2,441 research outputs found

    Laboratory and telescope use of the NICMOS2 128 x 128 HgCdTe array

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    The second generation of Hubble Space Telescope (HST) instruments will include a near-infrared instrument. This choice has driven the development of near-infrared arrays to larger sizes and lower read noises. Rockwell International has delivered an array for use in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument; this array has been dubbed NICMOS2. NICMOS2 is a 128x128 array of HgCdTe diodes In-bonded to a switched MOSFET readout. The readout was specifically designed for astronomical use with the HST requirement of low read noise a prime goal. These arrays use detector material which is similar to that used by Rockwell in previous arrays (e.g., HgCdTe produced on a sapphire substrate), but the NICMOS2 devices differ substantially from other 128x128 arrays produced by Rockwell in having a read noise of only 30 electrons when read out using appropriate correlated sampling. NICMOS2 has now been characterized in the laboratory, and it has been used on groundbased telescopes

    A modular IoT platform for real-time indoor air quality monitoring

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    The impact of air quality on health and on life comfort is well established. In many societies, vulnerable elderly and young populations spend most of their time indoors. Therefore, indoor air quality monitoring (IAQM) is of great importance to human health. Engineers and researchers are increasingly focusing their efforts on the design of real-time IAQM systems using wireless sensor networks. This paper presents an end-to-end IAQM system enabling measurement of CO2, CO, SO2, NO2, O3, Cl2, ambient temperature, and relative humidity. In IAQM systems, remote users usually use a local gateway to connect wireless sensor nodes in a given monitoring site to the external world for ubiquitous access of data. In this work, the role of the gateway in processing collected air quality data and its reliable dissemination to end-users through a web-server is emphasized. A mechanism for the backup and the restoration of the collected data in the case of Internet outage is presented. The system is adapted to an open-source Internet-of-Things (IoT) web-server platform, called Emoncms, for live monitoring and long-term storage of the collected IAQM data. A modular IAQM architecture is adopted, which results in a smart scalable system that allows seamless integration of various sensing technologies, wireless sensor networks (WSNs) and smart mobile standards. The paper gives full hardware and software details of the proposed solution. Sample IAQM results collected in various locations are also presented to demonstrate the abilities of the system. 2018 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: This publication was made possible by the National Priority Research Program (NPRP) award (NPRP6-600-2-250) from the Qatar National Research Fund (QNRF), a member of the Qatar Foundation. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of QNRF.Scopu

    Voltammetric Studies of DyBa2Cu3O7-δ (DyBCO) prepared via solid-state(SS) and co-precipitation (COP) technique

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    This paper describes a series of electrochemical measurements design to explore the reactivity of the oxide superconductor, DyBa2Cu3O7-δ (DyBCO). The reproducible voltammetry was obtained in the potential window of 1.0 V to -1.0 V vs Ag/AgCl reference electrode. DyBa2Cu3O7-δ was prepared via co-precipitation and conventional solid state technique. Parameters used in this study including the effect of potential cycling, scan rate, temperature and pH as well as chronoamperometry (CA) and chronocoulometry (CC). The electrochemical reduction and oxidation can be recognized easily by the solid-phase voltammetric technique. The cyclic voltammogram for DyBCO prepared in both techniques showed four major peaks attributed to first and second redox couple. The peaks are due to the redox reaction of Cu(NH3)42+ complex.The peak current is highly dependent upon the formation of the Cu(NH3)42+ complexwhich shows that the copper planes in the superconductor played major role inproducing the peaks observed in the voltammograms. A complex surface process was found in the redox reaction through the scan rate study. After thorough investigations, it was found out that DyBCO prepared in both techniques responses strongly under acidic(pH ≈ 2.00), high temperature (80oC) condition with slight differences in voltammetricbehaviors. The cyclic voltammetric behavior exhibited by both samples is found to depend greatly on the parameters used in this study. From CA and CC studies, theamount of charge, Q that was presence on the electrode surface is 17.0 µC/cm2 and 25.0µC/cm2 and diffusion coefficient, D is 4.6 x 10-6 cm2/s and 4.0 x 10-6 cm2/s for co-precipitation and conventional solid state technique, respectively. From the chronocoulometry (CC) measurement, the estimated mass of sample that was attachedon the glassy electrode is 65 ng and 96 ng for sample prepared via conventional solid state and co-precipitation technique, respectively

    The design and simulation of a planar microarray dot electrode for a dielectrophoretic lab-on-chip device

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    Dielectrophoresis (DEP) has been proven as a method of manipulating and analyzing the electrophysiological properties of bioparticles by applying non-uniform electric fields generated through special electrodes. Various electrode geometries have been developed to address different applications. Electric field simulation over electrodes is essential in order to optimize the generated DEP force for cell manipulation. This paper describes the study of electric field distribution over planar multiple microarray dot electrodes using numerical modeling of Comsol Multiphysics 4.2a®. Electric field evaluation for different dot sizes has been demonstrated by applying a range of frequencies to the designed electrodes. Results show that the electric field is axisymmetrical around the center of the dot aperture and that it is higher at the dot edges than the dot centers. Furthermore, adding ground plane between adjacent dots increases the electric field strength. © 2012 by ESG

    Abrasive stripping voltammetric (AbrSV) studies of ErBa2Cu3O7-δ superconductor synthesised via co-precipitation and solid state methods

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    The electrochemical analysis of ErBa2Cu3O7-δ (ErBCO) superconductor ceramic materials, adhered abrasively at a glassy carbon electrode surface placed in an aqueous media has been investigated by abrasive stripping voltammetry, AbrSV technique. ErBCO samples were prepared via co-precipitation (COP) and solid state (SS) method. Powder x-ray diffraction (XRD) patterns showed both samples to be single-phased 123 of an orthorhombic structure. Details studies on the reduction-oxidation of ErBCO involved the variation of scan rate, temperature and pH of electrolyte as well as chronoamperometry (CA) and chronocoulometry (CC). The voltammogram obtained for ErBCO prepared in both methods showed four major peaks attributed to first and second redox couples. The peaks are due to the redox reaction of Cu(NH3)42+ complex. The peak current is highly dependent upon the formation of the Cu(NH3)42+ complex which shows that the copper planes in the superconductor played major role in producing the peaks observed in the voltammograms. The voltammetric response of the ErBCO was found to depend greatly on the scan rate, pH and temperature. From CA and CC studies, the amount of charge, Q that was presence on the electrode surface is 4.7 μC/cm2 and 5.4 μC/cm2 and diffusion coefficient, D is 3.4 x 10-6 cm2/s and 4.0 x 10-6 cm2/s for solid state and co-precipitation method respectively

    Calibração dos níveis críticos de potássio nas folhas de soja de cultivares com tipo de crescimento indeterminado em diferentes estádios de desenvolvimento.

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    O objetivo do trabalho foi avaliar a concentração de K em amostras de folhas de duas cultivares de soja durante os estádios de desenvolvimento reprodutivo da cultura

    Effect of Taekwondo Practice on Cognitive Function in Adolescents with Attention Deficit Hyperactivity Disorder.

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    Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neuro-developmental/behavioral disorders among adolescents. Sport and physical activity seem to play a major role in the development of cognition, memory, selective attention and motor reaction time, especially among adolescents with ADHD. In this context, the objective of this study was to investigate the effects of a one-and-a-half-year-long Taekwondo (TKD) intervention on cognitive function in adolescents with ADHD. Two cognitive instruments, namely the Stroop and the Ruff 2 and 7 tests, were administered to assess attentional inhibitory control and sustained and selective visual attention, respectively. Comparisons between the TKD and control groups at baseline did not reveal significant differences. For post-test scores, there were statistically significant differences on the Stroop color block test (large effect size or ES = 1.26 [95% confidence interval or CI 0.30⁻2.22]), the color-word interference test (large ES = 2.16 [95% CI 1.10⁻3.26]), the interference test (large ES = 1.63 [95% CI 0.62⁻2.64]) and error (large ES = -2.20 [95% CI -3.31 to -1.10]). Similar trends were reported for the Ruff 2 and 7 automated detection trials (large ES = 2.78 [95% CI 1.55⁻4.01]), controlled search trials (large ES = 2.56 [95% CI 1.38⁻3.75]) and total speed (large ES = -2.90 [95% CI -4.15 to -1.64]). In conclusion, TKD practice increased selective attention in adolescents with ADHD. Practitioners should implement martial art programs in their general plans to favorably influence attention and health in adolescents with ADHD

    Food Leftover Practices among Consumers in Selected Countries in Europe, South and North America

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    Citation: Koppel, K., Higa, F., Godwin, S., Gutierrez, N., Shalimov, R., Cardinal, P., . . . Chambers, E. (2016). Food Leftover Practices among Consumers in Selected Countries in Europe, South and North America. Foods, 5(3), 14. doi:10.3390/foods5030066Foodborne illnesses may be related to many food production factors with home practices of consumers playing an important role in food safety. Consumer behavior for handling food leftovers has been studied, however little work on comparisons among countries has been published. The objective of this study was to investigate home food leftover practices of people from North American, South American, and European countries. Surveys were conducted with approximately 100 or more consumers in Argentina, Colombia, the United States, Estonia, Italy, Russia, and Spain. The participants responded to questions related to the length of time different types of food leftovers; such as meat, fresh salads, or restaurant dishes would be kept refrigerated or would be left at room temperature before refrigeration. Researchers also investigated how consumers would determine if the food was still safe for consumption. Potentially risky behaviors were observed in all seven countries. For instance, 55.8% of Estonians, 25% of Russians and 25.8% of Argentinean participants left food out at room temperature for several hours before storing in the refrigerator. Furthermore, 25%-29% of Colombian, Estonian, and Spanish consumers would look, smell, and taste leftovers to determine its probable safety. Correct handling of leftovers is an important aspect of consumer food safety. Although the surveys cannot be representative of all consumers in each country, they do provide an initial overview of comparative practices for handling leftovers among different countries. This provides government and educators with information on potential universal and unique consumer food safety issues related to handling leftover foods among various countries

    Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors from nanopowders synthesised via co-precipitation

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    Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors synthesised via co-precipitation (COP) method were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis. All samples showed identical thermal decomposition behaviour from the thermogram in which 5 major weight losses were observed. However, XRD of the samples at different heat treatment temperatures showed different diffraction patterns indicating different thermolytic processes. Meanwhile, transmission electron microscopy and surface area analysis revealed that the powders obtained from COP have particle sizes ranging from 7 to 12 nm with relatively large surface area. Molar ratios of prepared samples obtained were near to the theoretical values as confirmed by elemental analyses using X-ray fluorescence (XRF). The TC(R=0) for sintered YGd, YNd and NdGd were 87 K, 86 K and 90 K, respectively. Surface morphological study via scanning electron microscope showed the structures of samples were dense and non porous
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