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A modified QuEChERS pretreatment method and LC-MS/MS technique were performed to simultaneously determine four pesticide (Hexachlorophene, Dinex, Dinosam, Dinoterb) residues in agricultural products. Through the optimization of LC-MS/MS detection parameters in SIM mode, the optimal instrument conditions are obtained. The modified QuEChERS method was used to pretreat the samples. Solid phase extractants PSA, C18 and GCB were used for sample purification. The research results showed that the correlation coefficients of the four pesticides were all greater than 0.991, which had a good linear relationship. The limits of quantitation (LOQ) of the four pesticides were 0.05–0.56 μg/kg. The recoveries were 70.51–113.20% with relative standard deviations (RSDS) of 1.6–11.2%. The developed method can provide reliable data support for the subsequent simultaneous detection of these four pesticides. [ABSTRACT FROM AUTHOR]

A novel medium-length fluorinated diols and poly(L-lactide) (PLLA) were synthesized via Michael addition reaction and ring-opening polymerization, respectively. Subsequently, Synthetic medium-length fluorinated diols and PLLA were combined to prepare new polyurethane composites with degradability and low surface energy. The compositional analysis and structural characterization of synthetic materials were characterized by using fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectra (1HNMR). Thermogravimetric analysis(TGA) indicated that the introduction of medium-length fluorinated diols improved the thermal stability of the polyurethane. The biodegradation and low surface energy of the polyurethane were investigated by static hydrolysis experiment and water contact angle test. It was found that the degradation rate of the polyurethane increased as measurement time went on when the PLLA content was under 40%, and the water contact angle increased from 71.12° to 108.24° with the increase of fluorine content, which indicated that the degradable and low surface energy polyurethane has a potential as a coating material for a marine antifouling coating application. [ABSTRACT FROM AUTHOR]

Background:There is lack of further observations on the microstructure and material property of callus during bone defect healing and the relationships between callus properties and the mechanical strength.Methods:Femur bone defect model was created in rabbits and harvested CT data to reconstruct finite element models at 1 and 2 months. Three types of assumed finite element models were compared to study the callus properties, which assumed the material elastic property as heterogeneous (R-model), homogenous (H-model) or did not change from 1 to 2 months (U-model).Results: The apparent elastic moduli increased at 2 months (from 355.58 ± 132.67 to 1139.30 ± 967.43 MPa) in R-models. But there was no significant difference in apparent elastic moduli between R-models (355.58 ± 132.67 and 1139.30 ± 967.43 MPa) and H-models (344.79 ± 138.73 and 1001.52 ± 692.12 MPa) in 1 and 2 months. A significant difference of apparent elastic moduli was found between the R-model (1139.30 ± 967.43 MPa) and U-model group (207.15 ± 64.60 MPa) in 2 months.Conclusions:This study showed that the callus structure stability remodeled overtime to achieve a more effective structure, while the material quality of callus tissue is a very important factor for callus strength. At the meantime, this study showed an evidence that the material heterogeneity maybe not as important as it is in bone fracture model. [ABSTRACT FROM PUBLISHER]