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Scientific Reports May 2023Artificial electronic synapses are commonly used to simulate biological synapses to realize various learning functions, regarded as one of the key technologies in the...
Artificial electronic synapses are commonly used to simulate biological synapses to realize various learning functions, regarded as one of the key technologies in the next generation of neurological computation. This work used a simple spin coating technique to fabricate polyimide (PI):graphene quantum dots(GQDs) memristor structure. As a result, the devices exhibit remarkably stable exponentially decaying postsynaptic suppression current over time, as interpreted in the spike-timing-dependent plasticity phenomenon. Furthermore, with the increase of the applied electrical signal over time, the conductance of the electrical synapse gradually changes, and the electronic synapse also shows plasticity dependence on the amplitude and frequency of the pulse applied. In particular, the devices with the structure of Ag/PI:GQDs/ITO prepared in this study can produce a stable response to the stimulation of electrical signals between millivolt to volt, showing not only high sensitivity but also a wide range of "feelings", which makes the electronic synapses take a step forwards to emulate biological synapses. Meanwhile, the electronic conduction mechanisms of the device are also studied and expounded in detail. The findings in this work lay a foundation for developing brain-like neuromorphic modeling in artificial intelligence.
PubMed: 37210533
DOI: 10.1038/s41598-023-35183-8 -
Science (New York, N.Y.) May 2023Discovery of earth-abundant electrocatalysts to replace iridium for the oxygen evolution reaction (OER) in a proton exchange membrane water electrolyzer (PEMWE)...
Discovery of earth-abundant electrocatalysts to replace iridium for the oxygen evolution reaction (OER) in a proton exchange membrane water electrolyzer (PEMWE) represents a critical step in reducing the cost for green hydrogen production. We report a nanofibrous cobalt spinel catalyst codoped with lanthanum (La) and manganese (Mn) prepared from a zeolitic imidazolate framework embedded in electrospun polymer fiber. The catalyst demonstrated a low overpotential of 353 millivolts at 10 milliamperes per square centimeter and a low degradation for OER over 360 hours in acidic electrolyte. A PEMWE containing this catalyst at the anode demonstrated a current density of 2000 milliamperes per square centimeter at 2.47 volts (Nafion 115 membrane) or 4000 milliamperes per square centimeter at 3.00 volts (Nafion 212 membrane) and low degradation in an accelerated stress test.
PubMed: 37167381
DOI: 10.1126/science.ade1499 -
Klinische Monatsblatter Fur... Apr 2023To assess optic nerve head (ONH) and macular blood flow in young healthy volunteers using laser speckle flowgraphy (LSFG).
PURPOSE
To assess optic nerve head (ONH) and macular blood flow in young healthy volunteers using laser speckle flowgraphy (LSFG).
METHODS
This is a prospective single-center study conducted at the Department of Ophthalmology, University Hospital Zurich from May to November 2021. Young, healthy men aged ≥ 18 years without ocular or systemic diseases were included. A corrected visual acuity (VA) of 0.0 logMAR or better in both eyes and an intraocular pressure (IOP) of 21 mmHg or lower were required for inclusion. Subjects exceeding a spherical equivalent (SE) of ± 6 diopters (dpt) were excluded. Blood flow in the macula and the ONH was recorded using the Nidek LSFG RetFlow device (Nidek Company, Ltd., Hirioshi-cho, Japan). Laser power was set to 0.5 Millivolts (mV). Mean blur rate (MBR) was recorded as a parameter for blood flow. MBR is a calculated parameter that represents relative blood flow velocity correlated with the real anatomical blood flow rate. Colored heat maps of the recorded retinal area were generated automatically by the RetFlow device.
RESULTS
Final analyses included 83 eyes of 43 male volunteers. Mean age was 21.9 years (SD ± 1.5, range: 20 to 29). Mean corrected VA was - 0.1 logMAR (SD ± 0.05, range: - 0.2 to 0.0), mean IOP was 15.4 mmHg (SD ± 2.5, range: 8.5 to 18.5), and mean SE was - 0.3 dpt (SD ± 1.2, range: - 5.0 to 1.2). Mean ONH MBR was 37.44 (SD ± 7.9, range: 22.5 to 53.5) and mean macular MBR was 27.8 (SD ± 9.7, range: 6.4 to 57.7). Pearson's Test showed a strong correlation between macular and papillary blood flow (p < 0.05, coefficient: 0.647).
CONCLUSION
This study provides both ONH and macular blood flow data in a healthy young male population, showing a strong correlation between ONH and macular blood flow in the examined eyes. Further investigations are required to assess the validity of MBR as a parameter for the combined evaluation of retinal blood flow at the macula and ONH in healthy volunteers and patients with various diseases.
Topics: Humans; Male; Young Adult; Adult; Optic Disk; Healthy Volunteers; Prospective Studies; Regional Blood Flow; Blood Flow Velocity; Lasers
PubMed: 37164413
DOI: 10.1055/a-2026-0924 -
Nano-micro Letters Apr 2023Ionic thermoelectrics (i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin....
Ionic thermoelectrics (i-TE) possesses great potential in powering distributed electronics because it can generate thermopower up to tens of millivolts per Kelvin. However, as ions cannot enter external circuit, the utilization of i-TE is currently based on capacitive charge/discharge, which results in discontinuous working mode and low energy density. Here, we introduce an ion-electron thermoelectric synergistic (IETS) effect by utilizing an ion-electron conductor. Electrons/holes can drift under the electric field generated by thermodiffusion of ions, thus converting the ionic current into electrical current that can pass through the external circuit. Due to the IETS effect, i-TE is able to operate continuously for over 3000 min. Moreover, our i-TE exhibits a thermopower of 32.7 mV K and an energy density of 553.9 J m, which is more than 6.9 times of the highest reported value. Consequently, direct powering of electronics is achieved with i-TE. This work provides a novel strategy for the design of high-performance i-TE materials.
PubMed: 37052861
DOI: 10.1007/s40820-023-01077-7 -
Science (New York, N.Y.) Apr 2023The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal...
The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal grains along specific orientations. We present a seed-passivated texturing process to fabricate textured PZT ceramics by using newly developed Ba(Zr,Ti)O microplatelet templates. This process not only ensures the template-induced grain growth in titanium-rich PZT layers but also facilitates desired composition through interlayer diffusion of zirconium and titanium. We successfully prepared textured PZT ceramics with outstanding properties, including Curie temperatures of 360°C, piezoelectric coefficients of 760 picocoulombs per newton and of 100 millivolt meters per newton, and electromechanical couplings of 0.85. This study addresses the challenge of fabricating textured rhombohedral PZT ceramics by suppressing the otherwise severe chemical reaction between PZT powder and titanate templates.
PubMed: 37023196
DOI: 10.1126/science.adf6161 -
Nano Letters Apr 2023Highly uniform quantum systems are essential for the practical implementation of scalable quantum processors. While quantum dot spin qubits based on semiconductor...
Highly uniform quantum systems are essential for the practical implementation of scalable quantum processors. While quantum dot spin qubits based on semiconductor technology are a promising platform for large-scale quantum computing, their small size makes them particularly sensitive to their local environment. Here, we present a method to electrically obtain a high degree of uniformity in the intrinsic potential landscape using hysteretic shifts of the gate voltage characteristics. We demonstrate the tuning of pinch-off voltages in quantum dot devices over hundreds of millivolts that then remain stable at least for hours. Applying our method, we homogenize the pinch-off voltages of the plunger gates in a linear array for four quantum dots, reducing the spread in pinch-off voltages by one order of magnitude. This work provides a new tool for the tuning of quantum dot devices and offers new perspectives for the implementation of scalable spin qubit arrays.
PubMed: 36975126
DOI: 10.1021/acs.nanolett.2c04446 -
Investigative Ophthalmology & Visual... Mar 2023The purpose of this study was to compare 24-hour intraocular pressure (IOP) related fluctuations monitoring between 2 groups of visual field progression rates in...
PURPOSE
The purpose of this study was to compare 24-hour intraocular pressure (IOP) related fluctuations monitoring between 2 groups of visual field progression rates in patients with open angle glaucoma (OAG).
METHODS
Cross-sectional study performed at Bordeaux University Hospital. Twenty-four-hour monitoring was performed using a contact lens sensor (CLS; Triggerfish; SENSIMED, Etagnières, Switzerland). Progression rate was calculated using a linear regression of the mean deviation (MD) parameter of the visual field test (Octopus; HAAG-STREIT, Switzerland). Patients were allocated into two groups: group 1 with an MD progression rate <-0.5 dB/year and group 2 with an MD progression rate ≥-0.5 dB/year. An automatic signal-processing program was developed and a frequency filtering of the monitoring by wavelet transform analysis was used to compare the output signal between the two groups. A multivariate classifier was performed for prediction of the faster progression group.
RESULTS
Fifty-four eyes of 54 patients were included. The mean progression rate was -1.09 ± 0.60 dB/year in group 1 (n = 22) and -0.12 ± 0.13 dB/year in group 2 (n = 32). Twenty-four-hour magnitude and absolute area under the monitoring curve were significantly higher in group 1 than in group 2 (group 1: 343.1 ± 62.3 millivolts [mVs] and 8.28 ± 2.10 mVs, respectively, group 2: 274.0 ± 75.0 mV and 6.82 ± 2.70 mVs respectively, P < 0.05). Magnitude and area under the wavelet curve for short frequency periods ranging from 60 to 220 minutes were also significantly higher in group 1 (P < 0.05).
CONCLUSIONS
The 24-hour IOP related fluctuations characteristics, as assessed by a CLS, may act as a risk factor for progression in OAG. In association with other predictive factors of glaucoma progression, the CLS may help adjust treatment strategy earlier.
Topics: Humans; Intraocular Pressure; Glaucoma, Open-Angle; Cross-Sectional Studies; Glaucoma; Contact Lenses
PubMed: 36862120
DOI: 10.1167/iovs.64.3.3 -
Sensors (Basel, Switzerland) Jan 2023Levels of lead (Pb) in tap water that are well below established guidelines are now considered harmful, so the detection of sub-parts-per-billion (ppb) Pb levels is...
Levels of lead (Pb) in tap water that are well below established guidelines are now considered harmful, so the detection of sub-parts-per-billion (ppb) Pb levels is crucial. In this work, we developed a two-step, facile, and inexpensive fabrication approach that involves direct bonding of copper (Cu) and liquid crystal polymer (LCP) followed by polyester resin printing for masking onto Cu/LCP to fabricate Cu thin-film-based Pb sensors. The oxygen plasma-treated surfaces resulted in strongly bonded Cu/LCP with a high peel strength of 500 N/m due to the highly hydrophilic nature of both surfaces. The bonded specimen can withstand wet etching of the electrode and can address delamination of the electrode for prolonged use in application environments. The Cu-foil-based electrochemical sensor showed sensitivity of ~11 nA/ppb/cm and a limit of detection (LOD) of 0.2 ppb (0.2 µg/L) Pb ions in water. The sensor required only 30 s and a 100 µL sample to detect Pb. To date, this is the most rapid detection of Pb performed using an all-Cu-based sensor. The selectivity test of Cu to Pb with interferences from cadmium and zinc showed that their peaks were separated by a few hundred millivolts. This approach has strong potential towards realizing low-cost, highly reliable integrated water quality monitoring systems.
PubMed: 36772462
DOI: 10.3390/s23031424 -
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 -
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