Low Load Research Articles

Investigation of the effect of load weight on the discharge capacity of lithium–o2 batteries using carbon-paper–based electrodes

We prepared carbon electrodes with nearly uniform thickness and varying loading weights using carbon paper (CP) as a support material and current collector for single-walled carbon nanotubes (SWCNTs). These electrodes were used as the positive electrode in a lithium–O2 battery, tested at a lower voltage limit of 2.4 V with a fixed current of 0.26 mA/cm2 (0.5 mA). Results demonstrated that the discharge gravimetric capacity (capacity normalized per weight of SWCNTs) did not change significantly for loading weights ≥0.42 mg/cm2. However, for loading weights <0.42 mg/cm2, the discharge gravimetric capacity exhibited an inverse correlation with weight. Analysis of the prepared electrodes revealed that at very low SWCNT loading weights, the sheets of SWCNTs became extremely thin, leading to occasional tears. Nonetheless, these structural changes had no significant impact on the specific surface area or contact resistance. Further analysis of the post-test electrodes using scanning electron microscopy and X-ray diffraction, along with considerations of the carbon paper's surface area as a percentage of the total electrode surface, led to the conclusion that at low loading weights, CP actively contributes to the discharge process and serves as a deposition site for Li2O2. Consequently, when the weight of the active material falls below a certain threshold, there is a risk of misperception, potentially leading to an overestimation of the discharge capacity.

Experimental study on GFRP-steel double-skin rubber concrete composite piers under mixed loading

To address the issues related to the insufficient compressive and shear strength of rubberized concrete and to enhance the deformation capacity and longevity of composite piers, a novel approach involving the confinement of rubberized concrete with glass fiber-reinforced polymer (GFRP) tube and steel tube has been proposed. This method aims to create a GFRP-steel double-skin rubberized concrete composite pier. Pseudo-dynamic and quasi-static tests were conducted on the composite pier to assess its seismic response and residual seismic performance. The study investigated the failure mode, hysteretic characteristics, ductility, energy dissipation, stiffness, and self-centering capability of composite piers. Additionally, a correction coefficient for the equivalent plastic hinge length was proposed. The results indicate that the specimen maintains its elastic state when subjected to frequent seismic events. However, when subjected to infrequent seismic events, the glass fiber layer may fracture, leading to the development of white stripes, while the steel tube experiences yielding, transitioning into a plastic state. The shock absorption and toughness of rubberized concrete were effectively utilized when subjected to horizontal low cyclic loading, thereby mitigating the appearance of more pronounced damage in seismic-damaged specimens. The hysteretic curve was complete, demonstrating a significant energy dissipation capacity. This confirmation indicates that the composite pier can be a viable solution for sea-crossing bridges and complex environments.

Impacts of meteorological conditions on the plummeting surface-reaching solar radiation over a sub-tropical station – Pune, India

The unprecedented rise of solar energy as a dominant power source is a remarkable feat, considering our historical struggle to establish its widespread adoption. However, the dynamics of solar radiation reaching the Earth's surface are greatly influenced by meteorological conditions such as clouds, aerosols, and wind speed. This study investigates the detailed changes in surface-reaching solar radiation within the subtropical region Pune from 1993 to 2022. By employing analytical methodologies including linear regression, wavelet coherence, and quantitative analysis, our study reveals a compelling and alarming pattern of plummeting solar radiation over Pune (also known as solar dimming). The total drop is ∼1.04 Wm−2 year−1 (0.21 % year−1), with a more steep decline registered from 2018 to 2022, providing an astonishing rate of ∼6.01 Wm−2 year−1 (1.21 % year−1). Moreover, wavelet coherence transform revealed an antiphase coherence between solar radiation and both clouds and aerosols, suggesting their substantial influence over a longer timeframe. Extensive analysis utilizing observational data is conducted to find the contributing elements to the significant decline during 2018 to June 2022. Analysis of solar radiation statistics showed that clouds led to a substantial reduction of ∼30.18 % compared to conditions with clear-skies. Similarly, the aerosols have a comparable effect, reducing radiation by ∼17.75 % compared to days characterized by low or negligible aerosol loading for the same period. Furthermore, a through statistical analysis investigates a notable anticorrelation (ρ = −0.64) between wind speed and solar radiation. These findings underscore the imperative of incorporating climatic variables while studying solar dimming trends and devising sustainable renewable energy strategies to ensure the long-term viability of solar energy source.

Power law dependence of unstable slip velocity on decreasing shear loading stiffness

Shear loading stiffness plays a critical role in conditioning the stability of slip on reactivated faults. However, a relationship linking peak slip velocities and shear loading stiffness is lacking. To explore this, we shear granite faults in double direct shear with shear loading stiffnesses spanning two orders to define the effects of shear loading stiffness in conditioning the transition from stable to unstable slip. Our results show that peak slip velocity and acceleration decrease as power law relationships with respect to the shear loading stiffness ratio, with identical exponent, and with a linear relationship between the peak slip velocity and acceleration. The maximum acceleration occurs during the velocity weakening process that limits the peak slip velocity. The power law exponent increases linearly with increasing normal stress. Experimental results also indicate that slip magnitude, stress drop and recurrence time of unstable slip events increase, and slip durations decrease with decreasing stiffness ratios. The spans of limit cycles of velocity versus shear stress decrease, and their shapes evolve from triangular to semicircular with increasing loading stiffness ratio. Stress drops mostly occur during deceleration. The deceleration phase dominates the unstable slip duration that decreases as peak slip velocity increases. Our results indicate that the average stress drop rates over a slip duration increase as a power law relationship with reducing shear loading stiffness, which also contributes to a lower shear loading stiffness producing increased slip velocities and accelerations. Our findings highlight that loading stiffness ratio is an underlying mechanism defining unstable slip behaviors with the normal stress merely conditioning the exponent. The present relationship of unstable slip velocity with shear loading stiffness suggests a way to evaluate hazard of an impending instability event based on the initial shear loading stiffness ratio that can be calculated through the linear-elastic behaviors at the early quasi-static phase.

Оценка нестабильности последовательных впрыскиваний топливной аппаратуры дизелей

The issues of uneven cyclic feed in sequential injections by diesel fuel equipment are considered, which is directly related to solving the problem of ensuring the quality of operation of engines of various types and purposes when operating at low loads and rotational speeds. The special importance of solving these problems from the standpoint of ensuring fuel efficiency, environmental pollution, solving issues of engine reliability and improving their operational properties was noted. The features of the formation of residual fuel pressure in the high-pressure pipeline are revealed. The periodic fluctuations of the cyclic feed and injection parameters from cycle to cycle are estimated. A study of possible options for the operation of fuel equipment in low fuel supply modes has been carried out. Based on the analysis, a criterion for evaluating the instability of successive injection cycles for diesel fuel equipment during its operation in various modes has been introduced. By studying numerical examples, the conditions of unstable fuel supply processes in successive injections of various characteristic modes are determined. The criterion determines the quality of the fuel equipment of marine diesel engines and diesel generators in terms of ensuring a minimum stable idle speed and the possibility of ensuring stable reduced fuel supplies. The variability of fuel supply processes in sequential feeds is the cause of increased exchange processes of electric power flow during parallel operation of diesel alternators and reduces the performance characteristics of diesels for various purposes when operating in partial modes. In the process of carrying out development work, scientific research and during the refinement of diesels, the instability criterion allows us to assess the quality of the fuel equipment precisely in partial modes. This is of particular importance for diesel engines of fishing vessels operating for a long time at shared loading modes and low idle speeds, as well as for engines of the tugboat fleet and auxiliary diesel generator sets of all types of facilities used.

Shake table tests on a rigid block isolated with high-damping unbonded fiber-reinforced elastomeric isolators

Fiber-reinforced elastomeric isolators (FREIs) represent a relatively recent type of elastomeric device. In contrast to traditional steel-reinforced elastomeric isolators (SREIs), FREIs are constructed with multiple layers of rubber pads and fiber layers instead of steel laminas. This choice is aimed at cost reduction during the manufacturing and installation process. To enhance cost-efficiency, FREIs can also be used in unbonded applications (UFREIs), where the device is placed between the foundation and the superstructure without bonding or fastening. This approach helps to further minimize installation expenses. Furthermore, the lateral rollover deformation, a characteristic feature of this configuration, improves energy dissipation. This study investigates the seismic isolation capabilities of high-damping unbonded FREIs for low-rise masonry buildings. Specifically, unidirectional cyclic and shake table tests of a rigid block isolated with two UFREIs are discussed. The primary goals of this experimental study include evaluating the effectiveness of UFREIs in reducing seismic demands, analyzing the response of UFREIs under unidirectional ground-motion excitation, confirming the ability of UFREIs to withstand major unidirectional excitation without sustaining damage, and exploring the limitations of this isolation system under a range of seismic inputs and low axial loads.

Enhancing the protective performance of anti-impact, corrosion resistant and flame retardant polyurea coatings using bio-based supramolecular decorated montmorillonite

Developing bio-based nano-additives for enhancing mechanical strength, corrosion resistance, and flame retardancy in polyurea (PUA) coatings at low loading levels is crucial for human well-being and environmental preservation. In this study, montmorillonite (MMT) was first exfoliated by ball milling with the aid of chitosan, and then further co-assembled with phytic acid and urea to form a nanohybrid (CPN@MMT). The resulting CPN@MMT nanohybrid exhibited good compatibility and dispersibility within matrix and endowed PUA composites with improved anti-impact, corrosion resistant and flame retardant properties. Remarkably, the addition of CPN@MMT improved the mechanical and impact protection properties of PUA coatings. Electrochemical and salt spray tests confirmed that the excellent anti-corrosion performance of PUA composite coating stemmed from the dispersed nano-sheets forming a protective nano-barrier. CPN@MMT in the PUA matrix formed a compact char layer, reducing heat release and smoke by inhibiting heat diffusion and volatile gas evaporation, as evidenced by cone calorimeter and TG-FTIR tests. The enhanced fire safety was primarily attributed to the physical barrier, catalytic charring and dilution effect of CPN@MMT. Hence, a green and feasible method was developed to create bio-based nano-additive in PUA coatings with anti-impact, corrosion resistant and flame retardant performance.

Optimization of mixed cargo allocation and stowage with heterogeneous vehicles

In order to solve the problem of low efficiency and high loading costs in business logistics and distribution operations, this paper classifies non-standard cargoes based on their spatial and temporal characteristics. Based on this, a dual-layer planning model for multi-vehicle cargoes loading and transportation is constructed to jointly optimize the loading process. This paper designs a space-inspired heuristic algorithm to solve the model and verifies the feasibility of the model. The results show that compared to a single vehicle type, the joint optimization of multi-vehicle combinations for loading and transportation has stronger adaptability and can better accommodate changes in cargo volume. Compared to the single vehicle type, not only did the loading rate increase by 18%, but also effectively reduced the transportation cost by 3%. Different proportions of spatial and temporal characteristic cargoes have different effects on the loading and transportation. Adjusting the proportion of cargoes that can be placed on both upper and lower layers to 50% can better utilize transportation resources such as vehicles. Increasing the proportion of urgent cargoes can improve the economic efficiency of loading and transportation.

High Selenium Loading in Vertically Aligned Porous Carbon Framework with Visualized Fast Kinetics for Enhanced Lithium/Sodium Storage

AbstractLithium/sodium–selenium (Li/Na–Se) batteries with high volumetric specific capacity are considered promising as next‐generation battery technologies. However, their practical application is hindered by challenges such as low Se loading in cathodes and the polyselenides shuttle effect. To address these challenges, a new Se host is introduced in the form of a free‐standing N, O co‐doped vertically aligned porous carbon framework decorated with a carbon nanotube forest (VCF‐CNTs), allowing for high mass loading of up to 16 mg cm−2. The low‐tortuosity Se@VCF‐CNTs architecture facilitates rapid lithiation/sodiation kinetics, while the CNT forests in vertical microchannels enhance efficient Se loading and serve as a multi‐layer fence to prevent undesired polyselenide shuttling. Consequently, the Se@VCF‐CNTs cathode displays a significant areal capacity of 10.3 mAh cm−2 at 0.1 C with a Se loading of 16 mg cm−2 for Li–Se batteries, exceeding that of commercial lithium ion batteries (4.0 mAh cm−2). In Na–Se batteries, the Se@VCF‐CNTs electrode with a Se loading of 5 mg cm−2 exhibits a discharge capacity of 436 mAh g−1 after 200 cycles, proving its consistent cycling performance. This study enriches the field of knowledge concerning high‐loading Se‐based battery systems, offering a promising avenue for enhancing energy density in the field.

A series of triphenylamine-derived fluorophores attached to a Cu-based MOF for gaseous CO optical sensing: synthesis, performance, and mechanism.

A series of triphenylamine-derived fluorescent dyes were attached to a Cu2+-containing MOF (metal-organic framework), denoted as Pm@CuMOF. The molecular structures of these dyes were discussed by the single crystal structures. Their major absorption bands peaked at 410-450 nm, showing emission bands ranging from 556 to 586 nm with emission quantum yields ranging from 8.0 to 15.1%. It was found that the [-N(C2H5)2] group generally improved sensing performance, and the -OH group in the dyes helped the Cu2+ quenching effect. Pm@CuMOF was observed by SEM as nanorods with a width of ~100 nm and a length of 300 nm. Their XRD patterns and N2 adsorption/desorption isotherms were recorded to confirm their porous structure. A low probe loading level of ~4% was determined by TGA result. The CO sensing mechanism was revealed as a Cu2+/Cu+-involved sensing mechanism based on the result of NMR titration, IR, XPS, and EPR. The fluorescence of these triphenylamine-derived dyes was firstly quenched by CuMOF. In contact with CO, Cu2+ was reduced to Cu+, accompanied by the release and fluorescence recovery of the fluorescent dyes, showing emission turn-on effect towards CO gas. Pm@CuMOF showed increased emission intensity at CO level of 0.005% (versus N2), with response times ranging from 123 s to 280 s (depending on various temperatures). Good selectivity was observed over competing alkane gases, with stable emission for at least 5 days, but no linear calibration plots were observed.

The RT M184V resistance mutation clearance in the reservoir is mainly related to CD4 nadir and viral load zenith independently of therapeutic regimen type.

Resistance associated mutations (RAMs) are archived in the HIV reservoir and can re-emerge with an inappropriate ART use limiting treatment options. However, recent studies, using ultra-deep sequencing (UDS), showed a decrease of quasispecies harbouring RAMs, suggesting that recycling some antiretrovirals could be considered. The aim of this study was to characterize, in HIV treated PLWHIV, the M184V mutation decrease kinetics in proviral DNA and associated factors of M184V mutation clearance over time. UDS was performed on HIV-DNA from blood cells at different time points to quantify the percentage of M184V positive quasispecies. The sequence reads were analysed with a minimum coverage set at 50 and an ambiguity filter at 5% or 2%. At 2.5 years after the first time point, the M184V lost was observed in 50% of PLWHIV. Moreover, univariate analyses highlight that a higher nadir CD4 count and a lower zenith HIV1 RNA viral load were correlated with a faster clearance of the mutation. In multivariate analysis, a higher zenith was negatively associated with the M184V clearance at the 5% threshold. Interestingly, lamivudine/emtricitabine presence in the ART therapy regiment during the 5 years was not associated with the persistence of the M184V. Our study provides new information concerning the clearance speed of M184V mutation over time in PLWHIV with fully suppressed viremia, opens the discussion about the duration needed to consider a lamivudine/emtricitabine recycling and reinforces the association of the nadir and zenith values with the M184V mutation clearance.

Improved Tribological Performance of a Polybutylene Terephthalate Hybrid Composite by Adding a Siloxane-Based Internal Lubricant

To mitigate the environmental hazards aroused by fossil-based lubricants, the development of eco-friendly internal lubricants is imperative. Siloxane-based internal lubricants, widely applied as plasticizers in polymeric compounds, are a promising option. However, their impacts on the tribological properties of polymeric tribocomponents are still unclarified. Therefore, in the current study, a siloxane-based internal lubricant with the product name ‘EverGlide MB 1550 (EG)’ was dispersed into a polybutylene terephthalate (PBT)-based tribological composite to investigate whether the tribological properties of the composite can be optimized. A block-on-ring (BOR) test configuration was used for this purpose. It was found that the addition of EG to the composite significantly improved the tribological behavior; the improvement was particularly significant under lower load conditions (pv-product ≤ 2 MPa∙m/s). Compared to the reference PBT composite, the addition of EG reduced the friction coefficient (COF) by about 30% and the specific wear rate by about 14%. An accompanying surface analytical investigation using photoelectron spectroscopy to elucidate the effective mechanisms at the molecular level showed the availability of tribologically effective and free EG after its addition to the composite in the relevant tribocontact.

Real-Time Three-Dimensional Tracking of Distant Moving Objects Using Non-Imaging Single-Pixel LiDAR

The real-time tracking of moving objects has extensive applications in various domains. Existing tracking methods typically utilize video image processing, but their performance is limited due to the high information throughput and computational requirements associated with processing continuous images. Additionally, imaging in certain spectral bands can be costly. This paper proposes a non-imaging real-time three-dimensional tracking technique for distant moving targets using single-pixel LiDAR. This novel approach involves compressing scene information from three-dimensional to one-dimensional space using spatial encoding modulation and then obtaining this information through single-pixel detection. A LiDAR system is constructed based on this method, where the peak position of the detected full-path one-dimensional echo signal is used to obtain the target distance, while the peak intensity is used to obtain the azimuth and pitch information of the moving target. The entire process requires minimal data collection and a low computational load, making it feasible for the real-time three-dimensional tracking of single or multiple moving targets. Outdoor experiments confirmed the efficacy of the proposed technology, achieving a distance accuracy of 0.45 m and an azimuth and pitch angle accuracy of approximately 0.03° in localizing and tracking a flying target at a distance of 3 km.

A life cycle assessment of the laboratory—scale oxidative liquefaction as the chemical recycling method of the end-of-life wind turbine blades

According to the latest reports, estimated values of 50,000–66 000 t of end-of-life wind turbine blades (WTB) are expected to be decommissioned in Europe in 2025–2030, posing a significant threat from the environmental and waste management perspectives. This study aims to present the preliminary Life Cycle Assessment (LCA) with sensitivity and uncertainty analysis of the lab-scale oxidative liquefaction process of the WTB, as the original method to recover the high-quality glass fibers with simultaneous production of the secondary chemicals: phenols, ketones, acids, and fatty acids, from the oxidation of the epoxy resin from the polymer matrix. The LCA is based on the experimental results of the oxidative liquefaction process carried out on a laboratory scale using a Parr 500 ml batch reactor, at two different conditions sets for the functional unit (FU) of 1 kg of treated WTB. Each of the analyzed scenarios resulted in higher impact indicators compared to the landfilling. The highest quality fibers were obtained at 350 °C and 40 wt % H2O2 content resulted in 5.52 ± 1.20 kgCO2 eq Climate change impact and 97.8 ± 20.6 MJ of Resource use, fossil per kg of recycled WTB. The lowest quality fiber recovered in char, yet well separated from the matrix obtained at 250 °C and the lowest H2O2 content resulted in 0.0953 ± 0.487 kgCO2 eq Climate change impact and 8.84 ± 7.90 MJ of Resource use, fossil per kg of recycled WTB. The hot spot and sensitivity analysis indicated, that the oxidizer for the process – hydrogen peroxide, when acquired as a shelf product causes a significant burden on the whole process, with sensitivity ratios on the total impact indicators varying across the categories from 0.56 to 0.99. Substitution of H2O2 with theoretical 0-input oxidizer allowed to significantly lower environmental load of the recycling process, which in all of the analyzed scenarios presented environmental benefits compared to landfilling with recovery of the glass fiber and secondary chemicals.

A modified persian version of the self-stigma of depression scale among the Iranian population: a methodological study in 2023

IntroductionThis cross -sectional research evaluated the psychometric properties of the Self-Stigma of Depression Scale (SSDS) among Iranian people.MethodsThis methodological study was conducted among 881 people in 2023, Iran. The method of proportional stratified sampling was used to select participants. To evaluate the validity, face, content, construct, convergent, and discriminant were evaluated. The reliability of SSDS was assessed with the McDonald’s omega coefficient, Cronbach α coefficient, and test– retest (Intraclass Correlation Coefficient).ResultsIn confirmatory factor analysis, the factor loading of all items of SSDS was more than 0.5, and two items had low factor loading. After deleted these items, goodness of fit indexes (such as GFI = 0.945, RMSEA = 0.067, AGFI = 0.917, CFI = 0.941, RFI = 0.905) confirmed the final model with 14 items and four factors of social inadequacy (3 items), help-seeking inhibition (4 questions), self-blame (3 questions), and shame (4 questions). In the reliability phase, for all items of SSDS, Cronbach α coefficient was 0.850, the McDonald omega coefficient was 0.853, and the intraclass correlation coefficient was 0.903.ConclusionThe Persian form of SSDS was approved with 14 items and four factors: social inadequacy, help-seeking inhibition, self-blame, and shame. This tool can be used to check the status of self-stigmatization of depression in different groups.

Validation of the motivated strategies for learning questionnaire and instructional materials motivation survey

Purpose To validate the Motivated Strategies for Learning Questionnaire (MSLQ), which measures learner motivations; and the Instructional Materials Motivation Survey (IMMS), which measures the motivational properties of educational activities. Methods Participants (333 pharmacists, physicians, and advanced practice providers) completed the MSLQ, IMMS, Congruence-Personalization Questionnaire (CPQ), and a knowledge test immediately following an online learning module (April 2021). We randomly divided data for split-sample analysis using confirmatory factor analysis (CFA), exploratory factor analysis (EFA), and the multitrait-multimethod matrix. Results Cronbach alpha was ≥0.70 for most domains. CFA using sample 1 demonstrated suboptimal fit for both instruments, including 3 negatively-worded IMMS items with particularly low loadings. Revised IMMS (RIMMS) scores (which omit negatively-worded items) demonstrated better fit. Guided by EFA, we identified a novel 3-domain, 11-item ‘MSLQ-Short Form-Revised’ (MSLQ-SFR, with domains: Interest, Self-efficacy, and Attribution) and the 4-domain, 12-item RIMMS as the best models. CFA using sample 2 confirmed good fit. Correlations among MSLQ-SFR, RIMMS, and CPQ scores aligned with predictions; correlations with knowledge scores were small. Conclusions Original MSLQ and IMMS scores show poor model fit, with negatively-worded items notably divergent. Revised, shorter models—the MSLQ-SFR and RIMMS—show satisfactory model fit (internal structure) and relations with other variables.

Electrochemically Dealloying Engineering toward Integrated Monolithic Electrodes with Superior Electrochemical Li-Storage Properties.

Integrated monolithic electrodes (IMEs) free of inactive components demonstrate great potential in boosting energy-power densities and cycling life of lithium-ion batteries. However, their practical applications are significantly limited by low active substance loading (< 4.0mgcm-2 and 1.0gcm-3), complicated manufacturing process, and high fabrication cost. Herein, employing industrial Cu-Mn alloy foil as a precursor, a simple neutral salt solution-mediated electrochemical dealloying strategy is proposed to address such problems. The resultant Cu-Mn IMEs achieve not only a significantly larger active material loading due to the in situ generated Cu2O and MnOx (ca. 16.0mgcm-2 and 1.78gcm-3), simultaneously fast transport of ions and electrons due to the well-formed nanoporous structure and built-in Cu current collector, but also high structural stability due to the interconnected ligaments and suitable free space to relieve the volume expansion upon lithiation. As a result, they demonstrate remarkable performances including large specific capacities (> 5.7mAhcm-2), remarkable pseudocapacitive effect despite the battery-type constitutes, long cycling life, and good working condition in a lithium-ion full cell. This study sheds new light on the further development of IMEs, enriches the existing dealloying techniques, and builds a bridge between the two.

Enhancing computational thinking and spatial reasoning skills in gamification programming learning: A comparative study of tangible, block and paper‐and‐pencil tools

AbstractTangible programming tools have become a mainstream teaching aid in gamification programming learning (GPL) due to their interactivity and ability to enhance novice learners' computational thinking and spatial reasoning skills. However, comparing the relative efficacy of different programming tools that simultaneously support these skills was not adequately explored. This study designed and evaluated three programming tools: the tangible programming tool (TPG), which uses real touchable objects; the block programming tool (BPG), which employs virtual programming blocks and 3D game scenarios; and the paper‐and‐pencil programming tool (PPG), which uses paper and pen to draw. The study involved 112 seventh‐grade students from three natural classes: Class A (TPG, n1=37), Class B (BPG, n2=38), and Class C (PPG, n3=37). These students completed four gamification programming tasks and CT skills, spatial reasoning skills, enjoyment, cognitive load and GPL task list measurements. The results indicated that the tangible programming tool led to lower cognitive load, significant improvement in spatial reasoning skills and better abstraction and problem decomposition skills. The block programming tool provided a more enjoyable experience and facilitated students' algorithm design and efficiency. The paper‐and‐pencil programming tool was found to be less effective in improving spatial reasoning skills. This study's findings can help programming educators cultivate students' thinking skills and improve their learning experience by effectively selecting the most appropriate programming tools.

The association between family dynamics and Positive Youth Development in secondary education students.

The Positive Youth Development (PYD) framework is a strengths-based approach to adolescence that states that adolescents will thrive if nurtured by the right developmental assets. The family is one of the most important developmental assets, but studies about the relationship between family dynamics and the overall PYD of adolescents are scarce. The present study aims to examine the associations between five family dynamics indicators and PYD, while taking into account the role of gender. A cross-sectional study was carried out with a representative sample of adolescents from the city of Huelva, Spain (n = 1,036). Data were collected in 14 randomly selected secondary education schools. A Structural Equation Model (SEM) was tested to determine the effect of family dynamics on PYD, both for the whole sample and within each gender. The SEM for the whole sample showed a positive effect of the family dynamics factor on the PYD factor, explaining 51.8% of its variance. The indicators of satisfaction with the relationship with the mother, satisfaction with the relationship with the father, frequency of engaging in joint family activities on weekends, and frequency of sharing daily occurrences at home showed factor loadings over 0.50, while the indicator of frequency of contribution to household chores had the lowest loading. The family dynamics factor in the model with the subsample of girls explained 54.8% of the variance in PYD, while in the SEM with the subsample of boys this factor explained 47.6% of it. Additionally, among girls, the relative influence of satisfaction in the relationship with the parents, as well as of frequently discussing the day at home, is higher than among boys. These results highlight a strong association between family dynamics indicators and PYD among adolescents and indicate that this relationship is stronger for girls than for boys. Intersectoral policies enhancing improvements in family dynamics (e.g., facilitating the practice of joint family activities on weekends) may have a relevant impact on PYD.

Technologically advanced running shoes reduce oxygen cost and cumulative tibial loading per kilometer in recreational female and male runners

Technologically advanced running shoes (TARS) improve performance compared to classical running shoes (CRS). Improved race performance has been attributed to metabolic savings in male runners, but it remains unclear if these same benefits are experienced among females and in recreational runners. The mechanisms behind these benefits are still not fully understood despite the need for optimisation, and their influence on injury mechanisms has not been explored. Here we combined biomechanical, physiological, and modelling approaches to analyse joint mechanics, oxygen uptake, and tibial load in nineteen male and female recreational runners running with CRS and TARS at their individual lactate threshold speed (12.4 ± 1.9 km/h). Oxygen uptake was 3.0 ± 1.5% lower in TARS than in CRS. Ankle dorsiflexion, joint moment and joint power were reduced in TARS compared to CRS at various phases of stance including midstance, while knee joint mechanics were mostly similar throughout. There were no significant differences for tibial bending moment during the stance phase but cumulative tibial damage per kilometre was 12 ± 9% lower in TARS compared to CRS. Our results suggest that running with TARS reduces oxygen cost in recreational female and male runners, which may partly be explained by differences in lower limb joint mechanics. The lower cumulative tibial bone load with TARS may allow runners to run longer distances in this type of shoe compared to CRS.