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Ion beam is used to synthesize heteroepitaxial Co(x)Ni(1-x)Si2 layers with good crystalline quality. A ternary silicide layer with an x value of 0.66 exhibits a 11% type B and 89% type A orientation. Transmission electron microscope reveals that the Type B component is found at the interfaces and with a thickness consisting of a few monolayers. The unique distribution of the type B component in the epilayer is attributed to its small strain size, as observed from X-ray diffraction studies.

Focuses on the formation of nickel (Ni)-silicon (Si) layers with good crystalline quality by ion-beam synthesis. Use of Rutherford backscattering spectrometry and transmission electron microscopy; Structural difference between NiSi[sub2] and cobalt-Si; Overview of the x-ray diffraction measurements.

Presents information on a study that formed high-quality ErSi[sub1.7] layers with an abrupt interface, excellent crystallinity, and high thermal stability by ion-beam-synthesis. Experimental procedure; Results and discussion; Conclusion.

Examines the implantation temperature dependent distribution of nickel silicide layers formed by ion implantation in silicon. Formation of precipitates; Evolution of an epitaxial silicide surface layer.

Mental fatigue (MF) and hypoxia impair cognitive performance through changes in brain hemodynamics. We want to elucidate the role of prefrontal cortex (PFC)-oxygenation in MF. Twelve participants (22.9 ± 3.5 years) completed four experimental trials, (1) MF in (normobaric) hypoxia (MF_HYP) (3.800 m; 13.5%O 2 ), (2) MF in normoxia (MF_NOR) (98 m; 21.0%O 2 ), (3) Control task in HYP (CON_HYP), (4) Control in NOR (CON_NOR). Participants performed a 2-back task, Digit Symbol Substitution test and Psychomotor Vigilance task before and after a 60-min Stroop task or an emotionally neutral documentary. Brain oxygenation was measured through functional Near Infrared Spectroscopy. Subjective feelings of MF and physiological measures (heart rate, oxygen saturation, blood glucose and hemoglobin) were recorded. The Stroop task resulted in increased subjective feelings of MF compared to watching the documentary. 2-back accuracy was lower post task compared to pre task in MF_NOR and CON_NOR, while no differences were found in the other cognitive tasks. The fraction of inspired oxygen did not impact feelings of MF. Although performing the Stroop resulted in higher subjective feelings of MF, hypoxia had no effect on the severity of self-reported MF. Additionally, this study could not provide evidence for a role of oxygenation of the PFC in the build-up of MF., (© 2024. The Author(s).)

Purpose: Several mechanisms have been proposed to explain how mental fatigue degrades sport performance. In terms of endurance performance, a role for an increased perceived exertion has been demonstrated. Using electroencephalography and, more specifically, the movement-related cortical potential (MRCP), the present study explored the neural mechanisms that could underlie the mental fatigue-associated increase in perceived exertion., Methods: Fourteen participants (age, 23 ± 2 yr; 5 women, 9 men) performed one familiarization and two experimental trials in a randomized, blinded, crossover study design. Participants had to complete a submaximal leg extension task after a mentally fatiguing task (EXP; individualized 60-min Stroop task) or control task (CON; documentary). The leg extension task consisted of performing 100 extensions at 35% of 1 repetition maximum, during which multiple physiological (heart rate, electroencephalography) and subjective measures (self-reported feeling of mental fatigue, cognitive load, behand motivation, ratings of perceived exertion) were assessed., Results: Self-reported feeling of mental fatigue was higher in EXP (72 ± 18) compared with CON (37 ± 17; P < 0.001). A significant decrease in flanker accuracy was detected only in EXP (from 0.96 ± 0.03% to 0.03%; P < 0.05). No significant differences between conditions were found in MRCP characteristics and perceived exertion. Specifically in EXP, alpha wave power increased during the leg extension task ( P < 0.01)., Conclusions: Mental fatigue did not impact the perceived exertion or MRCP characteristics during the leg extension task. This could be related to low perceived exertion and/or the absence of a performance outcome during the leg extension task. The increase in alpha power during the leg extension task in EXP suggests that participants may engage a focused internal attention mechanism to maintain performance and mitigate feelings of fatigue., (Copyright © 2023 by the American College of Sports Medicine.)

Mental fatigue (MF) is a psychobiological state negatively impacting both cognitive and physical performance. Although recent research implies that some table tennis (TT) performance outcomes are impaired by MF, open skill sports such as TT require a more detailed overview of MF-related performance decrements. Moreover, research into MF and sport-specific psychomotor performance lacks the inclusion of brain-related measurements to identify MF mechanisms. Eleven experienced TT players participated in this randomized counterbalanced crossover trial. Participants were either required to perform an individualized Stroop task (MF condition) or watch a documentary (control condition). The primary outcomes were reaction time on a sport-specific visuomotor task and EEG activity throughout the trial. The subjective feeling of MF was significantly different between both conditions and confirmed that the MF condition induced the mentally fatigue state of participants ( p < 0.001), though no behavioral indicators (i.e., decrease in performance on Stroop and flanker task) of MF. MF worsened reaction time on the visuomotor task, while other secondary measurements remained largely ambiguous. Spectral power (i.e., decreases in upper α band and θ band) was influenced by MF, while ERPs measured during the visuomotor task remained unaltered. The present study confirms that MF negatively impacts table tennis performance, specifically inhibitory stimuli during the visuomotor task. These findings also further augment our understanding of the effects of MF on human performance.

Introduction: A myriad of factors underlie pacing-/exhaustion-decisions that are made during whole-body endurance performance. The prefrontal cortex (PFC) is a brain region that is crucial for decision-making, planning, and attention. PFC oxygenation seems to be a mediating factor of performance decisions during endurance performance. Nowadays, there is no general overview summarizing the current knowledge on how PFC oxygenation evolves during whole-body endurance performance and whether this is a determining factor. Methods: Three electronic databases were searched for studies related to the assessment of PFC oxygenation, through near-IR spectroscopy (NIRS), during endurance exercise. To express PFC oxygenation, oxygenated (HbO 2 ) and deoxygenated hemoglobin (HHb) concentrations were the primary outcome measures. Results: Twenty-eight articles were included. Ten articles focused on assessing prefrontal oxygenation through a maximal incremental test (MIT) and 18 focused on using endurance tasks at workloads ranging from low intensity to supramaximal intensity. In four MIT studies measuring HbO 2 , an increase of HbO 2 was noticed at the respiratory compensation point (RCP), after which it decreased. HbO 2 reached a steady state in the four studies and increased in one study until exhaustion. All studies found a decrease or steady state in HHb from the start until RCP and an increase to exhaustion. In regard to (non-incremental) endurance tasks, a general increase in PFC oxygenation was found while achieving a steady state at vigorous intensities. PCF deoxygenation was evident for near-to-maximal intensities at which an increase in oxygenation and the maintenance of a steady state could not be retained. Discussion/Conclusion : MIT studies show the presence of a cerebral oxygenation threshold (ThCox) at RCP. PFC oxygenation increases until the RCP threshold, thereafter, a steady state is reached and HbO 2 declines. This study shows that the results obtained from MIT are transferable to non-incremental endurance exercise. HbO 2 increases during low-intensity and moderate-intensity until vigorous-intensity exercise, and it reaches a steady state in vigorous-intensity exercise. Furthermore, ThCox can be found between vigorous and near-maximal intensities. During endurance exercise at near-maximal intensities, PFC oxygenation increases until the value exceeding this threshold, resulting in a decrease in PFC oxygenation. Future research should aim at maintaining and improving PFC oxygenation to help in improving endurance performance and to examine whether PFC oxygenation has a role in other performance-limiting factors., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 De Wachter, Proost, Habay, Verstraelen, Díaz-García, Hurst, Meeusen, Van Cutsem and Roelands.)

Objective: The reactive balance test (RBT) is a recently developed neurocognitive balance test. The aim of this study was to determine test-retest, intra- and inter-rater reliability of the RBT in healthy recreational athletes., Design: Reliability study design., Setting: Primary., Participants: Twenty-one volunteers (age = 22 ± 1 years, height = 175 ± 9 cm, weight = 69 ± 7 kg) participated., Interventions: The two experimental trials were separated by an average of 33 ± 15 days. During experimental trials participants performed the Y-balance test (to determine maximal reach distances), and RBT once., Main Outcome Measures: Visuomotor response time and accuracy. Test-retest, intra- and inter-rater reliability were estimated for both these RBT outcome measures., Results: Excellent intra- and inter-rater reliability was observed for visuomotor response time and accuracy. Test-retest reliability for visuomotor response time was considered good, while moderate test-retest reliability was found for accuracy., Conclusions: Our results indicate that overall test-retest, intra- and inter-rater reliability of the RBT was moderate to excellent. Thus, the RBT possesses acceptable reliability to use in group level analyses. Future research should further determine the clinimetric properties of the RBT in specific populations and research the RBT along the sport injury continuum., Competing Interests: Declaration of competing interest The authors declare to not have any conflicts of interest or to have received any external source of funding for this study., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In 40 patients undergoing arthroscopic subacromial decompression, we monitored the soft tissue pressure in the paratracheal region and in the deltoid and supraspinatus muscles, looking for evidence of a potentially dangerous rise in pressure, especially in the paratracheal region. Statistical analysis was used to determine predictable variables of the time of reaching maximum pressure in and between the three regions. Deltoid pressure rose quickly during surgery, and did not drop to baseline levels at the end of surgery. Supraspinatus pressures showed a similar trend but with lower maximum levels of pressure rise. Five patients had an (unexpected) rise in paratracheal pressure, with an absolute maximum of 133.4 mmHg in one. In only two patients, did "10 minutes post-op" paratracheal pressure levels not drop to baseline levels. No respiratory problems occurred during any procedure. There are no variables to predict a potentially dangerous rise in surrounding soft tissue pressure during shoulder arthroscopy. We recommend endotracheal intubation during shoulder arthroscopy.