ABSTRACT
Water quality monitoring allows communities to achieve sustainable management of water resources, which is crucial for life-supporting processes. Water quality is determined by measuring chemical, physical, and biological parameters, requiring sophisticated meters and trained specialists to perform the measurement. However, in low-income communities, water quality is determined by using human senses-smell, color, and taste-since meter acquisition is limited by costs and most people do not know how to monitor water quality. Therefore, accessible technology is necessary to empower communities to have a sustainable lifestyle. In this paper, we present the design and implementation of PortAqua, a 2-parameter water quality meter (WQM), to promote training on water quality measurement. Using basic electronic components, PortAqua is capable of measuring pH with an error of 0.4, and conductivity with an error of 33% at 85 µS cm-1, and 8.7% at 1413 µS cm-1. To demonstrate its preliminary effectiveness as a WQM and its science communication capabilities, the meter has been used in a hands-on workshop with undergraduate and graduate students. During the workshop, attendees participated in a short lecture about water quality measurement techniques and local regulations. Then, they collected water samples from a local source, measured the samples using PortAqua, and discussed the results based on the concepts and regulations. The workshop's effectiveness was evaluated through pre- and post-assessments which revealed increased knowledge of water quality regulations, measurement, and parameters at the end of the activity.
Subject(s)
Environmental Monitoring , Water Quality , Humans , Environmental Monitoring/methods , Students , CommunicationABSTRACT
The pervasive use of portable electronic devices, powered from rechargeable batteries, represents a significant portion of the electricity consumption in the world. A sustainable and alternative energy source for these devices would require unconventional power sources, such as harvesting kinetic/potential energy from mechanical vibrations, ultrasound waves, and biomechanical motion, to name a few. Piezoelectric materials transform mechanical deformation into electric fields or, conversely, external electric fields into mechanical motion. Therefore, accurate prediction of elastic and piezoelectric properties of materials, from the atomic structure and composition, is essential for studying and optimizing new piezogenerators. Here, we demonstrate the application of harmonic-covalent and reactive force fields (FF), Dreiding and ReaxFF, respectively, coupled to the polarizable charge equilibration (PQEq) model for predicting the elastic moduli and piezoelectric response of crystalline zinc oxide (ZnO) and polyvinylidene difluoride (PVDF). Furthermore, we parametrized the ReaxFF atomic interactions for Zn-F in order to characterize the interfacial effects in hybrid PVDF matrices with embedded ZnO nanoparticles (NPs). We capture the nonlinear piezoelectric behavior of the PVDF-ZnO system at different ZnO concentrations and the enhanced response that was recently observed experimentally, between 5 and 7 wt % ZnO concentrations. From our simulation results, we demonstrate that the origin of this enhancement is due to an increase in the total atomic stress distribution at the interface between the two materials. This result provides valuable insight into the design of new and improved piezoelectric nanogenerators and demonstrates the practical value of these first-principles based modeling methods in materials science.
Subject(s)
Nanoparticles , Zinc Oxide , Molecular Dynamics Simulation , PolyvinylsABSTRACT
BACKGROUND: Ectopic pregnancy (EP) is the most frequent cause of maternal death in the first trimester of pregnancy. The objective was to establish the clinical features and risk factors associated with EP. METHODS: Observational, retrospective, transversal and analytic case-control study. Two groups were included: the cases group (28 patients) and the control group (56 postpartum patients). Univariate and bivariate descriptive statistical analysis were carried out using the Pearson chi-square test, p < 0.05, with odds ratios (OR) and 95% confidence intervals (95% CI). RESULTS: Statistically significant values (OR) were: smoking: 18.33, history of EP: 11.96, IUD use: 11.9, abdominal surgery: 5.87, being multigravid: 3.80, and having two or more sexual partners: 2. The most common clinical symptom was pelvic pain with 57.1% (16), right ruptured EP 53.6%, tubal pregnancy 82.1% (23), unruptured EP 60.7% (17), hemoperitoneum 60.7% (17). Gestational age for EP was of 4-8 weeks (75%) and surgical treatment 96.4%. CONCLUSIONS: The frequency of EP found in our population was 1 in every 122 live births. Risk factors associated with ectopic pregnancy with statistically higher values were: smoking, being multigravid, having a clinical record of EP, IUD use before conception, abdominal surgery. The more frequent clinical characteristics were pelvic pain, right EP, tubal pregnancy, EP with no ruptures, hemoperitoneum < 750 ml, a gestational age between four and eight weeks.
Introducción: el embarazo ectópico (EE) es la causa más frecuente de muerte materna en el primer trimestre de embarazo. Se buscó determinar las características clínicas y los factores de riesgo asociados a EE. Métodos: estudio de casos y controles, observacional, retrospectivo, transversal y analítico. Se incluyeron dos grupos: casos (28 pacientes) y controles (56 pacientes puérperas). Se hizo un análisis estadístico descriptivo con univariante y bivariante mediante chi cuadrada de Pearson (p < 0.05), con razones de momios (RM) e intervalos de confianza al 95% (IC al 95%). Resultados: la RM del hábito tabáquico fue de 18.33, la del antecedente de EE de 11.96, uso de DIU: 11.9, cirugía abdominal: 5.87, ser multigesta: 3.80, tener dos o más parejas sexuales: 2. El síntoma clínico más común fue el dolor pélvico abdominal con 57.1% (16), EE derecho 53.6%, embarazo tubárico 82.1% (23), EE no roto 60.7% (17), hemoperitoneo 60.7% (17). La edad gestacional para EE fue de 4-8 semanas (75%) y el tratamiento quirúrgico de 96.4%. Conclusión: la frecuencia de EE fue de 1 por cada 122 nacidos vivos. Los factores de riesgo para EE con valores estadísticos más altos fueron: consumir tabaco, tener dos o más parejas sexuales, ser multigesta, tener antecedente de EE, usar DIU antes de la concepción, haber sido sometida a cirugías abdominales. Las características clínicas más frecuentes fueron el dolor pélvico abdominal, EE derecho, embarazo tubárico, EE no roto, hemoperitoneo < 750 mL y una edad gestacional entre cuatro y ocho semanas.
