Environmental Information-Aided Electromagnetic Propagation Testbed for Maritime Communication

Maritime channel modeling can be affected by some key time-varying environmental factors.The ducting effect is one of the thorniest factors since it causes anomalous propagation enhancement and severe co-channel interference.Moreover,the atmospheric attenuation is much more severe in the ocean environment,resulting in shorter coverage distance and more link outage.In this paper,we propose an environmental information-aided electromagnetic propagation testbed.It is based on complex refractivity estimation and improved parabolic equation propagation model,taking into account both ducting effect and atmospheric attenuation.A large-scale temporal and spatial propagation measurement was conducted with meteorological acquisition.We consider practical path loss and ducting conditions to verify the testbed feasibility in these long-distance radio links.The simulation results are in good agreement with the measured data,which further reveal the basic temporal and spatial distribution of ducting effect at 3.5 GHz band.

Protective effect of paeonol on beta-amyloid 25-35- induced toxicity in PC12 cells

BACKGROUND：Paeonol is a primary phenolic component of the Chinese medicinal herb Cortex moutan. Recent studies have shown that paeonol has anti-inflammatory, analgesic, and antioxidative effects as well as a significant cardioprotective effect against myocardial ischemia. OBJECTIVE： To investigate the protective effect of paeonol on β-amyloid 25-35-induced toxicity in PC12 cells and analyze its mechanism of action. DESIGN, TIME AND SETTING： A controlled repeated-measures cell-based study was performed in the Department of Pharmacology of Guangdong Medical College between September 2006 and December 2007. MATERIALS： Paeonol was supplied by Xuancheng Baicao Plant Industry and Trade Company, China. PC12 cells were a kind gift from Dr. Haitao Zhang at Guangdong Medical College. β-amyloid 25-35 was purchased from Sigma Company, USA. Lactate dehydrogenase （LDH） and malondialdehyde （MDA） kits were purchased from Nanjing Jiancheng Bioengineering Research Institute, China. METHODS： PC12 cells were maintained in Dulbecco＇s modified eagle＇s medium （DMEM） supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum at 37 ℃ and cultured in an incubator with 5% CO2. The medium was renewed every other day. Batches of cells were assigned into three groups. （1） Paeonol group： cells were preincubated with different concentrations of paeonol （12, 25 or 50 μmol/L） for one hour and β-amyloid 25-35 was added to the medium; （2） control group： cells were cultured in DMEM supplemented with 100 mL/L heat-inactivated horse serum and 50 mL/L fetal bovine serum; and （3） β-amyloid 25-35 group： β-amyloid 25-35 was added to the medium. MAIN OUTCOME MEASURES： When PC12 cells in each group were cultured for 24 hours, the cell viability was determined using the MTT reduction assay, LDH release into the culture media was measured by 2,4-dinitrophenylhydrazine chromatometry and MDA content was measured using a thiobarbituric acid assay. RESULTS： When PC12 cells were treated withβ-amyloid 25-35 （50 μmol/L） for 24 hours, their viability was significantly lower compared with the control group （P 〈 0.01）. When the cells were treated with paeonol for one hour prior to incubation withβ-amyloid 25-35, their viability was significantly increased compared with theβ-amyloid 25-35 group （P 〈 0.05–0.01）. LDH activity and MDA level in the β-amyloid 25-35 group were significantly increased compared with the control group （P 〈 0.01）. When the cells were treated with different concentrations of paeonol, LDH activity and MDA level in PC12 cells were significantly decreased compared with theβ-amyloid 25-35 group （P 〈 0.01）. CONCLUSION： Paeonol protects PC12 cells againstβ-amyloid 25-35-induced toxicity and the protective effect of paeonol is probably achieved through its antioxidative effects.