Aqueous production of secondary organic aerosol from fossil-fuel emissions in winter Beijing haze.

Secondary organic aerosol (SOA) produced by atmospheric oxidation of primary emitted precursors is a major contributor to fine particulate matter (PM2.5) air pollution worldwide. Observations during winter haze pollution episodes in urban China show that most of this SOA originates from fossil-fuel combustion but the chemical mechanisms involved are unclear. Here we report field observations in a Beijing winter haze event that reveal fast aqueous-phase conversion of fossil-fuel primary organic aerosol (POA) to SOA at high relative humidity. Analyses of aerosol mass spectra and elemental ratios indicate that ring-breaking oxidation of POA aromatic species, leading to functionalization as carbonyls and carboxylic acids, may serve as the dominant mechanism for this SOA formation. A POA origin for SOA could explain why SOA has been decreasing over the 2013-2018 period in response to POA emission controls even as emissions of volatile organic compounds (VOCs) have remained flat.

Puzzling Haze Events in China During the Coronavirus (COVID-19) Shutdown.

It is a puzzle as to why more severe haze formed during the New Year Holiday in 2020 (NYH-20), when China was in an unprecedented state of shutdown to contain the coronavirus (COVID-19) outbreak, than in 2019 (NYH-19). We performed a comprehensive measurement and modeling analysis of the aerosol chemistry and physics at multiple sites in China (mainly in Shanghai) before, during, and after NYH-19 and NYH-20. Much higher secondary aerosol fraction in PM2.5 were observed during NYH-20 (73%) than during NYH-19 (59%). During NYH-20, PM2.5 levels correlated significantly with the oxidation ratio of nitrogen (r 2 = 0.77, p < 0.01), and aged particles from northern China were found to impede atmospheric new particle formation and growth in Shanghai. A markedly enhanced efficiency of nitrate aerosol formation was observed along the transport pathways during NYH-20, despite the overall low atmospheric NO2 levels.

USP3 stabilizes p53 protein through its deubiquitinase activity.

p53 is the guardian of the genome integrity and the degradation of p53 protein is mediated by MDM2. Here we report that USP3 interacts with p53 and regulates p53 stability. Depletion of USP3 lead to accelerated degradation of p53 in normal cells thereby enhanced cell proliferation and transformation. Reconstitution of wildtype USP3, but not the USP3 C168S mutant, restored the stability of p53 protein and inhibited cell proliferation and transformation. These findings suggest that USP3 is an important regulator of p53 and regulates normal cell transformation.

Significance of Volatile Organic Compounds to Secondary Pollution Formation and Health Risks Observed during a Summer Campaign in an Industrial Urban Area.

The chemical complexity and toxicity of volatile organic compounds (VOCs) are primarily encountered through intensive anthropogenic emissions in suburban areas. Here, pollution characteristics, impacts on secondary pollution formation, and health risks were investigated through continuous in-field measurements from 1-30 June 2020 in suburban Nanjing, adjacent to national petrochemical industrial parks in China. On average, the total VOCs concentration was 34.47 ± 16.08 ppb, which was comprised mostly by alkanes (41.8%) and halogenated hydrocarbons (29.4%). In contrast, aromatics (17.4%) dominated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) with 59.6% and 58.3%, respectively. Approximately 63.5% of VOCs were emitted from the petrochemical industry and from solvent usage based on source apportionment results, followed by biogenic emissions of 22.3% and vehicle emissions of 14.2%. Of the observed 46 VOC species, hexachlorobutadiene, dibromoethane, butadiene, tetrachloroethane, and vinyl chloride contributed as high as 98.8% of total carcinogenic risk, a large fraction of which was ascribed to the high-level emissions during ozone pollution episodes and nighttime. Therefore, the mitigation of VOC emissions from petrochemical industries would be an effective way to reduce secondary pollution and potential health risks in conurbation areas.

Real-time non-refractory PM1 chemical composition, size distribution and source apportionment at a coastal industrial park in the Yangtze River Delta region, China.

This study present real-time measurements of the chemical composition and particle number size distributions (PNSD) of submicron particulate matter (PM1) in winter at a coastal industrial park in the Yangtze River Delta region of China. Positive matrix factorization (PMF) analysis identified three PNSD factors and three organic aerosol (OA) factors. Contributions and potential source regions of these factors were investigated for four typical periods during the PM1 formation and dissipation process. Results show that the relative contributions from aged 250 nm- factor, fresh 35 nm- and 80 nm- factors were strongly affected by local fresh emissions and regional new particle formation. The non-refractory PM1 measured by Aerodyne aerosol chemical speciation monitor is indicative of the chemical composition of aged 250 nm-factor, but not fresh 35 nm- and 80 nm-factors. The contributions of NO3- and SO42- to NR-PM1 were largely dictated by whether the air mass trajectory went over the sea or the continent. NO3- was abundant (up to 44% of NR-PM1) in cold and dry continental air masses, while SO42- formation (up to 39% of NR-PM1) was preferred in humid and warm marine air masses. Among the three OA source factors, more-oxidized oxygenated OA (MO-OOA) was the most abundant OA factor (44-66% of total OA) throughout the entire field campaign, while an enhanced contribution of 39% from hydrocarbon-like OA (HOA) was observed prior to heavy pollution period. On average, secondary components SO42-, NO3-, NH4+, MO-OOA and less-oxidized oxygenated OA (LO-OOA) contributed 90 ± 7% of NR-PM1, while primary components HOA and Cl- accounted for the remaining 10 ± 7%.

Chemical characteristics, sources and evolution processes of fine particles in Lin'an, Yangtze River Delta, China.

In this study, daily PM2.5 mass and chemical composition were measure in Lin'an Reginal Background Station, Yangzte River Delta, from March 1, 2018, to February 28, 2019. Organic matter (OM) was found to be the most dominant component in four seasons. The proportions of nitrate in PM2.5 presented dramatically lowest in warm seasons but highest in winter, indicating that NO3- was maily driven by thermodynamics. Regional transportation in winter plays a strong impact on PM2.5 concentration, which showed the highest average mass of 60.1 µg m-3. Sulfate occupied a significant portion of PM2.5 in summer (19%), followed by spring (17%), fall (15%), and winter (12%), respectively, suggesting photochemical processes may play a dominant role in the sulfate formation. Secondary inorganic aerosol (SIA) was the dominant component (70%) in the highest polluted periods (PM2.5 > 75 µg m-3), whereas OM decreased into the lowest fraction (22%) of PM2.5. Nitrate was the most important component in SIA in the highest polluted periods with regarding winter. Source apportionment results shown that winter haze was likely strongly dominated by SIA, which was mainly affected by air masses from the North China Plain and Shang-Hangzhou direction. PM2.5 is known to play an important role in sunlight absorption and reversing to human health, continuous observation on PM2.5 species in a background site can help us to evaluate the control policy, and promote our insights to lifetime, formation pathways, health effects of PM2.5.

Fast sulfate formation from oxidation of SO2 by NO2 and HONO observed in Beijing haze.

Severe events of wintertime particulate air pollution in Beijing (winter haze) are associated with high relative humidity (RH) and fast production of particulate sulfate from the oxidation of sulfur dioxide (SO2) emitted by coal combustion. There has been considerable debate regarding the mechanism for SO2 oxidation. Here we show evidence from field observations of a haze event that rapid oxidation of SO2 by nitrogen dioxide (NO2) and nitrous acid (HONO) takes place, the latter producing nitrous oxide (N2O). Sulfate shifts to larger particle sizes during the event, indicative of fog/cloud processing. Fog and cloud readily form under winter haze conditions, leading to high liquid water contents with high pH (>5.5) from elevated ammonia. Such conditions enable fast aqueous-phase oxidation of SO2 by NO2, producing HONO which can in turn oxidize SO2 to yield N2O.This mechanism could provide an explanation for sulfate formation under some winter haze conditions.

High calcium diet alleviates 5/6 nephrectomy-induced bone deteriorations of lumbar vertebrae in mice.

Dietary calcium (Ca) supplementation has beneficial effects on bone health. However, it is not clear whether a high calcium diet (HCD) following 5/6 nephrectomy (5/6 Nx) is beneficial to bone health. The aim of the present study was to examine the effects of an HCD on bone metabolism using a chronic kidney disease (CKD) mouse model. Male C57BL/6J mice were divided into three groups: Sham group, 5/6 Nx group and 5/6 Nx + HCD group. Mice were sacrificed 12 weeks post-surgery. Calcium (Ca) and creatinine (Cr) were measured using standard colorimetric methods and picric acid methods, respectively. Bone metabolism-associated markers, FGF-23, PTH, ALP-b and TRAP-5b were measured using ELISA kits. Lumbar vertebrae histomorphological analysis was performed using hematoxylin and eosin staining. The expression of osteoprotegerin (OPG) and receptor activator of nuclear factor κB ligand (RANKL) mRNA was detected using reverse transcription-quantitative polymerase chain reaction. Impaired renal function and histopathological damage was indicated in 5/6 Nx mice. However, HCD had no significant effects on these changes in 5/6 Nx mice. Notably, mineral metabolism disorder and histopathological damage to lumbar vertebrae were markedly improved in HCD-treated 5/6 Nx mice. Compared with 5/6 Nx mice, HCD supplementation significantly elevated the ratio of OPG/RANKL and inhibited RANKL mRNA expression in lumbar vertebrae. To conclude, the present findings indicated that increased Ca intake is effective in increasing bone mineral content of the lumbar vertebrae in 5/6 Nx mice. These results may provide a basis for the clinical use of dietary Ca supplementation as a therapeutic approach to treat CKD-induced disturbance of mineral metabolism and bone loss.

[A comparative study of outcome between single cage and double cages interbody fusion combined with pedicle screw fixation in treatment of isthmic spondylolisthesis].

OBJECTIVE: To compare the clinical effects of isthmic spondylolisthesis by a single cage or double cages interbody fusion combined with pedicle screw fixation. METHODS: The clinical data of 172 patients with isthmic spondylolisthesis underwent surgery from March 2000 to August 2008 were retrospectively analyzed. All cases underwent posterior pedicle screw fixation and interbody fusion, 89 cases with single cage fusion and 83 cases with double cages fusion. In single cage group, there were 56 males and 33 females, aged from 18 to 63 years old with an average of(41.60±8.20) years;25 cases were in L4 segment and 64 cases were in L5;according to the Meyerding standard, 32 cases were I degree, 46 cases were II degree and 11 cases were III degree. In double cage group, there were 49 males and 34 females, aged from 20 to 65 years old with an average of(43.30±6.39) years;21 cases were in L4 and 62 cases were in L5;according to the Meyerding standard, 25 cases were I degrees, 45 cases were II degree, and 13 cases were III degree. The operative time, intraoperative blood loss, postoperative drainage volum, bone fusion rate, intervertebral space height and the improvement of clinical symptoms were compared between two groups. RESULTS: All the operations were successful and all patients were followed up for 18 to 83 months with an average of 4 years and 3 months. The operative time, intraoperative blood loss, postoperative drainage volume in single cage group were less than of double cage group(P<0.05). Two weeks after operation, the intervertebral space height was significantly increased in two groups(P<0.05), and there was no significant difference at the last follow-up between two groups. At 16 months after operation, all bone grafts of patients got bony fusion by X-rays. At the last follow-up, there were no statistically significant difference in JOA, ODI and VAS score between two groups, no pedicle screw loosening and breaking were found. CONCLUSIONS: Single cage interbody fusion combined with pedicle screw fixation is as effective as with double cages interbody fusion in treatment of isthmic spondylolisthesis, it has the advantages of short operative time and less blood loss.

[Treatment of thoracolumbar kyphosis caused by old fracture using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach].

OBJECTIVE: To evaluate the effectiveness of using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach to treat thoracolumbar kyphosis caused by old fracture. METHODS: Between June 2008 and June 2010, 15 cases of thoracolumbar kyphosis caused by old fracture were treated with pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach. There were 9 males and 6 females with a mean age of 54.6 years (range, 39-65 years). The disease duration was 5 months to 3 years with an average of 1.5 years. Fractured segments included T11 in 1 case, T12 in 4 cases, L1 in 5 cases, and L2 in 5 cases. Ten patients had nerve symptom, according to American Spinal Injury Association (ASIA) grading, 3 cases were classified as grade B, 4 cases as grade C, and 3 cases as grade D, of which 3 cases had sexual and sphincter dysfunction. At preoperation, the Cobb angle was (47.4 +/- 10.2) degrees; the Oswestry disability index (ODI) score was 67.9% +/- 6.9%; and the visual analogue scale (VSA) was 8.6 +/- 1.4. RESULTS: The wounds obtained primary healing. The mean follow-up time was 28 months (range, 13-60 months). X-ray films showed intervertebral bone fusion was obtained within 6-11 months (mean, 10.2 months). No fixation loosening or breaking occurred during follow-up. Kyphosis was corrected, and lumbar back pain was relieved. At 1 year after operation, Cobb angle was significantly corrected to (13.3 +/- 7.7) degrees (t = 72.80, P = 0.00); ODI score was significantly improved to 25.2% +/- 4.6% (t = 48.04, P = 0.00); VAS score was significantly decreased to 2.3 +/- 0.6 (t = 26.52, P = 0.00). According to ASIA grading in 10 patients with spinal cord injury, the spinal cord function was improved by 1 grade in 8 cases (3 cases from grade B to C, 3 cases from grade C to D, and 2 cases from grade D to E); 3 patients with sexual and sphincter dysfunction recovered in different degrees. CONCLUSION: Using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach is an effective method to treat thoracolumbar kyphosis caused by old fracture.