The macroporous honeycomb-like MgO (MHM) had been successfully prepared by hard template method using polystyrene (PS) spheres with different particle sizes of about 400, 600, and 800 nm, ...respectively. The adsorption performance (3700, 3470, and 3087 mg/g) and specific surface areas (64.0, 51.4, and 34.4 m
2
/g) of MHM materials were inversely proportional to their pore diameters. Among the prepared MHM materials, MHM-400 exhibited the most excellent adsorption performance of 3700 mg/g towards Pb(II) at 25 °C. In this study, the macropore size in MHM played a major role in the adsorption process; Dubinin-Radushkevich (D-R) model further indicated that Pb(II) removal by MHM-400 was dominated by chemical adsorption. The thermodynamic analysis (
ΔG
0
< 0,
ΔH
0
> 0, and
ΔS
0
> 0) revealed that the Pb(II) adsorption was spontaneous and endothermic. After storing for 360 days, the Pb(II) removal efficiency of MHM-400 was still higher than 98.2%, exhibiting ultra-long life for Pb(II) capture. MHM-400 also exhibited high anti-interference ability towards typically coexisting ions (Na
+
and K
+
). According to the density functional theory (DFT) calculation, the Pb could be adsorbed on the top site of the oxygen atom at the surface of the cubic MgO (200) plane; the adsorption energy (
E
ad
) was 0.159 eV. The XRD and FTIR analyses revealed the further formation of Pb
3
(CO
3
)
2
(OH)
2
and PbO after Pb(II) adsorption. Furthermore, MHM-400 could effectively remove both Cd(II) and Pb(II) ions from wastewater within 20 min, and the adsorption efficiency achieved > 99%, suggesting that MHM-400 was a potential material for effective Pb(II) removal.
Recently, compressed sensing (CS) methods are widely used in high-resolution inverse synthetic aperture radar (ISAR) imaging. However, these CS-based imaging methods generally do not take the ...block-sparse structure of the ISAR images into account, and the image recovery performance needs to be improved. By utilising the block-sparse structure of the signal, more sparse solution and better focused ISAR images can be obtained. In this study, the authors convert the block-sparse signal recovery problem into a sparse recovery problem for multiple measurement vector (MMV), which can be solved more efficiently. A sparser and more accurate solution can be obtained based on the MMV model, and therefore better focused ISAR images can be recovered. Simulation and experimental results validate the effectiveness of the proposed method.
Wearable artificial kidney can provide continuous dynamic dialysis for uremia patients. For the sake of practical application, the critical step is to find an adsorbent that can effectively remove ...urea and have excellent biological compatibility. The layered Ti3C2Tx (DL-Ti3C2Tx) with high specific surface area and good dispersion was prepared by a two-step etching method. From the first principles calculation, urea can be adsorbed by different groups (−F, –O, –OH) on the surface of Ti3C2Tx, among which –OH has the greatest binding energy to urea. Therefore, DL-Ti3C2Tx was modified with different alkali solutions (KOH, NaOH, LiOH) to introduce –OH on the surface, which can increase the adsorption capacity of urea. The experimental results showed that DL-Ti3C2Tx (LiOH-Ti3C2Tx) after treated by LiOH had the highest urea adsorption efficiency, and the urea removal rate of LiOH-Ti3C2Tx was still higher than 92% when the urea concentration was 500 mg/L. In the Simulated dialysate, Ti3C2Tx treated with three kinds of alkali solutions still maintained a good adsorption efficiency for urea, and still had a certain adsorption capacity after recycling for four times. Biocompatibility experiments showed that Ti3C2Tx in different concentrations did not cause hemolysis of erythrocyte, and had no obvious damage to vascular endothelial cells. This study greatly improves the urea adsorption efficiency of MXene, which has a broad application prospect in the selection of adsorbent for wearable artificial kidney.
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•By a two-step etching method, layered Ti3C2Tx (DL-Ti3C2Tx) with high specific surface area and good dispersion was prepared.•DL-Ti3C2Tx was modified with different alkali solutions (KOH, NaOH, LiOH) to introduce –OH on the surface, increasing the adsorption capacity of urea.•The alkalized Ti3C2Tx with excellent biocompatibility can efficiently adsorb urea, and maintain high stability in the simulated dialysate.
Allelopathy is regarded as an economic and eco-friendly approach for the control of harmful algal blooms (HABs) because allelochemicals degrade easily and cause less pollution than traditional ...algicides. We first surveyed the inhibitory effect of the traditional medicinal plant Cerbera manghas L. on the notorious dinoflagellates Alexandrium tamarense, Scrippsiella trochoidea, and Karenia mikimotoi. Then, we identified and quantified the potential algicidal compounds by UPLC-MS and determined their activity. The aqueous extract inhibited algae with EC50–120 h at 0.986, 1.567 and 1.827 g L−1 for A. tamarense, S. trochoidea, and K. mikimotoi, respectively. Three potential allelochemicals were quantified in the stock solution: quinic acid (QA) (28.81 mg L−1), protocatechuic acid (PA) (53.91 mg L−1), and phloridzin (PD) (26.17 mg L−1). Our results illustrated that 1) QA did not have an inhibitory effect, 2) PA had medium toxicity to algae (EC50–120h: 0.22, 0.28, and 0.35 mM for A. tamarense, S. trochoidea, and K. mikimotoi), and 3) PD had low toxicity (EC50–120h > 0.66 mM). These findings suggested that PA might be the main allelopathic compound in the aqueous extract of the studied algae. In addition, PA could have a negative effect on the photosynthesis of S. trochoidea by impeding the reduction of quinone electrons and destroying electron transfer in PSII. In summary, this was the first study to quantify allelochemicals in C. manghas fruit. Moreover, C. manghas and protocatechuic have the potential to be algicides to control and mitigate the HABs caused by dinoflagellates.
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•Cerbera manghas aqueous extract could inhibit dinoflagellate growth.•Quinic acid, protocatechuic acid, and phloridzin were quantified.•Protocatechuic acid was one of the main allelopathic compounds for dinoflagellates.•Protocatechuic acid inhibits dinoflagellate photosynthesis.
The mining of ion-adsorption rare earth minerals or ores generated a large amount of wastewater containing rare earth elements at low-concentration, resulting in continuous environmental pollution. ...For this problem, our study prepared an efficient, recyclable MgO/MgFe2O4 magnetic adsorbent, synthesized by a template method and characterized using XRD, SEM-EDS, BET, and VSM. The isothermal adsorption experiments and adsorption kinetic experiments were carried out to evaluate the ability of MgO/MgFe2O4 to remove La(Ⅲ) and Ce(Ⅲ), and the effects of the initial pH of the solution and the dosage were also investigated. FT-IR and XPS analyzed the ion-exchange mechanism between La(III) and Ce(III) ions and the hydroxyl functional groups present in the adsorbent, culminating in the formation of La/Ce-OH complexes. MgO/MgFe2O4 demonstrated a theoretical adsorption capacity of 2002 mg/g and 5317 mg/g for La(III) and Ce(III), respectively, achieving removal rates of 97.2% and 98.7% in dilute solutions, marking it as a potent solution for rare earth element remediation in wastewater. This advancement holds substantial implications for environmental management within rare earth mining locales.
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•Adsorbents showed excellent adsorption capacity for La(Ⅲ) and Ce(Ⅲ).•Efficient magnetic separation of adsorbents from water.•Analysis of adsorption mechanism by batch adsorption experiments.•Significant for the restoration of water resources in rare earth mining areas.
Functional networks (FNs) hold significant promise in understanding brain function. Independent component analysis (ICA) has been applied in estimating FNs from functional magnetic resonance imaging ...(fMRI). However, determining an optimal model order for ICA remains challenging, leading to criticism about the reliability of FN estimation. Here, we propose a SMART (splitting-merging assisted reliable) ICA method that automatically extracts reliable FNs by clustering independent components (ICs) obtained from multi-model-order ICA using a simplified graph while providing linkages among FNs deduced from different-model orders. We extend SMART ICA to multi-subject fMRI analysis, validating its effectiveness using simulated and real fMRI data. Based on simulated data, the method accurately estimates both group-common and group-unique components and demonstrates robustness to parameters. Using two age-matched cohorts of resting fMRI data comprising 1,950 healthy subjects, the resulting reliable group-level FNs are greatly similar between the two cohorts, and interestingly the subject-specific FNs show progressive changes while age increases. Furthermore, both small-scale and large-scale brain FN templates are provided as benchmarks for future studies. Taken together, SMART ICA can automatically obtain reliable FNs in analyzing multi-subject fMRI data, while also providing linkages between different FNs.
The current two-dimensional (2D) material based NH3 sensors generally suffer from low response values and sluggish recovery dynamics, which is resulted from their inferior conductivity. Herein, high ...conductivity (0.045 S/m) of 2D hydrogen substituted graphyne (HsGY) nanosheets are successfully synthesized employing aqueous/organic interface method and using them for the first time for the detection of NH3 at room temperature. The resultant gas sensing performance shows that the 2D HsGY nanosheets exhibit a high gas response value (4.9) to 100 ppm NH3 and fast recovery time (108 s) at the room temperature. The NH3 gas sensing mechanism is discussed by utilizing density functional theory (DFT) calculations. The present study provides novel gas sensing material for the development of high-performance room temperature NH3 sensors.
This study successfully synthesized two-dimensional hydrogen substituted graphyne (HsGY) nanosheets using an aqueous/organic interface method and applied them for the detection of NH3 at room temperature for the first time. HsGY nanosheets exhibit excellent sensing performance towards NH3, due to their high conductivity and continuous thin gauze like morphology, which facilitates gas transport. Display omitted
The activity of pyrite (FeS2) and microsized zero-valent iron (mZVI) is greatly limited by the passivating layer. This study indicated that hexavalent chromium (Cr(VI)) could be effectively ...sequestered by mechanochemically activated mZVI/FeS2 composite (MA-mZVI/FeS2), which was obtained from the mZVI/FeS2 mixture by mechanochemical technology. Compared with MA-mZVI and MA-FeS2, the Cr(VI) removal performance of MA-mZVI/FeS2 was significantly improved at a mZVI/FeS2 molar ratio of 1:9. The effects of initial concentration, coexisting anions, reaction time, and initial pH on Cr(VI) sequestration by MA-mZVI/FeS2 were investigated. During the removal process, the concentrations of different valence states of chromium and iron were measured to explore the Cr(VI) removal mechanism. Based on the experiments and characterizations, surface sorption accounted for 41.38% and reduction accounted for 58.62% at the Cr(VI) adsorption equilibrium of MA-mZVI/FeS2. The ball milling destroyed the passivating layer of MA-mZVI/FeS2, resulting in a rough surface. The corrosion of mZVI can be significantly accelerated by FeS2 due to the strong interaction between mZVI and FeS2 in MA-mZVI/FeS2, which led to the enhanced Cr(VI) sequestration. The practical application indicated that MA-mZVI/FeS2 had good Cr(VI) removal performance in real water samples. This study revealed that MA-mZVI/FeS2 can be a hopeful adsorbent for effective Cr(VI) sequestration in aqueous solution.
Space-time adaptive processing (STAP) based on sparse recovery (SR-STAP) techniques exhibits significantly better performance than conventional STAP algorithms within a very small number of ...snapshots. However, when the clutter patches do not locate exactly on the discrete space-time grid points, the performances of SR-STAP algorithms degrade severely. In this letter, a low-complexity off-grid STAP algorithm based on local search clutter subspace estimation is proposed to overcome this issue. In the proposed algorithm, the global atoms are first selected from the reduced-dimension global STAP dictionary using the design selection criterion. Then, the optimal atoms are searched from the local STAP dictionary. Finally, these space-time steering vectors corresponding to the optimal atoms are used to construct the clutter subspace iteratively, and the STAP weight is obtained by projecting the snapshot on the subspace orthogonal to the clutter subspace. Numerical experiments with both simulated and Mountain-Top data are carried out to demonstrate the effectiveness of the proposed algorithm.
Sequential order one negative exponential (SOONE) function is used to measure the sparsity of a two-dimensional (2D) signal. A 2D gradient projection (GP) method is developed to solve the SOONE ...function and thus the 2D-GP-SOONE algorithm is proposed. The algorithm can solve the sparse recovery of 2D signals directly. Theoretical analysis and simulation results show that the 2D-GP-SOONE algorithm has a better performance compared with the 2D smoothed L0 algorithm. Simulation results also show that the proposed algorithm has a better performance and requires less computation time than 2D iterative adaptive approach.
