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131.
Xueping Liu Huiwang Wu Yue Zheng Zaisheng Wu Jianhui Jiang Guoli Shen Ruqin Yu 《Electroanalysis》2010,22(2):244-250
A sensitive and specific electrochemical immunosensor was developed with α‐fetoprotein (AFP) as the model analyte by using gold nanoparticle label for enzymatic catalytic amplification. A self‐assembled monolayer membrane of mercaptopropionic acid (MPA) was firstly formed on the electrode surface through gold‐sulfur interaction. Monoclonal mouse anti‐human AFP was covalently immobilized to serve as the capture antibody. In the presence of the target human AFP, gold nanoparticles coated with polyclonal rabbit anti‐human AFP were bound to the electrode via the formation of a sandwiched complex. With the introduction of goat anti‐rabbit IgG conjugated with alkaline phosphatase, the dentritical enzyme complex was formed through selective interaction of the secondary antibodies with the colloidal gold‐based primary antibody at the electrode, thus affording the possibility of signal amplification for AFP detection. Current response arising from the oxidation of enzymatic product was significantly amplified by the dentritical enzyme complex. The current signal was proportional to the concentration of AFP from 1.0 ng mL?1 to 500 ng mL?1 with a detection limit of 0.8 ng mL?1. This system could be extended to detect other target molecules with the corresponding antibody pairs. 相似文献
132.
A simple, rapid and environment‐friendly technique of single‐drop liquid‐phase microextraction has been developed for the determination of sulfonamides in environmental water. Several important parameters including stirring rate, extraction solvent, extraction pH, salinity and extraction time were optimized to maximize the extract efficiency. Extraction solvent 1‐octyl‐3‐methylimidazolium hexafluorophosphate [C8MIM][PF6] ionic liquid showed better extraction efficiency than 1‐butyl‐3‐methylimidazolium hexafluorophosphate [C4MIM][PF6] and 1‐octanol. The optimum experimental conditions were: pH, 4.5; sodium chloride content, 36% w/v; extraction time, 20 min. This method provided low detection limits (0.5–1 ng/mL), good repeatability (the RSD ranging from 4.2 to 9.9%, n=5) and wide linear range (1–1500 ng/mL), with determination coefficients (r2) higher than 0.9989 for all the target compounds. Real sample analysis showed relative recoveries between 63.5 and 115.8% for all the target compounds. 相似文献
133.
Junhai Liu Yong Wan Zhichao Zhou Xueping Tian Wenjuan Han Huaijin Zhang 《Applied physics. B, Lasers and optics》2012,109(2):183-188
Continuous-wave (CW) and passively Q-switching laser performance of the Yb:CNGG and Yb:CLNGG disordered garnet crystals are compared. CW output powers of 6.3 and 7.5?W are generated from the Yb:CNGG and Yb:CLNGG lasers, with slope efficiencies measured to be 63 and 74?%, respectively. In passively Q-switched operation, the average output power reaches 2.0 and 3.1?W, with slope efficiencies of 56 and 65?%, for the Yb:CNGG and Yb:CLNGG lasers, respectively. Laser pulses of 9.5?ns in duration are generated with the two Yb lasers, with the highest pulse energy and peak power amounting to 166.7???J and 17.5?kW for the Yb:CNGG laser, and 133.0???J and 14.0?kW for the Yb:CLNGG laser. In respects of efficient laser operation and power scaling, the Yb:CLNGG proves to be advantageous over Yb:CNGG, whereas the Yb:CNGG is superior to Yb:CLNGG in energy storage capacity. 相似文献
134.
Xueping Huang 《Journal of Mathematical Analysis and Applications》2012,393(2):377-388
We study the uniqueness class problem for a class of heat equations defined on weighted graphs. As an application, we recover the volume growth criterion for stochastic completeness of Grigor’yan, Huang and Masamune in the case of weighted graphs. 相似文献
135.
Zhu H Zheng Z Gao X Huang Y Yan Z Zou J Yin H Zou Q Kable SH Zhao J Xi Y Martens WN Frost RL 《Journal of the American Chemical Society》2006,128(7):2373-2384
Niobium pentoxide reacts actively with concentrate NaOH solution under hydrothermal conditions at as low as 120 degrees C. The reaction ruptures the corner-sharing of NbO(7) decahedra and NbO(6) octahedra in the reactant Nb(2)O(5), yielding various niobates, and the structure and composition of the niobates depend on the reaction temperature and time. The morphological evolution of the solid products in the reaction at 180 degrees C is monitored via SEM: the fine Nb(2)O(5) powder aggregates first to irregular bars, and then niobate fibers with an aspect ratio of hundreds form. The fibers are microporous molecular sieve with a monoclinic lattice, Na(2)Nb(2)O(6).(2)/(3)H(2)O. The fibers are a metastable intermediate of this reaction, and they completely convert to the final product NaNbO(3) cubes in the prolonged reaction of 1 h. This study demonstrates that by carefully optimizing the reaction condition, we can selectively fabricate niobate structures of high purity, including the delicate microporous fibers, through a direct reaction between concentrated NaOH solution and Nb(2)O(5). This synthesis route is simple and suitable for the large-scale production of the fibers. The reaction first yields poorly crystallized niobates consisting of edge-sharing NbO(6) octahedra, and then the microporous fibers crystallize and grow by assembling NbO(6) octahedra or clusters of NbO(6) octahedra and NaO(6) units. Thus, the selection of the fibril or cubic product is achieved by control of reaction kinetics. Finally, niobates with different structures exhibit remarkable differences in light absorption and photoluminescence properties. Therefore, this study is of importance for developing new functional materials by the wet-chemistry process. 相似文献
136.
Eu2+-activated strontium–barium silicate, SrBaSiO4:Eu2+, which is an intermediate phase between Sr2SiO4 and Ba2SiO4, was synthesized by a solid-state reaction. The synthesized phosphor was efficiently excited by a broad spectral range of near UV between 300 and 450 nm, and exhibited a strong and wide green emission. As the doped Eu2+ concentration increased from 0.005 to 0.18 (molar ratio), the emission wavelength shifted from 509 to 521 nm, and this red-shift phenomenon was discussed through a band-gap model. The concentration quenching mechanism was calculated to be a dipole–quadrupole interaction. It showed good thermal stability with T1/2 of 170 °C and high internal quantum efficiency (78%). A green LED was fabricated with SrBaSiO4:Eu2+and a 395 nm-emitting InGaN chip and it showed a superior current tolerant property. All the results indicate that this phosphor is a good candidate as green component in fabrication of phosphor-converted white LEDs. 相似文献
137.
Lijun Zhao Hua Yang Shuiming Li Lianxiang Yu Yuming Cui Xueping Zhao Shouhua Feng 《Journal of magnetism and magnetic materials》2006
Composites of α-Fe/Fe3O4 having dimensions in the range of 100–150 nm have been prepared by disproportion method. The structure and morphology are investigated by XRD and TEM. XRD shows that the metal has got the BCC structure. TEM shows balls of metallic iron about 100-nm-wide stuck to magnetite grains. Magnetic measurement shows that the sample aged for 3 h and calcined at 200 °C has the maximal saturation magnetization corresponding to the highest concentration of α-Fe in the final sample. 相似文献
138.
139.
Qiong Ma Xiaolan Liu Yingying Zhang Ling Chen Xueping Dang Youhong Ai Huaixia Chen 《Journal of separation science》2020,43(8):1514-1522
In this study, porous sandwich structure Fe3O4 nanoparticles coated by polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe3O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high‐performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2–400 μg/kg for carbaryl and carbofuran (R2 = 0.9995), respectively. The limits of detection were 0.5 μg/kg of carbaryl and 0.7 μg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high‐performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts. 相似文献
140.
Xueping Jia Weiping Qian Dajian Wu Dongwei Wei Guilan Xu Xiaojun Liu 《Colloids and surfaces. B, Biointerfaces》2009,68(2):231-237
Biologically derived materials provide a rich variety of approaches toward new functional materials because of their fascinating structures and environment-friendly features, which is currently a topic of research interest. In this paper, we show that the cuttlebone-derived organic matrix (CDOM) is an excellent scaffold for the one-step synthesis and assembly of silver nanoparticles (AgNPs), which can be further used as substrate for surface-enhanced Raman scattering (SERS). Formation of AgNPs–CDOM composite was accomplished by the reaction of CDOM with AgNO3 and NH3·H2O solution at 80 °C without using any other stabilizer and reducing agents. UV–vis spectra and TEM were utilized to characterize the AgNPs and investigate their formation process. Results demonstrate that the size and distribution of AgNPs can be partly regulated by changing incubation time; the concentration of NH3·H2O is critical to the formation rate of AgNPs. As a proof of principle, we show that the AgNPs–CDOM composite can be employed in trace analysis using SERS. 相似文献