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The present research on intelligent bearing fault diagnosis assumes that the same feature distribution is used to obtain training and testing data. However, the domain shift (distribution discrepancy) issue generally occurs in both datasets because of different operational conditions. The domain adaptation techniques are preferably applied for fault diagnosis to handle the domain shift issue. Moreover, collecting sufficient testing data or labelled data in real industries is a challenging task. Therefore, the multi-kernel joint distribution adaptation (MKJDA) with dynamic distribution alignment is proposed for bearing fault diagnosis. This method dynamically joins both the marginal and conditional distributions and uses the multi-kernel to solve the non-linear problems to extract the most effective and robust representation for cross-domain issues. Moreover, it runs with the unlabelled task domain to perform the diagnosis by iteratively updating the pseudo code. The experimental results (two public datasets and one experimental dataset) demonstrated that the proposed method (MKJDA) exhibited stable and robust accuracy while conducting bearing fault diagnosis. It can effectively address the most crucial issue: intelligent diagnosis methods must re-train the model when the distribution differs between the source domain (the model is learned) and the target domain (the learned model is applied).

The coaxiality and unbalance are the two important indexes to evaluate the assembly quality of an aeroengine. It often needs to be tested and disassembled repeatedly to meet the double-objective requirements at the same time. Therefore, an intelligent assembly method is urgently needed to directly predict the optimal assembly orientations of the rotors at each stage to meet the double-objective requirements simultaneously. In this study, an assembly optimization method for the multistage rotor of an aeroengine is proposed based on the genetic algorithm. Firstly, a spatial location propagation model is developed to accurately predict the spatial position of each rotor after assembly. The alignment process of the assembly screw holes of the adjacent rotors is considered for the first time. Secondly, a new assembly optimization strategy is proposed to select different assembly data for the specific values of the coaxiality and unbalance, respectively. Finally, a double-objective fitness function is constructed based on the coaxiality and unbalance. The simulation and experimental results show that the assembly optimization method proposed in this study can be utilized to achieve synchronous optimization of the coaxiality and unbalance of an aeroengine during preassembly.

In order to develop the degradation technology of toxic and refractory pollutants, a new Rhodamine B-sensitized BiOClBr photocatalyst was synthesized by a simple impregnation method. Different from the previous work, this work made good use of the pollutant RhB. The dye RhB acted as a component of the nanocomposite. The sensitization of the dye not only promotes the effective degradation of 2,4,6-TCP, but also RhB itself. The morphology, structure, optical and electrochemical properties of the as-prepared catalyst were systematically characterized. The factors affecting photocatalytic removal 2,4,6-TCP (dosage, initial concentration and pH) were optimized by modeling the 3D surface response. Under visible light irradiation, the removal rate of 2,4,6-TCP can reach 92.3% in 80 min at an optimal initial concentration of 10 mg·L − 1, a pH of 4.2 and a dosage of 16.2 mg. The photocatalytic mechanism of the material was discussed in conjunction with the energy band structure and capture agent experiment. The main active species are h+ and ·OH. This research provides a new idea for the simultaneous treatment of dye and chlorophenol wastewater.

The graphitic carbon nitride (g-C3N4) and the Fe3O4/g-C3N4 magnetic materials were synthesized in this paper. The structures of the materials were confirmed by a series of analysis. The Fe3O4/g-C3N4 was then used as a sorbent to adsorb polychlorinated diphenyl ethers and polychlorinated biphenyls. Different extraction conditions were examined, including adsorbent amount, salinity, pH of the sample matrix, adsorption time, reaction temperature, elution solvent and preconcentration factor. The maximum recoveries were obtained by employing methanol to desorb pollutants on 40.0 mg Fe3O4/g-C3N4 in 120.0 mL environmental water with a salinity of 5% (w/v) at a pH of 7 at 25 °C within 10 min. Using the optimized parameters, the detection limits of the method are between 0.01 and 0.04 μ · L−1 with a satisfying linear relationship. The adsorbent can be recycled at least 10 times with no significant reduction in the extraction efficiency.

Photocatalytic oxidation technique is considered as one of the most prospective approaches to solve the problem of environmental pollution. Herein, the novel ternary nanocomposite UiO-66(Ce)/Ag/BiOBr was fabricated via simple synthetic strategy. The obtained UiO-66(Ce)/Ag/BiOBr exhibited an excellent performance and photocatalytic efficiency of ketoprofen reached 93.5% after 180 min illumination. The ·OH and ·O

The Z-scheme Bi2WO6/NaBiO3 nanocomposites were first fabricated by a facile hydrothermal method, and were then characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometer, Fourier-transform-infrared spectroscopy, X-ray photoelectron spectroscopy and N2 adsorption–desorption. The as-prepared Bi2WO6/NaBiO3 nanocomposites exhibit outstanding photocatalytic activity and recyclability. A 98.4% photodegradation of 2,3-dichlorophenol (50 mg·L−1) was attained in the presence of Bi2WO6/NaBiO3 (1:10) under the visible-light irradiation in 30 min. In particular, the photocatalytic mechanism has been discussed in detail, based on four aspects: (1) oxidative species, (2) photoelectrochemical performance, (3) conduction band and valence band energy levels and (4) possible transition states and reactions. In conclusion, O−2 is the main active oxidative species in the Bi2WO6/NaBiO3 nanocomposite. The material has higher photocurrent and visible light adsorption but lower electron–hole pairs recombination, which contributes to distinguished photocatalytic efficiency. The Z-scheme photocatalytic path was proposed and the possible degradation process and routes have been summarized.

The aperture of KIT-6 can influence the recoveries of magnetic solid phase extraction. In this context, aperture regulated magnetic KIT-6 was prepared and characterized to improve the performance in the detection of deltamethrin and permethrin diastereomers. The novel Fe3O4@SiO2@KIT-6/130 °C nanocomposite was selected for the extraction of pyrethroid insecticides including deltamethrin, cis-permethrin and trans-permethrin. The variables influencing the extraction process such as the material dosage, adsorption time, pH, salinity of the solution, desorption solvent and enrichment factor were evaluated. The method has the advantages of low LODs, a wide linear range, good reproducibility and acceptable recoveries. Under the optimal conditions, the recoveries are between 88.5% and 95.4%. The adsorption process corresponds well with pseudo-second order kinetics and Langmuir adsorption isotherms. The process is spontaneous and exothermic on the basis of thermodynamic records. Magnetic solid phase extraction coupled with high performance liquid chromatography based on the Fe3O4@SiO2@KIT-6/130 °C nanocomposite offers an easy and sensitive way to detect trace pyrethroid insecticides in environmental water samples.

Accident statistics show that more than 80% of car-to-pedestrian collisions (CPC) occur when pedestrians cross the road. It is very important to establish a finite element model with natural walking posture to study the kinematics and injury mechanism of pedestrians. In this study, a finite element model of six-year-old child pedestrian is developed with detailed anatomical characteristics and posture parameters as specified in Euro NCAP Pedestrian Human Model Certification (TB024). The numerical human body model is validated in total twelve simulations in which the pedestrian is impacted against four generic vehicle models at speeds 30, 40, 50 km/h prescribed in TB024. The Head Impact Time (HIT), Contact Force and the Trajectories of HC, T12 and AC of all twelve simulations are compared with the reference corridors provided by Technical Bulletin 024. The results indicate that the numerical human body model of a six-year-old child can be used to demonstrate the suitability of the sensing system for the range of pedestrian sizes; the timing of system deployment, and the bonnet deflection due to body loading. Furthermore, the model could be a good tool for further research on pedestrian injury mechanism and the development of pedestrian protection devices.

The graphitic carbon nitride (g-C₃N₄) and the Fe₃O₄/g-C₃N₄ magnetic materials were synthesized in this paper. The structures of the materials were confirmed by a series of analysis. The Fe₃O₄/g-C₃N₄ was then used as a sorbent to adsorb polychlorinated diphenyl ethers and polychlorinated biphenyls. Different extraction conditions were examined, including adsorbent amount, salinity, pH of the sample matrix, adsorption time, reaction temperature, elution solvent and preconcentration factor. The maximum recoveries were obtained by employing methanol to desorb pollutants on 40.0 mg Fe₃O₄/g-C₃N₄ in 120.0 mL environmental water with a salinity of 5% (w/v) at a pH of 7 at 25 °C within 10 min. Using the optimized parameters, the detection limits of the method are between 0.01 and 0.04

Magnetic CoFe2 O4 -embedded porous graphitic carbon nanocomposites were prepared through a facile solid-phase thermal reaction with NaCl as a template. The material was applied in the magnetic solid-phase extraction process coupled with high performance liquid chromatography with a diode array detector to detect the trace fenpropathrin, cyhalothrin, S-fenvalerate, and bifenthrin in different water samples. The synthesis conditions of nanomaterial including glucose concentration and calcination time on extraction performance for pyrethroid pesticides have been investigated. Different magnetic solid-phase extraction parameters have been studied, such as the nanomaterial amount, solution pH, eluent types, adsorption time, and the reusability. Under the optimum conditions, good recoveries (80.2-110.9%) were achieved with relative standard deviations of 0.2-5.8%. There are probably hydrophobic interactions and dipole-dipole attractions between nanocomposites and the analytes.

The high-efficient photocatalytic material Ag3PO4/g-C3N4 was synthesized through calcination and precipitation methods. The physico-chemical properties of the material were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS) photoluminescence spectra (PL) and Brunauer-Emmett-Teller (BET) surface area test. The morphology analysis indicated that Ag3PO4 particles were heterogeneously dispersed on the surface of layered g-C3N4. The Ag3PO4/g-C3N4 nanocomposites were applied in the photodegradation of bisphenol A under the visible light irradiation. The effects of the material proportion, the initial concentration of BPA, and the salinity on the degradation were discussed. The results showed that 92.8% bisphenol A (10 mg/L) can be photodegraded under 3 h irradiation by Ag3PO4/g-C3N4 with 25% Ag3PO4 mass ratio. The photodegradation kinetics and possible photocatalytic mechanism were discussed. The active specie ·O2− was found to play a key role during the photocatalytic reaction. The reaction mechanism was described based on valence band, conduction band energy levels and reduction potentials of oxygen and hydroxyl radicals.

Semiconductor photocatalysis has a great prospect in solving the problems of environmental pollution. Herein, the thickness-dependent BiOIO3 loaded by carbon quantum dots (CQDs/BiOIO3) was first synthesized. The 3 wt% CQDs/BiOIO3 with sheet-like morphology exhibited the highest efficiency of 95.01 % for the photodegradation of bisphenol A after 60 min. The outstanding photocatalytic activity was ascribed to two aspects: the first was the efficient separation of photogenic e−-h+ in thin layered BiOIO3 (50 nm); the second was the acceleration of charge transfer and the extension of light absorption after the CQDs co-catalysis. The h+ and O2− were dominant active species in the degradation process and possible mechanism was deeply studied. The attacked sites of bisphenol A were ascertained by Fukui index and the degradation pathways were proposed through the LC–MS analysis. This work significantly deepens the understanding of layered bismuth-based material and provides ideas for the design of high-performance catalysts.

In this study, the Z-scheme heterojunction photocatalysts Ag/NH2-MIL-125(Ti)/CdS (AMC-5, AMC-10 and AMC-20) were first successfully obtained by stepwise deposition of Ag and CdS. The morphology, crystallinity and photochemical properties of the materials were investigated. The N2 adsorption–desorption isotherm showed that AMC-10 had a large specific surface area (363.41 m2/g). Cyclic tests proved that the heterojunction exhibited good stability. In comparison, AMC-10 exhibited a significantly higher photocatalytic activity. Results suggested that 94.2% ketoprofen (10 mg/L) can be photocatalytically degraded to intermediates and small molecules after 180 min of simulated sunlight illumination. AMC-10 had a large degradation rate constant 0.0168 min−1, which is 3.15 and 2.50 times higher than that of CdS and NH2-MIL-125(Ti), respectively. The total organic carbon removal percentage of ketoprofen was 57.5%. Free radical trapping experiments indicated that ·O2− and h+ were the main active species, which can also be verified by the detection of electron paramagnetic resonance. Possible degradation pathways and reaction mechanisms were proposed by band potential calculations and liquid chromatography-mass spectrometry. The results of Vibrio qinghaiensis sp.-Q67 culture demonstrated that the biotoxicity of ketoprofen increased first and then decreased with time. It can be concluded that the Z-scheme heterojunction of Ag/NH2-MIL-125(Ti)/CdS was beneficial for the separation of photo-generated electrons and holes and the noble metal Ag nanoparticles play the important role in the photocatalytic degradation with the surface plasmonic resonance effect and Schottky junction.

A novel Bi₂MoO

Novel magnetic CoFe2O4-embedded MIL-101(Cr) with tetramethylammonium hydroxide (CoFe2O4/MIL-101T) was prepared through the facile hydrothermal method. Tetramethylammonium hydroxide acts as a template molecule and avoids the recrystallisation of terephthalic acid. The material was applied as the adsorbent in the magnetic solid-phase extraction (MSPE) process coupled with high-performance liquid chromatography to detect the five flame retardants in environmental water samples. Several parameters affecting MSPE efficiency were systematically investigated, such as MIL-101T content, material amount, desorption solvents, adsorption time, solution pH, theoretical maximum enrichment factor (EFmax) and the reusability. Under optimised conditions, good linearities were achieved for five flame retardants with correlation coefficients R2 > 0.9961. The limits of detections for analytes at the signal-to-noise ratio of three were 0.013–0.071 μg·L−1. This method was applied to the analysis of tap, pond, lake and river waters. The recoveries were in the range of 81.5 ± 3.2–107.0 ± 2.3% with the relative standard deviations ranging from 0.11% to 8.66% in four real water samples. The adsorption mechanism was the hydrophobic interaction between the material and the analytes besides pore adsorption action of the material.

Mesoporous KIT-6-magnetite composite (Fe3O4@SiO2@KIT-6) was successfully prepared and characterized by transmission electron microscopy, scan electron microscopy, elemental mapping, energy dispersive X-ray spectrum, Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray powder diffraction, Brunauer Emmett Teller analysis and magnetic property analysis. It was then applied as adsorbent for magnetic solid phase extraction of fenpropathrin, lambda-cyhalothrin, S-fenvalerate and bifenthrin from water samples before analyzed by high performance liquid chromatography-ultraviolet detector. A few factors impacting extraction were studied. The optimal results were acquired by using acetonitrile to eluent the targets adsorbed on 40 mg of Fe3O4@SiO2@KIT-6 adsorbent in 100 mL water samples at a pH of 7 at 25 ℃ within 10 min. The experimental limit of detections of fenpropathrin, cyhalothrin, S-fenvalerate and bifenthrin are 0.01 × 10−3, 0.006 × 10−3, 0.01 × 10−3 and 0.005 × 10−3 mg∙L-1, respectively. Good relative recoveries (86.58–98.80%) and reproducibility values are also obtained. The kinetic experiment shows that the adsorption follows pseudo-second order, while the isotherm experiment follows Langmuir isotherm model. Trace pyrethroid pesticides in water samples can be detected by the developed magnetic solid phase extraction technique followed by high performance liquid chromatography, which is simple, easy, environmental friendly and efficient.

The novel HNO3-modifitied biochar (NBC) was synthesized from walnut shell. The NBC was characterized from scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectrum. The NBC was then used in the adsorption of sulfadiazine, sulfamethazine and sulfachloropyridazine from aqueous solution. The material surface has carbon/oxygen-contained groups, which is benefit for the adsorption. The results showed the adsorption ability of NBC on three sulfonamides were 32, 46, and 40 mg g−1, respectively. The kinetic was found to follow the Elovich model and the isotherm conformed Freundlich. Adsorption was more favorable at weak acidic solution. The interactions mainly include π - π EDA, electrostatic interaction, Lewis acid-base interaction, hydrophobic interaction and H-bond.

In this study, chlorella was first used as the carbon source of Carbon dots (CDs) and further modified the BiOCl. Then, a novel photocatalyst Carbon dots/BiOCl (CBOC) was successfully synthesized. The morphology, crystal structure, chemical states and optical properties of the material were characterized by different techniques. Meanwhile, the energy band structure and density of states of CBOC2 composite were calculated based on density functional theory. In order to investigate the photocatalytic performance of the materials, the photodegradation of tetracycline was carried out under the simulated sunlight. The conditions of different materials, materials dosage and sample concentration were compared. About 99.5% tetracycline (10 mg/L) can be photodegraded by 15 mg CBOC2 in 75 min illumination with 52.2% mineralization rate. The material can be reused with high stability. The ·O2− is the main reactive species. The possible degradation pathways and mechanism of photocatalysis was discussed in detail. The CDs originated from chlorella has the large contribution in the photocatalysis. The work creates a new road of the application of chlorella in photocatalysis.

In order to simulate the injury of rear children occupants in the frontal impact, a previously validated six-year-old child Finite Element (FE) model was used to load ECE R44 testing conditions. Through the resultant head acceleration, pressure, brain tissue Von Mises stress, brain tissue shear stress, shear force and axial force of neck, compression of chest and abdomen to compare the protective effects of the six-year-old rear seat occupant on forward-facing child seat restraint system and booster in different collision speeds. The results indicate that: when the collision speed is low, there is little difference of the child FE model's injury criteria in the two restraint systems, while the protective effect of child seat restraint system to the children is better than booster with the increase of the collision speed.

Carbon-encapsulated Ni nanoparticles (the average diameter of the particles is 7–8 nm) in B matrix were successfully in situ synthesized by chemical vapor deposition (CVD) in order to solve the agglomeration of nanoparticles by traditional mixing method. The influences of CVD technique on the carbon yield, morphology and structure were well investigated based on model system, and the (MgB 2 ) 0.96 Ni 0.04 bulks containing 3.8, 8.2 and 8.5 wt% carbon were prepared at 750 °C. The X-ray diffraction patterns showed no substitution of Ni for Mg and less substitution of C for B during the synthesis process, whereas the TEM analysis suggested such decorated insertions with core-shell structure were stable within the MgB 2 matrix and hopefully acted as pinning center due to the small size. In our experiment, although the advantage of nanoparticles was suppressed by the large amount of MgO impurities during the deposition process, a small enhancement of J c was observed in the low field range, which indicated improved grain connectivity because of the refinement of MgB 2 grains by inducing homogeneous nanoparticles. In view of this, a desirable J c performance at high field could be further obtained under the control of MgO content.

Purpose It is usually difficult to obtain the accurate mechanical properties of pediatric brain and skull because of the absence of pediatric cadaver experiments. The goal of this work is to discuss how different brain mechanical properties influence pediatric head response.

The novel, stable, and environment-friendly Fe 3 O 4 /g-C 3 N 4 nanocomposites (10–15 nm) were synthesized with a combination of calcination and co-precipitation methods. The nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller analysis (BET). The results indicated that the Fe 3 O 4 nanoparticles were uniformly deposited on the g-C 3 N 4 nanosheets. The photocatalytic activity of the Fe 3 O 4 /g-C 3 N 4 nanocomposites was investigated for the first time in terms of the photodegradation of 2,4,6-trichlorophenol (2,4,6-TCP) under visible light. The nanocomposites with 50% g-C 3 N 4 (mass percent) were found to have good photocatalytic activity for the photodegradation of 2,4,6-TCP. In addition, the nanocomposites could be reused several times by applying an external magnetic field to separate them from the solution. The photodegradation kinetics and a possible reaction mechanism were investigated. Hydroxyl radicals were detected during the photodegradation reactions by using fluorescence spectroscopy.

Novel material wool ball-like F-doped BiOCl0.4Br0.3I0.3 has been successfully fabricated via a facile solvothermal method. In this work, the as-synthesized catalyst was characterized to examine the structure, morphology, optical and electrochemical properties. The catalyst was used in sulfamethazine degradation under visible-light irradiation. The optimized photocatalyst F-BiOCl0.4Br0.3I0.3 (Bi:F = 3:2) exhibits superior activity and the degradation efficiency can reach 99.6 % in pH 6 within 60 min. There are two reasons to explain it: (i) The F-BiOCl0.4Br0.3I0.3 has narrow band gap; (ii) Wool ball-like morphology can cause multiple reflections of the irradiated light, and availably prolong the action time. The primary oxidative species are holes and superoxide radicals. The possible degradation mechanism was discussed based on the experimental results.

It is a central issue to improve the separation efficiency of photogenerated charge carriers and the utilization of visible light in the field of photocatalysis. Herein, taking MIL-125(Ti) as a host material, the Pt/MIL-125(Ti) was first prepared by solvothermal method to build the interface of Schottky junction. Ag was then introduced onto the surface of Pt/MIL-125(Ti) to form the interface with the surface plasmon resonance effect. These double interfaces in the composite play a synergistic role on the photodagradation. The morphology, crystallinity and photochemical properties of the material were tested. By comparison, Pt/MIL-125(Ti)/Ag (4 wt% Ag) exhibited the best performance in the photodegradation of ketoprofen (KP, 10 mg/L) and the degradation process conformed to the pseudo-first-order kinetics. The photodegradation rate is 0.0253 min−1, which was higher than MIL-125(Ti) (0.0009 min−1). The TOC removal efficiency of KP reached approximately 51.5%. The electron paramagnetic resonance (EPR) and free radical capture tests verified that h+ and ·OH played the prominent roles during the reaction system. The degradation process, possible pathways and reaction mechanism were proposed. The design of the double interfaces between semiconductor and noble metals is a novel strategy to enhance the photocatalytic performance.

In view of the deterioration of the environment and the shortage of resources, it is necessary to develop efficient photocatalysts for the degradation of organic pollutants. Herein, a novel and environmentally friendly ZnNb2O6/g-C3N4 heterojunction nanocomposite was synthesized by calcination-hydrothermal method successfully. The chemical and physical capabilities of the material were characterized by various kinds of analytical instruments. Compared with ZnNb2O6 and g-C3N4, ZnNb2O6/g-C3N4 showed the strongest photocatalytic activity. The nanomaterial was used in the removal of the pollutant 2,4-DCP. The effects of degradation conditions were discussed including component ratio, material dosage, initial analyte concentration, pH and salinity. After 180 min’ simulated sunlight illumination, the removal efficiency of 2,4-DCP (10 mg/L) reached 95.7% under the optimum condition. Furthermore, the possible photocatalytic mechanisms were discussed according to four aspects: (i) The conformation of the active species; (ii) The calculation of valence and conduction band; (iii) The analysis Z-scheme heterojunction mechanism; (iv) The speculation of feasible photocatalytic paths. In conclusion, the ZnNb2O6/g-C3N4 (ZC-7) nanocomposite has the least recombination rate of electron-hole pairs and the highest photocatalytic efficiency.

A previously developed and validated 6-year-old (6YO) Finite Element (FE) human head model was used to evaluate the biomechanical performance of a new bicycle helmet design for children. The cushion structure of the new helmet design is made of honeycomb paperboard and corrugated paperboard instead of Expanded Polystyrene (EPS) foam. Simulation results showed that the EPS foam helmet can effectively resist external shocks in a short period. However, based on biomechanical responses of the 6YO head model, honeycomb and corrugated paperboard helmets also had a promising cushioning performance. From the drop test of the head-helmet model simulations, the effects of paperboard thickness and material parameters on the helmet protection efficiency were further investigated. It was concluded that the EPS foam helmet can be replaced with honeycomb/corrugated paperboard helmets which are made of more environmental friendly manufacturing materials.

The validated finite element head model(FEHM)of a 3-year-old child,a 6-year-old child and a 50 th percentile adult were used to investigate the effects of head dimension and material parameters of brain tissues on the head rotational responses based on experimental design.Results showed that the effects of head dimension and directions of rotation on the head rotational responses were not significant under the same rotational loading condition,and the same results appeared in the viscoelastic material parameters of brain tissues.However,the head rotational responses were most sensitive to the shear modulus(G)of brain tissues relative to decay constant(β)and bulk modulus(K).Therefore,the selection of material parameters of brain tissues is most important to the accuracy of simulation results,especially in the study of brain injury criterion under the rotational loading conditions.

Magnetic CoFe

Nanoscale zero-valent iron (NZVI) was first assembled on magnetic carbon/Fe

Graphene-doped Fe3O4 nanocomposites were prepared by a solvothermal reaction of an iron source with graphene. The nanocomposites were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, superconducting quantum interference, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This nanomaterial has been used as a magnetic solid-phase extraction sorbent to extract trace brominated flame retardants from environmental waters. Various extraction parameters were optimized including dosage and reusability of the nanocomposites, and pH of sample matrix. The reliability of the magnetic solid-phase extraction protocol based on graphene-doped Fe3O4 nanocomposites was evaluated by investigating the recoveries of 2,4,6-tribromophenol, tetrabromobisphenol A, 4-bromodiphenyl ether, and 4,4'-dibromodiphenyl ether in water samples. Good recoveries (85.0-105.0%) were achieved with the relative standard deviation ranging from 1.1-7.1%. Moreover, it is speculated from characterization and magnetic solid-phase extraction experiment that there is not only π-π stacking but also possible hydrophobic interaction between the graphene-doped Fe3O4 nanocomposites and analytes.

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05-0.1 ng mL(-1) and precision in the range of 1.8-5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0-99.8% were obtained.

Carbon doped Fe3O4 nanoparticles (Fe3O4/C) prepared by a facile hydrothermal reaction of glucose with iron resource have been applied as magnetic solid-phase extraction (MSPE) sorbent, for the first time, to extract trace brominated flame retardants (BFRs) and pentachlorophenol (PCP) from environmental waters. Various MSPE parameters were optimized including amount of Fe3O4/C nanoparticles, pH of sample solution, enrichment factor of analytes and reusability of Fe3O4/C sorbent. The reliability of the MSPE method was evaluated by the recoveries of BFRs and PCP in spiked water samples. Good recoveries (80.0–110.0%) were achieved with the relative standard deviations range from 0.3% to 6.8%. In this paper, the extraction characteristics of Fe3O4/C sorbent were further elucidated. It is found that the adsorption process of Fe3O4/C to analytes predominates the MSPE efficiency. There is hybrid hydrophobic interaction and hydrogen bonding or dipole–dipole attraction between Fe3O4/C and analytes. Notably, the chemical components of carbon layer on the surface of Fe3O4 nanoparticles were identified by X-ray photoelectron spectroscopy and thermogravimetry-mass spectrometry, and in consequence the covalent bonds between Fe3O4 and the coated carbon have been observed. In addition, the straight influence of synthesis condition of Fe3O4/C nanoparticles including glucose concentration and hydrothermal reaction time on extraction performance for BFRs and PCP has been investigated. It is confirmed that the existence of organic carbon containing functional groups over Fe3O4/C sorbent is responsible for the MSPE extraction.

Cobalt doped TiO 2 nanoparticle prepared by ultrasonic-assisted hydrothermal method was used as the photocatalyst in the degradation of chlorophenols (CPs) and bromophenols (BPs). The doping content of cobalt in this catalyst was optimized as 0.5 wt%. The degradation rates of 2,4,6-trichlorophenol (2,4,6-TCP), 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP), 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4,6-tribromophenol (2,4,6-TBP), 2,4-dibromophenol (2,4-DBP), 2,6-dibromophenol (2,6-DBP), 2-bromophenol (2-BP) and 4-bromophenol (4-BP) were estimated based on the quantitative determination of the degradation products. It was found that the degradation of CPs and BPs underwent dehalogenation process with pseudo-first-order kinetics. Moreover, the photodegradation kinetics was compared between CPs and BPs. The degradation rate of BPs was more quickly than CPs due to the difference in bond energy of carbon–halogen, and the degradation rates of BPs and CPs were mainly dependent on the number and the position of substituting halogen atom respectively. In addition, 2,4,6-TCP and 2,4,6-TBP can be effectively degraded by more than 95.1% and 93.5%, respectively, within 240 and 30 min. Tri-substituted phenols were firstly photodegraded to corresponding di-substituted ones, then to mono-substituted ones, and finally to phenol by TiO 2 /Co nano catalyst, although there were some differences in selectivity, rate and yield in the dehalogenation pathway of 2,4,6-TCP and 2,4,6-TBP.

At present, in the feature extraction of non-stationary vibration signals, many timefrequency analytic methods have emerged to meet the further need of non-stationary signal analysis such as Wavelet Transform (WT), Short Time Fourier Transform (STFT), WignerVille Distribution (WVD), Empirical Mode Decomposition (EMD), Ensemble Empirical Mode Decomposition (EEMD) and so on. However, these time-frequency analysis methods can only be carried out on Matlab platform and the processes are of low efficiency, bringing a lot of inconvenience in signal analysis because they can not run on Windows system independently. According to the defects, a novel method of mixed programming which combines Matlab with Delphi based on COM (component Object Model) module technology is proposed to design a time-frequency analysis system for non-stationary vibration signals assembling fourteen methods. The advantages of two languages are shared with each other. In design of the system, a combined method which combines two or three analytic methods is put forward for relational analytic modules to make the analytic results more perfect and clearer, like WAVELET-FFT, EMD-WVD etc.. This paper uses the EMD-WVD combined method as an example to present the programming thoughts and processes. The effectiveness of the system is validated using a simulation signal and an experimental signal. The system can be executed separated from MATLAB environment.

We have developed a facile in-situ growth method for the deposition of magnetite (Fe3O4) particles on the surface of a graphitic carbon nitride (g-C3N4) nanosheet. The material was characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The high affinity of g-C3N4 for phenolic acids in combination with the magnetism of Fe3O4 provides an efficient means for magnetic solid phase extraction. The adsorption, desorption and recoveries were examined. Under optimized conditions, the method has limits of detection in the range from 17.5–42.6 ng mL−1 (at an S/N of 3), and precisions from 2.8–3.8 % (for n = 5). The method was successfully applied to the determination of protocatechuic, caffeic, and ferulic acids in Salicornia herbacea L. plant extracts. Recoveries ranged from 92.4–99.5 %.

The novel semiconductor heterojunction of MIL-53(Fe)/BiOCl composite was first prepared through the solvothermal reaction. The prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunner-Emmet-Teller (BET) and ultraviolet-visible diffuse reflectance spectroscopy (DRS). MIL-53(Fe)/BiOCl heterojunction is a kind of photoexcited materials and it accelerates the photoreactivity of BiOCl under the visible light irradiation. It was used to remove Rhodamine B (RhB) with the existence of persulfate (PS). The UV–vis spectrophotometer and the TOC detector show that the degradation rate and TOC removal efficiency of RhB (20 mg/L) are 99.5% and 69.4%within 30 min visible-light irradiation, respectively. Due to the proper band gap of material and the presence of electron acceptor, PS, the survival time of active radicals are increased. The active species h+, ·SO4− and ·OH are found to play the important roles during the reaction system. The possible mechanism for the RhB degradation of MIL-53(Fe)/BiOCl/PS is also proposed. Furthermore, the results of the material reusability for the degradation of RhB indicate that the MIL-53(Fe)/BiOCl has a good stability and can be used in the environmental water sample treatment.

To test the applicability of Head Injury Criterion (HIC), three different-sized (5th, 50th, 95th percentile) finite element head models were developed from medical CT scan images of living humans. These models were scaled to generate six scaled models. The skulls of these nine models were defined as deformable and rigid bodies, respectively. It was found that both coup and contrecoup pressures decreased from the smaller head to the larger one when the skulls were deformable; while the opposite trends were found when the skulls were defined as rigid bodies. Maximum principal strains and maximum share stresses increased from the smaller head to the larger one for both deformable and rigid skulls with much larger increases in the rigid skull cases. It also found that there were larger discrepancies in intracranial responses between scaled models and the original ones, which invalidate the scaling laws used in biomechanical injury studies.

With its advantages of good torque and speed characteristics, high-speed dynamic response, the brushless DC motor is gradually becoming the first choice for electric vehicles. In order to effectively solve the brushless DC motor control problems caused by the non-linear characteristics, so that this type of motor can be preferably applied in electric vehicles. In this study, according to the nonlinear characteristics of brushless DC motor, the mathematical model is established. Rotating speed and current dual-loop control is selected as the control strategy, The control system is analyzed and simulated, the simulation model of the drive motor is established in the MATLAB/Simulink. And dynamic driving characteristics of the motor are analyzed. The simulation results show that mathematical model is accurate. In this design, no static speed difference can be realized and the motor can be quickly started and broke. The study has great significance in improving the electric vehicle dynamic performance and battery efficiency, as well as increasing the driving range.

The trajectory model of dispersed phase drops and distribution model of drop diameters were derived. By numerical simulation, the analytical results indicate that a large number of dispersed phase drops accumulate on the upper plate in different directions and form a hydrodynamic area with the stream-wise location in the range of 0–0.4 m, where the flow of trickling film obtains kinetic drive from flowing field. The flowing field of trickling film exhibits an unstable state if the stream-wise location is less than 0.02 m, and a stable state otherwise. Moreover, different velocity vectors of drops in the x-y plane result in different interactions between the trickling film and drops. For the non-uniform distribution of drop diameters, there is a stronger interaction between the trickling film and drop if the stream-wise location is less than 0.02 m, because the amplitudes of velocity vectors are higher than those in the range of 0.02–1.0 m. The result reveals a complexity and diversity of stratified two-phase flowing field. On the other hand, both the basic flowing field and distributions of drop diameters have a great influence on the distributions of comparable kinetic energy of drops. The complicated motions of larger drops are helpful to coalescence because they will consume much more kinetic energy on the trickling film than those of smaller drops. The change of comparable kinetic energy of smaller drops is continuous and steady. The smaller drops are easily entrained by the liquid-liquid flowing field.

Selective inhibition of cyclooxygenase-2 (COX-2) might avoid the side effects of current available nonsteroidal antiinflammatory drugs while retaining their therapeutic efficacy. A novel variable selection and modeling method based on prediction is developed to construct the quantitative structure-activity relationships (QSAR) between the molecular electronegativity distance vector (MEDV) based on 13 atomic types and the biological activities of a set of selective cyclooxygenase-2 inhibitory molecules, 3,4-diarylcycloxazolones (DAA) plus indomethacin, naproxen, and celecoxib. Using multiple linear regression, a 5-variable linear model is developed with the calibrated correlation coefficient of 0.9271 and root mean square error of 0.17 in modeling stage and the validated correlation coefficient of 0.9030 and root mean square error of 0.20 in leave-one-out validation step, respectively. To further test the predictive ability of the model, 20 DAA compounds are picked up to construct a training set which is used to build a QSAR model and then the model is employed to predict the biological activities of the balance compounds. The predicted correlation coefficient and root mean square error are 0.9332 and 0.19, respectively.

Protective coating was successfully prepared on SiC p /A356 composites by plasma electrolytic oxidation(PEO) technique. XRD analysis showed that the PEO coating was mainly composed of α-Al 2 O 3 γ-Al 2 O 3 and mullite. The electrochemical corrosion behavior of coated and uncoated SiC p /A356 composites was tested in 3.5 wt.% NaCl solution by potentiodynamic polarization technique with low scanning rates. It was found that the corrosion potential was shifted significantly in the anodic direction and the corrosion current density was much lower due to the presence of the PEO coating. Additionally, the wear behavior of the PEO coating was also tested using a ring-on-ring wear tester. The PEO coating showed a low specific wear of 4.76 × 10 − 6 mm 3 /(N·m) against bearing steel at a speed of 0.52 m/s and a contact pressure of 0.75 MPa.

Brain tissue mechanical properties are of importance to investigate child head injury using finite element (FE) method. However, these properties used in child head FE model normally vary in a large range in published literatures because of the insufficient child cadaver experiments. In this work, a head FE model with detailed anatomical structures is developed from the computed tomography (CT) data of a 6-year-old healthy child head. The effects of brain tissue mechanical properties on traumatic brain response are also analyzed by reconstruction of a head impact on engine hood according to Euro-NCAP testing regulation using FE method. The result showed that the variations of brain tissue mechanical parameters in linear viscoelastic constitutive model had different influences on the intracranial response. Furthermore, the opposite trend was obtained in the predicted shear stress and shear strain of brain tissues caused by the variations of mentioned parameters.