Characterization and Investigation of Reduction Capacity of Hydrophilic Organic Matter from Compost and its Influence Factors / 分析化学

Reduction capacity ( RC ) is an important index to evaluate the redox ability of dissolved organic matter. In order to determine the RC, hydrophilic organic fractions ( HyI ) isolated from dissolved organic matter extracted from the uncomposted and composted samples were used as electron donators and mediators, and three kinds of irons were chosen as electron acceptors. The results showed that, the RC values from the composted sample were 15. 88, 13. 41 and 51. 45 mmol e -/mol C for the electron acceptors Fe2(SO4)3, Fe(NO3)3 and FeCit, respectively, which were higher than the corresponding values (13. 45, 11. 77 and 43. 16 mmol e-/mol C) from the uncomposted sample. The electron acceptor type shows a dramatic influence on the RC value of HyI. The RC value determined by FeCit was obviously higher than that measured using Fe2( SO4 ) 3 and Fe( NO3 ) 3 , and the microbial reducing capacity of the HyI was lower than the corresponding native reducing capacity. By analyzing the special absorbencies ( SUVA254 and SUVA280 ) , absorbance ratios ( A2/A3 and A4/A6 ) and integrated area from UV-vis spectra, it can be found that the RC was affected by aromatic degree, unsaturated conjugated structure, and molecular weight. Excitation-emission matrix spectra coupled with regional integration analysis showed that the relative content of humic-like substances ( humic-like acids and fulvic-like acids) was the main factor influencing the RC value of HyI. The results obtained can be used to characterize the redox properties of HyI, and reveal its role in the transformation and degradation of pollutants during composting.

Recognition of Mercury Ion and Copper Ion with 8-Aminoquinoline Derivatives / 分析化学

The novel 8-Aminoquinoline(8-AQ) derivatives receptor was designed and synthesized.Its struc ture was characterized by NMR and ESI-MS.It was investigated to recognize metal ions such as Cu~(2+), Hg~(2+), Pb~(2+), Zn~(2+), Ni~(2+) and Cd~(2+) via its absorption and fluorescence spectra.The recognition mechanism .and bind ing mode were discussed.The results showed that 8-AQ derivatives 1 coordinated with Cu~(2+) can induce a new absorption peak at 509 nm, which turned the solution to red from colorless.In acetonitrile Hg~(2+) and Cu~(2+) induced dramatic enhancement in the fluorescence of the derivation 1 by 368 and 192 folds.Job plot showed 1:1 stoichiometry between 8-AQ and Cu~(2+) or Hg~(2+).

Effects of Zinc and Hypothermic Process during the Light and Dark Adaptation of Vertebrate Retina

PURPOSE: The purpose of this study was to clarify the effects of zinc treatment and hypothermia on visual adaptation and visual sensitivity in bullfrogs (Rana catesbeiana), which are poikilothermal animals capable of adjusting quickly to environmental temperature changes. METHODS: The effects of both zinc treatment and hypothermia on visual sensitivity were studied by using electroretinogram (ERG) recording and absorption spectra scanning before and after zinc and TSQ (N-[6-methoxy-8-quinolyl]-p-toluene sulfonamide) treatment, with or without temperature changes. RESULTS: In spite of malnutrition due to hibernation, the optimal zinc concentration effect was obtained at 10-4 M (10-2 M 200 microliter ZnCl2 in 20 microliter Ringer's solution) according to ERG recording. After zinc treatment and hypothermia induction, increments of all ERG components and thresholds were taken by ERG recording. These results showed that both zinc treatment and hypothermia may increase visual sensitivity during visual adaptation. In spectral scans, the absorbance increment due to zinc treatment and hypothermia was shown over the whole spectral range (400~750 nm), and it was especially prominent at alpha-peak (about 500 nm). In addition, there was a decrease in absorption differences between dark adaptation and light adaptation after zinc treatment. Furthermore, according to the visual sensitivity decrement using TSQ as a zinc specific chelator, this visual sensitivity increase was shown to be caused by zinc. CONCLUSIONS: As the results suggest, both zinc treatment and hypothermic effects may improve visual sensitivity by promoting rhodopsin regeneration and inhibiting rhodopsin bleaching induced by light illumination. Zinc may activate the enzyme activity of retinol dehydrogenase and phosphodiesterase, while hypothermic effects may improve precursor transport, which is required for rhodopsin regeneration, by tightening membrane adhesion between retinas and retinal pigment epithelia. In addition, we believe that zinc treatment and hypothermic effects may work synergistically to accelerate visual sensitivity during visual adaptation.