Determination of Sulfonylurea Herbicides in Pears Using Hollow Fiber-Protected Magnetized Solvent-Bar Liquid-Phase Microextraction HPLC

Hollow fiber-protected magnetized solvent-bar liquid-phase microextraction of sulfonylurea herbicides, including nicosulfuron, bensulfuron-methyl, pyrazosulfuron and chlorimuron-ethyl, in pears was developed. The analytes were determined by high-performance liquid chromatography. This present method has the advantages of stir bar sorptive extraction and hollow fiber-protected solvent-bar microextraction, that permits active magnetic stirring, extraction and preenrichment in a single device simultaneously. The magnetized solvent-bar was easily retrieved after extraction with a magnet, so the extract is conveniently collected. Experimental parameters, including type of extraction solvent, the number of magnetized solvent-bars, extraction temperature and time, stirring speed, pH of the sample solution, and the salting-out effect, were investigated and optimized. Under optimal experimental conditions, the calibration curve showed good linearity (r ≥ 0.9998). The limits of detection and quantification were in the range of 7.15–8.26 ng/g and 24.99–27.52 ng/g, respectively. The recoveries were in the range of 80.08–105.56 %, and the relative standard deviations were lower than 6.82 %. The results showed that the present method was a satisfactory method for the determination of sulfonylurea herbicides in pears.     

Thermal study of NaP zeolite with different morphologies

NaP zeolites samples with different morphologies were successfully synthesized and their thermal behaviors were fully characterized by in situ HT-XRD, IR spectrum, and TG-DSC techniques. It was found that the cubic zeolite NaP phase underwent the same phase transitions, despite their different morphologies. During the whole heating process, they first underwent a minor phase transition into the tetragonal phase at 200 °C. Then they were gradually converted into the phillipsite phase between 400 and 700 °C. Finally, a very stable NaAlSiO₄ nepheline phase formed when the calcination temperature reached 800 °C, which would be kept even after the sample was cooled to room temperature. Although samples with different morphologies had similar phase transitions, they did have different thermal stability as proved by the TG-DSC study.     

《催化学报》以本期专刊的出版庆祝闵恩泽院士九十华诞

<正>闵恩泽先生1924年2月出生于四川省成都市,1946年毕业于国立中央大学化工系,获得学士学位,1951年毕业于美国俄亥俄州立大学化工系,获得博士学位,1955年回国到石油化工科学研究院工作.五十多年来,闵先生一直致力于石油炼制与石油化工科学技术的研究.他长期在炼油催化剂领域广泛而深入的研究,奠定了     

Magnetic nanocomposite thin films of BaFe12O19 and TiO2 prepared by sol-gel method

The composite films with different weight ratio of barium ferrite to titanium dioxide are successfully prepared using sol-gel method for the first time. The morphology, crystal structure and magnetic properties of composite films are investigated with atomic force microscopy, X-ray diffraction and vibrating sample magnetometry. The results show that the composite films are uniform with no microcracks. The grain diameters are less than 100 nm. With the increase of barium ferrite, the grain diameter decreases. The composite films are composed of M-type hexagonal barium ferrite and rutile titanium dioxide. The composite films possess the excellent magnetic properties. The specific saturation magnetization and coercivity reach 18.3 emu/g and 3350 Oe, respectively. The application of composite films in magnetic recording and electromagnetic absorption fields is promising.     

Inhibitory effect and possible mechanism of action of patchouli alcohol against influenza A (H2N2) virus

In the present study, the anti-influenza A (H2N2) virus activity of patchouli alcohol was studied in vitro, in vivo and in silico. The CC?? of patchouli alcohol was above 20 μM. Patchouli alcohol could inhibit influenza virus with an IC?? of 4.03 ± 0.23 μM. MTT assay showed that the inhibition by patchouli alcohol appears strongly after penetration of the virus into the cell. In the influenza mouse model, patchouli alcohol showed obvious protection against the viral infection at a dose of 5 mg/kg/day. Flexible docking and molecular dynamic simulations indicated that patchouli alcohol was bound to the neuraminidase protein of influenza virus, with an interaction energy of -40.38 kcal mol?1. The invariant key active-site residues Asp151, Arg152, Glu119, Glu276 and Tyr406 played important roles during the binding process. Based on spatial and energetic criteria, patchouli alcohol interfered with the NA functions. Results presented here suggest that patchouli alcohol possesses anti-influenza A (H2N2) virus properties, and therefore is a potential source of anti-influenza agents for the pharmaceutical industry.     

Ti-MWW催化氯丙烯环氧化反应动力学行为

以Ti-MWW分子筛为催化剂,以H2O2为氧化剂,系统研究了氯丙烯环氧化反应的动力学行为.结果表明,该反应速率与Ti-MWW分子筛的用量成正比,是1级反应.当H2O2浓度小于0.67 mol/L时,环氧化反应为1级反应;大于2 mol/L时,为0级反应.随着氯丙烯浓度的增加,环氧化反应级数从1级向0级转变;且只有当其浓...     

Spectroscopic Study on the Interaction of Pyronine Y with Nucleic Acids and Its Analytical Application

ABSTRACT

The interaction of pyronine Y (PY) with nucleic acids was studied by resonance Rayleigh scattering (RRS) for nucleic acid detection. The enhanced RRS intensity of nucleic acids reacted with PY was proportional to the concentration of nucleic acids in the ranges of 27.0–625 ng ml^?1 for fish sperm DNA, 39.0–500 ng ml^?1 for calf thymus DNA, and 59.0–375 ng ml^?1 for yeast RNA. The limits of determination were 0.2 ng ml^?1 for fish sperm DNA, 0.6 ng ml^?1 for calf thymus DNA, and 0.7 ng ml^?1 for yeast RNA. The method had been successfully applied to the quick determination of nucleic acids in synthetic and natural samples.     

An adaptive fuzzy sliding mode controller for MEMS triaxial gyroscope with angular velocity estimation

In this paper, an adaptive fuzzy sliding mode control (AFSMC) for Micro-Electro-Mechanical Systems (MEMS) triaxial gyroscope is proposed. First, a novel adaptive identification approach with sliding mode controller which can identify angular velocity and other system parameters is developed. And in order to reduce the chattering, an AFSMC is designed to approximate the upper bound of the uncertainties and external disturbances. Based on Lyapunov methods, these adaptive laws can guarantee that the system is asymptotically stable. Numerical simulations are investigated to verify the effectiveness of the proposed AFSMC scheme.     

氧化铝对Pt-SO2-4/ZrO2-Al2O3固体酸催化剂结构与酸性的影响

 通过混捏法制备了Pt-SO2-4/ZrO2-Al2O3固体酸催化剂,考察了该催化剂在正构烷烃低温异构化反应中的催化稳定性. 采用X射线衍射、差热分析、X射线光电子能谱、核磁共振、N2吸附-脱附和微量热等表征技术,对氧化铝的作用机理进行了研究. 结果表明,氧化铝起到结构助催化剂作用,对四方相氧化锆具有稳定作用,并延迟了氧化锆的晶化,抑制了氧化锆的烧结,从而增大了催化剂的比表面积和孔容. XPS结果表明, Zr 3d峰向低结合能方向移动, Al 2p峰向高结合能方向移动,说明Al3+的电子向Zr4+偏移. 微量热结果表明氧化铝的引入提高了催化剂的酸量和酸强度. 27Al固体核磁共振结果表明, Pt-SO2-4/ZrO2-Al2O3中的六配位铝的结构发生了变化. 氧化铝的引入还可能有助于氧化锆晶格缺陷的形成,焙烧过程中Al3+迁移进入氧化锆晶格并同晶取代Zr4+形成氧缺陷位,这些氧缺陷位在 S=O 键诱导下显示强酸性.