also lower; the maximal isotonic contraction and the maximum tetanus contraction obviously decreased; the cross section areas of EDL and SOL were reduced with loosely arranged cells. In EDL, the proportion of type I fibers was added and the proportion of type II fibers was lowered. In SOL, there was no change in the proportion of type I and type II fibers. CONCLUSIONS: EDL and SOL were obviously atrophied in the two PDS model mice. The type I fibers of SOL was more significantly atrophied in Group B.

Changes in calpains and calpastatin in the soleus muscle of Daurian ground squirrels during hibernation.

We investigated changes in muscle mass, calpains, calpastatin and Z-disk ultrastructure in the soleus muscle (SOL) of Daurian ground squirrels (Spermophilus dauricus) after hibernation or hindlimb suspension to determine possible mechanisms by which muscle atrophy is prevented in hibernators. Squirrels (n=30) were divided into five groups: no hibernation group (PRE, n=6); hindlimb suspension group (HLS, n=6); two month hibernation group (HIB, n=6); two day group after 90±12 days of hibernation (POST, n=6); and forced exercise group (one time forced, moderate-intensity treadmill exercise) after arousal (FE, n=6). Activity and protein expression of calpains were determined by casein zymography and western blotting, and Z-disk ultrastructure was observed by transmission electron microscopy. The following results were found. Lower body mass and higher SOL muscle mass (mg) to total body mass (g) ratio were observed in HIB and POST; calpain-1 activity increased significantly by 176% (P=0.034) in HLS compared to the PRE group; no significant changes were observed in calpain-2 activity. Protein expression of calpain-1 and calpain-2 increased by 83% (P=0.041) and 208% (P=0.029) in HLS compared to the PRE group, respectively; calpastatin expression increased significantly by 180% (P<0.001) and 153% (P=0.007) in HIB and POST, respectively; the myofilaments were well-organized, and the width of the sarcomere and the Z-disk both appeared visually similar among the pre-hibernation, hibernating and post-hibernation animals. Inhibition of calpain activity and consequently calpain-mediated protein degradation by highly elevated calpastatin protein expression levels may be an important mechanism for preventing muscle protein loss during hibernation and ensuring that Z-lines remained ultrastructurally intact.

Roles of Myokines and Muscle-Derived Extracellular Vesicles in Musculoskeletal Deterioration under Disuse Conditions.

Prolonged inactivity and disuse conditions, such as those experienced during spaceflight and prolonged bedrest, are frequently accompanied by detrimental effects on the motor system, including skeletal muscle atrophy and bone loss, which greatly increase the risk of osteoporosis and fractures. Moreover, the decrease in glucose and lipid utilization in skeletal muscles, a consequence of muscle atrophy, also contributes to the development of metabolic syndrome. Clarifying the mechanisms involved in disuse-induced musculoskeletal deterioration is important, providing therapeutic targets and a scientific foundation for the treatment of musculoskeletal disorders under disuse conditions. Skeletal muscle, as a powerful endocrine organ, participates in the regulation of physiological and biochemical functions of local or distal tissues and organs, including itself, in endocrine, autocrine, or paracrine manners. As a motor organ adjacent to muscle, bone tissue exhibits a relative lag in degenerative changes compared to skeletal muscle under disuse conditions. Based on this phenomenon, roles and mechanisms involved in the communication between skeletal muscle and bone, especially from muscle to bone, under disuse conditions have attracted widespread attention. In this review, we summarize the roles and regulatory mechanisms of muscle-derived myokines and extracellular vesicles (EVs) in the occurrence of muscle atrophy and bone loss under disuse conditions, as well as discuss future perspectives based on existing research.

Ultralong Cycling and Interfacial Regulation of Bilayer Heterogeneous Composite Solid-State Electrolytes in Lithium Metal Batteries.

Under the background of "carbon neutral", lithium-ion batteries (LIB) have been widely used in portable electronic devices and large-scale energy storage systems, but the current commercial electrolyte is mainly liquid organic compounds, which have serious safety risks. In this paper, a bilayer heterogeneous composite solid-state electrolyte (PLPE) was constructed with the 3D LiX zeolite nanofiber (LiX-NF) layer and in-situ interfacial layer, which greatly extends the life span of lithium metal batteries (LMB). LiX-NF not only offers a continuous fast path for Li+, but also zeolite's Lewis acid-base interaction can immobilize large anions, which significantly improves the electrochemical performance of the electrolyte. In addition, the in-situ interfacial layer at the electrode-electrolyte interface can effectively facilitate the uniform deposition of Li+ and inhibit the growth of lithium dendrites. As a result, the Li/Li battery assembled with PLPE can be stably cycled for more than 2500 h at 0.1 mA cm-2. Meanwhile, the initial discharge capacity of the LiFePO4/PLPE/Li battery can be 162.43 mAh g-1 at 0.5 C, and the capacity retention rate is 82.74% after 500 cycles. These results emphasize that this bilayer heterogeneous composite solid-state electrolyte has distinct properties and shows excellent potential for application in LMB.

Polydopamine-Induced Metal-Organic Framework Network-Enhanced High-Performance Composite Solid-State Electrolytes for Dendrite-Free Lithium Metal Batteries.

Due to the high safety, flexibility, and excellent compatibility with lithium metals, composite solid-state electrolytes (CSEs) are the best candidates for next-generation lithium metal batteries, and the construction of fast and uniform Li+ transport is a critical part of the development of CSEs. In this paper, a stable three-dimensional metal-organic framework (MOF) network was obtained using polydopamine as a medium, and a high-performance CSE reinforced by the three-dimensional MOF network was constructed, which not only provides a continuous channel for Li+ transport but also restricts large anions and releases more mobile Li+ through a Lewis acid-base interaction. This strategy endows our CSEs with an ionic conductivity (7.1 × 10-4 S cm-1 at 60 °C), a wide electrochemical window (5.0 V), and a higher Li+ transfer number (0.54). At the same time, the lithium symmetric batteries can be stably cycled for 2000 h at 0.1 mA cm-2, exhibiting excellent electrochemical stability. The LiFePO4/Li cells have a high initial discharge specific capacity of 153.9 mAh g-1 at 1C, with a capacity retention of 80% after 915 cycles. This paper proposes an approach for constructing three-dimensional MOF network-enhanced CSEs, which provides insights into the design and development of MOFs for the positive effects of high-performance CSEs.

Plasticity changes in iron homeostasis in hibernating Daurian ground squirrels (Spermophilus dauricus) may counteract chronically inactive skeletal muscle atrophy.

Disuse-induced muscular atrophy is frequently accompanied by iron overload. Hibernating animals are a natural animal model for resistance to disuse muscle atrophy. In this paper, we explored changes in skeletal muscle iron content of Daurian ground squirrels (Spermophilus dauricus) during different periods of hibernation as well as the regulatory mechanisms involved. The results revealed that compared with the summer active group (SA), iron content in the soleus muscle (SOL) decreased (- 65%) in the torpor group (TOR), but returned to normal levels in the inter-bout arousal (IBA); splenic iron content increased in the TOR group (vs. SA, + 67%), decreased in the IBA group (vs. TOR, - 37%). Expression of serum hepcidin decreased in the TOR group (vs. SA, - 22%) and returned to normal levels in the IBA groups; serum ferritin increased in the TOR group (vs. SA, + 31%), then recovered in the IBA groups. Soleus muscle transferrin receptor 1 (TfR1) expression increased in the TOR group (vs. SA, + 83%), decreased in the IBA group (vs. TOR, - 30%); ferroportin 1 increased in the IBA group (vs. SA, + 55%); ferritin increased in the IBA group (vs. SA, + 42%). No significant differences in extensor digitorum longus in iron content or iron metabolism-related protein expression were observed among the groups. Significantly, all increased or decreased indicators in this study returned to normal levels after the post-hibernation group, showing remarkable plasticity. In summary, avoiding iron overload may be a potential mechanism for hibernating Daurian ground squirrels to avoid disuse induced muscular atrophy. In addition, the different skeletal muscle types exhibited unique strategies for regulating iron homeostasis.