Compensatory behavior of physical activity in adolescents - a qualitative analysis of the underlying mechanisms and influencing factors.

INTRODUCTION: Compensatory behavior of physical activity (PA) based on the ActivityStat hypothesis in adolescents is scarcely investigated, and existing studies showed inconclusive results. Understanding the compensatory behavior in a holistic way is important as this can help to improve intervention outcomes and thus, increase the PA levels in adolescents. Thus, the aim of the present study is to investigate the occurrence, direction, timeframe, and ratio of habitual activity compensation in adolescents. Furthermore, we want to identify the awareness of compensation and factors that influence compensatory behavior. METHODS: The present qualitative study used a mixed methods crossover analysis design. Participants (N = 15, 8 boys and 7 girls) were adolescents aged 11-15 years (mean age 13.04 ± 1.28). They provided a habitual weekly schedule with habitual/regular activities and their intensity. Participants then kept an activity diary over one week to capture their actual behavior. After that, data were compared and deviations > ±20% were considered as compensation opportunities. On this basis, deviations were descriptively analyzed for compensatory behavior and were coded as positive and negative compensatory behavior. Further, for each compensation, the ratio of compensation (MET-minutes of the compensating activity/MET-minutes of the activity that was compensated) was calculated. Additionally, interviews were conducted to explore perceptions and influencing factors for (no) compensation. RESULTS: Overall, 198 compensation opportunities were identified with deviations greater ± 20%. Of these, 109 opportunities were compensated overall (69 within-day, 40 between-day). Negative compensation took place in 57 opportunities and 52 opportunities were compensated positively. Most of the deviations were overcompensated (compensation/deviation > 100%). About half of the adolescents (N = 8) were not aware about their compensatory behavior, and only one boy was aware of all his compensatory behavior. The most mentioned influence for positive compensation were social support by friends and good weather. As influencing factors for negative compensation, tiredness as well as no need for movement were mentioned predominantly. No negative compensation occurred because adolescents wanted to stick to their routines or participated in hedonistic activities. DISCUSSION: Summarizing the findings, the present study delivered new insights into the field of compensatory behavior in adolescents. Nevertheless, compensatory behavior was not consistently observed regarding the occurrence of compensation, direction, timeframe and ratio. However, social support appears to be an important factor to compensate positively or to avoid a negative compensatory behavior. Further, it seems to be helpful to support individuals in their search for hedonistic activities as well as in the establishment of routines.

Physical activity of children and adolescents who use a wheelchair: a systematic review.

Physical activity has numerous health benefits for people with physical disabilities. Nevertheless, activity levels are often below recommended levels. To promote physical activity among children and adolescents who use a wheelchair as their primary source of mobility, this systematic review explores the physical activity patterns of this group. A systematic search of PubMed, Sports Medicine & Education Index, Web of Science, and SPORTDiscus was performed, included articles were synthesized in terms of duration, intensity, and settings in which physical activity occurred, as well as the physical activity measurement methods. Nine articles were included. The mean overall physical activity level across the included studies was 98 minutes per day (range: 78-115 minutes per day). Two articles analysed the duration of physical activity at different intensities (very light physical activity, light physical activity (LPA), moderate to vigorous physical activity (MVPA) and intensities near to maximum). Within the included articles, both subjective and objective measurement methods were used. Due to the small number of articles, combined with small sample sizes, there is not enough evidence to answer the research questions sufficiently. Nevertheless, the review provides an overview of actual research and clearly shows that the physical activity values are insufficiently researched. There is a need for further research on the scope, types and settings of physical activity in the target group.

Determination of cut-off points for the Move4 accelerometer in children aged 8-13 years.

BACKGROUND: To assess physical activity (PA) there is a need of objective, valid and reliable measurement methods like accelerometers. Before these devices can be used for research, they need to be calibrated and validated for specific age groups as the locomotion differs between children and adults, for instance. Therefore, the aim of the present study was the calibration and validation of the Move4 accelerometer for children aged 8-13 years. METHODS: 53 normal weighted children (52% boys, 48%girls) aged 8-13 years (mean age = 10.69 ± 1.46, mean BMI = 17.93 kg/m- 2, 60th percentile), wore the Move4 sensor at four different body positions (thigh, hip, wrist and the Move4ecg including heart rate measurement at the chest). They completed nine activities that considered the four activity levels (sedentary behavior (SB), light PA (LPA), moderate PA (MPA) and vigorous PA (VPA)) within a test-retest design. Intensity values were determined using the mean amplitude deviation (MAD) as well as the movement acceleration intensity (MAI) metrics. Determination of activities and energy expenditure was validated using heart rate. After that, cut-off points were determined in Matlab by using the Classification and Regression Trees (CART) method. The agreement for the cut-off points between T1 and T2 was analyzed. RESULTS: MAD and MAI accelerometer values were lowest when children were lying on the floor and highest when running or doing jumping jacks. The mean correlation coefficient between acceleration values and heart rate was 0.595 (p = 0.01) for MAD metric and 0.611 (p = 0.01) for MAI metric, indicating strong correlations. Further, the MAD cut-off points for SB-LPA are 52.9 mg (hip), 62.4 mg (thigh), 86.4 mg (wrist) and 45.9 mg (chest), for LPA-MPA they are 173.3 mg (hip), 260.7 mg (thigh), 194.4 mg (wrist) and 155.7 mg (chest) and for MPA-VPA the cut-off points are 543.6 mg (hip), 674.5 mg (thigh), 623.4 mg (wrist) and 545.5 mg (chest). Test-retest comparison indicated good values (mean differences = 9.8%). CONCLUSION: This is the first study investigating cut-off points for children for four different sensor positions using raw accelerometer metrics (MAD/MAI). Sensitivity and specificity revealed good values for all positions. Nevertheless, depending on the sensor position, metric values differ according to the different involvement of the body in various activities. Thus, the sensor position should be carefully chosen depending on the research question of the study.

How do adolescents experience the decision-making process on travel mode choice?

Active travel can contribute to multiple health benefits in youth. Previous research has identified several factors influencing travel behavior. This study investigates how adolescents process these factors during their decision-making process on travel mode choice. Semi-structured interviews were conducted with 13 adolescents (11-14 years) and analysed using deductive-inductive thematic analysis. Four themes were generated from which the decision-making process on mode choice was conceptualized according to adolescents. The step-by-step process in which travel mode options were gradually reduced, was dependent on the context (Theme 1), the perceived availability of travel mode choice options, which was influenced by factors beyond the individual's perceived control (Theme 2), and on adolescents' pros/cons assessment to identify the most convenient option. Adolescents' habitually used travel mode influenced the decision at several stages throughout the process (Theme 4). To promote healthy travel behaviors, interventions should consider contextual circumstances, balance between enabling autonomous choices and promoting advantages of active travel modes, address individual travel modes and include practices that foster conscious processing of decision-making.

Parental perspectives on the decision-making process on transport mode choice in adolescents: a qualitative study with mothers and fathers.

Objective: The present study aims to understand the familial decision-making process on transport mode choice in adolescents with a focus on the parental perspective within this process. Background: Active travel contributes to adolescents' overall physical activity and its positive health effects. Based on the social-learning theory, especially parents are assigned a central role for adolescents' travel behavior. The aim of the present study was to examine how parents are involved in the decision-making process on transport mode choice in adolescents. Method: The study is part of the cross-sectional mixed-methods ARRIVE study which includes semi-structured interviews with mothers (n = 12) and fathers (n = 7) of 11- to 14-year-old German adolescents. The interviews focused on travel behavior in adolescents and the decision-making process on transport mode choice from the parental perspective. All interviews were analyzed inductively using Thematic Analysis. Results: Our study revealed that parents do not primarily decide for or against active travel in adolescents, but are mostly involved in the decision-making process, especially in case of a deviation from the main transport mode. Different forms of parental involvement in the decision-making process were identified. Some parents acted as main decision makers which is the highest form of involvement while others gave their children complete freedom of choose a transport mode for themselves. These parents accepted their child's choice fully which shows a low involvement in the decision-making process. Conclusion: The results provide a deeper understanding of the familial decision-making process on travel behavior in adolescents. The results indicate an occasionally parental involvement in the decision-making process on the mainly used transport mode by adolescents, and that mothers and fathers are always involved when deviating from the main mode. Implications: Further research should investigate changes in travel behavior from childhood to young adulthood to understand long-term travel decisions in families. Due to the findings that parents are often involved in the decision-making process on transport mode choice and that they mainly reported safety concerns as barriers to their children's active travel, further research should focus especially on the social and physical environment of adolescents.

Developing a policy brief on physical activity promotion for children and adolescents.

Introduction: While there are several approaches to collect basic information on physical activity (PA) promotion policies, some governments require more in-depth overviews on the situation in their country. In Germany, the Federal Ministry of Health expressed its interest in collecting detailed data on target group specific PA promotion, as relevant competences are distributed across a wide range of political levels and sectors. This study describes the development of a policy brief on physical activity promotion for children and adolescents in Germany. In particular, it addresses two major gaps in the current literature by systematically assessing good practice examples and "routine practices," i.e., PA promotion activities already taking place on large scale and regular basis. Materials and methods: Based on relevant national and international guidelines, the TARGET:PA tool was co-produced by researchers and ministry officials. It includes (1) PA recommendations, (2) national prevalence rates, (3) recommendations for PA promotion, and data on national (4) routine practices, (5) good practice projects and (6) policies. Data were collected for children and adolescents in Germany using desk research, semi-structured interviews and secondary data analysis. Results: A policy brief and scientific background document were developed. Results showed that 46% of the 4-5-year-olds fulfil WHO recommendations but only 15% of the 11-17-year-olds, and that girls are less active than boys. Currently, in Germany no valid data are available on the PA behaviour of children under the age of three. An overview of routine practices for PA promotion for children and adolescents was compiled, and experts were asked to critically assess their effectiveness, reach and durability. Overall, 339 target group specific projects for PA promotion were found, with 22 classified as examples of good practice. National PA policies for children and adolescents were identified across different sectors and settings. Conclusion: The study provides a comprehensive overview of the current status of PA promotion for children and adolescents in Germany. The co-production of the policy brief was a strength of the study, as it allowed researchers to take the needs of ministry officials into account, and as it supported the immediate uptake of results in the policymaking process. Future studies should test the applicability of the TARGET:PA tool to different target groups and countries.

Associations of parents' and adolescents' active travel behavior across various destinations - a sex/gender analysis.

BACKGROUND: Active travel behavior such as walking and cycling is associated with several health benefits. Especially the family environment seems to be important for active travel in children and adolescents. Currently, little is known regarding travel behavior in leisure time and associations of travel behavior within parent-adolescent dyads. METHODS: The present analysis is based on the German ARRIVE study (Active tRavel behavioR in the famIly enVironmEnt), which incorporated a large scale, representative cross-sectional online survey including 517 parent-child dyads consisting of adolescents (N = 517; boys = 263, girls = 254) aged 11-15 years and one of their parents (N = 517; fathers = 259, mothers = 258). Based on that survey which took place in June 2021 (during the COVID-19 pandemic), we calculated the prevalence of active travel to four commonly visited destinations (school/work, friends/relatives, shopping stores and recreational activities) using an adapted version of the travel to school questionnaire by Segura-Diaz JM, Rojas-Jimenez A, Barranco-Ruiz Y, Murillo-Pardo B, Saucedo-Araujo RG, Aranda-Balboa MJ, et al. (Int J Environ Res Public Health 17(14), 2020). In addition, we investigated the associations between parents' and adolescents' travel behavior using scores for school/work, leisure time (friends/relatives, shopping stores and recreational activities) and overall (school/work and leisure time). RESULTS: Across all destinations, prevalence of active travel in adolescents (63.08%) was higher than in parents (29.21%). Active travel to school (47.33%) as well as to work (20.43%) indicated the lowest prevalence. Linear regression models revealed significant associations in overall active travel between mothers and adolescents (girls: ß = 0.308, p < 0.001; boys: ß = 0.302, p = 0.001) and in leisure time active travel behavior between mothers and daughters (ß = 0.316, p < 0.001). Related to school/work active travel there were no associations between parents and adolescents. CONCLUSION: The associations between adolescents' and parents' travel behavior differ depending on gender: they are solely seen in mother-adolescents dyads. Furthermore, our findings conclude that travel is a routine and independent of the destination.

Motivation and Basic Psychological Needs Satisfaction in Active Travel to Different Destinations: A Cluster Analysis with Adolescents Living in Germany.

Active travel in adolescence contributes to improved health outcomes. Self-Determination Theory suggests that motivation and basic psychological needs influence travel behavior. Person-centered approaches can examine interrelationships of these constructs underlying travel behavior. The aim of this study was to investigate (i) which clusters can be identified in adolescents, (ii) whether clusters explain overall active travel behavior, (iii) whether clusters were associated with travel mode to various destinations or distance, and (iv) whether differences across clusters appear regarding sex/gender, age, and weight status. The sample included 517 (263 male, 254 female) adolescents from Germany, aged 11-15. Self-organizing maps analysis identified six clusters from nine input variables: intrinsic motivation, integrated regulation, identified regulation, introjected regulation, external regulation, amotivation, autonomy satisfaction, competence satisfaction, and relatedness satisfaction. The most beneficial cluster regarding active travel demonstrated highest basic psychological needs satisfaction and autonomous motivation with low controlled motivation and amotivation. The most vulnerable cluster was characterized by generally low levels of motivation except for external regulation and amotivation. Clusters were not associated with distance to school, friends/relatives, shopping facilities, or leisure facilities. The findings support the importance of high quality and high quantity of motivation for active travel in adolescents.

Signaling strategies of silver nanoparticles in optical and electrochemical biosensors: considering their potential for the point-of-care.

Silver nanoparticles (AgNPs) have long been overshadowed by gold NPs' success in sensor and point-of-care (POC) applications. However, their unique physical, (electro)chemical, and optical properties make them excellently suited for such use, as long as their inherent higher instability toward oxidation is controlled. Recent advances in this field provide novel strategies that demonstrate that the AgNPs' inherent capabilities improve sensor performance and enable the specific detection of analytes at low concentrations. We provide an overview of these advances by focusing on the nanosized Ag (in the range of 1-100 nm) properties with emphasis on optical and electrochemical biosensors. Furthermore, we critically assess their potential for point-of-care sensors discussing advantages as well as limitations for each detection technique. We can conclude that, indeed, strategies using AgNP are ready for sensitive POC applications; however, research focusing on the simplification of assay procedures is direly needed for AgNPs to make the successful jump into actual applications.

Family predictors of physical activity change during the COVID-19 lockdown in preschool children in Germany.

The COVID-19 pandemic is associated with crucial changes in children's daily life including their physical activity (PA) and screen time (ST). Among preschool children, the family represents an important factor for sufficient PA levels by being the gatekeeper for PA. Thus, the aim of this study was to investigate the influence of the family environment, specifically SES, parental support, and having siblings on COVID-19-related changes of PA and ST behavior in 317 (170 boys, 147 girls) German preschool children using longitudinal data. Our results indicate a decline in total amount of sports-related PA, an increase in outdoor play, as well as an increase in leisure ST in preschool children. The changes in total amount of PA differed between children with different levels of parental support as well as in dependence on having siblings. Furthermore, levels of outdoor play and ST in preschool children were influenced by environmental factors like having access to their own garden. We conclude that the family environment (parental support as well as physical environment) is highly relevant for PA and ST levels in preschool children. To provide every child with PA opportunities during potential future lockdowns, restriction policies should be adapted and parents need sophisticated information about the importance of their support and thus the PA levels of their children.

Compensation of overall physical activity in (pre)adolescent girls - the CReActivity project.

BACKGROUND: According to the ActivityStat hypothesis more physical activity (PA) in one timespan is compensated by increased sedentary time (ST) in the following timespan and vice versa to maintain an overall stable PA level. Until now, existing literature revealed inconsistent results regarding compensatory behaviour across children and adolescents. Thus, the aim of the present study is (1) to investigate whether ST in the morning is compensated by active behaviour in the afternoon and (2) whether ST during the week is compensated by active behaviour during the weekend in (pre)adolescent girls. Additionally, we aimed to differentiate between positive and negative compensatory behaviour and examine whether it is moderated by socioeconomic status (SES), age or weight status. METHODS: The participants were 370 sixth grade school girls (mean age 11.6 years) from Munich that participated in the CReActivity study, a school based intervention study aiming to identify the mechanisms of behavioural changes in PA among girls. ST and PA were measured over seven consecutive days using accelerometery. Descriptive determination of compensatory behaviour, as well as Bayesian multivariate multilevel analysis were conducted with data clustered on the individual (ID), class and school level. RESULTS: Descriptive analysis revealed rather constant compensatory behaviour of about 60% for after-school days and weekends over all observation points. However, regarding all girls, compensation was predominantly negative. Differentiated analysis indicated that all girls with low ST levels in the morning or on weekdays, compensated for this behaviour with lower PA levels in the afternoon or on weekends. Multilevel covariate analysis indicated great variability between the participants. Furthermore, differences in compensatory behaviour can also be seen on class and school levels. Interestingly, PA compensatory behaviour is not associated with age, weight status or SES. CONCLUSION: Our findings could neither confirm nor reject the ActivityStat Hypothesis. Overall, due to the great variability across the girls, it seems that compensation depends on individual factors. In the future, to prevent negative compensation, school-based interventions that have the potential to provide opportunities to be physically active, should not neglect (pre)adolescents' leisure time behaviour. TRIAL REGISTRATION: DRKS00015723 (date of registration: 2018/10/22 retrospectively registered).

Compensation or Displacement of Physical Activity in Children and Adolescents: A Systematic Review of Empirical Studies.

Regular physical activity during childhood and adolescence is associated with health benefits. Consequently, numerous health promotion programs for children and adolescents emphasize the enhancement of physical activity. However, the ActivityStat hypothesis states that increases in physical activity in one domain are compensated for by decreasing physical activity in another domain. Currently, little is known about how physical activity varies in children and adolescents within intervals of one day or multiple days. This systematic review provides an overview of studies that analyzed changes in (overall) physical activity, which were assessed with objective measurements, or compensatory mechanisms caused by increases or decreases in physical activity in a specific domain in children and adolescents. A systematic search of electronic databases (PubMed, Scopus, Web of Science, SportDiscus) was performed with a priori defined inclusion criteria. Two independent researchers screened the literature and identified and rated the methodological quality of the studies. A total of 77 peer-reviewed articles were included that analyzed changes in overall physical activity with multiple methodological approaches resulting in compensation or displacement. Of 40,829 participants, 16,265 indicated compensation associated with physical activity. Subgroup analyses separated by study design, participants, measurement instrument, physical activity context, and intervention duration also showed mixed results toward an indication of compensation. Quality assessment of the included studies revealed that they were of high quality (mean = 0.866). This review provides inconclusive results about compensation in relation to physical activity. A trend toward increased compensation in interventional studies and in interventions of longer duration have been observed.

Active travel behaviour in the family environment: protocol for the mixed-methods cross-sectional ARRIVE study.

INTRODUCTION: Active travel is an important source of physical activity and a primary contributor to overall health among adolescents. To understand and promote active travel behaviour in adolescents, developing a more robust understanding of the predictors of active travel and its associated decision-making processes is needed. Situated within a theoretical socioecological framework for adolescent travel behaviour, the mixed-methods Active tRavel behavioR in the famIly enVironmEnt study aims to quantitatively assess the influence of several predictors of adolescent travel behaviour, and to qualitatively understand the associated decision-making processes of both adolescents and parents. METHODS AND ANALYSIS: Our mixed-methods approach will feature online surveys and semistructured interviews. The online questionnaire, developed in accordance with a theoretical framework of adolescent active travel, will examine adolescent travel behaviour with respect to four different destinations while controlling for multiple relevant individual, social and physical environment factors. To enable the comparison of adolescent and parental perspectives, the questionnaire will be answered by a representative sample of German adolescents (11-15 years old) and their parents.Our semistructured interviews, likewise framed based on the central tenets of the theoretical framework of adolescent active travel, will seek to explore the decision-making process of families regarding travel mode choice via conducting interviews with each member (ie, father, mother, adolescent). To investigate travel decision-making processes, adolescents and their parents will be invited to talk about trips they undertook using both active and passive transport modes during the last week. Thematic analyses will be conducted to highlight the central concerns, priorities and values of participants' decision-making processes. ETHICS AND DISSEMINATION: This study has received ethical approval from the ethics commission of the Friedrich-Alexander-University Erlangen-Nuremberg. Study results will be disseminated at scientific conferences and published in peer-reviewed journals. Additionally, study findings will be made publicly available to relevant health, policy, and research stakeholders and groups.

Riboflavin and Its Effect on Dentin Bond Strength: Considerations for Clinical Applicability-An In Vitro Study.

Bioactive collagen crosslinkers propose to render the dentin hybrid layer less perceptive to hydrolytic challenge. This study aims to evaluate whether bond strength of dental resin composite to dentin benefits from riboflavin (RB)-sensitized crosslinking when used in a clinically applicable protocol. A total of 300 human dentin specimens were prepared consistent with the requirements for a macro-shear bond test. RB was applied on dentin, either incorporated in the primer (RBp) of a two-step self-etch adhesive or as an aqueous solution (RBs) before applying the adhesive, and blue light from a commercial polymerization device was used for RB photoactivation. Bonding protocol executed according to the manufacturer's information served as control. Groups (n = 20) were tested after 1 week, 1 month, 3 months, 6 months or 1 year immersion times (37 °C, distilled water). The different application methods of RB significantly influenced bond strength (p < 0.001) with a medium impact (η2p = 0.119). After 1 year immersion, post hoc analysis identified a significant advantage for RB groups compared to RBp (p = 0.018), which is attributed to a pH-/solvent-dependent efficiency of RB-sensitized crosslinking, stressing the importance of formulation adjustments. We developed an application protocol for RB-sensitized crosslinking with emphasis on clinical applicability to test its performance against a gold-standard adhesive, and are confident that, with a few adjustments to the application solution, RB-sensitized crosslinking can improve the longevity of adhesive restorations in clinics.

Dry-reagent microfluidic biosensor for simple detection of NT-proBNP via Ag nanoparticles.

The diagnosis of many diseases requires monitoring of biomarker levels over a period of time instead of assessing their concentration only once. For example, in case of heart failure determination, the levels of N-terminal prohormone brain natriuretic peptide (NT-proBNP) in blood vary so strongly amongst individuals, that the current procedure of one-time measurement in combination with clinical examination does not allow for accurate assessment of disease severity and progression. Our microfluidic biosensor addresses key characteristics of desirable home-tests which include low limits of detection, small sample volume (less than 10 µL), simple detection strategies, and ready-to-go all-dried long-term stable reagents. Here, electrochemically superior silver nanoparticles (AgNP) were dried directly within the microfluidic channel in a matrix of trehalose sugar doped with Na2SO3 as oxygen scavenger. This successfully prevented AgNP oxidation and enabled dry and ready-to-use storage for at least 18 weeks. Based on this, laser-cut flow chips were developed containing all bioassay reagents needed in a ready-to-go dry format. An oxidation-reduction stripping voltammetry strategy was used for highly sensitive quantification of the AgNPs as electrochemical label. This microfluidic biosensor demonstrated limits of detection for NT-proBNP of 0.57 ng mL-1 with a mean error of 6% (n ≥ 3) in undiluted human serum, which is below the clinically relevant cut-off of 1 ng mL-1. This practical approach has the potential to substitute commonly used lateral-flow assays for various biomarkers, as it offers low patient sample volumes hence supporting simple finger-prick strategies well-known also for other electrochemical biosensors, and independence from the notorious variability in fleece fabrication.

Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors.

Electrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL-1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL-1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL-1 in buffer and 4.7 ng∙mL-1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

Changes in Physical Activity during the COVID-19 Pandemic-An Analysis of Differences Based on Mitigation Policies and Incidence Values in the Federal States of Germany.

Measures to slow down the spread of coronavirus SARS-CoV-2 have had an impact on the daily life and physical activity (PA) of many people. Nevertheless, in Germany, mitigation policies and incidence values vary widely across the federal states (Länder). Thus, the aim of the present study was to investigate regional differences in PA during the coronavirus pandemic. This study is based on the SPOVID project (Examining physical activity and sports behavior in the face of COVID-19 pandemic: a social inequality perspective) that incorporates a large-scale, representative cross-sectional survey representing the German population (≥14 years). Based on the survey that took place in October 2020 (N = 1477), we investigated the relationships between the COVID-19 incidence values as well as the mitigation policies across the federal states in Germany and changes in PA. Pearson correlations indicated a strong negative relationship between PA change and 7-day incidence values (r = -0.688 **, p = 0.009) and a moderate negative relationship between PA changes and an index of mitigation policies (r = -0.444, p = 0.112). Higher 7-day incidence values and stricter mitigation policies were associated with a stronger decline in PA levels. Therefore, it is important to support people to stay active even if there are restrictions. In particular, in federal states and regions with high incidences and stricter mitigation policies, measures to promote health-enhancing PA are necessary.

Microfluidic-enabled magnetic labelling of nanovesicles for bioanalytical applications.

Bearing multiple functionalities dramatically increases nanomaterial capabilities to enhance analytical assays by improving sensitivity, selectivity, sample preparation, or signal read-out strategies. Magnetic properties are especially desirable for nanoparticles and nanovesicles as they assist in negating diffusion limitations and improving separation capabilities. Here, we propose a microfluidic method that reliably labels functional nanovesicles while avoiding the risk of crosslinking that would lead to large conglomerates as typically observed in bulk reactions. Thus, the carboxy groups of bi-functional biotinylated fluorescent liposomes were activated in bulk. They were then covalently bound to amino group presenting magnetic beads immobilized through a magnetic field within microfluidic channels. Microfluidic design and coupling strategy optimization led to a 62% coupling efficiency when using 1 µm magnetic beads. The yield dropped to 13% with 30 nm magnetic nanoparticles (MNPs) likely due to crowding of the MNPs on the magnet. Finally, both populations of these tri-functional liposomes were applied to a biological binding assay demonstrating their superior performance under the influence of a magnetic field. The microfluidic functionalization strategy lends itself well for massively parallelized production of larger volumes and can be applied to micro- and nanosized vesicles and particles.

Antioxidants and Collagen-Crosslinking: Benefit on Bond Strength and Clinical Applicability.

Antioxidants are known for their potential of strengthening the collagen network when applied to dentin. They establish new intra-/intermolecular bonds in the collagen, rendering it less perceptive to enzymatic hydrolysis. The study evaluated the benefit on shear bond strength (SBS) of a resin-composite to dentin when antioxidants with different biomolecular mechanisms or a known inhibitor of enzymatic activity are introduced to the bonding process in a clinically inspired protocol. Specimens (900) were prepared consistent with the requirements for a macro SBS-test. Four agents (Epigallocatechingallate (EGCG), Chlorhexidindigluconate (CHX), Proanthocyanidin (PA), and Hesperidin (HPN)) were applied on dentin, either incorporated in the primer of a two-step self-etch adhesive or as an aqueous solution before applying the adhesive. Bonding protocol executed according to the manufacturer's information served as control. Groups (n=20) were tested after one week, one month, three months, six months, or one year immersion times (37 °C, distilled water). After six-month immersion, superior SBS were identified in PA compared to all other agents (p<0.01) and a higher reliability in both primer and solution application when compared to control. After one year, both PA incorporated test groups demonstrated the most reliable outcome. SBS can benefit from the application of antioxidants. The use of PA in clinics might help extending the lifespan of resin-based restorations.