Iranian Journal of

Background and Objective: Efforts to improve the effectiveness of noise barriers have been made, including shape, aesthetics, form and gender. Therefore, the aim of this study was to investigate the effect of the angle upper edge in shaped noise barriers with a T-shaped upper edge.
Materials and Methods: A 2D boundary element method (BEM) was used to predict the insertion loss of the tested barriers. The results obtained from the angular obstructions of the upper edge with the upper T-face were compared.
Results: The design of the angular barriers of the upper edge in the shape of the barrier caused a significant increase in the insertion loss performance, especially in the low frequency range, as compared to the upper T-shaped face. The highest amount of insertion loss in the angular barriers of the upper edge in the shaped barriers was estimated to be 3.79 dB (A) above the upper edge of T, which usually depends on the relative dimensions and position relative to the source and location of the receiver. The results of this study showed that among the tested models to determine the efficiency, the best noise barrier for controlling the traffic noise was the angular barrier with a high angle of 19 degrees compared to the other higher angles and a simple T barrier at a frequency of 315, 400, 500, and 630 Hz was obtained.
Conclusion: The performance of the barriers  in the case of applying the angle at the upper edge on the T-shaped barrier surface is improved in comparison with the use of a simple T-barrier in lower frequencies. In this regard, the best form for applying angular obstructions with a high angle was about 19 degrees from the horizon.. The cause of this effect was the presence of a failure and reflection of the angled edges in the direction of transmission of sound wave from source to receiver. All angular barrier are able to increase the barrier performance at a specific frequency range, especially at low frequencies.
 

Background and Objective: Air pollution, especially the portion related to Motor vehicles, is a serious problem in many heavily polluted areas in the world. This investigation was conducted to study the effects of the air pollution on the anatomical structure of leaf in some valuable fruit-bearing trees in Traditional Qazvin gardens.
Materials and Methods: In this study, 72 leaf samples were randomly collected from the contaminated and control areas from traditional Qazvin gardens in 2018. Three leaves of each sample were selected randomly and were submerged into the fixative solution. Then the samples were sliced using a microtome after embedding in the paraffin. Staining was carried out with hematoxylin and eosin. Measurements at cellular levels were performed by Image J. Data were analyzed by SPSS 16 software. Comparison of the means was done by Duncan's test and the charts were drown using Excel.
Results: The thickness of the lower cuticle of the main leaf's vein was significantly increased in both plants. The leaf thickness and length of palisade parenchyma in the polluted areas were increased in Juglans regia in comparison to Pistacia vera. In addition, the resin duct's diameter of the leaves of the P. vera was significantly decreased as compared with those of the control areas.
Conclusion: The results revealed some of the negative effects of air pollution on the anatomical structure of the leaves, and on several various resistance mechanisms of them. In conclusion, the metabolism of the plants can be affected by air pollution and consequently their consumers health may be at risk.