منابع مشابه
Superdendrites in Directional Solidification of Polymer-solvent Mixtures
The directional solidification of the transparent binary alloy succinonitrile-poly(ethylene oxide) was studied in an experiment in which solidification speeds of about 2 mm/sec could be reached without loss of the linear temperature gradient. The low diffusivity of the polymer solute allowed the study of the dynamics of rapid solidification using an optical microscope. For both normal and doubl...
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The conversion of chlorophyll a (Chl a) monomers into large aggregates in six polar solvents upon addition of water has been studied by means of absorption, fluorescence spectroscopy and fluorescence lifetime measurements for the purpose of elucidating the various environmental factors promoting Chl a self-assembly and determining the type of its organization. Two empirical solvent parameter sc...
متن کاملNegative thermodiffusion of polymers and colloids in solvent mixtures
Results on thermodiffusion of poly~ethylene oxide! and colloidal boehmite (g-AlOOH! rods in ethanol/water mixtures are presented. Data were obtained using thermal diffusion forced Rayleigh scattering. The sign of the Soret coefficient of the boehmite rods changes from positive to negative with increasing water content, i.e., at sufficiently high water content the colloidal particles move to hig...
متن کاملSinglet Oxygen Reactivity in Water-rich Solvent Mixtures
The 3-methylindole (3MI) oxygenation sensitized by psoralen (PSO) has been investigated in 100%, 20% and 5% O 2 -saturated water/ dioxane (H 2 O/Dx) mixtures. The lowering of the O 2 * chemical rate when water (k chem 3MI = 1.4 109 M s) is replaced by deuterated water (k chem 3MI = 1.9 108 M s) suggests that hydrogen abstraction is involved in the rate determining step. A high dependence of the...
متن کاملPhase Behavior of Polylactides in Solvent-Nonsolvent Mixtures
Isothermal phase diagrams for the semicrystalline poly-L-lactide (PLLA) and the amorphous poly-DL-lactide (PDLLA) in combination with several solvent-nonsolvent combinations (dioxane/water, dioxane/methanol, chloroform/methanol, and NMP/water) have been determined. The locations of the liquid-liquid miscibility gap, the solid-liquid miscibility gap and the vitrification boundary in the isotherm...
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ژورنال
عنوان ژورنال: Nature
سال: 1993
ISSN: 0028-0836,1476-4687
DOI: 10.1038/365398a0