Decomposing biophotovoltaic current density profiles using the Hilbert-Huang transform reveals influences of circadian clock on cyanobacteria exoelectrogenesis.

Electrons from cyanobacteria photosynthetic and respiratory systems are implicated in current generated in biophotovoltaic (BPV) devices. However, the pathway that electrons follow to electrodes remains largely unknown, limiting progress of applied research. Here we use Hilbert-Huang Transforms to decompose Synechococcus elongatus sp.

Augmenting the biodegradation of recalcitrant ethinylestradiol using Rhodopseudomonas palustris in a hybrid photo-assisted microbial fuel cell with enhanced bio-hydrogen production.

This study presents the biodegradation potential of ethinylestradiol (EE2) in anaerobic environments using exoelectrogenic activity of Rhodopseudomonas palustris. EE2, a basic ingredient in oral contraceptives, is a significant estrogenic micropollutant in various wastewaters and is considered highly recalcitrant. This recalcitrance of EE2 has caused anoxic areas to become repositories for these pollutants.

Optimised spectral effects of programmable LED arrays (PLA)s on bioelectricity generation from algal-biophotovoltaic devices.

The biophotovoltaic cell (BPV) is deemed to be a potent green energy device as it demonstrates the generation of renewable energy from microalgae; however, inadequate electron generation from microalgae is a significant impediment for functional employment of these cells. The photosynthetic process is not only affected by the temperature, CO concentration and light intensity but also the spectrum of light. Thus, a detailed understanding of the influences of light spectrum is essential.

Quantitative analysis of the effects of morphological changes on extracellular electron transfer rates in cyanobacteria.

Background: Understanding the extracellular electron transport pathways in cyanobacteria is a major factor towards developing biophotovoltaics. Stressing cyanobacteria cells environmentally and then probing changes in physiology or metabolism following a significant change in electron transfer rates is a common approach for investigating the electron path from cell to electrode. However, such studies have not explored how the cells' concurrent morphological adaptations to the applied stresses affect electron transfer rates.

Mechanistic evaluation of the exoelectrogenic activity of Rhodopseudomonas palustris under different nitrogen regimes.

The operation of bioelectrochemical systems (BESs) relies on the ability of microbes to export electrons outside of their cells. However, microorganisms are not evolutionary conceived to power BESs as most of the redox processes occur within. In this study, a low cost strategy equivalent to the one used to improve hydrogen production is employed to divert electrons from the metabolism to an electrode.

Enhancement of Power Output by using Alginate Immobilized Algae in Biophotovoltaic Devices.

We report for the first time a photosynthetically active algae immobilized in alginate gel within a fuel cell design for generation of bioelectricity. The algal-alginate biofilm was utilized within a biophotovoltaics (BPV) device developed for direct bioelectricity generation from photosynthesis. A peak power output of 0.

Generation of strength in a drying film: How fracture toughness depends on dispersion properties.

The fracture toughness of colloidal films is measured by characterizing cracks which form during directional drying. Images from a confocal microscope are processed to measure the crack width as a function of distance from the crack tip. Applying theory for thin elastic films the fracture toughness is extracted.

Investigating the association between photosynthetic efficiency and generation of biophotoelectricity in autotrophic microbial fuel cells.

Microbial fuel cells operating with autotrophic microorganisms are known as biophotovoltaic devices. It represents a great opportunity for environmentally-friendly power generation using the energy of the sunlight. The efficiency of electricity generation in this novel system is however low.

Reduced graphene oxide anodes for potential application in algae biophotovoltaic platforms.

The search for renewable energy sources has become challenging in the current era, as conventional fuel sources are of finite origins. Recent research interest has focused on various biophotovoltaic (BPV) platforms utilizing algae, which are then used to harvest solar energy and generate electrical power. The majority of BPV platforms incorporate indium tin oxide (ITO) anodes for the purpose of charge transfer due to its inherent optical and electrical properties.

Evaluation of algal biofilms on indium tin oxide (ITO) for use in biophotovoltaic platforms based on photosynthetic performance.

In photosynthesis, a very small amount of the solar energy absorbed is transformed into chemical energy, while the rest is wasted as heat and fluorescence. This excess energy can be harvested through biophotovoltaic platforms to generate electrical energy. In this study, algal biofilms formed on ITO anodes were investigated for use in the algal biophotovoltaic platforms.

In situ fluorescence and electrochemical monitoring of a photosynthetic microbial fuel cell.

Using an in-house developed platform, the performance of an Arthrospira maxima biofilm photosynthetic microbial fuel cell (PMFC) was monitored both optically and electrochemically. Fluorescence (excitation wavelength 633 nm, emission range 640 to 800 nm for detection of fluorescence), power density and current output of the PMFC were recorded in real time. Confocal microscopy performed in situ allowed detailed fluorescence imaging to further improve the understanding of the photosynthetic activity of the biofilm that developed on the anode surface of the PMFC, whilst power and current outputs indicated the performance of the cell.

Comparison of power output by rice (Oryza sativa) and an associated weed (Echinochloa glabrescens) in vascular plant bio-photovoltaic (VP-BPV) systems.

Vascular plant bio-photovoltaics (VP-BPV) is a recently developed technology that uses higher plants to harvest solar energy and the metabolic activity of heterotrophic microorganisms in the plant rhizosphere to generate electrical power. In the present study, electrical output and maximum power output variations were investigated in a novel VP-BPV configuration using the crop plant rice (Oryza sativa L.) or an associated weed, Echinochloa glabrescens (Munro ex Hook.

Surface morphology and surface energy of anode materials influence power outputs in a multi-channel mediatorless bio-photovoltaic (BPV) system.

Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. Currently power outputs from BPVs are generally low and suffer from low efficiencies. However, a better understanding of the electrochemical interactions between the microbes and conductive materials will be likely to lead to increased power yields.

Attributes of direct current aperiodic and alternating current harmonic components derived from large amplitude Fourier transformed voltammetry under microfluidic control in a channel electrode.

The flow rate dependencies of the aperiodic direct current (dc) and fundamental to eighth alternating current (ac) harmonic components derived from large-amplitude Fourier transformed ac (FT-ac) voltammetry have been evaluated in a microfluidic flow cell containing a 25 μm gold microband electrode. For the oxidation of ferrocenemethanol ([FcMeOH]/[FcMeOH](+) process) in aqueous 0.1 M KNO(3) electrolyte, standard "Levich-like" dc behavior is observed for the aperiodic dc component, which enables the diffusion coefficient for FcMeOH to be obtained.

In situ fabrication of a microfluidic device for immobilised metal affinity sensing.

In this work a novel microfluidic device was constructed in situ containing the smallest microscopic co-polymeric immobilised metal affinity (IMA) adsorbent yet documented. This device has for the first time allowed the microlitre scale chromatographic assay of histidine-tagged proteins in a biological sample. To enable this approach, rather than using a high capacity commercial packed bed column which requires large sample volumes and would be susceptible to occlusion by cell debris, a microgram capacity co-polymeric chromatographic substrate suitable for analytical applications was fabricated within a microfluidic channel.

A method for the positioning and tracking of small moving particles.

On the move: Electrochemistry has been used to detect and monitor the motion of a single 330 microm sphere in both time and space (see picture). The motion was recorded simultaneously by video and chronoamperometry, which showed an excellent correlation. The ability to fabricate electrode arrays capable of spatial resolution at the sub-micrometer scale opens the possibility of using this technique to monitor considerably smaller particles.

The electrochemical detection of droplets in microfluidic devices.

This paper presents a new electrochemical method for the detection and characterisation of aqueous droplets in an organic carrier fluid (1,2-dichloroethane) formed in flow-focusing microfluidic devices. The devices consist of a conventional flow-focusing channel 250 microm wide and 250 microm deep cast out of poly(dimethylsiloxane) (PDMS) which is sealed onto a glass substrate containing a set of microelectrodes 100 microm long. Chronoamperometric analysis of a suitable electrolyte contained in the organic phase is presented for characterising the droplet frequency and size.

Study of miscible and immiscible flows in a microchannel using magnetic resonance imaging.

Magnetic resonance imaging (MRI) is a noninvasive technique that can be used to visualize mixing processes in optically opaque systems in up to three dimensions. Here, MRI has been used for the first time to obtain both cross-sectional velocity and concentration maps of flow through an optically opaque Y-shaped microfluidic sensor. Images of 23 micromx23 microm resolution were obtained for a channel of rectangular cross section (250 micromx500 microm) fed by two square inlets (250 micromx250 microm).

Quantitative kinetic analysis in a microfluidic device using frequency-domain fluorescence lifetime imaging.

A novel microfluidic approach for the quantification of reaction kinetics is presented. A three-dimensional finite difference numerical simulation was developed in order to extract quantitative kinetic information from fluorescence lifetime imaging experimental data. This approach was first utilized for the study of a fluorescence quenching reaction within a microchannel; the lifetime of a fluorophore was used to map the diffusion of a quencher across the microchannel.

Refolding of a membrane protein in a microfluidics reactor.

Membrane protein production for structural studies is often hindered by the formation of non-specific aggregates from which the protein has to be denatured and then refolded to a functional state. We developed a new approach, which uses microfluidics channels, to refold protein correctly in quantities sufficient for structural studies. Green fluorescent protein (GFP), a soluble protein, and bacteriorhodopsin (BR), a transmembrane protein, were used to demonstrate the efficiency of the process.

A microfluidic channel flow cell for electrochemical ESR.

The design, fabrication, and characterization of microfluidic channel flow devices for in situ simultaneous hydrodynamic electrochemical ESR is reported. The microelectrochemical reactors consist of gold film electrodes situated within rectangular ducts of height 350 microm and widths in the range 500-2000 microm. The small dimensions of the channels result in minimal dielectric loss when centralized within a cylindrical TE011 resonant cavity, leading to a high level of sensitivity.

Hydrodynamic study of ion transfer at the liquid/liquid interface: the channel flow cell.

A hydrodynamic system based on the channel flow cell for voltammetric detection of ions at the liquid/liquid interface is reported. The current response for tetraethylammonium ion transfer across a membrane-supported liquid/liquid interface is shown to be consistent with existing theory for both the flow rate and voltage scan rate dependence of such processes, with no calibration factors or other adjustable parameters required. The analytical utility of such a device is discussed with specific regard to in situ measurements in flow systems.