This study was designed to assess the variation of the air quality actually measured from the air pollution monitoring stations (AQMS) in three cities (Wuhan, Daegu, and Tokyo), in Asian countries ...experiencing the explosive outbreak of COVID-19, in a short period of time. In addition, we made a new attempt to calculate the reduced
(μg) at the bronchiolar (Br.) and alveolar-interstitial (AI) regions of the 10-year-old children after the city lockdown/self-reflection of each city. A comparison of the average PM
of a month before and after the lockdown (Wuhan) and self-reflection (Daegu and Tokyo) clearly shows that the PM
concentration was decreased by 29.9, 20.9, and 3.6% in Wuhan, Daegu and Tokyo, respectively. Wuhan, Daegu and Tokyo also recorded 53.2, 19.0, and 10.4% falls of NO
concentration, respectively. Wuhan, which had the largest decrease of PM
concentration due to COVID-19, also marked the largest reduced
(μg) (3660 μg at Br. and 6222 μg at AI), followed by Daegu (445 μg at Br. and 1,287 μg at AI), and Tokyo (18 μg at Br. and 52 μg at AI), over two months after the city lockdown/self-reflection. Our results suggest that the city lockdown/self-reflection had the effect of lowering the concentration of PM
, resulting in an extension of the period it took to the acute allergic airway inflammation (AAI) for the 10-year-old children.
As small-sized superconducting magnetic energy storage (SMES) system is commercially available at present, the function and effect of a small-sized SMES in an EV charging station including ...photovoltaic (PV) generation system is studied in this paper, which provides a practical application of small-sized SMES. The comparison of three quick response energy storage systems including flywheel, capacitor (super-capacitor) and SMES is also presented to clarify the features of SMES. SMES, PV generation system, and EV battery are connected to a common dc bus with corresponding converters respectively. Voltage source converter (VSC) is used for grid-connection. With characteristic of quick power response, SMES is utilized to maintain the dc bus steady. During the long-term operation of EV charging station, an energy management strategy is designed to control the energy transfer among PV units, SMES, EV battery, and power grid. The EV charging station system is modeled in MATLAB/SIMULINK and simulation tests are carried out to verify the function and performance of SMES.
Ranking among the most effective anticancer drugs, anthracyclines represent an important family of aromatic polyketides generated by type II polyketide synthases (PKSs). After formation of polyketide ...cores, the post-PKS tailoring modifications endow the scaffold with various structural diversities and biological activities. Here we demonstrate an unprecedented four-enzyme-participated hydroxyl regioisomerization process involved in the biosynthesis of kosinostatin. First, KstA15 and KstA16 function together to catalyze a cryptic hydroxylation of the 4-hydroxyl-anthraquinone core, yielding a 1,4-dihydroxyl product, which undergoes a chemically challenging asymmetric reduction-dearomatization subsequently acted by KstA11; then, KstA10 catalyzes a region-specific reduction concomitant with dehydration to afford the 1-hydroxyl anthraquinone. Remarkably, the shunt product identifications of both hydroxylation and reduction-dehydration reactions, the crystal structure of KstA11 with bound substrate and cofactor, and isotope incorporation experiments reveal mechanistic insights into the redox dearomatization and rearomatization steps. These findings provide a distinguished tailoring paradigm for type II PKS engineering.
This study aims to assess the particulate matter (PM
1
, PM
2.5
, PM
10
) and black carbon (BC) in the Korea Train eXpress (KTX) cabin during train running, and the personal exposure of PM
2.5
for ...the female/male passengers who use the KTX 20 days a month to commute. Intensive measurements were made on the day when the outside ambient PM concentration was much higher than usual. To compare with the PM concentration in the subway cabin, a measurement was also performed in some sections of the Seoul Metro subway (from Namyoung Station (hereafter referred to as the “Sta.”) to Jonggak Sta.). The amount of PM
2.5
exposure
was calculated for the male/female passengers who regularly board the KTX. The
, which is the amount of PM
2.5
exposure when moving by car in the same section, was also calculated. The PM concentration in the KTX cabin elevated and fallen off at train staying and train running, respectively. The PM
2.5
concentrations inside KTX cabin at the stop station exhibited a remarkable positive correlation with those of outdoor. Compared to the PM concentration measured in the cabin of Seoul Metro subway, PM
1
, PM
2.5
, and PM
10
in the KTX passenger cabin were 74.9%, 73.3%, and 62.7% of those in the cabin of Seoul Metro subway, respectively. The PM
2.5
exposure amount (exposure PM
2.5
(μg)) when moving the same section using the KTX and passenger cars was calculated, and as a result, the exposure PM
2.5
(μg) for both male and female were 5.7 times lower in the KTX than that in car. The mapping result of BC concentration drawn on the KTX line from Iksan Sta. to Gwang-myeong Sta. shows that it fluctuated greatly for each service section or stop station.
A thick foggy weather and worst visibility in Fukuoka, Japan and Busan, South Korea occurred from the late July to early August 2020 due to the Nishinoshima volcanic eruption. In this study, an ...intensive measurement was made to clarify the chemical nature of the ambient particulate matter (PM) and rain water collected in Fukuoka and Busan during the Nishinoshima volcanic eruption (episode period) and non-eruption (non-episode period). In this study, one week after volcanic eruption, which recorded the usual PM concentration, was defined as the non-episode period. Compared to non-episode period, the PM
2.5
concentration during the episode period increased 4.32 times in Busan and 6.03 times in Fukuoka. The sulfur and chlorine concentrations in the total suspended particles (TSP) and rainwater of episode period were particularly higher than those of non-episode period. The sulfate concentration in PM
2.5
was 1.81 and 27.98 µg/m
3
in non-episode and episode periods, respectively. The sulfate concentration during the episode period accounted for 55.4% of PM
2.5
(50.45 µg/m
3
). Strong correlation between trace elements in TSP and those in rainwater during the episode period indicates that the volcanic ashes could be incorporated into raindrops.
Object
In the present study, we carried out a case study on the hour variation of chemical compositions in PM
2.5
collected in Gwangju, South Korea, during the high loading PM
2.5
period. We also ...developed the advanced DALYs that can be used as a more practical health-impact assessment index of PM
2.5
.
Methods
Particle sampling and simultaneous determination of its chemical compositions were taken place on the roof (13.5 m) of the Honam area air pollution intensive monitoring site (35.15°N; 126.81°E). In this study, we developed a method for calculating
DALYs
PM
/
Deposition
PM2.5
(g) by age as a new health impact assessment index of PM
2.5
. For calculating the
DALYs
PM
/
Deposition
PM2.5
(g) at first, the lifetime
Deposition
PM2.5
(g) was calculated, and then the
DALYs
PM
/
Deposition
PM2.5
(g) was calculated by dividing the
DALYs
PM
by
∑
i
=
0
Death
D
e
p
o
s
i
t
i
o
n
P
M
2.5
i
g
For the calculation of the lifetime
Deposition
PM2.5
(g), the average PM
2.5
concentration (23 µg/m
3
) in Gwangju in 2016 28 was applied.
Results
The concentrations of Pb, Cr, Mn, As, and Cd in PM
2.5
on the event day were 18.1, 7.6, 1.9, 7.6 and 2.0 times higher than those of non-event day, respectively. Pb concentration accounted for 70.6% of the total concentration of 5-hazardous heavy metals and it ranged from 35 to 374 ng/m
3
. The deposition amount of PM
2.5
at A.I. for 10-year-old children and adults varied greatly depending on their behavior patterns on both event and non-event days. It was 3.1 times higher on event day than on non-event day.
Conclusion
The concentrations of harmful heavy metals on the event day were 1.9–18.1 times higher than those on non-event day. The newly developed the
DALYs
PM
/
Deposition
PM2.5
(g) in this study can be used as a more practical health impact assessment index of PM
2.5
than conventional
DALYs
.
The concerns about the reliability of SMES have always been the obstacle to the practical application of SMES. In this paper, a fuzzy logic-based operating current regulation strategy, aiming at ...improving the reliability of SMES, has been proposed. In this control strategy, the current of SMES will be maintained in the best range during normal operation. When the temperature of magnet sharply rises after deep power exchange, the current of SMES will be down regulated to reduce ac loss and obtain more thermal stability margin. An application of SMES in microgrid is taken as an example to verify the control strategy. Simulation results based on MATLAB/Simulink demonstrate the feasibility and correctness of the control strategy.
Straw checkerboard barrier (SCB) array is one of the most effective and widely used measures for antidesertification projects. The efficiency and durability of SCB are greatly influenced by the ...features of wind field and sand particle motion. Unfortunately, very few studies have explored the characteristics of turbulent flow and the internal erosional form inside the barrier cell, because of the complexity of turbulent flow and the sand particle motion around the surface of SCBs. In this paper, we simulated the wind‐sand flow around SCBs using 3‐D hybrid Reynolds‐averaged Navier‐Stokes/large eddy simulation method and Lagrangian particle tracing method to analyze the characteristics of turbulent flow, particle motion, and internal erosional form of SCBs. The results show that the vast majority of particles fall into SCB cells from their middle and posterior parts when wind‐sand flow passes SCBs, due to the impact of gravity and subsidence flow. It indicates that SCBs could effectively prevent sand flow‐induced hazards. The turbulent flow in SCBs has great instantaneous pulse velocity, resulting in retransfer of sand particles in SCBs. Analysis of the mean flow field in SCB found one huge streamwise vortex that filled the SCB cells and two spanwise vortexes in the back of SCB cells. These vortexes will drive particles inside SCBs to move toward the front and side walls, making the erosional form of SCB cells low in the middle and high near all the sides.
Plain Language Summary
Straw checkerboard barrier (SCB) is the most representative anti‐desertification measure and plays a significant role in anti‐desertification projects. We studied the wind‐sand flow around SCBs using computational method and analyzed the characteristics of turbulent flow, particle motion and internal erosional form of SCBs. Based on the simulation results, the weakness of current SCBs can be identified. Therefore, this research is of significance in improving artificial sand control measures designed to help combat desertification control.
Key Points
Turbulent aeolian sand movement over 3‐D straw checkerboard barriers is simulated
High instantaneous wind velocity and shear stress caused by turbulence enhances particle retransfer inside the barrier cell
The wind vortex is the main cause of internal morphology of the straw checkerboard
Bangong Lake is a narrow and long lake in the arid region of the plateau in northern Tibet. The salinity of the east of the lake is different from that the west, resulting in differences in the ...natural environment and human living conditions on each side. Watershed hydrochemical analysis and spatial statistical analysis can help to understand regional hydrochemical evolution and water quality evaluation. In this study, the hydrochemical characteristics of surface water (glacier, river, and lake) and groundwater in the Bangong Co Lake Watershed were investigated to reveal the relationships between various water bodies. The drinking water quality index (DWQI) and USSL classification were applied to assess groundwater quality suitability for agricultural and drinking purposes. The hydrochemical characteristics show the differences among water bodies and their spatial distribution. The analyzed groundwater and surface water samples, such as river water and glaciers, were mainly Ca-HCO3-type and the lake water was mainly categorized as Na-Cl-type with some Na-HCO3-Cl type. The lake water’s chemical components are mainly affected by evaporative karst decomposition. The main mineralization process of groundwater and river water was related to the dissolution of reservoir minerals, such as dolomite and calcite, as well as halite. The drinking water quality index (DWQI) indicates that 79% of the groundwater samples in the study area were of good enough quality for drinking. In terms of irrigation water quality, the electrical conductivity (EC), calculated sodium adsorption ratio (SAR), and magnesium hazardous ratio (MHR) showed that more than 13% of the total samples were not suitable for irrigation. However, the USSL classification indicated that glacier and river water are relatively suitable for irrigation. Additionally, some groundwater and lake water has very high alkalinity or salinity, which is alarming when considering them for irrigation.
Gas-phase NH
3
is one of the significant contributors to secondary aerosol formation in the atmosphere, and it is a crucial consideration in any strategy aiming to reduce PM
2.5
emissions. This study ...aimed to investigate the spatial distributions of NH
3
in verity source areas in Republic of Korea using passive samplers. NH
3
concentrations were observed at 45 locations over a period of approximately 35 weeks, from June 2022 to February 2023. As a result, NH
3
concentration was found to be more affected by local sources rather than long-distance influx from outside. The average concentration of NH
3
observed in 7 source areas excluding the background area was all less than 20.91 ppb, except for livestock sources. These results suggest that atmospheric NH
3
concentrations are significantly influenced from livestock sources. In addition, in major cities, the need for NH
3
management was confirmed to be more focused on emissions from automobiles and industrial complexes than emissions from livestock and farmland. Moreover, even for the same source, NH
3
concentrations varied depending on the type of livestock species, breeding methods and scale, products produced, crops cultivated, and vehicle traffic volume. These findings indicate the importance of considering factors such as breeding methods and manure treatment practices in emission factors, and it is expected that the results can be used as basic data for NH
3
emission estimation and management.
Graphical Abstract
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