Search

The planetary boundary layer (PBL) height (PBLH) is an important parameter for weather, climate, and air quality models. Radiosonde is one of the most commonly used instruments for PBLH determination and is generally accepted as a standard for other methods. However, mainstream approaches for the estimation of PBLH from radiosonde present some uncertainties and even show disadvantages under some circumstances, and the results need to be visually verified, especially during the transition period of different PBL regimes. To avoid the limitations of individual methods and provide a benchmark estimation of PBLH, we propose an ensemble method based on high-resolution radiosonde data collected in Beijing in 2017. Seven existing methods including four gradient-based methods are combined along with statistical modification. The ensemble method is verified at 08:00, 14:00, and 20:00 Beijing time (BJT = UTC + 8), respectively. The overestimation of PBLH can be effectively eliminated by setting thresholds for gradient-based methods, and the inconsistency between individual methods can be reduced by clustering. Based on the statistics of a 1-year observational analysis, the effectiveness (E) of the ensemble method reaches up to 62.6 %, an increase of 6.5 %–53.0 % compared to the existing methods. Nevertheless, the ensemble method suffers to some extent from uncertainties caused by the consistent overestimation of PBLH, the profiles with a multi-layer structure, and the intermittent turbulence in the stable boundary layer (SBL). Finally, this method has been applied to characterize the diurnal and seasonal variations of different PBL regimes. Particularly, the average convective boundary layer (CBL) height is found to be the highest in summer, and the SBL is lowest in summer with about 200 m. The average PBLH at the transition stage lies around 1100 m except in winter. These findings imply that the ensemble method is reliable and effective. [ABSTRACT FROM AUTHOR]

PdPt nanosheets decorated on SnS 2 nanosheets (i.e., PdPt@SnS 2 NSs) were fabricated for a novel electrochemiluminescence (ECL) biosensor for ultrasensitive detection of miRNA-21 based on catalytic hairpin assembly (CHA) cycles. The PdPt@SnS 2 NSs serve as both the main luminophore and a highly effective coreaction accelerator in the ECL biosensor. In the CHA cycles, more miRNA-21 is captured, and the performance of the ECL biosensor is improved. When miRNA-21 is present, the hairpin chain DNA1 (i.e., H1) is opened, and the ferrocene (Fc)-modified hairpin chain DNA2 (i.e., Fc-H2) hybridizes with as-opened H1 by replacing miRNA-21 to stimulate CHA cycles of miRNA-21. During the CHA cycles, Fc-H2 quenches the ECL signal to monitor miRNA-21. As a result, the ECL biosensor shows ultrasensitive and highly selective detection of miRNA-21 from 1 aM to 1 nM with a detection limit (LOD) of 0.02 aM. In addition, the ECL biosensor exhibits excellent practicality for miRNA-21 detection in human serum samples.

Heterostructured materials have great potential as cathodes for zinc-ion batteries (ZIBs) because of their fast Zn 2+ transport channels. Herein, hollow MoS 2 @C@Cu 2 S heterostructures are innovatively constructed using a template-engaged method. The carbon layer improves the electrical conductivity, provides a high in situ growth area, and effectively restricts volume expansion during the recycling process. MoS 2 nanosheets are grown on the surfaces of hollow C@Cu 2 S nanocubes using the in situ template method, further expanding the specific surface area and exposing more active sites to enhance the electrical conductivity. As expected, an admirable reversible capacity of 197.2 mA h g -1 can be maintained after 1000 cycles with a coulombic efficiency of 91.1%. Therefore, we firmly believe that this work points the way forward for high-performance materials design and energy storage systems.