Search results for "Nitrogen"
showing 10 items of 1200 documents
Surface passivation of gallium selenide by nitrogen implantation
2002
In this paper we report on the characterization of nitrogen-implanted single-crystal GaSe samples. Nitrogen atoms were implanted at 80 keV, with doses ranging from 4 × 10 13 to 10 15 N + ions cm -2 . Next, samples were aged in open air and characterized by small-area XPS, together with an unimplanted clean surface, in order to quantify the effects of the nitrogen implantation. In general, we found that the oxidation was fully prevented in N + -implanted samples.
ENVIRONMENTAL EFFECTS ON FRACTIONAL EXHALED NITRIC OXIDE IN ALLERGIC CHILDREN
2011
Fractional exhaled nitric oxide (FeNO) is a non-invasive marker of airway inflammation in asthma and respiratory allergy. Environmental factors, especially indoor and outdoor air quality, may play an important role in triggering acute exacerbations of respiratory symptoms. The authors have reviewed the literature reporting effects of outdoor and indoor pollutants on FeNO in children. Although the findings are not consistent, urban and industrial pollution—mainly particles (PM2.5 and PM10), nitrogen dioxide (NO2), and sulfur dioxide (SO2)—as well as formaldehyde and electric baseboard heating have been shown to increase FeNO, whilst ozone (O3) tends to decrease it. Among children exposed to …
Effect of different cryosurgical protocols using liquid nitrogen on bone tissue: a histomorphological analyze
2011
The aim of the present experimental study was to evaluate the morphological effects of different liquid nitrogen cryosurgery protocols on bone tissue. The femoral diaphyses of 42 Wistar rats were exposed to three local and sequential applications of liquid nitrogen for 1 or 2 min, intercalated with periods of 5 min of passive thawing. The animals were sacrificed after 1, 2, 4 and 12 weeks and the specimens obtained were processed and analyzed histomorphologically. Histologically, an increase in bone necrosis was observed for the two protocols in the second week after cryotherapy. A significant osteogenic phase was observed after 4 weeks. Moreover, complete remodeling process was encountered…
DNA strand breaks induced by nuclear hijacking of neuronal NOS as an anti-cancer effect of 2-methoxyestradiol
2015
2-Methoxyestradiol (2-ME) is a physiological metabolite of 17β-estradiol. At pharmacological concentrations, 2-ME inhibits colon, breast and lung cancer in tumor models. Here we investigated the effect of physiologically relevant concentrations of 2-ME in osteosarcoma cell model. We demonstrated that 2-ME increased nuclear localization of neuronal nitric oxide synthase, resulting in nitro-oxidative DNA damage. This in turn caused cell cycle arrest and apoptosis in osteosarcoma cells. We suggest that 2-ME is a naturally occurring hormone with potential anti-cancer properties.
Stable carbon isotopic composition of peat columns, subsoil and vegetation on natural and forestry-drained boreal peatlands.
2018
We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ13C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ13C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ13C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ13C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the…
Methanotrophy induces nitrogen fixation during peatland development
2013
Significance In peatlands, the external sources of nitrogen are mainly atmospheric, but the atmospheric nitrogen deposition alone cannot explain the long-term annual nitrogen accumulation rates to these ecosystems. Because of methodological problems, methane-induced fixation of atmospheric dinitrogen gas has been previously overlooked as an additional nitrogen input mechanism. We found that the activity of methane-oxidizing bacteria provides not only carbon but also nitrogen to peat mosses and, thus, contributes to carbon and nitrogen accumulation in peatlands, which store approximately one-third of the global soil carbon pool. Our results imply that nitrogen fixation in wetlands may be str…
Outdoor, but not indoor, nitrogen dioxide exposure is associated with persistent cough during the first year of life
2011
Background and aims: Because their lungs and immune system are not completely developed, children are more susceptible to respiratory disease and more vulnerable to ambient pollution. We assessed the relation between prenatal and postnatal nitrogen dioxide (NO2) levels and the development of lower respiratory tract infections (LRTI), wheezing and persistent cough during the first year of life. Methods: The study population consisted of 352 children from a birth cohort in Valencia, Spain. Prenatal exposure to NO2, a marker of traffic related air pollution was measured at 93 sampling sites spread over the study area during four different sampling periods of 7 days each. It was modeled for eac…
Air Pollution Exposure During Pregnancy and Symptoms of Attention Deficit and Hyperactivity Disorder in Children in Europe
2018
Background: Exposure to air pollution during pregnancy may increase attention-deficit/hyperactivity disorder (ADHD) symptoms in children, but findings have been inconsistent. We aimed to study this association in a collaborative study of eight European population-based birth/child cohorts, including 29,127 mother-child pairs. Methods: Air pollution concentrations (nitrogen dioxide [NO2] and particulate matter [PM]) were estimated at the birth address by land-use regression models based on monitoring campaigns performed between 2008 and 2011. We extrapolated concentrations back in time to exact pregnancy periods. Teachers or parents assessed ADHD symptoms at 3-10 years of age. We classified …
Prenatal exposure to traffic-related air pollution and fetal growth in a cohort of pregnant women
2012
Objectives Scant evidence is available on effects of air pollution on longitudinally measured fetal biometry, and thus it remains unclear as to whether there are critical windows of exposure or specificity of effects. Our objective was to examine the association between exposure to nitrogen dioxide (NO2) during pregnancy and fetal and neonatal anthropometry in a cohort of Spanish women. Methods Temporally adjusted land-use regression was used to estimate exposure to NO2 at home addresses. Biparietal diameter (BPD), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW) were evaluated in each trimester by ultrasound. As neonatal outcomes, weight, length and head cir…
Changes in fish mercury concentrations over 20 years in an acidified lake subject to experimental liming
2007
Abstract Lake Iso Valkjarvi (southern Finland, Europe) was divided in two with a plastic curtain in 1991. One half was neutralized with CaCO 3 , and the other acted as a control. Mercury concentrations of perch ( Perca fluviatilis ) and northern pike ( Esox lucius ) in the limed and control side of the lake were studied both before and after the treatment. Average Hg concentrations of perch and pike were 0.40 and 1.2 μg g −1 (ww) in the early 1980s and 0.25 and 0.72 μg g −1 (ww) a decade later at the time of liming. Ten years after the liming the Hg concentrations of perch in the limed and control sides of the lake were 0.21 and 0.28 μg g −1 (ww) and those of pike were 0.69 and 0.43 μg g −1…