The megacity of Beijing has experienced frequent severe fine particle pollution during the last decade. Although the sources and formation mechanisms of aerosol particles have been extensively ...investigated on the basis of ground measurements, real-time characterization of aerosol particle composition and sources above the urban canopy in Beijing is rare. In this study, we conducted real-time measurements of non-refractory submicron aerosol (NR-PM1) composition at 260 m at the Beijing 325 m meteorological tower (BMT) from 10 October to 12 November 2014, by using an aerosol chemical speciation monitor (ACSM) along with synchronous measurements of size-resolved NR-PM1 composition near ground level using a high-resolution time-of-flight aerosol mass spectrometer (HR–ToF–AMS). The NR-PM1 composition above the urban canopy was dominated by organics (46 %), followed by nitrate (27 %) and sulfate (13 %). The high contribution of nitrate and high NO3− / SO42− mass ratios illustrates an important role of nitrate in particulate matter (PM) pollution during the study period. The organic aerosol (OA) was mainly composed of secondary OA (SOA), accounting for 61 % on an average. Different from that measured at the ground site, primary OA (POA) correlated moderately with SOA, likely suggesting a high contribution from regional transport above the urban canopy. The Asia–Pacific Economic Cooperation (APEC) summit with strict emission controls provides a unique opportunity to study the impacts of emission controls on aerosol chemistry. All aerosol species were shown to have significant decreases of 40–80 % during APEC from those measured before APEC, suggesting that emission controls over regional scales substantially reduced PM levels. However, the bulk aerosol composition was relatively similar before and during APEC as a result of synergetic controls of aerosol precursors. In addition to emission controls, the routine circulations of mountain–valley breezes were also found to play an important role in alleviating PM levels and achieving the "APEC blue" effect. The evolution of vertical differences between 260 m and the ground level was also investigated. Our results show complex vertical differences during the formation and evolution of severe haze episodes that are closely related to aerosol sources and boundary-layer dynamics.
The mitigation of air pollution in megacities remains a great challenge because of the complex sources and formation mechanisms of aerosol particles. The 2014 Asia-Pacific Economic Cooperation (APEC) ...summit in Beijing serves as a unique experiment to study the impacts of emission controls on aerosol composition, size distributions, and oxidation properties. Herein, a high-resolution time-of-flight aerosol mass spectrometer was deployed in urban Beijing for real-time measurements of size-resolved non-refractory submicron aerosol (NR-PM1) species from 14 October to 12 November 2014, along with a range of collocated measurements. The average (±σ) PM1 was 41.6 (±38.9) μg m−3 during APEC, which was decreased by 53 % compared with that before APEC. The aerosol composition showed substantial changes owing to emission controls during APEC. Secondary inorganic aerosol (SIA: sulfate + nitrate + ammonium) showed significant reductions of 62–69 %, whereas organics presented much smaller decreases (35 %). The results from the positive matrix factorization of organic aerosol (OA) indicated that highly oxidized secondary organic aerosol (SOA) showed decreases similar to those of SIA during APEC. However, primary organic aerosol (POA) from cooking, traffic, and biomass-burning sources were comparable to those before APEC, indicating the presence of strong local source emissions. The oxidation properties showed corresponding changes in response to OA composition. The average oxygen-to-carbon level during APEC was 0.36 (±0.10), which is lower than the 0.43 (±0.13) measured before APEC, demonstrating a decrease in the OA oxidation degree. The changes in size distributions of primary and secondary species varied during APEC. SIA and SOA showed significant reductions in large accumulation modes with peak diameters shifting from ~ 650 to 400 nm during APEC, whereas those of POA remained relatively unchanged. The changes in aerosol composition, size distributions, and oxidation degrees during the aging processes were further illustrated in a case study of a severe haze episode. Our results elucidated a complex response of aerosol chemistry to emission controls, which has significant implications that emission controls over regional scales can substantially reduce secondary particulates. However, stricter emission controls for local source emissions are needed for further mitigating air pollution in the megacity of Beijing.
Targeting the ubiquitin-proteasome pathway has emerged as a rational approach in the treatment of human cancer. Based on positive preclinical and clinical studies, bortezomib was subsequently ...approved for the clinical use as a front-line treatment for newly diagnosed multiple myeloma patients and for the treatment of relapsed/refractory multiple myeloma and mantle cell lymphoma, for which this drug has become the staple of treatment. The approval of bortezomib by the US Food and Drug Administration (FDA) represented a significant milestone as the first proteasome inhibitor to be implemented in the treatment of malignant disease. Bortezomib has shown a positive clinical benefit either alone or as a part of combination therapy to induce chemo-/radio-sensitization or overcome drug resistance. One of the major mechanisms of bortezomib associated with its anticancer activity is through upregulation of NOXA, which is a proapoptotic protein, and NOXA may interact with the anti-apoptotic proteins of Bcl-2 subfamily Bcl-X(L) and Bcl-2, and result in apoptotic cell death in malignant cells. Another important mechanism of bortezomib is through suppression of the NF-κB signaling pathway resulting in the down-regulation of its anti-apoptotic target genes. Although the majority of success achieved with bortezomib has been in hematological malignancies, its effect toward solid tumors has been less than encouraging. Additionally, the widespread clinical use of bortezomib continues to be hampered by the appearance of dose-limiting toxicities, drug-resistance and interference by some natural compounds. These findings could help guide physicians in refining the clinical use of bortezomib, and encourage basic scientists to generate next generation proteasome inhibitors that broaden the spectrum of efficacy and produce a more durable clinical response in cancer patients. Other desirable applications for the use of proteasome inhibitors include the development of inhibitors against specific E3 ligases, which act at an early step in the ubiquitin-proteasome pathway, and the discovery of less toxic and novel proteasome inhibitors from natural products and traditional medicines, which may provide more viable drug candidates for cancer chemoprevention and the treatment of cancer patients in the future.
Essentials
Perioperative blood loss and inflammatory response can significantly affect recovery after surgery.
We studied the effects of multiple‐dose oral tranexamic acid on blood loss and ...inflammatory response.
A postoperative four‐dose regimen brought about maximum reduction in postoperative blood loss.
A postoperative four‐dose regimen reduced inflammatory response and promoted early rehabilitation.
Summary
Background
Tranexamic acid (TXA) can reduce blood loss and the inflammatory response at multiple doses in total knee arthroplasty patients. However, the optimal regimen has not been determined.
Objectives
To identify the most effective regimen for achieving maximum reductions in blood loss and the inflammatory response.
Patients/Methods
Two hundred and seventy‐five patients were randomized to receive a placebo (group A), a single 2‐g oral dose of TXA 2 h preoperatively followed by 1 g of oral TXA 3 h postoperatively (group B), a single dose followed by 1 g of oral TXA 3 h and 7 h postoperatively (group C), a single dose followed by 1 g of oral TXA 3 h, 7 h and 11 h postoperatively (group D), or a single dose followed by 1 g of oral TXA 3 h, 7 h, 11 h and 15 h postoperatively (group E). The primary outcome was total blood loss on postoperative day (POD) 3. Secondary outcomes included a decrease in the hemoglobin level, coagulation parameters, inflammatory marker levels, and thromboembolic complications.
Results
Groups D and E had significantly lower blood loss and smaller decreases in hemoglobin level than groups A, B, and C, with no significant difference on POD 3 between groups D and E. Significantly enhanced coagulation was identified for the four multiple‐dose regimens; however, all thromboelastographic parameters remained within normal ranges. Group E had the lowest inflammatory marker levels and pain, and the greatest range of motion. No thromboembolic complications were identified.
Conclusion
The four‐dose regimen yielded the maximum reductions in blood loss and inflammatory response, improved analgesia, and promoted early rehabilitation. Further studies are required to ensure that these findings are reproducible.
Organic molecular composition of marine aerosol samples collected during the MALINA cruise in the Arctic Ocean was investigated by gas chromatography/mass spectrometry. More than 110 individual ...organic compounds were determined in the samples and were grouped into different compound classes based on the functionality and sources. The concentrations of total quantified organics ranged from 7.3 to 185 ng m−3 (mean 47.6 ng m−3), accounting for 1.8–11.0% (4.8%) of organic carbon in the marine aerosols. Primary saccharides were found to be dominant organic compound class, followed by secondary organic aerosol (SOA) tracers formed from the oxidation of biogenic volatile organic compounds (VOCs) such as isoprene, α-pinene and β-caryophyllene. Mannitol, the specific tracer for airborne fungal spores, was detected as the most abundant organic species in the samples with a concentration range of 0.052–53.3 ng m−3 (9.2 ng m−3), followed by glucose, arabitol, and the isoprene oxidation products of 2-methyltetrols. Biomass burning tracers such as levoglucosan are evident in all samples with trace levels. On the basis of the tracer-based method for the estimation of fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 10.7% (up to 26.2%) of the OC in the marine aerosols was due to the contribution of fungal spores, followed by the contribution of isoprene SOC (mean 3.8%) and α-pinene SOC (2.9%). In contrast, only 0.19% of the OC was due to the photooxidation of β-caryophyllene. This study indicates that primary organic aerosols from biogenic emissions, both from long-range transport of mid-latitude aerosols and from sea-to-air emission of marine organics, as well as secondary organic aerosols formed from the photooxidation of biogenic VOCs are important factors controlling the organic chemical composition of marine aerosols in the Arctic Ocean.
The Tibetan Plateau is the highest and one of the most demanding environments ever inhabited by humans. We investigated the timing and mechanisms of its initial colonization at the Nwya Devu site, ...located nearly 4600 meters above sea level. This site, dating from 40,000 to 30,000 years ago, is the highest Paleolithic archaeological site yet identified globally. Nwya Devu has yielded an abundant blade tool assemblage, indicating hitherto-unknown capacities for the survival of modern humans who camped in this environment. This site deepens the history of the peopling of the "roof of the world" and the antiquity of human high-altitude occupations more generally.
Previously treated TB patients still pose a serious threat to global control of TB, yet new re-treatment therapies were little studied. This study aimed to examine the therapeutic effects of new ...re-treatment regimens, and explore risk factors associated with recurrence after successful treatment. We conducted a cohort study in nine regions of China and enrolled previously treated TB patients from October, 2008 to December, 2010. Patients were randomly divided into four treatment regimen groups including standard, high-dose, long-course, and individualized treatment. After treatment, those with successful treatment outcomes were followed up to 7 years. The effects of different regimens and the information of recurrence were recorded. Risk factors to poor treatment outcomes were calculated using logistic regression model, while risk factors to recurrence or death were calculated using Cox model. Four hundred ninety-two participants were enrolled during the study time and 419 patients were included in our analysis of treatment effects. Overall, the treatment success rate is 75.9%, and the recurrence and death rate is 6.9% and 3.8%, respectively. Reduced risks of poor outcomes were observed in patients who were treated with high-dose and individualized regimen compared with standard regimen, and the adjusted ORs were 0.3 (0.1–0.6), 0.2 (0.1–0.5), respectively. In our analysis of factors associated with recurrence, all documented variables were not significant. Revised re-treatment regimen has better therapeutic effects compared to standard regimen, but it was not associated with lower risk of TB recurrence. Further studies are warranted to evaluate the role of other revised re-treatment regimens in recurrence risk. Trial registration:
chictr.org
Identifier: ChiCTR1800017441.
The aim of this study was to characterize detailed interfacial microstructures and evaluate tensile properties of Al6061-to-Cu dissimilar welded joints via electromagnetic pulse welding (EMPW) at ...different discharge voltages. The EMPWed joints consisted of annular weld zone and central non-weld zone. The outer and inner regions of annular weld zone exhibited mainly diffusion bonding and mechanical interlocking, respectively, representing a well-bonded interface. Distinctive discontinuous “droplet-like” pseudo-eutectic (α-Al + Al2Cu) particles or patches were observed to eject in the adjacent transition region in the non-weld zone. The highly non-equilibrium eutectic-like liquid or slurry at the Al/Cu interface was formed due to the ultra-high strain rate experienced by the interface and the ensuing instant temperature rise beyond the eutectic temperature of Al–Cu system, when the high-velocity flyer Al sheet crashed into the fixed Cu sheet driven by the Lorentz force during EMPW. The interfacial diffusion layer was thin in the order of 1–2 μm. The higher the discharge voltage was, the more obvious the interfacial diffusion layer and mechanical interlocking were, with “wave-like” and “inverted hook-like” interfacial characteristics observed. While interfacial failure occurred during the tensile lap shear tests for the joints made at a discharge voltage of 12 kV, the failure loads were still significantly higher than those specified in the AWS D17.2 standard. The EMPWed joints made at 14 kV and 16 kV remained intact and only base metal failure occurred, with the tensile lap shear failure loads reaching over twice those specified in the AWS D17.2 standard. Thus the well-bonded robust Al/Cu dissimilar welds were successfully achieved via EMPW.
Due to that the high charge density and small radius render In3+ cation a stronger Lewis acidity, multifunctional nanoporous In-MOFs have become one of the most promising catalysts for their high ...activity. Herein, the solvothermal self-assembly by employing 2,4,6-tri (2,4-dicarboxyphenyl)pyridine (H6TDP) as organic linker leads to a robust honeycomb skeleton of {(CH3)2NH2InIIIPbII(TDP) (H2O)⋅3DMF⋅3H2O}n (NUC-52) with the merits of nanoscopic channels, high porosity (61.3%), large specific surface area, and thermal stability. To the best of our knowledge, this is the first 4p-5p heterometallic {InIIIPbII} cluster-based nano-porous host framework, whose activated state possesses the coexistence of Lewis acid-base sites including 7-coordinated Pb2+ ions, 4-coordinated In3+ ions, uncoordinated carboxyl oxygen atoms, and Npyridine atoms. Performed catalytic experiments exhibited that activated NUC-52 owned the high catalytic activity on the cycloaddition reactions of styrene oxide with CO2 under mild conditions with excellent turnover number (2475) and turnover frequency (619 h−1). Moreover, activated NUC-52 could greatly accelerate the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile. Hence, this work lays down the groundwork for constructing heterometallic cluster-based nanoporous MOFs with excellent Lewis acidic catalysis and chemical stability, which should be ascribed to the reasonable coordination arrangement between organic ligands and distinct metal ions according to the hard–soft acid–base (HSAB) theory.
A highly robust {InPb}-organic framework with Lewis acid-base bifunctional features exhibits high catalytic activity on the cycloaddition reactions of epoxides with CO2 and deacetalization-Knoevenagel condensation reactions. Display omitted
•InPb-cluster-based honeycomb framework of NUC-52 can highly catalyze the cycloaddition of CO2 and deacetalization-Knoevenagel condensation.•Performed catalytic experiments exhibited that activated NUC-52 owned the high catalytic activity on the cycloaddition reactions of styrene oxide with CO2 under mild conditions with excellent turnover number (2475) and turnover frequency (619 h-1). Moreover, activated NUC-52 could greatly accelerate the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile.
Organic tracer compounds, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been ...investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006) field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3) were double those in late June (926 ± 574 ng m−3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, mean 403 ng m−3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3%). In contrast, isoprene SOC was the main contributor (6.6%) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (−26.6 to −23.2‰, mean −25.0‰) were lower than those (−23.9 to −21.9‰, mean −22.9‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic composition and stable carbon isotopic composition of aerosol particles in the troposphere over the North China Plain.
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