Besides the help of diverse signals as mentioned above, another part contributing to the understanding of the brain is machine learning methods. According to their study, the deep learning-based ...method can help refine the frequency band associated with the exercise. A much narrower frequency band (27–29 Hz) was identified, compared to a usually used frequency band of 15–30 Hz. ...the exercise-related brain areas were also identified, which were the contralateral and ipsilateral sensorimotor areas, contralateral prefrontal area, and occipital area.
MOx/ABO3 is a promising catalyst for the high-efficiency removal of volatile organic compounds. However, this catalyst is limited on practical applications due to its complex synthesis procedure and ...high cost. In this work, the MnO2/LaMnO3 catalyst was prepared in situ using a facile one-step method for the first time, in which partial La cations were selectively removed from three dimensionally chain-like ordered macroporous (3DOM) LaMnO3 material. After selective removal, the obtained MnO2/LaMnO3 sample expressed an excellent catalytic performance on toluene oxidation. Toluene could be completely oxidized into CO2 and H2O at 290 °C over the MnO2/LaMnO3 catalyst with a toluene/oxygen molar ratio of 1/100 and a space velocity of 120 000 mL/(g h). In addition, the apparent activation energy value of MnO2/LaMnO3 was 57 kJ/mol, which was lower than those of other metal oxides catalysts. According to O2-TPD and XPS results, it is concluded that the high catalytic performance of MnO2/LaMnO3 was mainly associated with the large amount of oxygen species and the excellent lattice oxygen mobility. MnO2/LaMnO3 is a promising catalyst for the practical removal of volatile organic compounds due to its high efficiency, good stability, low cost, and convenient preparation.
The water cloud model (WCM) is a widely used radar backscatter model applied to SAR images to retrieve soil moisture over vegetated areas. The WCM needs vegetation descriptors to account for the ...impact of vegetation on SAR backscatter. The commonly used vegetation descriptors in WCM, such as Leaf Area Index (LAI) and Normalized Difference Vegetation Index (NDVI), are sometimes difficult to obtain due to the constraints in data availability in in-situ measurements or weather dependency in optical remote sensing. To improve soil moisture retrieval, this study investigates the feasibility of using all-weather SAR derived vegetation descriptors in WCM. The in-situ data observed at an agricultural crop region south of Winnipeg in Canada, RapidEye optical images and dual-polarized Radarsat-2 SAR images acquired in growing season were used for WCM model calibration and test. Vegetation descriptors studied include HV polarization backscattering coefficient ( σ H V ° ) and Radar Vegetation Index (RVI) derived from SAR imagery, and NDVI derived from optical imagery. The results show that σ H V ° achieved similar results as NDVI but slightly better than RVI, with a root mean square error of 0.069 m3/m3 and a correlation coefficient of 0.59 between the retrieved and observed soil moisture. The use of σ H V ° can overcome the constraints of the commonly used vegetation descriptors and reduce additional data requirements (e.g., NDVI from optical sensors) in WCM, thus improving soil moisture retrieval and making WCM feasible for operational use.
Photocatalytic synthesis of ammonia (NH3) holds significant potential compared with the Haber–Bosch process. However, the reported photocatalysts suffer from low efficiency owing to localized ...electron deficiency. Herein, Ru‐SA (single atoms)/HxMoO3−y hybrids with abundant of Mon+ (4<n<6) species neighboring oxygen vacancies (OV) are synthesized via a H‐spillover process. Detailed characterizations demonstrate that Ru‐SA/HxMoO3−y hybrids can quantitatively produce NH3 from N2 and H2 through the presence of dual active centers (Ru SA and Mon+). The Ru SA boost the activation and migration of H2, and Mon+ species act as the trapping sites of localized electrons and the adsorption and dissociation sites of N2, finally leading to NH3 synthesis on Mon+−OH. The NH3 generation rate is up to 4.0 mmol h−1 g−1, accompanied by an apparent quantum efficiency over 6.0 % at 650 nm.
Ru‐SA (single atom)/HxMoO3−y hybrids with abundant Mon+ species neighboring oxygen vacancies are synthesized via a H‐spillover process. More importantly, Ru‐SA/HxMoO3−y hybrids can quantitatively produce NH3 from N2 and H2 by the effect of dual active centers (Ru SA and Mon+).
An increasing number of industries remove toluene from flue gas by the existing NH3-selective catalytic reduction (NH3-SCR) units. A thorough probe into the impact of NOx and NH3 addition on toluene ...oxidation is imperative but still lacks a unified understanding. In this work, NH3-SCR reactants are found to inhibit the toluene oxidation process over the MnOx-CeO2 catalyst below 200 °C. The competitive adsorption between NH3-SCR reactants and toluene, the NO2 adsorption state, and carbon deposition are emphasized to play important roles in this deactivation. Within the NO2 adsorption states, only the adsorbed NO2 can enhance the toluene oxidation. The formed nitrate species (NO3-) on the surface is inactive. NO2 adsorption is the weakest among the reactants with the smallest adsorption energy of −0.42 eV, restricting its promotion on toluene oxidation. NO and N2O are both demonstrated to be inefficient to oxidize toluene. Meanwhile, MnOx-CeO2 catalyst suffers from serious acetonitrile and benzonitrile poisoning. The amount of nitrile species accounts for ~95% of total carbon deposition, while no simple substance carbon (C) can be generated from CO disproportionation. Special care should be considered towards the formation of environmentally hazardous benzamide in the off-gas from the simultaneous NOx and toluene removal process.
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•NH3-SCR gas inhibits the toluene oxidation process over MnOx-CeO2 catalyst.•Toluene competitively adsorbs with NH3-SCR reactants.•The formed nitrate species is inactive for toluene oxidation.•Nitrile species block the active sites on the catalyst surface.•Environmentally hazardous benzamide is generated in the off-gas.
The removal of NOₓ by catalytic technology at low temperatures (100–300°C) is significant for flue gas of industry and exhaust gas of diesel engine; however, to develop the low-temperature catalyst ...(LTC) for selective catalytic reduction of NOₓ with ammonia (NH₃-SCR) is still a challenge especially at temperature below 200°C. This study reviews two types of LTC, the metal oxide catalyst and metal exchanged zeolite catalyst. The performances of Mn-based metal oxide with and without supports have been attempted to correlate with preparation method, precursor, and various supports. The role of manganese oxides with different phases as the most effective low temperature active component and the limitation of stability in the presence of H₂O and SO₂ are discussed. Fe, Cu exchanged zeolites as potential real application catalysts in diesel engine have been investigated for NH₃-SCR of NOₓ in the past decades, the activity, selectivity and thermal stability related to types of metal, and zeolite, and reaction conditions are reviewed. The research progress in active sites and reaction mechanisms of Mn-based catalyst and Fe–zeolite catalysts are described and compared. Finally, future research directions in the developing LTC for removal of NOₓ are proposed.
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•Cu modified Mn3O4 spinel showed excellent SCR performance and SO2 resistance.•The Eley-Rideal mechanism predominated in the low temperature SCR reaction.•The formation of MnSO4 was ...mainly responsible for the deactivation of Mn3O4.•Cu doping restrained MnSO4 generation by reducing the amounts of adjacent Mn.
Mn-based oxides are regarded as one of the most promising catalysts for selective catalytic reduction (SCR) of NOx by NH3 at low temperatures, but their applications are extremely restricted by the irreversible poisoning of SO2. Improving the SO2 tolerance of Mn-based catalyst has longtime received the most attentions from both academia and industry. In this work, a series of Cu-modified Mn3O4 spinels were synthesized, and the roles of the Cu dopant were investigated. The (Cu1.0Mn2.0)1–δO4 spinel showed both excellent SCR performance and SO2 resistance at low temperature. Cu doping improved the BET surface area, the quantities of active Mn4+ and the acid sites of Mn3O4 spinels, all of which contributed to the increase in low-temperature SCR activity. The formation of MnSO4 was mainly responsible for the irreversible deactivation of the Mn3O4 spinel upon exposure to SO2. DFT calculations suggested that SO2 was more likely to be adsorbed as “–Mn–O–S–O–Mn–” on Mn3O4 and (Cu1.0Mn2.0)1–δO4 spinels. Therefore, the formation of MnSO4 on the (Cu1.0Mn2.0)1–δO4 spinel was significantly mitigated by Cu doping, mainly due to reduced amounts of adjacent Mn. Moreover, resulting from the electronic transfer between copper and manganese cations within the spinel lattice (Cu2+ + Mn3+ ⇄ Mn4++ Cu+), the (Cu1.0Mn2.0)1–δO4 spinel retained a high surface ratio of Mn4+/Mntotal, which maintained an excellent low-temperature SCR activity under the SO2-containing condition. This work shows that doping with the low–valence dopant of Cu can significantly improve the low-temperature SCR activity and SO2 tolerance of the Mn3O4 spinel, which could be a strategy for the further design of Mn-based SCR catalysts.
The gut microbiota has been linked to cardiovascular diseases. However, the composition and functional capacity of the gut microbiome in relation to cardiovascular diseases have not been ...systematically examined. Here, we perform a metagenome-wide association study on stools from 218 individuals with atherosclerotic cardiovascular disease (ACVD) and 187 healthy controls. The ACVD gut microbiome deviates from the healthy status by increased abundance of Enterobacteriaceae and Streptococcus spp. and, functionally, in the potential for metabolism or transport of several molecules important for cardiovascular health. Although drug treatment represents a confounding factor, ACVD status, and not current drug use, is the major distinguishing feature in this cohort. We identify common themes by comparison with gut microbiome data associated with other cardiometabolic diseases (obesity and type 2 diabetes), with liver cirrhosis, and rheumatoid arthritis. Our data represent a comprehensive resource for further investigations on the role of the gut microbiome in promoting or preventing ACVD as well as other related diseases.The gut microbiota may play a role in cardiovascular diseases. Here, the authors perform a metagenome-wide association study on stools from individuals with atherosclerotic cardiovascular disease and healthy controls, identifying microbial strains and functions associated with the disease.
A method with high sensitivity, good accuracy and fast response is of ever increasing importance for the simultaneous detection of AA, DA and UA. In this paper, a simple and sensitive electrochemical ...sensor, which based on the polyvinylpyrrolidone (PVP)-graphene composite film modified glassy carbon electrode (PVP-GR/GCE), was presented for detecting ascorbic acid (AA), dopamine (DA) and uric acid (UA) simultaneously. The PVP-GR/GCE has excellent electrocatalytic activity for the oxidation of AA, DA and UA. The second-order derivative linear sweep voltammetry was used for the electrochemical measurements. The peak potential differences of DA-AA, DA-UA, and UA-AA (measured on the PVP-GR/GCE) were 212, 130 and 342 mV respectively. Besides, the over potential of AA, DA and UA reduced obviously, so did the peak current increase. Under the optimum conditions, the linear ranges of AA, DA and UA were 4.0 μM-1.0 mM, 0.02-100 μM, and 0.04-100 μM, respectively. The detection limits were 0.8 μM, 0.002 μM and 0.02 μM for AA, DA, and UA. The electrochemical sensor presented the advantages of high sensitivity and selectivity, excellent reproducibility and long-term stability. Furthermore, the sensor was successfully applied to the analysis of real samples.
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