Performance analysis of photo-electrochemical photodetector based on liquid-phase exfoliation few-layered graphdiyne nanosheets

The band gap of two-dimensional (2D) materials become a hot issue for photoelectric detection. Recently, public attention is thoroughly aroused as to the remarkable electrical transport characteristic and super photoresponse of 2D graphdiyne. The simulation results show that the photoresponse can be adjusted in various solutions based on the graphdiyne nanosheets with different sizes and thicknesses. Based on few-layered graphdiyne nanosheets prepared by a liquid-phase exfoliation method, a photoelectrochemical (PEC)-type few-layered graphdiyne photodetector is demonstrated in this paper. A group of PEC tests are carried out in neutral solution to verify the simulation results. The as-prepared graphdiyne photodetector possesses high photocurrent density, effective responsivity and excellent cycle stability in condition of KCl electrolyte and solar illuminance. The detectivity of the PEC-type graphdiyne photodetector can be easy to adjust by altering electrolyte concentration and other corresponding parameters, which indicates the proposed equipment can be a good candidate for photoelectric detection.

Particle Distribution and Motion in Six-Stage Centrifugal Pump by Means of Slurry Experiment and CFD-DEM Simulation

Six-stage centrifugal pumps are used in deep-sea mining lifting systems and are required to convey slurry containing coarse particles. A six-stage centrifugal pump suitable for operation in a natural mining system was manufactured. High-flow and full-scaled slurry conveying experiments at a 5% and 9% volume concentration of particles was carried out at a large modified test site with artificial nodules. CFD-DEM simulations were carried out to obtain slurry transport characteristic curves, particle transport and distribution characteristics, where the simulation method was validated by the experiment data. A clarified two-stage pump can be used instead of a multi-stage pump for simplified simulation calculations with acceptable accuracy. Local agglomeration of particles caused by backflow was found at the outlet of the diffuser, and such agglomeration decreased with increasing flow rates. It was found that particles are transported non-uniformly, particles transport in diffusers in strands. Particles are transported in a pulse-like mode within the pump, with the latter stage showing similar particle characteristics to those transported in the previous pump stage.

Two-step direct heteroarylation reaction towards 2,5-bis(alkoxy)benzene polymer for organic field-effect transistors processed with tetrahydrofuran

A 2,5-bis(alkoxy)benzene polymer POB-TNT has been newly designed and synthesized via very convenient two-step direct heteroarylation reaction. Its physicochemical properties have been investigated. POB-TNT demonstrates typical [Formula: see text]-type carrier transport characteristic in unencapsulated bottom-gate and top-contact organic field-effect transistors (OFETs) processed with relatively green tetrahydrofuran solvent. The results highlight a readily accessible and low-cost-oriented polymer semiconductor for non-halogenated solvent-processed OFET application.

Analyzing opto-electronic and transport characteristics of ZnSc2Se4 and CdSc2Se4 spinels for opto-electronic and energy storage devices

ZnSc2Se4 and CdSc2Se4 spinels in cubic phase are analyzed by using ab-initio total energy calculations in order to examine their structure along with optoelectronic and thermoelectric characteristics. We used Perdew–Burke–Ernzerhof (PBEsol) generalized gradient approximation (GGA) to evaluate the structural parameters and found that our predicted parameters are good compared with existing other theoretical and experimental results. In addition, we employed the recently developed modified Becke and Johnson (mBJ) potential for the prediction of accurate electronic bandgap measurements of ZnSc2Se4 and CdSc2Se4. By employing mBJ potential, direct bandgap nature of studied spinels is absorbed from electronic band structure plots, which indicate that bandgap decreases as cation Zn is replaced by Cd. Predicted values of bandgap are [Formula: see text] eV for ZnSc2Se4 and [Formula: see text] eV for CdSc2Se4 using mBJ potential representing the studied spinels which play a vital role in the field of opto-electronic devices operating in visible range of spectrum. On the basis of direct bandgaps nature, we also investigate optical characteristic in detail as a function of incident photon energy (0–12 eV). Further, electronic transport characteristic of studied spinels is also investigated with respect to temperature (K) and chemical potential (eV) for their application in energy storage devices.

Hydrometeorological Characteristics of Ice Jams on the Pemigewasset River in Central New Hampshire

Ice jams that occurred on the Pemigewasset River in central New Hampshire resulted in significant localized flooding on 26 February 2017 and 13 January 2018. Analyses of these two case studies shows that both ice jam events occurred in association with enhanced moisture transport characteristic of atmospheric rivers (ARs) that resulted in rain-on-snow, snowpack ablation, and rapid increases in streamflow across central New Hampshire. However, while the ice jams and ARs that preceded them were similar, the antecedent hydrometeorological characteristics of the region were different. The February 2017 event featured a “long melting period with low precipitation” scenario, with several days of warm (~5°–20°C) maximum surface temperatures that resulted in extensive snowmelt followed by short-duration, weak AR that produced ~10–15 mm of precipitation during a 6-h period prior to the formation of the ice jam. Alternatively, the January 2018 event featured a “short melting period with high precipitation” scenario with snowmelt that occurred primarily during a more intense and long-duration AR that produced >50 mm of rainfall during a 30-h period prior to the formation of the ice jam. Composite analysis of 20 ice jam events during 1981–2019 illustrates that 19 of 20 events were preceded by environments characterized by ARs along the U.S. East Coast and occur in association with a composite corridor of enhanced integrated water vapor > 25 mm collocated with integrated water vapor transport magnitudes > 600 kg m−1 s−1. Additional analyses suggest that most ice jams on the Pemigewasset River share many common synoptic-scale antecedent meteorological characteristics that may provide situational awareness for future events.

Effect of Annealing on Proton Conductivity of Aquivion-Like Proton-Exchange Membrane

Proton-conducting membranes were fabricated from a new short-side chain ionomer Inion (Russian analogue of Aquivion) by solution casting method. A series of temperature treatment experiments was conducted to show that annealing of Inion membranes at the temperature range from 160 °C to 170 °C leads to a significant increase of specific proton conductivity to values even higher than those of commercial membrane Nafion NR212. An explanation of this fact can be given by considering the membranes’ proton transport mechanism and water behavior models in nanopores. Matching the proton conductivity mechanism of the membranes, which is realized in nanostructured channels with the diameter of about several nanometers according to the Grotthuss proton hopping mechanism, and the model of water and ice states in nanopores leads to the comprehensive understanding for the further optimization of the membranes to achieve high transport characteristic. For example, it can be improved by increasing the number of side-chain branches of the polymer.

Steam Condensation Heat Transfer During Initial Blow-Down Period of a Severe Nuclear Accident

Heat transfer coefficient (HTC) relations developed using steady-state experimental data are used for capturing the complete heat transport characteristic in a severe nuclear accident. It is important to verify the applicability of these correlation(s) at an early stage of the accident where heat transfer is transient in nature. In this paper, an experimental study is executed for this purpose. High-pressure steam (at 0.26 MPa (2.6 bar) and 0.41 MPa (4.1 bar) absolute pressure) is leaked into the closed containment initially filled with atmospheric air, and filmwise condensation is studied on an isothermally maintained vertical stainless steel test plate. During the experiment, temperature variation across the test plate at specified locations and inside the containment are recorded using the microthermocouples. The steam–air mixture composition is also examined using an online mass-spectrometry system. An inverse heat conduction (IHC) technique, validated using air-jet impingement heat transfer data, is used to estimate the time-varying condensation heat flux. It is found that the existing correlations based on the steady-state experimental data predict the transient condensation flux quite well, except in very early transient situation with a time scale of ∼20 s.