The development of a low cost, high performance and stable catalyst is an important prerequisite for the widespread application of efficient hydrogen production from sodium borohydride (NaBH4). ...Herein, Ni-BTC is derived into CoP-NiCoP/NC catalyst consisting of CoP-NiCoP nanorods and nitrogen-doped carbon (NC) microsphere by hydrothermal and gas-phase phosphorylation methods. The CoP-NiCoP/NC catalyst exhibits good catalytic activity, with a high hydrogen evolution rate of NaBH4 reaching 7052 mL·min−1·g−1 at 303 K, and an activation energy of only 35.57 kJ·mol−1. This is significantly better than most catalysts reported previously. In addition, the CoP-NiCoP/NC catalyst demonstrates good durability with 75 % of the original catalytic activity after 10 performance testing. This excellent catalytic performance is achieved thanks to its porous microsphere structural design and the cooperative effect between CoP and NiCoP. This catalyst with high catalytic performance and mild preparation conditions is promising for future actual applications.
•Novel CoP-NiCoP/NC catalyst was prepared by three-step simple methods.•The CoP-NiCoP/NC catalyst composed of CoP-NiCoP nanorods and nitrogen-doped carbon (NC) microspheres.•The synergistic catalysis of CoP and NiCoP effectively improved the catalytic activity.•The catalyst achieved excellent hydrogen production performance and lower Ea of 35.57 kJ·mol−1.
Due to the high discharge capacity, lithium-rich layered oxides are regarded as one of the most promising cathode materials for lithium-ion batteries (LIBs). In the present circumstances, however, ...they have been suffering from rapid voltage fading and poor rate capability. Herein, a lithium-rich layered oxide of Li1.2Mn0.6Ni0.2O2 (PLMNO) with a specific fine microstructure is successfully prepared through a solvothermal method followed by a stepwise calcination process. The PLMNO material consists of primary nanoparticles assembled into a 3D porous rod-like hierarchical micro/nanostructure, which exhibits a facile pathway for the transportation of lithium ions and electrons. The initial charge and discharge capacities at a current density of 0.1C (1C = 200 mA g−1) are 348.3 and 263.4 mAh g−1, respectively, with a initial coulombic efficiency of 75.6% in the voltage range of 2.0–4.8 V. At a large rate of 1C, a high discharge capacity of 197.3 mAh g−1 can be achieved with capacity retention of 88.5% after 200 charge/discharge cycles. In addition, the voltage fading during charge/discharge cycles is remarkably suppressed. The superior electrochemical properties make this layered Li-rich material of PLMNO a very promising cathode material in LIBs.
•Li1.2Mn0.6Ni0.2O2 with 3D porous rod-like hierarchical micro/nanostructure is successfully prepared.•The special microstructure provides a facile pathway for the transportation of Li+ and electrons.•Li1.2Mn0.6Ni0.2O2 exhibits a superior electrochemical performance.•The improved rate capability and suppressed voltage decay are achieved.
In this study, sea ice thickness (SIT) and sea ice extent (SIE) in the Bohai Sea from 2000 to 2016 were investigated. A surface heat balance equation was applied to calculate SIT using ice surface ...temperatures estimated from the Moderate Resolution Imaging Spectroradiometer (MODIS) data with input from air temperature and wind speed from reanalyzing weather data. No trend was found in SIT during 2000-2016. The mean SIT and SIE during this period were 5.58±0.86 cm and 23×10
3
±8×10
3
km
2
, respectively. The largest SIT and SIE periods were observed during the second half of January and the first half of February, respectively. The Spearman correlation coefficient between mean ice thickness and average air temperature from 21 automatic weather stations around the Bohai Sea was -0.94 (P < .005), and the coefficient between median ice extent and negative accumulated temperature was -0.503 (P < .001). The rate of increase in air temperature around the Bohai Sea is 0.271°C per decade in winter for 1979-2016 (P < .05), which is much lower than that in northern polar area (0.648°C per decade). This rate has not resulted in a decreasing trend in SIT and SIE for the past 16 years in the Bohai Sea.
Lithium aluminum hydride (LiAlH4) with a high hydrogen capacity of 10.5 wt% has become one of the most promising solid-state hydrogen storage materials for onboard hydrogen fuel cell systems. ...However, neither dehydrogenation kinetics nor cycling behaviors of LiAlH4 can fulfill the requirements of practical application. Here, we prepared the Ni/C nanoparticles anchored on large-size Ti3C2Tx nanosheets, firstly introduced into LiAlH4 to investigate its catalytic effect. Dehydrogenation experiments demonstrate that LiAlH4 doped with 7 wt% Ni/C@Ti3C2 starts to release hydrogen at 56.9 °C. Also, it can release about 4.3 wt% hydrogen within 50 min at 120 °C. The activation energies of LiAlH4 doped with 7 wt% Ni/C@Ti3C2 for the first and second steps are 34.5% and 53.2% lower than the as-received LiAlH4, respectively. Under 300 °C and 40 bar hydrogen, it can absorb 0.58 wt% hydrogen. It is found that in situ formed intermetallic Al2Ti during ball milling can weaken the Al-H bonds in LiAlH4 through interfacial charge transfer and the dehybridization, benefitting for the breaking of the Al-H bond in LiAlH4. In addition, Al2Ti can promote the adsorption and splitting of H2, contributing to the rehydrogenation of LiAlH4.
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•Doping Ni/C@Ti3C2 can reduce the release hydrogen of LiAlH4.•The in-situ formation of Al2Ti enhances the hydrogen storage properties of LiAlH4.•Al2Ti can reduce the desorption energy barrier of Al-H bond and enhance the adsorption of H2.
An umbrella review of meta-analyses was performed to summarize the evidence of associations between alcohol consumption and health outcomes and to assess its credibility. Meta-analyses of prospective ...cohort studies reporting the associations of alcohol consumption with health outcomes were identified. We recalculated the random-effects summary effect size and 95% confidence interval, heterogeneity, and small-study effect for each meta-analysis and graded the evidence. Fifty-nine publications reporting 224 meta-analyses of prospective cohort studies with 140 unique health outcomes were included, in which there were 49 beneficial associations and 25 harmful associations with nominally statistically significant summary results. But quality of evidence was rated high only for seven beneficial associations (renal cell carcinoma risk, dementia risk, colorectal cancer mortality, and all-cause mortality in patients with hypertension for low alcohol consumption; renal cell carcinoma risk, cardiovascular disease (CVD) risk in patients with hypertension and all-cause mortality in patients with hypertension for moderate consumption) and four harmful associations (cutaneous basal cell carcinoma risk for low alcohol consumption; cutaneous basal cell carcinoma risk and cutaneous squamous cell carcinoma risk for moderate alcohol consumption; hemorrhagic stroke risk for high alcohol consumption). In this umbrella review, only 11 health outcomes (5 in low alcohol consumption, 5 in moderate alcohol consumption and 1 in high alcohol consumption) with statistically significant showed high quality of epidemiologic evidence. More robust and larger prospective studies are needed to verify our results.
This paper is concerned with the network-based finite-time controller design problems for a class of switched linear systems with sampled-data control approach, the quantisation errors are also taken ...into account. A novel event-driven communication scheme is developed which can be seen as the extension of time-driven communication cases. By invoking an input-delay approach, the networked switched control systems are firstly modelled as a kind of switched time-delay systems with time-varying delays, upon which a set of mode-dependent controllers are then designed such that the reformulated switched system with time-varying delays is finite-time bounded and has a guaranteed noise attenuation performance in the finite-time
sense. Moreover, a co-design algorithm of mode-dependent control and event-driven communication is presented to find the optimal event-driven strategy for reducing transmission loads. Finally, a numerical example and an application to F-18 aircraft are provided to demonstrate the effectiveness and the advantages of the developed results.
Objective: To analyze the mechanism of the halo vest-assisted Z-shape elevating-pulling reduction technique for cervical unilateral locked facets, and confirm the safety of the spinal cord under the ...epidural pressure that occurs during the reduction process. Methods: Eleven osteoligamentous whole coronal and cervical spine specimens were established as skull-neck-thorax models of cervical unilateral locked facets at the C5/6 level. The halo vest-assisted Z-shape elevating-pulling reduction technique was then applied to reduce the locked facets. The changes in the epidural pressure in five cervical positions (cervical physiological curvature, cervical lateral bending, cervical unilateral locked facets, cervical unilateral perched facets, and reduction) were measured by a pressure sensor during the reduction procedure. The models simultaneously underwent multi-angle radiographic examination and CT scanning. Results: Successful closed reduction was achieved via the halo vest-assisted Z-shape elevating-pulling reduction technique in all 11 models. The epidural pressure in the cervical unilateral locked facets position was significantly higher than that in the other four cervical positions (P < 0.005). There was no significant difference in the epidural pressures measured during cervical lateral bending, cervical unilateral perched facets, and reduction. Conclusions: Maximum epidural pressures were measured in the position of cervical unilateral locked facets. The halo vest-assisted Z-shape elevating-pulling reduction technique achieved spinal decompression without causing secondary spinal cord injury. The halo vest-assisted Z-shape elevating-pulling reduction technique is safe and effective, and has a high success rate of reduction.
This paper investigates the finite-time filter design problem for a class of switched linear systems with parameter uncertainties and impulsive effects. The sensor failures with output-measurement ...errors and mode-detection delays are taken into account. A filter mode-dependent Lyapunov-like function construction approach is developed which can effectively reduce the filter design difficulty induced by the mode-detection delays. Sufficient conditions on finite-time boundedness and finite-time H∞ performance are first derived for the augmented switched error systems, upon which the mode-dependent finite-time H∞ filter is designed. Performance of the potential of the developed filter is illustrated by a numerical example and an application to PWM (Pulse-Width-Modulation)-driven boost converter.
•Filter-dependent Lyapunov-like function can simplify the asynchronous filter design.•Impulsive effects and sensor-induced faults are addressed by filtering error model.•The developed techniques can analyze the Lyapunov asymptotic stability performance.
This paper investigates the finite-time boundedness (FTB) problem for a class of uncertain switched neural networks with time-varying delays. By exploring the mode-dependent properties of each ...subsystem, all the subsystems could be categorized into stable and unstable ones under the Lyapunov-like function framework. The sufficient conditions and a set of unified switching signals with average dwell time (ADT) are first derived with a known limit to the total activation time ratio between unstable and stable subsystems. Then, the obtained results are extended to a new switching approach with mode-dependent average dwell time (MDADT). Compared with general results, our proposed approach distinguishes the stable and unstable subsystems rather than viewing all subsystems as being unstable, thus getting less conservative switching criteria. Finally, a numerical example is provided to show the validity and the advantages of the finding techniques.
