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81.
Guifang Ju Yihua Hu Li Chen Xiaojuan Wang Lihua Hung 《Applied Physics A: Materials Science & Processing》2014,114(3):867-874
We investigate the persistent luminescence in europium-doped SrMg2(PO4)2 upon codoping with auxiliary terbium. Luminescence properties of the phosphors, including photoluminescence, luminescence decay and thermoluminescence, are systematically studied. SrMg2(PO4)2:Eu2+ shows only a weak persistent luminescence, and codoping with Tb3+ is necessary to obtain considerable persistent luminescence. An energy level scheme is constructed to convey reasonable trapping and detrapping processes in the material. 相似文献
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84.
Non-specular reflection of self-collimated beams in photonic-crystal-made prism and waveguide system
Fei Zhou Kui Han Yang Ge Faliang Ju Yifeng Shen Gang Tang 《Optics Communications》2012,285(12):2780-2784
We demonstrate a dual-beam-reflection phenomenon for a Gaussian beam illuminating at a Kretschmann configuration composed of a photonic-crystal-made prism and a dielectric waveguide. One reflection beam has a positive shift and the other has a negative shift. The finite-difference time-domain (FDTD) shows that the specific phenomenon takes place only when the corresponding quasi-guided mode supported in the Kretschmann configuration is excited. Field profile of the quasi-guided mode demonstrates a strong localized stationary field in the dielectric waveguide. We found that the maximum positive lateral shift (LS) is 14.27a (where a is the lattice constant), corresponding to 3.07 times of the incident wavelength, which is 0.7135 times of the beam waist and much larger than that in some previous reports. 相似文献
85.
Chang Ling Zhao Zhong Jian Chen Xue Song Bai Can Ding Ting Ju Long Fu Gang Wei Kang Ru Miao 《Molecular diversity》2014,18(3):687-700
This paper summarizes the main achievements about the structure–activity relationships of anthocyanidin glycosylation. Anthocyanidin glycosylation is the essential step of anthocyanin biosynthesis and also the prerequisite of the further modifications of anthocyanins, which is jointly characterized by the glycosylation site, the type and number of the glycosyl as well as the glycosidic bond type. It generally enhances the stability, results in the hypsochromic effect and blueing, decreases the bioavailability and anticancer activity, and decreases, increases, or does not change the antioxidant activity of the anthocyanidins or anthocyanins, which is synergetically determined by the glycosylation site and the type and number of the glycosyl. Thereinto, in nature, the blue hues caused by the glycosylation may also be reinforced by the formation of the anthocyanic vacuolar inclusions. This review could provide a reference for the research of the structure-optimizing and function-exploiting of anthocyanins. 相似文献
86.
87.
Le Wang Yong Ye Zhiyu Ju Shangbin Zhong Yufen Zhao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1958-1963
A modified method for preparing large-scale quantities of pure hexachlorocyclophosphazene (N3P3Cl6) and octachlorocyclotetraphosphazene (N4P4Cl8), phosphorus pentachloride with ammonium chloride, in the presence of zinc chloride, has been developed. The time of the reaction and the quantities of the catalyst are also studied. It is found that the optimum reaction time is 1.5 h and by-products are remarkably reduced by addition of 10% zinc chloride. As indicated by the 31 P NMR spectra, the synthesis and separation of cyclophosphazenes can be accomplished in moderate yield of tetramer (39%) and good yield of trimer (83%). 相似文献
88.
Eun‐Ju Ha Bong‐Soo Kim Eun‐Kyoung Park Ki‐Won Song Sun‐Gu Lee Seong Soo A. An Hyun‐jong Paik 《先进技术聚合物》2013,24(1):75-80
Ni2+‐complexed poly(2‐acetamidoacrylic acid) (PAAA) hydrogel beads were developed for the site‐specific reversible immobilization and purification of the histidine‐tagged green fluorescent protein (His‐tagged GFP). PAAA hydrogel beads were prepared by photopolymerization, and significantly improved mechanical properties of PAAA hydrogel beads were observed in comparison with PAAA hydrogel from our previous study. Confocal laser scanning microscopy was used to determine the binding of His‐tagged GFP to the hydrogel beads in three‐dimensional space. Photoluminescence spectroscopy revealed 89% of binding efficiency of His‐tagged GFP to the Ni2+‐PAAA hydrogel beads, 51% of yielding recovery. The maximum binding capacity of His‐tagged GFP was estimated to be 0.45 µg/mg of Ni2+‐PAAA hydrogel beads. The recombinant His‐tagged GFP from the soluble fraction of E. coli BL21(DE3) cell lysates was purified with Ni2+‐PAAA hydrogel beads. The major advantage of the Ni2+‐PAAA hydrogel beads system was simple preparation procedures of producing the matrix, because PAAA hydrogel beads had relatively enhanced mechanical strength than soft hydrogels. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
89.
Cellular prion protein, a membrane protein, is expressed in all mammals. Prion protein is also found in human blood as an anchorless protein, and this protein form is one of the many potential sources of misfolded prion protein replication during transmission. Many studies have suggested that β-amyloid1–42 oligomer causes neurotoxicity associated with Alzheimer''s disease, which is mediated by the prion protein that acts as a receptor and regulates the hippocampal potentiation. The prevention of the binding of these proteins has been proposed as a possible preventative treatment for Alzheimer''s disease; therefore, a greater understanding of the binding hot-spots between the two molecules is necessary. In this study, the epitope mapping immunoassay was employed to characterize binding epitopes within the prion protein and complementary epitopes in β-amyloid. Residues 23–39 and 93–119 in the prion protein were involved in binding to β-amyloid1–40 and 1–42, and monomers of this protein interacted with prion protein residues 93–113 and 123–166. Furthermore, β-amyloid antibodies against the C-terminus detected bound β-amyloid1–42 at residues 23–40, 104–122 and 159–175. β-Amyloid epitopes necessary for the interaction with prion protein were not determined. In conclusion, charged clusters and hydrophobic regions of the prion protein were involved in binding to β-amyloid1–40 and 1–42. The 3D structure appears to be necessary for β-amyloid to interact with prion protein. In the future, these binding sites may be utilized for 3D structure modeling, as well as for the pharmaceutical intervention of Alzheimer''s disease. 相似文献
90.
A liquid chromatographic chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was applied to the resolution of 15 analytes, including racemic rasagiline, a chiral drug for the treatment of Parkinson's disease, and its analogues. The composition of mobile phase was optimized to be ethanol/acetonitrile/acetic acid/triethylamine (80:20:0.2:0.3, v/v/v/v) by evaluating the chromatographic results for the resolution of five selected analytes under various mobile phase conditions. Under the optimized mobile phase conditions, racemic rasagiline was resolved quite well with a separation factor of 1.48 and resolution of 2.71 and its 14 analogues were also resolved reasonably well with separation factors of 1.06–1.54 and resolutions of 0.54–2.11. Among 15 analytes, racemic rasagiline was resolved best except for just one analyte. The analyte structure–enantioselectivity relationship indicated that racemic rasagiline has the most appropriate structural characteristics for resolution on the chiral stationary phase. 相似文献