Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells

Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Using a segmented anode fuel cell we study the effect of gas phase convection and membrane diffusion of water on the spatiotemporal nonlinear dynamics - localized ignition and front propagation - in the cell. Co-current gas flow causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate to the inlet; counter-current flow causes ignition in the interior of the cell, with the fronts subsequently spreading towards both inlets. These instabilities critically affect fuel cell performance

Dynamics of Fattening and Thinning 2D Sessile Droplets

We investigate the dynamics of a droplet on a planar substrate as the droplet volume changes dynamically due to liquid being pumped in or out through a pore. We adopt a diffuse-interface formulation which is appropriately modified to account for a localized inflow–outflow boundary condition (the pore) at the bottom of the droplet, hence allowing to dynamically control its volume, as the droplet moves on a flat substrate with a periodic chemical pattern. We find that the droplet undergoes a stick–slip motion as the volume is increased (fattening droplet) which can be monitored by tracking the droplet contact points. If we then switch over to outflow conditions (thinning droplet), the droplet follows a different path (i.e., the distance of the droplet midpoint from the pore location evolves differently), giving rise to a hysteretic behavior. By means of geometrical arguments, we are able to theoretically construct the full bifurcation diagram of the droplet equilibria (positions and droplet shapes) as the droplet volume is changed, finding excellent agreement with time-dependent computations of our diffuse-interface model

Simultaneous in-process control of weld pool geometry and heat affected zone based on thermal- optic imaging for welding of steel materials by concentrated energy fluxes

Abstract Robot welding using high power energy flow processes is widely used in the fabrication industry for increasing productivity and enhancing product quality. The application of infrared thermography to the adaptive control of different welding processes is discussed in this paper. Because these processes are difficult to control and automate, the quality of the product can vary over a large range. Therefore temperature gradients need to be controlled directly on-line with a high accuracy. This requires twodimensional temperature monitoring. A thermo-optic camera system can be used in order to investigate the cooling process in the weld seam area as well as in the heat affected zone. It was found that reasonable correlations exist between thermo-optical machine vision and weld seam quality, as far as weld pool geometry and thermal cycle interrogation is concerned

Determining and addressing obstacles to the effective use of long-lasting insecticide-impregnated nets in rural Tanzania

<p>Abstract</p> <p>Background</p> <p>The objective of this project was to achieve high, sustainable levels of net coverage in a village in rural Tanzania by combining free distribution of long-lasting insecticide-impregnated nets (LLINs) with community-tailored education. In Tanzania, malaria is the leading cause of morbidity and mortality. Although malaria bed nets have a well-established role in reducing disease burden, few rural households have access to nets, and effective use depends on personal practices and attitudes.</p> <p>Methods</p> <p>Five practices and attitudes inconsistent with effective LLIN use were identified from household interviews (n = 10). A randomized survey of villagers (n = 132) verified local prevalence of these practices and attitudes. Community leaders held an educational session for two members of every household addressing these practice and attitudes, demonstrating proper LLIN use, and emphasizing behaviour modification. Attendees received one or two LLINs per household. Surveys distributed three weeks (n = 104) and 15 months (n = 104) post-intervention assessed corrected practices and attitudes. Project efficacy was defined by correction of baseline practices and attitudes as well as high rates of reported daily net use, with statistical significance determined by chi-square test.</p> <p>Results</p> <p>Baseline interviews and surveys revealed incorrect practices and attitudes regarding 1) use of nets in dry season, 2) need to retreat LLINs, 3) children napping under nets, 4) need to repair nets, and 5) net procurement as a priority, with 53- 88.6% incorrect responses (11.4-47% correct responses). A three-week follow-up demonstrated 83-95% correct responses. Fifteen-month follow-up showed statistically significant (p < 0.01) corrections from baseline in all five practice and attitudes (39.4-93.3% correct answers). 89.4% of respondents reported using their nets every night, and 93.3% affirmed purchase of nets as a financial priority.</p> <p>Conclusions</p> <p>Results suggest that addressing community-specific practices and attitudes prior to LLIN distribution promotes consistent and correct use, and helps change attitudes towards bed nets as a preventative health measure. Future LLIN distributions can learn from the paradigm established in this project.</p

Metabolic Abnormalities Are Common among South American Hispanics Subjects with Normal Weight or Excess Body Weight: The CRONICAS Cohort Study.

OBJECTIVE: We aimed to characterize metabolic status by body mass index (BMI) status. METHODS: The CRONICAS longitudinal study was performed in an age-and-sex stratified random sample of participants aged 35 years or older in four Peruvian settings: Lima (Peru's capital, costal urban, highly urbanized), urban and rural Puno (both high-altitude), and Tumbes (costal semirural). Data from the baseline study, conducted in 2010, was used. Individuals were classified by BMI as normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and obese (≥30 kg/m2), and as metabolically healthy (0-1 metabolic abnormality) or metabolically unhealthy (≥2 abnormalities). Abnormalities included individual components of the metabolic syndrome, high-sensitivity C-reactive protein, and insulin resistance. RESULTS: A total of 3088 (age 55.6±12.6 years, 51.3% females) had all measurements. Of these, 890 (28.8%), 1361 (44.1%) and 837 (27.1%) were normal weight, overweight and obese, respectively. Overall, 19.0% of normal weight in contrast to 54.9% of overweight and 77.7% of obese individuals had ≥3 risk factors (p<0.001). Among normal weight individuals, 43.1% were metabolically unhealthy, and age ≥65 years, female, and highest socioeconomic groups were more likely to have this pattern. In contrast, only 16.4% of overweight and 3.9% of obese individuals were metabolically healthy and, compared to Lima, the rural and urban sites in Puno were more likely to have a metabolically healthier profile. CONCLUSIONS: Most Peruvians with overweight and obesity have additional risk factors for cardiovascular disease, as well as a majority of those with a healthy weight. Prevention programs aimed at individuals with a normal BMI, and those who are overweight and obese, are urgently needed, such as screening for elevated fasting cholesterol and glucose

PREVALENCE OF IDEAL CARDIOVASCULAR HEALTH IN PERU: THE CRONICAS COHORT STUDY

ACC.15: American College of Cardiology Scientific Session 2015, developed at March 14, 2015 to March 16, 2015. Session Title: Young Investigator Awards Competition: Cardiovascular Health Outcomes and Population Genetics Abstract Category: Cardiovascular Health Outcomes and Population Genetics Presentation Number: 915-05. Oral Contributions Room 4 Monday, March 16, 2015, 11:00 a.m.-11:15 a.m.Background: American Heart Association 2020 Impact Goal focuses on promotion of health and control of cardiovascular risk. We aimed to determine the prevalence of Ideal Cardiovascular Health in Peru. Methods: Ideal Cardiovascular Health is the presence of 3 ideal health factors (untreated total cholesterol 3 times/day). Data from the CRONICAS longitudinal study, an age-and-sex stratified random sample of participants aged 35 years or older in four Peruvian settings. Results: 3058 of 3618 (84.5%) of the CRONICAS cohort participants had complete information for analysis. Figure 1 shows the agestandardized prevalence estimates of ideal, intermediate and poor health metrics. No one had all 7 metrics; only 48 (15.7%) had 6 ideal health metrics and 650 (21.3%) had ≤ 1 ideal health metric. Compared to urban Lima, living in rural Puno was associated with more Ideal Cardiovascular Health (OR 2.09, 95% CI 1.49-2.91) and rural Tumbes was less ideal (OR 0.54, 95% CI 0.39-0.76) after adjusting for sex, age, education and wealth index. Conclusion: There is an alarmingly low prevalence of Ideal Cardiovascular Health in Peru and the metrics with the greatest potential for improvement are health behaviors, including diet quality, physical activity and body weight.Revisión por pare

The SABRE project and the SABRE Proof-of-Principle

SABRE aims to directly measure the annual modulation of the dark matter interaction rate with NaI(Tl) crystals. A modulation compatible with the standard hypothesis, in which our Galaxy is immersed in a dark matter halo, has been measured by the DAMA experiment in the same target material. Other direct detection experiments, using different target materials, seem to exclude the interpretation of such modulation in the simplest scenario of WIMP-nucleon elastic scattering. The SABRE experiment aims to carry out an independent search with sufficient sensitivity to confirm or refute the DAMA claim. The goal of the SABRE experiment is to achieve the lowest background rate for a NaI(Tl) experiment (order of 0.1 cpd/kg/keV(ee) in the energy region of interest for dark matter). This challenging goal could be achievable by operating high-purity crystals inside a liquid scintillator veto for active background rejection. In addition, twin detectors will be located in the northern and southern hemispheres to identify possible contributions to the modulation from seasonal or site-related effects. The SABRE project includes an initial Proof-of-Principle phase at LNGS (Italy), to assess the radio-purity of the crystals and the efficiency of the liquid scintillator veto. This paper describes the general concept of SABRE and the expected sensitivity to WIMP annual modulation.The SABRE program is supported by funding from INFN (Italy), NSF (USA), and ARC (Australia Grants: LE170100162, LE16010080, DP170101675, LP150100075). F. Froborg has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 703650. We acknowledge the generous hospitality and constant support of the Laboratori Nazionali del Gran Sasso (Italy)