Autophagy is an intracellular trafficking mechanism by which cytosolic macromolecules and organelles are sequestered into autophagosomes for degradation inside the vacuole. In various eukaryotes ...including yeast, metazoans, and plants, the precursor of the autophagosome, termed the phagophore, nucleates in the vicinity of the endoplasmic reticulum (ER) with the participation of phosphatidylinositol 3-phosphate (PI3P) and the coat protein complex II (COPII). Here we show that Arabidopsis thaliana FYVE2, a plant-specific PI3P-binding protein, provides a functional link between the COPII machinery and autophagy. FYVE2 interacts with the small GTPase Secretion-associated Ras-related GTPase 1 (SAR1), which is essential for the budding of COPII vesicles. FYVE2 also interacts with ATG18A, another PI3P effector on the phagophore membrane. Fluorescently tagged FYVE2 localized to autophagic membranes near the ER and was delivered to vacuoles. SAR1 fusion proteins were also targeted to the vacuole via FYVE2-dependent autophagy. Either mutations in FYVE2 or the expression of dominant-negative mutant SAR1B proteins resulted in reduced autophagic flux and the accumulation of autophagic organelles. We propose that FYVE2 regulates autophagosome biogenesis through its interaction with ATG18A and the COPII machinery, acting downstream of ATG2.
Under nutrient and energy-limiting conditions, plants up-regulate sophisticated catabolic pathways such as autophagy to remobilize nutrients and restore energy homeostasis. Autophagic flux is tightly ...regulated under these circumstances through the AuTophaGy-related1 (ATG1) kinase complex, which relays upstream nutrient and energy signals to the downstream components that drive autophagy. Here, we investigated the role(s) of the Arabidopsis (
) ATG1 kinase during autophagy through an analysis of a quadruple mutant deficient in all four ATG1 isoforms. These isoforms appear to act redundantly, including the plant-specific, truncated ATG1t variant, and like other well-characterized
mutants, homozygous
quadruple mutants display early leaf senescence and hypersensitivity to nitrogen and fixed-carbon starvations. Although ATG1 kinase is essential for up-regulating autophagy under nitrogen deprivation and short-term carbon starvation, it did not stimulate autophagy under prolonged carbon starvation. Instead, an ATG1-independent response arose requiring phosphatidylinositol-3-phosphate kinase (PI3K) and SUCROSE NONFERMENTING1-RELATED PROTEIN KINASE1 (SnRK1), possibly through phosphorylation of the ATG6 subunit within the PI3K complex by the catalytic KIN10 subunit of SnRK1. Together, our data connect ATG1 kinase to autophagy and reveal that plants engage multiple pathways to activate autophagy during nutrient stress, which include the ATG1 route as well as an alternative route requiring SnRK1 and ATG6 signaling.plantcell;31/12/2973/FX1F1fx1.
Solid polymer electrolytes suffer from the low ionic conductivity and poor capability of suppressing lithium dendrites, which have greatly hindered the practical application of solid-state ...lithium-metal batteries. Here, we report a novel laponite sheet (LS) with a large negatively charged surface as an additive in a solid composite electrolyte (poly(ethylene oxide)-LS) to rearrange the lithium-ion environment and enhance the mechanical strength of the electrolytes (PEO-LS). The strong electrostatic regulation of laponite sheets assists the dissociation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and constructs multiple transport channels for free lithium ions, achieving a high ionic conductivity of 1.1 × 10–3 S cm–1 at 60 °C. Furthermore, LS facilitates the in situ formation of a LiF-rich interface because of the boosting TFSI– anion concentration, which significantly suppresses lithium dendrites and prevents short circuit. As a result, the assembled LiFePO4|PEO-LS|Li battery demonstrates a long cycle life of over 800 cycles and a high Coulombic efficiency of 99.9% at 1C and 60 °C. When paired with a high-voltage NCM811 cathode, the battery also demonstrates excellent cycling stability and rate capability.
Poly(amino acid)-type macromolecules (PAAs), poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAAs), and poly(ethylene glycol)-b-poly(glutamic acid) (PEG-PGAs) were synthesized, and their states in ...aqueous solutions were studied. PEG-PAAs and PEG-PGAs were first used as novel polycarboxylate superplasticizers, and their dispersion and adsorption behaviors were investigated in cement slurries in the absence and presence of montmorillonite (MMT) clay. The results demonstrated that both PEG-PAAs and PEG-PGAs not only showed excellent water reducing and fluidity retention capabilities but also exhibited remarkable MMT clay tolerance. In contrast to the stretched molecular conformation of traditional polycarboxylate superplasticizers (PCEs), the hydrophobic main chain and the side methylene and ethylene linkers connected to the carboxylic groups of PAA and PGA segments resulted in self-assembly of the PEG-PAAs and PEG-PGAs in aqueous solutions, and the self-assembled nanosized aggregates exhibited relatively uniform spherical morphologies with average sizes of 30–100 nm. Carboxylic groups located on the periphery of the nanoaggregates acted as anchors and adsorbed on the surfaces of the cement particles. The nanoaggregates and the stretched hydrophilic PEG side chains, which jointly produced and enhanced the steric hindrance to prevent cement particle aggregation and hydration, resulted in notable dispersion capabilities. Total organic carbon (TOC), X-ray diffraction (XRD), and thermogravimetry–differential scanning calorimetry (TG-DSC) analyses revealed that the adsorption between the MMT clay and PAA nanoaggregates was surface adsorption (rather than interlayer adsorption), and this significant finding could be ascribed to the enlarged steric hindrance of the PAA nanoaggregates, which prevented the interlamination adsorption consumption of MMT clay to PAAs and revealed the outstanding clay insensitivity. This study provides a new perspective and strategy to design novel poly(amino acid)-type superplasticizers (PAAs) with excellent dispersion performances and improved clay tolerance.
Display omitted
•Poly(amino acid)-type superplasticizers (PAAs) with enhanced dispersing performance for cement doped with clay impurities.•The self-assembled nanoaggregates of PAAs enhanced steric hindrance and resulted in notable dispersion capabilities.•The enlarged steric hindrance of PAAs prevented interlamination adsorption and revealed outstanding clay insensitivity.
The Nb-doped Li-rich materials Li1.2(Mn0.54Ni0.13Co0.13)1-xNbxO2 are synthesized via a modified one-step sol–gel and high-temperature calcination method. The crystal structure and surface morphology ...of synthesized materials are analyzed through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. After optimization, the Nb-0.02 sample exhibits exceptional electrochemical performance, that is, the initial discharge-specific capacity of 305.9 mAh g−1 at 0.08 C and 202.6 mAh g−1 at 1 C, respectively. Combined with the result of the density of states (DOS), we found that the doping of Nb5+ into the crystal structure significantly reduces the value of the band gap of the Li2MnO3 (1.07 eV). At the same time, the strengthened Nb–O bond and Nb5+ with big ionic radius, regulate the degree of oxygen ion participation in the redox reaction and enhance the electrochemical performance of the Li-rich materials.
●A series of Li-rich materials with different lithium deficiencies is synthesized.●Li-rich material with moderate lithium deficiencies has a positive influence on the electrochemical performance.●The ...L1.1 sample, written as Li1.1Mn0.54Co0.13Ni0.13O2, presents some distorted lattice fringes.●The L1.1 sample displays superior rate capability.
A series of Li-rich materials with lithium deficiencies are obtained by a mild sol-gel and high-temperature calcination method. We use conventional test methods, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, to analyze the crystal structure and morphology of as-prepared materials. The results show that the Li1.1Mn0.54Co0.13Ni0.13O2 (named L1.1) displays superior electrochemical performance, that is, the discharge capacities are 303.9 and 145 mAh g−1 at rate of 0.1 C and 5 C, respectively. The excellent rate capability is mainly attributed to the formation of lithium vacancy and the formation of distorted lattice fringes, which enlarged the Li slab and changed the local structures in the L1.1 material.
Solid‐state electrolytes paired with lithium‐metal anodes is considered a next‐generation energy storage technology. However, the slow ionic transportation of the solid‐state electrolyte and the ...instability against the lithium‐metal anode impede their practical application. Here a cellulose separator modified with highly uniform boric oxide solid acid, contributing to a high transference number (0.75) and good ionic conductivity of 0.52 mS cm−1 due to the strengthened binding of the salt anions with this solid acid, is reported. Moreover, the boron ions with occupied interstitial sites can release free electrons to regulate the electrochemical dynamics of the electrolyte, in situ inducing the formation of Li2CO3/LiF‐rich heterostructured solid electrolyte interphase layer. The cellulose/B2O3‐based composite electrolyte paired with LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode and Li‐metal anode displays a specific capacity of 155 mAh g−1 with a capacity retention of 92% in 200 cycles. Additionally, this electrolyte paired with high‐mass‐loading NCM622 cathode (10 mg cm−2) in a pouch cell can be stably operated for 50 cycles with a capacity retention of over 90%.
Boron ions with occupied interstitial sites can release free electrons, which enhance the electrochemical dynamics of electrolyte to get an in situ formation of Li2CO3/LiF‐rich heterostructured solid electrolyte interphase layer. Boric oxide with high acidity is supposed to bind with anions in the electrolyte, tuning the dissociation of lithium salt to improve the lithium‐ion transport.
Autophagy is essential for nutrient recycling and intracellular housekeeping in plants by removing unwanted cytoplasmic constituents, aggregated polypeptides, and damaged organelles. The ...autophagy-related (ATG)1-ATG13 kinase complex is an upstream regulator that integrates metabolic and environmental cues into a coherent autophagic response directed by other ATG components. Our recent studies with Arabidopsis thaliana revealed that ATG11, an accessory protein of the ATG1-ATG13 complex, acts as a scaffold that connects the complex to autophagic membranes. We showed that ATG11 encourages proper behavior of the ATG1-ATG13 complex and faithful delivery of autophagic vesicles to the vacuole, likely through its interaction with ATG8. In addition, we demonstrated that Arabidopsis mitochondria are degraded during senescence via an autophagic route that requires ATG11 and other ATG components. Together, ATG11 appears to be an important modulator of the ATG1-ATG13 complex and a multifunctional scaffold required for bulk autophagy and the selective clearance of mitochondria.
Purpose This paper aims to study the tribological characteristics of the electrical contact system under different displacement amplitudes. Design/methodology/approach First, the risk frequency of ...real nuclear safety distributed control system (DCS) equipment is evaluated. Subsequently, a reciprocating friction test device which is characterized by a ball-on-flat configuration is established, and a series of current-carrying tribological tests are carried out at this risk frequency. Findings At risk frequency and larger displacement amplitude, the friction coefficient visibly rises. The reliability of the electrical contact system declines as amplitude increases. The wear morphology analysis shows that the wear rate increases significantly and the degree of interface wear intensifies at a larger amplitude. The wear area occupied by the third body layer increases sharply, and the appearance of plateaus on the surface leads to the increase of friction coefficient and contact resistance. EDS analysis suggests that oxygen elements progressively arise in the third layer as a result of increased air exposure brought on by larger displacement amplitude. Originality/value Results are significant for recognizing the tribological properties of electrical connectors in nuclear power control systems. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0098/
The purpose of this study is to investigate the effect of normal load, electric current and sliding speed on tribological performance of electrical contact interface. Sliding electrical contact tests ...of H65 material are carried out by using a customized ball-on-flat tribometer. Results show that with the increase of normal load, both the friction coefficient and contact voltage drop show a downward trend. Too low or too high load will not cause the generation of friction-induce vibration (FIV). Although increasing the normal load appropriately can improve the wear behavior of the interface, it will intensify wear if the normal load is overly high. Larger electric current will increase the friction coefficient, contact voltage drop and surface temperature, but reduce the contact resistance. A certain value of electric current will cause the generation of FIV. Larger electric current will destroy the surface lubricating film of interface and intensify wear. With the increase of sliding speed, the friction coefficient firstly increases and then decreases, while the contact voltage drop shows the opposite trend. Strong FIV will be generated at a certain value of sliding speed. Larger sliding speed will cause the formation of a dense film layer, which plays a good lubrication effect.
•The electrical sliding tribological properties of H65 material are studied.•Effect of normal load, electric current and speed are studied systematically.•Friction-induced vibration during sliding electrical contact is analyzed.•Different wear mechanisms for electrical sliding wear of H65 are presented.
PDF
