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Fu, N.,Lv, R.,Guo, Z.,Guo, Y.,You, X.,Tang, B.,Han, D.,Yan, H.,Row, K.H. Elsevier 2017 Journal of chromatography Vol.1492 No.-
<P>In this work, choline chloride (ChCI) deep eutectic solvents (DESs) were evaluated for the pretreatment of palm samples in the analysis of polyphenols, such as protocatechuic acid, catechins, epicatechin, and caffeic acid. During the enrichment step of the pretreatment, eight DESs comprising ChCI with ethylene glycol (EG), glycerol (Gly), xylitol (Xyl), phenol (Ph), formic acid (FA), citric acid (CiA), oxalic acid (OA), or malonic acid (MA), were prepared and applied to the reflux extraction of polyphenols from palm samples. All the DESs exhibited higher polyphenol extraction efficiency than methanol, and the highest extraction efficiency was obtained using ChCI-FA (1:1, mole ratio). For the purification step of the pretreatment, eight ChCI DES-modified adsorbents were prepared by hydrothermal polymerization and packed into solid phase extraction (SPE) cartridges, and ChCI-Urea, ChCI-Gly, ChCI-FA, and water, were used as eluents. The ChCI DES-modified adsorbents were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, and Brunauer-Emmett-Teller surface analysis, and the polyphenols were analyzed by mass spectrometry and high-performance liquid chromatographultraviolet detection. The highest purification efficiency was obtained using the ChCI-Ph DES-modified adsorbent as the SPE packing material and ChCI-Urea-H2O (1:1:5, mole ratio), ChCI-Gly (1:1, mole ratio), ChCI-FA-H2O (1:1:5, mole ratio), and H2O as the eluents. Compared to conventional purification processes that employ commercial C-18 or C-8 SPE columns with organic solvents as eluents, the ChCI DES-based SPE purification process successfully avoided the use of expensive commercial SPE columns and organic solvents. Furthermore, it isolated a larger amount of the target compounds under the same experimental conditions, and could be applied over five cycles with good reversibility. This work indicates that DESs as green solvents have great potential for the totally green pretreatment of samples during the enrichment and purification processes. (C) 2017 Elsevier B.V. All rights reserved.</P>
Fu, Z.,Yang, H.K.,Moon, B.K.,Choi, B.C.,Jeong, J.H. Elsevier 2009 CURRENT APPLIED PHYSICS Vol.9 No.6
Zn<SUB>2</SUB>SnO<SUB>4</SUB>:Eu<SUP>3+</SUP> nanocrystals were one-step synthesized by hydrothermal method for the first time. All the products were systematically characterized by powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), electron probe X-ray microanalyzer (EPMA), photoluminescence (PL) and photoluminescent excitation (PLE). The characteristic peak of Eu<SUP>3+</SUP>-doped in Zn<SUB>2</SUB>SnO<SUB>4</SUB> nanocrystals was also detected. The luminescent properties of blank and Eu<SUP>3+</SUP>-doped Zn<SUB>2</SUB>SnO<SUB>4</SUB> nanocrystals were reported.
Fu, Z.,Yang, H.K.,Moon, B.K.,Choi, B.C.,Jeong, J.H. Elsevier 2009 Current Applied Physics Vol.9 No.2
La<SUB>2</SUB>Sn<SUB>2</SUB>O<SUB>7</SUB>:Eu<SUP>3+</SUP> nanospheres were prepared by a hydrothermal synthesis method. Well-crystallized and phase-pure La<SUB>2</SUB>Sn<SUB>2</SUB>O<SUB>7</SUB>:Eu<SUP>3+</SUP> solid nanospheres ∼400nm in size can be readily obtained after calcination at 900<SUP>o</SUP>C, a temperature much lower than that of the conventional solid-state method. The prepared samples were systematically characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and photoluminescence excitation spectra (PLE). Furthermore, PL results for the Eu<SUP>3+</SUP>-doped La<SUB>2</SUB>Sn<SUB>2</SUB>O<SUB>7</SUB> nanospheres show that the material displays intense and prevailing emission at 585nm belonging to the <SUP>5</SUP>D<SUB>0</SUB>-<SUP>7</SUP>F<SUB>1</SUB> magnetic dipole transition.
( Y. Y. Wang ),( Z. B. Fu ),( K. L. Ng ),( C. C. Lam ),( A. K. N. Chan ),( K. F. Sze ),( W. K. R. Wong ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.6
Production of recombinant proteins by excretory expression has many advantages over intracellular expression in Escherichia coli. Hyperexpression of a secretory exoglucanase, Exg, of Cellulomonas fimi was previously shown to saturate the SecYEG pathway and result in dramatic cell death of E. coli. In this study, we demonstrated that overexpression of the PspA in the JM101(pM1VegGcexL-pspA) strain enhanced excretion of Exg to 1.65 U/ml using shake-flask cultivation, which was 80% higher than the highest yield previously obtained from the optimized JM101(pM1VegGcexL) strain. A much higher excreted Exg activity of 4.5 U/ml was further achieved with high cell density cultivation using rich media. Furthermore, we showed that the PspA overexpression strain enjoyed an elevated critical value (CV), which was defined as the largest quotient between the intracellular unprocessed precursor and its secreted mature counterpart that was still tolerable by the host cells prior to the onset of cell death, improving from the previously determined CV of 20/80 to the currently achieved CV of 45/55 for Exg. The results suggested that the PspA overexpression strain might tolerate a higher level of precursor Exg making use of the SecYEG pathway for secretion. The reduced lethal effect might be attributable to the overexpressed PspA, which was postulated to be able to reduce membrane depolarization and damage. Our findings introduce a novel strategy of the combined application of metabolic engineering and construct optimization to the attainment of the best possible E. coli producers for secretory/excretory production of recombinant proteins, using Exg as the model protein.