[Profile Characteristics of VOCs from Wood and Economic Crop Burning].

Wood and economic crops are still widely used in rural areas of China. Although their combustion is an important source of volatile organic compounds (VOCs), study on their emission characteristics is relatively weak. In this study, three kinds of wood (poplar, cedarwood, and citrus branches) and six economic crop straws (soybean stalk, sesame stalk, corn cob, cotton stalk, peanut stalk, and corn stalk) were selected and their burning was simulated in the laboratory. A dilution tunnel system was used to dilute the smoke, and then Tedlar bags were used to collect the smoke. The compositions of 102 VOCs were analyzed by Agilent 7820A/5977E gas chromatography/mass spectrometry. The ozone formation potential (OFP) of VOCs for different types of biomass burning was analyzed. The results indicated that there are differences in the VOC compositions of different types of biomass burning emissions. Ethane (11.1%), trans-2-pentene (15.4%), ethylene (8.3%), and dichloromethane (11.9%) are the main VOCs emitted from poplar and cedarwood burning. Toluene (49.8%) is the most abundant species of VOC emitted from burning of citrus branches. Ethylene (11.8%-17.5%) and acetone (9.2%-14.7%) are the main VOCs components of straw burning. Corn stalks, peanut stalks, and citrus branches have similar VOC source profiles, with the coefficient of divergence less than 0.1. The benzene/toluene ratio for biomass burning emissions obtained in this study and in the literature is in the range of 0.030-6.48. It is arguable that a value higher than 1 indicated the impact of biomass burning. The contributions of alkenens, oxygenated VOCs, and aromatic hydrocarbons to the OFP of biomass burning were 30.6%-80.3%, 6.5%-21.0%, and 3.8%-56.5%, respectively. The components contributing more than 10.0% to the OFP are ethylene, propylene, trans-2-pentene, cis-2-pentene, toluene, and propionaldehyde.

Anti-cyclic citrullinated peptide antibody predicts the development of rheumatoid arthritis in patients with undifferentiated arthritis / 中华医学杂志(英文版)

BACKGROUND@#Clinical outcomes of undifferentiated arthritis (UA) are diverse, and only 40% of patients with UA develop rheumatoid arthritis (RA) after 3 years. Discovering predictive markers at disease onset for further intervention is critical. Therefore, our objective was to analyze the clinical outcomes of UA and ascertain the predictors for RA development.@*METHODS@#We performed a prospective, multi-center study from January 2013 to October 2016 among Chinese patients diagnosed with UA in 22 tertiary-care hospitals. Clinical and serological parameters were obtained at recruitment. Follow-up was undertaken in all patients every 12 weeks for 2 years. Predictive factors of disease progression were identified using multivariate Cox proportional hazards regression.@*RESULTS@#A total of 234 patients were recruited in this study, and 17 (7.3%) patients failed to follow up during the study. Among the 217 patients who completed the study, 83 (38.2%) patients went into remission. UA patients who developed RA had a higher rheumatoid factor (RF)-positivity (42.9% vs. 16.8%, χ = 8.228, P = 0.008), anti-cyclic citrullinated peptide (CCP) antibody-positivity (66.7% vs. 10.7%, χ = 43.897, P < 0.001), and double-positivity rate of RF and anti-CCP antibody (38.1% vs. 4.1%, χ = 32.131, P < 0.001) than those who did not. Anti-CCP antibody but not RF was an independent predictor for RA development (hazard ratio 18.017, 95% confidence interval: 5.803-55.938; P < 0.001).@*CONCLUSION@#As an independent predictor of RA, anti-CCP antibody should be tested at disease onset in all patients with UA.

[Emission Factors of Heavy Metals in Size-resolved Particles Emitted from Residential Coal Combustion].

Based on a dilution sampling system and domestic burning tests, size-segregated particles emitted from burning of three kinds of honeycomb coals (in view of flaming and smoldering burning conditions) and four kinds of raw coals, were collected by cascade impactors (FA-3). The contents of V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sb, and Pb were analyzed to get their emission factors (EFs) in different particle size fractions. Results indicated that:① Zn and Pb dominated the emitted mass of heavy metals from chunk (53.16%-65.76%) and honeycomb (96.08% in 0.43 µm) during the flaming combustion condition. However, the emission of Ni was increased from 30.70% to 52.36% in the smoldering condition. Thus, combustion condition may affect the composition of heavy metals in particle matters. ② In the flaming condition, both chunk and honeycomb emission factors of heavy metals were concentrated under 1.1 µm, while the larger sized particles in the range of 5.8-10 µm were distributed. So, heavy metal components may shift to the larger size of the particles at lower combustion temperatures. ③ Fine particle matters(PM) was divided into three categories based on the size distribution of 11 kinds of heavy metal emission factors. The maximum emission values of As and V fell under the PM size category of 5.8-10 µm. The fourth cycle transition metal elements, such as Cr, Mn, Cu, Ni, and Co, fell in the range of 1.1-2.1 µm and these elements represented similar emission characteristic features. Other elements, such as Pb, Sb, Cd, and Zn, were concentrated in sizes less than 0.43 µm. ④ The additive in the honeycomb during the process may import several kinds of heavy metals and may change the combustion temperature, which remodels the mechanism of heavy metal emission. Thus, honeycomb coal may emit different heavy metals under different combustion conditions.The heavy metal emission mechanism during honeycomb coal combustion needs further investigation and the emission reduction effects (especially of heavy metals) needs to be re-estimated.

[Size-resolved Emission Factors of Carbonaceous Particles from Domestic Coal Combustion in China].

China is one of the most important contributors to the global burden of carbonaceous aerosols, of which domestic coal combustion occupies a large fraction. Uncertainty in the emission factors (EFs) directly influences the accuracy of corresponding emission inventories. In the present study, based on domestic burning tests with a dilution sampling system, nine size-segregated particle classes emitted from the burning of three kinds of honeycomb coals (under flaming and smoldering burning conditions) and four kinds of chunk coals, including bituminous and lignite, were collected via a cascade impactor (FA-3). Organic and elemental carbon (OC and EC, respectively) were analyzed using the thermal-optical method. The EFs of particulate matter (PM), OC, and EC for nine size ranges were obtained. For honeycomb coals, the EFs of OC and EC in PM2.1 were 0.07 g·kg-1 and 0.002 g·kg-1, respectively, under flaming burning conditions and 0.10 g·kg-1 and 0.001 g·kg-1, respectively, under smoldering burning conditions. Carbonaceous particles exhibited higher EFs under flaming burning conditions. For chunk coals, the EFs of OC and EC in PM2.1 were 1.4 g·kg-1 and 0.02 g·kg-1, respectively, which are about one magnitude higher than those for honeycomb coal burning. Particulate matter and its associated carbonaceous components preferred to concentrate in fine particles. The EFs of carbonaceous components peaked at the size of ≤ 0.43 µm and 0.43-0.65 µm for honeycomb coal burning and chunk coal burning, respectively.