Integrating engineering design improvements with exoelectrogen enrichment process to increase power output from microbial fuel cells

Microbial fuel cells (MFC) hold promise as a green technology for bioenergy production. The challenge is to improve the engineering design while exploiting the ability of microbes to generate and transfer electrons directly to electrodes. A strategy using a combination of improved anode design and an enrichment process was formulated to improve power densities. The design was based on a flow-through anode with minimal dead volume and a high electrode surface area per unit volume. The strategy focused on promoting biofilm formation via a combination of forced flow through the anode, carbon limitation, and step-wise reduction of external resistance. The enrichment process resulted in development of exoelectrogenic biofilm communities dominated by Anaeromusa spp. This is the first report identifying organisms from the Veillonellaceae family in MFCs. The power density of the resulting MFC using a ferricyanide cathode reached 300 W m⁻³ net anode volume (3220 mW m⁻²), which is about a third of what is estimated to be necessary for commercial consideration. The operational stability of the MFC using high specific surface area electrodes was demonstrated by operating the MFC for a period of over four months.     

Experimental investigation on digital offset switching strategy for precise dosing using digital multiple micropump infusion system

Microfluidics and Nanofluidics - In a drug delivery system, a piezoelectric micropump plays a vital role to deliver precise volume and concentration of the drug. Micropump in the modern infusion...     

Neural BTF Compression and Interpolation

The Bidirectional Texture Function (BTF) is a data‐driven solution to render materials with complex appearance. A typical capture contains tens of thousands of images of a material sample under varying viewing and lighting conditions. While capable of faithfully recording complex light interactions in the material, the main drawback is the massive memory requirement, both for storing and rendering, making effective compression of BTF data a critical component in practical applications. Common compression schemes used in practice are based on matrix factorization techniques, which preserve the discrete format of the original dataset. While this approach generalizes well to different materials, rendering with the compressed dataset still relies on interpolating between the closest samples. Depending on the material and the angular resolution of the BTF, this can lead to blurring and ghosting artefacts. An alternative approach uses analytic model fitting to approximate the BTF data, using continuous functions that naturally interpolate well, but whose expressive range is often not wide enough to faithfully recreate materials with complex non‐local lighting effects (subsurface scattering, inter‐reflections, shadowing and masking…). In light of these observations, we propose a neural network‐based BTF representation inspired by autoencoders: our encoder compresses each texel to a small set of latent coefficients, while our decoder additionally takes in a light and view direction and outputs a single RGB vector at a time. This allows us to continuously query reflectance values in the light and view hemispheres, eliminating the need for linear interpolation between discrete samples. We train our architecture on fabric BTFs with a challenging appearance and compare to standard PCA as a baseline. We achieve competitive compression ratios and high‐quality interpolation/extrapolation without blurring or ghosting artifacts.     

An IEEE 802.22 transceiver framework and its performance analysis on software defined radio for TV white space

With rapid increase in new applications and services, there is huge demand for internet bandwidth. Several researchers around the world have found that, majority of licensed bands (mostly terrestrial TV band) are either unused or underused. These underutilized bands allocated for TV transmission are known as TV white space (TVWS). For effective utilization of TVWS, the IEEE 802.22 is proposed. The IEEE 802.22 wireless regional area network (WRAN) is the latest standard for effective utilization of TV bands. This standard is based on orthogonal frequency division multiplexing with various modulation techniques to provide different data rates. In this paper, an implementation framework for physical layer of IEEE 802.22 WRAN standard for normal mode is demonstrated and analyzed. This transceiver is implemented using the National Instruments Laboratory Virtual Instrument Engineering Workbench programming software on the National Instruments universal software radio peripheral 2952R. We have also analyzed different blocks of IEEE 802.22 based on their execution time, and identify the critical blocks of IEEE 802.22 that should be optimized for real-time applications for commercial product development and field deployments. We have also highlighted the difference between theoretical and practical performance of the considered error control codes for IEEE 802.22 specified block size. Additionally, various covariance based spectrum sensing methods are also analyzed for real-world environment.     

Sulfur specificity in the bench‐scale biological desulfurization of crude oil by Rhodococcus IGTS8

Biological removal of organic sulfur from petroleum feedstocks may offer an attractive alternative to conventional thermochemical treatment due to the mild operating conditions and greater reaction specificity afforded by the nature of biocatalysis. Previous investigations have either reported the desulfurization of model sulfur compounds in organic solvents or gross desulfurization of crude oil without data on which sulfur species were being removed. This study reports initial sulfur speciation data for thiophenic sulfur compounds present in crude oil which may be used as a guide both as to which species are treated by the biocatalyst investigated as well as to where biocatalyst development is needed to improve the extent of biological desulfurization when applied to whole crudes. Biodesulfurization of two different crude oils in the 22–31 ° API specific gravity range with total sulfur contents between 1 and 2% is demonstrated in 1‐dm³ batch stirred reactors using wild type Rhodococcus sp IGTS8. While analysis of the crudes before and after biodesulfurization did not reveal a decrease in total sulfur, GC–MS did reveal significant (43–99%) desulfurization of dibenzothiophenes (DBT) and substituted DBTs. Fractionation of the whole crude, followed by analysis using gas chromatography–sulfur chemiluminescence detection (GC–SCD) of the aromatic fraction of the Van Texas crude oil, demonstrated a reduction of sulfur in this fraction from 3.8% to 3.2%. This research indicates that IGTS8 may be capable of biodesulfurization of refined products such as gasoline and diesel whose predominant sulfur species are dibenzothiophenes. Further biocatalyst development would be needed for effective treatment of the spectrum of sulfur‐bearing compounds present in whole crudes.     

An Expeditious Route to Fluorinated Rapamycin Analogues by Utilising Mutasynthesis

Rapamycin is a drug with several important clinical uses. Its complex structure means that total synthesis of this natural product and its analogues is demanding and lengthy. A more expeditious approach is to utilise biosynthesis to enable the generation of otherwise synthetically intractable analogues. In order to achieve this, rules governing biosynthetic precursor substrate preference must be established. Through determining these rules and synthesising and administering suitable substrate precursors, we demonstrate the first generation of fluorinated rapamycin analogues. Here we report the generation of six new fluororapamycins.     

Intellectual contribution of Indian periodontists to world literature: a bibliometric evaluation of Pubmed database till 1st March, 2012

Scientifically liberated and developed countries produce huge amounts of cutting-edge publications in peer-reviewed impact-creating journals. These publications may become basis for various policies/other blueprints. There is no reported study regarding the publication trends of Periodontists from India. The aim of this study was to assess the trends of Indian Periodontist’s publications in Pubmed database till 1st March, 2012 by taking quantitative bibliometric approach. Studies were identified by running select search phrases on Pubmed search engine. Search inputs included, ‘dental’, ‘oral’, ‘periodontal’, ‘gingiva’, ‘gingival’, ‘periodontology’, ‘periodontics’, ‘periodontia’, ‘periodontitis’, ‘gingivitis’, and ‘dental implant’. A parallel search with above phrases along with ‘India’ also done to assess India-specific publications. All publications with or without available abstracts were analyzed for selected parameters. Analysis was performed to determine name of the journal, number of authors, year of publication, type of institute, statewide distribution, type of study etc. The approximate contribution of Indian Dental/Periodontal literature to Pubmed database is 1.45 % till 1st March 2012. The number of articles published by Indian Periodontists is 764 across 107 journals and starting from 1960. The number of original articles published were 510 (66.75 %) as opposed to 127 (16.62 %) each for review articles and case reports/case series. The average contribution of an Indian Periodontist to Pubmed database is 0.53 articles. The contribution of Indian Periodontists to world literature through Pubmed database is not voluminous but, the publications are multiplying every passing year almost in an exponential way. There is also an increasing trend towards original articles to be published.     

PIV and PLIF measurements of interacting bubble plumes and their role in liquid-phase mixing in a shallow vessel

Gas-induced liquid-phase mixing in shallow vessels is important to primary and secondary steel-refining processes and governs the quality of the steel. In the present work, we have investigated the dynamics of meandering bubble plumes and their role in liquid-phase mixing in shallow vessel that corresponds to 1:6 scaled-down model of ladle used in the secondary steel-refining process. The effects of multiple meandering bubble plumes and their interactions on the liquid-phase velocity distribution, recirculatory flow, plume oscillation frequencies, and turbulent kinetic energy are analyzed for different bottom injection configurations using particle image velocimetry measurements. The role of meandering bubble plumes and their interactions in the liquid-phase mixing is analyzed using planar laser-induced fluorescence measurements. ~60% reduction in the mixing time was found with differential flow scheme. Present findings help to understand the contributions of differential flow and bubble plumes interactions to liquid-phase mixing in shallow vessels.     

Thermal fragmentation and deactivation of combustion-generated soot particles

The effect of thermal treatment on diesel soot and on a commercial soot in an inert environment under isothermal conditions at intermediate temperatures (400–900 °C) is studied. Two important phenomena are observed in both the soot samples: soot fragmentation leading to its mass loss, and loss of soot reactivity towards _O2${\mathrm{O}}_2$. Several experimental techniques such as high resolution transmission electron microscopy, electron energy loss spectroscopy, thermo-gravimetric analysis with mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction have been used to identify the changes in structures, functional groups such as oxygenates and aliphatics, σ$\sigma$ and π$\pi$ bonding, O/C and H/C ratios, and crystallite parameters of soot particles, introduced by heat. A decrease in the size of primary particles and an increase in the average polycyclic aromatic hydrocarbon (PAH) size was observed in soots after thermal treatment. The activation energies of soot oxidation for thermally treated soot samples were found to be higher than those for the untreated ones at most conversion levels. The cyclic or acyclic aliphatics with sp³${\mathrm{sp}}^3$ hybridization were present in significant amounts in all the soot samples, but their concentration decreased with thermal treatment. Interestingly, the H/C and the O/C ratios of soot particles increased after thermal treatment, and thus, they do not support the decrease in soot reactivity. The increase in the concentration of oxygenates on soot surface indicate that their desorption from soot surface in the form of CO, _CO2${\mathrm{CO}}_2$ and other oxygenated compounds may not be significant at the temperatures (400–900 °C) studied in this work.     

Calculation of phonon spectrum and thermal properties in suspended 〈100〉 In X Ga1?X As nanowires

The phonon spectra in zinc blende InAs, GaAs and their ternary alloy nanowires (NWs) are computed using an enhanced valence force field (EVFF) model. The physical and thermal properties of these nanowires such as sound velocity, elastic constants, specific heat (C _v ), phonon density of states, phonon modes, and the ballistic thermal conductance are explored. The calculated transverse and longitudinal sound velocities in these NWs are ∼25% and 20% smaller compared to the bulk velocities, respectively. The C _v for NWs are about twice as large as the bulk values due to higher surface to volume ratio (SVR) and strong phonon confinement in the nanostructures. The temperature dependent C _v for InAs and GaAs nanowires show a cross-over at 180°K due to higher phonon density in InAs nanowires at lower temperatures. With the phonon spectra and Landauer’s model the ballistic thermal conductance is reported for these III–V NWs. The results in this work demonstrate the potential to engineer the thermal behavior of III–V NWs.