1,720,961 research outputs found
Self-assembled cellulosic superstructures with unanticipated high quantum yields
No full textAbstract Nonconventional luminophores devoid of traditional, large π-conjugates often suffer from low solid-state fluorescence quantum yields (FLQYs). In parallel, self-assembled bowl-shaped and helical architectures at the micro- and macroscale are unusual (mostly reported at the nanoscale). Here, we report that surface-stearoylated cellulose nanocrystals and cellulose stearoyl esters co-assemble into macroscale helices (FLQY: 86%) with diameters of 32−104 μm. Meanwhile, surface-lauroylated cellulose nanocrystals and cellulose lauroyl esters co-assemble into porous bowl-shaped microparticles (FLQY: 91%) with diameters of 8−19 μm. The high FLQYs are ascribed to the synergism of the dense oxygen clusters and abundant van der Waals interactions and hydrogen bonds between side stearoyl or lauroyl groups, which can promote through-space electron delocalization, ultimately improving fluorescence performance. These results were rationalized by theoretical calculations. Such superstructures exhibit great potential for stable anti-counterfeiting materials due to the excellent regeneration ability as well as structural stability of the oxygen clusters.EU:‘NEuM’China Scholarship Council https://doi.org/10.13039/501100004543Gouvernement du Canada | Natural Sciences and Engineering Research Council of Canada https://doi.org/10.13039/501100000038Alexander von Humboldt-Stiftung https://doi.org/10.13039/10000515
Self‐Powered Mechanical Nanofluidic Generators Based on Gradient Charge‐Modified Sustainable Wood‐Derived Nanochannels
No full textAbstract The growing demand for self‐powered technology in portable and wearable electronics has spurred significant advancements in energy harvesting systems. However, conventional mechanical generators based on triboelectric and piezoelectric effects are limited by short discharge durations, despite achieving high output potentials. Here, a mechanical nanofluidic generator (MNG) is reported with gradient charge‐modified nanochannels, designed for mechanical energy harvesting. The MNG features highly aligned nanochannels with engineered surface charges, enabling a peak output voltage of 10.58 ± 1.29 V and a prolonged energy release time of 675.80 ± 112.08 s, with orders of magnitude longer than traditional generators that normally discharge in milliseconds to microseconds. This superior performance is attributed to the synergistic effects of gradient surface charge modification and enhanced interactions between transport ions and surface charges. This performance is attributed to the synergistic effects of surface charge gradients and strengthened ion–surface interactions, underscoring the MNG's potential for next‐generation self‐powered systems.Natural Sciences and Engineering Research Council of Canada https://doi.org/10.13039/501100000038Alexander von Humboldt-Stiftung https://doi.org/10.13039/100005156Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659China Scholarship Council https://doi.org/10.13039/50110000454
Dehydration regulates structural reorganization of dynamic hydrogels
No full textAbstract The dehydration process is widely recognized as a significant phenomenon in nature. Hydrogels, which are important functional materials with high water content and crosslinked networks, encounter the issue of dehydration in their practical applications. Here, we report the distinctive anisotropic dehydration modality of dynamic hydrogels, which is fundamentally different from the more commonly observed isotropic dehydration of covalent hydrogels. Xerogels derived from dynamic hydrogel dehydration will fully cover a curved substrate surface and exhibit hollow structures with internal knots, in contrast to the bulk xerogels produced by covalent hydrogel dehydration. Depending on the competing cohesion of polymer chains and the adhesion at the hydrogel-substrate interface, the previously overlooked reorganization of polymer networks within dynamic hydrogels, triggered by dehydration-induced stress, has been discovered to regulate such macroscopic structural reconstruction for dynamic hydrogel dehydration. With the attached hydrogel-substrate interface, the surface microstructures of substrates can also be engraved onto xerogels with high resolution and on a large scale. This work will greatly enhance our understanding of the soft matter dehydration process and broaden the applications of dehydration technologies using water-containing materials.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Niedersächsisches Ministerium für Wissenschaft und Kultur https://doi.org/10.13039/501100010570China Scholarship Council https://doi.org/10.13039/501100004543Open-Access-Publikationsfonds 202
Solvothermal engineering of lignin-based fluorescent/phosphorescent carbon dots with tunable multicolor emission
No full texthttp://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of Chinahttp://dx.doi.org/10.13039/501100007129 Natural Science Foundation of Shandong Provincehttp://dx.doi.org/10.13039/501100000038 Natural Sciences and Engineering Research Council of Canadahttp://dx.doi.org/10.13039/501100004543 China Scholarship Councilhttp://dx.doi.org/10.13039/100005156 Alexander von Humboldt-Stiftun
Electrospun Lignin/ZnO Nanofibrous Membranes for Self‐Powered Ultrasensitive Flexible Airflow Sensor and Wearable Device
No full textAbstract The interest and demand for flexible sensors and wearable devices are rapidly growing. The added benefit of electricity generation, enabling gas sensors to be self‐powered, increases the applicability of these devices for flexible and wearable airflow sensors. Inspired by water evaporation‐induced power generation, this study explores its potential in sensing applications, which has not yet been explored in detail. Electrospinning technology is used to prepare superhydrophilic lignin/ZnO nanofibrous membranes with a ZnO nanoparticle layer, capable of generating at least 100 mV (which allows it to power its own signal transduction). The membrane is highly sensitive to variations in airflow, enabling its use as an ultrasensitive and flexible airflow sensor. This sensor demonstrates exceptional performance, including a fast response time (0.65 s), broad detection range (with lower detection limit down to 0.25 and upper detection limit of 3 m s −1 ), and extremely high airflow velocity detection accuracy. Beyond these, it can serve as a wearable sensor for sweat monitoring, motion detection, and breath monitoring (to accurately detect breathing rate, intensity and variations in speech). Such self‐powered, ultrasensitive, and flexible lignin/ZnO airflow sensors provide novel potential to advance the development of smart textiles and wearable electronics.Natural Sciences and Engineering Research Council of Canada https://doi.org/10.13039/501100000038Alexander von Humboldt-Stiftung https://doi.org/10.13039/100005156Deutsche Forschungsgemeinschaft https://doi.org/10.13039/50110000165
Design of Hydrogel Electrolytes Using Strong Bacterial Cellulose with Weak Ionic Interactions
No full textSelf‐assembled small molecule spherulites under mild conditions: High solid‐state quantum yield and unique interconnected structural and fluorescent colors
No full textOpen-Access-Publikationsfonds 202
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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