Enhancement in the Photoluminescence Properties of SiO2:Ge Embedded in a Polymeric Matrix

Polymer films of styrene butadiene copolymer (SBC) mixed with SiO2:Ge powder were successfully obtained by the drop casting method. The SBC concentration (in chloroform solution) was 10%w/v and the SiO2:Ge powder was mixed (mass ratio 80:20 respectively). The thicknesses of the films obtained were 50, 100, and 200 μm. In addition, polymer films of polytetrafluoroethylene (PTFE) preparation (60% dispersion in water), were obtained mixing 2 ml of PTFE and 0.05g of SiO2:Ge powder with a mass relation of 98% polymer and 2% SiO2:Ge. The photoluminescence emission spectra (PL) of SBC doped with SiO2:Ge resulted in similar characteristics to those for SiO2:Ge powders, although their intensity shows an increase 3.5 times approximately, compared with the pure powder. On the other hand, the PTFE films with SiO2:Ge present just one peak in the PL emission at 439 nm but their intensity increases 18 times respect to the powder. The photoluminescence excitation (PLE) spectra of the SiO2:Ge powders show the characteristic peaks at 248 nm (most intense) and at 366 nm. However, when the powder is embedded either in SBC or PTFE the peak at 366 nm shows an important increase which seems to indicate an energy transfer from the polymer to the SiO2:Ge

On the Use of the FuzzyARTMAP Neural Network for Pattern Recognition in Statistical Process Control using a Factorial Design

Time-series statistical pattern recognition is of prime importance in statistics, especially in quality control techniques for manufacturing processes. A frequent problem in this application is the complexity when trying to determine the behaviour (pattern) from sample data. There have been identified standard patterns which are commonly present when using the X chart; its detection depends on human judgement supported by norms and graphical criteria. In the last few years, it has been demonstrated that Artificial Neural Networks (ANN’s) are useful to predict the type of time-series pattern instead of the use of rules. However, the ANN control parameters have to be fixed to values that maximize its performance. This research proposes an experimental design methodology to determine the most appropriate values for the control parameters of the FuzzyARTMAP ANN such as: learning rate (β ) and network vigilance (ρa, ρb, ρab) in order to increment the neural network efficiency during unnatural pattern recognition

Drones, Virtual Reality, and Modeling: Communicating Catastrophic Dam Failure

Dam failures occur worldwide and can be economically and ecologically devastating. Communicating the scale of these risks to the general public and decision-makers is imperative. Two-dimensional (2D) dam failure hydraulic models inform owners and floodplain managers of flood regimes but have limitations when shared with non-specialists. This study addresses these limitations by constructing a 3D Virtual Reality (VR) environment to display the 1976 Teton Dam disaster case study using a pipeline composed of (1) 2D hydraulic model data (extrapolated into 3D), (2) a 3D reconstructed dam, and (3) a terrain model processed from UAS (Uncrewed Airborne System) imagery using Structure from Motion photogrammetry. This study validates the VR environment pipeline on the Oculus Quest 2 VR Headset with the criteria: immersion fidelity, movement, immersive soundscape, and agreement with historical observations and terrain. Through this VR environment, we develop an effective method to share historical events and, with future work, improve hazard awareness; applications of this method could improve citizen engagement with Early Warning Systems. This paper establishes a pipeline to produce a visualization tool for merging UAS imagery, Virtual Reality, digital scene creation, and sophisticated 2D hydraulic models to communicate catastrophic flooding events from natural or human-made levees or dams

Emanation Study of Gas Radon on the Ancient Cuexcomate Geyser in Puebla City, Mexico

Radon measurements were collected over a period of nine months in the area of the ancient Cuexcomate geyser, in Puebla City. For measuring radon, the passive method of nuclear tracks in solids was used, using polycarbonate CR-39 as radiation sensitive material. Radon concentrations varied in strong anti-correlation with the rainfall intensity. And are lower compared to other locations, in concordance with the stratigraphic composition, as travertine and deposits of volcanic origin, corresponding to the geyser chemical composition and the active environment in the north part of the Trans-Mexican Volcanic Belt with an andesitic and basalt composition

Potential of mathematical modeling in fruit quality

A review of mathematical modeling applied to fruit quality showed that these models ranged inresolution from simple yield equations to complex  representations of processes as respiration, photosynthesis and assimilation of nutrients. The latter models take into account complex  genotype environment interactions to estimate their effects on growth and yield. Recently, models are used to estimate seasonal changes in quality traits as fruit size, dry matter, water content and the concentration of sugars and acids, which are very important for flavor and aroma. These models have demonstrated their ability to generate relationships between physiological variables and quality attributes (allometric relations). This new kind of hybrid models has sufficient complexity to predict quality traits behavior

Prevalence and correlates of food insecurity among students attending a midsize rural university in Oregon

Objective: To examine the prevalence and identify correlates of food insecurity among students attending a rural university in Oregon. Methods: Cross-sectional non-probability survey of 354 students attending a midsize rural university in Oregon during May 2011. Main outcome was food insecurity measured using the USDA Household Food Security Survey Module: Six-Item Short Form. Socioeconomic and demographic variables were included in multivariate logistic regression models. Results: Over half of students (59%) were food insecure at some point during the previous year. Having fair/poor health (OR: 2.08, 95%CI: 1.07 – 4.63), being employed (OR: 1.73, 95%CI: 1.04 – 2.88) and with incomes below $15,000 per year (OR: 2.23, 95% CI: 1.07 – 4.63) was associated with food insecurity. In turn, good academic performance (GPA 3.1 or higher) was inversely associated with food insecurity. Conclusions: Food insecurity seems to be a significant issue for college students. It is necessary to expand research on different campus settings, and further strengthen support systems to increase access to nutritious foods for this population.This is the author's peer-reviewed accepted manuscript. The version of record is copyrighted by Elsevier and can be found at: http://www.jneb.org/home.Keywords: Food insecurity, Oregon, Rural, College student

Nuclear Tracks Morphology Study Using Raman Methodology

In this work, a new methodology for rendering profiles of etched nuclear tracks is presented, using confocal micro-Raman spectrometry instrumentation. The precise profile of etched nuclear tracks with normal and/or angular incidence of the particle can be determined in few minutes, with a great visual and numerical resolution, that means a quantitative and qualitative simultaneous chemical and morphology characterization with the Raman technique. The Raman image routine is designed to acquire at each image pixel a complete Raman spectrum. This is a mapping of the functional groups that form the polymeric structure, which may be broken by the damage caused by the incident radiation and/or the etching process

Versatile Graphene-Based Platform for Robust Nanobiohybrid Interfaces

Technologically useful and robust graphene-based interfaces for devices require the introduction of highly selective, stable, and covalently bonded functionalities on the graphene surface, whilst essentially retaining the electronic properties of the pristine layer. This work demonstrates that highly controlled, ultrahigh vacuum covalent chemical functionalization of graphene sheets with a thiol-terminated molecule provides a robust and tunable platform for the development of hybrid nanostructures in different environments. We employ this facile strategy to covalently couple two representative systems of broad interest: metal nanoparticles, via S-metal bonds, and thiol-modified DNA aptamers, via disulfide bridges. Both systems, which have been characterized by a multi-technique approach, remain firmly anchored to the graphene surface even after several washing cycles. Atomic force microscopy images demonstrate that the conjugated aptamer retains the functionality required to recognize a target protein. This methodology opens a new route to the integration of high-quality graphene layers into diverse technological platforms, including plasmonics, optoelectronics, or biosensing. With respect to the latter, the viability of a thiol-functionalized chemical vapor deposition graphene-based solution-gated field-effect transistor array was assessed