Effect of ammonium concentration on alcoholic fermentation kinetics by wine yeasts for high sugar content

Kinetics of alcoholic fermentation by Saccharomyces cerevisiae wine strains in a synthetic medium with high sugar content were established for different nitrogen initial content and are presented for 4 strains. The composition of the medium was close to grape must except that the nitrogen source consisted mainly in ammonium and was varied from 120 to 290 mg N/L assimilable nitrogen. The overall nitrogen consumed was also estimated in order to determine nitrogen requirement variability. The effect of assimilable nitrogen was in general greater on sugar consumption rates than on growth and 3 kinds of effect on sugar consumption rates were observed: i) existence of an optimal initial nitrogen level for a maximal sugar consumption rate (inhibition if excess), ii) no effect of nitrogen beyond the intermediary level (saturation), iii) sugar consumption rate proportional to the initial nitrogen level (activation). In all cases, the amount of consumed nitrogen increased with its initial concentration and so did the fructophilic capacity of the strains. The optimal requirement varied from 0.62 to 0.91 mg N per g of sugars according to the different strains. There was no general correlation between the sugar assimilation rates and the nitrogen requirement

An evaluation of weld metal nitrogen retention and properties in 316NL austenitic stainless steel

A series of tests were conducted using varying levels of nitrogen and helium in a conventional argon shielding gas when welding 316LN austenitic stainless steel. The outcome was that a 15 per cent nitrogen addition to the argon shielding gas had the most significant effect on increasing the weld metal nitrogen. Subsequent additions of helium to the argon 15 per cent nitrogen shielding gas had very little overall benefit. Increasing the nitrogen content of the weld metal had the consequential effects of decreasing the ferrite content and the hardness. As a result of solid solution strengthening, the yield strength increased with increase in nitrogen content. There was an increase in impact toughness as the nitrogen content increased. This was related to the decreased ferrite content associated with the strong austenetizing potential of nitrogen. It was also shown that an almost fully austenitic weld metal could still have very good toughness. In combination with these effects there was no loss in corrosion resistance. The addition of nitrogen to a conventional argon shielding gas presents attractive cost and quality benefits over the established requirement to over alloy the weld filler material with expensive alloys such as nickel

Effect of Nitrogen Fertilizer on Milling Quality of Rice (Oryza sativa)

The effect of nitrogen fertilizer on milling quality or milling yield of rice (Oryza sativa) was tested for two cultivars, \u27Lemont\u27 and \u27Newbonnet\u27. This was an increase in the percentage of broken kernels and a decrease in head rice yield when no nitrogen fertilizer was applied as compared to applying all of the nitrogen at preflood or in split applications. The greater affect was on Lemont, a cultivar that requires a high amount of nitrogen fertilizer for maximum grain yields. Data showed that the percentage of head rice can be reduced by as much as 7 to 22 percent in Lemont and from 2 to 6 percent in Newbonnet when no nitrogen is applied as compared to applying all of the nitrogen at preflood or in split applications. Also, these data show that the percentage of broken kernels can increase from 8 to 1 9 percent for Lemont and from 4 to 11 percent for Newbonnet when no nitrogen fertilizer is applied as compared to applying all of the nitrogen at preflood or in split applications

Oxygen molecule dissociation on carbon nanostructures with different types of nitrogen doping

Energy barrier of oxygen molecule dissociation on carbon nanotube or graphene with different types of nitrogen doping is investigated using density functional theory. The results show that the energy barriers can be reduced efficiently by all types of nitrogen doping in both carbon nanotubes and graphene. Graphite-like nitrogen and Stone-Wales defect nitrogen decrease the energy barrier more efficiently than pyridine-like nitrogen, and a dissociation barrier lower than 0.2 eV can be obtained. Higher nitrogen concentration reduces the energy barrier much more efficiently for graphite-like nitrogen. These observations are closely related to partial occupation of {\pi}* orbitals and change of work functions. Our results thus provide useful insights into the oxygen reduction reactions.Comment: Accepted by Nanoscal

Functional indicators of response mechanisms to nitrogen deposition, ozone, and their interaction in two Mediterranean tree species

The effects of nitrogen (N) deposition, tropospheric ozone (O3) and their interaction were investigated in two Mediterranean tree species, Fraxinus ornus L. (deciduous) and Quercus ilex L. (evergreen), having different leaf habits and resource use strategies. An experiment was conducted under controlled condition to analyse how nitrogen deposition affects the ecophysiological and biochemical traits, and to explore how the nitrogen-induced changes influence the response to O3. For both factors we selected realistic exposures (20 kg N ha-1 yr-1 and 80 ppb h for nitrogen and O3, respectively), in order to elucidate the mechanisms implemented by the plants. Nitrogen addition resulted in higher nitrogen concentration at the leaf level in F. ornus, whereas a slight increase was detected in Q. ilex. Nitrogen enhanced the maximum rate of assimilation and ribulose 1,5-bisphosphate regeneration in both species, whereas it influenced the light harvesting complex only in the deciduous F. ornus that was also affected by O3 (reduced assimilation rate and accelerated senescence-related processes). Conversely, Q. ilex developed an avoidance mechanism to cope with O3, confirming a substantial O3 tolerance of this species. Nitrogen seemed to ameliorate the harmful effects of O3 in F. ornus: the hypothesized mechanism of action involved the production of nitrogen oxide as the first antioxidant barrier, followed by enzymatic antioxidant response. In Q. ilex, the interaction was not detected on gas exchange and photosystem functionality; however, in this species, nitrogen might stimulate an alternative antioxidant response such as the emission of volatile organic compounds. Antioxidant enzyme activity was lower in plants treated with both O3 and nitrogen even though reactive oxygen species production did not differ between the treatments

Desirable Host Plant Qualities in Wild Rice \u3ci\u3e(Zizania Palustris)\u3c/i\u3e for Infestation by the Rice Worm \u3ci\u3eApamea Apamiformis\u3c/i\u3e (Lepidoptera: Noctuidae)

The rate at which an insect infests hosts by ovipositioning and/or subsequent growth of larvae often depends on specific desirable host plant qualities. In this study, we measured the infestation rate of wild rice, Zizania palustris, by the wild rice worm, Apamea apamiformis, D. F. Hardwick (Lepidoptera: Noctuidae) and compared it to sediment nitrogen availability, plant biomass, plant density, litter accumulation, and seed carbohydrate and nitrogen concentration. Plant density and litter accumulation had no effect on infestation rates. Infestation rate increased with plant biomass and sediment nitrogen availability. The correlation between infestation rate and sediment nitrogen availability seems to reflect the fact that high nitrogen availability produces larger plants rather than more nutritious seeds as the infestation rate was not correlated with seed glucose content and surprisingly decreased with concentration of nitrogen in seeds. Infestation rate was not related to any other measured quantities. Therefore, Apamea appear to infest larger, rapidly growing host plants which are made possible by high sediment nitrogen availability

Fertilization: trade-offs between manure abatement and plant productivity

In 2005, 30% of the Flemish farms faced a manure excess, while at aggregated level still 9.7% of the emission rights were unused. This means that, despite the various possibilities, Flemish farmers do not succeed in an effective exchange of manure between farms. In current paper is shown how inorganic fertilizer use influences the use and exchange of organic nitrogen. Because of the mutual interdependency between organic and inorganic nitrogen emission rights (or quota), inorganic nitrogen use limits the emission rights for organic nitrogen. Utilisation of these emission rights are analysed as a trade-offs choice between plant productivity (use of inorganic nitrogen) and manure disposal, as the major abatement alternative of manure production. Farmers still prefer inorganic fertilizers because of their effect on plant productivity and income. However, by changing the quota rent of organic nitrogen, the fertilization behaviour can be influenced. A higher quota rent of organic nitrogen would increase the use of manure. This trade-off behaviour seriously influences effectiveness of policies. When the objective is to lower the total nitrogen use, a mere reduction of organic quota can partially be counteracted by a higher inorganic nitrogen use. When the objective is to better spread the manure, increasing the quota rent for deficit farms will increase their acceptance of manure

Nitrogen removal in maturation WSP ponds via biological uptake and sedimentation of dead biomass

In this work a set of experiments was undertaken in a pilot-scale WSP system to determine the importance of organic nitrogen sedimentation on ammonium and total nitrogen removals in maturation ponds and its seasonal variation under British weather conditions. Two maturation ponds in series (M1 and M2) were monitored seasonally from September 2004 to May 2007. The nitrogen content in collected sediment samples varied from 4.17 to 6.78 percent (dry weight) and calculated nitrogen sedimentation rates ranged from 291 to 2,868 g N/ha d in M1 and from 273 to 2,077 g N/ha d in M2. The increment of chlorophyll-a in M1 and M2 maturation pond effluents had a very good correlation with the corresponding increment of VSS (algal biomass) and suspended organic nitrogen; therefore, the occurrence of biological (algal) nitrogen uptake was confirmed. After sedimentation of the dead algal biomass, it was clear that algal-cell nitrogen was recycled from the sludge layer into the pond water column. An important portion (51% in M1 and 39% in M2) of the nitrogen taken up by the in-pond algae was finally accumulated as sludge after anaerobic digestion. Biological (mainly algal) uptake of inorganic nitrogen species and further sedimentation of dead biomass is one of the major mechanisms controlling ammonium and nitrogen removal in maturation WSP, particularly when environmental and operational conditions are favourable for algal growth

Denitrification by rhizobia: A possible factor contributing to nitrogen losses from soils

The intensive pastoral farming system on which New Zealand animal production is based is almost completely dependent upon the rhizobium-legurne symbiosis for the fixed nitrogen required for pasture production. The average annual fixation has been measured as 184 kg nitrogen/ha in developed lowland pastures Hoglund et cii., 1979 and about 13 kg nitrogen/ha in poorly developed bill country pastures (Grant and Lambert, 1979). From these figures it can be estimated that rhizobia in New Zealand pastures fix in excess of one million tonnes of nitrogen an nually. The current annual application of fertilizer nitrogen to pastures is about 12 500 tonnes (O'Connor, 1979)