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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]

This research was set out to explore the development of arrowroot starch (AS) films using glycerol (G) as plasticizer at the ratio of 15, 30, and 45% (w/w, starch basis) using solution casting technique. The developed films were analyzed in terms of physical, structural, mechanical, thermal, environmental, and barrier properties. The incorporation of glycerol to AS film-making solution reduced the brittleness and fragility of films. An increment in glycerol concentration caused an increment in film thickness, moisture content, and solubility in water, whereas density and water absorption were reduced. The tensile strength and modulus of G-plasticized AS films were reduced significantly from 9.34 to 1.95 MPa and 620.79 to 36.08 MPa, respectively, while elongation at break was enhanced from 2.41 to 57.33%. FTIR analysis revealed that intermolecular hydrogen bonding occurred between glycerol and AS in plasticized films compared to control films. The G-plasticized films showed higher thermal stability than control films. The cross-sectional micrographs revealed that the films containing 45% glycerol concentration had higher homogeneity than 15% and 30%. Water vapour permeability of plasticized films increased by an increase in glycerol concentrations. The findings of this research provide insights into the development of bio-degradable food packaging. [ABSTRACT FROM AUTHOR]

Abstract The present study focuses on biopolymer surface modification of cp-Titanium with Chitosan, Gelatin, and Sodium Alginate. The biopolymers were spin coated onto a cp-Titanium substrate and further subjected to Electrochemical Impedance Spectroscopic (EIS) characterization. Artificial Neural Network (ANN) was developed to predict the Open Circuit Potential (OCP) values and Nyquist plot for bare and biopolymer coated cp-Titanium substrate. The experimental data obtained was utilized for ANN training. Two input parameters, i.e., substrate condition (coated or uncoated) and time period were considered to predict the OCP values. Backpropagation Levenberg-Marquardt training algorithm was utilized in order to train ANN and to fit the model. For Nyquist plot, the network was trained to predict the imaginary impedance based on real impedance as a function of immersion periods using the Back Propagation Bayesian algorithm. The biopolymer coated cp-Titanium substrate shows the enhanced corrosion resistance compared to uncoated substrates. The ANN model exhibits excellent comparison with the experimental results in both the cases indicating that the developed model is very accurate and efficiently predicts the OCP values and Nyquist plot. Graphical abstract Unlabelled Image Highlights • The present study focuses on evaluation of corrosion behaviour of uncoated and biopolymer coated commercially pure (CP) Ti. • Three biopolymers, i.e. , Chitosan, Gelatin B and Sodium Alginate were coated via. spin coating technique. • Open Circuit Potential (OCP) and Electrochemical Impedance spectroscopy (EIS) studies were carried out for corrosion evaluation. • Artificial Neural Network (ANN) modeling is carried out to predict OCP values and Nyquist plots. • The present ANN model can be used to predict OCP values and Nyquist plots accurately. [ABSTRACT FROM AUTHOR]

Abstract: Detection of traces from pharmaceutical drugs such as antibiotics in drinking water and foodstuff is essential for guaranteeing human health in some environments, and this has to be done with low cost technologies to be widely deployed in public services and industry. In this paper, we describe an ultralow cost (

With the widespread application of liquid chromatography with organic carbon detection (LC-OCD) to investigate membrane fouling in low-pressure membranes such as microfiltration (MF) and ultrafiltration (UF), membrane fouling by macromolecular hydrophilic biopolymer fraction has been recognized. In this study, a drinking water source was intensively investigated over 16 months. Membrane filtration using hollow-fiber MF membranes was carried out in constant flux mode with periodic backwashing, and two pretreatments (aluminum coagulation and anion exchange) were examined in terms of biopolymer removal and fouling mitigation. Higher biopolymer removal rates achieved by anion exchange than coagulation did not cause better control of membrane fouling in MF. Coagulation and anion exchange removed different types of biopolymers, which implied diversity in the biopolymer fraction. A modified set-up of LC-OCD analysis in which two different columns were sequentially connected was examined. It was demonstrated that the biopolymer fraction detected as a single peak with molecular weight of > 10,000 Da with the conventional LC-OCD set-up comprised of molecules with a variety of molecular weights including > 1,000,000 Da. It was found that coagulation removed large-size biopolymers with higher fouling potentials; while anion exchange preferentially removed small-size biopolymers with lower fouling potential. Concentration of large-size biopolymers in the feed water collected on different dates correlated with the degree of membrane fouling. In an attempt to generalize the conclusion drawn from the experiments using the specific drinking water source, batch MF tests filtering biopolymers isolated from different drinking water sources were also carried out. Importance of the large-size biopolymer fraction in the evolution of membrane fouling was also suggested with different drinking water sources. [ABSTRACT FROM AUTHOR]

In this paper, the effect of alkali activator to binder (AAB) ratio and molarity of alkaline activator on the rice husk ash based geopolymer were investigated. Compressive strength has been determined on 70.6 × 70.6 × 70.6 mm specimens by varying AAB ratio from 0.5 to 0.7 and molarity of alkali activator solution from 12 M to 16 M. The microstructure was also examined using scanning electron microscope (SEM). Experimental results revealed that the maximum compressive strength is obtained up to 39.95 N/mm 2 after 28 days. It has been observed that compressive strength is directly proportional to both AAB ratio and molarity of alkali activator solution. With increasing the molarity, microstructure become quite dense, this may be attributed to high degree of geopolymerisation. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of the total biopolymer (egg white protein - EW and hydroxypropylmethylcellulose – HPMC) concentration (1.4–5.6 g/100 g of sugar) and EW/HPMC ratio (2/1 to 18/1 g/g) on the apparent viscosity before whipping, foaming capacity (density and overrun) and foam rheological properties (G’, G” and δ) of sugar/EW/HPMC mixtures using a central composite rotatable design (CCRD). The conditions to obtain intermediate apparent viscosity, high foaming capacity, elastic and solid behaviour were total biopolymer concentration 5.0 g/100 g of sugar and EW/HPMC ratio 14/1 (g/g). Under these conditions, experiments were carried out to evaluate the effect of interactions between EW and HPMC at pH 3.0, 4.5 and 6.0 on the foaming and rheological properties. The greatest foaming capacity, elastic and solid behaviour, with no liquid drainage, were obtained at pH 3.0. At pH 4.5, foams possessed monodisperse bubble size distribution and viscoelastic behaviour, leading to better stability with respect to disproportionation and coalescence compared to foams at pH 3.0. At pH 6.0, foam showed the poorest foaming properties and viscous behaviour. The interactions between EW and HPMC in aerated confectionery at different pH affect foaming and rheological properties. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) and ciprofloxacin-degrading microbial community in the combined Fe-C micro-electrolysis and up-flow biological aerated filter (UBAF) process for the treatment of high-level ciprofloxacin (CIP) were analyzed. The research demonstrated a great potential of Fe-C micro-electrolysis-UBAF for the elimination of high-level CIP. Above 90% of CIP removal was achieved through the combined process at 100 mg L −1 of CIP loading. In UBAF, the pollutants were mainly removed at 0–70 cm heights. Three-dimensional fluorescence spectrum (3D-EEM) was used to characterize the chemical structural of loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) extracted from biofilm sample in UBAF. The results showed that the protein-like substances in LB-EPS and TB-EPS had no clear change in the study. Nevertheless, an obvious release of polysaccharides in EPSs was observed during long-term exposure to CIP, which was considered as a protective response of microbial to CIP toxic. The high-throughput sequencing results revealed that the biodiversity of bacteria community became increasingly rich with gradual ciprofloxacin biodegradation in UBAF. The ciprofloxacin-degrading microbial community was mainly dominated by Proteobacteria and Bacteroidetes . Microorganisms from genera Dechloromonas , Brevundimonas , Flavobacterium , Sphingopyxis and Bosea might take a major role in ciprofloxacin degradation. This study provides deep theoretical guidance for real CIP wastewater treatment. [ABSTRACT FROM AUTHOR]

In current study, starch/TiO 2 bionanocomposites were produced by photochemical reactions as a biodegradable food packaging material. Physical, mechanical, thermal and water-vapor permeability properties were investigated. Then, the photo-degradation properties of nanocomposite films were studied. This is the first report of the photo-producible and photo-degradable bionanocomposite as a food packaging material. Film-forming solutions were exposed to ultraviolet A (UV-A) for different times. Our results showed that UV-A irradiation increased the hydrophobicity of starch films. With increasing UV-A exposure time, tensile strength and Young’s modulus of the specimens were decreased. On the other hand, elongation at break of the films was increased with increasing UV-A irradiation. The glass transition temperature and melting point of the films were increased by increasing UV-A exposure time. Nevertheless, the results showed that photo-degradation properties of photo-produced starch/TiO 2 nanocomposite were significantly higher than virgin starch and virgin starch/TiO 2 films. According to obtain results and bibliography a schema was developed to describe the mechanism of photo-production and photo-degradation of starch/TiO 2 by UV-A ray. It can be concluded, the modification of starch based biopolymer by UV-A and nano-TiO 2 , is an easy and accessible process to improve the packaging properties and photo-degradability of biopolymer based films. [ABSTRACT FROM AUTHOR]

The aim of this study is focused on the elaboration of new bio-based alumina concentrated suspensions with rheological properties adapted to the tape casting process and with low environmental impact. Natural polymers extracted from plants were identified as promising candidates in order to substitute the classical organic additives. The aqueous suspensions were prepared from bio-polymer additives. The interactions between different organic additives with alumina were characterized by zeta-potential and quartz crystal microbalance measurements. The influence of the incorporation order of the different organic additives on the viscosity of the suspension was evaluated. Then, mechanical properties of the green and sintered tapes were determined in relation with the nature of bio-polymer additives. [ABSTRACT FROM AUTHOR]

Algal extracellular and intracellular polymeric substances (EPS and IPS) are widely applied in fields such as food, cosmetics, and wastewater treatment. Algal IPS content was much higher than EPS and thus extracting IPS from algal biomass may greatly improve the commercial value of algal cultivation. This study was to provide a basis for development of algal IPS by comparing composition of algal IPS and EPS. EPS and IPS produced by Scenedesmus and Microcystis, which commonly dominates the freshwater ecosystems, were analyzed using fluorescence excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). The IPS concentration of Scenedesmus obliquus and Microcystis aeruginosa was 1.2 to 2.1 times higher than EPS concentration. The maximum EPS concentration was 145.7 mg C/L but the maximum IPS concentration reached 206.1 mg C/L. Seven components including five humic-like components (C1, C2, C3, C4, and C7) and two tryptophan-like component (C5 and C6) were identified by EEM-PARAFAC. All seven components identified in the current study were considered effective in removing heavy metals. Therefore, IPS of M. aeruginosa would be potential polymeric substances for environmental biotechnology. [ABSTRACT FROM AUTHOR]

Development of bioactive hydrogel as extracellular matrix (ECM) is a very important field for cell-based therapy. In this study, we provided a facile method based on sol-gel process for fabricating bioactive composite hydrogels. The composite hydrogels were composed of sol-gel derived silica and biopolymer. Different amounts of silica solution (20–80 wt%) were mixed with 2% polymer sol (alginate) followed by aging and gelation to form a network so that the alginate-silica hybrid mixture could form a gel without any additional crosslinking process. The self-gelation time of the hybrid hydrogel measured by rheometer was reduced as the content of silica was increased. Such hydrogels had highly porous and interconnected structures. Their strut showed uniform surface texture. Under physiological conditions (PBS, 37 °C), these hybrid hydrogels exhibited long-term stability compared to alginate hydrogels as control. The mechanical properties of these hydrogels such as compressive strength, compressive modulus, and work of fracture were significantly enhanced by hybridization with sol-gel derived silica. In vitro cell tests revealed that these hybrid hydrogels exhibited improved cell adhesion and proliferation behaviors compared to pure alginate hydrogel cross-linked by CaCl 2 solution. Furthermore, cell encapsulation within these hydrogels revealed that their alginate-silica composite provided suitable microenvironment for cell survival. [ABSTRACT FROM AUTHOR]

This article focuses on the valorization of marine sediments (MS) in proteinic biopolymer (HE) that will generate HEMS biocomposites. These biocomposites were developed with various percentages of marine sediments (0%, 5%, 15%, and 20%) and characterized. Mechanical properties were examined as a function of the contents of used marine sediments. The flexural and compressive modulus increase with the rise of the MS percentage in the composite. The compressive strength increases while the flexural and tensile strengths decrease. Furthermore, the HEMS composite was characterized using Fourier transform infrared spectroscopy and by using scanning electron microscopy. And the thermal degradation behavior of the composite was investigated by thermogravimetric analysis coupled with differential scanning calorimetry. POLYM. COMPOS., 38:1624-1630, 2017. © 2015 Society of Plastics Engineers [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]

This study investigated the effects of pH, salinity, biomass concentration, and algal organic matter (AOM) on the efficiency of four commercial cationic flocculants. The tannin-based biopolymers Tanfloc SG and SL and the polyacrylamide polymers Flopam FO 4800 SH and FO 4990 SH were tested for flocculation of two microalgae models, the freshwater Chlorella vulgaris and the marine Nannochloropsis oculata. Both biomass concentration and AOM presence affected all polymers evaluated, whereas salinity and pH affected only Flopam and Tanfloc, respectively. A restabilization effect due to overdosing was only observed for Flopam polymers and increasing Tanfloc dose resulted in improved efficiency. Flopam polymers showed a significant decrease in the maximum quantum yield of photosystem II as function of polymer dose for Chlorella, which supported the need for toxicological studies to assess the potential toxicity of Flopam. In overall, Tanfloc was not affected by salinity nor presented potential toxicity therefore being recommended for the flocculation of both freshwater and marine species. [ABSTRACT FROM AUTHOR]

Extensive employment of biomaterials in the areas of biomedical and microbiological applications is considered to be of prime importance. As expected, oil based polymer materials were gradually replaced by natural or synthetic biopolymers due to their well-known intrinsic characteristics such as biodegradability, non-toxicity and biocompatibility. Literature on this subject was found to be expanding, especially in the areas of biomedical and microbiological applications. Introduction of porosity into a biomaterial broadens the scope of applications. In addition, increased porosity can have a beneficial effect for the applications which exploit their exceptional ability of loading, retaining and releasing of fluids. Different applications require a unique set of pore characteristics in the biopolymer matrix. Various pore morphologies have different characteristics and contribute different performances to the biopolymer matrix. Fabrication methods for bio-based porous materials more related to the choice of material. By choosing the appropriate combination of fabrication technique and biomaterial employment, one can obtain tunable pore characteristic to fulfill the requirements of desired application. In our previous review, we described the literature related to biopolymers and fabrication techniques of porous materials. This paper we will focus on the biomedical and microbiological applications of bio-based porous materials. [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]

Consumer markets have questioned the use of plastics in packaging because of their environmental impact, and alternative, bio-based films are being developed for this purpose. This study employs Life Cycle Assessment to analyze the environmental and energy performances of producing cassava starch-based film made from casting in Brazil. Results indicate that impacts are mainly caused by the cassava crops, the film manufacture, and the fossil glycerin and ethanol additives used. Resource efficiency and cleaner production measures were devised to reduce the environmental and energy impacts of the product. In terms of energy, an arrangement using both renewable glycerin and biofilm made by extrusion combining cassava starch and polyethylene was shown to be an adequate option to reduce impact. The use of sugarcane ethanol led to an increase in impact for most of the analyzed categories. On the other hand, if the carbon balance considers both carbon dioxide sequestration and biogenic carbon dioxide emissions, the use of renewable alcohol leads to lower impact in Climate Changes. This systemic analysis also allowed for the identification of trade-offs in terms of environmental impacts when considering cultivating and processing cassava in other sites. [ABSTRACT FROM AUTHOR]

Infections continue to spread in all fields of medicine, and especially in the field of implant biomaterial surgery, and not only during the surgery, but also after surgery. Reducing the adhesion of bacteria could decrease the possibility of biomaterial-associated infections. Bacterial adhesion could be reduced by local antibiotic release from the biomaterial. In this in vitro study, hydroxyapatite biomaterials with antibiotics and biodegradable polymers were tested for their ability to reduce bacteria adhesion and biofilm development. This study examined the antibacterial efficiency of hydroxyapatite biomaterials with antibiotics and biodegradable polymers against Staphylococcus epidermidis and Pseudomonas aeruginosa. The study found that hydroxyapatite biomaterials with antibiotics and biodegradable polymers show longer antibacterial properties than hydroxyapatite biomaterials with antibiotics against both bacterial cultures. Therefore, the results of this study demonstrated that biomaterials that are coated with biodegradable polymers release antibiotics from biomaterial samples for a longer period of time and may be useful for reducing bacterial adhesion on orthopedic implants. [ABSTRACT FROM AUTHOR]

Methods of capillary viscometry, spectroscopy, and conductometry were used to investigate the compatibility of components in a biopolymer composite made of polyvinyl alcohol, products of enzymethermal degradation of collagen, and maltodextrin in aqueous solutions. The optimum proportion of maltodextrin ensuring high physicomechanical properties of biopolymer films was determined. [ABSTRACT FROM AUTHOR]

In this paper, the effects of lithium chloride (LiCl) on 1-allyl-3-methylimidazolium chloride (AMIMCl) and cellulose/AMIMCl were studied by steady-state and dynamic rheology experiments. After adding LiCl, a suprastructure may be formed in AMIMCl/LiCl because of fiber drawing and shear-thinning behavior. Moreover, the size of cellulose coil swelled by adding LiCl. In the master curve of cellulose-AMIMCl/LiCl solution, the critical overlap concentration was c = 0.63 and the entangled concentration was c = 2.27 for the entangled regime. Dependence of η on cellulose concentration in cellulose-AMIMCl/LiCl was η ∼ c and c in dilute and semi-dilute untangled regimes, respectively. Therefore, the AMIMCl/LiCl mixture was not a θ solvent for the neutral polymer. The solubility of cellulose decreased and degradation was aggravated after adding LiCl. [ABSTRACT FROM AUTHOR]

In the paper, a comprehensive study of rheological properties of 3% (w/v) Japanese kuzu starch pastes was conducted. To describe the experimental data obtained from oscillatory and creep tests, the new rheological model-which was a modification of the fractional Kelvin-Voigt model-was proposed. The model provided an accurate description of the dynamic data in a range of nearly seven logarithmic decades of oscillation frequency v, with an average error equal to 4.7%. It allowed for a precise determination of 17 rheological parameters of the biopolymer in a function of temperature and time of pasting. These parameters have provided a lot of additional information about structure and viscoelastic properties of the test medium in comparison to the classical analysis of dynamic curves G0 and G00 and shear creep compliance J(t). The study indicated that kuzu starch pastes were viscoelastic polydisperse solids. Rising temperature and time of pasting caused an increase in elastic properties and average molecular weight of the biopolymer. The analysis also showed that the specific pasting conditions, 80°C, 15 min; 95°C, 75 min; and 80°C, 30 min, are particularly important from the point of view of structure and rheological properties of products in food, pharmaceutical, and cosmetics industry, respectively. [ABSTRACT FROM AUTHOR]

Biopolymers are viewed as effective and eco-friendly agents in soil modification. This study focuses on the wettability analysis of polyacrylamide (PAM) solutions for soil remediation. The contact angle, surface tension, and viscosity of PAM solutions were experimentally evaluated in air-and decane-biopolymer solution systems. Furthermore, a micromodel was used to investigate the pore-scale displacement phenomena during the injection of the PAM solution in decane and or air saturated pores. The contact angle of the PAM solution linearly increases with increasing concentration in air but not in decane. The surface tension between the PAM solution and air decreases at increasing concentration. The viscosity of the PAM solution is highly dependent on the concentration of the solution, shear rate, and temperature. Low flow rate and low concentration result in a low displacement ratio level, which is defined as the volume ratio between the injected and the defended fluids in the pores. The displacement ratio is higher for PAM solutions than distilled water; however, a higher concentration does not necessarily guarantees a higher displacement ratio. Soil remediation could be conducted cost-efficiently at high flow rates but with moderate concentration levels. [ABSTRACT FROM AUTHOR]

Polylactide (PLA) is an important biodegradable polymer, used for numerous applications ranging from industrial packaging to tissue engineering. However, its inherent brittleness and limited thermal stability have restricted its penetration to niche markets. In this communication, the authors demonstrate that blending of PLA with castor oil-based polyurethane prepolymer (COPUP), with the addition of COPUP, dispersed in the PLA matrix can overcome the inherent brittleness of the matrix polymer. NCO-terminated COPUP was successfully synthesized and subsequently mixed with variable concentration of PLA matrix using melt blending technique. The interfacial compatibilization between COPUP and PLA phase happened by the reaction of −NCO groups with terminal hydroxyl groups of PLA was confirmed by FT-IR peak deconvolution technique. As indicated by the results of DMA and DSC, the glass transition temperature (Tg) of both PLA and COPUP shifted closer together, indicating that the blend compatibility increased. The tensile properties and notched Izod impact strength of the PLA and toughened PLA are also investigated. With the addition of 30 % COPUP concentration, the elongation at break of the blend reached 377.46 %, and a notched Izod impact 269.62 J m-1. With improved toughness, the PLA/COPUP blends could be used as replacements for some traditional petroleum-based polymers. [ABSTRACT FROM AUTHOR]

Biopolymers are considered a potential alternative to conventional chemical polymers because of their ease of biodegradability, high efficiency, non-toxicity and non-secondary pollution. Recently, extracellular polymeric substances (EPS, biopolymers produced by the microorganisms) have been recognised by many researchers as a potential flocculent for their applications in various water, wastewater and sludge treatment processes. In this context, literature information on EPS is widely dispersed and is very scarce. Thus, this review marginalizes various studies conducted so far about EPS nature-production-recovery, properties, environmental applications and moreover, critically examines future research needs and advanced application prospective of the EPS. One of the most important aspect of chemical composition and structural details of different moieties of EPS in terms of carbohydrates, proteins, extracellular DNA, lipid and surfactants and humic substances are described. These chemical characteristics of EPS in relation to formation and properties of microbial aggregates as well as degradation of EPS in the matrix (biomass, flocs etc) are analyzed. The important engineering properties (based on structural characteristics) such as adsorption, biodegradability, hydrophilicity/hydrophobicity of EPS matrix are also discussed in details. Different aspects of EPS production process such as bacterial strain maintenance; inoculum and factors affecting EPS production were presented. The important factors affecting EPS production include growth phase, carbon and nitrogen sources and their ratio, role of other nutrients (phosphorus, micronutrients/trace elements, and vitamins), impact of pH, temperature, metals, aerobic versus anaerobic conditions and pure and mixed culture. The production of EPS in high concentration with high productivity is essential due to economic reasons. Therefore, the knowledge about all the aspects of EPS production (listed above) is highly essential to formulate a logical and scientific basis for the research and industrial activities. One of the very important issues in the production/application/biodegradation of EPS is how the EPS is extracted from the matrix or a culture broth. Moreover, EPS matrix available in different forms (crude, loosely bound, tightly bound, slime, capsular and purified) can be used as a bioflocculant material. Several chemical and physical methods for the extraction of EPS (crude form or purified form) from different sources have been analyzed and reported. There is ample information available in the literature about various EPS extraction methods. Flocculability, dewaterability and biosorption ability are the very attractive engineering properties of the EPS matrix. Recent information on important aspects of these properties qualitatively as well as quantitatively has been described. Recent information on the mechanism of flocculation mediated by EPS is presented. Potential role of EPS in sludge dewatering and biosorption phenomenon has been discussed in details. Different factors influencing the EPS ability to flocculate and dewaterability of different suspensions have been included. The factors considered for the discussion are cations, different forms of EPS, concentration of EPS, protein and carbohydrate content of EPS, molecular weight of EPS, pH of the suspension, temperature etc. These factors were selected for the study based upon their role in the flocculation and dewatering mechanism as well the most recent available literature findings on these factors. For example, only recently it has been demonstrated that there is an optimum EPS concentration for sludge flocculation/dewatering. High or low concentration of EPS can lead to destabilization of flocs. Role of EPS in environmental applications such as water treatment, wastewater flocculation and settling, colour removal from wastewater, sludge dewatering, metal removal and recovery, removal of toxic organic compounds, landfill leachate treatment, soil remediation and reclamation has been presented based on the most recent available information. However, data available on environmental application of EPS are very limited. Investigations are required for exploring the potential of field applications of EPS. Finally, the limitations in the knowledge gap are outlined and the research needs as well as future perspectives are highlighted. [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]

This paper investigates the enhancement of fly ash-based geopolymer with chitosan biopolymer. Unconfined compression and split tensile tests were carried out to investigate the effect of addition of small amount of N-carboxymethyl chitosan (0.05, 0.1, 0.15, and 0.2 wt% of fly ash) on the mechanical performance of fly ash-based geopolymer. Scanning electron microscopy (SEM) imaging was also conducted to study the microstructure of the chitosan enhanced fly ash-based geopolymer. The results indicated that the inclusion of N-carboxymethyl chitosan led to slight increase of the unconfined compressive strength and substantial increase of the tensile strength, the displacement at the peak tensile load and the pre-peak toughness, with the maximum increases at 0.1 wt% chitosan content. The SEM imaging indicated that the added N-carboxymethyl chitosan biopolymer coated and bridged the (geopolymerized) fly ash particles and led to the formation of a more condensed geopolymer network structure, thus enhancing the mechanical behavior of the geopolymer-biopolymer composite. However, when too much N-carboxymethyl chitosan was used, the excessive coating and encapsulation of un-reacted and partially hydrolyzed fly ash particles hindered their geopolymerization and adversely affected the mechanical behavior of the geopolymer-biopolymer composite. [ABSTRACT FROM AUTHOR]

The use of native starch as a thermoplastic polymer is limited by its fragility and high moisture absorption. Native potato starch was derivatized using different agents in order to reduce its hydrophobicity. A reduction in starch mechanical properties was also found as a side effect of derivatization treatments. The addition of nanocellulose allows to considerably improve mechanical properties of biopolymers as well as to maintain their inherent biodegradation capability. Cellulose nanofibers were added to native and modified starch in order to improve the mechanical properties. The mechanical properties of starch/cellulose nanocomposite films were evaluated, finding that they considerably improved with the addition of cellulosic nanofibers. This contribution demonstrates a new approach in order to produce bioplastics with combined effect: improved moisture and heat resistance (due to the chemical treatment) and high mechanical properties (after the addition of nanocellulose). [ABSTRACT FROM AUTHOR]

This work includes the study of the hydrolytic biodegradation of coatings based on polylactic acid, polyglycolic acid and hydroxyapatite. These coatings were obtained by cathodic electrodeposition over piezoelectric quartz crystals, using an electrolyte with different polymer/ceramic ratios but with a fixed time, voltage and volume of solvent. The films obtained were immersed into a simulated body fluid (SBF) during 1, 3, 5, 7 and 10 days at constant temperature and pH. The coatings were analyzed by EIS and QCM to find a correlation between frequency changes and the total transferred mass. [ABSTRACT FROM AUTHOR]

Anadenanthera colubrina var. cebil (Griseb.) Altschul (Fabaceae family), commonly known as the red angico tree, is a medicinal plant found throughout Brazil's semi-arid area. In this study, a chemical analysis was performed to investigate the antidiarrheal activity and safety profile of red angico gum (RAG), a biopolymer extracted from the trunk exudate of A. colubrina. Upon FT-IR spectroscopy, RAG showed bands in the regions of 1608 cm−1, 1368 cm−1, and 1029 cm−1, which relate to the vibration of O–H water molecules, deformation vibration of C-O bands, and vibration of the polysaccharide C-O band, respectively, all of which are relevant to glycosidic bonds. The peak molar mass of RAG was 1.89 × 105 g/mol, with the zeta potential indicating electronegativity. RAG demonstrated high yield and solubility with a low degree of impurity. Pre-treatment with RAG reduced the total diarrheal stool and enteropooling. RAG also enhanced Na+/K+-ATPase activity and reduced gastrointestinal transit, and thereby inhibited intestinal smooth muscle contractions. Enzyme-Linked Immunosorbent Assay (ELISA) demonstrated that RAG can interact with GM1 receptors and can also reduce E. coli-induced diarrhea in vivo. Moreover, RAG did not induce any signs of toxicity in mice. These results suggest that RAG is a possible candidate for the treatment of diarrheal diseases. [ABSTRACT FROM AUTHOR]

Large amounts of waste generated by the disposal of non‐biodegradable packaging is a major concern that has stimulated the search for new materials for the development of environmentally friendly packaging. This study aims to produce cassava starch‐based foams incorporated with broken rice, a co‐product of rice milling. Foams were obtained by a thermopressing process, and the influence of broken rice concentration on the formulations is investigated. Broken rice addition is tested for 0 (control sample), 10, 15, 20, and 30% (w/w). Foams containing broken rice show lower thickness and higher density. With respect to water absorption capacity, the control foam and those with 10 and 15% (w/w) of broken rice addition do not present significant statistical differences for any of the tested times. Mechanical properties (tensile strain and maximum flexural stress) are positively influenced by the addition of 10% (w/w) broken rice. Foams made from formulations containing 10% (w/w) broken rice demonstrate higher tensile strain and maximum flexural stress values compared to control foams. Additionally, these foams exhibit a good appearance without superficial cracks. Broken rice is evaluated as an additive in cassava starch‐based foams. Starch‐based foams with broken rice addition (0, 10, 15, 20 and 30%, w/w) are produced by a thermopressing process. Foams containing 10% (w/w) broken rice present higher tensile strain and maximum flexural stress. In addition, these foams are homogeneous, without superficial cracks. [ABSTRACT FROM AUTHOR]

Coarse-grained (CG) simulations can more efficiently study large conformational changes of biological polymers but usually lose accuracies in the details. Lots of different hybrid models involving multiple different resolutions have been developed to overcome the difficulty. Here we propose a novel effective hybrid CG (hyCG) approach which mixes the fine-grained interaction and its average in CG space to form a more smoothing potential energy surface. The hyCG approximately reproduces the potential of mean force in the CG space, and multiple mixed potentials can be further combined together to form a single effective force field for achieving both high efficiency and high accuracy. We illustrate the hyCG method in Trp-cage and Villin headpiece proteins to exhibit the folding of proteins. The topology of the folding landscape and thus the folding paths are preserved, while the folding is boosted nearly one order of magnitude faster. It indicates that the hyCG approach could be applied as an efficient force field in proteins. [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.