An Fe‐doped CoP nanoarray behaves as a robust 3D monolithic multifunctional catalyst for electrolytic and hydrolytic hydrogen evolution with high activity. Its two‐electrode electrolyzer needs a cell ...voltage of only 1.60 V for 10 mA cm−2 water‐splitting current. It also catalyzes effectively NaBH4 hydrolysis with a low activation energy of ≈39.6 kJ mol−1 and a hydrogen generation rate of 6.06 L min−1 g−1.
It is highly attractive but challenging to develop earth‐abundant electrocatalysts for energy‐saving electrolytic hydrogen generation. Herein, we report that Ni2P nanoarrays grown in situ on nickel ...foam (Ni2P/NF) behave as a durable high‐performance non‐noble‐metal electrocatalyst for hydrazine oxidation reaction (HzOR) in alkaline media. The replacement of the sluggish anodic oxygen evolution reaction with such the more thermodynamically favorable HzOR enables energy‐saving electrochemical hydrogen production with the use of Ni2P/NF as a bifunctional catalyst for anodic HzOR and cathodic hydrogen evolution reaction. When operated at room temperature, this two‐electrode electrolytic system drives 500 mA cm−2 at a cell voltage as low as 1.0 V with strong long‐term electrochemical durability and 100 % Faradaic efficiency for hydrogen evolution in 1.0 m KOH aqueous solution with 0.5 m hydrazine.
A Ni2P nanoarray grown on nickel foam (Ni2P/NF) behaves as a bifunctional catalyst for anodic hydrazine oxidation and cathodic hydrogen evolution in alkaline hydrazine solution. This two‐electrode electrolytic system drives 500 mA cm−2 at a cell voltage as low as 1.0 V with strong long‐term electrochemical durability and 100 % Faradaic efficiency for hydrogen evolution.
The overall mechanical behavior of the structure of a gravity dam is comprehensively reflected by modal information included in the measured vibration response. In this study, the dynamic elastic ...modulus of the dam body and foundation materials were inverted via an underwater explosion, and analyzed. First, the first three main frequencies and basic mode shapes of the dam were obtained based on the acceleration response induced by the explosion. Then, the support vector regression model optimized with the particle swarm optimization algorithm was used to invert the mechanical parameters. The results indicate that the objective function that considers dominant frequency and mode shape has a greater advantage in terms of anti-noise compared to when only the dominant frequency is considered. The inverted dynamic elastic modulus is about 1.5 times that of the static elastic modulus of the corresponding material, and the calculated modal values using the inversion parameters are basically consistent with the measured values. This method provides a new way of determining the dynamic parameters of gravity dams.
The development of efficient bifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of extreme importance for future renewable energy systems. This ...Communication reports the recent finding that room‐temperature treatment of CoO nanowire array on Ti mesh by NaBH4 in alkaline media leads to in situ development of CoB nanoparticles on nanowire surface. The resulting self‐supported CoB@CoO nanoarray behaves as a 3D bifunctional electrocatalyst with high activity and durability for both HER (<17% current density degradation after 20 h electrolysis) and OER (<14% current density degradation after 20 h electrolysis) with the need of the overpotentials of 102 and 290 mV to drive 50 mA cm−2 in 1.0 m KOH, respectively. Moreover, its two‐electrode alkaline water electrolyzer also shows remarkably high durability and only demands a cell voltage of 1.67 V to deliver 50 mA cm−2 water‐splitting current with a current density retention of 81% after 20 h electrolysis. This work provides a promising methodology for the designing and fabricating of metal‐boride based nanoarray as a high‐active water‐splitting catalyst electrode for applications.
Room‐temperature treatment of CoO nanowire array on Ti mesh by NaBH4 in alkaline media leads to in situ surface development of CoB nanoparticles. Such CoB@CoO core–shell nanoarray is stable and efficient for water splitting with the need of 1.67 V to deliver 50 mA cm−2 in 1.0 m KOH.
In this paper, we report on the first preparation of well-defined SiO(2)-coated graphene oxide (GO) nanosheets (SiO(2)/GO) without prior GO functionalization by combining sonication with sol-gel ...technique. The functional SiO(2)/GO nanocomposites (F-SiO(2)/GO) obtained by surface functionalization with NH(2) group were subsequently employed as a support for loading Ag nanoparticles (AgNPs) to synthesize AgNP-decorated F-SiO(2)/GO nanosheets (AgNP/F-SiO(2)/GO) by two different routes: (1) direct adsorption of preformed, negatively charged AgNPs; (2) in situ chemical reduction of silver salts. The morphologies of these nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the resultant AgNP/F-SiO(2)/GO exhibits remarkable catalytic performance for H(2)O(2) reduction. This H(2)O(2) sensor has a fast amperometric response time of less than 2s. The linear range is estimated to be from 1×10(-4) M to 0.26 M (r=0.998) and the detection limit is estimated to be 4 × 10(-6) M at a signal-to-noise ratio of 3, respectively. We also fabricated a glucose biosensor by immobilizing glucose oxidase (GOD) into AgNP/F-SiO(2)/GO nanocomposite-modified glassy carbon electrode (GCE) for glucose detection. Our study demonstrates that the resultant glucose biosensor can be used for the glucose detection in human blood serum.
The present article reports on a simple, economical, and green preparative strategy toward water-soluble, fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 6.9% by ...hydrothermal process using low cost wastes of pomelo peel as a carbon source for the first time. We further explore the use of such CPs as probes for a fluorescent Hg2+ detection application, which is based on Hg2+-induced fluorescence quenching of CPs. This sensing system exhibits excellent sensitivity and selectivity toward Hg2+, and a detection limit as low as 0.23 nM is achieved. The practical use of this system for Hg2+ determination in lake water samples is also demonstrated successfully.
The disturbance of a rock mass due to blasting impact and stress redistribution can significantly affect the overall performance of an excavation. Crack formation during presplit blasting was ...analyzed with a mathematical model, considering the in situ stress. The results clearly indicate that the in situ stress can inhibit crack formation. The linear density of the explosive and blast hole spacing should be adjusted to improve crack formation. The damage distribution produced by different blasting approaches was reproduced with a numerical simulation based on the secondary development of LS-DYNA. The results demonstrate that the damage control effects of conventional presplit blasting or smooth blasting under in situ stress are not ideal. Owing to the combination of blasting load and stress redistribution, crack formation at the lateral sides was inhibited during presplit blasting, while the middle side could not be sufficiently broken during smooth blasting. An optimized method of presplit-smooth blasting was proposed and verified with numerical simulations. Finally, based on excavation of the Baihetan high rock slope, a comparison of the conventional and optimized approaches was conducted with sonic wave tests and roughness monitoring. The results demonstrate that the presplit-smooth blasting approach inherits the advantages of both presplit and smooth blasting, and could significantly improve contour control effects.
•The crack formation under blasting was analyzed with a mathematical model.•Different optimize approaches were compared by using numerical simulation.•The method of presplit-smooth blasting was proposed.•Site experiment was implemented to with the sonic wave test and flatness measurement.•The presplit-smooth blasting was verified that it could inherit the advantages of presplit and smooth blasting.
In the process of deep-hole blasting, the quality of blasting stemming seriously affects the blasting effect, but the optimal stemming length is difficult to determine. In this paper, the movement ...process and length optimization of deep-hole blasting stemming were investigated. At first, the mechanical mechanism of stemming structure was theoretically analyzed, and the additional friction resistance of stemming structure caused by the compression of the blasting shock wave was considered. Then, a time-sharing piecewise solution method for the movement process of stemming structure based on the method of time-space discretization was proposed, which can reveal the distribution law of the decreasing friction resistance along the axial direction. Moreover, the movement law of stemming structure under the conditions of explosion pressure ranging from 0.2 to 1.2 GPa, duration of detonation gas ranging from 10 to 15 ms, sliding friction coefficients ranging from 0.02 to 0.06, borehole diameters ranging from 76 to 200 mm, and stemming length ranging from 1.6 to 3.0 m was studied. Results showed that explosion load, duration of detonation gas, sliding friction coefficients, borehole diameters and stemming length all have a great influence on the movement of stemming structure. Finally, aiming at the common stemming materials of rock debris in engineering blasting, the effects of rock mass properties, explosion load, and borehole diameters on the optimal stemming length have been discussed based on the optimization principle that allows the part of stemming structure to rush out of borehole. It is found that the optimal stemming length increases linearly with the logarithmic product of the explosion pressure and the borehole diameter by the statistical analysis of the optimal stemming length under different calculation conditions. In view of the above, a new method for calculating the optimal stemming length is proposed and its reliability has been verified preliminarily by field application.
Since the discovery of cell-free DNA (cfDNA) in maternal plasma, it has opened up new approaches for non-invasive prenatal testing. With the development of whole-genome sequencing, small ...subchromosomal deletions and duplications could be found by NIPT. This study is to review the efficacy of NIPT as a screening test for aneuploidies and CNVs in 42,910 single pregnancies.
A total of 42,910 single pregnancies with different clinical features were recruited. The cell-free fetal DNA was directly sequenced. Each of the chromosome aneuploidies and the subchromosomal microdeletions/microduplications of PPV were analyzed.
A total of 534 pregnancies (1.24%) were abnormal results detected by NIPT, and 403 pregnancies had underwent prenatal diagnosis. The positive predictive value (PPV) for trisomy 21(T21), trisomy 18 (T18), trisomy 13 (T13), sex chromosome aneuploidies (SCAs), and other chromosome aneuploidy was 79.23%, 54.84%, 13.79%, 33.04%, and 9.38% respectively. The PPV for CNVs was 28.99%. The PPV for CNVs ≤ 5 Mb is 20.83%, for within 5-10 Mb 50.00%, for > 10 Mb 27.27% respectively. PPVs of NIPT according to pregnancies characteristics are also different.
Our data have potential significance in demonstrating the usefulness of NIPT profiling not only for common whole chromosome aneuploidies but also for CNVs. However, this newest method is still in its infancy for CNVs. There is still a need for clinical validation studies with accurate detection rates and false positive rates in clinical practice.
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