Monolayer of 2D transition metal dichalcogenides, with a thickness of less than 1 nm, paves a feasible path to the development of ultrathin memristive synapses, to fulfill the requirements for constructing large-scale high density 3D stacking neuromorphic chips. Herein, memristive devices based on monolayer n-MoS on p-Si substrate with a large self-rectification ratio, exhibiting photonic potentiation and electric habituation, are successfully fabricated. Versatile synaptic neuromorphic functions, such as potentiation/habituation, short-term/long-term plasticity, and paired-pulse facilitation, are successfully mimicked based on the inherent persistent photoconductivity performance and the volatile resistive switching behavior. These findings demonstrate the potential applications of ultrathin transition metal dichalcogenides for memristive synapses. These memristive synapses with the combination of photonic and electric neuromorphic functions have prospective in the applications of synthetic retinas and optoelectronic interfaces for integrated photonic circuits based on mixed-mode electro-optical operation.

This work investigated degradation (measured by qPCR) and biological deactivation (measured by culturebased natural transformation) of extra-and intracellular antibiotic resistance genes (eARGs and iARGs) by free available chlorine (FAC), NH 2 Cl, O 3 , ClO 2 , and UV light (254 nm), and of eARGs by • OH, using a chromosomal ARG (blt) of multidrug-resistant Bacillus subtilis 1A189. Rate constants for degradation of four 266−1017 bp amplicons adjacent to or encompassing the acfA mutation enabling blt overexpression increased in proportion to #AT+GC bps/ amplicon, or in proportion to #5′-GG-3′ or 5′-TT-3′ doublets/amplicon, with respective values ranging from 0.59 to 2.3 (×10 11 M −1 s −1 ) for • OH, 1.8−6.9 (×10 4 M −1 s −1 ) for O 3 , 3.9−9.2 (×10 3 M −1 s −1 ) for FAC, 0.35−1.2(×10 1 M −1 s −1 ) for ClO 2 , and 2.0−8.8 (×10 −2 cm 2 /mJ) for UV at pH 7, and from 1.7−4.4 M −1 s −1 for NH 2 Cl at pH 8. For FAC, NH 2 Cl, O 3 , ClO 2 , and UV, ARG deactivation paralleled degradation of amplicons approximating a ∼800−1000 bp acfA-flanking sequence required for natural transformation in B. subtilis, whereas deactivation outpaced degradation for • OH. At practical disinfectant exposures, eARGs and iARGs were ≥90% degraded/deactivated by FAC, O 3 , and UV, but recalcitrant to NH 2 Cl and ClO 2 . iARG degradation/deactivation always lagged cell inactivation. These findings provide a quantitative framework for evaluating ARG fate during disinfection/oxidation, and support using qPCR as a proxy for tracking ARG deactivation under carefully selected circumstances.

We have developed a template-free procedure to synthesize Co3O4 hollow-structured nanoparticles on a Vulcan XC-72 carbon support. The material was synthesized via an impregnation-reduction method followed by air oxidation. In contrast to spherical particles, the hollow-structured Co3O4 nanoparticles exhibited excellent lithium storage capacity, rate capability, and cycling stability when used as the anode material in lithium-ion batteries. Electrochemical testing showed that the hollow-structured Co3O4 particles delivered a stable reversible capacity of about 880 mAh/g (near the theoretical capacity of 890 mAh/g) at a current density of 50 mA/g after 50 cycles. The superior electrochemical performance is attributed to its unique hollow structure, which combines nano- and microscale properties that facilitate electron transfer and enhance structural robustness.

model, and the leaky integrate-and-fire (LIF) model. The HH model, which is the closest to a biological neuron, focuses on the variation of the conductance of the ionic channels and the bioinspired spikes. However, the HH model is too complex for practical applications. [8] The functions of integration and firing in a neuron are more clearly presented in the IF and LIF models. The IF and LIF models focus on whether a neuron should fire a spike or not by comparing the local graded potential (LGP) with the threshold. The IF neuron will retain LGP boosting forever until it fires, even when it receives a subthreshold signal. Unlike the IF model, the LGP in the LIF neuron leaks out in a short time when it is lower than the threshold, which is exactly in line with what happens in a biological neuron. In addition to the leaky integrate-andfire functions, bioinspired spikes with hyperpolarization, i.e., the spike from an HH neuron, are critical in modulating firing characteristics and synaptic plasticity. For example, a hyperpolarization-activated cation current helps a neuron to respond to a synaptic change faster. [9] The transition at some synapses can also be enhanced by the hyperpolarization current. [10] Since synaptic plasticity is the basis of neuromorphic computing, fast synaptic changes will make the computing more efficient. For a neural network, especially a spike neural network, information is encoded in the spikes. Noise signals are unavoidable; however, the hyperpotential can be used as a fingerprint to remove the noise signals in the spike trains to improve the efficiency and accuracy of the neuromorphic computing.Artificial neurons based on memristive devices have been reported. An HH axon was realized with a circuit based on two Mott memristors and two parallel capacitors. [11] Simplified passive neurons consisting of parallel threshold switching (TS) and capacitors were also put forward, [12] in which accumulating charges in the capacitor increase the partial voltage of the TS device, promoting threshold switching. Afterward, the capacitor begins to discharge, forming the voltage or current pulses, i.e., spikes. Recently, Yang and co-workers constructed an artificial neuron with stochastic leaky integrate-and-fire dynamics and tunable integration time, and integrated the neuron in a fully memristive artificial neural network for pattern classification and associative learning. [13] IBM researchers implemented a stochastic neuron with IF functions based on nonvolatile phase change memristors, while the LGP was represented by the Artificial neurons with functions such as leaky integrate-and-fire (LIF) and spike output are essential for brain-inspired computation with high efficiency. However, previously implemented artificial neurons, e.g., Hodgkin-Huxley (HH) neurons, integrate-and-fire (IF) neurons, and LIF neurons, only achieve partial functionality of a biological neuron. In this work, quasi-HH neurons with leaky integrate-and-fire functions are physically demonstrated with a volatile memristive devi...

Degradation kinetics of antibiotic resistance genes (ARGs) by free available chlorine (FAC), ozone (O3), and UV254 light (UV) were investigated in phosphate buffered solutions at pH 7 using a chromosomal ARG (mecA) of methicillin-resistant Staphylococcus aureus (MRSA). For FAC, the degradation rates of extracellular mecA (extra-mecA) were accelerated with increasing FAC exposure, which could be explained by a two-step FAC reaction model. The degradation of extra-mecA by O3 followed second-order reaction kinetics. The degradation of extra-mecA by UV exhibited tailing kinetics, which could be described by a newly proposed kinetic model considering cyclobutane pyrimidine dimer (CPD) formation, its photoreversal, and irreversible (6–4) photoproduct formation. Measured rate constants for extra-mecA increased linearly with amplicon length for FAC and O3, or with number of intrastrand pyrimidine doublets for UV, which enabled prediction of degradation rate constants of extra-mecA amplicons based on sequence length and/or composition. In comparison to those of extra-mecA, the observed degradation rates of intracellular mecA (intra-mecA) were faster for FAC and O3 at low oxidant exposures but significantly slower at high exposures for FAC and UV. Differences in observed extra- and intracellular kinetics could be due to decreased DNA recovery efficiency and/or the presence of MRSA aggregates protected from disinfectants.