Electrochemical approach to microfluidics

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

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 0.289 mWm-2 with an increase of 18% in power output compared to conventional suspension culture BPV device was observed. The increase in maximum power density was correlated to the maximum relative electron transport rate (rETRm). The semi-dry type of photosynthetically active biofilm proposed in this work may offer significantly improved performances in terms of fuel cell design, bioelectricity generation, oxygen production and CO2 reduction

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

Funder: Cambridge Commonwealth, European and International Trust; Grant(s): http://dx.doi.org/10.13039/501100003343Abstract: 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. In this paper, we establish a ratio to quantify this effect in mediated systems and apply it to Synechococcus elongatus sp. PCC7942 cells grown under different nutritional regimes. Results: The results provide evidence that wider and longer cells with larger surface areas have faster mediated electron transfer rates. For rod-shaped cells, increase in cell area as a result of cell elongation more than compensates for the associated decline in mass transfer coefficients, resulting in faster electron transfer. In addition, the results demonstrate that the extent to which morphological adaptations account for the changes in electron transfer rates changes over the bacterial growth cycle, such that investigations probing physiological and metabolic changes are meaningful only at certain time periods. Conclusion: A simple ratio for quantitatively evaluating the effects of cell morphology adaptations on electron transfer rates has been defined. Furthermore, the study points to engineering cell shape, either via environmental conditioning or genetic engineering, as a potential strategy for improving the performance of biophotovoltaic devices

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

Funder: Higher Institution Centre of Excellence (HICoE) Fund, Ministry of Education: Air ocean and land interaction; Grant(s): IOES-2014FThe 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, CO2 concentration and light intensity but also the spectrum of light. Thus, a detailed understanding of the influences of light spectrum is essential. Accordingly, we developed spectrally optimized light using programmable LED arrays (PLA)s to study the effect on algae growth and bioelectricity generation. Chlorella is a green microalga and contains chlorophyll-a (chl-a), which is the major light harvesting pigment that absorbs light in the blue and red spectrum. In this study, Chlorella is grown under a PLA which can optimally simulate the absorption spectrum of the pigments in Chlorella. This experiment investigated the growth, photosynthetic performance and bioelectricity generation of Chlorella when exposed to an optimally-tuned light spectrum. The algal BPV performed better under PLA with a peak power output of 0.581 mW m-2 for immobilized BPV device on day 8, which is an increase of 188% compared to operation under a conventional white LED light source. The photosynthetic performance, as measured using pulse amplitude modulation (PAM) fluorometry, showed that the optimized spectrum from the PLA gave an increase of 72% in the rETRmax value (190.5 μmol electrons m-2 s-1), compared with the conventional white light source. Highest algal biomass (1100 mg L-1) was achieved in the immobilized system on day eight, which translates to a carbon fixation of 550 mg carbon L-1. When artificial light is used for the BPV system, it should be optimized with the light spectrum and intensity best suited to the absorption capability of the pigments in the cells. Optimum artificial light source with algal BPV device can be integrated into a power management system for low power application (eg. environment sensor for indoor agriculture system)

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. In this paper, we establish a ratio to quantify this effect in mediated systems and apply it to Synechococcus elongatus sp. PCC7942 cells grown under different nutritional regimes. Results: The results provide evidence that wider and longer cells with larger surface areas have faster mediated electron transfer rates. For rod-shaped cells, increase in cell area as a result of cell elongation more than compensates for the associated decline in mass transfer coefficients, resulting in faster electron transfer. In addition, the results demonstrate that the extent to which morphological adaptations account for the changes in electron transfer rates changes over the bacterial growth cycle, such that investigations probing physiological and metabolic changes are meaningful only at certain time periods. Conclusion: A simple ratio for quantitatively evaluating the effects of cell morphology adaptations on electron transfer rates has been defined. Furthermore, the study points to engineering cell shape, either via environmental conditioning or genetic engineering, as a potential strategy for improving the performance of biophotovoltaic devices

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

Funder: Cambridge Trust; doi: http://dx.doi.org/10.13039/501100003343Funder: Cambridge CARES C4TElectrons 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. PCC7942 BPV current density profiles into physically meaningful oscillatory components, and compute their instantaneous frequencies. We develop hypotheses for the genesis of the oscillations via repeat experiments with iron-depleted and 20% CO[Formula: see text] enriched biofilms. The oscillations exhibit rhythms that are consistent with the state of the art cyanobacteria circadian model, and putative exoelectrogenic pathways. In particular, we observe oscillations consistent with: rhythmic D1:1 (photosystem II core) expression; circadian-controlled glycogen accumulation; circadian phase shifts under modified intracellular %ATP; and circadian period shortening in the absence of the iron-sulphur protein LdpA. We suggest that the extracted oscillations may be used to reverse-identify proteins and/or metabolites responsible for cyanobacteria exoelectrogenesis

Concha Bullosa Mucopyocele: a Case Report

Concha bullosa (CB) is among the most common anatomic variations of sinonasal anatomy. Although usually asymptomatic, CB can occasionally cause nasal obstruction or headache. Obstructions within the mucociliary transport system can develop into a mucocele or mucopyocele. A 48-year-old female, with a history of progressive headache and nasal obstruction, was referred to our department. Paranasal sinus tomography revealed a nasal mass in the left nasal cavity resembling a mucopyocele in the middle turbinate. Under general anesthesia, the purulent material was aspirated, and the lateral part of the left turbinate was resected. Mucopyoceles are common within the paranasal sinuses, but uncommon with CB; thus, they should be considered in patients with a large hyperemic nasal mass

Research data supporting “Generation of strength in a drying colloidal dispersion: How the fracture toughness depends on film properties”

In experiments we generate images of cracks in drying suspensions The code determines the crack tip and then calculates the crack width as a function of distance from the crack tip.Ernest-Solvay-Stiftung and Studienstiftung des deutschen Volke

Transseptal Suturing Reduce Patient Anxiety after Septoplasty Compared to Nasal Packing

Background: We measured postoperative anxiety in patients who underwent transseptal suturing or nasal packing after septoplasty. Materials and Methods: Transseptal suturing was performed on Group 1 patients and nasal splints with airway were placed after septoplasty in Group 2 patients. Postoperative 48-h anxiety levels of both groups were measured using the State-Trait Anxiety Inventory (STAI) clinical assessment scale, prior to removal of nasal packing in Group 2. Results: Transseptal suturing was performed after septoplasty in 28 patients and nasal packing in 34 patients. The State-Trait Anxiety Inventory clinical assessment state (STAI-S) and trait (STAI-T) instruments were used to measure postoperative anxiety. The STAI-S scores were found 35.00 in the transseptal suturing group and 43.8 in the nasal packing group; the difference was found significant (p 0.05). The rate of minor hemorrhage was found 10.7% in Group 1 patients. Conclusions: Transseptal suturing is simple and reliable when performed after septoplasty. The technique is painless and comfortable, and reduces patient anxiety (compared to that associated with nasal packing) with only a minor increase in operating time and hemorrhage