Effect of the Reduction Temperature of PdAg Nanoparticles during the Polyol Process in the Ethanol Electrooxidation Reaction

This work reports the effect of reduction temperature during the synthesis of PdAg catalysts through the polyol process and their evaluation in the ethanol electrooxidation reaction (EOR). The characterization was performed using Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The electrochemical evaluation for the ethanol electrooxidation reaction was implemented in alkaline medium using chronoamperometry (CA) and cyclic voltammetry (CV). An important effect of the reduction temperature on electroactivity and catalytic stability was observed: both the maximum current density and the catalytic stability were higher in the catalyst synthesized at the highest temperature (135°C). This performance was associated with the extent of the interaction between Pd and Ag which was measured in terms of the structural expansion of Pd

The Comparability of Men Who Have Sex With Men Recruited From Venue-Time-Space Sampling and Facebook: A Cohort Study

Background: Recruiting valid samples of men who have sex with men (MSM) is a key component of the US human immunodeficiency virus (HIV) surveillance and of research studies seeking to improve HIV prevention for MSM. Social media, such as Facebook, may present an opportunity to reach broad samples of MSM, but the extent to which those samples are comparable with men recruited from venue-based, time-space sampling (VBTS) is unknown. Objective: The objective of this study was to assess the comparability of MSM recruited via VBTS and Facebook. Methods: HIV-negative and HIV-positive black and white MSM were recruited from June 2010 to December 2012 using VBTS and Facebook in Atlanta, GA. We compared the self-reported venue attendance, demographic characteristics, sexual and risk behaviors, history of HIV-testing, and HIV and sexually transmitted infection (STI) prevalence between Facebook- and VTBS-recruited MSM overall and by race. Multivariate logistic and negative binomial models estimated age/race adjusted ratios. The Kaplan-Meier method was used to assess 24-month retention. Results: We recruited 803 MSM, of whom 110 (34/110, 30.9% black MSM, 76/110, 69.1% white MSM) were recruited via Facebook and 693 (420/693, 60.6% black MSM, 273/693, 39.4% white MSM) were recruited through VTBS. Facebook recruits had high rates of venue attendance in the previous month (26/34, 77% among black and 71/76, 93% among white MSM; between-race P=.01). MSM recruited on Facebook were generally older, with significant age differences among black MSM (P=.02), but not white MSM (P=.14). … See full text for complete abstract

Analytical Study of Solution-Processed Tin Oxide as Electron Transport Layer in Printed Perovskite Solar Cells

Solution‐processed tin oxide (SnO$_{x}$ ) electron transport layers demonstrate excellent performance in various optoelectronic devices and offer the ease of facile and low cost deposition by various printing techniques. The most common precursor solution for the preparation of SnO$_{x}$ thin films is SnCl$_{2}$ dissolved in ethanol. In order to elucidate the mechanism of the precursor conversion at different annealing temperatures and the optoelectronic performance of the SnO$_{x}$ electron transport layer, phonon and vibrational infrared and photoelectron spectroscopies as well as atomic force microscopy are used to probe the chemical, physical, and morphological properties of the SnO$_{x}$ thin films. The influence of two different solvents on the layer morphology of SnO$_{x}$ thin films is investigated. In both cases, an increasing annealing temperature not only improves the structural and chemical properties of solution‐processed SnO$_{x}$, but also reduces the concentration of tin hydroxide species in the bulk and on the surface of these thin films. As a prototypical example for the high potential of printed SnO$_{x}$ layers for solar cells, high performance perovskite solar cells with a stabilized power conversion efficiency of over 15% are presented

The influence of religious identity and socio-economic status on diet over time, an example from medieval France

In Southern France as in other parts of Europe, significant changes occurred in settlement patterns between the end of Antiquity and the beginning of the Middle Ages. Small communities gathered to form, by the tenth century, villages organized around a church. This development was the result of a new social and agrarian organization. Its impact on lifestyles and, more precisely, on diet is still poorly understood. The analysis of carbon and nitrogen isotopes in bone collagen from the inhabitants of the well-preserved medieval rural site Missignac-Saint Gilles le Vieux (fifth to thirteenth centuries, Gard, France) provides insight into their dietary practices and enables a discussion about its transformation over time. A sample of 152 adult individuals dated from 675 to 1175 AD (75 females, 77 males) and 75 specimens from 16 non-human species were analyzed. Results show the exploitation of freshwater, marine, and terrestrial ecosystems as well as various breeding practices specific to each species. The use of both C4 and halophyte plants for feeding domestic animals was also observed. Concerning human dietary practices, a change seemed to occur at the beginning of the tenth century with an increase of δ15N values and a decrease of δ13C values. This corresponds to the introduction of a significant amount of freshwater resources into the diet and could be related to the evolution of the Catholic doctrine. A concomitant diversification of access to individual food resources was also observed, probably linked to the increased diversity of practice inside a population otherwise perceived as one community

3D printing for surgical planning in bone grafts for cleft-palate: a case report

3D printing has been used for teaching purposes. Creating models for simulating surgeries. Gong et al presented a workflow for digital planning for surgery and Rendon et al previously presented a low-cost method with acceptable precision.  This paper aims to present a case where 3D printing surgical planning was applied for bone graft shape and dimensions. A 16-year-old female patient with a history of bilateral cleft lip and palate has received 6 surgical interventions to treat her congenital pathology. She begins orthodontic management at the age of 6 years and is referred to the plastic surgery service 10 years later, presenting oral and nasal fistula on the nasal floor with mainly liquid leakage. A bone graft was taken and applied from the patient's left iliac crest. the iliac crest is taken and the bone graft is molded Assisted with 3D printed model which is fixed in the premaxilla with a 14-hole linear plate. We proposed a new application for low-cost 3D printed models. Patient specific models have applications in cleft palate bone grafting. We present a case and more studies are required to measure variables as time, graft integration, and patient satisfaction

Acceptance towards COVID-19 vaccination in Latin America and the Caribbean: A systematic review and meta-analysis

Introduction: Vaccination represents an important strategy to mitigate COVID-19 related morbidity and mortality by protecting against severe forms of the disease and reducing hospitalization and death rates. In this sense, the objective of this study is to estimate the prevalence of Vaccination Intention (VI) against COVID-19 in Latin America and Caribbean (LAC). Methods: We conducted a systematic review with a comprehensive search strategy for the following databases: PubMed, Scopus and Web of Science. A random-effect model meta-analysis was carried out using observational studies assessing the intention to vaccines against COVID-19 in LAC countries. The Clopper-Pearson method was used to estimate 95% Confidence Intervals. The quality assessment was developed using the Newcastle-Ottawa Scale adapted for cross-sectional studies. A subgroup analysis by study location and a sensitivity analysis were developed. Results: Nineteen cross-sectional studies were included. Five meta-analyzes were performed according to the target population of the included studies. The VI in the general population of LAC was 78.0% (95%CI: 74.0%–82.0%). The VI for non-pregnant women was 78.0% (95%CI: 58.0%–99.0%), for elderly population was 63.0% (95%CI: 59.0%–69.0%), for pregnant women was 69.0% (95%CI: 61.0%–76.0%) and for health-personnel was 83.0% (95% CI: 71.0%–96.0%). The sensitivity analysis for general population meta-analysis that included only low risk of bias studies showed a 77.0% VI (95%CI: 73.0%–82.0%) and for non-pregnant women, 85.0% VI (95%CI: 79.0%–90.0%). Conclusion: Despite the high prevalence of VI in general population found in our study, VI prevalence from elderly people and pregnant women are lower than other population groups and overall population.Revisión por pare

The 2HWC HAWC Observatory Gamma Ray Catalog

We present the first catalog of TeV gamma-ray sources realized with the recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV telescope currently in operation, with a 1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma ray energies between hundreds GeV and tens of TeV. HAWC is located in Mexico at a latitude of 19 degree North and was completed in March 2015. Here, we present the 2HWC catalog, which is the result of the first source search realized with the complete HAWC detector. Realized with 507 days of data and represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected contamination of 0.5 due to background fluctuation. Out of these sources, 16 are more than one degree away from any previously reported TeV source. The source list, including the position measurement, spectrum measurement, and uncertainties, is reported. Seven of the detected sources may be associated with pulsar wind nebulae, two with supernova remnants, two with blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa

Search for very-high-energy emission from Gamma-ray Bursts using the first 18 months of data from the HAWC Gamma-ray Observatory

The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory is an extensive air shower detector operating in central Mexico, which has recently completed its first two years of full operations. If for a burst like GRB 130427A at a redshift of 0.34 and a high-energy component following a power law with index -1.66, the high-energy component is extended to higher energies with no cut-off other than from extragalactic background light attenuation, HAWC would observe gamma rays with a peak energy of $\sim$300 GeV. This paper reports the results of HAWC observations of 64 gamma-ray bursts (GRBs) detected by $\mathit{Swift}$ and $\mathit{Fermi}$, including three GRBs that were also detected by the Large Area Telescope ($\mathit{Fermi}$-LAT). An ON/OFF analysis method is employed, searching on the time scale given by the observed light curve at keV-MeV energies and also on extended time scales. For all GRBs and time scales, no statistically significant excess of counts is found and upper limits on the number of gamma rays and the gamma-ray flux are calculated. GRB 170206A, the third brightest short GRB detected by the Gamma-ray Burst Monitor on board the $\mathit{Fermi}$ satellite ($\mathit{Fermi}$-GBM) and also detected by the LAT, occurred very close to zenith. The LAT measurements can neither exclude the presence of a synchrotron self-Compton (SSC) component nor constrain its spectrum. Instead, the HAWC upper limits constrain the expected cut-off in an additional high-energy component to be less than $100~\rm{GeV}$ for reasonable assumptions about the energetics and redshift of the burst.Comment: 19 pages, 6 figures, published in Ap

Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above $\sim$1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form $\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}$. The data is well-fit with values of $\alpha=2.63\pm0.03$, $\beta=0.15\pm0.03$, and log$_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02$ when $E_{0}$ is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be $\pm$50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa