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Advanced Materials (Deerfield Beach,... May 2024Integration of molecular switching units into complex electronic circuits is considered to be the next step towards the realization of novel logic and memory devices....
Integration of molecular switching units into complex electronic circuits is considered to be the next step towards the realization of novel logic and memory devices. Here, we report on an ordered 2D network of neighboring ternary switching units represented by triazatruxene (TAT) molecules organized in a honeycomb lattice on a Ag(111) surface. Using low-temperature scanning tunneling microscopy, we are able to control the bonding configurations of individual TAT molecules within the lattice, realizing up to 12 distinct states per molecule. The switching between those states shows a particularly strong bias dependence ranging from tens of millivolts to volts. Based on a single TAT molecule as a fundamental building block, we then explore the low-bias switching behavior in units consisting of two and more interacting TAT molecules purposefully defined by the high-bias switching within the honeycomb lattice. we demonstrate the possibility to realize up to 9 and 19 distinguishable states in a dyad and a tetrad of coupled switching units, respectively. The switching dynamics can be triggered and accessed by single-point measurements on a single molecule. High experimental control over the desired state, owing to hierarchical switching and pronounced switching directionality, as well as the observed full reversibility, makes this system particularly appealing, paving the way to design complex molecule-based memory systems. This article is protected by copyright. All rights reserved.
PubMed: 38749066
DOI: 10.1002/adma.202401662 -
Fiziologicheskii Zhurnal SSSR Imeni I.... Mar 1979In chronic experiments on monkeys and cats, the effects of intracerebral micropolarization modulating memory processes, on the mV potential of cerebral structures, were... (Comparative Study)
Comparative Study
In chronic experiments on monkeys and cats, the effects of intracerebral micropolarization modulating memory processes, on the mV potential of cerebral structures, were studied. A connection was revealed between trace fixing and processes of systemic kindling on the one hand, and the following stabilizing of mV potential, on the other hand. The data obtained suggest that the distant changes of the mV potential reflect a general "tuning" of cerebral systems, are realized by means of specialized regulatory neuronal networks and connected with shifts in metabolic processes.
Topics: Animals; Brain; Cats; Caudate Nucleus; Electric Stimulation; Electrophysiology; Haplorhini; Hippocampus; Memory; Motor Cortex; Pentobarbital; Pentylenetetrazole; Seizures; Temporal Lobe
PubMed: 110624
DOI: No ID Found -
Journal of Visualized Experiments : JoVE Feb 2020Recent advances in neuroprosthetics have enabled those living with extremity loss to reproduce many functions native to the absent extremity, and this is often...
Recent advances in neuroprosthetics have enabled those living with extremity loss to reproduce many functions native to the absent extremity, and this is often accomplished through integration with the peripheral nervous system. Unfortunately, methods currently employed are often associated with significant tissue damage which prevents prolonged use. Additionally, these devices often lack any meaningful degree of sensory feedback as their complex construction dampens any vibrations or other sensations a user may have previously depended on when using more simple prosthetics. The composite regenerative peripheral nerve interface (C-RPNI) was developed as a stable, biologic construct with the ability to amplify efferent motor nerve signals while providing simultaneous afferent sensory feedback. The C-RPNI consists of a segment of free dermal and muscle graft secured around a target mixed sensorimotor nerve, with preferential motor nerve reinnervation of the muscle graft and sensory nerve reinnervation of the dermal graft. In rats, this construct has demonstrated the generation of compound muscle action potentials (CMAPs), amplifying the target nerve's signal from the micro- to milli-volt level, with signal to noise ratios averaging approximately 30-50. Stimulation of the dermal component of the construct generates compound sensory nerve action potentials (CSNAPs) at the proximal nerve. As such, this construct has promising future utility towards the realization of the ideal, intuitive prosthetic.
Topics: Action Potentials; Animals; Female; Male; Nerve Regeneration; Peripheral Nerves; Rats; Rats, Inbred F344
PubMed: 32176203
DOI: 10.3791/60841 -
IEEE Transactions on Neural Systems and... Jul 2019This paper presents a new method of reducing the noise in the EEG response signal recorded during repetitive transcranial magnetic stimulation (rTMS). This noise is...
This paper presents a new method of reducing the noise in the EEG response signal recorded during repetitive transcranial magnetic stimulation (rTMS). This noise is principally composed of the residual stimulus artefact and millivolt amplitude compound muscle action potentials (CMAP) recorded from the scalp muscles and precludes analysis of the cortical evoked potentials, especially during the first 20-ms post stimulus. The proposed method uses the wavelet transform with a fourth-order Daubechies mother wavelet and a novel coefficient reduction algorithm based on cortical amplitude thresholds. Four other mother wavelets as well as digital filtering have been tested, and the Coiflets 2 and 3 also found to be effective with Coiflet 3 results marginally better than Daubechies 4. The approach has been tested using data recorded from 16 normal subjects during a study of cortical sensitivity to rTMS at different cortical locations using stimulation amplitudes, frequencies, and sites typically used in clinical practice to treat major depressive disorder.
Topics: Action Potentials; Adult; Algorithms; Artifacts; Computer Simulation; Depressive Disorder, Major; Electroencephalography; Electromyography; Female; Healthy Volunteers; Humans; Male; Middle Aged; Muscle, Skeletal; Scalp; Transcranial Magnetic Stimulation; Wavelet Analysis; Young Adult
PubMed: 30951471
DOI: 10.1109/TNSRE.2019.2908951 -
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 -
ACS Nano May 2024The subnanometer distance between tip and sample in a scanning tunneling microscope (STM) enables the application of very large electric fields with a strength as high...
The subnanometer distance between tip and sample in a scanning tunneling microscope (STM) enables the application of very large electric fields with a strength as high as ∼1 GV/m. This has allowed for efficient electrical driving of Rabi oscillations of a single spin on a surface at a moderate radiofrequency (RF) voltage on the order of tens of millivolts. Here, we demonstrate the creation of dressed states of a single electron spin localized in the STM tunnel junction by using resonant RF driving voltages. The read-out of these dressed states was achieved all electrically by a weakly coupled probe spin. Our work highlights the strength of the atomic-scale geometry inherent to the STM that facilitates the creation and control of dressed states, which are promising for the design of atomic scale quantum devices using individual spins on surfaces.
PubMed: 38698541
DOI: 10.1021/acsnano.4c00196 -
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 -
Ion-Mediated Polymerase Chain Reactions Performed with an Electronically Driven Microfluidic Device.Angewandte Chemie (International Ed. in... Sep 2016The polymerase chain reaction (PCR) is a powerful method for exponentially amplifying very low amounts of target DNA from genetic, clinical, and forensic samples....
The polymerase chain reaction (PCR) is a powerful method for exponentially amplifying very low amounts of target DNA from genetic, clinical, and forensic samples. However, the heating and cooling steps in PCR largely hamper the miniaturization of thermocyclers for on-site detection of pathogens and point-of-care tests. Herein, we devise an ion-mediated PCR (IM-PCR) strategy by exploiting ion-induced DNA denaturation/renaturation cycles. DNA duplexes are effectively denatured in alkaline solutions; whereas, the denatured single-stranded DNA strands readily reform duplexes at neutral pH. By using an integrated microchip that can programmably control the solution pH simply switching the potential in a range of several hundred millivolts, we can trigger IM-PCR at a constant temperature. Analogously to thermal cycling, 30 cycles of pH-induced denaturation/renaturation were used to amplify protein DNA fragments as confirmed by DNA sequencing. We anticipate that this portable, low-cost, and scalable IM-PCR holds great promise for widespread biological, clinical, and environmental applications.
PubMed: 27611873
DOI: 10.1002/anie.201606137 -
Plant Physiology Apr 1990Fe-efficient plants respond to iron stress both by morphological and physiological modifications. In roots of a Fe-efficient plant (Cucumis sativus L.) grown in the...
Fe-efficient plants respond to iron stress both by morphological and physiological modifications. In roots of a Fe-efficient plant (Cucumis sativus L.) grown in the presence or in the absence of iron, the capacity to acidify the external medium, change in the transmembrane electrical potential, and the ATPase activity have been determined. Roots from plants grown in the absence of iron showed a great capacity to acidify the external medium, a higher transmembrane electrical potential difference (-145 millivolts, versus -105 millivolts), and a higher ATPase activity (+30%). The administration of Fe(2+), but not Fe(3+), caused a block of the acidification capacity, a great decrease in the transmembrane electrical potential difference in root cells, and a large inhibition of the ATPase activity of isolated microsomal membrane vesicles.
PubMed: 16667404
DOI: 10.1104/pp.92.4.908 -
ACS Applied Materials & Interfaces Jul 2015The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this...
The mechanical and electrochemical properties are coupled through a piezo-electrochemical effect in Li-intercalated carbon fibers. It is demonstrated that this piezo-electrochemical effect makes it possible to harvest electrical energy from mechanical work. Continuous polyacrylonitrile-based carbon fibers that can work both as electrodes for Li-ion batteries and structural reinforcement for composites materials are used in this study. Applying a tensile force to carbon fiber bundles used as Li-intercalating electrodes results in a response of the electrode potential of a few millivolts which allows, at low current densities, lithiation at higher electrode potential than delithiation. More electrical energy is thereby released from the cell at discharge than provided at charge, harvesting energy from the mechanical work of the applied force. The measured harvested specific electrical power is in the order of 1 μW/g for current densities in the order of 1 mA/g, but this has a potential of being increased significantly.
PubMed: 26061792
DOI: 10.1021/acsami.5b02585