Relative Amount Of Nitrogen Research Articles

Estimating nutrient production from human activities in subcatchments of the Red River, Manitoba

Human activities in the subcatchments of Lake Winnipeg's contributing basins are hypothesized to be an important cause of the increased nutrient loadings intensifying eutrophication processes in Lake Winnipeg, Manitoba, Canada. This study used a geographic information system (GIS) and available human activity data to describe the types and extents of nutrient producing human activities in subcatchments of the Red River Valley, Manitoba. The goal of the study was to estimate variation in the relative amount of nitrogen and phosphorus produced by human activities and thus potentially available for release to aquatic environments. Estimates of nutrient production indicated that agricultural activities, particularly through synthetic fertilizer application, were by far the largest potential source of anthropogenic nutrients to aquatic ecosystems in most subcatchments. Residential sources in these subcatchments contributed less than 1% of the total amount of nutrients produced. Assessment of spatial variation in nutrient production demonstrated that estimated nutrient production from fertilizer application in subcatchments on the west side of the Red River Valley was up to two orders of magnitude higher than that found in subcatchments on the east side. In contrast, high livestock densities in several eastern subcatchments of the Red River Valley produced more than five times the annual areal mass of nitrogen and phosphorus of most western subcatchments. Our findings demonstrate the importance of quantifying, a priori, the potential sources of nutrients to river tributaries so that future sampling sites can be stratified to include catchments where different nutrient producing activities are most extensive.

Effects of magnesium doping on growth and electric conductivity of nanocrystalline cubic boron nitride thin films

We have achieved in situ magnesium doping into nanocrystalline cubic boron nitride thin films during sputter deposition. It was clarified, through x-ray diffraction, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, that less than 1 at% magnesium doping does not significantly affect the growth of the cubic phase. Magnesium-doped films deposited in pure argon showed electric conductivity up to 104 times higher than the undoped film. Although the Hall voltage was not reproduced reliably for most of the cases, the films containing 2.1 at% magnesium clearly revealed p-type conduction with carrier concentration and mobility of 4 × 1014 cm−3 and 6 cm2 V−1 s−1, respectively, at 380 K. It was also found that the increase in electric conductivity with magnesium concentration was accompanied by the decrease in the relative amount of nitrogen in the film.

Pyrolisis-MS and FT-IR analysis of fresh and decomposed dairy manure

The ability to predict manure nitrogen mineralization is essential for optimizing crop growth while preventing N losses to the environment. However, estimating mineralizable manure N is problematic because of the wide variety of organic manure N forms, as well as the lack of a rapid standardized method. Fourier-transformed infrared spectroscopy (FT-IR) is a promising technology, since it can detect the absorbance of proteins and primary amines, in addition to being instantaneous and non-destructive. Likewise, analytical pyrolysis-mass spectrometry (Py-GC/MS) has been used to study lignin and protein composition of forages. We carried out a 10-week laboratory incubation of manure-amended soil in order to test the sensitivity of FT-IR and Py-GC/MS to detect changes in manure during decomposition in soil. Four different dairy or beef manures were included. The manures (0.15 mg manure-N g −1 soil) were placed inside mesh bags during the soil incubation to allow for the recovery and analysis of fresh as well as decomposed manure. Infrared spectroscopy of the fresh and incubated manures showed that this technique is sensitive to changes in manure organic N after soil application. Bands associated with primary amines decreased during the incubation, while bands associated with proteins increased during manure decomposition. Bands associated with fatty acids tended to decrease during the incubation, possibly due to utilization as C sources. The spectroscopic data also showed that lignin-specific signals increase during manure decomposition, suggesting that the relative amount of lignin in manure increases as it decomposes in soil. The changes in peak areas of pyrolyzates were related to changes in manure constituents during decomposition. The Py-GC/MS data showed qualitative changes in manure lignin during decomposition. The relative amounts of nitrogen containing pyrolyzates, such as phenylacetonitrile and methylindole, changed during the decomposition, but the changes were not consistent across manures. In summary, this experiment showed that the use of manure bags is valuable in discerning between the N cycling dynamics of manure and soil, and that infrared spectroscopy, as well as Py-GC/MS show potential as analytical tools to study manure decomposition in soil.

Physiological ecology and seasonality of Ulva pertusa on a temperate rocky shore

Green tides, i.e. blooms of Ulva species, occur on rocky intertidal shores over a wide geographic area in Korea. For the first time we report seasonal fluctuations in biomass, photosynthetic performance and chemical composition of the green-tide forming Ulva pertusa on the southern coast of Korea. Water temperature, salinity, inorganic nutrients and precipitation influencing Ulva mat dynamics were also monitored. There was a pronounced seasonality, not only in the biomass of U. pertusa, but also in photosynthetic performance and in variation in tissue pigments and nutrients. In addition to a primary seasonal response, significant variation in biomass was correlated in parts of the year with nutrient inputs from the surrounding watershed, heavy rain events and summer desiccation. There was a unimodal seasonal pattern in which biomass peaked in May (2.2 kg fw m−2) and dropped significantly from June to September. Recovery of Ulva mats, as indicated by recruitment of new plants, began during autumn. Photosynthetic rates, maximum photosynthesis (Pmax) and photosynthetic efficiency (α) were highest during the growth period and were lowest when biomass peaked or declined in May and July. Tissue pigments had a less clear seasonal pattern. Relative amounts of nitrogen and phosphorus bound in U. pertusa also displayed an obscure seasonal trend. Complex interactions among biological and environmental variables precluded strong correlations with any particular environmental factor. Stochastic events also played a major role in seasonality and can override normal physiological adaptations.

Changes in Nitrogen Metabolism of Vigna Radiata in Response to Elevated CO<sub>2</sub>

With the aim to determine the effects of CO2 on nitrogen metabolism mungbean (Vigna radiata) plants were grown from seedling emergence to maturity inside open top chambers under ambient CO2 (CA, 350 ± 25 µmol mol-1) and elevated CO2 (CE, 600 ± 50 µmol mol-1) concentrations at the Indian Agricultural Research Institute, New Delhi. Leaflet blades of the same physiological age were sampled at 20, 35 and 50 d after germination. Total nitrogen concentration in dry mass was consistently lower under CE than in CA. Non-protein nitrogen and protein nitrogen were also decreased under CE Total soluble protein content also decreased up to 35 d after germination under CE. However, a 27 % increase in protein content at 50 d after germination due to CE was observed. A significant decrease in total free amino acid under CE at 20 d after germination was observed. CE also brought about a remarkable decrease in the activity of nitrate reductase in leaves at 20 d after germination but increase at 35 d and 50 d after germination. Nitrogenase activity increased at all growth stages due to CE. Although total harvested leaves of CE plants accumulated more nitrogen, the relative amount of nitrogen on a percentage basis was low, probably due to a comparatively greater accumulation of sugars in the leaves of CE plants.

Inheritance Pattern and Elemental Composition of Enamel Affected by Hypomaturation Amelogenesis Imperfecta

Hypomaturation amelogenesis imperfecta (AI) is characterized clinically by enamel of normal thickness that is hypomineralized, mottled, and detaches easily from the underlying dentin. Autosomal dominant, autosomal recessive, X-linked, and sporadic modes of inheritance have been documented. The present study investigated the elemental composition of the enamel of teeth from individuals demonstrating clinical hypomaturation AI from families representing three of these patterns of inheritance. The aim of the study was to determine if there was any commonality in microscopic phenotype of this defect between families demonstrating the various inheritance patterns. One section from each tooth was microradiographed and then viewed in a scanning electron microscope (SEM) equipped with an ultrathin window energy-dispersive x-ray spectroscopy (EDX) detector. In the SEM, prisms and constituent crystals in discrete areas appeared to be largely obscured by an amorphous material. EDX analysis showed enamel outside these areas to have a composition indistinguishable from control teeth. However, within these affected areas there was a large increase in carbon content (up to a fivefold increase). In some teeth there was also detectable but smaller increase in the relative amounts of nitrogen or oxygen. The results suggest the defect in these teeth with a common clinical phenotype, irrespective of the pattern of inheritance, demonstrates a commonality in microscopic phenotype. The large increase in carbon content, not matched by an equivalent increase in nitrogen or oxygen, suggests a possible increased lipid content. In those teeth with elevated nitrogen levels there may also be retained protein.

Control of plant development by limiting factors: A nutritional perspective.

It is postulated that limiting nutritional factors play a major role in the regulation of some aspects of plant development, and can provide an alternative to mechanisms based on the concept of hormonal control. This hypothesis is consistent with experimental evidence of the role of water as a limiting factor in (1) seed maturation and viviparous germination, (2) the elongation and phototropism of hypocotyls and coleoptiles, (3) the NO3--induced germination of dormant seeds, and (4) the release of buds from correlative inhibition. Studies on the influence of nutrition on morphogenesis have shown that the relative amounts of nitrogen and carbohydrate can determine the path of bud development as a shoot or rhizome. There is also evidence that either NO3- or sugar can limit lateral root initiation, and it is postulated that they may influence this process by a combination of osmotic and nutritional effects. The close correlation between environmentally induced developmental responses and the associated changes in the water or nutritional status of the responsive tissues, together with increasing evidence of the role of water and nutrients as transmitted signals and as regulators of gene expression, are in good agreement with their postulated role as limiting factors in the regulation of plant development.

Influence of the sputtering gas composition on the properties of thin boron nitride thin films

Abstract Boron nitride thin films have been prepared in a radio frequency magnetron sputtering system using different argon–nitrogen gas mixtures and substrate bias values, being deposited on silicon, aluminium and stainless steel substrates. Optical emission spectroscopy was used to monitor the plasma. Under optimal bias, pressure and temperature conditions stoichiometric films can be obtained, their cubic phase content can be controlled by varying the relative amount of nitrogen in the plasma as well as the total flow. The effect of these parameters on intensity ratio between the emission lines for N+2 ions and boron atoms is related to the amount of the cubic phase found in the films, as determined by infrared spectroscopy. This gives support to the idea that also in sputtered films the ion to atom arrival ratio controls the amount of cubic phase. Films with up to 60 to 70% of cubic phase content can be deposited on metallic substrates using the same optimum conditions.

Photografting of Albumin onto Dimethyldichlorosilane-Coated Glass

4-Azido-2-nitrophenyl albumin (ANP-albumin) was prepared by displacing the fluoro group of 4-fluoro-3-nitrophenyl azide (FNPA) by an amino group of albumin. Photolysis of phenyl azides of ANP-albumin was studied by Fourier-transform infrared (FTIR) spectroscopy. The band of phenyl azide disappeared completely after a 12-min exposure to long wave UV light (366 nm), and the photolysis was first-order. Albumin was grafted onto dimethyldichlorosilane-coated glass (DDS-glass) by photolysis of the azido groups of ANP-albumin without any premodification of the surface. The albumin-grafted DDS-glass was characterized by determining the relative amount of nitrogen resulting from the grafted albumin on the surface using electron spectroscopy for chemical analysis (ESCA). The amount of nitrogen increased when the concentration of ANP-albumin in the adsorption solution increased up to 0.1 mg/ml. As the solution concentration increased above this value, the amount of nitrogen decreased. The platelet resistance of the albumin-grafted surfaces was evaluated by measuring the number of adherent platelets and the extent of activation that was quantitated by the area of platelets spread on the surfaces. The maximum platelet-resistant effect was observed when the ANP-albumin was adsorbed for more than 50 min at the solution concentration ranging from 0.05 to 10 mg/ml.

Microanalysis of Calcium and Phosphorus in Biology Using Electron Energy Loss Spectroscopy

Quantitative microanalysis of the important elements calcium and phosphorus in thin biological samples is normally performed using EDX spectroscopy. Sometimes, however, it is helpful to obtain additional information such as the relative amounts of nitrogen and oxygen present. EELS is sensitive to these low-Z elements and in certain cases can also improve P and Ca detection limits because of the higher EELS counting rate. Here we demonstrate the feasibility of Ca:P:Q:N ratio determinations, though we must be cautious about the N and O ratios because of mass loss.Fig. 1(a) is a STEM image of isolated dense bodies extracted from human blood platelets by sonication and then centrifuged onto a thin carbon substrate. The dense bodies which are typically 1000 Å in diameter were well separated from other constituents of the cells. Fig. 2(a) shows an EELS spectrum from a dense body about 800 Å in diameter. It was recorded at 100 keV beam energy with a Hitachi spectrometer attached to an H700H electron microscope.