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This study developed a method to perform the simultaneous determination of 58 (ultra) trace human and veterinary drugs in river water. The analytes included 24 steroid hormones, 22 sulfonamides and 12 quinolones. The easy-to-handle magnetic dispersive solid-phase extraction (Mag-dSPE) procedure was performed using three-dimensional interconnected magnetic chemically modified graphene oxide (3D-Mag-CMGO) as the adsorbent, and an enrichment factor of 100 times was obtained. Under the optimal conditions, the results showed higher extraction capacity of 3D-Mag-CMGO with recoveries between 78.0 and 109%. The limits of quantification (LOQs) for 58 (ultra) trace analytes are in the range of 0.10–2.09 ng L−1. Validation results on linearity, specificity, accuracy, and precision, as well as the application to the analysis of 58 (ultra) trace analytes in ten real samples demonstrated the applicability to environment monitoring analysis.

A new facile, rapid, inexpensive, and sensitive method for the analysis of six trace trichlorophenols in seawater samples was developed by magnetic micro-solid-phase extraction coupled to liquid chromatography with tandem mass spectrometry. Core-shell covalently functionalized ferroferric oxide coated with aminated silicon dioxide and decorated with multiwalled carbon nanotubes was applied as an adsorbent to perform the extraction process. The effect of factors including solution pH, contact time, adsorbent amount, and ionic strength were investigated in detail. The obtained results revealed that the proposed adsorbent was a highly effective and low-cost magnetic micro-solid-phase extraction material for the enrichment of 2,3,4-trichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 3,4,5-trichlorophenol from seawater. Under the optimized conditions, the recoveries ranged from 88.0 to 99.5% at the three spiking levels, the limits of detection and the limits of quantification were 0.002 and 0.007 μg/L for the six trichlorophenols, respectively. The intra- and interday relative standard deviations were 2.0-6.7 and 4.5-8.9%, respectively. The calibration curves showed a good linearity in the range of 0.02-5.0 μg/L. The routine run analyses showed that the developed method was fast, simple, accurate, solvent-saving and high resolution, and it was suitable for the determination of trace trichlorophenols in seawater.

Correction for ‘Surface core–shell magnetic polymer modified graphene oxide-based material for 2,4,6-trichlorophenol removal’ by Mei-Lan Chen et al., RSC Adv., 2014, 4, 63494–63501.

An ionic liquid-based ultrasonic-assisted dispersive liquid–liquid microextraction (IL-USA-DLLME) method was proposed for highly effective extraction of trace bromadiolone and brodifacoum in environmental water samples. The ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate [C6mim][PF6] was quickly disrupted by ultrasonication and dispersed in water as fine droplets. At this stage, the analytes were extracted into the fine ionic liquid droplets. After centrifugation, the concentration of the enriched rodenticides in the sedimented phase was determined. Extraction conditions including extraction solvent, dispersive solvent volume, pH, ultrasonic time and centrifugation time were investigated thoroughly. Compared with the conventional solvent extraction, the proposed approach exhibited higher efficiency, which indicated the IL-USA-DLLME method was an efficient, rapid and simple sample preparation technique. Under optimized extraction conditions, the enrichment factors were up to 122–137 times, achieving the limits of quantitation, which based on the signal-to-noise ratio (S/N) of 10 were 0.005 μg L−1 for both. The linearities for both analytes were in the range of 0.005–1.0 μg L−1 with a correlation coefficient >0.999, and the recoveries were between 88.8–98.3% with relative standard deviations (RSDs) between 1.1% and 9.3%. The proposed method shows high reproducibility, and it is suitable for analysis of trace bromadiolone and brodifacoum in environmental water samples.

A novel well-designed graphene oxide-based magnetic polymer (GO-Fe3O4@P) has been successfully synthesized via distillation–precipitation polymerization, ring-opening and amidation reactions. The as-prepared GO-Fe3O4@P was further characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), BET analysis, zeta potential analysis, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) and the characterization results revealed that core–shell structural Fe3O4@P microspheres were covalently bonded onto the GO sheet. The adsorption characteristics of the GO-Fe3O4@P intended for removal of 2,4,6-trichlorophenol (2,4,6-TCP) were investigated. Batch adsorption studies were carried out to optimize adsorption conditions. The effect of solution pH, adsorption isotherm, kinetics, and thermodynamics was deeply investigated. The results indicated that the adsorption property of GO-Fe3O4@P was highly pH dependent and the adsorption mechanism referred to hydrogen bond and π–π stacking interactions. The adsorption data for 2,4,6-TCP onto GO-Fe3O4@P was well fitted to a Langmuir isotherm. The maximum adsorption capacity (qm) of GO-Fe3O4@P to 2,4,6-TCP was found to be 232.6 mg g−1. Kinetic results showed that the adsorption reached equilibrium within 4 min, 10 min, and 60 min for initial 2,4,6-TCP concentrations of 10 mg L−1, 100 mg L−1, and 500 mg L−1, respectively. The data of adsorption kinetics obeyed the pseudo-second-order rate model well. Thermodynamic parameters such as ΔHθ, ΔSθ, and ΔGθ for the 2,4,6-TCP adsorption onto GO-Fe3O4@P have been estimated, suggesting the adsorption process was endothermic and entropy favored in nature.

The optimization design of gear transmission based on MATLAB is studied for the purpose of finding a convenient and practical method. A mathematical model of optimization design is established in order to minimize the volume of gear transmission, the sequential quadratic programming method (SQP) is used to solve the nonlinear constrained optimization problems. The method how to solve gear parameter optimization base on optimization toolbox of MATLAB is introduced in detail. An optimization design example is given, the optimization result accords with the standard specifications of mechanical design and can be directly used. The result shows that this method is convenient and effective, and can simplify computer programming, is especially suitable for engineer.

The inertia vibrating screen mechanism is taken as an example for the purpose of finding out the kinetic characteristic conveniently, the solution of mechanism kinetic simulation based on SimMechanics is studied, the simulation physical model is given, and the simulation is carried out after the setting of all simulation parameters. Compared with the others simulation solutions, its most prominent feature of SimMechanics is that it needn’t establish the mechanism kinematical mathematical model and program, it has the advantage of convenient and the visual modeling function, also has the powerful simulation function. it is a powerful and convenient tool in mechanical system’s analysis and simulation.

A numerical investigation is presented of the structure of a displacement ventilation convection by using the Reynolds averaged Navier-Stokes equation and K-ε turbulence model. Numerical results are reported for the effect of Gr/Re2 on structure of indoor air convection and ventilation efficiency. The results show that the structure of indoor air convection changes from mechanical ventilation to natural ventilation, and the curves of ventilation efficiency are like “M” with Gr/Re2 increasing.

A new facile, rapid, inexpensive, and sensitive method for the analysis of six trace trichlorophenols in seawater samples was developed by magnetic micro-solid-phase extraction coupled to liquid chromatography with tandem mass spectrometry. Core-shell covalently functionalized ferroferric oxide coated with aminated silicon dioxide and decorated with multiwalled carbon nanotubes was applied as an adsorbent to perform the extraction process. The effect of factors including solution pH, contact time, adsorbent amount, and ionic strength were investigated in detail. The obtained results revealed that the proposed adsorbent was a highly effective and low-cost magnetic micro-solid-phase extraction material for the enrichment of 2,3,4-trichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 3,4,5-trichlorophenol from seawater. Under the optimized conditions, the recoveries ranged from 88.0 to 99.5% at the three spiking levels, the limits of detection and the limits of quantification were 0.002 and 0.007 μg/L for the six trichlorophenols, respectively. The intra- and interday relative standard deviations were 2.0-6.7 and 4.5-8.9%, respectively. The calibration curves showed a good linearity in the range of 0.02-5.0 μg/L. The routine run analyses showed that the developed method was fast, simple, accurate, solvent-saving and high resolution, and it was suitable for the determination of trace trichlorophenols in seawater.

Geometrical optimization and electrostatic potential calculations have been performed at the HF/6-31G level of theory for investigated persistent organic pollutants (POPs). A number of statistically based parameters have been obtained. Relationship between soot-water partition coefficients (logK(SC)) of POPs and the structural descriptors has been established by the multiple linear regression method. The result shows that the quantities derived from electrostatic potential V(s)(-)¯ and V(s,max), together with molecular surface area (A(S)) and the energy of the highest occupied molecular orbital (E(HOMO)) can be well used to express the quantitative relationship between structure and logK(SC) (QSPR) of POPs. Predictive capability of the model has been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient of 0.9797. Furthermore, the predictive power of this model was further examined for the external test set with the correlation coefficient of 0.9811 between observed and predicted logK(SC), validating the robustness and good predictive ability of our model. Furthermore, in order to further investigate the applicability of these parameters derived from electrostatic potential in prediction of soot-water partition coefficient for organic pollutants, eleven polycyclic aromatic hydrocarbons (PAHs), eleven polychlorinated biphenyls (PCBs) and nine phenyl urea herbicides (PUHs) from other source have also been studied. The QSPR models established may provide a new powerful method for predicting soot-water partition coefficients (logK(SC)) of organic pollutants.