Realization of a two-dimensional checkerboard lattice in monolayer Cu2_2N

Two-dimensional checkerboard lattice, the simplest line-graph lattice, has been intensively studied as a toy model, while material design and synthesis remain elusive. Here, we report theoretical prediction and experimental realization of the checkerboard lattice in monolayer Cu$_2$N. Experimentally, monolayer Cu$_2$N can be realized in the well-known N/Cu(100) and N/Cu(111) systems that were previously mistakenly believed to be insulators. Combined angle-resolved photoemission spectroscopy measurements, first-principles calculations, and tight-binding analysis show that both systems host checkerboard-derived hole pockets near the Fermi level. In addition, monolayer Cu$_2$N has outstanding stability in air and organic solvents, which is crucial for further device applications.Comment: Nano Letters, in pres

Sizing optimization for island microgrid with pumped storage system considering demand response

Abstract Currently, small islands are facing an energy supply shortage, which has led to considerable concern. Establishing an island microgrid is a relatively good solution to the problem. However, high investment costs restrict its application. In this paper, micro pumped storage (MPS) is used as an energy storage system (ESS) for islands with good geographical conditions, and deferrable appliance is treated as the virtual power source which can be used in the planning and operational processes. Household acceptance of demand response (DR) is indicated by the demand response participation degree (DRPD), and a sizing optimization model for considering the demand response of household appliances in an island microgrid is proposed. The particle swarm optimization (PSO) is used to obtain the optimal sizing of all major devices. In addition, the battery storage (BS) scheme is used as the control group. The results of case studies demonstrate that the proposed method is effective, and the DR of deferrable appliances and the application of MPS can significantly reduce island microgrid investment. Sensitivity analysis on the total load of the island and the water head of the MPS are conducted

Diagnosing Subsidence Geohazard at Beijing Capital International Airport, from High-Resolution SAR Interferometry

Beijing Capital International Airport (BCIA) has suffered from uneven land subsidence since 1935, which affects the smoothness of airport runways and seriously threatens the safety of aircrafts. In this paper, a spaceborne interferometric synthetic aperture radar (InSAR) with high-resolution Cosmo-SkyMed SAR data was utilized at BCIA for the first time to diagnose the subsidence hazard. The results show that subsidence is progressing at BCIA at a maximum rate of 50 mm/year, which is mainly distributed in the northwest side of the airport. It was found that the Shunyi-Liangxiang fault directly traverses Runway2 and Runway3 and causes uneven subsidence, controlling the spatial subsidence pattern to some degree. Four driving factors of subsidence were investigated, namely: the over-exploitation of groundwater, active faults, compressible soil thickness, and aquifer types. For the future sustainable development of BCIA, the influence of Beijing new airport and Beijing Daxing International Airport (BDIA), was analyzed and predicted. It is necessary to take relevant measures to control the uneven subsidence during the initial operation of BDIA and conduct long-term monitoring to ensure the regular safe operation of BCIA. This case demonstrates a remote sensing method of diagnosing the subsidence hazard with high accuracy and non-contact, providing a reliable alternative for the geohazard diagnosis of key infrastructures in the future

A recyclable biomass electrolyte towards green zinc-ion batteries

Abstract The operation of traditional aqueous-electrolyte zinc-ion batteries is adversely affected by the uncontrollable growth of zinc dendrites and the occurrence of side reactions. These problems can be avoided by the development of functional hydrogel electrolytes as replacements for aqueous electrolytes. However, the mechanism by which most hydrogel electrolytes inhibit the growth of zinc dendrites on a zinc anode has not been investigated in detail, and there is a lack of a large-scale recovery method for mainstream hydrogel electrolytes. In this paper, we describe the development of a recyclable and biodegradable hydrogel electrolyte based on natural biomaterials, namely chitosan and polyaspartic acid. The distinctive adsorptivity and inducibility of chitosan and polyaspartic acid in the hydrogel electrolyte triggers a double coupling network and an associated synergistic inhibition mechanism, thereby effectively inhibiting the side reactions on the zinc anode. In addition, this hydrogel electrolyte played a crucial role in an aqueous acid-based Zinc/MnO2 battery, by maintaining its interior two-electron redox reaction and inhibiting the formation of zinc dendrites. Furthermore, the sustainable biomass-based hydrogel electrolyte is biodegradable, and could be recovered from the Zinc/MnO2 battery for subsequent recycling

In Situ Removal of HBr via Microdroplets for High Selectivity Bromobutyl Rubber Synthesis in a Microreaction System

To obtain a high quality bromobutyl rubber product, a higher selectivity of brominated secondary allylic structure is necessary, but it is difficult to realize in traditional reaction devices. We developed a microreaction system and used microwater droplets as an extractant to in situ remove HBr, the catalyst of the isomerization side reaction, from the organic reacting solution to prevent converting brominated secondary allyl to brominated primary allyl and degradation of the polymer chain. The microreaction system contains two micromixers, including a membrane dispersion micromixer for dispersing microwater droplets in the butyl rubber solution and a cross-junction micromixer for blending butyl rubber and Br₂ solutions. A volume adjustable delayed loop after the micromixers is used to carry out the reaction. The results show that 1 wt % water in the organic phase is satisfied to remove HBr, and 97% selectivity of brominated secondary allyl is successfully obtained under optimized operating conditions

Application of Montgomery T-Tube Placement in Treating Cotton-Myer IV Subglottic Airway Atresia after Bi-Level Airway Recanalization

Objective. The purpose of this study is to explore the effectiveness and safety of Montgomery T-tube placement in treating Cotton-Myer IV subglottic airway atresia after bi-level airway recanalization. Methods. This study is a retrospective study. 11 patients who were treated for IV subglottic airway atresia between January 2017 and January 2019 in the Second Affiliated Hospital of Jiaxing University were involved in this study. The 11 patients all had undergone tracheotomies at our hospital, and they were transferred to the Department of Pulmonary and Critical Care Medicine for Montgomery T-tube placement after bi-level airway recanalization when their subglottic airway was atretic. Patients were observed for their clinical manifestations after placement. The effectiveness of T-tube placement after bi-level airway recanalization was assessed. The incidence of short-term and long-term complications after surgery was assessed. Patients were followed up for 3 to 24 months for evaluating their airway recovery. Results. T-tubes were successfully placed in 11 patients. The atretic airways of all patients were recanalized after treatment. Eight patients got restoration of vocal ability, and 3 patients could only say simple words. None of the patients needed assisted oxygen inhalation. The SpO2 average level was increased from 95±2% before treatment to 97±3% after treatment. Patients had significant relief of cough or sputum, and they had less difficulty in dyspnea. All short- or long-term complications were self-relieved or controlled without further malignant progression after treatment by doctors. The average postoperative extubating time was (14.86±3.62) months. Conclusion. The application of Montgomery T-tube placement in treating Cotton-Myer IV subglottic airway atresia after bi-level airway recanalization is well effective and safe for patients, and it can be promoted in clinical treatment

Distributed Fiberoptic Sensor for Simultaneous Temperature and Strain Monitoring Based on Brillouin Scattering Effect in Polyimide-Coated Fibers

A unique multiparameter sensor for distributed measurement of temperature and strain based on spontaneous Brillouin scattering in polyimide-coated optical fiber is proposed, which is an excellent candidate for the cross-sensitivity problem in conventional Brillouin sensing network. In the experimental section, the discrimination of strain and temperature is successfully demonstrated by analysing the unequal sensing coefficients of the Brillouin frequency shifts generated by different acoustic modes. The Brillouin frequency shifts of the main two peaks are successfully measured to discriminate the strain and temperature with an accuracy 19.68 με and 1.02°C in 2.5 km sensing range. The proposed distributed Brillouin optical fiber sensor allows simultaneous measurement of temperature and strain, thus opening a door for practical application such as oil explorations

Surface-Electron Coupling for Efficient Hydrogen Evolution

Maximizing the activity of materials towards the alkaline hydrogen evolution reaction while maintaining their structural stability under realistic working conditions remains an area of active research. Herein, we report the first controllable surface modification of graphene(G)/V8C7 heterostructures by nitrogen. Because the introduced N atoms couple electronically with V atoms, the V sites can reduce the energy barrier for water adsorption and dissociation. Investigation of the multi-regional synergistic catalysis on N-modified G/V8C7 by experimental observations and density-functional-theory calculations reveals that the increase of electron density on the epitaxial graphene enable it to become favorable for H* adsorption and the subsequent reaction with another H2O molecule. This work extends the range of surface-engineering approaches to optimize the intrinsic properties of materials and could be generalized to the surface modification of other transition-metal carbides

Simultaneous Measurement of Distributed Temperature and Strain through Brillouin Frequency Shift Using a Common Communication Optical Fiber

A multiparameter Brillouin fiber-optic sensor for distributed strain and temperature information measuring based on spontaneous scattering in a common communication optical fiber (the G. 652. D commercial fiber) is presented and experimentally demonstrated. Benefiting from the difference of the temperature and strain sensitivity from different Brillouin peaks with different acoustic modes, our proposed sensing configuration can be used to distinguish ambient temperature and applied strain at the same time, which is an excellent candidate to address the problem of cross-sensitivity in the classical Brillouin system. In the experimental section, using a 21.8 km sensing length of communication optical fiber, a temperature accuracy of 1.13°C and a strain accuracy of 21.46 με are obtained simultaneously. Considering the performance we achieved now, the proposed innovation and experimental setup will have some potential applications in the field of fiber sensors