Overview of mechanisms of Fe-based catalysts for the selective catalytic reduction of NOx with NH3 at low temperature.

With the increasingly stringent control of NOx emissions, NH3-SCR, one of the most effective de-NOx technologies for removing NOx, has been widely employed to eliminate NOx from automobile exhaust and industrial production. Researchers have favored iron-based catalysts for their low cost, high activity, and excellent de-NOx performance. This paper takes a new perspective to review the research progress of iron-based catalysts. The influence of the chemical form of single iron-based catalysts on their performance was investigated. In the section on composite iron-based catalysts, detailed reviews were conducted on the effects of synergistic interactions between iron and other elements on catalytic performance. Regarding loaded iron-based catalysts, the catalytic performance of iron-based catalysts on different carriers was systematically examined. In the section on iron-based catalysts with novel structures, the effects of the morphology and crystallinity of nanomaterials on catalytic performance were analyzed. Additionally, the reaction mechanism and poisoning mechanism of iron-based catalysts were elucidated. In conclusion, the paper delved into the prospects and future directions of iron-based catalysts, aiming to provide ideas for the development of iron-based catalysts with better application prospects. The comprehensive review underscores the significance of iron-based catalysts in the realm of de-NOx technologies, shedding light on their diverse forms and applications. The hope is that this paper will serve as a valuable resource, guiding future endeavors in the development of advanced iron-based catalysts.

On-Surface Isomerization of Indigo within 1D Coordination Polymers.

Natural products are attractive components to tailor environmentally friendly advanced new materials. We present surface-confined metallosupramolecular engineering of coordination polymers using natural dyes as molecular building blocks: indigo and the related Tyrian purple. Both building blocks yield identical, well-defined coordination polymers composed of (1 dehydroindigo : 1 Fe) repeat units on two different silver single crystal surfaces. These polymers are characterized atomically by submolecular resolution scanning tunnelling microscopy, bond-resolving atomic force microscopy and X-ray photoelectron spectroscopy. On Ag(100) and on Ag(111), the trans configuration of dehydroindigo results in N,O-chelation in the polymer chains. On the more inert Ag(111) surface, the molecules additionally undergo thermally induced isomerization from the trans to the cis configuration and afford N,N- plus O,O-chelation. Density functional theory calculations confirm that the coordination polymers of the cis-isomers on Ag(111) and of the trans-isomers on Ag(100) are energetically favoured. Our results demonstrate post-synthetic linker isomerization in interfacial metal-organic nanosystems.

DM-CNN: Dynamic Multi-scale Convolutional Neural Network with uncertainty quantification for medical image classification.

Convolutional neural network (CNN) has promoted the development of diagnosis technology of medical images. However, the performance of CNN is limited by insufficient feature information and inaccurate attention weight. Previous works have improved the accuracy and speed of CNN but ignored the uncertainty of the prediction, that is to say, uncertainty of CNN has not received enough attention. Therefore, it is still a great challenge for extracting effective features and uncertainty quantification of medical deep learning models In order to solve the above problems, this paper proposes a novel convolutional neural network model named DM-CNN, which mainly contains the four proposed sub-modules : dynamic multi-scale feature fusion module (DMFF), hierarchical dynamic uncertainty quantifies attention (HDUQ-Attention) and multi-scale fusion pooling method (MF Pooling) and multi-objective loss (MO loss). DMFF select different convolution kernels according to the feature maps at different levels, extract different-scale feature information, and make the feature information of each layer have stronger representation ability for information fusion HDUQ-Attention includes a tuning block that adjust the attention weight according to the different information of each layer, and a Monte-Carlo (MC) dropout structure for quantifying uncertainty MF Pooling is a pooling method designed for multi-scale models, which can speed up the calculation and prevent overfitting while retaining the main important information Because the number of parameters in the backbone part of DM-CNN is different from other modules, MO loss is proposed, which has a fast optimization speed and good classification effect DM-CNN conducts experiments on publicly available datasets in four areas of medicine (Dermatology, Histopathology, Respirology, Ophthalmology), achieving state-of-the-art classification performance on all datasets. DM-CNN can not only maintain excellent performance, but also solve the problem of quantification of uncertainty, which is a very important task for the medical field. The code is available: https://github.com/QIANXIN22/DM-CNN.

Selected Bacteria Are Critical for Karst River Carbon Sequestration via Integrating Multi-omics and Hydrochemistry Data.

Recalcitrant dissolved organic carbon (RDOC) produced by microbial carbon pumps (MCPs) in the ocean is crucial for carbon sequestration and regulating climate change in the history of Earth. However, the importance of microbes on RDOC formation in terrestrial aquatic systems, such as rivers and lakes, remains to be determined. By integrating metagenomic (MG) and metatranscriptomic (MT) sequencing, we defined the microbial communities and their transcriptional activities in both water and silt of a typical karst river, the Lijiang River, in Southwest China. Betaproteobacteria predominated in water, serving as the most prevalent population remodeling components of dissolved organic carbon (DOC). Binning method recovered 45 metagenome-assembled genomes (MAGs) from water and silt. Functional annotation of MAGs showed Proteobacteria was less versatile in degrading complex carbon, though cellulose and chitin utilization genes were widespread in this phylum, whereas Bacteroidetes had high potential for the utilization of macro-molecular organic carbon. Metabolic remodeling revealed that increased shared metabolites within the bacterial community are associated with increased concentration of DOC, highlighting the significance of microbial cooperation during producing and remodeling of carbon components. Beta-oxidation, leucine degradation, and mevalonate (MVA) modules were significantly positively correlated with the concentration of RDOC. Blockage of the leucine degradation pathway in Limnohabitans and UBA4660-related MAGs were associated with decreased RDOC in the karst river, while the Fluviicola-related MAG containing a complete leucine degradation pathway was positively correlated with RDOC concentration. Collectively, our study revealed the linkage between bacteria metabolic processes and carbon sequestration. This provided novel insights into the microbial roles in karst-rivers carbon sink.

A review of regeneration mechanism and methods for reducing soot emissions from diesel particulate filter in diesel engine.

With the global emphasis on environmental protection and the proposal of the climate goal of "carbon neutrality," countries around the world are calling for reductions in carbon dioxide, nitrogen oxide, and particulate matter pollution. These pollutants have severe impacts on human lives and should be effectively controlled. Engine exhaust is the most serious pollution source, and diesel engine is an important contributor to particulate matter. Diesel particulate filter (DPF) technology has proven to be an effective technology for soot control at the present and in the future. Firstly, the exacerbating effect of particulate matter on human infectious disease viruses is discussed. Then, the latest developments in the influence of key factors on DPF performance are reviewed at different observation scales (wall, channel, and entire filter). In addition, current soot catalytic oxidant schemes are presented in the review, and the significance of catalyst activity and soot oxidation kinetic models are highlighted. Finally, the areas that need further research are determined, which has important guiding significance for future research. Current catalytic technologies are focused on stable materials with high mobility of oxidizing substances and low cost. The challenge of DPF optimization design is to accurately calculate the balance between soot and ash load, DPF regeneration control strategy, and exhaust heat management strategy.

Effect of regeneration method and ash deposition on diesel particulate filter performance: a review.

As countries around the world pay more attention to environmental protection, the corresponding emission regulations have become more stringent. Exhaust pollutants cause great harm to the environment and people, and diesel engines are one of the most important sources of pollution. Diesel particulate filter (DPF) technology has proven to be the most effective way to control and treat soot. In this paper, we review the latest research progress on DPF regeneration and ash. Passive regeneration, active regeneration, non-thermal plasma-assisted DPF regeneration and regeneration mechanism, DPF regeneration control assisted by engine management, and uncontrolled DPF regeneration and its control strategy are mainly introduced. In addition, the source, composition, and deposition of ash are described in detail, as well as the effect of ash on the DPF pressure drop and catalytic performance. Finally, the issues that need to be further addressed in DPF regeneration research are presented, along with challenges and future work in ash research. Over all, composite regeneration is still the mainstream regeneration method. The formation of ash is complex and there are still many unanswered questions that require further in-depth research.

Selected rhizosphere bacteria are associated with endangered species - Scutellaria tsinyunensis via comparative microbiome analysis.

Scutellaria tsinyunensis is an endangered plant under extremely critical condition. Soil microbiome is important for plants growth. To better understand the endangered mechanism of S. tsinyunensis from the perspective of rhizosphere bacteria, we examined soil bacteria community in nearly all extant S. tsinyunensis populations at two altitude levels through high-throughput sequencing. Our co-occurrence network analysis manifested six key genera had active interactions with many genera. Moreover, we found that deterministic processes dominate rhizosphere bacterial community assembly. By constructing structural equation model, we found that pH as a key factor shaping the bacterial community, suggesting canopy density - pH - bacterial diversity regulatory model may contribute to the endangerment of S. tsinyunensis. Further, we revealed that Haliangium and Candidatus Koribacter act as essential genera for the protection of S. tsinyunensis through controlling multi combination of covariates. Together, our study revealed a holistic picture of rhizosphere microbiome and environmental factors associated with S. tsinyunensis, and provided direction for future protection of this endangered plant.

Depositing Molecular Graphene Nanoribbons on Ag(111) by Electrospray Controlled Ion Beam Deposition: Self-Assembly and On-Surface Transformations.

The chemical processing of low-dimensional carbon nanostructures is crucial for their integration in future devices. Here we apply a new methodology in atomically precise engineering by combining multistep solution synthesis of N-doped molecular graphene nanoribbons (GNRs) with mass-selected ultra-high vacuum electrospray controlled ion beam deposition on surfaces and real-space visualisation by scanning tunnelling microscopy. We demonstrate how this method yields solely a controllable amount of single, otherwise unsublimable, GNRs of 2.9 nm length on a planar Ag(111) surface. This methodology allows for further processing by employing on-surface synthesis protocols and exploiting the reactivity of the substrate. Following multiple chemical transformations, the GNRs provide reactive building blocks to form extended, metal-organic coordination polymers.

Adsorption of Pb(II) cation from aqueous solutions by acid modified low-rank coal: An experimental study and simulation.

An acid modified approach to enhance the adsorption capacity of low-rank coal (lignite) is proposed to reduce the risk of heavy metal ions within the wastewater. Adsorption kinetics, adsorption thermodynamics, adsorption coefficient and density functional theory DFT calculations were studied in this paper, respectively. The results indicate that the adsorption capacity of lignite was enlarged after HNO3 modification, and pseudo-second order kinetics model and Langmuir isothermal adsorption model can be used to describe the adsorption process. The surface chemical properties of lignite play a dominant role rather than the specific surface area and total pore volume in the Pb(II) cation adsorption process, and it is suggested that the adsorption of Pb(II) cation by raw lignite (RL) and modified lignite (ML) is mainly completed by chemical adsorption. The Fourier transform infrared spectroscopy (FTIR) characterization showed that the surface oxygen functional groups of lignite increased after modification. The results of interaction energies between the model molecule and Pb(II) cation show that Pb(II) cation and -C-O-C are most easily combined, followed by -COOH, and -C = O is the weakest.

Experimental Investigation of the Attachment Performance between Coal Particle and Bubble.

Attachment behavior is a key component of flotation and has a decisive influence on flotation performance, and the experiment research on the attachment between mineral particles and bubbles still needs further research. In this work, a particle-bubble attachment apparatus and multiple target tracking software were developed. Coal particles were used as the subjects, and the effect of particle properties on the attachment performance was studied from the perspective of the particle group. The particle-bubble attachment experiments indicated that the collision position had an effect on the attachment efficiency, and the attachment efficiency decreased with an increase in the collision angle. The efficiency-weighted attachment angle was proposed to quantitatively describe the attachment performance of coal samples. The efficiency-weighted attachment angle of low-density coal samples was greater than that of high-density coal samples. For particles with different sizes, the efficiency-weighted attachment angle of fine particles was greater than that of coarse particles. Furthermore, SDS weakened the attachment performance between coal particles and bubbles via adsorption on the bubble, and the efficiency-weighted attachment angle decreased as the concentration of the SDS solution increased. CTAB adsorbed on coal particles and bubbles, and the efficiency-weighted attachment angle first increased and then decreased with increasing CTAB concentration.

Fast Response Isopropanol Sensing Properties with Sintered BiFeO3 Nanocrystals.

BiFeO3 nanocrystals were applied as the sensing material to isopropanol. The isopropanol sensor based on BiFeO3 nanocrystals shows excellent gas-sensing properties at the optimum working temperature of 240 °C. The sensitivity of as-prepared sensor to 100 ppm isopropanol is 31 and its response and recovery time is as fast as 6 and 17 s. The logarithmic curves of the sensitivity and concentration of BiFeO3 sensors are a very good linear in the low detection range of 2-100 ppm. In addition, the gas sensing mechanism is also discussed. The results suggest that the BiFeO3 nanomaterial can be potentially applied in isopropanol gas detection.

Effect of Different Acid-Modified Coking Coals on Quinoline Adsorption.

The adsorption of quinoline from wastewater by coking coal (AC-1), HCl-modified coking coal (AC-2), HNO3-modified coking coal (AC-3), HF-modified coking coal (AC-4), and H2SO4-modified coking coals (AC-5) was investigated in this paper. The effects of acid-modified concentration, modification time, and adsorption time versus quinoline removal rate were studied by batch experiments. The quinoline concentration was measured by UV spectrophotometry, the average pore size and specific surface area of coking coal before and after modification were characterized through static nitrogen adsorption, the mineral composition of coking coal was tested by X-ray diffraction, the surface functional groups were tested by Fourier transform infrared spectroscopy, and the surface topography was tested using a scanning electron microscope. The experimental results showed that the adsorption capacity of coking coals was the best when both the modification time was 120 min and the acid-modified concentration was 0.1 mol·L-1 and the quinoline removal rate reaches the highest when the adsorption time was 120 min. The specific surface area of AC-2 increased from 2.898 to 3.637 m2·g-1, and the removal rate of quinoline increased from 77.64 to 90.61%. Acids reacted with inorganic mineral impurities within coking coal such as hydrogen vanadium phosphate hydrate, which caused an increase in the specific surface area. A new peak appeared in the Fourier transform infrared spectroscopy pattern at the wavenumber 2300 cm-1. The surface of coking coal modified by acids was rougher than that of AC-1. The adsorption capacity of coking coal was improved after modification, and modified coking coals have the highest potential as low-cost adsorbents for quinoline removal.

Adsorption of Methylene Blue on Bituminous Coal: Adsorption Mechanism and Molecular Simulation.

Coal with its complex porous medium and abundant oxygen functional groups could be used as an adsorbent to adsorb organic compounds. Adsorption experiments and molecular dynamics simulations were carried out to study the behavior of methylene blue (MB) on the surface of Wiser bituminous coal. The influence of adsorption through factors, such as pulverized coal dosage, adsorption reaction time, initial concentration, and temperature effect, was investigated. The removal efficiency of MB reached 96.5% under optimum reactive conditions. The adsorption equilibrium was accorded with a Langmuir isotherm adsorption equation. The adsorption of MB onto coal was a spontaneous process because the adsorption free energy ΔG 0 was negative. It was consistent with the conclusion of a negative interaction energy between bituminous coal and MB obtained by molecular dynamics simulation. Moreover, the density distribution along z-axis of each component molecule showed that MB molecules were adsorbed on the coal surface because of the polar interactions between the methyl groups of MB and the hydrophilic sites at the coal surface. Also, the diffusion degree of water molecule in liquid phase showed that as MB molecules formed hydrogen bonds with the water molecules, the activity of water molecules was restricted.

Study on the Interaction between Galena and Sphalerite During Grinding Based on the Migration of Surface Components.

In Pb-Zn ore flotation, unintentional activation of sphalerite often leads to difficult separation of Pb and Zn minerals, during which grinding plays a key role in unintentional activation. Therefore, the aim of this study was to evaluate the surface component changes of two different mineral particles and to propose the interaction between galena and sphalerite during mixed grinding using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results show that after mixed grinding of the galena and sphalerite, the Pb content on the sphalerite surface increased with the decrease of Zn and Fe contents on the sphalerite surface. The lead ions from galena were obviously absorbed onto the sphalerite surface, while the zinc and iron ions from sphalerite were not obviously migrated to the galena surface. Principal component analysis (PCA) of a dataset composed of 206 positive ion peaks of galena and sphalerite indicates that the surface components of galena and sphalerite migrated from either side to different degrees. This study successfully identified an important factor for unintentional activation of lead and zinc minerals during flotation: homogenization of surface components of different minerals during grinding.

Preparation and Tribological Properties of WS2 Hexagonal Nanoplates and Nanoflowers.

This paper presents the facile synthesis of two different morphologies of WS2 nanomaterials-WS2 hexagonal nanoplates and nanoflowers-by a sulfurization reaction. The phases and morphology of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The tribological performance of the two kinds of WS2 nanomaterials as additives in paraffin oil were measured using a UMT (Universal Mechanical Tester)-2 tribotester. The results demonstrated that the friction and wear performance of paraffin oil can be greatly improved with the addition of WS2 nanomaterials, and that the morphology and content of WS2 nanomaterials have a significant effect on the tribological properties of paraffin oil. The tribological performance of lubricating oil was best when the concentration of the WS2 nanomaterial additive was 0.5 wt %. Moreover, the paraffin oil with added WS2 nanoflowers exhibited better tribological properties than paraffin oil with added WS2 hexagonal nanoplates. The superior tribological properties of WS2 nanoflowers can be attributed to their special morphology, which contributes to the formation of a uniform tribo-film during the sliding process.

Observations of Gradual Chiral Self-Recognition of Adsorbed Aromatic Compound.

The self-assembly of two-dimensional chiral 1 H,5 H-benzo(1,2- d:4,5- d')bistriazole (H2bbta) on a Ag(110) surface was investigated by ultra-high-vacuum scanning tunneling microscopy. The gradual formation of ordered structures by H2bbta molecules with the same chirality recognizing each other was observed as the annealing temperature was increased from 300 to 333 K. When the sample was annealed at 355 K, the homochiral structures were converted to coexisting structures containing λ-H2bbta and δ-H2bbta in a ratio of 6:1. Density functional theory (DFT) calculations revealed that thermally driven and intermolecular interactions induced chiral self-recognition to form enantiomorphous H2bbta structures in which N-H···N hydrogen bonds and C-H···N hydrogen bonds are the main attractive forces.

Assembling fullerene into nanostructures over micrometer scale with atomic precision.

Assembling large organic molecules into predesigned structures for nanoscale devices is a long-standing challenge. Here, we present the atom-scale precise repositions of individual fullerene molecules and molecule transportation over the micrometer scale on a Si(111) surface via reproducible and reversible vertical manipulation by a scanning tunneling microscopy tip. A two-rod abacus consisting of ten fullerene molecules was used to perform arithmetic operations with double digits. This opens the door for the use of larger organic molecules displaying intrinsic characteristics as complex molecular devices with novel functions.

Effects and mechanistic aspects of absorbing organic compounds by coking coal.

Coal is a porous medium and natural absorbent. It can be used for its original purpose after adsorbing organic compounds, its value does not reduce and the pollutants are recycled, and then through systemic circulation of coking wastewater zero emissions can be achieved. Thus, a novel method of industrial organic wastewater treatment using adsorption on coal is introduced. Coking coal was used as an adsorbent in batch adsorption experiments. The quinoline, indole, pyridine and phenol removal efficiencies of coal adsorption were investigated. In addition, several operating parameters which impact removal efficiency such as coking coal consumption, oscillation contact time, initial concentration and pH value were also investigated. The coking coal exhibited properties well-suited for organics' adsorption. The experimental data were fitted to Langmuir and Freundlich isotherms as well as Temkin and Redlich-Peterson (R-P) models. The Freundlich isotherm model provided reasonable models of the adsorption process. Furthermore, the purification mechanism of organic compounds' adsorption on coking coal was analysed.

Synthesis of Ultrathin WS2 Nanosheets and Their Tribological Properties as Lubricant Additives.

In this paper, ultrathin WS2 nanosheets with thickness of about 5 nm were successfully prepared by a facile solid phase reaction method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). On the basis of experimental results obtained under different reaction durations, a possible formation mechanism of WS2 nanosheets is proposed. The tribological performance of ultrathin WS2 nanosheets as additives in the 500SN base oil was tested by an UMT-2 ball-on-disc tribotester, and the worn surface of the steel disc was investigated by a non-contact optical profile testing instrument and SEM. The results showed that the friction coefficient and anti-wear property of base oil can be improved strikingly by adding ultrathin WS2 nanosheets. Especially, when the concentration of WS2 nanosheets was 1.0 wt.%, the corresponding lubricating oil exhibited the best tribological properties. Moreover, according to the investigation of the wear scar, an anti-friction and anti-wear mechanism is proposed. It is believed that the reduction of friction and wear must come from the addition of ultrathin WS2 nanosheets which can penetrate and enter the friction interface and form a continuous tribofilm on the rubbing face.

Gas holdup in cyclone-static micro-bubble flotation column.

The present work has been carried out to investigate the effect of process variables on gas holdup and develop an empirical equation and a neural network model for online process control of the gas holdup based on the operating variables. In this study, the effect of process variables (nozzle diameter, circulation pressure, aeration rate, and frother dosage) on gas holdup in a cyclone-static micro-bubble flotation column of an air/oily wastewater system was investigated. Gas holdup was estimated using a pressure difference method and an empirical equation was proposed to predict gas holdup. A general regression neural network (GRNN) model was also introduced to predict gas holdup for the cyclone-static micro-bubble flotation column. The predictions from the empirical equation and the GRNN are in good agreement with the experiment data for gas holdup, while the GRNN provides higher accuracy and stability compared with that of the empirical equation.