Neuromorphic electro-stimulation based on atomically thin semiconductor for damage-free inflammation inhibition.

Inflammation, caused by accumulation of inflammatory cytokines from immunocytes, is prevalent in a variety of diseases. Electro-stimulation emerges as a promising candidate for inflammatory inhibition. Although electroacupuncture is free from surgical injury, it faces the challenges of imprecise pathways/current spikes, and insufficiently defined mechanisms, while non-optimal pathway or spike would require high current amplitude, which makes electro-stimulation usually accompanied by damage and complications. Here, we propose a neuromorphic electro-stimulation based on atomically thin semiconductor floating-gate memory interdigital circuit. Direct stimulation is achieved by wrapping sympathetic chain with flexible electrodes and floating-gate memory are programmable to fire bionic spikes, thus minimizing nerve damage. A substantial decrease (73.5%) in inflammatory cytokine IL-6 occurred, which also enabled better efficacy than commercial stimulator at record-low currents with damage-free to sympathetic neurons. Additionally, using transgenic mice, the anti-inflammation effect is determined by ß2 adrenergic signaling from myeloid cell lineage (monocytes/macrophages and granulocytes).

An ultrasmall organic synapse for neuromorphic computing.

High-performance organic neuromorphic devices with miniaturized device size and computing capability are essential elements for developing brain-inspired humanoid intelligence technique. However, due to the structural inhomogeneity of most organic materials, downscaling of such devices to nanoscale and their high-density integration into compact matrices with reliable device performance remain challenging at the moment. Herein, based on the design of a semicrystalline polymer PBFCL10 with ordered structure to regulate dense and uniform formation of conductive nanofilaments, we realize an organic synapse with the smallest device dimension of 50 nm and highest integration size of 1 Kb reported thus far. The as-fabricated PBFCL10 synapses can switch between 32 conductance states linearly with a high cycle-to-cycle uniformity of 98.89% and device-to-device uniformity of 99.71%, which are the best results of organic devices. A mixed-signal neuromorphic hardware system based on the organic neuromatrix and FPGA controller is implemented to execute spiking-plasticity-related algorithm for decision-making tasks.

An ultrafast bipolar flash memory for self-activated in-memory computing.

In-memory computing could enhance computing energy efficiency by directly implementing multiply accumulate (MAC) operations in a crossbar memory array with low energy consumption (around femtojoules for a single operation). However, a crossbar memory array cannot execute nonlinear activation; moreover, activation processes are power-intensive (around milliwatts), limiting the overall efficiency of in-memory computing. Here we develop an ultrafast bipolar flash memory to execute self-activated MAC operations. Based on atomically sharp van der Waals heterostructures, the basic flash cell has an ultrafast n/p program speed in the range of 20-30 ns and an endurance of 8 × 106 cycles. Utilizing sign matching between the input voltage signal and the storage charge type, our bipolar flash can realize a rectified linear unit activation function during the MAC process with a power consumption for each operation of just 30 nW (or 5 fJ of energy). Using a convolutional neural network, we find that the self-activated MAC method has a simulated accuracy of 97.23%, tested on the Modified National Institute of Standards and Technology dataset, which is close to the conventional method where the MAC and activation operations are separated.

Experimental Research on Seepage Law and Migration Characteristics of Core-Shell Polymeric Nanoparticles Dispersion System in Porous Media.

The nanoparticles dispersion system has complex migration characteristics and percolation law in porous media due to the interaction between the nanoparticles and porous media. In this paper, lab experiments were carried out to characterize the morphology, particle size distributions, and apparent viscosities of SiO2/P(MBAAm-co-AM) polymeric nanoparticle solution, investigate its migration characteristics in porous media, and probe its capability of enhanced oil recovery (EOR) in the reservoirs. Quartz microtubule, sand pack, and etched glass micromodels were used as the porous media in the flow and flooding experiments. Gray image-processing technology was applied to achieve oil saturation at different flooding stages in the micromodel for calculating the EOR of the SiO2/P(MBAAm-co-AM) polymeric nanoparticle solution. The results show that The SiO2/P(MBAAm-co-AM) polymeric nanoparticles are spherical with diameters ranging from 260 to 300 nm, and the thicknesses of the polymeric layers are in the range of 30-50 nm. As the swelling time increases from 24 to 120 h, the medium sizes of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles increase from 584.45 to 1142.61 nm. The flow of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles has obvious nonlinear characteristics and a prominent scale effect at a low-pressure gradient, and there should be an optimal matching relationship between its injection mass concentration and the channel size. The flow tests in the sand packs demonstrate that the SiO2/P(MBAAm-co-AM) polymeric nanoparticles can form effective plugging in the main flow channels at different permeability areas and can break through at the throat to fulfill the step-by-step profile control. Moreover, the profile control of the SiO2/P(MBAAm-co-AM) polymeric nanoparticles strengthens with an increase in their swelling time. The microscopic flooding experiment in the etched glass micromodel confirms that the SiO2/P(MBAAm-co-AM) polymeric nanoparticles can block dynamically and alternatively the channels of different sizes with the form of loose or dense networks to adjust the fluid flow diversion, improve the sweep efficiency, and recover more residual oil. The SiO2/P(MBAAm-co-AM) polymeric nanoparticles can achieve an enhanced oil recovery of 20.71% in the micromodel.

High-pressure carbon dioxide-hydrothermal enhance yield and methylene blue adsorption performance of banana pseudo-stem activated carbon.

In order to reduce environmental risks and fungus disease spread of banana waste, the high-pressure CO2-hydrothermal treatment was developed to produce hydrochar as a precursor of activated carbon from banana pseudo-stem(BP). SEM, BET, XRD, Raman and FTIR was used to investigate the influence mechanism of the high-pressure CO2-hydrothermal pretreatment on the yield and methylene blue(MB) adsorption capacities of the activated carbon. The results show that although the adsorption capacities of BP after high-pressure CO2-hydrothermal pretreatment(BPx) is decrease due to decrease of oxygen-containing functional group and flatter spatial structure, that of BPx after KOH activation(BPx-A) significantly increase and is higher than that of BP by direct KOH activation(BP-A). Because BP-A presents honeycomb porous microstructures and has a higher mesoporous structure(138-472 m2/g), plentiful active sites and rich the abundant influential adsorption group of MB adsorption. In addition, compared to BP-A(0.68%), the total yield of BPx-A(2.42-9.11%) is 356-1340%.

An application-specific image processing array based on WSe2 transistors with electrically switchable logic functions.

With the rapid development of artificial intelligence, parallel image processing is becoming an increasingly important ability of computing hardware. To meet the requirements of various image processing tasks, the basic pixel processing unit contains multiple functional logic gates and a multiplexer, which leads to notable circuit redundancy. The pixel processing unit retains a large optimizing space to solve the area redundancy issues in parallel computing. Here, we demonstrate a pixel processing unit based on a single WSe2 transistor that has multiple logic functions (AND and XNOR) that are electrically switchable. We further integrate these pixel processing units into a low transistor-consumption image processing array, where both image intersection and image comparison tasks can be performed. Owing to the same image processing power, the consumption of transistors in our image processing unit is less than 16% of traditional circuits.

Ultrathin Multibridge Channel Transistor Enabled by van der Waals Assembly.

Multibridge channel field-effect transistors (MBCFETs) enable improved gate control and flow of a large drive current and they are regarded as promising candidates for next-generation transistor architecture. However, in achieving a larger drive current with a thinner channel, limitations arise from the decrease in mobility when the thickness of the Si nanosheet is less than 5 nm. In addition, an increase in the leakage current is unavoidable when a large number of channels are stacked. Here, a 2D ultrathin MBCFET is demonstrate, constructed based on 2 nm/2 nm MoS2 channels. The normalized drive current (23.11 µA*µm µm-1 ) in each level channel of this MBCFET exceeds that of the latest seven-level-stacked Si MBCFET, while the leakage current is only 0.4% of this value, with the subthreshold swing reaching 60 mV dec-1 and an on/off ratio reaching up to 4 × 108 at room temperature. Furthermore, the drive current of this 2D ultrathin MBCFET can be further increased by regulating the polarity of the operation voltage to reduce the injection barrier. The combination of 2D materials and an MBC structure has the potential for use in high-performance and low-power-consumption electronics.

Assessment of the Multiphase Mechanical Properties of the Longmaxi Formation Shale Using Nanoindentation Tests.

Mechanical properties are some of the most important parameters for understanding well drilling and hydraulic fracturing designs in unconventional reservoir development. As an effective tool, nanoindentation has been used to determine the mechanical properties of rocks at the nanoscale. In this study, the Longmaxi Formation shale samples from the Yibin area of China were collected and analyzed to obtain the multiphase mechanical properties. The mineral compositions and organic geochemistry of the shale samples were studied using X-ray diffraction, energy-dispersive X-ray spectrometry, and a carbon/sulfur analyzer. The pore structures of the shale samples at the micro- and nanoscales were characterized by field-emission scanning electron microscopy. The mechanical parameters of the shale samples, such as the hardness and elastic modulus, were investigated using the nanoindentation method to identify three mineral phases: brittle minerals, soft matters, and complex minerals at the interfaces between brittle minerals and soft matters. The uncertainty characteristics of the mechanical parameters of the three mineral phases were evaluated using the Weibull model, and the factors interfering with the mechanical parameters were analyzed for the different shale samples. The results showed that the brittle minerals had the largest recovered elastic deformations and the smallest residual deformations, while the soft matters had the largest residual deformations and the smallest recovered elastic deformations. The analysis results of the coefficients of variation and the Weibull modulus both confirmed that the scatter of the hardness was higher than that of the elastic modulus because of the uncertain contact area, and the hardness and elastic modulus of the soft matters had the highest uncertainty among the three mineral phases. The elastic modulus increased nonlinearly with increasing hardness according to a power function for the whole shale sample. The elastic modulus and hardness both had a favorable linear relationship with the total organic carbon (TOC) content, illustrating that the TOC content was one of the significant factors that affected the mechanical parameters of the shale samples.

A Steep-Slope MoS2/Graphene Dirac-Source Field-Effect Transistor with a Large Drive Current.

In the continuous transistor feature size scaling down, the scaling of the supply voltage is stagnant because of the subthreshold swing (SS) limit. A transistor with a new mechanism is needed to break through the thermionic limit of SS and hold the large drive current at the same time. Here, by adopting the recently proposed Dirac-source field-effect transistor (DSFET) technology, we experimentally demonstrate a MoS2/graphene (1.8 nm/0.3 nm) DSFET for the first time, and a steep SS of 37.9 mV/dec at room temperature with nearly free hysteresis is observed. Besides, by bringing in the structure of gate-all-around (GAA), the MoS2/graphene DSFET exhibits a steeper SS of 33.5 mV/dec and a 40% increased normalized drive current up to 52.7 µA·µm/µm (VDS = 1 V) with a current on/off ratio of 108, which shows potential for low-power and high-performance electronics applications.

Enhanced Oil Recovery by a Suspension of Core-Shell Polymeric Nanoparticles in Heterogeneous Low-Permeability Oil Reservoirs.

Polymeric nanoparticle suspension is a newly developed oil-displacing agent for enhanced oil recovery (EOR) in low-permeability reservoirs. In this work, SiO2/P(MBAAm-co-AM) polymeric nanoparticles were successfully synthesized by a simple distillation-precipitation polymerization method. Due to the introduction of polymer, the SiO2/P(MBAAm-co-AM) nanoparticles show a favorable swelling performance in aqueous solution, and their particle sizes increase from 631 to 1258 nm as the swelling times increase from 24 to 120 h. The apparent viscosity of SiO2/P(MBAAm-co-AM) suspension increases with an increase of mass concentration and swelling time, whereas it decreases as the salinity and temperature increase. The SiO2/P(MBAAm-co-AM) suspension behaves like a non-Newtonian fluid at lower shear rates, yet like a Newtonian fluid at shear rates greater than 300 s-1. The EOR tests of the SiO2/P(MBAAm-co-AM) suspension in heterogeneous, low-permeability cores show that SiO2/P(MBAAm-co-AM) nanoparticles can effectively improve the sweep efficiency and recover more residual oils. A high permeability ratio can result in a high incremental oil recovery in parallel cores. With an increase of the permeability ratio of parallel cores from 1.40 to 15.49, the ratios of incremental oil recoveries (low permeability/high permeability) change from 7.69/4.61 to 23.61/8.46. This work demonstrates that this SiO2/P(MBAAm-co-AM) suspension is an excellent conformance control agent for EOR in heterogeneous, low-permeability reservoirs. The findings of this study can help to further the understanding of the mechanisms of EOR using SiO2/P(MBAAm-co-AM) suspension in heterogeneous, low-permeability reservoirs.

Batch pH Oscillations in the Belousov-Zhabotinsky Reaction.

No single-phase system has been previously reported to give significant pH oscillations in a closed (batch) reactor. We report here sustained pH oscillations in batch for the Belousov-Zhabotinsky reaction using much lower [H+]0 and much higher [BrO3-]0 than in traditional studies of this reaction. In fact, pH oscillations were obtained in the presence of only BrO3-, malonic acid (MA), and Mn2+. The amplitude, frequency, and duration of oscillations tend to depend primarily on the ratio of [BrO3-]0 to [MA]0. A critical part of the proposed mechanism involves the reversible formation of a manganese(III) complex with bromomalonic acid, followed by two-electron oxidation to tartraric acid and Mn2+. Estimates of the corresponding rate constant values for these reactions have been obtained by simulation. It is suggested that the presence of a supercatalytic reaction in H+ may be a sufficient, if not necessary, requirement for the occurrence of pH oscillations in a batch system.