[Atmospheric Ozone Concentration Prediction in Nanjing Based on LightGBM].

Based on the air quality data and conventional meteorological data of the Nanjing Region from January 2015 to December 2016, to analyze the characteristics of O3 concentration changes in the Nanjing Region, a light gradient boosting machine (LightGBM) model was established to predict O3 concentration. The model was compared with three machine learning methods that are commonly used in air quality prediction, including support vector machine, recurrent neural network, and random forest methods, to verify its effectiveness and feasibility. Finally, the performance of the prediction model was analyzed under different meteorological conditions. The results showed that the variation in O3 concentration in Nanjing had significant seasonal differences and was affected by a combination of its pre-concentration, meteorological factors, and other air pollutant concentrations. The LightGBM model predicted the ground-level O3 concentration in the Nanjing area more precisely to a large extent (R2=0.92), and the model outperformed other models in prediction accuracy and computational efficiency. In particular, the model showed a significantly higher prediction accuracy and stability than that of other models under a high-temperature condition that was more likely prone to ozone pollution. The LightGBM model was characterized by its high prediction accuracy, good stability, satisfactory generalization ability, and short operation time, which broaden its application prospect in O3 concentration prediction.

[Characteristics and Health Risk Assessment of BTESX in the Northern Suburbs of Nanjing].

AMA GC5000BTX was used to monitor the mixing ratio of benzene, toluene, ethylbenzene, m,p-xylene, o-xylene, and styrene (BTESX) in the atmosphere of the northern suburb of Nanjing from January 2014 to December 2016. The temporal variation characteristics of BTESX and the influence of meteorological elements on it were analyzed, and the characteristic ratio method (T/B) was used to qualitatively analyze the source of BTESX. Finally, the human exposure analysis and evaluation method of EPA was used to evaluate the health risk of BTESX. The results showed that during the observation period, the average mixing ratio of BTESX was (7.28±6.63)×10-9, and the mixing ratio of benzene was the highest at (2.45±3.91)×10-9. The mixing ratio of other species from large to small was toluene>ethylbenzene>m,p-xylene>o-xylene>styrene, which were (2.41±2.61)×10-9, (1.37±1.28)×10-9, (0.51±0.48)×10-9, (0.3±0.36)×10-9, and (0.22±0.42)×10-9, respectively. Due to the existence of stable aromatic sources, the monthly and seasonal variation in BTESX mixing ratio was not as obvious as that of other species (NOx, CO, SO2, PM2.5, etc.). The weekend effect of BTESX and other pollutants was not significant. The mixing ratio of BTESX was largely affected by the short distance transportation of chemical enterprises and traffic trunk roads in the northeast, resulting in a large mixing ratio of BTESX in the northeast. The mixing ratio of BTESX was jointly affected by relative humidity and temperature, and its high value area was mainly located in the range of 30%-70% relative humidity. In this range of relative humidity, the high value range of BTESX volume fraction increased with the elevation of temperature. The HI (hazard index) of BTESX in different seasons was within the safety range recognized by EPA, whereas the R (carcinogenic risk of benzene) value was higher than the safety threshold specified by EPA. At the same time, the HI and R values were higher in summer, to which great attention should be paid.

DEAD-Box RNA Helicase DDX47 Maintains Midgut Homeostasis in Locusta migratoria.

Tissue homeostasis is critical for maintaining organ shape, size, and function. The condition is regulated by the balance between the generation of new cells and the loss of senescent cells, and it involves many factors and mechanisms. The midgut, an important part of the intestinal tract, is responsible for digestion and nutrient absorption in insects. LmDDX47, the ortholog of DEAD-box helicase 47 from Locusta migratoria, is indispensable for sustaining a normal midgut in the nymphs. However, the underlying cellular and molecular mechanisms remain to be elucidated. In this study, LmDDX47 knockdown resulted in atrophy of the midgut and gastric cecum in both nymph and adult locusts. After LmDDX47 knockdown, the number of regenerative and columnar cells in the midgut was significantly reduced, and cell death was induced in columnar tissue. LmDDX47 was localized to the nucleolus; this was consistent with the reduction in 18S rRNA synthesis in the LmDDX47 knockdown group. In addition, the acetylation and crotonylation levels of midgut proteins were significantly increased. Therefore, LmDDX47 could be a key regulator of midgut homeostasis, regulating 18S rRNA synthesis as well as protein acetylation and crotonylation in the migratory locust.

[Source Analysis of Volatile Organic Compounds in the Nanjing Industrial Area and Evaluation of Their Contribution to Ozone].

Ambient volatile organic compounds (VOCs) were continuously measured during the high ozone (O3) periods from May 1 to May 31 and June 1 to July 16, 2015 at an industrial area in the north suburb of Nanjing. A positive matrix factorization (PMF) model and an observation-based model (OBM) were combined for the first time to investigate the contributions of VOC sources and species to local photochemical O3 formation. The average VOC concentrations in 2014 and 2015 were (36.47±33.44)×10-9 and (34.69±34.08)×10-9, respectively. The VOC sources identified by the PMF model for 2014 and 2015 belonged to 7 source categories, including vehicular emissions, liquefied petroleum gas usage, biogenic emissions, furniture manufacturing industry, chemical industry, chemical coating industry, and chemical materials industry emission sources. The OBM was modified to assess the O3 precursors' relationships. Generally, photochemical O3 production was VOC limited, with positive relative incremental reactivity (RIR) values for VOC species and a negative RIR value for NO. It can be seen that alkenes (1.20-1.79) and aromatics (1.42-1.48) presented higher RIR values and controlling O3 would be the most effective when the VOC emissions from alkenes were reduced by 80%. Vehicle emissions (1.01-1.11), LPG (0.74-0.82), biogenic emissions (0.34-0.42), and furniture manufacturing industry (0.32-0.49) sources were the top four VOC sources making significant contributions to photochemical O3 formation, which suggests that controlling vehicle emissions, biogenic emissions, LPG, and furniture manufacturing industry sources should be the most effective strategy to reduce photochemical O3 formation.

[Variation Characteristics and Health Risk Assessment of BTEX in the Atmosphere of Northern Suburb of Nanjing].

BTEX concentrations were determined by GC5000 online gas chromatography in the atmosphere of the north suburb of Nanjing in March 2013 to February 2014, using the EPA human exposure analysis evaluation method for benzene series compounds of volatile organic compounds (VOCs) in health risk assessment. The results showed that the total amount of BTEX showed the variation characteristics of spring > winter > autumn > summer. BTEX concentration was higher in the periods of 07:00-10:00 and 17:00-20:00, and the lowest was detected between 13:00-15:00; At the weekend, the concentration of BTEX was higher than on the working day. The sources of BTEX included traffic sources, industrial sources and solvent evaporation. The HQ of BTEX in all four seasons showed the order of benzene > xylene > ethylbenzene > toluene, and the HQ risk values were within the safety range in all analysis periods. The distribution of R value was winter > autumn > spring > summer, and R was higher than the safety threshold for all the analyses, indicating the existence of carcinogenic risk.

[Source Apportionment of Volatile Organic Compounds and Health Assessment of Benzene Series in Northern Suburb of Nanjing in Winter].

Volatile organic compounds (VOCs) in the atmosphere of the north suburb of Nanjing in December 2015 were determined by GC5000 online gas chromatography,and the main composition and characteristics of VOCs were analyzed by using the PMF receptor model sources of VOCs parsing.The United States Environmental Protection Agency (EPA) human exposure analysis and evaluation method in the United States were used to evaluate Human health risk of benzene series.The results showed that there were 6 sources in the PMF mode.Natural gas leakage accounted for 32.05%,automobile exhaust accounted for 18.99%,solvent use 13.67%,industrial emissions 2 13.20%,gasoline volatile 11.72%,and industrial emissions 1(chemical type)10.36%.The high value areas of the emission source were in accordance with the location of pollution sources surrounding the observation point.The B/T ratio was 0.74,which was at a relatively high level.The noncarcinogenic risk hazard quotient value HQ at 06:00 reached the highest value.HQ risk values were within the safe range specified by EPA.HQ of each source was as follows:automobile exhaust emissions 20.67×10-2,solvent use 6.97×10-2,natural gas leakage 6.34×10-2.In the carcinogenic risk of benzene,automobile exhaust emissions was 4.11×10-6,and natural gas leakage was 1.09×10-6,both were higher than the EPA specified safety threshold.

[Modeled Deposition of Fine Particles in Human Airway in Northern Suburb of Nanjing].

The particles number concentrations were determined by Wide-range Particle Spectrometer (WPS) in northern suburb of Nanjing in January and April 2015. The information of size distributions was applied in the multiple-path particle dosimetry model (MPPD) v.3.04 to quantify deposition fractions (DF) and number concentration (NC) depositions of fine particles in different regions of human airway, at different air quality levels, at rest and exercise. DF of nucleation mode and Aitken mode at rest and exercise were similar, while DF of accumulation mode at exercise was 2.49 times of that at rest. DF of nucleation mode and Aitken mode in pulmonary (PUL) was the highest, about 48.17% of total deposition fractions (TDF) at rest and 54.23% of TDF at exercise. DF of accumulation mode in head was the highest, about 41.23% of TDF at rest and 80.47% of TDF at exercise. The particle NC deposition in human airway in winter was lower than that in spring, and the total NC deposition in 3 regions was in the order of PUL > tracheobronchial(TB) > head. Compared with resting, nucleation mode deposition in PUL and accumulation mode deposition in TB and head increased at exercise. The worse the air quality, the higher the deposition growth rate of exercising to resting in head. DF difference among regions was mainly due to the different physiological parameters, while NC deposition difference was mainly due to the different particle NC in the local environment.

[Characteristic Study on the "Weekend Effect" of Atmospheric O3 in Northern Suburb of Nanjing].

The data of ozone (O3) and its precursors (NOx, CO, VOCs) observed at northern suburb of Nanjing from December 01, 2013 to November 30, 2014 were used to analyze the difference of pollutant concentrations on weekends and weekdays, and its causes. The results showed that there was an obvious "Weekend Effect" in northern suburb of Nanjing. The mass concentrations of O3 on weekdays were higher than those on weekends, whereas mass concentrations of its precursors were higher on the weekends; The average mass concentrations of O3 were 19.84 µg·m-3, 53.45 µg·m-3, 57.17 µg·m-3, and 40.43 µg·m-3 in winter, spring, summer, and autumn respectively. Compared with other seasons, "Weekend Effect " was more distinct in spring. The value of NO2/NO was 4.81% higher on weekdays (3.63) than on weekends (3.46). The longer cumulative time and higher accumulation rate of O3, and the stronger atmospheric oxidation capacity on weekdays were responsible for the higher O3 mass concentrations on weekdays. The correlation coefficients of the mass concentrations of O3 with VOCs, NOx, NO, and NO2 were higher on weekdays than on weekends.

[Distribution Characteristics of Water Soluble Ions Under Different Weather Conditions During the Youth Olympic Games in Nanjing].

To study the variation characteristics of water soluble ions during youth Olympic Games, PM2.5 and water soluble ions were observed by using the beta dust instrument, Anderson 9th sampler and IC type ion chromatography analyzer from August 6 to September 4, 2014. The observations were divided into three types of weather, sunny, rainy and cloudy. The average concentrations of PM2.5 under different weather conditions were sunny > cloudy > rainy days. The concentrations of water soluble ions in PM1.1, PM1.1-2.1 and PM2.1-10 were also sunny > cloudy > rainy days, and the obliterate of fine particles by precipitation process was more obvious. The spectra of Ca2+ and Mg2+ were bimodal. The scavenging effects of SO42- and NH4+ in range of 0.65-1.1 µm were stronger. The ratio of NO3-/SO42- under different weather conditions was less than 1, and the ratio of NO3-/SO42- in rainy and cloudy days was higher than that in sunny days. The values of SOR and NOR in the three kinds of weather conditions were more than 0.1, SO2 and NO2 had different degrees of transformation, there was more secondary pollutant in the atmosphere.

[Identification and Comparison of Constituents of Different Processed Products of Ligubtrum lucidum Fruit by HPLC Fingerprint].

OBJECTIVE: To identify and compare the constituents in different processed products of Ligubtrum lucidum fruit by HPLC fingerprint, in order to study the changes of chemical constituents before and after processing. METHODS: HPLC analysis was carried outwith the mobile phase of acetonitrile and 0.1% formic acid in a gradient elution mode. The number of HPLC fingerprint chromatographic peaks and peak area changes in two processed products and the crude product under 240 nm and 280 nm were compared. Then the obtained fingerprint chromatographic peaks were confirmed according to the the standard references. RESULTS: 40 chromatographic peaks were detected from Ligustrum lucidum fruit, of which 18 chromatographic peaks were confirmed, including eleven iridoids, five phenethyl alcohols, one flavonoid and one aldehyde. 38 chromatographic peaks were detected from both steaming with wine product and the steamed product, of which 15 chromatographic peaks were confirmed, including seven iridoids, five phenethyl alcohols, one flavonoid, one aldehyde and one organic acid. There was a significant difference of fingerprint among crude Ligustrum lucidum fruit and its two processed products, but little difference between steaming with wine product and the steamed product. CONCLUSION: HPLC fingerprint of the steaming with wine product and the steamed product of Ligustrum lucidum fruit are similar while the changes on chemical composition and the content in steaming with wine product and steamed product of Ligustrum lucidum fruit are remarkable.