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Sensors (Basel, Switzerland) Jan 2023Clean air in cities improves our health and overall quality of life and helps fight climate change and preserve our environment. High-resolution measures of pollutants'...
Clean air in cities improves our health and overall quality of life and helps fight climate change and preserve our environment. High-resolution measures of pollutants' concentrations can support the identification of urban areas with poor air quality and raise citizens' awareness while encouraging more sustainable behaviors. Recent advances in Internet of Things (IoT) technology have led to extensive use of low-cost air quality sensors for hyper-local air quality monitoring. As a result, public administrations and citizens increasingly rely on information obtained from sensors to make decisions in their daily lives and mitigate pollution effects. Unfortunately, in most sensing applications, sensors are known to be error-prone. Thanks to Artificial Intelligence (AI) technologies, it is possible to devise computationally efficient methods that can automatically pinpoint anomalies in those data streams in real time. In order to enhance the reliability of air quality sensing applications, we believe that it is highly important to set up a data-cleaning process. In this work, we propose AIrSense, a novel AI-based framework for obtaining reliable pollutant concentrations from raw data collected by a network of low-cost sensors. It enacts an anomaly detection and repairing procedure on raw measurements before applying the calibration model, which converts raw measurements to concentration measurements of gasses. There are very few studies of anomaly detection in raw air quality sensor data (millivolts). Our approach is the first that proposes to detect and repair anomalies in raw data before they are calibrated by considering the temporal sequence of the measurements and the correlations between different sensor features. If at least some previous measurements are available and not anomalous, it trains a model and uses the prediction to repair the observations; otherwise, it exploits the previous observation. Firstly, a majority voting system based on three different algorithms detects anomalies in raw data. Then, anomalies are repaired to avoid missing values in the measurement time series. In the end, the calibration model provides the pollutant concentrations. Experiments conducted on a real dataset of 12,000 observations produced by 12 low-cost sensors demonstrated the importance of the data-cleaning process in improving calibration algorithms' performances.
Topics: Air Pollutants; Particulate Matter; Artificial Intelligence; Quality of Life; Reproducibility of Results; Environmental Monitoring; Air Pollution; Environmental Pollutants
PubMed: 36679439
DOI: 10.3390/s23020640 -
Accounts of Chemical Research Sep 2020ConspectusPlasmonic nanostructures have garnered widescale scientific interest because of their strong light-matter interactions and the tunability of their absorption...
ConspectusPlasmonic nanostructures have garnered widescale scientific interest because of their strong light-matter interactions and the tunability of their absorption across the solar spectrum. At the heart of their superlative interaction with light is the resonant excitation of a collective oscillation of electrons in the nanostructure by the incident electromagnetic field. These resonant oscillations are known as localized surface plasmon resonances (LSPRs). In recent years, the community has uncovered intriguing photochemical attributes of noble metal nanostructures arising from their LSPRs. Chemical reactions that are otherwise unfavorable or sluggish in the dark are induced on the nanostructure surface upon photoexcitation of LSPRs. This phenomenon has led to the birth of plasmonic catalysis. The rates of a variety of kinetically challenging reactions are enhanced by plasmon-excited nanostructures. While the potential utility for solar energy harvesting and chemical production is clear, there is a natural curiosity about the precise origin(s) of plasmonic catalysis. One explanation is that the reactions are facilitated by the action of the intensely concentrated and confined electric fields generated on the nanostructure upon LSPR excitation. Another mechanism of activation involves hot carriers transiently produced in the metal nanostructure by damping of LSPRs.In this Account, we visit a phenomenon that has received less attention but has a key role to play in plasmonic catalysis and chemistry. Under common chemical scenarios, plasmonic excitation induces a potential or a voltage on a nanoparticle. This photopotential modifies the energetics of a chemical reaction on noble metal nanoparticles. In a range of cases studied by our laboratory and others, light-induced potentials underlie the plasmonic enhancement of reaction kinetics. The photopotential model does not replace other known mechanisms, but it complements them. There are multiple ways in which an electrostatic photopotential is produced by LSPR excitation, such as optical rectification, but one that is most relevant in chemical media is asymmetric charge transfer to solution-phase acceptors. Electrons and holes produced in a nanostructure by damping of LSPRs are not removed at the same rate. As a result, the slower carrier accumulates on the nanostructure, and a steady-state charge is built up on the nanostructure, leading to a photopotential. Potentials of up to a few hundred millivolts have been measured by our laboratory and others. A photocharged nanoparticle is a source of carriers of a higher potential than an uncharged one. As a result, redox chemical reactions on noble metal nanoparticles exhibit lower activation barriers under photoexcitation. In electrochemical reactions on noble metal nanoparticles, the photopotential supplements the applied potential. In a diverse set of reactions, the photopotential model explains the photoenhancement of rates as well as the trends as a function of light intensity and photon energy. With further gains, light-induced potentials may be used as a knob for controlling the activities and selectivities of noble metal nanoparticle catalysts.
PubMed: 32786334
DOI: 10.1021/acs.accounts.0c00378 -
Physical Review Letters Jan 2023Vibrational dynamics in conventional molecules usually takes place on a timescale of picoseconds or shorter. A striking exception are ultralong-range Rydberg molecules,...
Vibrational dynamics in conventional molecules usually takes place on a timescale of picoseconds or shorter. A striking exception are ultralong-range Rydberg molecules, for which dynamics is dramatically slowed down as a consequence of the huge bond length of up to several micrometers. Here, we report on the direct observation of vibrational dynamics of a recently observed Rydberg-atom-ion molecule. By applying a weak external electric field of a few millivolts per centimeter, we are able to control the orientation of the photoassociated ultralong-range Rydberg molecules and induce vibrational dynamics by quenching the electric field. A high resolution ion microscope allows us to detect the molecule's orientation and its temporal vibrational dynamics in real space. Our study opens the door to the control of molecular dynamics in Rydberg molecules.
PubMed: 36706402
DOI: 10.1103/PhysRevLett.130.023002 -
Frontiers in Veterinary Science 2022Personalized healthcare technology has grown explosively through the use of portable and smart monitoring devices for diagnosis. The objective of this study was to...
BACKGROUND
Personalized healthcare technology has grown explosively through the use of portable and smart monitoring devices for diagnosis. The objective of this study was to determine the practicality and usability of the Equimetre fitness tracker on camels in comparison to the standard base-apex system in normal and clinical cases.
METHODS
Five apparently healthy adult camels, five clinical adult cases and two clinical calves were enrolled in this study. The camels were equipped with two monitoring systems: Equimetre and a standard base-apex electrocardiogarphy. Each tracing was evaluated for the normal ECG variable's measure, including heart rate beats per min, P-R, QRS, R-R, Q-T, S-T intervals, and P-R and S-T segments in seconds. The amplitudes for P, Q, R, S, and T-peaks were evaluated in millivolts.
RESULTS
Equimetre showed stability on ECG tracing with less movement artifacts compared with the standard base-apex system. Different polarities were observed for the P-waves and T-waves between the standard base-apex system and Equimetre. Both devices showed perfect agreement for heart rate (ICC = 1.00, ≥ 0.0001, 95% = 1.00-1.00) in healthy and clinical adults. A good correlation was observed for the R-R interval between the devices in healthy and clinical adults. A moderate correlation was observed between the devices for Q-peak in clinical adults, with no correlation in clinical calves.
CONCLUSIONS
This study demonstrated acceptable ECG measurements between the standard base-apex and Equimetre device. This suggests that Equimetre could be a useful device in camels for initial electrocardiographic examinations in remote areas such as deserts.
PubMed: 36713881
DOI: 10.3389/fvets.2022.963732 -
Nature Communications Feb 2021A graphdiyne-based artificial synapse (GAS), exhibiting intrinsic short-term plasticity, has been proposed to mimic biological signal transmission behavior. The impulse...
A graphdiyne-based artificial synapse (GAS), exhibiting intrinsic short-term plasticity, has been proposed to mimic biological signal transmission behavior. The impulse response of the GAS has been reduced to several millivolts with competitive femtowatt-level consumption, exceeding the biological level by orders of magnitude. Most importantly, the GAS is capable of parallelly processing signals transmitted from multiple pre-neurons and therefore realizing dynamic logic and spatiotemporal rules. It is also found that the GAS is thermally stable (at 353 K) and environmentally stable (in a relative humidity up to 35%). Our artificial efferent nerve, connecting the GAS with artificial muscles, has been demonstrated to complete the information integration of pre-neurons and the information output of motor neurons, which is advantageous for coalescing multiple sensory feedbacks and reacting to events. Our synaptic element has potential applications in bioinspired peripheral nervous systems of soft electronics, neurorobotics, and biohybrid systems of brain-computer interfaces.
Topics: Dendrites; Density Functional Theory; Diffusion; Graphite; Ions; Nerve Net; Neuronal Plasticity; Neurons, Efferent; Signal Transduction; Synapses; Temperature
PubMed: 33594066
DOI: 10.1038/s41467-021-21319-9 -
Science Advances Oct 2023Ionic liquid-based ionogels emerge as promising candidates for efficient ionic thermoelectric conversion due to their quasi-solid state, giant thermopower, high...
Ionic liquid-based ionogels emerge as promising candidates for efficient ionic thermoelectric conversion due to their quasi-solid state, giant thermopower, high flexibility, and good stability. P-type ionogels have shown impressive performance; however, the development of n-type ionogels lags behind. Here, an n-type ionogel consisting of polyethylene oxide (PEO), lithium salt, and ionic liquid is developed. Strong coordination of lithium ion with ether oxygen and the anion-rich clusters generated by ion-preferential association promote rapid transport of the anions and boost Eastman entropy change, resulting in a huge negative ionic Seebeck coefficient (-15 millivolts per kelvin) and a high electrical conductivity (1.86 millisiemens per centimeter) at 50% relative humidity. Moreover, dynamic and reversible interactions among the ternary mixtures endow the ionogel with fast autonomous self-healing capability and green recyclability. All PEO-based ionic thermoelectric modules are fabricated, which exhibits outstanding thermal responses (-80 millivolts per kelvin for three p-n pairs), demonstrating great potential for low-grade energy harvesting and ultrasensitive thermal sensing.
PubMed: 37878706
DOI: 10.1126/sciadv.adk2098 -
Science (New York, N.Y.) Jul 2023High-performance thermogalvanic cells have the potential to convert thermal energy into electricity, but their effectiveness is limited by the low concentration...
High-performance thermogalvanic cells have the potential to convert thermal energy into electricity, but their effectiveness is limited by the low concentration difference of redox ions. We report an in situ photocatalytically enhanced redox reaction that generates hydrogen and oxygen to realize a continuous concentration gradient of redox ions in thermogalvanic devices. A linear relation between thermopower and hydrogen production rate was established as an essential design principle for devices. The system exhibited a thermopower of 8.2 millivolts per kelvin and a solar-to-hydrogen efficiency of up to 0.4%. A large-area generator (112 square centimeters) consisting of 36 units yielded an open-circuit voltage of 4.4 volts and a power of 20.1 milliwatts, as well 0.5 millimoles of hydrogen and 0.2 millimoles of oxygen after 6 hours of outdoor operation.
PubMed: 37471552
DOI: 10.1126/science.adg0164 -
Sensors (Basel, Switzerland) Mar 2024The seafloor E-field signal is extremely weak and difficult to measured, even with a high signal-to-noise ratio. The preamplifier for electrodes is a key technology for...
The seafloor E-field signal is extremely weak and difficult to measured, even with a high signal-to-noise ratio. The preamplifier for electrodes is a key technology for ocean-bottom electromagnetic receivers. In this study, a chopper amplifier was proposed and developed to measure the seafloor E-field signal in the nanovolt to millivolt range at significantly low frequencies. It included a modulator, transformer, AC amplifier, high-impedance (hi-Z) module, demodulator, low-pass filter, and chopper clock generator. The injected charge in complementary metal-oxide semiconductor (CMOS) switches that form the modulator is the main source of 1/ noise. Combined with the principles of peak filtering and dead bands, a hi-Z module was designed to effectively reduce low-frequency noise. The chopper amplifier achieved an ultralow voltage noise of 0.6 nV/rt (Hz) at 1 Hz and 1.2 nV/rt (Hz) at 0.001 Hz. The corner frequency was less than 100 mHz, and there were few 1/ noises in the effective observation frequency band used for detecting electric fields. Each component is described with relevant tradeoffs that realize low noise in the low-frequency range. The amplifier was compact, measuring Ø 68 mm × H 12 mm, and had a low power consumption of approximately 23 mW (two channels). The fixed gain was 1500 with an input voltage range of 2.7 mV. The chopper amplifiers demonstrated stable performance in offshore geophysical prospecting applications.
PubMed: 38544183
DOI: 10.3390/s24061920 -
Giant negative thermopower of ionic hydrogel by synergistic coordination and hydration interactions.Science Advances Nov 2021The design of ultrasensitive ionic thermopiles is important for low-grade heat collection and temperature sensing. However, high-quality ionic thermoelectric materials...
The design of ultrasensitive ionic thermopiles is important for low-grade heat collection and temperature sensing. However, high-quality ionic thermoelectric materials with negative thermopower have been rarely reported to date. Effective adjustment of the interaction between the polymer network and the electrolyte anion/cation is an important method to achieve notable thermopower. Here, we demonstrate an ionic hydrogel thermoelectric material with giant negative thermopower obtained by synergistic coordination and hydration interactions. The ionic hydrogel, made of polyvinyl alcohol and sodium hydroxide, is prepared by simple dry-annealed process and exhibits a thermopower of up to −37.61 millivolts per kelvin, an extremely high absolute thermopower for electronic and ionic conductors. This ionic hydrogel is promising for the design of high-thermopower ionic thermoelectric materials and the low-grade heat energy harvesting.
PubMed: 34818039
DOI: 10.1126/sciadv.abi7233 -
ACS Applied Materials & Interfaces Jul 2023The advent of nonfullerene acceptors (NFAs) enabled records of organic photovoltaics (OPVs) exceeding 19% power conversion efficiency in the laboratory. However,...
The advent of nonfullerene acceptors (NFAs) enabled records of organic photovoltaics (OPVs) exceeding 19% power conversion efficiency in the laboratory. However, high-efficiency NFAs have so far only been realized in solution-processed blends. Due to its proven track record in upscaled industrial production, vacuum thermal evaporation (VTE) is of prime interest for real-world OPV commercialization. Here, we combine the benchmark solution-processed NFA Y6 with three different evaporated donors in a bilayer (planar heterojunction) architecture. We find that voltage losses decrease by hundreds of millivolts when VTE donors are paired with the NFA instead of the fullerene C, the current standard acceptor in VTE OPVs. By showing that evaporated small-molecule donors behave much like solution-processed donor polymers in terms of voltage loss when combined with NFAs, we highlight the immense potential for evaporable NFAs and the urgent need to direct synthesis efforts toward making smaller, evaporable compounds.
PubMed: 37348123
DOI: 10.1021/acsami.3c04282