OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Afewerki Tesfagabr” ,找到相关结果约2条。
Assessment of the Levels of Brominated Flame Retardants in Computers and Televisions in Selected Regions of Eritrea  [PDF]
Afewerki Tesfagabr, Tesfamichael Haile, Mussie Sium, Teame Tekleab
Open Access Library Journal (OALib Journal) , 2018, DOI: 10.4236/oalib.1105061
During recent years, electronic waste (e-waste) around the world is growing at a fast rate and has become a matter of concern due to the presence of toxic brominated flame retardants (BFRs) and certain heavy metals. Currently, in Eritrea there is low awareness on the harmful effects of e-wastes, lack of proper storage facilities and no proper policy and legislative framework related to e-wastes. Thus, in most cases e-wastes still reside in homes, offices, and some are stored with other materials in different places. Therefore, the objective of the present study was to assess the levels of BFRs in obsolete as well as in lately imported computers and televisions using hand held hazardous substances analyzer—Genius 3000 XRF. The survey was done in selected regions of Eritrea and thus a total of 223 samples of computers and TVs from 78 different products were screened. Three readings at forty seconds were conducted for each sample and the average value was calculated. From 173 sampled computers, both oldest and lately imported products, different levels of Br were measured varying from the lowest detectable amount (0.3689 ppm) to the highest (87,821 ppm). Similarly, out of 50 screened old and new models of TVs various levels of Br were determined with minimum detectable level (1.5793 ppm) and highest level (80,916 ppm). The analysis displayed high levels of Br both in the obsolete and lately manufactured products. The concentration of Br didn’t show any consistency either to the product type or manufacturing time. This is a very first preliminary study conducted related to the levels of BFRs in electronic wastes in the country and thus in order to evaluate the environmental impacts and health hazards caused by BFRs and other toxic materials of e-wastes, further study using advanced analytical methods is mandatory.
Equatorial scintillations in relation to the development of ionization anomaly
R. H. Wiens, B. M. Ledvina, P. M. Kintner, M. Afewerki,Z. Mulugheta
Annales Geophysicae (ANGEO) , 2006,
Abstract: An all-sky imager was installed in Asmara, Eritrea (15.4° N, 38.9° E, 7° N dip) and used to monitor the OI 630-nm nightglow. Nine months of data were studied between September 2001 and May 2002, a time including the recent maximum in the solar activity cycle. Equatorial plasma bubbles (EPBs) were recorded on 63% of nights with adequate viewing conditions. The station location within view of the equatorial ionization anomaly and with a magnetic declination near zero makes it an excellent test case for comparison with satellite studies of the seasonal variation of EPBs with longitude. The imager was accompanied by two Cornell GPS scintillation monitors, and the amplitude scintillation data are compared to the all-sky data. GPS scintillations indicate the beginning of EPBs, but die out sooner in the post-midnight period than the larger scale EPBs. Both phenomena exhibit clear occurrence maxima around the equinoxes. Ionospheric zonal drift speeds have been deduced from EPB and GPS scintillation pattern movement. Average near-midnight EPB drift speeds are between 100 and 120 m/s most months, with the GPS scintillation speeds being about the same. A winter drift speed maximum is evident in both EPB and GPS scintillation monthly means.

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