Efficacy and safety of pericapsular nerve group block in total hip arthroplasty: a meta-analysis and systematic review.

INTRODUCTION: Ensuring effective perioperative pain control is a crucial aspect of rehabilitation programs following total hip arthroplasty. This study presents a comprehensive meta-analysis and systematic review to assess the efficacy and safety of pericapsular nerve group block (PENG) in the context of total hip arthroplasty. EVIDENCE ACQUISITION: A systematic search was conducted in multiple databases, including PubMed, Embase, Cochrane Library, and Web of Science, to identify relevant randomized controlled studies investigating the efficacy and safety of PENG for total hip arthroplasty. The search was conducted up until 1st June 2023. Data analysis was performed using Stata v. 15.0. EVIDENCE SYNTHESIS: A total of 721 individuals participated in this study, which included 13 randomized controlled trials. Among them, 377 individuals were assigned to the experimental group, while 344 individuals were assigned to the control group. The findings from the meta-analysis indicated that the application of PENG yielded favorable outcomes in terms of reducing six-hour pain scores (SMD=-0.63, 95% CI -1.18, -0.09) and 24-hour pain scores (SMD=-1.45, 95% CI -2.51, -0.29). Moreover, it was found to decrease opioid consumption (SMD=-0.84, 95% CI -1.35, -0.34), without causing a significant increase in nausea and vomiting (RR=0.75, 95% CI 0.45, 1.23) or urinary retention (RR=2.46, 95% CI 0.49, 12.31). CONCLUSIONS: Based on the latest findings, PENG has been shown to effectively decrease pain scores within six and 24 hours following total hip arthroplasty. However, its effectiveness in pain control diminishes after 48 hours. Additionally, PENG has demonstrated the ability to reduce opioid consumption without an accompanying increase in adverse drug events.

System pharmacology-based determination of the functional components and mechanisms in chronic heart failure treatment: an example of Zhenwu decoction.

Chronic heart failure (CHF) is the primary cause of death among patients with cardiovascular diseases, representing the advanced stage in the development of several cardiovascular conditions. Zhenwu decoction (ZWD) has gained widespread recognition as an efficacious remedy for CHF due to its potent therapeutic properties and absence of adverse effects. Nevertheless, the precise molecular mechanisms underlying its actions remain elusive. This study endeavors to unravel the intricate pharmacological underpinnings of five herbs within ZWD concerning CHF through an integrated approach. Initially, pertinent data regarding ZWD and CHF were compiled from established databases, forming the foundation for constructing an intricate network of active component-target interactions. Subsequently, a pioneering method for evaluating node significance was formulated, culminating in the creation of core functional association space (CFAS). To discern vital components, a novel dynamic programming algorithm was devised and used to determine the core component group (CCG) within the CFAS. Enrichment analysis of the CCG targets unveiled the potential coordinated molecular mechanisms of ZWD, illuminating its capacity to ameliorate CHF by modulating genes and related signaling pathways involved in pathological remodeling. Notable pathways encompass PI3K-Akt, diabetic cardiomyopathy, cAMP and MAPK signaling. Concluding the computational analyses, in vitro experiments were executed to assess the effects of vanillic acid, paradol, 10-gingerol and methyl cinnamate. Remarkably, these compounds demonstrated efficacy in reducing the production of ANP and BNP within isoprenaline-induced AC 16 cells, further validating their potential therapeutic utility. This investigation underscores the efficacy of the proposed model in enhancing the precision and reliability of CCG selection within ZWD, thereby presenting a novel avenue for mechanistic inquiries, compound refinement and the secondary development of TCM herbs.

Direct emissions of particulate glyoxal and methylglyoxal from biomass burning and coal combustion.

Glyoxal (Gly) and methylglyoxal (Mgly) are key precursors globally for secondary organic aerosol (SOA) formation. These two species were often thought to be formed in the atmosphere via photochemical oxidation of organics from biogenic and anthropogenic origins, although few studies have shown their direct emissions. In this study, we report direct emissions of particulate Gly and Mgly from different residential fuels typically used in north China. The emission ratios (ERs) and emission factors (EFs) of particulate Gly and Mgly for biomass burning were approximate 5-fold and 7-fold higher than those for coal combustion, respectively. The large variances in emissions of Gly and Mgly could be attributed to the different combustion processes, which influenced by the fuel types and combustion conditions. The averaged ERs and EFs of particulate Gly and Mgly were about one order of magnitude lower than their gaseous counterparts due to the low Henry's law constant, which was also consistent with the low particle-to-gas ratio of Gly (0.04) and Mgly (0.02). Our results suggest that the direct emissions of Gly and Mgly from emission sources should be considered when estimating the formation of SOA from Gly and Mgly.

Comparison of the efficacy of costoclavicular space brachial plexus blockade with 0.5% versus 0.375% ropivacaine: a randomized, double-blind, single-centre, noninferiority clinical trial.

PURPOSE: Recently, more attention has been given to the costoclavicular space (CCS) as an alternative pathway for ultrasound-guided brachial plexus block (BPB). While 0.5% ropivacaine was used in most related studies, research has shown effective ultrasound-guided supraclavicular BPB using lower local anesthetic concentrations, and our preliminary data have indicated that 0.375% ropivacaine may be effective when given in the CCS. Hence, we hypothesized that the efficacy of 0.375% ropivacaine would be noninferior compared with 0.5% in ultrasound-guided BPB via the CCS. METHODS: We conducted a randomized, double-blind, single-centre, noninferiority clinical trial. Seventy patients undergoing elective forearm or hand surgery were randomly assigned to receive either 20 mL of 0.375% ropivacaine (experimental group) or 0.5% ropivacaine (control group) in the CCS for BPB. We assessed sensory and motor blockade at five, ten, 15, 20, 25, and 30 min after the injection. The primary outcome was the rate of successful BPB. Secondary outcomes included onset time, duration of sensory and motor blockade, and adverse reactions. The depth from the skin to the CCS was also recorded during the procedure. RESULTS: A total of 69 patients were evaluable for block success. There was one failed block in both groups, yielding a BPB block success rate of 97% in both groups. 0.375% Ropivacaine was noninferior to 0.5% ropivacaine (P = 0.98). There was no significant difference in the median [interquartile range (IQR)] onset time of sensory-motor blockade in the experimental group (15 [15-20] min; N = 34) compared with the control group (15 [13-20] min; N = 33; Mann-Whitney test, P = 0.48). The median [IQR] duration of sensory blockade was significantly shorter in the experimental group (455 [398-490] min vs 610 [570-655] min in the control group; Hodges-Lehmann estimator of the difference, 165 min; 95.08% confidence interval (CI), 130 to 195; P < 0.001). Likewise, the median [IQR] duration of motor blockade was significantly shorter in the experimental group (470 [409-500] min vs 625 [578-665] min in the control group; Hodges-Lehmann estimator of the difference, 165 min; 95.08% CI, 130 to 195; P < 0.001). There were no adverse reactions directly related to the technique or the ropivacaine injection in either group. CONCLUSIONS: 0.375% Ropivacainewas noninferior to 0.5% ropivacaine with regard to rate of successful ultrasound-guided costoclavicular BPB. STUDY REGISTRATION: chictr.org.cn (ChiCTR20000306570); registered 8 March 2020.

RéSUMé: OBJECTIF: L'espace costo-claviculaire (ECC) a récemment bénéficié d'un regain d'intérêt comme voie de substitution pour le bloc du plexus brachial (BPB) échoguidé. La ropivacaïne 0,5 % a été utilisée dans la majorité des études sur ce sujet, mais la recherche a montré un BPB supra-claviculaire échoguidé efficace en utilisant de plus faibles concentrations d'anesthésique local et nos données préliminaires ont indiqué que la ropivacaïne à 0,375 % pouvait être efficace en administration dans l'ECC. En conséquence, nous avons émis l'hypothèse selon laquelle l'efficacité de la ropivacaïne 0,375 % serait non inférieure à la ropivacaïne 0,5 % dans le BPB échoguidé via l'ECC. MéTHODES: Nous avons mené un essai clinique monocentrique de non-infériorité, randomisée en double insu. Soixante-dix patients subissant une chirurgie élective de l'avant-bras ou de la main ont été randomisés dans un groupe recevant 20 mL de ropivacaïne 0,375 % (groupe expérimental) ou de ropivacaïne 0,5 % (groupe contrôle) dans l'ECC pour un BPB. Nous avons évalué les blocs sensoriel et moteur à 5, 10, 15, 20, 25 et 30 minutes après l'injection. Le critère d'évaluation principal était le taux de succès du BPB. Les critères d'évaluation secondaires étaient, notamment, le délai d'action, la durée des blocs sensoriel et moteur, et les événements indésirables. La profondeur de la peau à l'ECC a aussi été consignée pendant la procédure. RéSULTATS: Un total de 69 patients était évaluable pour le succès du bloc. Il y a eu un échec du bloc dans chacun des deux groupes, ramenant le taux de succès du BPB à 97 % dans les deux groupes. La ropivacaïne 0,375 % a été non inférieure à la ropivacaïne 0,5 % (P = 0,98). Il n'y a pas eu de différence significative concernant le délai d'action médian (plage interquartile [PIQ]) du bloc sensori-moteur dans le groupe expérimental (15 [15 à 20] minutes; n = 34) comparativement au groupe contrôle (15 [13 à 20] minutes; n = 33; test de Mann­Whitney, P = 0,48). La durée médiane [PIQ] du bloc sensitif a été significativement plus courte dans le groupe expérimental (455 [398 à 490] minutes contre 610 [570 à 655] minutes dans le groupe contrôle; estimateur de la différence de Hodges­Lehmann, 165 minutes; intervalle de confiance [IC] à 95,08 % : 130 à 195; P < 0,001). De même, la durée médiane [PIQ] du bloc moteur a été significativement plus courte dans le groupe expérimental (470 [409 à 500] minutes contre 625 [578 à 665] minutes dans le groupe contrôle; estimateur de la différence de Hodges­Lehmann, 165 minutes; IC à 95,08 %, 130 à 195; P < 0,001). Il n'y a pas eu d'événement indésirable directement lié à la technique ou à l'injection de ropivacaïne dans l'un ou l'autre groupe. CONCLUSIONS: La ropivacaïne 0,375 % a été non inférieure à la ropivacaïne 0,5 % en ce qui concerne le taux de succès du BPB costo-claviculaire échoguidé. ENREGISTREMENT DE L'éTUDE: chictr.org.cn (ChiCTR20000306570); Enregistrée le 8 mars 2020.

Staggered-peak production is a mixed blessing in the control of particulate matter pollution.

Staggered-peak production (SP)-a measure to halt industrial production in the heating season-has been implemented in North China Plain to alleviate air pollution. We compared the variations of PM1 composition in Beijing during the SP period in the 2016 heating season (SPhs) with those in the normal production (NP) periods during the 2015 heating season (NPhs) and 2016 non-heating season (NPnhs) to investigate the effectiveness of SP. The PM1 mass concentration decreased from 70.0 ± 54.4 µg m-3 in NPhs to 53.0 ± 56.4 µg m-3 in SPhs, with prominent reductions in primary emissions. However, the fraction of nitrate during SPhs (20.2%) was roughly twice that during NPhs (12.7%) despite a large decrease of NOx, suggesting an efficient transformation of NOx to nitrate during the SP period. This is consistent with the increase of oxygenated organic aerosol (OOA), which almost doubled from NPhs (22.5%) to SPhs (43.0%) in the total organic aerosol (OA) fraction, highlighting efficient secondary formation during SP. The PM1 loading was similar between SPhs (53.0 ± 56.4 µg m-3) and NPnhs (50.7 ± 49.4 µg m-3), indicating a smaller difference in PM pollution between heating and non-heating seasons after the implementation of the SP measure. In addition, a machine learning technique was used to decouple the impact of meteorology on air pollutants. The deweathered results were comparable with the observed results, indicating that meteorological conditions did not have a large impact on the comparison results. Our study indicates that the SP policy is effective in reducing primary emissions but promotes the formation of secondary species.

Effect of Celastrol on LncRNAs and mRNAs Profiles of Cerebral Ischemia-Reperfusion Injury in Transient Middle Cerebral Artery Occlusion Mice Model.

Celastrol plays a significant role in cerebral ischemia-reperfusion injury. Although previous studies have confirmed that celastrol post-treatment has a protective effect on ischemic stroke, the therapeutic effect of celastrol on ischemic stroke and the underlying molecular mechanism remain unclear. In the present study, focal transient cerebral ischemia was induced by transient middle cerebral artery occlusion (tMCAO) in mice and celastrol was administered immediately after reperfusion. We performed lncRNA and mRNA analysis in the ischemic hemisphere of adult mice with celastrol post-treatment through RNA-Sequencing (RNA-Seq). A total of 50 differentially expressed lncRNAs (DE lncRNAs) and 696 differentially expressed mRNAs (DE mRNAs) were identified between the sham and tMCAO group, and a total of 544 DE lncRNAs and 324 DE mRNAs were identified between the tMCAO and tMCAO + celastrol group. Bioinformatic analysis was done on the identified deregulated genes through gene ontology (GO) analysis, KEGG pathway analysis and network analysis. Pathway analysis indicated that inflammation-related signaling pathways played vital roles in the treatment of ischemic stroke by celastrol. Four DE lncRNAs and 5 DE mRNAs were selected for further validation by qRT-PCR in brain tissue, primary neurons, primary astrocytes, and BV2 cells. The results of qRT-PCR suggested that most of selected differentially expressed genes showed the same fold change patterns as those in RNA-Seq results. Our study suggests celastrol treatment can effectively reduce cerebral ischemia-reperfusion injury. The bioinformatics analysis of lnRNAs and mRNAs profiles in the ischemic hemisphere of adult mice provides a new perspective in the neuroprotective effects of celastrol, particularly with regards to ischemic stroke.

European aerosol phenomenology - 8: Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets.

Organic aerosol (OA) is a key component of total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013-2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables quantification of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30-240 min) and long-term data coverage (9-36 months), providing essential information to improve/validate air quality, health impact, and climate models.

Chemical signature and fractionation of trace elements in fine particles from anthropogenic and natural sources.

The health effects of trace metal elements in atmospheric fine particulate matter (PM2.5) are widely recognized, however, the emission factor profiles and chemical fractionation of metal elements in different sources were poorly understand. In this study, sixteen metal elements, including Cd, Pb, V, Zn, Ba, Sb, As, Fe, Sr, Cr, Rb, Co, Mn, Cu, Ni and Sn from biomass burning, bituminite and anthracite combustion, as well as dust, were quantified. The results show different emission sources were associated with distinct emission profiles, holding important implications for source apportionment of ambient particulate metals. Specifically, Fe was the dominant metal species (28-1922 mg/kg) for all samples, and was followed by different metals for different samples. For dust, Mn (39.9 mg/kgdust) had the second-highest emission factor, while for biomass burning, it was Cr and Ba (7.5 and 7.4 mg/kgbiomass, respectively). For bituminous coal combustion, the emission factor of Zn and Ba was 6.2 and 6.0 mg/kgbituminous, respectively, while for anthracite combustion the corresponding emission factor was 5.6 and 4.3 mg/kganthracite, respectively. Moreover, chemical fractionation (i.e., the exchangeable, reducible fraction, oxidizable, and residual fraction) and the bioavailability index (BI) values of the metal elements from different sources were further investigated to reveal the link between different emission sources and the potential health risk. The findings from this study hold important implications for source apportionment and source-specific particulate metal-associated health effects.

Seasonality of Aerosol Sources Calls for Distinct Air Quality Mitigation Strategies.

An Aerosol Chemical Speciation Monitor (ACSM) was deployed to investigate the temporal variability of non-refractory particulate matter (NR-PM1) in the coastal city of Galway, Ireland, from February to July 2016. Source apportionment of the organic aerosol (OA) was performed using the newly developed rolling PMF strategy and was compared with the conventional seasonal PMF. Primary OA (POA) factors apportioned by rolling and seasonal PMF were similar. POA factors of hydrocarbon-like OA (HOA), peat, wood, and coal were associated with domestic heating, and with an increased contribution to the OA mass in winter. Even in summer, sporadic heating events occurred with similar diurnal patterns to that in winter. Two oxygenated OA (OOA) factors were resolved, including more-oxygenated OOA and less-oxygenated OOA (i.e., MO-OOA and LO-OOA, accordingly) which were found to be the dominant OA factors during summer. On average, MO-OOA accounted for 62% of OA and was associated with long-range transport in summer. In summer, compared to rolling PMF, the conventional seasonal PMF over-estimated LO-OOA by nearly 100% while it underestimated MO-OOA by 30%. The results from this study show residential heating and long-range transport alternately dominate the submicron aerosol concentrations in this coastal city, requiring different mitigation strategies in different seasons.

Large contribution from worship activities to the atmospheric soot particles in northwest China.

Worship activities like burning joss paper during the Chinese Hanyi festival is a common, traditional custom in northwest China. However, the pollutants of e.g., soot particles, released from joss paper burning and the corresponding impacts on urban air quality were poorly investigated, which can be a particular concern since these activities are conducted in an uncontrolled manner. In this study, a long time-of-flight (LToF) soot particle aerosol mass spectrometry (SP-AMS) was deployed to characterize the refractory black carbon (rBC) emitted from the joss paper burning, as well as crop residue, coal combustion, and traffic during the Hanyi Festival in mid-November 2020 in the northwestern city of Xi'an in China. Large difference (from <5% to >100%) in the fragmentation patterns (Cn+) for the measured rBC from different source emissions were found when compared to the reference Regal Black. Using the receptor model of positive matrix factorization (PMF) with the multilinear engine (ME-2) algorithm, the obtained rBC mass spectra were used as the anchoring profiles to evaluate the emission strengths of different source types to the atmospheric rBC. Our results show that the burning of joss paper accounted for up to 42% of the atmospheric rBC mass, higher than traffic (14-17%), crop residue (10-17%), coal (18-20%) during the Hanyi festival in northwest China. Moreover, we show that the overall air quality can be worsened due to the practice of uncontrolled burning of joss paper during the festival, which is not just confined to the people who do the burning. Although worship activities occur mainly during festival periods, the pollution events contributed by joss paper burning may pose an acute exposure risk for public health. This is particularly important since burning joss paper during worship activities is common in China and most Asian countries with similar traditions.

Polycyclic aromatic hydrocarbons from cooking emissions.

Air pollution studies have often overlooked the contribution from cooking to the particle-bound polycyclic aromatic hydrocarbons (PAHs) in the ambient environment, despite cooking emissions have been identified as an important source of organic aerosol in most urban areas, known as the cooking-like organic aerosol factor (i.e., COA). In this study, a Long-Time-of-Flight (LToF) soot particle aerosol mass spectrometer (SP-AMS) was deployed to evaluate the impact of cooking emissions on outdoor particle-bound PAHs levels during a summer campaign in 2019 in Xi'an China. Combined with the robust receptor model, cooking emission was found to be the major source of ambient PAHs, on average, accounting for 90% of PAHs, 9 times higher than traffic (10%). The ambient cooking PAH profile was well correlated (r2 of 0.87) with that for frying oil fume, suggesting cooking oil was the major source of PAHs instead of the food being cooked. We further evaluated the health risk associated with the cooking PAHs and estimated the cooking PAH levels in some of the major cities in the world where COA factor has been reported. The results show the particle-bound PAHs from cooking can be an important source of ambient PAHs in most Chinese cities. The findings from this study hold important implications for public health and are informing for policymakers.

Study of Emissions from Domestic Solid-Fuel Stove Combustion in Ireland.

Solid-fuel stoves are at the heart of many homes not only in developing nations, but also in developed regions where there is significant deployment of such heating appliances. They are often operated inefficiently and in association with high emission fuels like wood. This leads to disproportionate air pollution contributions. Despite the proliferation of these appliances, an understanding of particulate matter (PM) emissions from these sources remains relatively low. Emissions from five solid fuels are quantified using a "conventional" and an Ecodesign stove. PM measurements are obtained using both "hot filter" sampling of the raw flue gas, and sampling of cooled, diluted flue gas using an Aerosol Chemical Speciation Monitor and AE33 aethalometer. PM emissions factors (EF) derived from diluted flue gas incorporate light condensable organic compounds; hence they are generally higher than those obtained with "hot filter" sampling, which do not. Overall, the PM EFs ranged from 0.2 to 108.2 g GJ-1 for solid fuels. The PM EF determined for a solid fuel depends strongly on the measurement method employed and on user behavior, and less strongly on secondary air supply and stove type. Kerosene-based firelighters were found to make a disproportionately high contribution to PM emissions. Organic aerosol dominated PM composition for all fuels, constituting 50-65% of PM from bituminous and low-smoke ovoids, and 85-95% from torrefied olive stone (TOS) briquettes, sod peat, and wood logs. Torrefied biomass and low-smoke ovoids were found to yield the lowest PM emissions. Substituting these fuels for smoky coal, peat, and wood could reduce PM2.5 emissions by approximately 63%.

Measurement report of the change of PM2.5 composition during the COVID-19 lockdown in urban Xi'an: Enhanced secondary formation and oxidation.

Enhanced secondary aerosol formation was observed during the COVID-19 lockdown in Xi'an, especially for polluted episodes. More oxidized­oxygenated organic aerosol (MO-OOA) and sulfate showed the dominant enhancements, especially in large particle-mode. Meanwhile, relative humidity (RH) showed a positive promotion on the formation of sulfate and MO-OOA during the lockdown, but had no obvious correlation with less oxidized­oxygenated organic aerosol (LO-OOA) or nitrate. Organosulfurs (OS) displayed a higher contribution (~58%) than inorganic sulfate to total sulfate enhancement in the polluted episode during the lockdown. Although the total nitrate (TN) decreased during the lockdown ascribing to a larger reduction of inorganic nitrate, organic nitrate (ON) showed an obvious increase from pre-lockdown (0.5 ± 0.6 µg m-3 and 1 ± 2% of TN) to lockdown (5.3 ± 3.1 µg m-3 and 17 ± 9% of TN) in the polluted case (P < 0.05). In addition, RH also displayed a positive promotion on the formation of ON and OS, and the increases of both OS and ON were much efficient in the nighttime than in the daytime. These results suggest that higher RH and stagnant meteorology might facilitate the sulfate and MO-OOA enhancement, especially in the nighttime, which dominated the secondary aerosol enhancement in haze pollution during the lockdown.

Enhanced formation of secondary organic aerosol from photochemical oxidation during the COVID-19 lockdown in a background site in Northwest China.

The COVID-19 pandemic has drastically affected the economic and social activities, leading to large reductions in anthropogenic emissions on a global scale. Despite the reduction of primary emissions during the lockdown period, heavy haze pollution was observed unexpectedly in megacities in North and East China. In this study, we conducted online measurements of organic aerosol in a background site before and during the lockdown in Guanzhong basin, Northwest China. The oxygenated organic aerosol (OOA) increased from 24% of total OA (3.2 ± 1.6 µg m-3) before lockdown to 54% of total OA (4.5 ± 1.3 µg m-3) during lockdown, likely due to substantial decrease of NOx emissions during lockdown which resulted in large increase of O3 and thus atmospheric oxidizing capacity. OOA showed higher mass concentrations and fractional contributions during lockdown than before lockdown, and increased with the increase of Ox in both periods. In comparison, aqueous secondary organic aerosol (aqSOA) showed high mass concentrations and fractional contributions in both polluted periods before and during lockdown with the increase of aerosol liquid water content (ALWC). The increase of aqSOA under high ALWC conditions is very likely the reason of pollution events during lockdown. Combined with trajectory analysis, the absence of Guanzhong cluster in polluted period during lockdown may play a key role in the OA variations between two polluted periods. In addition, when comparing the clusters from the same transmission directions between before lockdown and during lockdown, the OA fractions showed similar variations during lockdown in all clusters, suggesting the OA variations are widespread in northwest China.

The formation and evolution of secondary organic aerosol during summer in Xi'an: Aqueous phase processing in fog-rain days.

Secondary organic aerosol (SOA) is an important contributor to organic aerosol (OA), however, the model simulations of SOA concentrations and oxidation states remain significant uncertainties because of inadequate cognition of its formation and aging chemistry. In this study, SOA formation and evolution processes during summer in Xi'an were investigated, based on high-resolution online measurements of non-refractory PM2.5 (NR-PM2.5) species and OA source apportionment using positive matrix factorization. The results showed that the total SOA, including less oxidized-oxygenated OA (LO-OOA), more oxidized-oxygenated OA (MO-OOA), and aqueous-phase-processed oxygenated OA (aq-OOA), on average constituted 69% of OA, and 43% of NR-PM2.5, suggesting the high atmospheric oxidation capacity and the dominance of SOA during summer in Xi'an. Photochemical oxidation processes dominated the summertime SOA formation both during non-fog-rain days and fog-rain days, which were responsible for the formation of both LO-OOA and MO-OOA. Consistently, LO-OOA and MO-OOA in total contributed 59% to OA during non-fog-rain days and 56% to OA during fog-rain days, respectively. On the contrary, aq-OOA was mainly observed during fog-rain days, which increased dramatically from 2% of OA during non-fog-rain days to 19% of OA during fog-rain days with the mass concentration increasing accordingly from 0.3 µg m-3 to 2.5 µg m-3. Episodic analyses further highlighted the persistently high RH period with high aerosol liquid water content (ALWC) was the driving factor of aq-OOA formation, and high Ox condition could further enhance its formation. Meanwhile, air masses from east and southeast were much favorable for the formation of long-time fog-rain days, which facilitated aq-OOA production during summer in Xi'an.

Seasonal variations in the sources of organic aerosol in Xi'an, Northwest China: The importance of biomass burning and secondary formation.

The Guanzhong basin is a part of the three top priority regions in China's blue sky action as of 2019. Understanding the chemical composition, sources, and atmospheric process of aerosol in this region is therefore imperative for improving air quality. In this study, we present, for the first time, the seasonal variations of organic aerosol (OA) in Xi'an, the largest city in the Guanzhong basin. Biomass burning OA (BBOA) and oxidized OA (OOA) contributed >50% of OA in both autumn and winter. The average concentrations of BBOA in autumn (14.8 ± 5.1 µg m-3) and winter (11.6 ± 6.8 µg m-3) were similar. The fractional contribution of BBOA to total OA, however, decreased from 31.9% in autumn to 15.3% in winter, because of enhanced contributions from other sources in winter. The OOA fraction in OA increased largely from 20.9% in autumn to 34.9% in winter, likely due to enhanced emissions of precursors and stagnant meteorological conditions which facilitate the accumulation and secondary formation. A large increase in OOA concentration was observed during polluted days, by a factor of ~4 in autumn and ~6 in winter compared to clean days. In both seasons, OOA formation was most likely dominated by photochemical oxidation when aerosol liquid water content was <30 µg m-3 or by aqueous-phase processes when Ox was <35 ppb. A higher concentration of BBOA was observed for air masses circulated within the Guanzhong basin (16.5-18.1 µg m-3), compared to air masses from Northwest and West (10.9-14.5 µg m-3). Furthermore, compared with OA fraction in non-refractory PM1 in other regions of China, BBOA (17-19%) and coal combustion OA (10-20%) were major emission sources in the Guanzhong Basin and the BTH region, respectively, whereas OOA (10-34%) was an important source in all studied regions.

Chemical nature and sources of fine particles in urban Beijing: Seasonality and formation mechanisms.

To mitigate air pollution in China, a legislative 'Air Pollution Prevention and Control Action Plan' has been implemented by the Chinese government since 2013. There is, however, a lack of investigations for long-term trends in the composition, sources and evolution processes of PM1 (particulate matter with diameter less than 1 µm) after the implementation. To evaluate the effectiveness of these control measures, we present a year-long real-time measurement of the chemical composition of PM1 at an urban site in Beijing from November 2014 to November 2015, and the results are compared with previous studies from 2008 to 2013 to gain insights into the variations of the chemical composition and sources of PM1 in Beijing. Large seasonal differences were observed in the mass concentrations of PM1 species and general declining trend was observed in the last seven years. Specifically, the annual averages of mass concentrations in 2014-2015 decrease by 16-43% (PM1), 23-43% (organic aerosol, OA), 38-68% (sulfate), 26-51% (nitrate), 18-33% (ammonium) and 27-38% (chloride) compared to those from 2008 to 2013. During winter and summer, the seasonal mass concentrations of sulfate and nitrate show more significant declines especially in summer 2008 (79% and 81%) and summer 2011 (76% and 77%). The nitrate-to-sulfate ratio is higher in 2014-2015 (1.5 ± 0.6) than that in 2013 (1.0 ± 0.3), largely due to significant reduction in SO2 emissions, suggesting that nitrate is becoming more important than sulfate in particulate pollution in Beijing. OA is the dominant PM1 fraction (>45%) in all seasons and the mass concentrations/contributions of both primary and secondary OA show different seasonality. As for the more oxidized oxygenated OA (MO-OOA) and less oxidized oxygenated OA (LO-OOA), the contributions of MO-OOA are much higher than those of LO-OOA (27-62% vs. 6-26%) in both high-pollution and low-pollution days. Aqueous-phase processes are found to facilitate the formation of MO-OOA while photochemical oxidation formation is a major contributor of LO-OOA in winter, and photochemical oxidation plays a major role in the formation of MO-OOA in summer and fall. The current study provides a comprehensive seasonal comparison of chemical composition and formation of PM1 in Beijing and a pacesetter in tackling PM pollution for other equally polluted megacities, after implementation of more stringent control measures after 2013.

Effects of NH3 and alkaline metals on the formation of particulate sulfate and nitrate in wintertime Beijing.

Sulfate and nitrate from secondary reactions remain as the most abundant inorganic species in atmospheric particle matter (PM). Their formation is initiated by oxidation (either in gas phase or particle phase), followed by neutralization reaction primarily by NH3, or by other alkaline species such as alkaline metal ions if available. The different roles of NH3 and metal ions in neutralizing H2SO4 or HNO3, however, are seldom investigated. Here we conducted semi-continuous measurements of SO42-, NO3-, NH4+, and their gaseous precursors, as well as alkaline metal ions (Na+, K+, Ca2+, and Mg2+) in wintertime Beijing. Analysis of aerosol acidity (estimated from a thermodynamic model) indicated that preferable sulfate formation was related to low pH conditions, while high pH conditions promote nitrate formation. Data in different mass fraction ranges of alkaline metal ions showed that in some ranges the role of NH3 was replaced by alkaline metal ions in the neutralization reaction of H2SO4 and HNO3 to form particulate SO42- and NO3-. The relationships between mass fractions of SO42- and NO3- in those ranges of different alkaline metal ion content also suggested that alkaline metal ions participate in the competing neutralization reaction of sulfate and nitrate. The implication of the current study is that in some regions the chemistry to incorporate sulfur and nitrogen into particle phase might be largely affected by desert/fugitive dust and sea salt, besides NH3. This implication is particularly relevant in coastal China and those areas with strong influence of dust storm in the North China Plain (NCP), both of which host a number of megacities with deteriorating air quality.

[Effect of propofol on myelin basic protein expression and myelination of oligodendrocytes in neonatal SD rats].

OBJECTIVE: To investigate the effects of different doses of propofol on myelin basic protein (MBP) synthesis and myelination of oligodendrocytes in neonatal SD rats. METHODS: A total of 57 neonatal SD rats (7 days old) were randomly divided into control group (n=13), vehicle (fat emulsion) group (n=5), and 25, 50 and 100 mg/kg propofol groups (n=13 in each group). Eight hours after a single intraperitoneal injection of propofol or the vehicle, the rats were examined for expressions of mbp mRNA, caspase-3 mRNA, cleaved caspase-3 and MBP in the brain tissues using qPCR and Western blotting. Immunofluorescence assay was used to detect the apoptosis of the oligodendrocytes at 8 h after the injection and the myelination of the corpus callosum and internal capsule at 24 h. RESULTS: Compared with the control group, the neonatal rats with propofol injections showed significantly down-regulated expressions of mbp mRNA and MBP protein in the brain tissue (P < 0.05). Propofol dose-dependently increased the transcription level of caspase-3 and the protein levels of cleaved caspase-3 at 8 h after the injection (P < 0.05). Propofol injection significantly increased the apoptosis of the oligodendrocytes, and the effect was significantly stronger in 50 and 100 mg/kg groups than in 25 mg/kg group (P < 0.05). At 24 h after propofol injection, myelin formation was significantly decreased in the corpus callosum of the neonatal rats in 100 mg/kg propofol group and in the internal capsule in 50 and 100 mg/kg groups (P < 0.05). CONCLUSIONS: In neonatal SD rats, propofol can dose-dependently promote oligodendrocyte apoptosis, decrease MBP expressions in the brain, and suppress myelin formation in the corpus callosum and the internal capsule.

Preactivation of Notch1 in remote ischemic preconditioning reduces cerebral ischemia-reperfusion injury through crosstalk with the NF-κB pathway.

BACKGROUND: Remote ischemic preconditioning (RIPC) initiates endogenous protective pathways in the brain from a distance and represents a new, promising paradigm in neuroprotection against cerebral ischemia-reperfusion (I/R) injury. However, the underlying mechanism of RIPC-mediated cerebral ischemia tolerance is complicated and not well understood. We reported previously that preactivation of Notch1 mediated the neuroprotective effects of cerebral ischemic preconditioning in rats subjected to cerebral I/R injury. The present study seeks to further explore the role of crosstalk between the Notch1 and NF-κB signaling pathways in the process of RIPC-induced neuroprotection. METHODS: Middle cerebral artery occlusion and reperfusion (MCAO/R) in adult male rats and oxygen-glucose deprivation and reoxygenation (OGD/R) in primary hippocampal neurons were used as models of I/R injury in vivo and in vitro, respectively. RIPC was induced by a 3-day procedure with 4 cycles of 5 min of left hind limb ischemia followed by 5 min of reperfusion each day before MCAO/R. Intracerebroventricular DAPT injection and sh-Notch1 lentivirus interference were used to inhibit the Notch1 signaling pathway in vivo and in vitro, respectively. After 24 h of reperfusion, neurological deficit scores, infarct volume, neuronal apoptosis, and cell viability were assessed. The protein expression levels of NICD, Hes1, Phospho-IKKα/ß (p-IKK α/ß), Phospho-NF-κB p65 (p-NF-κB p65), Bcl-2, and Bax were assessed by Western blotting. RESULTS: RIPC significantly improved neurological scores and reduced infarct volume and neuronal apoptosis in rats subjected to I/R injury. OGD preconditioning significantly reduced neuronal apoptosis and improved cell viability after I/R injury on days 3 and 7 after OGD/R. However, the neuroprotective effect was reversed by DAPT in vivo and attenuated by Notch1-RNAi in vitro. RIPC significantly upregulated the expression of proteins related to the Notch1 and NF-κB pathways. NF-κB signaling pathway activity was suppressed by a Notch1 signaling pathway inhibitor and Notch1-RNAi. CONCLUSIONS: The neuroprotective effect of RIPC against cerebral I/R injury was associated with preactivation of the Notch1 and NF-κB pathways in neurons. The NF-κB pathway is a downstream target of the Notch1 pathway in RIPC and helps protect focal cerebral I/R injury.