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Aqueous energy storage technologies, including aqueous supercapacitors and aqueous batteries, have attracted extensive research interest owing to their great potential for diverse applications. Water-based electrolytes enable aqueous energy storage devices with advantageous features, such as fast charging capability, high power density, eco-friendliness, low cost, and large-scale manufacturing. The development of advanced electrode materials is highly pursued to improve the performance of aqueous energy storage devices. In this regard, van der Waals (vdW) layered transition metal-containing compounds (LTMCs) have been brought into the spotlight due to their high theoretical specific capacity and versatile possibilities for structure engineering. This review highlights the recently developed structure engineering strategies for LTMCs in the applications of aqueous energy storage. Particular efforts are made to emphasize the correlation between the engineered vdW structure of LTMCs and their energy storage behaviours. Lastly, we provide an outlook about the future challenges in this field, which will hopefully inspire more exploration on LTMC-based aqueous energy storage devices.

Carbon materials hold great promise as oxygen catalysts in rechargeable Zn-air batteries (ZABs) but suffer from the sluggish catalytic kinetics due to unfavorable intermediate specie adsorption/desorption properties. Herein, we demonstrate an effective oxygen-induced surface electron density modulation strategy to significantly boost the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of carbon nanotubes. Experimental and theoretical studies conjointly reveal that the incorporation of electron-drawing oxygen atoms in the conjugated carbon nanotube plane imparts a relatively high positive charge density on adjacent carbon atoms, making them energetically favorable for OOH∗ adsorption in OER and OH∗ desorption in ORR. Such oxygen-modulated carbon nanotubes display excellent bifunctional catalytic activity toward both ORR and OER. The as-fabricated aqueous and flexible all-solid-state ZABs display superb peak power densities of 130.5 ​mW ​cm−2 and 103.5 ​mW ​cm−2 with good durability, outstripping most of recently reported ZABs. This surface electron density modulation method may open up valuable insights for designing other robust carbon electrocatalysts for ZABs and beyond.

The evaporation behaviours of various components were investigated by using a low pressure distillation method in a 2LiF-BeF

Robotic grasping in multi-object stacking scenes is important for autonomous robot manipulation. In this paper, we propose a 6-DoF (Degree of Freedom) grasping method for stacked rectangular objects from the single-view point clouds. We use the PointNet++ network and DBSCAN clustering algorithm to extract the target object from the whole scene. The 6-DoF pose of the gripper is obtained by our grasp pose estimation algorithm. To train the PointNet++ network, we build a small rectangular object segmentation dataset containing 800 real-world stacking scenes. The whole grasping system is lightweight, which takes about 518ms for a whole grasp planning process. Sufficient experiments show that our method gets 92% success rate and 95.5% completion rate, which satisfies the requirements of industrial applications.

Graphene field-effect transistors (G-FETs) on flexible substrates have demonstrated much higher strain limits than that on rigid substrates. In this letter, G-FETs with an extrinsic ${f}_{\textrm {max}}$ of 28 GHz on flexible polyethylene terephthalate (PET) substrates are presented. Polyimide film benzocyclobutene with 50-nm thickness is coated on a PET substrate surface for optimizing the carrier transport. The results show that the hole mobility can reach up to 1738 cm2/V.s. An Au-supported graphene transfer technology is used to facilitate the quality of graphene in G-FETs and reduce the output parasitic resistance to $50~\Omega $ . The measured figure of metric of “ ${f}_{\textrm {max}}\cdot {L}_{\textrm {g}}$ ” is $8.4~\textrm {GHz}\cdot \mu \text{m}$ , which is 105% higher than the highest reported results on polymeric substrates. The RF performance of flexible G-FETs under the bending condition is also studied. The results of the letter will be useful for developing the millimeter-wave flexible graphene integrated circuits.

Highly efficient and stable electrocatalyst for hydrogen evolution reaction (HER) is essential for the application of green hydrogen energy. To date, platinum-based materials are the most efficient electrocatalyst. Developing inexpensive electrocatalyst with low Pt loading and high platinum utilization efficiency is one of effective strategies to lower the cost of platinum-based electrocatalyst. In this paper, it was demonstrated that ultrafine and uniform distribution platinum nanoparticles could be synthesized on three-dimensional sulfur-doped graphene materials (Pt/3DSG) via covalent cross-linking between platinum and doped sulfur atoms. The high conductive 3DSG not only facilitates the electron transport but also serves as a template for depositing ultrafine and uniform platinum nanoparticles. The Pt/3DSG with low Pt loading (3.1 wt%) delivers extremely outstanding HER performance, which is superior to the commercial 20 wt% Pt/C catalyst. The turnover frequencies (TOFs) of Pt/3DSG can reach 1.12 s(-1), which is larger than that of 20% Pt/C (0.71 s(-1)). Furthermore, the stability is also superior than that of Pt/C. This work provides a rational design strategy for highly efficient and stable electrocatalysts with low loading and high utilization of precious metal. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

It is still challenging to develop non-precious free-standing bifunctional electrocatalysts with high efficiency for hydrogen and oxygen evolution reactions. Herein, for the first time, we present a novel hybrid electrocatalyst synthesized via a facile hydrothermal reaction, which is constructed from ultrafine NiSe2 nanoparticles/nanosheets homogeneously anchored on 3D graphene/nickel foam (NiSe2/3DSNG/NF). This hybrid delivers superior catalytic performances for hydrogen/oxygen evolution reactions and overall water splitting: it shows an ultra-small Tafel slope of 28.56 mV dec-1 for hydrogen evolution in acid, and a small Tafel slope of 42.77 mV dec-1 for the oxygen evolution reaction; particularly, in a two-electrode setup for water splitting, it requires an ultra-small potential of 1.59 V to obtain 10 mA cm-2 with nearly 100% faradaic efficiencies for H2 and O2. This study presents a new approach of catalyst design and fabrication to achieve highly efficient and low-cost water electrolysis.

It is still challenging to develop non-precious free-standing bifunctional electrocatalysts with high efficiency for hydrogen and oxygen evolution reactions. Herein, for the first time, we present a novel hybrid electrocatalyst synthesized via a facile hydrothermal reaction, which is constructed from ultrafine NiSe2 nanoparticles/nanosheets homogeneously anchored on 3D graphene/nickel foam (NiSe2/3DSNG/NF). This hybrid delivers superior catalytic performances for hydrogen/oxygen evolution reactions and overall water splitting: it shows an ultra-small Tafel slope of 28.56 mV dec-1 for hydrogen evolution in acid, and a small Tafel slope of 42.77 mV dec-1 for the oxygen evolution reaction; particularly, in a two-electrode setup for water splitting, it requires an ultra-small potential of 1.59 V to obtain 10 mA cm-2 with nearly 100% faradaic efficiencies for H2 and O2. This study presents a new approach of catalyst design and fabrication to achieve highly efficient and low-cost water electrolysis.

Three-dimensional graphene foam (3DGF) with high conductivity and rich porosity is an ideal carbon-based metal-free electrocatalyst for hydrogen evolution reaction (HER); however, its HER performance is still very poor due to insufficient electrocatalytic active sites. Herein, in order to create many more electrocatalytic active sites, a facile approach combining Ar plasma pretreatment and subsequent N, S co-doping is presented. As a free-standing and binder-free electrocatalyst, the Ar-plasma-pretreated and N, S co-doped 3DGF (3DGF-Ar-NS) demonstrates significantly enhanced HER performance: the Tafel slope of 3DGF-Ar-NS dramatically decreases from 182 mV/dec (3DGF) to 75 mV/dec. The excellent HER performance and long-term stability of 3DGF-Ar-NS can be attributed to the synergistic effect of the 3DGF skeleton, Ar plasma pretreatment and heteroatom doping: the conductive, porous and flexible 3D graphene skeleton provides the interconnected conductive paths and facilitates the charge transportation; the Ar plasma pretreatment and N, S co-doping effectively create many more electrocatalytic active sites, resulting in significant enhancement in HER performance. This work provides a facile strategy to tailor and enhance the electrocatalytic performances of carbon-based materials for hydrogen evolution applications.

For the first time, the interwoven CoSe2/CNTs hybrid with ultra-small CoSe2 nanoparticles on highly conductive CNTs has been synthesized by a facile one-pot hydrothermal method. The CoSe2/CNTs hybrid has been investigated as electrocatalysts for the Hydrogen evolution reaction (HER) in acidic media. The physicochemical characterizations of CoSe2/CNTs have been performed by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The HER performances have been evaluated by linear sweep voltammetry (LSV), cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The CNT content in the CoSe2/CNTs hybrids has been optimized and CoSe2/CNTs (14.7 wt%) exhibits the best HER performance. It delivers a very small Tafel slope of −32 mV/dec, a low onset potential of −150 mV vs RHE and overpotential of −186 mV at −10 mA/cm2, which are much better than those of bare CoSe2 with a Tafel slope of −52 mV/dec, an onset potential of −234 mV vs RHE and overpotential of −293 mV vs RHE at −10 mA/cm2. Furthermore, the CoSe2/CNTs hybrid also demonstrates good long-term stability even after 1000 cycles. The excellent HER performance of CoSe2/CNTs can be attributed to its unique and conductive interwoven structure. This work provides insights into rational design and facile synthesis of non-precious electrocatalysts with high efficiency and good stability for HER.

We present a fiber-optic microphone (FOM) based on graphene oxide (GO) membrane in this study. A Fabry–Perot cavity consisting of a single-mode fiber and a piece of GO membrane works as the acoustic sensing structure. Using the GO as the core acoustic sensing component, the fabricating process of the FOM is demonstrated to be simple and efficient. Acoustic tests show that this FOM achieves an average minimum detectable pressure of 10.2 μPa/Hz 1/2, while maintaining a linear acoustic pressure response and a flat frequency response in the range of 100 Hz to 20 kHz. These results indicate the excellent suitability of this FOM for acoustic detection in the audible range with high sensitivity and high fidelity.

Rhenium disulfide (ReS 2 ) two-dimensional (2D) semiconductor, has attracted more and more attention due to its unique anisotropic electronic, optical, mechanical properties. However, the facile synthesis and electrochemical performance of ReS 2 and corresponding composite are still necessary to be explored. In this study, for the first time, few-layered ReS 2 nanosheets directly nucleated and grown on the tube walls of carbon nanotubes (CNTs) have been synthesized through a facile and one-pot hydrothermal method. Compared with bare ReS 2 , the ReS 2 /CNTs composite anode delivers remarkably enhanced electrochemical performance. It exhibits a very high capacity with 1048 mAh g −1 at 0.2 C and high capacity retention of 93.6% after 100 cycles at 0.5 C, which are much larger than that of bare ReS 2 . The significant enhancement in electrochemical performance is mainly attributed to its unique architecture: the CNTs not only guarantee to construct a high conductive and porous internetwork, but also ensure a compact contact with ReS 2 , which allow for easy electrolyte infiltration, efficient electron transfer and ionic diffusion. The presented synthesis approach can be extended to synthesize other 2D-semiconductor-based composite for energy storage and catalytic devices.

Considerable research has been conducted on evaluating the effectiveness of land consolidation (LC). However, most of the previous studies dealt with such evaluation in the areas where LC has taken place, whereas few focused on the potential evaluation before LC is implemented. Furthermore, land fragmentation has critical effects on the effectiveness evaluation of LC, but is not appropriately measured by currently used landscape metrics in the potential evaluation since project zones of LC cannot be delimited before LC implementation. To fill these gaps, this study demonstrates a potential evaluation model for LC, in which land fragmentation is taken into account by buffering land parcels and then quantifying their contiguity with a proper method. This model was tested in a case study area – Yangshan County of Guangdong, China, and the results showed that the new model is more robust than the traditional approach that evaluates the potential of land parcels in LC in terms of their locations, quality, terrains, and distances to infrastructural facilities. Moreover, the model revealed that land fragmentation plays an important role in LC potential evaluation. These findings imply that the proposed method can provide more appropriate guidelines for land decision-makers.

Tungsten disulfide (WS 2 ) has attracted much attention as the promising electrocatalyst for hydrogen evolution reaction (HER). Herein, the three-dimensional (3D) structure electrode composed of WS 2 and graphene/Ni foam has been demonstrated as the binder-free electrode for highly effective and stable HER. The overpotential of 3D WS 2 /graphene/Ni is 87 mV at 10 mA cm −2 , and the current density is 119.1 mA cm −2 at 250 mV overpotential, indicating very high HER activity. Moreover, the current density of 3D WS 2 /graphene/Ni at 250 mV only decreases from 119.1 to 110.1 mA cm −2 even after 3000 cycles, indicating a good stability. The high HER performance of 3D WS 2 /graphene/Ni binder-free electrode is superior than mostly previously reported WS 2 -based catalysts, which is attributed to the unique graphene-based porous and conductive 3D structure, the high loading of WS 2 catalysts and the robust contact between WS 2 and 3D graphene/Ni backbones. This work is expected to be beneficial to the fundamental understanding of both the electrocatalytic mechanisms and, more significantly, the potential applications in hydrogen economy for WS 2 .

For the first time, a facile one-pot synthesis of chrysanthemum-like ReSe 2 microspheres (CRM), which are self-assembled by wrinkled few-layer ReSe 2 nanosheets with highly crystalline quality, is presented. Compared to ReS 2 , the ReSe 2 microspheres exhibit superior electrocatalytic activity for hydrogen evolution reaction (HER): the CRM catalyst delivers a small onset overpotential of 80 mV and the lowest Tafel slope of 67.5 mV/decade for all reported Re-based dichalcogenides; it also exhibits excellent stability. The unique chrysanthemum-like structure with rich wrinkled edges and abundant nanopores guarantees sufficient electrocatalytic active edge sites, resulting in excellent HER performance of ReSe 2 . Chrysanthemum-like ReSe 2 microsphere is a promising candidate for high-performance HER.

Heteroatom doping can effectively tune the structure and properties of graphene. Theoretical calculations indicate that sulfur doping can effectively modify the band structure and further modulate the carrier transport properties of graphene. However, it is still a big challenge to synthesize large-area sulfur-doped graphene (SG) films with a high sulfur doping concentration and reasonable electrical properties since sulfur has a much larger atomic radius than carbon. In this study, the solid organic source thianthrene (C12H8S2) is employed as both a carbon source and sulfur dopant to grow large-area, few-layered SG films via chemical vapor deposition (CVD). The results show that the doping concentration, doping configuration and electrical properties can be effectively tuned via the hydrogen flux. The sulfur doping concentration is as high as 4.01 at% and the maximal mobility of SG can reach up to 270 cm(2) V-1 s(-1), which are the highest ever reported for sulfur-doped graphene.

As a new two-dimensional semiconductor, rhenium disulfide (ReS2), has lots of distinctive features and exhibits great potential for future novel device applications due to its unusual structure and unique anisotropic properties. In this study, for the first time, large-area few-layer ReS2 has been grown on the SiO2/Si substrate by physical vapour deposition (PVD) using ReS2 powder as source material. XPS and Raman data confirm the composition and bonding configurations of ReS2. Clear lattice fringes of the high-resolution TEM images reveal that the ReS2 is few-layer with highly crystalline quality. It suggests that PVD is promising to synthesize wafer-scale ReS2 film to realize its applications in electronics, optoelectronics, valleytronics and spintronics. The PVD method can be extended to grow other two-dimensional semiconductors with few-layer thickness and high quality.

As a new member of the transition metal dichalcogenides (TMDs) family, rhenium disulfide (ReS2) is attracting more and more attention because of its many distinctive characteristics, such as extremely weak interlayer coupling and anisotropic electronic, optical, and mechanical properties. The studies on synthesis method and electrochemical properties of ReS2 are still rare. For the first time, three-dimensional (3D) chrysanthemum-like microspheres composed of curly ReS2 nanosheets have been synthesized through a facile hydrothermal method. The high-resolution TEM image indicates that the ReS2 nanosheet is highly crystalline with a thickness of few monolayers. As anode for lithium-ion battery, the as-synthesized 3D chrysanthemum-like ReS2 (C-ReS2) microspheres deliver a large initial discharge capacity of 843.0 mAh g−1 and remain 421.1 mAh g−1 after 30 cycles. These values are much higher than that of commercial ReS2. The significant enhancement in electrochemical performance can be attributed to its porous and chrysanthemum-like microsphere structure constructed by few-layered curly ReS2 nanosheets. This unique architecture can allow for easy electrolyte infiltration, efficient electron transfer, and ionic diffusion. The facile synthesis approach can be extended to synthesize other two-dimensional TMDs semiconductors. The study renders ReS2 a promising future in lithium-ion batteries.

Three-dimensional S, N co-doped graphene/Ni foam (3DSNG/NF) hybrid electrocatalyst for oxygen evolution reaction (OER) is presented and prepared by a facile chemical vapor deposition (CVD). The doping concentrations of N and S of 3DSNG can be easily modulated by growth parameters, which strongly influence its catalytic activity. As a free-standing hybrid electrocatalyst without polymer binder, the optimized 3DSNG/NF doped with 2.56 at% N and 2.95 at% S, delivers good catalytic activity: it shows a very low Tafel slope of 45.61 mV dec−1 in alkaline solution, which is much lower than that of RuO2 (78.62 mV dec−1); it requires only a very low overpotential of 339 mV to obtain a large current density of 100 mA cm−2, which is far lower than that of RuO2 (418 mV); furthermore, it exhibits good long-term stability even after 50-h current-time test. The good OER performance and stability of 3DSNG/NF can be attributed to the synergistic effects originating from its unique hierarchical architecture. The porous and conductive graphene skeleton can not only guarantee the mechanical and structural stability, but also facilitate the electron transfer and ion diffusion; most important, the homogenously doped nitrogen and sulfur atoms create abundant catalytic active sites.

Triboelectric generators, which can directly transform energy from our living environment into electricity, are self-powered component for wearable devices. Flexible and transparent triboelectric generators (FTTGs) with high output power densities are urgently needed for wearable electronics. By introducing graphene (G) and indium tin oxide (ITO) as transparent electrodes and optimizing the electrode structure, a FTTG with polyimide (PI) and polyethylene terephthalate (PET) as friction layers and graphene (ITO) as top (bottom) electrode was obtained and it has a large output power density of 10.1 μW cm−2, which is over four times larger than previously reported FTTGs ca. 2 μW cm−2. Moreover, the output voltage of the graphene-based FTTG is as large as 56 V, and it exhibits excellent cycling behavior. The effects of electrode structure on the performance of FTTG have been analyzed and corresponding mechanism has been discussed. Light-emitting diodes (LED) can be easily powered by the FTTG, suggesting its potential application in harvesting electrical energy from human activities by using flexible and transparent devices.

Existing landscape ecology measures may not effectively capture the compactness of patterns that have multiple, disconnected parts. We develop a new way of measuring the compactness of such disconnected landscape patterns. Our method uses a map generalization approach to aggregating the multiple parts into a connected polygon while preserving the overall shape of the original pattern. We then measure the compactness by considering the weighted area-perimeter ratio of the aggregated shape and the closeness between the parts. Our measure, called weighted aggregation and closeness (WAC), is compared with 15 other landscape ecology metrics and the results suggest that WAC outperforms the other metrics by providing a more reasonable description of the compactness for patterns with multiple parts.

Graphene-based silica fiber-optic sensors, with high sensitivity, fast response, and low cost, have shown great promise for gas sensing applications. In this letter, by covering a monolayer of p-doped graphene on a D-shaped microstructured polymer fiber Bragg grating (FBG), we propose and demonstrate a novel biochemical probe sensor, the graphene-based D-shaped polymer FBG (GDPFBG). Due to the graphene-based surface evanescent field enhancement, this sensor shows high sensitivity to detect surrounding biochemical parameters. By monitoring the Bragg peak locations of the GDPFBG online, human erythrocyte (red blood cell) solutions with different cellular concentrations ranging from 0 to $10^{\mathrm {\mathbf {4}}}$ ppm were detected precisely, with the maximum resolution of sub-ppm. Such a sensor is structurally compact, is clinically acceptable, and provides good recoverability, offering a state-of-the-art polymer-fiber-based sensing platform for highly sensitive in situ and in vivo cell detection applications.

The state-of-art Si Matel-Oxide-Semiconductor Field-Effect-Transistor (MOS-FET) meets the problem of the Power Consumption (PC) can not be effecively deceased guided by the Moore’s Law as before. The GFET has the problem of the device can not be effectively turned off, since the band-gap of the graphene is zero. To solve these problems, noticing the amount of the carriers in the 2 dementional semiconductor material is limited, we propose a Matel-Semi-Insulator-Semiconductor Field-Effect-Transistor (MSIS-FET) to replace the traditional MOS-FET. We verify our idea by fabricating the graphene MSIS-FETs using the natural Aluminium-oxide (Al-oxide) as the semi-insulator gate dielectric. From MSIS-FETs fabricated, we obtain following experimental results. The graphene MSIS-FET is turned off very well, a recorded high Ids on/off ratio of 5 × 107 is achieved. A saddle and close-loop shape transfer feature of Ids-Vgs is obtained first time for transistors. A non-volatile memory characteristics is observed. A carrier re-injection principle and a super-Low PC mechanism for semiconductor devices and integrated circuits (ICs) are found from the transfer feature of the graphene MSIS-FET. It is shown that the PC of the semiconductor devices and (ICs) can be reduced by over three orders of magnitude by using this new mechanism.

Three-dimensional sulfur-doped graphene (3DSG) with high sulfur-doping content (2.9%) was synthesized on nickel foam by chemical vapor deposition using solid organic source of thianthrene as both the carbon source and sulfur dopant. The 3DSG further treated by Ar plasma (3DSG-Ar) was demonstrated as a free-standing and binder-free electrocatalyst without any polymeric binders for electrode fabrication. Particularly, 3DSG-Ar can be used as highly effective and stable electrocatalyst for hydrogen evolution reaction (HER). It delivers a very low Tafel slope of 64 mV dec(-1), which is superior or comparable to most metal-free carbon-based electrocatalysts ever reported; moreover, it shows superior long-term electrocatalytic stability even after 2000 cycles. The excellent HER performances of 3DSG-Ar can be attributed to its well-designed porous, conductive and flexible 3D sulfur-doped graphene structure. Sulfur doping combing with plasma treatment cause a synergistic effect to effectively provide many more electrocatalytic active sites, resulting in significantly improved HER performance. In addition, the conductive, porous and flexible 3D graphene skeleton can not only act as free-standing and binder-free electrocatalytic electrode, but also guarantee the interconnected conductive paths in the whole electrode, leading to facilitate the charge transportation between the electrocatalyst and electrolyte and thus enhance its HER performances.

Large-area MoS2 thin layers have been synthesized onto the SiO2/Si substrate by the thermolysis of (NH4)2MoS4 film. The structure and growth mechanism of MoS2 thin layers have been investigated. The results reveal that MoO3 can be easily formed during the growth process of MoS2 film, which will dramatically degrade the quality of MoS2 film. Further studies show that with increasing hydrogen fluxes, the content of MoO3 will decrease, and when the hydrogen flux reaches 100 sccm, pure MoS2 film can be obtained. It means that hydrogen plays a critical factor for synthesis of high-quality MoS2 thin layers without unexpected Mo oxidation. This work is beneficial for not only the fundamental understanding of growth mechanism, but also the potential applications of MoS2 film in electronics.

Chemical vapor deposition is a promising method to synthesize the large area monolayer graphene. However, unexpected bilayer regions are easily formed on the monolayer graphene, which will dramatically degrade the quality and uniformity of graphene. In this work, the large-area, high-quality and uniform monolayer graphene has been synthesized on the Cu foil. The studies reveal that the density of bilayer graphene regions decreases with increasing the growth time; when the growth time increases to 120 min, the formation of bilayer regions is effectively prevented. The corresponding growth mechanism was discussed. Further, the electrical studies reveal that by preventing the formation of bilayer regions, the mobility of graphene not only obviously increases, but also has a narrow distribution, indicating that the as-synthesized monolayer graphene has high quality and uniformity. We expect that this work is beneficial for not only potential applications, but also the fundamental understanding of the growth mechanism for graphene on Cu surface.

A highly sensitive fiber-optic Fabry-Perot interferometric geophone (FFPG) with graphene coated PMMA membrane is proposed and demonstrated, where the graphene coating is used for enhancement of the mechanical strength of the membrane. It is found that the sensitivity of the FFPG is much higher than that of the conventional electrical geophone. Such a novel all-optical geophone with low cost, high sensitivity, electromagnetic interference immunity, easy fabrication and robust structure would have great potential for use in oil/gas exploration and seismic wave detection.

Graphene sparks great interest to develop and extend its applications with its excellent mechanical, electrical, chemical, physical properties. Especially, its higher sensitivity and stronger selectivity presents exciting and bright prospects for biomedical detection applications. From 2008, piles of teams set foot to study graphene applications in biosensors and significant progress has been made. Here we will introduce the applications of graphene in the measurements of biological molecules and microorganism, which facilitates the diagnosis of related diseases, such as diabetes, coronary heart disease, arteriosclerosis and especially cancer.

When studying the comprehensive performance of the anti-skid valve, the test of the curve characteristic lacks theoretical basis in the brake anti-skid process and the mathematical equations are difficult to derive. Take a domestic locomotive anti-skid valve as the research object. Combine with the physical structure parameters of the anti-skid valve and the working principle of inflating and exhausting. A simulation model of the anti-skid valve was established by using MATLAB/Simulink, which included the motion equation of valve core and diaphragm plate, electromagnetic suction equation of electromagnet and air chamber charging and exhausting equation. The characteristics of the air pressure curve of the anti-skid valve under different control signals were analyzed. In order to verify the correctness of the simulation model, a set of locomotive anti-skid valve comprehensive performance test bench based on STM32 was built for experimental verification. The results show that the simulation results are consistent with the experimental results, meet the test requirements, and verify the accuracy of the model. This model provides a theoretical basis for structural optimization of anti-skid valves and analysis of locomotive braking anti-skid performance.

Broadly-tunable pulse generation in cavity-free graphene random lasers is reported, with tunable pulsewidths across two orders-of-magnitude to less-than 900 ps, tunable repetition over three orders-of-magnitude up to 3 MHz, and 41-dB singly-polarized extinction ratio.

Nitrogen-doped graphene (NG) films have been grown on Cu foils by using imidazole (C3H4N2) and PMMA as solid N and C sources. The results show that the pyridinic and pyrrolic nitrogen-bonding configurations and the N doping concentration can be effectively modulated by the hydrogen flux. In addition, it reveals that the defect density of the NG film is dominated by the pyridinic-N configuration instead of the pyrrolic-N configuration from the Raman spectra. Furthermore, from the electrical measurements, it is concluded that the pyrrolic-N configuration has stronger donor ability, and lower carrier scattering than those of pyridinic-N configuration. This study provides fundamental insights to understand the role of various N-bonding configurations, but also give guidance to synthesize the NG with controllable N-bonding configurations.

Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses., 8 pages paper with 4 figures, has been accepted on Nature Scientific Reports

Although there are already many efforts to investigate the electronic structures of twisted bilayer graphene, a definitive conclusion has not yet been reached. In particular, it is still a controversial issue whether a tunable electrical (or transport) bandgap exists in twisted bilayer graphene film until now. Herein, for the first time, it has been demonstrated that a tunable electrical bandgap can be opened in the twisted bilayer graphene by the combination effect of twist and vertical electrical fields. In addition, we have also developed a facile chemical vapor deposition method to synthesize large-area twisted bilayer graphene by introducing decaborane as the cocatalyst for decomposing methane molecules. The growth mechanism is demonstrated to be a defined-seeding and self-limiting process. This work is expected to be beneficial to the fundamental understanding of both the growth mechanism for bilayer graphene on Cu foil and more significantly, the electronic structures of twisted bilayer graphene.