Studies on syntheses and permeabilities of special polymer membranes

Summary An active transport of alkali metal ion through cation exchange membranes was studied under various conditions. This active transport was facilitated by using a greater anion species on an acidic side in a diaphragm cell, in which one side of the solution was adjusted to be acidic and the other side alkaline across the membrane. An active transport fraction of alkali metal ion was in order poly(styrenesulfonate)>benzenesulfonate>Cl^– >I^–>Br^– of anion species on the acidic side. A rate, fraction and period of the active transport of metal ion were significantly influenced by an electric potential gradient in the membrane.     

Studies on syntheses and permeabilities of special polymer membranes.: 15. Permeation characteristics of nylon-12 cellulose acetate blends

The permeation characteristics of nylon-12-cellulose acetate polymer blend membranes in the separation of polymers, poly(vinyl alcohols), from their aqueous solutions were investigated under various conditions. The permeation characteristics were influenced markedly by the ratio of nylon-12-cellulose acetate, the feed concentration, the operating pressure and temperature. It was found that the changes of polymer ratio and the concentration of blended polymer were related to the change of microporous structure of the resulting membranes. When the cellulose acetate content was higher a significant compaction of the membrane occurred under pressure. It was found that there was a concentration polarization of poly(vinyl alcohol) molecules on the membrane surface, whose thickness increased with increase in molecular weight of poly(vinyl alcohol) and in feed concentration. The bursting strength of the polymer blend membranes swollen with water increased considerably as the cellulose acetate content in the blended polymer increased.     

Studies on syntheses and permeabilities of special polymer membranes. IV. Permeation characteristics of improved cellulose nitrate membranes

For the purpose of the application of cellulose nitrate membranes for artificial kidneys, the permeation characteristics and the bursting strength of three types of membranes, which were prepared from a system of cellulose nitrate/methyl alcohol/1,4-dioxane/barium perchlorate (CN-1), from a system of cellulose nitrate/methyl alcohol/formamide (CN-2), and a poly(ethylene terephthalate) cloth coated with the casting solution of CN-2 (CN-3), were investigated under various conditions. It was found that permeabilities of these membranes were influenced significantly by the preparation methods of the membranes and the permeation conditions, and they depended upon the structure of the resulting membranes and the interaction between the polymer in the membrane and the feed. In blood filtrations, the permeation rates of our three types of membranes had about four-fold values than a cuprophane membrane, and moreover no protein was found in the blood filtrate. The bursting strength of the membranes swollen with water was in the order CN-3 > cuprophane > CN-2 > CN-1, and this ratio was calculated to be about 5.9:1.0:0.5:0.3     

Glycan Sequence‐Dependent Nod2 Activation Investigated by Using a Chemically Synthesized Bacterial Peptidoglycan Fragment Library

Nucleotide oligomerization domain‐containing protein 2 (Nod2), an innate immune receptor, recognizes bacterial cell‐wall peptidoglycan (PGN), the minimum ligand of which is muramyl dipeptide (MDP). Enzymatic digestion of PGN appears to be important for Nod2 recognition. PGN is degraded by muramidase or glucosamidase through a process that produces two types of glycan sequence; glycans containing GlcNAcβ(1→4)MurNAc or MurNAcβ(1→4)GlcNAc. In this report, a range of disaccharide or tetrasaccharide fragments of each sequence were chemically synthesized, and their activities in stimulating human Nod2 (hNod2) were investigated. The results reveal that hNod2 recognitions is dependent on the glycan sequence, as demonstrated by comparing the activities of glycans with the same peptide moieties. (MurNAcβ(1→4)GlcNAc)₂‐containing structures exhibited stronger activity than those containing (GlcNAcβ(1→4)MurNAc)₂. The results suggest that differences in the enzymatic degradation process affect the host's immunomodulation process.     

Effects of molecular weight on phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

The phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends was studied in relation to the molecular weight. The samples were prepared by both solution blends, which showed two glass‐transition temperatures (T_g), and melt blends (MQ), which showed a single T_g, depending on the composition of the blends. The T_g of the MQ series was independent of the molecular weight of the homopolymer, although the degree of transesterification in the blends was affected by the molecular weight. The MQ series showed two exotherms during the heating process of a differential scanning calorimetry scan. The peak temperature and the heat flow of the exotherms were affected by the molecular weight of the homopolymers. The strain‐induced crystallization of the MQ series suggested the independent crystallization of PET and PEN. Based on the results, a microdomain structure of each homopolymer was suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2428–2438, 2005     

Holographic recording in a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various polarizations

Surface relief (SR) gratings with a molecularly oriented structure and pure polarization hologram were fabricated on a photo-cross-linkable liquid crystalline copolymer using a 325-nm laser with various two-beam polarization modes. For intensity holography, the polarization information from the two beams simultaneously provided the molecular motion and molecular reorientation; the SR height reached up to 186 nm and the concave area revealed a molecular reorientation when the exposing beams were linearly polarized. In contrast, SR formation was negligible for polarization holography when molecular reorientation due to the polarization modulation was observed. The resulting polarization gratings changed the polarization properties of the diffraction beams, and their diffraction efficiency was reached 24%, which agreed with theoretical expectations.     

Molecular reorientation behavior of photocrosslinkable liquid-crystalline polymer films containing phenylamide side chains

The cooperative molecular reorientation in methacrylate copolymer films comprising photoreactive 4-(4-methoxycinnamoyloxy)biphenyl and phenylamide in their side chains was investigated by irradiation with linearly polarized ultraviolet light and subsequent annealing. Both cinnamate and phenylamide side groups were miscible in the copolymer composition, and axis-selective photoreaction of the cinnamate groups was observed. Thermally enhanced cooperative in-plane orientation of both side groups was obtained when the irradiated films were annealed in the liquid-crystalline temperature range of the copolymers.     

Mapping Nanomechanical Properties of Basal Surfaces in Metastatic Intestinal 3D Living Organoids with High-Speed Scanning Ion Conductance Microscopy

Studying mechanobiology is increasing of scientific interests in life science and nanotechnology since its impact on cell activities (e.g., adhesion, migration), physiology, and pathology. The role of apical surface (AS) and basal surface (BS) of cells played in mechanobiology is significant. The mechanical mapping and analysis of cells mainly focus on AS while little is known about BS. Here, high-speed scanning ion conductance microscope as a powerful tool is utilized to simultaneously reveal morphologies and local elastic modulus (E) of BS of genotype-defined metastatic intestinal organoids. A simple method is developed to prepare organoid samples allowing for long-term BS imaging. The multiple nano/microstructures, i.e., ridge-like, stress-fiber, and E distributions on BS are dynamically revealed. The statistic E analysis shows softness of BS derived from eight types of organoids following a ranking: malignant tumor cells > benign tumor cells > normal cells. Moreover, the correlation factor between morphology and E is demonstrated depending on cell types. This work as first example reveals the subcellular morphologies and E distributions of BS of cells. The results would provide a clue for correlating genotype of 3D cells to malignant phenotype reflected by E and offering a promising strategy for early-stage diagnosis of cancer.     

Absolute flatness measurements of silicon mirrors by a three-intersection method by near-infrared interferometry

Absolute flatness of three silicon plane mirrors have been measured by a three-intersection method based on the three-flat method using a near-infrared interferometer. The interferometer was constructed using a near-infrared laser diode with a 1,310-nm wavelength light where the silicon plane mirror is transparent. The height differences at the coordinate values between the absolute line profiles by the three-intersection method have been evaluated. The height differences of the three flats were 4.5 nm or less. The three-intersection method using the near-infrared interferometer was useful for measuring the absolute flatness of the silicon plane mirrors.