Facile Process for Preparation of PS/PtOEP Composite Microspheres and their Oxygen Sensing Properties

2014 ◽  
Vol 1004-1005 ◽  
pp. 307-310
Author(s):  
Song Li ◽  
Ke Zhang ◽  
Su E Hao
Keyword(s):  
Fluorescence Intensity ◽  
Dispersion Polymerization ◽  
Monomer Concentration ◽  
Excitation Wavelength ◽  
Ultrapure Water ◽  
Fluorescent Substance ◽  
Composite Microspheres ◽  
Dispersing Agent ◽  
Intensity Changes ◽  
Content Of Oxygen

In this study, the monodispersed PS/PtOEP microspheres were successfully synthesized by dispersion polymerization, in which anhydrous ethanol and ultrapure water as dispersing agent, AIBN as an initiator, styrene as monomer, PtOEP as the fluorescent substance. Polystyrene microspheres with the size of the initiator, dispersant, the amount of monomer and so on, and has nothing to do with PtOEP. We can be obviously seen under scanning electron microscope. When in the same content of PtOEP, the particle size of composite microspheres size increases with increasing monomer concentration. When the excitation wavelength was 362nm, the PtOEP peak measured emission spectrum at 720nm. With the increasing size of composite microspheres, the peak fluorescence intensity changes. From the S-V diagram, we observed that the concentration of luminous intensity of composite microspheres monotonously dependent on oxygen, there is a linear correlation between PtOEP in 720nm fluorescence intensity and the concentration of oxygen. This method can be utilized to reliably monitor the content of oxygen in the system.

scholarly journals Chiral recognition and enantiomer excess determination based on emission wavelength change of AIEgen rotor

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ming Hu ◽  
Ying-Xue Yuan ◽  
Weizhou Wang ◽  
Dong-Mi Li ◽  
Hong-Chao Zhang ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Theoretical Calculation ◽  
Fluorescence Intensity ◽  
Chiral Recognition ◽  
Natural World ◽  
Enantiomer Excess ◽  
Intensity Changes ◽  
Colour Changes ◽  
Chiral Receptors ◽  
Fluorescence Wavelength

AbstractChiral recognition, such as enantioselective interactions of enzyme with chiral agents, is one of the most important issues in the natural world. But artificial chiral receptors are much less efficient than natural ones. For tackling the chiral recognition and enantiomer excess (ee) analysis, up until now all the fluorescent receptors have been developed based on fluorescence intensity changes. Here we report that the chiral recognition of a large number of chiral carboxylic acids, including chiral agrochemicals 2,4-D, is carried out based on fluorescent colour changes rather than intensity changes of AIEgen rotors. Moreover, the fluorescence wavelength of the AIEgen rotor linearly changes with ee of the carboxylic acid, enabling the ee to be accurately measured with average absolute errors (AAE) of less than 2.8%. Theoretical calculation demonstrates that the wavelength change is ascribed to the rotation of the AIEgen rotor upon interaction with different enantiomers.

L-Histidine Stabilized Copper Nanoclusters as a Fluorescence Probe for Determination of Fluazinam

NANO ◽  
2020 ◽  
Vol 15 (05) ◽  
pp. 2050063
Author(s):  
Zhifeng Cai ◽  
Xiu Yin ◽  
Jingling Fang ◽  
Jie Zhao ◽  
Tianqi Wu ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Fluorescence Probe ◽  
Synthesis Method ◽  
Fluorescence Emission ◽  
Average Diameter ◽  
High Dispersion ◽  
Excitation Wavelength ◽  
One Pot

In this contribution, a one-pot synthesis method possessing the advantages of simple, green and low-cost had been researched for the preparation of L-histidine-stabilized Cu nanoclusters (Cu NCs). Subsequently, the structure and optical properties of as-prepared Cu NCs were studied by using Fourier transform infrared (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy and UV-Vis absorption spectroscopy. TEM image of the Cu NCs showed high dispersion with an average diameter of 2.0[Formula: see text]nm. Fluorescence spectrum displayed that the Cu NCs emitted green fluorescence (emission wavelength of 492[Formula: see text]nm) under excitation wavelength of 393[Formula: see text]nm. Moreover, the as-synthesized Cu NCs illustrated excellent performances, such as good water solubility, UV stability and high-salt resistance. Interestingly, the fluorescence intensity of as-prepared Cu NCs was obviously quenched in the presence of fluazinam. Under optimal conditions, the relative fluorescence intensity was linear with the fluazinam concentrations from 1 to 40[Formula: see text][Formula: see text]M, with a detection limit of 0.25[Formula: see text][Formula: see text]M. Eventually, the fluorescence sensor was successfully used to determine fluazinam in real water samples.

Study on Three-Dimensional Fluorescence Spectra of Oil Concentration in Water

2011 ◽  
Vol 322 ◽  
pp. 144-147
Author(s):  
Yu Tian Wang ◽  
Li Li Yang ◽  
Xin Qiong Lu
Keyword(s):  
Quantitative Analysis ◽  
Fluorescence Intensity ◽  
Fluorescence Spectra ◽  
Three Dimensional ◽  
Measurement Model ◽  
Excitation Wavelength ◽  
Experimental Basis ◽  
Oil In Water ◽  
Oil Concentration ◽  
Fluorescence Spectrometer

According to the Lambert-Beer laws, the fluorescence spectra of oil in water were investigated by measuring excitation-emission matrixes with FS920 fluorescence spectrometer. On the basis of the three-dimensional fluorescence spectra of oil in water, the excitation wavelength of 290nm and emission wavelength of 324nm were chosen for the quantitative analysis of oil in water. The results show that the concentration of oil in water is linearly proportional to the fluorescence intensity in the range of 1ppm-100ppm, and the measurement model of concentration is obtained with the linear correlation coefficient of 0.9993. The artificial samples has also been tested and the results are satisfactory. The recovery is in the range of 92%-106%. The research provides experimental basis for the quantitative analysis of multi-component oil in water.

scholarly journals Two-photon microscopy of cortical NADH fluorescence intensity changes: correcting contamination from the hemodynamic response

2011 ◽  
Vol 16 (10) ◽  
pp. 106003 ◽  
Author(s):  
Edward Baraghis ◽  
Anna Devor ◽  
Qianqian Fang ◽  
Vivek J. Srinivasan ◽  
Weicheng Wu ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Hemodynamic Response ◽  
Two Photon Microscopy ◽  
Two Photon ◽  
Nadh Fluorescence ◽  
Intensity Changes

Rapid Synthesis of Non-Crosslinked and Monodisperse Polystyrene Microspheres

2013 ◽  
Vol 634-638 ◽  
pp. 2222-2227
Author(s):  
Chang Ming Ye ◽  
Yan Qin Yang ◽  
Feng Dong ◽  
Li Li ◽  
Xi Long Hao ◽  
...  
Keyword(s):  
Dispersion Polymerization ◽  
Monomer Concentration ◽  
Volume Ratio ◽  
Polymerization Process ◽  
Polystyrene Microspheres ◽  
Fenton Reagent ◽  
Uniform Size ◽  
Transmission Electron ◽  
New Synthesis ◽  
Monodisperse Polystyrene

Non-crosslinked and monodisperse polystyrene (PS) microspheres showing uniform size were synthesized by using a dispersion polymerization technique in the presence of the Fenton reagent (FeSO4/H2O2) as an initiator. The effects of stabilizer dosage, monomer concentration, volume ratio of dispersion medium and reaction time on both the morphology and dispersity of PS microspheres were investigated. The results of transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) indicated that the obtained PS microspheres are perfect with uniform size of about 170 nm under the optimum experimental condition. On the basis of the experimental results, the mechanism of PS polymerization was proposed, which should be helpful to guide the preparation of polymer microspheres with desired uniform size. In comparison with the conventional emulsion polymerization, this new synthesis technique with the Fenton reagent exhibits some advantages such as being a simple and fast polymerization process without deoxygenation.

Steady-State Fluorescence of Polystyrene Plasticized by Supercritical Carbon Dioxide

1996 ◽  
Vol 50 (6) ◽  
pp. 740-746 ◽  
Author(s):  
Ming Li ◽  
Frank V. Bright
Keyword(s):  
Molecular Weight ◽  
Steady State ◽  
Conformational Changes ◽  
Fluorescence Intensity ◽  
Excitation Wavelength ◽  
Fluorescence Intensity Ratio ◽  
Steady State Fluorescence ◽  
Proposed Model ◽  
Major Increase ◽  
Reduced Density

A steady-state fluorescence study of low-molecular-weight polystyrene (MW = 1060 g/mol and 13,000 g/mol) plasticized in supercritical CO2 is reported. In addition to excitation wavelength, molecular weight, and polystyrene concentration dependencies, CO2 density also strongly affects the emission spectral contours. A major increase in the steady-state fluorescence intensity and a significant decrease in the polystyrene 320- to 365-nm fluorescence intensity ratio are observed when CO2 density is increased. Concentration and conformational changes in the polystyrene molecules are used to explain the observations, and these results are proposed to arise from changes in the plasticization power of supercritical CO2 over the density range studied. A theoretical model is proposed that is based on the assumption that, at low CO2 densities and low polymer concentrations, polystyrene intermolecular interactions are negligible. The proposed model is able to fit our observed fluorescence data from a CO2 reduced density of 0.3 to 1.4.

Preparation of PVAc Particles by Dispersion Polymerization

2012 ◽  
Vol 184-185 ◽  
pp. 1134-1137 ◽  
Author(s):  
Wen Juan Gu ◽  
Xiao Hui Zhang ◽  
Jie Li
Keyword(s):  
Dispersion Polymerization ◽  
Monomer Concentration ◽  
Mixed Media ◽  
Monomer Conversion ◽  
Particle Properties ◽  
Submicron Size ◽  
Redox Initiator ◽  
Highly Uniform

Highly uniform polyvinylacetate particles of submicron size were prepared by dispersion polymerization in mixed media of isopropanol and water initiated by redox initiator of NaHSO3 and K2S2O8 using poly(N-vinylpyrrolidone) as stabilizer. Monomer conversion was studied gravimetrically. Both the morphology and the size of the particles were measured by TEM. The influences of various polymerization parameters, such as monomer concentration, stabilizer content, on the particle properties were systematically investigated. The PVAc particles synthesized in this research were mono-disperse spheres with the diameter between 100-1000 nm.

scholarly journals Analyzing the Effect of Fluorescence Characteristics on Leaf Nitrogen Concentration Estimation

2018 ◽  
Vol 10 (9) ◽  
pp. 1402 ◽  
Author(s):  
Jian Yang ◽  
Shalei Song ◽  
Lin Du ◽  
Shuo Shi ◽  
Wei Gong ◽  
...  
Keyword(s):  
Fluorescence Intensity ◽  
Nitrogen Concentration ◽  
Back Propagation ◽  
Principal Component ◽  
Back Propagation Neural Network ◽  
Leaf Nitrogen ◽  
Excitation Wavelength ◽  
Excitation Light ◽  
Leaf Nitrogen Concentration ◽  
Fluorescence Characteristics

Leaf nitrogen concentration (LNC) is a significant indicator of crops growth status, which is related to crop yield and photosynthetic efficiency. Laser-induced fluorescence is a promising technology for LNC estimation and has been widely used in remote sensing. The accuracy of LNC monitoring relies greatly on the selection of fluorescence characteristics and the number of fluorescence characteristics. It would be useful to analyze the performance of fluorescence intensity and ratio characteristics at different wavelengths for LNC estimation. In this study, the fluorescence spectra of paddy rice excited by different excitation light wavelengths (355 nm, 460 nm, and 556 nm) were acquired. The performance of the fluorescence intensity and fluorescence ratio of each band were analyzed in detail based on back-propagation neural network (BPNN) for LNC estimation. At 355 nm and 460 nm excitation wavelengths, the fluorescence characteristics related to LNC were mainly located in the far-red region, and at 556 nm excitation wavelength, the red region being an optimal band. Additionally, the effect of the number of fluorescence characteristics on the accuracy of LNC estimation was analyzed by using principal component analysis combined with BPNN. Results demonstrate that at least two fluorescence spectral features should be selected in the red and far-red regions to estimate LNC and efficiently improve the accuracy of LNC estimation.

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