Biodiesel fuels contain unsaturated fatty acid ester, which can easily oxidize, especially when exposed to ultraviolet light. The products formed by this oxidation give rise to sediment or gum formation. As a result, the fuel can contribute to the corrosion and plugging of the filter pump. Antioxidants have been used in an effort to stabilize biodiesels, but there is still a need for a biodiesel composition with improved oxidation stability. In general, good fuel compositions should provide synergistic combinations of a biodiesel and antioxidants. Our work involved the synthesis of antioxidants to improve the oxidative stability of biodiesel fuel.
We report the design and synthesis of a novel chemosensor (Rh6G-Cin) rhodamine-based indicator for selective detection of Zn2+ ion. Rh6G-Cin displayed high selectivity towards Zn2+ from various metal ions, including Ca2+, Ag+, Cd2+, Co2+, Cu2+, Al3+, Zn2+, Cr3+, Ba2+, Fe2+, Fe3+, Gd3+, Hg2+, Mg2+, Mn2+, Nd3+, Pb2+, Sr2+ and Ni2+, and the resultant complex is [Rh6G-Cin-Zn2+]. The obvious change from colorless to pink upon the addition of Zn2+ could make it a suitable "naked eye" indicator for Zn2+. More significantly, the sensor displayed a remarkable colorless to yellowish green fluorescence switch in the presence of Zn2+ ions. The ring-opening mechanism of the rhodamine spirolactam was induced by Zn2+ binding, and the 3:1 stoichiometric structure between Rh6G-Cin and Zn2+ was adequately supported by the Job's plot evaluation, optical titration and 1H NMR results.
Over the past two decades, fluorescent chemosensors have emerged as important alternatives to traditional qualitative and quantitative analysis technologies. Such sensors have been designed and synthesized for various uses, including biological, environmental, medical, and electromagnetic applications.
1-12Fluorescent sensors are highly sensitive, easy to use, and have wide applicability. In addition, such sensors can be used for analyzing metal ions quickly and accurately via the formation of a complex between the fluorophore and the metal ion being detected.
13The fluorophore anthracene and its derivatives have been used widely for fluorescence sensing, including the detection of metal ions, simple inorganic anions, and small organic molecules as well as for pH measurements. [14][15][16][17] These materials also exhibit very interesting photophysical properties: both chelation-enhanced fluorescence (CHEF) and chelation-enhanced fluorescence quenching (CHEQ) have been observed during complex formation. [18][19][20][21][22] We had previously reported that 9, 10-bis(3-hydroxypropylamino-methyl)anthracene exhibits significant OFF-ON-type fluorescence responses after interacting with Fe 3+
A rhodamine-based fluorescent chemosensor (Rh6G-2HC) was synthesized easily by a one-step condensation reaction. The structure was characterized using NMR, MS and EA spectroscopies. As soon as Cu 2+ was added into the chemosensor solution, a color change from colorless to pink color was observed, and a considerable change in the absorption and fluorescence spectra. However, no spectral changes were indicated for other heavy metals such as Ag + , Zn 2+ , Cd 2+ , and Co 2+. In order to provide a more detailed metal sensing performance, the optical and structural properties for the Cu 2+ sensing effect were investigated using UV-Vis, fluorescence and H-NMR spectroscopies.
Abstract-Reproduction of antique document is of importance with the concept of sharing the their contents and original aspects in terms of textual and artistic message. 'Pine tree ink stick' and 'Oil ink stick' are greatly enjoyed in their uses in the most written documentary works. Thus, it is said that the approach of this study has implied considerable meanings to cultural aspects. In this work, we have performed to investigate the reproduction and restoration study for antique documents. With comparison and analysis of some types of "ink stick", we have prepared several ink samples, controlling viscosity, surfactant, thickness agent, and applied these inks to the target antique document. Several reproduced samples showed a practical application possibility in terms of reproduction and restoration.
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