Atmospheric fate and impacts of HFO-1234yf from mobile air conditioners in East Asia.

HFO-1234yf (2,3,3,3-tetrafluoropropene) is being used as refrigerant to replace HFC-134a (1,1,1,2-tetrafluoroethane), a potent greenhouse gas, in mobile air conditioners. However, the environmental impacts of HFO-1234yf, which is quickly and almost completely transformed to the persistent and phytotoxic trifluoroacetic acid (TFA), is of great concern. Here, we used the nested-grid chemical transport model, GEOS-Chem, to assess the fate and environmental impacts of HFO-1234yf emissions from mobile air conditioners in East Asia. With total emissions of 30.3 Gg yr-1, the annual mean concentrations of HFO-1234yf in China, Japan, and South Korea were 4.00, 3.23, and 5.54 pptv (parts per trillion volume), respectively, and the annual deposition fluxes (dry plus wet) of TFA in these regions were 0.35, 0.48, and 0.53 kg km-2 yr-1, dominated by wet deposition. About 14 %, 13 % and 11 % of HFO-1234yf emissions were deposited as TFA in China, Japan and South Korea, respectively, i.e. a large portion of TFA was deposited in areas outside of the emission boundary regions. The TFA characteristics in Japan and South Korea was significantly influenced by emission from China, which contributions ranged from 43 % to 94 % for the TFA concentrations and 44 % to 98 % for the TFA depositions across the four seasons. This suggests that the influence of neighboring emission sources cannot be ignored when assessing the impact of HFO-1234yf emissions in individual countries.

Style Transfer-assisted Deep Learning Method for Kidney Segmentation at Multiphase MRI.

Purpose: To develop and validate a semisupervised style transfer-assisted deep learning method for automated segmentation of the kidneys using multiphase contrast-enhanced (MCE) MRI acquisitions. Materials and Methods: This retrospective, Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study included 125 patients (mean age, 57.3 years; 67 male, 58 female) with renal masses. Cohort 1 consisted of 102 coronal T2-weighted MRI acquisitions and 27 MCE MRI acquisitions during the corticomedullary phase. Cohort 2 comprised 92 MCE MRI acquisitions (23 acquisitions during four phases each, including precontrast, corticomedullary, early nephrographic, and nephrographic phases). The kidneys were manually segmented on T2-weighted images. A cycle-consistent generative adversarial network (CycleGAN) was trained to generate anatomically coregistered synthetic corticomedullary style images using T2-weighted images as input. Synthetic images for precontrast, early nephrographic, and nephrographic phases were then generated using the synthetic corticomedullary images as input. Mask region-based convolutional neural networks were trained on the four synthetic phase series for kidney segmentation using T2-weighted masks. Segmentation performance was evaluated in a different cohort of 20 originally acquired MCE MRI examinations by using Dice and Jaccard scores. Results: The CycleGAN network successfully generated anatomically coregistered synthetic MCE MRI-like datasets from T2-weighted acquisitions. The proposed deep learning approach for kidney segmentation achieved high mean Dice scores in all four phases of the original MCE MRI acquisitions (0.91 for precontrast, 0.92 for corticomedullary, 0.91 for early nephrographic, and 0.93 for nephrographic). Conclusion: The proposed deep learning approach achieved high performance in kidney segmentation on different MCE MRI acquisitions.Keywords: Kidney Segmentation, Generative Adversarial Network, CycleGAN, Convolutional Neural Network, Transfer Learning Supplemental material is available for this article. Published under a CC BY 4.0 license.

Integration of single-cell and bulk RNA sequencing to establish a prognostic signature based on tumor-associated macrophages in colorectal cancer.

Several studies have shown significant involvement of tumor-associated macrophages (TAMs) in the tumor microenvironment and cancer progression. However, no data on reliable TAM-related biomarkers are available for predicting the prognosis of patients with colorectal cancer (CRC). We analyzed the clinical data and gene expression profiles of patients with CRC from databases. The single-cell transcriptomic data was applied to identify M2-like TAM-related differentially expressed genes. Univariate Cox and least absolute shrinkage and selection operator regression analyses were used to determine the prognostic signature genes. Then, seven key genes were screened to develop the prognostic signature. In the training and external validation cohorts, the overall survival (OS) of patients in the high-risk group was significantly shorter compared to the low-risk group. Consequently, we created a nomogram that could accurately and reliably predict the prognosis of patient with CRC. A significant correlation was observed between the patient's prognosis, clinical features, sensitivity to anticancer drugs, TME, and risk scores. Moreover, risk score was strongly related to the response to immunotherapy in patients from GSE91061, GSE78220, and GSE60331 cohorts. Finally, high expression of HSPA1A, SERPINA1, CXCL1, and low expression of DNASE1L3 were found in human CRC tissue and normal tissue by using qRT-PCR. In conclusion, the M2-like TAM-related prognostic signature could predict the survival, prognosis, and response of patients with CRC to immunotherapy, which sheds light on the role of TAMs in CRCs and enhances our understanding of TAMs.

Single-arm, phase II study of intra-arterial chemotherapy plus total neoadjuvant therapy to optimise complete response in distal rectal cancer: a study protocol.

INTRODUCTION: Organ preservation is now considered an acceptable alternative option in distal rectal cancer patients with clinical complete response (cCR) after neoadjuvant chemoradiation (CRT). But the cCR rate is low and about one-third of tumour will regrow, which requires more effective local treatment. CRT combined with intra-arterial chemotherapy (IAC) might be a promising approach. Additionally, total neoadjuvant therapy using FOLFIRINOX induction chemotherapy improved survival while consolidation chemotherapy improved organ preservation. We assess whether IAC plus CRT and FOLFIRINOX consolidation chemotherapy can improve the chance of organ preservation and survival in distal rectal cancer. METHODS AND ANALYSIS: This prospective, monocentric, open-label, single-arm phase II study will include 32 patients with cT3-4NanyM0 distal rectal adenocarcinoma. All patients will receive one cycle of IAC (irinotecan, raltitrexed and oxaliplatin), followed by CRT (50 Gy/25 fractions with concomitant capecitabine) and then with six cycles of FOLFIRINOX (leucovorin, 5-fluorouracil, oxaliplatin and irinotecan). After final evaluation, patients with cCR will receive non-operative management or surgery at their own discretion and others are mandatorily referred to surgery. Adjuvant chemotherapy with six cycles of mFOLFOX6 (leucovorin, 5-fluorouracil and oxaliplatin) will be used for patients with adverse pathological features. The primary endpoint is the rate of complete response (CR; pathological CR or sustained cCR≥2 years). The main secondary endpoints are toxicity, compliance, short-term and long-term oncological outcomes, surgical morbidity and quality of life. This protocol has been designed in accordance with the Standard Protocol Items: Recommendations for Interventional Trials 2013 guidelines. ETHICS AND DISSEMINATION: This study was approved by the Academic and Ethics Committee of The Affiliated Hospital of Youjiang Medical University for Nationalities in March 2023. Trial results will be published in peer-reviewed international journals and on the ChiCTR website. PROTOCOL VERSION: Registered on 18 April 2023; version #1. TRIAL REGISTRATION NUMBER: ChiCTR2300070620.

Assessment of the internal and external exposure risks to methylsiloxanes in communities near a petroleum refinery.

Methylsiloxanes (MSs) are widely used in industrial production and have attracted much attention due to their potential health risks to humans. MSs are present in emissions from petroleum refining, and it is therefore important to assess the health risks to residents living near refineries. In this study, we evaluated the pollution characteristics and human exposure risks of three cyclic MS (CMS) oligomers (D4-D6) in areas upwind and downwind of a petroleum refinery. The concentrations of total CMSs were 4-33 times higher in the downwind than upwind areas. At the same sampling site, the concentrations of CMSs were higher indoors than outdoors. The maximum concentration of CMSs was found in the indoor environment 200 m downwind of the petroleum refinery (75 µg/m3 in air and 2.3 µg/g in dust). The concentrations and detection rates of CMSs in plasma samples were higher in the downwind than upwind residents. Although residents living downwind of the petroleum refinery were a non-occupationally exposed population, they should be considered a highly CMS-exposed population because of their extremely high internal exposure doses. Inhalation exposure was the main source of CMSs in the plasma of these residents. When different exposure pathways were investigated, inhalation exposure was the major contributor to the average daily dose in residents of locations near the petroleum refinery, whereas the dermal absorption of personal care products was the major contributor at other sites. Although the overall risks of exposure to total CMSs were below the chronic reference dose for all exposure pathways, the combined joint toxic effects of various CMSs remain unclear. Further studies are therefore required to determine the exposure risks and subsequent health effects of CMSs for the residents of these areas.

Association of volatile methylsiloxanes exposure with non-alcoholic fatty liver disease among Chinese adults.

Owing to the wide use of volatile methylsiloxanes (VMSs) in various industries and consumer products, both cyclic VMSs (cVMS) and linear VMSs (lVMS) have been detected in human plasma. Experimental studies suggest that exposure to cVMSs may induce liver disease. Whereas, there is no human evidence of the potential health effects of VMSs yet. In this cross-sectional study, we evaluated the association of plasma VMSs concentrations with liver enzymes and Nonalcoholic fatty liver disease (NAFLD) among adults located in southwestern China. We used the fibrosis 4 calculator (FIB-4) as the NAFLD index and defined FIB-4≥1.45 as the NAFLD case. Among 372 participants, 45 (12.1%) of them were classified as NAFLD. Positive associations of plasma cVMSs concentrations with liver enzymes and NAFLD were observed among all participants. With per doubling increase in the total cVMSs, we observed a 1.40 (95%CI: 0.31, 2.48) increase in Alanine aminotransferase (ALT), a 1.56 (95%CI: 0.52, 2.61) increase in aspartate aminotransferase (AST) and a 0.04 (0.00, 0.09) increase in NAFLD index. A 19% increased risk of NAFLD was also found to be associated with per doubling increase in total cVMSs. In addition, positive associations of total lVMSs with ALT, AST and NAFLD were also detected when restricting our analyses to 230 participants living in industrial areas. Our study first provides epidemiological evidence on the association between VMSs and liver health, indicating more careful usage of VMSs may potentially reduce the burden of NAFLD, though more well-designed cohort studies are needed to confirm these findings.

Projections of National-Gridded Emissions of Hydrofluoroolefins (HFOs) in China.

Hydrofluoroolefins (HFOs) are being used as substitutes for potent greenhouse gas hydrofluorocarbons (HFCs). However, the use and environmental impacts of HFOs are of great concern due to the rapid degradation of HFOs to produce persistent and phytotoxic trifluoroacetic acid (TFA). Here, we provide a comprehensive projection of HFO emissions in China during 2024-2060 for the first time. Under the Kigali Amendment to the Montreal Protocol, China's HFO emissions are estimated to increase from 1.7 (1.3-2.3) to 148.8 (111.4-185.4) kt in 2024-2060 with cumulative emissions of 2.8 (2.0-3.5) Gt, and cumulative reduced HFCs emissions are evaluated to be 5.4 Gt CO2-equivalent. High HFO emissions would be distributed mainly in the North China Plain and the eastern and coastal areas. HFO-1234yf (2,3,3,3-tetrafluoropropene) contributes most of HFO emissions with a cumulative emission of 1.7 Gt in 2024-2060, while the cumulative increment of TFA deposition from HFO-1234yf emissions would reach 0.4-1.0 Gt. The long-term national-gridded HFO emission inventories can provide scientific support for evaluating the environmental risks of HFOs and developing HFC phase-out pathways for addressing climate change.

Occurrence and Behavior of Methylsiloxanes in Urban Environment in Four Cities of China.

Methylsiloxanes (MSs), used in industrial production and personal care products, are released in various environmental media. In this study, we combined monitoring and modeling to investigate the occurrence and behavior of MSs in the urban environment in China. MSs were widely found in the air, water, soil and sediment of four cities in China. The concentrations of MSs in all four environmental media of Zhangjiagang were higher than those in the other three cities (Beijing, Kunming and Lijiang), indicating that the siloxane production plant had a significant impact on the pollution level of MSs in the surrounding environment. The samples with high MS concentrations were all from the sample sites near the outlet of the WWTPs, which showed that the effluent of the WWTPs was the main source of MS pollution in the surrounding environment. The modeling results of the EQC level III model showed that D4 discharged into the environment was mainly distributed in the air, while D5 and D6 were mainly distributed in the sediment. CMSs (D4-D6) discharged into various environmental media could exist in the urban environment for a long time with low temperatures in cities. When the temperature was 0 °C, the residence time of D5 and D6 could be 68.1 days and 243 days in the whole environmental system in Beijing. This study illustrates the importance of CMSs (D4-D6) in low-temperature environments and the potential environmental risks that they may pose.

Methylsiloxanes risk assessment combining external and internal exposure for college students.

Methylsiloxanes (MSs) are widely used as solvents or emollients in various personal care products (PCPs) and may pose a health risk. In this study, we assessed external and internal exposure to MSs among students at two universities in southwestern China. Samples of air, dust, and PCPs were collected to evaluate indoor non-dietary exposure to MSs via multiple pathways among the students. Indoor MS levels were approximately 1-3 orders of magnitude higher in the dormitories of female students than in either classrooms or the dormitories of male students. Lipstick contained the highest MS levels. Cyclic MS (CMS: D4-D6) levels were 1 order of magnitude higher in female students than in male students. Among the three CMSs, D5 levels were highest in the plasma of all students (1.3-15 ng/mL). In dormitories, dermal contact with PCPs was the major route of exposure to CMSs for all students. Among linear MSs (LMSs: L5-L16), dermal PCP absorption and dust ingestion were the predominant exposure routes for male and female students, respectively. Although the overall risk of exposure to D4 and D5 was below the chronic reference dose for all exposure routes and all students, the total daily doses of exposure to D4 and D5 via dermal PCP absorption approached the chronic reference dose in four female students. Therefore, the effects of MSs on female students should be further investigated in future studies.

Deep learning kidney segmentation with very limited training data using a cascaded convolution neural network.

BACKGROUND: Deep learning segmentation requires large datasets with ground truth. Image annotation is time consuming and leads to shortages of ground truth data for clinical imaging. This study is to investigate the feasibility of kidney segmentation using deep learning convolution neural network (CNN) models trained with MR images from only a few subjects. METHODS: A total of 60 subjects from two cohorts were included in this study. The first cohort of 20 subjects from publicly available data was used for training and testing. The second cohort of 40 subjects with renal masses from our institution was used for testing only. A few-shot deep learning approach using 3D augmentation was investigated. T1-weighted images in the first cohort were used for training and testing. Cascaded CNN networks were trained using images from one, three, and six subjects, respectively. Images for the remaining subjects were used for testing. Images in the second cohort were utilized for testing only. Dice and Jaccard coefficients were generated to evaluate the performance of CNN models. Statistical analyses for segmentation metrics among different approaches were performed. RESULTS: Our approach achieved mean Dice coefficients of 0.85 using a single training subject and 0.91 with six training subjects. Compared to a single Unet, the cascaded network significantly improved the results using a single training subject (Dice, 0.759 vs. 0.835; p<0.001) and three subjects (0.864 vs. 0.893; p = 0.015) in the first cohort, and the results for the second cohort (0.821 vs. 0.873; p = 0.008). CONCLUSION: Our few-shot kidney segmentation approach using 3D augmentation achieved a good performance even using a single Unet. Furthermore, the cascaded network significantly improved the performance of segmentation and was superior to a single Unet in certain cases. Our approach provides a promising solution to segmentation in medical imaging when the number of ground truth masks is limited.

Deep Learning-based Deformable Registration of Dynamic Contrast-Enhanced MR Images of the Kidney.

Respiratory motion is a major contributor to bias in quantitative analysis of magnetic resonance imaging (MRI) acquisitions. Deformable registration of three-dimensional (3D) dynamic contrast-enhanced (DCE) MRI data improves estimation of kidney kinetic parameters. In this study, we proposed a deep learning approach with two steps: a convolutional neural network (CNN) based affine registration network, followed by a U-Net trained for deformable registration between two MR images. The proposed registration method was applied successively across consecutive dynamic phases of the 3D DCE-MRI dataset to reduce motion effects in the different kidney compartments (i.e., cortex, medulla). Successful reduction in the motion effects caused by patient respiration during image acquisition allows for improved kinetic analysis of the kidney. Original and registered images were analyzed and compared using dynamic intensity curves of the kidney compartments, target registration error of anatomical markers, image subtraction, and simple visual assessment. The proposed deep learning-based approach to correct motion effects in abdominal 3D DCE-MRI data can be applied to various kidney MR imaging applications.

Deciphering Intratumoral Molecular Heterogeneity in Clear Cell Renal Cell Carcinoma with a Radiogenomics Platform.

PURPOSE: Intratumoral heterogeneity (ITH) challenges the molecular characterization of clear cell renal cell carcinoma (ccRCC) and is a confounding factor for therapy selection. Most approaches to evaluate ITH are limited by two-dimensional ex vivo tissue analyses. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can noninvasively assess the spatial landscape of entire tumors in their natural milieu. To assess the potential of DCE-MRI, we developed a vertically integrated radiogenomics colocalization approach for multi-region tissue acquisition and analyses. We investigated the potential of spatial imaging features to predict molecular subtypes using histopathologic and transcriptome correlatives. EXPERIMENTAL DESIGN: We report the results of a prospective study of 49 patients with ccRCC who underwent DCE-MRI prior to nephrectomy. Surgical specimens were sectioned to match the MRI acquisition plane. RNA sequencing data from multi-region tumor sampling (80 samples) were correlated with percent enhancement on DCE-MRI in spatially colocalized regions of the tumor. Independently, we evaluated clinical applicability of our findings in 19 patients with metastatic RCC (39 metastases) treated with first-line antiangiogenic drugs or checkpoint inhibitors. RESULTS: DCE-MRI identified tumor features associated with angiogenesis and inflammation, which differed within and across tumors, and likely contribute to the efficacy of antiangiogenic drugs and immunotherapies. Our vertically integrated analyses show that angiogenesis and inflammation frequently coexist and spatially anti-correlate in the same tumor. Furthermore, MRI contrast enhancement identifies phenotypes with better response to antiangiogenic therapy among patients with metastatic RCC. CONCLUSIONS: These findings have important implications for decision models based on biopsy samples and highlight the potential of more comprehensive imaging-based approaches.

SNHG17 Serves as an Oncogenic lncRNA by Regulating the miR-361-3p/STC2 Axis in Rectal Cancer.

Long noncoding RNA (lncRNA) have been reported to be crucial regulators for carcinogenesis, including rectal cancer. This work aimed to explore the roles and associated mechanisms of small nucleolar RNA host gene 17 (SNHG17) in rectal cancer. A quantitative real-time polymerase chain reaction was performed to measure the expression level of SNHG17 in rectal cancer tissues and cells. Cell counting kit-8 (CCK-8) assay and flow cytometry assay were conducted to measure the biological roles of SNHG17 in rectal cancer. In addition, luciferase activity reporter assay, RNA immunoprecipitation (RIP) assay, and rescue experiments were conducted to explore the mechanisms of SNHG17 in rectal cancer. The upregulation status of SNHG17 was identified in rectal cancer tissues and cells. Functionally, knockdown the expression of SNHG17 inhibits rectal cancer cell proliferation via stimulating cell apoptosis. In vivo assay showed that the knockdown of SNHG17 inhibits tumor growth. Furthermore, we showed that microRNA-361-3p (miR-361-3p) has decreased expression in tumor tissues and cells, and SNHG17 functions as a sponge for miR-361-3p. The upregulation status of stanniocalcin 2 (STC2) was also found in rectal cancer, and the knockdown of STC2 hinders cancer progression. In conclusion, lncRNA SNHG17 functions as an oncogenic lncRNA in rectal cancer by regulating the miR-361-3p/STC2 axis.

Assessment of internal exposure to methylsiloxanes in children and associated non-dietary exposure risk.

Methylsiloxanes (MSs) are a significant source of indoor environmental pollution due to their high production level and widespread application, and pose a potential health risk. Given the special vulnerability of children to environmental contaminants, assessment of indoor MSs exposure in children is quite essential. In this study, we assessed internal exposure doses and external exposure levels of MSs in children from industrial and residential areas in southwestern China. Indoor air, indoor dust, and personal care product (PCP) samples were collected to evaluate indoor non-dietary MSs exposure in children through various pathways. The concentrations of MSs in indoor environments of industrial areas were approximately one to four orders of magnitude higher than those of residential areas. Sun protection products contained the highest concentrations of MSs. Relatively high levels of cyclic methylsiloxanes (CMSs) were found in plasma of children from industrial areas, which were one to two orders of magnitude higher than those in children from residential areas. The highest MSs levels in plasma were detected in infants (0-1 year), with values of 1.4 × 102 ng/mL and 1.3 × 102 ng/mL for CMSs (D4-D6) and linear methylsiloxanes (LMSs) (L5-L16), respectively. The internal exposure dose of infants in residential areas is driven by major unknown sources of MSs. The average daily doses via inhalation and dust ingestion in children from industrial areas were one to three orders of magnitude higher than in those from residential areas, indicating that these children should be considered a highly exposed population. Inhalation and dust ingestion were both major exposure pathways to MSs for children of all age groups in industrial areas, whereas dermal absorption from PCPs was the predominant exposure pathway for children of all age groups in residential areas (except for infants). Although the exposure risk to D4 and D5 was at an acceptable level for all children studied, the total daily exposure doses of these two cyclic compounds via inhalation for infants in the industrial areas was near the chronic reference dose. Meanwhile, MSs may accumulate in infant plasma within a short period of time (<6 months). Therefore, infants should be the focus of greater attention in future research. As indoor environments may pose high risks for infants in industrial areas, they should be the focus of future research.

Hand-Powered Microfluidics for Parallel Droplet Digital Loop-Mediated Isothermal Amplification Assays.

Droplet digital loop-mediated isothermal amplification (ddLAMP) is an important assay for pathogen detection due to its high accuracy, specificity, and ability to quantify nucleic acids. However, performing ddLAMP requires expensive instrumentation and the need for highly trained personnel with expertise in microfluidics. To make ddLAMP more accessible, a ddLAMP assay is developed, featuring significantly decreased operational difficulty and instrumentation requirements. The proposed assay consists of three simplified steps: (1) droplet generation step, in which a LAMP mixture can be emulsified just by manually pulling a syringe connected to a microfluidic device. In this step, for the first time, we verify that highly monodispersed droplets can be generated with unstable flow rates or pressures, allowing untrained personnel to operate the microfluidic device and perform ddLAMP assay; (2) heating step, in which the droplets are isothermally heated in a water bath, which can be found in most laboratories; and (3) result analysis step, in which the ddLAMP result can be determined using only a fluorescence microscopy and an open-source analyzing software. Throughout the process, no droplet microfluidic expertise or equipment is required. More importantly, the proposed system enables multiple samples to be processed simultaneously with a detection limit of 10 copies/µL. The test is simple and intuitive to operate in most laboratories for multi-sample detection, significantly enhancing the accessibility and detection throughput of the ddLAMP technique.

Multi-site, multi-platform comparison of MRI T1 measurement using the system phantom.

Recent innovations in quantitative magnetic resonance imaging (MRI) measurement methods have led to improvements in accuracy, repeatability, and acquisition speed, and have prompted renewed interest to reevaluate the medical value of quantitative T1. The purpose of this study was to determine the bias and reproducibility of T1 measurements in a variety of MRI systems with an eye toward assessing the feasibility of applying diagnostic threshold T1 measurement across multiple clinical sites. We used the International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) system phantom to assess variations of T1 measurements, using a slow, reference standard inversion recovery sequence and a rapid, commonly-available variable flip angle sequence, across MRI systems at 1.5 tesla (T) (two vendors, with number of MRI systems n = 9) and 3 T (three vendors, n = 18). We compared the T1 measurements from inversion recovery and variable flip angle scans to ISMRM/NIST phantom reference values using Analysis of Variance (ANOVA) to test for statistical differences between T1 measurements grouped according to MRI scanner manufacturers and/or static field strengths. The inversion recovery method had minor over- and under-estimations compared to the NMR-measured T1 values at both 1.5 T and 3 T. Variable flip angle measurements had substantially greater deviations from the NMR-measured T1 values than the inversion recovery measurements. At 3 T, the measured variable flip angle T1 for one vendor is significantly different than the other two vendors for most of the samples throughout the clinically relevant range of T1. There was no consistent pattern of discrepancy between vendors. We suggest establishing rigorous quality control procedures for validating quantitative MRI methods to promote confidence and stability in associated measurement techniques and to enable translation of diagnostic threshold from the research center to the entire clinical community.

Emissions, degradation and impact of HFO-1234ze from China PU foam industry.

Currently used foam agent HCFC-141b was undergoing phased out worldwide with the implementation of the Montreal Protocol. HFO-1234ze was proposed as replacement in polyurethane (PU) foam industry with shorter atmospheric lifetime. This paper calculated historical and future emissions of HCFC-141b and HFO-1234ze till 2050, used GEOS-Chem under two HFO-1234ze emission scenarios to track its atmospheric process and distribution, and to assess its potential environmental effects. Results showed that annual HCFC-141b emissions for 2015, 2019 and 2050 were 12.6 Gg/yr, 21.0 Gg/yr and 7.6 Gg/yr, respectively and emissions of HFO-1234ze would reach 124.4 Gg/yr by 2050. Under Scenario I with HFO-1234ze emissions of 12.6 Gg/yr as input, annual mixing ratios of HFO-1234ze and its products CF3CHO and HCOF were 10.47, 2.68 and 1.74 pptv for China, and were 0.55, 0.18 and 0.1 pptv globally, respectively, suggesting the regional aggregation of these substances in emission areas. HCOF were removed from atmosphere by depositions, with total deposition rates of 22.06 g km-1 y-1 in CH, and 1.15 g km-1 y-1 in globe. Under Scenario II with HFO-1234ze emissions of 124.4 Gg/yr as input, annual mixing ratios of HFO-1234ze, CF3CHO and HCOF, along with HCOF total deposition rates were 102.98 26.36 and 17.17 pptv and 217 g km-1 y-1 in China, respectively, increased linearly to HFO-1234ze emissions change. The mixing ratios of HFO-1234ze and HCOF were too small to exert significant effects on current atmosphere burden and circulation, while CF3CHO might potentially involve in aminolysis reaction under future emissions of HFO-1234ze.

Comparison of neonicotinoid residues in soils of different land use types.

Neonicotinoid insecticides (NEOs) have attracted particular attention in recent years due to their wide occurrence and potential impacts on the ecosystem and human health. This study aimed to compare the composition and level of NEOs in soils of different land use types. Two rounds of sampling were performed in Tianjin, China, with 158 soil samples in fall and 61 soil samples in spring collected from five types of land, i.e., greenhouse, orchard, farm, park and residential area. The concentrations of eight NEOs, i.e., imidacloprid (IMI), acetamiprid (ACE), thiamethoxam (THX), clothianidin (CLO), thiacloprid (THA), dinotefuran (DIN), nitenpyram (NIT) and flonicamid (FLO), were analyzed in the soil samples using LC-MS/MS. Six NEOs were detected, with IMI, ACE and THX being the most frequently detected ones. Concentrations of NEOs (arithmetic means in fall and spring, respectively) in greenhouse were the highest (2.52×102 and 4.59×102 ng g-1), followed by in orchard (35.1 and 1.31×102 ng g-1), park (50.4 and 1.02×102 ng g-1), residential area (20.2 and 1.38×102 ng g-1) and farm (25.5 and 84.2 ng g-1). The contribution of individual NEO varied in soils of different land use types. Both IMI and THX were largely used in greenhouse, while IMI was the main NEO in the other four lands. The NEO levels in soils planted with different crops varied greatly. Extremely high levels of NEOs (>103 ng g-1) were observed in soils planted with watermelon, tomato and peach in greenhouse. The ubiquitous presence of NEOs in soils deserves more attention, particularly in greenhouse.

Gas-particle partitioning of carbonyls and its influencing factors in the urban atmosphere of Zhengzhou, China.

Despite their profound roles in atmospheric chemistry and health concerns, the gas-particle partitioning of carbonyl compounds and its influencing factors in the ambient atmosphere are poorly elucidated. In this work, a reliable method using a denuder/filter-pack system coated with the derivative reagent, O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) was developed for the simultaneous collection of gaseous and particulate carbonyls. Sampling campaigns were performed at an urban site in Zhengzhou, China. The average field-derived partitioning coefficients (Kpf) of the six most abundant carbonyls (formaldehyde, acetaldehyde, acetone, propionaldehyde, glyoxal, and methylglyoxal) were in the range of 10-5-10-4 m3·µg-1, and their effective Henry's law coefficients (eff. KH) ranged from 107 to 109 M·atm-1. Comparisons revealed that their Kpf and eff. KH were 104-106 times and 102-107 times higher than theoretically predicted, respectively. Given that the aerosol liquid water is a concentrated salt solution, these six carbonyls very clearly salted in to three atmospherically relevant aqueous salts, following the order of sulfate > ammonium > nitrate. However, even taking salting-in effects into account, the Pankow's absorptive partitioning theory and effective Henry's law both failed to explain the unexpected highly particulate carbonyls. In regard to the influencing factors, the negative correlations between Kpf and temperature indicate that lower temperature is conducive to carbonyls partitioning. As for the strong relative humidity (RH) dependence of KPf, high partitioning coefficients were observed under low and high RH conditions. Partitioning is considered to be dominated by the carbonyl-oligomer formation when RH increases from <10% to 50%, and driven by the abundant aerosol liquid water content when RH exceeds 50%. The presence of particulate inorganic components and the transition of particle phase state may also impact the partitioning process, especially in the urban atmosphere.