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111.
This work aims at the development of a fast scanning method for organic pollutants with low-cost small Raman spectrometers. A gold nanoparticles-embedded alginate gel is prepared and applied as the substrate for surface enhanced Raman spectrometric detection of polycyclic aromatic hydrocarbons (PAHs). The target molecules are captured by the three-dimensional network of the alginate gel, and brought close to the hot spots generated by gold nanoparticles embedded in the gel. Significant Raman enhancement effects are observed in the analysis of four typical PAH compounds including pyrene, anthracene, fluorene and benzo(a)pyrene. Quantitative analysis of BaP shows a limit of detection of 0.365 nM using a low-cost small Raman spectrometer, which is comparable to published values. The practicability of the method is tested by analyzing PAHs in different water samples, offering a fast scanning method for PAHs. 相似文献
112.
The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ‐fluoro‐γ‐nitro‐esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, affording the desired adducts in acceptable to good yields. 相似文献
113.
Simple and sensitive colorimetric detection of cysteine based on ssDNA-stabilized gold nanoparticles
Zhang Chen Shenglian Luo Chengbin Liu Qingyun Cai 《Analytical and bioanalytical chemistry》2009,395(2):489-494
In this paper, we demonstrate a simple and sensitive colorimetric detection of cysteine based on the cysteine-mediated color
change of ssDNA-stabilized gold nanoparticles (AuNPs). Cysteine is capable of absorbing onto AuNPs surfaces via the strong
interaction between its thiol group and gold. ssDNA molecules which stabilize AuNPs against salt-induced aggregation are removed
away by cysteine encapsulation on the AuNPs surfaces, resulting in a characteristic color change of AuNPs from red to blue
as soon as salt is added. The ratio of absorptions at 640 to 525 nm (A
640/A
525) is linear dependent on the cysteine concentration in the range from 0.1 to 5 μM. Furthermore, amino acids other than cysteine
cannot mediate the color change under the identical conditions due to the absence of thiol groups, suggesting the selectivity
of the proposed method toward cysteine. The employment of complicated protocols and sophisticated processes such as the preparation
of modified AuNPs are successfully avoided in design to realize the simple and low-cost cysteine detection; and the high sensitivity
and low cost of the method is favorable for practical applications.
Figure In the presence of cysteine, cysteine binds to the AuNPs surface via Au-S bond, spontaneously driving ssDNA molecules away
from the nanoparticles, which leads to the AuNPs aggregation under the condition of NaCl introduction, and the corresponding
color change from red to blue. However, the presence of other amino acids results in no color change due to the absence of
thiol groups.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
114.
Liu Q Bian Y Liu H Wang X Chen Y Li X Jiang J 《Journal of colloid and interface science》2006,304(2):431-436
Regular square, wirelike, quadrate, and rodlike nanocrystal arrays of Cd2+, Hg2+, or Ag+ metal-cation-mediated sandwich-type mixed (phthalocyaninato) [5,10,15,20-tetrakis(4-pyridyl)poprhyrinato] cerium(III) double-decker complex Ce(Pc)(TPyP) have been successfully prepared at the water-chloroform interface. The nanocrystal growth processes were monitored by transmission electron microscopy (TEM), which reveals that different morphologies of nanocrystals have been fabricated from double-decker molecules connected by different kinds of metal cations, forming coordination polymers. These nanoscaled coordination polymers were characterized by FT-IR spectra and energy-dispersive X-ray spectra (EDS). EDS results clearly revealed the elements of the nanocrystals and the FT-IR spectra give evidence for the coordination interaction between the double-decker molecules and metal cations. The UV-vis absorption spectrum indicates the formation of J-aggregates of the double-decker molecules in the nanocrystals formed. 相似文献
115.
The Metal–Metal‐to‐Ligand Charge Transfer Excited State and Supramolecular Polymerization of Luminescent Pincer PdII–Isocyanide Complexes 下载免费PDF全文
Qingyun Wan Dr. Wai‐Pong To Dr. Chen Yang Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2018,57(12):3089-3093
Pincer PdII–isocyanide complexes are described that display intermolecular interactions and emissive 3MMLCT excited states in aggregation state(s) at room temperature. The intermolecular PdII?PdII and ligand–ligand interactions drive these complexes to undergo supramolecular polymerization in a living manner. Comprehensive spectroscopic studies reveal a pathway with a kinetic trap that can be modulated by changing the counteranion and metal atom. The PdII supramolecular assemblies comprise two different aggregation forms with only one to be emissive. DFT/TDDFT calculations lend support to the MMLCT absorption and emission of these pincer PdII–isocyanide aggregates. 相似文献
116.
Chang Q Yan L Chen M He H Qu J 《Langmuir : the ACS journal of surfaces and colloids》2007,23(22):11197-11199
The bactericidal process of Ag/Al2O3 to Escherichia coli has been investigated to clarify the bactericidal mechanism. In SEM images, the configuration of E. coli cells contacting with the catalyst surface was quite different from that contacting with AgNO3 solution, which indicated that the Ag+ eluted from the catalyst did not play an important role in the bactericidal process. The bactericidal experiments strongly confirmed the contribution of multiform reactive oxygen species (ROS) (super oxide dismutase (SOD) and catalase as the scavengers for O2*- and H2O2, respectively) to bactericidal effect on the catalyst surface. Furthermore, the surface modification of Ag/Al2O3 by ultraviolet and formaldehyde influenced the bactericidal effect obviously, which not only confirmed the bactericidal mechanism of catalytic oxidation but also provided evidence for the synergistic effect between Ag and Al2O3 on the catalyst surface. 相似文献
117.
ω-取代全氟烷基氯化物R(CF_2)_nCl(1a~f)与LiAlH_4反应,得到氯被还原为氢的产物R(CF_2)_nH(2a~f),产率甚好。可是1f与LiAlH_4在四氢呋喃中反应,由于苯乙烯的存在而受到抑制。此外还进行了多氟烷基铜与苄基溴、烯丙溴和β-溴代苯乙烯的反应,得到相应的交叉偶合产物(7,8,9)。 相似文献
118.
Nonlinear Dynamics - Gamma oscillations (30–90 Hz) in the brain are known to have an evident relationship with many cognitive processes. Computational models are promising tools for... 相似文献
119.
Yingying Wang Qingyun Chang Xin Zhou Xiaohuan Zang Chun Wang 《International journal of environmental analytical chemistry》2013,93(14):1563-1573
A simple and efficient liquid phase microextraction based on solidification of floating organic drop coupled with gas chromatography–flame photometric detection was developed for the extraction and determination of some triazine herbicides (metribuzin, simetryn, ametryn and prometryn) in soil samples. The type and volume of the extraction solvent, sample solution temperature, salt addition, stirring rate, and the extraction time were optimized. Under the optimal conditions, the linear response was observed over the range of 10–2000?µg?kg?1 for metribuzin and 2–500?µg?kg?1 for simetryn, ametryn, and prometryn, respectively, with the correlation coefficients (r) varying from 0.9990 to 0.9992. The limits of detection were in the range between 0.2 and 1.0?µg?kg?1 (S/N?=?3?:?1). The recoveries of the target analytes for the spiked soil samples ranged from 75.5% to 97.3%, with the relative standard deviation values less than 7.2% (n?=?5). The enrichment factors were achieved ranging from 122 to 336. The developed method was applied for the preconcentration and determination of triazine herbicides in real soil samples and a satisfactory result was obtained. 相似文献
120.
Qingyun Chang Mengting Wang Guijiang Zhang Xiaohuan Zang Hongda Li Shuaihua Zhang Chun Wang Zhi Wang 《Journal of separation science》2020,43(13):2594-2601
A solid‐phase microextraction with carbon nanospheres coated fiber coupled with gas chromatographic detection was established for the determination of eight polycyclic aromatic hydrocarbons (naphthalene, biphenyl, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene, and pyrene) in water and soil samples. The experimental parameters (extraction temperature, extraction time, stirring rate, headspace volume, salt content, and desorption temperature) which affect the extraction efficiency were studied. Under the optimized conditions, good linearity between the peak areas and the concentrations of the analytes was achieved in the concentration range of 0.5‐300 ng/mL for water samples, and in the concentration range of 6.0‐2700 ng/g for soil samples. The detection limits for the analytes were in the range of 0.12‐0.45 ng/mL for water samples, and in the range of 1.53‐2.70 ng/g for soil samples. The method recoveries of the polycyclic aromatic hydrocarbons for spiked water samples were 80.10‐120.1% with relative standard deviations less than 13.9%. The method recoveries of the analytes for spiked soil samples were 80.40‐119.6% with relative standard deviations less than 14.4%. The fiber was reused over 100 times without a significant loss of extraction efficiency. 相似文献