323,002 research outputs found
A General-Purpose Small RFID Epidermal Datalogger for Continuous Human Skin Monitoring in Mobility
No full textSkin sensors based on Radiofrequency Identification enable non-invasive monitoring of human physiologic parameters. To speed up the experimentations of new sensing modalities and their possible applications, a general purpose on-skin oriented board is here described. A 3 cm by 3 cm flexible Kapton layer hosts a miniaturized open-loop antenna tunable in the worldwide UHF RFID band (860-960)MHz, a microchip with internal ADC and pads for interconnecting external sensors and a battery for data-logging mode. The epidermal board can be integrated into plasters and is suitable to measure both skin and external parameters. When working in Battery Assisted Passive mode it can be read up to 1.5 m and hence the wearer can automatically upload the stored data in mobility on crossing a gate. The device is preliminarily experimented in the measurement of the temperature of the skin and of the moisture on clothes
Aqueous concentration of CO2 in carbon-saturated fluids as a highly sensitive oxybarometer
No full textThe CO2 content of aqueous fluids in equilibrium with carbon can be used to retrieve their oxygen fugacity if pressure and temperature are known. Applicable to both natural and experimental systems, we present a new oxybarometer based on the aqueous concentration of CO2 in fluids saturated with either graphite or glass-like carbon, suitable to retrieve their oxygen fugacity. The method was experimentally tested by measuring by mass spectrometry the CO2 content in aqueous fluids coexisting with glass-like carbon buffered externally with Ni-NiO, employing ordered and disordered forms of NiO characterised by small differences in free energy (<5 kJ/mol). Considering analytical uncertainties on CO2 measurements, fO2 values can be resolved with an accuracy of about 0.01 log units, which is one order of magnitude lower than uncertainties affecting conventional solid state redox sensors. The CO2- in-fluid oxybarometer is the first available parameterisation of the fO2 dependency on pressure, temperature and CO2 content of aqueous fluids and can be used for fluids containing >1 mol. % CO2 beneath the graphite-diamond transition
Quantitative analysis of COH fluids synthesized at HP–HT conditions: an optimized methodology to measure volatiles in experimental capsules
No full textThe quantitative assessment of COH fluids is crucial in modeling geological processes. The composition of fluids, and in particular their H2O/CO2 ratio, can influence the melting temperatures, the location of hydration or carbonation reactions, and the solute transport capability in several rock systems. In the scientific literature, COH fluids speciation has been generally assumed on the basis of thermodynamic calculations using equations of state of simple H2O–nonpolar gas systems (e.g., H2O–CO2–CH4). Only few authors dealt with the experimental determination of high-pressure COH fluid species at different conditions, using diverse experimental and analytical approaches (e.g., piston cylinder + capsule piercing + gas chromatography/mass spectrometry; cold seal + silica glass capsules + Raman). In this contribution, we present a new methodology for the synthesis and the analysis of COH fluids in experimental capsules, which allows the quantitative determination of volatiles in the fluid by means of a capsule-piercing device connected to a quadrupole mass spectrometer. COH fluids are synthesized starting from oxalic acid dihydrate at P = amb and T = 250°C in single capsules heated in a furnace, and at P = 1 GPa and T = 800°C using a piston-cylinder apparatus and the double-capsule technique to control the redox conditions employing the rhenium–rhenium oxide oxygen buffer. A quantitative analysis of H2O, CO2, CH4, CO, H2, O2, and N2 along with associated statistical errors is obtained by linear regression of the m/z data of the sample and of standard gas mixtures of known composition. The estimated uncertainties are typically <1% for H2O and CO2, and <5% for CO. Our results suggest that the COH fluid speciation is preserved during and after quench, as the experimental data closely mimic the thermodynamic model both in terms of bulk composition and fluid speciation
Capacitively-coupled UHF antennas for wireless temperature monitoring of bearings in electric vehicles
No full textThis work introduces a capacitively-coupled telemetry system operating in the UHF band (868-960 MHz). It is based on two concentric C-shaped dipoles positioned at a millimeter distance. Numerical simulations have been employed to optimize the angular dimensions of the antennas, and the resulting arrangement ensures a stable link for any mutual orientation. Preliminary experiments conducted with a mock-up have demonstrated that sensing and communication through backscattering modulation can be achieved with only 400 μW of power
Carbon-saturated COH fluids in the upper mantle: a review of high-pressure and high-temperature ex situ experiments
No full text
No Evidence for Seed Transmission of Tomato Yellow Leaf Curl Sardinia Virus in Tomato
No full textSeed transmission is an important factor in the epidemiology of plant pathogens. Geminiviruses are serious pests spread in tropical and subtropical regions. They are transmitted by hemipteran insects, but a few cases of transmission through seeds were recently reported. Here, we investigated the tomato seed transmissibility of the begomovirus tomato yellow leaf curl Sardinia virus (TYLCSV), one of the agents inducing the tomato yellow leaf curl disease, heavily affecting tomato crops in the Mediterranean area. None of the 180 seedlings originating from TYLCSV-infected plants showed any phenotypic alteration typical of virus infection. Moreover, whole viral genomic molecules could not be detected in their cotyledons and true leaves, neither by membrane hybridization nor by rolling-circle amplification followed by PCR, indicating that TYLCSV is not a seed-transmissible pathogen for tomato. Examining the localization of TYLCSV DNA in progenitor plants, we detected the virus genome by PCR in all vegetative and reproductive tissues, but viral genomic and replicative forms were found only in leaves, flowers and fruit flesh, not in seeds and embryos. Closer investigations allowed us to discover for the first time that these embryos were superficially contaminated by TYLCSV DNA but whole genomic molecules were not detectable. Therefore, the inability of TYLCSV genomic molecules to colonize tomato embryos during infection justifies the lack of seed transmissibility observed in this host
A General-purpose Configurable RFID Epidermal Board with a Two-way Discrete Impedance Tuning
No full textCurrent advances of the Radiofrequency Identifi- cation (RFID) technology can boost the emerging class of bio- integrated skin devices exploiting low-power (even passive) wire- less communication and sensing interfaces. This work describes a small-size (3cmx3cm) flexible UHF RFID board conceived for the rapid laboratory experimentation and suitable to multi-purpose monitoring of physical parameters (e.g. temperature and sweat) over the skin and/or over clothing layers and medical plasters. An engineered open-loop antenna is coupled with a two-way discrete (four states) tuning circuit to compensate the frequency shifts that occur in real applications due to the intrinsic variability of the human body. The capability of the tuning mechanism to down/up-shift the operating frequency and to restore the default state is validated by means of both numerical simulation and measurements over some volunteers in realistic conditions
- …
