Tunable and nonvolatile multibit data storage memory based on MoTe/boron nitride/graphene heterostructures through contact engineering.

Heterostructures formed by stacking atomically thin two-dimensional materials are promising candidates for flash memory devices to achieve premium performances, due to the capability of effective carrier modulation and unique charge trapping behavior at the interfaces with atomic flatness. Here, we report a nonvolatile floating-gate flash memory based on MoTe/h-BN/graphene van der Waals heterostructure, which possesses increased data storage capacity per cell and versatile tunability. The decent memory behavior of the device is enabled by the carriers stored in the floating gate of graphene layer, which tunnel through the dielectric layer of h-BN from the channel layer of MoTe under static-electrical field.

Semimetals for high-performance photodetection.

Semimetals are being explored for their unique advantages in low-energy high-speed photodetection, although they suffer from serious drawbacks such as an intrinsically high dark current. In this Perspective, we envision the exploitation of topological effects in the photoresponse of these materials as a promising route to circumvent these problems. We overview recent studies on photodetection based on graphene and other semimetals, and further discuss the opportunities created by topological effects, along with the additional challenges that they impose on photodetector designs.

Error evaluation of Judd-Ofelt spectroscopic analysis.

Judd-Ofelt (J-O) spectroscopic knowledge of a rare-earth-doped luminescent material is crucial to its application. Although a large number of papers with regard to the J-O study of various rare-earth-doped luminescent materials have been reported each year, few papers presented the errors of the J-O intensity parameters Ω (i = 2, 4, 6) and radiative probabilities evaluated from them. Present study focuses on the error evaluation of the J-O parameters and radiative probabilities.

Effects of extracellular matrix rigidity on sonoporation facilitated by targeted microbubbles: Bubble attachment, bubble dynamics, and cell membrane permeabilization.

In this study, we investigated the effects of extracellular matrix rigidity, an important physical property of microenvironments regulating cell morphology and functions, on sonoporation facilitated by targeted microbubbles, highlighting the role of microbubbles. We conducted mechanistic studies at the cellular level on physiologically relevant soft and rigid substrates. By developing a unique imaging strategy, we first resolved details of the 3D attachment configurations between targeted microbubbles and cell membrane.

Peak focusing based on stationary phase thickness gradient.

This paper reports the development of a stationary phase thickness gradient gas chromatography (GC) column that enables analyte peak focusing and improves separation resolution. Theoretical analysis and simulation demonstrate focusing via a positive thickness gradient, i.e.

Microfabricated porous layer open tubular (PLOT) column.

Development of micro gas chromatography (μGC) is aimed at rapid and in situ analysis of volatile organic compounds (VOCs) for environmental protection, industrial monitoring, and toxicology. However, due to the lack of appropriate microcolumns and associated stationary phases, current μGC is unable to separate highly volatile chemicals such as methane, methanol, and formaldehyde, which are of great interest for their high toxicity and carcinogenicity. This inability has significantly limited μGC field applicability.

Self-driven visible-near infrared photodetector with vertical CsPbBr/PbS quantum dots heterojunction structure.

Self-driven photodetectors are widely used in communication and imaging. As a newly developed semiconductor material, perovskite quantum dots (QDs) are not only bandgap tunable, but also easily combined with other materials. In this paper, a vertical structure self-driven photodetector based on heterojunction of CsPbBr QDs and PbS QDs is proposed, and the device is prepared by solution spin coating method.

Measurement of refractive index of powder by prism coupler.

Refractive index of optical material of powder is measured not as easily as a bulk material. Here, the prism coupling technique in combination with the immersion method is proposed to measure the refractive index of an optical material of powder. First, the powder material to be measured was dispersed in α-bromonaphthalene (CHBr) liquid to form a suspension mixture.

Light enhanced low-voltage nonvolatile memory based on all-inorganic perovskite quantum dots.

Light enhanced low-voltage nonvolatile memory was prepared using all-inorganic perovskite quantum dots (QDs) as a semiconductor layer and Ag nanoparticles (NPs) as a floating gate layer. The photo-induced carriers can be produced in CsPbBr QDs under ultraviolet light and trapped in Ag NPs under the action of an external electric field. With the assistance of light, the device exhibited a significantly larger memory window (ΔV ) under low programming and erasing voltages of ±5 V owing to the use of CsPbBr QDs.

Improving the nondestructive analysis accuracy of liquids in a flexible container based on the multi-pathlength spectrum method.

In order to achieve nondestructive analysis of liquid samples, the spectral analysis of solution in a flexible container is proposed in this paper. However, the difference in the flexible containers reduces the accuracy of the spectral analysis. By analyzing the relationship between the condition number of coefficient matrix (CNCM) and the solution accuracy, a method of reducing CNCM by multi-pathlength spectrum is proposed to reduce the error caused by the differences in flexible containers.

Comment on "A universal approach for calculating the Judd-Ofelt parameters of RE in powdered phosphors and its application for the β-NaYF4:Er/Yb phosphor derived from auto-combustion-assisted fluoridation" by B. Chen, S. Xu et al., Phys. Chem. Chem. Phys., 2018, 20, 15876.

A recent paper [Y. Q. Zhang, B.

Dynamically controllable polarity modulation of MoTe field-effect transistors through ultraviolet light and electrostatic activation.

Energy band engineering is of fundamental importance in nanoelectronics. Compared to chemical approaches such as doping and surface functionalization, electrical and optical methods provide greater flexibility that enables continuous, reversible, and in situ band tuning on electronic devices of various kinds. In this report, we demonstrate highly effective band modulation of MoTe field-effect transistors through the combination of electrostatic gating and ultraviolet light illumination.

Gate-Tunable Photodetection/Voltaic Device Based on BP/MoTe Heterostructure.

van der Waals heterostructures based on two-dimensional (2D) materials have attracted tremendous attention for their potential applications in optoelectronic devices, such as solar cells and photodetectors. In addition, the widely tunable Fermi levels of these atomically thin 2D materials enable tuning the device performances/functions dynamically. Herein, we demonstrated a MoTe/BP heterostructure, which can be dynamically tuned to be either p-n or p-p junction by gate modulation due to compatible band structures and electrically tunable Fermi levels of MoTe and BP.

Wet Chemical Method for Black Phosphorus Thinning and Passivation.

Layered black phosphorus (BP) has been expected to be a promising material for future electronic and optoelectronic applications since its discovery. However, the difficulty in mass fabricating layered air-stable BP severely obstructs its potential industry applications. Here, we report a new BP chemical modification method to implement all-solution-based mass production of layered air-stable BP.

A Fast Response-Recovery 3D Graphene Foam Humidity Sensor for User Interaction.

Humidity sensors allow electronic devices to convert the water content in the environment into electronical signals by utilizing material properties and transduction techniques. Three-dimensional graphene foam (3DGF) can be exploited in humidity sensors due to its convenient features including low-mass density, large specific surface area, and excellent electrical. In this paper, 3DGF with super permeability to water enables humidity sensors to exhibit a broad relative humidities (RH) range, from 0% to 85.

A Broadband Phototransistor Based on Three-Dimensional Reduced Graphene Oxide Foam.

Three-dimensional (3D) cross-linked polymer-like reduced graphene oxide foams (rGOFs) with a seamlessly continuous graphene network, exhibit high photoresponsive and conductivity and have received much attention regarding solar cells and supercapacitors. However, little attention has been paid to photodetection applications of 3D rGOFs. Here we report a novel broadband phototransistor based on metal-3D GFs-metal, which exhibits a high light absorption and a wide spectra response ranging at least from 400 to 1600 nm wavelength with a maximum photoresponsivity of 10 mA/W at 400 nm.

Solution-Based Property Tuning of Black Phosphorus.

The air instability of black phosphorus (BP) severely hinders the development of its electronic and optoelectronic applications. Although a lot of effort has been made to passivate it against degradation in ambient conditions, approaches to further manipulate the properties of passivated BP are still very limited. Herein, we report a simple and low-cost chemical method that can achieve BP passivation and property tailoring simultaneously.

Highly-sensitive gas sensor based on two-dimensional material field effect transistor.

Atomically thin two-dimensional (2D) materials are ideal gas sensing materials for achieving an ultra-low detection limit, due to the high surface-to-volume ratio, low electronic noise and sensitively tunable Fermi level. However, the sensitivity of 2D materials to their surrounding environment may also severely degrade the long-term stability of sensing devices, since most of them use the same 2D material flake as both the sensing and conduction material. In this work, we report a gas sensor based on a 2D material field effect transistor (FET) which uses few-layer black phosphorus (BP), boron nitride (BN) and molybdenum disulfide (MoS) as the top-gate, dielectric layer and conduction channel, respectively.

Ultraviolet Light-Induced Persistent and Degenerated Doping in MoS for Potential Photocontrollable Electronics Applications.

Efficient modulation of carrier concentration is fundamentally important for tailoring the electronic and photoelectronic properties of semiconducting materials. Photoinduced doping is potentially a promising way to realize such a goal for atomically thin nanomaterials in a rapid and defect-free manner. However, the wide applications of photoinduced doping in nanomaterials are severely constrained by the low doping concentration and poor stability that can be reached.

Implementing Lateral MoSe P-N Homojunction by Efficient Carrier-Type Modulation.

High-performance p-n junctions based on atomically thin two-dimensional (2D) materials are the fundamental building blocks for many nanoscale functional devices that are ideal for future electronic and optoelectronic applications. The lateral p-n homojunctions with conveniently tunable band offset outperform vertically stacked ones, however, the realization of lateral p-n homojunctions usually require efficient carrier-type modulation in a single 2D material flake, which remains a tech challenge. In this work, we have realized effective carrier-type modulation in a single MoSe flake, and thus, a lateral MoSe p-n homojunction is achieved by sequential treatment of air rapid thermal annealing and triphenylphosphine (PPh) solution coating.

Enhancing electronic and optoelectronic performances of tungsten diselenide by plasma treatment.

Transition metal dichalcogenides (TMDCs) have recently become spotlighted as nanomaterials for future electronic and optoelectronic devices. In this work, we develop an effective approach to enhance the electronic and optoelectronic performances of WSe2-based devices by N2O plasma treatment. The hole mobility and sheet density increase by 2 and 5 orders of magnitude, reaching 110 cm2 V-1 s-1 and 2.

Flexible gas sensor based on graphene/ethyl cellulose nanocomposite with ultra-low strain response for volatile organic compounds rapid detection.

Minimizing the strain-induced undesirable effects is one of the major efforts to be made for flexible electronics. This work demonstrates a highly sensitive flexible gas sensor with ultra-low strain response, which is potentially suitable for wearable electronics applications. The gas sensing material is a free-standing and flexible thin film made of graphene/ethyl cellulose (EC) nanocomposite, which is then integrated with flexible substrate of polyethylene terephthalate.

VEGF attenuates 2-VO induced cognitive impairment and neuronal injury associated with the activation of PI3K/Akt and Notch1 pathway.

Vascular endothelial growth factor (VEGF) has been identified as a potential treatment for effectively improving cognitive function in several neuropathological conditions. However, the underlying mechanism and the relevant downstream protective pathways that are activated in neurons by VEGF remain elusive, especially in chronic global cerebral ischemia. In this study, we intended to investigate the signaling mechanisms of VEGF in cognitive protection and anti-apoptosis in a rat model of chronic global cerebral ischemia induced by permanent bilateral common carotid artery occlusion (2-VO).

A simple, compact, low-cost, highly efficient thermometer based on green fluorescence of Er/Yb-codoped NaYF microcrystals.

We developed a highly efficient optical thermometer based on intensity ratio of upconversion green fluorescence of Er/Yb-codoped NaYF microcrystals. The sensor consists simply of a 980nm laser diode, one narrow-band interference filter, two lenses, one Si-photocell and one multimeter, while being without use of spectrometer and additional electronics. The device not only has a simple, compact structure (hence a low cost), but also displays highly efficient sensing performance, characterized by large signal-to-noise ratio due to strong fluorescence intensity, high thermal resolution and sensitivity, which have the values 1.