V Zaroushani, A Khavanin, S Mortazavi, A Jonidi Jafari, M Moeini, M Javadzadeh,
Volume 12, Issue 5 (11-2015)
Abstract
Background and aims: X-band microwave with 8-12.5 frequency range has various applications such as air control traffic, navy communication and etc. Uncontrolled exposure with microwave can lead to adverse effect on workers. Application of the shielding is superior control for prevention of microwave exposure.The aim of this study is production a new electromagnetic shielding for exposure control of X-band frequency by nano nickel oxide and epoxy resin.
Method: Nanocomposites prepared by epoxy resin and nano nickel oxide (7wt %) with 2, 4 and 6 mm thicknesses. Nanoparticles characterized by XRD and FESEM. Shielding effectiveness measured with vector network analyzer.
Results: The Average of shielding effectiveness for three thicknesses were 2.68, 5.09 and 5.35 dB respectively that were equivalent to 45.98, 69.01 and 70.87 attenuation percentage. Maximum attenuation (8.96 dB or 87.29 attenuation percentage) obtained by the nanocomposite with 6mm thickness at 8.51 GHz frequency. The Average of shielding effectiveness increased with increasing the thickness.
Conclusion: these nanocomposites could be used as appropriate shielding for exposure control of X-band frequency in workplace .Both Epoxy and nanocomposite with 6mm thicknesses are useful in specific frequency such as 8.52 and 8.51 GHz. However, According to economical and technical issues, nanocomposite with 4mm thickness is appropriate shield in this study. In according to required attenuation and economical benefit, attenuation matrix can be used for selecting the appropriate electromagnetic shield. Keyword: electromagnetic shielding, microwave, nanocomposite, nickel oxide, epoxy, radiation
V Zaroushani, A Khavanin, Sb Mortazavi, A Jnonidi Jafari,
Volume 13, Issue 1 (4-2016)
Abstract
Background and aims: X-band with 8-12.5 frequencies range has various applications such as air control traffic, navy communication and etc. Uncontrolled exposure with microwave can lead to adverse effect on workers. Application of the shielding is superior control for prevention of microwave exposure, now. This study investigated the effect of dispersion on shielding effectiveness improvement about a novel nanocomposit shiled.
MethodS: Nanocomposites prepared by epoxy resin and nano nickel oxide (7wt %) with 2, 4 and 6 mm thicknesses. In order to investigate the effect of dispersion , 10 and 66 minutes was considered as mixing time . Nanoparticles characterized by X-ray Diffraction and Field Emission Scanning Electron Microscope. Shielding effectiveness measured with vector network analyzer.
Results: Dispersion of nanoparticles in group 2-nanocomposites was better than group 1- nanocomposites. Average of percentage attenuation in group 2-nanocomposites was better than group 1- nanocomposites. The Average of shielding effectiveness for three thicknesses in group 1 was 46.5, 69.03 , 70.83 and for group 2 was 52.02%, 78.48% and 84.14 %dB, respectively. Maximum attenuation obtained by the 6mm thickness in group 2- nanocomposites at 8.8 GHz frequency (91.12%). The Average of shielding effectiveness increased with increasing the thickness.
Conclusion: with increasing the mixing time, the dispersion and shielding effectiveness be improved. These nanocomposites could be used as appropriate shielding for exposure control of X-band frequency in workplace and nanocomposite with 4mm thickness is appropriate shield in this study. Both 4mm and 6mm thicknesses in group2 are useful in specific frequency such as 8.8 and 12.5 GHz .the average of percentage attenuation for above thicknesses is more than 87%. Keyword: electromagnetic shielding, microwave, nanocomposite, nickel oxide, electromagnetic radiation, dispersion
Ali Khavanin, Ahmad Jonidi Jafari, Saeid Ahmadi, Vida Zaroushani,
Volume 15, Issue 3 (8-2018)
Abstract
Background and aims: Radio frequency and microwaves radiations are a part of non-ionizing electromagnetic radiation that have various applications in different work environments. Administrative measures reduce the occupational exposure with low cost and acceptable performance. This study using narrative review was conducted to investigate the recommended administrative controls that published by international organizations in order to control the occupational exposure to Radio Frequency and microwave radiations.
Methods: Firstly, the international reference organizations were determined in relation to the research topic. Then, based on the PICO principle, related keywords designed. Then, all documents as a Government Document, Legal Rule or Regulation, Publication, Standard, Report, Guideline, Manual, were reviewed in English language without time limit. In addition, the search was conducted on two external databases (BING and GOOGLE). Then, the process of reviewing, screening and eliminating repeated, unrelated, and unusable resources was carried out. After preparation of the full text, the process of translation and extraction of related information conducted based on the organizations and administrative measures. In this study, experimental research, descriptive studies, analytical studies, Meta-analyzes, and systematic reviews, did not entry. Also, documents with incomplete and obscure information were also not used.
Results: The results of this study showed that there are several international organizations that work up in field of occupational exposure control to radiofrequency and microwave radiation. extracted administrative measures are diverse and including the inspection, medical monitoring, employee participation, safe/standard operating procedure, compliance with standards, preventive maintenance, lock out/ tag out, safety signs and warnings, workplace monitoring, Responsibility of the employer, exposure limit, access restrictions, reducing output energy, training and distance .
Conclusion: Meanwhile, exposure limits, maintenance process and access restrictions were the most recommended administrative controls. Among the international organization, the International Labor Organization (ILO) presented the most diverse and comprehensive administrative controls. It is suggested that the results of this study be used in health and safety radiation policies and as a simple guide to introduction on recommended administrative measures for managers and occupational and environmental health experts.
Saeed Rahmani, Alireza Akbarzadeh Baghban, Mohammadreza Nazari, Mohammad Ghassemi-Broumand,
Volume 19, Issue 1 (3-2022)
Abstract
Background and Aims: Solar spectrum is composed of different wavelengths that some of them may lead to various ocular diseases. The aim of this study was to investigate the effectiveness of sunglasses in filtering harmful light.
Methods: In this cross-sectional study, 56 pairs (112 lenses) of branded sunglasses randomly collected from different importing companies. A spectrophotometer was used to measure blue light transmission. For statistical analysis, non-parametric Mann-Whitney and Kruskal-Wallis tests were used. A P ≤ 0.05 was considered statistically significant.
Results: The mean UVA and UVB transmission of the sunglasses were 0.16±1.21% and 0.01±0.06 %, respectively. The mean blue light transmission of the sunglasses was 10.03 ± 3.91 %. The effect of different colors on the blue light transmission was significant (P≤0.001). Polarization and visible light transmission of the sunglasses had no significant effect on blue light transmission (P=0.3).
Conclusion: The effectiveness of available sunglasses to filter hazardous light was acceptable, and brown colored sunglasses was the best option to filter of the blue light.
