Journal Article Isolation of Tremerogen a-13, a Peptidal Sex Hormone of Tremella mesenterica Get access Mitsuru Yoshida, Mitsuru Yoshida Department of Agricultural Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan Search for other works by this author on: Oxford Academic Google Scholar Youji Sakagami, Youji Sakagami Department of Agricultural Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan Search for other works by this author on: Oxford Academic Google Scholar Akira Isogai, Akira Isogai Department of Agricultural Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan Search for other works by this author on: Oxford Academic Google Scholar Akinori Suzuki Akinori Suzuki Department of Agricultural Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 45, Issue 4, 1 April 1981, Pages 1043–1044, https://doi.org/10.1080/00021369.1981.10864654 Published: 01 April 1981 Article history Received: 06 February 1981 Published: 01 April 1981
Mechanisms of paper sizing by reactive sizes such as alkylketene dimers (AKD), alkenylsuccinic anhydrides (ASA) and fatty acid anhydrides (FAA) arc reviewed on the basis of the results obtained in our laboratory. Solid-state ¹ ³C-NMR analysis of cellulase-treated residues of handsheets prepared with ¹ ³C-labeled sizes showed that the size components are present primarily as hydrolyzed products, without forming covalent bonds with hydroxyl groups of cellulose in the handsheets. Furthermore, most size components in handsheets were removed by stirring the defibrated handsheets in water with Tween 80 at 70℃ for 4 h. Thus, the hydrolyzed products of size molecules consequently contribute to sizing performance for the reactive size-treated papers. Scanning electron microscopic observations revealed that the chemical structures of reactive sizes are necessary for efficient paper sizing to achieve homogenous distribution of hydrophobic size components on hydrophilic pulp fiber surfaces in the papermaking process, where water is always present. Size reversion is presumably explained in terms of partial introduction of hydrophilic groups into the size molecules by auto-oxidation. Therefore, mechanisms of paper sizing by reactive sizes can be rationalized, without introducing the covalent bond formations. by changes in chemical structures of the size molecules from hydrophilic to hydrophobic by hydrolysis in papermaking process. Model experiments using a cellulose-AKD ester sample also supported these mechanisms.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Adsorption behavior of aluminum compounds on pulp fibers at the wet-end was studied in terms of structures of aluminum components using some analytical techniques. Fibrous cellulose powder (CF) and fibrous carboxymethylcellulose powder (FCMC) were used as models of pulp fibers. When de-ionized water was used, aluminum components originating from alum added to cellulose suspensions were adsorbed on FCMC, probably forming carboxyl group aluminum salts. On the other hand, no interactions occurred between hydroxyl groups of cellulose and aluminum components in the suspensions. Analysis of adsorption behavior of cationic aluminum species on cellulosic fibers using solution-state ^27AI-showed that any cationic aluminum species such as AI^3+, AI_13.met^+7 and aluminum polymers were adsorbed on FCMC. Again no interactions were recognized between such cationic aluminum species and hydroxyl groups of cellulose in the ^27AI-NMR study. Thus, adsorption and retention behavior of aluminum compounds in paper is greatly influenced by carboxyl contents of pulp fibers used. Mapping analyses revealed that aluminum components were distributed almost homogeneously in the cross sections of each pulp fiber for the handsheets prepared with 2% aluminum sulfate or 2% polyhydroxyaluminum chloride (PHAC). Thus, water-soluble aluminum species such as AI^3+ ions, AI_13mer^7+' and aluminum polymers can penetrate into the inside pulp fibers during the handsheet-making process.
Sizing behavior of handsheets, which were prepared from thermomechanical pulp (TMP) with alkylketene dimer (AKD), was studied in terms of conditions of the handsheet-making. AKD content in the TMP handsheets increased with increasing the AKD addition level, and the addition of a polyamideamine - epichlorohydrin resin (PAE) clearly enhanced AKD retention as well as the resultant sizing performance. Although drying
of the wet TMP webs at 20℃ led to no or quite low sizing
level, the AKD-sized TMP handsheets had higher sizing degrees with increasing the temperature of heat treatment. Scanning electron microscopic observations of the AKD-sized TMP handsheets showed that AKD emulsion particles were present on pulp fiber surfaces independently without coagulation in the TMP handsheets dried at 20℃. Heat treatment of the AKD-sized hand sheets resulted in disappearance of the AKD emulsion particles by their melting and spreading. The addition of calcium carbonate filler to the TMP suspensions did not influence on AKD content in the TMP handsheets. Nevertheless, their sizing degrees clearly
increased by the addition of CaCO₃) filler. Probably, AKD molecules adsorbed on the CaCO₃) filler particles contribute to the enhancement of sizing performance. Thus, AKD can give sizing features effectively to the TMP hand sheets, when they are made under suitable conditions.
Cotton fabrics were oxidized with TEMPO/NaClO/NaClO2 or 4‐acetamido‐TEMPO/NaClO/NaClO2 system in water at pH 3.8 or 6.8 and 40-80℃ for 0-120 min. As references, cotton fabrics were oxidized with TEMPO/NaBr/NaClO system in water at pH 10 and room temperature for 0-45 min. In all cases, the higher the carboxylate content of the oxidized cotton fabric, the lower its viscosity‐average degree of polymerization (DPv). However, the oxidation at pH 3.8 and 6.8 gave cotton fabrics with higher DPv values at carboxylate contents > 0.3 mmol/g, compared to those prepared at pH 10. When the cotton fabrics oxidized with 4‐acetamido‐TEMPO/NaClO/NaClO2 system in water at pH 3.8 or 6.8 were heated at 105℃ for 2 h, clear whiteness reductions were observed, a part of which may have been caused by thermal degradation of 4‐acetamido‐TEMPO‐related compounds physically adsorbing on the oxidized cotton fabrics and slightly remaining in them even after repeated washing with water. When ethylene glycol, gluconic acid or glucose was directly added to the aqueous solution containing the cotton fabric after the oxidation, the oxidized cotton fabrics had relatively low whiteness reduction and low bending resistance (or better softness for clothes) even after heating at 105℃ for 2 h. Thus, the TEMPO‐ or 4‐acetamido‐TEMPO‐mediated oxidation in water at pH 3.8 or 6.8 may be applicable to chemical modification of cotton fabrics to be used as clothes for functionalized underwear.
