Abstract
An optoelectronic synapse having a multispectral color-discriminating ability is an essential prerequisite to emulate the human retina for realizing a neuromorphic visual system. Several ...studies based on the three-terminal transistor architecture have shown its feasibility; however, its implementation with a two-terminal memristor architecture, advantageous to achieving high integration density as a simple crossbar array for an ultra-high-resolution vision chip, remains a challenge. Furthermore, regardless of the architecture, it requires specific material combinations to exhibit the photo-synaptic functionalities, and thus its integration into various systems is limited. Here, we suggest an approach that can universally introduce a color-discriminating synaptic functionality into a two-terminal memristor irrespective of the kinds of switching medium. This is possible by simply introducing the molecular interlayer with long-lasting photo-enhanced dipoles that can adjust the resistance of the memristor at the light-irradiation. We also propose the molecular design principle that can afford this feature. The optoelectronic synapse array having a color-discriminating functionality is confirmed to improve the inference accuracy of the convolutional neural network for the colorful image recognition tasks through a visual pre-processing. Additionally, the wavelength-dependent optoelectronic synapse can also be leveraged in the design of a light-programmable reservoir computing system.
Security of Cached Content in NDN Dohyung Kim; Jun Bi; Vasilakos, Athanasios V. ...
IEEE transactions on information forensics and security,
12/2017, Letnik:
12, Številka:
12
Journal Article
Recenzirano
In Named-Data Networking (NDN), content is cached in network nodes and served for future requests. This property of NDN allows attackers to inject poisoned content into the network and isolate users ...from valid content sources. Since a digital signature is embedded in every piece of content in NDN architecture, poisoned content is discarded if routers perform signature verification; however, if every content is verified by every router, it would be overly expensive to do. In our preliminary work, we have suggested a content verification scheme that minimizes unnecessary verification and favors already verified content in the content store, which reduces the verification overhead by as much as 90% without failing to detect every piece of poisoned content. Under this scheme, however, routers are vulnerable to verification attack, in which a large amount of unverified content is accessed to exhaust system resources. In this paper, we carefully look at the possible concerns of our preliminary work, including verification attack, and present a simple but effective solution. The proposed solution mitigates the weakness of our preliminary work and allows this paper to be deployed for real-world applications.
Organic-inorganic metal halide perovskites have gained considerable attention for next-generation photovoltaic cells due to rapid improvement in power conversion efficiencies. However, fundamental ...understanding of underlying mechanisms related to light- and bias-induced effects at the nanoscale is still required. Here, structural variations of the perovskites induced by light and bias are systematically investigated using scanning probe microscopy techniques. We show that periodically striped ferroelastic domains, spacing between 40 to 350 nm, exist within grains and can be modulated significantly under illumination as well as by electric bias. Williamson-Hall analysis of X-ray diffraction results shows that strain disorder is induced by these applied external stimuli. We show evidence that the structural emergence of domains can provide transfer pathways for holes to a hole transport layer with positive bias. Our findings point to potential origins of I-V hysteresis in halide perovskite solar cells.
The use of extracorporeal membrane oxygenation (ECMO) in cases of near-fatal asthma (NFA) has increased, but the benefits and potential complications of this therapy have yet to be fully ...investigated.
Cases were extracted from the Extracorporeal Life Support Organization Registry between March 1992 and March 2016. All patients with a diagnosis of asthma (according to the International Classification of Diseases 9th edition), who also received ECMO, were extracted. Exclusion criteria included patients who underwent multiple courses of ECMO; those who received ECMO for cardiopulmonary resuscitation or cardiac dysfunction; and those with another primary diagnosis, such as sepsis. We analyzed survival to hospital discharge, complications, and clinical factors associated with in-hospital mortality, in patients with severe life-threatening NFA requiring ECMO support.
In total 272 patients were included. The mean time spent on ECMO was 176.4 hours. Ventilator settings, including rate, fraction of inspired oxygen (FiO
), peak inspiratory pressure (PIP), and mean airway pressure, significantly improved after ECMO initiation (rate (breaths/min), 19.0 vs. 11.3, p < 0.001; FiO
(%), 81.2 vs. 48.8, p < 0.001; PIP (cmH
O), 38.2 vs. 25.0, p < 0.001; mean airway pressure (cmH
O): 21.4 vs. 14.2, p < 0.001). In particular, driving pressure was significantly decreased after ECMO support (29.5 vs. 16.8 cmH
O, p < 0.001). The weaning success rate was 86.7%, and the rate of survival to hospital discharge was 83.5%. The total complication rate was 65.1%, with hemorrhagic complications being the most common (28.3%). Other complications included renal (26.8%), cardiovascular (26.1%), mechanical (24.6%), metabolic (22.4%), infection (16.5%), neurologic (4.8%), and limb ischemia (2.6%). Of the hemorrhagic complications, cannulation site hemorrhage was the most common (13.6%). Using multivariate logistic regression analysis, it was found that hemorrhage was associated with increased in-hospital mortality (odds ratio, 2.97; 95% confidence interval, 1.07-8.24; p = 0.036). Hemorrhage-induced death occurred in four patients (1.5%). The most common reason for death was organ failure (37.8%).
ECMO can provide adequate gas exchange and prevent lung injury induced by mechanical ventilation, and may be an effective bridging strategy to avoid aggressive ventilation in refractory NFA. However, careful management is required to avoid complications.
Ferroic Halide Perovskite Optoelectronics Liu, Yongtao; Kim, Dohyung; Ievlev, Anton V. ...
Advanced functional materials,
09/2021, Letnik:
31, Številka:
36
Journal Article
Recenzirano
Odprti dostop
Metal halide perovskites (MHPs) as one of the most active materials gained tremendous attention in the past decade because of their outstanding performance in optoelectronics. Owing to their ...perovskite structure, ferroelectricity is anticipated in this class of materials. However, whether MHPs are ferroelectric or not remains elusive. Recently, discussion regarding ferroelasticity in MHPs has been also raised. In addition, ionic motion and structural dynamics are well known in MHPs. The interplay of these phenomena including electric polarization, strain, ionic motion, and structural dynamics can have a significant impact on optoelectronics. Therefore, understanding the mechanism behind these phenomena and their interactions is critical in addressing the controversy about ferroicity of MHPs and developing functional devices. Here, the current findings about MHP's ferroicity are summarized and evaluated and a perspective for the future is provided. It is suggested that ionic motion and associated phenomena, coupled with ferroic behavior, are the main drivers behind MHPs functionality. The challenges are also discussed in probing MHPs’ ferroicity and what new measurement modalities are needed to fully understand and characterize MHP behavior. Finally, it is discussed how ferroic and strain can affect the optoelectronic performance of MHPs and how they can be used for engineering of higher performance devices.
This work discusses the current findings about the ferroicity of metal halide perovskites (MHPs) and the challenges in probing MHPs’ ferroicity. It is suggested that ionic motion and associated phenomena, coupled with ferroic behavior, are the main drivers behind MHPs functionality. Finally, how ferroicity and strain can affect the optoelectronic performance of MHPs is discussed.
Amorphous carbon layer (ACL) deposited by the capacitively coupled plasma (CCP), plasma-enhanced chemical vapor deposition (PE-CVD) is widely used in etching hard masks in the semiconductor industry. ...As the feature size of semiconductor devices decreased below 30 nm, a carbon hard mask film with high etching selectivity and high transparency is required. However, it is very difficult to deposit the amorphous carbon film with both high etching selectivity and high transparency by CCP type PE-CVD. In this study, ACL films were deposited by an inductively coupled plasma (ICP) type deposition system. We selected the ICP deposition method because it allows independent control of the plasma density and ion impingement energy. The ACL films deposited by the ICP system had higher film density than the density of ACL films deposited by PE-CVD system. Moreover, Raman spectroscopy analysis of the ICP-made ACL films showed diamond-like properties with a high ratio of sp3 bonding, which could be due to the optimal bias power in ICP during deposition. The dry-etching selectivity of ACL films linearly increased with the density of the film. These studies confirmed that ICP is an effective method for the deposition of carbon hard masks with high etching selectivity.
•Dry-etching carbon hard mask deposited by inductively coupled plasma (ICP) deposition•Properties of ICP deposited carbon film were controlled by radio-frequency bias power.•ICP-deposited diamond-like carbon film had high dry-etch selectivity and transparency.
Flow at various scales, such as perfusion flow and interstitial flow, is a critical component of the physiology of living systems. Microphysiological system (MPS), which is designed to mimic human ...physiology, needs to recapitulate various physiological flows to accurately reflect in vivo conditions. Most MPSs that simulate flows utilize a pump and tubing (pumped-based-flow MPS). However, these components have limitations that prevent them from recapitulating sophisticated physiological phenomena. Alternatively, passive-flow MPS can be used to recapitulate physiological flow on various scales without using pumps or tubing. This review presents recent developments in passive-flow-based MPS using various engineering approaches. To this end, engineering approaches that enable a passive-flow-based MPS to operate are summarized. Subsequently, representative examples of passive-flow-based MPS are reviewed under the criterion of whether they can recapitulate single-organ (tissue) or multi-organ (tissue) systems. It is our belief that passive-flow-based MPS will be widely used in a wide range of fields, such as human physiology research, analysis of pharmacokinetics and pharmacodynamics (PK/PD), and even space medicine research.
We report the discovery of room temperature in-plane ferroelectricity in van der Waals In
2
Se
3
with β′ phase.
Van der Waals (vdW) assembly of layered materials is a promising paradigm for creating ...electronic and optoelectronic devices with novel properties. Ferroelectricity in vdW layered materials could enable nonvolatile memory and low-power electronic and optoelectronic switches, but to date, few vdW ferroelectrics have been reported, and few in-plane vdW ferroelectrics are known. We report the discovery of in-plane ferroelectricity in a widely investigated vdW layered material, β′-In
2
Se
3
. The in-plane ferroelectricity is strongly tied to the formation of one-dimensional superstructures aligning along one of the threefold rotational symmetric directions of the hexagonal lattice in the
c
plane. Surprisingly, the superstructures and ferroelectricity are stable to 200°C in both bulk and thin exfoliated layers of In
2
Se
3
. Because of the in-plane nature of ferroelectricity, the domains exhibit a strong linear dichroism, enabling novel polarization-dependent optical properties.
We apply gas quenching to fabricate rubidium (Rb) incorporated perovskite films for high-efficiency perovskite solar cells achieving 20% power conversion efficiency on a 65 mm2 device. Both ...double-cation and triple-cation perovskites containing a combination of methylammonium, formamidinium, cesium, and Rb have been investigated. It is found that Rb is not fully embedded in the perovskite lattice. However, a small incorporation of Rb leads to an improvement in the photovoltaic performance of the corresponding devices for both double-cation and triple-cation perovskite systems.
This review article explores the transformative advancements in wearable biosignal sensors powered by machine learning, focusing on four notable biosignals: electrocardiogram (ECG), electromyogram ...(EMG), electroencephalogram (EEG), and photoplethysmogram (PPG). The integration of machine learning with these biosignals has led to remarkable breakthroughs in various medical monitoring and human–machine interface applications. For ECG, machine learning enables automated heartbeat classification and accurate disease detection, improving cardiac healthcare with early diagnosis and personalized interventions. EMG technology, combined with machine learning, facilitates real‐time prediction and classification of human motions, revolutionizing applications in sports medicine, rehabilitation, prosthetics, and virtual reality interfaces. EEG analysis powered by machine learning goes beyond traditional clinical applications, enabling brain activity understanding in psychology, neurology, and human–computer interaction, and holds promise in brain–computer interfaces. PPG, augmented with machine learning, has shown exceptional progress in diagnosing and monitoring cardiovascular and respiratory disorders, offering non‐invasive and accurate healthcare solutions. These integrated technologies, powered by machine learning, open new avenues for medical monitoring and human–machine interaction, shaping the future of healthcare.
The convergence of wearable biosignal sensors and machine learning paves the way for significant advancements in healthcare, enabling early medical diagnosis and personalized health monitoring. This review article provides an overview of recent transformative advancements in wearable biosignal sensors powered by machine learning, focusing on four notable biosignals: electrocardiogram, electromyogram, electroencephalogram, and photoplethysmogram.
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