Reduction of water surface tension significantly impacts gecko adhesion underwater.

The gecko adhesive system is dependent on weak van der Waals interactions that are multiplied across thousands of fine hair-like structures (setae) on geckos' toe pads. Due to the requirements of van der Waals forces, we expect that any interruption between the setae and substrate, such as a water layer, will compromise adhesion. Our recent results suggest, however, that the air layer (plastron) surrounding the superhydrophobic toe pads aid in expelling water at the contact interface and create strong shear adhesion in water when in contact with hydrophobic surfaces.

Performance enhancement and fouling mitigation by organic flocculant addition in membrane bioreactor at high salt shock.

The main objective of this study was to investigate the effect of an organic flocculant (MPE50) addition on reducing membrane fouling and enhancing performance in membrane bioreactor (MBR) at the high salt shock. Results show that MPE50 addition is a reliable and effective approach in terms of both membrane fouling mitigation and pollutants removal improvement in the case of high salt shock. Compared to the control reactor, the MBR with MPE50 addition enhanced the average removal of COD, NH4(+)-N and TP by 4.

Nutrient deprivation induces property variations in spider gluey silk.

Understanding the mechanisms facilitating property variability in biological adhesives may promote biomimetic innovations. Spider gluey silks such as the spiral threads in orb webs and the gumfoot threads in cobwebs, both of which comprise of an axial thread coated by glue, are biological adhesives that have variable physical and chemical properties. Studies show that the physical and chemical properties of orb web gluey threads change when spiders are deprived of food.

Vegetable-oil-based polymers as future polymeric biomaterials.

Vegetable oils are one of the most important classes of bio-resources for producing polymeric materials. The main components of vegetable oils are triglycerides - esters of glycerol with three fatty acids. Several highly reactive sites including double bonds, allylic positions and the ester groups are present in triglycerides from which a great variety of polymers with different structures and functionalities can be prepared.

Nanotechnology for implantable sensors: carbon nanotubes and graphene in medicine.

Implantable sensors utilizing nanotechnology are at the forefront of diagnostic, medical monitoring, and biological technologies. These sensors are often equipped with nanostructured carbon allotropes, such as graphene or carbon nanotubes (CNTs), because of their unique and often enhanced properties over forms of bulk carbon, such as diamond or graphite. Because of these properties, the fundamental and applied research of these carbon nanomaterials have become some of the most cited topics in scientific literature in the past decades.

An acetylcholinesterase-inspired biomimetic toxicity sensor.

This work demonstrates the ability of an acetylcholinesterase-inspired biomimetic sensor to accurately predict the toxicity of acetylcholinesterase (AChE) inhibitors. In surface waters used for municipal drinking water supplies, numerous pesticides and other anthropogenic chemicals have been found that inhibit AChE; however, there is currently no portable toxicity assay capable of determining the potential neurotoxicity of water samples and complex mixtures. Biological assays have been developed to determine the toxicity of unknown samples, but the short shelf-life of cells and other biological materials often make them undesirable for use in portable assays.

Continuous rhamnolipid production using denitrifying Pseudomonas aeruginosa cells in hollow-fiber bioreactor.

Rhamnolipids are high-value effective biosurfactants produced by Pseudomonas aeruginosa. Large-scale production of rhamnolipids is still challenging especially under free-cell aerobic conditions in which the highly foaming nature of the culture broth reduces the productivity of the process. Immobilized systems relying on oxygen as electron acceptor have been previously investigated but oxygen transfer limitation presents difficulties for continuous rhamnolipid production.

Biomimicry in biomedical research.

Biomimicry (literally defined as the imitation of life or nature) has sparked a variety of human innovations and inspired countless cutting-edge designs. From spider silk-made artificial skin to lotus leaf-inspired self-cleaning materials, biomimicry endeavors to solve human problems. Biomimetic approaches have contributed significantly to advances biomedical research during recent years.

Promoting pellet growth of Trichoderma reesei Rut C30 by surfactants for easy separation and enhanced cellulase production.

It is desirable to modify the normally filamentous Trichoderma reesei Rut C-30 to a pellet form, for easy biomass separation from the fermentation medium containing soluble products (e.g., cellulase).

Spider silk inspired functional microthreads.

We employ the adhesive web building strategy used by modern orb-weaving spiders to produce functional microthreads that are similar in structure (beads-on-a-string (BOAS) morphology) and adhesive properties to the capture-silk threads of the spider web. The diameter and spacing of droplets (beads) are controlled by varying the viscosity, velocity, and surface tension of the coating fluid. Using these functional threads, we also describe the behavior of the BOAS morphology during contact (mimicking the collision of an insect with the web) and during separation (mimicking insect rescue from the web).

Rhamnolipids as affinity foaming agent for selective collection of β-glucosidase from cellulase enzyme mixture.

Selective and effective separation can potentially be achieved with affinity foam fractionation using simple foaming setup and operation. In this study the use of affinity foam fractionation for selective collection and enrichment of β-glucosidase from a cellulase enzyme mixture was evaluated. Rhamnolipids, a group of glycolipids produced most commonly by Pseudomonas aeruginosa, were used as the affinity foaming agent, because of their foaming property and the presence of dirhamnose moiety (a potential substrate analog for β-glucosidase) in some rhamnolipids.

Pretreatment of guayule biomass using supercritical carbon dioxide-based method.

Guayule, a desert shrub harvested for commercial production of hypoallergenic latex and resins constitutes <20% of the biomass. Converting the remaining bagasse to biorefinery feedstock for value-added products is an optimal economic option. A supercritical CO(2)-based process had been developed previously for resin extraction.

Analysis of rhamnolipid biosurfactants by methylene blue complexation.

Rhamnolipids, produced by Pseudomonas aeruginosa, represent an important group of biosurfactants having various industrial, environmental, and medical applications. Current methods for rhamnolipid quantification involve the use of strong hazardous acids/chemicals, indirect measurement of the concentration of sugar moiety, or require the availability of expensive equipment (HPLC-MS). A safer, easier method that measures the whole rhamnolipid molecules would significantly enhance strain selection, metabolic engineering, and process development for economical rhamnolipid production.

A protean palette: colour materials and mixing in birds and butterflies.

While typically classified as either 'structural' or 'pigmentary', bio-optical tissues of terrestrial animals are rarely homogeneous and typically contain both a structural material such as keratin or chitin and one or more pigments. These base materials interact physically and chemically to create colours. Combinations of structured base materials and embedded pigment molecules often interact optically to produce unique colours and optical properties.

Dewetting of polystyrene thin films on poly(ethylene glycol)-modified surfaces as a simple approach for patterning proteins.

A simple technique for patterning proteins utilizing dewetted polystyrene (PS) droplets is demonstrated. A polystyrene thin film was spin coated on a poly(ethylene glycol) (PEG) silane-modified surface. As the PS film dewets from the surface, upon annealing, to form droplets, the PEG-silane-modified surface is exposed, which retains its capability to resist protein adsorption, and the PS droplets allow the selective adsorption of proteins.

Sludge settling and online NAD(P)H fluorescence profiles in wastewater treatment bioreactors operated at low dissolved oxygen concentrations.

Biological nitrogen removal via simultaneous nitrification and denitrification (SND) may be achieved in the single-tank bioreactors operated at low dissolved oxygen concentrations (DO). The continuous-stirred tank reactor (CSTR) configuration and the low DO environments employed are; however, more conducive to growth of filamentous bacteria and, thus, poor sludge settling in clarifiers. In this work, a synthetic wastewater was treated in bench-scale (approximately 6L) bioreactors under either cyclic or constant-rate aeration, at various sludge retention times (SRT) and DO.

Modeling culture profiles of the heterocystous N2-fixing cyanobacterium Anabaena flos-aquae.

Heterocyst differentiation is a unique feature of nitrogen-fixing cyanobacteria, potentially important for photobiological hydrogen production. Despite the significant advances in genetic investigation on heterocyst differentiation, there were no quantitative culture-level models that describe the effects of cellular activities and cultivation conditions on the heterocyst differentiation. Such a model was developed in this study, incorporating photosynthetic growth of vegetative cells, heterocyst differentiation, self-shading effect on light penetration, and nitrogen fixation.

Competition between oxygen and nitrate respirations in continuous culture of Pseudomonas aeruginosa performing aerobic denitrification.

Continuous culture of P. aeruginosa was conducted with nitrate-containing media under the dilution rates (D) of 0.026, 0.

Monitoring aerobic sludge digestion by online scanning fluorometry.

With sludge samples from two wastewater treatment plants, batch experiments of aerobic sludge digestion were conducted under different dissolved oxygen (DO) and solids concentrations. A fluorometer capable of online excitation and emission scanning was used to monitor the digestion process. Three major fluorescence peaks were observed.

Biocatalysis using an organic-soluble enzyme for the preparation of poly(lactic acid) in organic solvents.

Proleather from Bacillus sp. was chemically modified with decanoyl chloride for enhanced activity for the preparation of poly(lactic acid) in organic solvents. The modified enzyme was highly soluble (up to 44 mg-protein/ml) and active in various organic solvents including chloroform, tetrahydrofuran (THF), pyridine and acetone.

Aerobic biodegradation of trichloroethylene using a consortium of five bacterial strains.

Degradation with an aerobic consortium was used to evaluate the bioremediation trichloroethylene (TCE) as a model substrate. After one week, 228-1186 mg TCE l(-1) was degraded at rates of 20-50 microg TCE l(-1) h(-1). The introduction of 10 mg toluene l(-1) enhanced the degradation rates for TCE when greater than 600 mg l(-1).

Evaluation of different organic phases for water-in-oil xanthan fermentation.

Water-in-oil (W/O) fermentation technology has the potential for overcoming the problems related with high broth viscosity in xanthan fermentations. By dispersing the aqueous broth in a continuous organic phase, the broth-thickening mechanisms are confined within the aqueous droplets without significantly increasing the overall viscosity. In this study, xanthan fermentations were made with perfluorocarbon (PFC) or vegetable oil as the organic phase.

Polyhydroxyalkanoic acids and rhamnolipids are synthesized sequentially in hexadecane fermentation by Pseudomonas aeruginosa ATCC 10145.

Rhamnolipids and poly(beta-hydroxyalkanoic acids) (PHAs) are important fermentation products of Pseudomonas aeruginosa. Both contain beta-hydroxyalkanoic acids as main constituents. To investigate the possible relationship between their syntheses, we studied the n-hexadecane fermentation by P.

Rhamnolipid production by Pseudomonas aeruginosa under denitrification: effects of limiting nutrients and carbon substrates.

Being biosurfactants, rhamnolipids create severe foaming when produced in aerobic Pseudomonas aeruginosa fermentation. The necessary reduction of aeration causes oxygen limitation and restricts cell and product concentrations. In this study, we evaluate the new strategy of rhamnolipid production under denitrification conditions.