A New Memristor with 2D Ti3 C2 Tx MXene Flakes as an Artificial Bio-Synapse.

Two-dimensional (2D) materials have attracted extensive research interest in academia due to their excellent electrochemical properties and broad application prospects. Among them, 2D transition metal carbides (Ti3 C2 Tx ) show semiconductor characteristics and are studied widely. However, there are few academic reports on the use of 2D MXene materials as memristors. In this work, reported is a memristor based on MXene Ti3 C2 Tx flakes. After electroforming, Al/Ti3 C2 Tx /Pt devices exhibit repeatable resistive switching (RS) behavior. More interestingly, the resistance of this device can be continuously modulated under the pulse sequence with 10 ns pulse width, and the pulse width of 10 ns is much lower than that in other reported work. Moreover, on the nanosecond scale, the transition from short-term plasticity to long-term plasticity is achieved. These two properties indicate that this device is favorable for ultrafast biological synapse applications and high-efficiency training of neural networks. Through the exploration of the microstructure, Ti vacancies and partial oxidation are proposed as the origins of the physical mechanism of RS behavior. This work reveals that 2D MXene Ti3 C2 Tx flakes have excellent potential for use in memristor devices, which may open the door for more functions and applications.

A bidirectional thermal sensory leaky integrate-and-fire (LIF) neuron model based on bipolar NbOx volatile threshold devices with ultra-low operating current.

Brain-like artificial intelligence (AI) will become the main form and important platform in future computing. It will play an important and unique role in simulating brain functions, efficiently implementing AI algorithms, and improving computing power. Developing artificial neurons that can send facilitation/depression signals to artificial synapses, sense, and process temperature information is of great significance for achieving more efficient and compact brain-like computing systems. Herein, we have constructed a NbOx bipolar volatile threshold memristor, which could be operated by 1 µA ultra-low current and up to ∼104 switching ratios. By using a leaky integrate-and-fire (LIF) artificial neuron model, a bipolar LIF artificial neuron is constructed, which can realize the conventional threshold-driven firing, all-or-nothing spiking, refractory periods, and intensity-modulated frequency response bidirectionally at the positive/negative voltage stimulation, which will give the artificial synapse facilitation/depression signals. Furthermore, this bipolar LIF neuron can also explore different temperatures to output different signals, which could be constructed as a more compact thermal sensory neuron to avoid external harm to artificial robots. This study is of great significance for improving the computational efficiency of the system more effectively, achieving high integration density and low energy consumption artificial neural networks to meet the needs of brain-like neural computing.

Purification of rutin and nicotiflorin from the flowers of Edgeworthia chrysantha Lindl. by high-speed counter-current chromatography.

An ethanol extract of air-dried flowers of Edgeworthia chrysantha Lindl. was partitioned between water and petroleum, ethyl acetate, and n-butanol. The n-butanol extraction was initially purified by silica gel column chromatography to give a partially purified sample. The bioactive compound rutin, along with nicotiflorin, were successfully separated from the partially purified sample by high-speed counter-current chromatography. The two compounds were isolated from the plant of Edgeworthia genus for the first time. The two-phase solvent system used was composed of ethyl acetate-n-butanol-water at an optimized ratio of 4:1:5 (v/v/v). High-speed counter-current chromatography yielded, from 108 mg of the partially purified extract, 53 mg rutin and 32 mg nicotiflorin with 92.5% and 92.2% recovery, with each at over 96.5% purity by high-performance liquid chromatography analysis. Their structures were identified by 1H NMR and 13C NMR.

[A microfabricated ICP source base on planar spiral-shaped coil].

Along with the development of micro-electromechanical system technology, the reports on the optical splitting systems and the photoelectric detection systems of spectrometer based on micro-electromechanical system have become increasingly popular, whereas the reports on micro excitation source in the development of micro spectrometer are few. In other words, the development of micro excitation source is the most important part in the development of the micro spectrometer. A novel low-pressure microfabricated inductively coupled plasma source is introduced, which is an emission spectrum excitation source based on surface-micromaching technology. Its radio frequency power consumption is much lower than the general inductively coupled plasma source. The source can work at an argon gas pressure of 100 Pa, and thus consumes less argon. The principle of operation for a microfabricated inductively coupled plasma source is illustrated. The layout of the planar spiral-shaped coil, the matched capacitor and the resonant capacitor is given. The fabrication process and properties of the plasma source are described. Meanwhile a novel inductively coupled plasma based on the technology of printed circuit board is introduced. In the experiment, the planar spiral-shaped coil and interdigatial capacitor were used. When the pressure of argon was 100 Pa and the radio frequency power was 3. 5 W at 13. 56 MHz the novel inductively coupled plasma was ignited. The photo of the argon ignition is given. Finally the potential application of the micro inductively coupled plasma in spectrometers is presented.

Preparative isolation and purification of germacrone and curdione from the essential oil of the rhizomes of Curcuma wenyujin by high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) was applied to isolate and purify bioactive compounds in the essential oil of the rhizomes of Curcuma wenyujin. Two sesquiterpenes germacrone and curdione were successfully isolated and purified using two-phase solvent system composed of petroleum ether-ethanol-diethyl ether-water (5/4/0.5/1, v/v) in tail to head elution mode. 62 mg of germacrone and 93 mg of curdione were obtained from 658 mg of the essential oil each at over 95% purity. Their structures were identified by 1H NMR and EI MS.

Self-rectifying performance in the sandwiched structure of Ag/In-Ga-Zn-O/Pt bipolar resistive switching memory.

We reported that the resistive switching of Ag/In-Ga-Zn-O/Pt cells exhibited self-rectifying performance at low-resistance state (LRS). The self-rectifying behavior with reliability was dynamic at elevated temperature from 303 to 393 K. The Schottky barrier originated from the interface between Ag electrode and In-Ga-Zn-O films, identified by replacing Ag electrode with Cu and Ti metals. The reverse current at 1.2 V of LRS is strongly suppressed and more than three orders of magnitude lower than the forward current. The Schottky barrier height was calculated as approximately 0.32 eV, and the electron injection process and resistive switching mechanism were discussed.

Graphene's cousin: the present and future of graphane.

The so-called graphane is a fully hydrogenated form of graphene. Because it is fully hydrogenated, graphane is expected to have a wide bandgap and is theoretically an electrical insulator. The transition from graphene to graphane is that of an electrical conductor, to a semiconductor, and ultimately to an electrical insulator. This unique characteristic of graphane has recently gained both academic and industrial interest. Towards the end of developing novel applications of this important class of nanoscale material, computational modeling work has been carried out by a number of theoreticians to predict the structures and electronic properties of graphane. At the same time, experimental evidence has emerged to support the proposed structure of graphane. This review article covers the important aspects of graphane including its theoretically predicted structures, properties, fabrication methods, as well as its potential applications.

Prediction of shelled shrimp weight by machine vision.

The weight of shelled shrimp is an important parameter for grading process. The weight prediction of shelled shrimp by contour area is not accurate enough because of the ignorance of the shrimp thickness. In this paper, a multivariate prediction model containing area, perimeter, length, and width was established. A new calibration algorithm for extracting length of shelled shrimp was proposed, which contains binary image thinning, branch recognition and elimination, and length reconstruction, while its width was calculated during the process of length extracting. The model was further validated with another set of images from 30 shelled shrimps. For a comparison purpose, artificial neural network (ANN) was used for the shrimp weight predication. The ANN model resulted in a better prediction accuracy (with the average relative error at 2.67%), but took a tenfold increase in calculation time compared with the weight-area-perimeter (WAP) model (with the average relative error at 3.02%). We thus conclude that the WAP model is a better method for the prediction of the weight of shelled red shrimp.

Separation of pyridine derivatives from synthetic mixtures by pH-zone-refining counter-current chromatography.

Three novel pyridine derivatives were successfully separated from their partially purified synthetic mixtures by pH-zone-refining counter-current chromatography using a multilayer coil planet centrifuge designed in our laboratory. After equilibration of a two-phase solvent system consisting of methyl tert-butyl ether-tetrahydrofuran-water at an optimized volume ratio of 4:6:7, triethylamine (10 mM) was added to the organic phase as a retainer and hydrochloric acid (10 mM) to the aqueous phase as an eluter. Separation runs of 1.20, 1.16, and 1.15 g of three samples yielded three pyridine derivatives in weights of 306, 255, and 314 mg at a high purity of over 98.5, 99.0, and 98.2% (determined by HPLC), respectively. The structures were identified by electron impact mass spectrometry and (1)H NMR.

Preparative isolation and purification of harpagoside from Scrophularia ningpoensis hemsley by high-speed counter-current chromatography.

The bioactive component harpagoside was successfully separated from the crude extract of Scrophularia ningpoensis Hemsley by one-step purification using high-speed counter-current chromatography (HSCCC). A two-phase solvent system containing n-butanol:ethyl acetate:water (1:9:10) was selected following consideration of the partition coefficient of the target compound. A 276 mg quantity of the crude extract was loaded onto a 250 mL HSCCC column and yielded 11 mg harpagoside at over 97% purity. The chemical structure of harpagoside was determined by HPLC-ESI/MS and 1H-NMR.