439 research outputs found
Effect of growth media modifications on cell biomass and polyunsaturated fatty acids (PUFAs) production from Shewanella frigidimarina
Polyunsaturated fatty acids (PUFAs) are chemically present as esters, ethers, glycerides glycolipids, phospholipids, phosphonolipids, glycosphingolipids, sulpholipids and lipoproteins in storage oils andmembranes lipids. Marine microorganisms such as Shewanella frigidimarina are important sources of polyunsaturated fatty acids with promising biomedical applications, commercial value and the potentialability to be used in the bioremediation of environments contaminated with petroleum hydrocarbons. The growth media dependency of S. frigidimarina in terms of its growth behavior in response to modifications made to the media as well as its potential to produce PUFAs was evaluated. S. frigidimarina was cultured in conventional shake-flasks and controlled bioreactors with a batch-type procedure using different media compositions. The media used included artificial sea water, modifiedartificial sea water 1, modified artificial sea water 2, Luria Bertani, modified Luria Bertani, sodium pyruvate-yeast (PYS) and marine broth. The highest cell biomass was obtained from artificial sea water media with an optical density (OD600) value of 0.15 and subsequent studies were carried out using this medium. To evaluate the potential for PUFA production, RNA transcripts of polyketide synthases (PKS) genes were isolated and reverse-transcriptase polymerase chain reaction (RT-PCR) with S. frigidimarina specific primers carried out. The results of the successful RNA extraction and subsequent RT-PCR revealed that modifications made to growth media compositions can affect the potential for PUFA production.Keywords: Polyunsaturated fatty acids, Shewanella frigidimarina, media modificatio
Phytochemical Screening and Preliminary Evaluation of Analgesic and Anti-Inflammatory Activities of the Methanol Root Extract of Cissus Polyantha
Cissus polyantha is used in traditional medicine for the treatment of conjunctivitis and inflammation. In this study, the methanolic root extract of Cissus polyantha was subjected to preliminary phytochemical screening, analgesic and anti-inflammatory studies. Phytochemical studies was carried out using standard phytochemical protocol while the analgesic studies was carried out using acetic acid-induced writhing tests in mice. Carrageenan-induced hind paw oedema in rats was used to evaluate the anti-inflammatory potential of the extract. Phytochemical studies of the methanolic crude root extract of the plant revealed the presence of carbohydrates, flavonoids, saponins, tannins steroids and triterpenes. The extract at doses of 20, 40 and 80 mg/kg, i.p significantly (P < 0.05) decreased the acetic-acid induced writhing. The extract also produced significant (P < 0.05) and dose-independent anti-inflammatory activity comparable to that of reference drug, ketoprofen. The intraperitoneal lethal dose (LD 50) toxicity studies on the methanol crude root extract of the plant was found to be 288.53 mg/kg body weight. These findings are suggestive of the analgesic and anti-inflammatory potentials of the methanol root bark extract of the plant and provide a scientific rationale for the use of the root of Cissus polyantha in traditional medicine.Keywords: Cissus polyantha, Phytochemical screening Analgesic, Anti-inflammatory, traditiona
Phytochemical and Antimicrobial Properties of Commiphora Pedunculata (ENGL) Stem Extracts
The extracts from the stem bark of Commiphora pedunculata, a plant used in Northern Nigeria for the treatment of infectious diseases, were subjected to phytochemical as well as antimicrobial screening using standard procedures. The antimicrobial activity against S. aureus, B. cereus, S. typhii, E. coli and C. albicans was carried out using the disc diffusion and broth micro dilution methods as outlined by the NCCLS. Preliminary phytochemical screening of the petroleum ether, ethyl acetate and methanol extracts revealed the presence of cardiac glycosides, anthraquinones, saponins, triterpenes, steroids, flavonoids, tannins and alkaloids. The results of the antimicrobial activity as indicated by the zone of inhibition of growth of the test microorganisms ranged from 17 to 28 mm, the MIC results ranged from 3.125 to 12.5 mg/mL and the MBC results ranged from 6.25 to 25.0 mg/mL for the petroleum ether, ethyl acetate and methanol extracts. The MIC of 12.50 mg/mL exhibited by the petroleum ether extract against both Gram-positive and Gram-negative bacteria indicates broad spectrum activity of Commiphora pedunculata. The results from this study showed that the extracts from the stem bark of the plant contain antimicrobial components worthy of further investigation and lends credence to the use of the plant for the treatment of infectious diseases.Keywords: Phytochemistry, Commiphora pedunculata extracts, antibacterial activity, MIC, MBC
Treatment of synthetic textile wastewater containing dye mixtures with microcosms
The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L. minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p < 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH4-N), and nitrate-nitrogen (NO3-N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L. minor, and the presence of artificial wastewater reduced their development
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
The azimuthal anisotropy of charged particles in PbPb collisions at
nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS
detector at the LHC over an extended transverse momentum (pt) range up to
approximately 60 GeV. The data cover both the low-pt region associated with
hydrodynamic flow phenomena and the high-pt region where the anisotropies may
reflect the path-length dependence of parton energy loss in the created medium.
The anisotropy parameter (v2) of the particles is extracted by correlating
charged tracks with respect to the event-plane reconstructed by using the
energy deposited in forward-angle calorimeters. For the six bins of collision
centrality studied, spanning the range of 0-60% most-central events, the
observed v2 values are found to first increase with pt, reaching a maximum
around pt = 3 GeV, and then to gradually decrease to almost zero, with the
decline persisting up to at least pt = 40 GeV over the full centrality range
measured.Comment: Replaced with published version. Added journal reference and DO
Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy
A search for new physics is performed in events with two same-sign isolated
leptons, hadronic jets, and missing transverse energy in the final state. The
analysis is based on a data sample corresponding to an integrated luminosity of
4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of
7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of
140 increase in integrated luminosity over previously published results. The
observed yields agree with the standard model predictions and thus no evidence
for new physics is found. The observations are used to set upper limits on
possible new physics contributions and to constrain supersymmetric models. To
facilitate the interpretation of the data in a broader range of new physics
scenarios, information on the event selection, detector response, and
efficiencies is provided.Comment: Published in Physical Review Letter
Compressed representation of a partially defined integer function over multiple arguments
In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one
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