Along with the progress of nanoscience and nanotechnology, nanomaterials with attractive structural and functional properties have gained more attention than ever before, especially in the field of ...electronic sensors. In recent years, the gas sensing devices have made great achievement and also created wide application prospects, which leads to a new wave of research for designing advanced sensing materials. There is no doubt that the characteristics are highly governed by the sensitive layers. For this reason, important advances for the outstanding, novel sensing materials with different dimensional structures including 0D, 1D, 2D, and 3D are reported and summarized systematically. The sensing materials cover noble metals, metal oxide semiconductors, carbon nanomaterials, metal dichalcogenides, g‐C3N4, MXenes, and complex composites. Discussion is also extended to the relation between sensing performances and their structure, electronic properties, and surface chemistry. In addition, some gas sensing related applications are also highlighted, including environment monitoring, breath analysis, food quality and safety, and flexible wearable electronics, from current situation and the facing challenges to the future research perspectives.
A comprehensive overview of recent progress on gas sensors based on various functional materials varying from 0D to 3D is provided. The multifunctional sensing applications, including environmental monitoring, breath analysis, food quality and safety, and flexible, wearable electronics are summarized. In addition, the recent development and further challenge are also discussed and highlighted.
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•Bi2S3 and BiVO4 are introduced into graphene aerogel to construct the heterojunction.•Simultaneous removal of Cr(VI) and BPA is efficient by adsorption and photocatalysis.•The ...practical water samples can be treated by the SVGA with a satisfactory result.•A mechanism for the transfer of photogenerated carriers is proposed.
Rational design strategy and facile synthesis method of photocatalysts with high efficiency and stability have been still a significant challenge for the removal of environmental contaminants. In this study, a three dimensional (3D) all-solid-state Z-scheme heterojunction photocatalytic system containing bismuth sulphide (Bi2S3) and bismuth vanadate (BiVO4) was constructed as Bi2S3-BiVO4 graphene aerogel (SVGA) by a facile hydrothermal method. The potential application of as-synthesized SVGA was demonstrated to remove Cr(VI) and bisphenol A (BPA) simultaneously in aqueous media via the synergy of adsorption and photocatalysis under visible light irradiation. The removal rates of Cr(VI) and BPA both nearly reached 100% after adsorption for 40 min and photocatalysis for 120 min under visible light (λ > 420 nm), which was much better than the removal efficiency of individual Bi2S3 and BiVO4, as well as Bi2S3 graphene aerogel (SGA) and BiVO4 graphene aerogel (VGA) samples. The rGO played an important role as photoinduced electron transfer mediator between Bi2S3 and BiVO4, which promoted the photogenerated electrons transfer efficiency and enhanced photocatalytic ability of SVGA efficiently. The harmful Cr(VI) was conserved into hypotoxic Cr(III) and BPA was degraded into CO2 and H2O after photocatalysis on SVGA, and the fabricated SVGA also presented favorable stability and satisfactory application effect in practical water samples, implied that such photocatalyst has a promising application for simultaneous removal of heavy metals and organics from aqueous environment.
A porous nanosheet-assembled hierarchical Co3O4-based sensing platform exhibits a selective response/recovery toluene behavior at a working temperature of 180 °C.
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•The construction of ...Co3O4 nanoparticles into a pore-rich nanostructure is reported.•The surface structure can be tailored by initial concentration of reactant.•The nanosheets-assembly sensing layer achieves a highest sensitivity.•Gas sensors are able to retain 88% of this sensitivity after 30 days.
Rational structure design of sensing materials plays a crucial part in fabricating high performance gas sensors. In this work, three Co3O4 samples with different morphologies, including Co3O4-C (Cube-shaped Co3O4), Co3O4-R (Rod-shaped Co3O4) and Co3O4-S (Sheet-shaped Co3O4), were synthesized through a hydrothermal route. Hierarchical structures-dependent gas-sensing properties were further investigated. The toluene sensing performance of Co3O4-S hierarchical structure-based sensor outperforms the other two ones. It exhibited higher sensitivity, faster response-recovery speed and better selectivity to toluene at the working temperature of 180 °C. In addition, the Co3O4-S-based gas sensor can maintain its sensitivity to toluene after one month, suggesting it good reliability. Preliminary functional tests for the detection of toxic analytes indicated it can be considered as a promising candidate for applications in detecting toluene.
Advanced sensing materials are in high demand for sensitive, real-time, and continuous detection of gas molecules for gas sensors, which have been becoming an effective tool for environmental ...monitoring and disease diagnosis. Cobalt-containing spinel oxides are promising sensing materials for the gas-sensing reaction owing to their element abundance and remarkable activity. Structural and component properties can be modulated to optimize the sensing performances by substituting Co with other transition metals. Herein, a systematic study of spinel MCo2O4 oxides (M = Mn, Ni, and Zn) toward gas sensing is presented. Results show that ZnCo2O4 materials with a multishelled hollow twin-sphere structure obtained excellent sensing performances to formaldehyde and acetone at different temperatures. The replacement of Co with Zn in the lattice improves the oxygen-chemisorbing ability, which allows new opportunities to synthesize and design highly sensitive chemical sensors.
Investigation of the neural mechanisms underlying social hierarchy requires a reliable and effective behavioral test. The tube test is a simple and robust behavioral assay that we recently validated ...as a reliable measure of social hierarchy in mice. The test was demonstrated to produce results largely consistent with the results seen when using other dominance measures, including the warm spot test, territory urine marking or the courtship ultrasound vocalization test. Here, we describe a step-by-step procedure to use the tube test to measure dominance within a cage of four male C57/BL6 mice as an example application. The procedure comprises three stages: habituation, training to pass through the tube, and the tube test itself. The social rank of each mouse is determined by the number of wins it gains when competing against the other three cagemates. A stable rank is derived when all mice maintain the same ranking for 4 consecutive days. The time required to acquire a stable rank usually varies from 4 to 14 d. An additional 5 d is required for habituation and training.
Colorimetric assays have drawn increasing research interest with respect to the quantitative detection of hydrogen peroxide (H2O2) based on artificial enzymes because of their advantages with respect ...to natural enzymes, including design flexibility, low cost, and high stability. Regardless, the majority of the artificial enzymes exhibit low affinity to H2O2 with large Michaelis–Menten constants (K m). This indicates that the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to blue-colored oxTMB requires a high H2O2 concentration, hindering the sensitivity of the colorimetric assay. To address this problem, novel reduced Co3O4 nanoparticles (R-Co3O4) have been synthesized in this study via a step-by-step procedure using ZIF-67 as the precursor. R-Co3O4 exhibits a considerably enhanced peroxidase-like activity when compared with that exhibited by pristine Co3O4 (P-Co3O4). The catalytic process in the case of R-Co3O4 occurs in accordance with the typical Michaelis–Menten equation, and the affinity of R-Co3O4 to H2O2 is apparently higher than that of P-Co3O4. Furthermore, the density functional theory calculations revealed that the introduction of oxygen vacancies to R-Co3O4 enhances its H2O2 adsorption ability and facilitates the decomposition of H2O2 to produce ·OH radicals, resulting in improved peroxidase-like activity. A simple and convenient colorimetric assay has been established based on the excellent peroxidase-like activity of R-Co3O4 for detecting H2O2 in concentrations of 1–30 μM with a detection limit of 4.3 × 10–7 mol/L (S/N = 3). Furthermore, the R-Co3O4-based colorimetric method was successfully applied to glucose detection in human serum samples, demonstrating its potential for application in complex biological systems.
•A conjugate-lengthened cyanine NIR fluorescent probe was firstly obtained.•The probe displayed good selectivity and high sensitivity towards H2S with a detection limit 20 nM.•The probe can ...efficiently realize mitochondria-targeted H2S in vivo.
As an important biological messenger and effector molecule, hydrogen sulfide (H2S) not only is involved in maintaining the physiological function in cardiovascular, immune and nervous systems but also controls the activity of mitochondrial atpase and antioxidant stress in living cells. Herein, a new PET-based mitochondria-targeted NIR probe Mito-N3 with good selectivity and high sensitivity for H2S was presented in this work. The free probe has no fluorescence, however, once reacts with H2S, Mito-N3 goes through an analyte-prompted immolation, resulting in the releasing of the fluorophore (Mito−OH) and the concomitant restoring of remarkable fluorescence in the NIR emission at 736 nm. The detection limit was calculated as low as 20 nM. Most importantly, fluorescence imaging experiments showed that the probe can monitor the intracellular H2S level in mitochondria of MCF-7 cells, the probe Mito-N3 also had the potential application in sensing and tracking H2S in living nude mice.
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As(III) is more toxic and harder to remove than As(V) though they are always co-exist in water. In order to effectively eliminate pollution of arsenic and explore the adsorption ...mechanism, a novel-innovative hydrated zirconium oxide (ZrO(OH)2) and manganese dioxide (MnO2) coated modified activated charcoal (Zr/Mn/C) prepared via a co-precipitation-hydrothermal method. Results showed that As(III) can be oxidized to As(V) by the MnO2 and then adsorbed by ZrO(OH)2, the toxicity reduced and the ability of Zr/Mn/C to remove As(III) is efficiently enhanced. The maximum adsorption capacity of As(V) and As(III) are 95.60 mg/g and 132.28 mg/g, respectively. The outstanding removal performance benefits from the large specific surface area of the modified activated charcoal, which makes agglomeration phenomenon weakened, and the ZrO(OH)2 and MnO2 can homogeneously distribute on the surface of carrier. The residual concentrations of As(V) and As(III) can drop under 7.0 ug/L, meeting the standards of drinking water with initial concentrations under 9mg/L and 1mg/L, respectively. Meanwhile, the nanocomposite exhibits excellent interference rejection from various co-existing anions such as: Cl−, F−, NO3−, SiO32-, PO43-, SO42- and HCO3−, it can be used in different water environments. In short, the Zr/Mn/C is a promising sorbent with a great potential for removing arsenic.
Due to the block of high-rise objects and the influence of the sun’s altitude and azimuth, shadows are inevitably formed in remote sensing images particularly in urban areas, which causes missing ...information in the shadow region. In this paper, we propose a new method for shadow detection and compensation through objected-based strategy. For shadow detection, the shadow was highlighted by an improved shadow index (ISI) combined color space with an NIR band, then ISI was reconstructed by the objects acquired from the mean-shift algorithm to weaken noise interference and improve integrity. Finally, threshold segmentation was applied to obtain the shadow mask. For shadow compensation, the objects from segmentation were treated as a minimum processing unit. The adjacent objects are likely to have the same ambient light intensity, based on which we put forward a shadow compensation method which always compensates shadow objects with their adjacent non-shadow objects. Furthermore, we presented a dynamic penumbra compensation method (DPCM) to define the penumbra scope and accurately remove the penumbra. Finally, the proposed methods were compared with the stated-of-art shadow indexes, shadow compensation method and penumbra compensation methods. The experiments show that the proposed method can accurately detect shadow from urban high-resolution remote sensing images with a complex background and can effectively compensate the information in the shadow region.
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