Dynamic Microcirculation Characteristics of Plantar Skin Under Metatarsal Head of Human Foot in Response to Life-Like Pressure Stimulus.

OBJECTIVE: Diabetic foot ulcer (DFU) is a severe complication with high mortality. High plantar pressure and poor microcirculation are considered main causes of DFU. The specific aims were to provide a novel technique for real-time measurement of plantar skin blood flow (SBF) under walking-like pressure stimulus and delineate the first plantar metatarsal head dynamic microcirculation characteristics because of life-like loading conditions in healthy individuals. METHODS: Twenty young healthy participants (14 male and 6 female) were recruited. The baseline (i.e., unloaded) SBF of soft tissue under the first metatarsal head were measured using laser Doppler flowmetry (LDF). A custom-made machine was utilized to replicate daily walking pressure exertion for 5 min. The exerted plantar force was adjusted from 10 N (127.3 kPa) to 40 N (509.3 kPa) at an increase of 5 N (63.7 kPa). Real-time SBF was acquired using the LDF. After each pressure exertion, postload SBF was measured for comparative purposes. Statistical analysis was performed using the R software. RESULTS: All levels of immediate-load and postload SBF increased significantly compared with baseline values. As the exerted load increased, the postload and immediate-load SBF tended to increase until the exerted load reached 35 N (445.6 kPa). However, in immediate-load data, the increasing trend tended to level off as the exerted pressure increased from 15 N (191.0 kPa) to 25 N (318.3 kPa). For postload and immediate-load SBF, they both peaked at 35 N (445.6 kPa). However, when the exerted force exceeds 35 N (445.6 kPa), both the immediate-load and postload SBF values started to decrease. CONCLUSIONS: Our study offered a novel real-time plantar soft tissue microcirculation measurement technique under dynamic conditions. For the first metatarsal head of healthy people, 20 N (254.6 kPa)-plantar pressure has a fair microcirculation stimulus compared with higher pressure. There might be a pressure threshold at 35 N (445.6 kPa) for the first metatarsal head, and soft tissue microcirculation may decrease when local pressure exceeds it.

Mitochondria-derived methylmalonic acid aggravates ischemia-reperfusion injury by activating reactive oxygen species-dependent ferroptosis.

Ferroptosis is a regulatory cell death process pivotal in myocardial ischemia-reperfusion (I/R) injury. However, the precise mechanism underlying myocardial ferroptosis remains less known. In this study, we investigated the pathophysiological mechanisms of methylmalonic acid (MMA) associated with ferroptosis activation in cardiomyocytes after I/R. We found an increase level of MMA in patients with acute myocardial injury after reperfusion and AC16 cells under hypoxia/reoxygenation (H/R) condition. MMA treatment was found to be associated with excessive oxidative stress in cardiomyocytes, leading to ferroptosis-related myocardial injury. In mice with I/R injury, MMA treatment aggravated myocardial oxidative stress and ferroptosis, which amplified the myocardial infarct size and cardiac dysfunction. Mechanistically, MMA promoted NOX2/4 expression to increase reactive oxygen species (ROS) production in cardiomyocytes, aggravating myocardial injury. Notably, the increased ROS further activated ferroptosis by inhibiting solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) expression. In addition, MMA decreased the ectopic nuclear distribution of nuclear factor E2-related factor 2 (NRF2) by increasing the interaction between NRF2 and kelch-like ECH-associated protein 1 (KEAP1). This impeded the activation of GPX4/SLC7A11, downstream of NRF2, activating ferroptosis and aggravating myocardial cell injury. Collectively, our study indicates that MMA activates oxidative stress and ROS generation, which induces ferroptosis to exacerbate cardiomyocyte injury in an I/R model. These findings may provide a new perspective for the clinical treatment of I/R injury and warrant further investigation.

Electrochemical Radical Retro-Allylation of Homoallylic Alcohols with Sulfonyl Hydrazides.

We report herein the first examples of electrochemical radical retro-allylation of homoallylic alcohols via the cleavage of the C(sp3)-C(sp3) bond. In this reaction, a variety of sulfonyl hydrazides were employed as the environmentally friendly radical sources via an electrochemical dehydrazination with the release of N2 and H2 as the byproducts, leading to sulfonyl allylic compounds in moderate to good yields. The reaction features metal- and base-free reaction conditions, broad functional group tolerance, and a broad substrate scope.

Selective N-functionalization of Arylhydrazines with Primary Alcohols and Acids under PPh3/DDQ System.

We present a PPh3/DDQ-mediated regiospecific selective N-functionalization of arylhydrazines with primary benzylic alcohols and aryl carboxylic acids for the synthesis of N1-benzyl arylhydrazines and N2-acyl arylhydrazines, respectively. This metal- and base-free approach features very short reaction times (about 10 min), broad substrate scope, good functional group tolerance, and mild reaction conditions. Furthermore, N1-benzlated products have also been successfully applied to the concise synthesis of N-substituted indoles and anticancer drug MDM2 inhibitor.

Differences of soil carbon pools and crop growth across different typical agricultural fields in China: The role of geochemistry and climate change.

Carbon storage and the aboveground biomass of farmland provide practical significance for understanding global changes and ensuring food production and quality. Based on soil carbon storage, aboveground biomass, climate, geochemistry, and other data from 19 farmland ecological stations in China, we analysed the distribution characteristics of farmland carbon storage in topsoil and aboveground biomass. We notably revealed the response direction and degree of climate and geochemical factors to farmland carbon storage in topsoil and aboveground biomass. The results indicated that the average carbon stocks of farmland in different regions ranged from 0.28 to 7.91 kg m-2, the average fresh weight of the aboveground biomass (FAB) ranged from 1370.64 to 5997.28 g m-2, and the average dry weight of the aboveground biomass (DAB) ranged from 119.95 to 852.35 g m-2. The least angle regression (LARS) and the best subsection selection regression (BSS) showed that evapotranspiration and extreme low temperatures were significant climatic factors affecting carbon sequestration and aboveground biomass on long-time scales. The linear mixed-effects model (LMM) further showed that AN and AP had significant long-term effects on carbon sequestration and aboveground biomass (p < 0.05), with AN having the highest contribution to SOC%, FAB, and DAB. The structural equation model (SEM) showed that carbon sequestration and aboveground biomass in agricultural fields were significantly positively correlated (p < 0.05). Moreover, the climate had a less direct contribution to carbon sequestration and above-ground biomass compared to geochemistry (PCc < 0.1

Endobronchial Ultrasound-Guided Transbronchial Mediastinal Cryobiopsy versus Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration for Mediastinal Disorders: A Meta-Analysis.

INTRODUCTION: Endobronchial ultrasound-guided transbronchial mediastinal cryobiopsy (EBUS-TMC), a novel technique, has been reported to improve the diagnostic value of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) for mediastinal lesions in recent studies. Current literature suggests that this procedure has greater diagnostic efficacy compared to conventional EBUS-TBNA. This systematic review and meta-analysis aimed to evaluate the diagnostic yield and complications associated with EBUS-TMC in comparison to EBUS-TBNA, thereby exploring the potential of this novel technique in enhancing the diagnostic utility for mediastinal lesions. METHODS: A comprehensive literature review was conducted by searching the PubMed, Embase, and Google Scholar databases for articles published from inception to December 31, 2023. The objective of this review was to evaluate the utilization of EBUS-TMC in diagnosing mediastinal disease, while also assessing the quality of each study using the QUADAS-2 tool. The diagnostic yield estimates were subjected to a meta-analysis utilizing inverse variance weighting. Furthermore, a comprehensive analysis of the complications associated with this procedure was performed. RESULTS: The meta-analysis included 10 studies involving a total of 538 patients. The findings of the meta-analysis demonstrated that EBUS-TMC yielded an overall diagnostic rate of 89.59% (482/538), while EBUS-TBNA yielded a rate of 77.13% (415/538). The calculated inverse variance-weighted odds ratio was 2.63 (95% confidence interval, 1.86-3.72; p < 0.0001), and I2 value was 11%, indicating a statistically significant difference between the two techniques. The associated complications consisted of pneumothorax, pneumomediastinum, mediastinitis, and bleeding, with an incidence of 0.74% (4/538), 0.37% (2/538), 0.0% (0/538), and 1.12% (6/538), respectively. Moreover, the funnel plot displayed no discernible publication bias. Further subgroup analysis revealed a notable improvement in the diagnosis value for lymphoma (86.36% vs. 27.27%, p = 0.0006) and benign disorder (87.62% vs. 60.00%, p < 0.0001). CONCLUSION: This review of the current available studies indicated that EBUS-TMC enhanced overall diagnostic yields compared to EBUS-TBNA, particularly for diagnosing benign disease and lymphoma. This procedure was not associated with any serious complications.

Effects of soil properties and land use patterns on the distribution of microplastics: A case study in southwest China.

Microplastic pollution in the soil environment is of great concern. However, the current research on microplastics (MPs) in Southwest China mainly focuses on their distribution characteristics and sources in soil, making the understanding of the soil properties and land use patterns influencing soil MPs insufficient. In this study, the abundance and distribution characteristics of MPs in the soil of different land use patterns in Guizhou Province were determined. The results revealed that the average abundance of MPs in soils was 2936 items/kg, ranging from 780 to 9420 items/kg. The MPs were mainly small particle size (0-0.5 mm), granular, and black, accounting for 87.5%, 36.6%, and 82.2%, respectively. The most common polymer types of MPs were polypropylene, polyethylene terephthalate, and polyethylene, which accounted for 20.4%, 16.8%, and 16.4%, respectively. As soil bulk density increased, microplastic abundance and small particle size decreased. Soil microplastic abundance slightly decreased with increasing soil porosity. The abundance of MPs increased with the increase in soil pH, but no significant correlation was observed between soil organic matter content and microplastic abundance. pH was the major factor that affected the microplastic distribution, which accounted for 32.5%. This study provides insight into the distribution and influencing factors of soil MPs and also provides a theoretical basis for subsequent research on soil microplastic pollution.

Access to Saturated Oxygen Heterocycles and Lactones via Electrochemical Sulfonylative Oxycyclization of Alkenes with Sulfonyl Hydrazides.

A facile electrochemical sulfonylative cycloetherification of linear unsaturated alcohols with sulfonyl hydrazides under mild conditions has been accomplished. This catalyst- and oxidant-free protocol proceeds via electro-oxidation, followed by radical addition, as well as an intramolecular oxygen nucleophilic process. This methodology is compatible with a broad substrate scope and good functional group compatibility, which provides a valuable and convenient synthetic tool for the synthesis of saturated five-, six-, seven-, and eight-membered ring oxygen heterocycles. Furthermore, sulfonylative cycloesterification of linear unsaturated acids toward the lactone products has also been established under this electrochemical system. In addition, control experiments indicated that the N-H bonds of the sulfonyl hydrazide molecule are non-essential.

Inhibition of Spartina alterniflora growth alters soil bacteria and their regulation of carbon metabolism.

The state of growth of invasive species has a significant impact on the microbial regulation of the soil carbon (C) cycle. This study focused on the growth of Spartina alterniflora treated with imazapyr in the Tiaozini wetland of Jiangsu Province, China. The changes in soil bacterial structure, bacterial C metabolic activity, soil C, and regulation mechanism of soil C metabolic activity by biotic and abiotic factors were investigated. The results showed that soil bacterial diversity eventually decreased significantly (p < 0.05) along with significant changes in microbial structure (p < 0.05). Significant changes in soil physicochemical properties due to S. alterniflora growth inhibition were the key factors affecting the changes in the soil bacterial taxa composition (p < 0.05). Abiotic factors showed a greater effect on metabolic activities related to C fixation and biosynthesis of bacterial taxa than biotic factors (self-regulation). Additionally, bacterial taxa regulated soil C emission and degradation to a greater extent than abiotic factors. This study provides important information for understanding the regulators of C cycling in coastal wetland soil during the control of S. alterniflora invasion by imazapyr; moreover, it provides a scientific basis for the government to establish a prevention and control policy for S. alterniflora invasion. Understanding the complex interplay between abiotic and biotic factors is essential for developing effective strategies to manage soil C and mitigate the impacts of climate change.

The Diagnostic and Prognostic Value of EBUS-TBNA for Intrathoracic Metastasis in Previously Treated Patients With Head and Neck Cancer.

OBJECTIVE: The present study assessed the diagnostic and prognostic significance of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) for suspected intrathoracic metastasis after HNC treatment. METHODS: A retrospective analysis was conducted on 75 patients with a prior history of head and neck cancer treatment who underwent EBUS-TBNA for suspected intrathoracic metastases between March 2012 and December 2021. RESULTS: A total of 126 targeted lesions, including 107 mediastinal/hilar lymph nodes and 19 intrapulmonary/mediastinal masses, were sampled. The metastatic head and neck cancer (HNC) cases detected by EBUS-TBNA consisted of nasopharyngeal carcinoma (n = 24), oropharyngeal carcinoma (n = 3), hypopharynx carcinoma (n = 6), laryngeal carcinoma (n = 6), and oral cavity carcinoma (n = 6). Cases with negative EBUS-TBNA results consisted of tuberculosis (n = 9), sarcoidosis (n = 3), anthracosis (n = 9), and reactive lymphadenitis (n = 9). Six false-negative cases were found among the 75 patients with suspected intrathoracic metastases. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of the EBUS-TBNA procedure for metastatic HNC were 88.2, 100.0, 100.0, 80, and 92.0%, respectively. The diagnosis of HNC intrathoracic metastasis by EBUS-TBNA correlated with an adverse prognosis in terms of overall survival (OS) (P = .008). The log-rank univariate analysis and Cox regression multivariate analysis results indicated that the detection of metastatic HNC through EBUS-TBNA was a significant independent prognostic factor for patients with HNC who had received prior treatment. CONCLUSIONS: Endobronchial ultrasound-guided transbronchial needle aspiration is a safe, effective, and minimally invasive procedure for assessing suspected intrathoracic metastasis in HNC patients after treatment. The intrathoracic metastasis detected by EBUS-TBNA has crucial prognostic significance in previously treated HNC patients.

A Mechanical Defect Localization and Identification Method for High-Voltage Circuit Breakers Based on the Segmentation of Vibration Signals and Extraction of Chaotic Features.

To address the problem of mechanical defect identification in a high-voltage circuit breaker (HVCB), this paper studies the circuit breaker vibration signal and proposes a method of feature extraction based on phase-space reconstruction of the vibration substages. To locate mechanical defects in circuit breakers, vibration signals are divided into different substages according to the time sequence of the parts of the circuit breakers. The largest Lyapunov exponent (LLE) of the vibration signals' substages is calculated, and then the substages are reconstructed in high-dimensional phase space. The geometric features of the phase trajectory mean center distance (MCD) and vector diameter offset (VDO) are calculated, and the LLE, MCD, and VDO are selected as the three fault identification features of the vibration substages. The eigenvalue anomaly rate of each substage of the vibration signal under defect state are calculated and analyzed to locate the vibration substage of the mechanical defect. Finally, a fault diagnosis model is constructed by a support vector machine (SVM), and the common mechanical defects of circuit breakers simulated in the laboratory are effectively identified.

[Effect of Calcified Lymph Nodes on Thoracoscopic Lobectomy in Chronic Obstructive Pulmonary Disease Patients with Lung Cancer].

Objective To observe the effect of calcified lymph nodes on video-assisted thoracoscopic surgery (VATS) lobectomy in the chronic obstructive pulmonary disease (COPD) patients with lung cancer. Methods A retrospective analysis was conducted on the COPD patients with lung cancer who underwent VATS lobectomy in the Department of Thoracic Surgery in the First Affiliated Hospital of Hebei North University from May 2014 to May 2018.The patients were assigned into a calcified lymph node group and a control group according to the presence or absence of calcified lymph nodes in CT,and the size,morphology,and calcification degree of the lymph nodes were recorded.The operation duration,intraoperative blood loss,chest tube retention time,hospitalization days,and overall complication rate were compared between the two groups. Results The 30 patients in the calcified lymph node group included 17 patients with one calcified lymph node and 13 patients with two or more calcified lymph nodes,and a total of 65 calcified lymph nodes were recorded.The calcified lymph nodes with the size ≤5 mm were the most common (53.8%),and complete calcification was the most common form (55.4%) in lymph node calcification.The mean operation duration had no significant difference between the calcified lymph node group and the control group (t=-1.357,P=0.180).The intraoperative blood loss (t=-2.646,P=0.010),chest tube retention time (t=-2.302,P=0.025),and hospitalization days (t=-2.274,P=0.027) in the calcified lymph node group were higher than those in the control group. Conclusion Calcified lymph nodes increase the difficulty and risk of VATS lobectomy in the COPD patients with lung cancer.The findings of this study are conducive to predicting the perioperative process of VATS lobectomy.

Roll-to-Roll DNA Nanomachine for Ultrasensitive Electrochemical Determination of miRNA.

MicroRNAs (miRNAs) are a family of endogenous noncoding RNAs with the functions of gene regulation, which serve as promising markers for a range of diseases such as diabetic foot ulcers, cancers, etc. In this work, we engineered a roll-to-roll DNA nanomachine for highly sensitive electrochemical detection of miRNA. A dumbbell-structured DNA probe could be transitioned to be wheel-structured conformation upon target recognition, which rolls around track strands on the surface of gold nanoparticles (AuNPs) in the presence of nicking endonuclease. The resulting single strands on AuNPs are activated for the second round of rolling at the DNA-modified electrode interface, leading to the variation of electrochemical responses. The roll-to-roll amplification behavior allows a wide detection range with a limit of detection as low as 10 aM. The practicability is also demonstrated by the application in human serum samples with satisfactory results. It is expected that the proposed electrochemical method offers a new paradigm to develop miRNA assays based on DNA nanotechnology.

Expression of Shh, Gli1, and Cyr61 in Gastric Cancer Predicts Overall Survival of Patients: A Retrospective Study.

OBJECTIVE: This study aimed to evaluate the expression levels of Shh, Gli1, and Cyr61 proteins in gastric cancer tissues and analyze the relationship between these three proteins and the clinicopathological factors and prognosis of patients. METHODS: This was a retrospective study. Four hundred gastric cancer tissue specimens from patients who underwent radical gastrectomy in Zhangye People's Hospital affiliated to Hexi University between February 2013 and February 2021 underwent immunohistochemical analysis. RESULTS: The positive expression rates of Shh, Gli1, and Cyr61 in gastric cancer tissues were 55.5%, 56.5%, and 64.5%, respectively. The expressions of Shh, Gli1, and Cyr61 in gastric cancer tissues were significantly correlated with tumor size, depth of invasion, and degree of differentiation (P < .05). The expression of Shh protein was positively correlated with the expression of Gli1 protein (P < .01), and the expression of Gli1 protein was positively correlated with the expression of Cyr61 protein (P < .01). Univariate and multivariate analyses showed that the expression of Shh, Gli1, and Cyr61 could predict the prognosis of patients (P < .05). Receiver operating characteristic curve analysis combined with TNM staging could better predict the three-year overall survival of patients (P < .05). CONCLUSION: Shh, Gli1, and Cyr61 proteins are significantly expressed in gastric cancer tissues and are risk factors for the prognosis of patients with gastric cancer.

Palladium-Catalyzed Oxidative Nonclassical Heck Reaction of Arylhydrazines with Allylic Alcohols via C-N Bond Cleavage: Access to ß-Arylated Carbonyl Compounds.

An efficient palladium-catalyzed oxidative nonclassical Heck reaction of arylhydrazines with allylic alcohols via C-N bond cleavage has been successfully developed. This method provides a series of ß-arylated carbonyl compounds with broad functional group tolerance under base-free, simple, and mild open air reaction conditions. In the reaction, arylhydrazines with the smaller molecular weight of the leaving group were employed as the "green" arylation reagent, which released N2 and water as the byproducts under air. Mechanistic studies suggested that an aryl radical process and Pd-H complex migration reinsertion were involved. Moreover, the synthesis of the antiarrhythmic drug propafenone was completed with this transformation as the key step.

Access to gem-Difluoroalkenes via Organic Photoredox-Catalyzed gem-Difluoroallylation of Alkyl Iodides.

An organic photoredox-catalyzed gem-difluoroallylation of α-trifluoromethyl alkenes with alkyl iodides via C-F bond cleavage for the synthesis of gem-difluoroalkene derivatives is reported. This transition-metal-free transformation utilized a readily available organic dye 4CzIPN as the sole photocatalyst and employed a common chemical N,N,N',N'-tetramethylethylenediamine as the radical activator of alkyl iodides via halogen-atom transfer. In addition, a variety of iodides, including primary, secondary, and tertiary alkyl iodides, were tolerated and provided good to high yields.

Synthesis of (Z)-ß-Chloro-enamides via a Base-Promoted trans-Hydroamidation of Alkynyl Chlorides Using 1,1-Dichloroalkenes as Precursor.

An efficient and general base-promoted reaction of 1,1-dichloroalkenes with secondary sulfonamides and amides for the synthesis of (Z)-ß-chloro-enamides has been described. This reaction exhibits functional group tolerance under simple and mild conditions. Mechanistic study indicated that a stereoselective trans-hydroamidation of alkynyl chlorides generated in situ from 1,1-dichloroalkenes was the key step.

Consistency between deposition of particulate matter and its removal by rainfall from leaf surfaces in plant canopies.

The leaf surfaces of plants are important organs for retaining particulate matter (PM). They can be renewed via washout processes (e.g., rainfall), thereby restoring the ability to retain new PM. Most of the current studies have focused on the mechanisms of rainfall characteristics on the renewal of PM on plant leaf surfaces and interspecific differences, while the effects of different leaf heights on PM renewal within the same plant canopy have been less studied. In addition, the dynamics of PM during rainfall, especially the water-soluble ions (WSII) component, are often neglected. This research used Salix matsudana, a tree species with a significant natural height difference between the upper and lower leaves of its canopy, as its study object. Using artificially simulated rainfall, the rainfall intensity was quantified as low, medium, and high (i.e., 30 mm/h, 45 mm/h, and 60 mm/h), and the rainfall process was divided into three sub-stages: pre (0-20 min), mid (20-40 min), and post (40-60 min). The experimental setup was divided into upper (2 m) and lower leaves (1 m) according to the height of the canopy. The concentration and distribution of water-insoluble PM (WIPM) were obtained using the elution weighing method, whereas WSII were obtained using ion chromatography. The dynamics of WIPM and WSII during the removal of PM from the leaf surface by rainfall were studied at different canopy heights, and the results showed that the composition and proportions of WIPM and WSII varied at different stages of the rainfall process and that the concentrations of WIPM and WSII removed from the upper leaves differed slightly from those of the lower leaves. In particular, the concentrations of WIPM and WSII removed from the lower leaves were greater than those from the upper leaves at high rainfall intensity (60 mm/h), showing consistency between rainfall removal of PM from the leaf surface at different heights within the plant canopy and deposition of PM, while at low (30 mm/h) and medium (45 mm/h) rainfall intensities the performance was slightly different.

Rainfall characteristics significantly affect the scavenging of water-soluble ions attached to leaves.

Precipitation is considered the most effective way to remove particulate matter from the leaves of plants. Changes in rainfall characteristics can affect the scavenging processes of particulate matter from leaves. In order to better understand the dynamics of PM scavenging during rainfall, especially the water-soluble ions components, leaves from the 11 plant species (trees, shrubs, terrestrial herbs, wetland plants) from the Olympic park were sampled and used in indoor experiments. During the experiments, the rainfall intensity was set at 30 mm/h, 45 mm/h, and 60 mm/h, and the duration was divided into 0-20 min, 20-40 min, and 40-60 min. The sampled plant leaves were set in the experiments at 1 m and 3 m height from the ground. Concentrations and compositions of nine water-soluble ions of rainfall samples were analyzed in this experiment. The results revealed that SO42-, Ca2+, and Na+ were the most abundant ionic species removed from the leaves, and NO3- ranked fourth, followed by Cl-, Mg2+ K+, NH4+, and F-. The ions concentration of rainfall samples decreased when the rain intensity increased from 30 to 45 mm/h and when the rain intensity increased to 60 mm/h. The efficiency of scavenging during different rainfall durations depends on the ionic species. Na+, Mg2+, Ca2+, and SO42- concentrations increased with the increase in rainfall duration, whereas those of NH4+, K+, and Cl- decreased. The effect of leaf height on ions concentration of rainfall samples was also different among the ionic species: Na+, Mg2+, Ca2+, NO3-, and F- concentrations were significantly higher at 1 m compared with 3 m. The principal component analysis of ions in rainfall samples revealed two main sources of particulate matter in our study. One is from vehicle exhaust and industrial and agricultural pollution. The other is agricultural combustion and ground dust sources. The results of the above study can provide a basis and theoretical support for the establishment of urban cleaning systems and the prevention of air pollution.

Concentrations and isotopic analysis for the sources and transfer of lead in an urban atmosphere-plant-soil system.

Lead pollution has attracted significant attention over the years. However, research on the transfer of lead between urban atmospheric particles, soils, and plants remains rare. We measured lead concentrations and lead isotope ratios in total suspended particles (TSP), soil, and plants in an urban wetland in Beijing. The study period was September 2016-August 2017- covering all four seasons. The concentrations of lead in the atmospheric particles vary from 3.13 to 6.68 mg/m3. It is significantly higher in autumn than that in spring and summer (P < 0.05). There is also a significant difference between summer and winter (P < 0.05). The soil lead concentrations range from 57 to 114 mg/kg, with the highest concentration in spring, followed by summer, winter and autumn. The lead concentrations are 1.28-7.75 mg/kg in plants. The concentration was highest in spring and significantly higher than in summer. The bioaccumulation factor of Phragmites australis was 0.064 (<0.1), indicating that lead is not easily transferred to plants. Unlike the bioaccumulation factors, translocation factors have much higher values, indicating a higher transfer within the plants. Results also indicate an interesting seasonal pattern with almost 97% of lead in plants during spring being of atmospheric origin, whereas in autumn, soilborne sources contribute almost 94%. The isotopic compositions of lead in the urban atmosphere-soil-plant system show that lead pollution results from the mixing of geogenic and anthropogenic materials. Vehicle exhaust, crustal rocks and ore deposits are likely primary sources of lead pollution within the study domain.