Abstract
Power dissipation is a fundamental issue for future chip-based electronics. As promising channel materials, two-dimensional semiconductors show excellent capabilities of scaling dimensions ...and reducing off-state currents. However, field-effect transistors based on two-dimensional materials are still confronted with the fundamental thermionic limitation of the subthreshold swing of 60 mV decade
−1
at room temperature. Here, we present an atomic threshold-switching field-effect transistor constructed by integrating a metal filamentary threshold switch with a two-dimensional MoS
2
channel, and obtain abrupt steepness in the turn-on characteristics and 4.5 mV decade
−1
subthreshold swing (over five decades). This is achieved by using the negative differential resistance effect from the threshold switch to induce an internal voltage amplification across the MoS
2
channel. Notably, in such devices, the simultaneous achievement of efficient electrostatics, very small sub-thermionic subthreshold swings, and ultralow leakage currents, would be highly desirable for next-generation energy-efficient integrated circuits and ultralow-power applications.
This paper presents an analysis of the joint estimation of target location and velocity using a multiple-input multiple-output (MIMO) radar employing noncoherent processing for a complex Gaussian ...extended target. A MIMO radar with M transmit and N receive antennas is considered. To provide insight, we focus on a simplified case first, assuming orthogonal waveforms, temporally and spatially white noise-plus-clutter, and independent reflection coefficients. Under these simplifying assumptions, the maximum-likelihood (ML) estimate is analyzed, and a theorem demonstrating the asymptotic consistency, large MN , of the ML estimate is provided. Numerical investigations, given later, indicate similar behavior for some reasonable cases violating the simplifying assumptions. In these initial investigations, we study unconstrained systems, in terms of complexity and energy, where each added transmit antenna employs a fixed energy so that the total transmitted energy is allowed to increase as we increase the number of transmit antennas. Following this, we also look at constrained systems, where the total system energy and complexity are fixed. To approximate systems of fixed complexity in an abstract way, we restrict the total number of antennas employed to be fixed. Here, we show numerical examples which indicate a preference for receive antennas, similar to MIMO communications, but where systems with multiple transmit antennas yield the smallest possible mean-square error (MSE). The joint Cramér-Rao bound (CRB) is calculated and the MSE of the ML estimate is analyzed. It is shown for some specific numerical examples that the signal-to-clutter-plus-noise ratio (SCNR) threshold, indicating the SCNRs above which the MSE of the ML estimate is reasonably close to the CRB, can be lowered by increasing MN . The noncoherent MIMO radar ambiguity function (AF) is developed in two different ways and illustrated by examples. It is shown for some specific examples that the size of the product MN controls the levels of the sidelobes of the AF.
In this letter, we propose a reliable design of physical unclonable function (PUF) exploiting resistive random access memory (RRAM). Unlike the conventional silicon PUFs based on manufacturing ...process variation, the randomness of RRAM PUF comes from the stochastic switching mechanism and intrinsic variability of the RRAM devices. RRAM PUF's characteristics, such as uniqueness and reliability, are evaluated on 1 kb HfO 2 -based 1-transistor-1-resistor (1T1R) arrays. Our experimental results show that the selection of the reference current significantly affects the uniqueness. More dummy cells to generate the reference can improve the uniqueness of RRAM. The reliability of RRAM PUF is determined by the RRAM data retention. A new design is proposed where the sum of the readout currents of multiple RRAM cells is used for generating one response bit, which statistically minimizes the risk of early lifetime failure. The experimental results show that with eight cells per bit, the retention time is more than 50 h at 150 °C or equivalently 10 years at 69 °C. This experimental work demonstrates that RRAM PUF is a viable technology for hardware security primitive with inter-Hamming distance 49.8% and intra-Hamming distance 0%.
With the development in international food trade, there has been emerging risks in the food chain. Food contamination can be caused by several factors in a complex food chain. This articles provides ...a comprehensive review of known chemical contaminants from the production of raw materials to the consumption of food products as well as prevention and control measures. Specifically, this review discusses the following topics, raw material contamination caused by environmental pollution, endogenous food contamination caused by processing methods, and cold chain system challenges in food e-commerce.
Abstract
Diverse microscopic ionic dynamics help mediate the ability of a biological neural network to handle complex tasks with low energy consumption. Thus, rich internal ionic dynamics in ...memristors based on transition metal oxide are expected to provide a unique and useful platform for implementing energy‐efficient neuromorphic computing. To this end, a titanium oxide (TiO
x
)‐based interface‐type dynamic memristor and an niobium oxide (NbO
x
)‐based Mott memristor are integrated as an artificial dendrite and spike‐firing soma, respectively, to construct a dendritic neuron unit for realizing high‐efficiency spatial‐temporal information processing. Further, a dendritic neural network is hardware‐implemented for spatial‐temporal information processing to highlight the computational advantages achieved by incorporating dendritic functions in the network. Human motion recognition is demonstrated using the Nanyang Technological University‐Red Green Blue (NTU‐RGB) dataset as a benchmark spatial‐temporal task; it shows a nearly 20% improvement in accuracy for the memristors‐based hardware incorporating dendrites and a 1000× advantage in power efficiency compared to that of the graphics processing unit (GPU). The dendritic neuron developed in this study can be considered a critical building block for implementing more bio‐plausible neural networks that can manage complex spatial‐temporal tasks with high efficiency.
Spiking Neural Networks (SNNs) offer great potential to promote both the performance and efficiency of real-world computing systems, considering the biological plausibility of SNNs. The emerging ...analog Resistive Random Access Memory (RRAM) devices have drawn increasing interest as potential neuromorphic hardware for implementing practical SNNs. In this article, we propose a novel training approach (called greedy training) for SNNs by diluting spike events on the temporal dimension with necessary controls on input encoding phase switching, endowing SNNs with the ability to cooperate with the inevitable conductance variations of RRAM devices. The SNNs could utilize Spike-Timing-Dependent Plasticity (STDP) as the unsupervised learning rule, and this plasticity has been observed on our one-transistor-one-resistor (1T1R) RRAM devices under voltage pulses with designed waveforms. We have also conducted handwritten digit recognition task simulations on MNIST dataset. The results show that the unsupervised SNNs trained by the proposed method could mitigate the requirement for the number of gradual levels of RRAM devices, and also have immunity to both cycle-to-cycle and device-to-device RRAM conductance variations. Unsupervised SNNs trained by the proposed methods could cooperate with real RRAM devices with non-ideal behaviors better, promising high feasibility of RRAM array based neuromorphic systems for online training.
In the nervous system, dendrites, branches of neurons that transmit signals between synapses and soma, play a critical role in processing functions, such as nonlinear integration of postsynaptic ...signals. The lack of these critical functions in artificial neural networks compromises their performance, for example in terms of flexibility, energy efficiency and the ability to handle complex tasks. Here, by developing artificial dendrites, we experimentally demonstrate a complete neural network fully integrated with synapses, dendrites and soma, implemented using scalable memristor devices. We perform a digit recognition task and simulate a multilayer network using experimentally derived device characteristics. The power consumption is more than three orders of magnitude lower than that of a central processing unit and 70 times lower than that of a typical application-specific integrated circuit chip. This network, equipped with functional dendrites, shows the potential of substantial overall performance improvement, for example by extracting critical information from a noisy background with significantly reduced power consumption and enhanced accuracy.
Chicoric acid (CA), a polyphenolic acid compound extracted from chicory and echinacea, possesses antiviral, antioxidative and anti-inflammatory activities. Growing evidence supports the pivotal roles ...of brain-spleen and brain-gut axes in neurodegenerative diseases, including Parkinson's disease (PD), and the immune response of the spleen and colon is always the active participant in the pathogenesis and development of PD. In this study, we observe that CA prevented dopaminergic neuronal lesions, motor deficits and glial activation in PD mice, along with the increment in striatal brain-derived neurotrophic factor (BDNF), dopamine (DA) and 5-hydroxyindoleacetic acid (5-HT). Furthermore, CA reversed the level of interleukin-17(IL-17), interferon-gamma (IFN-γ) and transforming growth factor-beta (TGF-β) of PD mice, implicating its regulatory effect on the immunological response of spleen and colon. Transcriptome analysis revealed that 22 genes in the spleen (21 upregulated and 1 downregulated) and 306 genes (190 upregulated and 116 downregulated) in the colon were significantly differentially expressed in CA-pretreated mice. These genes were functionally annotated with GSEA, GO and KEGG pathway enrichment, providing the potential target genes and molecular biological mechanisms for the modulation of CA on the spleen and gut in PD. Remarkably, CA restored some gene expressions to normal level. Our results highlighted that the neuroprotection of CA might be associated with the manipulation of CA on brain-spleen and brain-gut axes in PD.
Isatin dimers and their biological activities Zhang, Ya‐Zhou; Du, Hong‐Zhi; Liu, Hai‐Lin ...
Archiv der Pharmazie (Weinheim),
March 2020, 2020-Mar, 2020-03-00, 20200301, Volume:
353, Issue:
3
Journal Article
Peer reviewed
Dimerization is a promising strategy to develop novel drug candidates that could extend the biological spectrum, enhance the activity, overcome drug resistance, as well as improve pharmacological, ...pharmacokinetic, and physicochemical profiles. Isatin dimers possess a broad spectrum of biological properties and the isatin dimer indirubin has already been used in the clinic, revealing the potential of isatin dimers as putative drugs. This review covers the recent advances of isatin dimers as pharmacologically significant scaffolds and the structure–activity relationship to set up the direction for the design and development of isatin dimers with higher efficiency and lower toxicity.
This review covers the recent advances in the investigation of isatin dimers as pharmacologically significant scaffolds and their structure–activity relationships to set up the direction for the design and development of isatin dimers with higher efficiency and lower toxicity
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