Accelerometer-based and self-reported physical activity of children and adolescents from a seasonal perspective.

Background: Many children and adolescents in Europe are insufficiently physically active, which makes the advancement of children's physical activity a critical health promotion target. However, there are some environmental factors, such as the amount of daylight, weather conditions, temperature, and precipitation levels, which might influence physical activity behavior. The purpose of this study was to assess accelerometer-based and self-reported daily physical activity of children and adolescents in Luxembourg, during autumn/winter as well as during spring/summer, and to examine if there is a seasonal influence on the physical activity behavior. Methods: At two measurements, one in autumn/winter and one in spring/summer, physical activity of N = 137 (59.12% females; M = 12.37 years) participating children and adolescents aged 10-18 years was objectively undertaken via an accelerometer (ActiGraph) and subjectively assessed using, among others, one item of the MoMo physical activity questionnaire. Results: A repeated measures ANOVA revealed a significant seasonal effect on moderate to vigorous physical activity per day [F(1.000, 135.000) = 7.69, p < 0.05, partial η² = 0.054]. More minutes of moderate to vigorous physical activity per day were accrued in spring/summer than in autumn/winter. The mean difference scores between the accelerometer-based and the self-reported physical activity at the two time periods, T1 and T2, correlated significantly (r = 0.31, p < 0.001). Conclusions: According to these results, children and adolescents are less physically active in autumn/winter than in spring/summer. However, the discrepancy between the accelerometer-based and the self-reported physical activity remains stable over the two measurements. Therefore, schools, sports clubs, and communities should offer special physical activity programs for the colder season.

Uncovering the Role of Mindfulness in Autonomous Motivation across Physical Education and Leisure Time: Extending the Trans-Contextual Model.

Mindfulness is assumed to foster the ability to consistently act in line with one's authentic self; a skill which has been found to enhance students' autonomous motivated behavior in the educational context. However, evidence regarding how mindfulness can be integrated into existing conceptual frameworks such as the trans-contextual model is scarce. Therefore, the present study aimed to evaluate the role of mindfulness in students' autonomous motivation in the school and leisure time contexts. Overall, N = 1877 students (M = 14.74 years, SD = 2.63) indicated their self-reported mindfulness, their perceived need for support in physical education, their autonomous motivation during physical education and leisure time, as well as their perceived behavioral control, attitude, subjective norm, and intention toward physical activity. Physical activity was additionally measured physiologically for n = 240 students using accelerometers. Path model analyses revealed that the inclusion of mindfulness substantially improved the trans-contextual model fit. Perceived autonomy support positively predicted mindfulness, which, in turn, predicted autonomous motivation in physical education and leisure time, attitude, subjective norm, and perceived behavioral control. Furthermore, mediation analyses revealed the significant indirect effects of mindfulness on physiological and self-reported physical activity. Based on these results, mindfulness can be considered a key factor in fostering students' motivation to become physically active.

Plasma-Assisted Fabrication of Molecularly Imprinted NiAl-LDH Layer on Ni Nanorod Arrays for Glyphosate Detection.

An inorganic-framework molecularly imprinted NiAl layered double hydroxide (MI-NiAl-LDH) with specific template molecule (glyphosate pesticide, Glyp) recognition ability was prepared on Ni nanorod arrays (Ni NRAs) through electrodeposition followed by a low-temperature O2 plasma treatment. The freestanding Ni/MI-NiAl-LDH NRA electrode had highly enhanced sensitivity and selectivity. The electrocatalytic oxidation of Glyp was proposed to occur at Ni3+ centers in MI-NiAl-LDH, and the current response depended linearly on the Glyp concentration from 10.0 nmol/L to 1.0 µmol/L (R2 = 0.9906), with the limit of detection (LOD) being 3.1 nmol/L (S/N = 3). An exceptional discriminating capability with tolerance for other similar organophosphorus compounds was achieved. Molecular imprinting (N and P residues) affected the electronic structure of NiAl-LDH, triggering the formation of highly active NiOOH sites at relatively lower anodic potentials and substantially enhancing the electrocatalytic oxidation ability of the NiAl-LDH interface toward the C-N bonds in Glyp. In combination with the surface enrichment effect of MI-NiAl-LDH toward template molecules, the electrochemical oxidation signal intensity of Glyp increased significantly, with a greater peak separation from interfering molecules. These results challenge the common belief that the excellent performance of inorganic-framework molecularly imprinted interfaces arises from their specific adsorption of template molecules, providing new insight into the development of high-performance organic-pollutant-sensing electrodes.

Associations between Physical Activity and Mental Health in Iranian Adolescents during the COVID-19 Pandemic: An Accelerometer-Based Study.

Using self-reported questionnaires, several studies found that social isolation during the COVID-19 pandemic has significantly changed the level of physical activity (PA) in children and adolescents. Since the objectivity of self-reported PA is limited in several ways, we used modern accelerometers in this study to assess the PA levels of male and female adolescents during the pandemic-related lockdown. Moreover, the association of PA with mental health of the adolescents were analyzed. A total of 136 students (76 girls, mean age of 16.28 ± 0.97 years) from various schools in Iran wore the accelerometer (ActiGraph GT3X-BT) for seven consecutive days. Mental health was measured through the Depression, Anxiety, Stress Scale-21 of Lovibond and Lovibond (1995). Descriptive statistics and independent t-tests were used to analyze the PA levels of male and female students, and linear regressions were computed to examine whether PA predicts mental health status. On average, the daily time spent in moderate-to-vigorous PA (MVPA) was 18.47 min, which is clearly below the WHO guideline of at least 60 min of MVPA per day. Only 4% of adolescents showed MVPA for more than 30 min per day. Male students were significantly more active than their female peers (p = 0.015). As expected, MVPA was negatively associated with mental health issues such as depression, anxiety, and stress. However, the majority of adolescents reported symptoms of mild-to-moderate mental health disorders. These results emphasize the need for targeted strategies and offerings geared to young people's needs and preferences to promote an adequate level of PA and good mental health during and after the ongoing pandemic.

Electrogravimetry and Structural Properties of Thin Silicon Layers Deposited in Sulfolane and Ionic Liquid Electrolytes.

Potentiostatic deposition of silicon is performed in sulfolane (SL) and ionic liquid (IL) electrolytes. Electrochemical quartz crystal microbalance with damping monitoring (EQCM-D) is used as main analytical tool for the characterization of the reduction process. The apparent molar mass (Mapp) is applied for in situ estimation of the layer contamination. By means of this approach, appropriate electrolyte composition and substrate type are selected to optimize the structural properties of the layers. The application of SL electrolyte results in silicon deposition with higher efficiency compared to the IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMP][TFSI]. This has been associated with the instability of the IL in the presence of silicon tetrachloride and the enhanced incorporation of IL decomposition products into the growing silicon deposit. X-ray photoelectron spectroscopy (XPS) analysis supports the results about the layer composition, as suggested from the microgravimetric experiments. Attention has been given to the impact of practically relevant substrates (i.e., Cu, Ni, and vitreous carbon) on the reduction process. An effective deposition can be carried out on the metal electrodes in both electrolytes due to accelerated reaction kinetics for these types of substrates. However, on vitreous carbon (VC), a successful reduction of SiCl4 can only be accomplished in the IL, while the electroreduction process in SL is dominated by the decomposition of the electrolyte. For short deposition times, the scanning electron microscopy (SEM) images display rough morphologies in the nanometer range, which evolve further to structures with increased length scale of the surface roughness. The development of a rough interface during deposition, resulting in QCM damping at advanced stages of the process, is interpreted by a model accounting for the resistive force caused by the interaction of the liquid with a nonuniform layer interface. By using this approach, the individual contributions of the surface roughness and viscoelastic effects to the measured damping values are estimated.

Does Motivation in Physical Education Have an Impact on Out-of-School Physical Activity over Time? A Longitudinal Approach.

Previous research based on the trans-contextual model proposes that autonomous motivation in physical education (PE) is transferable to an out-of-school leisure-time (LT) context. However, only cross-sectional and unidirectional analyses have been conducted. The present study used a longitudinal design assessing N = 1681 students (M = 14.68 years) on two occasions, measuring the following constructs: perceived need for support in PE, motivational regulation during PE and LT, attitude, subjective norm, perceived behavioral control, intention, and physical activity behavior. Findings based on mixed effect models revealed that autonomy, competence, and relatedness support of the PE teacher were positively related to autonomous motivation. Moreover, similar motivational regulation types were found to significantly cross-lag across contexts. Through longitudinal mediation analyses, further support for the impact of autonomous motivation on physical activity, mediated by intention, attitude, and perceived behavioral control, was found. Suggestions for educational stakeholders regarding how to promote students' autonomous motivation are provided.

The Vanadium Redox Reactions - Electrocatalysis versus Non-Electrocatalysis.

Catalytic effects of surface groups on porous carbon electrodes are claimed in literature for the redox reactions V(II)/V(III) and V(IV)/V(V). The literature is critically analysed also in relation to work of this group. A method how to overcome the problem of assessing the electrochemically active surface area on porous electrodes is presented. Applying this method, no catalytic effects for above reactions can be substantiated. It is further pointed out that the parameters electrochemical potential and temperature need to be used to assess electrocatalysis.

Fluidic Self-Assembly on Electroplated Multilayer Solder Bumps with Tailored Transformation Imprinted Melting Points.

This communication presents fluidic self-assembly of Si-chip on a sequentially electroplated multilayer solder bump with tailored transformation imprinted melting points. The multilayer solder bump is a lead free ternary solder system, which provides a route to transform the melting point of interconnects for applications in solder directed fluidic self-assembly. The outermost metal layers form a low melting point Bi33.7In66.3 solder shell (72 °C). This solder shell enables fluidic self-assembly and self-alignment of freely in water suspended Si-dies at relatively low temperature (75 °C) leading to well-ordered chip arrays. The reduction of the free surface energy of the shell-water interface provides the driving force for the self-assembly. The lowermost metal layer is a high melting point solder and acts as a core. After the self-assembly is complete, a short reflow causes the transformation of the core and the shell yielding a stable high melting point solder with adjustable melting points. The chosen ternary solder system enables the realization of interconnects with melting points in the range of 112 °C to 206 °C.

Microgravimetric and Spectroscopic Analysis of Solid-Electrolyte Interphase Formation in Presence of Additives.

Electrochemical quartz crystal microbalance (EQCM) with damping monitoring is applied for real-time analysis of solid-electrolyte interphase (SEI) formation in diphenyl octyl phosphate (DPOP) and vinylene carbonate (VC) modified electrolytes. Fast SEI formation is observed for the DPOP containing electrolyte, whereas slow growth is detected in VC-modified and reference electrolytes. QCM measurements in a dry state show considerable reduction of the mass quantity for DPOP and reference samples and minor mass decrease for the SEI layer formed in the presence of VC. The results indicate that VC enhances SEI stability, whereas the addition of DPOP or no additive results in incorporation of loosely attached species, leadubg to SEI instability. Resonance frequency damping, Δw, and dissipation factor, D, are used for analyzing mechanical properties of the SEI layers. The apparent increase of Δw and D during SEI formation in presence of DPOP suggests a pronounced viscoelasticity of the layer. QCM results are compared with surface morphology and chemical composition, revealing excellent agreement of the applied characterization approaches.

Motor tests for primary school aged children: A systematic review.

Motor testing in education has gained in relevance in light of recent developments in educational systems (Köller & Baumert, 2012). The purpose of this systematic review was to identify studies using motor tests in primary school children aged 4 to 12 years and to synthetize information about the quality and application of the test instruments used. A systematic review of 910 records identified by a search of nine databases yielded 144 papers reporting motor testing in primary school age children, including 25 articles reporting on the quality of 20 test instruments. In the selected articles, tests grounded on the constructs of "motor abilities" and/or "motor skills" are the most frequent and are mostly used for monitoring purposes or for impact research. Tests based on the construct "motor competencies" have become popular only recently, being relevant for educational motor testing due to their curricular validity. The test instruments have been investigated towards their validity and reliability to different extents. However, for several test instruments factorial validity has not been established and more validation studies are needed to improve their psychometric quality especially if used in educational contexts.

In Situ Studies of Solid Electrolyte Interphase (SEI) Formation on Crystalline Carbon Surfaces by Neutron Reflectometry and Atomic Force Microscopy.

The solid electrolyte interphase (SEI) is a complex and fragile passivation layer with crucial importance for the functionality of lithium-ion batteries. Due to its fragility and reactivity, the use of in situ techniques is preferable for the determination of the SEI's true structure and morphology during its formation. In this study, we use in situ neutron reflectometry (NR) and in situ atomic force microscopy (AFM) to investigate the SEI formation on a carbon surface. It was found that a lithium-rich adsorption layer is already present at the open circuit voltage on the carbon sample surface and that the first decomposition products start to deposit close to this potential. During the negative potential sweep, the growth of the SEI can be observed in detail by AFM and NR. This allows precise monitoring of the morphology evolution and the resulting heterogeneities of individual SEI features. NR measurements show a maximum SEI thickness of 192 Å at the lower cutoff potential (0.02 V vs Li/Li+), which slightly decreases during the positive potential scan. The scattering length density (SLD) obtained by NR provides additional information on the SEI's chemical nature and structural evolution.

Throwing Skills.

Traditionally, motor learning scientists have evaluated the process of learning a new motor skill by considering the skill as a whole. Yet, motor skills comprise various phases, and in the motor learning literature, it is not clear whether new learners show similar or different learning across various phases. We provide exploratory data on learning movement phases by novices, using baseball pitching as the learning task. Eight participants (four male, four female, M age = 23.7 years, SD = 2.4) performed five trials each in the pretest followed by three blocks of 10 trials each in the acquisition phase. Finally, two retention tests of five trials were conducted by each participant 10 minutes and seven days after the last acquisition block, respectively. Intra- and interlimb coordination of upper and lower body segments were measured as dependent variables. We found significant differences between the stride phase and the other phases at pretest, during the acquisition phase, and on both retention tests across all kinematic variables. Participants experienced more trouble coordinating the stride phase than the other phases of pitching, perhaps because the stride phase is the only phase in which the participants had to move their upper and lower body parts simultaneously. We discuss implications for motor learning generally.

A short German Physical-Self-Concept Questionnaire for elementary school children (PSCQ-C): Factorial validity and measurement invariance across gender.

Research on children's physical self-concept (PSC) is increasingly recognised as an important field of psychology. However, there is a lack of instruments suitable for younger children at elementary school age. In the present study, a short German 21-item Physical Self-Concept-Questionnaire for children (PSCQ-C) was tested measuring seven specific facets of elementary school children's PSC (strength, endurance, speed, flexibility, coordination, physical appearance, global sport competence). A number of 770 elementary school children aged 8-12 years completed the PSCQ-C. Results showed good psychometric properties and high reliabilities of the seven scales. Confirmatory factor analysis revealed that the presumed 7-factor model fitted the data best compared to a global 1- and 2-factor model. Also, full measurement invariance was strongly established. Correlations among the seven scales were mainly moderate. Gender differences were suggestive of developmental trends that are consistent with prior studies. These results provide support that the PSCQ-C is a confidential instrument with sound psychometric properties measuring seven specific facets of elementary school children's PSC.

A Three-Dimensional Movement Analysis of the Spike in Fistball.

Due to its relevancy to point scoring, the spike is considered as one of the most important skills in fistball. Biomechanical analyses of this sport are very rare. In the present study, we performed a three-dimensional kinematic analysis of the fistball spike, which helps to specify performance parameters on a descriptive level. Recorded by four synchronized cameras (120 Hz) and linked to the motion capture software Simi Motion® 5.0, three female fistball players of the second German league (24⁻26 years, 1.63⁻1.69 m) performed several spikes under standardized conditions. Results show that the segment velocities of the arm reached their maximum successively from proximal to distal, following the principle of temporal coordination of single impulses. The wrist shows maximum speed when the fist hits the ball. The elbow joint angle performs a rapid transition from a strong flexion to a (almost) full extension; however, the extension is completed after the moment of ball impact. In contrast, the shoulder joint angle increases almost linearly until the fistball contact and decreases afterward. The findings can be used to optimize the training of the spike.

Double layer effects at nanosized electrodes.

This paper discusses numerical simulations of double layer effects at shrouded electrodes with dimensions below 100 nm. Special focus is given to the surface charge on the shrouding material. The Poisson-Nernst-Planck equations are solved to study the effects on the limiting current arising from the electrical double layer of the shrouding.

Do solvation layers of ionic liquids influence electrochemical reactions?

In this discussion paper we discuss our recent results on the electrodeposition of materials and in situ STM/AFM measurements which demonstrate that ionic liquids should not be regarded as neutral solvents which all have similar properties. In particular, we focus on differences in interfacial structure (solvation layers) on metal electrodes as a function of ionic liquid species. Recent theoretical and experimental results show that conventional double layers do not form on metal electrodes in ionic liquid systems. Rather, a multilayer architecture is present, with the number of layers determined by the ionic liquid species and the properties of the surface; up to seven discrete interfacial solvent layers are present on electrode surfaces, consequently there is no simple electrochemical double layer. Both the electrodeposition of aluminium and of tantalum are strongly influenced by ionic liquids: in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]TFSA, aluminium is obtained as a nanomaterial, whereas in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]TFSA, a microcrystalline material is made. Tantalum can be deposited from [Py(1,4)]TFSA, whereas from [EMIm]TFSA only non-stoichiometric tantalum fluorides TaF(x) are obtained. It is likely that solvation layers influence these reactions.

On the electrodeposition of tantalum from three different ionic liquids with the bis(trifluoromethyl sulfonyl) amide anion.

The electrodeposition of Ta from TaF(5) was studied in three different ionic liquids, namely in 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl sulfonyl) amide, 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl) amide and 1-methyl-3-propyl imidazolium bis(trifluoromethyl sulfonyl) amide. The electrochemical quartz crystal microbalance (EQCM) was used together with electrochemical techniques for characterizing in situ the electrodeposition process. With the help of the EQCM we could identify the stoichiometry of the electrodeposited species. Furthermore, square-wave voltammery was used to study intermediate reduction processes in the potential regime where no mass change was detected. An XPS analysis proved the existence of elemental Ta, besides some oxides and Ta halide species. Both the ionic liquid and the deposition conditions influence strongly the quality and properties of the deposited layers.

Novel amino-acid-based polymer/multi-walled carbon nanotube bio-nanocomposites: highly water dispersible carbon nanotubes decorated with gold nanoparticles.

A well-reproducible and completely green route towards highly water dispersible multi-walled carbon nanotubes (MWNT) is achieved by a non-invasive, polymer wrapping technique, where the polymer is adsorbed on the MWNT's surface. Simply mixing an amino-acid-based polymer derivative, namely poly methacryloyl beta-alanine (PMBA) with purified MWNTs in distilled water resulted in the formation of PMBA-MWNT nanocomposite hybrids. Gold nanoparticles (AuNPs) were further anchored on the polymer-wrapped MWNTs, which were previously sonicated in distilled water, via the hydrogen bonding interaction between the carboxylic acid functional groups present in the polymer-modified MWNTs and the citrate-capped AuNPs. The surface morphologies and chemistries of the hybrids decorated with nanoparticles were characterized by transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. Additionally, the composites were also prepared by the in situ free radical polymerization of the monomer, methacryloyl beta-alanine (MBA), with MWNTs. Thus functionalized MWNTs were studied by thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and TEM. Both methods were effective in the nanotube functionalization and ensured good dispersion and high stability in water over three months. Due to the presence of the high densities of carboxylic acid functionalities on the surface of CNTs, various colloidal nanocrystals can be attached to MWNTs.