نتایج جستجو برای: ultraviolet radiation uv a

تعداد نتایج: 13529841  

Hadi Sabri Mahak Osuli Parinaz Mehnati, Reza Malekzadeh Reza Meynagi Zadeh Zargar ta Allah Nadiri Yaser Bagheri

Introduction: Solar energy is one of the free sources, clean and environmentally friendly energy. Sun is the most important source of natural ultraviolet radiation that has a major role in the life of living beings. Industrial and medical applications of ultraviolet radiation have been clearly proven, like the production of vitamin D or treatment of many diseases, and also har...

H. Mafakheri, K. Khoshgard, M. Kanaani, M. Rezaei,

ABSTRACT Background: Ultraviolet radiation is present in sunlight. If ultraviolet radiation exceeds the limit, it can cause detrimental effects on human health such as skin cancer and cataract. Materials and Methods: In this descriptive cross-sectional study, the level of solar ultraviolet radiation type A (UVA) were measured using UV LOG HAND HELD in Kermanshah city. The intensity of ultravio...

Journal: :iranian journal of science and technology (sciences) 2005
kh. m-kalantari

the role of the antioxidant defense system was studied in brassica napus, and subjected todifferent supplementary bands of ultraviolet radiation (uv-a, uv-b and uv-c). this study showed thatuv-b and uv-c induced oxidative stress as evidenced by an increase in lipid peroxidation and totalascorbate content. under uv-b and uv-c treatments, flavonoids and anthocyanins were increasedsignificantly co...

2013
Marius Hedimbi Shyam Singh A. Kent

The laser induced fluorescence (LIF) spectra from plants give accurate information on the influences of ultraviolet A (UV-A) and ultraviolet B (UV-B) radiation on the growth of maize plants. In this paper, a thorough LIF study has been done on maize plants grown under controlled conditions. The maize (Zea mays) seeds were planted and exposed to UV-A and UV-B radiation from 0 to10 hours. The dec...

Journal: :تحقیقات نظام سلامت 0
علیرضا مصداقی نیا استاد، گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران. فروغ واعظی دانشیار، گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران. عماد دهقانی فرد گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران امیرحسین محوی استادیار، گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران. کاظم ندافی دانشیار، گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران. محمود علی محمدی استادیار، گروه مهندسی بهداشت محیط، دانشکده بهداشت، دانشگاه علوم پزشکی تهران، تهران، ایران. رضا قنبری

background: despite their simplicity and the low-cost, the conventional non-contact uv systems have low efficiency in water disinfection. the purpose of this study was to examine the possibility of upgrading these systems by some modifications in order to maximize the water contact with the uv radiation and as a result a better disinfection.    methods: in this study, two enhanced models of non...

Journal: :iranian journal of radiation research 0
f. bouzarjomehri department of medical physics, shahid sadoughi university of medical sciences, yazd, iran v. tsapaki department of medical physics, konstantopoulio hospital, nea ionia, athens, greece

background: ultraviolet (uv) radiation is divided into three regions: uva, uvb, and uvc. both the quality and quantity of solar uv radiation vary with various factors including the elevation of the sun above the horizon, as well as absorption and scattering of uv photons by molecules in the atmosphere, notably ozone and clouds. it is clear that whereas a moderate amount of uv exposure is benefi...

2012
Lee B. Kats Gary M. Bucciarelli David E. Schlais Andrew R. Blaustein Barbara A. Han

Ambient ultraviolet-B radiation can harm amphibian eggs, larvae and adults. However, some amphibians avoid UV-B radiation when given the opportunity. The strawberry poison dart frog, Oophaga pumilio, is diurnal and males vocalize throughout the day in light gaps under forest canopies that expose them to solar radiation. Previous studies have demonstrated that males calling from high perches are...

2006
Andrea P. Buccino Guillermo A. Lemarchand Pablo J. D. Mauas

Ultraviolet radiation is known to inhibit photosynthesis, induce DNA destruction and cause damage to a wide variety of proteins and lipids. In particular, UV radiation between 200-300 nm becomes energetically very damaging to most of the terrestrial biological systems. On the other hand, UV radiation is usually considered one of the most important energy source on the primitive Earth for the sy...

2012
Asta Juzeniene Johan Moan

Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanni...

2013
Yinzhao Wang Wei Lin Jinhua Li Yongxin Pan

Effects of ultraviolet radiation on microorganisms are of great interest in field of microbiology and planetary sciences. In the present study, we used Magnetospirillum magneticum AMB-1 as a model organism to examine the influence of ultraviolet-B (UV-B) radiation on cell growth and magnetite biomineralization of magnetotactic bacteria (MTB). Live AMB-1 cells were exposed to UV-B radiation for ...

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