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Nitrogen Content (nitrogen + content)
Kinds of Nitrogen Content Selected AbstractsLeaves of Lianas and Self-Supporting Plants Differ in Mass per Unit Area and in Nitrogen ContentPLANT BIOLOGY, Issue 3 2000M. Kazda Abstract: The aim of this study was to test the hypothesis that the reduction in supporting tissues in climbers compared to self-supporting plants is also true for their leaves, and that climbers generally require higher leaf nitrogen than self-supporting plants to accomplish fast growth. This hypothesis was tested using paired samples of both growth forms with assessment of leaf area index above the sampled plants (LAIa) in a tropical rain forest in Gabon. The sampling protocol ensured that within a highly fluctuating low canopy environment, the growth conditions were identical for each pair sampled. The results confirmed the hypothesis. Lianas had significantly lower leaf mass per unit leaf area (LMA) than their supporters. Liana leaves also contained significantly more nitrogen than host tree leaves. The differences in nitrogen concentration between liana and tree leaves reversed for the most shaded sites, when nitrogen was expressed on a leaf area base (Narea). Significant regression between leaf nitrogen and LAIa was found for the climbers on the shaded sites but not for their supporters. This indicated better acclimation of climbers to prevailing light conditions. Better nitrogen allocation at low LMA, together with lower carbon costs for building supporting tissues, makes lianas highly competitive, especially where high nitrogen availability is assured. [source] Highly Ordered Mesoporous Carbon Nitride Nanoparticles with High Nitrogen Content: A Metal-Free Basic Catalyst,ANGEWANDTE CHEMIE, Issue 42 2009Xin Jin Stickstoffreiches Kohlenstoffnitrid wurde durch die Reaktion von Ethylendiamin mit CCl4 in den Nanokanälen eines mesoporösen Silica-Templats in Form ultrakleiner, diskreter, mesoporöser Nanopartikel erhalten (siehe SEM-Aufnahme). Die Nanopartikel sind hoch aktive Katalysatoren für die Umesterung von ,-Ketoestern arylischer, aliphatischer und cyclischer primärer Alkohole. Die hohe Aktivität ist dem hohen Stickstoffgehalt, der großen Oberfläche und dem großen Porenvolumen zu verdanken. [source] Estimation of kinetic and mass-transfer parameters for cellulose nitrationAICHE JOURNAL, Issue 10 2006I. V. M. Barbosa Abstract When nitrocellulose is used in the production of gun powders and rocket/missile propellants, rigid control of the cellulose nitration reaction is necessary. Nitrogen content is, by far, the most important parameter to be controlled and only off-line measurements can be performed for that. Although cellulose is a natural polymer whose characteristics may vary, the final product must have its nonuniformities compensated by blending of different batches. In this work, kinetic and mass-transfer parameters are nonlinearly fitted using typical nitration experiments. The required mathematical modeling is carried out using a continuous mixtures approach, which depends only on structural descriptions of the cellulose. The model leads to an algebraic-integro-differential population balance system of equations, solved with an approximant built with block-pulse functions. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Quantification of monomeric and polymeric wheat proteins and the relationship of protein fractions to wheat quality,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2003Jerry Suchy Abstract Wheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross-contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan-1-ol and 0.3 M sodium iodide (monomeric-rich protein), 50% propan-1-ol (soluble glutenin-rich protein) and 40% propan-1-ol and 0.2% dithiothreitol (insoluble glutenin-rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross-contamination of protein fractions was evaluated by SDS-PAGE, SE-HPLC and RP-HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric-rich protein (<2%) and insoluble glutenin-rich protein (<4%). Three wheats with similar high-molecular-weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P , 0.05) in the proportion of monomeric-rich and insoluble glutenin-rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin-rich protein and inversely related to the proportion of monomeric-rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter-cultivar differences in the proportion of monomeric-rich, insoluble glutenin-rich protein and glutenin-to-gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat-breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri-Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd. [source] Saccharomyces cerevisiae biodiversity in spontaneous commercial fermentations of grape musts with ,adequate' and ,inadequate' assimilable-nitrogen contentLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2003L. Granchi Abstract Aim: To evaluate whether intraspecific diversity of Saccharomyces cerevisiae in wine fermentations is affected by initial assimilable-nitrogen content. Methods and Results:Saccharomyces cerevisiae isolates from two spontaneous commercial wine fermentations started with adequate and inadequate nitrogen amounts were characterized by mitochondrial DNA restriction analysis. Several strains occurred in each fermentation, two strains, but not the same ones, being predominant at frequencies of about 30%. No significant differences were detected by comparing the biodiversity indices of the two fermentations. Cluster analysis demonstrated that the strain distribution was independent of nitrogen content, the two pairs of closely related dominant strains grouping into clusters at low similarity. Conclusions: The genetic variability of S. cerevisiae in wine fermentations seemed not to depend on the nitrogen availabilty in musts. Significance and Impact of the Study: Nitrogen content did not affect the genetic diversity but may have induced a ,selection effect' on S. cerevisiae strains dominating wine fermentations, with possible consequences on wine properties. [source] Lack of Interaction between Extreme High-Temperature Events at Vegetative and Reproductive Growth Stages in WheatJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2003B. Wollenweber Abstract Increased climatic variability and more frequent episodes of extreme conditions may result in crops being exposed to more than one extreme temperature event in a single growing season and could decrease crop yields to the same extent as changes in mean temperature. The developmental stage of the crop exposed to increased temperatures will determine the severity of possible damage experienced by the plant. It is not known whether or not the damaging effects of heat episodes occurring at different phenological stages are additive. In the present study, the interaction of high-temperature events applied at the stages of double ridges and anthesis in Triticum aestivum (L.) cv. Chablis was investigated. Biomass accumulation of control plants and that of plants experiencing high temperatures during the double-ridge stage were similar and were reduced by 40 % when plants were subjected to a heat event at anthesis. Grain number on the main and side tillers declined by 41 %, and individual grain weight declined by 45 % with heat stress applied at the double-ridge stage and anthesis or at anthesis alone. The harvest index was reduced from 0.53 to 0.33. Nitrogen contents in leaves were reduced by 10 % at the double-ridge stage and by 25 % at anthesis. The maximum rates of CO2 assimilation increased with heat stress at the double-ridge stage and higher rates were maintained throughout the growing season. The results clearly indicate that an extreme heat event at the double-ridge stage does not affect subsequent growth or the response of wheat to heat stress at anthesis. [source] Host plant variation in plant-mediated indirect effects: moth boring-induced susceptibility of willows to a specialist leaf beetleECOLOGICAL ENTOMOLOGY, Issue 2 2008SHUNSUKE UTSUMI Abstract 1.,We examined the plant-mediated indirect effects of the stem-boring moth Endoclita excrescens (Lepidoptera: Hepialidae) on the leaf beetle Plagiodera versicolora (Coleoptera: Chrysomelidae) in three willow species, Salix gilgiana, S. eriocarpa, and S. serissaefolia. 2.,When the stem-boring moth larvae damaged stems in the previous year, willows were stimulated to produce vigorously growing lateral shoots on these stems. These new lateral shoots were significantly longer and the upper leaves had significantly higher nitrogen and water content than current-year shoots on unbored stems, although the carbon content and leaf dry mass were not different between lateral and current-year shoots. 3.,In the field, leaf beetle larvae and adults had significantly greater densities on lateral shoots of bored stems than on current-year shoots of unbored stems. A laboratory experiment showed that female beetles had significantly greater mass and fecundity when fed on leaves of newly-emerged lateral shoots. Thus, the stem-boring moth had a positive effect on the temporally and spatially separated leaf beetle by increasing resource availability by inducing compensatory regrowth. 4.,The strength of the indirect effects on the density and performance of the leaf beetle differed among willow species, because there was interspecific variation in host quality and herbivore-induced changes in plant traits. In particular, we suggest that the differences in magnitude of the changes among willow species in shoot length and leaf nitrogen content greatly affected the strength of the plant-regrowth mediated indirect effect, coupled with host-plant preference of the leaf beetle. [source] Separating host-tree and environmental determinants of honeydew production by Ultracoelostoma scale insects in a Nothofagus forestECOLOGICAL ENTOMOLOGY, Issue 4 2007ROGER J. DUNGAN Abstract 1.,Sugar-rich honeydew excreted (,produced') by insects feeding on phloem sap is a key energy flow in a range of temperate and tropical ecosystems. The present study measured honeydew produced by Ultracoelostoma sp. (Homoptera: Coelostomidiidae) scale insects feeding on Nothofagus solandri var. solandri (Hook f.) Oerst. trees in a temperate evergreen forest in New Zealand. Simultaneous measurements of environmental variables and canopy photosynthesis were conducted to allow separation of host-tree and environmental determinants of honeydew production. These relationships were further examined in experiments where canopy photosynthesis was manipulated by shading or plant nitrogen levels increased by foliar spray. 2.,Rates of honeydew production varied nine-fold from a maximum (± 1 SE) of 64.4 ± 15.2 mg dry mass m,2 bark h,1 in early summer (December) to a minimum of 7.4 ± 4.2 mg m,2 h,1 in winter (August). Rates of production measured 1.4 m from the base of the trees' stems varied significantly with stem diameter, and were higher on medium-sized (18 cm diameter) than small or large stems. 3.,Rates of production were significantly related to environmental conditions over the hours preceding measurement (air temperature and air saturation deficit averaged over the preceding 24 and 12 h respectively). There was no evidence that rates of production were directly related to short-term changes in the supply of carbohydrates from the canopy (either when compared with measurements of unmanipulated photosynthetic rate, or after sugar levels were manipulated by shading 80% of host-trees' leaf area), or to changes in phloem nitrogen content. 4.,The results show that there is no clear effect of host-tree carbon supply on honeydew production; if production is related to photosynthesis, the effect of this is much less important that the large and significant direct effect of environmental conditions on honeydew production. [source] The Dry Limit of Microbial Life in the Atacama Desert Revealed by Calorimetric ApproachesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008N. Barros Abstract The Atacama desert in Chile is one of the driest and most lifeless environments on Earth. It rains possibly once a decade. NASA examined these soils as a model for the Martian environment by comparing their degradation activity with Martian soil and looking for "the dry limit of life". The existence of heterotrophic bacteria in Atacama soil was demonstrated by DNA extraction and by the isolation of microorganisms. So far, however, no data have been available about the metabolic activities in these soils due to the limitations of the existing methodologies when applied to desert soils. Calorimetry was used to obtain information on the metabolic and thermal properties of eleven soil samples collected at different sites in the Atacama desert. Differential scanning calorimetry and isothermal calorimetry were employed to determine the pyrolysis properties of the carbon-containing matter and to measure biomass and microbial metabolism. They were compared to other soil properties such as total carbon and nitrogen, carbon to nitrogen ratio and pH. There was measurable organic matter in nine of the eleven samples and the heat of pyrolysis of those soils was correlated to the carbon content. In five of the eleven samples no biomass could be detected and the existence of basal microbial metabolism could not be established because all samples showed endothermic activity, probably from inorganic reactions with water. Six samples showed microbial activation after the addition of glucose. Carbon content, nitrogen content and the microbial activity after glucose amendment were correlated to the altitude and to the average minimum temperature of the sampling sites calculated from meteorological data. The detectable microbial metabolism was more dissipative with increasing altitude and decreasing temperature. [source] Palatability of macrophytes to the invasive freshwater snail Pomacea canaliculata: differential effects of multiple plant traitsFRESHWATER BIOLOGY, Issue 10 2010PAK KI WONG Summary 1.,By selective grazing, invasive grazers can alter macrophyte-herbivore relationships in shallow freshwater bodies. Evaluating the palatability of macrophytes and understanding the determinants of plant palatability can help predict grazing impact. In no-choice feeding assays, we tested the palatability of 21 species of freshwater macrophytes to the invasive freshwater apple snail Pomacea canaliculata. 2.,Daily feeding rate varied greatly with plant species, ranging from 1.1 to 22% of snail body mass. We assessed six plant properties and examined their correlation with feeding rate. Total nitrogen content was positively related, and C:N ratio and dry matter content (DMC) negatively related, to snail feeding rate. There was no significant correlation between snail feeding rate and plant phenolic content, but the feeding rate on Myriophyllum aquaticum (the plant with the highest phenolic content) was very low. 3.,We repeated the feeding assays for 15 species that were not palatable as fresh leaves with reconstituted plant tissues formed by mixing ground up dried leaves with agar. The feeding rate still differed greatly among macrophyte species. Phragmites australis and Vallisneria natans (two species with the highest DMC) were eaten much more as reconstituted plant than as fresh leaves, indicating that structure (i.e. DMC) may be important in their defence against snail herbivory. For two plants (M. aquaticum and Alternanthera philoxeroides) that had moderate amounts of nitrogen/phosphorus but were consumed very little as fresh and reconstituted tissues, we incorporated their extracts into a palatable agar-based food. The extracts from both species greatly reduced snail feeding rate, indicating the presence of chemical defences in these two species. 4.,These results indicated that feeding was affected by several plant traits. The snail favoured plants with a high nitrogen content and avoided plants with a high DMC. Only a few plants possessed chemical feeding deterrents that were effective against this snail. Given the invasive spread of P. canaliculata in Asia, ecologists and managers should consider plant palatability when selecting plants for use in wetland restoration and when predicting the impact of further invasion by this species. [source] Effects of drying regime on microbial colonization and shredder preference in seasonal woodland wetlandsFRESHWATER BIOLOGY, Issue 3 2008MARTYN D. INKLEY Summary 1. Energy budgets of wetlands in temperate deciduous forests are dominated by terrestrially derived leaf litter that decays under different drying conditions depending on autumn precipitation. We compared decay rates and microbial colonization of maple leaves under different inundation schedules in a field experiment, and then conducted a laboratory study on shredder preference. In the field, litter bags either remained submerged (permanent), were moved to a dried part of the basin once and then returned (semi-permanent), or were alternated between wet and dry conditions for 8 weeks (temporary). 2. There was no difference in decay rates among treatments, but leaves incubated under permanent and semi-permanent conditions had higher fungal and bacterial biomass, and lower C : N ratios than those incubated under alternating drying and wetting conditions. 3. To determine the effects of these differences in litter nutritional quality on shredder preference, we conducted a laboratory preference test with larvae of leaf-shredding caddisflies that inhabit the wetland. Caddisflies spent twice as much time foraging on permanent and semi-permanent litter than on litter incubated under temporary conditions. 4. There is considerable variation among previous studies in how basin drying affects litter breakdown in wetlands, and no previous information on shredder preference. We found that frequent drying in a shallow wetland reduces the nutritional quality of leaf litter (lower microbial biomass and nitrogen content), and therefore preference by invertebrate shredders. These results suggest that inter-annual shifts in drying regime should alter detritus processing rates, and hence the mobilization of the energy and nutrients in leaf litter to the wetland food web. [source] Breakdown of wood in the Agüera streamFRESHWATER BIOLOGY, Issue 11 2002Joserra Díez SUMMARY 1. Breakdown of wood was compared at three sites of the Agüera catchment (Iberian Peninsula): two oligotrophic first-order reaches (one under deciduous forest, the other under Eucalyptus globulus plantations) and one third-order reach under mixed forest, where concentration of dissolved nutrients was higher. 2. Branches (diameter = 3 cm, length = 10 cm) of oak (Quercus robur), alder (Alnus glutinosa), pine (Pinus radiata) and eucalyptus, plus prisms (2.5 × 2.5 × 10 cm) of alder heartwood were enclosed in mesh bags (1 cm mesh size) and placed in the streams. Mass loss was determined over 4.5 years, whereas nutrient, lignin and ergosterol were determined over 3 years. In order to describe fungal dynamics, ergosterol was also determined separately on the outer and inner parts of some branches. 3. Breakdown rates ranged from 0.0159 to 0.2706 year,1 with the third-order reach having the highest values whatever the species considered. The most rapid breakdown occurred in alder heartwood and the slowest in pine branches; breakdown rates of oak, eucalyptus and alder branches did not differ significantly. 4. The highest nitrogen and phosphorus contents were found in alder, followed by oak, while pine and eucalyptus had low values. During breakdown, all materials rapidly lost phosphorus, but nitrogen content remained constant or slightly increased. Lignin content remained similar. 5. Peaks of ergosterol ranged from 0.023 to 0.139 mg g,1 and were higher in alder than in other species in two of the three sites. The third-order reach generally had the greatest increase in ergosterol, especially in alder branches, eucalyptus and alder heartwood. The overall species/site pattern of fungal biomass was thus consistent with the observed differences in breakdown. 6. When compared with leaves of the same species decomposing at these sites, wood breakdown appeared to be less sensitive to the tree species but more sensitive to stream water chemistry. Although wood breakdown is slower and its inputs are lower than those of leaf litter, its higher resistance to downstream transport results in a relatively high standing stock and a significant contribution to the energy flux. [source] Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvaeFUNCTIONAL ECOLOGY, Issue 4 2010Carita Lindstedt Summary 1.,Aposematic animals advertise their defences to predators via warning signals that often are bright colours combined with black patterns. Predation is assumed to select for large pattern elements and conspicuousness of warning signals because this enhances avoidance learning of predators. However, conspicuousness of the colour pattern can vary among individuals of aposematic species, suggesting that warning signal expression may be constrained by opposing selection pressures. If effective warning signals are costly to produce, variation in signal expression may be maintained via physiological trade-offs. To understand the costs of signalling that might underlay both physiological and ecological trade-offs, it is crucial to identify the pigments involved in aposematic traits, how they or their precursors are acquired and how their production and/or deposition interact with other physiological processes. 2.,We characterized the pigments responsible for the genetically and phenotypically variable orange-black warning signal of the hairy larvae of an Arctiid moth, Parasemia plantaginis. We tested orange and black coloured hairs for the presence of six candidate pigment types using high-performance liquid chromatography, spectral and solubility analyses. 3.,After excluding the presence of carotenoids, ommochromes, pterins and pheomelanins in orange hairs, our results suggest that tiger moth larvae produce their orange warning signal by depositing both diet-derived flavonoids and trace levels of synthesized eumelanin in their hairs. The nearby black hairs are coloured by eumelanin. 4.,In light of previous studies, we conclude that although a large orange patch increases the 1larvae's antipredator efficacy, variation in the size of orange patches within a population can be driven by scarcity of flavonoids in diet. However, traces of eumelanin found in the orange hairs of the larvae may also play a significant role in the maintenance of the signal pattern on poor quality diets. 5.,The goal of the future studies will be to test the condition dependence of pigment deposition in aposematic colour patterns by directly manipulating relevant nutritional parameters such as dietary flavonoid or nitrogen content (i.e. amino acid content). [source] Alkaloids may not be responsible for endophyte-associated reductions in tall fescue decomposition ratesFUNCTIONAL ECOLOGY, Issue 2 2010Jacob A. Siegrist Summary 1. ,Fungal endophyte , grass symbioses can have dramatic ecological effects, altering individual plant physiology, plant and animal community structure and function, and ecosystem processes such as litter decomposition and nutrient cycling. 2. ,Within the tall fescue (Schedonorus arundinaceus) , fungal endophyte (Neotyphodium coenophialum) symbiosis, fungal produced alkaloids are often invoked as the putative mechanism driving these ecological responses. Yet few measurements of alkaloids exist in the ecological literature. In this study, we quantified alkaloid levels in live, standing dead and decomposing endophyte-infected (E+) and ,free (E,) plant material and simultaneously evaluated the direct and indirect effects of endophyte presence on tall fescue decomposition. 3. ,Loline and ergot alkaloid levels were consistently high in live E+ (common toxic strain of N. coenophialum) tall fescue biomass throughout the sampling period (May,November 2007), whereas, E, live and standing dead material had non-detectable alkaloid concentrations. Standing dead E+ biomass had significantly reduced alkaloid levels (6,19x lower than the levels measured in the corresponding live E+ biomass) that were equivalent to E, live and dead for loline but were still somewhat higher than E, material for ergots. 4. ,In an effort to test the role of alkaloids in directly inhibiting decomposition, as has been suggested by previous studies, we conducted a litter bag experiment using green, alkaloid-laden E+ and alkaloid-free E, tall fescue plant material. We incubated E+ and E, litter bags in both E+ and E, tall fescue stands for 170 days, and measured mass loss, carbon and nitrogen content, and ergot and loline alkaloid concentrations over the incubation period. 5. ,Consistent with previous reports, both direct and indirect effects of endophyte presence on litter decomposition were observed: endophyte presence in the litter and surrounding microenvironment significantly reduced decomposition rates. Surprisingly, despite large differences in alkaloid content between E+ and E, litter from Day 0,Day 21 of the incubation, direct effects of the endophyte on litter decomposition, while significant, were relatively small (differences in mass loss between E+ and E, litter were never >3%). Alkaloids were gone from E+ material by day 56. 6. ,We propose that results from this study indicating alkaloids are largely absent in standing dead material (the typical input to the decomposition process), and that despite being present in our litter bag experiment, failed to produce large differences in mass loss between E+ and E, material questions the supposition that fungal produced alkaloids directly inhibit decomposition. Additional studies exploring the mechanisms behind the direct and indirect effects of endophytes on this ecosystem process are needed. [source] Carbon dioxide assimilation by a wetland sedge canopy exposed to ambient and elevated CO2: measurements and model analysisFUNCTIONAL ECOLOGY, Issue 2 2003D. P. Rasse Summary 1The wetland sedge Scirpus olneyi Gray displays fast rates of CO2 assimilation and responds positively to increased atmospheric CO2 concentration. The present study was aimed at identifying the ecophysiological traits specific to S. olneyi that drive these CO2 -assimilation patterns under ambient and elevated CO2 conditions. 2The net ecosystem exchange (NEE) of CO2 between S. olneyi communities and the atmosphere was measured in open-top chambers. 3We developed a new mechanistic model for S. olneyi communities based on published ecophysiological data and additional measurements of photosynthetic parameters. 4Our NEE measurements confirmed that S. olneyi communities have a high rate of summertime CO2 assimilation, with noontime peaks reaching 40 µmol CO2 m,2 ground s,1 on productive summer days, and that elevated CO2 increased S. olneyi CO2 assimilation by c. 35,40%. 5Using S. olneyi -specific ecophysiological parameters, comparison with measured NEE showed that the model accurately simulated these high rates of CO2 uptake under ambient or elevated CO2. 6The model pointed to the Rubisco capacity of Scirpus leaves associated with their high total nitrogen content as the primary explanation for the high rates of CO2 assimilation, and indicated that the vertical-leaf canopy structure of S. olneyi had comparatively little influence on CO2 assimilation. [source] Leaf dark respiration as a function of canopy position in Nothofagus fusca trees grown at ambient and elevated CO2 partial pressures for 5 yearsFUNCTIONAL ECOLOGY, Issue 4 2001K. L. Griffin Summary 1,Mass-based and area-based rates of respiration, leaf nitrogen content, leaf total protein content, non-structural carbohydrates and leaf mass per unit area (LMA) all decreased with depth in the canopy of Nothofagus fusca (Hook. F.) Oerst. (Red beech) trees grown for 5 years at ambient (36 Pa) or elevated (66 Pa) CO2 partial pressures. 2Elevated CO2 partial pressure had a strong effect on dark respiration, decreasing both mass-based and area-based rates at all canopy positions, but had little or no effect on leaf physical and biochemical properties. 3Leaf sugars, starch, protein, N and LMA were all correlated with respiration rate, and are therefore strong predictors of area-based dark respiration rates. The y axis intercept of regressions of respiration rate on mean leaf N, protein, starch and LMA was lower for plants grown at elevated compared to ambient CO2 partial pressures because of the differential effect of growth at elevated CO2 partial pressure on leaf gas-exchange, chemical and physical characteristics. 4,The lower respiration rates for leaves from trees grown at elevated CO2 partial pressure resulted in a significant increase in the ratio of light-saturated net photosynthesis to respiration, increasing the potential carbon-use efficiency of these leaves. [source] Nitrogen-Enriched Nonporous Carbon Electrodes with Extraordinary SupercapacitanceADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Denisa Hulicova-Jurcakova Abstract Nitrogen-enriched nonporous carbon materials derived from melamine,mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol-like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300,µF,cm,2) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280,F,cm,3 in KOH, 152,F,cm,3 in H2SO4, and 92,F,cm,3 in tetraethylammonium tetrafluoroborate/propylene carbonate. [source] C3 grasses have higher nutritional quality than C4 grasses under ambient and elevated atmospheric CO2GLOBAL CHANGE BIOLOGY, Issue 9 2004Raymond V. Barbehenn Abstract Grasses with the C3 photosynthetic pathway are commonly considered to be more nutritious host plants than C4 grasses, but the nutritional quality of C3 grasses is also more greatly impacted by elevated atmospheric CO2 than is that of C4 grasses; C3 grasses produce greater amounts of nonstructural carbohydrates and have greater declines in their nitrogen content than do C4 grasses under elevated CO2. Will C3 grasses remain nutritionally superior to C4 grasses under elevated CO2 levels? We addressed this question by determining whether levels of protein in C3 grasses decline to similar levels as in C4 grasses, and whether total carbohydrate : protein ratios become similar in C3 and C4 grasses under elevated CO2. In addition, we tested the hypothesis that, among the nonstructural carbohydrates in C3 grasses, levels of fructan respond most strongly to elevated CO2. Five C3 and five C4 grass species were grown from seed in outdoor open-top chambers at ambient (370 ppm) or elevated (740 ppm) CO2 for 2 months. As expected, a significant increase in sugars, starch and fructan in the C3 grasses under elevated CO2 was associated with a significant reduction in their protein levels, while protein levels in most C4 grasses were little affected by elevated CO2. However, this differential response of the two types of grasses was insufficient to reduce protein in C3 grasses to the levels in C4 grasses. Although levels of fructan in the C3 grasses tripled under elevated CO2, the amounts produced remained relatively low, both in absolute terms and as a fraction of the total nonstructural carbohydrates in the C3 grasses. We conclude that C3 grasses will generally remain more nutritious than C4 grasses at elevated CO2 concentrations, having higher levels of protein, nonstructural carbohydrates, and water, but lower levels of fiber and toughness, and lower total carbohydrate : protein ratios than C4 grasses. [source] Hydrology and nitrogen balance of a seasonally inundated Danish floodplain wetlandHYDROLOGICAL PROCESSES, Issue 3 2004Hans Estrup Andersen Abstract This paper characterizes a seasonally inundated Danish floodplain wetland in a state close to naturalness and includes an analysis of the major controls on the wetland water and nitrogen balances. The main inputs of water are precipitation and percolation during ponding and unsaturated conditions. Lateral saturated subsurface flow is low. The studied floodplain owes its wetland status to the hydraulic properties of its sediments: the low hydraulic conductivity of a silt,clay deposit on top of the floodplain maintains ponded water during winter, and parts of autumn and spring. A capillary fringe extends to the soil surface, and capillary rise from groundwater during summer maintains near-saturated conditions in the root zone, and allows a permanently very high evapotranspiration rate. The average for the growing season of 1999 is 3·6 mm day,1 and peak rate is 5·6 mm day,1. In summer, the evapotranspiration is to a large degree supplied by subsurface storage in a confined peat layer underlying the silt,clay. The floodplain sediments are in a very reduced state as indicated by low sulphate concentrations. All nitrate transported into the wetland is thus denitrified. However, owing to modest water exchange with surrounding groundwater and surface water, denitrification is low; 71 kg NO3,N ha,1 during the study period of 1999. Reduction of nitrate diffusing into the sediments during water ponding accounts for 75% of nitrate removal. Biomass production and nitrogen uptake in above-ground vegetation is high,8·56 t dry matter ha,1 year,1 and 103 kg N ha,1 year,1. Subsurface ammonium concentrations are high, and convective upward transport into the root zone driven by evapotranspiration amounted to 12·8 kg N ha,1year,1. The floodplain wetland sediments have a high nitrogen content, and conditions are very favourable for mineralization. Mineralization thus constitutes 72% of above-ground plant uptake. The study demonstrates the necessity of identifying controlling factors, and to combine surface flow with vadose and groundwater flow processes in order to fully comprehend the flow and nitrogen dynamics of this type of wetland. Copyright © 2004 John Wiley & Sons, Ltd. [source] The suitability of muscle of Cirrhinus mrigala in the formation of gel: a comparative electrophoretic study of six tropical carp meatsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2008Rupsankar Chakrabarti Summary The annual inland fish production in India is 3.2 million tonnes and above. Aquaculture is around 80% of total inland fish production. The enhanced aquaculture production demands alternate processing methods for better utilisation of the farmed fish. Cirrhinus mrigala is one of the dominated species among cultured Indian major carps, but rated with lowest price. Fish meat with good gel-forming capacity is a prerequisite in the production of fast-moving fabricated analogue product. Cirrhinus mrigala had the highest gel strength, i.e. 435 gcm of its fresh meat in comparison with other carps. Apart from the highest protein and salt-soluble protein nitrogen content in fresh C. mrigala meat, this article also reports that the presence of the darkest thick band of myosin heavy chain and actin in the polyacrylamide gel electrophoresis pattern of salt-soluble extract of C. mrigala might be another possible reason for the highest gel strength in comparison with other carps. Cirrhinus mrigala contained white meat around 90%. This carp could be suitably used in the preparation of high-valued fabricated analogue product. [source] Monitoring the fermentation of the traditional Bulgarian beverage bozaINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2001Velitchka Gotcheva Summary For many centuries fermented foods have been produced and consumed world-wide as they are of such great importance for human nutrition. Fermentation helps to preserve the food, provides a wide variety of textures and flavours and significantly improves the nutritional properties of the raw materials used. In this work we tested the hypothesis that the fermentation process of the Bulgarian cereal-based traditional beverage boza was similar to other cereal-based fermentations. Boza was prepared both from whole-wheat grains and flour, and the effect of the raw material on product quality was studied. The main microorganisms responsible for boza fermentation, yeasts and lactobacilli, were identified and some physical and biochemical changes were monitored during the first 48 h of fermentation. A significant increase in glucose content was observed, while pH, viscosity, free amino nitrogen content and dry matter decreased during the fermentation. The use of wheat flour resulted in a product with higher viscosity and dry matter content when compared to that produced from whole-wheat grains. The effect of temperature on fermentation rate was also tested. [source] The Ratios of Carbon, Nitrogen, and Phosphorus in a Wetland Coastal Ecosystem of Southern IndiaINTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 2 2003Lizen Mathews Abstract The fertility of the coastal and estuarine waters is of great concern because of its influence on the productivity of these waters. Seasonal variations in the distribution of organic carbon, total nitrogen and total phosphorus in the sediments of Kuttanad Waters, a part of the tropical Cochin Estuary on the south west coast of India, are examined to identify the contribution of sediments to the fertility of the aquatic systems. The adjoining region has considerable agricultural activity. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. Organic carbon, total phosphorus and total nitrogen were higher in the fresh water zones and lower in the estuarine zones. Total phosphorus and organic carbon showed the lowest values during monsoon periods. No significant trends were observed in the seasonal distributions of total nitrogen. Ratios of C/N, C/P and N/P, and the phosphorus and nitrogen content indicate significant modification in the character of the organic matter. Substantial amounts of the organic matter can contribute to reducing conditions and modify diagenetic processes. [source] Feedback effects of chronic browsing on life-history traits of a large herbivoreJOURNAL OF ANIMAL ECOLOGY, Issue 4 2008M. Anouk Simard Summary 1Increasing ungulate populations are affecting vegetation negatively in many areas, but few studies have assessed the long-term effects of overbrowsing on individual life-history traits of ungulates. 2Using an insular population of white-tailed deer (Odocoileus virginianus Zimmermann; Anticosti, Québec, Canada) introduced in 1896, and whose density has remained high since the first evidence of severe browsing in the 1930s, we investigated potential feedbacks of long-term and heavy browsing on deer life-history traits. 3We assessed whether chronic browsing contributed to a decline of the quality of deer diet in early autumn during the last 25 years, and evaluated the impacts of reduced diet quality on deer body condition and reproduction. 4Rumen nitrogen content declined 22% between two time periods, 1977,79 and 2002,04, indicating a reduction in diet quality. 5After accounting for the effects of year within the time period, age and date of harvest in autumn, peak body mass of both sexes declined between the two time periods. At the end of November, males were on average 12% heavier and adult does 6% heavier in 1977,79 than in 2002,04. Hind foot length did not vary between time periods. 6The probability of conception increased 15% between the two time periods, but litter size at ovulation declined 7%, resulting in a similar total number of ovulations in 2002,04 and in 1977,79. 7Our results suggest that following a decline in diet quality, white-tailed deer females modified their life-history strategies to maintain reproduction at the expense of growth. 8Deer appear to tolerate drastic reductions in diet quality by modifying their life history traits, such as body mass and reproduction, before a reduction in density is observed. Such modifications may contribute to maintain high population density of large herbivores following population irruption. [source] Long-term enhancement of agricultural production by restoration of biodiversityJOURNAL OF APPLIED ECOLOGY, Issue 1 2007JAMES M. BULLOCK Summary 1Experimental manipulations have shown positive impacts of increased species richness on ecosystem productivity, but there remain some questions about this relationship. First, most studies last < 4 years, which raises issues about whether diversity,productivity relationships are maintained in mature communities. Secondly, the conservation relevance of many studies is debatable. We addressed both issues using long-term experimental studies of the agriculturally relevant hay yield of recreated species-rich grasslands. 2Grasslands were recreated within replicated experiments in ex-arable fields at two sites in southern England by using either species-poor or species-rich seed mixtures. The species-poor mixture comprised seven grasses as recommended for grassland creation in English agri-environment schemes. The species-rich mixture comprised 11 grasses and 28 forbs and was designed to recreate a typical southern English hay meadow. 3After 8 years the plots sown with species-rich mixtures resembled target diverse community types. The plots sown with species-poor mixtures had been colonized by a number of forbs but had lower numbers of grasses, legumes and other forbs than the species-rich plots. Increased hay yield of the species-rich plots in the first years of the experiments have been described in an earlier paper, and these differences were maintained after 8 years. 4In the eighth year the species-rich plots had an average 43% higher hay yield than the species-poor plots. Regression analysis showed that the variation in hay yield was related to differences in the number of non-leguminous forbs and showed no relation to grass or legume numbers. This suggests increased hay yield is an effect of the greater range of life forms exhibited by forbs rather than a simple fertilizing effect of legumes. 5The nitrogen content and phosphorus content of the hay showed complex treatment effects over time. However, the nutritional value of the hay was above the minimum requirements for livestock. 6Synthesis and applications. The aims of conservationists and farmers can often be in conflict. This study has shown that the recreation of diverse grasslands of conservation value can have a positive impact on hay yield, which benefits the farm business, and this is repeated across differing sites. Because the effect is maintained over time, farm income will be increased in the long term. [source] Response of multiple generations of cotton bollworm Helicoverpa armigera Hübner, feeding on spring wheat, to elevated CO2JOURNAL OF APPLIED ENTOMOLOGY, Issue 1 2006G. Wu Abstract:, The growth, development and consumption of three successive generations of cotton bollworm, Helicoverpa armigera (Hübner), reared on milky grains of spring wheat grown under elevated CO2 (double-ambient vs. ambient) in open-top chambers (OTCs) were examined. Decreases in protein, total amino acid, water and nitrogen content, and increases in total non-structure carbohydrates (TNCs) and ratio of TNC : nitrogen were found in wheat milky grains grown under elevated CO2 conditions. Changes in quality of wheat grains affected the growth, development and food utilization of H. armigera. Significantly longer larval lifespan for the third generation and lower pupal weight for all generations were observed in cotton bollworm fed on milky grains of spring wheat grown under elevated CO2 conditions. Bollworm fecundity was significantly decreased for the second and third generations under elevated CO2 levels. The consumption, frass per larva and relative consumption rate significantly increased in elevated CO2 compared with ambient CO2 conditions. However, the potential population consumption was significant reduced by elevated CO2 in the second and third generations. The results of this study indicate that elevated CO2 levels adversely affect grain quality, resulting in consistently increased consumption per larva for a longer period to produce less fecund bollworm through generations, suggesting that net damage of cotton bollworm on wheat will be less under elevated atmospheric CO2 levels because increased consumption is offset by slower development and reduced fecundity. [source] The role of GAP1 gene in the nitrogen metabolism of Saccharomyces cerevisiae during wine fermentationJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009R. Chiva Abstract Aim:, The aim of this study was to analyse the relevance of the general amino acid permease gene (GAP1) of the wine yeast Saccharomyces cerevisiae on nitrogen metabolism and fermentation performance. Methods and Results:, We constructed a gap1 mutant in a wine strain. We compared fermentation rate, biomass production and nitrogen consumption between the gap1 mutant and its parental strain during fermentations with different nitrogen concentrations. The fermentation capacity of the gap1 mutant strain was impaired in the nitrogen-limited and -excessive conditions. The nitrogen consumption rate between the wild strain and the mutant was different for some amino acids, especially those affected by nitrogen catabolite repression (NCR). The deletion of GAP1 gene also modified the gene expression of other permeases. Conclusions:, The Gap1 permease seems to be important during wine fermentations with low and high nitrogen content, not only because of its amino acid transporter role but also because of its function as an amino acid sensor. Significance and Impact of the Study:, A possible biotechnological advantage of a gap1 mutant is its scarce consumption of arginine, whose metabolism has been related to the production of the carcinogenic ethyl carbamate. [source] Highly purified natural rubber by saponificaion of latex: Analysis of green and cured propertiesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sureerut Amnuaypornsri Abstract Natural rubber (NR) was purified by saponification of fresh latex from Hevea brasiliensis and soaking process of the coagulum with aqueous NaOH solution. This treatment resulted in the decrease of nitrogen content to the same level as enzymatic deproteinized NR. The saponification of NR latex and soaking of the coagulum gave the rubber having good processability with easy to cure. The saponified rubber showed outstanding physical and dynamic mechanical properties such as high tensile properties, high storage modulus, low tan ,, low heat build-up and low dynamic compression set. The saponified rubber blend with styrene butadiene rubber (SBR) according to the recipe of rubber tire showed also a good performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Antimicrobial finishing of regular and modified nylon-6 fabricsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008S. E. Shalaby Abstract A simple, efficient, and practically applicable functional approach for improvement antimicrobial properties of nylon-6 fabrics and increase the washing durability of biofunctions was developed. This finishing approach is based on grafting of the fabrics with methacrylic acid (MAA) to create additional carboxylic groups in nylon-6 macromolecules, followed by subsequent reaction with dimethylalklbenzyl ammonium chloride (DMABAC) solution under alkaline conditions. The carboxylic groups react with cationic agent through ionic interaction, which led to the immobilization of QAS on nylon-6 fabrics. This immobilization was proofed through determination of nitrogen content, applying scanning electron microscopy (SEM), and FTIR microscopy. The effect of treatment conditions on salt uptake (SUT) on nylon-6 fabrics and reaction efficiency (RE) was investigated. The antimicrobial assessment of regular and grafted with PMAA nylon-6 fabrics treated with DMABAC revealed that both types of fabrics are characterized before washing, by quite strong biocide effect on Bacillus mycoides, Escherichia coli and Candida albicans. The role of grafting nylon-6 fabrics before treatment with salt on durability of antimicrobial functions seems to be more significant as the samples were repeatedly washed. Even after Laundring 10 times the grafted samples could still provide 80%, 100%, and 87.5% microbial reduction against B. mycoides, E. coli and C. albicans, respectively, in contrast with 42.6%, 65.6%, and 42.5% in case of regular nylon-6 fabrics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Silicon carbonitride thin-film coatings fabricated by remote hydrogen,nitrogen microwave plasma chemical vapor deposition from a single-source precursor: Growth process, structure, and properties of the coatings,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007A. M. Wrobel Abstract Silicon carbonitride (Si:C:N) films were produced by remote hydrogen,nitrogen microwave plasma chemical vapor deposition (RP-CVD) from a 1,1,3,3-tetramethyldisilazane precursor with a nitrogen content {[N2]/([H2] + [N2])} of 0.88 in the plasma-generating mixture and a substrate temperature in the range of 30,400°C. The effects of the substrate temperature on the rate and yield of the RP-CVD process and chemical structure (examined by Fourier transform infrared spectroscopy) of the resulting films were investigated. The Si:C:N film properties were characterized in terms of the density, hardness, elastic modulus, and friction coefficient. With the IR structural data, reasonable structure,property relationships were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 105: 122,129, 2007 [source] Large-scale geographical trends in fruit traits of vertebrate-dispersed temperate plantsJOURNAL OF BIOGEOGRAPHY, Issue 4 2003Arndt Hampe Abstract Aim, To assess large-scale geographical trends in the character of fleshy, vertebrate-dispersed fruits. Location, Europe between central Sweden and southern Spain. Methods, Analyses of fruit of sixty-three plant species from twenty-nine families were compiled from four regional data sets. Four structural and five chemical fruit traits were analysed intraspecifically to control rigorously for phylogenetic lineage effects. Trends were examined in relation to various biological features of the considered species. Results, Contents of soluble carbohydrate and lipids decreased markedly northwards. Fruit diameter and fresh mass peaked at the wettest site, while the pulp water content remained more constant throughout the gradient than any other fruit trait. Ash content, seed number and seed mass did not change, while the nitrogen content showed conflicting trends. No relation was detected between observed variation in fruit traits and fruit type, fruit colour, ripening season, plant growth form, leaf longevity, or geographical distribution of the considered plant species. Main conclusions, Considerable intraspecific variability exists in vertebrate-dispersed fruits on large geographical scales. Climate presumably affects particularly those traits related to carbon and water gain and storage. Most research on fruit,frugivore interactions has been carried out on small spatial scales and failed to find matchings between frugivore communities and the character of fleshy fruits. I suggest that explicitly addressed large-scale surveys on the geographical variability of fruits and their disperser assemblages are needed to elucidate their spatial patterns and to determine the extent to which fleshy fruit traits are shaped by animals and/or abiotic factors. [source] | ||||||||||||||||||||||||||||||||||||||||||||||