2,196 research outputs found
Model Design of Wind/PV/Fossil-Fuel Hybrid Systems
This paper presents the analysis and design of a mathematical model for a hybrid-power generation system consisting of a photovoltaic array, wind-turbines, a batterybank and a backup fossil-fuel generator. The static mathematical models of each element are validated by comparing them with field-data obtained in an experimental hybrid generation system in Pachuca, Mexico. Two different state-of-charge models were simulated and compared. The results are presented in this paper. The main purpose of this work is the development of a fuzzy-supervisory-controller for small hybrid-systems
Synthesis of Fe-Au nanoparticles through phase separation using the gas aggregation technique
During the last veers different type of magnetic materials have been obtained either alloys or nanopor-ritlcs with severall metalllics shells. These particle exhibt better magnetic properties, are biocompatible and have optical properties due to their shell noble metal layer, this is possible, to synthesize heterostructured nanoparticles with care/shell structure by using sputtering targets consisting of alloys of different materials. In the case of such materials have different surface energies and atomic sizes, there are diffusion processes which lead to the formation of structured nanoparticles with a shell and core having different composition. In this work we will show the results obtained about Fe-Au nanoparticles grown by I he gas aggregation technique, using magnetron sputering sources. Colloids prepared from sputtered deposits of heterostructed nanoparticles exhibit less aggregation when compared to suspensions obtained from pure magnetic materials. Spectrophotometry measurement show the presence of gold at the surface of the nanoparticles. Magnetic properties of such particle are analyzed by VSM. Compasition end structural analysis are studied by TEM and ÉDA
Organics in Space: Results from Space Exposure Platforms and Nanosatellites
A series of successful laboratory astrophysics experiments performed on International Space Station(ISS) external platforms such as EXPOSE have provided insights into the evolution of organic and biological materials in space and planetary environments. The study of the reactions, destruction, and longevity of organics in the space environment is of fundamental interest. To provide an accurate outer space environment for extended durations, exposure experiments in low Earth orbit have been conducted in the last decades in order to examine the consequences of actual space conditions including combinations of solar and cosmic radiation, space vacuum, and microgravity. The OOREOS (OrganismORganic Exposure to Orbital Stresses) nanosatellite studied in situ during the 6-month primary and 1-year extended mission the photochemical processing of selected PAHs in low Earth orbit (650 km altitude); results were autonomously telemetered to Earth. We report on the methods and flight preparation of samples for space exposure platforms and results on the stability of organic thin-films. The UV-vis degradation process of thin-films was recorded over time, which revealed intriguing and counter-intuitive photolytic kinetics that will be re-investigated on the ISS in a space environment
RNase H2, mutated in Aicardi-Goutières syndrome, promotes LINE-1 retrotransposition
Long INterspersed Element class 1 (LINE-1) elements are a type of
abundant retrotransposons active in mammalian genomes. An
average human genome contains ~100 retrotransposition-competent
LINE-1s, whose activity is influenced by the combined action
of cellular repressors and activators. TREX1, SAMHD1 and ADAR1
are known LINE-1 repressors and when mutated cause the autoinflammatory
disorder Aicardi-Goutières syndrome (AGS). Mutations
in RNase H2 are the most common cause of AGS, and its activity
was proposed to similarly control LINE-1 retrotransposition. It has
therefore been suggested that increased LINE-1 activity may be
the cause of aberrant innate immune activation in AGS. Here, we
establish that, contrary to expectations, RNase H2 is required for
efficient LINE-1 retrotransposition. As RNase H1 overexpression
partially rescues the defect in RNase H2 null cells, we propose a
model in which RNase H2 degrades the LINE-1 RNA after reverse
transcription, allowing retrotransposition to be completed. This
also explains how LINE-1 elements can retrotranspose efficiently
without their own RNase H activity. Our findings appear to be at
odds with LINE-1-derived nucleic acids driving autoinflammation
in AGS.M.B.-G. is funded by a “Formacion Profesorado
Universitario” (FPU) PhD fellowship from the Government of Spain (MINECO,
Ref FPU15/03294), and this paper is part of her thesis project (“Epigenetic
control of the mobility of a human retrotransposon”). R.V.-A. is funded by a
PFIS Fellowship from the Government of Spain (ISCiii, FI16/00413). O.M. is
funded by an EMBO Long-Term Fellowship (ALTF 7-2015), the European
Commission FP7 (Marie Curie Actions, LTFCOFUND2013, GA-2013-609409) and
the Swiss National Science Foundation (P2ZHP3_158709). S.R.H. is funded by
the Government of Spain (MINECO, RYC-2016-21395 and SAF2015-71589-P).
A.P.J’s laboratory is supported by the UK Medical Research Council (MRC University Unit grant U127527202). J.L.G.P’s laboratory is supported by CICEFEDER-
P12-CTS-2256, Plan Nacional de I+D+I 2008-2011 and 2013-2016 (FISFEDER-
PI14/02152), PCIN-2014-115-ERA-NET NEURON II, the European
Research Council (ERC-Consolidator ERC-STG-2012-233764), by an International
Early Career Scientist grant from the Howard Hughes Medical Institute
(IECS-55007420), by The Wellcome Trust-University of Edinburgh Institutional
Strategic Support Fund (ISFF2) and by a private donation from Ms Francisca
Serrano (Trading y Bolsa para Torpes, Granada, Spain)
Silver nanoparticles-composing alginate/gelatine hydrogel improves wound healing in vivo
Polymer hydrogels have been suggested as dressing materials for the treatment of cutaneous wounds and tissue revitalization. In this work, we report the development of a hydrogel composed of natural polymers (sodium alginate and gelatin) and silver nanoparticles (AgNPs) with recognized antimicrobial activity for healing cutaneous lesions. For the development of the hydrogel, different ratios of sodium alginate and gelatin have been tested, while different concentrations of AgNO3 precursor (1.0, 2.0, and 4.0 mM) were assayed for the production of AgNPs. The obtained AgNPs exhibited a characteristic peak between 430450 nm in the ultraviolet-visible (UVVis) spectrum suggesting a spheroidal form, which was confirmed by Transmission Electron Microscopy (TEM). Fourier Transform Infra-red (FTIR) analysis suggested the formation of strong intermolecular interactions as hydrogen bonds and electrostatic attractions between polymers, showing bands at 2920, 2852, 1500, and 1640 cm1. Significant bactericidal activity was observed for the hydrogel, with a Minimum Inhibitory Concentration (MIC) of 0.50 µg/mL against Pseudomonas aeruginosa and 53.0 µg/mL against Staphylococcus aureus. AgNPs were shown to be non-cytotoxic against fibroblast cells. The in vivo studies in female Wister rats confirmed the capacity of the AgNP-loaded hydrogels to reduce the wound size compared to uncoated injuries promoting histological changes in the healing tissue over the time course of wound healing, as in earlier development and maturation of granulation tissue. The developed hydrogel with AgNPs has healing potential for clinical applications.This research received funding from the Coordenação Aperfeiçoamento de Pessoal de Nivel Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de Sergipe (FAPITEC), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, #443238/2014-6, #470388/2014-5), and from the Portuguese Science and Technology Foundation (FCT) projects M-ERA-NET/0004/2015 (PAIRED) and UIDB/04469/2020 (strategic fund).info:eu-repo/semantics/publishedVersio
Correction: Diniz et al. Silver Nanoparticles-Composing Alginate/Gelatine Hydrogel Improves Wound Healing In Vivo. Nanomaterials 2020, 10, 390
In the original publication, there was a mistake in Figure 6 as published [...]info:eu-repo/semantics/publishedVersio
Patients with Cholangiocarcinoma Present Specific RNA Profiles in Serum and Urine Extracellular Vesicles Mirroring the Tumor Expression: Novel Liquid Biopsy Biomarkers for Disease Diagnosis
Cholangiocarcinoma (CCA) comprises a group of heterogeneous biliary cancers with
dismal prognosis. The etiologies of most CCAs are unknown, but primary sclerosing cholangitis
(PSC) is a risk factor. Non-invasive diagnosis of CCA is challenging and accurate biomarkers are
lacking. We aimed to characterize the transcriptomic profile of serum and urine extracellular
vesicles (EVs) from patients with CCA, PSC, ulcerative colitis (UC), and healthy individuals. Serum
and urine EVs were isolated by serial ultracentrifugations and characterized by nanoparticle
tracking analysis, transmission electron microscopy, and immunoblotting. EVs transcriptome was
determined by Illumina gene expression array [messenger RNAs (mRNA) and non-coding RNAs
(ncRNAs)]. Differential RNA profiles were found in serum and urine EVs from patients with CCA
compared to control groups (disease and healthy), showing high diagnostic capacity. The
comparison of the mRNA profiles of serum or urine EVs from patients with CCA with the
transcriptome of tumor tissues from two cohorts of patients, CCA cells in vitro, and CCA cellsderived EVs, identified 105 and 39 commonly-altered transcripts, respectively. Gene ontology
analysis indicated that most commonly-altered mRNAs participate in carcinogenic steps. Overall,
patients with CCA present specific RNA profiles in EVs mirroring the tumor, and constituting novel
promising liquid biopsy biomarkers
Massive star formation and tidal structures in HCG 31
We present new broad-band optical and near-infrared CCD imaging together with
deep optical intermediate-resolution spectroscopy of the Hickson Compact Group
31. We analyze the morphology and colors of the stellar populations of the
galaxies, as well as the kinematics, physical conditions and chemical
composition of the ionized gas in order to get a more complete view on the
origin and evolution of the system. We estimate the ages of the most recent
star formation bursts of the system, finding an excellent consistency among the
values obtained with different indicators and starburst models. We find that
member F hosts the youngest starburst of the group, showing a substantial
population of Wolf-Rayet stars. The chemical abundances are fairly similar in
all the members of the group despite their very different absolute magnitudes.
We argue that the use of traditional metallicity-luminosity relations based on
the absolute -magnitude is not appropriate for dwarf starburst galaxies,
because their luminosity is dominated by the transient contribution of the
starburst to the blue luminosity. We think that members E and F of the group
are candidate tidal dwarf galaxies because of their high metallicity, their
kinematics, and the absence of underlying old stellar populations. Finally, we
propose that HCG~31 is suffering several almost simultaneous interaction
processes. The most relevant of these processes are: (a) the merging of members
A and C, that would have produced two optical tidal tails; and (b) a fly-by
encounter between G and the A+C complex, that would have produced an \ion{H}{1}
tidal tail from the stripping of the external gas of A+C, from which members F
and E have originated.Comment: Accepted for publication in ApJS, 41 pages, 15 figures, 9 table
HBV Infection in Relation to Consistent Condom Use: A Population-Based Study in Peru
Data on hepatitis B virus (HBV) prevalence are limited in developing countries. There is also limited information of consistent condom use efficacy for reducing HBV transmission at the population level. The study goal was to evaluate the prevalence and factors associated with HBV infection in Peru, and the relationship between anti-HBc positivity and consistent condom use.Data from two different surveys performed in 28 mid-sized Peruvian cities were analyzed. Participants aged 18-29 years were selected using a multistage cluster sampling. Information was collected through a validated two-part questionnaire. The first part (face-to-face) concerned demographic data, while the second part (self-administered using handheld computers) concerned sexual behavior. Hepatitis B core antibody (anti-HBc) was tested in 7,000 blood samples. Prevalences and associations were adjusted for sample strata, primary sampling units and population weights. Anti-HBc prevalence was 5.0% (95%CI 4.1%-5.9%), with the highest prevalence among jungle cities: 16.3% (95%CI 13.8%-19.1%). In the multivariable analysis, Anti-HBc positivity was directly associated with geographic region (highlands OR = 2.05; 95%CI 1.28-3.27, and jungle OR = 4.86; 95%CI 3.05-7.74; compared to coastal region); and inversely associated with age at sexual debut (OR = 0.90; 95%CI 0.85-0.97). Consistent condom use, evaluated in about 40% of participants, was associated with reduced prevalence (OR = 0.34; 95%CI 0.15-0.79) after adjusting for gender, geographic region, education level, lifetime number of sex partners, age at sexual debut and year of survey.Residence in highlands or jungle cities is associated with higher anti-HBc prevalences, whereas increasing age at sexual debut were associated with lower prevalences. Consistent condom use was associated with decreased risk of anti-HBc. Findings from this study emphasize the need of primary prevention programs (vaccination) especially in the jungle population, and imply that condom use promotion might be a potential strategy to prevent HBV infection
Handheld computers for self-administered sensitive data collection: A comparative study in Peru
<p>Abstract</p> <p>Background</p> <p>Low-cost handheld computers (PDA) potentially represent an efficient tool for collecting sensitive data in surveys. The goal of this study is to evaluate the quality of sexual behavior data collected with handheld computers in comparison with paper-based questionnaires.</p> <p>Methods</p> <p>A PDA-based program for data collection was developed using Open-Source tools. In two cross-sectional studies, we compared data concerning sexual behavior collected with paper forms to data collected with PDA-based forms in Ancon (Lima).</p> <p>Results</p> <p>The first study enrolled 200 participants (18–29 years). General agreement between data collected with paper format and handheld computers was 86%. Categorical variables agreement was between 70.5% and 98.5% (Kappa: 0.43–0.86) while numeric variables agreement was between 57.1% and 79.8% (Spearman: 0.76–0.95). Agreement and correlation were higher in those who had completed at least high school than those with less education. The second study enrolled 198 participants. Rates of responses to sensitive questions were similar between both kinds of questionnaires. However, the number of inconsistencies (p = 0.0001) and missing values (p = 0.001) were significantly higher in paper questionnaires.</p> <p>Conclusion</p> <p>This study showed the value of the use of handheld computers for collecting sensitive data, since a high level of agreement between paper and PDA responses was reached. In addition, a lower number of inconsistencies and missing values were found with the PDA-based system. This study has demonstrated that it is feasible to develop a low-cost application for handheld computers, and that PDAs are feasible alternatives for collecting field data in a developing country.</p
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