Southern Regions Of China Research Articles

The characteristics of the complete chloroplast genome of Staurogyne concinnula (Hance) O. Kuntze (Acanthaceae)

Staurogyne concinnula (Hance) O. Kuntze (Acanthaceae) is an important ornamental herb mainly distributed in the southern region of China, including Fujian, Guangdong, Hainan, and Taiwan provinces. However, the complete chloroplast genome of S. concinnula, which could serve as a genetic resource for studies on its taxonomy and evolution, is poorly studied at present. In this study, we reported the complete chloroplast genome of S. concinnula that was assembled using high-throughput sequencing data. The chloroplast genome was 153,783 bp long, with a typical quadripartite structure containing a small single-copy region (SSC; 17,855 bp), a large single-copy region (LSC; 84,636 bp) and a pair of inverted repeats (IRs; each 25,646 bp). The overall GC content of the chloroplast genome was 38.04%. A total of 86 protein-coding genes (PCGs), 8 rRNA genes, and 37 tRNA genes were predicted. Phylogenetic analysis based on the combined sequences of 86 PCGs with the other 16 closely related species of Acanthaceae indicated that S. concinnula is closely related to Avicennia marina. The genomic data and finding from the phylogenetic studies of S. concinnula could provide useful information and give light to in-depth studies on the evolution pattern of the understudied species, as well as Staurogyne.

Distribution characteristics and clinical phenotype analyses of hemoglobin variants in the Z region of Central Guangxi, Southern China

ABSTRACTObjectiveTo investigate the molecular diagnosis of hemoglobin variants in Z region by Capillary electrophoresis in Central Guangxi, Southern China, and analyze their distribution and phenotypic characteristics, to provide a reference for clinical consultation and prenatal diagnosis for couples.MethodsA total of 23,709 subjects were collected for blood routine analysis, hemoglobin analysis, and common α- and β-globin gene loci in Chinese population. The hemoglobin electrophoresis components were divided into Zone 1-Zone 15 (Z1-Z15) by Capillary zone electrophoresis (CE). For samples not clearly detected by the conventional technology, Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used. Single-molecule real-time (SMRT) sequencing technology was used to analyze rare-type genes in a sample with a structural variation.ResultsTen rare hemoglobin variants distributed in Z region were detected in 23,709 samples, including Hb Cibeles, which was reported for the first time in Asia; Hb J-Broussais, Hb G-Honolulu and J-Wenchang-Wuming, they were first reported in Guangxi; 1 case of Hb Anti-Lepore Liuzhou, which was a newly discovered hemoglobin variant; hemoglobin variants Hb G-Siriraj, Hb Handsworth, Hb Q-Thailand, Hb Ube-2, Hb NewYork were also detected.ConclusionThere are a few studies on rare hemoglobin variants in Z region in Southern China. Ten rare hemoglobin variants were found in this study. The hematological phenotype and component content of hemoglobin variants are related to the occurrence of thalassemia. This study enriched the data of rare hemoglobin variants in Southern China and provided a comprehensive data basis for prenatal diagnosis of hemoglobin variants in this area.

Economic Cooperation of Krasnoyarsk Krai (Territory) with Chinese Regions at the Beginning of the XXI Century (Based on Records of the Krasnoyarsk Krai State Archive)

The article deals with the development of economic cooperation between Krasnoyarsk Krai (Territory) and the regions of China in the first decade of the XXI century. The relevance of the study is in the need to draw on the historical experience of Russia-China relations for the successful development of economic cooperation between the Russian Federation and the People's Republic of China at the present stage. Currently, China is a priority strategic partner for Russia and a key focus of its foreign policy. Problems of interregional cooperation are in the focus of the study. Krasnoyarsk Krai has been cooperating most closely in economic sphere with three provinces of Northeast China, Xinjiang Uygur Autonomous Region and Inner Mongolia Autonomous Region, developing cooperation with southern regions of China. At the beginning of the 21st century, Russia's regions developed international cooperation, building on the experience of the previous decade, but in a new historical context. The authors, for the first time ever, introduce the records that they discovered at the Krasnoyarsk Krai State Archive. These documents show the mutual interest of Russian and Chinese regions in developing cooperation in different sectors of the economy and reflect the problems that hampered the development of economic cooperation, the case of Krasnoyarsk Krai in the first decade of the XXI century.

Analysis of spatial–temporal dynamic distribution and related factors of tuberculosis in China from 2008 to 2018

Through spatial–temporal scanning statistics, the spatial–temporal dynamic distribution of pulmonary tuberculosis incidence in 31 provinces and autonomous regions of China from 2008 to 2018 is obtained, and the related factors of spatial–temporal aggregation of tuberculosis in China are analyzed to provide strong scientific basis and data support for the prevention and control of pulmonary tuberculosis. This is a retrospective study, using spatial epidemiological methods to reveal the spatial–temporal clustering distribution characteristics of China's tuberculosis epidemic from 2008 to 2018, in which cases data comes from the China Center for Disease Control and prevention. Office Excel is used for general statistical description, and the single factor correlation analysis adopts χ2 Test (or trend χ2 Inspection). Retrospective discrete Poisson distribution space time scanning statistics of SaTScan 9.6 software are used to analyze the space time dynamic distribution of tuberculosis incidence in 31 provinces, cities and autonomous regions in China from 2008 to 2018. ArcGIS 10.2 software is used to visualize the results. The global spatial autocorrelation analysis adopts Moran's I of ArcGIS Map(Monte Carlo randomization simulation times of 999) is used to analyze high-risk areas, low-risk areas and high-low risk areas. From 2008 to 2018, 10,295,212 cases of pulmonary tuberculosis were reported in China, with an average annual incidence rate of 69.29/100,000 (95% CI: (69.29 ± 9.16)/100,000). The annual GDP (gross domestic product) of each province and city showed an upward trend year by year, and the number of annual medical institutions in each province and city showed a sharp increase in 2009, and then tended to be stable; From 2008 to 2018, the national spatiotemporal scanning statistics scanned a total of 6 clusters, including 23 provinces and cities. The national high-low spatiotemporal scanning statistics of the number of pulmonary tuberculosis cases scanned a total of 2 high-risk and low-risk clusters. The high-risk cluster included 8 provinces and cities, and the low-risk cluster included 12 provinces and cities. The global autocorrelation Moran's I index of the incidence rate of pulmonary tuberculosis in all provinces and cities was greater than the expected value (E (I) = −0.0333); The correlation analysis between the average annual GDP and the number of pulmonary tuberculosis cases in each province and city from 2008 to 2018 was statistically significant. From 2008 to 2018, the spatial and temporal scanning and statistical scanning areas of tuberculosis incidence in China were mainly concentrated in the northwest and southern regions of China. There is an obvious positive spatial correlation between the annual GDP distribution of each province and city, and the aggregation degree of the development level of each province and city is increasing year by year. There is a correlation between the average annual GDP of each province and the number of tuberculosis cases in the cluster area. There is no correlation between the number of medical institutions set up in each province and city and the number of pulmonary tuberculosis cases.

Solar energy potential using GIS-based urban residential environmental data: A case study of Shenzhen, China

This study examines Shenzhen's potential for utilizing photovoltaics (PV) on buildings in terms of residential electricity consumption. Based on its geographic information system (GIS) data, typical local meteorological data, and electricity demand, the solar potential of Shenzhen has been thoroughly studied, critically analyzed, and compared with different urban morphology characteristics. Urban morphology influences the solar radiation received by individual buildings. First, four representative residential areas have been chosen. Using the 3D architectural modeling software Rhinoceros with its Grasshopper and Ladybug plug-ins, the solar potential of the areas was then evaluated. Following this, an economic analysis was carried out. Due to the high solar radiation of the rooftop areas, the results demonstrated that a combination of rooftops and high-performance facades (over 700 kWh/m2/year) produces a promising payback period. Therefore, this paper calls for action to start a large-scale program to promote and then mandate the use of renewable energy resources (RES), specifically solar, for the residential sector in the cities located in the southern region of China.

Association of ERCC1 and XPF polymorphisms with pediatric glioma susceptibility.

Association of ERCC1 and XPF polymorphisms with pediatric glioma susceptibility.

Comparison of production of bioactive components in Zanthoxylum nitidum taproots from different regions in southern China.

Zanthoxylum nitidum (Roxb.) DC is a traditional Chinese herb from southern China and its 3-4-year old roots are used in medicine. However, there is a scarcity of studies on the differences in the content of different regions of the roots, as well as comprehensive evaluations of Z. nitidum from the main areas of production in China. This study used ultra performance liquid chromatography, triple quadrupole tandem mass spectrometry, HPLC, and Fourier-transform infrared spectroscopy to detect and identify the bioactive components from different parts and eight regions of 4-year-old roots of Z. nitidum. Our results revealed that the types and quantities of compounds extracted were similar in root bark and root wood, although the amount of alkaloids in the former was substantially higher. The contents of four alkaloids in samples from Guangdong were higher than those in Guangxi Province. Meanwhile, hierarchical cluster analysis and principal component analysis showed that the samples from different regions were effectively identified and evaluated based on alkaloids and other bioactive substances. Our findings have significant implications for Z. nitidum harvesting and usage, as well as for origin identification, quality evaluation, and sensible use of Z. nitidum resources.

Molecular spectrum of α- and β-thalassemia among individuals of reproductive age in the Zhuhai region of southern China.

Thalassemia is the most common monogenic disease in South and Southeast Asia. An accurate assessment of the relative frequency and composition of thalassemia mutations is important for the design of appropriate strategies to prevent the disease. In this study, we aimed to decode the molecular characterization of thalassemia mutations in Zhuhai region of southern China. A total of 8048 individuals who were potential thalassemia carriers were enrolled. Gap-polymerase chain reaction (Gap-PCR) and reverse dot-blot (RDB) hybridization methods were employed to detect common deletional and non-deletional thalassemia mutations. Multiplex ligation dependent probe amplification (MLPA) and Sanger sequencing were used to analyze and verify rare and complex mutations. We diagnosed 3433 individuals as thalassemia carriers or patients. Of these, 2395 (69.76%) individuals with α-thalassemia harbored 13 α-globin gene mutations. The three most common α-thalassemia mutations were --SEA (60.08%), -α3.7 (20.62%) and -α4.2 (9.25%). We diagnosed 903 (26.30%) individuals with β-thalassemia and identified 20 β-globin gene mutations, of which the three most frequent were CD41/42 (-TCTT) (38.10%), IVS-II-654 (C>T) (23.69%) and TATAbox-28 (A>G) (15.18%). In addition, we identified 15 rare thalassemia variants. We also summarized the association between the thalassemia genotype and hematological parameters, which demonstrated the broad phenotypic heterogeneity caused by globin gene mutations. This is the first survey of thalassemia molecular epidemiology and hematological phenotype in Zhuhai region. It uncovered a high prevalence and complex molecular spectrum of thalassemia. These findings can be used as a basis for thalassemia diagnosis, counseling and prevention management.

Abnormal Waves Observation and Analysis of the Mechanism in the Pearl River Estuary, South China

The Pearl River Estuary is a typical estuary region in southern China, and the study of surface wave occurrence and characteristics is of great importance for shipping management, nearshore engineering, and monitoring shoreline changes and other human activities. Long-term and continuous observational data are critical for achieving a better understanding of waves. In this study, the wave measurements based on a high-precision wave gauge were analyzed and observation data over approximately two years at a sampling frequency of 2 Hz were obtained. The wave system in the Pearl River Estuary was found to deviate from the assumption of a stationary stochastic process similar to that in the open ocean, due to the effects of abnormal waves caused by human activities. Therefore, traditional distribution functions such as Rayleigh and Weibull were not suitable for accurately fitting the main wave parameters (Hs, Tp, etc.), particularly in the tail. Consequently, abnormal wave signals were extracted from all wave sets, and through the comparison and analysis of the wave spectral features, it was determined that these abnormal waves are caused by the ship wakes. The spectral characterization of these waves was performed to determine the characteristics of different ship wake processes. Ship wakes in the Pearl River Estuary are an important part of the wave system, and their wave height is significantly larger than the normal wave. Based on the spectral characteristics of ship wakes, this study proposed some news characteristics of ship wakes in the main channel of the Pearl River Estuary.

Distinct seasonality in vertical variations of tropospheric ozone over coastal regions of southern China

The surface ozone pollution is strongly coupled with ozone variations above the ground. Using sufficient airborne ozone profiles during 2012–2018, this study reveals the tropospheric ozone distributions over four cities located in coastal regions of southern China. The 7-year mean tropospheric ozone profiles in the four cities consistently show a double-maxima profile, with a local maximum at 1 km altitude and the other in the middle-to-upper troposphere. Seasonally, springtime ozone is larger than the annual mean throughout the troposphere, while ozone in summer is high in the middle-to-upper troposphere, leading to largest vertical variations among seasons. Ozone in the middle-to-upper troposphere is lower in autumn than in spring and summer. The winter ozone is characterized with a minimum in the lower troposphere, and low values in the middle-to-upper troposphere, leading to least vertical variations among seasons. We untangle the causes for these complicated vertical ozone variations using the GEOS-Chem model. The tropospheric ozone over southern China is partitioned into locally produced ozone, regionally transported native ozone, imported ozone from outside of China (foreign ozone) and natural stratospheric ozone. The results suggest that the springtime ozone abundance is due to the enhanced import of foreign and stratospheric ozone and the intensified regional transport processes of native ozone. In summer, local ozone production is enhanced and regional transport of ozone in the middle-to-upper troposphere is strengthened due to upward air motions, while such transport becomes weaker in autumn leaving low ozone in the middle-to-upper troposphere. In winter, the intensive westerly jets promote foreign and stratospheric ozone again in the middle-to-upper troposphere, but the local ozone production and regional transport are sharply reduced, resulting in low ozone near the surface. This study provides new insights into regional ozone profiles and reveals the significance of vertical ozone variations on surface ozone prevention strategy.

HCN-induced embryo arrest: passion fruit as an ecological trap for fruit flies.

Fruit flies are important economic pests of fruits, vegetables, and nuts all over the world. In this study, a permanent ecological trap, which was created by the ovicidal effect of phytogenic hydrogen cyanide (HCN) liberated from passion fruits due to oviposition by fruit flies and can be used in the pest management, were determined. Observation of fruit fly eggs in Passiflora within the passion fruit cultivation region in southern China, from Aug 2019 to Oct 2020 showed that the exotic Passiflora attracted the native fruit flies to oviposit, but the eggs could not hatch. Using classical staging to categorize embryonic development and fumigation assays, we show that oviposition by fruit fly on passion fruits, release HCN from the cyanogenic mesocarp. Exposure of the eggs to HCN causes arrest of embryonic development and finally the death of eggs. Our results reveal that the life cycle of fruit fly in Passiflora is interrupted at the egg stage. Consequently, we predict that this ecological trap may be permanent. Extensive cultivation of the Passiflora vine as a dead-end trap crop may be an effective avenue to reduce populations of fruit fly pests. © 2023 Society of Chemical Industry.

Endogenous relapse and exogenous reinfection in recurrent pulmonary tuberculosis: A retrospective study revealed by whole genome sequencing.

Tuberculosis may reoccur due to reinfection or relapse after initially successful treatment. Distinguishing the cause of TB recurrence is crucial to guide TB control and treatment. This study aimed to investigate the source of TB recurrence and risk factors related to relapse in Hunan province, a high TB burden region in southern China. A population-based retrospective study was conducted on all culture-positive TB cases in Hunan province, China from 2013 to 2020. Phenotypic drug susceptibility testing and whole-genome sequencing were used to detect drug resistance and distinguish between relapse and reinfection. Pearson chi-square test and Fisher exact test were applied to compare differences in categorical variables between relapse and reinfection. The Kaplan-Meier curve was generated in R studio (4.0.4) to describe and compare the time to recurrence between different groups. p < 0.05 was considered statistically significant. Of 36 recurrent events, 27 (75.0%, 27/36) paired isolates were caused by relapse, and reinfection accounted for 25.0% (9/36) of recurrent cases. No significant difference in characteristics was observed between relapse and reinfection (all p > 0.05). In addition, TB relapse occurs earlier in patients of Tu ethnicity compared to patients of Han ethnicity (p < 0.0001), whereas no significant differences in the time interval to relapse were noted in other groups. Moreover, 83.3% (30/36) of TB recurrence occurred within 3 years. Overall, these recurrent TB isolates were predominantly pan-susceptible strains (71.0%, 49/69), followed by DR-TB (17.4%, 12/69) and MDR-TB (11.6%, 8/69), with mutations mainly in codon 450 of the rpoB gene and codon 315 of the katG gene. 11.1% (3/27) of relapse cases had acquired new resistance during treatment, with fluoroquinolone resistance occurring most frequently (7.4%, 2/27), both with mutations in codon 94 of gyrA. Endogenous relapse is the main mechanism leading to TB recurrences in Hunan province. Given that TB recurrences can occur more than 4 years after treatment completion, it is necessary to extend the post-treatment follow-up period to achieve better management of TB patients. Moreover, the relatively high frequency of fluoroquinolone resistance in the second episode of relapse suggests that fluoroquinolones should be used with caution when treating TB cases with relapse, preferably guided by DST results.

DISTRIBUTION OF HEAVY METALS IN SOIL IN INDUSTRIAL ESTATES: A COMPARATIVE REVIEW OF SOUTH CHINA AND SIDOARJO, EAST JAVA, INDONESIA

Heavy metals, found in extremely minute particles, can create environmental contamination in various media, including soil, water, and air. The study sites were chosen in coastal regions of southern China, other industrial zones in Sidoarjo, East Java, Indonesia, and areas near significant industrial activity. This study aims to review and compare the sources and spatial distribution of heavy metals, as well as the potential health risks for the two regions of South China and Sidoarjo, Indonesia. The methodology utilized for this study is a literature review. There are parallels across the research location articles in terms of industrial soil properties.

Diversity and Distribution of Calonectria Species in Soils from Eucalyptus urophylla × E. grandis, Pinus massoniana, and Cunninghamia lanceolata Plantations in Four Provinces in Southern China.

The species of Calonectria include many notorious plant pathogens and are widely distributed around the world. Leaf blight caused by Calonectria species is considered one of the most prominent diseases in Eucalyptus plantations in China. Some Calonectria species isolated from soils in Eucalyptus plantations are highly pathogenic to inoculated Eucalyptus genotypes. In southern China, the plantation trees Cunninghamia lanceolata, Eucalyptus spp., and Pinus massoniana are always adjacently planted, especially in FuJian, GuangDong, GuangXi, and YunNan Provinces. The aim of this study was to understand the diversity and distribution of Calonectria in soils from plantations of different tree species in different geographic regions. Soil samples were collected from 12 sampling sites in Eucalyptus urophylla × E. grandis, P. massoniana, and C. lanceolata plantations in FuJian, GuangDong, GuangXi, and YunNan Provinces. Approximately 250 soil samples were collected from each sampling site, and a total of 2991 soil samples were obtained. A total of 1270 Calonectria isolates were obtained from 1270 soil samples. The 1270 isolates were identified based on DNA sequence comparisons of the partial gene regions of act, cmdA, his3, rpb2, tef1, and tub2. These isolates were identified as 11 Calonectria species: Calonectria aconidialis (69.50%), C. kyotensis (13.10%), C. hongkongensis (10.80%), C. ilicicola (2.50%), C. asiatica (2.36%), C. curvispora (0.31%), C. chinensis (0.24%), C. pacifica (0.24%), C. yunnanensis (0.16%), and C. canadiana (0.08%) in the C. kyotensis species complex and C. eucalypti (0.71%) in the C. colhounii species complex. The three dominant species, C. aconidialis, C. kyotensis, and C. hongkongensis, were widely distributed. The richness of Calonectria (percentage of soil samples that yielded Calonectria) in soils in the eastern regions (relatively humid regions) was higher than that in the western regions. The Calonectria richness of E. urophylla × E. grandis, P. massoniana, and C. lanceolata plantations decreased gradually. For each of the three dominant species, its richness in the eastern regions was generally higher than that in the western regions; the species richness was highest in E. urophylla × E. grandis plantations for C. aconidialis, while for each of C. kyotensis and C. hongkongensis, its species richness was highest in P. massoniana plantations. The genetic variation in C. aconidialis, C. kyotensis, and C. hongkongensis was more greatly affected by geographic region than by plantation tree species. This study expanded our understanding of the richness, species diversity, and distribution characteristics of Calonectria in soils from the plantations of different tree species in different geographic regions in southern China. Results in this study enhanced our understanding of the influencing characteristics of geographic region and tree species on the species and genetic diversity of soilborne fungi.

Magnesium isotopic composition of modern human teeth enamel and its implications for dietary reconstructions

Metal stable isotopic composition of dental enamel is a novel proxy for reconstructing human dietary structure. Magnesium is the second most prevalent element in teeth only after calcium. Significant isotopic fractionation of Mg isotopes during biological processes implies its great advantages in reconstructing human recipes. To evaluate the potential of the Mg isotopic composition of dental enamel in learning the human dietary structure, elemental and Mg isotopic analyses were performed on the modern human teeth from regions in northern and southern China with various dietary characteristics. Our findings reveal that southern Chinese teeth enamel has higher Mg contents and heavier Mg isotopic compositions (-0.69‰ for SN and -0.66‰ for Hangzhou) than those of their northern counterparts (−1.27‰ for Weinan and −1.33‰ for Puyang). Such discrepancy cannot be attributed to the provenance heterogeneity or individual metabolic processes. Instead, the correlations between cereal-based dietary patterns and the δ26Mg in dental enamel demonstrate that the structure of the staple diet is more responsible for the Mg isotopic signatures. Moreover, heavier Mg isotopic compositions have been observed in dental enamel of individuals with higher rice and lower wheat in the diet, indicating that Mg isotopes are a promising tracer for rebuilding individual or population plant-based dietary structures as well as distinguishing more specific species within C3 plants. These findings suggest that Mg isotopes in teeth enamel have the great potential to better identify the food composition and constrain the diet structure of ancient humans.

Parent material and altitude influence red soil acidification after converted rice paddy to upland in a hilly region of southern China

Parent material and altitude influence red soil acidification after converted rice paddy to upland in a hilly region of southern China

Research on power trade potential and power balance between Lancang-Mekong countries and southern China under long-term operation simulation

In order to further promote the interconnection development and construction of the power grids between the Lancang-Mekong countries and Southern China region and facilitate multilateral energy interaction, an assessment mechanism of the power balance and power trade potential between the two areas under long-term operation simulation is proposed. The mechanism first analyzes the energy supply structure, energy use forms, cross-border transmission capacity, and multi-area power trade potential of the power grids of the Lancang-Mekong countries and Southern China. Secondly, a power and electricity optimization model considering the long-period operation characteristics of generating units and regional interconnection transmission constraints is constructed, which can optimize the solution of a typical time-series operation scenario of 8760 h a year and improve the accuracy of regional power trade potential analysis. The results show that the Lancang-Mekong countries and the southern region of China have a significant potential for power trading, and the construction of a unified power trading market is vital for promoting the optimal allocation of power resources, achieving power balance, increasing the proportion of energy consumption, and reducing the cost of electricity consumption.

Quantitative impacts of vertical transport on the long-term trend of nocturnal ozone increase over the Pearl River Delta region during 2006–2019

Abstract. The Pearl River Delta (PRD) region in southern China has been subject to severe ozone (O3) pollution during daytime and anomalous nocturnal O3 increase (NOI) during nighttime. In this study, the spatiotemporal variation of NOI events in the PRD region from 2006 to 2019 is comprehensively analysed, and the role of vertical transport in the occurrence of NOI events is quantified based on observed surface and vertical O3 and the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) dataset. The results show that the average annual frequency of NOI events in the whole PRD region during the 14 year period is estimated to be 53 ± 16 d yr−1, with an average of 58 ± 11 µg m−3 for the nocturnal O3 peak (NOP) concentration. Low-level jets (LLJs) are the main meteorological processes triggering NOI events, explaining on average 61 % of NOI events. Annual NOI events exhibit an upward trend before 2011 (4.70 d yr−1) and a downward trend thereafter (−0.72 d yr−1), which is consistent with the annual variation of LLJs (r=0.88, p&lt;0.01). Although the contribution of convective storms (Conv) to NOI events is relatively small with an average value of 11 %, Conv-induced NOI events steadily increased at a rate of 0.26 d yr−1 during this 14 year period due to the impact of urbanisation. Seasonally, a relatively higher frequency of NOI events is observed in spring and autumn, which is consistent with the seasonal pattern of LLJs and maximum daily 8 h average (MDA8) O3. Spatially, NOI events are frequent in the eastern PRD, which agrees well with the spatial distribution of the frequency of LLJs and partially overlaps with the distribution of MDA8 O3 concentration, suggesting that vertical transport plays a more important role in NOI events than daytime O3 concentration. The Weather Research and Forecasting (WRF) model coupled with the Community Multiscale Air Quality (CMAQ) model and the observed vertical O3 profiles are further applied to illustrate the mechanisms of NOI formation caused by LLJs and Conv. The results confirm that both LLJs and Conv trigger NOI events by inducing downdrafts with the difference being that LLJs induce downdrafts by wind shear, while Conv by compensating downdrafts. Through observational and modelling analysis, this study presents the long-term (2006–2019) trends of NOI events in the PRD region and quantifies the contribution of meteorological processes for the first time, emphasising the importance of vertical transport, as well as daytime O3 concentration for the occurrence of NOI events.

Soil and water conservation measures reduce erosion but result in carbon and nitrogen accumulation of red soil in Southern China

Soil erosion is continually overlooked in the hilly red soil region of southern China, and there is a substantial lack of knowledge about the effects of soil and water conservation measures (SWCMs) on erosion prevention and soil carbon and nitrogen accumulation for the eroded sloping arable land in this region. Herein, based on a long-term experiment in the red soil hilly region in China, we investigated the effects of 17 years of SWCMs on soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon and nitrogen (MBC and MBN, respectively) as well as soil erodibility (K factor) at soil depths of 0–100 cm in the top, middle and bottom parts of the slope. The SWCMs included straw mulching (SM), downslope ridge cultivation (DC), downslope ridge cultivation + contour hedgerow planting (DCH), and contour ridge cultivation tillage (CC). A bare land treatment without any crops was used as a control (CK). We found that SWCMs increased SOC, TN, MBC, and MBN by 8–57%, 1–14%, 25–68%, and 17–35%, respectively, with greater increases in these variables in the CC and SM treatments and smaller increase in the DC treatment. Additionally, the effects of the SWCMs were greater at the top and middle of the slope than at the bottom of the slope, and the effects varied with soil depth. Moreover, the SWCMs decreased soil erodibility, with a lower K factor in the SWCMs treatments (0.018–0.049 t ha h ha−1 MJ−1 mm−1) than in the CK (0.042–0.068 t ha h ha−1 MJ−1 mm−1) and a greater decrease in the CC treatment. The effects of the SWCMs on soil erodibility mainly occurred through the regulation of SOC according to structural equation modeling. Overall, this study suggested that straw mulching and contour ridge cultivation tillage were the most effective strategies for restoring soil carbon and nitrogen and preventing soil erosion.

Prevalence of hepatitis B virus infection among pregnant women in the mountainous regions of southern China: A retrospective single‐center study

Hepatitis B virus (HBV) infection remains a major public health issue worldwide. Moreover, its prevalence varies significantly in different geographic areas of China. The current study aimed to assess the prevalence of HBV infection among Hakka pregnant women in Meizhou, a remote mountainous region in southern China. This research was performed between January 2015 and December 2020. In total, 16,727 pregnant women receiving antenatal care at Meizhou People's Hospital were included in the analysis. All pregnant women were screened for serum HBV markers. The prevalence rates of hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody positivity among the participants were 11.74% (n=1964) and 48.00% (n=8029), respectively. The overall prevalence rates of susceptibility to infection, HBV immunity, previous/occult infection, inactive HBsAg carrier, and active infection were 36.16%, 33.61%, 16.94%, 8.11%, and 2.30%, respectively. According to age distribution, the prevalence rate of HBsAg positivity elevated concomitantly with increasing age (p < 0.001). From 2015 to 2020, the prevalence rate of HBsAg positivity decreased from 14.50% to 8.19% and that of hepatitis B pre-core antigen positivity from 4.42% to 2.31%. In addition, pregnant women with HBsAg-positive status were more likely to present with gestational diabetes, thrombocytopenia, and anemia than those with HBsAg-negative status. The HBV infection rate remains high among pregnant women in the indigenous Hakka population in southern China. To prevent vertical transmission, cautious surveillance of maternal HBV infection status should be considered in Hakka pregnant women in Meizhou.