[Determination of acetochlor and its metabolites in urine using liquid chromatography-tandem mass spectrometry].

Objective: A method for the determination of acetochlor and its metabolites in urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established. Methods: After cleaned-up by a HLB extraction cartridges, the urine was eluted with 1% acetic acid acetonitrile solution. The target compounds were separated by ACQUITY UPLC®HSS T3 Column (2.1 mm×100 mm×1.8 µm) by using 1% formic acid solution and acetonitrile as mobile phase with gradient elution program, and analyzed in positive electrospray ionization mode by liquid chromatography tandem mass spectrometry. Results: All the target compounds showed good linear relationships in the range of 1-50 µg/L, and the correlation coefficients (r) were higher than 0.997. The recoveries rates at three different spiked levels for all target compounds in blank matrices were 107.6%-129.1%, and the relative standard deviations (RSD) were 1.5%-9.9% (n=6) . The limits of detection and quantitation of the method were 0.04-0.11 µg/L and 0.15-0.42 µg/L, respectively, and target substances were detected in all urine samples from occupational exposure workers to acetochlor. Conclusion: This method is suitable for rapid screening and analysis of acetochlor and metabolites in urine with the advantages of accuracy, rapidity, simplicity, high sensitivity and good specificity.

In situ electron holography study of charge distribution in high-κ charge-trapping memory.

Charge-trapping memory with high-κ insulator films is a candidate for future memory devices. Many efforts with different indirect methods have been made to confirm the trapping position of the charges, but the reported results in the literatures are contrary, from the bottom to the top of the trapping layers. Here we characterize the local charge distribution in the high-κ dielectric stacks under different bias with in situ electron holography. The retrieved phase change induced by external bias strength is visualized with high spatial resolution and the negative charges aggregated on the interface between Al2O3 block layer and HfO2 trapping layer are confirmed. Moreover, the positive charges are discovered near the interface between HfO2 and SiO2 films, which may have an impact on the performance of the charge-trapping memory but were neglected in previous models and theory.

[Comparison of topical therapeutic effect between silver norfloxacin (Ag-NFL) and silver sulfadiazine (Ag-SD) in treatment of pyocyaneous sepsis in burn rats].

The purpose of the study was to carry out a further investigation of the efficacy of topical antimicrobial treatment of Ag-NFL in comparison with that of the most commonly used topical agent Ag-SD. An experimental model of rats with 20% TBSA full thickness burns seeded with 109 CFU of Pseudomonas aeruginosa ATCC-27853 was used. At 24, 48 and 72h after the seeding bacteriologic examination showed that the subeschar bacterial counts exceeded 10(6) CFU per gram of tissue. Subeschar bacterial counts were zero in the group in which Ag-NFL was used, while those in the group using Ag-SD were almost the same as the control. The amount of silver accumulated in the eschar of Ag-NFL, treated rats was significantly higher than that of Ag-SD treated rats. In conclusion, Ag-NFL was proved valuable in the treatment of burn wound infection caused by invading organisms, particularly by the Ag-SD resistant strain of Pseudomonas.