Absorption Ability of Different M/G Values of Alginate Fiber

The M/G values of different sodium alginate were studied by means of H-NMR. The alginate fiber was prepared via wet-spinning technology. The effects of M/G, the concentration of sodium-alginate, the concentration of the coagulation bath and coagulating time on the absorptive ability of alginate fiber were discussed. The results show that the absorptive ability to different substances varies in such order： physiological saline 〉 blood 〉 tap water 〉distilled water. The absorptive ability of the alginate fiber increases with the increase of M/G value and the concentration of sodium-alginate. Gradually increasing the concntration of coagulation bath, it increases until the concentration is up to 5%. However, it reduces with lasting coagulating tine.

Dissolved organic carbon fractionation in wet deposition and its potential impact on radiative forcing in the central Tibetan Plateau

As an important component of carbonaceous matters,dissolved organic carbon(DOC)can absorb and scatter the solar radiation at ultraviolet and blue wavelengths.The wet deposition process has great impact on the con-centration and light absorption ability of precipitation DOC,affecting the climatic effect caused by DOC in the atmosphere.In this study,light absorption and fluorescence characteristics of precipitation DOC was investigated in the central Tibetan Plateau(TP).The results showed that the mean DOC concentration and mass absorption cross-section measured at 365 nm(MAC_(365)) in Tanggula(TGL)station were 0.59±0.42 mg/L and 0.37±0.19 m^(2)/g,respectively,while both values showed much higher volatilities than those of aerosols.DOC concentrations had significant negative correlation with the precipitation amount,while MAC_(365) values increase with the precipitation amount in TGL station.Therefore,DOC with high light-absorbing ability was preferred to be retained in the atmosphere during wet deposition.In this study,precipitation DOC contained three fluorescent components(one humic-like component and two tyrosine-like components)mainly from local biomass burning sources.DOC concentration showed a negative relationship with MAC_(365) value in TGL station.The wet deposition of DOC with low light-absorbing ability can reduce the strong negative radiative forcing caused by secondary organic aerosol due to high proportion of DOC in secondary organic carbon.Similar phenomenon was also found in Nam Co,Lulang and Everest stations of previous study,which may have a potential impact on radiative forcing in the atmosphere of TP.