How relationship-maintenance strategies influence athlete burnout: Mediating roles of coach-athlete relationship and basic psychological needs satisfaction.

Introduction: Athlete burnout has many potential negative effects on athletes' sporting performance and careers. Maintaining and promoting the coach-athlete relationship to meet athletes' basic psychological needs is one way to reduce burnout. Existing studies of the correlation between coach-athlete relationships and athlete burnout have mainly focused on the coaches' leadership style, with little attention given to relationship-maintenance strategies and the mechanism of athlete burnout from the athletes' perspective. Methods: Using an online survey of 256 adolescent athletes, we explore the relationship between relationship-maintenance strategies and athlete burnout, including the potential mediating effects of the coach-athlete relationship and basic psychological needs satisfaction. Results: (1) Athletes' relationship-maintenance strategies negatively predicted athlete burnout. (2) Besides the direct effect, we found evidence to support three mediation paths: (a) the coach-athlete relationship, (b) basic psychological needs satisfaction, and (c) both as serial mediators. Discussion: These findings enhance understanding of the mechanism of athlete burnout, demonstrating the influence of factors beyond the coach's role. The study also provides a theoretical basis for practical intervention by coaches, athletes, and sports organizations to reduce athlete burnout by focusing on athletes' perspectives.

Associations Between Psychological Profiles and Performance Success Among Professional Taekwondo Athletes in China: A Multidimensional Scaling Profile Analysis.

Sport psychology research has long sought to uncover the determinants of the optimal psychological state for peak performance. Persistent inquiries in this work include whether there is a set of ideal psychological and emotional factors that are required to achieve optimal performance and, if there are, what are they and how are they related to optimal performance. To answer these questions, the current study aimed to identify potential profiles of personality and emotional traits based on a sample of professional Taekwondo athletes from China. In addition, the study also aimed to examine the utility of the profiles in predicting successful athlete performance. Using multidimensional scaling (MDS) profile analysis, two latent profiles of personality and emotional traits were identified that indicate four subtypes of athletes. Regression analyses were conducted to examine how the identified profiles were associated with performance success. The results seemed to suggest that Taekwondo athletes with more performance success were more likely to have a profile of positive personality and emotional traits, while athletes with less performance success were likely to have somewhat elevated levels of self-control, extraversion, and aggression. Knowledge of athletes' personality profiles will help sport psychologists develop suitable interventions to enhance athletes' performance success. In concluding, the results are discussed in the context of athlete psychosocial development. The study added further evidence about the association between psychological and emotional factors and successful Taekwondo athletes.

Ordered mesoporous carbon assisted Fe-N-C for efficient oxygen reduction catalysis in both acidic and alkaline media.

Fe-N-C catalyst obtained by high temperature pyrolysis is one of the most promising electrocatalysts for non-precious metal oxygen reduction reaction (ORR). However, up to now, the lesser density of active sites results in a substantial performance gap between the Fe-N-C materials and the conventional Pt/C ORR catalysts. Herein, an N-doped mesoporous carbon is employed as the support for the dispersion of poly-m-phenylenediamine. With high specific surface areas of 1526 m2 g-1, the as-prepared Fe-N-C materials show the half-wave potential of 0.89 V and 0.79 V in 0.1 M KOH and 0.5 M H2SO4, respectively. Notably, the superior methanol tolerance, as well as excellent stability, makes our Fe-N-C materials as competitive candidates for oxygen electrochemical catalysis.

Mechanistic insights into the SNARE complex disassembly.

NSF (N-ethylmaleimide-sensitive factor) and α-SNAP (α-soluble NSF attachment protein) bind to the SNARE (soluble NSF attachment protein receptor) complex, the minimum machinery to mediate membrane fusion, to form a 20S complex, which disassembles the SNARE complex for reuse. We report the cryo-EM structures of the α-SNAP-SNARE subcomplex and the NSF-D1D2 domain in the 20S complex at 3.9- and 3.7-Å resolutions, respectively. Combined with the biochemical and electrophysiological analyses, we find that α-SNAPs use R116 through electrostatic interactions and L197 through hydrophobic interactions to apply force mainly on two positions of the VAMP protein to execute disassembly process. Furthermore, we define the interaction between the amino terminus of the SNARE helical bundle and the pore loop of the NSF-D1 domain and demonstrate its essential role as a potential anchor for SNARE complex disassembly. Our studies provide a rotation model of α-SNAP-mediated disassembly of the SNARE complex.

Cryo-EM structures of the ATP-bound Vps4E233Q hexamer and its complex with Vta1 at near-atomic resolution.

The cellular ESCRT-III (endosomal sorting complex required for transport-III) and Vps4 (vacuolar protein sorting 4) comprise a common machinery that mediates a variety of membrane remodelling events. Vps4 is essential for the machinery function by using the energy from ATP hydrolysis to disassemble the ESCRT-III polymer into individual proteins. Here, we report the structures of the ATP-bound Vps4E233Q hexamer and its complex with the cofactor Vta1 (vps twenty associated 1) at resolutions of 3.9 and 4.2 Å, respectively, determined by electron cryo-microscopy. Six Vps4E233Q subunits in both assemblies exhibit a spiral-shaped ring-like arrangement. Locating at the periphery of the hexameric ring, Vta1 dimer bridges two adjacent Vps4 subunits by two different interaction modes to promote the formation of the active Vps4 hexamer during ESCRT-III filament disassembly. The structural findings, together with the structure-guided biochemical and single-molecule analyses, provide important insights into the process of the ESCRT-III polymer disassembly by Vps4.

Conformational analysis of Epac activation using amide hydrogen/deuterium exchange mass spectrometry.

Exchange proteins directly activated by cAMP (Epac) play important roles in mediating the effects of cAMP through the activation of downstream small GTPases, Rap. To delineate the mechanism of Epac activation, we probed the conformation and structural dynamics of Epac using amide hydrogen/deuterium exchange and structural modeling. Our studies show that cAMP induces significant conformational changes that lead to a spatial rearrangement of the regulatory components of Epac and allows the exposure of the catalytic core for effector binding without imposing significant conformational change on the catalytic core. Homology modeling and comparative structural analyses of the cAMP binding domains of Epac and cAMP-dependent protein kinase (PKA) lead to a model of Epac activation, in which Epac and PKA activation by cAMP employs the same underlying principle, although the detailed structural and conformational changes associated with Epac and PKA activation are significantly different.

Dissecting the mechanism of Epac activation via hydrogen-deuterium exchange FT-IR and structural modeling.

Exchange proteins directly activated by cAMP (Epac) make up a family of cAMP binding domain-containing proteins that play important roles in mediating the effects of cAMP through the activation of downstream small GTPases, Ras-proximate proteins. To delineate the mechanism of Epac activation, we probed the conformation and structural dynamics of Epac using amide hydrogen-deuterium (H-D) exchange coupled with Fourier transform infrared spectroscopy (FT-IR) and structural modeling. Our studies show that unlike that of cAMP-dependent protein kinase (PKA), the classic intracellular cAMP receptor, binding of cAMP to Epac does not induce significant changes in overall secondary structure and structural dynamics, as measured by FT-IR and the rate of H-D exchange, respectively. These results suggest that Epac activation does not involve significant changes in the amount of exposed surface areas as in the case of PKA activation, and conformational changes induced by cAMP in Epac are most likely confined to small local regions. Homology modeling and comparative structural analyses of the CBDs of Epac and PKA lead us to propose a model of Epac activation. On the basis of our model, Epac activation by cAMP employs the same underlying structural principal utilized by PKA, although the detailed structural and conformational changes associated with Epac and PKA activation are significantly different. In addition, we predict that during Epac activation the first beta-strand of the switchboard switches its conformation to a alpha-helix, which folds back to the beta-barrel core of the CBD and interacts directly with cAMP to form the base of the cAMP-binding pocket.