Rapid hydrolysis of NO2 at High Ionic Strengths of Deliquesced Aerosol Particles

Nitrogen dioxide (NO2) hydrolysis in deliquesced aerosol particles forms nitrous acid and nitrate and thus impacts air quality, climate, and the nitrogen cycle. Traditionally, it is considered to proceed far too slowly in the atmosphere. However, the significance of this process is highly uncertain because kinetic studies have only been made in dilute aqueous solutions but not under high ionic strength conditions of the aerosol particles. Here, we use laboratory experiments, air quality models, and field measurements to examine the effect of the ionic strength on the reaction kinetics of NO2 hydrolysis. We find that high ionic strengths (I) enhance the reaction rate constants (kI) by more than an order of magnitude compared to that at infinite dilution (kI=0), yielding log10(kI/kI=0) = 0.04I or rate enhancement factor = 100.04I. A state-of-the-art air quality model shows that the enhanced NO2 hydrolysis reduces the negative bias in the simulated concentrations of nitrous acid by 28% on average when compared to field observations over the North China Plain. Rapid NO2 hydrolysis also enhances the levels of nitrous acid in other polluted regions such as North India and further promotes atmospheric oxidation capacity. This study highlights the need to evaluate various reaction kinetics of atmospheric aerosols with high ionic strengths.

Brusatol attenuated proliferation and invasion induced by KRAS in differentiated thyroid cancer through inhibiting Nrf2

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) can be developed from differentiated thyroid cancer, and this dedifferentiated transformation leads to poor prognosis and high mortality. The role of Nrf2 in the dedifferentiation of differentiated thyroid cancer (DTC) induced by KRAS remains unclear.

METHODS AND MATERIALS

In this study, two DTC cell lines, BCPAP and WRO, were used to evaluate the function of Nrf2 in the dedifferentiation caused by wild-type KRAS (KRAS-WT) and G12V point mutation KRAS (KRAS-G12V).

RESULTS

The overexpression of KRAS-WT and KRAS-G12V increased the proliferative and invasive ability of BCPAP and WRO cells. Aggressive morphology was observed in KRAS-WT and KRAS-G12V overexpressed WRO cells. These results suggested that overexpression of KRAS-WT or KRAS-G12V may induce dedifferentiation in DTC cells. The expression of Nrf2 was increased by KRAS-WT and KRAS-G12V in DTC cells. In addition, compared with normal thyroid tissues, the expression of Nrf2 protein was considerably higher in thyroid cancer tissues on immunohistochemistry (IHC) staining, and the increased expression of Nrf2 indicated a poor prognosis of thyroid cancer. These results indicated that Nrf2 is the KRAS downstream molecule in thyroid cancer. Functional studies showed that the Nrf2 inhibitor Brusatol counteracted the proliferative and invasive abilities induced by KRAS-WT and KRAS-G12V in BCPAP and WRO cells. In addition, the xenograft assay further confirmed that Brusatol inhibits tumor growth induced by KRAS-WT and KRAS-G12V.

CONCLUSION

Collectively, this study suggests that Nrf2 could be a promising therapeutic target in KRAS-mediated dedifferentiation of thyroid cancer.

Dissecting Drivers of Ozone Pollution during the 2022 Multicity Lockdowns in China Sheds Light on Future Control Direction

In 2022, many Chinese cities experienced lockdowns and heatwaves. We analyzed ground and satellite data using machine learning to elucidate chemical and meteorological drivers of changes in O3 pollution in 27 major Chinese cities during lockdowns. We found that there was an increase in O3 concentrations in 23 out of 27 cities compared with the corresponding period in 2021. Random forest modeling indicates that emission reductions in transportation and other sectors, as well as the changes in meteorology, increased the level of O3 in most cities. In cities with over 80% transportation reductions and temperature fluctuations within -2 to 2 °C, the increases in O3 concentrations were mainly attributable to reductions in nitrogen oxide (NOx) emissions. In cities that experienced heatwaves and droughts, increases in the O3 concentrations were primarily driven by increases in temperature and volatile organic compound (VOC) emissions, and reductions in NOx concentrations from ground transport were offset by increases in emissions from coal-fired power generation. Despite 3-99% reduction in passenger volume, most cities remained VOC-limited during lockdowns. These findings demonstrate that to alleviate urban O3 pollution, it will be necessary to further reduce industrial emissions along with transportation sources and to take into account the climate penalty and the impact of heatwaves on O3 pollution.

Research on ozone formation sensitivity based on observational methods: Development history, methodology, and application and prospects in China

Observation-based method for O3 formation sensitivity research is an important tool to analyze the causes of ground-level O3 pollution, which has broad application potentials in determining the O3 pollution formation mechanism and developing prevention and control strategies. This paper outlined the development history of research on O3 formation sensitivity based on observational methods, described the principle and applicability of the methodology, summarized the relative application results in China and provided recommendations on the prevention and control of O3 pollution in China based on relevant study results, and finally pointed out the shortcomings and future development prospects in this field in China. The overview study showed that the O3 formation sensitivity in some urban areas in China in recent years presented a gradual shifting tendency from the VOC-limited regime to the transition regime or the NOx-limited regime due to the implementation of the O3 precursors emission reduction policies; O3 pollution control strategies and precursor control countermeasures should be formulated based on local conditions and the dynamic control capability of O3 pollution control measures should be improved. There are still some current deficiencies in the study field in China. Therefore, it is recommended that a stereoscopic monitoring network for atmospheric photochemical components should be further constructed and improved; the atmospheric chemical mechanisms should be vigorously developed, and standardized methods for determining the O3 formation sensitivity should be established in China in the near future.

Measurements of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays from 0.3 to 30 PeV with LHAASO-KM2A

We present the measurements of all-particle energy spectrum and mean logarithmic mass of cosmic rays in the energy range of 0.3-30 PeV using data collected from LHAASO-KM2A between September 2021 and December 2022, which is based on a nearly composition-independent energy reconstruction method, achieving unprecedented accuracy. Our analysis reveals the position of the knee at 3.67±0.05±0.15  PeV. Below the knee, the spectral index is found to be -2.7413±0.0004±0.0050, while above the knee, it is -3.128±0.005±0.027, with the sharpness of the transition measured with a statistical error of 2%. The mean logarithmic mass of cosmic rays is almost heavier than helium in the whole measured energy range. It decreases from 1.7 at 0.3 PeV to 1.3 at 3 PeV, representing a 24% decline following a power law with an index of -0.1200±0.0003±0.0341. This is equivalent to an increase in abundance of light components. Above the knee, the mean logarithmic mass exhibits a power law trend towards heavier components, which is reversal to the behavior observed in the all-particle energy spectrum. Additionally, the knee position and the change in power-law index are approximately the same. These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.

Key toxic components and sources affecting oxidative potential of atmospheric particulate matter using interpretable machine learning: Insights from fog episodes

Fog significantly affects the air quality and human health. To investigate the health effects and mechanisms of atmospheric fine particulate matter (PM2.5) during fog episodes, PM2.5 samples were collected from the coastal suburb of Qingdao during different seasons from 2021 to 2022, with the major chemical composition in PM2.5 analyzed. The oxidative potential (OP) of PM2.5 was determined using the dithiothreitol (DTT) method. A positive matrix factorization model was adopted for PM2.5. Interpretable machine learning (IML) was used to reveal and quantify the key components and sources affecting OP. PM2.5 exhibited higher oxidative toxicity during fog episodes. Water-soluble organic carbon (WSOC), NH4+, K+, and water-soluble Fe positively affected the enhancement of DTTV (volume-based DTT activity) during fog episodes. The IML analysis demonstrated that WSOC and K+ contributed significantly to DTTV, with values of 0.31 ± 0.34 and 0.27 ± 0.22 nmol min-1 m-3, respectively. Regarding the sources, coal combustion and biomass burning contributed significantly to DTTV (0.40 ± 0.38 and 0.39 ± 0.36 nmol min-1 m-3, respectively), indicating the significant influence of combustion-related sources on OP. This study provides new insights into the effects of PM2.5 compositions and sources on OP by applying IML models.

Unveiling the overlooked direct emissions of particulate organic nitrates from ship

Particulate organic nitrates (pONs) have drawn growing interests due to their effects on nitrogen cycling, air pollution, and regional climate. While secondary formation is typically considered as the major source of pONs, direct emissions from various sources remain poorly explored. Ship exhausts have been known as an important source of reactive nitrogen species, yet pONs emissions from ship have been rarely characterized. In this study, we conducted atmospheric measurement of pONs during a ship-based cruise measurement campaign in the East China Sea and also emission measurement of pONs from ship exhausts. During the ship-based cruise, total five typical kinds of pONs were determined and the average total concentrations of five pONs were 479 ± 193 and 250 ± 139 ng m-3 when sampling was influenced by ship emissions or not, respectively, indicating the notable impact of ship exhaust plumes on ambient pONs. Further, five typical pONs were successfully identified and quantified from ship exhausts, with the average total concentration of 1123 ± 406 μg m-3. The much higher pONs levels in ship exhausts than in ambient particulate matters demonstrated ship emission as an important source for pONs. Additionally, their emission factors from ship exhausts were determined as at a range of 0.1-12.6 mg kWh-1. The chemical transport model simulations indicate that direct pONs emissions from ship exert a significant contribution to atmospheric pONs, especially in the clean marine atmosphere. These findings provide compelling evidence for direct emission of pONs from ship and its considerable effects. We call for further studies to better characterize the direct pONs emissions from ship and other potential sources, which should be incorporated into global and regional models.

Mixing state and influence factors controlling diurnal variation of particulate nitrophenol compounds at a suburban area in northern China

Nitrophenols have received extensive attention due to their strong light-absorbing ability in the near-ultraviolet-visible region, which could be influenced by the atmospheric processes of nitrophenols. However, our knowledge and understanding of the formation and evolution of nitrophenols are still in the nascent stages. In the present study, the mixing states of four mononitrophenol particles (i.e., nitrophenol, methynitrophenol, nitrocatechol, and methoxynitrophenol), and one nitropolycyclic aromatic hydrocarbon particles (i.e., nitronaphthol (NN)) were investigated using a single-particle aerosol mass spectrometer (SPAMS) in November 2019 in Qingdao, China. The results showed, for the first time, that mononitrophenols and NN exhibit different mixing states and diurnal variations. Four mononitrophenols were internally mixed well with each other, and with organic acids, nitrates, potassium, and naphthalene. The diurnal variation in the number fraction of mononitrophenols presented two peaks at 07:00 to 09:00 and 18:00 to 20:00, and a valley at noon. Atmospheric environmental conditions, including NO2, O3, relative humidity, and temperature, can significantly influence the diurnal variation of mononitrophenols. Multiple linear regression and random forest regression models revealed that the main factors controlling the diurnal variation of mononitrophenols were photochemical reactions during the day and aqueous-phase reactions during the night. Unlike mononitrophenols, about 62-83% of NN were internally mixed with [NH4]+ and [H(NO3)2]-, but not with organic acids and potassium. The diurnal variation of NN was also different from that of mononitrophenols, generally increased from 17:00 to 10:00 and then rapidly decreaed from 11:00 to 16:00. These results imply that NN may have sources and atmospheric processes that are different from mononitrophenols. We speculate that this is mostly controlled by photochemical reactions and mixing with [NH4]+, which may influence the diurnal variation of NN in the ambient particles; however, this requires further confirmation. These findings extend our current understanding of the atmospheric formation and evolution of nitrophenols.

[Reconsideration of the indications for unicompartmental knee arthroplasty]

Unicompartmental knee arthroplasty (UKA), a procedure that has gradually emerged in recent years, is considered an effective treatment for resolving knee pain and restoring good function due to its significant clinical advantages. In the 1980s, Kozinn and Scott proposed the classic indications as selection criteria to identify ideal candidates for UKA. However, as treatment concepts, surgical instruments, surgical techniques, and prosthesis designs for this disease have improved, these indications proposed more than 30 years ago appear too limited, leading to some limitations in the widespread use of UKA. Specifically, surgeons have offered new perspectives on issues related to obesity, age, patellofemoral arthritis, severe varus deformity of the knee, anterior cruciate ligament deficiency, flexion contracture, failed high tibial osteotomy and post-traumatic arthritis. For this reason, this article will briefly discuss modern perspectives involving the indications for UKA based on current evidence with the aim of providing a reference for the reader.

Comparison of the ozone formation mechanisms and VOCs apportionment in different ozone pollution episodes in urban Beijing in 2019 and 2020: Insights for ozone pollution control strategies

Ground-level ozone (O3) pollution has been a tough issue in urban areas of China in the past decade. Clarifying the formation mechanisms of O3 and the sources of its precursors is necessary for the effective prevention of O3 pollution. In this study, a comparative analysis of O3 formation mechanisms and VOCs apportionment for five O3 pollution episodes was carried out at two urban sites (CRAES and CGZ) in Beijing in 2019 and 2020 by applying an observation-based modeling approach in order to obtain insights into O3 pollution control strategies. Results indicated that O3 pollution levels were generally more severe in 2019 than in 2020 during the observation periods. O3 formation at the two sites was both VOCs-limited on O3 polluted days and non-O3 polluted days. Stronger atmospheric oxidation capacity and ROx radicals cycling processes were found on O3 polluted days which could accelerate the local production of O3, and local photochemical production dominated the observed O3 concentrations at the two sites even on non-O3 polluted days. Emission reduction of VOCs should be a priority for mitigating O3 pollution, and alkenes and biogenic VOCs was the priority species at the CRAES and CGZ sites, respectively. Additionally, the reduction of oxygenated VOCs should also be important for the ozone control. Gasoline exhaust at the CRAES site, and solvent utilization and fuel evaporation at the CGZ site were main anthropogenic sources of VOCs. Therefore, local control measures should be further strengthened and differentiated control strategies of VOCs in the aspects of area, time, sources and species should be adopted in urban Beijing in the future. Overall, the findings of this study could provide a scientific understanding of the causes of O3 pollution and significant guidelines for formulating O3 control strategies from the perspective of different ozone pollution episodes in urban Beijing.

Evolution of Ozone Formation Sensitivity during a Persistent Regional Ozone Episode in Northeastern China and Its Implication for a Control Strategy

In recent years, the magnitude and frequency of regional ozone (O3) episodes have increased in China. We combined ground-based measurements, observation-based model (OBM), and the Weather Research and Forecasting and Community Multiscale Air Quality (WRF-CMAQ) model to analyze a typical persistent O3 episode that occurred across 88 cities in northeastern China during June 19-30, 2021. The meteorological conditions, particularly the wind convergence centers, played crucial roles in the evolution of O3 pollution. Daily analysis of the O3 formation sensitivity showed that O3 formation was in the volatile organic compound (VOC)-limited or transitional regime at the onset of the pollution episode in 92% of the cities. Conversely, it tended to be or eventually became a NOx-limited regime as the episode progressed in the most polluted cities. Based on the emission-reduction scenario simulations, mitigation of the regional O3 pollution was found to be most effective through a phased control strategy, namely, reduction of a high ratio of VOCs to NOx at the onset of the pollution and lower ratio during evolution of the O3 episode. This study presents a new possibility for regional O3 pollution abatement in China based on a reasonable combination of OBM and the WRF-CMAQ model.

Comprehensive understanding on sources of high levels of fine particulate nitro-aromatic compounds at a coastal rural area in northern China

Nitro-aromatic compounds (NACs) are among the major components of brown carbon (BrC) in the atmosphere, causing negative impacts on regional climate, air quality, and ecological health. Due to the extensive origins, it is still a challenge to figure out the contributions and originating regions for different sources of atmospheric NACs. Here, field observations on fine particulate NACs were conducted at a coastal rural area in Qingdao, China in the winter of 2018 and 2019. The mean total concentrations of fine particulate nitro-aromatic compounds were 125.0 ± 89.5 and 27.7 ± 21.1 ng/m3 in the winter of 2018 and 2019, respectively. Among the measured eleven NACs, nitrophenols and nitrocatechols were the most abundant species. Variation characteristics and correlation analysis showed that humidity and anthropogenic primary emissions had significant influences on the NAC abundances. In this study, two tracing methods of the improved spatial concentration weighted trajectory (SCWT) model and the receptor model of positive matrix factorization (PMF) were combined to comprehensively understand the origins of NACs in fine particles at coastal Qingdao. Four major sources were identified, including coal combustion, biomass burning, vehicle exhaust, and secondary formation. Surprisingly, coal combustion was responsible for about half of the observed nitro-aromatic compounds, followed by biomass burning (∼30%). The results by SCWT demonstrated that the coal combustion dominated NACs mainly originated from the Shandong peninsula and the areas to the north and southwest, while those dominated by biomass burning primarily came from local Qingdao and the areas to the west.

[A study on the surgical efficacy of modified laparoscopic levator ani muscle external abdominoperineal resection for the treatment of ultra-low rectal cancer patients]

Objective: Exploring the surgical effectiveness and post-operative recovery of modified laparoscopic levator ani muscle external abdominoperineal resection (L-ELAPE) in the treatment of ultra-low rectal cancer patients. Methods: In a retrospective study conducted at the Oncology Department of Xinxiang Central Hospital and the Fourth Clinical College of Xinxiang Medical University, we analyzed 107 patients with ultra-low rectal cancer who underwent surgical treatment from April 2017 to April 2022. Among them, 54 patients in the modified group were treated using the L-ELAPE technique, while 53 patients in the conventional group underwent the traditional ELAPE surgery. We compared the surgical operation metrics, post-operative pathological results, quality of life, and incidence of complications between the two groups. Results: The age of 54 patients in the modified group was (56.8±7.2) years old, with 53.7% (29 cases) being male; The age of 53 patients in the conventional group was (54.5±5.9) years old, with males accounting for 45.3% (24 cases). There was no statistically significant difference in surgical time between the modified group and the conventional group (P>0.05); The surgical bleeding volume, drainage tube placement time, first postoperative anal exhaust time, and hospitalization time of the modified group patients were (143.2±26.7) ml, (61.9±11.4) h, (5.5±1.6) d, and (10.5±2.2) d, respectively, which were shorter than those in the conventional group's (185.0±31.5) ml, (74.8±14.0) h, (6.4±1.7) d, and (12.2±2.8) d (all P values<0.05). There was no statistically significant difference in postoperative pathological TNM staging, vascular infiltration rate, nerve invasion rate, number of lymph nodes cleaned, and tumor differentiation degree between the two groups of patients (all P values>0.05); The incidence of surgical complications in the modified group was 7.41% (4 cases), lower than that in the conventional group (P<0.05) with 24.53%(13 cases). One month after surgery, the physiological health score of the modified group patients was (35.6±4.7) score, which was higher than the conventional group's (32.8±5.1) score (P<0.05). Conclusion: For patients with ultra-low rectal cancer, the use of the L-ELAPE treatment, compared to conventional methods, can effectively promote post-operative recovery and reduce the rate of surgical complications, which, to some extent, contributes to improving the post-operative quality of life for the patients.

Reduced atmospheric sulfate enhances fine particulate nitrate formation in eastern China

Nitrate (NO3-) is a major component of atmospheric fine particles. Recent studies in eastern China have shown the increasing trend of NO3- in contrast to the ongoing control of nitrogen oxide (NOx). Here, we elucidate the effects of reduced sulfur dioxide (SO2) on the enhancement of NO3- formation based on field measurements at the summit of Mt. Tai (1534 m a.s.l.) and present detailed modelling analyses. From 2007 to 2018, the measured springtime concentrations of various primary pollutants and fine sulfate (SO42-) decreased sharply (-16.4 % to -89.7 %), whereas fine NO3- concentration increased by 22.8 %. The elevated NO3- levels cannot be explained by the changes in meteorological conditions or other related parameters but were primarily attributed to the considerable reduction in SO42- concentrations (-73.4 %). Results from a multi-phase chemical box model indicated that the reduced SO42- levels decreased the aerosol acidity and prompted the partitioning of HNO3 into the aerosol phase. WRF-Chem model analyses suggest that such a negative effect is a regional phenomenon throughout the planetary boundary layer over eastern China in spring. This study provides new insights into the worsening situation of NO3- aerosol pollution and has important implications for controlling haze pollution in China.

Double-Edged Role of VOCs Reduction in Nitrate Formation: Insights from Observations during the China International Import Expo 2018

Aerosol nitrate (NO3-) constitutes a significant component of fine particles in China. Prioritizing the control of volatile organic compounds (VOCs) is a crucial step toward achieving clean air, yet its impact on NO3- pollution remains inadequately understood. Here, we examined the role of VOCs in NO3- formation by combining comprehensive field measurements conducted during the China International Import Expo (CIIE) in Shanghai (from 10 October to 22 November 2018) and multiphase chemical modeling. Despite a decline in primary pollutants during the CIIE, NO3- levels increased compared to pre-CIIE and post-CIIE─NO3- concentrations decreased in the daytime (by -10 and -26%) while increasing in the nighttime (by 8 and 30%). Analysis of the observations and backward trajectory indicates that the diurnal variation in NO3- was mainly attributed to local chemistry rather than meteorological conditions. Decreasing VOCs lowered the daytime NO3- production by reducing the hydroxyl radical level, whereas the greater VOCs reduction at night than that in the daytime increased the nitrate radical level, thereby promoting the nocturnal NO3- production. These results reveal the double-edged role of VOCs in NO3- formation, underscoring the need for transferring large VOC-emitting enterprises from the daytime to the nighttime, which should be considered in formulating corresponding policies.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

Changed mercury speciation in clouds driven by changing cloud water chemistry and impacts on photoreduction: Field evidence at Mt. Tai in eastern China

Chemical speciation of mercury (Hg) in clouds largely determines the photochemistry of Hg in the atmosphere and consequently influences Hg deposition on the surface through precipitation. Cloud water chemistry has notably changed over the last decade in response to global changes, however, the effects on Hg speciation remain poorly understood. During summer 2021, we collected sixty cloud water samples at Mt. Tai in eastern China and compared the cloud chemistry and Hg speciation with our previous findings during summer 2015. The results showed that although there were no statistically significant differences in the concentrations of total Hg (THg), dissolved Hg (DHg), and particulate Hg (PHg), there was a distinct shift in DHg species from the predominated Hg-DOM (78.6% in 2015 campaign) to the more homogeneously distributed Hg(OH)2 (28.4% in 2021 campaign), HgBr2 (26.5%), Hg-DOM (17.3%) and HgBrOH (17.0%). Changes in cloud water chemistry, particularly the significant increase in pH values to 6.49 ± 0.27 and unexpectedly high levels of bromide ions (Br-, 0.19 ± 0.22 mg L-1), were found to drive the changing of Hg speciation by enhancing Hg(II) hydrolysis and binding by Br-. Elevated Br- originating primarily from the continent likely caused noticeable differences in the dominating DHg species between cloud water sourced from marine and continental regions. The changes in chemical speciation of DHg were estimated to result in a 2.6-fold decrease in Hg(II) photoreduction rate between 2015 and 2021 campaigns (0.178 ± 0.054 h-1 vs. 0.067 ± 0.027 h-1), implying a shortened lifetime of atmospheric Hg and increased ecological risks associated with Hg wet deposition.

A Machine Learning Method to Predict Pathological Complete Response of Esophageal Cancer after Neoadjuvant Chemoradiotherapy with Clinicohematological Markers and MR Radiomics: A Multi-Center Study

PURPOSE/OBJECTIVE(S)

Nearly 30% of patients with local advanced esophageal cancer achieved pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT), who may benefit from organ-preservation strategy under accurate prediction of pCR. We aimed to develop and validate machine learning models based on clinicohematological markers and MR radiomics to accurately predict pCR of esophageal cancer after nCRT.

MATERIALS/METHODS

In this multi-center study, eligible patients with esophageal cancer who received baseline MR scan (T2-weighted image) and nCRT plus surgery were enrolled between September 2014 and September 2022 at institution 1 (training set) and between December 2017 and August 2021 at institution 2 (testing set). Pre-nCRT and post-nCRT blood test results were collected to calculate hematological markers. Models were constructed by machine learning based on clinicohematological markers and MR radiomics to predict pCR. Area under the curve (AUC) and cut-off analysis were used to evaluate model performances.

RESULTS

Totally 154 patients (81 in the training set and 73 in the testing set) were enrolled. The combined model integrating pre-nCRT monocyte-to-lymphocyte ratio and 6 radiomics features achieved AUC of 0.800 (95% CI 0.671-0.918) in the testing set, with sensitivity of 79.2% (95% CI 62.5%-95.8%), specificity of 83.7% (95% CI 73.5%-93.9%), positive predictive value of 76.0% (95% CI 62.5%-90.0%), and negative predictive value of 89.6% (95% CI 82.0%-95.8%).

CONCLUSION

A machine learning model based on clinicohematological markers and MR radiomics to predict pCR after nCRT for patients with esophageal cancer was developed and validated, providing a novel tool for personalized treatment. It is necessary to further validate in more large datasets.

Unraveling the O3-NOX-VOCs relationships induced by anomalous ozone in industrial regions during COVID-19 in Shanghai

The COVID-19 pandemic promoted strict restrictions to human activities in China, which led to an unexpected increase in ozone (O₃) regarding to nitrogen oxides (NOx) and volatile organic compounds (VOCs) co-abatement in urban China. However, providing a quantitative assessment of the photochemistry that leads to O₃ increase is still challenging. Here, we evaluated changes in O₃ arising from photochemical production with precursors (NO_X and VOC_S) in industrial regions in Shanghai during the COVID-19 lockdowns by using machine learning models and box models. The changes of air pollutants (O₃, NO_X, VOCs) during the COVID-19 lockdowns were analyzed by deweathering and detrending machine learning models with regard to meteorological and emission effects. After accounting for effects of meteorological variability, we find increase in O₃ concentration (49.5%). Except for meteorological effects, model results of detrending the business-as-usual changes indicate much smaller reduction (-0.6%), highlighting the O₃ increase attributable to complex photochemistry mechanism and the upward trends of O₃ due to clear air policy in Shanghai. We then used box models to assess the photochemistry mechanism and identify key factors that control O₃ production during lockdowns. It was found that empirical evidence for a link between efficient radical propagation and the optimized O₃ production efficiency of NO_X under the VOC-limited conditions. Simulations with box models also indicate that priority should be given to controlling industrial emissions and vehicle exhaust while the VOCs and NO_X should be managed at a proper ratio in order to control O₃ in winter. While lockdown is not a condition that could ever be continued indefinitely, findings of this study offer theoretical support for formulating refined O₃ management in industrial regions in Shanghai, especially in winter.

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at sqrt[s]=510 GeV in p[over →]+p[over →] Collisions

We present measurements of the cross section and double-helicity asymmetry A_{LL} of direct-photon production in p[over →]+p[over →] collisions at sqrt[s]=510  GeV. The measurements have been performed at midrapidity (|η|<0.25) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at sqrt[s]=510  GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range 0.02<x<0.08, with direct sensitivity to the sign of the gluon contribution.

Optical properties and molecular composition of wintertime atmospheric water-soluble organic carbon in different coastal cities of eastern China

To evaluate the optical properties and molecular composition of water-soluble organic carbon (WSOC) in the atmosphere of coastal cities, particle samples were collected in Tianjin, Qingdao and Shanghai, three coastal cities in eastern China. Subsequent analysis by ultraviolet visible and fluorescence spectrometer and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry were performed. The results showed that the concentration levels and light absorption of WSOC decreased from the north to south cities, ranking as Tianjin > Qingdao > Shanghai. Three major fluorescent components including less‑oxygenated humic-like substances (52-60 %), highly‑oxygenated humic-like substances (15-31 %) and protein-like substances (17-31 %) were identified in WSOC based on the fluorescence spectroscopy and parallel factor analysis, which might be closely related to anthropogenic emissions and continental sources as well as secondary formation processes. Five subgroups of molecular components were further identified in WSOC, including the predominant CHON compounds (35-43 %), sulfur-containing compounds (i.e., CHONS and CHOS compounds; 24-43 %), CHO compounds (20-26 %) and halogen-containing compounds (1-7 %). Compared to marine air masses influenced samples, WSOC affected by continental air masses exhibited higher light absorption coefficients and generally had a higher degree of aromaticity and unsaturation, as well as contained more molecular formulas of WSOC, especially enriched with sulfur-containing compounds. In contrast, relatively more abundant halogen-containing compounds were identified in the marine air masses influenced samples. Overall, this study provided new insights into the light-absorbing and chemical properties of WSOC in coastal cities, especially under the influences of continental and marine air masses.

A tera-electron volt afterglow from a narrow jet in an extremely bright gamma-ray burst

Some gamma-ray bursts (GRBs) have a tera-electron volt (TeV) afterglow, but the early onset of this has not been observed. We report observations with the Large High Altitude Air Shower Observatory of the bright GRB 221009A, which serendipitously occurred within the instrument field of view. More than 64,000 photons >0.2 TeV were detected within the first 3000 seconds. The TeV flux began several minutes after the GRB trigger, then rose to a peak about 10 seconds later. This was followed by a decay phase, which became more rapid ~650 seconds after the peak. We interpret the emission using a model of a relativistic jet with half-opening angle ~0.8°. This is consistent with the core of a structured jet and could explain the high isotropic energy of this GRB.

Chemical drivers of ozone change in extreme temperatures in eastern China

Surface ozone pollution has become the biggest issue in China's air pollution since particulate matters have been improved in the atmosphere. Compared with normal winter/summer, extremely cold/hot weather sustained several days and nights by unfavorable meteorology is more impactful in this regard. However, ozone changes in extreme temperatures and their driving processes remain rarely understood. Here, we combine comprehensive observational data analysis and 0-D box models to quantify the contributions of different chemical processes and precursors to ozone change in these unique environments. Analyses of radical cycling indicate that temperature accelerates OH-HO₂-RO₂, optimizing ozone production efficiency in higher temperatures. The HO₂ + NO → OH + NO₂ reaction was the most influenced by temperature change, followed by OH + VOCs → HO₂/RO₂. Although most reactions in ozone formation increased with temperature, the increase in ozone production rates was greater than the rate of ozone loss, leading to a fast net ozone accumulation in heat waves. Our results also show that the ozone sensitivity regime is VOC-limited in extreme temperatures, highlighting the significance of volatile organic compound (VOC) control (particularly the control of alkenes and aromatics). In the context of global warming and climate change, this study helps us deeply understand ozone formation in extreme environments and design abatement policies for ozone pollution in such conditions.

[Research on the cone-beam CT of the fracture morphology and location of a single oblique complicated crown-root fracture of maxillary incisors]

Objective: To study the morphological pattern of single oblique complex crown fracture and its relative location to periodontal hard tissues from a three-dimensional perspective by using cone-beam CT, which provides a more intuitive and comprehensive understanding for the pathological features and rules of single oblique complex crown fracture. Methods: Primary cone-beam CT images of 56 maxillary permanent anterior teeth with oblique complex crown root fractures were collected from the Department of Integrated Emergency Dental Care, Capital Medical University School of Stomatology during January 2015 to January 2019. Fracture pattern, fracture angle, fracture depth, fracture width, and the relative location of the fracture line to the crest of the adjacent alveolar ridge were retrospectively analyzed. Independent samples t-test was used to compare the differences in angle, depth and width of fractures between sexes and tooth locations, as well as the pre-and post-fracture crown-to-root ratios between different tooth locations. Then the affected teeth were divided into juvenile group (≤18 years), young group (19-34 years) and middle-aged and elderly group (≥35 years). One-way ANOVA was applied to compare the differences in angle, depth and width of fracture between age groups, and Fisher exact test to compare the differences in fracture pattern of the teeth and the relative position of the fracture line to the crest of the adjacent alveolar ridge. Results: There were 35 males and 21 females in 56 patients, aged (28.2±13.2) years. Among the 56 affected teeth, forty-six were maxillary central incisors and 10 were lateral incisors. According to the patients' age and growing stage, they could be divided into the juvenile group (19 cases), the young group (14 cases), and the middle-aged and elderly group (23 cases). Forty-six (82%) affected teeth had an S-shaped fracture pattern, and ten (18%) had a diagonal pattern, in which the fracture angle of the S-shaped fracture line (47.85°±10.02°) was significantly greater than that of the diagonal line (28.30°±8.07°) (P<0.001). The fracture nadir was flush with or below the top of the alveolar crest in 98% (55/56) of cases. The fracture depth was significantly greater in the juvenile group [(1.75±0.73) mm] than in the young group [(1.21±0.68) mm](P=0.042) and in the middle-aged and elderly group [(1.12±0.90) mm] (P=0.001). The width of fractures among 56 patients was (4.75±1.44) mm, which had no statistically significant differences between different age, sex and tooth location groups (P>0.05). There were no statistically significant differences in the crown-to-root ratios after fracture of maxillary central incisors (1.18±0.13) compared to maxillary lateral incisors (1.14±0.20) (t=1.90, P=0.373). Conclusions: The fracture patterns of single oblique complex crown fracture were mainly S-shaped and oblique alignment; the fracture nadir was mostly located within 2.0 mm below the palatal alveolar crest.

[Safety and efficacy of the early administration of levosimendan in patients with acute non-ST-segment elevation myocardial infarction and elevated NT-proBNP levels: An Early Management Strategy of Acute Heart Failure (EMS-AHF)]

Objectives: To investigated the safety and efficacy of treating patients with acute non-ST-segment elevation myocardial infarction (NSTEMI) and elevated levels of N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP) with levosimendan within 24 hours of first medical contact (FMC). Methods: This multicenter, open-label, block-randomized controlled trial (NCT03189901) investigated the safety and efficacy of levosimendan as an early management strategy of acute heart failure (EMS-AHF) for patients with NSTEMI and high NT-proBNP levels. This study included 255 patients with NSTEMI and elevated NT-proBNP levels, including 142 males and 113 females with a median age of 65 (58-70) years, and were admitted in the emergency or outpatient departments at 14 medical centers in China between October 2017 and October 2021. The patients were randomly divided into a levosimendan group (n=129) and a control group (n=126). The primary outcome measure was NT-proBNP levels on day 3 of treatment and changes in the NT-proBNP levels from baseline on day 5 after randomization. The secondary outcome measures included the proportion of patients with more than 30% reduction in NT-proBNP levels from baseline, major adverse cardiovascular events (MACE) during hospitalization and at 6 months after hospitalization, safety during the treatment, and health economics indices. The measurement data parameters between groups were compared using the t-test or the non-parametric test. The count data parameters were compared between groups using the χ² test. Results: On day 3, the NT-proBNP levels in the levosimendan group were lower than the control group but were statistically insignificant [866 (455, 1 960) vs. 1 118 (459, 2 417) ng/L, Z=-1.25,P=0.21]. However, on day 5, changes in the NT-proBNP levels from baseline in the levosimendan group were significantly higher than the control group [67.6% (33.8%,82.5%)vs.54.8% (7.3%,77.9%), Z=-2.14, P=0.03]. There were no significant differences in the proportion of patients with more than 30% reduction in the NT-proBNP levels on day 5 between the levosimendan and the control groups [77.5% (100/129) vs. 69.0% (87/126), χ²=2.34, P=0.13]. Furthermore, incidences of MACE did not show any significant differences between the two groups during hospitalization [4.7% (6/129) vs. 7.1% (9/126), χ²=0.72, P=0.40] and at 6 months [14.7% (19/129) vs. 12.7% (16/126), χ²=0.22, P=0.64]. Four cardiac deaths were reported in the control group during hospitalization [0 (0/129) vs. 3.2% (4/126), P=0.06]. However, 6-month survival rates were comparable between the two groups (log-rank test, P=0.18). Moreover, adverse events or serious adverse events such as shock, ventricular fibrillation, and ventricular tachycardia were not reported in both the groups during levosimendan treatment (days 0-1). The total cost of hospitalization [34 591.00(15 527.46,59 324.80) vs. 37 144.65(16 066.90,63 919.00)yuan, Z=-0.26, P=0.80] and the total length of hospitalization [9 (8, 12) vs. 10 (7, 13) days, Z=0.72, P=0.72] were lower for patients in the levosimendan group compared to those in the control group, but did not show statistically significant differences. Conclusions: Early administration of levosimendan reduced NT-proBNP levels in NSTEMI patients with elevated NT-proBNP and did not increase the total cost and length of hospitalization, but did not significantly improve MACE during hospitalization or at 6 months.

Two-year online measurements of volatile organic compounds (VOCs) at four sites in a Chinese city: Significant impact of petrochemical industry

Volatile organic compounds (VOCs) management has been recently given a high priority in China to mitigate ozone (O₃) air pollution. However, there is a relatively poor understanding of VOCs due to their complexity and fewer observations. To better understand the pollution characteristics of VOCs and their impact on O₃ pollution, two-year continuous measurements were conducted at four representative sites in Ji'nan, eastern China. These four sites cover urban, background, and industrial areas (within a petroleum refinery). Ambient VOCs showed higher concentrations at industrial site than at urban and background sites, owing to intensive emissions from petrochemical industry. The VOCs compositions present spatial heterogeneity with alkenes dominated in total reactivity at urban and background sites, while alkenes and aromatics together dominated at industrial site. The VOCs emission profile from petrochemical industry was calculated based on observational data, which revealed a huge impact on light alkanes (C₂-C₅), light alkenes (ethene), and aromatics (toluene and m/p-xylene). The positive matrix factorization (PMF) model analysis further refined the impact of different petrochemical industrial processes. Alkanes and alkenes dominated the emissions during refining process, while aromatics dominated during solvent usage process. Analysis by an observation-based model indicated stronger in-situ O₃ production and higher sensitivity to nitrogen oxides at industrial site compared to urban and background sites. The reduction of VOCs emissions from petrochemical industry would significantly reduce the O₃ concentrations. The analyses underline the significant impact of petrochemical industry on VOCs and O₃ pollution, and provide important reference for the formulation of refined and effective control strategies.

Constraints on Heavy Decaying Dark Matter from 570 Days of LHAASO Observations

The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9}  GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.

Worsening ozone air pollution with reduced NOx and VOCs in the Pearl River Delta region in autumn 2019: Implications for national control policy in China

Ozone (O₃) pollution has emerged as a major air quality issue in China. Here we emphasize the great challenges in controlling O₃ pollution by analyzing the recent experience of the Pearl River Delta (PRD) in southern China in reducing the autumn O₃ peaks. Despite significant reductions in the concentration of O₃ precursors, i.e., nitrogen oxides (NO_x) and volatile organic compounds (VOCs), regional O₃ pollution in the PRD was largely worse in autumn 2019 than in autumn 2018. We found that the supra-regional and regional background concentrations of O₃ increased significantly in the PRD in autumn 2019 due to increased concentrations of O₃ in the vast surrounding areas. We also observed slight increases in the concentrations of PRD-regionally and Guangzhou-locally produced O₃. A chemical box-model analysis confirmed a slight increase in the in-situ production of O₃ and revealed that increased biogenic VOCs (BVOCs) and decreased NO_x levels negated the effect of significant decrease in the anthropogenic VOCs. Taken together, these aspects exacerbated O₃ pollution in the PRD region in autumn 2019 relative to autumn 2018. The findings from this study highlight the strong interactions of O₃ pollution over multiple regions and the need for collaborative inter-regional efforts to control O₃ pollution. The experience of PRD also underlines the key role of BVOCs and the importance of science-based strategies to decrease VOCs and NO_x.

Does Ozone Pollution Share the Same Formation Mechanisms in the Bay Areas of China?

As important regions of transition between land and sea, the three bay areas of Bohai Bay (BHB), Hangzhou Bay (HZB), and Pearl River Estuary (PRE) in China often suffer from severe photochemical pollution despite scarce anthropogenic emissions. To understand the causes of high ozone (O₃) concentrations, the high O₃ episode days associated with special synoptic systems in the three bays were identified via observations and simulated by the weather research and forecasting coupled with community multiscale air quality (WRF-CMAQ) model. It was revealed that the interaction between synoptic winds and mesoscale breezes resulted in slow wind speeds over the HZB and PRE, where air pollutants transported from upwind cities gained a long residence time and subsequently participated in intensive photochemical reactions. The net O₃ production rates within the bay areas were even comparable to those in surrounding cities. This finding was also applicable to BHB but with lower net O₃ production rates, while high levels of background O₃ and the regional transport from farther upwind BHB partially elevated the O₃ concentrations. Hence, these three bay areas served as O₃ "pools" which caused the accumulation of air pollutants via atmospheric dynamics and subsequent intense photochemical reactions under certain meteorological conditions. The results may be applicable to other similar ecotones around the world.

Seed germination traits and dormancy classification of 27 species from a degraded karst mountain in central Yunnan-Guizhou Plateau: seed mass and moisture content correlate with germination capacity

In degraded karst ecosystem, vegetation restoration efforts almost exclusively rely on planted seedlings, but this is not effective to maintain community diversity and resilience. As seed functional traits, seed dormancy and germination are key to community assembly. Unfortunately, these elements are commonly overlooked in restoring degraded ecosystems. This work classifies seed dormancy of 27 species with different life forms that are common on a degraded karst mountain. We examined the effects of temperature regime and light conditions on percentage germination and assessed the relationships between seed traits and germination index using a partial least squares regression (PLSR). Approximately 48% of the investigated species had physiological dormancy, 37% were non-dormant, 7% had morphophysiological dormancy, 4% had morphological dormancy and 4% had physical dormancy. We found that 94% (15 out of 16) species had maximum germination in warm temperature regimes (20/13 and 25/18 °C), while the remaining species required cool temperatures (10/4 °C). PLSR analysis indicated a significant positive correlation between seed mass and T_50m (time to 50% final germination), and a negative correlation between seed moisture content and percentage germination. Our findings indicate that seed traits are important factors in seed-based restoration practice. F. esculentum, O. opipara, P. fortuneana and S. salicifolia are recommended for direct seeding during the early rainy season to restore seriously degraded lands in subtropical karst regions.

Large contributions of anthropogenic sources to amines in fine particles at a coastal area in northern China in winter

Amines in fine particles constitute a significant fraction of secondary organic aerosols and have adverse effects on air quality and human health. To understand the chemical composition, variation characteristics, and potential sources of fine particulate amines in the coastal area in northern China, field sampling and chemical analysis were conducted in coastal Qingdao in the winter of 2018 and 2019. A total of 15 major amines were identified and quantified by using an ultra-high-performance liquid chromatography coupled with mass spectrometry. The average concentration of total amines in PM_2.5 samples was approximately 130 ng m^-3. Dimethylamine was the most abundant species with average fractions of 44.8% and 65.0% in the quantified amines during the two field campaigns, followed by triethylamine (22.9% and 8.7%) and methylamine (8.3% and 4.4%). The amines in PM_2.5 usually exhibited elevated concentrations in the presence of high levels of SO₂ and NO_x or in the condition of high relative humidity. A receptor model of positive matrix factorization was employed and seven major sources were identified, including coal combustion, industrial production, vehicle exhaust, biomass burning, agricultural activities, secondary formation, and marine emission. Surprisingly, most of 15 amines in fine particles primarily originated from the primary emissions of anthropogenic activities particularly related to coal combustion and industrial productions, which should be given close concern to address the amine pollution.

Effects of coal chemical industry on atmospheric volatile organic compounds emission and ozone formation in a northwestern Chinese city

Coal is well known as the primary energy consumption in China, and the coal chemical industry (CCI) can serve as an important source of volatile organic compounds (VOCs) emissions. However, the characteristics of VOCs emitted from CCI along with their environmental consequences are still poorly understood. To pin down this, an intensive field campaign was carried out at a typical CCI city in northwestern China (Yulin) from February 26 to March 7, 2021. Results showed that VOC compositions in Yulin were distinct from those in the megacities of China as well as in the typical oilfields over the world. The concentration of naphthalene (1.6 ± 1.1 ppbv), an important byproduct of CCI, was significantly higher than that in other cities (<0.2 ppbv). Positive matrix factorization (PMF) model analysis revealed that the direct contribution of the CCI source for VOC emissions is 8.8 ± 1.8%. More importantly, these VOCs emitted from the CCI can account for 17.9 ± 6.8% of ozone (O₃) formation potential and 16.9 ± 7.4% of OH reactivity of VOCs, suggesting the significant impacts of the CCI on the air quality and atmospheric oxidizing capacity. During the observation, a rapid increase in O₃ concentration after a snowfall was encountered. The changing rate of O₃ concentration in the daytime was significantly higher than in its peripheral cities. The increased O₃ formation was partially attributed to the CCI, and this enhancement can be further magnified by snow cover due to the increment of surface albedo. These findings deepen the understanding of the characteristics and air quality impact of VOCs related to the CCI and provide valuable insights for the development of air quality control measures in the region influenced by intensive coal chemical production.

Particulate organic nitrates at Mount Tai in winter and spring: Variation characteristics and effects of mountain-valley breezes and elevated emission sources

Particulate organic nitrates, among the major components of secondary organic aerosols and fine particles, play important roles in regional nitrogen cycle, ozone budget, and cloud condensation nuclei formation. However, the pollution characteristics of particulate organic nitrates at mountain areas and the effects of anthropogenic pollutant transport remain poorly understood. In this study, field sampling and measurements were conducted at a high-elevation mountain site over North China Plain in winter and spring. Total five kinds of particulate organic nitrates in fine particles were determined by ultra-high performance liquid chromatography-electrospray mass spectrometry. The average total concentrations of particulate organic nitrates were 330 ± 121 ng m^-3 and 247 ± 63 ng m^-3 in winter and spring. The monoterpene-derived organic nitrates were the dominant components in both seasons with their contribution higher than 70%, accounting for 1.2 ± 0.8% and 2.0 ± 1.0% in organic aerosols in winter and spring, respectively. The significantly higher levels of particulate organic nitrates in winter than spring was ascribed to the strong effects of mountain-valley breezes and coal combustion plumes. The increasing concentrations of NO_x and particulate matters brought by the valley breeze at daytime facilitated the formation of MHN215, OAKN359, and OAHN361, while the rising SO₂ abundance and the sulfate aerosols transported by elevated emission sources affected the formation of MDCN247 at nighttime.

[Relationship between simple renal cyst and adverse events in patients receiving thoracic endovascular aortic repair for Stanford B aortic dissection]

Objective: To explore the prognostic value of simple renal cyst (SRC) for adverse events in patients receiving thoracic endovascular aortic repair (TEVAR) for Stanford B aortic dissection (TBAD). Methods: This study is a retrospective cohort study. Consecutive patients receiving TEVAR for TBAD between January 2010 and December 2015 were enrolled in this study. The patients were divided into SRC group and non-SRC group. With sex and age ±2 years old as matching factors, SRC group and non-SRC group were matched by 1∶1. Collect and compare the differences of clinical data between the two groups. Adverse events were recorded through outpatient, telephone follow-up and in-hospital review. After adjusting for confounding factors, multivariate Cox regression was used to analyze the risk factors of aortic adverse events. Kaplan-Meier method was used to analyze the survival curve of SRC group and non-SRC group. Results: A total of 692 consecutive patients were recruited. Patients were divided into SRC group (n=235) and non-SRC group (n=457). After 1∶1 matching, there were 229 cases in SRC group and no SRC group respectively. The age of SRC group was (62.3±10.4) years old, 209 cases were male (91.3%), and the age of no SRC group was (62.0±10.2) years old, 209 cases were male (91.3%). Cox regression analysis showed that, after adjusting for confounding factors, comorbid SRC (HR=1.991, 95%CI: 1.090-3.673, P=0.025), TEVAR in the acute phase (HR=13.635, 95%CI: 5.969-31.147, P=0.001), general anesthesia (HR=2.012, 95%CI: 1.066-3.799, P=0.031) are independent factors of aortic-adverse events after TEVAR for TBAD. Kaplan-Meier analysis showed that the cumulative survival rate of SRC group was significantly lower than non-SRC group (log-rank P=0.031, 0.005). Conclusion: SRC is an independent predictor of aortic-related adverse events in patients following TEVAR for TBAD.

[Differential diagnosis and management of hemangioma at geniculate ganglion]

Objective: To investigate the clinical characteristics, differential diagnosis, treatments and prognosis of facial nerve hemangioma and schwannoma at genicular ganglion, so as to provide reference for clinical diagnosis and treatments of facial nerve tumor at genicular ganglion. Methods: Clinical data of 13 patients with facial nerve tumors at genicular ganglion confirmed by postoperative pathology in the Ninth People's Hospital affiliated to Shanghai Jiaotong University School of Medicine from March 2018 to April 2020 were retrospectively analyzed, including seven cases of hemangioma and six cases of schwannoma. There were eight males and five females. Their ages ranged from 20 to 65, with an average age of 40. The course of disease ranged from 3 to 118 months, with an average of 52 months. All the patients underwent preoperative HRCT of the temporal bone and facial nerve dynamic contrast-enhanced(DCE) MRI examinations. All the patients had detailed surgical procedures and at least one-year postoperative follow-up. Results: On HRCT of the temporal bone, (4/7) hemangioma at geniculate ganglion showed characteristic honeycomb appearance, while 6/6 schwannoma and 3/7 hemangiomas showed expansive bone changes. On DCE-MRI, geniculate ganglion hemangioma (7/7) showed characteristic "point-to-surface" enhancement, and schwannoma (6/6) showed characteristic "face-to-surface" enhancement. For five hemangioma-patients with HB-Ⅱ-Ⅳ before surgery, the facial nerve anatomy was completely preserved through transcanal endoscopic approach(TEA), and the facial nerve function improved one year after surgery (two cases of HB-I, two cases of HB-Ⅱ, and one case of HB-Ⅲ). For two patients, with preoperative facial nerve function HB-Ⅴ-Ⅵ, since their tumors was inseparable from the nerves, they were performed with facial nerve anastomosis during the surgery, and the facial nerve function was improved to HB-Ⅳ level one year after surgery. For six patients with meningioma whose facial nerve function was greater than or equal to HB-Ⅲ, based on the preoperative hearing level, the involved segments, and duration of facial paralysis, three of them were conducted surgeries through middle cranial fossa approach, one by translabyrinthine approach, and one via mastoid approach. Two patients among them with complete facial paralysis over three years preoperatively were not performed facial nerve anastomosis after total resections of the tumors, and there was no improvement in facial nerve function one year after surgery. Three patients underwent facial nerve anastomosis after total tumor resections, and their facial nerve function was HB-Ⅲ in one patient, HB-Ⅳ in two patients one year after surgery. One patient (preoperative HB-Ⅲ) had a normal hearing level preoperatively, and the tumor involved the labyrinth segment. To protect the hearing, partial tumor was resected through the middle cranial fossa approach, and facial nerve function improved to HB-Ⅱ one year after surgery. Conclusions: Temporal bone HRCT combined with DCE-MRI are useful for the differential diagnosis of hemangioma and schwannoma at geniculate ganglion and provide references for preoperative clinical decision makings. It is extremely necessary to select the appropriate surgical approach based on the patient's hearing and involved segments. For geniculate ganglion hemangioma, early surgery can improve the possibilities of anatomical integrity of facial nerve, thereby improving facial nerve function postoperatively.TEA is a kind of surgical method worth consideration, with the characteristics of minimally invasive, favorable postoperative features, and so on. For schwannoma, one-stage functional reconstruction of the facial nerve is recommended during the resection of the tumors because of the inevitable damage to the anatomical integrity of the facial nerve.

O-008 Low grade blastocysts result in healthy live births and should not be discarded

Study question

Does transfer of low grade blastocysts results in acceptable live birth rates the birth of healthy babies?

Summary answer

While BC/CB/CC blastocysts have a reduced chance of live birth compared with AA/AB/BA/BB blastocysts, the absolute chances are still reasonable.

What is known already

Transfer of poorer quality embryos and blastocysts result in lower live birth rates, though to what extent is unclear, nor if there is an absolute threshold below which live births are very rare or even do not occur. Further, the developmental competence of the inner cell mass (ICM) or trophectoderm (TE) could at least theoretically impact the pregnancy and/or the health of the baby. Many clinics do not transfer or freeze poor quality embryos and blastocysts, and prefer to submit the patient to a further stimulation cycle.

Study design, size, duration

We performed a retrospective analysis of 10,978 couples undergoing singleton blastocyst transfers between 2009 and March 2020. We included all single blastocyst transfers for which there was complete data on blastocyst quality, singleton or twin births, birthweight and gestation at delivery, irrespective of blastocyst grading, female age, cause of infertility, ovarian response or endometrial thickness. We recorded live birth rates, birth weight and gestational age.

Participants/materials, setting, methods

Data from 14 clinics in 3 countries, 8 from China, 5 from New Zealand, and 1 from Australia were included in the final dataset. We compared the impact of blastocyst grading using multiple logistic regression. Blastocyst grading was based on the Gardner classification, in which the first letter denotes the grade of the inner cell mass (A is best), and the second letter the grade of the trophectoderm.

Main results and the role of chance

Overall, 10,978 single blastocyst cycles resulted in 4,261 live births (38.8%) (4195 singletons and 132 twins). Live birth rates were 47% after transfer of AA blastocysts (n = 2306); 42% after AB/BA (n = 2088); 33% after BC (n = 1973); 25% after CB (n = 715) and 14% after CC (n = 117). There were too few AC (n = 27) or CA (n = 12) blastocysts to include in the analysis. The odds of live birth for BC/CB/CC blastocysts compared with AA/AB/BA blastocysts, vary between 0.8 and 0.9.

The live birth rate appears to be more dependent on ICM quality (C grade, n = 844, 23.2%) rather than TE quality (C grade, n = 2117, 32.1%), with the odds of live birth 0.43 and 0.57 respectively compared to A grade ICM or TE.

The average birth weight (singleton only) was 3336.9+/-570.3 g (range 3323 to 3386 g), and the average gestation at delivery (singleton only) was 38+6+/-2.0 weeks (range 38+2 to 39+1). There was no significant difference for birth weight or gestational age at delivery between blastocysts of different grades.

Limitations, reasons for caution

This was a retrospective study. Grading was based on inner cell mass and trophectoderm and not on degree of expansion, or on day of transfer.

It is likely that higher quality blastocysts were transferred first, in a fresh cycle, and poorer quality blastocysts frozen for later transfer.

Wider implications of the findings

The most important finding is that reasonable live birth rates are obtained in CC-blastocysts.

We therefore advocate that CC-blastocysts should be replaced or frozen for later transfer. It is reassuring that there was no impact of blastocyst quality on birth weights or gestational age at the time of delivery.

Trial registration number

Not applicable

Nitrous acid in the polluted coastal atmosphere of the South China Sea: Ship emissions, budgets, and impacts

Nitrous acid (HONO) can significantly contribute to hydroxyl radicals (OH) and thus regulate atmospheric oxidation chemistry; however, ambient HONO sources are not well quantified and vary in different environments. In this study, we conducted comprehensive field observations at a coastal site in the South China Sea and performed chemical box modelling to demonstrate contrasting budgets and impacts of diurnal atmospheric HONO derived from the sea, coastline and continent. The ship emission ratio of HONO/nitrogen oxides (NO_x) (1.21 ± 0.99%) was calculated from hundreds of night-time fresh plume measurements. Offshore marine air was frequently influenced by ship exhausts, and the sea acted as an HONO sink. Heterogeneous conversions of nitrogen dioxide (NO₂) on underlying surfaces and photolysis of adsorbed nitric acid (HNO_3(ads)) were the major HONO sources in coastal air, when heterogeneous NO₂ conversions on the ground surface and the homogeneous NO + OH reaction dominated HONO formation in continental air. HONO photolysis was a significant source of reactive radicals (RO_x = OH + HO₂ + RO₂) in these air masses. Atmospheric box model including only homogeneous HONO source of the NO + OH reactions significantly underpredicted the OH concentration and atmospheric oxidising capacity in coastal and continental air. This study provides new insights into the complex sources and significant impacts of HONO in the polluted coastal boundary layer.

Investigating the sources of atmospheric nitrous acid (HONO) in the megacity of Beijing, China

Nitrous acid (HONO) can powerfully influence atmospheric photochemistry by producing hydroxyl radical (OH), which is a crucial oxidant that controls the fate of atmospheric trace species. To deduce HONO formation mechanisms in polluted regions, two field observations were conducted in urban Beijing during the early summer of 2017 and the winter of 2018. These two seasons bore distinguishing pollution characteristics with a higher degree of ageing and heavier aerosol loading in the early summer and more abundant NO_x (NO_x = NO + NO₂) in the winter. Elevated concentrations of HONO were observed during these two seasons, with the mean ± standard deviation (maximum) concentrations of 1.25 ± 0.94 (6.69) ppbv and 1.04 ± 1.27 (9.55) ppbv in early summer and winter, respectively. The observed daytime (08:00-17:00 h, local time) HONO production rate was several times higher in early summer than in winter (4.44 ± 1.93 ppbv h^-1 vs. 0.88 ± 0.49 ppbv h^-1). Budget analysis revealed distinct daytime HONO formation mechanisms during these two seasons. Photo-induced heterogeneous conversion of NO₂ on the ground surface dominated in early summer, and homogeneous reaction of NO + OH was dominant in winter. Photolysis of HONO was the major source of primary OH in both seasons, and thus, played a key role in the regulation of atmospheric oxidising capacity. This study demonstrates the significant seasonal variations in HONO budget and underlines the predominant role of HONO in primary OH production in Beijing. Our findings will be helpful to gain an understanding of the chemical mechanisms underlying the formation of secondary pollution in metropolitan areas.

Exploring Lorentz Invariance Violation from Ultrahigh-Energy γ Rays Observed by LHAASO

Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.

[Analysis of molecular and clinical characteristics of carbapenem-resistant hypervirulent Klebsiella pneumoniae in the intensive care unit]

To investigate the carbapenemases distribution of carbapenem-resistant Klebsiella pneumoniae (CRKP) in the intensive care unit, and the clinical characteristics between carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) and carbapenem-resistant non-hypervirulent Klebsiella pneumoniae (CR-non-hvKP) were compared. A total of 53 non-repetitive CRKP strains isolated from 49 patients in the intensive care unit of the Second Affiliated Hospital of Xi'an Jiaotong University from May 2020 to March 2021 were retrospectively studied. The carbapenemase inhibitor enhancement test was used for screening carbapenemase-producing strains, and the string test was carried out to screen the hypermucoviscosity phenotype. Using PCR to detect five main carbapenemase genes (bla_KPC-2, bla_NDM, bla_IMP , bla_VIM and bla_OXA-48-like), common serotype (K1 and K2) and virulence gene (rmpA and iutA). Treated the strains with both rmpA and iutA genes as hypervirulent Klebsiella pneumonia (hvKP), and the whole genome sequencing of CR-hvKP was completed. At the same time, the clinical data of 49 patients were sorted out, and the differences in clinical characteristics of CR-hvKP and CR-non-hvKP infected patients were compared using the independent sample t test, Mann-Whitney U test, chi-square test or Fisher's exact probability test. CRKP isolated from the intensive care unit were extensively drug resistance and still had a good sensitivity to polymyxin B and tigecycline. Producing carbapenemases were the main resistance mechanism of CRKP (52/53, 98.1%). Of the 53 CRKP strains, except for 1strain that did not detect carbapenemase, at least one carbapenemase resistance gene was detected in the remaining 52 CRKP strains, of which 45 strains carried an enzyme, including 36 bla_KPC-2 (36/53, 67.9%), 8 bla_NDM (8/53, 15.1%), 1 bla_IMP (1/53, 1.9%), and 7 strains carried with both bla_KPC-2 and bla_NDM (7/53, 13.2%). String test and virulence gene showed that 7 CR-hvKP strains (13.2%) were detected in 53 CRKP strains, and two of which were hypermucoviscosity phenotype. Sequencing results revealed that CR-hvKP were mainly ST11 type. Almost all patients with CR-hvKP infection were over 60 years old (7/7), with invasive treatment (7/7), pulmonary infection with hypermucoviscosity phenotype (2/7) and high mortality (5/7); and the percentage of neutrophils in patients with CR-hvKP infection (86.44±4.70) % was higher than those patients with CR-non-hvKP infection (78.90±19.15) %, the difference was statistically significant (t=-2.225, P=0.032). The CR-hvKP strains in the intensive care unit mainly produced KPC-2 enzyme, with K2 capsular serotype and ST11 type. It is necessary to strengthen the monitoring and control of the CR-hvKP strain to prevent the co-evolution of drug-resistant and hypervirulent strains.

An unexpected large continental source of reactive bromine and chlorine with significant impact on wintertime air quality

Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of 'conventional' tropospheric oxidants (OH, HO₂ and RO₂) by 26%-73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent.

Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p^{↑}+p Collisions at sqrt[s]=200 GeV

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p^{↑}+p collisions at sqrt[s]=200  GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

Heavy ozone pollution episodes in urban Beijing during the early summertime from 2014 to 2017: Implications for control strategy

Ground-level ozone (O₃) has become the principal air pollutant in Beijing during recent summers. In this context, an investigation of ambient concentrations and variation characteristics of O₃ and its precursors in May and June from 2014 to 2017 in a typical urban area of Beijing was carried out, and the formation sensitivity and different causes of heavy O₃ pollution (HOP, daily maximum 8-h O₃ (MDA8h O₃)>124 ppbv) were analyzed. The results showed that the monthly assessment values of the O₃ concentrations (the 90^th percentile MDA8h O₃ within one month) were highest in May or June from 2014 to 2017, and the values presented an overall increasing trend. During this period, the number of O₃ pollution days (MDA8h O₃ > 75 ppbv) also showed an increasing trend. During the HOP episodes, the concentrations of volatile organic compounds (VOCs), nitrogen oxides (NO_X), and carbon monoxide (CO) were higher than their respective mean values in May and June, and the meteorological conditions were more conducive to atmospheric photochemical reactions. The HOP episodes were mainly caused by local photochemical formation. From 2014 to 2017, O₃ formation during the HOP episodes shifted from VOC and NO_X mixed-limited to VOC-limited conditions, and O₃ formation was most sensitive to anthropogenic VOCs. Six categories of VOC sources were identified, among which vehicular exhaust contributed the most to anthropogenic VOCs. The VOC concentrations and OFPs of anthropogenic sources have decreased significantly in recent years, indicating that VOC control measures have been effective in Beijing. Nevertheless, NO_X concentrations did not show an evident decreasing trend in the same period. Therefore, more attention should be devoted to O₃ pollution control in May and June; control measure adjustments are needed according to the changes in O₃ precursors, and coordinated control of VOCs and NO_X should be strengthened in long-term planning.