Distribution Of Nitrogen Compounds Research Articles

Role of Melatonin and Nitrogen Metabolism in Plants: Implications under Nitrogen-Excess or Nitrogen-Low

Melatonin is a new plant hormone involved in multiple physiological functions in plants such as germination, photosynthesis, plant growth, flowering, fruiting, and senescence, among others. Its protective role in different stress situations, both biotic and abiotic, has been widely demonstrated. Melatonin regulates several routes in primary and secondary plant metabolism through the up/down-regulation of many enzyme/factor genes. Many of the steps of nitrogen metabolism in plants are also regulated by melatonin and are presented in this review. In addition, the ability of melatonin to enhance nitrogen uptake under nitrogen-excess or nitrogen-low conditions is analyzed. A model that summarizes the distribution of nitrogen compounds, and the osmoregulation and redox network responses mediated by melatonin, are presented. The possibilities of using melatonin in crops for more efficient uptake, the assimilation and metabolization of nitrogen from soil, and the implications for Nitrogen Use Efficiency strategies to improve crop yield are also discussed.

The nitrogen transformation and controlling mechanism of NH3 and HCN conversion during the catalytic pyrolysis of amino acid

Pyrolysis can convert biomass into sustainable chemicals and fuels, but the nitrogen compounds in its non-lignocellulosic components may produce hazardous NOx and its precursors. In this paper, catalytic pyrolysis of glutamic acid (Glu), used as a representing compound for biomass nitrogen source, was investigated at bench scale to study the transformation of the nitrogen element and the mechanism of Ammonia (NH3) and Hydrogen Cyanide (HCN) formation. The yields of the liquid, gaseous and solid products and the distribution of nitrogen compounds were systematically analysed. The experimental results showed that catalytic pyrolysis with H-ZSM-5 could increase the nitrogen compounds in the gas product from 38.54 % to 53.95 %, while it can reduce the nitrogen in the tar and char by 69.22 % and 58.07 %, respectively. The result of Density Functional Theory (DFT) study showed that the deamination to ternary cyclic ethers was the optimum pathway for NH3 formation. The formation of HCN has been dominated by the removal of side chain groups (reaction path 8). The energy barrier of the reaction path 9 was reduced to a level comparable to the energy barrier of path 8 during the catalytic pyrolysis, which may compete with each other. The 8T cluster model of the H-ZSM-5 catalyst revealed that the hydrogen bond formed between the acid sites and the reactants played an significant role in decreasing the reaction energy barrier. The experimental and computational results demonstrated the controlling mechanism of acid sites on the production of NH3 and HCN compounds and provided fundamental understanding to nitrogen transformation during the biomass pyrolysis.

New insight into ammonium oxidation processes and mechanisms mediated by manganese oxide in constructed wetlands

Manganese oxide (MnOx) mediated ammonium (NH4+) oxidation in wetlands is receiving increased interest; however, the biochemical mechanisms of this process are vague due to only few studies have focused on terrestrial ecosystems. In this study, three subsurface flow constructed wetlands (CWs), high/low content of Mn-sand CW (HMn-CW/LMn-CW) and quartz sand CW (C-CWs), were set up to explore the extent of ammonium nitrogen (NH4+-N) removal and underlying mechanisms. According to the surface characteristics of Mn-sand, MnOx nanospheres were loaded as birnessite on the sand, while changes of the Mn/N contents indicated involvement of Mn-sand in NH4+-N removal. During the 120-day operation, higher extent of NH4+-N removal with decreased nitrous oxide (N2O) emission was achieved in the HMn-CW (76%) than in the LMn-CW (73%) and C-CW (67%). According to the distribution of nitrogen compounds and Mn2+, Mn-sand in the HMn-CW delayed oxidation of NH4+ and production of nitrate and nitrite. High abundance of Zooloea and Psychrobacter was observed in the Mn-sand layer of HMn-CW, corresponding to a higher observed NH4+-N removal. NH4+ oxidation to hydroxylamine and then to nitrite was enhanced in HMn-CW due to ammonia monooxygenase genes being promoted. The decrease of N2O emission was closely related to the genus TM7a, verified by Pearson correlation analysis. Our findings expand the knowledge of MnOx-mediated NH4+ oxidation in wetlands and support the potential application of manganese oxide for effective nitrogen removal in CWs.

FOLIAR APPLICATION OF POTASSIUM AND ZINC ENHANCES THE PRODUCTIVITY AND VOLATILE OIL CONTENT OF DAMASK ROSE (Rosa damascena Miller var. trigintipetala Dieck)

Potassium (K) levels are decreasing worldwide in agricultural soils, and K deficiency is becoming a major issue. Study on damask rose response to K application is scarce. Furthermore, despite its importance in the cell division, photosynthesis and protein synthesis, there is a lack of published reports on plant responses to zinc (Zn) application. Further research is required to understand the damask rose's response to both elements. This study investigated the effects of K and Zn foliar application on the vegetative growth, flower yield, and volatile oil content and composition of damask rose. K and Zn nutrition was applied either individually or combined as K2SO4 and ZnSO4 at 0.5 or 1.0%. Foliar application of K2SO4 and ZnSO4 was applied with a manual pump four times in each growing season, the first at the beginning of stem elongation and leaf formation, and then at two-weekly intervals. Results showed that K and/or Zn treatments significantly improved the growth characters, flower yield, relative water content (RWC), stomatal conductance, and essential oil content and composition such as linalool, nerol, citronellol, geraniol, and nonadecane. The chlorophyll content, total soluble sugars (TSS), and protein content also increased, but free amino acid content decreased, suggesting that the distribution of nitrogenous compounds (between amino acids and proteins) and their transformation were influenced by K and Zn supply. Individual applications of K or Zn increased the N, P, K, and Zn contents in damask rose leaves, relative to the control, which increased further with combined applications of K and Zn. Results suggest that foliar application of K and/or Zn could be part of the damask rose fertilization program to provide plants with the optimum level of nutrition for improving the quantity and quality of flowers and essential oil yields.

A Comparison of Some Interpolation Techniques for Determining Spatial Distribution of Nitrogen Compounds in Groundwater

The aim of the study was to analyse spatial variability of selected parameters of subsurface waters in the area of approximately 10 ha, located in the valley of the Ciemięga River in the village of Snopków, near Lublin, Poland. For the purpose of this study, nine sections were delimited, each with four points of collecting groundwater. In the groundwater samples, there were measured {text{NH}}_{4}^{ + }, {text{NO}}_{3}^{-} , and {text{NO}}_{2}^{-}. Due to the small number of samples, the analysis was limited to deterministic interpolation methods. The following methods were compared using leave-one-out cross-validation procedure: triangulation, inverse distance weighting, radial base function, and modified Shepard’s method. The methods which proved to be optimal were used to create spatial variability maps of the analysed parameters. Spatial interpolation and visualization of the results were performed in Surfer ver.16, and other calculations were conducted using R software.

Effects of red mud on emission control of NOx precursors during sludge pyrolysis: A protein model compound study

The nitrogen-containing gases pyrolyzed from sewage sludge can be converted into NOx compounds, which would cause severe environmental pollution. This study developed a new strategy to reduce the emission of NOx precursors such as ammonia (NH3) and hydrogen cyanide (HCN) using red mud. The highest reduction efficiencies (15.10% for NH3 and 24.72% for HCN) were achieved at 900 °C while compared with those pyrolyzed from raw sludge without the addition of red mud. The transformation and distribution of nitrogenous compounds in three-phase pyrolysates were studied at 400–800 °C for pyrolysis process of a model soybean protein compound. The nitrogenous compounds, i.e., amine-N, heterocyclic-N, and nitrile-N, were identified as the three main intermediates related with the production of NOx precursors. Ferric oxide (Fe2O3) and calcium oxide (CaO) presented in red mud were identified as the driving force which facilitated nitrogen stabilization in char (e.g., at 800 °C, 21.63% increase of char-N after addition of Fe2O3, and 41.54% increase of char-N after addition of CaO). These metal oxides possibly reacted with protein-N to form FexN and CaCxNy, inhibited the secondary cracking of amine-N compounds in tar (e.g., at 800 °C, 2.33% increase of amine-N after addition of Fe2O3, and 0.38% increase of amine-N after addition of CaO), and reduced the production of nitrile-N (e.g., at 800 °C, 30.41% reduction of nitrile-N after addition of Fe2O3, and 27.40% reduction of nitrile-N after addition of CaO) and heterocyclic-N compounds (e.g., at 800 °C, 21.60% reduction of heterocyclic-N after addition of Fe2O3, and 13.98% reduction of heterocyclic-N after addition of CaO). Hence, the emission of NH3 and HCN in gas phase can be controlled. Moreover, Fe2O3 showed better capability in controlling the emission of NOx precursors than CaO (higher reduction of NH3-N and higher reduction of HCN-N). These results indicate that red mud is an efficient catalyst to reduce emission of NOx precursors through controlling intermediates at 400–800 °C.

Examining nitrogen dynamics in the unsaturated zone under an inactive cesspit using chemical tracers and environmental isotopes

This study evaluates the dynamics of nitrogen compounds generated by infiltration of wastewater from an inactive cesspit in the unconfined and sedimentary Adamantina Aquifer in Urânia, Brazil. A monitoring station, consisting of an 11.2 m well (1.8 m in diameter) with an array of 12 tensiometers and 12 suction lysimeters, was installed to monitor the shallow unsaturated zone from 0.5 to 9 m depth. A monitoring well was also installed below the water level to monitor the shallow aquifer. High amounts of ammonium (up to 96 mg/L NH4+-N) and nitrate (up to 458 mg/L NO3−-N) were observed in the unsaturated zone porewater which is comparable to active septic systems effluents. The distribution of NO3−, Cl− and Na+, typical constituents of sewage effluents, varied seasonally and spatially, which is correlated with changes in infiltration rates between the wet and dry seasons and with hydraulic conductivity variations in interlayered sandy and clayey sediments. A detailed monitoring of porewater geochemistry demonstrated the occurrence of several important reactions affecting nitrogen dynamics in the unsaturated zone: i) oxidation of organic matter, ii) ammonification, iii) nitrification, iv) methanogenesis, v) denitrification and likely, vi) sulfate reduction. The changes in nitrogen compound distribution and δ15NNO3 and δ18ONO3 values in porewater, in association with the N2O concentration and δ15NN2O and δ18ON2O signatures in gas samples, indicate the occurrence of nitrification and denitrification, suggesting the coexistence of reducing and oxidizing microsites in the unsaturated zone. This study indicated that cesspits can generate a significant amount of nitrate even a few years after being inactivated which can represent a potential long-term source of nitrate to groundwater in highly populated areas.

Stable isotope on the evaluation of water quality in the presence of WWTPs in rivers.

We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we observed the significant releases of NH4 (+)-N from effluent of wastewater treatment plants (WWTPs) in two tributaries that has resulted in the increases of ammonium nitrogen (NH4 (+)-N) in Han River as well as in Tancheon and Jungrangcheon. Due to the increases of NH4 (+)-N in two tributaries, the larger distribution of δ(15)N-NH4 (+) was observed than those of δ(15)N-NO3 (-) in downstream. We calculated the contribution rate of ammonium nitrogen and nitrate nitrogen from effluent to downstream according to the results of stable isotope. The contribution rates of δ(15)N-NH4 (+) from effluent to downstream were significant that ranged between 53 and 100% in Tancheon and between 27 and 100% in Jungrangcheon. While the contribution of δ(15)N-NO3 (-) was not significant in Tancheon, it was occasionally observed in Jungrangcheon. These results demonstrated that WWTPs are the major sources of NH4 (+)-N in two tributaries, which caused the distinguishable stable isotope of δ(15)N-NH4 (+). Therefore, the stable isotope of δ(15)N-NH4 (+) could be a useful parameter or tracer for the evaluation of NH4-N released from WWTPs in rivers.

Outbreak of fatal nitrate toxicosis associated with consumption of fennels (Foeniculum vulgare) in cattle farmed in Campania region (southern Italy)

Nitrate and nitrite are toxicants that have become increasingly significant environmental chemicals. Increase in environmental distribution of nitrogenous compounds, especially in surface and ground water, has been attributed to the intensive use of nitrate as agricultural fertilizers and to increasing amounts of nitrogenous wastes produced by municipalities, industries, and feedlots. The purpose of this study is to illustrate a fatal nitrate toxicosis in cattle associated with the consumption of fennels (Foeniculum vulgare). Fifteen cows from the same farm suddenly developed weakness, muscular tremors, respiratory distress, and finally convulsions. The affected animals died within 24 to 48h from the onset of the clinical signs. Five cows underwent a complete post-mortem examination. In all examined animals, gross lesions included presence of dark unclotted blood around the nostrils and the anal region, moderate inflammation of the gastrointestinal mucosa, and brown discoloration of the skeletal muscles and kidneys. The histological examination showed tubular degeneration and congestion of glomerular vessels in the kidney. Toxicological analysis detected nitrates at 4 672.2ppm in the fennels used to feed the animals. The source of exposure to nitrates was identified in the fennels. The fennels were grown in a polluted area of the Campania region in southern Italy and distributed in a public market for human consumption. The waste from the sale of the fennels was fed to the cows. The accumulation of nitrates in some vegetables poses a risk not only for animal health but also for human and environmental safety.

Analyses and assessment of the spatial and temporal distribution of nitrogen compounds in surface waters

AbstractThe temporal concentration variations and spatial distribution of nitrogen compounds (nitrate, nitrite, ammonium) in the natural surface waters of Stara Zagora Region, Bulgaria, over a period of 1 year were assessed in the present study. Nitrate‐nitrogen concentrations in all surface water samples, except for the December value – 21.8 mg/L in Zetyovo Reservoir, were within the permissible national quality standards. NO2 –‐N could be classified as a priority pollutant of Chirpan and Zetyovo Reservoirs waters. The greatest extent of NH 4 +‐N pollution was registered in Chirpan Reservoir surface waters. The correlation study revealed appreciable mutual relationship only between NH4 +‐N and NO 2 –‐N in the surface waters. The hierarchical cluster analysis (HCA) exhibited divergent apportionment of nitrogen compounds in the surface water bodies.

Characteristics of Oil Sources from the Chepaizi Swell, Junggar Basin, China

Abstract:So far there has been no common opinion on oil source of the Chepaizi swell in the Junggar Basin. Therefore, it is difficult to determine the pathway system and trend of hydrocarbon migration, and this resulted in difficulties in study of oil‐gas accumulation patterns. In this paper, study of nitrogen compounds distribution in oils from Chepaizi was carried out in order to classify source rocks of oils stored in different reservoirs in the study area. Then, migration characteristics of oils from the same source were investigated by using nitrogen compounds parameters. The results of nitrogen compounds in a group of oil/oil sand samples from the same source indicate that the oils trapped in the Chepaizi swell experienced an obvious vertical migration. With increasing migration distance, amounts and indices of carbazoles have a regular changing pattern (in a fine linear relationship). By using nitrogen compounds techniques, the analyzed oil/oil sand samples of Chepaizi can be classified into two groups. One is the samples stored in reservoir beds of the Cretaceous and Tertiary, and these oils came from mainly Jurassic source rock with a small amount of Cretaceous rock; the other is those stored in the Jurassic, Permian and Carboniferous beds, and they originated from the Permian source. In addition, a sample of oil from an upper Jurassic reservoir (Well Ka 6), which was generated from Jurassic coal source rock, has a totally different nitrogen compound distribution from those of the above‐mentioned two groups of samples, which were generated from mudstone sources. Because of influence from fractionation of oil migration, amounts and ratios of nitrogen compounds with different structures and polarities change regularly with increasing migrating distance, and as a result the samples with the same source follow a good linear relationship in content and ratio, while the oil samples of different sources have obviously different nitrogen compound distribution owing to different organic matter types of their source rocks. These conclusions of oil source study are identical with those obtained by other geochemical bio‐markers. Therefore, nitrogen compounds are of great significance in oil type classification and oil/source correlation.

Nitrogen compounds in drain sewage after constructed wetlands

Constructed wetlands, commonly known as ground filters, are well suited mostly for wastewater treatment in areas with no central sewage system. The basic difficulty with exploitation of constructed wetlands is connected with irregular hydraulic overload of its surface. However, irregular wastewater inflow can be reduced by cyclical irrigation which increases efficiency. The unquestionable advantage of the constructed wetlands is inexpensive construction and exploitation as well as low energy consumption. The constructed wetlands also fit very well in surrounding area. The investigation concerned the analysis of two constructed wetlands which are composed of mechanical separation (septic tank) and a filter bed with subsurface flow. The research has been undertaken in a period from July to December 2008, with regard to concentration distribution of nitrogen compounds in municipal sewage after constructed wetlands. The preliminary investigation on constructed wetland which has been exploited for 10 years showed variable removal efficiency of nitrogen compounds. The continuation of the research can indicate the efficiency of wastewater treatment in summer and winter season.

Nitrogen Compound Distribution in Refined Middle Distillate Fuels

Three diverse middle distillate fuels from Mobile, Alabama, Jacksonville, Florida, and Kirachi, Pakistan were analyzed to quantify the organic nitrogen compound distribution in each. Organo-nitrogen compounds were isolated by a mild acid extraction followed by a silica-gel adsorption procedure. The extraction process yielded three extracts for each fuel: a basic nitrogen extract in methylene chloride, a nonbasic nitrogen extract in methylene chloride, and a nonbasic nitrogen extract in methanol. The major compounds in each extract were identified by gas chromatography/mass spectrometry (GC/MS).

Nitrogen Compound Distribution of Refined Middle Distillate Fuels

Three middle distillate fuels originating from New Zealand, Venezuela, and Texas were studied to determine the nitrogen compound distribution in each fuel. Organo-nitrogen compounds in the fuels were isolated by mild acid extraction followed by silica gel adsorption. The extraction scheme yielded three extracts for each fuel—a basic nitrogen extract in methylene chloride, a non-basic nitrogen extract in methyl alcohol, and a non-basic nitrogen extract in methylene chloride. The major constituents of each extract were identified by gas chromatography/mass spectrometry (GC/MS).

Distribution of nitrogenous nutrients and denitrifiers strains in estuarine sediment profiles of the Tanshui River, northern Taiwan

Chemical profiles of both oxidized (nitrate and sulfate) and reduced (ammonium, sulfide, acid-volatile sulfide [AVS], and pyrite) materials and the corresponding distribution of denitrifier microbial communities were measured at low tide in sediments at Guandu in the estuary of the Tanshui River, northern Taiwan in August 2002. Denitrifier strains were isolated for physiological and phylogenic analyses. Based on the distribution of nitrogenous compounds and denitrifier abundances, the vertical profile of Guandu sediments could be separated into four layers: a mixed layer (the top 1 cm of depth, respectively containing 0.82–2.37 and 535.9–475.0 μM of nitrate and ammonium), a nitrate-concentrated layer (1–5 cm in depth, 2.37–0.53 and 475.0–1192.1 μM, respectively), a denitrifier-aggregation layer (5–7 cm in depth, 0.53–0.72 and 1192.1–1430.1 μM, respectively), and an ammonium-enriched layer (7–12 cm in depth, 0.72–0.78 and 1430.1–2196.6 μM, respectively). Denitrifier strains were detected in all layers except for the mixed layer. A variety of metabolic processes by these strains may occur in different layers. Bacillus jeotgali-, Bacillus sphaericus-, and Bacillus firmus-related strains isolated from the nitrate-concentrated layer may be involved in the nitrification-denitrification coupling process due to the relatively low nitrate concentrations (maximum = 2.37 μM), and may contribute to denitrification not nitrification. Bacillus bataviensis- and B. jeotgali-related strains isolated from the denitrifier-aggregation layer comprised the predominant denitrifier population (3.64 × 10 4 cells/g of denitrifier abundance). They possess the ability of dissimilatory nitrate reduction to ammonium (DNRA). Bacillus jeotgali-related strains and two newly identified strains of GD0705 and GD0706 isolated from the ammonium-enriched layer possibly use fermentative processes as the main metabolic pathway instead of denitrification when nitrate is scarce, and this further supports the high ammonium concentrations (up to 2.20 mM) found in the Guandu sediments. In addition, spore formation also enhances the chance of survival of these strains in the face with such a nitrate-deficient environment.

Specific Nitrogen Boiling Point Profiles of Vacuum Gasoils

Vacuum gasoils are heavy petroleum cuts that are hydrotreated prior to being transformed into valuable fuels by hydrocracking. Hydrotreatment is a refining process carried out to reduce the content of heteroatomic molecules in petroleum cuts to meet the stringent fuel specifications and to prevent catalyst poisoning in downstream conversion processes. Kinetic modeling of hydrotreatment reactions requires information about the distribution of nitrogen compounds in vacuum gasoils and in their hydrotreated effluents. Analysis of heavy distillates is a challenge since nitrogen molecules are present in small amounts in the hydrocarbon matrix. Moreover, a large number of isomers are distributed over a large boiling point range (350−650 °C). This paper presents a GC-NCD method developed to determine the nitrogen distribution in vacuum gasoils. To validate the GC-NCD results, vacuum gasoils, narrow cuts as well as hydrotreated vacuum gasoils, have been analyzed. Quantitative data were compared to the total nitrog...

Oil migration in the Lunnan region, Tarim Basin, China based on the pyrrolic nitrogen compound distribution

The distribution of pyrrolic nitrogen compounds (carbazoles and benzocarbazoles) in crude oils of the Lunnan region, produced from Ordovician, Carboniferous, Triassic and Jurassic reservoirs, are similar in the overall composition, but different in the total and the relative abundances of individual pyrrolic compounds. Since it was previously demonstrated that most of the Lunnan oils are sourced from the Middle–Upper Ordovician shaly carbonate rocks, and with similar maturity, these analytical results for pyrrolic nitrogen compounds indicate a remarkable geochromatographic fractionation effect during oil migration, especially for lateral secondary migration. Based on our results, we have shown that the migration and entrapment pathway of the Ordovician and Carboniferous oils is different from those for Triassic and Jurassic oils in the Lunnan region. That is, the Ordovician and Carboniferous oils migrated laterally from west to east, and their main filling points were on both southwest sides of the Lunnan and Sangtarmu Fault-horst Belts. On the other hand, Triassic and Jurassic oils migrated vertically via fault conduits from the Ordovician source kitchen and then migrated laterally from north to south.

Salt-dependent expression of a nitrate transporter and two amino acid transporter genes in Mesembryanthemum crystallinum.

Uptake and transport of inorganic nitrogen and allocation of amino acids are essential for plant growth and development. To study the effects of salinity on the regulation of transporters for nitrogenous compounds, we characterized the putative nitrate transporter McNRT1 and the amino acid transporters McAAT1 and McAAT2 from Mesembryanthemum crystallinum. By transcript analyses, McAAT1 was found in leaves, McAAT2 in roots, and McNRT1 in both tissues. By in situ PCR McNRT1 was localized, for example, to epidermal and vascular cells whereas McAAT2 was abundant in most cell types in mature roots and McAAT1 in the mesophyll and cells neighbouring xylem vessels in leaves. In response to salt stress, expression of McAAT2 and McNRT1 was stimulated in the root vasculature. In addition, McNRT1 and McAAT1 signals increased in the leaf phloem. Growth of yeast mutants deficient in histidine uptake was restored by McAAT2 whereas both McAAT1 and McAAT2 complemented a yeast mutant carrying a defect in proline uptake. The differential and cell-specific transcriptional activation of genes encoding nitrogen and amino acid transporters under salt stress suggest complex coordinated regulation of these transporter families to maintain uptake and distribution of nitrogenous compounds and amino acids under conditions of high salinity in plants.

Analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens fed on maize-based diets containing guar gum, or wheat-based diets

1. Three maize diets containing graded levels (0, 0.1, 0.3%) of guar gum and two wheat diets differing in their in vitro viscosities were fed to male broiler chickens (7 to 23 d) for measurements of growth performance and analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens. Analyses of degradation products were conducted to define which step (hydrolysis or absorption) was most involved in the negative effects of the digesta viscosity on lipid and protein digestibilities. The experiment was also carried out to examine whether effects of wheats could be explained in terms of intestinal viscosity alone. 2. The intestinal viscosities with wheat diets were within the range of those observed with the three maize diets. The correlations between in vivo and in vitro viscosities were higher with real than with potential applied viscosity of diets, both in jejunum and ileum. 3. The mean gain : food ratio observed with wheat diets was lower ( P < 0.05) than with maize diets despite lower ( P < 0.05) mean intestinal viscosities in birds given the wheat than given the maize diets. This shows that factors different from intestinal viscosity were also involved in the negative effects of wheats. 4. Distributions of nitrogen compounds in digesta were characterised by low proportions of compounds with high molecular weight (> 12,000). For all classes of nitrogen compounds, the contents measured in digesta dry matter did not differ between chickens fed with or without guar gum. 5. Distributions of lipid classes in both jejunum and ileum were characterised by a large proportion of free fatty acids (FFA) and very few triglycerides (TG). In the ileum, FFA and TG contents were both positively correlated with supernatant viscosity, but the slope for FFA content was 35 times higher than for TG. In these relationships, there was no difference between maize and wheat diets. 6. It is concluded that absorption was the main step involved in the lipid digestibility reduction due to intestinal viscosity. For proteins, the most important step (hydrolysis or absorption) involved in decreased digestibility due to intestinal viscosity was not clearly identified.

Nitrogen compound distribution in middle distillate fuels derived from petroleum, oil shale, and tar sand sources

Nitrogen compound distribution in middle distillate fuels derived from petroleum, oil shale, and tar sand sources