OBJECTIVETo investigate the seasonal characteristics and the sources of elements and ions with different sizes in the aerosols in Beijing.

METHODSSamples of particulate matters (PM2.5), PM10, and total suspended particle (TSP) aerosols were collected simultaneously in Beijing from July 2001 to April 2003. The aerosol was chemically characterized by measuring 23 elements and 18 water-soluble ions by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and ion chromatography (IC), respectively.

RESULTSThe samples were divided into four categories: spring non-dust, spring dust, summer dust, and winter dust. TSP, PM10, and PM2.5 were most abundant in the spring dust, and the least in summer dust. The average mass ratios of PM > 10, PM2.5-10, and PM2.5 to TSP confirmed that in the spring dust both the large coarse (PM > 10) and fine particles (PM2.5) contributed significantly in summer PM2.5, PM2.5-10, and PM > 10 contributed similar fractions to TSP, and in winter much PM2.5. The seasonal variation characteristics of the elements and ions were used to divide them into four groups: crustal, pollutant, mixed, and secondary. The highest levels of crustal elements, such as Al, Fe, and Ca, were found in the dust season, the highest levels of pollutant elements and ions, such as As, F-, and Cl-, were observed in winter, and the highest levels of secondary ions (SO4(2-), NO3-, and NH4+) were seen both in summer and in winter. The mixed group (Eu, Ni, and Cu) showed the characteristics of both crustal and pollutant elements. The mineral aerosol from outside Beijing contributed more than that from the local part in all the reasons but summer, estimated using a newly developed element tracer technique.

Aerosols ; China ; Chromatography, Ion Exchange ; Environmental Monitoring ; Particle Size ; Particulate Matter ; analysis ; chemistry ; Seasons ; Spectrophotometry, Atomic

Objective To investigate the effects of duration of untreated psychiatry (DUP) on the white matter integrity in first-episode medication-free patients with schizophrenia. Methods The Chinese version of Nottingham Onset Schedule was used to assess the DUP of 39 first-episode medication-free patients with schizophrenia. According to the median of DUP, the 39 patients were grouped into long-DUP group and short-DUP group. Diffusion weighted images of the 39 patients' whole brains were acquired with a Half-Fourier Acquired Single-Shot Turbo Spin Echo (HASTE) sequence.After being preprocessed with DTI-studio and statistical parametric mapping software (SPM5), the fractional anisotropy (FA) images of the 2 groups were compared by two-sample t-test with SPM5 software. The differences of gender, age, education level and total scores of Positive and Negative Syndrome Scale (PANSS) scores between the 2 groups were also detected. Results No significant difference was noted on gender, age, education level, PANSS scores between the 2 groups (P＞0.05).Subjects of long-DUP group showed significantly reduced FA value in the right anterior cingulate fasciculus (x=8, y=40, z=24) and left prefrontal white matter thresholded (x=32, y=34, z=4) as compared with that of short-DUP group at a level of P＜0.001 (uncorrected). Conclusion Extension of the duration of DUP will reduce the white matter integrity in first-episode medication-free patients with schizophrenia.