Carbon nanofibers (CNFs) and carbon nanotubes have revolutionized the world of the nanotechnology due to their excellent mechanical, electrical and thermal properties. CNFs are graphitic fibers made ...of stacks of graphene layers aligned perpendicular, tilted or parallel to the fiber axis, thus resulting in different microstructures. Post-production treatments can be applied to CNFs to improve their performance in several applications. Among them, the heat treatment at high temperature to achieve the transformation of the CNFs into graphite (graphitization) or graphitized CNFs (graphitization heat treatment) has been studied in detail. This review covers the literature on this topic for the last 20years, analyzing the structural and textural changes shown by the CNFs during graphitization, and how these changes influence their mechanical and electrical properties. Different techniques, particularly, high-resolution transmission electron microscopy, have allowed to determine the microstructure of these nanofilaments. A survey of the applications of graphitized CNFs is provided, these including additives for polymer reinforcement in composites, anodes in lithium-ion batteries, catalyst supports in fuel cells, hydrogen storage and others such as potential biosensors and catalysts in diverse reactions. In this regard, special emphasis is placed on the advantages (or disadvantages) of using graphitized CNFs instead of as-grown CNFs.
The intercalation of PF6− anions in graphite from various sodium salt-based electrolytes with organic carbonate mixtures as solvents is investigated. The purpose was to optimize the electrochemical ...performance of the graphite as cathode in terms of specific capacity, capacity stability, and coulombic efficiency to be coupled in the future with a hard carbon-based anode in a full sodium dual-ion battery. To this end, a detailed study was made of the influence of applied current density, upper cut-off voltage (UCOV), and electrolyte—in terms of both salt concentration and solvent mixture—on the intercalation/de-intercalation of PF6− anions in the graphite cathode. Low (37.2 mA g−1) and high (372.0 mA g−1) currents, UCOVs from 4.8 to 5.2 V, electrolytes with NaPF6 salt concentrations in the range of 0.2–1.2M and EC:DEC, EC:DMC and EC:EMC solvent mixtures were studied. The best graphite cathode performance was attained in 1.2MNaPF6/EC:EMC electrolyte at the highest current density of 372.0 mA g−1 and for the potential range between 2.9 and 5.0 V vs. Na/Na+. In these conditions, a discharge capacity of 79 mAh g−1 after 1000 cycles with a coulombic efficiency of 99 % and a remarkable capacity retention throughout cycling were determined.
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Exploiting the light-matter interplay to realize advanced light responsive multimodal platforms is an emerging strategy to engineer bioinspired systems such as optoelectronic synaptic devices. ...However, existing neuroinspired optoelectronic devices rely on complex processing of hybrid materials which often do not exhibit the required features for biological interfacing such as biocompatibility and low Young's modulus. Recently, organic photoelectrochemical transistors (OPECTs) have paved the way towards multimodal devices that can better couple to biological systems benefiting from the characteristics of conjugated polymers. Neurohybrid OPECTs can be designed to optimally interface neuronal systems while resembling typical plasticity-driven processes to create more sophisticated integrated architectures between neuron and neuromorphic ends. Here, an innovative photo-switchable PEDOT:PSS was synthesized and successfully integrated into an OPECT. The OPECT device uses an azobenzene-based organic neuro-hybrid building block to mimic the retina's structure exhibiting the capability to emulate visual pathways. Moreover, dually operating the device with opto- and electrical functions, a light-dependent conditioning and extinction processes were achieved faithful mimicking synaptic neural functions such as short- and long-term plasticity.
This work reports the synthesis and characterization of three novel carbazole-based push-pull dyes that have been purposely designed to be applied in p-type dye-sensitized solar cells (DSSCs). By ...using the same electron-donor moiety (the carbazole group) and three different electron acceptor groups, we explore how these new substituents affect the optical and electrochemical properties of the dye. State-of-the-art theoretical characterization at the DFT and TD-DFT levels of theory provides the means to understand and elucidate the connection between the chemical composition, the structure and the electronic features of these dyes. The interface between the dyes and the prototypical p-DSSC electrode (i.e. NiO) is also investigated by first-principles calculations, highlighting the importance of taking into account the dye/electrode mutual polarization for a correct alignment of the relevant electronic states (e.g., dye HOMO and NiO valence band edge). Following these characterizations, preliminary studies on the photoelectrochemical performances of the new dyes in p-DSSCs provide promising results and motivate future investigations on these new systems.
Perennial crops, such as fruit trees, are infected by many viruses, which are transmitted through vegetative propagation and grafting of infected plant material. Some of these pathogens cause severe ...crop losses and often reduce the productive life of the orchards. Detection and characterization of these agents in fruit trees is challenging, however, during the last years, the wide application of high-throughput sequencing (HTS) technologies has significantly facilitated this task. In this review, we present recent advances in the discovery, detection, and characterization of fruit tree viruses and virus-like agents accomplished by HTS approaches. A high number of new viruses have been described in the last 5 years, some of them exhibiting novel genomic features that have led to the proposal of the creation of new genera, and the revision of the current virus taxonomy status. Interestingly, several of the newly identified viruses belong to virus genera previously unknown to infect fruit tree species (e.g.,
,
) a fact that challenges our perspective of plant viruses in general. Finally, applied methodologies, including the use of different molecules as templates, as well as advantages and disadvantages and future directions of HTS in fruit tree virology are discussed.
Great efforts focus on early detection of autism spectrum disorder, although some scientists and policy-makers have questioned early universal screening. The aim of this meta-analysis was to evaluate ...the diagnostic accuracy of the different screening tools. Several electronic databases were used to identify published studies. A Bayesian model was used to estimate the screening accuracy. The pooled sensitivity was 0.72 (95% CI 0.61–0.81), and the specificity was 0.98 (95% CI 0.97–0.99). Subgroup analyses to remove heterogeneity indicated sensitivity was 0.77 (95% CI 0.69–0.84), and specificity was 0.99 (95% CI 0.97–0.99; SD ≤ 0.01). Level 1 screening tools for ASD showed consistent statistically significant results and therefore are adequate to detect autism at 14–36 months.
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