147 research outputs found
A New Kind of Quinonic-Antibiotic Useful Against Multidrug-Resistant S. aureus and E. faecium Infections
Indexación: Scopus.A rapid emergence of resistant bacteria is occurring worldwide, endangering the efficacy of antibiotics and reducing the therapeutic arsenal available for treatment of infectious diseases. In the present study, we developed a new class of compounds with antibacterial activity obtained by a simple, two step synthesis and screened the products for in vitro antibacterial activity against ATCC® strains using the broth microdilution method. The compounds exhibited minimum inhibitory concentrations (MIC) of 1⁻32 μg/mL against Gram-positive ATCC® strains. The structure⁻activity relationship indicated that the thiophenol ring is essential for antibacterial activity and the substituents on the thiophenol ring module, for antibacterial activity. The most promising compounds detected by screening were tested against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VREF) clinical isolates. We found remarkable activity against VREF for compounds 7 and 16, were the MIC50/90 were 2/4 µg/mL and 4/4 µg/mL, respectively, while for vancomycin the MIC50/90 was 256/512 µg/mL. Neither compound affected cell viability in any of the mammalian cell lines at any of the concentrations tested. These in vitro data show that compounds 7 and 16 have an interesting potential to be developed as new antibacterial drugs against infections caused by VREF.https://www.mdpi.com/1420-3049/23/7/177
Predicting blunt cerebrovascular injury in pediatric trauma: Validation of the Utah Score
Risk factors for blunt cerebrovascular injury (BCVI) may differ between children and adults, suggesting that children at low risk for BCVI after trauma receive unnecessary computed tomography angiography (CTA) and high-dose radiation. We previously developed a score for predicting pediatric BCVI based on retrospective cohort analysis. Our objective is to externally validate this prediction score with a retrospective multi-institutional cohort. We included patients who underwent CTA for traumatic cranial injury at four pediatric Level I trauma centers. Each patient in the validation cohort was scored using the “Utah Score” and classified as high or low risk. Before analysis, we defined a misclassification rate <25% as validating the Utah Score. Six hundred forty-five patients (mean age 8.6 ± 5.4 years; 63.4% males) underwent screening for BCVI via CTA. The validation cohort was 411 patients from three sites compared with the training cohort of 234 patients. Twenty-two BCVIs (5.4%) were identified in the validation cohort. The Utah Score was significantly associated with BCVIs in the validation cohort (odds ratio 8.1 [3.3, 19.8], p < 0.001) and discriminated well in the validation cohort (area under the curve 72%). When the Utah Score was applied to the validation cohort, the sensitivity was 59%, specificity was 85%, positive predictive value was 18%, and negative predictive value was 97%. The Utah Score misclassified 16.6% of patients in the validation cohort. The Utah Score for predicting BCVI in pediatric trauma patients was validated with a low misclassification rate using a large, independent, multicenter cohort. Its implementation in the clinical setting may reduce the use of CTA in low-risk patients
The H{\alpha} Luminosity Function of Galaxies at z {\sim} 4.5
We present the H{\alpha} luminosity function (LF) derived from a large sample
of Lyman break galaxies at z {\sim} 4.5 over the GOODS-South and North fields.
This study makes use of the new, full-depth Spitzer/IRAC [3.6] and [4.5]
imaging from the GOODS Re-ionization Era wide-Area Treasury from the Spitzer
program. The H{\alpha} flux is derived from the offset between the continuum
flux estimated from the best-fit spectral energy distribution, and the observed
photometry in IRAC [3.6]. From these measurements, we build the H{\alpha} LF
and study its evolution providing the best constraints of this property at high
redshift, where spectroscopy of H{\alpha} is not yet available. Schechter
parameterizations of the H{\alpha} LF show a decreasing evolution of
{\Phi^\star} with redshift, increasing evolution in L{^\star}, and no
significant evolution in the faint-end slope at high z. We find that star
formation rates (SFRs) derived from H{\alpha} are higher than those derived
from the rest-frame UV for low SFR galaxies but the opposite happens for the
highest SFRs. This can be explained by lower mass galaxies (also lower SFR)
having, on average, rising star formation histories (SFHs), while at the
highest masses the SFHs may be declining. The SFR function is steeper, and
because of the excess SFR(H{\alpha}) compared to SFR(UV) at low SFRs, the SFR
density estimated from H{\alpha} is higher than the previous estimates based on
UV luminosities.Comment: Astrophysical Journal, Accepted, 17 pages, 16 figure
Functionalization of gold nanostars with cationic ß-cyclodextrin-based polymer for drug co-loading and SERS monitoring
Gold nanostars (AuNSs) exhibit modulated plasmon resonance and have a high SERS enhancement factor. However, their low colloidal stability limits their biomedical application as a nanomaterial. Cationic ß-cyclodextrin-based polymer (CCD/P) has low cytotoxicity, can load and transport drugs more efficiently than the corresponding monomeric form, and has an appropriate cationic group to stabilize gold nanoparticles. In this work, we functionalized AuNSs with CCD/P to load phenylethylamine (PhEA) and piperine (PIP) and evaluated SERS-based applications of the products. PhEA and PIP were included in the polymer and used to functionalize AuNSs, forming a new AuNS-CCD/P-PhEA-PIP nanosystem. The system was characterized by UV–VIS, IR, and NMR spectroscopy, TGA, SPR, DLS, zeta potential analysis, FE-SEM, and TEM. Additionally, Raman optical activity, SERS analysis and complementary theoretical studies were used for characterization. Minor adjustments increased the colloidal stability of AuNSs. The loading capacity of the CCD/P with PhEA-PIP was 95 ± 7%. The physicochemical parameters of the AuNS-CCD/P-PhEA-PIP system, such as size and Z potential, are suitable for potential biomedical applications Raman and SERS studies were used to monitor PhEA and PIP loading and their preferential orientation upon interaction with the surface of AuNSs. This unique nanomaterial could be used for simultaneous drug loading and SERS-based detection
An Affordability Comparison Tool (ACT) for Space Transportation
NASA bas recently emphasized the importance of affordability for Commercial Crew Development Program (CCDP), Space Launch Systems (SLS) and Multi-Purpose Crew Vehicle (MPCV). System architects and designers are challenged to come up with architectures and designs that do not bust the budget. This paper describes the Affordability Comparison Tool (ACT) analyzes different systems or architecture configurations for affordability that allows for a comparison of: total life cycle cost; annual recurring costs, affordability figures-of-merit, such as cost per pound, cost per seat, and cost per flight, as well as productivity measures, such as payload throughput. Although ACT is not a deterministic model, the paper develops algorithms and parametric factors that use characteristics of the architectures or systems being compared to produce important system outcomes (figures-of-merit). Example applications of outcome figures-of-merit are also documented to provide the designer with information on the relative affordability and productivity of different space transportation applications
Co2TiO4/reduced graphene oxide nanohybrids for electrochemical sensing applications
For the first time, the synthesis, characterization, and analytical application for hydrogen peroxide quantification of the hybrid materials of Co2TiO4 (CTO) and reduced graphene oxide (RGO) is reported, using in situ (CTO/RGO) and ex situ (CTO+RGO) preparations. This synthesis for obtaining nanostructured CTO is based on a one-step hydrothermal synthesis, with new precursors and low temperatures. The morphology, structure, and composition of the synthesized materials were examined using scanning electron microscopy, X-ray diffraction (XRD), neutron powder diffraction (NPD), and X-ray photoelectron spectroscopy (XPS). Rietveld refinements using neutron diffraction data were conducted to determine the cation distributions in CTO. Hybrid materials were also characterized by Brunauer-Emmett-Teller adsorption isotherms, Scanning Electron microscopy, and scanning electrochemical microscopy. From an analytical point of view, we evaluated the electrochemical reduction of hydrogen peroxide on glassy carbon electrodes modified with hybrid materials. The analytical detection of hydrogen peroxide using CTO/RGO showed 11 and 5 times greater sensitivity in the detection of hydrogen peroxide compared with that of pristine CTO and RGO, respectively, and a two-fold increase compared with that of the RGO+CTO modified electrode. These results demonstrate that there is a synergistic effect between CTO and RGO that is more significant when the hybrid is synthetized through in situ methodology.Fil: Venegas, Constanza J.. Universidad de Chile; Chile. Universidad de Santiago de Chile; ChileFil: Gutierrez, Fabiana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Eguílaz Rubio, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Marco, José F.. Consejo Superior de Investigaciones Científicas; EspañaFil: Reeves-McLaren, Nik. University Of Sheffield; Reino UnidoFil: Rivas, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Ruiz-León, Domingo. Universidad de Santiago de Chile; ChileFil: Bollo, Soledad. Universidad de Chile; Chil
ALMACAL. XI. Over-densities as signposts to proto-clusters? A cautionary tale
It may be unsurprising that the most common approach to finding
proto-clusters is to search for over-densities of galaxies. Upgrades to
submillimetre (submm) interferometers and the advent of the James Webb Space
Telescope will soon offer the opportunity to find more distant candidate
proto-clusters in deep sky surveys without any spectroscopic confirmation. In
this letter, we report the serendipitous discovery of an extremely dense region
centred on the blazar, J0217-0820, at z=0.6 in the ALMACAL sky survey. Its
density is eight times higher than that predicted by blind submm surveys. Among
the seven submm-bright galaxies, three are as bright as conventional
single-dish submm galaxies, with S_870um > 3mJy. The over-density is thus
comparable to the densest known and confirmed proto-cluster cores. However,
their spectra betray a wide range of redshifts. We investigate the likelihood
of line-of-sight projection effects using light cones from cosmological
simulations, finding that the deeper we search, the higher the chance that we
will suffer from such projection effects. The extreme over-density around
J0217-0820 demonstrates the strong cosmic variance we may encounter in the deep
submm surveys. Thus, we should also question the fidelity of galaxy
proto-cluster candidates selected via over-densities of galaxies, where the
negative K correction eases the detection of dusty galaxies along an
extraordinarily extended line of sight.Comment: 7 pages, 5 figures, update with the accepted versio
Políticas de software libre en el Estado argentino
Este estudio tiene como objetivo conocer la situación actual del software libre en los organismos públicos argentinos con la finalidad de identificar pautas para desarrollar políticas de uso de herramientas FLOSS en los mismos.
Se coincide que uno de los ámbitos más favorables para la difusión del software libre son los organismos públicos. Experiencias exitosas como las emprendidas por entidades gubernamentales de España y Alemania, y de países más cercanos como Brasil y Venezuela, demuestran que son una alternativa atractiva para ser imitada por los entes estatales de nuestro país.
Diversos estudios nos dicen que las herramientas FLOSS tienen una ecuación favorable cuando se las compara con los productos de software comercial equivalentes; esta ecuación favorable está basada no sólo variables técnicas y económicas, sino también socio-políticas.
En nuestros trabajos de investigación anteriores abordamos el fenómeno del FLOSS desde la óptica de las organizaciones privadas usuarias de software libre en nuestro medio. Nuestra propuesta para el ciclo 2010/11 es continuar el análisis del movimiento FLOSS, enfocando nuestra investigación en el comportamiento de los organismos públicos argentinos como usuarios de productos y servicios open source.Sociedad Argentina de Informática e Investigación Operativ
MUSE-ALMA Halos XI: Gas flows in the circumgalactic medium
The flow of gas into and out of galaxies leaves traces in the circumgalactic
medium which can then be studied using absorption lines towards background
quasars. We analyse 27 log(N_HI) > 18.0 HI absorbers at z = 0.2 to 1.4 from the
MUSE-ALMA Halos survey with at least one galaxy counterpart within a line of
sight velocity of +/-500 km s^{-1}. We perform 3D kinematic forward modelling
of these associated galaxies to examine the flow of dense, neutral gas in the
circumgalactic medium. From the VLT/MUSE, HST broadband imaging and VLT/UVES
and Keck/HIRES high-resolution UV quasar spectroscopy observations, we compare
the impact parameters, star-formation rates and stellar masses of the
associated galaxies with the absorber properties. We find marginal evidence for
a bimodal distribution in azimuthal angles for strong HI absorbers, similar to
previous studies of the MgII and OVI absorption lines. There is no clear
metallicity dependence on azimuthal angle and we suggest a larger sample of
absorbers are required to fully test the relationship predicted by cosmological
hydrodynamical simulations. A case-by-case study of the absorbers reveals that
ten per cent of absorbers are consistent with gas accretion, up to 30 per cent
trace outflows while the remainder trace gas in the galaxy disk, the intragroup
medium and low-mass galaxies below the MUSE detection limit. Our results
highlight that the baryon cycle directly affects the dense neutral gas required
for star-formation and plays a critical role in galaxy evolution.Comment: 13 pages, 6 figures, 12 pages of appendix. Accepted for publication
in MNRA
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