Developing a cost-effective, stable, and recyclable adsorbent with high adsorption capacity and rapid adsorption kinetics is highly demanded for water treatment but has been proven challenging. ...Herein, we report a one-step strategy to synthesize tough porous nanocomposite hydrogel, by introducing biochar nanoparticles and interconnected pores into a polyacrylamide hydrogel matrix as an exemplary system. The polyacrylamide hydrogel provides the overall mechanical strength to carry loads and facilitate recycling, the biochar provides adsorptive locus for high adsorption capacity, and the interconnected pores expedite solvent transport for rapid adsorption kinetics. Mechanical characterizations manifest that the porous biochar hydrogel possesses a tensile strength of 128 kPa, a stretchability of 5.9, and a toughness of 538 J m–2. Porous structure analysis reveals that the hydrogel contains an increscent specific surface area by 441% and an augmented pore volume by 279% compared to pure polyacrylamide hydrogel. Experiments pertaining to adsorption isotherms and kinetics, with methylene blue as the model adsorbate, indicate enhanced adsorption performances. The tough hydrogel also allows facile recycling and maintains mechanical robustness after five regeneration cycles. Furthermore, biocompatibility is endorsed by cytotoxicity test. The proposed method could open an ample space for designing and synthesizing tough porous nanocomposite hydrogels for water treatment.
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•A generic principle is proposed to synthesize tough porous biochar hydrogel (PBH) for water treatment.•The PBH shows enhanced adsorption capability and kinetic in dye removal.•The PBH allows facile recycling and maintains mechanical robustness after five cycles of regeneration.
Abstract
The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen ...evolution reaction (OER). Here we present the identification of 6H-phase SrIrO
3
perovskite (6H-SrIrO
3
) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. 6H-SrIrO
3
contains 27.1 wt% less iridium than IrO
2
, but its iridium mass activity is about 7 times higher than IrO
2
, a benchmark electrocatalyst for the acidic OER. 6H-SrIrO
3
is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO
3
thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H
2
O → HOO* + H
+
+
e
¯
).
The 3D NiO hollow sphere/reduced graphene oxide (rGO) composite was synthesized according to the coordinating etching and precipitating process by using Cu
O nanosphere/graphene oxide (GO) composite ...as template. The morphology, structure, and composition of the materials were characterized by SEM, TEM, HRTEM, XPS, and Raman spectra, and the electrochemical properties were studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. Moreover, the electrochemical activity of the composite materials with different morphologies were also investigated, which indicating a better combination of the NiO hollow sphere and the rGO. Used as glucose sensing material, the 3D NiO hollow sphere/rGO composite modified electrode exhibits high sensitivity of ~2.04 mA mM
cm
, quick response time of less than 5 s, good stability, selectivity, and reproducibility. Its application for the detection of glucose in human blood serum sample shows acceptable recovery and R.S.D.
The outstanding glucose sensing performance should be attributed to the unique 3D hierarchical porous superstructure of the composite, especially for its enhanced electron-transfer kinetic properties.
Drastic changes in the random load of an electromechanical system bring about a reliability problem for the proportional solenoid valve based on a thermal effect. In order to accurately and ...effectively express the thermal load of a proportional solenoid valve under random load conditions and to meet the requirements of online acquisition, adaptive anomaly detection, and the missing substitution of thermal load data, a thermal load prediction model based on the Kalman filter algorithm is proposed. Taking the compound operation process of an excavator as the object and based on the field testing of an excavator and the independent testing experiment of a proportional solenoid valve in a non-installed state, a method of obtaining historical samples of the proportional solenoid valve's power and thermal load is given. The k-means clustering algorithm is used to cluster the historical samples of the power and thermal load corresponding to the working posture of a multi-tool excavator. The Grubbs criterion is used to eliminate the outliers in the clustering samples, and unbiased estimation is performed on the clustering samples to obtain the prediction model. The results show that the cross-validation of the sample data under the specific sample characteristics of the thermal load model was carried out. Compared with other methods, the prediction accuracy of the thermal load model based on the Kalman filter is higher, the adaptability is strong, and the maximum prediction deviation percentage is stable within 5%. This study has value as a reference for random cycle thermal load analyses of low-frequency electromechanical products.
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► Constructing core–shell structured Fe3O4@SiO2–Ag magnetic nanocomposite. ► Small and highly dispersed Ag nanoparticles with a narrow size distribution. ► An easy magnetically ...separable and recoverable process. ► An excellent catalytic activity toward the reduction of 4-nitrophenol.
In this work, we report a facile method to generate core–shell structured Fe3O4@SiO2–Ag magnetic nanocomposite by an in situ wet chemistry route with the aid of polyvinylpyrrolidone as both reductant and stabilizer. This method can effectively prevent Ag nanoparticles from aggregating on the silica surface, thus resulting highly dispersed and small-sized Ag nanoparticles. The as-prepared nanocomposite is composed of a central magnetite core with a strong response to external fields, an interlayer of SiO2, and numerous highly dispersed Ag nanoparticles with a narrow size distribution. Furthermore, the Fe3O4@SiO2–Ag nanocomposite showed high performance in the catalytic reduction of 4-nitrophenol and could be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 15 times.
Abstract
Electromechanical coupling factor,
k
, of piezoelectric materials determines the conversion efficiency of mechanical to electrical energy or electrical to mechanical energy. Here, we provide ...an fundamental approach to design piezoelectric materials that provide near-ideal magnitude of
k
, via exploiting the electrocrystalline anisotropy through fabrication of grain-oriented or textured ceramics. Coupled phase field simulation and experimental investigation on textured Pb(Mg
1/3
Nb
2/3
)O
3
-Pb(Zr,Ti)O
3
ceramics illustrate that
k
can reach same magnitude as that for a single crystal, far beyond the average value of traditional ceramics. To provide atomistic-scale understanding of our approach, we employ a theoretical model to determine the physical origin of
k
in perovskite ferroelectrics and find that strong covalent bonding between B-site cation and oxygen via
d
-
p
hybridization contributes most towards the magnitude of
k
. This demonstration of near-ideal
k
value in textured ceramics will have tremendous impact on design of ultra-wide bandwidth, high efficiency, high power density, and high stability piezoelectric devices.
Systematic study on the onset of cellular instability and self-acceleration propagation for syngas spherically expanding flames is investigated. Three onsets of crack branching, uniform cellularity ...and transition acceleration are obtained from Schlieren images and Sb-κcurves. Effective Lewis number Leeff and thermal expansion ratio σ are controlled independently by adjusting equivalence ratio and oxygen-nitrogen ratio. Results show that the order of three onsets is crack branching < transition acceleration < uniform cellularity. The critical flame radius is increased with Leeff but decreased with σ. Also, it is decreased with hydrogen volumetric fraction, leading to a much earlier onset at 85% hydrogen fraction. The theoretical result can give a qualitative prediction and closer to uniform cellularity onset quantitatively, although it overestimates Leeff effects a little. The critical Peclet number of uniform cellularity onset is not only increased with Leeff but also increased with σ, mainly due to the variation of flame thickness. Besides, there is a positive correlation between critical Peclet number and Markstein number, indicating a strengthened inhibition of stretch. The onset of similarity acceleration is also obtained through acceleration exponent and it performs a similar variation trend as that of cellular instability. All of these demonstrate that both cellular instability and similarity acceleration are the coupling results of diffusional-thermal instability, hydrodynamic instability and stretch.
•Three onsets of cellular instability are clearly distinguished.•Effects of Leeff and σ on cellular instability are investigated respectively.•Inhibition effect of stretch becomes significant with the increase of Mb.•Similarity acceleration onset appears a similar trend as that of cellular instability.
An effective route has been developed to synthesize magnetic Fe3O4@SiO2@TiO2-Ag microspheres with well-defined core–shell nanostructure and enhanced photocatalytic activity.
•Controllable synthesis ...of core–shell structured Fe3O4@SiO2@TiO2-Ag magnetic nanocomposite.•The unique nanostructure of Fe3O4@SiO2@TiO2-Ag can improve the total photocatalytic performance.•An easy magnetically separable and recoverable process.
Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical–chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron–hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application.
The incidence of chorioamnionitis and neonatal sepsis increases with the increasing time of rupture of membranes. Changes in the amount and categories of microbiomes in maternal and fetal ...environments after membrane rupture have yet to be discussed. In order to determine the microbiome diversity and signature in the maternal, intrauterine, and fetal environments of different durations following membrane rupture, we collected samples of fetal membrane, amniotic fluid, cord blood and maternal peripheral blood from singleton pregnant women and divided them into five groups according to the duration of membrane rupture. DNA was isolated from the samples, and the V3V4 region of bacterial 16S rRNA genes was sequenced. We found that the alpha diversity of the fetal membrane microbiome increased significantly 12 h after membrane rupture, while the beta diversity of the amniotic fluid microbiome increased 24 h after membrane rupture. In cord blood, the mean proportion of Methylobacterium and Halomonadaceae reached the highest 12 h after membrane rupture, and the mean proportion of Prevotella reached the highest 24 h after membrane rupture. The LEfSe algorithm showed that Ruminococcus, Paludibaculum, Lachnospiraceae, and Prevotella were detected earlier in cord blood or maternal blood and then detected in fetal membranes or amniotic fluid, which may suggest a reverse infection model. In conclusion, the microbes may invade the placenta 12 h after membrane rupture and invaded the amniotic cavity 24 h after membrane rupture. In addition to the common ascending pattern of infection, the hematogenous pathway of intrauterine infection should also be considered among people with rupture of membranes.
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