نتایج جستجو برای: ultraviolet radiation
تعداد نتایج: 268436 فیلتر نتایج به سال:
چکیده ندارد.
Polycyclic aromatic hydrocarbons (PAHs) can affect amphibians in lethal and many sublethal ways. There are many natural and anthropogenic sources of PAHs in aquatic environments. One potentially significant source is run off from surfaces of parking lots and roads that are protected with coal tar sealants. Coal tar is 50% or more PAH by wet weight and is used in emulsions to treat these surface...
Light of wave lengths 0.30micro to 0.50micro, accelerates return of the cleavage rate of Arbacia eggs to normal, after delay by exposure to ultraviolet radiation (wave lengths 0.238micro to 0.31micro). Recovery is apparently complete. Wave lengths 0.30micro to 0.50micro have no effect on the cleavage rate of normal eggs, nor does such illumination previous to dosage with ultraviolet radiation i...
Photoreactivation is the repair of ultraviolet radiation damage in a biological system with light of wavelength longer than that of the damaging radiation (Jagger1). A wide variety of ultraviolet induced effects may be reversed by photoreactiva tion, including killing, mutations, division delay, block in the DNA synthesis, etc. Such photoreactiva tion effects generally involve the photoenzyma...
A bystander effect is biological changes in non-irradiated cells by transmitted signals from irradiated bystander cells, which causes the radiation toxic effects on the adjacent non-irradiated tissues. This phenomenon occurs by agents such as ionizing radiation, ultraviolet radiation (UVR) and chemotherapy. The bystander effect includes biological processes such as damage to DNA, cell death, ch...
Introduction. Azithromycin is among the broad-spectrum antibiotics that is widely available in various environmental systems and could have destructive effects on the ecosystem and human health due to its bacterial resistance. In this study, removal of azithromycin from wastewater using an advanced oxidation process of ultraviolet light with and without persulfate was investigated and effective...
Ultraviolet radiation spectral irradiance was measured at different altitudes on horizontal and tilted planes in different azimuth directions on cloudless days in Austria, in March 2010, within the Impact of Climatic and Environmental factors on Personal Ultraviolet Radiation Exposure project framework. The presented results demonstrate variations of the UVB, UVA and biologically effective spec...
A scheme is analyzed for efficient generation of vacuum ultraviolet radiation through four-wave mixing processes assisted by the technique of Stark-chirped rapid adiabatic passage. These opportunities are associated with pulse excitation of laddertype short-wavelength two-photon atomic or molecular transitions so that relaxation processes can be neglected. In this three-laser technique, a delay...
In many vertebrate cells exposure to ultraviolet light lead to a dramatic increase in the cellular levels of the tumour suppressor protein p53, followed by a biological response of either growth arrest or programmed cell death. Ultraviolet light can be absorbed directly by cellular macromolecules, leading to photochemical modification of DNA and proteins. Additionally, it also causes free radic...
Two atmospheric responses to simulated astrophysical ionizing radiation events significant to life on Earth are production of odd-nitrogen species, especially NO2, and subsequent depletion of stratospheric ozone. Ozone depletion increases incident short-wavelength ultraviolet radiation (UVB, 280-315 nm) and longer (>600 nm) wavelengths of photosynthetically available radiation (PAR, 400-700 nm)...
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