Cycling Time Research Articles

A self-paced 15-minute cycling time trial is a reliable performance measure in recreationally active individuals

ABSTRACT Cycling time trial (TT) protocols have been shown to be reliable in trained cyclists, but their reproducibility in lesser-trained individuals is unknown. This study examined the reliability of a self-paced 15-minute cycling TT in recreationally active individuals. Twelve recreationally active males (age 27 ± 3 y; body mass 75.2 ± 8.9 kg; V ˙ O2peak = 51.10 ± 7.53 ml∙kg∙min−1) completed a V ˙ O2peak test and four experimental trials, separated by > 48 h. Experimental trials consisted of 10 min cycling at 60% Wmax, followed by a self-paced 15-min TT. Heart rate and work done were recorded every 5 min during the TT; and coefficient of variation (CV) was calculated. Work done was not different (P = 0.706) between trials (193.2 ± 45.3 kJ; 193.2 ± 43.5 kJ; 192.0 ± 42.3 kJ; 193.9 ± 42.8 kJ). Within participant CV ranged from 0.5–4.9% for the four TTs, with a mean CV of 2.1%. Mean CV decreased from 2.0% (range 0.1–5.0%) for the first two TTs to 1.7% (range 0.2–5.6%) for the second and third TTs, and further decreased to 1.0% (range 0.2–1.8%) for the third and fourth TTs. In conclusion, the use of a short-duration self-paced cycling TT in recreationally active individuals is a reliable performance measure.

Taguchi Optimization of Electrolytic Plasma Hardening Process Parameters on Ti‐6Al‐4V Alloy: Microstructure and Mechanical Properties

Herein, the effects of electrolytic plasma treatment (EPT) on the hardness distribution, wear resistance, and surface morphologies of titanium alloy (Ti‐6Al‐4V) at three different thermal cycles (4‐5‐6 times) are investigated. The microstructure is controlled by heat temperature and modification times of thermal cycles depending on EPT processing parameters. A novel technique to modify Ti‐6Al‐4V alloy by the process of EPT successfully occurs. The results show that the phase transformation is shown as follows: fine α and β for the low thermal cycle → irregular martensite α′ for the high thermal cycle → complete zigzag martensite α′ for the max thermal cycle. The hardness is increased from 350 ± 10HV0.05 to 530 ± 10HV0.05 after the modification. Wear tests are conducted according to the Taguchi L9 (3^3) orthogonal array. Three parameters (load, sliding speed, and sample type) with three levels examine wear rate and coefficient of friction. Optimum levels are obtained by Taguchi analysis from the experimental results. In addition, an analysis of variance is performed to find the effectiveness of the parameters. The wear surfaces are analyzed by scanning electron microscope. After the analysis, the best result is obtained in five thermal cycles.

Shrinkage Characteristics and Microstructure Evolution of Yili Loess under Different Wetting and Drying Cycles

The loess in Yili Valley is prone to landslides in the rainy season. We studied the influence law of shrinkage and the microstructure of the loess in Yili Valley under different wetting and drying cycles. Considering the climatic conditions and sampling depth of the study area, shrinkage tests were carried out under six kinds of dry and wet cycling paths. The fracture changes and shrinkage characteristics of the loess under different dry–wet cycling times were analyzed, and the deformation characteristics of the loess during the process of water-loss shrinkage under the dry–wet cycling conditions were discussed. The results show that (1) there is an exponential relationship between the number of dry and wet cycles and the final shrinkage rate. The influence of dry and wet cycles on the final shrinkage rate is significant in the early stage. (2) With the increase in the number of dry and wet cycles, the decline in the final shrinkage rate decreases, and the final shrinkage rate and shrinkage coefficient of soil also show a decreasing trend, while the soil sample area first increases and then gradually decreases, and the surface shrinkage cracking is gradually stable. The surface porosity tends to increase. (3) Under the action of repeated wet expansion and dry contraction, irregular cracks are produced inside the soil body, which leads to the increase in soil permeability, reduces the strength of the soil body, reflects the phenomenon of strength deterioration, and thus indicates the stability of loess slopes. The research results of this paper can provide an important parameter basis for the prevention and control of loess landslide geological disasters in Yili Valley.

Photothermal cyclic self-healing coating with long-term corrosion protection based on bifunctional graphene

The intrinsic repair ability is a new strategy to prolong the protection life of damaged coatings, but how to maintain long-term corrosion protection during repeated healing remains a challenge. Herein, a self-healing, weather-resistant polyurethane coating with long-term stable corrosion protection enhanced by dopamine-coated graphene oxide (GP) fillers was developed. The formation of hydrogen bond between GP and the amino group in the polyurethane chain enhances the interfacial compatibility of the filler in the coating, thus improves the photothermal, thermal conductivity and barrier properties of the coating. The coating maintains excellent corrosion protection properties after 7 times of scratch-healing cycles, and can withstand up to 15 days of immersion after scratch-healing. The water evaporation rate and deicing rate of the coating are respectively up to 5.57 and 4965.5 kg/(m2·h), achieving a highly photothermal conversion efficiency. In addition, molecular dynamics simulation demonstrates that the hydrogen bonds between GP and polyurethane chains is the key factor for the excellent corrosion protection of the coating. This study opens a new avenue for improving the service life of self-healing coatings in atmospheric environment.

Sodium Bicarbonate Ingestion in a Fasted State Improves 16.1-km Cycling Time-Trial Performance.

The use of sodium bicarbonate (SB) as a preexercise ergogenic aid has been extensively studied in short-duration high-intensity exercise. Very few studies have considered the effects of SB ingestion before prolonged high-intensity exercise. The aim of the present study was to determine the effects of a 0.3 g·kg -1 body mass dose of SB ingested before the start of a 16.1-km cycling time trial in cyclists. Ten trained male cyclists (age, 31.1 ± 9 yr; height, 1.84 ± 0.05 m; body mass, 82.8 ± 8.5 kg; and V̇O 2peak , 60.4 ± 3.1 mL·kg -1 ·min -1 ) completed this study. Participants ingested 0.3 g·kg -1 in gelatine (SB-G) and enteric capsules (SB-E) 1 wk apart to determine individualized time-to-peak alkalosis for each ingestion form. Using a randomized crossover design, participants then performed simulated 16.1-km time trials after ingestion of SB-G, SB-E, or a placebo. There were significant differences in performance between the SB and placebo ingestion strategies ( f = 5.50, P = 0.014, p η2 = 0.38). Performance time was significantly improved by SB ingestion (mean improvement: 34.4 ± 42.6 s ( P = 0.031) and 40.4 ± 45.5 s ( P = 0.020) for SB-G and SB-E, respectively) compared with the placebo. Gastrointestinal symptoms were lower after SB-E compared with SB-G (36.3 ± 4.5 vs 5.6 ± 3.1 AU, P < 0.001, g = 7.09). This study demonstrates that increased buffering capacity after acute preexercise SB ingestion can improve endurance cycling time-trial performances. The use of SB could be considered for use in 16.1-km cycling time trials, but further work is required to establish these effects after a preexercise meal.

Exercise-induced myocardial T1 increase and right ventricular dysfunction in recreational cyclists: a CMR study

PurposeAlthough cardiac troponin I (cTnI) increase following strenuous exercise has been observed, the development of exercise-induced myocardial edema remains unclear. Cardiac magnetic resonance (CMR) native T1/T2 mapping is sensitive to the pathological increase of myocardial water content. Therefore, we evaluated exercise-induced acute myocardial changes in recreational cyclists by incorporating biomarkers, echocardiography and CMR.MethodsNineteen male recreational participants (age: 48 ± 5 years) cycled the ‘L’étape du tour de France” (EDT) 2021’ (175 km, 3600 altimeters). One week before the race, a maximal graded cycling test was conducted to determine individual heart rate (HR) training zones. One day before and 3–6 h post-exercise 3 T CMR and echocardiography were performed to assess myocardial native T1/T2 relaxation times and cardiac function, and blood samples were collected. All participants were asked to cycle 2 h around their anaerobic gas exchange threshold (HR zone 4).ResultsEighteen participants completed the EDT stage in 537 ± 58 min, including 154 ± 61 min of cycling time in HR zone 4. Post-race right ventricular (RV) dysfunction with reduced strain and increased volumes (p < 0.05) and borderline significant left ventricular global longitudinal strain reduction (p = 0.05) were observed. Post-exercise cTnI (0.75 ± 5.1 ng/l to 69.9 ± 41.6 ng/l; p < 0.001) and T1 relaxation times (1133 ± 48 ms to 1182 ± 46 ms, p < 0.001) increased significantly with no significant change in T2 (p = 0.474). cTnI release correlated with increase in T1 relaxation time (p = 0.002; r = 0.703), post-race RV dysfunction (p < 0.05; r = 0.562) and longer cycling in HR zone 4 (p < 0.05; r = 0.607).ConclusionStrenuous exercise causes early post-race cTnI increase, increased T1 relaxation time and RV dysfunction in recreational cyclists, which showed interdependent correlation. The long-term clinical significance of these changes needs further investigation.Trial registration numbers and dateNCT 04940650 06/18/2021. NCT 05138003 06/18/2021.

A Trojan-Horse-Like Biomimetic Nano-NK to Elicit an Immunostimulatory Tumor Microenvironment for Enhanced GBM Chemo-Immunotherapy.

Although the chemo- and immuno-therapies have obtained good responses for several solid tumors, including those with brain metastasis, their clinical efficacy in glioblastoma (GBM) is disappointing. The lack of safe and effective delivery systems across the blood-brain barrier (BBB) and the immunosuppressive tumor microenvironment (TME) are two main hurdles for GBM therapy. Herein, a Trojan-horse-like nanoparticle system is designed, which encapsulates biocompatible PLGA-coated temozolomide (TMZ) and IL-15 nanoparticles (NPs) with cRGD-decorated NK cell membrane (R-NKm@NP), to elicit the immunostimulatory TME for GBM chemo-immunotherapy. Taking advantage of the outer NK cell membrane cooperating with cRGD, the R-NKm@NPs effectively traversed across the BBB and targeted GBM. In addition, the R-NKm@NPs exhibited good antitumor ability and prolonged the median survival of GBM-bearing mice. Notably, after R-NKm@NPs treatment, the locally released TMZ and IL-15 synergistically stimulated the proliferation and activation of NK cells, leading to the maturation of dendritic cells and infiltration of CD8+ cytotoxic T cells, eliciting an immunostimulatory TME. Lastly, the R-NKm@NPs not only effectively prolonged the metabolic cycling time of the drugs in vivo, but also has no noticeable side effects. This study may offer valuable insights for developing biomimetic nanoparticles to potentiate GBM chemo- and immuno-therapies in the future.

Form‐stable phase change materials supported by nanostructured zinc polyacrylate weakening super cooling of polyethylene glycol

AbstractIn order to solve the leakage and distinct super cooling issues of polyethylene glycol (PEG), zinc polyacrylate was used as the supporting material to prepare PEG‐based form‐stable phase change materials (FSPCMs) in this paper. The polyacrylate fractions of zinc polyacrylate are crosslinked by zinc ions through electrovalent bonding. Due to the strong intermolecular force between PEG molecules and the crosslinked polyacrylate fractions, the PCMs have stabilized shape even at 90°C. Zinc ions will gather together because of the incompatibility between PEG matrix and zinc ions, to form nanostructure as the nucleating agent of PEG, weakening the supercooling of the FSPCMs. The enthalpy change values of the FSPCMs in the phase transition processes are all above 120.0 J g−1, showing good thermal energy storage capacity. Additionally, the FSPCMs after 100 times of thermal cycling possess similar thermal properties to the original ones, indicating that the nanostructured zinc polyacrylate has stable interaction with the PEG matrix.

Serum brain-derived neurotrophic factor (BDNF) and self-paced time-trial performance in older untrained men.

This study examined the effect of 12 weeks of concurrent aerobic and resistance training on brain derived neurotrophic factor (BDNF) levels, neuromuscular performance and cerebral oxygenation on self-paced cycling exercise in previously untrained older men. Eight untrained healthy males aged 53-64 years performed a familiarisation and a pre-training self-paced cycling time trial before 12 weeks of exercise training which combined aerobic and resistance exercise. The self-paced cycling time trial comprised a 30 s maximal effort sprint for every 4.5 min of lower intensity pace for a total of 25 min. Upon completion of 12 weeks of training, a comparison of the pre-training trial analysed for serum BDNF, neuromuscular performance, and cerebral oxygenation was undertaken. Serum BDNF decreased significantly from 10.02 ± 4.63 to 6.96 ± 3.56 ng/ml after 12 weeks of training. There was also attenuated physiological strain for a comparable self-paced cycling performance. Despite positive physiological responses during the time trial pacing strategy was not altered compared with pre training. BDNF decreases following 12 weeks of concurrent training and might reflect neuroplasticity for this type of training stimulus. Exercise training in previously sedentary older men can result in a multitude of physical benefits, which may also confer a neuroprotective effect. However, specific training is required to improve pacing strategies in previously untrained older males. Australian New Zealand Clinical Trials Registry number ACTRN12622001477718.

Head-to-head opponent mitigates mental fatigue effects during a 20-km time trial in well-trained cyclists.

We aimed to analyze the effect of a head-to-head virtual race on 20-km time trial performance in well-trained mentally fatigued cyclists. A total of 24 male professional cyclists participated in the present study, which was conducted in a within-factors design [four experimental conditions × four times (throughout 20-km time trial cycling)]. An avatar representing the participant on the racecourse was visible during the time trials. Then, a second virtual avatar representing the opponent was projected onto the screen in the mental fatigue head-to-head and control head-to-head experimental conditions. Measurements [rating of perceived exertion, heart rate, and eye-tracking measures (i.e., pupil diameter)] were performed every 5-km throughout the 20-km time trial. As a result, impaired total time, power output, and cadence throughout the 20-km cycling time trial were found for mental fatigue compared to mental fatigue head-to-head, control head-to-head, and control conditions (p < 0.05). Also, impaired 20-km time trial performance (total time, power output, and cadence) was found for mental fatigue head-to-head compared to control head-to-head (p < 0.05). Moreover, lower RPE was found for the control and control head-to-head conditions than mental fatigue head-to-head and mental fatigue experimental conditions (p < 0.05). Higher pupil diameter was also found for mental fatigue head-to-head, control head-to-head, and control than the mental fatigue experimental condition (p < 0.05). In summary, the overall performance throughout the 20-km cycling time trial was improved by the presence of a virtual opponent for the mentally fatigued cyclists.

Acute Ketone Monoester Supplementation Impairs 20-min Time-Trial Performance in Trained Cyclists: A Randomized, Crossover Trial.

Acute ketone monoester (KE) supplementation can alter exercise responses, but the performance effect is unclear. The limited and equivocal data to date are likely related to factors including the KE dose, test conditions, and caliber of athletes studied. We tested the hypothesis that mean power output during a 20-min cycling time trial (TT) would be different after KE ingestion compared to a placebo (PL). A sample size of 22 was estimated to provide 80% power to detect an effect size dz of 0.63 at an alpha level of .05 with a two-tailed paired t test. This determination considered 2.0% as the minimal important difference in performance. Twenty-three trained cyclists (N = 23; peak oxygen uptake: 65 ± 12ml·kg-1 min-1; M ± SD), who were regularly cycling >5hr/week, completed a familiarization trial followed by two experimental trials. Participants self-selected and replicated their diet and exercise for ∼24hr before each trial. Participants ingested either 0.35g/kg body mass of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate KE or a flavor-matched PL 30min before exercise in a randomized, triple-blind, crossover manner. Exercise involved a 15-min warm-up followed by the 20-min TT on a cycle ergometer. The only feedback provided was time elapsed. Preexercise venous [β-hydroxybutyrate] was higher after KE versus PL (2.0 ± 0.6 vs. 0.2 ± 0.1mM, p < .0001). Mean TT power output was 2.4% (0.6% to 4.1%; mean [95% confidence interval]) lower after KE versus PL (255 ± 54 vs. 261 ± 54W, p < .01; dz = 0.60). The mechanistic basis for the impaired TT performance after KE ingestion under the present study conditions remains to be determined.

Increasing melting and solidification performances of a phase change material-based flat plate solar collector equipped with metal foams, nanoparticles, and wavy wall-Y-shaped surface

This paper presents solutions to improve the thermal performances of paraffin as a Phase Change Material (PCM) in solar flat-plate collector systems for domestic and industrial solar applications. These solutions are regarded as an effective way to solve the problem of energy supply and demand time delay. To address this issue, three different methods were proposed together or separately, namely using 10 PPIs aluminum foams with 0.92 or 0.95 porosity, various types of 5%wt nanoparticles, and modifications to the geometry in three different configurations: straight (Case A), wavy wall (Case B), and wavy wall-Y-shaped fin combinations (Case C). Because of melting, thermal energy is stored within the PCM during sun exposition; once the sun source is not available, thanks to the PCM solidification, thermal energy is released. Numerical predictions of phase change and temperature evolution are done – and extensively validated - by means of well-established approaches like enthalpy-porosity method, porous media approach, and nanoparticles single-phase homogeneous model. If comparisons are done with pure paraffin, it has been found that nano-powders in Case B and Case C reduce melting time by 18.15% and 40.70%, respectively. A reduction of 86.19% and 87.21% can be found if only metal foams, or nanoparticles with foams, are included. Furthermore, solidification time for Case C with nanoparticles and 0.95 or 0.92 porosity foams, in comparison with Case B-Pure paraffin, becomes lower of 84.49% and 89.18%, respectively. This suggests that metal foams play the most important role in improving cycling times in such applications, even if nanoparticles and wavy walls are helpful too. The heat storage rate has been found to be higher of an order of magnitude if both metal foam and nanoparticles are added to the paraffin in Case C.

PEO-based solid-state electrolyte modified by cationic covalent organic frameworks enabling high-performance all-solid-state Li metal and graphite anode batteries

Covalent organic frameworks (COFs) with regular and ordered channels have been proved that they could offer extra space to accommodate ions and fast conduction pathways for ion motion. However, the ion conductivities of their own are not high because of most of them have no enough active segmental motion of polymer chains for ion transport. Polyethylene oxide (PEO) is the most typical and efficient solid-state polymer material for Li+ migration by the segmental motion of molecular chains. Herein, we propose a simple and effective strategy of introducing a small quantity of cationic COF additive EB-COF-TFSI into the PEO of low glass transition temperature to obtain high-performance solid-state electrolyte (SSEs) and Li batteries. The cationic COF structure not only provides fast pathway for Li+ but also these cations on it accelerate Li salt dissociation and Li+ conduction. As a result, the cycling time of Li symmetrical cells increases to triplication at a same test condition; the corresponding all-solid-state LFP and NMC//Li metal cells are stimulated to release higher specific capacities, exhibit an enhanced cycling stability and better rate capability. It is surprising that all-solid-state LFP//graphite cells show excellent charging and discharging performance no matter on longtime cycling or rate performance test which are both much better than that of Li metal cells and provide a great strategy for building commercial all-solid-state Li battery based the current structure of it.

Enhanced removal of methylene blue from wastewater by alginate/carboxymethyl cellulose-melamine sponge composite

Industrial dye wastewater poses a threat to human health due to its harmful effects, and the treatment of related wastewater is receiving increasing attention. In this paper, the melamine sponge with high porosity and convenient separation was selected as matrix material, and alginate/carboxymethyl cellulose-melamine sponge composite (SA/CMC-MeS) was prepared through crosslinking strategy. Not only does the composite cleverly combined the merits of alginate and carboxymethyl cellulose, it also enhanced the adsorption performance for methylene blue (MB). The adsorption data manifested that the adsorption process of SA/CMC-MeS agreed with the Langmuir model and pseudo-second-order kinetic model, and theoretical maximum adsorption capacity was 230 mg/g (pH 8). The characterization results demonstrated that the adsorption mechanism was attributed to the electrostatic attraction between the carboxyl anions on the composite and the dye cations in solution. Importantly, SA/CMC-MeS could selectively separate MB from binary dye system and had positive anti-interference ability in the face of coexisting cations. After 5 times of cycles, the adsorption efficiency remained above 75 %. Based on these outstanding practical properties, this material has a potential to solve dye contamination.

Cycle Numbers of Cell Surface Recycling Receptors

The cycle number (nc) of a recycling receptor is defined as the average number of round trips (cell surface–endosome–cell surface) the receptor can make before it is degraded. This characteristic parameter of recycling receptors can be easily determined from the receptor’s half-life (t½, the time in which 50% of the receptor is degraded) and cycling time (Tc, the time a receptor needs to complete a round trip). Relationship analyses revealed that nc increases linearly with increasing t½ and decreases exponentially with increasing Tc. For commonly observed t½ and Tc values, it was calculated that recycling receptors have nc values of &lt;300. In addition, it was found that recycling receptors in cancer cells have generally smaller nc values (&lt;100), whereas recycling receptors in normal cells have larger nc values (&gt;100). Based on this latter finding, the cycle number nc may be a useful criterion for distinguishing between cancer and normal cells.

One step synthesis of novel CuS-ZnS/SiO2@n-octadecane nanocapsules with full spectral absorption range and high photothermal conversion efficiency

In this manuscript, CuS-ZnS/SiO2@n-octadecane nanocapsules were prepared by a simple one-step Cu2+ and Zn2+ co-deposition method. The results of XRD, SEM, TEM, FTIR and XPS show that nanocapsules composed of CuS-ZnS/SiO2 shell and n-octadecane core material were successfully prepared, and the particles deposited was proved to be composite structure of CuS-ZnS. The solution concentration, reaction temperature and pH value have significant effects on the morphology of the nanocapsules prepared. The appropriate conditions are 0.02 mol/L CuSO4, 0.02 mol/L Zn(CH3COO)2, 60 °C, and no additional pH adjustment. Under the optimum conditions, the melting enthalpy reached 45.11 J/g, and after 100 times of cold and hot cycles, the melting enthalpy of the sample only decreased by 3.2%, showing good thermal stability. The CuS-ZnS composite structure makes CuS-ZnS/SiO2 nanocapsules exhibit a wider spectrum absorption performance. The absorption effect of CuS-ZnS/SiO2 nanocapsules to ultraviolet light is significant, compared to the slight reducing of the visible light, while the absorption of near-infrared light is strong. The photothermal conversion efficiency of the samples is significantly improved from 9.7% to 86.6%. Hence, the prepared nanocapsules achieve full spectral absorption, which has a broad application prospect in solar thermal utilization.

Experimental study on frost resistance of hybrid fiber fly ash concrete

Based on the orthogonal test, the optimized ratio of hybrid fiber fly ash concrete prepared with different volume admixtures of polypropylene fiber and polyacrylonitrile fiber, and different lengths, was obtained, and its frost resistance was evaluated in terms of mass change, dynamic elastic modulus, compressive strength, and splitting tensile strength before and after water and salt freezing. Then, the damage mechanism was discussed by combining the pore structure and SEM analysis. The results show that the tensile strength and relative dynamic elastic modulus of specimens after the water freezing cycle are better than those after the salt freezing cycle with the same number of freeze-thaw cycles, and the mass loss rate is less than that of the salt freezing cycle; the compressive strength and the splitting tensile strength of hybrid fiber fly ash concrete increased by 8.5% and 9.5%, and 46.8% and 12.1%, respectively, after 60 times of water freezing and salt freezing cycles compared with the benchmark fly ash concrete. As the number of freeze-thaw cycles increased, the pore air content and the frequency of large pores increased and the frequency of small pores decreased; in terms of the pore distribution of concrete, the distribution of pore structure was more reasonable for water freeze cycle relative to salt freeze cycle and for hybrid fiber fly ash concrete relative to the base fly ash concrete. Thus, it can be found that hybrid fibers incorporated into concrete can reduce the damage to the concrete interior by the freeze-thaw cycle and significantly improve the frost resistance of concrete.

Unraveling the Role of (Meta-) Cognitive Functions in Pacing Behavior Development during Adolescence: Planning, Monitoring, and Adaptation.

This study aimed to investigate whether (meta-) cognitive functions underpin the development of the self-regulated distribution of effort during exercise (i.e., pacing) throughout adolescence. Participants included 18 adolescents (9 girls, 15.6 ± 2.5 yr old) and 26 adults (13 women, 26.8 ± 3.1 yr old), all recreationally active but unfamiliar with time trial cycling. The (meta-) cognitive functions involved in preexercise planning were quantified by calculating the difference between estimated and actual finish time during a 4-km cycling time trial. The capability to monitor and adapt one's effort distribution during exercise was measured during a 7-min submaximal trial, in which the participants were tasked with adhering to a set submaximal goal velocity either with (0-5 min) or without (5-7 min) additional feedback provided by the researcher. Analyses included between-group comparisons (ANOVA) and within-group comparisons (correlation) ( P < 0.05). Adolescents were less accurate in their estimation of the task duration. The adolescents' overestimation of task duration of the 4-km time trial was accompanied by pacing behavior characteristics resembling a longer trial (i.e., more even power output distribution, lower RPE, more pronounced end-spurt). Contrary to the adults, the adolescents deviated relatively more from the goal velocity during the 7-min submaximal trial, when no additional feedback was provided by the researcher. Within the adolescent group, estimation of task duration accuracy ( r = 0.48) and adherence to goal velocity ( r = 0.59) correlated with age. The (meta-) cognitive functions involved in the preexercise planning and the monitoring and adaptation of the distribution of effort during exercise underpin the development of pacing behavior during adolescence. Feedback from the (social) environment can be used to aid the monitoring and adaptation of effort expenditure in adolescents.

Memory Effects in the Nonequilibrium Critical Behavior of the Two-Dimensional XY Model in the Low-Temperature Berezinskii Phase

The Monte Carlo study of nonequilibrium memory effects in the two-dimensional pure and structurally disordered XY model in the low-temperature Berezinskii phase has been performed. Features of the correlation between memory and aging effects have been demonstrated. A qualitatively novel phenomenon for memory effects has been revealed: dynamic curves of the autocorrelation function in the thermal cycling time interval tend to the dynamic curves with the initial temperature. A unique implementation of memory effects has been demonstrated at both cooling and heating cycling of the system under the condition that cooling and heating temperatures are in the low-temperature Berezinskii phase. The influence of structural disorder on memory effects has been analyzed. It has been found that they are enhanced in the structurally disordered system owing to the enhancement of aging effects.

Damage and optimization of program/erase operation in MANOS 3D NAND flash memory

In this work, the damage caused by program/erase (P/E) operation in 3D NAND memory devices made of Metal-Al2O3-Nitride-Oxide-Semiconductor (MANOS) was examined. The damage caused by program and erase operations independently was intended to be identified and realized using several types of cycling stresses. Physical models were discussed to interpret that the anode hole could be responsible for the damage to the Al2O3-Nitride-Oxide (ANO) gate stacks. The tunnel oxide damage was caused by the erase operation and could be enhanced by a higher cycling temperature. This led to a faster program and a slower erase, and it demonstrated a strong correlation with retention and its active energy (Ea). On the other hand, program operation may merely be contributing to block oxide damage, with an invisible impact on erase efficiency and retention but a reduction in program efficiency. An optimized single pulse erase scheme was discussed. Not only can it reduce ANO damage and improve retention, but it can also decrease erase time. Furthermore, a feasible endurance acceleration method was discussed to save a lot of cycling time.