Abstract. Extensive forest fires occurred during late July 2014 across the forested region of Siberia, Russia. Smoke plumes emitted from Siberian forest fires underwent long-range transport over Mongolia and northeast China to the Korean Peninsula, which is located ∼ 3000 km south of the Siberian forest. A notably high aerosol optical depth of ∼ 4 was observed at a wavelength of 500 nm near the source of the Siberian forest fires. Smoke plumes reached 3-5 km in height near the source and fell below 2 km over the Korean Peninsula. Elevated concentrations of levoglucosan were observed (119.7 ± 6.0 ng m −3 ), which were ∼ 4.5 times higher than those observed during non-event periods in July 2014. During the middle of July 2014, a haze episode occurred that was primarily caused by the long-range transport of emission plumes originating from urban and industrial complexes in East China. Sharp increases in SO 2− 4 concentrations (23.1 ± 2.1 µg m −3 ) were observed during this episode. The haze caused by the long-range transport of Siberian forest fire emissions was clearly identified by relatively high organic carbon (OC) / elemental carbon (EC) ratios (7.18 ± 0.2) and OC / SO 2− 4 ratios (1.31 ± 0.07) compared with those of the Chinese haze episode (OC / EC ratio: 2.4 ± 0.4; OC / SO 2− 4 ratio: 0.21 ± 0.05). Remote measurement techniques and chemical analyses of the haze plumes clearly show that the haze episode that occurred during late July 2014 was caused mainly by the long-range transport of smoke plumes emitted from Siberian forest fires.
We present a thermochemical hydrogen (TCH) gas sensor
fabricated
with Pt-decorated exfoliated graphene sheets and a tellurium nanowire-based
thermoelectric (TNTE) layer operating at room temperature in wet air.
The sensor device was able to detect 50 ppm to 3% of hydrogen gas
within several seconds (response/recovery times of 6/5.1 s at 4000
ppm of hydrogen gas) at room temperature due to the relatively high
surface area of homogeneously dispersed Pt nanocrystals (∼8
nm) decorated on graphene sheets and the excellent Seebeck coefficient
(428 μV/K) of the TNTE layer. Furthermore, it was observed that
the effect of the relative humidity on sensing properties was greatly
minimized by incorporating Pt-decorated graphene sheets. These results
indicate that our device has great potential as a low power consumption
gas sensor for IoTs.
Rare-earth-based
core–shell spring nanomagnets have been intensively studied
in the permanent magnet industry. However, the inherent agglomeration
characteristics of zero-dimensional (0-D) magnetic nanoparticles are
an issue in practical fabrication of magnetic nanocomposites due to
deterioration in exchange-coupling interactions, resulting in inferior
magnetic performance. Here, with an aim to overcome the structural
limitations, we report a new type of SmCo/FeCo core–shell nanomagnet
with a well-dispersed one-dimensional (1-D) structure prepared by
a combination of electrospinning and electroless plating processes.
An FeCo layer with a tailored thickness on nanoscale SmCo was produced
to achieve a sufficient exchange-coupling effect. The influence of
electroless plating time on the microstructure of fibers was discussed,
and comparisons were made as a function of the magnet shape. A 1-D
SmCo/FeCo spring nanomagnet having a core diameter ranging from 150
to 200 nm and a shell thickness of 15–20 nm showed a potent
exchange-coupling effect compared with its 0-D counterpart. This effectively
reduced self-aggregation and further showed a remarkable enhancement
in (BH)max (above 45.7%). We think that
this novel structure marks a new era in the exchange-spring magnet
industry and may overcome the limitations of traditional core–shell
nanomagnets.
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