A LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode with B2O3 surface modification was prepared in a facial synthesis method using H3BO3 as a modifier precursor. Both TEM and XPS measurements demonstrate that a ...thin layer of amorphous B2O3 is successfully coated on the surface of 1B2O3@NCM111 particles. XRD, SEM and TEM testing results show that the morphology and lattice structure present little change after coating. The B2O3 surface modified 1B2O3@NCM111 shows 43% improved high-rate (at 5C rate) discharge performance and enhanced cycling stability (with about 92% and 86% capacity retention at 1C and 2C rates after 50 and 100 cycles measurements) compared to the pristine NCM111. EIS and GITT results also present that the 1B2O3@NCM111 electrode with B2O3 surface modification retains higher Li+ chemical diffusion coefficient than the pristine NCM111 even after 50 charge/discharge cycles at 1C rate.
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•B2O3 surface-modified LiNi1/3Co1/3Mn1/3O2 cathode was successfully prepared via a facial wet-chemical method.•B2O3 surface-modified LiNi1/3Co1/3Mn1/3O2 cathode shows improved high-rate discharge performance and cycling stability.•B2O3 surface modification acts as a protection layer to hinder the unfavorable side reactions.
Five types of biochars prepared from four crop straws and one wood shaving at 600°C were characterized, and their sorption to Cd(II) were determined to investigate the differences in capacity to ...function as sorbents to heavy metals. Surface areas and pore volumes of the biochars were inversely correlated to the lignin content of raw biomass. The biochars derived from crop straws displayed more developed pore structure than wood char due to the higher lignin content of wood. Sorption capacity of the biochars to Cd(II) followed the order of corn straw>cotton straw>wheat straw>rice straw>poplar shaving, which was not strictly consistent with the surface area of the chars. The surface characteristics of chars before and after Cd(II) sorption were investigated with scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, which suggested that the higher sorption of Cd(II) on corn straw chars was mainly attributed to cation exchange, surface precipitation of carbonate, and surface complexation with oxygen-containing groups. This study indicated that crop straw biochars exhibit distinct sorption capacities to heavy metals due to various surface characteristics, and thus the sorption efficiency should be carefully evaluated specific to target contaminant.
SEM images of corn straw biochars before and after sorption of Cd(II) and corresponding EDS spectra: (a) and (b) photographs of raw corn straw biochar with different magnitude of enlargement, (c) Cd-loaded corn straw biochar, (d) EDS spectra and elemental ratio of the square region inside (c) Display omitted
•Surface area of biochars is inversely correlated to lignin content of raw biomass.•Crop straw biochars display more developed pore structure than wood char.•Corn straw biochar exhibits the highest sorption capacity to Cd(II).•Sorption mechanisms mainly involved cation exchange, surface precipitation, and surface complexation.•Sorption efficiency of crop straw biochars varies greatly with their sources.
Abstract
Commercial Cu-exchanged small-pore SSZ-13 (Cu-SSZ-13) zeolite catalysts are highly active for the standard selective catalytic reduction (SCR) of NO with NH
3
. However, their activity is ...unexpectedly inhibited in the presence of NO
2
at low temperatures. This is strikingly distinct from the NO
2
-accelerated NO
x
conversion over other typical SCR catalyst systems. Here, we combine kinetic experiments, in situ X-ray absorption spectroscopy, and density functional theory (DFT) calculations to obtain direct evidence that under reaction conditions, strong oxidation by NO
2
forces Cu ions to exist mainly as Cu
II
species (fw-Cu
2+
and NH
3
-solvated Cu
II
with high CNs), which impedes the mobility of Cu species. The SCR reaction occurring at these Cu
II
sites with weak mobility shows a higher energy barrier than that of the standard SCR reaction on dynamic binuclear sites. Moreover, the NO
2
-involved SCR reaction tends to occur at the Brønsted acid sites (BASs) rather than the Cu
II
sites. This work clearly explains the strikingly distinctive selective catalytic behavior in this zeolite system.
There is a continuing need to develop effective materials for the environmental remediation of copper-contaminated sites. Nano-MnO₂-biochar composites (NMBCs) were successfully synthesized through ...the reduction of potassium permanganate by ethanol in a biochar suspension. The physicochemical properties and morphology of NMBCs were examined, and the Cu(II) adsorption properties of this material were determined using various adsorption isotherms and kinetic models. The adsorption capacity of NMBCs for Cu(II), which was enhanced by increasing the pH from 3 to 6, was much larger than that of biochar or nano-MnO₂. The maximum adsorption capacity of NMBCs for Cu(II) was 142.02 mg/g, which was considerably greater than the maximum adsorption capacities of biochar (26.88 mg/g) and nano-MnO₂ (93.91 mg/g). The sorption process for Cu(II) on NMBCs fitted very well to a pseudo-second-order model (
² > 0.99). Moreover, this process was endothermic, spontaneous, and hardly influenced by ionic strength. The mechanism of Cu(II) adsorption on NMBCs mainly involves the formation of complexes between Cu(II) and O-containing groups (e.g., COO-Cu and Mn-O-Cu). Thus, NMBCs may serve as effective adsorbents for various environmental applications, such as wastewater treatment or the remediation of copper-contaminated soils.
The sorption characteristics of tetracycline (TC) by waste tire powder and its chars were investigated to explore the potential of using waste tires as effective sorbents for removal of TC from ...aqueous solution. Naphthalene (NAPH), a typical hydrophobic organic compound, was selected as asorbate for comparison. TC displayed much lower sorption affinity to tire powder than NAPH. However, it exhibited similar adsorption affinity as NAPH on the pyrolyzed tire chars, which was mainly attributed to π-π electron-donor–acceptor interactions of TC with the graphite surface of chars. TC and Cu2+ could mutually facilitate the sorption of each other on both tire powder and pyrolyzed chars in a wide pH range. This could be explained by the metallic complexation and/or surface-bridging mechanisms (i.e., Cu- or TC-bridging). However, Cu2+ and NAPH depressed the sorption of each other on tire powder and displayed negligible impact to each other on the highly pyrolyzed chars.
Conceptual illustration of the effects of Cu2+ on the sorption of tetracycline (TC) and naphthalene (NAPH) on tire powder (TP) and pyrolytic char (C800). Display omitted
•Tire chars could be effective sorbents for tetracycline wastewater treatment.•Tetracycline and Cu2+ facilitate sorption of each other on tire sorbents in a wide pHs.•Naphthalene and Cu2+ depressed the sorption of each other on tire powder.•Naphthalene and Cu2+ displayed negligible effect to each other on carbonized chars.
Cu2+ exhibits opposite impacts on the sorption of tetracycline on waste tire powder and its chars.
In this study, a transcriptomic analysis of the dehydration rate of mature rice seeds was conducted to explore candidate genes related to the dehydration rate and provide a theoretical basis for ...breeding and utilization. We selected two rice cultivars for testing (Baghlani Nangarhar, an extremely rapid dehydration genotype, and Saturn, a slow dehydration genotype) based on the results determined by previous studies conducted on the screening of 165 germplasm materials for dehydration rate phenotypes. A rapid dehydration experiment performed on these two types of seeds was conducted. Four comparative groups were set up under control and dehydration conditions. The differentially expressed genes (DEGs) were quantified via transcriptome sequencing and real-time quantitative PCR (RT-qPCR). GO (Gene ontology) and KEGG(Kyoto Encyclopedia of Genes and Genomes) analyses were also conducted. In Baghlani Nangarhar, 53 DEGs were screened, of which 33 were up-regulated and 20 were down-regulated. In Saturn, 25 DEGs were screened, of which 19 were up-regulated and 6 were down-regulated. The results of the GO analysis show that the sites of action of the differentially expressed genes enriched in the rapid dehydration modes are concentrated in the cytoplasm, internal components of the membrane, and nucleosomes. They play regulatory roles in the processes of catalysis, binding, translocation, transcription, protein folding, degradation, and replication. They are also involved in adaptive responses to adverse external environments, such as reactive oxygen species and high temperature. The KEGG analysis showed that protein processing in the endoplasmic reticulum, amino acid biosynthesis, and oxidative phosphorylation were the main metabolic pathways that were enriched. The key differentially expressed genes and the most important metabolic pathways identified in the rapidly and slowly dehydrated genotypes were protein processing in the endoplasmic reticulum and oxidative phosphorylation metabolism. They were presumed to have important regulatory roles in the mechanisms of stress/defense, energy metabolism, protein synthesis/folding, and signal transduction during the dehydration and drying of mature seeds. The results of this study can potentially provide valuable information for further research on the genes and metabolic pathways related to the dehydration rate of mature rice seeds, and provide theoretical guidance for the selection and breeding of new rice germplasm that can be rapidly dehydrated at the mature stage.
In the current article, the effect of Si/Al ratio on the NOx adsorption and storage capacity over Pd/Beta with 1 wt% Pd loading was investigated. The XRD, 27Al NMR and 29Si NMR measurements were used ...to determine the structure of Pd/Beta zeolites. XAFS, XPS, CO-DRIFT, TEM and H2-TPR were used to identify the Pd species. The results showed that the NOx adsorption and storage capacity on Pd/Beta zeolites gradually decreased with the increase of Si/Al ratio. Pd/Beta-Si (Si-rich, Si/Al~260) rarely has NOx adsorption and storage capacity, while Pd/Beta-Al (Al-rich, Si/Al~6) and Pd/Beta-C (Common, Si/Al~25) exhibit excellent NOx adsorption and storage capacity and suitable desorption temperature. Pd/Beta-C has slightly lower desorption temperature compared to Pd/Beta-Al. The NOx adsorption and storage capacity increased for Pd/Beta-Al and Pd/Beta-C by hydrothermal aging treatment, while the NOx adsorption and storage capacity on Pd/Beta-Si had no change.
At present, many scientific experiments are carried out in extreme conditions. Pilots need to perform high-intensity tasks for a long time. Human error is an essential factor affecting mission ...execution. To deeply study the physiological characteristics of different erroneous states of consciousness, we used an improved double-choice Oddball paradigm to collect brain electrophysiological signals of volunteers and pilots in missions and analyze event-related potential (ERP), time-frequency, and brain function spectrum, extracting EEG indicators sensitive to error awareness. The results showed that, in the 300∼500 ms time window, the error awareness type was correlated with Pe amplitude. Meanwhile, the time-frequency and brain functional spectrum analysis showed that the amplitude of the aware errors α-ERS oscillation, the functional spectral density of the α-band, and the uncertain errors were more prominent than unaware errors. The error awareness of the pilots showed the same EEG sensitivity characteristics in flight as in the ground volunteer experiment, and the characteristic sensitivity value was higher than that of the ground participants. We analyzed the EEG indicators sensitive to error awareness and determined the differences in EEG characteristics when pilots have error awareness on the ground and in flight. This study provides theoretical guidance for the follow-up research on the intervention measures against error awareness and determines the target point positioning.
Citric acid (CA) can regulate the balance of anions and cations in plants, and improve their resistance to heavy metals. It is not clear if foliar application with CA has any effect on migration of ...Cd and Mn in rice plant. In this work, a low-Cd-accumulating indica rice line (P7) and a high-Cd-accumulating line (HZ) were used to investigate the influence of CA on the transport of Cd and Mn as well as amino acid metabolism in grains. Content of Cd in grains and other organs increased with the increase of Cd content (0.1–2.4 mg kg−1) in soil, while decreased with the foliar application with CA. With the increase of Cd content in rice grains, the content of most amino acids in HZ, P7, HZ+CA and P7 + CA showed an obvious decline trend. Foliar application with CA efficiently raised the Mn:Cd ratio in grains and nodes of both HZ and P7. Meanwhile, the expression levels of OsNramp2, 3 and 5 in panicles were efficiently enhanced by CA application when plants grew in soil with Cd content of 0.6–2.4 mg kg−1. The increasing effect of CA on the content of 4 amino acids (i.e., Glu, Phe, Thr and Ala) in grains was related to varieties and Cd pollution. These results indicate that foliar application with CA can regulate the transport of Cd and Mn in the opposite directions in tissues and inhibit Cd accumulation in grains by enhancing expression of OsNRAMP 2, 3 or 5 and triggering the defense response of some amino acids in Cd-contaminated environment.
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•Citric acid regulates migration of Cd and Mn in rice in the opposite directions and increase Mn:Cd ratio in grains and nodes.•The expression of Nramp family genes in panicles is inhibited by Cd stress and enhanced by exogenous citric acid.•Citric acid promotes the synthesis of Glu, Phe, His, Ser and Thr in rice for alleviating Cd toxicity.
At present, low-speed high-torque permanent magnet motors are widely used in the sampling industry, manufacturing industry and energy industry. However, the research on low-speed high-torque ...permanent magnet motors is far from enough. The primary difficulty in the initial design of low-speed high-torque permanent magnet motors is the selection of pole–slot ratio. The pole–slot ratio has a great influence on the electromagnetic performance such as torque ripple and the maximum output torque of low-speed motors. Choosing the appropriate pole–slot ratio scheme can make the design of a low-speed motor more efficient. In addition, the optimization design of the motor is also a necessary process. At present, there are many studies on optimization algorithms. However, the research on sample point sampling and surrogate model fitting is not enough. Choosing the appropriate sample point sampling method and surrogate model fitting method can help one obtain a more accurate surrogate model, which lays a foundation for the optimization of the motor. Based on the above analysis, this paper first selects four representative pole–slot ratio schemes for comprehensive comparison of their electromagnetic performances. Secondly, two sample point sampling methods and three surrogate model fitting methods are combined to obtain six surrogate models, and the accuracy of the six surrogate models is compared and analyzed. Finally, a 37kW,160rpm prototype is made, and the comparison of the surrogate model optimization prediction results, the finite element simulation calculation results and the measured results is carried out to further prove the accuracy of the selected surrogate model. The work performed in this paper provides a certain reference value for the initial design and optimization experiment design of low-speed high-torque permanent magnet motor.
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