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This study aimed to use the organic polymer, chitosan, as a flocculant for harvesting microalgae Chlorella. sp. Various polymer concentrations were tested. Within three min, 50 mg/L of chitosan showed the highest efficiency (98.9±0.5%), at pH 6.3, while the lowest efficiency (86.7±0.5%) was observed at pH 7.5. Harvesting efficiency in this study was chitosan concentration dependent. The present study showed that chitosan can be a promising and sustainable solution as an organic source and environmentally friendly flocculant. Additionally, it has excellent harvest productivity and requires minimum effort for quick outcomes. [ABSTRACT FROM AUTHOR]

Polysaccharides from Zizyphus jujube cv. Muzao (ZMP) were extracted by ultrasonic-assisted extraction with acidic buffer. The chemical composition and antioxidant and anti-inflammatory activities of ZMP were evaluated. The results revealed that ZMP had a molecular weight of 89.90 kDa and consisted of arabinose, galactose, glucose, rhamnose, and mannose, with molar percentages of 4.52 %, 2.64 %, 1.04 %, 0.49 %, and 0.41 %, respectively. Based on Fourier-transform infrared spectroscopy, ZMP belonged to the type I rhamnogalacturonans family. In vitro antioxidants assays revealed that ZMP had remarkable antioxidant activity in a dose-dependent manner. Proinflammatory cytokines, such as interleukin-6 and tumor necrosis factor alpha, were suppressed by ZMP in lipopolysaccharide-treated RAW264.7 cells. Overall, the results revealed that ZMP has potential applications as a natural anti-inflammatory agent. [ABSTRACT FROM AUTHOR]

The coagulation or flocculation of cohesive clay suspensions is one of the most widely used treatment technologies for contaminated water. Flocculated clay can transport pollutants and nutrients in ground water. Coagulants are used to accelerate these mechanisms. However, existing coagulants (e.g., polyacrylamide, polyaluminum chloride) are known to have harmful effects in the environment and on human health. As an alternative, eco-friendly coagulant, this study suggests ε-polylysine, a cationic biopolymer fermented by Streptomyces. A series of sedimentation experiments for various ε-polylysine concentrations were performed, and tire efficiency of sedimentation with ε-polylysine was estimated by microscopic observation and light absorbance measurements. Two types of sedimentation were observed in the experiments: accumulation sedimentation (at 0.15%, 0.20%, 0.25% ε-polylysine) and flocculation sedimentation (at 0%, 0.1%, 0.5%, 1.0%, 2.0% ε-polylysine). These sedimentation types occur as a result of the concentration of counter ions. Additionally, the performance of ε-polylysine was compared with that of a previously used environmentally friendly coagulant, chitosan. The obtained results indicate that flocculation sedimentation is appropriate for contamination removal and that e-polylysine functions more efficiently for clay removal than chitosan. From the experiments and analysis, this paper finds that polylysine is an alternative eco-friendly coagulant for removing chemical contaminants in groundwater. [ABSTRACT FROM AUTHOR]

Indentation has been widely used to characterize the mechanical properties of biopolymers. Besides Hertzian solution, Sneddon's solution is frequently adopted to interpret the indentation data to deduce the elastic properties of biopolymers, e.g., elastic modulus. Sneddon s solution also forms the basis to develop viscoelastic contact models for determining the viscoelastic properties of materials from either conical or flat punch indentation responses. It is worth mentioning that the Sneddon's solution was originally proposed on the basis of linear elastic contact theory. However, in both conical and flat punch indentation of compliant materials, the indented solid may undergo finite deformation. In this case, the extent to which the Sneddon's solution is applicable so far has not been systematically investigated. In this paper, we use the combined theoretical, computational, and experimental efforts to investigate the indentation of hyperelastic compliant materials with aflat punch or a conical tip. The applicability of Sneddon's solutions is examined. Furthermore, we present new models to determine the elastic properties of nonlinear elastic biopolymers. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the special issue on topics including the preparation, synthesis, and characterization of biopolymers.