892 research outputs found
Mixed Protein Carriers for Modulating DNA Release
Aqueous mixtures of oppositely charged polyelectrolytes undergo associative phase separation, resulting in coacervation, gelation, or precipitation. This phenomenon has been exploited in forming DNA gel particles by interfacial diffusion. We report here the formation of DNA gel particles by mixing solutions of double-stranded DNA with aqueous solutions containing two cationic proteins, lysozyme and protamine sulfate. The effect of the lysozyme/protamine ratio on the degree of DNA entrapment, surface morphology, swelling−deswelling behavior, and kinetics of DNA release has been investigated. By mixing the two proteins, we obtain particles that display higher loading efficiency and loading capacity values, in comparison to those obtained in single-protein systems. Examination of the release profiles has shown that in mixed protein particles, complex, dual-stage release kinetics is obtained. The overall release profile is dependent on the lysozyme/protamine ratio. The obtained profiles, or segments of them, are accuratelly fitted using the zero-order and first-order models, and the Weibull function. Fluorescence microscopy studies have suggested that the formation of these particles is associated with the conservation of the secondary structure of DNA. This study presents a new platform for controlled release of DNA from DNA gel particles formed by interfacial diffusion
Determinación de agua en alcoholes usando como reactivo un tiocianocomplejo del cobalto
En el presente trabajo se propone un método cuantitativopara la determinación de agua en etanol, basado en las variaciones de intensidad del color azul que presentan las soluciones hidroalcohólicas del complejo tetratiocianocobaltato(II) de potasio.El compuesto de coordinación se prepara triturando intimamente en un mortero cantidades estequiométricas desulfato de cobalto(II) y tiocianato de potasio. El complejoobtenido se extrae con etanol, y el sulfato de potasioremanente es insoluble en este medio. El extracto alcohólicofiltrado se evapora lentamente y los cristales azulesobtenidos se mantienen en desecador conteniendo ácido sulfúrico.El objetivo del presente trabajo es desarrollar un métodocuantitativo usando la espectrofotometría molecular, para determinar la concentración de agua en alcoholes hidratados.Esta técnica es de aplicación a limitadas cantidades de agua en alcohol etílico (3,6 -11,2 %) pues a mayores concentracionesde agua en la solución complejo-etanol, se descompone el complejo, liberando el ión cobalto(II) que colorea de rosado la solución
Infrared identification of hard X-ray sources in the Galaxy
The nature of the low- to intermediate-luminosity (LX ∼ 1032–34 erg s−1) source population revealed in hard band (2–10 keV) X-ray surveys of the Galactic plane is poorly understood. To overcome such problem, we cross-correlated the XMM–Newton 3XMM-DR4 survey with the infrared Two Micron All Sky Survey and Galactic Legacy Infrared Mid-Plane Survey Extraordinaire catalogues. We identified reliable X-ray–infrared associations for 690 sources. We selected 173 sources having hard X-ray spectra, typical of hard X-ray high-mass stars (kT > 5 keV), and 517 sources having soft X-ray spectra, typical of active coronae. About 18 per cent of the soft sources are classified in the literature: ∼91 per cent as stars, with a minor fraction of Wolf–Rayet (WR) stars. Roughly 15 per cent of the hard sources are classified in the literature: ∼68 per cent as high-mass X-ray stars single or in binary systems (WR, Be and high-mass X-ray binaries – HMXBs), with a small fraction of G and B stars. We carried out infrared spectroscopic pilot observations at the William Herschel Telescope for five hard X-ray sources. Three of them are high-mass stars with spectral types WN7-8h, Ofpe/WN9 and Be, and LX ∼ 1032–1033erg s−1. One source is a colliding-wind binary, while another source is a colliding-wind binary or a supergiant fast X-ray transient in quiescence. The Be star is a likely γ-Cas system. The nature of the other two X-ray sources is uncertain. The distribution of hard X-ray sources in the parameter space made of X-ray hardness ratio, infrared colours and X-ray-to-infrared flux ratio suggests that many of the unidentified sources are new γ-Cas analogues, WRs and low LX HMXBs. However, the nature of the X-ray population with Ks ≥ 11 and average X-ray-to-infrared flux ratio remains unconstrained.We acknowledge financial support from the ARCHES project (7th Framework of the
European Union, no. 313146). FJC acknowledges financial support from the Spanish Ministerio de Economía y Competitividad under project AYA2012-31447.Peer Reviewe
Small molecules containing chalcogen elements (S, Se, Te) as new warhead to fight neglected tropical diseases
Neglected tropical diseases (NTDs) encompass a group of infectious diseases with a protozoan etiology, high
incidence, and prevalence in developing countries. As a result, economic factors constitute one of the main
obstacles to their management. Endemic countries have high levels of poverty, deprivation and marginalization
which affect patients and limit their access to proper medical care. As a matter of fact, statistics remain un-
collected in some affected areas due to non-reporting cases. World Health Organization and other organizations
proposed a plan for the eradication and control of the vector, although many of these plans were halted by the
COVID-19 pandemic. Despite of the available drugs to treat these pathologies, it exists a lack of effectiveness
against several parasite strains. Treatment protocols for diseases such as American trypanosomiasis (Chagas
disease), leishmaniasis, and human African trypanosomiasis (HAT) have not achieved the desired results. Un-
fortunately, these drugs present limitations such as side effects, toxicity, teratogenicity, renal, and hepatic
impairment, as well as high costs that have hindered the control and eradication of these diseases. This review
focuses on the analysis of a collection of scientific shreds of evidence with the aim of identifying novel chalcogen-
derived molecules with biological activity against Chagas disease, leishmaniasis and HAT. Compounds illustrated
in each figure share the distinction of containing at least one chalcogen element. Sulfur (S), selenium (Se), and
tellurium (Te) have been grouped and analyzed in accordance with their design strategy, chemical synthesis
process and biological activity. After an exhaustive revision of the related literature on S, Se, and Te compounds,
183 compounds presenting excellent biological performance were gathered against the different causative agents
of CD, leishmaniasis and HAT
Re-use of construction and demolition residues and industrial wastes for the elaboration or recycled eco-efficient concretes
[EN] Production of residues from industries and construction and demolition sectors has increased during last years. The
total amount of debris produced according to different estimations reaches values close to 42 million tonnes yr
–1
. Much
of this waste has been thrown to landfill, without considering its potential for reuse, recycling or valuation. The aim
of this research is to describe some of the physical and mechanical properties of different laboratory-mixed concretes,
using various proportions of additional materials recovered from industrial waste and demolition rubble. The added
materials are included either as admixtures (forestry residues, cork dust, steel fibre) or in partial substitution of natural
aggregates (wire from electrical residues, tyre rubber, white ceramic, sanitary porcelain or shale). The laboratory tests
have followed the standard EN protocols. Assay results were variable according to the nature of the material added to
the mix: organic materials and shale, despite the steel fibre reinforcement, reduce the compression strength, but are
suitable for the manufacture of lightweight concrete for agricultural pavements, with certain flexion resistance and a
relatively good behaviour to impact. The substitution of natural aggregates with ceramic and porcelain wastes produces
a significant increase in compression resistance, making them suitable for the manufacture of concrete with
characteristic resistances above 40 MPa, which can be used both for structures or other agricultural elements: separators,
feeders, slat floors. As a conclusion can be stated the possibility of reuse these wastes for the production of structural
or non-structural concrete, with different applications in agricultural engineerin
On the "Mandelbrot set" for a pair of linear maps and complex Bernoulli convolutions
We consider the "Mandelbrot set" for pairs of complex linear maps,
introduced by Barnsley and Harrington in 1985 and studied by Bousch, Bandt and
others. It is defined as the set of parameters in the unit disk such
that the attractor of the IFS is
connected. We show that a non-trivial portion of near the imaginary axis is
contained in the closure of its interior (it is conjectured that all non-real
points of are in the closure of the set of interior points of ). Next we
turn to the attractors themselves and to natural measures
supported on them. These measures are the complex analogs of
much-studied infinite Bernoulli convolutions. Extending the results of Erd\"os
and Garsia, we demonstrate how certain classes of complex algebraic integers
give rise to singular and absolutely continuous measures . Next we
investigate the Hausdorff dimension and measure of , for
in the set , for Lebesgue-a.e. . We also obtain partial results on
the absolute continuity of for a.e. of modulus greater
than .Comment: 22 pages, 5 figure
Post-common envelope binaries from SDSS - XVI. Long orbital period systems and the energy budget of CE evolution
Virtually all close compact binary stars are formed through common-envelope
(CE) evolution. It is generally accepted that during this crucial evolutionary
phase a fraction of the orbital energy is used to expel the envelope. However,
it is unclear whether additional sources of energy, such as the recombination
energy of the envelope, play an important role. Here we report the discovery of
the second and third longest orbital period post-common envelope binaries
(PCEBs) containing white dwarf (WD) primaries, i.e. SDSSJ121130.94-024954.4
(Porb = 7.818 +- 0.002 days) and SDSSJ222108.45+002927.7 (Porb = 9.588 +- 0.002
days), reconstruct their evolutionary history, and discuss the implications for
the energy budget of CE evolution. We find that, despite their long orbital
periods, the evolution of both systems can still be understood without
incorporating recombination energy, although at least small contributions of
this additional energy seem to be likely. If recombination energy significantly
contributes to the ejection of the envelope, more PCEBs with relatively long
orbital periods (Porb >~ 1-3 day) harboring massive WDs (Mwd >~ 0.8 Msun)
should exist.Comment: Accepted for publication in MNRAS. 8 pages, 6 figures and 4 table
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