607 research outputs found
Biodesulfurization of dibenzothiophene by Shewanella putrefaciens NCIMB 8768
The desulfurization ability of Shewanella putrefaciens strain NCIMB 8768 was
studied and its activity profile was compared with the widely studied strain
Rhodococcus erythropolis strain IGTS8. Dibenzothiophene (DBT) is a recalcitrant
thiophenic component of fossil fuels especially among diesel blend stocks. DBT
in basic salt medium (BSM) at a final concentration of 0.3, 0.6 and 0.9 mM was
supplied to the microbes as the sole sulfur source. Experimental results showed
that S. putrefaciens, similar to other biodesulfurization organisms, converted
DBT to the end product 2-hydroxybiphenyl (HBP), as detected by the Gibbs assay
and HPLC. Cells cultivated in medium containing 0.3 mM of DBT showed the highest
desulfurization activity, with a maximum specific production rate 43.5 mmol/L of
HBP
Fabrication and optimisation of a fused filament 3D-printed microfluidic platform
A 3D-printed microfluidic device was designed and manufactured using a low cost
($2000)
consumer grade fusion deposition modelling (FDM) 3D printer. FDM printers are not typically
used, or are capable, of producing the fine detailed structures required for microfluidic
fabrication. However, in this work, the optical transparency of the device was improved
through manufacture optimisation to such a point that optical colorimetric assays can be
performed in a 50 µl device. A colorimetric enzymatic cascade assay was optimised using
glucose oxidase and horseradish peroxidase for the oxidative coupling of aminoantipyrine
and chromotropic acid to produce a blue quinoneimine dye with a broad absorbance peaking
at 590 nm for the quantification of glucose in solution. For comparison the assay was run in
standard 96 well plates with a commercial plate reader. The results show the accurate and
reproducible quantification of
0–10 mM glucose solution using a 3D-printed microfluidic
optical device with performance comparable to that of a plate reader assay
DBT degradation enhancement by decorating Rhodococcus erythropolis IGST8 with magnetic Fe3O4 nanoparticles
Biodesulfurization (BDS) of dibenzothiophene (DBT) was carried out by Rhodococcus erythropolis IGST8 decorated with magnetic Fe3O4 nanoparticles, synthesized in-house by a chemical method, with an average size of 45-50 nm, in order to facilitate the post-reaction separation of the bacteria from the reaction mixture. Scanning electron microscopy (SEM) showed that the magnetic nanoparticles substantially coated the surfaces of the bacteria. It was found that the decorated cells had a 56% higher DBT desulfurization activity in basic salt medium (BSM) compared to the nondecorated cells. We propose that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product, respectively. Model experiments with black lipid membranes (BLM) demonstrated that the nanoparticles indeed enhance membrane permeability
The ATLAS-SPT Radio Survey of Cluster Galaxies
Using a high-performance computing cluster to mosaic 4,787 pointings, we have
imaged the 100 sq. deg. South Pole Telescope (SPT) deep-field at 2.1 GHz using
the Australian Telescope Compact Array to an rms of 80 Jy and a resolution
of 8". Our goal is to generate an independent sample of radio-selected galaxy
clusters to study how the radio properties compare with cluster properties at
other wavelengths, over a wide range of redshifts in order to construct a
timeline of their evolution out to . A preliminary analysis of the
source catalogue suggests there is no spatial correlation between the clusters
identified in the SPT-SZ catalogue and our wide-angle tail galaxies.Comment: 9 pages, 4 figures. Submitted to Proceedings of Science for "The many
facets of extragalactic radio surveys: towards new scientific challenges",
Bologna, Italy 20-23 October 2015 (EXTRA-RADSUR2015
The Spatial Correlation of Bent-Tail Galaxies and Galaxy Clusters
We have completed a deep radio continuum survey covering 86 square degrees of
the Spitzer-South Pole Telescope deep field to test whether bent-tail galaxies
are associated with galaxy clusters. We present a new catalogue of 22 bent-tail
galaxies and a further 24 candidate bent-tail galaxies. Surprisingly, of the 8
bent-tail galaxies with photometric redshifts, only two are associated with
known clusters. While the absence of bent-tail sources in known clusters may be
explained by effects such as sensitivity, the absence of known clusters
associated with most bent-tail galaxies casts doubt upon current models of
bent-tail galaxies.Comment: Accepted by MNRA
Recommended from our members
ISO observations of M8, the Lagoon nebula
In this paper, IRAS, ISO, and molecular line observations of the M8 and M8E sources in the Lagoon Nebula are reported
Large-Scale CO Maps of the Lupus Molecular Cloud Complex
Fully sampled degree-scale maps of the 13CO 2-1 and CO 4-3 transitions toward
three members of the Lupus Molecular Cloud Complex - Lupus I, III, and IV -
trace the column density and temperature of the molecular gas. Comparison with
IR extinction maps from the c2d project requires most of the gas to have a
temperature of 8-10 K. Estimates of the cloud mass from 13CO emission are
roughly consistent with most previous estimates, while the line widths are
higher, around 2 km/s. CO 4-3 emission is found throughout Lupus I, indicating
widespread dense gas, and toward Lupus III and IV. Enhanced line widths at the
NW end and along the edge of the B228 ridge in Lupus I, and a coherent velocity
gradient across the ridge, are consistent with interaction between the
molecular cloud and an expanding HI shell from the Upper-Scorpius subgroup of
the Sco-Cen OB Association. Lupus III is dominated by the effects of two HAe/Be
stars, and shows no sign of external influence. Slightly warmer gas around the
core of Lupus IV and a low line width suggest heating by the
Upper-Centaurus-Lupus subgroup of Sco-Cen, without the effects of an HI shell.Comment: 54 pages, 27 figures, 5 tables. To appear in ApJS. Preprint also
available (with full-size figures) from
http://www.astro.ex.ac.uk/people/nfht/publications.html Datacubes available
from http://www.astro.ex.ac.uk/people/nfht/resources.htm
Infrared-Faint Radio Sources: A New Population of High-redshift Radio Galaxies
We present a sample of 1317 Infrared-Faint Radio Sources (IFRSs) that, for
the first time, are reliably detected in the infrared, generated by
cross-correlating the Wide-Field Infrared Survey Explorer (WISE) all-sky survey
with major radio surveys. Our IFRSs are brighter in both radio and infrared
than the first generation IFRSs that were undetected in the infrared by the
Spitzer Space Telescope. We present the first spectroscopic redshifts of IFRSs,
and find that all but one of the IFRSs with spectroscopy has z > 2. We also
report the first X-ray counterparts of IFRSs, and present an analysis of radio
spectra and polarization, and show that they include Gigahertz-Peaked Spectrum,
Compact Steep Spectrum, and Ultra-Steep Spectrum sources. These results,
together with their WISE infrared colours and radio morphologies, imply that
our sample of IFRSs represents a population of radio-loud Active Galactic
Nuclei at z > 2. We conclude that our sample consists of lower-redshift
counterparts of the extreme first generation IFRSs, suggesting that the fainter
IFRSs are at even higher redshift.Comment: 23 pages, 17 figures. Submitted to MNRA
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