Search

The IL-based electrolysis-deposition method was used to modulate Pb crystal facets (ED-Pb) for enhancing the CO2RR. ED-Pb-900 shows a formate formation rate of 2067.2 μmol h−1 cm−2, due to the preferential exposure of Pb(111) and larger ECSA.

The interfacial microhabitat induced by triazole ionic liquid ([124Triz]−) electrolyte can effectively enhance formate selectivity for electrochemical CO2 reduction reaction. However, the catalytic mechanism remains unclear. Herein, we combined molecular dynamics simulation and density functional theory to reveal the regulatory mechanism. The results showed that the dipolar interaction between CO2 and [124Triz]− cooperating the hydrogen bonds between [124Triz]− and H2O facilitate the accumulation of H atoms around C atoms of CO2. Meanwhile, the strong polar [124Triz]− induces negative electrostatic potential for the H atoms of H2O near anions. As a result, the negative H atoms are more likely to attack the positive C atoms of CO2, which results in a lower free energy of -0.10 eV for the formation of *HCOO intermediate and promotes the formation of formate. Thus, the [124Triz]− contributes to high formate selectivity owing to the combined effects of strong CO2-dipole interaction and hydrogen bonds with H2O.

In this study, triaxial compression and seepage tests were conducted on briquette and raw coal samples using a coal rock mechanics-seepage triaxial test system (TAWD-2000) to obtain the complete stress–strain curves of the two samples under certain conditions. On this basis, the different damage forms of the two coal samples and the effect of their deformation and damage on their permeability were analyzed from the perspective of fine-scale damage mechanics. Moreover, the sensitivity of permeability to external variables and the suddenness of coal and gas outbursts were discussed. The results show that the compressive strength of raw coal is 27.1 MPa and the compressive strength of briquette is 17.3 MPa, the complete stress–strain curves of the two coal samples can be divided into four stages and show a good correspondence to the permeability–axial strain curves. Since briquette and raw coal have different structural properties, they present different damage mechanisms under load, thus showing great diversity in the permeability-axial strain curve, especially in the damage stage. The deformation affects the seepage characteristics of briquette mainly in the latter two stages, while it affects raw coal throughout the test. The four stages of the complete stress–strain seepage test of raw coal can well explain the four stages of coal and gas outburst process, i.e., preparation, initiation, development, and termination. Hence, the law of coal permeability to gas variation can be utilized for the coal and gas outburst prediction and forecast. The research results are valuable for exploring the real law of gas migration in coal seams.

A Cu–N-doped carbon nanotube with an unsaturated coordination Cu atom (Cu–N3) was fabricated and it exhibited over 90% CO faradaic efficiency (FE) in a wide potential range from −0.42 to −0.92 V. The maximum CO FE can reach 98.7% with a high CO partial current density of 234.3 mA cm−2 in a flow cell. Theoretical calculations elucidated that the Cu–N3 site facilitated the formation of COOH*, thereby accelerating the CO2 electrochemical reduction.

The concentration of CO2 in the atmosphere increases with utilizing fossil energy, which caused serious environmental problems. Owing to the advantage of using renewable electricity, the issue of carbon recycling and energy recovery based on the electrochemical CO2 reduction reaction (CO2RR) presents a potentially sustainable way to transform CO2 into a variety of valuable products, such as carbon monoxide (CO), methanol (CH3OH), formic acid (HCOOH/HCOO−), and so on. The challenges of CO2RR mainly include high overpotential, low current density and low Faraday efficiency (FE). Therefore, the development of new electrochemical reduction systems to reduce overpotential and improve reaction selectivity is the research hotpot in CO2RR. The selection of the electrolyte is very important to design efficient electrochemical reduction systems, which provides the reaction environment, transports ions and serves a conductive medium in CO2RR system. Under the same condition, the species, concentration, and pH of electrolytes influence the local reaction environment, the current density and the selectivity of products. So far, various electrolytes, such as alkali metal and ionic liquid electrolytes have been applied to enhance the performance of CO2RR. Therefore, in comprehensive understanding of the electrolyte effects on CO2RR is crucial in selecting proper electrolytes for the reduction of CO2 to desired products. This paper mainly reviews the recent processes in the alkali metal and ionic liquid electrolytes, and summarizes their effects in CO2RR as well. Firstly, we summarize the product distribution and current density of CO2RR in the different alkali metal aqueous. Alkali metal aqueous is the most common solvent for CO2RR, because alkali metal aqueous are widely available at low cost, relatively easy to prepare, and store safely. Many studies reported that alkali metal aqueous effects CO2RR current density and product distribution. The effects of metal aqueous on the CO2RR based on preferential hydrolysis of hydrated cations near the cathode surface, which to buffer the electrolyte near the electrode surface, offsetting the polarization losses caused by concentration gradient. At the same time, hydrated alkali metal cations in the outer Helmholtz plane can create a dipole field, which can stabilize the adsorption the intermediates to enhance the selectivity of the CO2RR on the intrinsic activity. Secondly, ionic liquids as electrolytes have also attracted extensive interest due to their high electrical conductivity, high CO2 adsorption capacity, and high selectivity. Because the ionic liquid can be adsorption on the electrode surface to reduce the overpotential and change the reaction microenvironment. Using different ionic liquid electrolytes can promote CO2 electroreduction to different products, such as CO, HCOO−/HCOOH, CH3OH and so on, especially in the performance of production selectively. Although important progress has been made in CO2RR with ionic liquid electrolyte, the mechanism of CO2RR to C2+ products is unclear, especially the interaction between the liquid and the electrode surface. Finally, we briefly prospect the future research priorities and directions of CO2RR systems in ionic liquid electrolyte.

In this study, a new electrolyte system consisting of tetrabutylphosphonium 4-(methoxycarbonyl) phenol ([P4444][4-MF-PhO]) ionic liquid and acetonitrile (AcN) was developed as CO2 electroreduction electrolyte to produce oxalate, and the mechanism was studied. The results showed that using the new ionic liquid-based electrolyte, the reduction system exhibits 93.8% Faradaic efficiency and 12.6 mA cm-2 partial current density of oxalate at -2.6 V (vs. Ag/Ag+). The formation rate of oxalate is 234.4 μmol cm-2 h-1, which is better than that reported in the literature. The mechanism study using density functional theory (DFT) calculation revealed for the first time that [P4444][4-MF-PhO] IL can effectively activate CO2 molecules through ester and phenoxy double active sites, stabilize the reaction intermediate. The potential barriers of the key intermediates *CO2- and *C2O42- formation by induced electric-field was reduced in the phosphonium-based ionic environment, which greatly facilitates the activation and conversion of CO2 molecules to oxalate.

The influence mechanism of the blade tip clearance (TC) of an inducer on the performance of a centrifugal pump at high speed was researched under different flow rate conditions in this work. An experiment on the pump’s external performance was carried out, and numerical calculation was also performed under four different TCs. The full characteristic performance curves, static pressure and pressure pulsation distributions of the pump were obtained. Through the research and analysis, it was found that the influence of the TC on the efficiency and the head of the centrifugal pump are related to the flow rate. Under the influence of a large flow rate, the increase in the TC is helpful to improve the efficiency and the head of the pump. The increase in the TC helps to weaken the gap jet effect on the inducer. The inlet jet of the inducer, caused by TC leakage, will form a low-pressure vortex zone at the inlet of the inducer. The splitter-bladed inducer’s pressure pulsation is affected by the TC. The peak pressure pulsation at the monitoring point at the short blades is larger than that at the long blades. With the increase in TC, the cavitation degree at the inlet of the long blade of the inducer is decreased, while the cavitation degree at the short blade is deepened. It is also found that the TC has little effect on the radial force of the inducer and the impeller. These results will provide the design basis for the tip clearance of an inducer.

To provide technical support for gas extraction and gas accident prevention technology, the permeability law of gas in coal seams under different ground stress and gas pressure has been explored. The evolution law of coal sample permeability under different confining pressure and gas pressure was deeply studied by using the coal rock mechanics–permeability test system TAWD-2000. The conclusions are as follows. The permeability of coal samples can be divided into three stages in the whole stress–strain process, gradually decreasing stage, tending to be stable and slowly rising stage, and significantly rising stage. When the confining pressure and axial pressure of the coal sample are constant, the permeability of the coal sample decreases gradually with the increase in gas pressure. When the gas pressure and axial pressure of coal samples are constant, the permeability of the coal samples first decreases and then rises with the gradual increase of confining pressure. Under different confining pressures and gas pressures, the change degree and change rate of coal permeability and are different in the whole stress–strain process. The research results can provide necessary data support for subsequent numerical calculations and practical engineering application.

In order to study the effect of tip clearance on the internal cavitation stability of a shunt blade inducer, an external characteristics experiment of a centrifugal pump with a shunt blade inducer was carried out. Based on the turbulence model and mixture model, the cavitating flow in a centrifugal pump with the inducer was numerically simulated. The influence of tip clearance on the cavitating flow in a shunt inducer was studied and analyzed. Through the research, it was found that tip clearance has a certain influence on the critical cavitation coefficient. The existence of the tip clearance caused a significant leakage vortex near the inducer’s inlet and a strong transient effect was shown. The location and degree of cavitation caused by the tip leakage are clarified in this paper. Tip clearance has a great impact on the pressure distribution on a shunt blade inducer. The influence law of tip clearance on an inducer’s blade load distribution was clarified. The results showed that tip clearance has a significant effect on the cavitation of a shunt blade inducer under low flow rate conditions.

In this paper, the fracture zone of the Chunxuan Road Tunnel in Jinan, Shandong Province, China was selected for the engineering background. With reference to the field monitoring data, a finite element model was established based on the strength reduction method. With the aid of this model, the influences of different initial support parameters (including lining, bolt and steel arch) on the tunnel deformation in the fracture zone were analyzed to obtain reasonable initial support parameters. The results show that the tunnel deformation under the original initial support is severe. Among the initial support methods, such as lining, bolt, and steel arch, the parameters of the lining and steel arch significantly influence the tunnel deformation in the fracture zone. Therefore, selecting appropriate initial support parameters can effectively control the tunnel deformation in the fracture zone. After the optimized support scheme is adopted, failure instability no longer occurs in the tunnel and the tunnel deformation is also effectively controlled. The research findings provide a clear reference for deformation control and support scheme optimization of similar projects.

Developing effective catalysts based on earth abundant elements is critical for CO2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (jCO) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a jCO of 14.0 mA cm−2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher jCO of 29.7 mA cm−2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N3 site, which facilitates the formation of the key intermediate COOH* through a lowered free energy barrier.

Developing effective catalysts based on earth abundant elements is critical for CO2 electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (jCO) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N3 site embedded in graphitic carbon nitride. The prepared catalyst exhibits a 98.8% CO FE with a jCO of 14.0 mA cm−2 at a low overpotential of 0.44 V in aqueous electrolyte, outperforming all reported Mn SACs. Moreover, a higher jCO of 29.7 mA cm−2 is obtained in an ionic liquid electrolyte at 0.62 V overpotential. In situ X-ray absorption spectra and density functional theory calculations demonstrate that the remarkable performance of the catalyst is attributed to the Mn-N3 site, which facilitates the formation of the key intermediate COOH* through a lowered free energy barrier., Developing effective catalysts based on earth abundant elements is critical for electrochemical CO2 reduction. Here, the authors prepare a manganese single atom catalyst with high CO2 reduction performance, which can be attributed to the Mn-N3 site embedded in graphitic carbon nitride.

Grouting has been widely used in geotechnical engineering, such as deep mines and tunnels, to reinforce the rock joints or cracks. In this study, the effects of particle sizes of cement and nano-SiO2 on shear strength parameters, microstructure characteristics and rheological properties were evaluated. Results showed that with the addition of superfine cement and nano-SiO2, the early-age shear strength parameters (cohesion and internal friction angle) and microstructure characteristic of specimens were significantly improved. The large viscosity of grouts caused by the fast hydration reaction with superfine cement and nano-SiO2 addition can be significantly optimized by adding superplasticizer (SP). The optimal SP dose levels of 1.5% and 0.75% were recommended for superfine cement grouts with and without nano-SiO2 addition, respectively. And the direct shear test on grout-infilled sandstone specimens proved the grouting effectiveness. The finer cement exhibited higher viscosity, while the shear strength parameters of two types of superfine cements varied little. Suitable superfine cement should be selected in grouting engineering with the consideration of crack aperture, groutability and cost-savings.

INTRODUCTION:Emerging health technologies (EHT) are important to meet the challenges faced by healthcare systems but a major pressure on health systems as well (1). The International Information Network on New and Emerging Health Technologies (EUROSCAN) is a collaborative network to manage the introduction of EHT and share information on the results of early identification and assessment of EHT (2). This article analyzed the early assessment reports of EHT during 2000–2016 published in the EUROSCAN database (3), in order to reflect the 21st century development trend of the EHT.METHODS:The EHT report data was downloaded by researchers from the official website of the EUROSCAN and arranged using Excel 2007. A descriptive analysis on the number and growth rate of EHT, distribution of technology type and specialties, developmental trend of the integrated technologies were conducted with SAS 9.3.RESULTS:Health technology early assessment reports (3,151) have been published in the past 17 years, of which drugs had the highest proportion (54.3 percent). Most of new and emerging health technologies were adopted in oncology and radiotherapy (32.2 percent). The average growth rate every 4 years of EHT from 2001 to 2016 was 34.6 percent, the fastest-growing period was between 2005 and 2008 (63.8 percent). Rehabilitation & disability was the fastest-growing EHT specialty (184.4 percent) and the integrated technologies was the fastest-growing EHT type (64.6 percent).CONCLUSIONS:With the objective needs of effective technologies to deal with cancer and chronic disease, as well as the revolution of science, EHT were in the process of vigorous development, especially oncology & radiotherapy technologies. The integrated technologies and the ones applied in multidisciplinary areas have become a new spotlight. Early identification and timely assessment of new and emerging health technologies has aroused wide public concern. It is suggested to establish an Early Awareness and Alert Systerm in China.