436 research outputs found
Resolving the chemical substructure of Orion-KL
The Kleinmann-Low nebula in Orion (Orion-KL) is the nearest example of a
high-mass star-forming environment. For the first time, we complemented 1.3 mm
Submillimeter Array (SMA) interferometric line survey with IRAM 30 m
single-dish observations of the Orion-KL region. Covering a 4 GHz bandwidth in
total, this survey contains over 160 emission lines from 20 species (25
isotopologues), including 11 complex organic molecules (COMs).
At a spatial resolution of 1200 AU, the continuum substructures are resolved.
Extracting the spectra from individual substructures and providing the
intensity-integrated distribution map for each species, we studied the
small-scale chemical variations in this region. Our main results are: (1) We
identify lines from the low-abundance COMs CH3COCH3 and CH3CH2OH, as well as
tentatively detect CH3CHO and long carbon-chains C6H and HC7N. (2) We find that
while most COMs are segregated by type, peaking either towards the hot core
(e.g., N-bearing species) or the compact ridge (e.g., O-bearing species like
HCOOCH3 and CH3OCH3), while the distributions of others do not follow this
segregated structure (e.g., CH3CH2OH, CH3OH, CH3COCH3). (3) We find a second
velocity component of HNCO, SO2, 34SO2, and SO lines, which may be associated
with a strong shock event in the low-velocity outflow. (4) Temperatures and
molecular abundances show large gradients between central condensations and the
outflow regions, illustrating a transition between hot molecular core and
shock-chemistry dominated regimes.
Our observations of spatially resolved chemical variations in Orion-KL
provide the nearest reference source for hot molecular core and outflow
chemistry, which will be an important example for interpreting the chemistry of
more distant HMSFRs.Comment: 51 pages, 17 figures, accepted on 12 March 2015 Dashed lines in
Figure 10 of the published paper was missin
Phytopharmacotherapeutic and Antimicrobial Attributes of Bitter Apple (Citrullus colocynthis) - A Review
Emergence of drug-resistant microorganisms over the past few decades has resulted in the search for bioactive compounds potent against these microorganisms. Phytochemicals derived from plants have shown positive curative properties and can be extracted from any part of the plant such as the roots, stem or flower. Bitter apple (Citrullus colocynthis) has been used traditionally for the treatment of infectious diseases and this has stimulated pharmacological interest in the active ingredients responsible for its medicinal properties. The plant also possesses several biological and pharmacological activities including anti-inflammatory, antidiabetic, antimicrobial, anticancer, and antioxidant. This review discussed the phytochemicals present in C. colocynthis, their mode of action and their antimicrobial attributes
Phytopharmacotherapeutic and Antimicrobial Attributes of Bitter Apple (Citrullus colocynthis) - A Review
Emergence of drug-resistant microorganisms over the past few decades has resulted in the search for bioactive compounds potent against these microorganisms. Phytochemicals derived from plants have shown positive curative properties and can be extracted from any part of the plant such as the roots, stem or flower. Bitter apple (Citrullus colocynthis) has been used traditionally for the treatment of infectious diseases and this has stimulated pharmacological interest in the active ingredients responsible for its medicinal properties. The plant also possesses several biological and pharmacological activities including anti-inflammatory, antidiabetic, antimicrobial, anticancer, and antioxidant. This review discussed the phytochemicals present in C. colocynthis, their mode of action and their antimicrobial attributes
Analysis of Groundwater Pollution from an Unlined Constructed Wetland Sludge Drying Bed
Sludge drying beds (SBDs) are part of wastewater treatment processes where dewatering and reduction of water content from the substrate sludge take place to enhance caking and thus facilitate handling and disposal. In this study, the effect of the operation of an unlined drying bed of a constructed wetland for domestic wastewater treatment on the adjourning groundwater was investigated. Experimental boreholes for water quality monitoring were constructed downstream of the SBD prior to its operation. Preliminary investigations of the quality of water in the boreholes were carried out before the operation of the SBD. The concentration levels of pH, Conductivity, Total Dissolved Solids, Colour, Mn, Fe, SO4, NO3, Total Coliform and e-coli were used to empirically and statistically determine the level of pollution of the ground water during the operation of the SDB. The 2-way ANOVA at (=0.05) showed that the operation of the SBD had statistically significant impact on the quality of the groundwater on all the observed parameters. For the parameters observed, p<0.05 (p=0.00 for the averages of pH, EC, TDS, Turbidity, Colour, Mn+2, Fe+2, SO4 and NO3), while p=0.0028 and 0.0018 for the averages of Total coliform and E.coli respectively in all the boreholes. The distances from the discharge point of the SDB were at 15m, 20m, 25m, 30m, 35m, 40m and 50m for boreholes 1, 2, 3, 4, 5, 6 and 7 respectively. Also, comparison of the means of the quality parameters with the allowable limits set by the Nigerian National Environmental Surface and Groundwater Quality Control Regulations (NSGQCR) indicated that the operation of the SBD rendered the quality of the groundwater unacceptable
A line confusion-limited millimeter survey of Orion KL. III. Sulfur oxide species
We present a study of the sulfur-bearing species detected in a line
confusion-limited survey towards Orion KL performed with the IRAM 30m telescope
in the range 80-281 GHz. The study is part of an analysis of the line survey
divided into families of molecules. Our aim is to derive accurate physical
conditions and molecular abundances in the different components of Orion KL
from observed SO and SO2 lines. First we assumed LTE conditions obtain
rotational temperatures. We then used a radiative transfer model, assuming
either LVG or LTE excitation to derive column densities of these molecules in
the different components of Orion KL. We have detected 68 lines of SO, 34SO,
33SO, and S18O and 653 lines of SO2, 34SO2, 33SO2, SO18O and SO2 v2=1. We
provide column densities for all of them and also upper limits for the column
densities of S17O, 36SO, 34S18O, SO17O and 34SO2 v2=1 and for several
undetected sulfur-bearing species. In addition, we present 2'x2' maps around
Orion IRc2 of SO2 transitions with energies from 19 to 131 K and also maps with
four transitions of SO, 34SO and 34SO2. We observe an elongation of the gas
along the NE-SW direction. An unexpected emission peak appears at 20.5 km/s in
most lines of SO and SO2. A study of the spatial distribution of this emission
feature shows that it is a new component ~5" in diameter, which lies ~4" west
of IRc2. We suggest the emission from this feature is related to shocks
associated to the BN object. The highest column densities for SO and SO2 are
found in the high-velocity plateau (a region dominated by shocks) and in the
hot core. These values are up to three orders of magnitude higher than the
results for the ridge components. We also find high column densities for their
isotopologues in both components. Therefore, we conclude that SO and SO2 are
good tracers, not only of regions affected by shocks, but also of regions with
warm dense gas.Comment: Paper (ref AA/2013/21285) accepted for publication by A&A. 52 Pages,
26 figures, 13 table
Extended warm gas in Orion KL as probed by methyl cyanide
In order to study the temperature distribution of the extended gas within the
Orion Kleinmann-Low nebula, we have mapped the emission by methyl cyanide
(CH3CN) in its J=6_K-5_K, J=12_K-11_K, J=13_K-12_K, and J=14_K-13_K transitions
at an average angular resolution of ~10 arcsec (22 arcsec for the 6_K-5_K
lines), as part of a new 2D line survey of this region using the IRAM 30m
telescope. These fully sampled maps show extended emission from warm gas to the
northeast of IRc2 and the distinct kinematic signatures of the hot core and
compact ridge source components. We have constructed population diagrams for
the four sets of K-ladder emission lines at each position in the maps and have
derived rotational excitation temperatures and total beam-averaged column
densities from the fitted slopes. In addition, we have fitted LVG model spectra
to the observations to determine best-fit physical parameters at each map
position, yielding the distribution of kinetic temperatures across the region.
The resulting temperature maps reveal a region of hot (T > 350 K) material
surrounding the northeastern edge of the hot core, whereas the column density
distribution is more uniform and peaks near the position of IRc2. We attribute
this region of hot gas to shock heating caused by the impact of outflowing
material from active star formation in the region, as indicated by the presence
of broad CH3CN lines. This scenario is consistent with predictions from C-shock
chemical models that suggest that gas-phase methyl cyanide survives in the
post-shock gas and can be somewhat enhanced due to sputtering of grain mantles
in the passing shock front.Comment: 24 pages, 20 figures, accepted for publication in A&
Patogenisitas Beberapa Isolat Cendawan Entomopatogen Metarhizium Spp. Terhadap Telur Spodoptera Litura Fabricius (Lepidoptera: Noctuidae)
Metarhizium spp. is one of the entomopathogenic fungus that can be used to control Spodoptera litura. The purpose of this research was to study the pathogenicity of Metarhizium spp. to Spodoptera litura eggs. The isolates were collected from rhizosphere of different crops i.e., cabbage, onion, leek and Chili. The results showed that there was effect of all isolates on egg mortality. Mortality of S. litura eggs depend on the fungal isolates, ranged between 19.79%-75.70%. First instar larvae was also died 3 days after eclosion. The maximum mortality of first instar larvae was 58.65%. At a concentration of 108 conidia/ml, isolate Mt-kb had the highest virulence which caused higher mortality of eggs and first instar larvae
Scientific Advancement in Contemporary Society: The Interface between Technology, Science and Law
This article is premised on the relation of technology and applied sciences with law. The three subjects are not only interwoven but cannot be protected and regulated without the viable use of law. The unprecedented advancement ofscientific innovations has far-reaching implication in virtually all ramifications of human endeavour. Technology is an invention created using science, which needs to be sustained by prudent management and law. The research goal is to narrow down a middle ground where all these independent fields can meet and share a symbiotic relationship without stifling each other. The research seeks to ascertain the knowledge and perception of selected university students of Nigeria and India, about Science, Law and Technology. The authors adopted the doctrinal and empirical research methodology coupled with the use of cases and legislations as source of information. The research revealed that majority of the participants has knowledge about the co-existence and impact of Science, Technology and Law in the society. However, the attitude and perception of the participants constitute a fundamental influence on the degree to which technological orientations occur during learning process. Also, 85% of 200 participants agreed that there is need for frequent education and legislation as science and technology evolves in the society. Hence, this article recommends the implementation and frequent modifications of law to continually protect, encourage and ensure the societal sustainability of ethical standards
The hot core towards the intermediate mass protostar NGC7129 FIRS 2: Chemical similarities with Orion KL
NGC 7129 FIRS 2 (hereafter FIRS 2) is an intermediate-mass (2 to 8 Msun)
protostar located at a distance of 1250 pc. High spatial resolution
observations are required to resolve the hot core at its center. We present a
molecular survey from 218200 MHz to 221800 MHz carried out with the IRAM
Plateau de Bure Interferometer. These observations were complemented with a
long integration single-dish spectrum taken with the IRAM 30m telescope. We
used a Local Thermodynamic Equilibrium (LTE) single temperature code to model
the whole dataset. The interferometric spectrum is crowded with a total of ~300
lines from which a few dozens remain unidentified yet. The spectrum has been
modeled with a total of 20 species and their isomers, isotopologues and
deuterated compounds. Complex molecules like methyl formate (CH3OCHO), ethanol
(CH3CH2OH), glycolaldehyde (CH2OHCHO), acetone (CH3COCH3), dimethyl ether
(CH3OCH3), ethyl cyanide (CH3CH2CN) and the aGg' conformer of ethylene glycol
(aGg'-(CH2OH)_2) are among the detected species. The detection of vibrationally
excited lines of CH3CN, CH3OCHO, CH3OH, OCS, HC3N and CH3CHO proves the
existence of gas and dust at high temperatures. In fact, the gas kinetic
temperature estimated from the vibrational lines of CH3CN, ~405 K, is similar
to that measured in massive hot cores. Our data allow an extensive comparison
of the chemistry in FIRS~2 and the Orion hot core. We find a quite similar
chemistry in FIRS 2 and Orion. Most of the studied fractional molecular
abundances agree within a factor of 5. Larger differences are only found for
the deuterated compounds D2CO and CH2DOH and a few molecules (CH3CH2CN, SO2,
HNCO and CH3CHO). Since the physical conditions are similar in both hot cores,
only different initial conditions (warmer pre-collapse phase in the case of
Orion) and/or different crossing time of the gas in the hot core can explain
this behavior.Comment: 30 pages, 9 figure
A combined IRAM and Herschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC3N
We present a study of cyanoacetylene (HC3N) and cyanodiacetylene (HC5N) in
Orion KL, through observations from two line surveys performed with the IRAM
30m telescope and the HIFI instrument on board the Herschel telescope. The
frequency ranges covered are 80-280 GHz and 480-1906 GHz. We model the observed
lines of HC3N, HC5N, their isotopologues (including DC3N), and vibrational
modes, using a non-LTE radiative transfer code. To investigate the chemical
origin of HC3N and DC3N in Orion KL, we use a time-dependent chemical model. We
detect 40 lines of the ground state of HC3N and 68 lines of its 13C
isotopologues. We also detect 297 lines of six vibrational modes of this
molecule (nu_7, 2nu_7, 3nu_7, nu_6, nu_5, and nu_6+nu_7) and 35 rotational
lines of the ground state of HC5N. We report the first tentative detection of
DC3N in a giant molecular cloud with a DC3N/HC3N abundance ratio of 0.015. We
provide column densities and isotopic and molecular abundances. We also perform
a 2x2" map around Orion IRc2 and we present maps of HC3N lines and maps of
lines of the HC3N vibrational modes nu_6 and nu_7. In addition, a comparison of
our results for HC3N with those in other clouds allows us to derive
correlations between the column density, the FWHM, the mass, and the luminosity
of the clouds. The high column densities of HC3N obtained in the hot core, make
this molecule an excellent tracer of hot and dense gas. In addition, the large
frequency range covered reveals the need to consider a temperature and density
gradient in the hot core in order to obtain better line fits. The high D/H
ratio (comparable to that obtained in cold clouds) that we derive suggests a
deuterium enrichment. Our chemical models indicate that the possible deuterated
HC3N present in Orion KL is formed during the gas-phase. This fact provides new
hints concerning the processes leading to deuteration.Comment: 50 pages, 33 figures, 13 tables. Accepted for publication in A&
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