1,403 research outputs found
Population dynamics of a cladoceran zooplankter, Daphnia magna, in two poultry-cum-fish (duck-fish and chicken-fish) integrated ponds
The population dynamics of Daphnia magna was studied in two integrated fish-cum-poultry ponds (duck-fish and chicken-fish). The seasonal changes in the population of D. magna were recorded. Peak population of the zooplankter was recorded in the month of January in both ponds. The birth rate (b), growth rate (r) and death rate {d) of D. magna were studied in field as well as in the laboratory. Three temperatures and three different food concentrations were selected for laboratory study. The maximum values of (b) and (r) were recorded during December-January in field. Under laboratory conditions, highest birth and death rate occurred at lowest temperature (15 °C). Both food and temperature were found to affect the population dynamics of the species; longest life span and maximum population were recorded at lowest temperature and maximum food concentration
Selection and characterization of non-ideal ionic liquids mixtures to be used in CO
Due to the costs involved, the capture of CO2 in post-combustion is not currently seen as economically
viable. Aiming at changing the perception of post-combustion CO2 from a costly and non-profitable
process to a valuable commodity and fostering the development of the next-generation of technologies,
novel solvents and their mixtures have been investigated. In this work, mixtures of non-volatile
ionic liquids were screened by COSMO-RS aiming to find mixtures with positive excess volumes that
could present an increased CO2 capture by physical sorption. The most promising mixtures identified by
COSMO-RS, [C4C1im][DMP] or [C4C1im][NTf2] þ carboxylate-based protic ILs were characterized through
the measurement of their thermophysical properties, namely density and viscosity. Both properties were
measured for pure ILs and their binary mixtures at different temperatures and compositions. The temperature
dependence of density of pure ILs was described using the Gardas and Coutinho model while
viscosity was accurately described using the Vogel Tammann Fulcher equation. The Redlich-Kister
equation was used to predict the excess molar volumes and the non-ideality of the mixtures’ viscosity
was assessed using the Grunberg and Nissan mixing law. The excess molar volumes for mixtures containing
[C4C1im][DMP] show large positive values all over the range of compositions and temperatures,
making them good candidates for CO2 capture. To the best of our knowledge, the excess molar volumes
obtained in this work were the highest reported so far. COSMO-RS was able to correctly predict the trend
of the experimental excess molar volumes for these mixtures. Regarding viscosity, mixtures of [C4C1im]
[DMP] with the carboxylate-based protic ILs led to the desired viscosity decrease compared to the pure
aprotic IL, and large deviations from ideality were observed. The mixing of ILs is thus an efficient way to
fine-tune the properties, in this case decreasing the viscosity while increasing the sorption capacity.This work is a result of the Indo-Portuguese Program for
Cooperation in Science & Technology DST/INT/Portugal/P-01/2017,
financed by FCT and the Government of India. This work was also
developed within the scope of the project CICECO-Aveiro Institute
of Materials, UIDB/50011/2020 & UIDP/50011/2020, and CIMOMountain
Research Center, UIDB/00690/2020, both financed by
national funds through the FCT, MEC and when appropriate cofinanced
by FEDER under the PT2020 Partnership Agreement.
MARM acknowledges the project “AIProcMat@N2020 - Advanced
Industrial Processes and Materials for a Sustainable Northern Region
of Portugal 2020”, with the reference NORTE-01-0145-FEDER-
000006, supported by Norte Portugal Regional Operational Programme
(NORTE 2020). P.J.C. acknowledges FCT for his contract
under the Investigator FCT 2015 contract number IF/00758/2015.info:eu-repo/semantics/publishedVersio
Non-linear stability in photogravitational non-planar restricted three body problem with oblate smaller primary
We have discussed non-linear stability in photogravitational non-planar
restricted three body problem with oblate smaller primary. By
photogravitational we mean that both primaries are radiating. We normalised the
Hamiltonian using Lie transform as in Coppola and Rand (1989). We transformed
the system into Birkhoff's normal form. Lie transforms reduce the system to an
equivalent simpler system which is immediately solvable. Applying Arnold's
theorem, we have found non-linear stability criteria. We conclude that is
stable. We plotted graphs for They are rectangular
hyperbola.Comment: Accepted for publication in Astrophysics & Space Scienc
Rho-Nucleon Tensor Coupling and Charge-Exchange Resonances
The Gamow-Teller resonances are discussed in the context of a self-consistent
RPA, based on the relativistic mean field theory. We inquire on the possibility
of substituting the phenomenological Landau-Migdal force by a microscopic
nucleon-nucleon interaction generated from the rho-nucleon tensor coupling. The
effect of this coupling turns out to be very small when the short range
correlations are not taken into account, but too large when these correlations
are simulated by the simple extraction of the contact terms from the resulting
nucleon-nucleon interaction.Comment: 15 pages, LaTeX, 2 figures; extended text, improved figures, new
references added, the version appearing in Phys.Lett.
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Synthesis of a base-stock for electrical insulating fluid based on palm kernel oil
This report presents a method for synthesizing base-stock for green industrial product from a vegetable oil with a high composition of unsaturated fatty acids. Epoxy methyl ester of palm kernel oil was synthesized from laboratory purified palm kernel oil using a two-step reaction and the products were used as a base-stock for green electrical insulation fluid. Epoxidized palm kernel oil was first prepared through epoxidation reaction involving purified palm kernel oil, acetic acid and hydrogen peroxide in the presence of amberlite as catalyst which lasted for 4 h. It was then followed by transesterification reaction involving the epoxidized product and methanol in the presence of sodium hydroxide as catalyst to synthesize the corresponding epoxy methyl ester. The thermal and electrical breakdown properties of the epoxy methyl ester demonstrated significantly improved properties for its use as raw material for bio-based industrial products such as electrical insulation fluids
Low-dimensional representations of exact coherent states of the Navier-Stokes equations from the resolvent model of wall turbulence
We report that many exact invariant solutions of the Navier-Stokes equations for both pipe and channel flows are well represented by just few modes of the model of McKeon & Sharma J. Fl. Mech. 658, 356 (2010). This model provides modes that act as a basis to decompose the velocity field, ordered by their amplitude of response to forcing arising from the interaction between scales. The model was originally derived from the Navier-Stokes equations to represent turbulent flows and has been used to explain coherent structure and to predict turbulent statistics. This establishes a surprising new link between the two distinct approaches to understanding turbulence
Resonance approximation and charge loading/unloading in adiabatic quantum pumping
Quantum pumping through mesoscopic quantum dots is known to be enhanced by
resonant transmission. The pumped charge is close to an integer number of
electrons when the pumping contour surrounds a resonance, but the transmission
remains small on the contour. For non-interacting electrons, we give a
quantitative account of the detailed exchange of electrons between the dot and
the leads (to the electron reservoirs) during a pumping cycle. Near isolated
distinct resonances, we use approximate Breit-Wigner expressions for the dot's
Green function to discuss the loading/unloading picture of the pumping: the
fractional charge exchanged between the dot and each lead through a single
resonance point is related to the relative couplings of the dot and the leads
at this resonance. If each resonance point along the pumping contour is
dominated by the coupling to a single lead (which also implies a very small
transmission), then the crossing of each such resonance results in a single
electron exchange between the dot and that lead, ending up with a net quantized
charge. When the resonance approximation is valid, the fractional charges can
also be extracted from the peaks of the transmissions between the various
leads.Comment: 10 pages, 4 figure
Bag-of-Colors for Biomedical Document Image Classification
The number of biomedical publications has increased noticeably in the last 30 years. Clinicians and medical researchers regularly have unmet information needs but require more time for searching than is usually available to find publications relevant to a clinical situation. The techniques described in this article are used to classify images from the biomedical open access literature into categories, which can potentially reduce the search time. Only the visual information of the images is used to classify images based on a benchmark database of ImageCLEF 2011 created for the task of image classification and image retrieval. We evaluate particularly the importance of color in addition to the frequently used texture and grey level features.
Results show that bags–of–colors in combination with the Scale Invariant Feature Transform (SIFT) provide an image representation allowing to improve the classification quality. Accuracy improved from 69.75% of the best system in ImageCLEF 2011 using visual information, only, to 72.5% of the system described in this paper. The results highlight the importance of color for the classification of biomedical images
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