I3WSN: Industrial Intelligent Wireless Sensor Networks for indoor environments

Sensor Web Enablement (SWE) technologies have been successfully applied to a great variety of outdoor scenarios but, in practical terms, little effort has been applied for indoor environments, and even less in the field of industrial applications. This article presents an intelligent SWE application for an indoor and industrial scenario, with the aim of improving and increasing the levels of human safety. The base low-level architecture is built on top of wireless sensor networks (WSN) connected to a Sensor Observation Service (SOS). Higher layers in the architecture include services that make real time decisions based on the collected data. Both simulation and experimental results are presented. The paper shows the viability of our approach in terms of performance, scalability, modularity and safety.     

An extremely low noise photodetector based on the single electron transistor

We have demonstrated the use of the single electron transistor (SET) as an amplifier for a photodetector operated at 20 mK. The unparalleled low input noise of the SET permits the detection of very small numbers of charge carriers generated in a bulk p-type Si substrate. We present data showing the response of the detector when it is illuminated by extremely low levels of red light (=650 nm). Although we are not able to prove that individual charge carriers are being detected in our system, the magnitude of the detector response and the level of noise in the system are in good agreement with single charge, and therefore single photon, detection. From the dark current noise of 0.06 electron/s, we estimate a noise-equivalent power NEP=2×10^–21 W/Hz for infrared light with =30 µm, and from this calculate a detectivity D*=8×10¹⁷ cm-Hz/W.     

CrAlN coatings deposited by cathodic arc evaporation at different substrate bias

CrAlN is a good candidate as an alternative to conventional CrN coatings especially for high temperature oxidation-resistance applications. Different CrAlN coatings were deposited on hardened steel substrates by cathodic arc evaporation (CAE) from chromium-aluminum targets in a reactive nitrogen atmosphere at negative substrate bias between − 50 and − 400 V. The negative substrate bias has important effects on the deposition growth rate and crystalline structure. All our coatings presented hardness higher than conventional CrN coatings. The friction coefficient against alumina and tungsten carbide balls was around 0.6. The sliding wear coefficient of the CrAlN coatings was very low while an important wear was observed in the balls before a measurable wear were produced in the coatings. This effect was more pronounced as the negative substrate bias was increased.     

CMOS-SOI platform for monolithic integration of crystalline silicon MEMS

A new platform for the fabrication of crystalline micro- and nano-electromechanical systems fully integrable with CMOS is presented. A pre-CMOS process on SOI wafers allows bulk silicon areas for standard CMOS processing and areas with a stack layer of silicon and silicon oxide to be obtained, in which a set of microelectromechanical devices can be fabricated. An integrated resonant beam system with electrical actuation and detection fabricated according to the presented approach is provided.     

Environmental and individual exposure to secondhand aerosol of electronic cigarettes in confined spaces: Results from the TackSHS Project†

Secondhand electronic cigarette (e-cigarette) aerosol (SHA) might impair indoor air quality and expose bystanders. This study aims to investigate exposure to SHA in controlled conditions of enclosed settings simulating real-world scenario. An experiment was performed in a car and in a room, in which SHA was generated during a 30-minute ad libitum use of an e-cigarette. The experiment was replicated on five consecutive days in each setting. We measured PM_2.5, airborne nicotine concentrations, and biomarkers of exposure to SHA, such as nicotine metabolites, tobacco-specific nitrosamines, propylene glycol, and glycerol in bystanders’ saliva samples before, during, and after the exposure period. Self-reported health symptoms related to exposure to SHA were also recorded. The results showed that the highest median PM_2.5 concentration was recorded during the exposure period, being 21 µg/m³ in the room setting and 16 µg/m³ in the car setting—about twofold increase compared to the baseline. Most concentrations of the airborne nicotine and all biomarkers were below the limit of quantification in both settings. Bystanders in both settings experienced some short-term irritation symptoms, expressed as dry throat, nose, eyes, and phlegm. In conclusion, short-term use of an e-cigarette in confined spaces increased indoor PM_2.5 level and caused some irritation symptoms in bystanders.     

Automating a 96-Well Microtiter Plate Assay for Quick Analysis of Chemically Available Lysine in Foods

A new method for quick analysis of available lysine content in different food products has been developed by automating a 96-well microtiter plate assay. Although manual fluorometric methods validated in order to determinate available lysine content already existed for this compound, the benefits of applying appropriate automation should provide continuous operation, increased precision, an affordable electronic audit trail, and significantly reduced time and reagent consumption. The objective of this work was to adapt the ortho-phthaldialdehyde (OPA) fluorometric method to an automated workstation. Considerable effort went into developing and validating an automated method. The analytical parameters of linearity (r?=?0.999), the precision of the method (relative standard deviations?=?2.8–3.0 % for the different samples), and the results of the comparison with the corresponding OPA manual fluorometric method show that the studied method is useful for the measurement of available lysine in several food products from different natural origins such as liquid foods (soy, oat, quinoa beverages, and ultra-high temperature/sterilized milk) and powdered samples (powdered adapted, powdered follow-up, and junior milk infant formulas) with reduced time and reagent consumption.     

Physicochemical and nutritional characteristics of blueberry juice after high pressure processing

This study was carried out to investigate the impact of high pressure processing (HPP) at different pressure (200, 400 and 600 MPa) and treatment times (5, 9 and 15 min) on ascorbic acid, total phenolics, anthocyanin stability and total antioxidant capacity, were also studied at different physicochemical parameters such as pH, °Brix and color. HPP treatments resulted in more than 92% vitamin C retention at all treatment intensities. On the other hand, total phenolic content in the juice was increased, mainly after HPP at 200 MPa for all treatment times. The total and monomeric anthocyanin were similar or higher than the value estimated for the fresh juice being maximum at 400 MPa/15 min (16% increase). Antioxidant capacity values were not statistically different for treatments at 200 MPa for 5–15 min in comparison with fresh juice, however for 400 MPa/15 min and 600 MPa for all times (8–16% reduction), the lowest values were observed for total antioxidant capacity determined with TEAC method. No significant changes were observed in pH and °Brix. Color changes (a*, b*, L* and ΔE) were not visually noticeable for pressurized beverage for all pressures and times.     

Approximation of a Variable Density Cloud of Points by Shrinking a Discrete Membrane

This paper describes a method to obtain a closed surface that approximates a general 3D data point set with nonuniform density. Aside from the positions of the initial data points, no other information is used. Particularly, neither the topological relations between the points nor the normal to the surface at the data points are needed. The reconstructed surface does not exactly interpolate the initial data points, but approximates them with a bounded maximum distance. The method allows one to reconstruct closed surfaces with arbitrary genus and closed surfaces with disconnected shells.