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Sample records for acid-activated urea transporter

  1. Urea transporters and sweat response to uremia.

    Keller, Raymond W; Bailey, James L; Wang, Yanhua; Klein, Janet D; Sands, Jeff M

    2016-06-01

    In humans, urea is excreted in sweat, largely through the eccrine sweat gland. The urea concentration in human sweat is elevated when compared to blood urea nitrogen. The sweat urea nitrogen (UN) of patients with end-stage kidney disease (ESRD) is increased when compared with healthy humans. The ability to produce sweat is maintained in the overwhelming majority of ESRD patients. A comprehensive literature review found no reports of sweat UN neither in healthy rodents nor in rodent models of chronic kidney disease (CKD). Therefore, this study measured sweat UN concentrations in healthy and uremic rats. Uninephrectomy followed by renal artery ligation was used to remove 5/6 of renal function. Rats were then fed a high-protein diet to induce uremia. Pilocarpine was used to induce sweating. Sweat droplets were collected under oil. Sweat UN was measured with a urease assay. Serum UN was measured using a fluorescent ortho-pthalaldehyde reaction. Immunohistochemistry (IHC) was accomplished with a horseradish peroxidase and diaminobenzidine technique. Sweat UN in uremic rats was elevated greater than two times compared to healthy pair-fed controls (220 ± 17 and 91 ± 15 mmol/L, respectively). Post hoc analysis showed a significant difference between male and female uremic sweat UN (279 ± 38 and 177 ± 11 mmol/L, respectively.) IHC shows, for the first time, the presence of the urea transporters UT-B and UT-A2 in both healthy and uremic rat cutaneous structures. Future studies will use this model to elucidate how rat sweat UN and other solute excretion is altered by commonly prescribed diuretics. PMID:27273880

  2. UREA TRANSPORT DURING GAMETOGENESIS OF THE UNICELLULAR GREEN ALGA CHLAMYDOMONAS REINHARDTII

    Zalutskaya, Zhanneta; Lapina, Tatyana; Von, Wiren; Ermilova, Elena

    2009-01-01

    Direct urea transport mechanisms are present in Chlamydomonas reinhardtii. Urea uptake system(s) are repressed by ammonium and they can be induced by urea or acetamide in ammonium-starved vegetative cells. Urea transport ability of the alga is altered during gametogenesis. Unlike vegetative cells, mature gametes showed a low urea uptake. Incubation of gametes with urea or acetamide resulted in the increasing of urea uptake ability and the regaining of chemotactic activity. The data suggest a ...

  3. Developing Hypothetical Inhibition Mechanism of Novel Urea Transporter B Inhibitor

    Li, Min; Tou, Weng Ieong; Zhou, Hong; Li, Fei; Ren, Huiwen; Chen, Calvin Yu-Chian; Yang, Baoxue

    2014-07-01

    Urea transporter B (UT-B) is a membrane channel protein that specifically transports urea. UT-B null mouse exhibited urea selective urine concentrating ability deficiency, which suggests the potential clinical applications of the UT-B inhibitors as novel diuretics. Primary high-throughput virtual screening (HTVS) of 50000 small-molecular drug-like compounds identified 2319 hit compounds. These 2319 compounds were screened by high-throughput screening using an erythrocyte osmotic lysis assay. Based on the pharmacological data, putative UT-B binding sites were identified by structure-based drug design and validated by ligand-based and QSAR model. Additionally, UT-B structural and functional characteristics under inhibitors treated and untreated conditions were simulated by molecular dynamics (MD). As the result, we identified four classes of compounds with UT-B inhibitory activity and predicted a human UT-B model, based on which computative binding sites were identified and validated. A novel potential mechanism of UT-B inhibitory activity was discovered by comparing UT-B from different species. Results suggest residue PHE198 in rat and mouse UT-B might block the inhibitor migration pathway. Inhibitory mechanisms of UT-B inhibitors and the functions of key residues in UT-B were proposed. The binding site analysis provides a structural basis for lead identification and optimization of UT-B inhibitors.

  4. An evaluation of twelve nested models of transperitoneal transport of urea

    Graff, J; Fugleberg, S; Joffe, P;

    1995-01-01

    Models of transperitoneal urea transport are generally based on the one-compartment assumption, i.e. that the plasma water urea concentration in the peritoneal capillary bed is equal to the plasma water urea concentration in the peripheral veins. The aim of this study was to investigate the mecha...

  5. Influence of glucose and urea on 125I transport across an anion exchange paper membrane

    In order to study the influence of glucose and urea on the 125I transport across an anion exchange paper membrane, the transmembrane potential, the fluxes, and the concentrations of 125I, glucose and urea within the membrane were measured in the Na125I concentration-cell system containing glucose or urea. Glucose and urea increased the membrane/solution distribution of the iodide ion, but scarcely affected the diffusion process of iodide ion within the membrane

  6. Active urea transport by the skin of Bufo viridis: Amiloride- and phloretin-sensitive transport sites

    Urea is actively transported inwardly (Ji) across the skin of the green toad Bufo viridis. Ji is markedly enhanced in toads adapted to hypertonic saline. The authors studied urea transport across the skin of Bufo viridis under a variety of experimental conditions, including treatment with amiloride and phloretin, agents that inhibit urea permeability in the bladder of Bufo marinus. Amiloride (10-4 M) significantly inhibited Ji in both adapted and unadapted animals and was unaffected by removal of sodium from the external medium. Phloretin (10-4 M) significantly inhibited Ji in adapted animals by 23-46%; there was also a reduction in Ji in unadapted toads at 10-4 and 5 x 10-4 M phloretin. A dose-response study revealed that the concentration of phloretin causing half-maximal inhibition (K1/2) was 5 x 10-4 M for adapted animals. Ji was unaffected by the substitution of sucrose for Ringer solution or by ouabain. They conclude (1) the process of adaptation appears to involve an increase in the number of amiloride- and phloretin-inhibitable urea transport sites in the skin, with a possible increase in the affinity of the sites for phloretin; (2) the adapted skin resembles the Bufo marinus urinary bladder with respect to amiloride and phloretin-inhibitable sites; (3) they confirm earlier observations that Ji is independent of sodium transport

  7. The urease inhibitor acetohydroxamic acid is transported by the urea pathway in rat terminal IMCD.

    Star, R A; Gillin, A D; Parikh, V J; Sands, J M

    1993-09-01

    Acetohydroxamic acid (AHA), a urea analogue, is used clinically to dissolve struvite stones because it inhibits the urease produced by Proteus mirabilis. To be effective, the concentration of AHA must be high in the collecting duct system and final urine. Because AHA is structurally similar to urea, we investigated whether AHA is transported by the urea carrier found in the terminal inner medullary collecting duct (IMCD) and the erythrocyte. We examined AHA transport under four conditions known to affect urea movement across the terminal IMCD, i.e., stimulation by vasopressin (AVP) and hyperosmolality, and inhibition by phloretin and urea analogues. The AHA permeability was determined with a 10 mM bath-to-lumen AHA gradient. AHA was measured by ultramicrocolorimetry. Addition of 1 nM AVP to the bath increased the AHA permeability of the perfused terminal IMCD. Increasing perfusate and bath osmolality from 290 to 690 mosmol/kgH2O (by adding NaCl) also increased tubule permeability to AHA. Addition of either 0.25 mM phloretin to the bath or 200 mM thiourea to the lumen reversibly inhibited the AVP-stimulated AHA permeability. AHA-induced osmotic lysis of erythrocytes was inhibited by phloretin or thionicotinamide; AHA inhibited the osmotic lysis induced by the urea analogue acetamide. Thus, in the rat terminal IMCD, both urea and AHA transport are stimulated by AVP and hyperosmolality, and both are inhibited by phloretin and thiourea. In erythrocytes, both urea and AHA transport are inhibited by phloretin or thionicotinamide. Thus AHA is transported by the urea carrier in the terminal IMCD and erythrocyte.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8214097

  8. Radiation inactivation studies of renal brush border water and urea transport

    Radiation inactivation was used to determine the nature and molecular weight of water and urea transport pathways in brush border membrane vesicles (BBMV) isolated from rabbit renal cortex. BBMV were frozen to -50 degrees C, irradiated with 1.5 MeV electrons, thawed, and assayed for transport or enzyme activity. The freezing process had no effect on enzyme or transport kinetics. BBMV alkaline phosphatase activity gave linear ln(activity) vs. radiation dose plots with a target size of 68 +/- 3 kDa, similar to previously reported values. Water and solute transport were measured using the stopped-flow light-scattering technique. The rates of acetamide and osmotic water transport did not depend on radiation dose (0-7 Mrad), suggesting that transport of these substances does not require a protein carrier. In contrast, urea and thiourea transport gave linear ln(activity) vs. dose curves with a target size of 125-150 kDa; 400 mM urea inhibited thiourea flux by -50% at 0 and 4.7 Mrad, showing that radiation does not affect inhibitor binding to surviving transporters. These studies suggest that BBMV urea transport requires a membrane protein, whereas osmotic water transport does not

  9. Modelling and mutational analysis of Aspergillus nidulans UreA, a member of the subfamily of urea/H+ transporters in fungi and plants

    Sanguinetti, Manuel; Amillis, Sotiris; Pantano, Sergio; Scazzocchio, Claudio; Ramón, Ana

    2014-01-01

    We present the first account of the structure–function relationships of a protein of the subfamily of urea/H+ membrane transporters of fungi and plants, using Aspergillus nidulans UreA as a study model. Based on the crystal structures of the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT) and of the Nucleobase-Cation-Symport-1 benzylhydantoin transporter from Microbacterium liquefaciens (Mhp1), we constructed a three-dimensional model of UreA which, combined with site-directed and ...

  10. Mechanisms of molecular transport through the urea channel of Helicobacter pylori

    McNulty, Reginald; Ulmschneider, Jakob P.; Luecke, Hartmut; Ulmschneider, Martin B.

    2013-12-01

    Helicobacter pylori survival in acidic environments relies on cytoplasmic hydrolysis of gastric urea into ammonia and carbon dioxide, which buffer the pathogen’s periplasm. Urea uptake is greatly enhanced and regulated by HpUreI, a proton-gated inner membrane channel protein essential for gastric survival of H. pylori. The crystal structure of HpUreI describes a static snapshot of the channel with two constriction sites near the center of the bilayer that are too narrow to allow passage of urea or even water. Here we describe the urea transport mechanism at atomic resolution, revealed by unrestrained microsecond equilibrium molecular dynamics simulations of the hexameric channel assembly. Two consecutive constrictions open to allow conduction of urea, which is guided through the channel by interplay between conserved residues that determine proton rejection and solute selectivity. Remarkably, HpUreI conducts water at rates equivalent to aquaporins, which might be essential for efficient transport of urea at small concentration gradients.

  11. Effect of nitrogen intake on nitrogen recycling and urea transporter abundance in lambs.

    Marini, J C; Klein, J D; Sands, J M; Van Amburgh, M E

    2004-04-01

    Urea recycling in ruminants has been studied extensively in the past, but the mechanisms regulating the amount of urea recycled or excreted remain obscure. To elucidate the role of urea transporters (UT) in N recycling, nine Dorset-Finn ewe lambs (20.8 +/- 0.8 kg) were fed diets containing 15.5, 28.4, and 41.3 g of N/kg of DM for 25 d. Nitrogen balance and urea N kinetics were measured during the last 3 d of the period. Animals were then slaughtered and mucosa samples from the rumen, duodenum, ileum, and cecum, as well as kidney medulla and liver, were collected. Increasing N intake tended to increase N balance quadratically (1.5, 5.1, and 4.4 +/- 0.86 g of N/d, P 2.62 mg of urea N/dL, P creatinine excretion (518 +/- 82.4 mg/d; P level of N intake increased linearly the weight of the liver as a proportion of BW (1.73, 1.88, and 2.22 +/- 0.15%, P 0.10) in UT abundance, quantified by densitometry, were found. Ruminal-wall urease activity decreased linearly (P level of N intake. Urease activity in duodenal, ileal, and cecal mucosa did not differ from zero (P > 0.10) in lambs on the high-protein diet. In the present experiment, urea transporter abundance in the kidney medulla and the gastrointestinal tract did not reflect the increase in urea-N reabsorption by the kidney and transferred into the gut. PMID:15080338

  12. Movement of NH₃ through the human urea transporter B: a new gas channel.

    Geyer, R Ryan; Musa-Aziz, Raif; Enkavi, Giray; Mahinthichaichan, P; Tajkhorshid, Emad; Boron, Walter F

    2013-06-15

    Aquaporins and Rh proteins can function as gas (CO₂ and NH₃) channels. The present study explores the urea, H₂O, CO₂, and NH₃ permeability of the human urea transporter B (UT-B) (SLC14A1), expressed in Xenopus oocytes. We monitored urea uptake using [¹⁴C]urea and measured osmotic water permeability (Pf) using video microscopy. To obtain a semiquantitative measure of gas permeability, we used microelectrodes to record the maximum transient change in surface pH (ΔpHS) caused by exposing oocytes to 5% CO₂/33 mM HCO₃⁻ (pHS increase) or 0.5 mM NH₃/NH₄⁺ (pHS decrease). UT-B expression increased oocyte permeability to urea by >20-fold, and Pf by 8-fold vs. H₂O-injected control oocytes. UT-B expression had no effect on the CO₂-induced ΔpHS but doubled the NH₃-induced ΔpHS. Phloretin reduced UT-B-dependent urea uptake (Jurea*) by 45%, Pf* by 50%, and (- ΔpHS*)NH₃ by 70%. p-Chloromercuribenzene sulfonate reduced Jurea* by 25%, Pf* by 30%, and (ΔpHS*)NH₃ by 100%. Molecular dynamics (MD) simulations of membrane-embedded models of UT-B identified the monomeric UT-B pores as the main conduction pathway for both H₂O and NH₃ and characterized the energetics associated with permeation of these species through the channel. Mutating each of two conserved threonines lining the monomeric urea pores reduced H₂O and NH₃ permeability. Our data confirm that UT-B has significant H₂O permeability and for the first time demonstrate significant NH₃ permeability. Thus the UTs become the third family of gas channels. Inhibitor and mutagenesis studies and results of MD simulations suggest that NH₃ and H₂O pass through the three monomeric urea channels in UT-B. PMID:23552862

  13. Energetic and molecular water permeation mechanisms of the human red blood cell urea transporter B.

    Slim Azouzi

    Full Text Available Urea transporter B (UT-B is a passive membrane channel that facilitates highly efficient permeation of urea. In red blood cells (RBC, while the major function of UT-B is to transport urea, it is assumed that this protein is able to conduct water. Here, we have revisited this last issue by studying RBCs and ghosts from human variants with defects of aquaporin 1 (AQP1 or UT-B. We found that UT-B's osmotic water unit permeability (pfunit is similar to that of AQP1. The determination of diffusional permeability coefficient (Pd allowed the calculation of the Pf/Pd ratio, which is consistent with a single-file water transport. Molecular dynamic simulations of water conduction through human UT-B confirmed the experimental finding. From these results, we propose an atomistic description of water-protein interactions involved in this permeation. Inside the UT-B pore, five water molecules were found to form a single-file and move rapidly along a channel by hydrogen bond exchange involving two critical threonines. We further show that the energy barrier for water located in the central region coincides with a water dipole reorientation, which can be related to the proton exclusion observed experimentally. In conclusion, our results indicate that UT-B should be considered as a new member of the water channel family.

  14. Metformin, an AMPK activator, stimulates the phosphorylation of aquaporin 2 and urea transporter A1 in inner medullary collecting ducts.

    Klein, Janet D; Wang, Yanhua; Blount, Mitsi A; Molina, Patrick A; LaRocque, Lauren M; Ruiz, Joseph A; Sands, Jeff M

    2016-05-15

    Nephrogenic diabetes insipidus (NDI) is characterized by production of very large quantities of dilute urine due to an inability of the kidney to respond to vasopressin. Congenital NDI results from mutations in the type 2 vasopressin receptor (V2R) in ∼90% of families. These patients do not have mutations in aquaporin-2 (AQP2) or urea transporter UT-A1 (UT-A1). We tested adenosine monophosphate kinase (AMPK) since it is known to phosphorylate another vasopressin-sensitive transporter, NKCC2 (Na-K-2Cl cotransporter). We found AMPK expressed in rat inner medulla (IM). AMPK directly phosphorylated AQP2 and UT-A1 in vitro. Metformin, an AMPK activator, increased phosphorylation of both AQP2 and UT-A1 in rat inner medullary collecting ducts (IMCDs). Metformin increased the apical plasma membrane accumulation of AQP2, but not UT-A1, in rat IM. Metformin increased both osmotic water permeability and urea permeability in perfused rat terminal IMCDs. These findings suggest that metformin increases osmotic water permeability by increasing AQP2 accumulation in the apical plasma membrane but increases urea permeability by activating UT-A1 already present in the membrane. Lastly, metformin increased urine osmolality in mice lacking a V2R, a mouse model of congenital NDI. We conclude that AMPK activation by metformin mimics many of the mechanisms by which vasopressin increases urine-concentrating ability. These findings suggest that metformin may be a novel therapeutic option for congenital NDI due to V2R mutations. PMID:26962099

  15. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    MENG Yan; ZHAO ChunYan; ZHANG XueXin; ZHAO HuaShan; GUO LiRong; Lü Bin; ZHAO XueJian; YANG BaoXue

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead Ⅱ) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by float-ing microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5±4.2), (45.5±6.9) and (43.8±7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6±2.9), (38.7±5.6) and (38.2±7.3) ms, P<0.05). The atrial ventricular heart block type Ⅱ and Ⅲ only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17±10.56) and (101.89±9.54) mV/s) vs those in wild-type mice (vs (110.51±10.38) and (109.53±10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83±11.17) and (195.43±16.41) ms) vs that in wild-type mice ((108.27±10.85) and (171.00±15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80±0.92) nA vs that in wild-type mice ((-5.98±1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  16. Surface electrocardiogram and action potential in mice lacking urea transporter UT-B

    2009-01-01

    UT-B is a urea transporter protein expressed in the kidney and in many non-renal tissues including erythrocytes, brain, heart, bladder and the testis. The objective of this study was to determine the phenotype of UT-B deletion in the heart. UT-B expression in the heart was studied in wild-type mice vs UT-B null mice by utilizing RT-PCR and Western blot. A surface electrocardiogram (ECG) recording (lead II) was measured in wild-type mice and UT-B null mice at the ages of 6, 16 and 52 weeks. For the action potential recording, the ventricular myocytes of 16 w mice were isolated and recorded by floating microelectrode method. The sodium current was recorded by the patch clamp technique. RT-PCR and Western blot showed the UT-B expression in the heart of wild-type mice. No UT-B transcript and protein was found in UT-B null mice. The ECG recording showed that the P-R interval was significantly prolonged in UT-B null mice ((43.5 ± 4.2), (45.5 ± 6.9) and (43.8 ± 7.6) ms at ages of 6, 16 and 52 weeks) vs wild-type mice ((38.6 ± 2.9), (38.7 ± 5.6) and (38.2 ± 7.3) ms, P<0.05). The atrial ventricular heart block type II and III only appeared in the aging UT-B null mice (52 w old). The amplitude of action potential and Vmax decreased significantly in UT-B null mice ((92.17 ± 10.56) and (101.89 ± 9.54) mV/s) vs those in wild-type mice (vs (110.51 ± 10.38) and (109.53 ± 10.64) mV/s, P<0.05). The action potential duration at 50% and 90% (APD50 and APD90) was significantly prolonged in UT-B null mice ((123.83 ± 11.17) and (195.43 ± 16.41) ms) vs that in wild-type mice ((108.27 ± 10.85) and (171.00 ± 15.53) ms, P<0.05). The maximal sodium current decreased significantly in UT-B null mice (-8.80 ± 0.92) nA vs that in wild-type mice ((-5.98 ± 1.07) nA, P<0.05). These results provide the first evidence that UT-B deletion causes progressive heart block in mice.

  17. Protein abundance of urea transporters and aquaporin 2 change differently in nephrotic pair-fed vs. non-pair-fed rats

    Bou Matar, Raed N.; Malik, Bela; Wang, Xiaonan H.; Martin, Christopher F; Eaton, Douglas C.; Sands, Jeff M.; Klein, Janet D.

    2012-01-01

    Salt and water retention is a hallmark of nephrotic syndrome (NS). In this study, we test for changes in the abundance of urea transporters, aquaporin 2 (AQP2), Na-K-2Cl cotransporter 2 (NKCC2), and Na-Cl cotransporter (NCC), in non-pair-fed and pair-fed nephrotic animals. Doxorubicin-injected male Sprague-Dawley rats (n = 10) were followed in metabolism cages. Urinary excretion of protein, sodium, and urea was measured periodically. Kidney inner medulla (IM), outer medulla, and cortex tissue...

  18. Sistemas de transporte de aminoácidos, amonio y urea en cianobacterias

    Montesinos Gutiérrez, María Luz

    1997-01-01

    Al finalizar esta Tesis Doctoral, hemos sacado las siguientes conclusiones: 1. Las Cianobacterias son capaces de transportar un amplio rango de aminoácidos mediante un bajo número de sistemas de transporte que muestran, en general, baja especificidad de sustrato. Todas las estirpes estudiadas poseen, al menos, un sistema de transporte de aminoácidos neutros. 2. El sistema de transporte de aminoácidos neutros de Synechocystis sp. PCC 6803 y uno de los presentes en Anabaena sp. PCC 7120 son ...

  19. An in vitro study of urea, water, ion and CO2/HCO3- transport in the gastrointestinal tract of the dogfish shark (Squalus acanthias): the influence of feeding.

    Liew, Hon Jung; De Boeck, Gudrun; Wood, Chris M

    2013-06-01

    In vitro gut sac preparations made from the cardiac stomach (stomach 1), pyloric stomach (stomach 2), intestine (spiral valve) and colon were used to examine the impact of feeding on transport processes in the gastrointestinal tract of the dogfish shark. Preparations were made from animals that were euthanized after 1-2 weeks of fasting, or at 24-48 h after voluntary feeding on a 3% ration of teleost fish (hake). Sacs were incubated under initially symmetrical conditions with dogfish saline on both surfaces. In comparison to an earlier in vivo study, the results confirmed that feeding caused increases in H(+) secretion in both stomach sections, but an increase in Cl(-) secretion only in stomach 2. Na(+) absorption, rather than Na(+) secretion, occurred in both stomach sections after feeding. All sections of the tract absorbed water and the intestine strongly absorbed Na(+) and Cl(-), regardless of feeding condition. The results also confirmed that feeding increased water absorption in the intestine (but not in the colon), and had little influence on the handling of Ca(2+) and Mg(2+), which exhibited negligible absorption across the tract. However, K(+) was secreted in the intestine in both fasted and fed preparations. Increased intestinal water absorption occurred despite net osmolyte secretion into the mucosal saline. The largest changes occurred in urea and CO2/HCO3(-) fluxes. In fasted preparations, urea was absorbed at a low rate in all sections except the intestine, where it was secreted. Instead of an increase in intestinal urea secretion predicted from in vivo data, feeding caused a marked switch to net urea absorption. This intestinal urea transport occurred at a rate comparable to urea reabsorption rates reported at gills and kidney, and was apparently active, establishing a large serosal-to-mucosal concentration gradient. Feeding also greatly increased intestinal CO2/HCO3(-) secretion; if interpreted as HCO3(-) transport, the rates were in the upper range

  20. Clinical aspects of urea cycle dysfunction and altered brain energy metabolism on modulation of glutamate receptors and transporters in acute and chronic hyperammonemia.

    Natesan, Vijayakumar; Mani, Renuka; Arumugam, Ramakrishnan

    2016-07-01

    In living organisms, nitrogen arise primarily as ammonia (NH3) and ammonium (NH4(+)), which is a main component of the nucleic acid pool and proteins. Although nitrogen is essential for growth and maintenance in animals, but when the nitrogenous compounds exceeds the normal range which can quickly lead to toxicity and death. Urea cycle is the common pathway for the disposal of excess nitrogen through urea biosynthesis. Hyperammonemia is a consistent finding in many neurological disorders including congenital urea cycle disorders, reye's syndrome and acute liver failure leads to deleterious effects. Hyperammonemia and liver failure results in glutamatergic neurotransmission which contributes to the alteration in the function of the glutamate-nitric oxide-cGMP pathway, modulates the important cerebral process. Even though ammonia is essential for normal functioning of the central nervous system (CNS), in particular high concentrations of ammonia exposure to the brain leads to the alterations of glutamate transport by the transporters. Several glutamate transporters have been recognized in the central nervous system and each has a unique physiological property and distribution. The loss of glutamate transporter activity in brain during acute liver failure and hyperammonemia is allied with increased extracellular brain glutamate concentrations which may be conscientious for the cerebral edema and ultimately cell death. PMID:27261594

  1. Isolation and characterization of three maize aquaporin genes, ZmNIP2;1, ZmNIP2;4 and ZmTIP4;4 involved in urea transport

    Riliang Gu; Xiaoling Chen; Yuling Zhou; Lixing Yuan

    2012-01-01

    Urea-based nitrogen fertilizer was widely utilized in maizeproduction, but transporters involved in urea uptake, translocationand cellular homeostasis have not been identified.Here, we isolated three maize aquapoin genes, ZmNIP2;1,ZmNIP2;4 and ZmTIP4;4, from a cDNA library by heterogouscomplementation of a urea uptake-defective yeast. ZmNIP2;1and ZmNIP2;4 belonged to the nodulin 26-like intrinsic proteins(NIPs) localized at plasma membrane, and ZmTIP4;4 belongedto the tonoplast intrinsic prot...

  2. Isolation and characterization of three maize aquaporin genes, ZmNIP2;1, ZmNIP2;4 and ZmTIP4;4 involved in urea transport.

    Gu, Riliang; Chen, Xiaoling; Zhou, Yuling; Yuan, Lixing

    2012-02-01

    Urea-based nitrogen fertilizer was widely utilized in maize production, but transporters involved in urea uptake, translocation and cellular homeostasis have not been identified. Here, we isolated three maize aquapoin genes, ZmNIP2;1, ZmNIP2;4 and ZmTIP4;4, from a cDNA library by heterogeneous complementation of a urea uptake-defective yeast. ZmNIP2;1 and ZmNIP2;4 belonged to the nodulin 26-like intrinsic proteins (NIPs) localized at plasma membrane, and ZmTIP4;4 belonged to the tonoplast intrinsic protein (TIPs) at vacuolar membrane. Quantitative RT-PCR revealed that ZmNIP2;1 was expressed constitutively in various organs while ZmNIP2;4 and ZmTIP4;4 transcripts were abundant in reproductive organs and roots. Expression of ZmTIP4;4 was significantly increased in roots and expanded leaves under nitrogen starvation, while those of ZmNIP2;1 and ZmNIP2;4 remained unaffected. Functions of maize aquapoin genes in urea transport together with their distinct expression manners suggested that they might play diverse roles on urea uptake and translocation, or equilibrating urea concentration across tonoplast. PMID:22360887

  3. Isolation and characterization of three maize aquaporin genes, ZmNIP2;1, ZmNIP2;4 and ZmTIP4;4 involved in urea transport

    Riliang Gu

    2012-02-01

    Full Text Available Urea-based nitrogen fertilizer was widely utilized in maizeproduction, but transporters involved in urea uptake, translocationand cellular homeostasis have not been identified.Here, we isolated three maize aquapoin genes, ZmNIP2;1,ZmNIP2;4 and ZmTIP4;4, from a cDNA library by heterogouscomplementation of a urea uptake-defective yeast. ZmNIP2;1and ZmNIP2;4 belonged to the nodulin 26-like intrinsic proteins(NIPs localized at plasma membrane, and ZmTIP4;4 belongedto the tonoplast intrinsic protein (TIPs at vacuolarmembrane. Quantitative RT-PCR revealed that ZmNIP2;1 wasexpressed constitutively in various organs while ZmNIP2;4and ZmTIP4;4 transcripts were abundant in reproductive organsand roots. Expression of ZmTIP4;4 was significantly increasedin roots and expanded leaves under nitrogen starvation,while those of ZmNIP2;1 and ZmNIP2;4 remainedunaffected. Functions of maize aquapoin genes in urea transporttogether with their distinct expression manners suggestedthat they might play diverse roles on urea uptake and translocation,or equilibrating urea concentration across tonoplast.[BMB reports 2012; 45(2: 96-101

  4. H+, Water and Urea Transport in the Inner Medullary Collecting Duct and Their Role in the Prevention and Pathogenesis of Renal Stone Disease

    Wall, Susan M.; Klein, Janet D.

    2008-09-01

    The inner medullary collecting duct (IMCD) is the final site within the kidney for the reabsorption of urea, water and electrolytes and for the secretion of H+ before the luminal fluid becomes the final urine. Transporters expressed in the IMCD contribute to the generation of the large ion gradients that exist between the interstitium and the collecting duct lumen. Thus, the luminal fluid within the human IMCD can reach an osmolality of 1200 mOsm/kg H2O and a pH of 4. This ability of the human nephron to concentrate and acidify the urine might predispose to stone formation. However, under treatment conditions that predispose to stone formation, such as during hypercalciuria, the kidney mitigates stone formation by reducing solute concentration by reducing H2O reabsorption. Moreover, the kidney attenuates stone formation by tightly controlling acid-base balance, which prevents the bone loss, hypocitraturia and hypercalciuria observed during metabolic acidosis by augmenting net H+ excretion by tightly regulating H+ transporter function and through luminal buffering, particularly with NH3. This article will review the ion transporters present in the mammalian IMCD and their role in the prevention and in the pathogenesis of renal stone formation.

  5. Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)

    Summer, Heike; Grämer, René; Dröge, Peter

    2009-01-01

    Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their separation in a polyacrylamide gel matrix based on the molecular weight. Fragments between 2 to 500 bases, with length differences as small as a single nucleotide, can be separated using this method1. The migration of the sample is dependent on the chosen acrylamide concentration. A higher percentage of polyacrylamide resolves lower molecula...

  6. Ontogeny of rabbit proximal tubule urea permeability

    Quigley, Raymond; LISEC, AMBER; Baum, Michel

    2001-01-01

    Urea transport in the proximal tubule is passive and is dependent on the epithelial permeability. The present study examined the maturation of urea permeability (Purea) in in vitro perfused proximal convoluted tubules (PCT) and basolateral membrane vesicles (BLMV) from rabbit renal cortex. Urea transport was lower in neonatal than adult PCT at both 37 and 25°C. The PCT Purea was also lower in the neonates than the adults (37°C: 45.4 ± 10.8 vs. 88.5 ± 15.2 × 10−6 cm/s, P < 0.05; 25°C: 28.5 ± 6...

  7. Molecular evolution of urea amidolyase and urea carboxylase in fungi

    Harris Steven D; Nickerson Kenneth W; Strope Pooja K; Moriyama Etsuko N

    2011-01-01

    Abstract Background Urea amidolyase breaks down urea into ammonia and carbon dioxide in a two-step process, while another enzyme, urease, does this in a one step-process. Urea amidolyase has been found only in some fungal species among eukaryotes. It contains two major domains: the amidase and urea carboxylase domains. A shorter form of urea amidolyase is known as urea carboxylase and has no amidase domain. Eukaryotic urea carboxylase has been found only in several fungal species and green al...

  8. Urea metabolism in Barbari kids d on urea molasses diets

    The entry rates of urea into the body pool of urea were estimated in Barbari kids using a single injection isotope dilution technique using 14C-urea. The excretion rates of urea were calculated by estimating total urine output over 24 h and urea content. (M.G.B.)

  9. Living with urea stress

    Laishram R Singh; Tanveer Ali Dar; Faizan Ahmad

    2009-06-01

    Intracellular organic osmolytes are present in certain organisms adapted to harsh environments. These osmolytes protect intracellular macromolecules against denaturing environmental stress. In contrast to the usually benign effects of most organic osmolytes, the waste product urea is a well-known perturbant of macromolecules. Although urea is a perturbing solute which inhibits enzyme activity and stability, it is employed by some species as a major osmolyte. The answer to this paradox was believed to be the discovery of protective osmolytes (methylamines). We review the current state of knowledge on the various ways of counteracting the harmful effects of urea in nature and the mechanisms for this. This review ends with the mechanistic idea that cellular salt (KCl/NaCl) plays a crucial role in counteracting the effects of urea, either by inducing required chaperones or methylamines, or by thermodynamic interactions with urea-destabilised proteins. We also propose future opportunities and challenges in the field.

  10. Use of polyurea from urea for coating of urea granules

    Lu, Panfang; Zhang, Yanfei; Jia, Cong; Li, Yufeng; Mao, Zhiquan

    2016-01-01

    A new type of controlled release fertilizers coated with polyurea was prepared. The granulated urea was firstly changed into a liquid urea by heating as the coating liquid. By spraying uniformly the urea was coated with the polyurea synthesized by the reaction of isocyanates with a liquid urea. The effects of different modifiers on N release characteristics of polyurea-coated urea (PCU) were studied. The morphology and chemical structure of PCU coating materials was investigated by SEM and FT...

  11. Ethylated Urea - Ether - Modified Urea - Formaldehyde Resins,

    Mathew Obichukwu EDOGA

    2006-07-01

    Full Text Available First, phenol - formaldehyde (PF and urea - formaldehyde (UFII resins were separately conventionally prepared in our laboratory. Also, UF resin synthesized from the acid modified synthesis procedure was synthesized in a purely acid medium of pH 1.0, FU molar ratio of 1.0 and at 50oC (one-stage acid modified-synthesis procedure. Subsequently, the UF resin II was modified during synthesis by incorporating ethylated urea-ether (EUER (i.e. UFIII and glycerol (GLYC (i.e. UFV cured with and without acid curing agent. The structural and physicochemical analyses of the various resin samples were carried out.The results showed that the unmodified UF resin (UF II synthesized in acid medium of pH 1.0, F/U molar ratio 1.0, and at 50oC, cured in absence of acid curing catalyst, showed features in their spectra which are consistent with a tri-, and/or tetra-substituted urea in the reaction to give a 3 - dimensional network cured UF resin. Modification of the UF resin(UF II with ethylated urea-ether and glycerol to produce UF resins III and respectively V prominently increased the absorbance of methylene and ether groups in the spectra which are consistent with increased hydrophobicity and improved hydrolytic stability. For the conventional UF resin (UF I, the only clear distinction between spectra for the UF resin II and UF resins (III/V is the presence of diminished peaks for methylene groups at 2.2 ppm. The relationship between the logarithmic viscosity of cured PF resin with time showed continuos dependence of viscosity with time during cure up to 70 minutes. Similar trends were shown by UF resins (III/V, cured in absence of acid catalyst. In contrast, the conventional UF resins I and UF IV (i.e. UF II cured with NH4CL showed abrupt discontinuity in viscosity with time just after about 20 minutes of cure.

  12. Molecular evolution of urea amidolyase and urea carboxylase in fungi

    Harris Steven D

    2011-03-01

    Full Text Available Abstract Background Urea amidolyase breaks down urea into ammonia and carbon dioxide in a two-step process, while another enzyme, urease, does this in a one step-process. Urea amidolyase has been found only in some fungal species among eukaryotes. It contains two major domains: the amidase and urea carboxylase domains. A shorter form of urea amidolyase is known as urea carboxylase and has no amidase domain. Eukaryotic urea carboxylase has been found only in several fungal species and green algae. In order to elucidate the evolutionary origin of urea amidolyase and urea carboxylase, we studied the distribution of urea amidolyase, urea carboxylase, as well as other proteins including urease, across kingdoms. Results Among the 64 fungal species we examined, only those in two Ascomycota classes (Sordariomycetes and Saccharomycetes had the urea amidolyase sequences. Urea carboxylase was found in many but not all of the species in the phylum Basidiomycota and in the subphylum Pezizomycotina (phylum Ascomycota. It was completely absent from the class Saccharomycetes (phylum Ascomycota; subphylum Saccharomycotina. Four Sordariomycetes species we examined had both the urea carboxylase and the urea amidolyase sequences. Phylogenetic analysis showed that these two enzymes appeared to have gone through independent evolution since their bacterial origin. The amidase domain and the urea carboxylase domain sequences from fungal urea amidolyases clustered strongly together with the amidase and urea carboxylase sequences, respectively, from a small number of beta- and gammaproteobacteria. On the other hand, fungal urea carboxylase proteins clustered together with another copy of urea carboxylases distributed broadly among bacteria. The urease proteins were found in all the fungal species examined except for those of the subphylum Saccharomycotina. Conclusions We conclude that the urea amidolyase genes currently found only in fungi are the results of a horizontal

  13. Ammonia and urea permeability of mammalian aquaporins

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    /arginine region, and an exclusively water-permeable aquaporin can be transformed into an ammonia-permeable aquaporin by single point mutations in this region. The ammonia-permeable aquaporins fall into two groups: those that are permeable (AQP3, 7, 9, 10) and those that are impermeable (AQP8) to glycerol. The two......The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... significant at alkaline pH. It is debated whether the H(+) ion passes via the aquaporin or by some external route; the investigation of this problem requires the aquaporin-expressing cell to be voltage-clamped. The ammonia-permeable aquaporins differ from other aquaporins by having a less restrictive aromatic...

  14. Apical membrane limits urea permeation across the rat inner medullary collecting duct.

    Star, R A

    1990-01-01

    Urea diffuses across the terminal inner medullary collecting duct (IMCD) via a facilitated transport pathway. To examine the mechanism of transcellular urea transport, membrane-apparent urea (Purea) and osmotic water (Pf) permeabilities of IMCD cells were measured by quantitative light microscopy in isolated IMCD-2 tubules perfused in the absence of vasopressin. Basolateral membrane Pf, determined by addition of raffinose to the bath, was 69 microns/s. Basolateral membrane Purea, determined b...

  15. Use of polyurea from urea for coating of urea granules.

    Lu, Panfang; Zhang, Yanfei; Jia, Cong; Li, Yufeng; Mao, Zhiquan

    2016-01-01

    A new type of controlled release fertilizers coated with polyurea was prepared. The granulated urea was firstly changed into a liquid urea by heating as the coating liquid. By spraying uniformly the urea was coated with the polyurea synthesized by the reaction of isocyanates with a liquid urea. The effects of different modifiers on N release characteristics of polyurea-coated urea (PCU) were studied. The morphology and chemical structure of PCU coating materials was investigated by SEM and FTIR. We studied the nitrogen release characteristics of the PCU applied in both water and soil, and the biodegradability of PCU coating after buried in soil. The results showed that PCU reduced nitrogen release rate and exhibited excellent controlled release property. The PCU coating materials could biodegrade in soil. This indicated that the low cost PCU products from urea are expected to use in agricultural and horticultural applications. PMID:27119061

  16. Acidic pH and short-chain fatty acids activate Na+ transport but differentially modulate expression of Na+/H+ exchanger isoforms 1, 2, and 3 in omasal epithelium.

    Lu, Zhongyan; Yao, Lei; Jiang, Zhengqian; Aschenbach, Jörg R; Martens, Holger; Shen, Zanming

    2016-01-01

    Low sodium content in feed and large amounts of salivary sodium secretion are essential requirements to efficient sodium reabsorption in the dairy cow. It is already known that Na(+)/H(+) exchange (NHE) of the ruminal epithelium plays a key role in Na(+) absorption, and its function is influenced by the presence of short-chain fatty acids (SCFA) and mucosal pH. By contrast, the functional role and regulation of NHE in omasal epithelium have not been completely understood. In the present study, we used model studies in small ruminants (sheep and goats) to investigate NHE-mediated Na(+) transport and the effects of pH and SCFA on NHE activity in omasal epithelium and on the expression of NHE isoform in omasal epithelial cells. Conventional Ussing chamber technique, primary cell culture, quantitative PCR, and Western blot were used. In native omasal epithelium of sheep, the Na(+) transport was electroneutral, and it was inhibited by the specific NHE3 inhibitor 3-[2-(3-guanidino-2-methyl-3-oxo-propenyl)-5-methyl-phenyl]-N-isopropylidene-2-methyl-acrylamide dihydrochloride, which decreased mucosal-to-serosal, serosal-to-mucosal, and net flux rates of Na(+) by 80% each. The application of low mucosal pH (6.4 or 5.8) in the presence of SCFA activated the Na(+) transport across omasal epithelium of sheep compared with that at pH 7.4. In cultured omasal epithelial cells of goats, mRNA and protein of NHE1, NHE2, and NHE3 were detected. The application of SCFA increased NHE1 mRNA and protein expression, which was most prominent when the culture medium pH decreased from 7.4 to 6.8. At variance, the mRNA and protein expression of NHE2 and NHE3 were decreased with low pH and SCFA, which was contrary to the published data from ruminal epithelial studies. In conclusion, this paper shows that (1) NHE1, NHE2, and NHE3 are expressed in omasal epithelium; (2) NHE3 mediates the major portion of transepithelial Na(+) transport in omasal epithelium; and (3) SCFA and acidic pH acutely

  17. Urea dewaxing of naphthene oils

    Mead, Th. C.; Wright, J. H.

    1985-03-12

    In an improved urea dewaxing process a urea/alcohol slurry chilled to 60/sup 0/ F. to 65/sup 0/ F. is added to a naphthenic distillate chilled to 60/sup 0/ F. to 65/sup 0/ F. to produce a refrigerator oil with improved low temperature properties.

  18. Microbial urea-formaldehyde degradation involves a new enzyme, methylenediurease.

    Jahns, T; Schepp, R; Siersdorfer, C; Kaltwasser, H

    1998-01-01

    The enzymic mechanism of metabolization of urea-formaldehyde condensation products (methyleneureas; MU) and the fate of the degradation products ammonium, urea and formaldehyde were studied in bacteria isolated from garden soil, which were able to use methyleneureas as the sole source of nitrogen for growth. An organism identified as Ochrobactrum anthropi completely degraded methylenediurea (MDU) and dimethylenetriurea (DMTU) to urea, ammonia, formaldehyde and carbon dioxide. An enzyme designated as methylenediurease (methylenediurea deiminase; MDUase) was responsible for the degradation of both MDU and DMTU as well as higher polymerized MU. Growth on MU as the nitrogen source specifically induced the synthesis of this enzyme, which seems to be located in the periplasm of the bacterium. Under these growth conditions, urease as well as NAD-specific formaldehyde and formiate dehydrogenase were expressed to high levels, efficiently using the products of MU degradation, and high-affinity transport systems for urea and ammonia were synthesized scavenging the environment for these products. PMID:10526991

  19. Lithiation Chemistry of Vinyl Ureas

    Lefranc, Julien

    2011-01-01

    The construction of tertiary alkylamines is a synthetic challenge exacerbated by the poor electrophilicity of imines. Due to the presence of this kind of building block in a large number of bioactive molecules, the development of new strategies to synthesise the quaternary carbon centre is essential.This thesis describes the work carried out on the rearrangement of lithiated vinyl ureas in order to form α-tertiary amines. The first part presents how vinyl ureas were synthesised, using the re...

  20. Studies on the acid activation of Brazilian smectitic clays

    Francisco R. Valenzuela Díaz; Pérsio de Souza Santos

    2001-01-01

    Fuller's earth and acid activated smectitic clays are largely used as bleaching earth for the industrial processing of vegetable, animal and mineral oils and waxes. The paper comments about the nomenclature used for these materials, the nature of the acid activation of smectitic clays (bentonites), activation laboratory procedures and presents a review of the acid activation of bentonites from 20 deposits from several regions of Brazil. The activated clays were tested and show good decolorizi...

  1. Selective catalytic reduction of NOx from diesel engine exhaust using injection of urea. Doctoral thesis

    Hultermans, R.J.

    1995-09-25

    ;Contents: Diesel exhaust NOx formation and abatement (Diesel DeNOxing literature, System Considerations, Summary); Catalytic testing (Experimental facilities for testing catalysts, transport phenomena in steady state fixed bed reactors, Catalyst testing); Development of a urea injection system.

  2. NOx abatement through urea additives

    Compared with catalytic denitrification, the use of urea in thermic processes of selective, non-catalytic reduction (SNCR), when combined with primary measures, constitutes an inexpensive alternative way of abating NOx emissions by means of combustion processes and waste incineration plants. A natural-gas fired and also electrically heated flow reactor was used in a number of fast series to systematically determine the influences of retention time, reaction temperature, reductant (ammonia or urea), molar ratio, and additives (ethanol) on the process. Balancing the input and output nitrogenous substances served to describe the partial shift through addition of ethanol of the reaction towards incomplete reduction and greater N2O emission. (orig.)

  3. Examining urea flux across the intestine of the spiny dogfish, Squalus acanthias.

    Gary Anderson, W; McCabe, Chris; Brandt, Catherine; Wood, Chris M

    2015-03-01

    Recent examination of urea flux in the intestine of the spiny dogfish shark, Squalus acanthias, has shown that feeding significantly enhances urea uptake across the intestine, and this was significantly inhibited following mucosal addition of phloretin. The present study examined potential mechanisms of urea uptake across the dogfish intestine in starved and fed dogfish. Unidirectional flux chambers were used to examine the kinetics of urea uptake, and to determine the influence of sodium, ouabain, competitive urea analogues, and phloretin on urea uptake across the gut of fed dogfish. Intestinal epithelial preparations from starved and fed dogfish were mounted in Ussing chambers to examine the effect of phloretin on bidirectional solute transport across the intestine. In the unidirectional studies, the maximum uptake rate of urea was found to be 35.3±6.9 μmol.cm(-2).h(-1) and Km was found to be 291.8±9.6 mM in fed fish, and there was a mild inhibition of urea uptake following mucosal addition of competitive agonists. Addition of phloretin, Na-free Ringers and ouabain to the mucosal side of intestinal epithelia also led to a significant reduction in urea uptake in fed fish. In the Ussing chamber studies there was a net influx of urea in fed fish and a small insignificant efflux in starved fish. Addition of phloretin blocked urea uptake in fed fish when added to the mucosal side. Furthermore, phloretin had no effect on ion transport across the intestinal epithelia with the exception of the divalent cations, magnesium and calcium. PMID:25479361

  4. High plasma urea concentrations in collodion babies

    1987-01-01

    We describe two infants born with a collodion membrane; both were treated with a product containing 10% urea and 5% lactic acid and as a consequence were found to have a raised plasma urea concentration.

  5. Urea Biosynthesis Using Liver Slices

    Teal, A. R.

    1976-01-01

    Presented is a practical scheme to enable introductory biology students to investigate the mechanism by which urea is synthesized in the liver. The tissue-slice technique is discussed, and methods for the quantitative analysis of metabolites are presented. (Author/SL)

  6. Pembuatan Biosensor Urea Dengan Transduser Tembaga

    Khairi

    2010-01-01

    Pada penelitian ini dilaporkan pembuatan biosensor urea dengan metode potensiometri secara elektroda selektifion (ESI). Elektroda ini disebut elektroda urea tipe kawat terlapis. Elektroda urea diimobilisasi oleh enzim urease secara entrapmen pada kawat tembaga berdiameter 0,2 mm dengan komposisi membran PVC (polivinilklorida) : THF (tetrahidrofuran) : urease = 10 mg : 1,5 mL : 200 mg. Konsentrasi urea dalam sampel ditentukan berdasarkan perubahan pH yang dihasilkan dari reaksi hidrolis...

  7. 40 CFR 721.9892 - Alkylated urea.

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  8. Urea biosensor for hemodialysis monitoring

    Glass, R.S.

    1999-01-12

    This research discloses an electrochemical sensor capable of detecting and quantifying urea in fluids resulting from hemodialysis procedures. The sensor is based upon measurement of the pH change produced in an aqueous environment by the products of the enzyme-catalyzed hydrolysis of urea. The sensor may be fabricated using methods amenable to mass fabrication, resulting in low-cost sensors and thus providing the potential for disposable use. In a typical application, the sensor could be used in treatment centers, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. The sensor can also be utilized to allow at-home testing to determine if dialysis was necessary. Such a home monitor is similar, in principle, to devices used for blood glucose testing by diabetics, and would require a blood droplet sample by using a finger prick. 9 figs.

  9. Urea biosensor for hemodialysis monitoring

    Glass, Robert S. (Livermore, CA)

    1999-01-01

    An electrochemical sensor capable of detecting and quantifying urea in fluids resulting from hemodialysis procedures. The sensor is based upon measurement of the pH change produced in an aqueous environment by the products of the enzyme-catalyzed hydrolysis of urea. The sensor may be fabricated using methods amenable to mass fabrication, resulting in low-cost sensors and thus providing the potential for disposable use. In a typical application, the sensor could be used in treatment centers, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. The sensor can also be utilized to allow at-home testing to determine if dialysis was necessary. Such a home monitor is similar, in principle, to devices used for blood glucose testing by diabetics, and would require a blood droplet sample by using a finger prick.

  10. Nutritional factors influencing milk urea in buffaloes

    V. Proto

    2011-03-01

    Full Text Available Urea is the primary form in which N is excreted in ruminants. Milk urea (MU content was introduced as a means to monitor the efficiency of protein utilisation in dairy cattle (Baker et al., 1995; Roseler et al., 1993; Bertoni, 1995. In this study the effect of some nutrition factors on MU content in buffalo herds was analysed in order to examine the possibility that protein nutrition could be monitored by means of milk urea at herd level........

  11. Urea synthesis in patients with chronic pancreatitis

    Hamberg, Ole; Sonne, J; Larsen, S;

    2001-01-01

    Up-regulation of urea synthesis by amino acids and dietary protein intake may be impaired in patients with chronic pancreatitis (CP) due to the reduced glucagon secretion. Conversely, urea synthesis may be increased as a result of the chronic inflammation. The aims of the study were to determine...... urea synthesis kinetics in CP patients in relation to glucagon secretion (study I) and during an increase in protein intake (study II)....

  12. Urea and deuterium mixtures at high pressures

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D2 mixtures that indicate no inclusion compound forms up to 3.7 GPa

  13. Molecular and physiological interactions of urea and nitrate uptake in plants.

    Pinton, Roberto; Tomasi, Nicola; Zanin, Laura

    2016-01-01

    While nitrate acquisition has been extensively studied, less information is available on transport systems of urea. Furthermore, the reciprocal influence of the two sources has not been clarified, so far. In this review, we will discuss recent developments on plant response to urea and nitrate nutrition. Experimental evidence suggests that, when urea and nitrate are available in the external solution, the induction of the uptake systems of each nitrogen (N) source is limited, while plant growth and N utilization is promoted. This physiological behavior might reflect cooperation among acquisition processes, where the activation of different N assimilatory pathways (cytosolic and plastidic pathways), allow a better control on the nutrient uptake. Based on physiological and molecular evidence, plants might increase (N) metabolism promoting a more efficient assimilation of taken-up nitrogen. The beneficial effect of urea and nitrate nutrition might contribute to develop new agronomical approaches to increase the (N) use efficiency in crops. PMID:26338073

  14. Passive water and urea permeability of a human Na(+)-glutamate cotransporter expressed in Xenopus oocytes

    Macaulay, Nanna; Gether, Ulrik; Klærke, Dan Arne;

    2002-01-01

    The human Na(+)-glutamate transporter (EAAT1) was expressed in Xenopus laevis oocytes. The passive water permeability, L(p), was derived from volume changes of the oocyte induced by changes in the external osmolarity. Oocytes were subjected to two-electrode voltage clamp. In the presence of Na...... similar to the K(0.5) value for glutamate activation of transport. The specific inhibitor DL-threo-beta-benzyloxyaspartate (TBOA) reduced the EAAT1-specific L(p) to 72 %. EAAT1 supported passive fluxes of [(14)C]urea and [(14)C]glycerol. The [(14)C]urea flux was increased in the presence of glutamate. The...

  15. Ammonia volatilization from coated urea forms

    Carlos Antonio Costa do Nascimento

    2013-08-01

    Full Text Available Nitrogen fertilization is a major component of the cost of agricultural production, due to the high cost and low efficiency of fertilizers. In the case of urea, the low efficiency is mainly due to losses by volatilization, which are more pronounced in cultivation systems in which plant residues are left on the soil. The objective of this work was to compare the influence of urea coated with sulfur or boric acid and copper sulfate with conventional N fertilizers on N volatilization losses in sugar cane harvested after stubble burning. The sources urea, sulfur-coated urea, urea coated with boric acid and copper sulfate, as well as nitrate and ammonium sulfate, were tested at amounts containing N rates of 120 kg ha-1 N. The integration of new technologies in urea fertilization can reduce N losses by volatilization. These losses were most reduced when using nitrate and ammonium sulfate. The application of a readily acidified substance (boric acid to urea was more efficient in reducing volatilization losses and nutrient removal by sugar cane than that of a substance with gradual acidification (elemental sulfur.

  16. Phytotoxicity of foliar-applied urea

    Krogmeier, Michael J.; McCarty, Gregory W.; Bremner, John M.

    1989-01-01

    Recent work in our laboratory showed that the adverse effect of urea fertilizer on seed germination and seedling growth in soil is due to ammonia produced through hydrolysis of urea by soil urease (NH2CONH2 + H2O → 2NH3 + CO2) and can be eliminated by amending the fertilizer with a small amount of a urease inhibitor such as phenylphosphorodiamidate. Because the leaf-tip necrosis often observed after foliar fertilization of plants with urea is usually attributed to ammonia formed through hydro...

  17. Synthesis of 15 N double labelled urea

    Synthesis of double 15 N labelled urea by reacting 15 N - ammonia with elemental sulfur and carbon monoxide in a pressure vessel is presented. 15 NH3 was produced by H15 NO3 reduction with Dewarda alloy in alkaline solution, or by nitric monoxide reduction with hydrogen on metallic manganese. An average yield of 85% tacking into account 15 N - urea and 15 N ammonium sulfate, produced in the same time, and 99% urea purity (checked by I.R. spectroscopy and mass spectrometry) were obtained. (authors)

  18. Effect of urea on biomimetic aggregates

    F.H. Florenzano

    1997-02-01

    Full Text Available The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic, monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied, which leads to an increase in the area per headgroup and also in the loss of counterion affinities

  19. Effect of urea on biomimetic aggregates.

    Florenzano, F H; Politi, M J

    1997-02-01

    The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of counterion affinities. PMID:9239302

  20. Catalytic Ethanol Dehydration over Different Acid-activated Montmorillonite Clays.

    Krutpijit, Chadaporn; Jongsomjit, Bunjerd

    2016-01-01

    In the present study, the catalytic dehydration of ethanol to obtain ethylene over montmorillonite clays (MMT) with mineral acid activation including H2SO4 (SA-MMT), HCl (HA-MMT) and HNO3 (NA-MMT) was investigated at temperature range of 200 to 400°C. It revealed that HA-MMT exhibited the highest catalytic activity. Ethanol conversion and ethylene selectivity were found to increase with increased reaction temperature. At 400°C, the HA-MMT yielded 82% of ethanol conversion having 78% of ethylene yield. At lower temperature (i.e. 200 to 300°C), diethyl ether (DEE) was a major product. The highest activity obtained from HA-MMT can be attributed to an increase of weak acid sites and acid density by the activation of MMT with HCl. It can be also proven by various characterization techniques that in most case, the main structure of MMT did not alter by acid activation (excepted for NA-MMT). Upon the stability test for 72 h during the reaction, the MMT and HA-MMT showed only slight deactivation due to carbon deposition. Hence, the acid activation of MMT by HCl is promising to enhance the catalytic dehydration of ethanol. PMID:27041515

  1. Comparison of sodium and urea as indicators of pulmonary vascular permeability

    The objective of this work was to compare the blood-tissue transport properties of 14C-urea and 24Na in the lung circulation. The extraction of both substances was measured relative to intravascular reference tracers (125I-albumin for 24Na, 51Cr red cells and 125I-albumin for 14C-urea) in single-pass transpulmonary multiple indicator curves measured in awake sheep. Sheep were studied in baseline condition, after infusion of histamine solution (4 micrograms/kg-min for 4 hr), and after microvascular pressure was elevated. Permeability-surface area was computed for both sodium (PSn) and urea (PSu) by the Crone extraction model and by a mathematical model. In spite of the fact that the free diffusion coefficients of sodium and urea are approximately equal, the mean ratio of Crone PSn/PSu for baseline studies was 0.76. PSu was significantly increased by histamine infusion but PSn was not. The variation in PSn with histamine and increased pressure was marked. Thus, neither manipulation altered the ratio PSn/PSu in a consistent fashion. Correction of PS for extravascular distribution volumes of urea and Na did not change the PS ratio significantly. We concluded that the diffusional resistance to sodium is higher than expected from its diffusivity, possibly because of charge, and that PS for urea is more sensitive to changes in lung vascular permeability

  2. Release Kinetics of Urea from Polymer Coated Urea and Its Relationship with Coating Penetrability

    ZHANG Hai-jun; WU Zhi-jie; CHEN Li-jun; LIANG Wen-ju

    2003-01-01

    Four kinds of polymer coated urea (PCU) were put in distilled water at 30C to determine the variation of coating penetrability and give a precise description of the urea release kinetics. The urea release from PCU could be divided into four stages: lag stage, swell stage, steady stage and decay stage. The release rate coefficient K, a measure of coating penetrability, was linearly increased at swell stage, but almost not variable at steady stage. At decay stage, the relation of K to time t could be described by the equation K= mtn-1(where m and n are the coefficients). When n>1, the coating penetrability was gradually increased, and the urea release from PCU was accelerated; when n=1, the coating penetrability was steady, and the urea release from PCU obeyed the first-order kinetics; and when n<1, the coating penetrability was gradually decreased,and the urea release from PCU was delayed, resulting in a significant "tailing effect".

  3. Surface modified silicon nanochannel for urea sensing

    Chen, Yu; Hong, Mi; Erramilli, Shyamsunder; Mohanty, Pritiraj

    2008-01-01

    Silicon nanowires have been surface functionalized with the enzyme urease for biosensor applications to detect and quantify urea concentration. The device is nanofabricated from a silicon on insulator (SOI) wafer with a top down lithography approach. The differential conductance of silicon nanowires can be tuned for optimum performance using the source drain bias voltage, and is sensitive to urea at low concentration. The experimental results show a linear relationship between surface potential change and urea concentration in the range of 0.1 to 0.68 mM. The sensitivity of our devices shows high reproducibility with time and different measurement conditions. The nanowire urea biosensor offers the possibility of high quality, reusable enzyme sensor array integration with silicon based circuits.

  4. Metabolism of urea in kids fed different levels of urea molasses diets

    Urea entry rates were measured in the body pool of Barbari kids using a single injection isotope dilution technique. The kids were divided into five groups (T1, T2, T3, T4 and T5) and they were fed different levels of urea molasses viz., 10, 25, 35, 40 and 0 percent to meet their DCP requirement along with concentrate mixture and oat hay as per A.R.C. recommendation. Urea entry rate was significantly higher (P1 and the control group (T5 without urea in their diets) than that of T2, T3 and T4 which were not significantly different from each other. (author)

  5. 21 CFR 862.1770 - Urea nitrogen test system.

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  6. Transfer of blood urea into the goat colon

    Transfer of blood urea to the temporarily isolated and perfused colon of conscious goats was measured. Simultaneously, total urea turnover was estimated using 14C-labelled urea. Three animals in the weight range 50-70 k were used, with appropriately placed cannulae. The entry of blood urea into the total gastrointestinal tract was estimated from the difference between total urea turnover renal urea excretion. When experimental conditions remained constant, such as the permeability of the gastrointestinal tract wall, blood urea diffusion into the colon depended on plasma urea concentration. Results of varying feeding conditions demonstrated that changes in permeability of the gastrointestinal tract will have a more pronounced influence on the amounts of blood urea entering the gastrointestinal tract than differences in plasma urea concentration

  7. Study on the way of urea removal by baf

    Biofilm process is a kind of efficient way for sewage with high concentration of urea. A lot of researches on removal efficiency were carried out, but there existed less research for the process of urea removal. To understand the way of urea removal by biofilm process, biological aerated filter (BAF) was used to deal with sewage with high concentration of urea from a chemical plant, by studying adsorption property of the carrier, biomass and biological activity on the carrier, and contrastive analysis between hydrolysis product of urea and theoretical value was carried out and the microbial flora of urea removal was preliminarily determined using the method of inhibiting biological activity. The results showed that, removal of urea by BAF was mainly the result of biological action, the adsorption capacity of activated carbon for urea was limited, the dominant bacterial communities for the hydrolysis of urea were heterotrophic bacteria, and parts of nitrobacteria and nitrobacteria also had a certain capacity of hydrolyzing urea. (author)

  8. The permeability of red blood cells to chloride, urea and water

    Brahm, Jesper

    This study extends permeability (P) data on chloride, urea and water in red blood cells (RBC), and concludes that the urea transporter (UT-B) does not transport water. P of chick, duck, Amphiuma means, dog and human RBC to (36)Cl(-), (14)C-urea and (3)H2O was determined under self......-exchange conditions. At 25°C and pH 7.2-7.5, PCl is 0.94×10(-4)-2.15×10(-4) cm s(-1) for all RBC species at [Cl]=127-150 mmol l(-1). In chick and duck RBC, Purea is 0.84×10(-6) and 1.65×10(-6) cm s(-1), respectively, at [urea]=1-500 mmol l(-1). In Amphiuma, dog and human RBC, Purea is concentration dependent (1......-1000 mmol l(-1), Michaelis-Menten-like kinetics; K½=127, 173 and 345 mmol l(-1)), and values at [urea]=1 mmol l(-1) are 29.5×10(-6), 467×10(-6) and 260×10(-6) cm s(-1), respectively. Diffusional water permeability, Pd, was 0.84×10(-3) (chick), 5.95×10(-3) (duck), 0.39×10(-3) (Amphiuma), 3.13×10(-3) (dog...

  9. Theoretical and NMR experimental insights on urea, thiourea and diindolyurea as fluoride carriers

    Mendonça, João Guilherme P.; Silla, Josué M.; Andrade, Laize A. F.; Fernandes, Sergio A.; Cormanich, Rodrigo A.; Freitas, Matheus P.

    2016-06-01

    Urea and thiourea derivatives are widely known as anion transporters. The pristine urea and thiourea compounds were theoretically and spectroscopically evaluated as fluoride ligands, since transportation of F- is involved in many biochemical processes and this anion is suitable to be analyzed through NMR. Conformational changes induced by anions can be useful to probe ligand-anion complexation, but urea and thiourea do not undergo conformational isomerization. Thus, diindolylurea (DIU) was computationally investigated to search for its conformational preferences upon complexation with fluoride. Overall, the NMR proton signal for urea and thiourea moved downfield and broadened upon addition of one equivalent of fluoride anion in DMSO solution, indicating complexation. The 19F signal for the thiourea-F- mixture also shifted relative to the anion source. However, a J(N)H,F coupling constant was not observed, probably because of entropy and bulk solvation effects. In addition, the conformational preference of DIU changed drastically after simulated complexation with fluoride, in agreement with previous studies with other anions. This confirms the potential of urea derivatives as fluoride carriers.

  10. A perfusion study of the handling of urea and urea analogues by the gills of the dogfish shark (Squalus acanthias)

    Wood, Chris M.; Hon Jung Liew; Gudrun De Boeck; Patrick J. Walsh

    2013-01-01

    The branchial mechanism of urea retention in elasmobranchs was investigated using an in vitro isolated-perfused head preparation, as well as in vivo samples, in the spiny dogfish shark. Both in vivo and in control saline perfusions containing 350 mmol L−1 urea, calculated intracellular urea concentrations in gill epithelial cells were close to extracellular concentrations. Urea efflux to the external water fell only non-significantly, and calculated gill intracellular urea concentration did n...

  11. Standardization of the TRUE Test imidazolidinyl urea and diazolidinyl urea patches

    Agner, T; Andersen, Klaus Ejner; Björkner, B; Bruze, M; Frosch, P J; Gruvberger, B; Hoeck, U; Kreilgaard, B; Menné, T; Sommer, J

    2001-01-01

    The preservatives imidazolidinyl urea (IMID, Germall 115) and diazolidinyl urea (DU, Germall II) are commonly used in cosmetic products and are well-known sensitizers. The aim of the present study was to establish the optimal patch test concentration in hydrophilic dried-in vehicle (TRUE Test) for...

  12. Winter Wheat and Maize Response to Urea Ammonium Nitrate and a New Urea Formaldehyde Polymer Fertilizer

    Slow release nitrogen (N) fertilizers have potential to improve yield and nitrogen use efficiency (NUE) in winter wheat (Triticum aestivum L.) and maize (Zea mays L.). A slow release urea formaldehyde polymer (UFP) was compared with conventional aqueous urea-ammonium nitrate (UAN) [(NH2)2CO, NH4NO3]...

  13. Urea recycling from the renal pelvis in sheep: A study with [14C]urea

    To test the hypothesis that urea can be recycled from the renal pelvis, [14C]urea diluted in native urine (1 microCi/ml) was perfused (0.5 ml/min) into one of the pelvises of sheep fed either normal (NP) or low (LP)-protein diets. Blood samples were obtained from the ipsilateral renal vein and from the carotid artery throughout the perfusions. 14C activity determinations in urine and plasma demonstrated a flux of [14C]urea from the pelvis to renal vein blood (40,000 in NP and 130,000 disintegrations/min in LP sheep, P less than 0.01). The corresponding flux of native urea was only 1.5 times higher in NP than in LP sheep (6.8 +/- 1.1 vs. 4.7 +/- 2.9 mumol/min, not significant) despite their 8 times higher urinary concentration of urea. The fraction of filtered urea that was reabsorbed in the pelvis was larger in LP sheep (7.5 +/- 3.7 vs. 1.9 +/- 0.7% in NP sheep, P less than 0.05). A fraction of urea is thus actually recycled from the renal pelvis in sheep, and this pelvic retention is enhanced in LP animals. The importance of this phenomenon in the nitrogen economy is discussed

  14. Imaging Renal Urea Handling in Rats at Millimeter Resolution using Hyperpolarized Magnetic Resonance Relaxometry

    Reed, Galen D; Verkman, Alan S; Koelsch, Bertram L; Chaumeil, Myriam M; Lustig, Michael; Ronen, Sabrina M; Sands, Jeff M; Larson, Peder E Z; Wang, Zhen J; Larsen, Jan Henrik Ardenkjær; Vigneron, Daniel B

    2015-01-01

    \\textit{In vivo} spin spin relaxation time ($T_2$) heterogeneity of hyperpolarized \\textsuperscript{13}C urea in the rat kidney was investigated. Selective quenching of the vascular hyperpolarized \\textsuperscript{13}C signal with a macromolecular relaxation agent revealed that a long-$T_2$ component of the \\textsuperscript{13}C urea signal originated from the renal extravascular space, thus allowing the vascular and renal filtrate contrast agent pools of the \\textsuperscript{13}C urea to be distinguished via multi-exponential analysis. The $T_2$ response to induced diuresis and antidiuresis was performed with two imaging agents: hyperpolarized \\textsuperscript{13}C urea and a control agent hyperpolarized bis-1,1-(hydroxymethyl)-1-\\textsuperscript{13}C-cyclopropane-$^2\\textrm{H}_8$. Large $T_2$ increases in the inner-medullar and papilla were observed with the former agent and not the latter during antidiuresis suggesting that $T_2$ relaxometry may be used to monitor the inner-medullary urea transporter (UT)-...

  15. Transport

    Transport is one of the major causes of environmental damage in Austria. Energy consumption, pollutants emissions, noise emissions, use of surfaces, sealing of surfaces, dissection of ecosystems and impact on landscape are the most significant environmental impacts caused by it. An overview of the transport development of passengers and freight in Austria is presented. Especially the energy consumption growth, carbon dioxide and nitrogen oxide emissions by type of transport, and the emissions development (HC, particle and carbon monoxide) of goods and passengers transport are analyzed covering the years 1980 - 1999. The health cost resulting from transport-related air pollution in Austria is given and measures to be taken for an effective control of the transport sector are mentioned. Figs. 8, Table 1. (nevyjel)

  16. Nickel hydroxide electrode with a monolayer of nanocup arrays as an effective electrocatalyst for enhanced electrolysis of urea

    Highlights: • Nickel hydroxide electrode with tailored nanocup architecture was fabricated. • Deposition time dominates the morphological evolution of catalyst layer. • Catalyst with nanocup arrays expedites the transport of ion, electron, and gas. • Cup-like pore arrays provide much more active sites for the electrolysis of urea. - Abstract: Nickel hydroxide electrode composed of cup-like pore arrays, which could act as an effective catalyst layer for electrolysis of urea, was formed on stainless steel foil by cathodic electrodeposition using a monolayer of polystyrene spheres as a template. The morphology of the catalyst layer could be controlled from nanocup to hollow sphere by tuning the deposition time. Electrolysis of urea was characterized by cyclic voltammetry and chronoamperometry in 1 M KOH electrolyte containing 0.33 M urea. The tailored catalyst layer with nanocup arrays expedited the transport of ion, electron, and gas. Moreover, cup-like pore arrays might lead to an increased surface area, and more active sites were exposed to electrolyte for the electrolysis of urea. Therefore, the nickel hydroxide electrode with nanocup architecture offered the benefit of much better electrocatalytic performance than the film electrode and hollow-sphere electrode during electrolysis of urea

  17. Synthesis and characterization of chitosan alkyl urea.

    Wang, Jing; Jiang, Ji-Zhou; Chen, Wei; Bai, Zheng-Wu

    2016-07-10

    Chitosan is a versatile material employed for various purposes in many fields including the development of chiral stationary phases for enantioseparation. Chitosan alkyl urea is a kind of intermediate used to prepare enantioseparation materials. In order to synthesize the intermediates, in the present work, a new way to prepare chitosan alkyl urea has been established: chitosan was first reacted with methyl chloroformate yielding N-methoxyformylated chitosan, which was then converted to chitosan alkyl urea through amine-ester exchange reaction. With a large excess of methyl chloroformate and primary amine of low stereohindrance, the amino group in chitosan could be almost completely converted to ureido group. The as-prepared chitosan alkyl urea derivatives were characterized by IR, (1)H NMR, (13)C NMR,(1)H-(1)H COSY and (1)H-(13)C HSQC NMR spectra. The chemical shifts of hydrogen and carbon atoms of glucose unit were assigned. It was found that the degree of substitution was obviously lower if cyclopropyl amine, aniline, tert-butyl amine and diethyl amine were used as reactants for the amine-ester exchange reaction. The reason was explained with the aid of theoretical calculations. PMID:27106154

  18. 21 CFR 176.320 - Sodium nitrate-urea complex.

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  19. Synergetic Effects of Nanoporous Support and Urea on Enzyme Activity

    Lei, Chenghong; Shin, Yongsoon; Liu, Jun; Ackerman, Eric J.

    2007-02-01

    Here we report that synergetic effects of functionalized nanoporous support and urea on enzyme activity enhancement. Even in 8.0 M urea, the specific activity of GI entrapped in FMS was still higher than the highest specific activity of GI free in solution, indicating the strong tolerance of GI in FMS to the high concentration of urea.

  20. Early diabetic kidney maintains the corticomedullary urea and sodium gradient

    Qi, Haiyun; Nørlinger, Thomas S; Nielsen, Per M; Bertelsen, Lotte B; Mikkelsen, Emmeli; Xu, Yafang; Stødkilde Jørgensen, Hans; Laustsen, Christoffer

    2016-01-01

    concomitantly with a decreased sodium and urea gradient. By using hyperpolarized (13)C urea it was possible to measure the essential intrarenal electrolyte gradients and the acute changes following furosemide treatment. No differences in either intrarenal urea or sodium gradients were observed in early diabetes...

  1. Penentuan Rute Pengiriman Pupuk Urea Bersubsidi di Karanganyar

    Yusuf Priyandari

    2011-01-01

    Full Text Available This paper develops a vehicle routing problem (VRP model for determining the routes in urea fertilizer distribution from a depot to retailers. The distribution is done in work days which uses trucks, each truck can serve more than one route (multiple trips, and each retailer has a time window. The vehicle routing model is built in a mixed integer linear programming (MILP and the objective function is minimizing total transportation cost. The distances from the distributor to retailers and inter-retailers do not use Euclidian approach but the road network on a digital map in order to make the route solution is more realistic. Historical distribution data was used to test the model. The result shows that the model can minimize the cost about 2.28% which is compared to the original routes.

  2. ADSORPTION FROM AQUEOUS SOLUTION ONTO NATURAL AND ACID ACTIVATED BENTONITE

    Laila Al-Khatib

    2012-01-01

    Full Text Available Dyes have long been used in dyeing, paper and pulp, textiles, plastics, leather, paint, cosmetics and food industries. Nowadays, more than 100,000 commercial dyes are available with a total production of 700,000 tones manufactured all over the world annually. About 10-15% of dyes are being disposed off as a waste into the environment after dyeing process. This poses certain hazards and environmental problems. The objective of this study is to investigate the adsorption behavior of Methylene Blue (MB from aqueous solution onto natural and acid activated Jordanian bentonite. Both bentonites are firstly characterized using XRD, FTIR and SEM techniques. Then batch adsorption experiments were conducted to investigate the effect of initial MB concentration, contact time, pH and temperature. It was found that the percentage of dye removal was improved from 75.8% for natural bentonite to reach 99.6% for acid treated bentonite. The rate of MB removal followed the pseudo second order model with a high correlation factor. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir isotherm model was found more representative. The results indicate that bentonite could be employed as a low cost adsorbent in wastewater treatment for the removal of colour and dyes.

  3. Design and characterization of an acid-activated antimicrobial peptide.

    Li, Lina; He, Jian; Eckert, Randal; Yarbrough, Daniel; Lux, Renate; Anderson, Maxwell; Shi, Wenyuan

    2010-01-01

    Dental caries is a microbial biofilm infection in which the metabolic activities of plaque bacteria result in a dramatic pH decrease and shift the demineralization/remineralization equilibrium on the tooth surface towards demineralization. In addition to causing a net loss in tooth minerals, creation of an acidic environment favors growth of acid-enduring and acid-generating species, which causes further reduction in the plaque pH. In this study, we developed a prototype antimicrobial peptide capable of achieving high activity exclusively at low environmental pH to target bacterial species like Streptococcus mutans that produce acid and thrive under the low pH conditions detrimental for tooth integrity. The features of clavanin A, a naturally occurring peptide rich in histidine and phenylalanine residues with pH-dependent antimicrobial activity, served as a design basis for these prototype 'acid-activated peptides' (AAPs). Employing the major cariogenic species S. mutans as a model system, the two AAPs characterized in this study exhibited a striking pH-dependent antimicrobial activity, which correlated well with the calculated charge distribution. This type of peptide represents a potential new way to combat dental caries. PMID:19878192

  4. Transfer of blood urea into the goat colon

    Transfer of body urea into the temporarily isolated and perfused colon of conscious goats was measured. Simultaneously total urea turnover was estimated using 14C-urea. The transfer of urea into the total gastrointestinal tract (total turnover minus renal excretion) was four times higher with the high-energy - low-protein diet (sugar pulp plus straw) compared with control feeding (hay ad lib.). The transfer of urea into the colon was 8% of the transfer into the total GI tract during control feeding, 14% when food was withheld for 48 hours and 1% during sugar pulp feeding. The transfer into the colon depends mainly on the plasma urea concentration, whereas in the proximal part of the GI tract changes in the permeability of the GI tract wall have a more pronounced influence than plasma urea concentration. (author)

  5. Milk Urea Dynamics during its Transformation into Yogurt

    Cornelia Vintila

    2011-10-01

    Full Text Available The purpose of our work was to evaluate in what measure milk urea concentration stays in processed yogurt and in what measure urea dose influences its quality. We added known amounts of urea into milk destined to yogurt processing in order to obtain probes with concentrations from 0,5 to 28 mg/ 100 ml milk. Obtained results lead us to the conclusion that milk urea decreases dramatically until the finishing of the process of milk coagulation and its transformation into yogurt. All probes which contained higher amounts of urea than 6 mg/ 100 ml milk, urea totally disappeared from yogurt before 48 hours of keeping. Milk coagulation time and its transformation to yogurt is reduced proportional with urea concentration in milk.

  6. Entry of blood urea into the rumen of the llama

    Llamas were provided with a large rumen fistula, and the transfer of blood urea into the temporarily isolated rumen, cleaned and filled with test solution was measured. Plasma urea clearance due to transfer of blood urea across the rumen wall should indicate changes in its permeability to urea. Clearance values were highest with CO2 or with high concentrations of butyric acid. Permeability was low when food was with-held and when no volatile fatty acids were present in the solution. The permeability of the rumen wall to blood urea can be altered significantly. These changes can affect blood urea transfer more extensively than changes in the plasma urea concentration within physiological ranges

  7. Atomic scale insights into urea-peptide interactions in solution.

    Steinke, Nicola; Gillams, Richard J; Pardo, Luis Carlos; Lorenz, Christian D; McLain, Sylvia E

    2016-02-01

    The mechanism by which proteins are denatured by urea is still not well understood, especially on the atomic scale where these interactions occur in vivo. In this study, the structure of the peptide GPG has been investigated in aqueous urea solutions in order to understand the combination of roles that both urea and water play in protein unfolding. Using a combination of neutron diffraction enhanced by isotopic substitution and computer simulations, it was found, in opposition with previous simulations studies, that urea is preferred over water around polar and charged portions of the peptides. Further, it appears that while urea directly replaces water around the nitrogen groups on GPG that urea and water occupy different positions around the peptide bond carbonyl groups. This suggests that urea may in fact weaken the peptide bond, disrupting the peptide backbone, thus ultimately causing denaturation. PMID:26764567

  8. Urea-SCR System Demonstration and Evaluation for Heavy-Duty Diesel Trucks

    Brodrick, C. J.; M Farshchi; Dwyer, H. A.; Sperling, D.; Gouse, S. W.; Doelling, W.; Hoelzer, J.; Jackson, M.

    2001-01-01

    The Institute of Transportation Studies at the University of California, Davis (ITS-Davis) has brought together a group of public and industrial partners to demonstrate and evaluate the Siemens-Westinghouse Urea-Selective Catalyst Reduction System (SINOx TM). The SINOx System has the potential to generate major reductions in nitrogen oxides (NOx) and the volatile organic fraction (VOF) of particulate (PM) from heavy-duty diesel engines, without increasing fuel consumption and carbon dioxide (...

  9. Influence of milk urea concentration on fractional urea disappearance rate from milk to blood plasma in dairy cows.

    Spek, J W; Dijkstra, J; Bannink, A

    2016-05-01

    The relationship between milk urea nitrogen (MUN; mg of N/dL) and urinary N excretion is affected, among others, by diurnal dynamics in MUN, which in turn is largely influenced by feed intake pattern and characteristics of urea transfer from blood plasma to milk and vice versa. This study aimed to obtain insight in urea transfer characteristics within the mammary gland and from the mammary gland to blood plasma in dairy cows at various concentrations of plasma urea nitrogen (PUN; mg of N/dL) and MUN. Urea transfer from milk to blood plasma and urea transfer within the mammary gland itself was evaluated in a 4×4 Latin square design using 4 lactating multiparous Holstein-Friesian cows (milk production of 39.8±4.70kg/d and 90±3.9 d in milk). Treatments consisted of 4 primed continuous intravenous urea infusions of 0, 5, 10, and 15g of urea/h. Boluses of [(15)N(15)N]urea were injected in cistern milk at 20, 60, and 100 min before the 1700h milking. Milk was collected in portions of approximately 2 L at the 1700h milking. Milk samples were analyzed for urea and enrichment of (15)N-urea. Results from one cow were discarded because of leakage of milk from the teats after injection of boluses of [(15)N(15)N]urea. Increasing urea infusion rate linearly increased PUN from 11.4 (0g of urea/h) to 25.9mg/dL (15g of urea/h) and MUN from 10.3 (0g of urea/h) to 23.5 (15g of urea/h) mg of N/dL. The percentage of injected [(15)N(15)N]urea recovered from milk at the time of injection was not affected by urea infusion rate and varied between 65.1 and 73.0%, indicating that a substantial portion of injected [(15)N(15)N]urea was not accounted for by collected milk. The estimated fractional disappearance rate of (15)N-urea from milk to blood (Kurea; per hour) linearly increased from 0.429 (0g of urea/h) to 0.641 per hour (15g of urea/h). Cistern injected [(15)N(15)N]urea diffused within 20 min after injection toward alveoli milk. Calculations with the average Kurea estimated in this

  10. Determination of urea content in urea cream by centrifugal partition chromatography

    Ying-Qun Wang

    2016-04-01

    Full Text Available The objective of this study is to establish a centrifugal partition chromatography (CPC method for determination of the urea ingredient in urea cream. The mechanism of this method is that urea is determined by UV detector at 430 nm after being extracted from the cream and derivatized on line via Ehrlich reaction in rotor of CPC, where the reaction products dissolve in the mobile phase and the cream matrix retains in the stationary phase. The mixed solvent consisting of n-hexane, methanol, hydrochloric acid and p-dimethylaminobenzaldehyde with a ratio of 1000 mL:1000 mL:18 mL:2.0 g is used for solvent system of CPC. The CPC method proposed offers good precision and convenience without complex sample pretreatment processes.

  11. Activation and killing of Dictyostelium discoideum spores with urea.

    Cotter, D A; O'Connell, R W

    1976-12-01

    The optimal conditions for activation of Dictyostellium discoideum spores are an 8 M urea treatment for 30 min. The lag between activation and swelling is 45 min. Lower concentrations of urea do not activate entire spore populations. Incubating spores in 8 M urea for 60 min or treatment with 10 M urea for 30 min results in a lengthening of the post-activation lag and a decrease in the final percentage of germination. Urea-activated spores can be deactivated by azide, cyanide, osmotic pressure, and low-temperature incubation. Activated spores do not germinate if incubated in 1 M urea for 24 h but will complete germination upon resuspension in urea-free buffer. Shocking spores at 45 degrees C in 8 M urea or incubating spores in 4-8 M urea for 10 h at 23.5 degrees C causes inactivation. When suspended in urea-free buffer, a larger percentage of these dead spores release spheroplasts through a longitudinal split in the spore case. Sequential enzyme treatment of spheroplasts with cellulase and pronase causes them to release lysable protoplasts. The data of these experiments suggest that shedding of the outer and middle wall layers during physiological spore swelling may be a physical process rather than an enzymatic one. PMID:1034498

  12. Impact Behaviour of Modified Biopolymer Droplet on Urea Surface

    S. Yon Norasyikin; K. KuZilati; Zakaria, M; S. Suriati

    2014-01-01

    The droplet impact behaviour provides the particle coating characterization during the coating process of controlled release fertiliser. To have a good coating uniformity around the urea granules, it is necessary to enhance the wettabitily properties between the coating material and urea surface. In this study, modified biopolymer is used as the coating material for the controlled release fertilizer. Various compositions of starch:urea:borate were prepared and evaluated for the wettability pr...

  13. The electrophoresis of transferrins in urea/polyacrylamide gels

    Evans, RW; Williams, J.

    1980-01-01

    The denaturation of transferrin by urea has been studied by (a) electrophoresis in polyacrylamide gels incorporating a urea gradient, (b) measurements of the loss in iron-binding capacity and (c) u.v. difference spectrometry. In human serum transferrin and hen ovotransferrin the N-terminal and C-terminal domains of the iron-free protein were found to denature at different urea concentrations.

  14. The effect of urea and urea-modified halloysite on performance of PCL

    Khunová, V.; Kelnar, Ivan; Kristóf, J.; Dybal, Jiří; Kratochvíl, Jaroslav; Kaprálková, Ludmila

    2015-01-01

    Roč. 120, č. 2 (2015), s. 1283-1291. ISSN 1388-6150 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:61389013 Keywords : PCL * urea * halloysite Subject RIV: JI - Composite Materials Impact factor: 2.042, year: 2014

  15. Carcass characteristics of sheep fed diets with slow-release urea replacing conventional urea

    Evanilton Moura Alves

    2014-07-01

    Full Text Available This study aimed to evaluate the effects of adding slow-release urea to replace conventional urea in the diet on carcass characteristics of feedlot sheep. We used 20 Santa Ines x SRD rams, with average body weight of 21.1±1.2 kgand average age of 120 days, distributed in a completely randomized design with 5 treatments. The replacement levels used as treatments were 0, 20, 40, 60, and 80%, composing diets of about 12% crude protein, with 50 % Tifton-85 hay and 50% concentrate. There was no influence of slow release urea on weight at slaughter (35.17 kg, and on hot (16.75 kg and cold (16.24 kg carcass weight, but the yield of these carcasses showed quadratic trend, revealing lower percentages at 48.5 and 47.63% replacement levels, respectively. The weights and yields of cuts did not change, except for the posterior arm, whose values showed a cubic trend. Objective measures of carcass, loin eye area, and subjective evaluations of conformation, finishing and marbling of carcasses were not affected. The subcutaneous fat thickness decreased linearly (4.25 to2.48 mm. The inclusion of slow release urea in the diet changes the yield and reduces subcutaneous fat, however, it does not influence other carcass characteristics.

  16. N-Urea Efficiency In Lowland Rice Applied With Azolla

    Two N-fertilizer experiments have been conducted using urea tablet and prill urea combined with Azolla application. Twelve treatments have been tested using 2 rice varieties namely Atomita-4 and IR-64. To enable the determination of N-urea efficiency 15N labelled urea was used. The experiments were conducted in the dry and wet season (DS and WS) 1994/1995 at the experimental station, pusaka negara, Subang West Java. Data obtained from the two experiments showed that the highest N-urea efficiency was found in Atomita-4 applied with urea-tablet (DS=46,1%, WS= 35,8%). Letting the Azolla grow during one lowland rice growth period could increase the N-urea prill efficiency (±5%) compared when no azolla was applied. Apparently Atomita-4 could use N-urea more efficiently compared to IR-64, showing higher grain yield (atomita-4 DS=6.2 ton ha-1 WS=5.9 ton ha-1) vs IR-64 (DS=5.8 ton ha-1, WS=5.3 ton ha-1). Decreasing the levels of TSP not influence to the urea efficiency at the DS and WS

  17. Effect of urea on the structural dynamics of water

    Rezus, Y. L. A.; Bakker, H. J.

    2006-01-01

    We use polarization-resolved mid-infrared pump-probe spectroscopy to study the effect of urea on the structure and dynamics of water. Surprisingly, we find that, even at high concentrations of urea (8 M), the orientational dynamics of most water molecules are the same as in pure liquid water, showing that urea has a negligible effect on the hydrogen-bond dynamics of these molecules. However, a small fraction of the water molecules (approximately one water molecule per urea molecule) turns out...

  18. Pengolahan Limbah Cair Pabrik Pupuk Urea Menggunakan Advanced Oxidation Processes

    Darmadi Darmadi

    2014-06-01

    Full Text Available Limbah cair pabrik pupuk urea terdiri dari urea dan amonium yang masing-masing mempunyai konsentrasi berkisar antara 1500-10000 ppm dan 400-3000 ppm. Konsentrasi urea yang tinggi di dalam badan air dapat menyebabkan blooming algae dalam ekosistem tersebut yang dapat mengakibatkan kehidupan biota air lain terserang penyakit. Peristiwa ini terjadi karena kurangnya nutrisi bagi biota air dan sedikitnya sinar matahari yang dapat menembusi permukaan air. Disamping kedua hal tersebut di atas, algae juga dapat memproduksi senyawa beracun bagi biota air dan manusia. Penelitian ini bertujuan untuk mengolah urea menggunakan oksidasi konvensional (H2O2 dan Advanced Oxidation Processes (kombinasi H2O2-Fe2+ pada pH 5 dengan parameter yang digunakan adalah variasi konsen-trasi awal H2O2  dan konsentrasi Fe2+. Hasil percobaan menunjukkan bahwa penurunan konsentrasi urea tertinggi diperoleh pada penggunaan reagen fenton (8000 ppm H2O2 dan 500 ppm Fe2+, yaitu dapat menurunkan urea dari konsentrasi awal urea 2566,145 ppm menjadi 0 ppm. Kinetika reaksi dekomposisi urea menjadi amonium dan amonium menjadi nitrit dan nitrat yang diuji mengikuti laju kinetika reaksi orde 1 (satu terhadap urea dan orde satu terhadap amonium dengan konstanta laju reaksi masing-masing k1 = 0,019 dan k2 = 0,022 min-1.

  19. Urea thermolysis and NOx reduction with and without SCR catalysts

    Urea-selective catalytic reduction (SCR) has been a leading contender for removal of nitrogen oxides (deNOx) from diesel engine emissions. Despite its advantages, the SCR technology faces some critical detriments to its catalytic performance such as catalyst surface passivation (caused by deposit formation) and consequent stoichiometric imbalance of the urea consumption. Deposit formation deactivates catalytic performance by not only consuming part of the ammonia produced during urea decomposition but also degrading the structural and thermal properties of the catalyst surface. We have characterized the urea thermolysis with and without the urea-SCR catalyst using both spectroscopic (DRIFTS and Raman) and thermal techniques (thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC)) to identify the deposit components and their corresponding thermal properties. Urea thermolysis exhibits two decomposition stages, involving ammonia generation and consumption, respectively. The decomposition after the second stage leads to the product of melamine complexes, (HNC=NH)x(HNCO)y, that hinder catalytic performance. The presence of catalyst accompanied with a good spray of the urea solution helps to eliminate the second stage. In this work, kinetics of the direct reduction of NOx by urea is determined and the possibility of using additives to the urea solution in order to rejuvenate the catalyst surface and improve its performance will be discussed

  20. Nitrogen Cycling and Losses Under Rice-Wheat Rotations with Coated Urea and Urea in the Taihu Lake Region

    WANG Xiao-Zhi; ZHU Jian-Guo; GAO Ren; H. YASUKAZU; FENG Ke

    2007-01-01

    A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soil with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 (rice) and 250 (wheat) kg N ha-1, and reduced levels, 150 (rice) and 125 (wheat) kg N ha-1, coated urea at two levels, 100 (rice) and 75 (wheat) kg N ha-1, and 150(rice) and 125 (wheat) kg N ha-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both NH3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly (P < 0.001) positively correlated (r = 0.851) with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. However, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yieldof the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.

  1. Quantitative assessment of urea, glucose and ammonia changes in human dental plaque and saliva following rinsing with urea and glucose.

    Singer, D L; Kleinberg, I

    1983-01-01

    The rates of three processes associated with the rise and fall in plaque pH, that normally occur following a urea rinse, were determined: (i) disappearance of urea from plaque, (ii) disappearance of urea from saliva and (iii) formation and disappearance from plaque of the ammonia produced by the plaque bacteria from the urea. Also examined were two processes associated with the fall and rise in pH following a glucose rinse: the disappearance of glucose from plaque and from saliva. Entry into plaque of either urea or glucose during rinsing was immediate; the subsequent disappearance of both from the plaque was slow and followed first-order kinetics. The ammonia formation and urea-disappearance results suggested that clearance of urea from the plaque occurred mainly by bacterial degradation and not by diffusion out of the plaque. The rate constants for ammonia formation and for its subsequent disappearance from the plaque made it clear why a rapid rise and a slow subsequent fall in the pH occurs after urea rinsing. The rate constants enabled calculation of the ammonia produced as a percentage of the urea utilized. Only 16-26 per cent of the urea was recovered as ammonia and the remainder of the urea-N was stored probably as NH2 moieties of certain amino acids. Such storage may enable the plaque bacteria to maintain the pH at an elevated level for an extended period of time by bacterial production of ammonia from these stored compounds after the urea ceases to be available as a source of substrate. PMID:6580848

  2. Cobalt electrodeposition using urea and choline chloride

    The electrochemical behavior of Co(II) in urea-choline chloride-CoCl2 melt was investigated by cyclic voltammetry at 373 K. The results show that the reaction of Co(II) to Co is irreversible and it proceeds via a one-step two electrons transfer process. The diffusion coefficient of Co(II) was estimated to be 1.7 × 10−6 cm2 s−1 at 373 K. Electrodeposition of cobalt was studied at different cathodic potentials (-0.80 to -0.95 V) and at different temperatures (353 to 383 K) in eutectic mixture of choline chloride and urea (1:2 molar ratio). The deposits were characterized using scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). SEM images show that uniform, dense, and compact deposits were obtained at -0.80 V within a temperature range of 353 K to 373 K. EDS and XRD analysis confirm that high-purity metallic Co deposits were obtained

  3. Effect of urea and urea-gamma treatments on cellulose degradation of Thai rice straw and corn stalk

    Cellulose degradation of 20% urea treated and 20% urea-10 kGy gamma treated Thai rice straw and corn stalk showed that combination effect of urea and gamma radiation gave a higher % decrease in neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), cellulose, hemicellulose, and lignin and cutin in comparison with urea effect only for both room temperature storage and room temperature +258 K storage. The results also indicated that cellulose degradation proceeded with time, even at 258 K. A drastic drop to less than half of the original contents in NDF, ADF, and ADL could not be obtained in this study

  4. Effect of urea and urea-gamma treatments on cellulose degradation of Thai rice straw and corn stalk

    Banchorndhevakul, Siriwattana

    2002-08-01

    Cellulose degradation of 20% urea treated and 20% urea-10 kGy gamma treated Thai rice straw and corn stalk showed that combination effect of urea and gamma radiation gave a higher % decrease in neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), cellulose, hemicellulose, and lignin and cutin in comparison with urea effect only for both room temperature storage and room temperature +258 K storage. The results also indicated that cellulose degradation proceeded with time, even at 258 K. A drastic drop to less than half of the original contents in NDF, ADF, and ADL could not be obtained in this study.

  5. Elastic behavior of flexible polyether(urethane–urea) foam materials

    Schuur, van der Martijn; Heide, van der Evert; Feijen, Jan; Gaymans, Reinoud J.

    2004-01-01

    Polyether(urethane–urea) foams (PEUU) with varying urea contents and different polyether segments (PPO and PPO-co-PEO (93/7 w/w)) were compacted to transparent solid plaques via compression molding. The thermal, mechanical and elastic properties of the compacted PEUU materials were studied. With inc

  6. 40 CFR 721.9925 - Aminoethylethylene urea methacrylamide.

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aminoethylethylene urea methacrylamide... Substances § 721.9925 Aminoethylethylene urea methacrylamide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an aminoethylethylene...

  7. 76 FR 15339 - Solid Urea From Russia and Ukraine

    2011-03-21

    ... its notice of institution (75 FR 74746, December 1, 2010) were adequate and that the respondent... COMMISSION Solid Urea From Russia and Ukraine AGENCY: United States International Trade Commission. ACTION... orders on solid urea from Russia and Ukraine. SUMMARY: The Commission hereby gives notice that it...

  8. Effects of nitrogen supply on inter-organ fluxes of urea-N and renal urea-N kinetics in lactating Holstein cows

    Røjen, Betina Amdisen; Theil, Peter Kappel; Kristensen, Niels Bastian

    2011-01-01

    The effects of decreasing ruminal urea infusion in lactating dairy cows fed a basal diet deficient in rumen degradable protein on inter-organ urea-N fluxes, epithelial urea-N extraction, and renal urea-N kinetics were investigated. Eight Danish Holstein cows fitted with a ruminal cannula and...... permanent indwelling catheters in the major splanchnic blood vessels and the gastrosplenic vein were used. The cows were randomly allocated to a triplicate incomplete 3 × 3 Latin square design with 14-d periods. Treatments were continuous ventral ruminal infusion of water, 4.1 g of feed urea/kg of dry...... matter intake, and 8.5 g of feed urea/kg of dry matter intake. Dry matter intake and milk yield decreased linearly with decreasing urea infusion. Arterial blood urea-N and ruminal ammonia concentrations decreased linearly with decreasing urea infusion. In absolute amounts, the urea-N recycling did not...

  9. Hydrogen bonding of formamide, urea, urea monoxide and their thio-analogs with water and homodimers

    Damanjit Kaur; Shweta Khanna

    2014-11-01

    Ab initio and DFT methods have been employed to study the hydrogen bonding ability of formamide, urea, urea monoxide, thioformamide, thiourea and thiourea monoxide with one water molecule and the homodimers of the selected molecules. The stabilization energies associated with themonohydrated adducts and homodimers’ formation were evaluated at B3LYP/6-311++G** and MP2/6-311++G∗∗ levels. The energies were corrected for zero-point vibrational energies and basis set superposition error using counterpoise method. Atoms in molecules study has been carried out in order to characterize the hydrogen bonds through the changes in electron density and laplacian of electron density. A natural energy decomposition and natural bond orbital analysis was performed to understand the nature of hydrogen bonding.

  10. Utilization of urea-nitrogen-15 in ruminants

    In Merino sheep a series of experiments were carried out investigating exogenous and endogenous urea utilization. On the experimental sheep with isolated jejunum, rumen and intestine fistula, re-entral intestine cannulae, and after intra-ruminal or intra-intestinal 15N-urea administration it was found that urea-15N takes part in the nitrogen recycling, and is utilized in the nitrogen pool. In experiments with synthetic protein-free diet, low protein diet and high nitrogen diet, after the intravenous administration of 15N-urea the following findings were made: The results of experiments with synthetic diet, where the only nitrogen source was perorally (for 3-6 months) and then intravenously (for 3 months) administered urea, indicated the ability of ruminants to replace fully the nitrogen in the feed under certain conditions by increased endogenous urea recirculation. The results of the experiments with various nitrogen intakes showed that considerable amounts of urea-15N (44-96% from the given dose) were retained. Nitrogen compounds synthetized from blood urea-15N were recycled through the alimentary tract. Its secretion predominated in the forestomachs, abomasum and duodenum, and its reabsorption took place in the intestinal tract. From the 15N incorporated into the nitrogenous substances which passed through the duodenum, 73-84% was reabsorbed. The retained 15N was incorporated into the microbial and plasma proteins and its amide-N. On the basis of these results it is concluded that in addition to the rumeno-hepatal circulation, the entero-hepatal circulation of nitrogenous substances, including endogenous nitrogen, also plays an important role quantitatively and perhaps qualitatively in the process of re-utilizing the blood urea N for proteosynthesis and synthesis of other N-metabolites in ruminants. The hydrolysis of endogenous urea in the gastro-intestinal tract of ruminants and its utilization is a natural process indispensable for the maintenance of nitrogen

  11. Synthesis of aluminum nitride nanoparticles by a facile urea glass route and influence of urea/metal molar ratio

    Attention toward nanosized aluminum nitride (AlN) was rapidly increasing due to its physical and chemical characteristics. In this work, nanocrystalline AlN particles were prepared via a simple urea glass route. The effect of the urea/metal molar ratio on the crystal structure and morphology of nanocrystalline AlN particles was studied using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results revealed that the morphology and the crystal structure of AlN nanoparticles could be controlled by adjusting the urea/metal ratio. Furthermore, a mixture of Al2O3 and h-AlN was detected at the urea/metal molar ratio of 4 due to the inadequate urea content. With increasing the molar ratio, the pure h-AlN was obtained. In addition, the nucleation and growth mechanisms of AlN nanocrystalline were proposed.

  12. In vitro slow-release urea characteristics under different molasses levels contained in rice straw based diets

    D. Kardaya; K.G Wiryawan; A. Parakkasi; H.M. Winugroho

    2013-01-01

    Slow-release urea characteristics of zinc-urea, zeolites-urea, and zeolites-zinc-urea were examined using in vitro techniques. The objective of this experiment was to study the in vitro slow-release urea characteristics of zinc-urea, zeolites-urea, and zeolites-zinc-urea under different molasses concentrations in relation to the ruminal fermentative changes observed in different incubation time. The experimental design employed was randomized block design with a 4 x 3 factorial arrangement pl...

  13. Urea encapsulation in modified starch matrix for nutrients retention

    Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariff, Mohd. Hazwan Bin Mohd.; Ariwahjoedi, Bambang

    2014-10-01

    It has been estimated that 20-70% of the used urea goes to the environment via leaching, nitrification and volatilization which not only harms the environment but also reduces the urea efficiency. By coating the urea granules, the farmers can achieve high urea performance through controlling the excess release of nitrogen. Up until now, different materials have been tested for nutrients retention. However, most of them are either expensive or unfriendly to the environment. Being cheap and biodegradable materials, the starches may also be used to coat the urea fertilizer for controlling the nutrients release. However, the pure starches do not meet the standards set by many industrial processes due to their slow tacking and too low viscosities and should be modified for getting smooth, compact and mechanically stronger coatings. In these studies, the tapioca starch was modified by reacting it with urea and different masses of borax. The prepared solutions were used to coat the urea granules of 3.45 mm average diameter. Different volumes (1, 1.5 and 2 mL) of each solution were used to coat 30 g of urea fluidized above the minimum level of fluidization. It was noticed that the coating thickness, percent coating, dissolution rate and percent release follow an increasing trend with an increase of solution volume; however, some random results were obtained while investigating the solution volume effects on the percent release. It was seen that the nutrients percent release over time increases with an increase in solution volume from 1 to 1.5 mL and thereafter reaches to a steady state. It confirms that the 1.5 mL of solution for 30 g urea samples will give the optimized coating results.

  14. The importance of urea-molasses blocks and bypass protein in animal production: The situation in Bangladesh

    Molasses remains underutilized as an animal feed in Bangladesh. Urea and molasses are used for supplementation of fibrous feeds in many countries. Used in sprayed form on straw or in liquid form, urea-molasses caused practical problems in village farming conditions owing to urea toxicity from higher intake by livestock, as well as difficulties in handling, storage and transport to remote villages. To overcome these problems and to produce a supply of easily available energy and nitrogen to ruminants, a simple method has been developed for making urea-molasses blocks with locally available ingredients and equipment at the farm level in the villages. To evaluate the nutritional potential of urea-molasses blocks fed to livestock on a straw based diet, a study has been conducted on the performance of livestock under on-farm conditions. Results from experiments on the nutritional value of the block are reported. Daily live weight gain, milk yield and draught output of cattle increased significantly. A similar positive response in the performance of sheep and goats was also observed. Once the supply of rumen fermentable nitrogen and energy is ensured to optimize the rate of degradation of fibrous substrate with supplementation of urea-molasses block lick, the next limitation to production is the availability of amino acids absorbed from the intestine. To overcome this limitation, protein with a low rate of degradation, such as fish meal, could be used as bypass protein. Several experiments were conducted on the effect of supplementation of bypass protein on the performance of cattle, sheep and goats in both on-station and on-farm conditions. Results indicated a positive response in daily live weight gain, milk yield and draught power output. 31 refs, 6 figs, 6 tabs

  15. Titanium erosion in urea strippers and emerging technologies

    High Pressure Urea Stripper is the heart of a Urea Plant. The process fluids in the high pressure streams are generally very corrosive in nature. This is basically a falling film type exchanger/ evaporator and high pressure and temperatures here make the process fluid most corrosive compared to other regions in Urea Plant. The equipment design takes into account a trade off between cost and corrosion resistance against the aggressive process media. This paper explains erosion phenomenon/ counter measures in Titanium strippers as experienced by FFC at its plants and emerging technologies to improve life and reliability of this equipment. (author)

  16. Anatomy of energetic changes accompanying urea-induced protein denaturation

    Auton, Matthew; Holthauzen, Luis Marcelo F.; Bolen, D. Wayne

    2007-01-01

    Because of its protein-denaturing ability, urea has played a pivotal role in the experimental and conceptual understanding of protein folding and unfolding. The measure of urea's ability to force a protein to unfold is given by the m value, an experimental quantity giving the free energy change for unfolding per molar urea. With the aid of Tanford's transfer model [Tanford C (1964) J Am Chem Soc 86:2050–2059], we use newly obtained group transfer free energies (GTFEs) of protein side-chain an...

  17. Hydrolyzable polyureas bearing hindered urea bonds.

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications. PMID:25406025

  18. Highly sensitive urea sensing with ion-irradiated polymer foils

    Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms – tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

  19. IRIS TOXICOLOGICAL REVIEW OF UREA (EXTERNAL REVIEW DRAFT)

    EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Urea that when finalized will appear on the Integrated Risk Information System (IRIS) database.

  20. IRIS Toxicological Review of Urea (Interagency Science Discussion Draft)

    EPA is releasing the draft report, Toxicological Review of Urea,, that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment Development Process. C...

  1. Impact Behaviour of Modified Biopolymer Droplet on Urea Surface

    S. Yon Norasyikin

    2014-01-01

    Full Text Available The droplet impact behaviour provides the particle coating characterization during the coating process of controlled release fertiliser. To have a good coating uniformity around the urea granules, it is necessary to enhance the wettabitily properties between the coating material and urea surface. In this study, modified biopolymer is used as the coating material for the controlled release fertilizer. Various compositions of starch:urea:borate were prepared and evaluated for the wettability properties. The wettability properties measured are the maximum spreading diameter, dynamic contact angle and surface tension. The high speed Charged Couple Device (CCD camera was used to capture the images of this droplet impact behaviour. From this analysis, it is indicated that a composition of starch:urea:borate (50:15:2.5 has the best wettability characteristic and thus are suitable to be used as a coating material.

  2. Hydrogen production via urea electrolysis using a gel electrolyte

    King, Rebecca L.; Botte, Gerardine G.

    2011-03-01

    A technology was demonstrated for the production of hydrogen and other valuable products (nitrogen and clean water) through the electrochemical oxidation of urea in alkaline media. In addition, this process remediates toxic nitrates and prevents gaseous ammonia emissions. Improvements to urea electrolysis were made through replacement of aqueous KOH electrolyte with a poly(acrylic acid) gel electrolyte. A small volume of poly(acrylic acid) gel electrolyte was used to accomplish the electrochemical oxidation of urea improving on the previous requirement for large amounts of aqueous potassium hydroxide. The effect of gel composition was investigated by varying polymer content and KOH concentrations within the polymer matrix in order to determine which is the most advantageous for the electrochemical oxidation of urea and production of hydrogen.

  3. Deprotection of oximes using urea nitrate under microwave irradiation

    P T Perumal; M Anniyappan; D Muralidharan

    2004-08-01

    A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95 : 5), under microwave irradiation within 2 min, in good yields is reported.

  4. Influence of Ficoll on urea induced denaturation of fibrinogen

    Sankaranarayanan, Kamatchi; Meenakshisundaram, N.

    2016-03-01

    Ficoll is a neutral, highly branched polymer used as a molecular crowder in the study of proteins. Ficoll is also part of Ficoll-Paque used in biology laboratories to separate blood to its components (erythrocytes, leukocytes etc.,). Role of Ficoll in the urea induced denaturation of protein Fibrinogen (Fg) has been analyzed using fluorescence, circular dichroism, molecular docking and interfacial studies. Fluorescence studies show that Ficoll prevents quenching of Fg in the presence of urea. From the circular dichroism spectra, Fg shows conformational transition to random coil with urea of 6 M concentration. Ficoll helps to shift this denaturation concentration to 8 M and thus constraints by shielding Fg during the process. Molecular docking studies indicate that Ficoll interacts favorably with the protein than urea. The surface tension and shear viscosity analysis shows clearly that the protein is shielded by Ficoll.

  5. Influence of Ficoll on urea induced denaturation of fibrinogen

    Kamatchi Sankaranarayanan

    2016-03-01

    Full Text Available Ficoll is a neutral, highly branched polymer used as a molecular crowder in the study of proteins. Ficoll is also part of Ficoll-Paque used in biology laboratories to separate blood to its components (erythrocytes, leukocytes etc.,. Role of Ficoll in the urea induced denaturation of protein Fibrinogen (Fg has been analyzed using fluorescence, circular dichroism, molecular docking and interfacial studies. Fluorescence studies show that Ficoll prevents quenching of Fg in the presence of urea. From the circular dichroism spectra, Fg shows conformational transition to random coil with urea of 6 M concentration. Ficoll helps to shift this denaturation concentration to 8 M and thus constraints by shielding Fg during the process. Molecular docking studies indicate that Ficoll interacts favorably with the protein than urea. The surface tension and shear viscosity analysis shows clearly that the protein is shielded by Ficoll.

  6. Digestibility of pelleted rations containing diverse potato flour and urea

    Isabel Martinele

    2015-11-01

    Full Text Available The aim of this study was to evaluate ruminal in situ degradability and in vitro digestibility of dry matter (DM in concentrate supplements containing diverse potato flour pelletized with urea (0%, 4%, 8%, and 12% DM. Samples of feeds were incubated for 0, 2, 4, 8, 12, 24, 36, and 48h in the rumen of four fistulated sheep. Level of urea added had no significant effect (P>;0.05 on the soluble fraction (a or potentially degradable fraction (b of the pellets and ranged from 2.1% to 12.2% and 72.9% to 87.5%, respectively. Quadratic effects (P=0.03 of the rate of degradation of fraction "b" ranged from 4.75% h-1to 7.39% h-1; the estimated maximum value at 7.4% h-1was obtained when 5.9% urea was added to the pellet. Quadratic effects (P≤0.02 of the level of urea added to the pellets on the effective degradability (ED of DM were evaluated after considering rumen passage rates of 2.5% h-1and 8% h-1; the maximum values of ED calculated under these rumen passage rates were estimated at 6.3% to 7.3% urea in the pellets. The in vitro digestibility of DM of the pellets showed a quadratic effect (P=0.02 at different levels of urea, with a maximum value of 96.9% achieved when 7.9% urea was added to the pellets. Our results suggest that the addition of 6-8% urea to pelleted feed promotes an increase in the in vitro digestibility and ED of DM.

  7. Urea coated with oxidized charcoal reduces ammonia volatilization

    Diogo Mendes de Paiva; Reinaldo Bertola Cantarutti; Gelton Geraldo Fernandes Guimarães; Ivo Ribeiro da Silva

    2012-01-01

    Urea is the most consumed nitrogen fertilizer in the world. However, its agronomic and economic efficiency is reduced by the volatilization of NH3, which can reach 78 % of the applied nitrogen. The coating of urea granules with acidic compounds obtained by charcoal oxidation has the potential to reduce the volatilization, due to the acidic character, the high buffering capacity and CEC. This work aimed to evaluate the effect of HNO3-oxidized carbon on the control of NH3 volatilization. These ...

  8. Exploring the cocrystallization potential of urea and benzamide.

    Cysewski, Piotr; Przybyłek, Maciej; Ziółkowska, Dorota; Mroczyńska, Karina

    2016-05-01

    The cocrystallization landscape of benzamide and urea interacting with aliphatic and aromatic carboxylic acids was studied both experimentally and theoretically. Ten new cocrystals of benzamide were synthesized using an oriented samples approach via a fast dropped evaporation technique. Information about types of known bi-component cocrystals augmented with knowledge of simple binary eutectic mixtures was used for the analysis of virtual screening efficiency among 514 potential pairs involving aromatic carboxylic acids interacting with urea or benzamide. Quantification of intermolecular interaction was achieved by estimating the excess thermodynamic functions of binary liquid mixtures under supercooled conditions within a COSMO-RS framework. The smoothed histograms suggest that slightly more potential pairs of benzamide are characterized in the attractive region compared to urea. Finally, it is emphasized that prediction of cocrystals of urea is fairly direct, while it remains ambiguous for benzamide paired with carboxylic acids. The two known simple eutectics of urea are found within the first two quartiles defined by excess thermodynamic functions, and all known cocrystals are outside of this range belonging to the third or fourth quartile. On the contrary, such a simple separation of positive and negative cases of benzamide miscibility in the solid state is not observed. The difference in properties between urea and benzamide R2,2(8) heterosynthons is also documented by alterations of substituent effects. Intermolecular interactions of urea with para substituted benzoic acid analogues are stronger compared to those of benzamide. Also, the amount of charge transfer from amide to aromatic carboxylic acid and vice versa is more pronounced for urea. However, in both cases, the greater the electron withdrawing character of the substituent, the higher the binding energy, and the stronger the supermolecule polarization via the charge transfer mechanism. PMID:27052722

  9. Comparison of arteriovenous fistula recirculation by thermodilution and urea

    To compare arteriovenous fistula recirculation by thermodilution technique and urea based two needle slow flow method. Thirty one patients with end stage renal disease on maintenance hemodialysis through arteriovenous fistula were selected on purposive design. Hemodialysis was done on Fresenius 4008 S machines with in-built blood temperature monitoring module to measure recirculation by thermodilution method. Recirculation by the thermodilution method was calculated with the blood flow rate of 300 milliliter /minute and dialysate flow of 500ml /minute. Access recirculation by urea based method was calculated by taking three blood samples for blood urea nitrogen. Two samples were taken simultaneously from the arterial and venous ports respectively. Third sample was taken from the arterial port after slowing the blood flow pump to 50 milliliter/minute and waiting for 30 seconds. Relationship of thermodilution and urea based method was assessed by calculating Pearson correlation coefficient (r). Out of 31 patients, 18 (58.1%) were males, whereas 13 (41.9%) were females. Their mean age was 47.29 +- 13.42 years. Mean access recirculation by thermodilution method was 7.31+- 3.03 and by urea based method was 9.55 +- 6.64. Correlation coefficient (r) was 0.706 with p-value of < 0.001, which was highly significant. Arteriovenous fistula recirculation calculated by thermo-dilution technique has a strong correlation with the recirculation calculated by the two-needle urea based method. (author)

  10. Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase.

    Manickam, Manoj; Pillaiyar, Thanigaimalai; Boggu, PullaReddy; Venkateswararao, Eeda; Jalani, Hitesh B; Kim, Nam-Doo; Lee, Seul Ki; Jeon, Jang Su; Kim, Sang Kyum; Jung, Sang-Hun

    2016-07-19

    Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH. PMID:27092411

  11. Slow-release urea in supplement fed to beef steers

    Ana Paula Gonçalves

    2015-02-01

    Full Text Available Replacing regular urea (RU by slow-release urea (SRU at two levels of non-protein nitrogen (NPN in concentrate, offered with low-quality roughage, was evaluated in beef steers on dry matter intake (DMI, ruminal fermentation parameters, plasma urea nitrogen (PUN, total tract apparent digestibility of diets and in situ degradability of nitrogen sources. Eight ruminally cannulated steers were allocated into two 4x4 Latin squares, totalizing four treatments: 40 NPN/0 SRU: 40% of concentrate crude protein (CP as NPN, resulting from 0% of SRU and 100% of RU; 40 NPN/50 SRU: 40% of concentrate CP as NPN, resulting from 50% of SRU and 50% of RU; 40 NPN/100 SRU: 40% of concentrate CP as NPN, resulting from 100% of SRU and 0% of RU; 80 NPN/100 SRU: 80% of concentrate CP as NPN, resulting from 100% of SRU and 0% of RU. Results showed that partial substitution of regular urea by slow-release urea did not alter dry matter intake, pattern of ruminal fermentation or plasma urea nitrogen concentrations and increased the total tract apparent digestibility of crude protein in steers diets. The increase in non-protein nitrogen content in crude protein of the concentrate could compromise feed intake and the efficiency of nutrient utilization in the steers fed complete diets based on low quality forage.

  12. Preoperative Evaluating of Kidney Function: Urea and Creatinine Levels

    M Kadkhodayi

    2001-05-01

    Full Text Available Surgeons require determining urea and creatinine in patients undergoing surgery routinely as these parameters allow a judgment on the function of the kidneys. It is suggested that a normal urea level of blood is always associated with a normal value of creatinine in the same patient and, therefore, determination of urea alone suffices for this judgment. This spares collection of large volumes of blood sample for manual determination of creatinine, particularly in children and newborns. In this survey we analyzed the results of urea and creatinine estimation in blood samples of 1315 persons. In 95% of persons with a blood urea level of lower than 25 mg/dl and 99.8% havinglower than 20 mg/dl, the serum creatinine level was lower than 1 mg/dl. This confirms the suggestion that a person with a normal blood urea level will have a normal creatinine level too and an estimation of both of them is an unnecessary burden for the patient and the laboratory as well.

  13. Synthesis, enzyme inhibition and anticancer investigation of unsymmetrical 1,3-disubstituted ureas

    Mustafa Sana; Perveen Shahnaz; Khan Ajmal

    2014-01-01

    In this research work seventeen urea derivatives, including five new derivatives N-mesityl-N'-(3-methylphenyl)urea (2), N-(3-methoxyphenyl)-N'-(3-methylphenyl)urea (4), N-mesityl-N'-(4-methylphenyl)urea (6), N-(1,3-benzothiazol-2-yl)-N'-(3-methylphenyl)urea (9) and N-(2-methylphenyl)-2-oxo-1-pyrrolidinecarboxamide (15) have synthesized by reacting ortho, meta and para tolyl isocyanate with primary and secondary amines by previously reported method. We...

  14. Preparation of Urea Nitrogen Adsorbent of Complex Type and Adsorption Capacity of Urea Nitrogen onto the Adsorbent

    2006-01-01

    The urea nitroge n adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose (CDAC) and immobilized urease in gelatin membrane (IE), was prepared. The cellulose, the dialdehyde cellulose (DAC) and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10:1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37 ℃.

  15. Metabolic Induction of Lactic Acid Bacteria for Urea Removal

    ZHANG Su-ai; BAI Yu; LI Dong-xia; CHEN Bo-li; SONG Cun-jiang; QIAO Ming-qiang; KONG De-ling; YU Yao-ting

    2009-01-01

    Objective:This study aims to induce nonpathogenic bacteria for urea removal as a potential treatment in renal failure. Methods:Lactococus lactis MG1363 was induced by repeated exposure to urea-rich culture media, the ability to remove urea from the media was evaluated. The effect of gastroenteric environment, such as low pH, bile salt and antiagonistic properties were investigated.The antimicrobial activities on pathogenic E.coli and S.aureus in the intestinal tract and the antibiotic tolerance of the induced bacteria were also studied.Results: Induced bacteria of 50 generations could decrease the urea level from 40.01 mg/dL to 32.99 mg/dL after 24 h. The bacteria could grow after treatment at pH3.0 for 2 h and in 0.1% bile salt for 6 h, and the urea removal activity was retained in such simulated gastroenteric environment. The removal of urea was significantly enhanced to 35.8% by addition of Ni2+ to the culture medium at neutral pH. It was also found that the induced bacteria could inhibit the growth of E.coli and S.aureus, and tolerate ampicillin,gentamicin,roxithromycin,tetracycline and cefradine. The safety tests were performed by feeding normal rats with either Lactococus lactis MG1363 or induced Lactococus lactis MG1363. The two materials did not cause any changes in blood cells, blood biochemical indexes and body weight. Conclusion: These results suggest that the induced Lactococus lactis MG1363 has the potential as an oral therapy for the removal of urea in patients with renal failure.

  16. Endogenous retinoic acid activity in principal cells and intercalated cells of mouse collecting duct system.

    Yuen Fei Wong

    Full Text Available BACKGROUND: Retinoic acid is the bioactive derivative of vitamin A, which plays an indispensible role in kidney development by activating retinoic acid receptors. Although the location, concentration and roles of endogenous retinoic acid in post-natal kidneys are poorly defined, there is accumulating evidence linking post-natal vitamin A deficiency to impaired renal concentrating and acidifying capacity associated with increased susceptibility to urolithiasis, renal inflammation and scarring. The aim of this study is to examine the presence and the detailed localization of endogenous retinoic acid activity in neonatal, young and adult mouse kidneys, to establish a fundamental ground for further research into potential target genes, as well as physiological and pathophysiological roles of endogenous retinoic acid in the post-natal kidneys. METHODOLOGY/PRINCIPAL FINDINGS: RARE-hsp68-lacZ transgenic mice were employed as a reporter for endogenous retinoic acid activity that was determined by X-gal assay and immunostaining of the reporter gene product, β-galactosidase. Double immunostaining was performed for β-galactosidase and markers of kidney tubules to localize retinoic acid activity. Distinct pattern of retinoic acid activity was observed in kidneys, which is higher in neonatal and 1- to 3-week-old mice than that in 5- and 8-week-old mice. The activity was present specifically in the principal cells and the intercalated cells of the collecting duct system in all age groups, but was absent from the glomeruli, proximal tubules, thin limbs of Henle's loop and distal tubules. CONCLUSIONS/SIGNIFICANCE: Endogenous retinoic acid activity exists in principal cells and intercalated cells of the mouse collecting duct system after birth and persists into adulthood. This observation provides novel insights into potential roles for endogenous retinoic acid beyond nephrogenesis and warrants further studies to investigate target genes and functions of

  17. Urease immobilized fluorescent gold nanoparticles for urea sensing.

    Parashar, Upendra Kumar; Nirala, Narsingh R; Upadhyay, Chandan; Saxena, P S; Srivastava, Anchal

    2015-05-01

    We report a surfactant-free synthesis of monodispersed gold nanoparticles (AuNPs) with average size of 15 nm. An approach for visual and fluorescent sensing of urea in aqueous solution based on shift in surface plasmon band (SPB) maxima as well as quench in fluorescence intensity. To enable the urea detection, we functionalized the thiol-capped gold nanoparticles with urease, the enzyme specific to urea using carbodiimide chemistry. The visible color changed of the gold colloidal solution from red to blue (or purple); this was evident from quenching in absorbance and fluorescence intensity, is the principle applied here for the sensing of urea. The solution turns blue when the urea concentration exceeds 8 mg/dL which reveals visual lower detection limit. The lower detection limits governed by the fluorescence quenching were found 5 mg/dL (R(2) = 0.99) which is highly sensitive and selective compared to shift in SPB maxima. The approach depicted here seems to be important in clinical diagnosis. PMID:25809996

  18. Analysis Method for Isotope Abundance of 13C-urea

    In order to better control the effective content of 13C in 13C-urea reagent, the technique and the conditions for converting 13C-urea sample into the sample gas used in gas isotopic mass spectrometry detection by means of nitrite oxidation method and high temperature burning method were investigated. The results showed that the 13CO2 gas obtained from nitrite oxidation method with 2 mg 13C-urea samples and that from high temperature burning method with 1 mg 13C-urea samples can satisfy the demand of the mass spectrometer detection. The sodium nitrite reagent dosage, the reaction temperature and the reaction time of the sample gas preparation, as well as the treatment effect of copper oxide reagent etc.were sought experimentally. The high abundance 13C-urea testing was completed, the calculation and expression of the detection data were also determined, and the standard deviation were less than ±0.07%. (authors)

  19. Urea cycle disorders: brain MRI and neurological outcome

    Bireley, William R. [University of Colorado, Department of Radiology, Aurora, CO (United States); Van Hove, Johan L.K. [University of Colorado, Department of Genetics and Inherited Metabolic Diseases, Aurora, CO (United States); Gallagher, Renata C. [Children' s Hospital Colorado, Department of Genetics and Inherited Metabolic Diseases, Aurora, CO (United States); Fenton, Laura Z. [Children' s Hospital Colorado, Department of Pediatric Radiology, Aurora, CO (United States)

    2012-04-15

    Urea cycle disorders encompass several enzyme deficiencies that can result in cerebral damage, with a wide clinical spectrum from asymptomatic to severe. The goal of this study was to correlate brain MRI abnormalities in urea cycle disorders with clinical neurological sequelae to evaluate whether MRI abnormalities can assist in guiding difficult treatment decisions. We performed a retrospective chart review of patients with urea cycle disorders and symptomatic hyperammonemia. Brain MRI images were reviewed for abnormalities that correlated with severity of clinical neurological sequelae. Our case series comprises six urea cycle disorder patients, five with ornithine transcarbamylase deficiency and one with citrullinemia type 1. The observed trend in distribution of brain MRI abnormalities as the severity of neurological sequelae increased was the peri-insular region first, extending into the frontal, parietal, temporal and, finally, the occipital lobes. There was thalamic restricted diffusion in three children with prolonged hyperammonemia. Prior to death, this site is typically reported to be spared in urea cycle disorders. The pattern and extent of brain MRI abnormalities correlate with clinical neurological outcome in our case series. This suggests that brain MRI abnormalities may assist in determining prognosis and helping clinicians with subsequent treatment decisions. (orig.)

  20. The Formation and characteristics of Acrylonitrile/Urea Inclusion Compound

    Zou, Jun-Ting; Pang, Wen-Min; Shi, Lei; Lu, Fei

    2012-01-01

    The formation process and composition of the acrylonitrile/urea inclusion compounds (AN/UIC) with different aging times and AN/urea molar feed ratios are studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It is suggested that DSC could be one of the helpful methods to determine the guest/host ratio and the heat of decomposition. Meanwhile, the guest/host ratio and heat of deformation are obtained, which are 1.17 and 5361.53 J/mol, respectively. It is found that the formation of AN/UIC depends on the aging time. The formation process ends after enough aging time and the composition of AN/UIC becomes stable. It is suggested AN molecules included in urea canal lattice may be packed flat against each other. XRD results reveal that once AN molecules enter urea lattice, AN/UIC are formed, which possess the final structure. When AN molecules are sufficient, the content of AN/UIC increased as aging time prolonging until urea tunnels are saturated by AN.

  1. Modeling and measurement of boiling point elevation during water vaporization from aqueous urea for SCR applications

    Dan, Ho Jin; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of)

    2016-03-15

    Understanding of water vaporization is the first step to anticipate the conversion process of urea into ammonia in the exhaust stream. As aqueous urea is a mixture and the urea in the mixture acts as a non-volatile solute, its colligative properties should be considered during water vaporization. The elevation of boiling point for urea water solution is measured with respect to urea mole fraction. With the boiling-point elevation relation, a model for water vaporization is proposed underlining the correction of the heat of vaporization of water in the urea water mixture due to the enthalpy of urea dissolution in water. The model is verified by the experiments of water vaporization as well. Finally, the water vaporization model is applied to the water vaporization of aqueous urea droplets. It is shown that urea decomposition can begin before water evaporation finishes due to the boiling-point elevation.

  2. Evidence that the adverse effect of urea fertilizer on seed germination in soil is due to ammonia formed through hydrolysis of urea by soil urease

    Bremner, John M.; Krogmeier, Michael J.

    1989-01-01

    Studies using seeds of wheat (Triticum aestivum L.), rye (Secale cereale L.), barley (Hordeum vulgare L.), and corn (Zea mays L.) indicated that the adverse effect of urea fertilizer on seed germination in soil is due to ammonia formed through hydrolysis of urea by soil urease and is not due to urea itself, to urea fertilizer impurities such as biuret, or to nitrite formed by nitrification of urea nitrogen. Support for this conclusion was obtained from (i) comparison of the effects on seed ge...

  3. Android integrated urea biosensor for public health awareness

    Pranali P. Naik

    2015-03-01

    Full Text Available Integration of a biosensor with a wireless network on the Android 4.2.1 (Jelly Bean platform has been demonstrated. The present study reports an android integrated user friendly Flow injection analysis-Enzyme thermistor (FIA-ET urea biosensor system. This android-integrated biosensor system will facilitate enhanced consumer health and awareness alongside abridging the gap between the food testing laboratory and the concerned higher authorities. Data received from a flow injection mode urea biosensor has been exploited as an integration point among the analyst, the food consumer and the responsible higher authorities. Using the urea biosensor as an example, an alarm system has also been demonstrated both graphically and through text message on a mobile handset. The presented sensor integrated android system will also facilitate decision making support system in various fields of food quality monitoring and clinical analysis.

  4. The fate of ingested 14C-urea in the urea breath test for Helicobacter pylori infection

    The metabolic fate of the radioactive carbon in the 14C-urea breath test for Helicobacter pylori was investigated in 18 subjects. After ingestion of labelled urea, breath was sampled for 24 h, and urine was collected for 3 days. Subjects were designated high or low expirers on the basis of their breath counts, and this agreed well with H. pylori serologic analyses. When given 185 or 37 kBq of 14C-urea, 51% of the label was recovered from the breath of high expirers, and 7% from the breath of low expirers. The mean combined urinary and breath recovery for high expirers was 86%, and for low expirers it was 97%. It is concluded that the long-term retention of 14C from ingested 14C-urea is low. The results enable a more accurate estimation to be made of radiation exposure resulting from the 14C-urea breath test. 16 refs., 3 figs., 2 tabs

  5. Ammonia Volatilization from Urea Incorporation with wheat and Maize Straw on a Loamy Soil in China

    Dong, Wenxu; Hu, Chunsheng; Zhang, Yuming; Junfang, Cui

    2009-01-01

    Effects of incorporating urea with wheat or corn straw at different soil moisture levels on ammonia volatilization were measured in a field experiment using a sponge-tripping method with KCl extraction. Over a 10-day period following incubation NH3 volatilization peaked on day 3 for urea alone, while highest emission rates were observed on day 2 for urea plus wheat or corn straw. Total NH3 losses decreased in the order: urea > urea + maize straw > urea + wheat straw. Emissions of NH3 were mor...

  6. Biodegraded and Polyurethane Drape-formed Urea Fertilizer

    WANG Yong; LI Jian; CHEN Xiaoyao

    2005-01-01

    Natural water absorbent konjac flour participates in synthesizing biodegraded and polyurethane foamed drape, which is used to release urea slowly.The experimental results indicate that the slowly-releasing velocity of urea nitrogen and the degrading velocity of the drape can be controlled by regulating the thicknesses of drapes, the amount of konjac flour and the water content. In addition, the biodegradability of the drape was investigated by burying the specimens in earth afterwards,and results show this drape can be degraded naturally.

  7. Reinvestigation of growth of urea thiosemicarbazone monohydrate crystal

    Srinivasan, Bikshandarkoil R.; Raghavaiah, Pallepogu; Nadkarni, V. S.

    2013-08-01

    The reaction of urea with thiosemicarbazide in 1:1 mole ratio in aqueous solution does not result in the formation of urea thiosemicarbazone monohydrate crystal, as reported by Hanumantharao, Kalainathan and Bhagavannarayana [Spectrochim. Acta A91 (2012) 345-351]. A reinvestigation of the reported reaction reveals that the crystal obtained is the starting material namely thiosemicarbazide, which has been unambiguously confirmed with the aid of infrared and 1H NMR spectra and single crystal X-ray structure determination. Analysis of 1H NMR spectrum reveals that thiosemicarbazide exhibits thione-thiol tautomerism in solution. In contrast, thiosemicarbazide exists as the thione tautomer in the solid state.

  8. IMPROVING THE EFFICIENCY OF CARBON DIOXIDE SUPPLY ON UREA SYNTHESIS

    Лавренченко, Г. К.; Копытин, А. В.; Афанасьев, С. В.; Рощенко, О. С.

    2011-01-01

    Aggregates of urea synthesis are reconstructed with the purpose decrease in specific expenses and increase their productivity. Supply of additional quantities of carbon dioxide and ammonia is necessary to increase production volumes of urea. In most cases there is a problem with the supply of СО2, as the equipment for its compression is not any necessary reserves. Installation for supply of carbon dioxide using a pump is considered. For liquefaction of CO2 at low pressure the cold of the liqu...

  9. On-farm treatment of straws and stovers with urea

    The nutritional value of cereal crop residues to ruminants is constrained by low N and high fibre contents. These constraints can be alleviated by treatment with alkali, the most suitable of which, for smallholder use, is urea. However, it has not widely been used in Africa. Whilst in some areas, cost and availability of urea will be a factor, it may also be that the flexibility of the technique is not appreciated. The scope for adaptation at each stage of the procedure is reviewed, showing that the farmer does have options to develop a system suitable for a range of conditions. (author)

  10. Performance of phosphoric acid activated montmorillonite as buffer materials for radioactive waste repository

    In this study, the performance of phosphoric acid activated montmorillonite (PAmmt) was evaluated by cesium ions adsorption experiments. The PAmmt samples were obtained by activating with 1, 3 and 5 mol L-1 of phosphoric acid, respectively under reflux for 3, 12, and 24 h. Experimental results demonstrated that the treatment of raw K-10 montmorillonite with phosphoric acid increased the materials' affinity for Cs uptake and no significant amount of suspension solids were produced. A relatively insignificant variation in the CEC value was observed. Furthermore, PAmmt also showed high adsorption selectivity toward Cs ions. The improved sorptive properties were mainly related to the increased surface area and the relatively higher surface charge density. Increased specific surface area was the resulted from partial decomposition of lamellar structure of mmt; while the higher surface charge density was caused by the protonation of octahedral Al-OH sites during the acid activation. Generally speaking, stronger acid concentration and longer activation times would produce relatively more decomposed PAmmt particles. However, as the activation exceeds 3 h, the precipitation of Si4+ would passivate PAmmt against further acid attacks. Based upon our results, acid activation by phosphoric acid could produce PAmmt samples with high sorption capacity and selectivity, and good structural integrity, which are beneficial to be used at radioactive waste repository.

  11. Removal of Heavy Metal Ions with Acid Activated Carbons Derived from Oil Palm and Coconut Shells

    Mokhlesur M. Rahman

    2014-05-01

    Full Text Available In this work, batch adsorption experiments were carried out to investigate the suitability of prepared acid activated carbons in removing heavy metal ions such as nickel(II, lead(II and chromium(VI. Acid activated carbons were obtained from oil palm and coconut shells using phosphoric acid under similar activation process while the differences lie either in impregnation condition or in both pretreatment and impregnation conditions. Prepared activated carbons were modified by dispersing hydrated iron oxide. The adsorption equilibrium data for nickel(II and lead(II were obtained from adsorption by the prepared and commercial activated carbons. Langmuir and Freundlich models fit the data well. Prepared activated carbons showed higher adsorption capacity for nickel(II and lead(II. The removal of chromium(VI was studied by the prepared acid activated, modified and commercial activated carbons at different pH. The isotherms studies reveal that the prepared activated carbon performs better in low concentration region while the commercial ones in the high concentration region. Thus, a complete adsorption is expected in low concentration by the prepared activated carbon. The kinetics data for Ni(II, Pb(II and Cr(VI by the best selected activated carbon fitted very well to the pseudo-second-order kinetic model.

  12. Effect of acid activation on structural and bleaching properties of a bentonite

    A natural bentonite obtained from Khorasan, Iran, was submitted to acid activation with sulphuric acid. Sample aliquots (5 gr) were leached with 100 ml H2SO4 solutions of various concentrations (2-7 N) at 80±2 degreeC for 2 hours. X-ray diffraction, chemical analysis, infrared spectroscopy and specific surface area measurements were performed in order to evaluate important structural modifications occurring as a result of acid attack. Octahedral sheet was affected by acid activation resulting into the dissolution of cations (Mg2+, Fe2+, Al3+) and consequent decomposition of montmorillonite structure. Bentonite samples were then tested in order to verify their capacity to bleach colza-soybean oil, and their performances were compared to that of a commercial bleaching clay. The bleaching ability of the natural clay was poor when compared with that of the industrial adsorbent. Acid activation of the bentonite sample with 7N sulphuric acid yielded an adsorbent material which was highly efficient in the bleaching of the oil functioned better than the commercial clay product under the same conditions.

  13. Study on distribution law of modified urea-N in soil-plant system

    Distribution law of reprocessed urea-N and urea-N in soil-plant system was studied by 15N-trace under pot culture condition of tobacco plant. The results showed that reprocessed urea increased the yield of tobacco leaf by 25.16% compared with urea treatment. As to the amounts of total nitrogen in tobacco plant, the reprocessed urea was 145.7% of that with the urea treatment. As to the amounts of nitrogen from the fertilizer, reprocessed urea treatment was 27.9% higher than that of the urea treatment. The nitrogen from soil of the reprocessed urea treatment was 58.3% more than that of urea treatment. The nitrogen utilization ratio of the reprocessed urea treatment was 10.1% higher than that of the urea treatment. These results suggest that the reason of the reprocessed urea can increase the yield of tobacco was due to its high fertilizer utilization ratio and nitrogen releasing ratio of the soil

  14. Synthesis and Performance of Polyurethane Coated Urea as Slow/controlled Release Fertilizer

    LI Qingshan; WU Shu; RU Tiejun; WANG Limin; XING Guangzhong; WANG Jinming

    2012-01-01

    Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules,isocyanate,polyols and paraffin.Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface.Paraffin serves as a lubricant during syntheses of polyurethane skin layers.The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR,SEM and TG.Urea nitrogen slow-release behavior of the polyurethane coated urea was tested.The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 μm were formed on urea surface,the urea nitrogen slow-release time can reach 40-50 days.Paraffin proves to play a key role in inhibiting water to penetrate into urea,but excessive addition would decrease the polyurethane crosslinking density.

  15. Effect of time duration of ruminal urea infusions on ruminal ammonia concentrations and portal-drained visceral extraction of arterial urea-N in lactating Holstein cows

    Røjen, Betina Amdisen; Kristensen, Niels Bastian

    2012-01-01

    The effects of a 6 versus 24h ruminal urea infusion in lactating dairy cows fed a basal diet deficient in N on ruminal ammonia concentration, arterial urea-N concentration, net portal-drained viscera (PDV) urea-N flux, arterial urea-N extraction across the PDV, and renal urea-N kinetics were...... urea/kg of dry matter intake (DMI; 24-h INF), and 6-h infusion of 15g of urea/kg of DMI (6-h INF). The 6-h INF was initiated 0.5h after the afternoon feeding, and ran until 2230h. Eight sample sets of arterial, portal, and hepatic blood, ruminal fluid, and urine were obtained at 0.5h before the morning...... experimental setting plan was met (i.e., to cause changes in the daily pattern of ruminal ammonia and blood urea-N concentrations). The arterial urea-N concentration for 24-h INF and 6-h INF were greater than the arterial urea-N concentration with water INF throughout the sampling window. However, the arterial...

  16. Siloxane modified polyurea and polyurethane urea segmented copolymers

    Kim, Regina H.

    1989-01-01

    High molecular weight polyether urea copolymers were synthesized using perfectly difunctional aromatic amine terminated polypropylene oxide (PPO) (2800 ) prepared via aluminum porphorin initiated coordination polymerization. The resulting segmented copolymer showed much higher tensile strength and better thermal stability than polyureas based on commercial PPO which contains some terminal unsaturation. This was attributed to the achievement of both higher molecular weight and t...

  17. Effect of Urea on Activity and Conformation of a Glycoprotein

    WEI Xiang; WANG Xiaoyun; ZHOU Bo; ZHOU Haimeng

    2006-01-01

    The changes of the activity and conformation of Aspergillus niger phytase in urea were detected by farultraviolet circular dichroism (CD) spectra, fluorescence spectra, and enzyme activity assays. The results show that no enzyme activity can be detected after phytase is incubated for 10 h in 3.0 mol/L urea, even though at this urea concentration, less than 20% of the tertiary and secondary structures in the native enzyme changed. The inactivation reaction kinetics is found to be a monophasic first-order reaction, but the unfolding is a biphasic process consisting of two first-order reactions. The inactivation rates of the free enzyme and the substrate-enzyme complex are much faster than the conformational changes during urea denaturation. All of the results indicate that, as a glycoprotein, phytase's activity is strongly dependent on its conformational integrity. The phytase active sites seem to be located in a limited region in the molecule and display more conformational fragility and flexibility to denaturants than enzyme molecular structure as a whole.

  18. Why Urea Eliminates Ammonia Rather Than Hydrolyzes in Aqueous Solution

    Alexandrova, Anastassia N.; Jorgensen, William L.

    2007-01-01

    A joint QM/MM and ab initio study on the decomposition of urea in the gas phase and in aqueous solution is reported. Numerous possible mechanisms of intramolecular decomposition and hydrolysis have been explored; intramolecular NH3-elimination assisted by a water molecule is found to have the lowest activation energy. The solvent effects were elucidated using the TIP4P explicit w...

  19. Urea: A Clinically Oriented Overview from Bench to Bedside.

    Friedman, Adam J; von Grote, Erika C; Meckfessel, Matthew H

    2016-05-01

    Urea is an important hygroscopic component of the epidermis, where it participates in the maintenance of skin hydration as part of the skin's source of natural moisturizing factor (NMF) in the outer most layers. Xerotic skin, which is frequently characterized as NMF-deficient, is a unifying trait of dermatoses such as atopic dermatitis (AD), psoriasis, and ichthyosis vulgaris. The reduced hygroscopic potential of pathologically dry skin leads to unregulated transepidermal water loss (TEWL), epidermal hyperproliferation, and inhibited desquamation; all which clinically translate to hyperkeratotic and possibly pruritic skin. Common underlying etiologies link these dermatoses to aberrant expression of genes encoding epidermal structural and catalytic proteins. Intervention of dry skin pathologies with topical moisturizer formulations is a foundational management strategy. For over a century urea-containing formulations have been used in a concentration-dependent manner to restore skin hydration, thin hyperkeratosis, debride dystrophic nails, and enhance topical drug penetration. Recently, urea's role in skin hydration and repair has expanded to include regulation of epidermal genes necessary for proper barrier function. Taken together, urea's versatility in topical formulations and broad range of therapeutic mechanism highlights its utility to clinicians and benefit to patients. J Drugs Dermatol. 2016;15(5):633-639. PMID:27168272

  20. Reduction in slow intercompartmental clearance of urea during dialysis

    The kinetics of urea and inulin were analyzed in five anesthetized dogs during sequential 2-hour periods before, during, and after hemodialysis. The distribution of both compounds after simultaneous intravenous injection was characterized by three-compartment models, and the total volumes of urea (0.66 +/- 0.05 L/kg) and inulin (0.19 +/- 0.01 L/kg) distribution were similar to expected values for total body water and extravascular space, respectively. Intercompartmental clearances calculated before dialysis were used to estimate blood flows to the fast and slow equilibrating compartments. In agreement with previous results, the sum of these flows was similar to cardiac output, averaging 101% of cardiac output measured before dialysis (range 72% to 135%). Dialysis was accompanied by reductions in the slow intercompartmental clearances of urea (81%) and inulin (47%), which reflected a 90% attenuation in blood flow supplying the slow equilibrating compartments. This was estimated to result in a 10% average reduction in the efficiency with which urea was removed by dialysis (range 2.0% to 16.4%). Mean arterial pressure fell by less than 5% during dialysis, but total peripheral resistance increased by 47% and cardiac output fell by 35%. In the postdialysis period, total peripheral resistance and cardiac output returned toward predialysis values, but blood flow to the slow equilibrating peripheral compartment was still reduced by 80%. These changes parallel activation of the renin-angiotensin system, but further studies are required to establish causality

  1. Tailoring of analytical performances of urea biosensors using nanomaterials

    This paper is a contribution to the study of enzymatic sensors based on nanoparticles of iron oxide (FeNPs). Urease enzyme was immobilized on FeNPs using layer-by-layer (LbL) deposition method. FeNPs were first coated with polyelectrolytes (PE): Poly (allylamine hydrochloride), PAH and Poly (sodium 4-styrenesulfonate), PSS for enzyme immobilization and then with enzyme. It has been confirmed through zeta potential measurements of FeNPs that the enzyme is immobilized on the surface. We evaluated the sensitivity of biosensors for urea by potentiometric and capacitive measurements on silicon / silica / FeNP-LBL-urease structures. The recorded capacity-potential curves (C-V) show a significant shift of flat band potential towards negative potentials in the presence of urea, the observed values of sensitivity vary between 30 and 40 mV/p[urea]. It has been shown that the proposed method for the immobilization of urease can increase the dynamic range of urea detection (10−4M to 10−1M) compared to the immobilization of urease without FeNP (10−3.5 M to 10−2.5 M). When the number of PAH-PSS layers was increased the sensitivity of detection was modified. This effect is due to partial inhibition of the enzyme in presence of FeNPs, which was shown by measurements in homogeneous phase.

  2. IRIS Toxicological Review of Urea (Interagency Science Consultation Draft)

    On September 28, 2010, the Toxicological Review of Urea and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Of...

  3. Emissions of gun propellant compositions with added urea

    Driel, C.A. van; Hulst, M. van; Meuken, D.

    2011-01-01

    Addition of certain components to gun propellants may lead to a reduction of the NOx content in combustion gases. This is escribed in the literature based on small scale laboratory research. One of these components is urea. In the investigation described here, propellants have been studied which con

  4. Influence of urea and pituitrin on radiocerebral effects in rats

    The administration of urea and pituitrin produced a directed and rapid change in a hydration profile of brain tissue which permitted to modify the severity of radiocerebral affection in rats, that is, to increase it with hypohydration and to decrease with hyperhydration of the brain

  5. Peptidyl-urea based inhibitors of soluble epoxide hydrolases

    We prepared a series of amino acid derived cyclohexyl and adamantyl ureas and tested them as inhibitors of the human soluble epoxide hydrolase, and obtained very potent compounds (K(I)=15nM) that are >10-fold more soluble than previously described sEH inhibitors. While our lead compound 2 showed low...

  6. 75 FR 74746 - Solid Urea From Russia and Ukraine

    2010-12-01

    ... from Russia and Ukraine (64 FR 62653). Following second five-year reviews by Commerce and the... imports of solid urea from Russia and Ukraine (71 FR 581). The Commission is now conducting third reviews... part 207), as most recently amended at 74 FR 2847 (January 16, 2009). \\1\\ No response to this...

  7. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    Siafu Ibahati Sempeho

    2015-01-01

    Full Text Available Urea controlled release fertilizer (CRF was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU. Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600°C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

  8. Urea in sugarcane-based diets for dairy cows

    Alberto Magno Ferreira Santiago

    2013-06-01

    Full Text Available We evaluated the effect of adding four levels (0, 4, 8 and 12 g/kg, as fed of a mixture (9:1 of urea and ammonium sulfate (UAs to sugarcane on feed intake and digestibility, productive performance and metabolism of nitrogen compounds of dairy cows. Twelve multiparous Holstein cows (12.6±0.5 kg/d of milk, 225±90 days in milk were distributed in three 4 × 4 Latin squares, receiving diets with the same amount of nitrogen (125 g crude protein/kg of dry matter. Concentrate feed was supplied at a ratio of 1 kg for each 3 kg of milk produced. The sugarcane presented 21.9 ºBrix. The level of UAs did not affect intake, total digestibility of diet components, milk production or milk components. Increasing UAs level linearly increased concentration of plasma urea nitrogen (PUN, urinary excretion of nitrogen and contribution of non-urea nitrogen in the urinary excretion and linearly reduced milk production/urinary excretion of nitrogen ratio. In spite of the linear increase of PUN with increased urea, the maximum value observed (14.31 mg/dL was below the threshold value of 20 mg/dL, above which reproductive function may be compromised. In diets with sugarcane for dairy cows with production below 15 kg/day, the UAs level may be raised from 0 to 12 g/kg natural matter without impairing performance.

  9. Effects of slow-release urea on ruminal digesta characteristics and growth performance in beef steers

    Taylor-Edwards, C C; Hibbard, G; Kitts, S E;

    2009-01-01

    Two experiments were conducted to evaluate the effects of slow urea (SRU) versus feed-grade urea on ruminal metabolite characteristics in steers and DMI, gain, and G:F in growing beef steers.......Two experiments were conducted to evaluate the effects of slow urea (SRU) versus feed-grade urea on ruminal metabolite characteristics in steers and DMI, gain, and G:F in growing beef steers....

  10. Performance of cellulose acetate butyrate membranes in hyperfiltration of sodium chloride and urea feed solution

    Wydeven, T.; Leban, M.

    1973-01-01

    Cellulose acetate butyrate (CAB) membranes are shown to give high salt and urea rejection with water flux of about 3 gallons/sq ft per day at 600 psig. Membranes prepared from a formulation containing glyoxal show a significant increase in flux and decrease in salt and urea rejection with drying time. Zero drying time gives maximum urea and salt rejection and is therefore most suitable for hyperfiltration of sodium chloride and urea feed solution.

  11. Comparison of amino acid oxidation and urea metabolism in haemodialysis patients during fasting and meal intake

    Veeneman, JM; Kingma, HA; Stellaard, F; de Jong, PE; Reijngoud, DJ; Huisman, RM

    2004-01-01

    Background. The PNA (protein equivalent of nitrogen appearance) is used to calculate protein intake from urea kinetics. One of the essential assumptions in the calculation of PNA is that urea accumulation in haemodialysis (HD) patients is equivalent to amino acid oxidation. However, urea is hydrolys

  12. 75 FR 78243 - Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review...

    2010-12-15

    ... AGENCY Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review... pesticides propionic acid and salts, case no. 4078, urea sulfate, case no. 7213, methidathion, case no. 0034... pesticides in the table below--propionic acid and salts, case 4078, urea sulfate, case no. 7213,...

  13. 75 FR 51055 - Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of...

    2010-08-18

    ... AGENCY Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of... urea sulfate and opens a public comment period on the proposed decisions. Registration review is EPA's.... Urea sulfate is used as a desiccant on ] cotton. No food crop uses remain and all tolerances for...

  14. 40 CFR 721.9920 - Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-.

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Urea, (hexahydro-6-methyl-2... Specific Chemical Substances § 721.9920 Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance urea,...

  15. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the urea...) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory § 418.30 Applicability; description of the urea subcategory. The provisions of this subpart are applicable to...

  16. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177...-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact surface... conditions: (a) For the purpose of this section, urea-formaldehyde resins are those produced when 1 mole...

  17. Urea derivatives on the basis of 6-amino benzo-1.4-dioxan

    Present work is devoted to urea derivatives on the basis of 6-amino benzo-1.4-dioxan. The results of studies of condensation of 6-amino benzo-1.4-dioxan with urea and its derivatives are given. The new urea derivatives synthesized by fragment of 1.4-dioxan. (author)

  18. Hydroxymethyl urea and 1,3-bis(hydroxymethyl) urea as corrosion inhibitors for steel in HCl solution

    Highlights: •HMU and BHMU are new good inhibitors for steel in HCl solution. •Inhibition efficiency follows the order: BHMU > HMU. •The adsorption of urea inhibitor obeys Langmuir adsorption isotherm. •There is a correlation of quantum chemical parameters with the inhibition action. •HMU and BHMU molecules adsorb on Fe (0 0 1) surface in the nearly flat manner. -- Abstract: The inhibition effect of two urea derivatives of hydroxymethyl urea (HMU) and 1,3-bis(hydroxymethyl) urea (BHMU) on the corrosion of cold rolled steel (CRS) in 1.0 M HCl solution was studied by weight loss, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS), quantum chemical calculation and molecular dynamics (MD) simulation methods. Inhibition efficiency values of 20.0 mM HMU and BHMU are higher than 80% and 85% at 20–50 °C, respectively. The adsorption of each inhibitor on steel surface obeys Langmuir adsorption isotherm, and is mainly the chemical adsorption. Inhibition efficiency follows the order: BHMU > HMU

  19. DETERMINATION OF ACID–BASE PROPERTIES OF HCL ACID ACTIVATED PALYGORSKITE BY POTENTIOMETRIE TITRATION

    N. FriniSrasra; Srasra, E.

    2008-01-01

    The surface acidity of raw and acid activated palygorskite clay were studied by acid-base potentiometric titration. The Gran plot method was applied for the hydroxide titration and the total surface site (Hs) and the average number of protons reacted per surface site (Z) of palygorskite samples at a given ionic strength were calculated. Acid treatment increases the clay acidity and modifies its surface charge. The point of zero charge value, determined by the common crossing point of Z vs pH ...

  20. Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis.

    Emilie Glavind

    Full Text Available Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC, as well as to clinical disease severity.We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC, i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD score.The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01, and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05. The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05.Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up-regulation observed in other stressful

  1. Efficacy of Dietary Urea-Impregnated Zeolite in Improving Rumen Fermentation Characteristics of Local Lamb

    D. Kardaya; D. Sudrajat; E. Dihansih

    2012-01-01

    A research on dietary inclusion of urea-impregnated zeolite as slow-release urea (SRU) agent had been conducted to reveal its effect on ruminal fermentation characteristics in local lambs. The research used 24 heads of 7-8 mo old of local male lambs with (20.12±2.1 kg BW) designed upon a randomized block design. Treatments consisted of diets contained no urea, urea, zeolite, and urea-impregnated zeolite. The collected data was analyzed with UNIANOVA and Duncan’s multiple-range test. Results i...

  2. Adsorption of Bezanyl Red and Nylomine Green from aqueous solutions by natural and acid-activated bentonite

    BENGUELLA, B.; YACOUTA-NOUR, A.

    2009-01-01

    The adsorption of two acid dyes, namely, Red Bezanyl and Green Nylomine, onto natural bentonite and acid activated bentonite from aqueous solutions were studied in a batch system. The kinetic data show that at the equilibrium, the acid-activated bentonite fixes more Bezanyl Red and Nylomine Green than the natural bentonite. Adsorption equilibrium was reached within 2 h. The results also showed that the kinetics of adsorption is best descibed by a pseudo second-order expression than a first or...

  3. The effect of urea pretreatment on the formaldehyde emission and properties of straw particleboard

    Hojat Hematabadi; Rabi Behrooz

    2012-01-01

    For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments,we investigated the influence of urea treatment on the formaldehyde emission,physical and mechanical properties of the manufactured particleboard.Wheat straws were treated at three levels of urea concentration (5%,10%,15%) and 95℃ as holding temperature.Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive (UF-45,UF-91).Then the formaldehyde emission values,physical properties and mechanical properties were considered.The results show that the formaldehyde emission value was decreased by increasing urea concentration.Furthermore,the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens.Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.

  4. Synthesis and characterization of alternating poly(amide urea)s and poly(amide urethane urethane)s from ε-caprolactam, diamines, and diphenyl carbonate or ethylene carbonate

    Ubaghs, Luc; Sharma, Bhaskar; Keul, Helmut; Höcker, Hartwig; Loontjens, Ton; Benthem, Rolf van

    2003-01-01

    Alternating poly(amide urea)s from ε-caprolactam, diamines H2N-(CH2)x-NH2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The mo

  5. Patient risk of 14C-urea breath test

    Helicobacter Pylori bacteria infection is determined by activity measurement of the exhaled 14C-carbon dioxide formed from 14C-urea in stomach. About 37 kBq of capsulated 14C -urea is administered to the patient. Because 14C is a weak beta emitter, patients receive certain radiation dose. This could be the only drawback of this method. Because of that in this paper the effective dose has been determined. On that basis the patient risk has been estimated. The results show that the patient effective dose is at the level of the daily background radiation. So, from the radiation protection point of view this method is very safe. Including other excellent performances of the method like sensitivity, selectivity, noninvasivity, fastness and low costs, it could be recommended in diagnosis and eradication of Helicobacter Pylori infections. (author)

  6. Multiresidue HPLC methods for phenyl urea herbicides in water.

    Ruberu, S R; Draper, W M; Perera, S K

    2000-09-01

    High-performance liquid chromatography (HPLC) methods for the determination of phenyl urea herbicides in water are described. The target compounds include chlortoluron, diuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monuron, neburon, and siduron. Water was subjected to solid phase extraction (SPE) using either automated SPE with 47 mm C(18) Empore disks or on-line precolumn concentration. Herbicides were separated on a C(18) reversed phase column with an acetonitile-water gradient and were detected with either a diode array detector (DAD) or a postcolumn photolysis and derivatization (PPD) detector system. Photolysis converted the phenyl ureas to monoalkylamines that were derivatized to fluorescent isoindoles by reaction with o-phthalaldehyde and 2-mercaptoethanol. The DAD monitoring at 245 nm was linear over three decades with instrument detection limits of approximately 0.01 mg/L. SPE efficiency was between 48 and 70% in laboratory reagent water, but use of the internal standard quantitation method improved accuracy. High total dissolved solids and total organic carbon values in surface water improved recoveries relative to laboratory reagent water for all of the phenyl ureas. In Colorado River water spiked at 1 or 50 microg/L, mean recoveries ranged from 74 to 104%. Method detection limits (MDLs) ranged from 4 to 40 ng/L (parts per trillion) with the DAD instrument. PPD detection was highly specific but resulted in a slight loss in chromatographic efficiency and average MDLs approximately 5 times higher using a single set of detection conditions. The study indicates that methods based on SPE followed by HPLC with diode array or PPD detection have practical utility for trace analysis of phenyl ureas in drinking water or surface waters. PMID:10995323

  7. Voltamperometric Discrimination of Urea and Melamine Adulterated Skimmed Milk Powder

    Eduardo Cortón; M. Celina Bonetto; Sacco, Natalia J.; Fauerbach, Jonathan A.; Astrid Hilding-Ohlsson

    2012-01-01

    Nitrogen compounds like urea and melamine are known to be commonly used for milk adulteration resulting in undesired intoxication; a well-known example is the Chinese episode occurred in 2008. The development of a rapid, reliable and economic test is of relevance in order to improve adulterated milk identification. Cyclic voltammetry studies using an Au working electrode were performed on adulterated and non-adulterated milk samples from different independent manufacturers. Voltammetric data ...

  8. EXCRECION FRACCIONAL DE UREA BAJA EN HIPONATREMIA INDUCIDA POR HIPOTIROIDISMO

    Musso CG; Macías Núñez JF; Imperiali N; Algranati L

    2005-01-01

    ABSTRACTHypothyroidism can cause disturbance of renal hemodinamics, kidney histology, water and electrolyte metabolism, being hyponatremia and glomerular filtration reduction their low prevalent but most significant consequences. All these changes are largely corrected by substitution of exogenous thyroid hormone.Fractional excretion of urea (FEU) is a useful index in the evaluation of hyponatremia. However, it was not still reported in the literature the FEU value in hyponatremia induced by ...

  9. A stochastic model for an urea decomposition system

    VSS Yadavalli

    2005-12-01

    Full Text Available Availability is an important measure in describing the performance of a system. The availability of a decomposition process in an urea production system in the fertilizer industry is considered in this paper. The system contains four subsystems and is supported by a standby unit. An estimation study of the steady state availability of the system is performed and illustrated by means of a numerical example.

  10. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  11. Reverse osmosis membrane of high urea rejection properties. [water purification

    Johnson, C. C.; Wydeven, T. J. (Inventor)

    1980-01-01

    Polymeric membranes suitable for use in reverse osmosis water purification because of their high urea and salt rejection properties are prepared by generating a plasma of an unsaturated hydrocarbon monomer and nitrogen gas from an electrical source. A polymeric membrane is formed by depositing a polymer of the unsaturated monomer from the plasma onto a substrate, so that nitrogen from the nitrogen gas is incorporated within the polymer in a chemically combined form.

  12. Fundamental and Applied Aspects of Urea and Thiourea Inclusion Compounds

    Harris, Kenneth David Maclean

    2007-01-01

    Abstract Urea and thiourea inclusion compounds are well known to exhibit a wide range of fundamentally important physico-chemical properties, and through the work of many research groups, these materials have served as model systems for exploring a range of issues of wider relevance to other classes of organic solids. While continuing to investigate these issues, our research in recent years has also focused on issues of a more applied nature, including crystal growth processes, gu...

  13. Banding urea and lignosulfonate in corn (Zea mays L.) production and 15N recovery

    The use of urea in corn (Zea mays L.) production is common. Under current N fertilizer recommendations for corn, urea may have adverse effects on corn growth when applied in a band. The effects of ammonium lignosulfonate (LS) on corn growth and on N uptake from the banded application of urea and diammonium phosphate (DAP) mixtures were investigated on two soils from eastern Quebec. Field experiments were initiated in the first week of May 1991 on an Ormstown silty clay and a Ste. Rosalie clay soils (fine, mixed, nonacid, mesic Typic Humaquepts). Treatments were two rates of urea (30 and 90 kg urea-N ha-1) in a combination with DAP (14kg N ha 1), with or without banded fertilizer solutions of LS (8 kg N ha-1) applied at planting 5 cm to the side and 3 cm below the seed. A no treatment control was included. The low rate of urea compared with the unfertilized plots. When compared with the unfertilized treatment, the high rate of urea and DAP (no LS added) caused 10% increase in grain yield. However, addition of LS to the high rate of urea and DAP increase grain yield by band 20%. In general, LS significantly increased corn N uptake from urea on both soils. Separate 15N field experiments were initiated in June 1991. Mean recovery of 15N ranged from 17.8% to 30.9% of the applied labelled urea. The rate of urea-N banded had no significant effect on immobilization, but LS resulted in significantly less 15N immobilized. These observations suggest that LS can reduce the biological immobilization of urea-N and increase the efficiency of urea fertilizer by reducing the negative effects of banding high levels of urea, while attaining benefits of band placement. (author). 29 refs., 6 tabs

  14. Antibacterial kaolinite/urea/chlorhexidine nanocomposites: Experiment and molecular modelling

    Clay minerals are commonly used materials in pharmaceutical production both as inorganic carriers or active agents. The purpose of this study is the preparation and characterization of clay/antibacterial drug hybrids which can be further included in drug delivery systems for treatment oral infections. Novel nanocomposites with antibacterial properties were successfully prepared by ion exchange reaction from two types of kaolinite/urea intercalates and chlorhexidine diacetate. Intercalation compounds of kaolinite were prepared by reaction with solid urea in the absence of solvents (dry method) as well as with urea aqueous solution (wet method). The antibacterial activity of two prepared samples against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding the minimum inhibitory concentration (MIC). Antibacterial studies of both samples showed the lowest MIC values (0.01%, w/v) after 1 day against E. faecalis, E. coli and S. aureus. A slightly worse antibacterial activity was observed against P. aeruginosa (MIC 0.12%, w/v) after 1 day. Since samples showed very good antibacterial activity, especially after 1 day of action, this means that these samples can be used as long-acting antibacterial materials. Prepared samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental data are supported by results of molecular modelling.

  15. Antibacterial kaolinite/urea/chlorhexidine nanocomposites: Experiment and molecular modelling

    Holešová, Sylva, E-mail: sylva.holesova@vsb.cz [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Valášková, Marta; Hlaváč, Dominik [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Madejová, Jana [Institute of Inorganic Chemistry, SAS, Dúbravská cesta 9, SK-845 36 Bratislava (Slovakia); Samlíková, Magda; Tokarský, Jonáš [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Pazdziora, Erich [Institute of Public Health Ostrava, Centre of Clinical Laboratories, Partyzánské náměstí 7, CZ-702 00 Ostrava (Czech Republic)

    2014-06-01

    Clay minerals are commonly used materials in pharmaceutical production both as inorganic carriers or active agents. The purpose of this study is the preparation and characterization of clay/antibacterial drug hybrids which can be further included in drug delivery systems for treatment oral infections. Novel nanocomposites with antibacterial properties were successfully prepared by ion exchange reaction from two types of kaolinite/urea intercalates and chlorhexidine diacetate. Intercalation compounds of kaolinite were prepared by reaction with solid urea in the absence of solvents (dry method) as well as with urea aqueous solution (wet method). The antibacterial activity of two prepared samples against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding the minimum inhibitory concentration (MIC). Antibacterial studies of both samples showed the lowest MIC values (0.01%, w/v) after 1 day against E. faecalis, E. coli and S. aureus. A slightly worse antibacterial activity was observed against P. aeruginosa (MIC 0.12%, w/v) after 1 day. Since samples showed very good antibacterial activity, especially after 1 day of action, this means that these samples can be used as long-acting antibacterial materials. Prepared samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental data are supported by results of molecular modelling.

  16. Synthesis of dimethyl carbonate from urea and methanol

    Polyakov, M.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz Institute for Catalysis; Mueller, K.; Arlt, W. [Erlangen-Nuernberg Univ. (Germany); Strautmann, J.; Kruse, D. [Evonik Industries AG, Marl (Germany). Creavis Technologies and Innovation

    2012-07-01

    Alcoholation of urea with methanol to produce dimethyl carbonate (DMC) is an interesting approach from both the ecological and economical points of view because the urea synthesis usually occurs by the direct use of carbon dioxide. Literature survey reveals that metal oxide catalysts for instance MgO, ZnO, etc. or polyphosphoric acids are mostly used as catalysts for this reaction. In this contribution, we describe the application of ZnO, MgO, CaO, TiO{sub 2}, ZrO{sub 2} or Al{sub 2}O{sub 3} catalysts for the above mentioned reaction. The catalytic activity of different metal oxides towards DMC synthesis was checked and additionally a comparison of achieved conversions with that of predictions made by thermodynamic calculations was also carried out. The achieved conversions are in good agreement with those of calculated ones. The test results reveal that the reaction pressure and temperature have a strong influence on the formation of DMC. Higher reaction pressure improved the yield of DMC. Among different catalysts investigated, ZnO displayed the best performance. The conversion of urea in most cases is close to 100 % and methyl carbamate MC is the major product of the reaction. A part of MC is subsequently converted to DMC, which however depends upon the reaction conditions applied and nature of catalyst used. From the best case, a DMC yield of ca. 8 % could be successfully achieved over ZnO catalyst. (orig.)

  17. Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

    Das G

    2015-08-01

    Full Text Available Gautam Das, Hyon Hee Yoon Department of Chemical and Biological Engineering, Gachon University, Seongnam, Gyeonggi-do, South Korea Abstract: An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 µA·cm-2·mM-1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. Keywords: electrochemical deposition, sulfonated graphene oxide, urease

  18. Urochloa ruziziensis responses to sources and doses of urea

    João E. S. Lima

    2016-05-01

    Full Text Available ABSTRACT The use of products that promote reduction of nitrogen (N losses from the urea fertilizer can contribute to increasing its use efficiency in forage grasses. This study aimed to evaluate the effects of N sources and doses on the growth of Urochloa ruziziensis. The experiment was carried out in the growing season of 2007/2008 in Santo Antônio de Goiás-GO, in a Brazilian Oxisol. A completely randomized block was used, with four replicates in a factorial scheme, corresponding to two N sources (conventional urea and urea with urease inhibitor and five N doses (0, 50, 100, 200 and 300 kg ha-1, divided into equal applications in five periods (Nov 14 to Dec 13, Dec 14 to Jan 12, Jan 13 to Feb 11 - rainy season, Mar 24 to Apr 22 and Jul 10 to Aug 08 - dry season. The effects of the treatments were evaluated for: shoot dry matter, tiller density, total N content in the leaves and relative chlorophyll content. N fertilizer sources did not affect the evaluated variables; however, N fertilization allowed linear increases in all variables with higher values during the rainy period. The relative chlorophyll content in U. ruziziensis had positive correlation with its dry matter productivity.

  19. Utilization of 15N-urea in laying hens. 3

    In 3 colostomized laying hens the incorporation of heavy nitrogen from urea into the amino acids of the 21 eggs laid during the 8-day experiment was determined. In these eggs the content of 15 amino acids was ascertained separately in white and yolk of the eggs and their atom-% 15N excess (15N') was determined. The heavy nitrogen could be detected in all amino acids investigated. The incorporation of 15N' into the essential amino acids of the white and yolk of eggs is very low. Of the 15N' amount of the urea applied 0.18% could be detected in the 9 essential amino acids of the white of egg and 0.12% in those of the yolk. For the 6 analyzed nonessential amino acids the rediscovery quota of 15N' in the white of egg was 0.50% and in the yolk 0.81% is that the NPN-source urea is insignificant for egg protein synthesis. (author)

  20. Urea coated with oxidized charcoal reduces ammonia volatilization

    Diogo Mendes de Paiva

    2012-08-01

    Full Text Available Urea is the most consumed nitrogen fertilizer in the world. However, its agronomic and economic efficiency is reduced by the volatilization of NH3, which can reach 78 % of the applied nitrogen. The coating of urea granules with acidic compounds obtained by charcoal oxidation has the potential to reduce the volatilization, due to the acidic character, the high buffering capacity and CEC. This work aimed to evaluate the effect of HNO3-oxidized carbon on the control of NH3 volatilization. These compounds were obtained by oxidation of Eucalyptus grandis charcoal, produced at charring temperatures of 350 and 450 ºC, with 4.5 mol L-1 HNO3. The charcoal was oxidized by solubilization in acidic or alkaline medium, similar to the procedure of soil organic matter fractionation (CHox350 and CHox450. CHox was characterized by C, H, O, N contents and their respective atomic relations, by the ratio E4 (absorbance 465 nm by E6 (absorbance 665 nm, and by active acidity and total acidity (CEC. The inhibitory effect of CHox on the urease activity of Canavalia ensiformis was assessed in vitro. The NH3 volatilization from urea was evaluated with and without coating of oxidized charcoal (U-CHox350 or U-CHox450 in a closed system with continuous air flow. The pH of both CHox was near 2.0, but the total acidity of CHox350 was higher, 72 % of which was attributed to carboxylic groups. The variation in the ionization constants of CHox350 was also greater. The low E4/E6 ratios characterize the high stability of the compounds in CHox. CHox did not inhibit the urease activity in vitro, although the maximum volatilization peak from U-CHox450 and U-CHox350 occurred 24 h after that observed for uncoated urea. The lowest volatilization rate was observed for U-CHox350 as well as a 43 % lower total amount of NH3 volatilized than from uncoated urea.

  1. Equilibrium studies on hydrolysis of urea in a semi-batch reactor for production of ammonia to reduce hazardous pollutants from flue gases

    The increasing environmental awareness and the mandate of the pollution control agencies in various part of country for lowering emission of air pollutants such as CO2, NOx, SO2 and fly ash emissions, has increased the urgency for reviewing options and alternatives to accomplish the above objective. The addition of ammonia into the flue gas stream as a conditioning agent is found to be used in recent years for the reduction of air pollutants. Flue gas conditioning requires in situ generation of ammonia as the transportation and storage of anhydrous ammonia is hazardous in nature. The equilibrium study on hydrolysis of urea was done in a semi-batch glass reactor to investigate the effect of reaction temperature, initial feed concentration and stirring speed on ammonia production. Few experiments were carried out in a semi-batch reactor at atmospheric pressure by using different concentration of urea solution from 10 to 40 wt% of urea to water and equilibrium study has been done. The study reveals that conversion increases exponentially with an increase in temperature but the conversion decreases with increase in the inlet feed concentration of urea solution. Furthermore, the effect of stirring speed on conversion has also been studied and it found that conversion increases with increase in stirring speed.

  2. Enhancing the Urea-N Use Efficiency in Maize (Zea mays Cultivation on Acid Soils using Urea Amended with Zeolite and TSP

    Osumanu H. Ahmed

    2009-01-01

    Full Text Available Problem Statement: Ammonia loss significantly reduces urea-N use efficiency in crop production. Efforts to reduce ammonia loss are laboratory oriented, as such limited in reflecting actual field conditions. This paper reports the effects of urea amended with triple superphosphate (TSP and zeolite (Clinoptilolite on soil pH, soil nitrate, soil exchangeable ammonium, dry matter production, N uptake, fresh cob production and urea-N uptake efficiency in maize (Zea mays cultivation on an acid soil in actual field conditions. Approach: The treatments evaluated were: (i Normal N, P, K application (74.34 g urea, 27.36 g TSP, 24.12 g KCl (T1, (ii Urea-TSP mixture (74.34 g urea+27.36 g TSP+24.12 g KCl (T2, (iii 74.34 g urea+27.36 g TSP+9.0 g zeolite (T3, (iv 74.34 g urea+27.36 g TSP+13.5 g zeolite (T4 and (v No fertilization (T5. Note, the same amount of 24.12 g KCl was used in T3 and T4 plots. Standard procedures were used to determine the selected chemical properties of zeolite, soil, TSP and urea. The pH of the urea, zeolite, soil and TSP were determined in a 1:2.5 soil: distilled water suspension and/or 0.01 N CaCl2 using a glass electrode. The CEC of the zeolite was determined by the CsCl method. Soil CEC was determined by leaching with 1 N ammonium acetate buffer adjusted to pH 7.0 followed by steam distillation. Soil samples at harvest were analyzed for pH using the method previously outlined. Exchangeable ammonium and nitrate at harvest were extracted from the soil samples by the method of Keeney and Nelson and the amount determined using a LACHAT Autoanalyzer. Total N of the plant tissues (stem and leaf was determined by the Micro-Kjeldhal method. Results: Urea amended with TSP and zeolite treatments and Urea only (urea without additives did not have long term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf

  3. Effect of nickel nutrition on yield, urea accumulation and urease enzyme activity of lettuce

    M. Afyuni

    2011-04-01

    Full Text Available Although nickel (Ni is known as an essential element for higher plants, the biological effects of this nutrient on growth, yield, and N metabolism of some plants, particularly leafy vegetables, is still unknown. Therefore, this study was carried out to investigate the effects of Ni and urea nutrition on the growth and yield of lettuce (Lactuca sativa L. cv. Baker and urea accumulation in plant tissues. In this study, nitrogen was supplied from the source of urea or ammonium nitrate at three levels (5, 10 and 20 mM and Ni was supplied in the form of NiCl2 at two levels (0 and 0.04 µM. The plants were harvested 6 weeks after transplanting and the fresh weight of shoots and roots were determined. The shoots urea concentration and activity of urease enzyme in the leaves were also measured. The results indicated that shoots fresh weight of the urea-fed plants increased with increasing urea concentration in the nutrient solution. Addition of Ni to the nutrient solution significantly promoted the root and shoots fresh weight of urea-fed plants, regardless of N level. Ni nutrition significantly increased the urease activity in the lettuce leaves and as a result, reduced urea accumulation in the shoots and toxicity effects of urea. Therefore, it seems that urea in combination with Ni can successfully be used in production of lettuce in soilless culture systems.

  4. Non-enzymatic detection of urea using unmodified gold nanoparticles based aptasensor.

    Kumar, Piyush; Lambadi, Paramesh Ramulu; Navani, Naveen Kumar

    2015-10-15

    Biosensing nitrogenous compounds like urea is required to control the incidents of Economically Motivated Adulteration (EMA). In this study, we report the FluMag Systematic Evolution of Ligands by Exponential Enrichment (FluMag-SELEX) method to isolate a urea specific DNA aptamer with a dissociation constant (Kd) of 232 nM. The interaction of DNA aptamer with urea has been confirmed by affinity assay, CD analysis, melting curve analysis and truncation studies. Unlike other urea sensing methods reported so far, using this urea aptamer, we demonstrate a simple, 'non-enzymatic' easy-to-use, dual readout aptasensor that exploits unmodified gold nanoparticles (AuNPs) to transduce the signals of aptamer binding to urea in terms of intrinsic fluorescence differences and color changes simultaneously. This method is free from complicated sample processing and labeling steps. The urea aptasensor displays high selectivity for urea and is free from interference from common milk adulterants. The developed aptasensor reliably detects urea adulteration in milk. The response signals linearly correlate with the increasing concentrations of urea in milk ranging from 20mM to 150 mM with detection limit of 20mM. We also show that this aptasensor can also be used as a simple fluorescence based "turn-on" sensor. The results obtained in this study are comparable to the commercial urease based detection methods. PMID:26002019

  5. Reducing Ammonia Loss from Urea by Mixing with Humic and Fulvic Acids Isolated from Coal

    Ameera A. Reeza

    2009-01-01

    Full Text Available Problem statement: Ammonia volatilization is a major pathway for nitrogen loss from surface applied urea. While all top-dressed ammonia and ammonium based N fertilizers can volatilize, the potential loss is greatest with urea and fluids containing urea. As much as 20-50% of N applied to soils is lost through volatilization alone. Thus, the objective of this laboratory study was to reduce ammonia loss from urea via mixing with humic and fulvic acids isolated from coal. Approach: This study compared four different types of treatments which were urea without additives (T1, urea with humic acid-powdered form (T2, urea with fulvic acid-liquid form (T3 and urea with humic and fulvic acids-liquid form (T4. Comparisons were made based on ammonia loss, soil NH4 and NO3- contents as well as exchangeable cations in the treated soils. Soil samples from typic paleudults (Bekenu series were used. Humic substances were isolated using standard procedures. Daily ammonia loss from soil was measured using a modified closed-dynamic air flow system method. Results: All of the treatments with humic substances significantly reduced ammonia loss ranging between 13 and 25% compared to urea alone. The treatment with both humic and fulvic acids (T4 showed pronounced ammonia loss reduction. All treatments with humic substances significantly increased NH4+ and NO3- content in soil samples compared to urea alone except for treatment having humic acid alone (T2. Treatments with fulvic acid (T3 and T4 also showed significant increase in exchangeable K+ and Na+ compared to urea alone. The increase in the formation of NH4+ over NH3, soil exchangeable cations and temporary reduction of soil pH may had retarded urea hydrolysis in the immediate vicinity of the fertilizer. Conclusion: Surface applied urea fertilizer efficiency could be increased if applied together with humic and fulvic acids.

  6. An in vitro study of urea, water, ion and CO2/HCO3- transport in the gastrointestinal tract of the dogfish shark (Squalus acanthias): the influence of feeding

    Liew, H.J.; De Boeck, G.; Wood, C. M.

    2013-01-01

    In vitro gut sac preparations made from the cardiac stomach (stomach 1), pyloric stomach (stomach 2), intestine (spiral valve) and colon were used to examine the impact of feeding on transport processes in the gastrointestinal tract of the dogfish shark. Preparations were made from animals that were euthanized after 1–2 weeks of fasting, or at 24–48 h after voluntary feeding on a 3% ration of teleost fish (hake). Sacs were incubated under initially symmetrical conditions with dogfish saline o...

  7. Evaluation of Fermentation Dynamics and Structural Carbohydrate Degradation of Napiergrass Ensiled with Additives of Urea and Molasses

    Hui Rong, Cheng-qun Yu 1, Zhi-hua Li, Masataka Shimojo2 and Tao Shao*

    2013-01-01

    This study examined the effects of urea and molasses on fermentation dynamics and structural carbohydrate degradation of Napiergrass (Pennisetum purpureum Schumach), which was ensiled in laboratory silos for 3, 7, 14, and 30 days at the ambient temperature. The treatments were additions (fresh weight basis) of: no molasses or urea (control), no molasses and 0.4% urea (U), 4% molasses and 0% urea (M), 4% molasses and 0.4% urea (MU). The results showed that the control group produced an unstabl...

  8. Bile Acid-Activated Receptors, Intestinal Microbiota, and the Treatment of Metabolic Disorders.

    Fiorucci, Stefano; Distrutti, Eleonora

    2015-11-01

    The composition of the bile acid pool is a function of the microbial metabolism of bile acids in the intestine. Perturbations of the microbiota shape the bile acid pool and modulate the activity of bile acid-activated receptors (BARs) even beyond the gastrointestinal tract, triggering various metabolic axes and altering host metabolism. Bile acids, in turn, can also regulate the composition of the gut microbiome at the highest taxonomic levels. Primary bile acids from the host are preferential ligands for the farnesoid X receptor (FXR), while secondary bile acids from the microbiota are ligands for G-protein-coupled bile acid receptor 1 (GPBAR1). In this review, we examine the role of bile acid signaling in the regulation of intestinal microbiota and how changes in bile acid composition affect human metabolism. Bile acids may offer novel therapeutic modalities in inflammation, obesity, and diabetes. PMID:26481828

  9. Removal of Basic Violet 14 from aqueous solution using sulphuric acid activated materials.

    Suresh, S

    2016-01-01

    In this study the adsorption of Basic Violet, 14 from aqueous solution onto sulphuric acid activated materials prepared from Calophyllum inophyllum (CS) and Theobroma cacao (TS) shells were investigated. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models. The results showed that CS has a superior adsorption capacity compared to the TS. The adsorption capacity was found to be 1416.43 mg/g for CS and 980.39 mg/g for TS. The kinetic data results at different concentrations were analysed using pseudo first-order and pseudo-second order model. Boyd plot indicates that the dye adsorption onto CS and TS is controlled by film diffusion. The adsorbents were characterised by scanning electron microscopy. The materials used in this study were economical waste products and hence can be an attractive alternative to costlier adsorbents for dye removal in industrial wastewater treatment processes. PMID:27330899

  10. Fate of Urea Nitrogen Applied to Rape Grown on a Red Soil and Efficiency of Urea in Raising Rape Yield

    CAIGUI-XIN; WUYI-WEI; 等

    1995-01-01

    Fate of urea nitrogen(N) applied to rape grown on a red soil was investigated by the 15N mass balance technique.and efficiency of urea and effect of nutrients balance in raising rape yield were investigated in a field plot experiment.One hundred and thirty -eight kg N/ha,86kg N/ha as basal dressing and 52 kg N/ha as top dressing,was applied with band application technique.The experiment was conducted in the southeast of china ,near Yingtan City,Jianxi Province.Results from 15N mass balance study showed that when urea urea was applied as basal dressing the plant recovery was 44.0% of the applied N for Treatment T (with application of N,P,K,B and lime),Plant recoveries were 38.0%-40.5% for Treatments-K,-B-lime and+RS(without application of K,B or lime as well as with additional rice straw compared with Teatment T),which were not significantly different from Treatment T.In contrast ,plant recovery was only 5.1% for Treatment-P(without application of P), indicating that P was the factor limiting N uptake by rape.However,N remaining in 0-0.30 m soil was high up to 71.6% for Treatment-P,while the corresponding data were 33.0%-42.6% for the other treatments.The total recovery of applied N(including plant recovery and N remaining in 0-0.60 m soil) was 91.5% for Treatment T when urea was applied as basal dressing,while almost all the applied N was recovered when ureawas applied as top drssing,It was suggested that N loss was greatly controlled by using band application method in this experiment.Results from the field plot experiment field plot experiment showed that N supply capacity of this red soil was very low,and the efficiency of the applied N was quite high,7.1kg rape seed was increased by application of one kg N for Treatment T.Nitrogen and phosphorus were the key factors limiting rape yield,and the yield was very low when neither of them was applied.The yield in Treatment-K was significantly lower than that in Treatment T,With the former accounting for 77% of the

  11. Remote calorimetric detection of urea via flow injection analysis.

    Gaddes, David E; Demirel, Melik C; Reeves, W Brian; Tadigadapa, Srinivas

    2015-12-01

    The design and development of a calorimetric biosensing system enabling relatively high throughput sample analysis are reported. The calorimetric biosensor system consists of a thin (∼20 μm) micromachined Y-cut quartz crystal resonator (QCR) as a temperature sensor placed in close proximity to a fluidic chamber packed with an immobilized enzyme. Layer by layer enzyme immobilization of urease is demonstrated and its activity as a function of the number of layers, pH, and time has been evaluated. This configuration enables a sensing system where a transducer element is physically separated from the analyte solution of interest and is thereby free from fouling effects typically associated with biochemical reactions occuring on the sensor surface. The performance of this biosensing system is demonstrated by detection of 1-200 mM urea in phosphate buffer via a flow injection analysis (FIA) technique. Miniaturized fluidic systems were used to provide continuous flow through a reaction column. Under this configuration the biosensor has an ultimate resolution of less than 1 mM urea and showed a linear response between 0-50 mM. This work demonstrates a sensing modality in which the sensor itself is not fouled or contaminated by the solution of interest and the enzyme immobilized Kapton® fluidic reaction column can be used as a disposable cartridge. Such a system enables reuse and reliability for long term sampling measurements. Based on this concept a biosensing system is envisioned which can perform rapid measurements to detect biomarkers such as glucose, creatinine, cholesterol, urea and lactate in urine and blood continuously over extended periods of time. PMID:26479269

  12. Intermolecular interactions and 3D structure in cellulose-NaOH-urea aqueous system.

    Jiang, Zhiwei; Fang, Yan; Xiang, Junfeng; Ma, Yanping; Lu, Ang; Kang, Hongliang; Huang, Yong; Guo, Hongxia; Liu, Ruigang; Zhang, Lina

    2014-08-28

    The dissolution of cellulose in NaOH/urea aqueous solution at low temperature is a key finding in cellulose science and technology. In this paper, (15)N and (23)Na NMR experiments were carried out to clarify the intermolecular interactions in cellulose/NaOH/urea aqueous solution. It was found that there are direct interactions between OH(-) anions and amino groups of urea through hydrogen bonds and no direct interaction between urea and cellulose. Moreover, Na(+) ions can interact with both cellulose and urea in an aqueous system. These interactions lead to the formation of cellulose-NaOH-urea-H2O inclusion complexes (ICs). (23)Na relaxation results confirmed that the formation of urea-OH(-) clusters can effectively enhance the stability of Na(+) ions that attracted to cellulose chains. Low temperature can enhance the hydrogen bonding interaction between OH(-) ions and urea and improve the binding ability of the NaOH/urea/H2O clusters that attached to cellulose chains. Cryo-TEM observation confirmed the formation of cellulose-NaOH-urea-H2O ICs, which is in extended conformation with mean diameter of about 3.6 nm and mean length of about 300 nm. Possible 3D structure of the ICs was proposed by the M06-2X/6-31+G(d) theoretical calculation, revealing the O3H···O5 intramolecular hydrogen bonds could remain in the ICs. This work clarified the interactions in cellulose/NaOH/urea aqueous solution and the 3D structure of the cellulose chain in dilute cellulose/NaOH/urea aqueous solution. PMID:25111839

  13. Pengaruh Lama Penyimpanan Urea Di Bulk Storage Terhadap Kadar Ammoniak Bebas Pada PT. Pupuk Iskandar Muda

    Agustia, Delvi

    2011-01-01

    Free ammonia is the ammonia that is not perfect react with carbon dioxide during the process of manufacture of urea in the synthesis unit. Free ammonia is not bonded directly to urea but attached to the grain. Free ammonia would be toxic to plants at certain concentrations. Therefore the content of free ammonia in the urea granules have a reference quality Indonesian National Standard (SNI-2801-1992) and Organitation International Standards (ISO), ie, 150 ppm. From the results of my research ...

  14. Effects of Urea and Copper Sulphate on Some Serum Biochemical and Meat Parameters in Broiler Chicken

    A. Rasool, M. Tariq Javed*, Masood Akhtar1, S. Shabbir Bhatti, M. N. Shahzad and Riaz Hussain2

    2013-01-01

    Full Text Available In this study we analysed some of the serum enzymes, urea and creatinine to understand the pathological changes occurring in different organs of broilers due to urea and copper. The feeding for 15 days at or higher than 2% urea + 1gm copper sulphate caused significant rise in serum ALT, AST, AKP and creatinine. With further increase in time of 15 days, the levels of urea and LDH also increased significantly, this was seen even in birds fed 1% urea + 250 mg copper sulphate. We found increase in serum urea even in 1% urea fed birds and in all other groups where combination was used, however, serum creatinine increased significantly (P<0.05 only in birds fed 2% urea+1 gm copper sulphate or higher than these levels. The combined use of urea and copper sulphate resulted in changes in moisture, ash, crude protein and potassium in thigh and breast meat of broilers. The results of the present study suggest damaging effects of higher levels of urea and copper, alone or together and change in meat quality with lower protein contents and higher salt levels in meat of broilers. Thus the use of urea and copper sulphate together is not recommended in broilers, especially at 1% urea and 250mg copper sulphate or higher. The results of the study can be helpful to poultry farmers, pathologists and nutritionists who are involved in augmentation the meat quality and also to general public with special reference to people having hypertension as the meat salt levels may be higher with use of the these compounds in the broiler ration.

  15. Gel Characteristics of Urea-Formaldehyde Resin under Shear Flow Conditions

    Dang-liang Wang; Han-ying Bai; Gao Yue

    2013-01-01

    Urea-formaldehyde resin (UFR), one of chemical grouts in which the major ingredients are urea-formaldehyde and resin, is widely used in Chinese coal mines grouting. The gel characteristics of urea-formaldehyde resin (UFR) chemical grout under static conditions have been studied by many researchers. However, there is little research carried out on the gel characteristics under shear flow conditions. In fact, chemical grout like UFR keeps in shear flow conditions before gelling in the grouting ...

  16. Determing the fate of selected antibiotics during nitrogen recovery via urea-formaldehdye synthesis

    Kashobwe, Lackson

    2016-01-01

    The work presented here focused on the determination of fate of four selected antibiot-ics: enrofloaxicin, oxytetracyline, sulfamethoxazole and tylosin during nitrogen recovery from source separated urine via urea formaldehyde synthesis. The experimental pH was at 2 and temperature at 25°C throughout the chemical reaction, preventing urea hydroly-sis. Five main chemical reactions: aqueous + antibiotics, Urine + formaldehyde + antibi-otics (UF synthesis experiment), urea-formaldehyde polymer +...

  17. Study of Mechanical Properties of Waste Biomass Reinforced Urea-Resorcinol-Formaldehyde Composites

    A. S. Singha; Kaith, B. S.; Inderjeet Kaur; Ashwarya Jyoti Khanna

    2011-01-01

    Natural fibers play an important role in developing high performing fully biodegradable composites which will be a key material to solve the current ecological and environmental problems. Due to enormous advantages of composites reinforced with natural fibers, a study on pine needles reinforced urea-resorcinol-formaldehyde composites has been made. Present investigation has revealed that urea-formaldehyde resin in 1.0: 2.5 ratio exhibits optimum mechanical behavior whereas in case urea-resorc...

  18. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    Mahdavi Fariba; Abdul Rashid Suraya; Khanif Yusop Mohd

    2014-01-01

    In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD) patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR) also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS ...

  19. Infrared studies on o-, m- and p-cresol-urea (1:1) complexes

    Dobrowolski, J. Cz.

    1990-03-01

    Complex formation between urea and o-, m- and p-cresol in 1,2-dichloroethane solutions was investigated by i.r. spectroscopy. Analogical 1:1 urea-phenol complex was reevaluated. Those complexes are formed by CO⋯H hydrogen bonding. In solution the NH urea groups do not play any significant role. The i.r. temperature studies allowed us to determine the enthalpy and entropy of formation of 1:1 complex.

  20. LOW FRACTIONAL EXCRETION OF UREA IN HYPOTHYROIDISM INDUCED HYPONATREMIA

    Algranati L; Imperiali N; Macías Núñez JF; Musso CG

    2005-01-01

    RESUMEN:El hipotiroidismo puede causar alteraciones del metabolismo del agua, los electrolitos, la hemodinamia e histología renales, siendo la hiponatremia y la reducción del filtrado glomerular sus consecuencias más significativas, pero poco prevalentes. Todos estos cambios son corregibles con el suministro de hormona tiroidea exógena.La excreción fraccional de urea (EFU) es un índice útil en la evaluación de la hiponatremia, pero no se ha descripto aun el valor que este índice alcanza en la...

  1. Impact of Creatine on Coordination of Urea and Citrate Cycles

    Kohlíková, E.; Petr, M.; Navrátil, Tomáš; Šenholdová, Z.; Přistoupilová, K.; Přistoupil, T. I.; Heyrovský, Michael; Pelclová, D.

    Praha: IV. interní klinika 1. LF UK Praha, 2006 - (Tvrzická, E.), s. 21-24 ISBN 80-239-7726-1. [Atherosklerosa 2006. Diagnostika, léčba, prevence v dětském i dospělém věku. Praha (CZ), 11.09.2006-13.09.2006] R&D Projects: GA MPO 1H-PK/42; GA MZd NR8107 Institutional research plan: CEZ:AV0Z40400503 Keywords : Atherosclerosis * Citrate cycle * Urea cycle * Blood Subject RIV: CF - Physical ; Theoretical Chemistry

  2. N,N′-Diphenyl­thio­urea acetone monosolvate

    Okuniewski, Andrzej; Chojnacki, Jaroslaw; Becker, Barbara

    2010-01-01

    In the title compound, C13H12N2S·C3H6O, the phenyl rings of the thio­urea mol­ecule are in syn and anti positions in relation to the C=S bond. Two mol­ecules are connected by N—H⋯S=C hydrogen bonds into a centrosymmetric dimer. An additional N—H⋯O=C hydrogen bond to the acetone solvent mol­ecule and some weak C—H⋯π inter­actions reinforce the crystal structure.

  3. LOW DOSE CAPSULE BASED 13C-UREA BREATH TEST COMPARED WITH THE CONVENTIONAL 13C-UREA BREATH TEST AND INVASIVE TESTS

    Rejane MATTAR

    2014-04-01

    Full Text Available Context One of the limitations of 13C-urea breath test for Helicobacter pylori infection diagnosis in Brazil is the substrate acquisition in capsule presentation. Objectives The purpose of this study was to evaluate a capsule-based 13C-urea, manipulated by the Pharmacy Division, for the clinical practice. Methods Fifty patients underwent the conventional and the capsule breath test. Samples were collected at the baseline and after 10, 20 and 30 minutes of 13C-urea ingestion. Urease and histology were used as gold standard in 83 patients. Results In a total of 50 patients, 17 were positive with the conventional 13C-urea (75 mg breath test at 10, 20 and 30 minutes. When these patients repeated breath test with capsule (50 mg, 17 were positive at 20 minutes and 15 at 10 and 30 minutes. The relative sensitivity of 13C-urea with capsule was 100% at 20 minutes and 88.24% at 10 and at 30 minutes. The relative specificity was 100% at all time intervals. Among 83 patients that underwent capsule breath test and endoscopy the capsule breath test presented 100% of sensitivity and specificity. Conclusions Capsule based breath test with 50 mg 13C-urea at twenty minutes was found highly sensitive and specific for the clinical setting. HEADINGS- Helicobacter pylori. Breath Test. Urea, analysis.

  4. Continuous urea-molasses supplementation for Sumatra thin tail ewes grazing in rubber plantation : Reproductive performances.

    Simon P Ginting; L.P Batubara; M.D Sanchez; K.R Pond

    1999-01-01

    The reproductive responses of local Sumatra ewes on the continuous urea-molasses supplementation was studied in 116 ewes for 21 months. The animals were divided into two groups and randomly allocated to urea-molasses supplement and grazing in rubber plantation or grazing in rubber plantation only (control). Both groups were allowed to graze for 8 hours a day. The urea-molasses mixture contained 3% urea (kg/kg) and were fed to the supplemented ewes ad libitum. The number of lambs born from sup...

  5. An overview on the potential of natural products as ureas

    Luzia V. Modolo

    2015-01-01

    Full Text Available Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms’ health and life quality. On the one hand, the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. On the other hand, food production can be negatively affected by ureases of soil microbiota that, in turn, lead to losses of nitrogenous nutrients in fields supplemented with urea as fertilizer. In this context, nature has proven to be a rich resource of natural products bearing a variety of scaffolds that decrease the ureolytic activity of ureases from different organisms. Therefore, this work compiles the state-of-the-art researches focused on the potential of plant natural products (present in extracts or as pure compounds as urease inhibitors of clinical and/or agricultural interests. Emphasis is given to ureases of Helicobacter pylori, Canavalia ensiformis and soil microbiota although the active site of this class of hydrolases is conserved among living organisms.

  6. Voltamperometric Discrimination of Urea and Melamine Adulterated Skimmed Milk Powder

    Eduardo Cortón

    2012-09-01

    Full Text Available Nitrogen compounds like urea and melamine are known to be commonly used for milk adulteration resulting in undesired intoxication; a well-known example is the Chinese episode occurred in 2008. The development of a rapid, reliable and economic test is of relevance in order to improve adulterated milk identification. Cyclic voltammetry studies using an Au working electrode were performed on adulterated and non-adulterated milk samples from different independent manufacturers. Voltammetric data and their first derivative were subjected to functional principal component analysis (f-PCA and correctly classified by the KNN classifier. The adulterated and non-adulterated milk samples showed significant differences. Best results of prediction were obtained with first derivative data. Detection limits in milk samples adulterated with 1% of its total nitrogen derived from melamine or urea were as low as 85.0 mg·L−1 and 121.4 mg·L−1, respectively. We present this method as a fast and robust screening method for milk adulteration analysis and prevention of food intoxication.

  7. Voltamperometric discrimination of urea and melamine adulterated skimmed milk powder.

    Hilding-Ohlsson, Astrid; Fauerbach, Jonathan A; Sacco, Natalia J; Bonetto, M Celina; Cortón, Eduardo

    2012-01-01

    Nitrogen compounds like urea and melamine are known to be commonly used for milk adulteration resulting in undesired intoxication; a well-known example is the Chinese episode occurred in 2008. The development of a rapid, reliable and economic test is of relevance in order to improve adulterated milk identification. Cyclic voltammetry studies using an Au working electrode were performed on adulterated and non-adulterated milk samples from different independent manufacturers. Voltammetric data and their first derivative were subjected to functional principal component analysis (f-PCA) and correctly classified by the KNN classifier. The adulterated and non-adulterated milk samples showed significant differences. Best results of prediction were obtained with first derivative data. Detection limits in milk samples adulterated with 1% of its total nitrogen derived from melamine or urea were as low as 85.0 mg · L(-1) and 121.4 mg · L(-1), respectively. We present this method as a fast and robust screening method for milk adulteration analysis and prevention of food intoxication. PMID:23112709

  8. Voltamperometric Discrimination of Urea and Melamine Adulterated Skimmed Milk Powder

    Hilding-Ohlsson, Astrid; Fauerbach, Jonathan A.; Sacco, Natalia J.; Bonetto, M. Celina; Cortón, Eduardo

    2012-01-01

    Nitrogen compounds like urea and melamine are known to be commonly used for milk adulteration resulting in undesired intoxication; a well-known example is the Chinese episode occurred in 2008. The development of a rapid, reliable and economic test is of relevance in order to improve adulterated milk identification. Cyclic voltammetry studies using an Au working electrode were performed on adulterated and non-adulterated milk samples from different independent manufacturers. Voltammetric data and their first derivative were subjected to functional principal component analysis (f-PCA) and correctly classified by the KNN classifier. The adulterated and non-adulterated milk samples showed significant differences. Best results of prediction were obtained with first derivative data. Detection limits in milk samples adulterated with 1% of its total nitrogen derived from melamine or urea were as low as 85.0 mg·L−1 and 121.4 mg·L−1, respectively. We present this method as a fast and robust screening method for milk adulteration analysis and prevention of food intoxication. PMID:23112709

  9. Solvation of sodium octanoate micelles in concentrated urea solution studied by means of molecular dynamics simulations.

    de Moura, André Farias; Bernardino, Kalil; de Oliveira, Osmair Vital; Freitas, Luiz Carlos Gomide

    2011-12-15

    The effects of urea on self-assembling remains a challenging topic on surface chemistry, and computational modeling may have a role on the unraveling of the molecular mechanisms underlying these effects. Bearing that in mind, we performed a set of molecular dynamics simulations to assess the effects of urea on the self-assembling properties of sodium octanoate, an anionic surfactant, as compared to the aggregation of the same surfactant in pure water as the solvent. The concentration of free monomers increased 3-fold in the presence of urea, in agreement with the accepted view that urea should increase monomer solubility. Regarding the size distribution of micellar aggregates, the urea solution favored smaller micelles and a narrower distribution. Preferential solvation by either water or urea changed along the surfactant molecules, from urea-rich shells around apolar atoms at the end of the hydrophobic tails to nearly no urea at the polar headgroups. This solvation profile is consistent with two different hypotheses from the literature: on one hand, urea molecules interact directly with apolar atoms from the hydrophobic tails, acting as a surfactant, and on the other hand the presence of urea molecules increases the hydration of polar sites. Another important observation regards the solvent structure, which exhibits a complex composition profile around both water and urea molecules. Although the solvent structure was appreciably different in each case, the free energy calculations for the dissociation of a pair of octanoate molecules pointed to a purely enthalpic free energy loss in urea solution, a finding that does not lend support to the third hypothesis that is often claimed as accounting for the urea effects, namely, that urea disrupts water structure and that this structural change decreases the hydrophobic effect due to an entropy change. The presence of urea had no significant effect on the molecular structure of the surfactant molecules, although it

  10. EFFECT OF UREA WITH NUTRISPHERE-N POLYMER IN FALL AND SPRING NITROGEN APPLICATIONS FOR CORN

    Pawel Wiatrak

    2014-01-01

    Full Text Available Polymer coated urea may be a viable option to improve Nitrogen (N uptake and corn (Zea mays L. grain yields, especially in areas with relatively high soil N loss. The objective of this study was to evaluate the effect of two urea application timings (fall and spring and three N rates (90, 180 and 270 kg N ha-1 with and without Nutrisphere-N polymer on irrigated corn near Scandia, KS from 2006 to 2008. Compared to uncoated N, urea coated with Nutrisphere-N improved grain yields by 18.3% with applications of 180 kg N ha-1 in the fall. Application of urea with Nutrisphere-N in the spring produced similar grain yields for treatments with and without Nutrisphere-N. Corn ear-leaf content was highest with urea applied at 90 kg N ha-1 in the fall and urea coated with Nutrisphere-N at 180 and 240 kg N ha-1 in the fall and spring. Grain N content was highest from urea coated with Nutrisphere-N application at 270 kg N ha-1 in the fall and spring. Compared to untreated urea, Nutrisphere-N improved grain N removal by 29.6% at 180 kg N ha-1 applied in the fall. Spring urea application with Nutrisphere-N produced similar grain N removal compared to urea without Nutrisphere-N. Generally, adding Nutrisphere-N to urea fertilizer may help improve N content in leaves and grain and increase grain yields of corn, especially with the fall N applications having higher potential of soil N loss.

  11. Electrochemical behavior of H3PW12O40/ acid-activated bentonite powders

    Mojović Zorica

    2012-01-01

    Full Text Available Electrochemical behavior of 12-tungstophosphoric acid (HPW/acid-activated bentonite (AAB powders with various loadings of HPW was investigated. The physicochemical properties of the prepared powders were examined by X-ray powder diffraction, nitrogen adsorption-desorption isotherms, atomic force microscopy and cyclic voltammetry measurements. The results indicated that the prepared powders are composed mainly of oriented domains of large rock blocks, probably resulting from a preferable deposition of bentonite particles having a face-to-face interaction. The particles had a mainly disordered mesoporous structure with a pore volume that varied according to the pore size in the range of 2-50 nm. In addition, the particles had crystallite size between 4.9 and 9.0 nm. The electrocatalytic activities of prepared HPW/Aelectrodes were studied in the oxidation of NO2-ions and the results revealed that the electrodes possessed relatively higher nitrite oxidation currents than Aelectrode. The best electroactivity was observed for HPW3/Aelectrode (AAB+20 wt. % HPW and the limit of detection (3σ was determined as 8 μM.

  12. Effects of urea foliar application and of ammonium sulphate and urea applied to the soil on yield and N utilization by beans (Phaseolus vulgaris L.)

    The effects of nitrogen applied to the soil (as ammonium sulphate and urea) and foliar application of urea supplementing or not the soil application, on bean yield and nitrogen utilization are studied in a cerrado soil. Labelled ammonium sulphate is applied at the rate of 20Kg N/ha at seeding or 15 or 25 days after seeding and 40 Kg N/ha at seeding or in two different applications. Labelled urea is applied at the rate of 20kg N/ha at seeding and 40 Kg N/ha splitted. Foliar application is done at 15,22, 29,36 and 45 days after seeding, with 2% urea solution labelled with 10% 15N. (M.A.C.)

  13. Evaluation of carbon dioxide emission factor from urea during rice cropping season: A case study in Korean paddy soil

    Kim, Gil Won; Jeong, Seung Tak; Kim, Gun Yeob; Kim, Pil Joo; Kim, Sang Yoon

    2016-08-01

    Fertilization with urea can lead to a loss of carbon dioxide (CO2) that was fixed during the industrial production process. The extent of atmospheric CO2 removal from urea manufacturing was estimated by the Industrial Processes and Product Use sector (IPPU sector). On its basis, the Intergovernmental Panel on Climate Change (IPCC) has proposed a value of 0.2 Mg C per Mg urea (available in 2006 revised IPCC guidelines for greenhouse gas inventories), which is the mass fractions of C in urea, as the CO2 emission coefficient from urea for the agricultural sector. Notably, due to the possibility of bicarbonate leaching to waters, all C in urea might not get released as CO2 to the atmosphere. Hence, in order to provide an accurate value of the CO2 emission coefficient from applied urea in the rice ecosystem, the CO2 emission factors were characterized under different levels of 13C-urea applied paddy field in the current study. The total CO2 fluxes and rice grain yields increased significantly with increasing urea application (110-130 kg N ha-1) and thereafter, decreased. However, with increasing 13C-urea application, a significant and proportional increase of the 13CO2sbnd C emissions from 13C-urea was also observed. From the relationships between urea application levels and 13CO2sbnd C fluxes from 13C-urea, the CO2sbnd C emission factor from urea was estimated to range between 0.0143 and 0.0156 Mg C per Mg urea. Thus, the CO2sbnd C emission factor of this study is less than that of the value proposed by IPCC. Therefore, for the first time, we propose to revise the current IPCC guideline value of CO2sbnd C emission factor from urea as 0.0143-0.0156 Mg C per Mg urea for Korean paddy soils.

  14. Enhancing the urea-N use efficiency in maize (Zea mays) cultivation on acid soils amended with zeolite and TSP.

    Ahmed, Osumanu H; Hussin, Aminuddin; Ahmad, Husni M H; Rahim, Anuar A; Majid, Nik Muhamad Abd

    2008-01-01

    Ammonia loss significantly reduces the urea-N use efficiency in crop production. Efforts to reduce this problem are mostly laboratory oriented. This paper reports the effects of urea amended with triple superphosphate (TSP) and zeolite (Clinoptilolite) on soil pH, nitrate, exchangeable ammonium, dry matter production, N uptake, fresh cob production, and urea-N uptake efficiency in maize (Zea mays) cultivation on an acid soil in actual field conditions. Urea-amended TSP and zeolite treatments and urea only (urea without additives) did not have long-term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf) production of Swan (test crop). All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved urea-N uptake efficiency compared to urea without additives or amendment. This suggests that urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea. PMID:18454247

  15. Enhancing the Urea-N Use Efficiency in Maize (Zea mays Cultivation on Acid Soils Amended with Zeolite and TSP

    Osumanu H. Ahmed

    2008-01-01

    Full Text Available Ammonia loss significantly reduces the urea-N use efficiency in crop production. Efforts to reduce this problem are mostly laboratory oriented. This paper reports the effects of urea amended with triple superphosphate (TSP and zeolite (Clinoptilolite on soil pH, nitrate, exchangeable ammonium, dry matter production, N uptake, fresh cob production, and urea-N uptake efficiency in maize (Zea mays cultivation on an acid soil in actual field conditions. Urea-amended TSP and zeolite treatments and urea only (urea without additives did not have long-term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf production of Swan (test crop. All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved urea-N uptake efficiency compared to urea without additives or amendment. This suggests that urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea.

  16. MICROWAVE ASSISTED PREPARATION OF CYCLIC UREAS FROM DIAMINES IN THE PRESENCE OF ZNO

    A microwave-assisted facile method for the preparation of various ureas, cyclic ureas, and urethanes has been developed that affords nearly quantitative yield of products at 120 degrees C (150 W), 71 kPa within 10 min using ZnO as a catalyst. The enhanced selectivity in this rea...

  17. Salting-out of methane in the aqueous solutions of urea and sarcosine

    M K Dixit; Anupam Chatterjee; B L Tembe

    2016-04-01

    Hydrophobic association and solvation of methane molecules in aqueous solutions of urea and sarcosine (sa) have been studied using MD simulations. The potentials of mean force (PMFs) between methane molecules in water, water-sa, water-urea and water-urea-sa mixtures show an enhancement of methane association on the addition of these osmolytes. These observations are well supported by calculation of equilibrium constants. Calculation of thermodynamic parameters shows that the association of methane is stabilized by entropy and favored by enthalpy. The hydrophobic solvation of methane is stabilized by enthalpy and destabilized by entropy. The calculated solvation free energies of methane in these mixtures show that methane is less soluble in the mixtures of urea and sarcosine than in water. The solubility is the least in the water-urea-sa mixture. Analysis of distributions of solvent and co-solvent around methane suggests that the local densities of both urea and sarcosine are diminished around the methane in the mixtures of these osmolytes. The selective reduction of both urea and sarcosine from methane surface suggests that both urea and sarcosine push methane molecules towards water and increase the interaction between methane molecules i.e., salting-out of methane.

  18. COMPARISON OF THREE ANALYTICAL METHODS TO ASSESS UREA NITROGEN IN COLOSTRUM

    Milk urea nitrogen (MUN) obtained from cows fed mid to late lactation diets has been used as an indicator of diet composition adequacy and can be used to predict urine urea nitrogen. However, recent research has suggested that in early lactation, MUN was positively correlated with feed efficiency (...

  19. 76 FR 78885 - Solid Urea From the Russian Federation and Ukraine: Continuation of Antidumping Duty Orders

    2011-12-20

    ... amended (the Act). See Initiation of Five-Year (``Sunset'') Review, 75 FR 74685 (December 1, 2010); see also Solid Urea From Russia and Ukraine, 75 FR 74746 (December 1, 2010). \\1\\ On July 14, 1987, the... States within a reasonably foreseeable time. See Solid Urea From Russia and Ukraine, 76 FR...

  20. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyamine urea-for-malde-hyde condensate (specific name). 721.6440 Section 721.6440 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.6440 Polyamine urea-for-malde-hyde...

  1. Urea-induced binding between diclofenac sodium and bovine serum albumin: a spectroscopic insight.

    Dohare, Neeraj; Khan, Abbul Bashar; Athar, Fareeda; Thakur, Sonu Chand; Patel, Rajan

    2016-06-01

    We investigated the interaction of diclofenac sodium (Dic.Na) with bovine serum albumin (BSA) in the absence and presence of urea using different spectroscopic techniques. A fluorescence quenching study revealed that the Stern-Volmer quenching constant decreases in the presence of urea, decreasing further at higher urea concentrations. The binding constant and number of binding sites were also evaluated for the BSA-Dic.Na interaction system in the absence and presence of urea using a modified Stern-Volmer equation. The binding constant is greater at high urea concentrations, as shown by the fluorescence results. In addition, for the BSA-Dic.Na interaction system, a static quenching mechanism was observed, which was further confirmed using time-resolved fluorescence spectroscopy. UV-vis spectroscopy provided information about the formation of a complex between BSA and Dic.Na. Circular dichroism was carried out to explain the conformational changes in BSA induced by Dic.Na in the absence and presence of urea. The presence of urea reduced the α-helical content of BSA as the Dic.Na concentration varied. The distance r between the donor (BSA) and acceptor (Dic.Na) was also obtained in the absence and presence of urea, using fluorescence resonance energy transfer. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26564279

  2. Short-term alleviation of aluminum phytotoxicity by urea application in acid soils from south China.

    Qing-ru, Zeng; Bo-han, Liao; Li-tian, Zhang; Xi-hong, Zhou; Hong-xiao, Tang

    2006-05-01

    A laboratory experiment was conducted to study effects of urea fertilizer on the chemical composition of soil solutions over time, and to determine Al toxicity as a function of rates of urea application. The experiment revealed that addition of urea fertilizer to soils caused drastic changes in soil pH during the hydrolysis and nitrification stages of urea transformation in the experiment. These pH changes, depending on the N rate of urea application and time courses, had variable effects on soil exchangeable Al, extracted with artificial solutions containing 1 mol l(-1) KCl. The Al mobilization rate could be resolved into two phases: A declining phase for Al was attributed to the urea-induced hydrolysis while a second rising phase was dependent with the nitrification of added N fertilizer. The decreases in exchangeable Al reached the greatest in 4-7 days after fertilization, consistent with soil pH increase. Decreased Al availability had been observed as a consequence of increasing urea addition and soil pH when using Root elongation of maize seedlings as the estimators. Results from the present study demonstrate that urea fertilizer to the surface of soils may lead to a temporary immobilization of Al and, therefore, alleviated Al toxicity to plant seedlings. PMID:16169044

  3. Oral urea in the treatment of secondary tumours in the liver.

    Clark, P I; Slevin, M L; J. A. Webb; Osborne, R. J.; Jones, S; Wrigley, P F

    1988-01-01

    Twenty patients with secondary liver tumours, predominantly from colorectal carcinoma, were treated with oral urea at a daily dose of 8 gm-2. Treatment was well tolerated without side-effects. No objective responses were seen. It is concluded that oral urea is ineffective in the treatment of liver metastases from colorectal cancer. Images Figure 1

  4. Coating of Prilled Urea with Neem (Azadirachta Indica Juss) Oil for Efficient Nitrogen Use in Rice

    Prasad, R.; Singh, S.; Saxena, V. S.; Devkumar, C.

    A field study made with rice at the Indian Agricultural Research Institute, New Delhi, showed that coating urea with neem oil, neem cake or neem oil microemulsion improved rice growth and resulted in more grain and straw than did commercial prilled urea.

  5. Urea-induced Inactivation and Unfolding of Recombinant Phospholipid Hydroperoxide Glutathione Peroxidase from Oryza sativa

    WANG Feng; ZHOU Hui-ping; KONG Bao-hua; FAN Jing-hua; CHEN Hai-ru; LIU Jin-yuan

    2007-01-01

    Phospholipid hydroperoxide glutathione peroxidase is an antioxidant enzyme that has the highest capability of reducing membrane-bound hydroperoxy lipids as compared to free organic and inorganic hydroperoxides amongst the glutathione peroxidases. In this study, urea-induced effects on the inactivation and unfolding of a recombinant phospholipid hydroperoxide glutathione peroxidase(PHGPx) from Oryza sativa were investigated by means of circular dichroism and fluorescence spectroscopy. With the increase of urea concentration, the residual activity of OsPHGPx decreasea correspondingly. When the urea concentration is above 5.0 mol/L, there was no residual activity. In addition,the observed changes in intrinsic tryptophan fluorescence, the binding of the hydrophobic fluorescence probe ANS,and the far UV CD describe a common dependence on the concentration of urea suggesting that the conformational features of the native OsPHGPx are lost in a highly cooperative single transition. The unfolding process comprises of three zones: the native base-line zone between 0 and 2.5 mol/L urea, the transition zone between 2.5 and 5.5 mol/L urea, and the denatured base-line zone above 5.5 mol/L urea. The transition zone has a midpoint at about 4.0 mol/L urea.

  6. Facile one-pot synthesis of unsymmetrical ureas, carbamates, and thiocarbamates from Cbz-protected amines.

    Kim, Hee-Kwon; Lee, Anna

    2016-07-26

    A novel one-pot synthesis of unsymmetrical ureas, carbamates and thiocarbamates from Cbz-protected amines has been developed. In the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, isocyanates are generated in situ, which facilitate rapid reaction with amines, alcohols, and thiols to afford the corresponding ureas, carbamates and thiocarbamates in high yields. PMID:27406041

  7. Dialysis system. [using ion exchange resin membranes permeable to urea molecules

    Mueller, W. A. (Inventor)

    1978-01-01

    The improved hemodialysis system utilizes a second polymeric membrane having dialyzate in contact with one surface and a urea decomposition solution in contact with the other surface. The membrane selectively passes urea from the dialyzate into the decomposition solution, while preventing passage of positively charged metal ions from the dialyzate into the solution and ammonium ions from the solution into the dialyzate.

  8. Extended structure design with simple molybdenum oxide building blocks and urea as a directing agent

    Veen, S.J.; Roy, S.; Filinchuk, Y.; Chernyshov, D.; Petukhov, A.V.; Versluijs-Helder, M.; Broersma, A.; Soulimani, F.; Visser, T.; Kegel, W.K.

    2008-01-01

    We report here a simple one-pot directed synthesis of an oxomolybdate urea composite in which elementary molybdenum oxide building blocks are linked together with the aid of urea. This type of directed material design resulted in large rod-like crystals of an inorganic-organic hybrid extended struct

  9. Regulation of urea synthesis during the acute phase response in rats

    Thomsen, Karen Louise; Jessen, Niels; Buch Møller, Andreas;

    2013-01-01

    the tumor necrosis factor-α (TNF-α)-induced acute-phase response in rats. We used four methods to study the regulation of urea synthesis: We examined urea cycle enzyme mRNA levels in liver tissue, the hepatocyte urea cycle enzyme proteins, the in vivo capacity of urea-N synthesis (CUNS), and known...... humoral regulators of CUNS at 1, 3, 24, and 72 h after TNF-α injection (25 μg/kg iv rrTNF-α) in rats. Serum acute-phase proteins and their liver mRNA levels were also measured. The urea cycle enzyme mRNA levels acutely decreased and then gradually normalized, whereas the urea cycle enzyme proteins......The acute-phase response is a catabolic event involving increased waste of amino-nitrogen (N) via hepatic urea synthesis, despite an increased need for amino-N incorporation into acute-phase proteins. This study aimed to clarify the regulation of N elimination via urea during different phases of...

  10. Theoretical studies of urea adsorption on single wall boron-nitride nanotubes

    Graphical abstract: - Highlights: • DFT base investigations of urea molecule with various type of armchair BNNTs studied. • The adsorption of urea molecule is observed to be exothermic and physical in nature. • The most effective interaction occurs when urea located inside of BNNTs. • The electronic analysis indicated ΔEg values changed after urea adsorption. - Abstract: Surface modification of a boron nitride nanotube (BNNT) with urea molecule was investigated in terms of its energetic, geometric, and electronic properties using B3LYP and PW91 density functionals. In this investigation, various armchair (n,n) nanotubes, where n = 5, 6, 7 have been used. Two different interaction modes, including interaction with outer layer and inner layer of tube were studied. The results indicated that the adsorption of single urea molecule in all of its configurations is observed to be exothermic and physical in nature. Interestingly, the adsorption energy for the most stable configuration of urea was observed when the molecule located inside of the nanotube. Besides, the adsorption of urea on BNNTs changes the conductivity of nanotube