ABSTRACT
Objective To study the pollution and source apportionment differences of different periods PM2.5 in the residential community of suburb in Tianjin City during heating and non-heating periods. Methods From 2015 to 2016, daytime and nighttime PM2.5 samples were collected at a community in the suburb of Tianjin. The mass concentration of PM2.5 samples and major chemical components in PM2.5, including metal elements, polycyclic aromatic hydrocarbons (PAHs) and inorganic water-soluble ions were monitored. Positive matrix factorization (PMF) model was used to apportion potential sources of metal elements, PAHs and inorganic water-soluble ions in daytime and nighttime PM2.5. Results In the heating period, the concentrations of some metal elements of suburban residential community were higher in the daytime than in the nighttime. In the non-heating period, the concentrations of some PAHs and inorganic water-soluble ions of suburban residential community were higher in the nighttime than in the daytime. Meanwhile, the concentrations of some metal elements were greater in the daytime than in the nighttime. When in heating period, the main source of PM2.5 in the suburban residential community was coal combustion during daytime and its source contribution rate was 50.1% while secondary aerosol and fuel combustion emissions of gasoline and diesel vehicles were main sources during nighttime and their source contribution rates were 41.0% and 35.9%. The principal source of daytime PM2.5 in the suburban residential community was indoor activity emissions during non-heating period, and secondary aerosol was main source during nighttime and their source contribution rates were 29.8% and 31.1%. Conclusions The pollution status of PM2.5 in residential communities of suburban is serious, and the source apportionment of day and night PM2.5 samples has different in different heating periods.
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BACKGROUND: Hypothermia is associated with poor outcome in trauma patients; however, hemorrhagic shock (HS) model with anesthetized swine was different from that of clinical reality. To identify the effects of environmental hypothermia on HS, we investigated hemodynamics and oxygen dynamics in an unanesthetized swine model of HS under simulating hypothermia environment.METHODS: Totally 16 Bama pigs were randomly divided into ambient temperature group (group A) and low temperature group (group B), 8 pigs in each group. Venous blood (30 mL/kg) was continuously withdrawn for more than 15 minutes in conscious swine to establish a hemorrhagic shock model. Pulmonary arterial temperature (Tp), heart rate (HR), mean arterial pressure (MAP), pulmonary arterial pressure (PAP), pulmonary arterial wedge pressure (PAWP), central venous pressure (CVP), cardiac output (CO), hemoglobin (Hb), saturation of mixed venous blood (SvO2) and blood gas analysis were recorded at the baseline and different hemorrhagic shock time (HST). The whole body oxygen delivery indices, DO2I and VO2I, and the O2 extraction ratio (O2ER) were calculated.RESULTS: Core body temperature in group A decreased slightly after the hemorrhagic shock model was established, and environmental hypothermia decreased in core body temperature. The mortality rate was significantly higher in group B (50％) than in group A (0％). DO2I and VO2I decreased significantly after hemorrhage. No difference was found in hemodynamics, DO2I and VO2I between group A and group B, but the difference in pH, lactic acid and O2ER was significant between the two groups.CONCLUSION: Environmental hypothermia aggravated the disorder of oxygen metabolism after hemorrhagic shock, which was associated with poor prognosis.
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Objective To evaluate the relationship between Multi-slices spiral(MSCT) perfusion and microvessel density (MVD) in maxillofacial tumors. Methods Thirty-one cases of maxillofacial tumors were studied with MSCT perfusion imaging before operation. The time-density curve, perfusion, time to peak(TTP), and Peak enhancement imaging (PEI) of tumors were calculated. MVD of the tumors was measured with immuno-histochemical method by means of detecting factor Ⅷ in all the histologic specimens. Relativity analysis was carried between MSCT perfusion imaging parameters, perfusion curve types and MVD. Results MVD of maxillofacial tumors were higher than normal tissue. MVD remarkably correlated with malignancy of the tumors. Perfusion and time to peak (TTP) correlated well with MVD(t=7.09,4.10, P0.05). Significant difference of MVD in three types of perfusion curve was found(F=8.09,P