1,026 research outputs found
Self-assembly of bent-core amphiphiles joining the ethylene-oxide/lithium ion tandem
The synthesis, supramolecular self-assembly and structural characterization of a new family of tetraethylene oxide (TEG)-based bent-core compounds and their 1/1 lithium-containing complexes are reported. TEG-based bent-core amphiphiles, even joining the TEG/Li+ tandem, are suitable building-blocks to achieve supramolecular nanostructures, in some cases showing chiral features from achiral molecules either in the mesophase or in solvents. The thermal and liquid crystal behavior of these materials studied by polarizing optical microscopy and X-ray diffraction confirmed that Li-based materials stabilized polar smectic C and helical nanofilament-type mesophases, in contrast to the non-liquid crystalline pure TEG-compounds. Alternatively, both the pure amphiphiles and the lithium-doped materials self-assemble into physical gels in non-polar solvents, displaying three-dimensional networks composed of long fibers with lamellar molecular organizations as shown by transmission electron microscopy and X-ray diffraction. Interestingly, biphenyl- and azobenzene-based bent core amphiphiles aggregate in solvent into chiral nanostructured morphologies with supramolecular trends comparable to their molecular arrangement in their liquid crystalline phases
Comparative study of real-time pcr (Taqman probe and sybr green), serological techniques (elisa, ifa and dat) and clinical signs evaluation, for the diagnosis of canine leishmaniasis in experimentally infected dogs
Canine leishmaniasis (CanL) diagnosis is not fully resolved. Currently, two specific methodologies are in continuous development, the detection of the parasite DNA or RNA in target organs and the detection of specific antibodies against Leishmania sp. For a correct diagnosis, it has been shown that the joint use of this type of test is necessary. In this work, a Sybr Green and a TaqMan Probe based on real time PCRs (qPCR) was performed for the detection of Leishmania sp. in order to correlate the results with clinicopathological and serological evaluations (IFA, ELISA and DAT) to propose an optimal biological sample to be used to detect the parasite in both early and late stages of the infection. A total of four samples were processed: conjunctival swabs, popliteal lymph node aspirates, bone marrow aspirates, and peripheral blood from experimentally infected dogs belonging to a larger study. Our results indicated that a single non-invasive sample (conjunctival swab) and the application of both types of qPCR would be reliable for determining Leishmania infection as well as the disease stage in dogs, thus avoiding bone marrow, lymph node aspirate or blood samples collection. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/)
Inherently safer design and optimization of intensified separation processes for furfural production
Inherently Safer Design and Optimization of Intensified Separation Processes for Furfural Production
Currently
furfural production has been the subject of increased
interest because it is a biobased chemical able to compete with fossil-based
chemicals. Furfural is characterized by flammability, explosion, and
toxicity properties. Improper handling and process design can lead
to catastrophic accidents. Hence it is of most importance to use inherent
safety concepts during the design stage. This work is the first to
present several new downstream separation processes for furfural purification,
which are designed using an optimization approach that simultaneously
considers safety criteria in addition to the total annual cost and
the eco-indicator 99. The proposed schemes include thermally coupled
configuration, thermodynamic equivalent configuration, dividing-wall
column, and a heat integrated configuration. These are compared with
the traditional separation process of furfural known as the Quaker
Oats Process. The results show that because of a large amount of water
present in the feed, similar values are obtained for total annual
cost and eco-indicator 99 in all cases. Moreover, the topology of
the processes has an important role in the safety criteria. The thermodynamic
equivalent configuration resulted as the safest alternative with a
40% reduction of the inherent risk with respect to the Quaker Oats
Process, and thus it is the safest option to purify furfural
Automated detection of parenchymal changes of ischemic stroke in non-contrast computer tomography: a fuzzy approach
The detection of ischemic changes is a primary task in the interpretation of brain Computer Tomography (CT) of patients suffering from neurological disorders. Although CT can easily show these lesions, their interpretation may be difficult when the lesion is not easily recognizable. The gold standard for the detection of acute stroke is highly variable and depends on the experience of physicians. This research proposes a new method of automatic detection of parenchymal changes of ischemic stroke in Non-Contrast CT. The method identifies non-pathological cases (94 cases, 40 training, 54 test) based on the analysis of cerebral symmetry. Parenchymal changes in cases with abnormalities (20 cases) are detected by means of a contralateral analysis of brain regions. In order to facilitate the evaluation of abnormal regions, non-pathological tissues in Hounsfield Units were characterized using fuzzy logic techniques. Cases of non-pathological and stroke patients were used to discard/confirm abnormality with a sensitivity (TPR) of 91% and specificity (SPC) of 100%. Abnormal regions were evaluated and the presence of parenchymal changes was detected with a TPR of 96% and SPC of 100%. The presence of parenchymal changes of ischemic stroke was detected by the identification of tissues using fuzzy logic techniques. Because of abnormal regions are identified, the expert can prioritize the examination to a previously delimited region, decreasing the diagnostic time. The identification of tissues allows a better visualization of the region to be evaluated, helping to discard or confirm a stroke.Peer ReviewedPostprint (author's final draft
Pneumocystis carinii. Presentación de caso clínico y revisión de la bibliografía principal
El Pneumocystis Carinii es un microorganismo patógeno, oportunista, causante de neumonía en los pacientes inmunodeprimidos, cuya presentación clínica es insidiosa, aparentando un cuadro respiratorio simple caracterizado por fiebre, rinorrea, aleteo nasal; no responde favorablemente al tratamiento convencional, deteriorando el estado general del paciente. Estos pacientes son ingresados para estudios complementarios, especialmente de tipo radiológico lo cual nos revela imágenes de infiltrados pulmonares parahiliares difusos, típicas de infección por pneumocystis carinii, aproximadamente en el 90 % de los casos, en pacientes inmunodeprimidos por HIV. Describimos el caso de un lactante menor que fue atendido en el servicio de neonatología del hospital “Roberto Gilbert Elizalde” con neumonía por Pneumocystis Carinii inmunocomprometido por HIV
Aperture effects on the oxygen abundance determinations from CALIFA data
This paper aims at providing aperture corrections for emission lines in a
sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey
(CALIFA) database. In particular, we explore the behavior of the
log([OIII]5007/Hbeta)/([NII]6583/Halpha) (O3N2) and log[NII]6583/Halpha (N2)
flux ratios since they are closely connected to different empirical
calibrations of the oxygen abundances in star forming galaxies.
We compute median growth curves of Halpha, Halpha/Hbeta, O3N2 and N2 up to
2.5R_50 and 1.5 disk R_eff. The growth curves simulate the effect of observing
galaxies through apertures of varying radii. The median growth curve of the
Halpha/Hbeta ratio monotonically decreases from the center towards larger
radii, showing for small apertures a maximum value of ~10% larger than the
integrated one. The median growth curve of N2 shows a similar behavior,
decreasing from the center towards larger radii. No strong dependence is seen
with the inclination, morphological type and stellar mass for these growth
curves. Finally, the median growth curve of O3N2 increases monotonically with
radius. However, at small radii it shows systematically higher values for
galaxies of earlier morphological types and for high stellar mass galaxies.
Applying our aperture corrections to a sample of galaxies from the SDSS
survey at 0.02<=z<=0.3 shows that the average difference between fiber-based
and aperture corrected oxygen abundances, for different galaxy stellar mass and
redshift ranges, reaches typically to ~11%, depending on the abundance
calibration used. This average difference is found to be systematically biased,
though still within the typical uncertainties of oxygen abundances derived from
empirical calibrations. Caution must be exercised when using observations of
galaxies for small radii (e.g. below 0.5R_eff) given the high dispersion shown
around the median growth curves.Comment: Accepted for publication in Ap
Turnover time of fluorescent dissolved organic matter in the dark global ocean
Research articleMarine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on
Earth. In the dark ocean (4200 m), most of this carbon is refractory DOM. This refractory
DOM, largely produced during microbial mineralization of organic matter, includes humic-like
substances generated in situ and detectable by fluorescence spectroscopy. Here we show two
ubiquitous humic-like fluorophores with turnover times of 435±41 and 610±55 years, which
persist significantly longer than the B350 years that the dark global ocean takes to renew. In
parallel, decay of a tyrosine-like fluorophore with a turnover time of 379±103 years is also
detected. We propose the use of DOM fluorescence to study the cycling of resistant DOM
that is preserved at centennial timescales and could represent a mechanism of carbon
sequestration (humic-like fraction) and the decaying DOM injected into the dark global
ocean, where it decreases at centennial timescales (tyrosine-like fraction).Versión del editor10,015
Seminar Users in the Arabic Twitter Sphere
We introduce the notion of "seminar users", who are social media users
engaged in propaganda in support of a political entity. We develop a framework
that can identify such users with 84.4% precision and 76.1% recall. While our
dataset is from the Arab region, omitting language-specific features has only a
minor impact on classification performance, and thus, our approach could work
for detecting seminar users in other parts of the world and in other languages.
We further explored a controversial political topic to observe the prevalence
and potential potency of such users. In our case study, we found that 25% of
the users engaged in the topic are in fact seminar users and their tweets make
nearly a third of the on-topic tweets. Moreover, they are often successful in
affecting mainstream discourse with coordinated hashtag campaigns.Comment: to appear in SocInfo 201
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