As the most important skeletal component in plants, the polysaccharide cellulose is an almost inexhaustible polymeric raw material with fascinating structure and properties. Formed by the repeated connection of D-glucose building blocks, the highly functionalized, linear stiff-chain homopolymer is characterized by its hydrophilicity, chirality, biodegradability, broad chemical modifying capacity, and its formation of versatile semicrystalline fiber morphologies. In view of the considerable increase in interdisciplinary cellulose research and product development over the past decade worldwide, this paper assembles the current knowledge in the structure and chemistry of cellulose, and in the development of innovative cellulose esters and ethers for coatings, films, membranes, building materials, drilling techniques, pharmaceuticals, and foodstuffs. New frontiers, including environmentally friendly cellulose fiber technologies, bacterial cellulose biomaterials, and in-vitro syntheses of cellulose are highlighted together with future aims, strategies, and perspectives of cellulose research and its applications.

Cellulose: Fascinating Biopolymer and Sustainable Raw Material

4.3. Reaction Mechanism 2373 4.4. Asymmetric Synthesis 2374 4.5. Outlook 2374 5. Alternating Polymerization of Oxiranes and CO2 2374 5.1. Reaction Outlines 2374 5.2. Catalyst 2376 5.3. Asymmetric Polymerization 2377 5.4. Immobilized Catalysts 2377 6. Synthesis of Urea and Urethane Derivatives 2378 7. Synthesis of Carboxylic Acid 2379 8. Synthesis of Esters and Lactones 2380 9. Synthesis of Isocyanates 2382 10. Hydrogenation and Hydroformylation, and Alcohol Homologation 2382

Transformation of carbon dioxide.

Nanostructured materials: basic concepts and microstructure☆

Layered double hydroxides (LDHs) are a class of ionic lamellar compounds made up of positively charged brucite-like layers with an interlayer region containing charge compensating anions and solvation molecules. Delamination of LDHs is an interesting route for producing positively charged thin platelets with a thickness of a few atomic layers, which can be used as nanocomposites for polymers or as building units for making new designed organic-inorganic or inorganic-inorganic nanomaterials. The synthesis of nanosized LDH platelets can be generally classified into two approaches, bottom-up and top-down. It requires modification of the LDH interlamellar environment and then selection of an appropriate solvent system. In DDS intercalated LDHs, the aliphatic tails of the DDS- anions exhibit a high degree of interdigitation in order to maximize guest-guest dispersive interactions. Bellezza reported that the LDH colloids can also been obtained by employing a reverse microemulsion approach.

Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets.

Regional differences in species number have puzzled naturalists ince the early 1800's, and explanations account for a large part of modern ecological research. Two venerable observations form the cornerstone of our knowledge on the subject: The number of species within a taxonomic group tends to increase with decreasing latitude (see Fischer 1960; Pianka 1966); and the number of species within a taxonomic group tends to increase with increasing area (see Preston 1960, 1962; Williams 1964; MacArthur and Wilson 1967; Simberloff 1972). Despite early research on the latter trend (the species-area relationship), ecologists have studied it intensely only in the last 50 yr. The relationship was originally envisioned as an empirical tool and used in three principle ways: (1) to determine optimal sample size and sample number, (2) to determine the minimum area of a \"community,\" and (3) to predict the number of species in areas larger than those sampled. All three uses are discussed by Kilburn (1966). More recently interest in the species-area relationship has focused on mechanistic explanations, its precise mathematical descriptions, and interpretations of parameters derived from these mathematical descriptions. Williams (1964) and Preston (1960, 1962) have proposed that the exponential and power function models (\"exponential model\" throughout his paper also refers to the species/log area transformation, and \"power function\" also refers to the log species/log area transformation) of the species-area relationship result from the way in which individuals are distributed among species. Williams' (1964) exponential model, which emphasizes habitat heterogeneity, was considered important by many plant ecologists but is now largely ignored. Preston's (1960, 1962) power function model was based on the assumption of a dynamic equilibrium of species exchanges between islands in an archipelago. This assumption led to the equation of the power function model with the idea of a dynamic equilibrium as expounded by MacArthur and Wilson (1963, 1967), such that an adequate fit of this model to observed species numbers has been viewed as support of the equilibrium hypothesis (Grant 1970; Diamond 1973; Simpson 1974). The interplay of the equilibrium hypothesis and the power function model of the species-area relationship has led to interpretation of the slope and intercept of the power function model exclusively in the context of the equilibrium hypothesis. In particular, specific values of the slope of the power function are often construed to * Order of authorship determined by the toss of a coin. t Present address: Department of Biology, University of South Florida, Tampa, Florida 33620. Am. Nat. 1979. Vol. 113, pp. 791-833. c) 1979 by The University of Chicago. 0003-0147/79/1306-0002$03.26

/pdf/the-statistics-and-biology-of-the-species-area-relationship-442cynzyis.pdf

The statistics and biology of the species-area relationship

Polymerization via Zwitterion. 12. Novel 1:1:1 Alternating Terpolymerizations of 2-Phenyl-1,3,2-dioxaphospholane, Electron Deficient Vinyl Monomers of Acrylonitrile and Acrylate, and Carbon Dioxide

Injectable thermoreversible hydrogels based on amphiphilic poly(amino acid)s

Group IB and IIB metal compounds catalyze the reaction of isocyanides (1) with amines (2) producing formamidines (3). In the reaction of cyclohexyl isocyanide with piperidine, the accelerating effect of catalyst was in the order AgCl>CuCl>>ZnCl2, Cd(OAc)2, HAuCl4·4H2O. The AgCl catalyzed reaction proceeded almost quantitatively in 2.5 hr at 17°C. The reaction of aliphatic isocyanide with aromatic amine, e.g., N-methylaniline, required higher reaction temperatures (160°C) even in the presence of catalyst, in which the order of catalytic activity was HAuCl4·4H2O>ZnCl2>AgCl>>CuCl. A ternary complex of (CuCl)2 (cyclohexyl isocyanide)2 (piperidine) was isolated, which was unstable and decomposed gradually at room temperature to give N-cyclohexyl-N,N′-pentamethylene formamidine. A mechanism through a mixed ligand complex has been proposed, in which both isocyanide and amine are coordinated with the same metal ion and the reaction takes place in the sphere of complex ligand.

Synthetic Reactions by Complex Catalysts. XIV. Reaction of Isocyanide with Amine Catalyzed by Group IB and IIB Metal Compounds

Enzymatic oxidative polymerization of bisphenol-A was carried out in an aqueous organic solvent using horseradish and soybean peroxidases (HRP and SBP, respectively) as catalysts. The SBP-catalyzed polymerization in an equivolume mixture of methanol and phosphate buffer (pH 7.0) affords a new class of polyphenol quantitatively, which is readily soluble in polar organic solvents such as acetone, methanol, N,N-dimethylformamide, and dimethyl sulfoxide, but insoluble in chloroform, diethyl ether, and water. NMR and IR analyses show that the polymer is mainly composed of a mixture of phenylene and oxyphenylene units. The effects of the type of enzyme and the solvent composition were systematically investigated in respect to the yield and molecular weight of the polymer. The thermal treatment of the polymer produces an insoluble product and the curing temperature and the molecular weight of the starting polymer affect the thermal properties of the product. Crosslinking reaction of the present polyphenol with an epoxide resin affords insoluble polymeric material showing high thermal stability.

Enzymatic oxidative polymerization of bisphenol: A to a new class of soluble polyphenol

Micron-size monodisperse poly(methyl methacrylate) (PMMA) particles were prepared by dispersion copolymerization of MMA with a hydrophilic poly(2-oxazoline) macromonomer in an aqueous methanol solution. The macromonomer acted as a comonomer as well as a stabilizer. As the macromonomer concentration increased, the diameter of the particles decreased. The macromonomer with higher molecular weight, or with more hydrophilic nature, stabilized the particles more effectively. The diameter of the particles was dependent on the initiator concentration

Shiro Kobayashi

Papers

Polymerization via Zwitterion. 12. Novel 1:1:1 Alternating Terpolymerizations of 2-Phenyl-1,3,2-dioxaphospholane, Electron Deficient Vinyl Monomers of Acrylonitrile and Acrylate, and Carbon Dioxide

Injectable thermoreversible hydrogels based on amphiphilic poly(amino acid)s

Synthetic Reactions by Complex Catalysts. XIV. Reaction of Isocyanide with Amine Catalyzed by Group IB and IIB Metal Compounds

Enzymatic oxidative polymerization of bisphenol: A to a new class of soluble polyphenol

Preparation of micron‐size monodisperse poly(methyl methacrylate) particles using poly(2‐oxazoline) macromonomer