Artif Intern Organs 18-1972.98x, there has been great interest in the separation and identification of the role of UMM. However, few of the compounds isolated from UMM fractions were demonstrated to play an important role in humans. Thus, the separation and identification of the real UMM is essential for UMM research. Methods: Urine and serum samples from uremic patients and healthy subjects were separated by gel permeation chromatography. Two presumed UMM fractions, A and B, were obtained from uremic sera and urine, normal urine, but not normal sera. Fraction A was further isolated by anion exchange chromatography and a series of sub-peaks were obtained. The sub-fraction A-3 obtained in the second step was desalted on a Sephadex G-15 column, and characterized by IR, UV and matrix-assisted laser desorptionr ionization time-of-flight mass spectrometry-MALDI-TOF-MS.. Further separation of sub-fraction A-3 was performed by high performance liquid chromatography-HPLC.. Results: By gel permeation chromatography, two UMM peaks-A and B. were detected at 206 nm in normal urine, uremic sera, but they were barely noticed in the profile of normal sera. In contrast, the absorption at 206 nm of fractions A and B from uremic serum and urine were smaller than that of fractions A and B from normal urine. Fractions A from different origins were resolved into eight to nine sub-peaks at 230 nm by anion exchange chromatography. One of these sub-peaks, A-3, was detected in uremic serum and normal urine, but is undetectable in uremic urine. After desalting, sub-fraction A-3 was separated into two parts designated as A-3-I and A-3-II. MALDITOF-MS revealed that fraction A-3-I and A-3-II from two origins were identical, respectively-fraction A-3-I contained three components with MW 839.69, 1007.94 and 2015.16 and fraction A-3-II consisted of another three components with MW 873.69, 1106.67 and 1680.28. Six middle molecular compounds in sub-fraction A-3 were thoroughly resolved by HPLC. Conclusion: Our results demonstrated that the UMM sub-fraction A-3 contains the real UMM in the MW range of 800-2015 Da. By multi-step chromatographic isolation, six real middle molecular compounds were purified and character-

Crystalline macromolecules form folded-chain lamellar and metastable crystals. Annealing at a temperature below melting point results in a thickening of the metastable crystals to construct more stable ones. Such a process was visualized by AFM equipped with a hot stage in monolayers of poly- (ethylene oxide) lamellar crystals on a silicon wafer surface. Our observations show that the monolayers can be thickened in a stepwise manner during stepwise heating to temperatures below the melting point. Our analyses show the thickening process and mechanism as follows: At the first step a small portion of the lamellar crystals have the capability to be spontaneously thickened into a thicker one at a certain temperature range, giving rise to a difference in lamellar thickness. In the following step the thinner lamellae are forced to melt, and then the melted molecules enter an amorphous phase in which they are transported toward the thicker lamellae and finally recrystallize in the thicker ones. This inductive mechanism is analogous to the evaporation-condensation mechanism.

Amphiphilic block copolymer polystyrene-block-polyacrylic acid (PS-b-PAA) self-assembles into spherical core-shell micelles in the block-selective solvent water with the PS block as the core and the PAA block as the shell. When adding 1-propanol to the micellar solution and then casting the micellar solution at suitable temperatures, the spherical core-shell micelles are assembled into flower-like aggregates on substrates such as glass, formvar film or silicon. The size of the flower-like aggregates ranges from 2 2mm2 to 15 15mm2. Casting temperature, substrate type and character of the block copolymers and additive can all affect the assembly of PS-b-PAA micelles. The assembly of micelles is similar to the fractal aggregation of inorganic particles and a possible reason is discussed.

In this letter we describe a simple physical method for the ordered aggregation of scattered single spherical polystyrene-b-poly(acrylic acid) (PS-b-PAA) micelles. First, narrow dispersed spindlelike aggregates, about 60 nm in diameter and 1.5 Im in length, are obtained from the aggregation of single spherical PS-b-PAA micelles at 0℃ on a glass slide. Then, the yielding spindlelike units can further aggregate into long-ranged, close-packed, flowerlike arrays after a given amount of freeze-thaw cycles. The formation of the interesting arrays is ascribed to the templated aggregation of micelles on the water polycrystal at the freezing point.

The adsorption of poly(4-vinyl pyridine) (P4VP) unimers into spherical core-shell micelles self-assembled by polystyrene-block-poly(acrylic acid) (PS200-b-PAA78) in ethanol is studied by a combination of static light scattering (SLS) and dynamic light scattering (DLS). P4VP unimers with a coil size of ca. 7.9 nm can be first absorbed into the PS-b-PAA spherical core-shell micelles with a ydrodynamic diameter of 79.9 nm and then penetrate into the shell of the micelles to form hydrogen-bonded micelleunimers complexes in ethanol. During the adsorption, the hydrodynamic diameter and gyration radius of the micelle-unimers complexes decrease first and then stay almost unchanged when P4VP solution in ethanol is added into the PS-b-PAA micelle solution. It is also found that the structure of the micelleunimers complexes remains spherical but becomes smaller and denser than that of the PS-b-PAA micelles after absorption of P4VP unimers.