new microwave shield preparation for super high frequency range: occupational approach to radiation protection

Background: Widespread use of X-band frequency [a part of the super high frequency microwave] in the various workplaces would contribute to occupational exposure with potential of adverse health effects

According to limited study on microwave shielding for the workplace, this study tried to prepare a new microwave shielding for this purpose

Methods: We used El-403 epoxy thermosetting resin as a matrix and nickel oxide nanoparticle with the diameter of 15-35 nm as filler. The Epoxy/ Nickel oxide composites with 5, 7, 9 and 11 wt% were made in three different thicknesses [2, 4 and 6 mm]

According to transmission / reflection method, shielding effectiveness [SE] in the X-band frequency range [8-12.5 GHz] was measured by scattering parameters directly given by the 2-port Vector Network Analyzer. The fabricated composites characterized by X-ray Diffraction and Field Emission Scanning Electron Microscope

Results: The best average of shielding effectiveness in each thickness of fabricated composites obtained by 11%-2 mm, 7%-4 mm and 7%-6 mm composites with SE values of 46.80%, 66.72% and 64.52%, respectively. In addition, the 11%-6 mm, 5%-6 mm and 11%-4 mm-fabricated composites were able to attenuate extremely the incident microwave energy at 8.01, 8.51 and 8.53 GHz by SE of 84.14%, 83.57 and 81.30%, respectively

Conclusions: The 7%-4mm composite could be introduced as a suitable alternative microwave shield in radiation protection topics in order to its proper SE and other preferable properties such as low cost and weight, resistance to corrosion etc. It is necessary to develop and investigate the efficacy of the fabricated composites in the fields by future studies

Investigating the effects of noise exposure on intensification of diabetes mellitus, serum glucose, cortisol level and body weight of the male mice

Noise is considered as one of the harmful factors at industrial environments. It affects human health in different aspects including harmful influences on auditory, vision, neurological and psychiatric systems, hormones, physiological and mental systems. Paying attention to the importance of hormonal effects on human body seems to possess crucial importance. The aim of the present study is to investigate the effects of noise exposure on variation of serum levels of glucose and cortisol at Syrian adult male mouse. 36 Syrian male adult mice were randomly categorized into two experiment and control groups. Garlic powder was added to the mice pelleted food meal [equal to 1% of their daily diet] to study its effect on the cortisol and glucose serum levels. The mice pelleted food contains starch, glucose, isolated soya protein, etc., which are the rich resources of A, C, B1, B2 and B6 vitamins. Streptozotocin [60mg/kg] was injected to the mice at experiment group which were under noise exposure with intensity of 90dB in frequency range of 700-5700Hz. Noise were generated using CoolEdit software and distributed to the fabricated box for 30 days [8h/d]. Fasting cortisol and glucose serum levels were measured for mice of both groups 24h after finishing the exposure period. Results indicated that the glucose serum level in non-diabetic and diabetic subjects under noise exposure had significant difference [p<0.002] with the subjects at control group. Also, cortisol level in non-diabetic and diabetic subjects under noise exposure indicated significant difference [p<0.002] with the subjects at control group. Exposure to noise with intensity of 90dB at frequency range of 700-5700Hz increases the glucose and cortisol serum levels

Modeling the factors affecting unsafe behavior in the construction industry from safety supervisors' perspective

There can be little doubt that the construction is the most hazardous in-dustry in the worldwide. This study was designed to modeling the factors affecting un-safe behavior from the perspective of safety supervisors. The qualitative research was conducted to extract a conceptual model. A structural model was then developed based on a questionnaire survey [n=266] by two stage Structural Equation Model [SEM] approach. An excellent confirmed 12-factors structure explained about 62% of variances unsafe behavior in the construction industry. A good fit structural model indicated that safety climate factors were positively correlated with safety individual factors [P<0.001] and workplace safety condition [P<0.001]. The workplace safety condition was found to play a strong mediating role in linking the safety climate and construction workers' en-gagement in safe or unsafe behavior. In order to improve construction safety performance, more focus on the workplace condition is required.

Exposure to noise pollution and its effect on oxidant and antioxidant parameters in blood and liver tissue of rat

Noise is a known physical stress in workplace, which induces alterations of various physiological responses in exposed individuals. Aim of this study was to explore the status of oxidant and antioxidant parameters in blood and liver tissue of rats exposed to noise. Twenty-one adult albino wistar male rats seven in each of the following groups were used [N=7]: 1- Control group, 2- Noise exposure [100 dB, 700-5700 Hz, 8 h/day, 8 days], 3- Noise exposure [100 dB,700-5700 Hz, 8 h/day, 14 days]. The animals were anesthetized by CO[2] and after decapitation, blood and liver samples were collected and processed for estimation of biochemical parameters [MDA and GSH levels] in control and exposed groups. The present research findings showed significant decrease in liver weight and liver/body weight ratio in noise exposed groups compared to the control group [p<0.05]. Fourteen days noise exposure caused a statistically significant increase in MDA level in serum and liver tissue and also statistically significant decrease in GSH level in serum [p<0.05], however, the level of GSH in the liver tissue showed no significant change. 8-days exposure just caused a statistically significant increase in MDA level in serum, and there was no significant change in the other parameters. Moreover, the levels of changes in biochemical parameters in noise exposed groups were exposure time-dependent. The results of present study showed that exposure to noise is toxic to blood and liver tissue. Further research for exploring the toxicity of noise in occupationally exposed groups is recommended

Report of 267 cases of scorpion bite referring to an emergency department during one year

Scorpion bite is a common health problem in many parts of the world, including the Iran's tropics. There are thousands of cases and a number of deaths due to scorpion bite every year in the country. The present study aims to provide further data regarding the details, complications and outcomes of scorpion bite cases referring to Razi Hospital, Ahwaz, from March 2011 to April 2012. 267 patients [56.3% females] with a mean age of 35.2 +/- 15.8 years were included in the study. The most common genus of scorpion involved was Hemiscorpius [69.3%] and the most frequent body part involved was the lower limb [38.9%]. The frequency of hemolysis-induced renal insufficiency and death after scorpion bite were 1.9% and 1.1%, respectively. Of all the factors evaluated in this series only the old age was associated with higher possibility of renal insufficiency [P<0.001]

Adverse effects of formaldehyde vapor on mouse sperm parameters and testicular tissue

Formaldehyde [FA], one of the simplest organic molecules, is a flammable, pungent, irritating and colorless gas. This study aimed to investigate the effects of various concentrations of FA vapor on sperm parameters and testicular tissue. In this experimental study, we randomly assigned 36 adult male mice to one control and two experimental groups [n=12 for each group]. The control group [C] did not receive FA. Group F1 [low concentration] was exposed to 10 ppm FA vapor and the F2 [high concentration] group was exposed to 20 ppm FA vapor. FA was administered for ten days, eight hours per day for both groups. At the end of the exposure period, half of the animals in each group were sacrificed 24 hours after exposure to detect any short-term effects; the rest of the mice were sacrificed 35 days later to assess for long-term effects. Sperm parameters were analyzed by Computer-assisted Sperm Analyzer [CASA] and histological changes determined. In addition, we studied changes in testosterone hormone. Data were analyzed by one-way ANOVA followed by the Scheffe test using SPSS software. Long-term effects of FA in the experimental groups included significant reductions in sperm cell numbers and sperm viability. A drastic reduction in progressive motility and increased abnormal sperm percentage [p<0.001] compared with the control group was also noted. Histological study of testes specimens in the experimental group revealed displacement of germinal cells, along with degeneration of Leydig cells and seminiferous tubules. Exposure to FA vapor can destroy testicular structure and decrease percentages of concentration, viability, normal morphology, and progressive motility, in addition to increasing the percentage of immotile sperm

effects of cell phone waves [900 MHz-GSM Band] on sperm parameters and total antioxidant capacity in rats

There is tremendous concern regarding the possible adverse effects of cell phone microwaves. Contradictory results, however, have been reported for the effects of these waves on the body. In the present study, the effect of cell phone microwaves on sperm parameters and total antioxidant capacity was investigated with regard to the duration of exposure and the frequency of these waves. This experimental study was performed on 28 adult male Wistar rats [200-250 g]. The animals were randomly assigned to four groups [n=7]: i. control; ii. two-week exposure to cell phone-simulated waves; iii. three-week exposure to cell phonesimulated waves; and iv. two-week exposure to cell phone antenna waves. In all groups, sperm analysis was performed based on standard methods and we determined the mean sperm total antioxidant capacity according to the ferric reducing ability of plasma [FRAP] method. Data were analyzed by one-way ANOVA followed by Tukey's test using SPSS version 16 software. The results indicated that sperm viability, motility, and total antioxidant capacity in all exposure groups decreased significantly compared to the control group [p<0.05]. Increasing the duration of exposure from 2 to 3 weeks caused a statistically significant decrease in sperm viability and motility [p<0.05]. Exposure to cell phone waves can decrease sperm viability and motility in rats. These waves can also decrease sperm total antioxidant capacity in rats and result in oxidative stress

Removal of styrene from air by natural and modified zeolite

Changing the surface characteristics of raw materials has created new prospects for catalysts and adsorption technology. Natural and modified zeolite with trimethylchlorosilane [TMSCI] has been used to adsorb styrene. Dynamic adsorption tests were performed with a number of standard characterization techniques and zeolite particles were examined in three sizes: less than 1 mm, 1-2 mm, and 2-4 mm. The gas concentration was 20 ppm, 40 ppm, and 60 ppm. Three flow rates were tested in this study: 0.5 l/min, 0.75 l/min, and 1 l/min. The sorption of Styrene depended on the particle diameter size, gas flow rate, and inlet gas concentration. The optimum size for adsorption was less than 1 mm, the optimum flow rate was 0.5 l/min, and the optimum gas concentration was 20 ppm. The adsorption capacity decreased with increasing size, flow rate, and concentration of the pollutant. The adsorption by the surface-modified zeolite increased by as much as 100% compared with natural zeolite. Therefore, the surface-modified natural zeolite may be utilized for many adsorption applications. This study shows the importance of chemical surface modification and confirms similar findings of other studies

[Study of noise effects on rabbit's hearing status using distortion product otoacoustic emissions]

Noise-induced hearing loss is the most common problem in industrial areas. This study aimed to determine effects of excessive noise exposure on measurable characteristics of distortion product otoacoustic emissions [DPOAEs] in rabbits. The study was carried out on 12 adult male New Zealand White rabbits including case group - exposed to 500-8000 Hz broadband white noise with 100 dBA SPL for 8 hours per day in 5 consecutive days - and control group. After three days period of acclimatization to the experimental condition, rabbits' hearing status in each group were measured by distortion product otoacoustic emissions on days zero means before the study was initiated as a baseline, eight, one hour after the latest exposure to noise, and ten. The recorded results were analyzed using SPSS software. Highest mean distortion product otoacoustic emissions amplitudes in case group were allocated to frequencies of 5888.50 Hz, 8166.50 Hz, 9855.00 Hz, 3956.00 Hz, and 3098.50 Hz, respectively. However, the lowest mean distortion product otoacoustic emissions amplitude was related to frequency of 588.00 Hz [p=0.001]. This study revealed that distortion product otoacoustic emissions amplitude shifts due to noise occur first in high and then in middle frequencies. Additionally, exposure to noise can decrease distortion product otoacoustic emissions amplitudes. We conclude that distortion product otoacoustic emissions can be a reliable test for estimating personal susceptibility to noise-induced hearing loss

[ effect of hydrogen peroxide and solvent on photolysis of PCBs to reduce occupational exposure]

Polychlorinated biphenyls [PCBs] are toxic bio-accumulate components and may increase risk of adverse effects on human health and the environment. For different social, technical and economic reasons, significant quantities of PCBs contaminated transformer oil are still in use or storied. The study aimed to determine the effect of hydrogen peroxide and solvent on photolysis of PCBs to reduce occupational exposure. The photochemical annular geometry [500 ml volume] reactor was designed with a cylindrical low-pressure mercury lamp [UV-C Cathodeon TUV 6WE] with emission at 254 nm. The radiant power emitted by the lamp was 6w. The whole lamp was immersed in a reactor thermostat controlling of temperature at 32 +/- 2 oC. The PCBs was determined using GC/ECD and data was analyzed by SPSS. Degradation of total PCBs in terms of%10 and%20 of volume of H2O2 were 41%, 75% and 94%, respectively. The degradation of total PCBs in terms of ratio to solvent with oil transformer in 1:1, 2:1 and 3:1 was 61%, 75% and 94%, respectively. Our study show that UV-C photolysis of H2O2 leads to a degradation efficiency of PCBs only in the presence of isooctane, therefore indicating that the intermediates formation after ethanol oxidation are able to initiate PCBs degradation

[Manufacturing sound absorber based on combined recycling of polyethylene trephetalat and polystyrene at low and median frequencies]

Noise pollution is one of the main cause of occupational hearing loss. According to WHO reports in many countries workers have been exposed to 85 - 90 dB noise level. The purpose of this study is to manufacture a sound absorber based on combined recycled polyethylene trephetalat [PET] and polystyrene [PS] with an economical method in order to control noise pollution. Sound absorber was made of PET and PS with equal weight percent, polyester fiber, and polyvinyl acetate resine, with five to ten centimeters thick. Sound mean absorption coefficient percents were determined by acoustic impedance tube and compared with those of rock wool. Mean absorption coefficient percent of samples with one to five millimeter pore size and ten centimeters thickness was significantly better than those with six to twenty millimeters pore size in 50 to 630, 1250, and 1600 Hz, [p<0.05]. In general, samples mean absorption coeficient was significally different from those rock wool [p=0.005]. Recycle polymer absorbers may play an important role in national economics as they are prophylactic to some occupational disease and also are economical