نتایج جستجو برای: ultraviolet radiation uvr
تعداد نتایج: 268678 فیلتر نتایج به سال:
Many of the potential effects of ultraviolet radiation (UVR)—damage to materials, altered herbivory of insects and activity of microbes, modified growth of vegetation, and adverse or beneficial effects on human health—are modified by the presence of trees that influence UVR exposure to various degrees. Though tree effects on total solar irradiance have been investigated often by measurements an...
The bark extract of Pinus Maritima (PBE), a rich in phenolic acids, polyphenols and in particular flavonoids mixture, was examined for skin cancer preventive action that was evaluated in two different experimental animal tumor models induced by ultraviolet radiation (UVR) and combination of UVR with 7,12-dimethylbenz[a]anthracene. Significant decrease in the number of animals bearing tumors and...
Ultraviolet radiation (UVR)-induced mortality and behavioural disorder were studied in larval northern pike of two origins and ages. Newly hatched larvae of two differently coloured populations and six-day-old larvae of one population were exposed to four fluence rates of UVR, resulting in total doses from 11.5 to 63 kJ m–2, and monitored for mortality and behaviour. The rate of mortality and t...
Pheomelanin is widely thought to be causally related to susceptibility to the harmful effects of ultraviolet radiation: epidemiological studies show that those with a higher ratio of pheomelanin to eumelanin in hair have higher rates of melanoma, and work in mouse and cell culture shows that pheomelanin generates excess free radicals after UVR exposure. By contrast, based on measurements of eum...
Ultraviolet radiation (UVR) is a naturally occurring stressor to most forms of life. The sole relevant source of this stressor is the sun. The earth’s stratospheric ozone layer reduces the amount of UVR that reaches the earth’s surface. The potential for depletion of this ozone layer due to human activities and the subsequent increase in UVR at the earth’s surface is a global environmental conc...
Cumulative exposure to ultraviolet radiation (UVR) increases the risk of developing skin cancer, particularly squamous cell carcinoma and basal cell carcinoma. Thus, the need for protection from the sun is widely advocated, but consumers generally associate such protection with the occasional extreme exposure and tend to ignore the risk of long-term exposure. In fact, a sun exposure model predi...
[1] Field studies show that photosynthesis by Antarctic phytoplankton is inhibited by the increased ultraviolet radiation (UVR) resulting from springtime stratospheric ozone (O3) depletion. To extend previous observations, a numerical model utilizing satellitederived distributions of O3, clouds, sea ice, surface temperature, and phytoplankton biomass was developed to study the hemispheric-scale...
The combined effects of increased temperature and solar ultraviolet radiation (UVR, 280–400 nm) on M. aeruginosa cultures was analyzed in terms cell abundance, reactive oxygen nitrogen species (ROS/RNS), antioxidant activity catalase (CAT), superoxide dismutase (SOD), glutathione S transferase (GST), fatty acids (FA) content lipid damage. After 12 days exposure to high (29 °C), cells were expos...
Introduction & Objective: Biological effects of ultraviolet (UV) radiation on the body of live organisms, have been studied by researchers in recent years. UV affects human organs such as skin, eyes and immune system, as well as animals and plants. The main natural source of UV radiation is the Sun. So, the integral observation of UV levels and their effects at ground level is important to dete...
Ultraviolet radiation (UVR) has been demonstrated to be involved in a number of adverse ocular effects. One aspect of UVR-induced corneal stress only recently documented is an alteration of epithelial energy metabolite levels. In this study, in order to examine wavelength and dose dependency issues concerning metabolic effects of UVR, exposures were made at four different wavelengths (290, 300,...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید