The ever-increasing energy demand and fossil energy consumption accompanied by the worsening environmental pollution urge the invention and development of new, environmentally friendly and renewable ...high-performance energy devices. Among them, the supercapacitor has received massive attention, and the various electrode materials and polymer electrolytes have been exploited. The carbon-based electrodes and electrolytes derived from biomass are highly trusted as idea candidates for supercapacitors due to their attractive structure, abundance, low cost, renewability, and environmentally friendliness. This review will highlight the available characteristics of materials, synthetic strategies, and improvement approach of biomass-derived electrodes and electrolytes for application in supercapacitors. Future relative research trends also will be briefly discussed.
Nowadays, it has become a trend to prepare porous carbon as electrode materials for supercapacitors by using biomass and its derivatives by virtue of its low cost, abundant source and environmental ...friendliness. Carboxymethyl cellulose ammonium (CMC-NH
4
), a kind of cellulose derivative, is used as a carbon precursor and O/N source to prepare carbon material through cross-linking with aluminum ions, lyophilization, carbonization and activation. The as-prepared O/N-co-doped carbon samples (ONAC-500, ONAC-600 and ONAC-700) exhibit hierarchically porous structure with different size pores in carbon framework, ensuring electrolyte ions effective transport and diffusion. Meanwhile, the ONAC-600 reveals a high specific surface area of 2658 m
2
g
−1
, abundantly porous structure with pore volume of 1.32 cm
3
g
−1
and effective O/N-doping, which ensure a high capacitance of 465.0 F g
−1
at 1 A g
−1
in 3 M KOH three-electrode system. It also shows better rate capability and good stability after 10000 cycled under 10 A g
−1
. Besides, the assembled all-solid-state supercapacitor with ONAC-600 delivers an acceptable energy density of 7.8 Wh kg
−1
at a power density of 124.2 W kg
−1
.
•Enhanced brain activation was found in drug cue than sexual cue in heroin users.•Functional couplings of the left DLPFC were revealed during drug cue processing.•Drug cue induced brain response ...predicted craving changes after prolonged abstinence.
Loss of control over drug intake occurring in drug addiction is believed to result from disruption of reward circuits, including reduced responsiveness to natural rewards (e.g., monetary, sex) and heightened responsiveness to drug reward. Yet few studies have assessed reward deficiency and related brain responses in abstinent heroin users with opioid use disorder, and less is known whether the brain responses can predict cue-induced craving changes following by prolonged abstinence.
31 heroin users (age: 44.13±7.68 years, male: 18 (58%), duration of abstinence: 85.2 ± 52.5 days) were enrolled at a mandatory detoxification center. By employing a cue-reactivity paradigm including three types of cues (drug, sexual, neutral), brain regional activations and circuit-level functional coupling were extracted. Among the 31 heroin users, 15 were followed up longitudinally to assess cue induced craving changes in the ensuing 6 months.
One way analysis of variance results showed that heroin users have differential brain activations to the three cues (neutral, drug and sexual) in the left dorsolateral prefrontal cortex (DLPFC), insula, orbiotofrontal cortex (OFC) and the bilateral thalamus. Drug cue induced greater activations in left DLPFC, insula and OFC compared to sexual cue. The psychophysiological interactions (PPI) analysis revealed negative couplings of the left DLPFC and the left OFC, bilateral thalamus, putamen in heroin users during drug cue exposure. In the 6-month follow-up study, both drug cue induced activation of the left DLPFC and the functional coupling of the left DLPFC-bilateral thalamus at baseline was correlated with craving reductions, which were not found for sexual cues.
Our preliminary study provided novel evidence for the reward deficiency theory of opioid use disorder. Our findings also have clinical implications, as drug cue induced activation of the left DLPFC and functional coupling of left DLPFC-bilateral thalamus may be potential neuroimaging markers for craving changes during prolonged abstinence. Evidently, the findings in the current preliminary study should be confirmed by large sample size in the future.
Cellulose nanofibers (CNFs) paper with low thermal expansion and electrolyte absorption properties is considered to be a good potential substrate for supercapacitors. Unlike traditional substrates, ...such as glass or plastic, CNFs paper saves surfaces pretreatment when Layer-by-Layer (LbL) assembly method is used. In this study, negatively charged graphene oxide (GO) nanosheets and poly(3,4-ethylenedioxythiophene: poly(styrene sulfonate)) (PEDOT:PSS) nanoparticles are deposited onto CNFs paper with positively charged polyaniline (PANI) nanowires as agents to prepare multilayer thin film electrodes, respectively. Due to the different nanostructures of reduced graphene oxide (RGO) and PEDOT:PSS, the microstructures of the electrodes are distinguishing. Our work demonstrate that CNFs paper/PANI/RGO electrode provides a more effective pathway for ion transport facilitation compared with CNFs paper/PANI/PEDOT:PSS electrode. The supercapacitor fabricated by CNFs/PANI-RGO8 (S-PG-8) exhibits an excellent areal capacitance of 5.86 mF cm-2 at a current density of 0.0043 mA cm-2, and at the same current density the areal capacitance of the supercapacitor fabricated by CNFs/PANI-PEDOT:PSS8 (S-PP-8) is 4.22 mF cm-2. S-PG-8 also exhibits good cyclic stability. This study provides a novel method using CNFs as substrate to prepare hybrid electrodes with diverse microstructures that are promising for future flexible supercapacitors.
As a result of inherent rigidity of the conjugated macromolecular chains resulted from the delocalized π-electron system along the polymer backbone, it has been a huge challenge to make conducting ...polymer hydrogels elastic by far. Herein elastic and conductive polypyrrole hydrogels with only conducting polymer as the continuous phase have been simply synthesized in the indispensable conditions of 1) mixed solvent, 2) deficient oxidant, and 3) monthly secondary growth. The elastic mechanism and oxidative polymerization mechanism on the resulting PPy hydrogels have been discussed. The resulting hydrogels show some novel properties, e.g., shape memory elasticity, fast functionalization with various guest objects, and fast removal of organic infectants from aqueous solutions, all of which cannot be observed from traditional non-elastic conducting polymer counterparts. What's more, light-weight, elastic, and conductive organic sponges with excellent stress-sensing behavior have been successfully achieved via using the resulting polypyrrole hydrogels as precursors.
•CNFs-based flexible transparent conductive paper was successfully prepared.•Optoelectronic properties of paper can be controlled by the times of LbL assembly.•Transparent conductive paper has good ...optoelectronic properties.•Transparent conductive paper has excellent flexibility and mechanical properties.
The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu2+) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/RGO20 paper has the sheet resistances of ∼2.5kΩ/□, and the transmittance of about 76% at a wavelength of 550nm. Furthermore, CNFs/RGO20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility.
Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-RGOn hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO ...nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm(-2)), and a transmittance of about 56% (at 550 nm).
We report an
in-situ
fabrication of halide perovskite (CH
3
NH
3
PbX
3
, CH
3
NH
3
= methylammonium, MA, X= Cl, Br, I) nanocrystals in polyvinylalcohol (PVA) nanofibers (MAPbX
3
@PVA nanofibers) ...through electrospinning a perovskite precursor solution. With the content of the precursors increased, the resulting MAPbBr
3
nanocrystals in PVA matrix changed the shape from ellipsoidal to pearl-like, and finely into rods-like. Optimized MAPbBr
3
@PVA nanofibers show strong polarized emission with the photoluminescence quantum yield of up to 72%. We reveal correlations between the shape of
in-situ
fabricated perovskite nanocrystals and the polarization degree of their emission by comparing experimental data from the single nanofiber measurements with theoretical calculations. Polarized emission of MAPbBr
3
@PVA nanofibers can be attributed to the dielectric confinement and quantum confinement effects. Moreover, nanofibers can be efficiently aligned by using parallel positioned conductor strips with an air gap as collector. A polarization ratio of 0.42 was achieved for the films of well-aligned MAPbBr
3
@PVA nanofibers with a macroscale size of 0.5 cm × 2 cm, which allows potential applications in displays, lasers, waveguides, etc.
Metagenomic next-generation sequencing (mNGS) and droplet digital PCR (ddPCR) have recently demonstrated a great potential for pathogen detection. However, few studies have been undertaken to compare ...these two nucleic acid detection methods for identifying pathogens in patients with bloodstream infections (BSIs). This prospective study was thus conducted to compare these two methods for diagnostic applications in a clinical setting for critically ill patients with suspected BSIs. Upon suspicion of BSIs, whole blood samples were simultaneously drawn for ddPCR covering 20 common isolated pathogens and four antimicrobial resistance (AMR) genes, mNGS, and blood culture. Then, a head-to-head comparison was performed between ddPCR and mNGS. A total of 60 episodes of suspected BSIs were investigated in 45 critically ill patients, and ddPCR was positive in 50 (83.3%), mNGS in 41 (68.3%, not including viruses), and blood culture in 10 (16.7%) episodes. Of the 10 positive blood cultures, nine were concordantly identified by both mNGS and ddPCR methods. The head-to-head comparison showed that ddPCR was more rapid (~4 h vs. ~2 days) and sensitive (88 vs. 53 detectable pathogens) than mNGS within the detection range of ddPCR, while mNGS detected a broader range of pathogens (126 vs. 88 detectable pathogens, including viruses) than ddPCR. In addition, a total of 17 AMR genes, including 14
bla
KPC
and 3
mecA
genes, were exclusively identified by ddPCR. Based on their respective limitations and strengths, the ddPCR method is more useful for rapid detection of common isolated pathogens as well as AMR genes in critically ill patients with suspected BSI, whereas mNGS testing is more appropriate for the diagnosis of BSI where classic microbiological or molecular diagnostic approaches fail to identify causative pathogens.
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