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At present, compared with other antibiotic degradation systems, there are few literatures on pho- tocatalytic degradation of sulfadiazine (SDZ). In this research, it was firstly discovered that the oxygen-rich bismuth oxybromide (Bi24O31 Br10) photocatalyst can efficiently degrade SDZ under simulated sunlight. In this paper, the prepared Bi24O31Br10 photocatalyst by mixed solvothermal method represented outstanding photocatalytic performance. The catalyst synthesized at 120 °C and pH = 10 showed optimum degradation function in the samples prepared at various temperatures and pH value. After 3 h of irradiation, 96.2% of SDZ solution could be decomposed. The effects of preparation conditions, catalyst dosage, initial SDZ concentration and initial SDZ pH value on photocatalytic degradation efficiency were investigated systematically. Besides, the effect of active species was studied by trapping tests, and it was concluded that ‘O2 contributes the most to the photocatalytic process. A possible photocatalytic degradation mechanism was proposed.

Waste chicken feathers are the ideal precursor for the production of low-cost N-enriched biochar. KOH-modified N-enriched biochar (KNB) containing 15.92 wt% N was successfully prepared using waste chicken feathers. The adsorption kinetics results showed that KNB had rapid Cd (2 h) and Pb (1 h) adsorption rates. The Cd and Pb adsorption capacities of KNB (the values of KF were 22.324 (Cd) and 119.654 (Pb) mg1−(1/n)·L1/n·g−1) were 7.07 and 26.52 times higher than those of the original biochar based on the adsorption isotherm results. The KNB was stable at pH 3–6 and had stronger co-adsorption capacities in double-ion systems. Based on the adsorption experiments and various characterization methods, we concluded that the primary Cd and Pb adsorption mechanisms of KNB involved electrostatic interactions, cation-π interactions, complexation, and K+ exchange. The precipitation mechanism could partially account for Pb adsorption but not for Cd adsorption. KOH modification enhanced the electronegativity of biochar and then increased the electrostatic attraction. Surface O- and N-containing functional groups were involved in Cd and Pb adsorption. Graphitic-N, oxidised-N, and O C O were the main active adsorption groups, the relative contents of which increased after KOH modification, thus increasing the Cd and Pb adsorption performance. Therefore, KNB can be used as a fast and highly efficient adsorption agent to remove Cd and Pb from wastewater containing either Cd and Pb or a combination of these two metals.

In this paper, electret based vibration energy harvesters are designed and fabricated with perforated electrode based on MEMS technology. Through-holes are distributed on the fixed electrode in the device to optimize the energy harvesting process. The effect of the holes on the output power of the device are analyzed and discussed both in the finite element method (FEM) simulation and the experiments. It can be noticed that the through-holes can effectively lower the squeeze-film air damping force on the moveable proof mass at the atmosphere. Therefore, the energy loss due to the air damping could be reduced, and the output power of the device increases. The effects of the hole diameter and numbers on the output power of our device are also investigated in detail. By optimizing the configuration of the holes, the perforated device with the hole diameter of $400~\mu \text{m}$ and depth of $100~\mu \text{m}$ exhibits the highest power output at the low acceleration of 1.84 m/s2, which proves promising application for self-powered electronics in the future. [2020-0380]

Moisture is one of the important factors affecting coal spontaneous combustion. Coal with different moisture contents was prepared to obtain oxidized coal samples at different temperatures through temperature programming. In situ Fourier Transform Spectrometer was used to determine content of active functional groups in different oxidized coal samples, and to study influence of moisture form on formation and transformation of microscopic functional groups during coal spontaneous combustion. Nitrogen adsorber was used to study specific surface area of different oxidized coal samples and influence of form moisture on changes of micro-pore structure during coal spontaneous combustion. Combined with the change law of functional groups and specific surface area, microscopic action of different form moisture on coal spontaneous combustion process was discussed. The action regime of outside moisture varies with the development of coal spontaneous combustion. Different forms of moisture can promote formation of phenols, alcohols, hydroxyl groups, and carbonyl-containing compounds. Effects of moisture form and its content on change of micro-specific surface area, and on evolution of aliphatic C–H components, hydroxyl-containing compounds and carbonyl-containing compounds during spontaneous combustion of coal are different. While effect of moisture form and its content on formation and transformation of hydroxyl-containing compounds and carboxylic acid compounds are similar.

State-of-health (SOH) estimation is crucial for ensuring efficient, reliable and safe operation of power battery in electric vehicle (EV) application. However, due to the complicated physicochemical reactions happened in battery cells, it is extremely difficult to accurately estimate SOH, especially in real-world EV application scenarios. Traditional SOH estimation methods, including both model-based and data-driven ones, are deterministic, which cannot capture the stochastic property of battery aging process aroused from the inherent inconsistency during battery production. In this paper, Bayesian network (BN), which is a probabilistic graphical modeling method for indeterministic process, is used to battery degradation modeling. Its structure is derived from existing knowledge about battery aging mechanism. Two-year operational data and capacity calibration results of 16 electric taxies are collected for model training and validation. Specifically, a systematic data filling procedure is proposed to predict the missing values of variables necessary for SOH estimation. Markov Chain Monte Carlo method is adopted to generate the samples from parameterized BN for SOH estimation. Results show that the estimation result is very close to the calibrated SOH with mean absolute error below 4%. The proposed method is promising to be applied online for SOH estimation in real-world EV application.

To alleviate the pressure of energy utilization of buildings, more attention was focused on the utilization of GWSHP (groundwater source heat pump) systems. However, there have been many debates on feasibility. This paper is to study the suitability and feasibility of GWSHP systems in different climate zones. A simulation model of a GWSHP system is established based on TRNSYS software in the severe cold climate zones A and B, cold climate zones, hot summer and cold winter climate zones, and the hot summer and warm winter climate zones. Simultaneously, the reliability and energy-saving benefits of GWSHP systems in typical residential buildings situated in different climate zones are deeply analyzed. Results reveal that the operating performance of GWSHP systems is considered as the best in the climate zones that need both heating and cooling loads for residential buildings. In contrast, the energy-saving benefits of the GWSHP system in typical residential buildings are deemed to be higher in the cold climate zones and severe cold climate zones. Overall, compared with the ASHP, the economy of the system is generally better based on economic analysis.

Flow-induced acoustic resonance in the closed side branch of a natural gas pipeline can cause intensive vibration which threatens the safe operation of the pipeline. Accurately modeling this excitation process is necessary for a workable understanding of the genetic mechanism to resolve this problem. A realizable k-ε Delayed Detached Eddy Simulation (DDES) model was conducted in this study to numerically simulate the acoustic resonance problem. The model is shown to accurately capture the acoustic resonance phenomenon and self-excited vibration characteristics with low calculation cost. The pressure pulsation component of the acoustic resonance frequency is gradually amplified and transformed into a narrowband dominant frequency in the process of acoustic resonance excitation, forming a so-called “frequency lock-in phenomenon.” The gas is pressed into and out of the branch in sinusoidal mode during excitation. The first-order frequency, single vortex moves at the branch inlet following the same pattern. A quarter wavelength steady standing wave forms in the branch. The mechanism and characteristics presented in this paper may provide guidelines for developing new excitation suppression methods.

The spontaneous combustion of coal is one of the main disasters affecting safe production. In order to prevent and extinguish mine fires more efficiently, a new type of fire-suppression polymer gel...

Implementing coal to synthetic natural gas (SNG) is a key way to deal with the conflict between supply and demand of natural gas in China. For the coal to SNG process, gasification is a crucial unit, which determines the syngas composition and influences cost of coal to SNG system. In this current study, a coal to SNG system using ash agglomerating fluidized bed gasification is designed and modeled. According to the above results, the thermal performance and technoeconomic assessment of the coal to SNG system are performed. The research demonstrates that exergy efficiency and energy efficiency of the whole system are 55.37% and 61.50%, respectively. Additionally, the results of the economic evaluation show that the SNG production cost is 1.87 CNY/Nm3 with a coal price of 250 CNY/t and an electricity price of 0.65 CNY/kWh. Sensitivities to variables such as water price, electricity price, total equipment cost and coal price are performed. Coal price represents the most important sensitivity, but the sensitivity to water price is relatively small.

Most biomass derivatives were converted in the aqueous phase due to their high oxygen content, which, however, created a harsh environment for the catalytic reaction. In this work, Ru-based catalys...

The entrainment of fine particles in underflow of a grinding-classification hydrocyclone can cause ore over-grinding, reducing both the metal recovery and the ball mill throughput. This problem is addressed in this study by proposing a W-shaped hydrocyclone that effectively reduces the fine particle in the underflow. The separation performance of the W-shaped hydrocyclone was investigated in depth by experimentally studying the influences of a structural parameter, a physical property parameter, and an operating parameter on the split ratio, the yield, the product concentration, the product particle size, and the classification efficiency of the W-shaped hydrocyclone. And then the W-shaped hydrocyclone was scaled-up and successfully used in an industrial site. The results show that replacing a conventional hydrocyclone with the W-shaped one can reduce the −75 μm particle content in the underflow by 1.46 percentage points, increased the classification efficiency by 8.32 percentage points, and reduced the circulating load by 33.38%.

Eu/BiVO4 photocatalyst was synthesized by a facile one-step hydrothermal method. The structures and morphologies of Eu/BiVO4 photocatalysts were investigated by XRD, SEM and FT-IR and their photocatalytic activity was evaluated by the degradation of tetracycline hydrochloride (TCH) under the visible light irradiation. From the photocatalytic activity test, 1% Eu/BiVO4 displayed more superior photodegradation efficiency with 91.4% degradation efficiency of TCH in 150 min by contrast with 77.3% degradation rate of pure BiVO4. The mechanism has been explored that h+ is the primary active species, and ·OH is a secondary active substance in the photocatalytic process.

In this work, periodic density functional theory (DFT) calculations were performed to investigate the CO2 activation mechanism over thermodynamically stable χ-Fe5C2 (510) and θ-Fe3C (031) facets. Four major pathways of CO2 activation were examined, including the direct dissociation of CO2 and the H-assisted intermediates of *COOH, *HCOO, and *CO + *OH. Both χ-Fe5C2 and θ-Fe3C have proven to be active for CO2 direct dissociation (Ea =0.17 eV). As for H assisted CO2 activation, the one-step formation of *CO + *OH is feasible on χ-Fe5C2 (Ea =0.24 eV). Furthermore, θ-Fe3C favors the *HCOO pathway (Ea =0.20 eV) and *CO + *OH formation (Ea = 0.11 eV), while neither phase favors the formation of *COOH. Both CO2 direct activation and H-assisted CO2 activation pathways are of vital importance under high ratio of H/C in CO2 hydrogenation reaction. This work sheds light on CO2 activation mechanism over iron carbides, improving the rational design of CO2 hydrogenation catalysts.

The intrinsic exothermic reaction of coal with oxygen during low-temperature oxidation is the main heat source responsible for the self-heating and spontaneous combustion of coal. Due to the comple...

A good understanding of the intrinsic relationship between heat evolution and mass change induced by coal–oxygen oxidation reaction is critical for accurately predicting the behaviour of spontaneou...

A new and convenient visible-light-induced method has been developed for the synthesis of sulfonylated benzofurans via oxidative cyclization reaction of 1,6-enynes and arylsulfinic acids. This reaction was carried out under metal-free and mild conditions, in which the C–S, C-C and C = O bonds could be sequentially formed in one pot operation.

The fluidized bed combustor (FBC) boiler faces many control challenges such as high-order dynamics and strong nonlinearity. A hybrid control structure combining active disturbance rejection control (ADRC) and Bode ideal cut-off (BICO) is proposed to handle with these control difficulties and speed up the output responses. An empirical tuning procedure is summarized for the hybrid control structure. Simulation results show that the hybrid control structure has the best tracking performance compared with other control strategies. In addition, the hybrid control structure can obtain the satisfactory disturbance rejection performance when the FBC system has the coal quality variation or input disturbances. The superiority of the hybrid control structure can ensure the satisfactory control performance and shows a great potential in industrial applications.

It is imperative to have an in-depth understanding of CO overrun at the air return corner not only for pre-warning concentrations of safety and spontaneous combustion but also for providing scienti...

For potential applications such as suppressing the onset of peri-implant infections, a doped titania coating was developed to induce free radical release because of its ability for microbial elimination. The coatability of the sol-gel precursor is robust since the suspension's rheology can be modified to attain uniform and complete surface coverage. The coating is composed of a mixture of anatase and rutile polymorphs doped with nitrogen (N3-), and it contains substoichiometric Ti2+ and Ti3+ species. Nitrogen doping results in a 0.4 eV band gap shift, while the defects induce photocurrent generation under visible light excitation up to 650 nm. Greater currents were observed in the nitrogen-doped titania at wavelengths above 450 nm vis-a-vis its (singularly) self-doped counterparts. The (photo)electrochemical behavior and photoactivity of the coating were evaluated by assessing redox species formation in a background aqueous solution. In the absence of any illumination, the coating behaved as an insulator and inhibited the activities of both oxidative and reductive species. On the other hand, under illumination, the coating enhances oxidation processes and inhibits reduction reactions within a near-field region wherein release of free radicals occurs and is constrained (delimited).

A large number of particles with small size and light density in mine water are difficult to remove by traditional separation equipment. In order to improve the efficiency of mine water treatment, a cone-plate clarifier is proposed in this paper. The particle size distribution and their fragmentation fractal dimension were studied in 15 sampling points of the cone-plate clarifier to elucidate the process of floc growth and settling. The influence of the tangential inlet velocity size distribution characteristics was also studied. The results showed that the cone-plate clarifier can effectively improve suspended solids and turbidity removal efficiency. The floc growth and settlement courses are shown in the charts. The cone-plate clarifier was divided into four zones: micro flocculation, floc growing, settlement, and exit pipe. Because the fluid enters the cone-plate clarifier tangentially, the value of the inlet velocity and the tangential velocity are equal at the inlet feed. With the increase in tangential velocity, the flocculation efficiency first increased and then decreased. Comprehensive analysis of the particle greater than 50 μm in the effluent showed that the optimal inlet was qual to 1.63 m/s. By fitting the equations, the optimal SS and turbidity removal efficiency reached the maximum values of 92.04% and 80.18% at the inlet velocity of 1.86 m/s and 1.77 m/s, respectively.

The effective cryopreservation of mesenchymal stem cells (MSCs) is indispensable to the operation of basic research and clinical transplantation. The prevalent protocols for MSC cryopreservation utilize dimethyl sulfoxide (DMSO), which is easily permeable and able to protect MSCs from cryo-injuries, as a primary cryoprotectant (CPA). However, its intrinsic toxicity and adverse effects on cell function remain the bottleneck of MSC cryopreservation. In this work, we cryopreserved human umbilical cord mesenchymal stem cells (UCMSCs) using zwitterionic betaine combined with electroporation without any addition of DMSO. Betaine was characterized by excellent compatibility and cryoprotective properties to depress the freezing point of pure water and balance the cellular osmotic stress. Electroporation was introduced to achieve intracellular delivery of betaine, intending to further provide comprehensive cryoprotection on UCMSCs. Compared with DMSO cryopreservation, UCMSCs recovered from the protocol we developed maintained the normal viability and functions and reduced the level of reactive oxygen species (ROS) that are harmful to cell metabolism. Moreover, the in vivo distribution of thawed UCMSCs was consistent with that of fresh cells monitored by a bioluminescence imaging (BLI) system. This work opens a new window of opportunity for DMSO-free MSC cryopreservation using zwitterionic compounds like betaine combined with electroporation.

In this work, a simple chemical precipitation method was employed to prepare spherical-like Ag3PO4 material (IL-Ag3PO4) with exposed {111} facet in the presence of reactive ionic liquid 1-butyl-3-methylimidazole dihydrogen phosphate ([Omim]H2PO4). The crystal structure, microstructure, optical properties, and visible-light photocatalytic performance of as-prepared materials were studied in detail. The addition of ionic liquids played a crucial role in forming spherical-like morphology of IL-Ag3PO4 sample. Compared with traditional Ag3PO4 material, the intensity ratio of {222}/{200} facets in XRD pattern of IL-Ag3PO4 was significantly enhanced, indicating the main {111} facets exposed on the surface of IL-Ag3PO4 sample. The presence of exposed {111} facet was advantageous for facilitating the charge carrier transfer and separation. The light-harvesting capacity of IL-Ag3PO4 was larger than that of Ag3PO4. The photocatalytic activity of samples was evaluated by degrading rhodamine B (RhB) and p-chlorophenol (4-CP) under visible light. The photodegradation efficiencies of IL-Ag3PO4 were 1.94 and 2.45 times higher than that of Ag3PO4 for RhB and 4-CP removal, respectively, attributing to a synergy from the exposed {111} facet and enhanced photoabsorption. Based on active species capturing experiments, holes (h+), and superoxide radical (•O2−) were the main active species for visible-light-driven RhB photodegradation. This study will provide a promising prospect for designing and synthesizing ionic liquid-assisted photocatalysts with a high efficiency.

The introduction of nanostructures is an effective method to boost the photovoltaic performance of hybridized organic-inorganic halide perovskite-film solar cells. Taking into account their excellent light-scattering in the ultraviolet–visible range and their chemical inertness, silicon ( Si ) nanorods can be incorporated into the perovskite-film solar cells to enhance the light harvesting of the devices. By depositing Si nanorods between the prepared film and the substrate, the light scattering induced by the Si nanorods significantly promoted light absorption of the films. Moreover, resulting from the incorporation of Si nanorods, the enlarged grain size and compact structure of the films prolonged the lifetime of the carriers, which promoted the photoelectric properties of the perovskite films. By the appropriate incorporation of Si nanorods, the photovoltaic conversion efficiency of the CH 3 NH 3 Pb(Br 0.25 I 0.75 ) 3 -film-based solar cell was increased from 12.6% to 14.9% and the relative stability of the devices under dark humidity was improved. This strategy of employing low-cost and easily prepared Si nanorods to enhance the light harvesting of perovskite photovoltaic devices could be applied to photovoltaic devices based on perovskite films with other compositions.

Soil organic nitrogen fractions and soil-soluble nitrogen pools are important indicators of soil fertility and plant nutrition requirements. However, little is known about soil organic nitrogen fractions and their correlations with soil mineral nitrogen (SMN) and soluble organic nitrogen (SON). A five-year field experiment was conducted to determine the effects of lower irrigation limits (25, 35, and 45 kPa) and nitrogen fertilization (75, 300, and 525 kg ha−1) rates on greenhouse soil organic nitrogen fractions and soil-soluble nitrogen pools. The results indicated that the soil organic nitrogen fractions and soil-soluble nitrogen pools were significantly affected by the irrigation and nitrogen fertilization rates and their interactions at various greenhouse soil depths (P

The deconvolution and resolution of overlapping bands in the Raman spectra of a suite of coals studied by curve-fitting methods has improved our understanding of the main structural changes in naturally matured coals. Even though much work on deconvolution of Raman spectra has been done, the systematic evolution of chemical structures is not well established. In this study we used a suite of 28 coal samples from Australia with vitrinite reflectance ranging from 0.38 to 3.52%. The micro-Raman spectra of vitrinite macerals from selected coals were acquired using a custom-made Raman spectrometer and supplemented by other Raman spectra previously acquired under the same experimental conditions. In the spectral deconvolution procedure, the second derivative curve-fitting method was used to determine the number of peaks and peak positions of the Raman spectra. Each band was tentatively assigned to a corresponding chemical structure by references to the interpreted major structural changes likely to have taken place during coalification. These parameters included PD (the position of D band), RBS (the distance between G band and D band), FWHMG (full width at half maximum of G band), IG/IGL (the intensity ratio of G band and GL band), and AR/b (the ratio of Raman integrated area and the slope of the spectral background). All of these Raman parameters are found to have a very good correlation with Ro% with R2 higher than 0.90. While five simple equations have been proposed and may be used to estimate thermal maturity of coals, two equations (Eq. (4) for Ro% from 0.38 to 1.5 and Eq. (5) for Ro% from 1.5 to 3.52) are best suitable to predict thermal maturity of coals with the most accuracy.

The mobile industrial human-machine interaction plays an important role in the industrial internet of things, since the engineers can use a mobile device to interact with machines that greatly improves the efficiency and safety. Nevertheless, connecting to a specific machine becomes a non-trivial problem due to the massive machines in the network that make the connection list too long to identify the target machine. Some solutions such as QR code scanning and proximity estimation have been proposed to solve this problem. However, they have limited performance in scalability and accuracy correspondingly, and thus cannot satisfy the requirements in most applications. Observing the fact that the engineers generally interact with the machines in their line-of-sight, we propose the LightCon scheme which adopts proximity estimation to estimate the machines in the line-of-sight, and controls the display module of machines to show different visible symbols (colors or numbers). To connect with a specific machine, the engineers just need to select the corresponding symbol on the mobile device. Therefore, they do not have to remember the trivial address of each machine. Furthermore, the symbol assignment algorithm is designed to reduce the complexity of manual symbol selection, and its performance is analyzed theoretically. The performance of LightCon is evaluated in the testbed, and the experimental results prove that LightCon is a promising solution to simplify line-of-sight connections with low complexity.

The hydrogenation of CO2 to CH3OH is one of the most promising technologies for the utilization of captured CO2 in the future. Nano Ni–Ga bimetallic catalysts have been proven to be excellent catalysts in the hydrogenation of CO2 to CH3OH. To investigate the promotion mechanisms of Ga for the hydrogenation of CO2 to CH3OH over Ga-doped Ni catalysts and the wide application of these promotion mechanisms in other catalysts and reactions, herein, density functional theory (DFT) was employed. The reaction mechanisms and the properties of Ni(211) and Ga–Ni(211) surfaces were comparatively studied. The results show that the Ni sites on both the Ni(211) and the Ga–Ni(211) surfaces are active sites, and the most stable structures of the intermediates are similar. Moreover, the Ga–Ni(211) surface is more favorable for the hydrogenation of CO2, whereas Ni(211) is more favorable for the dissociation of CO2. The activation barrier of the rate-limiting step in the CH3OH formation pathway on Ni(211) is 0.54 eV higher than that on Ga–Ni(211). According to the analyses of the projected density of states (PDOS) and Hirshfeld charge transfer, the addition of Ga atoms demonstrates the reactivity of the Ga-doped Ni(211) surfaces. Most importantly, the replacement of some secondary active sites of Ni atoms with the non-active Ga atoms may lower the activities of the secondary active sites and strengthen the activities of the active sites at the step edge. These results provide a new perspective for the reaction mechanism of the hydrogenation of CO2 to CH3OH over the state-of-the-art Ga-doped catalysts.

A novel electrochemically activated nanocomposite, CoS2 Nanoparticles and MoS2 Nanosheets decorated poly(diallyldimethylammonium chloride)-functionalized graphene (CoS2-MoS2-PDDA-GR), was successfully synthesized through a simple and low-cost method. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV) techniques were used to characterize the nanocomposites. Based on the CoS2-MoS2-PDDA-GR nanocomposite modified glassy carbon electrode, the electrochemical properties of eriocitrin were investigated in detail and a sensitive determinative method was established synchronously. Compared with others, this sensor exhibited larger effective surface area, more reactive site and excellent voltammetric response for eriocitrin. Under optimum conditions by DPV, the oxidation peak currents responded to eriocitrin linearly over a concentration range from 2.0 × 10−9 to 1.0 × 10−6 mol L−1 with a detection limit of 6.7 × 10−10 mol L−1 (S/N = 3). In addition, this fabricated sensor was successfully applied to detect eriocitrin in real samples with satisfactory results.

Oiling-out crystallization of β-alanine was conducted in water–ethanol solvent mixtures, and the roles of oiling-out on the crystallization of β-alanine were investigated during the crystal nucleation and growth stages, respectively. Nucleation metastable zone width broadened with an increase of saturation temperature when oiling-out occurred, contrary to that observed in absence of oiling-out. This observed phenomenon could be explained by the solvent composition change in the nucleation phase (dense oil droplets) under different temperatures. In the crystal growth stage, the size of oil droplets could be controlled by varying agitation speeds. The resulting crystals were lumpy with bulges on specific surfaces when the agitation speed exceeded a certain level. It was supposed to be that the absorption of oil droplets on the crystal surfaces during growth stage led to the surface nucleation, and then the bulges formed consequently. Such performance was never revealed in normal single-phase crystallization...

Generally, the improvement in the strength comes at the cost of the ductility and toughness for most metallic materials. Here, an exceptional synergy of high strength (σy ~ 453.8 MPa), ductility (ef ~ 24.5%) and static toughness (Ur ~ 115.0 MJ/m3) is achieved in a low-carbon steel subjected to torsion deformation and annealing treatments, compared with that (σy ~ 282.4 MPa, ef ~ 27.3% and Ur ~ 102.9 MJ/m3) of its coarse-grained counterpart. The enhancement of mechanical properties is attributed to the formation of a specific gradient structure with a thickness of ~ 3 mm, that is, the ferrite size increases while the volume fraction of the pearlite decreases continuously with the depth from the sample surface to the core. The strengthening and toughening mechanisms of the gradient-structured low-carbon steel are also discussed.

It is imperative to have an in-depth understanding of the relationship between oxygen consumption and gaseous product emissions during coal self-heating not only for preventing fires in the coal industry but also for reducing emissions of hazardous gases. Two typical coal samples with high tendency of spontaneous combustion were heated to 230 °C with a programmed temperature of 1.0 K min−1 using a pilot-scale test apparatus. The trends for oxygen consumption and gaseous product emissions were obtained from continuous measurements of the gas samples at the reactor outlet via a gas chromatography equipped with a Flame Photometric Detector. Based on the rates of oxygen consumption and gaseous product emissions, the relationship between oxygen consumption and each gaseous product emission was studied. Multi-linear regressions of the oxygen consumption and gaseous product emissions were performed. The coefficients for the emission rates of CO2, CO and H2 in the regression equations of the two coals with three different particle sizes are found to be all positive, while the coefficients for the CH4 emission rates are all negative. These results indicate that the oxygen consumption of coal facilitates the release of CO2, CO and H2, while the increase of oxygen consumption rate may not enhance the release of hydrocarbon gas. Based on the results, an evaluation index defined as the ratio of oxygen consumption rate to the gaseous product emission rate is proposed to assess the state of coal spontaneous combustion.

We report that a gradient structured Zr processed by asymmetric rolling and partial annealing possesses an exceptional synergy of high strength (σy ∼ 550 MPa) and high tensile ductility (eu ∼ 10.1%) much better than that (σy ∼ 250 MPa and eu ∼ 14.2%) of its coarse-grained (CG) counterpart. This gradient structure is characterized by a gradient dislocation density distribution from the surface to the core and composed of microscale and ultra-fined elongated grains connected by low angle grain boundaries (LAGBs). These findings can provide valuable insight for designing gradient structures with excellent mechanical properties.

A series of catalysts were prepared using molybdenum sulfide clusters as precursors and their catalytic performance for higher alcohols synthesis was evaluated. It was found that the cluster precursors could provide well-dispersed MoS2 particles and a number of coordinated unsaturated Mo sites with all the catalysts in varying degrees, which were favorable for the formation of intermediate active phases thereby enhancing catalytic performance. In particular, K-NiMo3Sx catalyst obtained by using heterobimetallic cluster NiMo3S13 as precursor exhibited the highest activity with the space-time-yield (STY) of total alcohols (497 mg/g/h) and the selectivity of higher alcohols (59.71%), which could be attributed to the interaction effect of the Ni promoter and Mo species and the resultant formation of active phase NiMo3Sx. Thus, the most key factor for obtaining highly efficient molybdenum sulfide catalysts was to produce a number of coordinated unsaturated sites, on which abundant NiMoS active phase can be formed and the formation of bulk inactive phase should be avoided.

In present study, the feasibility of applying a natural adsorbent with Fe3+ modification (Fe3+-modified argillaceous limestone, FAL) on the competitive adsorption of heavy metals (i.e., Cd2+, Pb2+ and Ni2+) was evaluated. The current results revealed an efficient adsorption on Cd2+, Pb2+ and Ni2+ in mono-metal system. Further experiments demonstrated a high selectivity of Pb2+ during the competitive adsorption of Cd2+, Pb2+ and Ni2+. The adsorption selectivity of the metal ions followed the order of Pb ≫ Cd > Ni. In addition, both pH and ionic strength are important factors affecting the metal adsorptions. It is interestingly that various NOMs (i.e., humic acid (HA) and glycine (Gly)) exerted different effects on the adsorption behaviors, probably due to the different affinities for Pb2+, Cd2+ and Ni2+ and the redistribution of newly-formed metal-DOM complexes. X-ray photoelectron spectroscopy (XPS) analysis together with X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) analysis revealed that the metal adsorptions were mainly regulated via the synergistic mechanisms of ion exchange by Na+, Ca2+, and Al3+, precipitation to form CdCO3 and Pb2(OH)2(CO3)2, as well as complexes of FAL-OPb and FAL-ONi by hydroxyl groups on the surface of FAL. The application of FAL would be a promising option in leading to an efficient heavy metal removal.

The nanocomposite of ruthenium oxide (RuO2) loaded on Poly-(dimethyldiallylammonium chloride) (PDDA) functionalized reduced graphene oxide (RuO2-PDDA-rGO) was synthesized based on a one-step method. Based on the RuO2-PDDA-rGO modified glassy carbon electrode (GCE), a new electrochemical sensor (RuO2-PDDA-rGO/GCE) was fabricated and used in detection of baicalein for the first time. Compared with other reported electrochemical sensors for the detection of baicalein, the prepared RuO2-PDDA-rGO/GCE had a wider linear range (2–400 nM) and lower detection limit (0.6 nM, S/N = 3). The other advantages were the excellent repeatability of proposed method and good stability of prepared sensor.

Complex weather factors seriously affect the quality and accuracy of image processing, and indirectly pose severe challenges to the expansion of IoT applications in smart cities and the actual intelligent classification of research. However, the current research on weather classification cannot comprehensively deal with composite weather classification, and the accuracy and processing time are still not satisfactory. This is still a challenge for the popularization of IoT applications. This paper proposes a multi-weather classification method that can intelligently classify the weather elements in the image data collected by the IoT applications. The idea behind us is to propose the evolutionary algorithm into EfficientNet to solve the various weather classification problem. Our experimental results show that we can achieve remarkable classification results with a high degree of confidence in five complex weather conditions, even in pictures with obvious weather characteristics, and the recognition accuracy increases to more than 95%.

Cadmium (Cd) and tetracycline (TC) cause serious environmental risks. Nanomaterials have been extensively applied for environmental remediation. The size and content of nanoparticles directly affect the removal of contaminants. However, size regulation and quantitative determination of nanoparticles cannot be easily realized. In this study, hydrogels with different polymerization degrees were prepared by adjusting the contents of acrylamide (AM) and sodium lignosulfonate polymeric monomers. Ferrous sulfide (FeS) nanoparticles of different sizes were synthesized in situ within the hydrogels. The nanoparticle size decreased from 600 to 200 nm with increasing hydrogel polymerization degree, and an incomplete crystalline state was observed at the highest polymerization degree. By combining energy dispersive spectroscopy (EDS) images with the maximum between-class variance (Otsu) method, the content of nanoparticles was calculated to be 7.81%, 15.05%, 22.62%, 27.10%, 21.97%, and 23.95%. The distribution state of FeS compounds was also obtained. A low polymerization degree resulted in high FeS dispersal, and a high polymerization degree affected the uniformity distribution based on irregular ion diffusion. The obtained nanocomposites with different polymerization degrees were applied to the removal of Cd and TC in water. The removal capacity for both contaminants revealed a trend of initially increasing and then decreasing. The initial increase was related to the increasing content and decreasing size of the FeS nanoparticles, while the following decrease was due to the decreasing content and incomplete crystallization of the FeS nanoparticles. Overall, changing the proportion of polymeric monomers is an effective way to regulate particle size, and the Otsu method combined with EDS mapping images is a feasible method for calculating the content of nanoparticles.

Fine particles misclassification in the underflow (UF) of grinding-classification hydrocyclones might result in ore over-grinding, leading to both reduced ball mill throughput and metal recovery. In the current research, a W-shaped hydrocyclone is proposed, to efficiently decrease the misclassification of fine particles in UF. The effects of the following parameters (including cross-effects) on W-shaped hydrocyclone classification performance were studied experimentally&mdash, inlet pressure, apex diameter, and vortex finder insertion depth and diameter. A mathematical model on the basis of the response surface method was established for the prediction of W-shaped hydrocyclone separation performance. The significance of the effects of the factors on the fine particle content in UF decreased in the following order&mdash, vortex finder diameter &gt, inlet pressure &gt, vortex finder insertion depth &gt, apex diameter. The significance of influences of different factors on quality effectively decreased in the following order&mdash, apex diameter. The significance of factor effects on the quantity efficiency decreased in the following order&mdash, apex diameter &gt, vortex finder diameter. All influence factors were considered to obtain the optimal parameter configuration&mdash, an apex diameter of 0.14 D, a vortex finder diameter of 0.31 D, an insertion depth of 1.87 D, and an inlet pressure of 0.18 MPa. The corresponding optimal result was a &minus, 25 &mu, m particle content (C&minus, 25) in UF of 11.92%, a quality efficiency of 42.48%, and a quantity efficiency of 98.99%.

The Biliu River is the largest river in Dalian. The occurrence of floods and droughts in this basin has extremely important impacts on local industry, agriculture, and urban development. For a long time, the annual distribution of precipitation in the Biliu River Basin is extremely uneven, the river runoff varies greatly from year to year and season to year, floods and droughts occur frequently, and serious soil erosion results in fragile ecological environment and severe shortage of water resources. In this paper, the spatial and temporal changes of rainfall and runoff in the Biliu River Basin are studied through the coupling of the MIKE 11 model and the MIKE SHE model. The hydrological changes in the Biliu River Basin are simulated. The coupled model is verified by monthly runoff data from 1996 to 2015, and the simulation values are found to be true. The values match well. Based on the cyclical pattern of precipitation and runoff in the Biliu River Basin, the rainfall and runoff data in the Biliu River Basin from 2016 to 2030 are derived. The MIKE SHE/MIKE 11 coupling model is used to predict the Biliu River from 2016 to 2030. The results show that flood disasters are expected to occur in August 2020, July 2025, and July 2030, which can provide a basis for hydrological management in the Biliu River Basin.

Biomass furfural-like compounds are chemicals that cannot be extracted from fossil materials, through which a large number of fine chemicals and fuel additives can be opened up, but one big efficiency problem during the transformation is the accumulation of oligomers. Here, we propose a novel and efficient Ru-Mo bimetallic catalyst for selective hydrogenation-rearrangement of furfural-like compounds. The result showed that an unprecedented rearrangement product selectivity of 89.1% to cyclopentanol was achieved under an optimized reaction condition over a 1%Ru−2.5%Mo/CNT catalyst reduced at 600°C. Subsequent characterization suggested that the catalyst presented with weak acidity and strong hydrogenation activity for the reaction, which not only ensures the smooth hydrogenation-rearrangement reaction but also inhibits the accumulation of furan polymers. These findings provide a convenient strategy to tune the catalytic performance of Mo-based catalysts by controlling the reduction and carburization conditions, which appear to be versatile for the rearrangement of furans and similar compounds.

Using the extended STIRPAT model, this research examines the influence of various factors on US carbon emission from 1960 to 2019, including nuclear and alternative energy of total, fossil energy of total, GDP per capita, total population, urban population of total and merchandise trade of GDP. Ridge regression was used to perform the study. The research results show the significant of all factors on carbon emission. The estimated elastic coefficients reveal the most important factor influencing carbon emission is merchandise trade of GDP. GDP per capita has negative impact on carbon emission. Nuclear and alternative energy of total, urban population of total are also prominent influencing factors, while the other factors such as total population and fossil energy of total have less significant impact on carbon emission in US. These findings of this research will be of great significance for US to control its carbon emission in the future and to mitigate the global warming to some extent.

The degradation of bisphenol A (BPA) in spiked soil was studied to investigate persulfate (PS) activation by the environment-friendly heterogeneous material greigite for removing organic pollutants from soil. The effects of the PS and greigite doses were investigated, and the BPA degradation rate in the lateritic red soil was lower than that in kaolin. Notably, 500 mg/kg of BPA could be effectively removed by the flower-like greigite (FLG)/PS system in 30 min. The difference in BPA degradation in kaolin and the lateritic red soil was negligible, thus indicating that the contents of components such as total organic matters in the lateritic red soil did not affect the BPA degradation rate of the FLG/PS system considerably. Furthermore, the distribution processes of BPA in the soil and liquid phase were also investigated in detail. The results showed that the water contents were a key factor in the distribution and degradation of BPA. The transfer of BPA from kaolin to the liquid phase was simpler than that from the lateritic red soil to the liquid phase. BPA might be transferred to the liquid phase first and then degraded by the FLG/PS system in that phase. Regarding BPA degradation in the lateritic red soil, BPA was degraded in the soil and liquid phases at the same time. This study proposed a pathway for BPA degradation in soil slurries by heterogeneous material/PS systems for first time, providing a deeper understanding of the degradation mechanism of organic pollutants in soil and new methods for soil remediation.

Seebeck coefficient measurements provide unique insights into the electronic structure of single-molecule junctions, which underpins their charge and heat transport properties. Since the Seebeck coefficient depends on the slope of the transmission function at the Fermi energy (EF), the sign of the thermoelectric voltage will be determined by the location of the molecular orbital levels relative toEF. Here we investigate thermoelectricity in molecular junctions formed from a series of oligophenylene-ethynylene (OPE) derivatives with biphenylene, naphthalene and anthracene cores and pyridyl or methylthio end-groups. Single-molecule conductance and thermoelectric voltage data were obtained using a home-built scanning tunneling microscope break junction technique. The results show that all the OPE derivatives studied here are dominated by the lowest unoccupied molecular orbital level. The Seebeck coefficients for these molecules follow the same trend as the energy derivatives of their corresponding transmission spectra around the Fermi level. The molecule terminated with pyridyl units has the largest Seebeck coefficient corresponding to the highest slope of the transmission function atEF. Density-functional-theory-based quantum transport calculations support the experimental results.

In order to solve the problem of unclear evolution paths after oil–gas storage and transportation accidents, which lead to a lack of targeted accident emergency, delayed disposal measures,...

The remediation of soil contaminated by 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) remains an important issue in environmental research. Although our previous studies demonstrated that earthworms could enhance the degradation of DDT in soils, the underlying mechanisms and microorganisms involved in these transformation processes are still not clear. Here we studied the transformation of DDT in sterilized/non-sterilized drilosphere and non-drilosphere matrices and identified DDT degraders using the technique of DNA-stable isotope probing. The results show that DDT degradation in non-sterilized drilosphere was quicker than that in their non-drilosphere counterparts. Earthworms enhance DDT removal mainly by improving soil properties, thus stimulating indigenous microorganisms rather than abiotic degradation or tissue accumulating. Ten new genera, including Streptomyces, Streptacidiphilus, Dermacoccus, Brevibacterium, Bacillus, Virgibacillus, were identified as DDT ring cleavage degrading bacteria in the five matrices tested. Bacillus and Dermacoccus may also play vital roles in the dechlorination of DDTs as they were highly enriched during the incubations. The results of this study provide robust evidence for the application of earthworms in remediating soils polluted with DDT and highlight the importance of using combinations of cultivation-independent techniques together with process-based measurements to examine the function of microbes degrading organic pollutants in drilosphere matrices.

The charge stability of electret materials can directly affect the performance of electret-based devices such as electrostatic energy harvesters. In this paper, a spray-coating method is developed to deposit an electret layer with enhanced charge stability. The long-term stability of a spray-coated electret is investigated for 500 days and shows more stable performance than a spin-coated layer. A second-order linear model that includes both the surface charge and space charge is proposed to analyze the charge decay process of electrets in harsh environments at a high temperature (120 °C) and high humidity (99% RH); this model provides better accuracy than the traditional deep-trap model. To further verify the stability of the spray-coated electret, an electrostatic energy harvester is designed and fabricated with MEMS (micro-electromechanical systems) technology. The electret material can work as both the bonding interface and electret layer during fabrication. A maximum output power of 11.72 μW is harvested from a vibrating source at an acceleration of 28.5 m/s2. When the energy harvester with the spray-coated electret is exposed to a harsh environment (100 °C and 98% RH), an adequate amount of power can still be harvested even after 34 h and 48 h, respectively.

The CO formation rules of coal were analyzed by a self-developed testing device under ambient temperature. The changes of functional groups caused by oxidation were obtained using Fourier-transform infrared spectroscopy (FTIR). The experimental results showed that CO was generated during the ambient temperature oxidation. The highest concentration level of CO could be 389 ppm. The methylene and aldehyde groups on the side chains were involved in the reaction. For the quantum mechanical approach, we employed the density functional theory with the 6&ndash, 31 G (d, p) basis set. Density functional theory&ndash, based computations interpreted the possible reaction sites on a coal molecule by electronic static potential analysis. The rationality of the predicted reactions was also evaluated by transition state analysis and energy analysis. This research theoretically proved that coal could be oxidized to carbon monoxide under ambient temperatures and gave the possible reaction paths.

It is imperative to have an in-depth understanding of the effect of extraneous moisture on the spontaneous combustion of coal not only for the control and prevention of coal spontaneous combustion in the coal mining industry, but also for the optimization design and application of the technological process. In this study, the type of moisture in a coal body has been redefined for the first time from the perspective of disaster prevention and control, i.e., original occurrence of moisture in the coal matrix and the extraneous moisture from the technological process. A suit of coal bodies with different extraneous moisture was prepared by soaking long-flame coal with a low water content. Using a temperature-programmed oxidation test, the effects of extraneous moisture on the temperature increase rate of coal bodies and the emission characteristics of gaseous products during coal spontaneous combustion were studied. Moreover, combined with the characterization of thermal analysis and of pore structure test, the action the mechanism of extraneous moisture on the coal spontaneous combustion process was also explored. The experimental results indicated that the effect of the extraneous moisture content varied with the development of coal spontaneous combustion. In the slow oxidation stage, extraneous moisture played a physical inhibition role in the coal oxidation. In the accelerated oxidation stage, extraneous moisture exhibited a catalytic effect on the coal–oxygen reaction or directly participated in the reaction. After entering the rapid oxidation stage, a delayed effect appeared. When the coal temperature exceeded 180 °C, the spontaneous combustion characteristics of coals with different initial moisture contents gradually tended to achieved balance.

Graphene oxides (GOs) have received significant attention as emerging biomedical materials due to their special properties. The application of GOs in biological systems has raised considerable concern about their hepatotoxicity, however their biological effects on parenchymal hepatocytes remain unclear, despite the fact that GOs have shown size-dependent interactions with immunocytes in the liver. Herein we chose pleiotropic cytokine IL-6 as the model parameter to investigate inflammation responses upon exposure to GOs. An early and sensitive reporter mouse model was constructed, allowing non-invasive and longitudinal imaging of parenchymal hepatocyte IL-6 expressions. GOs of various lateral dimensions were assessed by using the reporter mice. The results demonstrated that large-sized GOs (L-GO) induced much stronger IL-6 activation. A detailed analysis uncovered that L-GO induced ROS production and TLR-4 activation promoted macrophage polarization and secretion of pro-inflammatory cytokines IL-1β and TNF-α, activated via> the NF-κB signaling pathway, which in turn initiated the expression of IL-6 in hepatocytes. These in-depth investigations are expected to help modulate the inflammatory responses involved in hepatotoxicity and provide extended information to design sub-hepatic distribution and cell subset targeting by controlling the nanoparticle sizes.