نتایج جستجو برای: light exposure
تعداد نتایج: 689681 فیلتر نتایج به سال:
Introduction: Rapid population growth and industrialization have increased chemical pollutants. Some studies show that employee exposure to formaldehyde in industrial places, hospitals, and laboratory settings is more than the allowed limits. Therefore, it is necessary to implement a proper control system to reduce this exposure. This study aimed to synthesize Ag3PO4/TiO2 nanocomposite, determi...
One of the problems of natural yellow dyes (weld) is their low stability against light and their high fading rate. One of the main destructive factors in pale of color fibers and hand-woven carpet is the high-energy ultraviolet radiation which causes chemical bonds to break and optically damages of organic structures. In this study, the effect of some antioxidants (gallic acid, ascorbic acid) a...
Background and aims: Compact fluorescent lamps(CFLs) are low-pressure mercury vapor lamps, which are more useful than other light sources. Some studies reported the leakage of UV radiation from CFLs. The aim of this study was measuring of ultraviolet radiation from universal compact fluorescent lamps in Iran. Methods: In this study, measuring of UV radiation of 54 bulb compact fluorescent lamps...
this study investigated the potential role of age in inductive and deductive grammar learning among iranian foreign language learners. the experimental population consisted of our randomly selected samples including two groups of children (with age of exposure to english within 8-13), and two groups of adults (with age of exposure to english within 11-13). thus, the comparison was between ch...
background: noise is one of the annoying agents in the environment and it is harmful agent in workplaces that its occurrence with work load, there are in many workstations. the aim of this study was to determine the combined effects of exposure to noise and work load on heart rate changes. methods: this cross-sectional study performed on 14 male students into climatic chamber in 2011.the mean ±...
Introduction: Noise and light can affect on body posture during the study. With regard to the importance of the mentioned factors and their effect on body posture, measurement and assessment of these parameters seems essential in the study rooms. This study aimed to measure and assess these factors and their relationship with students' postural status. Methods: In this cross-sectional (descrip...
introduction: the aim of this study was to in-vestigate the effect of irradiation duration and distance of light tip to prepared samples in two different light curing unites on the degree of conversion of resin composite. materials and methods: conventional halogen and blue light emitting diode (led) units were used for polymerization of an opalis resin com-posite. the conversion measurements w...
Computers and laptops are increasingly used at work and at home. As a consequence, the exposure of short wavelength blue light, which is emitted by LED displays, increases too. By its action, light is well-known to enact damage on the neurosensory retina, especially on the underlying structures. In particular, this happens through photothermal, photomechanical, and photochemical mechanisms. Thi...
Operators of construction vehicles are constantly exposed to whole body vibration, which can lead to musculoskeletal disorders. The aim of present study was to evaluate the impact of exposure to whole body vibration in operators and its relation to musculoskeletal disorders. This study is a descriptive-analytical study. Using easy sampling, 89 operators from 6 types of heavy vehicles (Bulldoze...
introduction: application of light transmitting posts to restore greatly damaged endodontically treated teeth has been increased. it is suspected that light intensity decreases as it passes throughout different materials. this can reduce the degree of conversion required for adequate bond strength throughout the length of these posts. the objective of this study was to evaluate the amount of li...
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