Long-chain anhydride modification: a new strategy for preparing xylan films.

Xylan, which is a widely abundant plant polymer, has been considered as an alternative for film preparation. Up to now, however, xylan films have suffered from brittleness, low mechanical strength, and humidity sensitivity. This paper describes a new and effective strategy to prepare xylan films with high mechanical strength and less moisture-sensitive properties by introducing long carbon chains into the xylan backbone.

Adsorption of heavy metals by a porous bioadsorbent from lignocellulosic biomass reconstructed in an ionic liquid.

A novel porous bioadsorbent for metal ion binding (Pd(2+) and Cd(2+)) was successfully prepared from lignocellulosic biomass in ionic liquid by homogeneous succinoylation and sequent chemical cross-linking. The morphology of the bioadsorbent and the interaction between bioadsorbent and metal ions was revealed by scanning electron microscopy and Fourier transform infrared spectroscopy. Results showed that the adsorption mechanism of the bioadsorbent was an ion exchange.

Highly effective adsorption of heavy metal ions from aqueous solutions by macroporous xylan-rich hemicelluloses-based hydrogel.

Xylan-rich hemicelluloses-based hydrogel was developed as a novel porous bioadsorbent by graft co-polymerization of acrylic acid (AA) and xylan-rich hemicelluloses for adsorption of heavy metal ions (Pd(2+), Cd(2+), and Zn(2+)) from aqueous solutions. The chemical structure, the interaction between the hydrogel and metal ions, and the porous structure of xylan-rich hemicelluloses-g-AA hydrogel were revealed by Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of AA and cross-linker dosage, pH value, contacting time, and initial concentration of metal ion on the adsorption capacity were studied.

Synthesis and characterization of amphoteric xylan-type hemicelluloses by microwave irradiation.

In this study, a novel amphoteric macromolecule was synthesized by sequential incorporation of carboxymethyl and quaternary ammonium groups into the backbone of xylan-type hemicelluloses under microwave irradiation. The reaction parameters such as the molar ratio of reagent (NaOH or 3-epoxypropyltrimethylammonium chloride)/anhydroxylose unit in hemicelluloses, the temperature, and the reaction time were investigated to optimize the reaction condition. The maximum degrees of substitution (DS) of carboxymethyl and quaternary ammonium groups under the optimum reaction condition were 0.

Nanocomposite films based on xylan-rich hemicelluloses and cellulose nanofibers with enhanced mechanical properties.

Interest in xylan-rich hemicelluloses (XH) film is growing, and efforts have been made to prepare XH films with improved mechanical properties. This work described an effective approach to produce nanocomposite films with enhanced mechanical properties by incorporation of cellulose nanofibers (CNFs) into XH. Aqueous dispersions of XH (64-75 wt %), sorbitol (16-25 wt %), and CNF (0-20 wt %) were cast at a temperature of 23 °C and 50% relative humidity.

Xylan-rich hemicelluloses-graft-acrylic acid ionic hydrogels with rapid responses to pH, salt, and organic solvents.

Exploitation of biomaterials derived from renewable resources is an important approach to address environmental and resource problems in the world today. In this paper, novel ionic hydrogels based on xylan-rich hemicelluloses were prepared by free radical graft copolymerization of acrylic acid (AA) and xylan-rich hemicelluloses (XH) by using N,N-methylene-bis(acrylamide) (MBA) as cross-linker and ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TMEDA) as redox initiator system. The network characteristics of the ionic hydrogels were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), as well as by determination of mechanical properties, swelling, and stimuli responses to pH, salts, and organic solvents.

Microwave-induced synthesis of carboxymethyl hemicelluloses and their rheological properties.

In this article, a facile, rapid, and efficient method was developed for the preparation of carboxymethyl hemicelluloses using microwave-induced organic reaction enhancement chemistry. The influences of the factors including reaction time, temperature, and the amount of sodium monochloroacetate and sodium hydroxide on the degree of substitution (DS) of the products were investigated. The rheological properties and the chemical structure of the resulting polymers were also studied.

Identification of a potent and highly efficacious, yet slowly desensitizing CB1 cannabinoid receptor agonist.

1 The relationship of agonist efficacy to the rate of G protein-coupled receptor signaling desensitization is controversial. 2 Expressing inwardly rectifying potassium channels (GIRKs) in Xenopus oocytes, we have devised a signaling assay that clearly identifies CB1 cannabinoid receptor agonists with low intrinsic efficacy. 3 In this assay, the synthetic CB1 agonists, AM411, AM782, AM1902, AM2233 and WIN55,212-2 and the endogenous cannabinoid, 2-arachidonoyl ester, were full agonists.