ABSTRACT
Ice clouds affect the energy balance of the atmosphere through absorption, reflection, and scattering of solar radiation. We have developed a new experimental technique to simultaneously measure thin ice film extinction and its thickness (about 0.06-0.21 µm) by combining Brewster angle cavity ring-down spectroscopy and quartz crystal microbalance. The ice film serves as a proxy for ice clouds. Thin ice films were formed by water vapor deposition on a silica surface at 258 K. The average extinction cross sections of ice films were determined to be about 6.6 × 10-23, 8.1 × 10-23, 5.3 × 10-23, 5.6 × 10-23, 5.2 × 10-23, 5.1 × 10-23, and 3.9 × 10-23 cm2/molecule at wavelengths of 290, 300, 310, 320, 330, 340, and 350 nm at 258 K, respectively. Atmospheric implications of the results are discussed.
ABSTRACT
OBJECTIVE: To analyze the relationship between environmental lead exposure and various types of brain tumors. METHODS: Search databases PubMed, Web of Science, Embase and Chinese National Knowledge Infrastructure (CNKI) as of July 1, 2019. Stata 15.0 software was used for analysis. RESULTS: In the case control, lead exposure was associated with gliomas and meningiomas 0.82 (95 % CI: 0.69, 0.95) and 1.06 (95 % CI: 0.65, 1.46). In the cohort study, lead exposure was associated with brain cancer and meningiomas 1.07 (95 % CI: 0.95, 1.19) and 1.06 (95 % CI: 0.94, 1.17). The risk of childhood brain tumors associated with parental lead exposure was 1.17 (95 % CI: 0.99, 1.34). CONCLUSIONS: Lead may be a risk factor for meningiomas and brain cancers. However, the glioma results suggest that lead may be a protective factor, which needs to be further studied.
