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Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2014

Drying patterns of aqueous solutions of potassium salts of poly(riboguanylic acid) (KPolyG), poly(ribocytidylic acid) (KPolyC), and their mixtures KPolyG + KPolyC were studied on a cover glass, a watch glass, and a glass dish at room temperature. Accumulation of the polymers forming the broad rings near the outside edge and also in the inner area of the dried film was observed. The fine multiple ring structures formed, which supports the fact that the affinity of the polymer with the substrate is strong. Typical microscopic drying patterns of KPolyG, KPolyC, and KPolyG + KPolyC were spherulites, dendritic long rods, and sword (harberd)-like rods, respectively. The patterns changed depending on the location in the dried film. The dendritic long rods and sword-like rods were assigned to the crystals of double-stranded and/or triple-stranded helices of the G:C and 2G:C complexes. Cross-like drying patterns that originated from the salt-polymer interaction are also observed. The relationship between the polymer complexation of KPolyG + KPolyC systems and the drying patterns is similar to that of KPolyA (potassium salt of poly(adenylic acid)) + KPolyU (potassium salt of poly(uridylic acid)). © 2014 Springer-Verlag. Source


Okubo T.,Institute for Colloidal Organization | Okubo T.,Yamagata University
Macromolecular Symposia | Year: 2010

Convectional, sedimentation and drying dissipative patterns during the course of dryness of suspensions and solutions are reviewed. The whole processes of convection were analyzed in the seven steps: irregular circulation accompanied with the upward heat transportation, global convectional flow from the central area toward outside edge at the surface layers of liquid, cooperative formation of distorted Benard cells, reversal of global flow of convection, growing of the spoke lines from the outside edge toward central area at the liquid surface layers, cluster and further bundle formation of the spoke lines, and the convectional flow by the pinning effect. The sedimentary colloidal particles were suspended above the substrate by the electric double layers and moved by the balancing of the external force fields including convectional flow and sedimentation. Principal macroscopic drying patterns are broad rings and spoke lines. Microscopic patterns such as star, needle, street road, string and cross-like are formed. The stratified structures form from micro to macro scales. Information on the size, shape, conformation and/or flexibility of particles or polymers is transferred cooperatively, and further accompanied with the amplification and selection processes during the course of dryness. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2013

Macroscopic and microscopic drying patterns were observed on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous suspensions of similar sized aggregates of diamonds (CD1), which formed from the deionization of the pre-particles of diamond 4 nm in diameter. Two kinds of macroscopic patterns, i.e., outer and inner broad rings, and spoke lines were formed. Cooperative drying processes of the convection, sedimentation, and solidification were clarified. Microscopic drying patterns showing the formation of very large dendritic aggregates from the CD1 particles were observed only when the excess amount of sodium chloride higher than 2 mM coexisted in the initial suspensions before dryness and further initial CD1 concentration is lower than 0.17 wt%. © 2013 Springer-Verlag Berlin Heidelberg. Source


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2013

Macroscopic and microscopic drying patterns were observed on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solutions of α-cyclodextrin (αCD), β-cyclodextrin (βCD), and γ-cyclodextrin (γCD), i.e., cone shape oligomers of polysaccharide. For all CD molecules, two kinds of macroscopic patterns, outside and inner broad rings and spoke lines formed. Multi-broad rings were formed for βCD in the inner region of the main broad ring at the outside edge especially at the high concentrations. Cooperative drying processes of the convection, sedimentation, and solidification were clarified. Microscopic drying patterns showing the formation of rod-like and/or sward-like crystals were observed mainly in the direction along the spoke lines. The microscopic patterns of βCD were similar to those of some of polysaccharides and polynucleotides the authors studied previously. α- and γ-cyclodextrins were slightly hygroscopic, and clear-cut drying patterns were not observed. © 2013 Springer-Verlag Berlin Heidelberg. Source


Okubo T.,Institute for Colloidal Organization
Colloids and Surfaces B: Biointerfaces | Year: 2011

Dissipative drying patterns of aqueous mixtures of potassium salts of poly(riboadenylic acid) (KPolyA) and poly(ribouridylic acid) (KPolyU) were studied on a cover glass, a watch glass and a glass dish at room temperature. Accumulation of the polymers forming the broad rings near the outside edge and the inner area of the dried film was observed. The fine multiple ring structures formed when the affinity of the polymer with the substrate is strong. Microscopic drying patterns changed drastically depending on the location in the dried film. Microscopic drying patterns were mainly dendritic long rods and sword (halberd)-like rods. They are assigned to the crystals of double-stranded and triple-stranded helices of the A:U and A:2U complexes, respectively. Cross-like drying patterns are also observed originated from the salt-polymer interaction. © 2011 Elsevier B.V. Source

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