Role Of Urea Research Articles

Role of urea and melamine as synergic co-plasticizers for starch composites for fertilizer application

Herein we describe the interaction of starch, urea, and melamine (C3N6H6) in composite materials for use as controlled-release plant fertilizer. Slow-release fertilizers are important in minimizing nutrient losses due to run-off, leaching, and other factors. Urea is an effective plasticizer for starch and is an important nitrogen fertilizer throughout the world. Melamine also has high nitrogen content and could be combined with urea-starch composites to provide enhanced controlled-release fertilizer. This study reports the structural interaction and the performance gain of melamine addition to starch-urea composites. Composites were characterized by spectroscopic techniques (FT-Raman and 13C NMR) detailing the interaction between melamine, urea, and starch. These interactions helped facilitate extrusion processing by lowering viscosity and processing temperatures suggesting an enhanced starch plasticizing effect of starch-urea-melamine composites. Further research into the co-plasticization of starch by urea and melamine could be exploited for improved controlled-release fertilizer products.Further research into the co-plasticization of starch by urea and melamine could be exploited for improved controlled-release fertilizer products.

Urea as a single denaturing agent in deproteinisation of natural rubber latex

This paper describes the utilisation of urea as a single chemical agent to obtain deproteinised high ammoniated natural rubber latex (HA-NRL). The role of urea in HA-NRL deproteinisation was further investigated by employing two different concentrations of urea solution which are low (0.01–0.05%) and high (1.0–5.0%) concentrations. The study assessed the potential usage of urea as a single denaturing agent in the presence of neither stabilising agent nor additives during the deproteinisation process. The effect of different urea concentrations on properties of deproteinised NRL was further scrutinised by using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), nitrogen content analysis, extractable protein (EP) content, Zeta potential, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and physical strength. The presence of residual urea is pertinent as the concentration of urea increases while contributing to the increase of total nitrogen content in the resultant film. Leaching the film with hot water is sufficient to remove the residual urea as supported by an ATR-FTIR analysis. Initial exploratory data analysis of low and high urea concentrations on the effect of nitrogen content, EP, surface charge properties of latex and green strength of the deproteinised NRL were evaluated and their relation to each factor was further discussed. Based on the initial findings, urea was observed to be less effective as a single denaturant. Nonetheless, the properties of the deproteinised HA-NRL treated with urea were revealed to be markedly influenced by the urea concentration.

Gelling mechanism and interactions of polysaccharides from Mesona blumes: Role of urea and calcium ions

In this study, the relaxation modulus was used to elucidate the gelling mechanism of polysaccharides from Mesona blumes. The pH of Mesona blumes polysaccharides (MBP) was adjusted could significantly change the relaxation modulus of MBP. The results showed that the hydrogen bonds and electrostatic interaction existed in during the formation of MBP gel. The addition of salt ions (sodium ions and calcium ions), EDTA and urea have different effects on the relaxation modulus of MBP. Result showed that the hydrogen bond was the main force maintaining the MBP gel network structure, followed was calcium ions. And electrostatic interaction was not the decisive role of gel formation. The small molecules with active hydrogen-bond donors and/or acceptors were added into MBP, which proved −COOH was involved in the hydrogen bonds formation of MBP gel. In addition, the entanglement network number (ENN) results quantitatively assessed contribution of interaction: hydrogen bonds interaction > calcium ions (calcium bridge) >electrostatic interaction.

Urea treatment in fluid restriction-refractory hyponatraemia.

Hyponatraemia in hospitalized patients is common and associated with increased mortality. International guidelines give conflicting advice regarding the role of urea in the treatment of SIADH. We hypothesized that urea is a safe, effective treatment for fluid restriction-refractory hyponatraemia. Review of urea for the treatment of hyponatraemia in patients admitted to a tertiary hospital during 2016-2017. Primary end-point: proportion of patients achieving a serum sodium ≥130mmol/L at 72hours. Urea was used on 78 occasions in 69 patients. The median age was 67 (IQR 52-76), 41% were female. Seventy (89.7%) had hyponatraemia due to SIADH-CNS pathology (64.3%) was the most common cause. The duration was acute in 32 (41%), chronic in 35 (44.9%) and unknown in the rest. The median nadir serum sodium was 122mmol/L (IQR 118-126). Fluid restriction was first-line treatment in 65.4%. Urea was used first line in 21.8% and second line in 78.2%. Fifty treatment episodes (64.1%) resulted in serum sodium ≥130mmol/L at 72hours. In 56 patients who received other prior treatment, the mean sodium change at 72hours (6.9±4.8mmol/L) was greater than with the preceding treatments (-1.0±4.7mmol/L; P<0.001). Seventeen patients (22.7%) had side effects (principally distaste), none were severe. No patients developed hypernatraemia, overcorrection (>10mmol/L in 24hours or >18mmol/L in 48hours), or died. Urea is safe and effective in fluid restriction-refractory hyponatraemia. We recommend urea with a starting dose of ≥30g/d, in patients with SIADH and moderate to profound hyponatraemia who are unable to undergo, or have failed fluid restriction.

The role of urea in neuronal degeneration and sensitization: An in vitro model of uremic neuropathy.

BackgroundUremic neuropathy commonly affects patients with chronic kidney disease, with painful sensations in the feet, followed by numbness and weakness in the legs and hands. The symptoms usually resolve following kidney transplantation, but the mechanisms of uremic neuropathy and associated pain symptoms remain unknown. As blood urea levels are elevated in patients with chronic kidney disease, we examined the morphological and functional effects of clinically observed levels of urea on sensory neurons.MethodsRat dorsal root ganglion neurons were treated with 10 or 50 mmol/L urea for 48 h, fixed and immunostained for PGP9.5 and βIII tubulin immunofluorescence. Neurons were also immunostained for TRPV1, TRPM8 and Gap43 expression, and the capsaicin sensitivity of urea- or vehicle-treated neurons was determined.ResultsUrea-treated neurons had degenerating neurites with diminished PGP9.5 immunofluorescence, and swollen, retracted growth cones. βIII tubulin appeared clumped after urea treatment. After 48 hours urea treatment, neurite lengths were significantly reduced to 60 ± 2.6% (10 mmol/L, **P < 0.01), and to 56.2 ± 3.3% (50 mmol/L, **P < 0.01), compared with control neurons. Fewer neurons survived urea treatment, with 70.08 ± 13.3% remaining after 10 mmol/L (*P < 0.05) and 61.49 ± 7.4% after 50 mmol/L urea treatment (**P < 0.01), compared with controls. The proportion of neurons expressing TRPV1 was reduced after urea treatment, but not TRPM8 expressing neurons. In functional studies, treatment with urea resulted in dose-dependent neuronal sensitization. Capsaicin responses were significantly increased to 115.29 ± 3.4% (10 mmol/L, **P < 0.01) and 125.3 ± 4.2% (50 mmol/L, **P < 0.01), compared with controls. Sensitization due to urea was eliminated in the presence of the TRPV1 inhibitor SB705498, the mitogen-activated protein kinase kinase inhibitor PD98059, the PI3 kinase inhibitor LY294002 and the TRPM8 inhibitor N-(3-Aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide (AMTB hydrochloride).ConclusionNeurite degeneration and sensitization are consistent with uremic neuropathy and provide a disease-relevant model to test new treatments.

Lack of urea transporters, UT-A1 and UT-A3, increases nitric oxide accumulation to dampen medullary sodium reabsorption through ENaC.

Although the role of urea in urine concentration is known, the effect of urea handling by the urea transporters (UTs), UT-A1 and UT-A3, on sodium balance remains elusive. Serum and urinary sodium concentration is similar between wild-type mice (WT) and UT-A3 null (UT-A3 KO) mice; however, mice lacking both UT-A1 and UT-A3 (UT-A1/A3 KO) have significantly lower serum sodium and higher urinary sodium. Protein expression of renal sodium transporters is unchanged among all three genotypes. WT, UT-A3 KO, and UT-A1/A3 KO acutely respond to hydrochlorothiazide and furosemide; however, UT-A1/A3 KO fail to show a diuretic or natriuretic response following amiloride administration, indicating that baseline epithelial Na+ channel (ENaC) activity is impaired. UT-A1/A3 KO have more ENaC at the apical membrane than WT mice, and single-channel analysis of ENaC in split-open inner medullary collecting duct (IMCD) isolated in saline shows that ENaC channel density and open probability is higher in UT-A1/A3 KO than WT. UT-A1/A3 KO excrete more urinary nitric oxide (NO), a paracrine inhibitor of ENaC, and inner medullary nitric oxide synthase 1 mRNA expression is ~40-fold higher than WT. Because endogenous NO is unstable, ENaC activity was reassessed in split-open IMCD with the NO donor PAPA NONOate [1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine)], and ENaC activity was almost abolished in UT-A1/A3 KO. In summary, loss of both UT-A1 and UT-A3 (but not UT-A3 alone) causes elevated medullary NO production and salt wasting. NO inhibition of ENaC, despite elevated apical accumulation of ENaC in UT-A1/A3 KO IMCD, appears to be the main contributor to natriuresis in UT-A1/A3 KO mice.

Urea changes oocyte competence and gene expression in resultant bovine embryo in vitro.

SummaryNutrition influences the microenvironment in the proximity of oocyte and affects early embryonic development. Elevated blood urea nitrogen, even in healthy dairy cows, is associated with reduced fertility and there is high correlation between blood urea levels and follicular fluid urea levels. Using a docking calculation (in silico), urea showed a favorable binding activity towards the ZP-N domain of ZP3, that of ZP2, and towards the predicted full-length sperm receptor ZP3. Supplementation of oocyte maturation medium with nutrition-related levels of urea (20 or 40 mg/dl as seen in healthy dairy cows fed on low or high dietary protein, respectively) dose-dependently increased: (i) the proportion of oocytes that remained uncleaved; and (ii) oocyte degeneration; and reduced cleavage, blastocyst and hatching rates. High levels of urea induced shrinkage in oocytes, visualised using scanning electron microscopy. Urea downregulated NANOG while dose-dependently upregulating OCT4, DNMT1, and BCL2 expression. Urea at 20 mg/dl induced BAX expression. Using mathematical modelling, the rate of oocyte degeneration was sensitive to urea levels; while cleavage, blastocyst and hatching rates exhibited negative sensitivity. The present data imply a novel role for urea in reducing oocyte competence and changing gene expression in the resultant embryos.

Urea controlled hydrothermal synthesis of ammonium aluminum carbonate hydroxide rods

In this study, ammonium aluminum carbonate hydroxide (AACH) rods were controllably prepared using the hydrothermal method by manipulating the amount of urea in the reaction system. The experimental results showed that AACH in rod shape was able to be gradually transformed from γ-AlOOH in cluster shape during the molar ratios of urea to Al in the reactants were ranged from 8 to 10, and the yield of AACH has increased accordingly. When the molar ratio of urea to Al reaches 11, pure AACH rods with a diameter of 500 nm and a length of 10 μm approximately was able to be produced. Due to the slow decomposition of urea during the hydrothermal reaction, the nucleation and growth of AACH crystal proceed step by step. Therefore, the crystal can fully grow on each crystal plane and eventually produce a highly crystalline rod-shaped product. The role of urea in controlling the morphology and yield of AACH was also discussed in this paper systematically.

The Lack of Urea Transporters, UT‐A1 and UT‐A3, Increases Nitric Oxide Accumulation to Dampen Medullary Sodium Reabsorption Through ENaC

While the role of urea in urine concentration is known, the effect of urea handling by the urea transporters, UT‐A1 and UT‐A3, on sodium balance remains elusive. Serum and urinary sodium is similar between wild‐type mice (WT) and UT‐A3 null (UT‐A3 KO) mice; however, mice lacking both UT‐A1 and UT‐A3 (UT‐A1/A3 KO) have significantly lower serum sodium and higher urinary sodium. Protein expression of renal sodium transporters (NHE3, NCC, NaATPase, NKCC2, ENaC) is unchanged among all three genotypes. WT, UT‐A3 KO and UT‐A1/A3 KO acutely respond to hydrochlorothiazide and furosemide; however, UT‐A1/A3 KO fail to show a diuretic or natriuretic response following amiloride administration indicating that ENaC activity is impaired. Interestingly, IMCD biotinylation showed that UT‐A1/A3 KO have more ENaC at the apical membrane than WT, and single channel analysis of ENaC in isolated, split‐open IMCD revealed that ENaC channel density and open probability is higher in UT‐A1/A3 KO than WT. UT‐A1/A3 KO excrete larger amounts of urinary nitric oxide (NO), a paracrine inhibitor of ENaC, and express 40‐fold more inner medullary nitric oxide synthase 1 (NOS1) mRNA than WT. Because endogenous NO is unstable, ENaC activity was reassessed in split‐open IMCD with the NO donor, PAPA NONOate, and now found to be almost completely abolished in UT‐A1/A3 KO. In summary, loss of both UT‐A1 and UT‐A3 (but not UT‐A3 alone) cause a salt‐wasting phenotype and an elevation in medullary NO production. NO inhibition of ENaC, despite elevated apical protein accumulation in UT‐A1/A3 KO IMCD, appears to be the main contributor to natriuresis in UT‐A1/A3 KO mice.

Molecular origin of urea driven hydrophobic polymer collapse and unfolding depending on side chain chemistry.

Osmolytes affect hydrophobic collapse and protein folding equilibria. The underlying mechanisms are, however, not well understood. We report large-scale conformational sampling of two hydrophobic polymers with secondary and tertiary amide side chains using extensive molecular dynamics simulations. The calculated free energy of unfolding increases with urea for the secondary amide, yet decreases for the tertiary amide, in agreement with experiment. The underlying mechanism is rooted in opposing entropic driving forces: while urea screens the hydrophobic macromolecular interface and drives unfolding of the tertiary amide, urea's concomitant loss in configurational entropy drives collapse of the secondary amide. Only at sufficiently high urea concentrations bivalent urea hydrogen bonding interactions with the secondary amide lead to further stabilisation of its collapsed state. The observations provide a new angle on the interplay between side chain chemistry, urea hydrogen bonding, and the role of urea in attenuating or strengthening the hydrophobic effect.

ChemInform Abstract: Divergent Roles of Urea and Phosphoric Acid Derived Catalysts in Reactions of Diazo Compounds.

Hydrogen-bond-donor catalysts enable a variety of formal insertion reactions of diazo compounds. The role of the catalyst in the reaction system may vary depending on several factors, including the nucleophilicity of the diazo compound and the acidity of the insertion partner. Ureas and phosphoric acid derivatives can offer complementary reactivity patterns when selected as catalysts for selected O–H and S–H insertion reactions of aryl- and diazo-substituted esters.

Dissolution of chitin in aqueous KOH

Our NMR experiments show that chitin can dissolve well in aqueous KOH through a freeze-thawing process, and the dissolution power of the alkali solvent systems is in the order of KOH > NaOH > LiOH aqueous solution, which is totally contrary to that of cellulose in the alkali aqueous solution (i.e., LiOH > NaOH ≫ KOH). In this work, we systematically study the dissolution process in KOH and KOH/urea aqueous solutions. Chitin has good solubility (solubility ~80 %) in 8.4–25 wt% KOH aqueous solution at −30 °C. The role of urea also has been investigated: unlike aqueous chitin-NaOH solutions, urea indeed enhances the solubility of chitin in KOH aqueous solutions, but the increased degree becomes unobtrusive with decreasing temperature and increasing dissolution time; the DA decline curves of chitin-KOH and chitin-KOH/urea aqueous solutions are nearly overlapping, indicating that the effect of the urea on the degree of acetylation of chitin in KOH aqueous solutions is small, similar to the NaOH/urea solvent.

The Contribution of Selected Urinary Solutes to the Determination of Urinary Osmolality in Guatemalan Preschool Children Consuming a Common Menu Offering

Background: Although water is the most abundant and most vital of all human nutrients, hydration is among the most ignored aspects of human nutrition. Many different solutes are eliminated by the kidneys in the urine flow, potentially contributing to the osmotic charge of this body fluid and acting as determinants of the urinary osmolality [Uosm]. Objectives: To measure urine osmolality concurrently with urea, uric acid, calcium, magnesium, potassium, sodium and inorganic phosphorus in a 24 h sample and to determine the patterns of their mutual interactions towards assessing the primary determinants of Uosm. Methods: Seventy-eight children from 2 to 7 years old, 40 girls and 38 boys, with median age of 57 mo underwent 24 h urine collections, with an aliquot separated for measuring urine osmolality by freezing-point-depression osmometry and solute concentrations by various analytical chemistry techniques. Spearman correlations and multiple regression models were run to assess interactions. Results: Backward-elimination multiple-regression models found that the urinary concentrations of inorganic phosphorus, urea, sodium, potassium and magnesium explained 95.1% of the variance in Uosm among the seven analytes quantified; calcium and uric acid made negligible contribution. Conclusion: The analyses allowed us to confirm the determinant roles of urea and the principal electrolytes, sodium and potassium, for urine osmolality and to appreciate coordination in the collateral collinear associations with other excreted solutes.

Isolation and functional characterization of a high affinity urea transporter from roots of Zea mays.

BackgroundDespite its extensive use as a nitrogen fertilizer, the role of urea as a directly accessible nitrogen source for crop plants is still poorly understood. So far, the physiological and molecular aspects of urea acquisition have been investigated only in few plant species highlighting the importance of a high-affinity transport system. With respect to maize, a worldwide-cultivated crop requiring high amounts of nitrogen fertilizer, the mechanisms involved in the transport of urea have not yet been identified. The aim of the present work was to characterize the high-affinity urea transport system in maize roots and to identify the high affinity urea transporter.ResultsKinetic characterization of urea uptake (<300 μM) demonstrated the presence in maize roots of a high-affinity and saturable transport system; this system is inducible by urea itself showing higher Vmax and Km upon induction. At molecular level, the ORF sequence coding for the urea transporter, ZmDUR3, was isolated and functionally characterized using different heterologous systems: a dur3 yeast mutant strain, tobacco protoplasts and a dur3 Arabidopsis mutant. The expression of the isolated sequence, ZmDUR3-ORF, in dur3 yeast mutant demonstrated the ability of the encoded protein to mediate urea uptake into cells. The subcellular targeting of DUR3/GFP fusion proteins in tobacco protoplasts gave results comparable to the localization of the orthologous transporters of Arabidopsis and rice, suggesting a partial localization at the plasma membrane. Moreover, the overexpression of ZmDUR3 in the atdur3-3 Arabidopsis mutant showed to complement the phenotype, since different ZmDUR3-overexpressing lines showed either comparable or enhanced 15[N]-urea influx than wild-type plants. These data provide a clear evidence in planta for a role of ZmDUR3 in urea acquisition from an extra-radical solution.ConclusionsThis work highlights the capability of maize plants to take up urea via an inducible and high-affinity transport system. ZmDUR3 is a high-affinity urea transporter mediating the uptake of this molecule into roots. Data may provide a key to better understand the mechanisms involved in urea acquisition and contribute to deepen the knowledge on the overall nitrogen-use efficiency in crop plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0222-6) contains supplementary material, which is available to authorized users.

Role of urea on recombinant Apo A-I stability and its utilization in anion exchange chromatography

Apolipoprotein A-I (Apo A-I) is an important lipid-binding protein involved in the transport and metabolism of cholesterol. High protein purity, in particular with respect to endotoxins is required for therapeutic applications. The use of urea during the purification process of recombinant Apo A-I produced in Escherichia coli has been suggested so as to provide high endotoxin clearance. In this work, we show that urea can be used as a sole modifier during the ion exchange chromatographic purification of Apo A-I and we investigate the molecular mechanism of elution by correlating the effect of urea on self-association, conformation and adsorption equilibrium properties of a modified model Apo A-I.In the absence of urea the protein was found to be present as a population of oligomers represented mainly by trimers, hexamers and nonamers. The addition of urea induced oligomer dissociation and protein structure unfolding. We correlated the changes in protein association and conformation with variations of the adsorption equilibrium of the protein on a strong anion exchanger. It was confirmed that the adsorption isotherms, described by a Langmuir model, were dependent on both protein and urea concentrations. Monomers, observed at low urea concentration (0.5M), were characterized by larger binding affinity and adsorption capacity compared to both protein oligomers (0M) and unfolded monomers (2–8M). The reduction of both the binding strength and maximum adsorption capacity at urea concentrations larger than 0.5M explains the ability of urea of inducing elution of the protein from the ion exchange resin. The dissociation of the protein complexes occurring during the elution could likely be the origin of the effective clearance of endotoxins originally trapped inside the oligomers.

Inclusion of urea in a 59FeEDTA solution stimulated leaf penetration and translocation of 59Fe within wheat plants

The role of urea in the translocation of (59) Fe from (59) FeEDTA-treated leaves was studied in durum wheat (Triticum durum) grown for 2 weeks in nutrient solution and until grain maturation in soil culture. Five-cm long tips of the first leaf of young wheat seedlings or flag leaves at the early milk stage were immersed twice daily for 10 s in (59) FeEDTA solutions containing increasing amounts of urea (0, 0.2, 0.4 and 0.8% w/v) over 5 days. In the experiment with young wheat seedlings, urea inclusion in the (59) FeEDTA solution increased significantly translocation of (59) Fe from the treated leaf into roots and the untreated part of shoots. When (59) Fe-treated leaves were induced into senescence by keeping them in the dark, there was a strong (59) Fe translocation from these leaves. Adding urea to the (59) Fe solution did not result in an additional increase in Fe translocation from the dark-induced senescent leaves. In the experiment conducted in the greenhouse in soil culture until grain maturation, translocation of (59) Fe from the flag leaves into grains was also strongly promoted by urea, whereas (59) Fe translocation from flag leaves into the untreated shoot was low and not affected by urea. In conclusion, urea contributes to transportation of the leaf-absorbed Fe into sink organs. Probably, nitrogen compounds formed after assimilation of foliar-applied urea (such as amino acids) contributed to Fe chelation and translocation to grains in wheat.

Ionic Liquid Promoted Synthesis of Conjugated Carbon Nitride Photocatalysts from Urea

To allow for simultaneous textural engineering and doping of carbon nitride materials with heteroatoms, urea has been polymerized with an ionic liquid. The role of urea is to create a delamination effect during carbon nitride synthesis, whereas ionic liquid functions as texture modifier as well as B/F dopant source. This will result in the rational fabrication of boron- and fluorine-containing 2D carbon nitride nanosheets with enhanced optical harvesting and charge separation capabilities for hydrogen evolution catalysis using visible light. We believe that the innovative modification strategy developed herein can be coupled with the already known modification tools of 2D carbon nitride, thus further developing a new family of light-harvesting 2D platforms for the efficient and sustained utilization of solar radiation for a variety of advanced applications, including CO2 photofixation, organic photosynthesis, and pollutant controls.

The effect of urea in the nucleation process of CO2 clathrate hydrates

The role of urea in the promotion and stability of CO2 clathrate hydrates in the context of nucleation was investigated through isothermal–isobaric molecular dynamics simulations. A comparison of structural and dynamic properties was made for aqueous solutions of CO2 interstitial to model montmorillonite surfaces in the presence and absence of urea. The results showed that meta-stable amorphous hydrates associated through proximity interact through cross-relaxation of H-bonds. Urea appears to mediate this effect by functioning as a bridge for thermal fluctuations of H-bond networks between nearby CO2 hydrates. The implications have significant bearing in the modification of solution properties for the enhancement of clathrate hydrate formation in geologic and aquatic sediments through the control and stabilization of nucleation using organic matter.

Potential Application of Urea and NPK 15:15:15 Fertilizers as Biostimulants in the Bioremediation of Domestic Wastewater

The role of urea and NPK 15:15:15 fertilisers as biostimulants of microbes in the bioremediation of domestic wastewater was investigated in this study. Five samples of domestic wastewater supplemented with 10, 20, 40, 60 and 80 g/L of urea, NPK as well as a combination of both fertilisers and the control were monitored for bioremediation. The indicating parameters such as pH, Biochemical Oxygen Demand (BOD), and Dissolved Oxygen (DO) over a period of 5 weeks were used. The results obtained showed that there was a BOD reduction of 86.62, 85.24 and 86.85% for wastewater treated with urea, NPK and a combination of both respectively. Stimulation by the fertilisers improved the DO level by 76, 75 and 77.8% respectively for wastewater treated with urea, NPK and a combination of both respectively. Generally, the best results were obtained when both fertilisers were used together. The final values of pH, BOD and DO fell within the values of 6-9, 30 mg/L and 2 mg/L set by the Federal Environmental Protection Agency (FEPA). The results obtained indicate the effective use of urea and NPK fertilisers in stimulating the activity of microbes for bioremediation in wastewater.

Synthesis of AlN – presence and absence of additive

Direct nitridation of hexagonal aluminium nitride (AlN), using additive like NH4Cl, was performed from Al metal powder. Different methods of AlN synthesis, viz. a) Al powder, b) Al and NH4Cl, c) Al and NH4Cl with urea, were carried out in continuous flowing of N2 gas at 900 °C for 5 h. The synthesized powder was characterized by employing TGA/DTA, XRD, FTIR, SEM, UV- VIS Spectroscopy and CHNS analysis. The mechanism for the formation of AlN by the influence of additive and role of urea are discussed.