Controlled synthesis and appropriate characterization of nanoscale particles of gallium-based liquid metals are critical to fulfilling their broad range of applications in the field of flexible, stretchable, and printable micro-/nanoelectronics. Herein, we report a new way to synthesize surfactant-free gallium-indium nanoparticles with controlled particle size on a variety of substrates through a facile physical vapor deposition method. It was found that with prolonged deposition time the liquid metal nanoparticles gradually grew from near-monodispersed small particles with a diameter of ~25 nm to bimodal distributed particles. A nucleation, growth, ripening and merging process was proposed to explain the observed evolution of particle size. Atomic force microscopy measurement indicates that the fabricated liquid metal nanoparticles demonstrate elastic deformation with a certain range of loads and the scanned particle size is dependent on the applied loads. We further investigated the gradual breaking process of the core-shell structured liquid metal nanoparticles, which was evidenced by multiple kinks on the force-separation curve. This work presents a new bottom-up approach to prepare nanoscale liquid metal particles and demonstrates that atomic force microscopy is a suitable technique to characterize the synthesized liquid metal nanoparticles.
Abstract Bionic condensate microdrop self‐propelling (CMDSP) surfaces are attracting intensive interest due to their academic and commercial values. Up to now, it is still a great challenge to design and fabricate CMDSP nanostructures with superior condensation heat transfer (CHT) efficiency. Here, it is reported that the CHT coefficient of copper surfaces can be enhanced maximally ≈320% via in situ growth and geometric regulation of closely packed aligned nanoneedles with CMDSP function. These experiments and theoretical analyses indicate that reducing the interspaces of nanoneedles can help reduce the departure diameters of condensate microdrops and increase their nucleation density, both of which are beneficial to enhance CHT. In contrast, increasing the tip size and height of nanoneedles can increase drop departure diameters and film‐layer thermal resistance, respectively, either of which is disadvantageous to enhance CHT. Clearly, only considering superhydrophobic effect is insufficient and both choosing ideal nanoarchitectures and optimizing their geometric parameters are very crucial to realize high‐efficiency CHT, which optimization can be achieved via simply controlling growth time of nanostructures. These findings offer new insights into the design and development of first‐rank CHT interface nanomaterials.
This study proposed a new process to fabricate the sensing unit of an electrochemical seismometer using only one silicon wafer. Based on this new fabrication process, the effective area of electrodes and the fabrication efficiency were significantly improved. In this study, the SU-8 negative photoresist was utilized as both the substrate (exposed SU-8) and the sacrificial layer (unexposed SU-8) on top of which the suspended platinum electrodes were fabricated using the positive-photoresist lift-off technology. The performances of the proposed devices were characterized experimentally where compared to the commercially available counterpart CME6011, significant improvements in 3 dB working bandwidth (0.11 Hz ∼21.50 Hz vs. 0.47 Hz ∼18.24 Hz) and device sensitivity (1592V/(m/s) vs. 820 V/(m/s)) were located.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Tuning the plasma field in reactive ion etching generates different etching profile of nanoparticles. For nanoparticles in an isotropic plasma field, there will be uniform shrinkage of the particle sizes due to the isotropic etching, with the curvature of the particles unchanged after the etching. An anisotropic etching, on the other hand, provides rich opportunities to modify the shape of the particles with reduced dimensions. For a monolayer of silica nanoparticles on a flat substrate in a unidirectional plasma field, the reactive ion etching changed the shape of silica nanoparticles from spherical to spheroid-like geometry. The mathematical description of the final spheroid-like geometry was discussed and matched well with the experimental results. The surface curvature of the particles after etching remained the same for both the top and the bottom surfaces, while the overall shape transformed to spheroid-like geometry. Varying the etching time resulted in particles with different height to width ratios. The unique geometry of these non-spherical particles will impact fundament properties of such particles, such as packing and assembly. In the case of spheroid-like particles, packing of such particles into ordered structures will involve an orientational order, which is different from spherical nanoparticles that have no orientational order.
Electrochemical CO2 reduction (ECR) into syngas is a promising method to reduce CO2 in the atmosphere. However, balancing the activity of ECR and hydrogen evolution reaction (HER) and controlling the stable CO/H2 ratios in a large potential range for the industrial desired syngas are still challenging. Herein, a low-cost Ni-doped ZnO nanosheet array on a zinc foil is synthesized via a convenient hydrothermal method to produce a controllable ratio of CO/H2 into syngas. Because of the lower impedance and larger electrochemical area, Ni-doped ZnO has a more significant current density. Furthermore, by adjusting the Ni doping content in the ZnO nanosheet, the activity of ECR and HER could be controlled, and the ratio of CO/H2 can be tuned from 0.1 to 4.5 over a wide potential range (−1.2 to −1.8 V vs reversible hydrogen electrode, RHE), surpassing most of the reported work. Such a wide range and stable ratio of CO/H2 in a broad potential range makes it possible to convert CO2 into feedstock for many essential chemical products.
This work reports a bioinspired three-dimensional (3D) heterogeneous structure for optical hydrogen gas (H2) sensing. The structure was fabricated by selective modification of the photonic architectures of Morpho butterfly wing scales with Pd nanostrips. The coupling of the plasmonic mode of the Pd nanostrips with the optical resonant mode of the Morpho biophotonic architectures generated a sharp reflectance peak in the spectra of the Pd-modified butterfly wing, as well as enhancement of light-matter interaction in Pd nanostrips. Exposure to H2 resulted in a rapid reversible increase in the reflectance of the Pd-modified butterfly wing, and the pronounced response of the reflectance was at the wavelength where the plasmonic mode strongly interplayed with the optical resonant mode. Owing to the synergetic effect of Pd nanostrips and biophotonic structures, the bioinspired sensor achieved an H2 detection limit of less than 10 ppm. Besides, the Pd-modified butterfly wing also exhibited good sensing repeatability. The results suggest that this approach provides a promising optical H2 sensing scheme, which may also offer the potential design of new nanoengineered structures for diverse sensing applications.
DNA cages are ideally suited to make nanostructures which serve as containers for drug delivery. Using fewer strands to assemble DNA cages is of importance to the design of DNA molecules with multiple component strands. In this study, we propose a rational assembling procedure to design and analyze DNA bipyramids with minimum strands. The results show that the odd-half twist has a major impact on assembling strands required to construct DNA cages and this method could offer a search of DNA bipyramids with minimum component strands faster. This research provides new insights into design and synthesis for DNA bipyramid-like cages from mathematical perspective.
The educational system in Sulaymaniyah, Iraq, faces significant challenges due to political instability, economic hardships, and conflict. These factors contribute to the stress and burnout experienced by secondary school teachers, affecting their occupational well-being. This research aims to investigate the relationship between social support and work engagement on teachers' occupational well-being, with the objectives of understanding how these factors interact and proposing strategies to enhance teachers' occupational well-being. Employing a mixed-methods approach, the study utilized the Norbeck Social Support Questionnaire, the NIOSH Questionnaire, and the Utrecht Work Engagement Scale to collect quantitative data from 120 secondary school teachers in Sulaymaniyah. Qualitative data were gathered through semi- structured interviews with a subset of 15 participants. The data were analyzed using SPSS 25 software for quantitative analysis and thematic analysis for qualitative insights. The results revealed a positive correlation between social support and work engagement with teachers' occupational well-being. Work engagement was found to mediate the relationship between social support and occupational well-being. Teachers expressed that a supportive work environment, opportunities for professional growth, and recognition contribute significantly to their job satisfaction and overall well-being. To promote teachers' occupational well-being, it is recommended that schools and policymakers focus on creating a supportive work culture, providing opportunities for professional development, and recognizing teachers' efforts. Implementing mentorship programs, facilitating collaborative learning communities, and offering incentives can further enhance teachers' work engagement and occupational well-being.
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