This study examined gender differences in student engagement and academic performance in school. Participants included 3420 students (7th, 8th, and 9th graders) from Austria, Canada, China, Cyprus, Estonia, Greece, Malta, Portugal, Romania, South Korea, the United Kingdom, and the United States. The results indicated that, compared to boys, girls reported higher levels of engagement in school and were rated higher by their teachers in academic performance. Student engagement accounted for gender differences in academic performance, but gender did not moderate the associations among student engagement, academic performance, or contextual supports. Analysis of multiple-group structural equation modeling revealed that perceptions of teacher support and parent support, but not peer support, were related indirectly to academic performance through student engagement. This partial mediation model was invariant across gender. The findings from this study enhance the understanding about the contextual and personal factors associated with girls' and boys' academic performance around the world.peer-reviewe

2D materials are of particular interest in light‐to‐heat conversion, yet challenges remain in developing a facile method to suppress their light reflection. Herein, inspired by the black scales of Bitis rhinoceros, a generalized approach via sequential thermal actuations to construct biomimetic 2D‐material nanocoatings, including Ti3C2Tx MXene, reduced graphene oxide (rGO), and molybdenum disulfide (MoS2) is designed. The hierarchical MXene nanocoatings result in broadband light absorption (up to 93.2%), theoretically validated by optical modeling and simulations, and realize improved light‐to‐heat performance (equilibrium temperature of 65.4 °C under one‐sun illumination). With efficient light‐to‐heat conversion, the bioinspired MXene nanocoatings are next incorporated into solar steam‐generation devices and stretchable solar/electric dual‐heaters. The MXene steam‐generation devices require much lower solar‐thermal material loading (0.32 mg cm−2) and still guarantee high steam‐generation performance (1.33 kg m−2 h−1) compared with other state‐of‐the‐art devices. Additionally, the mechanically deformed MXene structures enable the fabrication of stretchable and wearable heaters dual‐powered by sunlight and electricity, which are reversibly stretched and heated above 100 °C. This simple fabrication process with effective utilization of active materials promises its practical application value for multiple solar–thermal technologies.

The objective of the present study was to develop a scale that is appropriate for use internationally to measure affective, behavioral, and cognitive dimensions of student engagement. Psychometric properties of this scale were examined with data of 3,420 students (7th, 8th, and 9th grade) from 12 countries (Austria, Canada, China, Cyprus, Estonia, Greece, Malta, Portugal, Romania, South Korea, the United Kingdom, and the United States). The intraclass correlation of the full-scale scores of student engagement between countries revealed that it was appropriate to aggregate the data from the 12 countries for further analyses. Coefficient alphas revealed good internal consistency. Test-retest reliability coefficients were also acceptable. Confirmatory factor analyses indicated that the data fit well to a second-order model with affective, behavioral, and cognitive engagement as the first-order factors and student engagement as the second-order factor. The results support the use of this scale to measure student engagement as a metaconstruct. Furthermore, the significant correlations of the scale with instructional practices, teacher support, peer support, parent support, emotions, academic performance, and school conduct indicated good concurrent validity of the scale. Considerations and implications regarding the international use of this student engagement in school measure are discussed.

In the emerging Internet of Things, stretchable antennas can facilitate wireless communication between wearable and mobile electronic devices around the body. The proliferation of wireless devices transmitting near the human body also raises interference and safety concerns that demand stretchable materials capable of shielding electromagnetic interference (EMI). Here, an ultrastretchable conductor is fabricated by depositing a crumple-textured coating composed of 2D Ti 3 C 2 T x nanosheets (MXene) and single-walled carbon nanotubes (SWNTs) onto latex, which can be fashioned into high-performance wearable antennas and EMI shields. The resulting MXene-SWNT (S-MXene)/latex devices are able to sustain up to an 800% areal strain and exhibit strain-insensitive resistance profiles during a 500-cycle fatigue test. A single layer of stretchable S-MXene conductors demonstrate a strain-invariant EMI shielding performance of ≈30 dB up to 800% areal strain, and the shielding performance is further improved to ≈47 and ≈52 dB by stacking 5 and 10 layers of S-MXene conductors, respectively. Additionally, a stretchable S-MXene dipole antenna is fabricated, which can be uniaxially stretched to 150% with unaffected reflected power <0.1%. By integrating S-MXene EMI shields with stretchable S-MXene antennas, a wearable wireless system is finally demonstrated that provides mechanically stable wireless transmission while attenuating EM absorption by the human body.existing mobile devices. [1] To enable highperformance wireless communication between wearable sensors, displays, and data processing devices around the body, new routes to fabricating for stretchable antennas that exhibit mechanically stable performance are needed. Furthermore, the proliferation of mobile and wearable devices based on various wireless technologies, including GPS, Bluetooth, Wi-Fi, and near-field communication, is increasing the frequency and duration of the human body exposed to electromagnetic (EM) fields, which raises interference and safety concerns that may require certain suitable materials for EM protection. [2] Therefore, in addition to the growing demand for stretchable antennas, electromagnetic interference (EMI) shielding materials that are stretchable, durable, and can be integrated closely with wearable wireless technologies are needed to reduce the exposure of the human body to EM fields. Integrating such stretchable antennas with on-site EMI shields not only provides protection against EM fields, but also prevents unauthorized wireless transmission between wearable electronics and mobile devices for enhanced wireless privacy.Both wearable antennas and stretchable EMI shields face similar technological challenges, where the key materials awaiting to be developed are the stretchable conductors with high strain tolerance and strain-invariant electrical conductivities.Metals (e.g., Cu and Al) are the conventionally used materials for EMI shields and antennas on many occasions. As the trend in today's electronic devices becomes faster, lighter, and...

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Tuning surface strain is a new strategy for boosting catalytic activity to achieve sustainable energy supplies; however, correlating the surface strain with catalytic performance is scarce because such mechanistic studies strongly require the capability of tailoring surface strain on catalysts as precisely as possible. Herein, a conceptual strategy of precisely tuning tensile surface strain on Co S /MoS core/shell nanocrystals for boosting the hydrogen evolution reaction (HER) activity by controlling the MoS shell numbers is demonstrated. It is found that the tensile surface strain of Co S /MoS core/shell nanocrystals can be precisely tuned from 3.5% to 0% by changing the MoS shell layer from 5L to 1L, in which the strained Co S /1L MoS (3.5%) exhibits the best HER performance with an overpotential of only 97 mV (10 mA cm ) and a Tafel slope of 71 mV dec . The density functional theory calculation reveals that the Co S /1L MoS core/shell nanostructure yields the lowest hydrogen adsorption energy (∆E ) of -1.03 eV and transition state energy barrier (∆E ) of 0.29 eV (MoS , ∆E = -0.86 eV and ∆E = 0.49 eV), which are the key in boosting HER activity by stabilizing the HER intermediate, seizing H ions, and releasing H gas.

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Two-dimensional MXene materials have demonstrated attractive electrical and electrochemical properties in energy storage applications. Adding stretchability to MXene remains challenging due to its high mechanical stiffness and weak intersheet interaction, so the assembling techniques for mechanically stable MXene architectures require further development. We report a simple fabrication by harnessing the interfacial instability to generate higher dimensional MXene nanocoatings capable of programmed crumpling/unfolding. A sequential patterning approach enabled the design of sequence-dependent MXene textures across multiple length scales, which were utilized for controllable wetting surfaces and high-areal-capacitance electrodes. We next transferred the crumpled MXene nanocoating onto an elastomer to fabricate an MXene/elastomer electrode with high stretchability. The accordion-like MXene can be reversibly folded/unfolded and still preserve efficient specific capacitances. We further fabricated asymmetric MXene supercapacitors, and the devices demonstrated efficient electrochemical performance and large deformability (180° bendability, 100% stretchability). Our texturing techniques can be applied to large MXene families for designing stretchable architectures in wearable electronics.