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Sample records for acid-activated urea transporter

  1. Structure of Urea Transporters

    OpenAIRE

    Levin, Elena J.; Zhou, Ming

    2014-01-01

    Members of the urea transporter (UT) family mediate rapid, selective transport of urea down its concentration gradient. To date, crystal structures of two evolutionarily distant UTs have been solved. These structures reveal a common UT fold involving two structurally homologous domains that encircle a continuous membrane-spanning pore, and indicate that UTs transport urea via a channel-like mechanism. Examination of the conserved architecture of the pore, combined with crystal structures of l...

  2. Small-Molecule Inhibitors of Urea Transporters

    Science.gov (United States)

    Verkman, Alan S.; Esteva-Font, Cristina; Cil, Onur; Anderson, Marc O.; Li, Fei; Li, Min; Lei, Tianluo; Ren, Huiwen; Yang, Baoxue

    2015-01-01

    Urea transporter (UT) proteins, which include isoforms of UT-A in kidney tubule epithelia and UT-B in vasa recta endothelia and erythrocytes, facilitate urinary concentrating function. Inhibitors of urea transporter function have potential clinical applications as sodium-sparing diuretics, or ‘urearetics,’ in edema from different etiologies, such as congestive heart failure and cirrhosis, as well as in syndrome of inappropriate antidiuretic hormone (SIADH). High-throughput screening of drug-like small molecules has identified UT-A and UT-B inhibitors with nanomolar potency. Inhibitors have been identified with different UT-A versus UT-B selectivity profiles and putative binding sites on UT proteins. Studies in rodent models support the utility of UT inhibitors in reducing urinary concentration, though testing in clinically relevant animal models of edema has not yet been done. PMID:25298345

  3. Urea transporters and sweat response to uremia.

    Science.gov (United States)

    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. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  4. Molecular Mechanisms of Urea Transport in Health and Disease

    Science.gov (United States)

    Klein, Janet D.; Blount, Mitsi A.; Sands, Jeff M.

    2012-01-01

    In the late 1980s, urea permeability measurements produced values that could not be explained by paracellular transport or lipid phase diffusion. The existence of urea transport proteins were thus proposed and less than a decade later, the first urea transporter was cloned. The SLC14A family of urea transporters has two major subgroups, designated SLC14A1 (or UT-B) and Slc14A2 (or UT-A). UT-B and UT-A gene products are glycoproteins located in various extra-renal tissues however, a majority of the resulting isoforms are found in the kidney. The UT-B (Slc14A1) urea transporter was originally isolated from erythrocytes and two isoforms have been reported. In kidney, UT-B is located primarily in the descending vasa recta. The UT-A (Slc14A2) urea transporter yields 6 distinct isoforms, of which 3 are found chiefly in the kidney medulla. UT-A1 and UT-A3 are found in the inner medullary collecting duct (IMCD), while UT-A2 is located in the thin descending limb. These transporters are crucial to the kidney’s ability to concentrate urine. The regulation of urea transporter activity in the IMCD involves acute modification through phosphorylation and subsequent movement to the plasma membrane. UT-A1 and UT-A3 accumulate in the plasma membrane in response to stimulation by vasopressin or hypertonicity. Long term regulation of the urea transporters in the IMCD involves altering protein abundance in response to changes in hydration status, low protein diets, or adrenal steroids. Urea transporters have been studied using animal models of disease including diabetes mellitus, lithium intoxication, hypertension, and nephrotoxic drug responses. Exciting new genetically engineered mouse models are being developed to study these transporters. PMID:23007461

  5. Active urea transport in lower vertebrates and mammals.

    Science.gov (United States)

    Bankir, Lise

    2014-01-01

    Some unicellular organisms can take up urea from the surrounding fluids by an uphill pumping mechanism. Several active (energy-dependent) urea transporters (AUTs) have been cloned in these organisms. Functional studies show that active urea transport also occurs in elasmobranchs, amphibians, and mammals. In the two former groups, active urea transport may serve to conserve urea in body fluids in order to balance external high ambient osmolarity or prevent desiccation. In mammals, active urea transport may be associated with the need to either store and/or reuse nitrogen in the case of low nitrogen supply, or to excrete nitrogen efficiently in the case of excess nitrogen intake. There are probably two different families of AUTs, one with a high capacity able to establish only a relatively modest transepithelial concentration difference (renal tubule of some frogs, pars recta of the mammalian kidney, early inner medullary collecting duct in some mammals eating protein-poor diets) and others with a low capacity but able to maintain a high transepithelial concentration difference that has been created by another mechanism or in another organ (elasmobranch gills, ventral skin of some toads, and maybe mammalian urinary bladder). Functional characterization of these transporters shows that some are coupled to sodium (symports or antiports) while others are sodium-independent. In humans, only one genetic anomaly, with a mild phenotype (familial azotemia), is suspected to concern one of these transporters. In spite of abundant functional evidence for such transporters in higher organisms, none have been molecularly identified yet.

  6. Role of thin descending limb urea transport in renal urea handling and the urine concentrating mechanism

    Science.gov (United States)

    Lei, Tianluo; Zhou, Lei; Layton, Anita T.; Zhou, Hong; Zhao, Xuejian; Bankir, Lise

    2011-01-01

    Urea transporters UT-A2 and UT-B are expressed in epithelia of thin descending limb of Henle's loop and in descending vasa recta, respectively. To study their role and possible interaction in the context of the urine concentration mechanism, a UT-A2 and UT-B double knockout (UT-A2/B knockout) mouse model was generated by targeted deletion of the UT-A2 promoter in embryonic stem cells with UT-B gene knockout. The UT-A2/B knockout mice lacked detectable UT-A2 and UT-B transcripts and proteins and showed normal survival and growth. Daily urine output was significantly higher in UT-A2/B knockout mice than that in wild-type mice and lower than that in UT-B knockout mice. Urine osmolality in UT-A2/B knockout mice was intermediate between that in UT-B knockout and wild-type mice. The changes in urine osmolality and flow rate, plasma and urine urea concentration, as well as non-urea solute concentration after an acute urea load or chronic changes in protein intake suggested that UT-A2 plays a role in the progressive accumulation of urea in the inner medulla. These results suggest that in wild-type mice UT-A2 facilitates urea absorption by urea efflux from the thin descending limb of short loops of Henle. Moreover, UT-A2 deletion in UT-B knockout mice partially remedies the urine concentrating defect caused by UT-B deletion, by reducing urea loss from the descending limbs to the peripheral circulation; instead, urea is returned to the inner medulla through the loops of Henle and the collecting ducts. PMID:21849488

  7. Structure and permeation mechanism of a mammalian urea transporter

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Elena J.; Cao, Yu; Enkavi, Giray; Quick, Matthias; Pan, Yaping; Tajkhorshid, Emad; Zhou, Ming (UIUC); (Columbia)

    2012-09-17

    As an adaptation to infrequent access to water, terrestrial mammals produce urine that is hyperosmotic to plasma. To prevent osmotic diuresis by the large quantity of urea generated by protein catabolism, the kidney epithelia contain facilitative urea transporters (UTs) that allow rapid equilibration between the urinary space and the hyperosmotic interstitium. Here we report the first X-ray crystal structure of a mammalian UT, UT-B, at a resolution of 2.36 {angstrom}. UT-B is a homotrimer and each protomer contains a urea conduction pore with a narrow selectivity filter. Structural analyses and molecular dynamics simulations showed that the selectivity filter has two urea binding sites separated by an approximately 5.0 kcal/mol energy barrier. Functional studies showed that the rate of urea conduction in UT-B is increased by hypoosmotic stress, and that the site of osmoregulation coincides with the location of the energy barrier.

  8. Generation and phenotypic analysis of mice lacking all urea transporters.

    Science.gov (United States)

    Jiang, Tao; Li, Yingjie; Layton, Anita T; Wang, Weiling; Sun, Yi; Li, Min; Zhou, Hong; Yang, Baoxue

    2017-02-01

    Urea transporters (UT) are a family of transmembrane urea-selective channel proteins expressed in multiple tissues and play an important role in the urine concentrating mechanism of the mammalian kidney. UT inhibitors have diuretic activity and could be developed as novel diuretics. To determine if functional deficiency of all UTs in all tissues causes physiological abnormality, we established a novel mouse model in which all UTs were knocked out by deleting an 87 kb of DNA fragment containing most parts of Slc14a1 and Slc14a2 genes. Western blot analysis and immunofluorescence confirmed that there is no expression of urea transporter in these all-UT-knockout mice. Daily urine output was nearly 3.5-fold higher, with significantly lower urine osmolality in all-UT-knockout mice than that in wild-type mice. All-UT-knockout mice were not able to increase urinary urea concentration and osmolality after water deprivation, acute urea loading, or high protein intake. A computational model that simulated UT-knockout mouse models identified the individual contribution of each UT in urine concentrating mechanism. Knocking out all UTs also decreased the blood pressure and promoted the maturation of the male reproductive system. Thus, functional deficiency of all UTs caused a urea-selective urine-concentrating defect with little physiological abnormality in extrarenal organs. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  9. Crystal structure of a bacterial homologue of the kidney urea transporter

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Elena J.; Quick, Matthias; Zhou, Ming; (Columbia)

    2010-03-19

    Urea is highly concentrated in the mammalian kidney to produce the osmotic gradient necessary for water re-absorption. Free diffusion of urea across cell membranes is slow owing to its high polarity, and specialized urea transporters have evolved to achieve rapid and selective urea permeation. Here we present the 2.3 {angstrom} structure of a functional urea transporter from the bacterium Desulfovibrio vulgaris. The transporter is a homotrimer, and each subunit contains a continuous membrane-spanning pore formed by the two homologous halves of the protein. The pore contains a constricted selectivity filter that can accommodate several dehydrated urea molecules in single file. Backbone and side-chain oxygen atoms provide continuous coordination of urea as it progresses through the filter, and well-placed {alpha}-helix dipoles provide further compensation for dehydration energy. These results establish that the urea transporter operates by a channel-like mechanism and reveal the physical and chemical basis of urea selectivity.

  10. Urea transport mediated by aquaporin water channel proteins.

    Science.gov (United States)

    Li, Chunling; Wang, Weidong

    2014-01-01

    Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen aquaporins have been characterized. They are distributed wildly in specific cell types in multiple organs and tissues. Each AQP channel consists of six membrane-spanning alpha-helices that have a central water-transporting pore. Four AQP monomers assemble to form tetramers, which are the functional units in the membrane. Some of AQPs also transport urea, glycerol, ammonia, hydrogen peroxide, and gas molecules. AQP-mediated osmotic water transport across epithelial plasma membranes facilitates transcellular fluid transport and thus water reabsorption. AQP-mediated urea and glycerol transport is involved in energy metabolism and epidermal hydration. AQP-mediated CO2 and NH3 transport across membrane maintains intracellular acid-base homeostasis. AQPs are also involved in the pathophysiology of a wide range of human diseases (including water disbalance in kidney and brain, neuroinflammatory disease, obesity, and cancer). Further work is required to determine whether aquaporins are viable therapeutic targets or reliable diagnostic and prognostic biomarkers.

  11. Diabetes induced renal urea transport alterations assessed with 3D hyperpolarized 13 C,15 N-Urea.

    Science.gov (United States)

    Bertelsen, Lotte B; Nielsen, Per M; Qi, Haiyun; Nørlinger, Thomas S; Zhang, Xiaolu; Stødkilde-Jørgensen, Hans; Laustsen, Christoffer

    2017-04-01

    In the current study, we investigated hyperpolarized urea as a possible imaging biomarker of the renal function by means of the intrarenal osmolality gradient. Hyperpolarized three-dimensional balanced steady state 13 C MRI experiments alongside kidney function parameters and quantitative polymerase chain reaction measurements was performed on two groups of rats, a streptozotocin type 1 diabetic group and a healthy control group. A significant decline in intrarenal steepness of the urea gradient was found after 4 weeks of untreated insulinopenic diabetes in agreement with an increased urea transport transcription. MRI and hyperpolarized [13 C,15 N]urea can monitor the changes in the corticomedullary urea concentration gradients in diabetic and healthy control rats. Magn Reson Med 77:1650-1655, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  12. The emerging physiological roles of the SLC14A family of urea transporters

    Science.gov (United States)

    Stewart, Gavin

    2011-01-01

    In mammals, urea is the main nitrogenous breakdown product of protein catabolism and is produced in the liver. In certain tissues, the movement of urea across cell membranes is specifically mediated by a group of proteins known as the SLC14A family of facilitative urea transporters. These proteins are derived from two distinct genes, UT-A (SLC14A2) and UT-B (SLC14A1). Facilitative urea transporters play an important role in two major physiological processes – urinary concentration and urea nitrogen salvaging. Although UT-A and UT-B transporters both have a similar basic structure and mediate the transport of urea in a facilitative manner, there are a number of significant differences between them. UT-A transporters are mainly found in the kidney, are highly specific for urea, have relatively lower transport rates and are highly regulated at both gene expression and cellular localization levels. In contrast, UT-B transporters are more widespread in their tissue location, transport both urea and water, have a relatively high transport rate, are inhibited by mercurial compounds and currently appear to be less acutely regulated. This review details the fundamental research that has so far been performed to investigate the function and physiological significance of these two types of urea transporters. PMID:21449978

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

    DEFF Research Database (Denmark)

    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 mechanism(s) of transperitoneal urea transport and to test the one-compartment assumption for urea. A total of 12 nested models were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The validation procedure demonstrated...... that transperitoneal transport of urea probably involves diffusion, non-lymphatic convection and lymphatic convection. It was furthermore demonstrated that the inclusion of lymphatic convection changes the mass transfer area coefficient considerably. Finally, no deviation from the one-compartment assumption...

  14. Urea transporter proteins as targets for small-molecule diuretics.

    Science.gov (United States)

    Esteva-Font, Cristina; Anderson, Marc O; Verkman, Alan S

    2015-02-01

    Conventional diuretics such as furosemide and thiazides target salt transporters in kidney tubules, but urea transporters (UTs) have emerged as alternative targets. UTs are a family of transmembrane channels expressed in a variety of mammalian tissues, in particular the kidney. UT knockout mice and humans with UT mutations exhibit reduced maximal urinary osmolality, demonstrating that UTs are necessary for the concentration of urine. Small-molecule screening has identified potent and selective inhibitors of UT-A, the UT protein expressed in renal tubule epithelial cells, and UT-B, the UT protein expressed in vasa recta endothelial cells. Data from UT knockout mice and from rodents administered UT inhibitors support the diuretic action of UT inhibition. The kidney-specific expression of UT-A1, together with high selectivity of the small-molecule inhibitors, means that off-target effects of such small-molecule drugs should be minimal. This Review summarizes the structure, expression and function of UTs, and looks at the evidence supporting the validity of UTs as targets for the development of salt-sparing diuretics with a unique mechanism of action. UT-targeted inhibitors may be useful alone or in combination with conventional diuretics for therapy of various oedemas and hyponatraemias, potentially including those refractory to treatment with current diuretics.

  15. Short communication: Assessing urea transport from milk to blood in dairy cows

    NARCIS (Netherlands)

    Spek, J.W.; Dijkstra, J.; Borne, van den J.J.G.C.; Bannink, A.

    2012-01-01

    The concentration of urea in milk (MUC) has emerged as a potentially useful tool to predict urinary N excretion. Various factors may affect the relationship between MUC and urinary N excretion, including transport characteristics of urea from blood to milk and vice versa. The main objective of this

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

    OpenAIRE

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

    2013-01-01

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Rapoport, J.; Abuful, A.; Chaimovitz, C.; Noeh, Z.; Hays, R.M. (Soroka Medical Center, Beersheva (Israel) Albert Einstein College of Medicine, New York, NY (USA))

    1988-09-01

    Urea is actively transported inwardly (J{sub i}) across the skin of the green toad Bufo viridis. J{sub i} 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{sup {minus}4} M) significantly inhibited J{sub i} in both adapted and unadapted animals and was unaffected by removal of sodium from the external medium. Phloretin (10{sup {minus}4} M) significantly inhibited J{sub i} in adapted animals by 23-46%; there was also a reduction in J{sub i} in unadapted toads at 10{sup {minus}4} and 5 {times} 10{sup {minus}4} M phloretin. A dose-response study revealed that the concentration of phloretin causing half-maximal inhibition (K{sub {1/2}}) was 5 {times} 10{sup {minus}4} M for adapted animals. J{sub i} 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 J{sub i} is independent of sodium transport.

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

    Science.gov (United States)

    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 classical random mutagenesis, led to the identification of amino acids important for UreA function. Our approach allowed us to suggest roles for these residues in the binding, recognition and translocation of urea, and in the sorting of UreA to the membrane. Residues W82, Y106, A110, T133, N275, D286, Y388, Y437 and S446, located in transmembrane helixes 2, 3, 7 and 11, were found to be involved in the binding, recognition and/or translocation of urea and the sorting of UreA to the membrane. Y106, A110, T133 and Y437 seem to play a role in substrate selectivity, while S446 is necessary for proper sorting of UreA to the membrane. Other amino acids identified by random classical mutagenesis (G99, R141, A163, G168 and P639) may be important for the basic transporter's structure, its proper folding or its correct traffic to the membrane. PMID:24966243

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Thienoquinolins exert diuresis by strongly inhibiting UT-A urea transporters

    Science.gov (United States)

    Ren, Huiwen; Wang, Yanhua; Xing, Yongning; Ran, Jianhua; Liu, Ming; Lei, Tianluo; Zhou, Hong; Li, Runtao; Sands, Jeff M.

    2014-01-01

    Urea transporters (UT) play an important role in the urine concentration mechanism by mediating intrarenal urea recycling, suggesting that UT inhibitors could have therapeutic use as a novel class of diuretic. Recently, we found a thienoquinolin UT inhibitor, PU-14, that exhibited diuretic activity. The purpose of this study was to identify more potent UT inhibitors that strongly inhibit UT-A isoforms in the inner medullary collecting duct (IMCD). Efficient thienoquinolin UT inhibitors were identified by structure-activity relationship analysis. Urea transport inhibition activity was assayed in perfused rat terminal IMCDs. Diuretic activity of the compound was determined in rats and mice using metabolic cages. The results show that the compound PU-48 exhibited potent UT-A inhibition activity. The inhibition was 69.5% with an IC50 of 0.32 μM. PU-48 significantly inhibited urea transport in perfused rat terminal IMCDs. PU-48 caused significant diuresis in UT-B null mice, which indicates that UT-A is the target of PU-48. The diuresis caused by PU-48 did not change blood Na+, K+, or Cl− levels or nonurea solute excretion in rats and mice. No toxicity was detected in cells or animals treated with PU-48. The results indicate that thienoquinolin UT inhibitors induce a diuresis by inhibiting UT-A in the IMCD. This suggests that they may have the potential to be developed as a novel class of diuretics with fewer side effects than classical diuretics. PMID:25298523

  2. Immunohistochemical localization of urea transporters A and B in the rat cochlea.

    Science.gov (United States)

    Kwun, Yong-Sig; Yeo, Sang W; Ahn, Yang-Heui; Lim, Sun-Woo; Jung, Ju-Young; Kim, Wan-Young; Sands, Jeff M; Kim, Jin

    2003-09-01

    Urea is present in the inner ear, and when it is administered, induces rapid changes in the volume and osmolality of the inner ear fluid. However, the regulating mechanisms are unknown. Two groups of urea transporters (UTs), the renal urea transporter (UT-A) and the erythrocyte urea transporter (UT-B) have been cloned recently. The aims of the current study were to investigate the cellular localization of UTs in the cochlea of male Sprague-Dawley rats by immunohistochemistry. Both UT-A1 and UT-B were expressed in the inner and outer pillar cells, inner and outer hair cells, Boettcher's cells, and Deiters' cells in the organ of Corti. Immunoreactivity for UT-A3 was localized only in the mesothelial cells underlying the basilar membrane. In the stria vascularis, UT-A1 was expressed only in the marginal cells, whereas UT-B was expressed only in the basal cells. In the spiral ganglion, most cells had strong UT-A1 immunoreactivity whereas UT-B was not expressed. In the spiral limbus, UT-B was expressed in the interdental cells whereas UT-A was not expressed. In the crista ampullaris, UT-A1 was expressed in the dark cells, and UT-B expressed in the apical membrane of supporting cells in the neuroepithelium. The distribution of UT-A and UT-B in the inner ear suggests that the cells that surround the inner ear fluids may be involved in urea transport and thus play an important role in fluid homeostasis in the inner ear. The expression of UT-A and UT-B in the hair cells raises the possibility that UTs may be involved in volume regulation in these cells and mediate hair cell turgor.

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

    Science.gov (United States)

    Musa-Aziz, Raif; Enkavi, Giray; Mahinthichaichan, P.; Tajkhorshid, Emad; Boron, Walter F.

    2013-01-01

    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

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

    Science.gov (United States)

    Azouzi, Slim; Gueroult, Marc; Ripoche, Pierre; Genetet, Sandrine; Colin Aronovicz, Yves; Le Van Kim, Caroline; Etchebest, Catherine; Mouro-Chanteloup, Isabelle

    2013-01-01

    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.

  5. UT-B Urea Transporter Localization in the Bovine Gastrointestinal Tract.

    Science.gov (United States)

    Coyle, J; McDaid, S; Walpole, C; Stewart, Gavin S

    2016-04-01

    Facilitative UT-B urea transporters play an important role in the urea nitrogen salvaging process that occurs in the gastrointestinal tract of mammals, particularly ruminants. Gastrointestinal UT-B transporters have previously been reported in various ruminant species-including cow, sheep and goat. In this present study, UT-B transporter localization was investigated in tissues throughout the bovine gastrointestinal tract. RT-PCR analysis showed that UT-B2 was the predominant UT-B mRNA transcript expressed in dorsal, ventral and cranial ruminal sacs, while alternative UT-B transcripts were present in other gastrointestinal tissues. Immunoblotting analysis detected a strong, glycosylated ~50 kDa UT-B2 protein in all three ruminal sacs. Immunolocalization studies showed that UT-B2 protein was predominantly localized to the plasma membrane of cells in the stratum basale layer of all ruminal sac papillae. In contrast, other UT-B protein staining was detected in the basolateral membranes of the surface epithelial cells lining the abomasum, colon and rectum. Overall, these findings confirm that UT-B2 cellular localization is similar in all ruminal sacs and that other UT-B proteins are located in epithelial cells lining various tissues in the bovine gastrointestinal tract.

  6. One-Pot Synthesis and Transmembrane Chloride Transport Properties of C3-Symmetric Benzoxazine Urea.

    Science.gov (United States)

    Roy, Arundhati; Saha, Debasis; Mukherjee, Arnab; Talukdar, Pinaki

    2016-11-18

    One-pot synthesis of a C 3 -symmetric benzoxazine-based tris-urea compound is discussed. 1 H NMR titrations indicate a stronger Cl - binding compared that of Br - and I - by the receptor. Effective Cl - transport across liposomal membranes via a Cl - /X - antiport mechanism is confirmed. Theoretical calculation suggests that a few water molecules with N-H, C═O, and the aromatic ring of the receptor create a H-bonded polar cavity where a Cl - is recognized by O-H···Cl - interactions from five bridged water molecules.

  7. Application of a data assimilation method via an ensemble Kalman filter to reactive urea hydrolysis transport modeling

    Energy Technology Data Exchange (ETDEWEB)

    Juxiu Tong; Bill X. Hu; Hai Huang; Luanjin Guo; Jinzhong Yang

    2014-03-01

    With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations, we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study.

  8. Organic manure and urea effect on metolachlor transport through packed soil columns.

    Science.gov (United States)

    Singh, Neera

    2003-01-01

    Application of organic manure (OM) amendments and nitrogen fertilizers can affect the sorption and movement of pesticides in soil. This study summarizes the sorption and leaching of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylphenyl) acetamide] in soils after cow (Bos taurus) manure (2.5 and 5.0%) and urea (60 and 120 kg N ha(-1)) amendments in batch and column experiments. Both cow manure and urea applications increased metolachlor sorption in soils. The values of the Freundlich adsorption parameter K(r)(1/n) for treatments T0, T1 (OM), and T2 (OM) were 2.31, 3.32, and 3.96 in Soil 1; 2.02, 2.77, and 3.32 in Soil 2; and 1.10, 1.46, and 2.02 in Soil 3, respectively. Similarly, K(f)(1/n) values for treatment T1 (urea) and T2 (urea) were 2.37 and 2.84 in Soil 1; 2.16 and 2.83 in Soil 2; and 1.50 and 1.70 in Soil 3, respectively. Column leaching studies using Soil 1 indicated that OM application drastically reduced the metolachlor leaching losses from 50% (natural soil) to soil. Therefore, coapplication of metolachlor with cow manure or urea fertilizers will not enhance metolachlor mobility and reduces metolachlor leaching losses in low-organic-matter soil.

  9. Urea metabolism in plants.

    Science.gov (United States)

    Witte, Claus-Peter

    2011-03-01

    Urea is a plant metabolite derived either from root uptake or from catabolism of arginine by arginase. In agriculture, urea is intensively used as a nitrogen fertilizer. Urea nitrogen enters the plant either directly, or in the form of ammonium or nitrate after urea degradation by soil microbes. In recent years various molecular players of plant urea metabolism have been investigated: active and passive urea transporters, the nickel metalloenzyme urease catalyzing the hydrolysis of urea, and three urease accessory proteins involved in the complex activation of urease. The degradation of ureides derived from purine breakdown has long been discussed as a possible additional metabolic source for urea, but an enzymatic route for the complete hydrolysis of ureides without a urea intermediate has recently been described for Arabidopsis thaliana. This review focuses on the proteins involved in plant urea metabolism and the metabolic sources of urea but also addresses open questions regarding plant urea metabolism in a physiological and agricultural context. The contribution of plant urea uptake and metabolism to fertilizer urea usage in crop production is still not investigated although globally more than half of all nitrogen fertilizer is applied to crops in the form of urea. Nitrogen use efficiency in crop production is generally well below 50% resulting in economical losses and creating ecological problems like groundwater pollution and emission of nitric oxides that can damage the ozone layer and function as greenhouse gasses. Biotechnological approaches to improve fertilizer urea usage bear the potential to increase crop nitrogen use efficiency. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  10. Seasonal variation and response to osmotic challenge in urea transporter expression in the dehydration- and freeze-tolerant wood frog, Rana sylvatica.

    Science.gov (United States)

    Rosendale, Andrew J; Costanzo, Jon P; Lee, Richard E

    2012-08-01

    Urea accumulation is a universal response to osmotic challenge in anuran amphibians, and facilitative urea transporters (UTs) seem to play an important role in this process by acting in the osmoregulatory organs to mediate urea retention. Although UTs have been implicated in urea reabsorption in anurans, little is known about the physiological regulation of UT protein abundance. We examined seasonal variation in and effects of osmotic challenge on UT protein and mRNA levels in kidney and urinary bladder of the wood frog (Rana sylvatica), a terrestrial species that tolerates both dehydration and tissue freezing. Using immunoblotting techniques to measure relative UT abundance, we found that UT numbers varied seasonally, with a low abundance prevailing in the fall and winter, and higher levels occurring in the spring. Experimental dehydration of frogs increased UT protein abundance in the urinary bladder, whereas experimental urea loading decreased the abundance of UTs in kidney and bladder. Experimental freezing, whether or not followed by thawing, had no effect on UT numbers. UT mRNA levels, assessed using quantitative real-time polymerase chain reaction, did not change seasonally nor in response to any of our experimental treatments. These findings suggest that regulation of UTs depends on the nature and severity of the osmotic stress and apparently occurs posttranscriptionally in response to multiple physiological factors. Additionally, UTs seem to be regulated to meet the physiological need to accumulate urea, with UT numbers increasing to facilitate urea reabsorption and decreasing to prevent retention of excess urea. © 2012 WILEY PERIODICALS, INC.

  11. Increased gene expression of a facilitated diffusion urea transporter in the skin of the African lungfish (Protopterus annectens) during massively elevated post-terrestrialization urea excretion

    National Research Council Canada - National Science Library

    Hung, Carrie Y C; Galvez, Fernando; Ip, Yuen K; Wood, Chris M

    2009-01-01

    .... Upon re-immersion in water after 33 days of air exposure ('terrestrialization'), lungfish exhibited a massive rise in urea-N excretion which peaked at 12-30 h with rates of 2000-5000 micromol-N kg(-1) h(-1...

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

    OpenAIRE

    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 ...

  13. Comparative physiology and architecture associated with the mammalian urine concentrating mechanism: role of inner medullary water and urea transport pathways in the rodent medulla

    Science.gov (United States)

    2013-01-01

    Comparative studies of renal structure and function have potential to provide insights into the urine-concentrating mechanism of the mammalian kidney. This review focuses on the tubular transport pathways for water and urea that play key roles in fluid and solute movements between various compartments of the rodent renal inner medulla. Information on aquaporin water channel and urea transporter expression has increased our understanding of functional segmentation of medullary thin limbs of Henle's loops, collecting ducts, and vasa recta. A more complete understanding of membrane transporters and medullary architecture has identified new and potentially significant interactions between these structures and the interstitium. These interactions are now being introduced into our concept of how the inner medullary urine-concentrating mechanism works. A variety of regulatory pathways lead directly or indirectly to variable patterns of fluid and solute movements among the interstitial and tissue compartments. Animals with the ability to produce highly concentrated urine, such as desert species, are considered to exemplify tubular structure and function that optimize urine concentration. These species may provide unique insights into the urine-concentrating process.1 PMID:23364530

  14. Patterns of nitrogenous waste excretion and gill urea transporter mRNA expression in various species of marine fish

    OpenAIRE

    Walsh, P J; Wang, Y.; Campbell, C. E.; De Boeck, G; Wood, C M

    2001-01-01

    Many prior studies of nitrogenous waste excretion in marine fish have examined excretion patterns for short time periods, and with relatively coarse sampling schemes (e.g., an initial and a final sample point). Recent studies of a ureotelic marine fish (the gulf toadfish, Opsanus beta) have demonstrated that urea excretion in this species occurs in brief but massive bursts, lasting from 0.5 to 3 h, and often only once per day. The present study sought to determine if prior sampling protocols ...

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

    Science.gov (United States)

    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.

  16. Orphan drugs in development for urea cycle disorders: current perspectives

    Directory of Open Access Journals (Sweden)

    Häberle J

    2014-09-01

    Full Text Available Johannes Häberle,1 Shawn E McCandless2 1Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland; 2Center for Human Genetics, University Hospitals Case Medical Center, and Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA Abstract: The urea cycle disorders are caused by deficiency of one of the six hepatic enzymes or two transporters involved in detoxification of ammonia. The resulting hyperammonemia causes severe brain injury unless aggressive steps are taken to reduce the accumulation of ammonia, which is thought to be the most toxic metabolite. This review describes the current state of chronic management of urea cycle disorders, focusing on new and emerging therapies. Management strategies include the mainstay of treatment, namely dietary protein restriction and supplementation with l-arginine or l-citrulline. Several currently approved medications utilize and enhance alternative pathways of waste nitrogen excretion (sodium benzoate, sodium phenylacetate, sodium phenylbutyrate in several formulations, and glycerol phenylbutyrate, working through conjugation of the drug to either glycine (in the case of benzoate or glutamine, the products of which are excreted in the urine. Carglumic acid activates the first committed step of conversion of ammonia to urea, carbamoylphosphate synthetase, and thus effectively treats defective synthesis of the endogenous activator, N-acetylglutamate, whether due to genetic defects or biochemical inhibition of the N-acetylglutamate synthase enzyme. Approaches to neuroprotection during episodes of hyperammonemia are discussed, including the use of controlled hypothermia (brain cooling, as well as proposed, but as yet untested, pharmacologic therapies. Finally, cell-based therapies, including liver transplantation, infusion of fresh or cryopreserved hepatocytes, use of stem cells, and new approaches to gene

  17. Physiological and Transcriptomic Aspects of Urea Uptake and Assimilation in Arabidopsis Plants1[W

    Science.gov (United States)

    Mérigout, Patricia; Lelandais, Maud; Bitton, Frédérique; Renou, Jean-Pierre; Briand, Xavier; Meyer, Christian; Daniel-Vedele, Françoise

    2008-01-01

    Urea is the major nitrogen (N) form supplied as fertilizer in agriculture, but it is also an important N metabolite in plants. Urea transport and assimilation were investigated in Arabidopsis (Arabidopsis thaliana). Uptake studies using 15N-labeled urea demonstrated the capacity of Arabidopsis to absorb urea and that the urea uptake was regulated by the initial N status of the plants. Urea uptake was stimulated by urea but was reduced by the presence of ammonium nitrate in the growth medium. N deficiency in plants did not affect urea uptake. Urea exerted a repressive effect on nitrate influx, whereas urea enhanced ammonium uptake. The use of [15N]urea and [15N]ammonium tracers allowed us to show that urea and ammonium assimilation pathways were similar. Finally, urea uptake was less efficient than nitrate uptake, and urea grown-plants presented signs of N starvation. We also report the first analysis, to our knowledge, of Arabidopsis gene expression profiling in response to urea. Our transcriptomic approach revealed that nitrate and ammonium transporters were transcriptionally regulated by urea as well as key enzymes of the glutamine synthetase-glutamate synthase pathway. AtDUR3, a high-affinity urea transporter in Arabidopsis, was strongly up-regulated by urea. Moreover, our transcriptomic data suggest that other genes are also involved in urea influx. PMID:18508958

  18. Physiological and transcriptomic aspects of urea uptake and assimilation in Arabidopsis plants.

    Science.gov (United States)

    Mérigout, Patricia; Lelandais, Maud; Bitton, Frédérique; Renou, Jean-Pierre; Briand, Xavier; Meyer, Christian; Daniel-Vedele, Françoise

    2008-07-01

    Urea is the major nitrogen (N) form supplied as fertilizer in agriculture, but it is also an important N metabolite in plants. Urea transport and assimilation were investigated in Arabidopsis (Arabidopsis thaliana). Uptake studies using (15)N-labeled urea demonstrated the capacity of Arabidopsis to absorb urea and that the urea uptake was regulated by the initial N status of the plants. Urea uptake was stimulated by urea but was reduced by the presence of ammonium nitrate in the growth medium. N deficiency in plants did not affect urea uptake. Urea exerted a repressive effect on nitrate influx, whereas urea enhanced ammonium uptake. The use of [(15)N]urea and [(15)N]ammonium tracers allowed us to show that urea and ammonium assimilation pathways were similar. Finally, urea uptake was less efficient than nitrate uptake, and urea grown-plants presented signs of N starvation. We also report the first analysis, to our knowledge, of Arabidopsis gene expression profiling in response to urea. Our transcriptomic approach revealed that nitrate and ammonium transporters were transcriptionally regulated by urea as well as key enzymes of the glutamine synthetase-glutamate synthase pathway. AtDUR3, a high-affinity urea transporter in Arabidopsis, was strongly up-regulated by urea. Moreover, our transcriptomic data suggest that other genes are also involved in urea influx.

  19. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    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...... and 9 are found together with Rh proteins in cells exposed to portal blood coming from the intestine. In the kidney, AQP3 might participate in the excretion of NH(4) (+) in the collecting duct. The interplay between the ammonia-permeable aquaporins and the other types of ammonia- and urea...

  20. Ontogeny of rabbit proximal tubule urea permeability

    Science.gov (United States)

    QUIGLEY, RAYMOND; LISEC, AMBER; BAUM, MICHEL

    2014-01-01

    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). The activation energy for PCT Purea was not different between the neonatal and adult groups. BLMV Purea was determined by measuring vesicle shrinkage, due to efflux of urea, using a stop-flow instrument. Neonatal BLMV Purea was not different from adult BLMV Purea at 37°C [1.14 ± 0.05 × 10−6 vs. 1.25 ± 0.05 × 10−6 cm/s; P = not significant (NS)] or 25°C (0.94 ± 0.06 vs. 1.05 ± 0.10 × 10−6 cm/s; P = NS). There was no effect of 250 μM phloretin, an inhibitor of the urea transporter, on Purea in either adult or neonatal BLMV. The activation energy for urea diffusion was also identical in the neonatal and adult BLMV. These findings in the BLMV are in contrast to the brush-border membrane vesicles (BBMV) where we have previously demonstrated that urea transport is lower in the neonate than the adult. Urea transport is lower in the neonatal proximal tubule than the adult. This is due to a lower rate of apical membrane urea transport, whereas basolateral urea transport is the same in neonates and adults. The lower Purea in neonatal proximal tubules may play a role in overall urea excretion and in developing and maintaining a high medullary urea concentration and thus in the ability to concentrate the urine during renal maturation. PMID:11353675

  1. Urea in Milk

    OpenAIRE

    Projectsatbangalore

    2017-01-01

    This paper describes the design of a low-cost, portable instrument using CO2 and NH3 gas sensor technology to quantify and differentiate milk samples containing excess urea. Milk containing urea, in presence of urease enzyme hydrolyses urea to form ammonia and carbon dioxide.

  2. Kinetika Reaksi Polimerisasi Urea-Asetaldehid dalam Proses Enkapsulasi Urea

    OpenAIRE

    Purnamasari, Indah; Rochmadi,; Sulistyo, Hary

    2014-01-01

    Untuk meningkatkan efektivitas penggunaan urea dan mengurangi pencemaran lingkungan, perlu dilakukan enkapsulasi urea sehingga pelepasan urea dalam air dapat dikontrol. Dinding kapsul terbentuk langsung di permukaan partikel urea yang disebut in situ polimerisasi. Penelitian ini bertujuan untuk mempelajari kinetika reaksi polimerisasi urea dan asetaldehid dalam proses enkapsulasi urea. Urea dan asetaldehid dengan perbandingan 1:1,2 mol/mol dimasukkan ke dalam erlenmeyer yang dilengkapi ...

  3. Hydration of urea and alkylated urea derivatives.

    Science.gov (United States)

    Kaatze, Udo

    2018-01-07

    Compressibility data and broadband dielectric spectra of aqueous solutions of urea and some of its alkylated derivatives have been evaluated to yield their numbers Nh of hydration water molecules per molecule of solute. Nh values in a broad range of solute concentrations are discussed and are compared to hydration numbers of other relevant molecules and organic ions. Consistent with previous results, it is found that urea differs from other solutes in its unusually small hydration number, corresponding to just one third of the estimated number of nearest neighbor molecules. This remarkable hydration behavior is explained by the large density φH of hydrogen bonding abilities offered by the urea molecule. In terms of currently discussed models of reorientational motions and allied dynamics in water and related associating liquids, the large density φH causes a relaxation time close to that of undisturbed water with most parts of water encircling the solute. Therefore only a small part of disturbed ("hydration") water is left around each urea molecule. Adding alkyl groups to the basic molecule leads to Nh values which, within the series of n-alkylurea derivatives, progressively increase with the number of methyl groups per solute. With n-butylurea, Nh from dielectric spectra, in conformity with many other organic solutes, slightly exceeds the number of nearest neighbors. Compared to such Nh values, hydration numbers from compressibility data are substantially smaller, disclosing incorrect assumptions in the formula commonly used to interpret the experimental compressibilities. Similar to other series of organic solutes, effects of isomerization have been found with alkylated urea derivatives, indicating that factors other than the predominating density φH of hydrogen bond abilities contribute also to the hydration properties.

  4. Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion

    OpenAIRE

    Weiner, I. David; Mitch, William E.; Sands, Jeff M.

    2014-01-01

    Renal nitrogen metabolism primarily involves urea and ammonia metabolism, and is essential to normal health. Urea is the largest circulating pool of nitrogen, excluding nitrogen in circulating proteins, and its production changes in parallel to the degradation of dietary and endogenous proteins. In addition to serving as a way to excrete nitrogen, urea transport, mediated through specific urea transport proteins, mediates a central role in the urine concentrating mechanism. Renal ammonia excr...

  5. Urea nitrogen urine test

    Science.gov (United States)

    ... levels usually indicate: Increased protein breakdown in the body Too much protein intake Risks There are no risks with this test. Alternative Names Urine urea nitrogen Images Female urinary tract Male urinary tract References Agarwal R. Approach to the ...

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

    Science.gov (United States)

    Røjen, B A; Theil, P K; Kristensen, N B

    2011-05-01

    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, 4.1g 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 increase when urea infusion was decreased. Arterial urea-N extraction across the portal-drained viscera and rumen wall increased linearly with decreasing urea infusion (2.46, 3.65, and 4.32 ± 0.31% and 7.5, 11.5, and 16.9 ± 0.9%, respectively), indicating that cows responded to the changes in N supply. The relative urea-N extraction across the ruminal wall increased compared with the total portal-drained viscera extraction. We observed a postprandial decrease in ruminal extraction of arterial urea-N that might reflect that the activity of the protein, presumably facilitating urea-N transport, is regulated by ruminal ammonia. The urea-N clearance by the kidneys decreased (35, 30, and 25 ± 2L/h) and the urea-N reabsorbed by the kidney increased (42, 51 and 56 ± 3%) with decreasing urea infusion, indicating that the kidneys salvaged urea-N with low-N supply. The urea transporter B mRNA abundance in rumen papillae (papillae harvested at sampling days) was not affected by dietary N supply. The study showed, that rumen wall extraction of arterial urea-N is subjected to both long- and

  7. [Introduction neurodermatitis and urea].

    Science.gov (United States)

    Wohlrab, W

    1992-01-01

    Neurodermatitis is a multiphasic disease, yet despite intensive research, its etiopathogenesis still remains unclear. A large number of immunological and nonimmunological dysfunctions as well as their diverse interplay lead to very different types of manifestation. Consequently, treatment must also be varied and is mainly determined by the clinical picture. External therapy without glucocorticoids is no longer conceivable in acute and subacute dermatological conditions, although attenuated glucocorticoids which have the least amount of side effects should always be used. Improvement in the therapeutic efficacy of hydrocortisone can be achieved by combining it with urea which, depending on the vehicle used, represents one of the most effective penetration promoters for this glucocorticoid. Fighting the symptoms of dry skin and itching are of central importance in the follow-up treatment and prophylaxis of neurodermatitis. Here, urea preparations have been applied with great success. Urea's efficacy in the skin is largely based on its ability to elevate the water-binding capacity of the corneal layer, on its keratoplastic properties, its antipruriginous effect and its proliferation-suppressant action. However, the intensity and the duration of this therapeutic efficacy are dependent on several factors which must be taken into consideration in the galenics of urea preparations. As a whole, there is a multitude of possibilities for the use of urea in the therapy, follow-up and prophylaxis of neurodermatitis which we have only just begun to exploit in full.

  8. Evolutionary aspects of urea utilization by fungi.

    Science.gov (United States)

    Navarathna, Dhammika H M L P; Harris, Steven D; Roberts, David D; Nickerson, Kenneth W

    2010-03-01

    The higher fungi exhibit a dichotomy with regard to urea utilization. The hemiascomycetes use urea amidolyase (DUR1,2), whereas all other higher fungi use the nickel-containing urease. Urea amidolyase is an energy-dependent biotin-containing enzyme. It likely arose before the Euascomycete/Hemiascomycete divergence c. 350 million years ago by insertion of an unknown gene into one copy of a duplicated methylcrotonyl CoA carboxylase (MccA). The dichotomy between urease and urea amidolyase coincides precisely with that for the Ni/Co transporter (Nic1p), which is present in the higher fungi that use urease and is absent in those that do not. We suggest that the selective advantage for urea amidolyase is that it allowed the hemiascomycetes to jettison all Ni(2+)- and Co(2+)-dependent metabolisms and thus to have two fewer transition metals whose concentrations need to be regulated. Also, the absence of MccA in the hemiascomycetes coincides with and may explain their production of fusel alcohols.

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

    Directory of Open Access Journals (Sweden)

    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

  10. Urea based fuel cells and electrocatalysts for urea oxidation

    OpenAIRE

    Xu, Weijun; Wu, Zucheng; Tao, Shanwen

    2016-01-01

    Urea is a new member of hydrogen-storage materials for low-temperature fuel cells. It avoids issues of toxicity and safety compared to ammonia and hydrazine. The main limitation of urea fuel cells is the relative low power density due to the sluggish anode reaction. Rapid advances in nano-catalysts for urea electrooxidation have been achieved in order to lower overpotential and improve activity. Urine, as a natural resource of urea, is also an environmental pollutant. Most technologies of tre...

  11. Living with urea stress

    Indian Academy of Sciences (India)

    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 ...

  12. National Urea Cycle Disorders Foundation

    Science.gov (United States)

    ... INGESTING HIGH-PROTEIN FOODS AND PROTEIN SUPPLEMENTS FOR BODYBUILDING : Symptoms of urea cycle disorder went unrecognized as young mother, Meegan Hefford, prepared for a bodybuilding competition. Undiagnosed urea cycle disorders can be triggered ...

  13. Urea uptake enhances barrier function and antimicrobial defense in humans by regulating epidermal gene expression

    Science.gov (United States)

    Grether-Beck, Susanne; Felsner, Ingo; Brenden, Heidi; Kohne, Zippora; Majora, Marc; Marini, Alessandra; Jaenicke, Thomas; Rodriguez-Martin, Marina; Trullas, Carles; Hupe, Melanie; Elias, Peter M.; Krutmann, Jean

    2012-01-01

    Urea is an endogenous metabolite, known to enhance stratum corneum hydration. Yet, topical urea anecdotally also improves permeability barrier function, and it appears to exhibit antimicrobial activity. Hence, we hypothesized that urea is not merely a passive metabolite, but a small-molecule regulator of epidermal structure and function. In 21 human volunteers, topical urea improved barrier function in parallel with enhanced antimicrobial peptide (LL-37 and β-defensin-2) expression. Urea both stimulates expression of, and is transported into keratinocytes by two urea transporters, UT-A1 and UT-A2, and by aquaporin 3, 7 and 9. Inhibitors of these urea transporters block the downstream biological effects of urea, which include increased mRNA and protein levels for: (i) transglutaminase-1, involucrin, loricrin and filaggrin; (ii) epidermal lipid synthetic enzymes, and (iii) cathelicidin/LL-37 and β-defensin-2. Finally, we explored the potential clinical utility of urea, showing that topical urea applications normalized both barrier function and antimicrobial peptide expression in a murine model of atopic dermatitis (AD). Together, these results show that urea is a small-molecule regulator of epidermal permeability barrier function and antimicrobial peptide expression after transporter uptake, followed by gene regulatory activity in normal epidermis, with potential therapeutic applications in diseased skin. PMID:22418868

  14. Utilization of urea and expression profiles of related genes in the dinoflagellate Prorocentrum donghaiense.

    Science.gov (United States)

    Jing, Xiaoli; Lin, Senjie; Zhang, Huan; Koerting, Claudia; Yu, Zhigang

    2017-01-01

    Urea has been shown to contribute more than half of total nitrogen (N) required by phytoplankton in some estuaries and coastal waters and to provide a substantial portion of the N demand for many harmful algal blooms (HABs) of dinoflagellates. In this study, we investigated the physiological and transcriptional responses in Prorocentrum donghaiense to changes in nitrate and urea availability. We found that this species could efficiently utilize urea as sole N source and achieve comparable growth rate and photosynthesis capability as it did under nitrate. These physiological parameters were markedly lower in cultures grown under nitrate- or urea-limited conditions. P. donghaiense N content was similarly low under nitrate- or urea-limited culture condition, but was markedly higher under urea-replete condition than under nitrate-replete condition. Carbon (C) content was consistently elevated under N-limited condition. Consequently, the C:N ratio was as high as 21:1 under nitrate- or urea-limitation, but 7:1 under urea-replete condition and 9:1 to 10:1 under nitrate-replete condition. Using quantitative reverse transcription PCR, we investigated the expression pattern for four genes involved in N transport and assimilation. The results indicated that genes encoding nitrate transport, urea hydrolysis, and nickel transporter gene were sensitive to changes in general N nutrient availability whereas the urea transporter gene responded much more strongly to changes in urea concentration. Taken together, our study shows the high bioavailability of urea, its impact on C:N stoichiometry, and the sensitivity of urea transporter gene expression to urea availability.

  15. Hydrogen bonding of formamide, urea, urea monoxide and their thio ...

    Indian Academy of Sciences (India)

    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 ...

  16. Hydrogen bonding of formamide, urea, urea monoxide and their thio ...

    Indian Academy of Sciences (India)

    Abstract. Ab initio and DFT methods have been employed to study the hydrogen bonding ability of for- mamide, urea, urea monoxide, thioformamide, thiourea and thiourea monoxide with one water molecule and the homodimers of the selected molecules. The stabilization energies associated with the monohydrated ...

  17. High and Low Affinity Urea Root Uptake: Involvement of NIP5;1.

    Science.gov (United States)

    Yang, Huayiu; Menz, Jochen; Häussermann, Iris; Benz, Martin; Fujiwara, Toru; Ludewig, Uwe

    2015-08-01

    Urea is the most widespread nitrogen (N) fertilizer worldwide and is rapidly degraded in soil to ammonium by urease. Ammonium is either taken up by plant roots or is further processed to nitrate by soil microorganisms. However, urea can be taken up by roots and is further degraded to ammonium by plant urease for assimilation. When urea is supplied under sterile conditions, it acts as a poor N source for seedlings or adult Arabidopsis thaliana plants. Here, the gene expression of young seedlings exposed to urea and ammonium nitrate nutrition was compared. Several primary metabolism and transport genes, including those for nitrate and urea, were differentially expressed in seedlings. However, urease and most major intrinsic proteins were not differentially expressed, with the exception of NIP6;1, a urea-permeable channel, which was repressed. Furthermore, little overlap with the gene expression with ammonium as the sole N source was observed, confirming that pure urea nutrition is not associated with the ammonium toxicity syndrome in seedlings. The direct root uptake of urea was increased under boron deficiency, in both the high and low affinity range. This activity was entirely mediated by the NIP5;1 channel, which was confirmed to transport urea when expressed in oocytes. The uptake of urea in the high and low affinity range was also determined for maize and wheat roots. The urea uptake by maize roots was only about half that of wheat, but was not stimulated by boron deficiency or N deficiency in either species. This analysis identifies novel components of the urea uptake systems in plants, which may become agronomically relevant to urea uptake and utilization, as stabilized urea fertilizers become increasingly popular. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

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

    National Research Council Canada - National Science Library

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

    2016-01-01

    .... 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...

  19. Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion.

    Science.gov (United States)

    Weiner, I David; Mitch, William E; Sands, Jeff M

    2015-08-07

    Renal nitrogen metabolism primarily involves urea and ammonia metabolism, and is essential to normal health. Urea is the largest circulating pool of nitrogen, excluding nitrogen in circulating proteins, and its production changes in parallel to the degradation of dietary and endogenous proteins. In addition to serving as a way to excrete nitrogen, urea transport, mediated through specific urea transport proteins, mediates a central role in the urine concentrating mechanism. Renal ammonia excretion, although often considered only in the context of acid-base homeostasis, accounts for approximately 10% of total renal nitrogen excretion under basal conditions, but can increase substantially in a variety of clinical conditions. Because renal ammonia metabolism requires intrarenal ammoniagenesis from glutamine, changes in factors regulating renal ammonia metabolism can have important effects on glutamine in addition to nitrogen balance. This review covers aspects of protein metabolism and the control of the two major molecules involved in renal nitrogen excretion: urea and ammonia. Both urea and ammonia transport can be altered by glucocorticoids and hypokalemia, two conditions that also affect protein metabolism. Clinical conditions associated with altered urine concentrating ability or water homeostasis can result in changes in urea excretion and urea transporters. Clinical conditions associated with altered ammonia excretion can have important effects on nitrogen balance. Copyright © 2015 by the American Society of Nephrology.

  20. Evaporation of urea at atmospheric pressure.

    Science.gov (United States)

    Bernhard, Andreas M; Czekaj, Izabela; Elsener, Martin; Wokaun, Alexander; Kröcher, Oliver

    2011-03-31

    Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems.

  1. 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.

    Science.gov (United States)

    Røjen, B A; Kristensen, N B

    2012-03-01

    not used by the cow to increase the uptake of urea-N across the PDV). Arterial urea-N extraction across the PDV was increased with water INF especially from 0.5 to 3.5h postprandial relative to the urea infusion treatments, reflecting increased epithelial permeability for urea-N. This indicates that daily ruminal peak of ammonia or blood urea-N concentrations overruled potential signals from low ruminal ammonia concentration observed during the sampling window. In conclusion, dairy cows appear unable to increase transport of urea-N from blood to gut in periods with low ruminal ammonia concentrations, even in a situation with infrequent N supply and apparent carryover effects on blood urea-N. It is speculated that mechanisms responsible for downregulation of epithelial urea-N transport based on daily maximum concentrations of ammonia in the rumen or urea-N in the blood suppresses any short-term signal from low ruminal ammonia during periods with low ruminal N supply. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  2. Effects of supplemental energy and protein on forage digestion and urea kinetics in growing beef cattle.

    Science.gov (United States)

    Bailey, E A; Titgemeyer, E C; Olson, K C; Brake, D W; Jones, M L; Anderson, D E

    2012-10-01

    Effects of supplemental energy sources on nutrient digestion and urea kinetics at 2 levels of degradable intake protein were evaluated in cattle (Bos taurus). Six ruminally and duodenally cannulated steers (208 ± 17 kg) were used in a 6 × 6 Latin square with treatments arranged as a 3 × 2 factorial. Energy treatments included a control, 600 g glucose dosed ruminally once daily, and 480 g VFA infused ruminally over 8 h daily. Casein (120 or 240 g) was dosed ruminally once daily. Steers had ad libitum access to prairie hay (5.8% CP). Jugular infusion of (15)N(15)N-urea with measurement of enrichment in urine was used to measure urea kinetics. Infusing VFA decreased (P energy decreased (P = 0.03) plasma urea-N concentration, but casein level did not affect it (P = 0.16). Microbial N flow was greater (P energy (P = 0.23). Urea-N entry rate and gut entry of urea-N were not affected (P ≥ 0.12) by supplemental energy or casein, but the proportion of urea production that was recycled to the gut was less (P = 0.01) when 240 g/d rather than 120 g/d casein was provided. Compared with VFA, glucose tended (P = 0.07) to increase the proportion of urea-N entry rate that was recycled to the gut. Supplementation with glucose led to more (P = 0.01) microbial uptake of recycled urea than did supplementation with VFA. Urea recycling did not differ greatly among treatments despite impacts on ruminal pH and NH(3) and on plasma urea-N that were expected to alter urea transport across ruminal epithelium. Lack of treatment effects on urea production indicate that the complete diets did not provide excessive amounts of N and that increases of intestinally available AA were used efficiently by cattle for protein deposition.

  3. Cold recycle pavement using urea urethane dispersion agent and rubber : final report.

    Science.gov (United States)

    1994-12-01

    This research study was a joint venture of the Oregon Department of Transportation (ODOT), Evans, Loosely, Inc., and Roseburg Paving Company, to evaluate the use of Urea Urethane Dispersion (UUD) agent, with finely ground tire rubber, high float emul...

  4. Notas acerca de la Urea

    OpenAIRE

    Velásquez, Manuel A.; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú

    2014-01-01

    La urea, peso molecular = 60, es considerada en justicia como el producto principal del metabolismo de las proteínas y como el más interesante de los constituyentes nitrogenados de la orina y como el más importante también, pues contiene un 45%de azoe y toma para ella el 85 a 90% del nitrógeno total de la orina. Contribuye a afirmar este concepto de la importancia de la urea, el hecho de que casi el 90% del nitrógeno introducido en la economía con los alimentos es eliminado por la orina bajo ...

  5. comparative studies on the mineralization of furfural urea and urea ...

    African Journals Online (AJOL)

    DR. AMINU

    2013-12-02

    Dec 2, 2013 ... slow release N fertilizer in an alfisol of Nigeria Savanna in the year 2009/2010 season. Incubation studies revealed that ... mineralization of both fertilizers differ, the first, and the third to the fourth week should be synchronized with demand in ..... Coated urea, thiourea, ureaformaldehyde, hexamine, oxamide ...

  6. The effect of supplementing untreated, urea-supplemented and urea ...

    African Journals Online (AJOL)

    ammoniated wheat-straw with maize-meal and/or .... experiment, in order to investigate the effects of straw treatment (untreated, supplemented with 2% urea or ..... High levels of soy bean meal and maize gluten meal were, however, found to suppress the ...

  7. Effect of dietary nitrogen content and intravenous urea infusion on ruminal and portal-drained visceral extraction of arterial urea in lactating Holstein cows

    DEFF Research Database (Denmark)

    Kristensen, Niels Bastian; Storm, Adam Christian; Larsen, Mogens

    2010-01-01

    concentration (1.91 ± 0.13 mmol/L). Arterial urea extraction across the PDV and rumen increased from 2.7 to 5.4 ± 0.5% and from 7.1 to 23.8 ± 2.1% when cows were changed from high-N to low-N, respectively. Urea infusion did not decrease urea extractions, implying that urea transport rates were proportional......) concentration difference for ammonia increased instantly (first sampling 15 min after initiation of infusion) to the primed intravenous infusion when cows were adapted to the low-N diet. The RA difference for ammonia correlated poorly to the ventral ruminal concentration of ammonia (r = 0.55). Relating the RA...... transport across gut epithelia in cattle is adapting to N status and driven by mass action. Data are commensurable with a model for urea transport across gut epithelia based on regulated expression or activity of facilitative urea transporters....

  8. Maturational Changes in Rabbit Renal Brush Border Membrane Vesicle Urea Permeability

    Science.gov (United States)

    Quigley, Raymond; Flynn, Marisa; Baum, Michel

    2014-01-01

    Urea transport in the proximal tubule is thought to occur by passive diffusion through the lipid bilayers of the cell membranes. The lipid composition of cell membranes changes during maturation and may directly affect urea permeability of proximal tubule membranes. The present study examined the maturation of urea transport in rabbit renal brush border membrane vesicles (BBMV). BBMV from adult and neonatal (9- to 11-d-old) New Zealand white rabbits were loaded with 500 mM urea and mixed with an iso-osmotic mannitol solution using a stop-flow instrument. Vesicle shrinkage, due to efflux of urea, was followed with light scattering and urea permeability was calculated from an exponential fit of the data. Urea permeability was significantly lower in the neonatal BBMV than the adult at 25°C (0.34 ± 0.04 × 10−6 versus 0.56 ± 0.03 × 10−6 cm/sec; p excretion. This may also play a role in developing and maintaining a high medullary urea concentration and thus the ability to concentrate the urine during renal maturation. PMID:9890623

  9. Physiological and molecular ontogeny of branchial and extra-branchial urea excretion in posthatch rainbow trout (Oncorhynchus mykiss)

    Science.gov (United States)

    Wood, Chris M.

    2015-01-01

    All teleost fish produce ammonia as a metabolic waste product. In embryos, ammonia excretion is limited by the chorion, and fish must detoxify ammonia by synthesizing urea via the ornithine urea cycle (OUC). Although urea is produced by embryos and larvae, urea excretion (Jurea) is typically low until yolk sac absorption, increasing thereafter. The aim of this study was to determine the physiological and molecular characteristics of Jurea by posthatch rainbow trout (Oncorhynchus mykiss). Following hatch, whole body urea concentration decreased over time, while Jurea increased following yolk sac absorption. From 12 to 40 days posthatch (dph), extra-branchial routes of excretion accounted for the majority of Jurea, while the gills became the dominant site for Jurea only after 55 dph. This represents the most delayed branchial ontogeny of any process studied to date. Urea transporter (UT) gene expression in the gills and skin increased over development, consistent with increases in branchial and extra-branchial Jurea. Following exposure to 25 mmol/l urea, the accumulation and subsequent elimination of exogenous urea was much greater at 55 dph than 12 dph, consistent with increased UT expression. Notably, UT gene expression in the gills of 55 dph larvae increased in response to high urea. In summary, there is a clear increase in urea transport capacity over posthatch development, despite a decrease in OUC activity. PMID:26608657

  10. 40 CFR 721.9928 - Urea, tetraethyl-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Urea, tetraethyl-. 721.9928 Section... Substances § 721.9928 Urea, tetraethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as urea, tetraethyl- (PMN P-94-1017; CAS No. 1187-03-7) is...

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    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 data...... suggest that the permeability depends on the conformational equilibrium of the EAAT1. At positive potentials and in the presence of Na(+) and glutamate, the pore is enlarged and water and urea penetrate more readily. The L(p) was larger when measured with urea or glycerol as osmolytes as compared...... with mannitol. Apparently, the properties of the pore are not uniform along its length. The outer section may accommodate urea and glycerol in an osmotically active form, giving rise to larger water fluxes. The physiological role of EAAT1 for water homeostasis in the central nervous system is discussed....

  12. Urea Output by L3 Teladorsagia circumcincta and some Properties of Two Urea Producing Enzymes

    OpenAIRE

    N. Muhamad; LR Walker; DC Simcock; KC Pedley; HV Simpson; Brown, S

    2013-01-01

    Background: Like several other parasites, Teladorsagia circumcincta secretes or excretes urea, but nei­ther the rate of efflux nor the possible metabolic sources of the urea has been considered.Methods: Parasites were maintained by passage through sheep. Urea efflux was measured using phe­nol/hypochlorite after treatment with urea aminohydrolase. The kinetics of creatine amidinohy­drolase and arginine amidinohydrolase were characterised by coupling the reactions with urea aminohy­drolase and ...

  13. Urea biosensor for hemodialysis monitoring

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Urea biosensor for hemodialysis monitoring

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. Urea-Triazone N Characteristics and Uses

    Directory of Open Access Journals (Sweden)

    John G. Clapp

    2001-01-01

    Full Text Available Urea-triazone nitrogen (N is a stable solution resulting from a controlled reaction in aqueous medium of urea, formaldehyde, and ammonia which contains at least 25% total N. This N source contains no more than 40%, nor less than 5%, of total N from unreacted urea and not less that 40% from triazone. All other N shall be derived from water-soluble dissolved reaction products of the above reactants. It is a source of slowly available N. The rate of mineralization of urea-triazone is about 66% that of urea after 8 days when incorporated in a Munjor sandy loam. Ammonia volatilization losses of N applied as urea-triazone were about 41% of those from urea on a Cecil sandy loam in the first week after application. N leaching losses through saturated Yolo loam columns of urea-triazone were about two thirds that of urea or nitrate N. This N source has proven to be a safer and more effective material for direct application on plant foliage. Tomato growth was enhanced with foliar application of urea-triazone relative to that obtained from ammonium nitrate or urea. The stability of this N source from potential losses via ammonia volatilization and nitrate leaching when soil applied is also documented by results from university trials.

  16. Understanding strategy of nitrate and urea assimilation in a Chinese strain of Aureococcus anophagefferens through RNA-seq analysis.

    Science.gov (United States)

    Dong, Hong-Po; Huang, Kai-Xuan; Wang, Hua-Long; Lu, Song-Hui; Cen, Jing-Yi; Dong, Yue-Lei

    2014-01-01

    Aureococcus anophagefferens is a harmful alga that dominates plankton communities during brown tides in North America, Africa, and Asia. Here, RNA-seq technology was used to profile the transcriptome of a Chinese strain of A. anophagefferens that was grown on urea, nitrate, and a mixture of urea and nitrate, and that was under N-replete, limited and recovery conditions to understand the molecular mechanisms that underlie nitrate and urea utilization. The number of differentially expressed genes between urea-grown and mixture N-grown cells were much less than those between urea-grown and nitrate-grown cells. Compared with nitrate-grown cells, mixture N-grown cells contained much lower levels of transcripts encoding proteins that are involved in nitrate transport and assimilation. Together with profiles of nutrient changes in media, these results suggest that A. anophagefferens primarily feeds on urea instead of nitrate when urea and nitrate co-exist. Furthermore, we noted that transcripts upregulated by nitrate and N-limitation included those encoding proteins involved in amino acid and nucleotide transport, degradation of amides and cyanates, and nitrate assimilation pathway. The data suggest that A. anophagefferens possesses an ability to utilize a variety of dissolved organic nitrogen. Moreover, transcripts for synthesis of proteins, glutamate-derived amino acids, spermines and sterols were upregulated by urea. Transcripts encoding key enzymes that are involved in the ornithine-urea and TCA cycles were differentially regulated by urea and nitrogen concentration, which suggests that the OUC may be linked to the TCA cycle and involved in reallocation of intracellular carbon and nitrogen. These genes regulated by urea may be crucial for the rapid proliferation of A. anophagefferens when urea is provided as the N source.

  17. Understanding Strategy of Nitrate and Urea Assimilation in a Chinese Strain of Aureococcus anophagefferens through RNA-Seq Analysis

    Science.gov (United States)

    Dong, Hong-Po; Huang, Kai-Xuan; Wang, Hua-Long; Lu, Song-Hui; Cen, Jing-Yi; Dong, Yue-Lei

    2014-01-01

    Aureococcus anophagefferens is a harmful alga that dominates plankton communities during brown tides in North America, Africa, and Asia. Here, RNA-seq technology was used to profile the transcriptome of a Chinese strain of A. anophagefferens that was grown on urea, nitrate, and a mixture of urea and nitrate, and that was under N-replete, limited and recovery conditions to understand the molecular mechanisms that underlie nitrate and urea utilization. The number of differentially expressed genes between urea-grown and mixture N-grown cells were much less than those between urea-grown and nitrate-grown cells. Compared with nitrate-grown cells, mixture N-grown cells contained much lower levels of transcripts encoding proteins that are involved in nitrate transport and assimilation. Together with profiles of nutrient changes in media, these results suggest that A. anophagefferens primarily feeds on urea instead of nitrate when urea and nitrate co-exist. Furthermore, we noted that transcripts upregulated by nitrate and N-limitation included those encoding proteins involved in amino acid and nucleotide transport, degradation of amides and cyanates, and nitrate assimilation pathway. The data suggest that A. anophagefferens possesses an ability to utilize a variety of dissolved organic nitrogen. Moreover, transcripts for synthesis of proteins, glutamate-derived amino acids, spermines and sterols were upregulated by urea. Transcripts encoding key enzymes that are involved in the ornithine-urea and TCA cycles were differentially regulated by urea and nitrogen concentration, which suggests that the OUC may be linked to the TCA cycle and involved in reallocation of intracellular carbon and nitrogen. These genes regulated by urea may be crucial for the rapid proliferation of A. anophagefferens when urea is provided as the N source. PMID:25338000

  18. The Urease Inhibitor NBPT Negatively Affects DUR3-mediated Uptake and Assimilation of Urea in Maize Roots.

    Science.gov (United States)

    Zanin, Laura; Tomasi, Nicola; Zamboni, Anita; Varanini, Zeno; Pinton, Roberto

    2015-01-01

    Despite the widespread use of urease inhibitors in agriculture, little information is available on their effect on nitrogen (N) uptake and assimilation. Aim of this work was to study, at physiological and transcriptional level, the effects of N-(n-butyl) thiophosphoric triamide (NBPT) on urea nutrition in hydroponically grown maize plants. Presence of NBPT in the nutrient solution limited the capacity of plants to utilize urea as a N-source; this was shown by a decrease in urea uptake rate and (15)N accumulation. Noteworthy, these negative effects were evident only when plants were fed with urea, as NBPT did not alter (15)N accumulation in nitrate-fed plants. NBPT also impaired the growth of Arabidopsis plants when urea was used as N-source, while having no effect on plants grown with nitrate or ammonium. This response was related, at least in part, to a direct effect of NBPT on the high affinity urea transport system. Impact of NBPT on urea uptake was further evaluated using lines of Arabidopsis overexpressing ZmDUR3 and dur3-knockout; results suggest that not only transport but also urea assimilation could be compromised by the inhibitor. This hypothesis was reinforced by an over-accumulation of urea and a decrease in ammonium concentration in NBPT-treated plants. Furthermore, transcriptional analyses showed that in maize roots NBPT treatment severely impaired the expression of genes involved in the cytosolic pathway of ureic-N assimilation and ammonium transport. NBPT also limited the expression of a gene coding for a transcription factor highly induced by urea and possibly playing a crucial role in the regulation of its acquisition. This work provides evidence that NBPT can heavily interfere with urea nutrition in maize plants, limiting influx as well as the following assimilation pathway.

  19. Urea synthesis in patients with chronic pancreatitis

    DEFF Research Database (Denmark)

    Hamberg, Ole; Andersen, Vibeke; Sonne, J

    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)....

  20. Urea-Triazone N Characteristics and Uses

    OpenAIRE

    John G. Clapp

    2001-01-01

    Urea-triazone nitrogen (N) is a stable solution resulting from a controlled reaction in aqueous medium of urea, formaldehyde, and ammonia which contains at least 25% total N. This N source contains no more than 40%, nor less than 5%, of total N from unreacted urea and not less that 40% from triazone. All other N shall be derived from water-soluble dissolved reaction products of the above reactants. It is a source of slowly available N. The rate of mineralization of urea-triazone is about 66% ...

  1. A field evaluation of coated urea with biodegradable materials and ...

    African Journals Online (AJOL)

    ajl yemi

    2011-12-28

    Dec 28, 2011 ... urea), UAGCu (agar + Cu + urea), UGCu (gelatine + Cu coated urea), UCu (Cu coated urea) and UCuZn (Cu + Zn coated urea), which were surface applied once at the start of the experiment after clearing previously grown grass and irrigating the plot site. The plot was never fertilized for the last five years.

  2. Experimental studies on urea degradation in seawater

    Digital Repository Service at National Institute of Oceanography (India)

    Rajendran, A.; Joseph, T.; Reddy, C.V.G.

    polluted waters, resulting in the accumulation of ammonia. The urea decomposing bacteria varied between 7 and 40% among the total heterotrophic bacteria in Velsao Bay, while these were from 15 to 22% near Mormugao. The rate for biological oxidation of urea...

  3. 21 CFR 184.1923 - Urea.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea. 184.1923 Section 184.1923 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS § 184.1923 Urea. (a)...

  4. The crystal structure of urea nitrate

    NARCIS (Netherlands)

    Harkema, Sybolt; Feil, D.

    1969-01-01

    The structure of urea nitrate has been solved, by the use of three-dimensional X-ray data. Data were collected using Cu Ke and Mo K0~ radiations. The structure consists of layers with urea and nitrate groups held together by hydrogen bonds. The positions of all hydrogen atoms were found. The final R

  5. 40 CFR 721.9892 - Alkylated urea.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721.9892 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9892 Alkylated urea. (a) Chemical substanc...

  6. [Urea formation in the after operational liver].

    Science.gov (United States)

    Savilov, P N

    2016-01-01

    The effect of resection of the left lobe of the liver (LR, 15-20% og the organ weight) on hepatic urea formation was investigated in 84 albino rats. The objects of study were the surgery left (LLP), inoperable middle (MLP) lobe of the liver, blood (aorta, v. hepatica, v. porta) and choledochal bile. They studied the urea content. Arginase activity was examined in liver homogenate. On the day 3 and day 7 after resection reduced arginase activity was detected. LR caused a decrease of urea in v. hepatica, but increased urea content in the arterial blood and v. porta. Increase in bile urea on day 7 it was replaced by a decrease observed on day 14 of the postsurgery period. The concentration of urea in the liver on the 3rd day after LR was below the norm, and on the 7th and 14th day was within it. The results indicate a violation of urea operated by hepatocytes of the liver and extrahepatic activation mechanisms of the formation of urea.

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

    Science.gov (United States)

    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.

  8. Urea in Weaver Ant Feces

    DEFF Research Database (Denmark)

    Vidkjaer, Nanna H.; Wollenweber, Bernd; Jensen, Karl-Martin V.

    2016-01-01

    Weaver ants are tropical insects that nest in tree canopies, and for centuries these ants have been used for pest control in tropical orchards. Trees hosting weaver ants might benefit not only from the pest protective properties of these insects but also an additional supply of nutrients from ant...... feces deposited on the leaves. In a recent study, we demonstrated that Coffea arabica plants hosting Oecophylla smaragdina weaver ants under laboratory conditions experienced enhanced nitrogen availability compared with plants grown without ants. Therefore, the aim of the present study was to further...... investigate the interactions of weaver ants with the host plants with respect to plant nutrition. Here, we report the identification and quantification of urea, a highly effective foliar nutrient present in the fecal depositions of O. smaragdina. Feces samples obtained from six O. smaragdina colonies were...

  9. Association between Blood Levels of Glucose and Urea and the ...

    African Journals Online (AJOL)

    osman

    2017-08-05

    Aug 5, 2017 ... Normal blood glucose and urea levels in dairy cows vary within breeds, countries .... For glucose, an enzymatic method (Trinder, 1969) using colorimetric ... To determine blood urea, urea in the serum samples was hydrolysed.

  10. BUN (Blood Urea Nitrogen): MedlinePlus Lab Test Information

    Science.gov (United States)

    ... https://medlineplus.gov/labtests/bunbloodureanitrogen.html BUN (Blood Urea Nitrogen) To use the sharing features on this ... please enable JavaScript. What is a BUN (Blood Urea Nitrogen) Test? A BUN, or blood urea nitrogen ...

  11. Transcriptomic analysis highlights reciprocal interactions of urea and nitrate for nitrogen acquisition by maize roots.

    Science.gov (United States)

    Zanin, Laura; Zamboni, Anita; Monte, Rossella; Tomasi, Nicola; Varanini, Zeno; Cesco, Stefano; Pinton, Roberto

    2015-03-01

    Even though urea and nitrate are the two major nitrogen (N) forms applied as fertilizers in agriculture and occur concomitantly in soils, the reciprocal influence of these two N sources on the mechanisms of their acquisition are poorly understood. Therefore, molecular and physiological aspects of urea and nitrate uptake were investigated in maize (Zea mays), a crop plant consuming high amounts of N. In roots, urea uptake was stimulated by the presence of urea in the external solution, indicating the presence of an inducible transport system. On the other hand, the presence of nitrate depressed the induction of urea uptake and, at the same time, the induction of nitrate uptake was depressed by the presence of urea. The expression of about 60,000 transcripts of maize in roots was monitored by microarray analyses and the transcriptional patterns of those genes involved in nitrogen acquisition were analyzed by real-time reverse transcription-PCR (RT-PCR). In comparison with the treatment without added N, the exposure of maize roots to urea modulated the expression of only very few genes, such as asparagine synthase. On the other hand, the concomitant presence of urea and nitrate enhanced the overexpression of genes involved in nitrate transport (NRT2) and assimilation (nitrate and nitrite reductase, glutamine synthetase 2), and a specific response of 41 transcripts was determined, including glutamine synthetase 1-5, glutamine oxoglutarate aminotransferase, shikimate kinase and arogenate dehydrogenase. Also based on the real-time RT-PCR analysis, the transcriptional modulation induced by both sources might determine an increase in N metabolism promoting a more efficient assimilation of the N that is taken up. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  12. Ammonia volatilization from coated urea forms

    Directory of Open Access Journals (Sweden)

    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.

  13. Transportation

    Science.gov (United States)

    2006-01-01

    container. It now permits free transit of shipping containers from their western ports, if transported by rail directly to the U.S. ( Mireles , 2005, p...Transportation Industry Study Seminar. Mireles , Richard, Castillo. (2005, January). A Cure for West Coast Congestion. Logistics Today, Vol. 46, Issue 1. 1

  14. Urea and deuterium mixtures at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, M., E-mail: m.donnelly-2@sms.ed.ac.uk; Husband, R. J.; Frantzana, A. D.; Loveday, J. S. [Centre for Science at Extreme Conditions and School of Physics and Astronomy, The University of Edinburgh, Erskine Williamson Building, Peter Guthrie Tait Road, The King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Bull, C. L. [ISIS, Rutherford Appleton Laboratory, Oxford Harwell, Didcot OX11 0QX (United Kingdom); Klotz, S. [IMPMC, CNRS UMR 7590, Université P and M Curie, 4 Place Jussieu, 75252 Paris (France)

    2015-03-28

    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 D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.

  15. [Diuretic activity of benzimidazole urea derivatives].

    Science.gov (United States)

    Pashinskiĭ, V G; Romanova, T V; Mukhina, N A; Shkrabova, L V; Tetenchuk, K P

    1978-01-01

    The chemical structure of benzimidazol urea derivatives and physico-chemical properties of these compounds conditioned by it play a significant role in the manifestation of the emictory effect. Among the study substances a number of compounds displaying a marked, but short-lived diuretic action have been educed. In the manifestation of emictory properties in benzimidazol urea derivatives of importance is the character of the side chain and its ramification and also an even number of carbon atoms in the acyl radical.

  16. 21 CFR 862.1770 - Urea nitrogen test system.

    Science.gov (United States)

    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 urine...

  17. [Various effects of prostaglandin E2 on reabsorption of water and urea in the amphibia osmosis-regulating epithelium].

    Science.gov (United States)

    Parnova, R G; Bakhteeva, V T; Lavrova, E A

    2001-12-01

    Principal similarities between molecular pathways providing the enhancement of water and urea reabsorption under the action of argininvasotocin (AVT) in amphibian urinary bladder suggest that prostaglandin E2 (PGE2) could be a negative regulator of urea transport. To analyse this hypothesis, the role of PGE2 in regulation of urea transport was studied in isolated frog (Rana temporaria L.) urinary bladder. The urea permeability (Pu) was determined from the rate of efflux of (14) Curea from mucosal to serosal solution in isoosmotic conditions. The water permeability was measured in separate experiments in presence of an osmotic gradient. In contrast to water permeability, we were unable to demonstrate any inhibitory effect of 10-1000 nM PGE2 on AVT-stimulated urea transport using a variety of protocols. It was found that basolateral PGE2 exposure (10 nM-1 microM) caused an increase in Pu with no effect on osmotic water flow. The PGE2 effect was markedly inhibited by phloretin, a specific inhibitor of urea transporter. Sulprostone, an EP1/EP3 prostaglandin E2 receptor agonist, had no effect on Pu suggesting the contribution of EP2/EP4 receptor subtypes. In presence of osmotic water flow, the AVT-induced urea transport was significantly higher. This water flow-dependent urea permeability was inhibited by PGE2 although the inhibitory effect was less pronounced in comparison to the action of PGE2 on osmotic water flow. On the basis of these results we can make a conclusion that PGE2 has different role in regulation of water and urea transport in the frog urinary bladder. PGE2 could be considered as a stimulator of urea transport and an inhibitor of osmotic water flow activated by the AVT. The ability of PGE2 to regulate various types of cAMP-dependent transport by different mechanisms seems to be based on the presence of multiple basolateral PGE2 receptor subtypes in amphibian osmosis-regulatory epithelium.

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

    Science.gov (United States)

    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.

  19. Substitution of lucerne hay by untreated, urea-enriched and urea ...

    African Journals Online (AJOL)

    Wheat straw (no treatment applied) (WS). 2. Wheat straw enriched with 1.5% urea. Solution applied and dried prior to mixing the diets (UWS). 3. Wheat straw ammoniated with 5.5% urea in a stack, covered with a plastic sheet for 8 weeks and dried after- wards (AWS) (Cloete & Kritzinger, 1984). Lucerne hay (LH) as well as ...

  20. Patterns of gaseous nitrogen losses from cattle slurries enriched with urea of urea ammonium nitrate

    NARCIS (Netherlands)

    Postma, R.; Velthof, G.L.; Oenema, O.

    2000-01-01

    A study was conducted to investigate the potential of using mixtures of cattle slurry with cheap urea (U) or urea-ammonium nitrate (UAN). The kinetics of NH3 volatilization, nitrous oxide (N2O) emission and denitrification after the addition of U and

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

    DEFF Research Database (Denmark)

    Agner, T; Andersen, Klaus Ejner; Björkner, B

    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...

  2. Transportes

    Directory of Open Access Journals (Sweden)

    Hidalgo Fernández-Cano, Amalio

    1960-01-01

    Full Text Available El movimiento de materiales dentro de la Factoría está atendido por tres principales medios de transporte, en consonancia con las características del material y de los desplazamientos. Así se han establecido: sistemas de cintas transportadoras, una red ferroviaria de ancho normal y una completa malla de caminos enlazando funcionalmente las instalaciones.

  3. Reaction mechanism for chlorination of urea.

    Science.gov (United States)

    Blatchley, Ernest R; Cheng, Mingming

    2010-11-15

    Experiments were conducted to elucidate the mechanism of the reaction between free chlorine and urea. In combination with findings of previous investigations, the results of these experiments indicate a process by which urea undergoes multiple N-chlorination steps. The first of these steps results in the formation of N-chlorourea; this step appears to require Cl₂ to proceed and is the overall rate-limiting step in the reaction for conditions that correspond to most swimming pools. N-Chlorourea then appears to undergo further chlorine substitution; the fully N-chlorinated urea molecule is hypothesized to undergo hydrolysis and additional chlorination to yield NCl₃ as an intermediate. NCl₃ is hydrolyzed to yield NH₂Cl and NHCl₂, with subsequent decay to stable end products, including N₂ and NO₃⁻. Conversion of urea-N to nitrate is pH-dependent. The pattern of nitrate yield is believed to be attributable to the fact that when urea serves as the source of reduced-N, entry into the reactions that describe chlorination of ammoniacal nitrogen is through NCl₃, whereas when NH₃ is the source of reduced-N, entry to these reactions is through NH₂Cl.

  4. Photoluminescence of urea- and urea/rhodamine B-capped TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalo-Juan, I., E-mail: gonzalo@materials.tu-darmstadt.de; Macé, L.; Tengeler, S.; Mosallem, A.; Nicoloso, N.; Riedel, R.

    2016-07-01

    Urea- and rhodamine B (RhB)-capped TiO{sub 2} nanoparticles (NPs) have been prepared by solvothermal synthesis and characterized by HRTEM, XRD, FTIR, XPS, optical absorption and photoemission. The urea and urea/RhB ligands are capped to the surface of the TiO{sub 2} NPs for the first time through carbamate bonding. The band gap of TiO{sub 2} is slightly reduced from 3.1 eV to 3.0 eV in the urea capped TiO{sub 2} NPs (TU) and 2.9 eV for the NPs capped with urea/RhB (TUR). The generation of new trapping states in TU and TUR at the conduction band edges (surface oxygen vacancies) has been confirmed by the Urbach law providing tail state energies of 180 meV and 270 meV, respectively. These tail states are considered to be responsible for the strong reduction of the photoluminescence at ≈400 nm and the increased emission at ≈600 nm in TU and TUR. The findings suggest that urea- and RhB-capped TiO{sub 2} NPs could have potential applications as photocatalysts, opto-electronic devices, sensors, biological labels and anti-bacterial agents. - Highlights: • Urea- and urea/rhodamine B (RhB)-capped TiO{sub 2} nanoparticles preparation. • Characterization of optical properties of urea- and urea/rhodamine B (RhB)-capped TiO{sub 2} nanoparticles. • The recombination of electrons and holes is significantly reduced in the capped TiO{sub 2} nanoparticles, in comparison with TiO{sub 2}.

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

    DEFF Research Database (Denmark)

    Brahm, Jesper

    2013-01-01

    -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......) and 2.35×10(-3) cm s(-1) (human). DIDS, DNDS and phloretin inhibit PCl by >99% in all RBC species. PCMBS, PCMB and phloretin inhibit Purea by >99% in Amphiuma, dog and human RBC, but not in chick and duck RBC. PCMBS and PCMB inhibit Pd in duck, dog and human RBC, but not in chick and Amphiuma RBC...... that anion (AE1), urea (UT-B) and water (AQP1) transporters only transport chloride (all species), water (duck, dog, human) and urea (Amphiuma, dog, human), respectively. Water does not share UT-B with urea, and the solute transport is not coupled under physiological conditions....

  6. Effects of dietary urea concentration and zilpaterol hydrochloride on performance and carcass characteristics of finishing steers.

    Science.gov (United States)

    Samuelson, K L; Hubbert, M E; Löest, C A

    2016-12-01

    Cattle receiving zilpaterol hydrochloride () may recycle less N and require a greater supply of RDP. This study evaluated effects of ZH on performance and carcass characteristics of steers fed diets with increasing dietary RDP concentrations supplied as urea. Steers (429 animals; BW = 423 ± 4.5 kg) were sorted into 3 blocks according to BW and assigned to 1 of 6 treatments (6 pens per treatment) in a randomized complete block design. Treatments were a 2 × 3 factorial arrangement of either no ZH or ZH (75 mg ZH per steer daily) supplemented to finishing diets containing 0, 0.5, or 1.0% urea of dietary DM. Pen weights were recorded before treatment initiation; urea was fed for 27 d, and ZH treatments were fed for 24 d with a 3-d withdrawal period. Pen weights were recorded before transporting steers to a commercial abattoir. Continuous response variables were analyzed using the MIXED procedure and categorical data were analyzed using the GLIMMIX procedure of SAS. No ZH × dietary urea interactions ( ≥ 0.14) occurred for all performance and carcass response variables. Feeding ZH for the last 27 d (included a 3-d withdrawal period) of the finishing period increased ( urea linearly decreased ( = 0.01) ADG and DMI. A tendency for a linear decrease ( = 0.10) in HCW, and a tendency for a quadratic increase ( = 0.07) in marbling score were observed as urea increased in the diet. Results indicate that cattle supplemented with ZH do not require additional RDP in the diet, and that performance and carcass characteristics were negatively affected when urea was increased in the diet.

  7. THE POTENTIOMETRIC UREA BIOSENSOR USING CHITOSAN MEMBRANE

    Directory of Open Access Journals (Sweden)

    Ani Mulyasuryani

    2010-07-01

    Full Text Available Potentiometric urea biosensor development is based on urea hydrolysis by urease resulted CO2. The biosensor is used chitosan membrane and the H3O+ electrode as a transducer. The research was studied of effecting pH and membrane thickness to the biosensor performance. The best biosensor performance resulted at pH = 7.3 and 0.2 mm of membrane thickness. The biosensor has a Nerntian factor 28.47 mV/decade; the concentration range is 0.1 up to 6.00 ppm; and the limit of detection is 0.073 ppm. The response time of this biosensor is 280 seconds, efficiency 32 samples and accuracy 94% up to 99%.   Keywords: biosensor, potentiometry, urea, chitosan membrane

  8. Ammonia volatilization from coated urea forms

    OpenAIRE

    Carlos Antonio Costa do Nascimento; Godofredo Cesar Vitti; Letícia de Abreu Faria; Pedro Henrique de Cerqueira Luz; Fernanda Latanze Mendes

    2013-01-01

    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 s...

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

    CERN Document Server

    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)-...

  10. The excretion of urea by dogs following a meat meal.

    Science.gov (United States)

    O'Connor, W J; Summerill, R A

    1976-01-01

    1. After a meal of meat (10g/kg), urea excretion in dogs increased by about 200%, plasma urea by 60% and exogenous creatinine clearance by 40% in comparison with control experiments. 2. Urea, given by stomach tube in doses producing the same increase in plasma urea, caused urea excretion to increase by only 90%, with no increase in creatinine clearance. With the increased glomerular filtration rate after meat there was added excretion of urea. 3. In control experiments and after urea, the rate of excretion of urea was directly proportional to plasma urea. The ratio urea clearance/creatinine clearance, was 0-45. 4. After meat, urea clearance increased more than creatinine clearance, the ratio increasing to 0-55, i.e. a smaller fraction of the filtered urea was re-absorbed after meat. 5. After meat, 10g/kg, the rate of urea production rose to 230-600 mumole/min for 4-6 hr. PMID:933071

  11. Adsorption of humic acid on acid-activated Greek bentonite.

    Science.gov (United States)

    Doulia, Danae; Leodopoulos, Ch; Gimouhopoulos, K; Rigas, F

    2009-12-15

    The adsorption of humic acid on bentonite from Milos Island (Greece) acid-treated with dilute H(2)SO(4) solutions over a concentration range between 0.25 and 13M has been studied. Bentonite activated with 3M sulfuric acid (AAS) showed a higher efficiency in removing humic acid from aqueous solutions and was selected for further investigation. The specific surface area of acid-activated bentonite was estimated using the methylene blue adsorption method. The morphology of untreated, activated, and HA-sorbed bentonite was studied under scanning electron microscope (SEM). The effects of contact time, adsorbate concentration, adsorbent dose, and temperature on the adsorption of humic acid onto bentonite activated with 3M H(2)SO(4) were studied using a batch adsorption technique. Acidic pH and high ionic strength proved to be favorable for the adsorption efficiency. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to describe the kinetic data and the rate constants were evaluated. The experimental isotherm data were analyzed using Langmuir, Freundlich, and Temkin equations and the isotherm constants were determined. Thermodynamic parameters (DeltaH(o), DeltaS(o), and DeltaG(o)) of adsorption of humic acid onto acid-activated bentonite with 3M sulfuric acid were also evaluated.

  12. Hydroponics versus field lysimeter studies of urea, ammonium and nitrate uptake by oilseed rape (Brassica napus L.).

    Science.gov (United States)

    Arkoun, Mustapha; Sarda, Xavier; Jannin, Laëtitia; Laîné, Philippe; Etienne, Philippe; Garcia-Mina, José-Maria; Yvin, Jean-Claude; Ourry, Alain

    2012-09-01

    N-fertilizer use efficiencies are affected by their chemical composition and suffer from potential N-losses by volatilization. In a field lysimeter experiment, (15)N-labelled fertilizers were used to follow N uptake by Brassica napus L. and assess N-losses by volatilization. Use of urea with NBPT (urease inhibitor) showed the best efficiency with the lowest N losses (8% of N applied compared with 25% with urea alone). Plants receiving ammonium sulphate, had similar yield achieved through a better N mobilization from vegetative tissues to the seeds, despite a lower N uptake resulting from a higher volatilization (43% of applied N). Amounts of (15)N in the plant were also higher when plants were fertilized with ammonium nitrate but N-losses reached 23% of applied N. In parallel, hydroponic experiments showed a deleterious effect of ammonium and urea on the growth of oilseed rape. This was alleviated by the nitrate supply, which was preferentially taken up. B. napus was also characterized by a very low potential for urea uptake. BnDUR3 and BnAMT1, encoding urea and ammonium transporters, were up-regulated by urea, suggesting that urea-grown plants suffered from nitrogen deficiency. The results also suggested a role for nitrate as a signal for the expression of BnDUR3, in addition to its role as a major nutrient. Overall, the results of the hydroponic study showed that urea itself does not contribute significantly to the N nutrition of oilseed rape. Moreover, it may contribute indirectly since a better use efficiency for urea fertilizer, which was further increased by the application of a urease inhibitor, was observed in the lysimeter study.

  13. Kinetics on cocondensation of phenol and urea

    Science.gov (United States)

    Bunichiro Tomita; Yasunori Yoshida; Chung-Yun. Hse

    1993-01-01

    The chemical kinetics on cocondensation between methylolphenols and urea under acidic condition were investigated using 2- and 4-hydroxybenzyl alcohols as well as 2,4,6-trimethylolphenol as model compounds. The reactivity of the cocondensation were compared between o- and p-methylol groups. Moreover, the kinetics on self-condensations of monomethylolphenols and...

  14. Disorders of urea cycle: case report

    Directory of Open Access Journals (Sweden)

    Adolfo Álvarez

    2017-08-01

    Discussion: Urea cycle disorders are part of innate errors in ammonia detoxification or arginine synthesis, secondary to defects in the enzymes involved in this cycle. Clinical manifestations are secondary to elevated levels of serum ammonia. The treatment is composed of an acute and chronic phase.

  15. Urea retranslocation from senescing Arabidopsis leaves is promoted by DUR3-mediated urea retrieval from leaf apoplast.

    Science.gov (United States)

    Bohner, Anne; Kojima, Soichi; Hajirezaei, Mohammad; Melzer, Michael; von Wirén, Nicolaus

    2015-02-01

    In plants, urea derives either from root uptake or protein degradation. Although large quantities of urea are released during senescence, urea is mainly seen as a short-lived nitrogen (N) catabolite serving urease-mediated hydrolysis to ammonium. Here, we investigated the roles of DUR3 and of urea in N remobilization. During natural leaf senescence urea concentrations and DUR3 transcript levels showed a parallel increase with senescence markers like ORE1 in a plant age- and leaf age-dependent manner. Deletion of DUR3 decreased urea accumulation in leaves, whereas the fraction of urea lost to the leaf apoplast was enhanced. Under natural and N deficiency-induced senescence DUR3 promoter activity was highest in the vasculature, but was also found in surrounding bundle sheath and mesophyll cells. An analysis of petiole exudates from wild-type leaves revealed that N from urea accounted for >13% of amino acid N. Urea export from senescent leaves further increased in ureG-2 deletion mutants lacking urease activity. In the dur3 ureG double insertion line the absence of DUR3 reduced urea export from leaf petioles. These results indicate that urea can serve as an early metabolic marker for leaf senescence, and that DUR3-mediated urea retrieval contributes to the retranslocation of N from urea during leaf senescence. © 2014 The Authors The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.

  16. Urea retranslocation from senescing Arabidopsis leaves is promoted by DUR3-mediated urea retrieval from leaf apoplast

    Science.gov (United States)

    Bohner, Anne; Kojima, Soichi; Hajirezaei, Mohammad; Melzer, Michael; von Wirén, Nicolaus

    2015-01-01

    In plants, urea derives either from root uptake or protein degradation. Although large quantities of urea are released during senescence, urea is mainly seen as a short-lived nitrogen (N) catabolite serving urease-mediated hydrolysis to ammonium. Here, we investigated the roles of DUR3 and of urea in N remobilization. During natural leaf senescence urea concentrations and DUR3 transcript levels showed a parallel increase with senescence markers like ORE1 in a plant age- and leaf age-dependent manner. Deletion of DUR3 decreased urea accumulation in leaves, whereas the fraction of urea lost to the leaf apoplast was enhanced. Under natural and N deficiency-induced senescence DUR3 promoter activity was highest in the vasculature, but was also found in surrounding bundle sheath and mesophyll cells. An analysis of petiole exudates from wild-type leaves revealed that N from urea accounted for >13% of amino acid N. Urea export from senescent leaves further increased in ureG-2 deletion mutants lacking urease activity. In the dur3 ureG double insertion line the absence of DUR3 reduced urea export from leaf petioles. These results indicate that urea can serve as an early metabolic marker for leaf senescence, and that DUR3-mediated urea retrieval contributes to the retranslocation of N from urea during leaf senescence. PMID:25440717

  17. DENATURATION CHANGES IN EGG ALBUMIN WITH UREA, RADIATION, AND HEAT.

    Science.gov (United States)

    Clark, J H

    1943-11-20

    The extent of urea denaturation depends on the concentration of protein and urea and also on the temperature of the solution. Egg albumin solutions (0.9 per cent) are not denatured by 20 per cent urea, denature slowly with 25 per cent urea, and denature rapidly with 35 per cent urea at room temperature. At a higher temperature 30 per cent urea is rapidly effective. Denaturation of the egg albumin molecule by radiation or by heat is accompanied by structural changes as evidenced by optical rotation values, but is not accompanied by association or dissociation of the molecule in the pH range outside the zone in which aggregation follows denaturation. Denaturation of the egg albumin molecule by urea produces no change in optical rotation until the concentration of urea is high enough to dissociate the molecule. In the presence of urea a urea-protein complex is formed in which the protein is denatured but cannot flocculate because of the dispersive action of the urea. This prevents flocculation of proteins exposed to radiation and subsequent heating to 40 degrees C. as the urea-protein complex is not broken down at a temperature of 40 degrees C. The presence of urea therefore prevents the flocculation of proteins denatured by radiation. The urea-protein complex is broken down by heating to 55-58 degrees C. so that the molecules aggregate at a temperature below the temperature of rapid heat denaturation. This appears to be an acceleration of heat denaturation or a lowering of the heat denaturation temperature, but in reality is an effect of heat on the urea-protein complex which frees the urea-denatured protein and permits its aggregation.

  18. Control of ammonia and urea emissions from urea manufacturing facilities of Petrochemical Industries Company (PIC), Kuwait.

    Science.gov (United States)

    Khan, A R; Al-Awadi, L; Al-Rashidi, M S

    2016-06-01

    Petrochemical Industries Company (PIC) in Kuwait has mitigated the pollution problem of ammonia and urea dust by replacing the melting and prilling units of finished-product urea prills with an environmentally friendly granulation process. PIC has financed a research project conducted by the Coastal and Air Pollution Program's research staff at the Kuwait Institute for Scientific Research to assess the impact of pollution control strategies implemented to maintain a healthy productive environment in and around the manufacturing premises. The project was completed in three phases: the first phase included the pollution monitoring of the melting and prilling units in full operation, the second phase covered the complete shutdown period where production was halted completely and granulation units were installed, and the last phase encompassed the current modified status with granulation units in full operation. There was substantial decrease in ammonia emissions, about 72%, and a 52.7% decrease in urea emissions with the present upgrading of old melting and prilling units to a state-of-the-art technology "granulation process" for a final finished product. The other pollutants, sulfur dioxide (SO2), nitrogen oxides (NOx), and volatile organic compounds (VOCs), have not shown any significant change, as the present modification has not affected the sources of these pollutants. Petrochemical Industries Company (PIC) in Kuwait has ammonia urea industries, and there were complaints about ammonia and urea dust pollution. PIC has resolved this problem by replacing "melting and prilling unit" of final product urea prills by more environmentally friendly "granulation unit." Environmental Pollution and Climate Program has been assigned the duty of assessing the outcome of this change and how that influenced ammonia and urea dust emissions from the urea manufacturing plant.

  19. The effects of urea, guanidinium chloride and sorbitol on porphyrin ...

    Indian Academy of Sciences (India)

    potency between the Gdn and urea, with the urea being less potent to decrease hydration layer and porphyrin aggregation. Keywords. Porphyrin; molecular dynamics simulation; urea; sorbitol; radial distribution function; aggregation. 1. Introduction. The importance of porphyrins as therapeutic drugs and targeting agents ...

  20. Infrared spectroscopic monitoring of urea addition to oriented strandboard resins

    Science.gov (United States)

    Chi-Leung So; Thomas L. Eberhardt; Ernest Hsu; Brian K. Via; Chung Y. Hse

    2007-01-01

    One of the variables in phenol formaldehyde adhesive resin formulation is the addition of urea, which allows the resin manufacturer to manipulate both product functionality and cost. Nitrogen content can be used as a measure of the level of urea addition because most of the nitrogen present is derived from urea added at the end of the preparation process. Nitrogen...

  1. A field evaluation of coated urea with biodegradable materials and ...

    African Journals Online (AJOL)

    Urease inhibitor and biodegradable polymer coatings are two most suitable startegies to increase urea fertilizer efficiency. Coating of urea with selected inhibitors can increase the crop production by slowing down the hydrolysis process of urea in the soil. For this purpose, a field experiment was conducted to evaluate the ...

  2. 76 FR 77015 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2011-12-09

    ... COMMISSION Solid Urea From Russia and Ukraine Determination On the basis of the record \\1\\ developed in the... antidumping duty orders on solid urea from Russia and Ukraine would be likely to lead to continuation or... 2011), entitled Solid Urea from Russia and Ukraine: Investigation Nos. 731-TA- 340-E and 340-H (Third...

  3. 76 FR 15339 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2011-03-21

    ... 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 will...)) to determine whether revocation of the antidumping duty orders on solid urea from Russia and Ukraine...

  4. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Science.gov (United States)

    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... the provisions of this section. (a) Sodium nitrate-urea complex is a clathrate of approximately two...

  5. 40 CFR 721.9925 - Aminoethylethylene urea methacrylamide.

    Science.gov (United States)

    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 urea...

  6. Penentuan Rute Pengiriman Pupuk Urea Bersubsidi di Karanganyar

    Directory of Open Access Journals (Sweden)

    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.

  7. Short communication: Urea hydrolysis in dairy cattle manure under different temperature, urea, and pH conditions.

    Science.gov (United States)

    Moraes, L E; Burgos, S A; DePeters, E J; Zhang, R; Fadel, J G

    2017-03-01

    The objective of the study was to quantify the rate of urea hydrolysis in dairy cattle manure under different initial urea concentration, temperature, and pH conditions. In particular, by varying all 3 factors simultaneously, the interactions between them could also be determined. Fresh feces and artificial urine solutions were combined into a slurry to characterize the rate of urea hydrolysis under 2 temperatures (15°C and 35°C), 3 urea concentrations in urine solutions (500, 1,000, and 1,500 mg of urea-N/dL), and 3 pH levels (6, 7, and 8). Urea N concentration in slurry was analyzed at 0.0167, 1, 2, 4, 6, 8, 12, 16, 20, and 24 h after initial mixing. A nonlinear mixed effects model was used to determine the effects of urea concentration, pH, and temperature treatments on the exponential rate of urea hydrolysis and to predict the hydrolysis rate for each treatment combination. We detected a significant interaction between pH and initial urea level. Increasing urea concentration from 1,000 to 1,500 mg of urea-N/dL decreased the rate of urea hydrolysis across all pH levels. Across all pH and initial urea levels, the rate of urea hydrolysis increased with temperature, but the effect of pH was only observed for pH 6 versus pH 8 at the intermediate initial urea concentration. The fast rates of urea hydrolysis indicate that urea was almost completely hydrolyzed within a few hours of urine mixing with feces. The estimated urea hydrolysis rates from this study are likely maximum rates because of the thorough mixing before each sampling. Although considerable mixing of feces and urine occurs on the barn floor of commercial dairy operations from cattle walking through the manure, such mixing may be not as quick and thorough as in this study. Consequently, the urea hydrolysis rates from this study indicate the maximum loss of urea and should be accounted for in management aimed at mitigating ammonia emissions from dairy cattle manure under similar urea concentration, p

  8. Pimelic acid–urea (1/2)

    Science.gov (United States)

    Xu, Wei; Huang, Wen-xiang; Chen, Hong-yan

    2011-01-01

    The asymmetric unit, 2CH4N2O·C7H12O4, of the title cocrystal contains one urea mol­ecule and a half-mol­ecule of pimelic acid; the latter, together with a second urea mol­ecule, are completed by symmetry, with the central atom of the whole pimelic acid moiety placed on a twofold crystallographic axis. The crystal packing is stabilized by O—H⋯O and N—H⋯O hydrogen-bond, generating a chain along [10]. Additionally, the chains are assembled into a three-dimensional framework via weak N—H⋯O inter­chain inter­actions. PMID:21837168

  9. Urea, a true uremic toxin: the empire strikes back.

    Science.gov (United States)

    Lau, Wei Ling; Vaziri, Nosratola D

    2017-01-01

    Blood levels of urea rise with progressive decline in kidney function. Older studies examining acute urea infusion suggested that urea was well-tolerated at levels 8-10× above normal values. More recent in vitro and in vivo work argue the opposite and demonstrate both direct and indirect toxicities of urea, which probably promote the premature aging phenotype that is pervasive in chronic kidney disease (CKD). Elevated urea at concentrations typically encountered in uremic patients induces disintegration of the gut epithelial barrier, leading to translocation of bacterial toxins into the bloodstream and systemic inflammation. Urea induces apoptosis of vascular smooth muscle cells as well as endothelial dysfunction, thus directly promoting cardiovascular disease. Further, urea stimulates oxidative stress and dysfunction in adipocytes, leading to insulin resistance. Finally, there are widespread indirect effects of elevated urea as a result of the carbamylation reaction, where isocyanic acid (a product of urea catabolism) alters the structure and function of proteins in the body. Carbamylation has been linked with renal fibrosis, atherosclerosis and anaemia. In summary, urea is a re-emerging Dark Force in CKD pathophysiology. Trials examining low protein diet to minimize accumulation of urea and other toxins suggest a clinical benefit in terms of slowing progression of CKD. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  10. Milk Urea Dynamics during its Transformation into Yogurt

    Directory of Open Access Journals (Sweden)

    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.

  11. Analysis of urea distribution volume in hemodialysis.

    Science.gov (United States)

    Maduell, F; Sigüenza, F; Caridad, A; Miralles, F; Serrato, F

    1994-01-01

    According to the urea kinetic model it is considered that the urea distribution volume (V) is that of body water, and that it is distributed in only one compartment. Since the V value is different to measure, it is normal to use 58% of body weight, in spite of the fact that it may range from 35 to 75%. In this study, we have calculated the value of V by using an accurate method based on the total elimination of urea from the dialysate. We have studied the V, and also whether the different dialysis characteristics modify it. Thirty-five patients were included in this study, 19 men and 16 women, under a chronic hemodialysis programme. The dialysate was collected in a graduated tank, and the concentration of urea in plasma and in dialysate were determined every hour. Every patient received six dialysis sessions, changing the blood flow (250 or 350 ml/min), the ultrafiltration (0.5 or 1.5 l/h), membrane (cuprophane or polyacrylonitrile) and/or buffer (bicarbonate or acetate). At the end of the hemodialysis session, the V value ranged from 43 to 72% of body weight; nevertheless, this value was practically constant in every patient. The V value gradually increased throughout the dialysis session, 42.1 +/- 6.9% of body weight in the first hour, 50.7 +/- 7.5% in the second hour and 55.7 +/- 7.9% at the end of the dialysis session. The change of blood flow, ultrafiltration, membrane or buffer did not alter the results. The V value was significantly higher in men in comparison with women, 60.0 +/- 6.6% vs. 50.5 +/- 5.9% of body weight (p < 0.001).

  12. Determination of urea kinetics by isotope dilution with [C-13]urea and gas chromatography isotope ratio mass spectrometry (GC-IRMS) analysis

    NARCIS (Netherlands)

    Kloppenburg, Wybe; Wolthers, BG; Stellaard, F; Elzinga, H; Tepper, T; deJong, PE; Huisman, RM

    1. Stable urea isotopes can be used to study urea kinetics in humans, The use of stable urea isotopes far studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material, We devised a urea dilution for measurement of the distribution volume,

  13. Mechanochemical synthesis of thioureas, ureas and guanidines.

    Science.gov (United States)

    Štrukil, Vjekoslav

    2017-01-01

    In this review, the recent progress in the synthesis of ureas, thioureas and guanidines by solid-state mechanochemical ball milling is highlighted. While the literature is abundant on their preparation in conventional solution environment, it was not until the advent of solvent-free manual grinding using a mortar and pestle and automated ball milling that new synthetic opportunities have opened. The mechanochemical approach not only has enabled the quantitative synthesis of (thio)ureas and guanidines without using bulk solvents and the generation of byproducts, but it has also been established as a means to develop "click-type" chemistry for these classes of compounds and the concept of small molecule desymmetrization. Moreover, mechanochemistry has been demonstrated as an effective tool in reaction discovery, with emphasis on the reactivity differences in solution and in the solid state. These three classes of organic compounds share some structural features which are reflected in their physical and chemical properties, important for application as organocatalysts and sensors. On the other hand, the specific and unique nature of each of these functionalities render (thio)ureas and guanidines as the key constituents of pharmaceuticals and other biologically active compounds.

  14. Profile of sodium phenylbutyrate granules for the treatment of urea-cycle disorders: patient perspectives

    Directory of Open Access Journals (Sweden)

    Peña-Quintana L

    2017-09-01

    Full Text Available Luis Peña-Quintana,1–3 Marta Llarena,2 Desiderio Reyes-Suárez,2 Luis Aldámiz-Echevarria4 1Pediatric Gastroenterology, Hepatology, and Nutrition Unit, Universitario Materno-Infantil Hospital de Canarias, University of Las Palmas de Gran Canaria, 2Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas, 3CIBEROBN, Madrid, 4Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfremedades Raras (CIBERER, Barakaldo, Spain Abstract: Urea-cycle disorders are a group of rare hereditary metabolic diseases characterized by deficiencies of one of the enzymes and transporters involved in the urea cycle, which is necessary for the removal of nitrogen produced from protein breakdown. These hereditary metabolic diseases are characterized by hyperammonemia and life-threatening hyperammonemic crises. Pharmacological treatment of urea-cycle disorders involves alternative nitrogen-scavenging pathways. Sodium benzoate combines with glycine and phenylacetate/phenylbutyrate with glutamine, forming, respectively, hippuric acid and phenylacetylglutamine, which are eliminated in the urine. Among the ammonia-scavenging drugs, sodium phenylbutyrate is a well-known long-term treatment of urea-cycle disorders. It has been used since 1987 as an investigational new drug, and was approved for marketing in the US in 1996 and the EU in 1999. However, sodium phenylbutyrate has an aversive odor and taste, which may compromise patients’ compliance, and many patients have reported difficulty in taking this drug. Sodium phenylbutyrate granules are a new tasteless and odor-free formulation of sodium phenylbutyrate, which is indicated in the treatment of urea-cycle disorders. This recently developed taste-masked formulation of sodium phenylbutyrate granules was designed to overcome the considerable issues that taste has on adherence to therapy. Several studies have reported the

  15. The Effects of Acid Activation on the Thermal Properties of Polyvinylpyrrolidone and Organoclay Composites

    OpenAIRE

    Kooli, F.

    2015-01-01

    The thermal stabilities of polyvinylpyrrolidone-organoclays or organo-acid-activated clay composites prepared by chemical exchange reactions were assessed. The raw clay mineral was acid-activated prior to expansion by cetyltrimethylammonium surfactants. The acid activation process affected the intercalated amount of cetyltrimethylammonium cations in the resulting organoclays and, thus, the amount of polyvinylpyrrolidone in the composite. The content of cetyltrimethylammonium cations decreased...

  16. Reflection coefficient and permeability of urea and ethylene glycol in the human red cell membrane

    Energy Technology Data Exchange (ETDEWEB)

    Levitt, D.G.; Mlekoday, H.J.

    1983-02-01

    The reflection coefficient (sigma) and permeability (P) of urea and ethylene glycol were determined by fitting the equations of Kedem and Katchalsky (1958) to the change in light scattering produced by adding a permeable solute to a red cell suspension. The measurements incorporated three important modifications: (a) the injection artifact was eliminated by using echinocyte cells; (b) the use of an additional adjustable parameter (Km), the effective dissociation constant at the inner side of the membrane; (c) the light scattering is not directly proportional to cell volume (as is usually assumed) because refractive index and scattering properties of the cell depend on the intracellular permeable solute concentration. This necessitates calibrating for known changes in refractive index (by the addition of dextran) and cell volume (by varying the NaCl concentration). The best fit was for sigma . 0.95, Po . 8.3 X 10(-4) cm/s, and Km . 100 mM for urea and sigma . 1.0, Po . 3.9 X 10(-4) cm/s, and Km . 30 mM for ethylene glycol. The effects of the inhibitors copper, phloretin, p-chloromercuriphenylsulfonate, and 5,5'-dithiobis (2-nitro) benzoic acid on the urea, ethylene glycol, and water permeability were determined. The results suggest that there are three separate, independent transport systems: one for water, one for urea and related compounds, and one for ethylene glycol and glycerol.

  17. Competitive sorption between imidacloprid and imidacloprid-urea on soil clay minerals and humic acids.

    Science.gov (United States)

    Liu, Weiping; Zheng, Wei; Gan, Jianying

    2002-11-06

    Soil organic matter and clay minerals are responsible for the adsorption of many pesticides. Adsorption and competitive sorption of imidacloprid on clay minerals and humic acids (HA) were determined using the batch equilibration method. The sorption coefficient of imidacloprid on humic acids was significantly higher than that on Ca-clay minerals, indicating that soil organic matter content was a more important property in influencing the adsorption of imidacloprid. Competitive sorption was investigated between imidacloprid and its main metabolite imidacloprid-urea on HA and Ca-clay minerals. The results showed that the sorption capacity of imidacloprid on clay minerals and HA was reduced in the presence of the metabolite, implying that imidacloprid-urea could occupy or block adsorption sites of imidacloprid on soil, potentially affecting the fate, transport, and bioavailability of imidacloprid in the environment. The interactions between a Ca-clay or HA-clay mixture and adsorption of imidacloprid and imidacloprid-urea were studied using IR differential spectra on thin films made of the adsorbent. The possible mechanisms were discussed from the shift of characteristic IR absorption bands of imidacloprid and imidacloprid-urea after sorption.

  18. Variation of milk urea in dairy cattle : a study on factors that affect the relationship between urea concentration in milk and urea excretion in urine

    NARCIS (Netherlands)

    Spek, J.W.

    2013-01-01

    The aim of this thesis was to increase the applicability of milk urea nitrogen concentration (MUN) as a predictor of urinary urea nitrogen excretion (UUN) by identifying and quantifying factors that can explain variation in MUN that is not related to UUN. A literature study was conducted in order to

  19. Acid-activated biochar increased sulfamethazine retention in soils.

    Science.gov (United States)

    Vithanage, Meththika; Rajapaksha, Anushka Upamali; Zhang, Ming; Thiele-Bruhn, Sören; Lee, Sang Soo; Ok, Yong Sik

    2015-02-01

    Sulfamethazine (SMZ) is an ionizable and highly mobile antibiotic which is frequently found in soil and water environments. We investigated the sorption of SMZ onto soils amended with biochars (BCs) at varying pH and contact time. Invasive plants were pyrolyzed at 700 °C and were further activated with 30 % sulfuric (SBBC) and oxalic (OBBC) acids. The sorption rate of SMZ onto SBBC and OBBC was pronouncedly pH dependent and was decreased significantly when the values of soil pH increased from 3 to 5. Modeled effective sorption coefficients (K D,eff) values indicated excellent sorption on SBBC-treated loamy sand and sandy loam soils for 229 and 183 L/kg, respectively. On the other hand, the low sorption values were determined for OBBC- and BBC700-treated loamy sand and sandy loam soils. Kinetic modeling demonstrated that the pseudo second order model was the best followed by intra-particle diffusion and the Elovich model, indicating that multiple processes govern SMZ sorption. These findings were also supported by sorption edge experiments based on BC characteristics. Chemisorption onto protonated and ligand containing functional groups of the BC surface, and diffusion in macro-, meso-, and micro-pores of the acid-activated BCs are the proposed mechanisms of SMZ retention in soils. Calculated and experimental q e (amount adsorbed per kg of the adsorbent at equilibrium) values were well fitted to the pseudo second order model, and the predicted maximum equilibrium concentration of SBBC for loamy sand soils was 182 mg/kg. Overall, SBBC represents a suitable soil amendment because of its high sorption rate of SMZ in soils.

  20. PREPARASI MOLECULARLY IMPRINTED POLYMERS SEBAGAI ADSORBEN UNTUK UREA DAN KREATININ

    Directory of Open Access Journals (Sweden)

    Irhamni Irhamni

    2016-07-01

    Full Text Available Penelitian mengenai Molecularly Imprinted Polymers (MIPs,, khususnya terkait dengan pemanfaatannya sebagai adsorben, mengalami perkembangan yang cukup signifikan, karena sensitivitas dan selektivitasnya tinggi. Selain itu, preparasinya yang mudah dan murah. Penelitian ini bertujuan untuk mensisntesis senyawa MIPs yang dapat digunakan untuk adsorben pada adsorpsi urea dan kreatinin. Penelitian dimulai dengan preparasi grapena dari grafit, preparasi senyawa Molecularly Imprinted Polymers (MIPs dan penentuan kondisi optimal preparasi dan karakterisasi kimia dan morfologi permukaannya menggunakan IR , XRD dan SEM. Kemudian dilanjutkan dengan karakterisasi adsorpsi senyawa MIPs terhadap urea dan kreatinin. Senyawa Molecularly imprinted polymers (MIPs telah berhasil dipreparasi dengan menggunakan material kitosan yang dikompositkan dengan grapena sebagai polimernya serta urea dan keatinin sebagai senyawa template. Senyawa MIPs yang terbentuk dapat digunakan sebagai adsorben pada urea dan kreatinin. Kemampuan adsorpsi MIPs terhadap urea dan kreatinin secara bertahap naik sebanding dengan kenaikan konsentrasi dan waktu interaksi dengan analit. Mekanisme adsorpsi MIPs terhadap urea dan kreatinin terjadi melalui meknisme ikatan hidrogen pada pori cetakan senyawa MIPs.

  1. The optoelectronic sensor creatinine and urea

    Science.gov (United States)

    Vistak, Maria V.; Dmytrakh, Vasyl Ye.; Diskovskyu, Ivan S.; Kobylinska, Lesya I.; Mikityuk, Zinoviy M.; Petryshak, Vasyl S.; Barylo, Hryhoriy I.; Holyaka, Roman L.; Amirgaliyev, Yedilkhan; Surtel, Wojciech; DzierŻak, RóŻa

    2017-08-01

    In paper the concept of interaction of cholesteric liquid crystals (CLC) with creatinine and urea to designing the active medium material for optical sensor of biological substances are presented. It is shown that there is a general tendency to reduce the pitch of supramolecular helical structure versus of increasing of concentrations of aqueous solutions for all investigated substances. A decision to designing the scheme of signal converter of optical sensors with frequency selection is proposed. In basis of the proposed decision is impedance converter provided the inductive nature of the impedance circle of load photodiode and therefore suppressing of direct component of the photocurrent.

  2. Synthesis, Characterization, and Sensitivity Analysis of Urea Nitrate (UN)

    Science.gov (United States)

    2015-04-01

    vi INTENTIONALLY LEFT BLANK. 1 1. Introduction Urea nitrate (UN) is a high explosive obtained from the combination of urea and nitric acid...HNO3). Due to its simple composition, ease of manufacture, and higher detonation parameters than ammonium nitrate , it has become one of the... explosives of choice among terrorist organizations.1–4 UN is readily formed by treating a solution of urea in water with concentrated nitric acid. The

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

    Directory of Open Access Journals (Sweden)

    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.

  4. Milk Urea Dynamics during its Transformation into Yogurt

    OpenAIRE

    Cornelia Vintila; Adela Marcu; Teodor Vintila

    2011-01-01

    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...

  5. Design and test of urea hydrolysis reactor for vehicle

    Directory of Open Access Journals (Sweden)

    Qi Zhanfeng

    2017-01-01

    Full Text Available Ammonia production technology of urea-SCR system for vehicle is mainly used in pyrolysis. The reaction is complex, and there are some side effects. So a kind of urea hydrolysis device for vehicle is designed. Based on the in-depth analysis of ammonia production technology’s mechanism of urea hydrolysis for vehicle, the modified extended UNIQUAC equation and PHS equation of state were used to solve the thermodynamic model, and the experimental verification was carried out on the JX493ZLQ3 diesel engine. The results show that the design of urea hydrolysis reactor is in agreement with the experimental results. In the environment of urea hydrolysis, the higher the hydrolysis temperature, the faster the urea hydrolysis and the faster the production of ammonia. Under the same conditions, the hydrolysis rate of urea was the same, the higher the initial quality, the more ammonia produced. The method is suitable for the ammonia production technology of urea hydrolysis for vehicle and can be used for the formation of urea hydrolysis SCR system.

  6. Deaktivasi Katalis Konverter-Hidrogen Di Pabrik Urea Kaltim-3

    National Research Council Canada - National Science Library

    Agus Subekti; Achmad Syamsul Arief; Praharso Praharso; Subagjo Subagjo

    2007-01-01

    Di pabrik urea, konverter-hidrogen adalah satu reaktor yang berfungsi untuk mengkonversi hidrogen yang terikut dalam karbondioksida dengan cara mengoksidasi dengan udara, sehingga karbondioksida umpan...

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Urea kinetics in neonates receiving total parenteral nutrition.

    OpenAIRE

    Wheeler, R. A.; Griffiths, D M; Jackson, A A

    1993-01-01

    Urea kinetics were measured on 10 occasions in eight neonates who had not received an oral intake from birth and were maintained on total parenteral nutrition. After a prime/intermittent oral dose of 15N15N-urea over 14 hours urine was collected every three to four hours, urea isolated, and kinetics determined from the plateau level of enrichment in urea, measured by isotope ratio mass spectrometry. The total parenteral nutrition provided 393 kJ (94 kcal)/kg/day and 360 mg nitrogen/kg/day. Ur...

  9. Permeation of urea through various polyurethane membranes.

    Science.gov (United States)

    Watanabe, Atsushi; Takebayashi, Yoshihiro; Ohtsubo, Toshiro; Furukawa, Mutsuhisa

    2009-11-01

    Controlled-release systems using polymer membranes are very important in agriculture for labour-saving and effective delivery of pesticides and other agents. Polymer-coated granules are one of the most useful formulations, and a study of the factors for polymer design is necessary to achieve various release patterns. A permeation study using plain membranes was carried out in order to clarify parameters, and the results were compared with the release from polymer-coated granules. The permeation coefficient of urea through a plain polyurethane membrane decreased significantly as the urethane and alkyl side chain content increased. The glass transition temperature and crosslink density of the polyurethanes hardly influenced its permeability. The release rate from polyurethane-coated granules was also reduced by alkyl side chains. However, it was faster than that through a plain membrane because of capsule expansion by continuous water penetration and structural changes in the membrane. The release rate of urea through a polyurethane plain membrane and from polyurethane-coated granules can be controlled by changing the chemical properties of the membrane. In addition, physical properties such as the glass transition temperature T(g) or crosslink density should be considered to assess the release profile from polyurethane-coated granules. (c) 2009 Society of Chemical Industry.

  10. Nickel hydroxide modified electrodes for urea determination

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Dall´Antonia

    2007-03-01

    Full Text Available Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO32 0,05 mol L ?¹ on ITO electrodes (Tin oxide doped with Indium on PET-like plastic film, applying a current of - 0,1 A cm ?² during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?¹, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II/Ni(III. A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?¹ and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?¹, the behavior is linear and the sensibility found was of 20,3 mA cm?² (mol L?¹?¹, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.

  11. SnO(2) quantum dots-reduced graphene oxide composite for enzyme-free ultrasensitive electrochemical detection of urea.

    Science.gov (United States)

    Dutta, Dipa; Chandra, Sudeshna; Swain, Akshaya K; Bahadur, Dhirendra

    2014-06-17

    Most of the urea sensors are biosensors and utilize urease, which limit their use in harsh environments. Recently, because of their exceptional ability to endorse faster electron transfer, carbonaceous material composites and quantum dots are being used for fabrication of a sensitive transducer surface for urea biosensors. We demonstrate an enzyme free ultrasensitive urea sensor fabricated using a SnO2 quantum dots (QDs)/reduced graphene oxide (RGO) composite. Due to the synergistic effect of the constituents, the SnO2 QDs/RGO (SRGO) composite proved to be an excellent probe for electrochemical sensing. The morphology and structure of the composite was characterized by various techniques, and it was observed that SnO2 QDs are decorated on RGO layers. Electrochemical studies were performed to evaluate the characteristics of the sensor toward detection of urea. Amperometry studies show that the SRGO/GCE electrode is sensitive to urea in the concentration range of 1.6 × 10(-14)-3.9 × 10(-12) M, with a detection limit of as low as 11.7 fM. However, this is an indirect measurement for urea wherein the analytical signal is recorded as a decrease in the amperommetric and/or voltammetric current from the solution redox species ferrocyanide. The porous structure of the SRGO matrix offers a very low transport barrier and thus promotes rapid diffusion of the ionic species from the solution to the electrode, leading to a rapid response time (∼5 s) and ultrahigh sensitivity (1.38 μA/fM). Good analytical performance in the presence of interfering agents, low cost, and easy synthesis methodology suggest that SRGO can be quite promising as an electroactive material for effective urea sensing.

  12. The effect of urea treated cassava peels as supplement to West ...

    African Journals Online (AJOL)

    The performance of West African Dwarf (WAD) goats grazing natural pasture and supplemented with different levels of urea-treated cassava peels (UTCP) was evaluated. The urea treatments were 0% UTCP, 4% UTCP (40g urea/kg), 6% UTCP (60g urea/kg) and 8% UTCP (80g urea/kg).Twenty WAD bucks aged between 6 ...

  13. Metallic Nickel Hydroxide Nanosheets Give Superior Electrocatalytic Oxidation of Urea for Fuel Cells.

    Science.gov (United States)

    Zhu, Xiaojiao; Dou, Xinyu; Dai, Jun; An, Xingda; Guo, Yuqiao; Zhang, Lidong; Tao, Shi; Zhao, Jiyin; Chu, Wangsheng; Zeng, Xiao Cheng; Wu, Changzheng; Xie, Yi

    2016-09-26

    The direct urea fuel cell (DUFC) is an important but challenging renewable energy production technology, it offers great promise for energy-sustainable developments and mitigating water contamination. However, DUFCs still suffer from the sluggish kinetics of the urea oxidation reaction (UOR) owing to a 6 e(-) transfer process, which poses a severe hindrance to their practical use. Herein, taking β-Ni(OH)2 nanosheets as the proof-of-concept study, we demonstrated a surface-chemistry strategy to achieve metallic Ni(OH)2 nanosheets by engineering their electronic structure, representing a first metallic configuration of transition-metal hydroxides. Surface sulfur incorporation successfully brings synergetic effects of more exposed active sites, good wetting behavior, and effective electron transport, giving rise to greatly enhanced performance for UOR. Metallic nanosheets exhibited a much higher current density, smaller onset potential and stronger durability. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Effect of abomasal infusion of oligofructose on portal-drained visceral ammonia and urea-nitrogen fluxes in lactating Holstein cows.

    Science.gov (United States)

    Røjen, B A; Larsen, M; Kristensen, N B

    2012-12-01

    in arterial blood urea-N concentration appeared not to be due to increased urea-N transport, but rather could be explained by reduced NH(3) input to hepatic urea-N synthesis caused by increased sequestration of NH(3) in the hindgut and excretion in feces. Increasing the hindgut fermentation in lactating dairy cows by abomasal infusion of 1,500 g/d of oligofructose shifted some N excretion from the urine to feces and possibly reduced manure NH(3) volatilization without impairing rumen fermentation. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  15. Mutant Potential Ubiquitination Sites in Dur3p Enhance the Urea and Ethyl Carbamate Reduction in a Model Rice Wine System.

    Science.gov (United States)

    Zhang, Peng; Du, Guocheng; Zou, Huijun; Xie, Guangfa; Chen, Jian; Shi, Zhongping; Zhou, Jingwen

    2017-03-01

    Ubiquitination can significantly affect the endocytosis and degradation of plasma membrane proteins. Here, the ubiquitination of a Saccharomyces cerevisiae urea plasma membrane transporter (Dur3p) was altered. Two potential ubiquitination sites, lysine residues K556 and K571, of Dur3p were predicted and replaced by arginine, and the effects of these mutations on urea utilization and formation under different nitrogen conditions were investigated. Compared with Dur3p, the Dur3pK556R mutant showed a 20.1% decrease in ubiquitination level in yeast nitrogen base medium containing urea and glutamine. It also exhibited a >75.8% decrease in urea formation in yeast extract-peptone-dextrose medium and 41.3 and 55.4% decreases in urea and ethyl carbamate formation (a known carcinogen), respectively, in a model rice wine system. The results presented here show that the mutation of Dur3p ubiquitination sites could significantly affect urea utilization and formation. Modifying the ubiquitination of specific transporters might have promising applications in rationally engineering S. cerevisiae strains to efficiently use specific nitrogen sources.

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

    NARCIS (Netherlands)

    van der Schuur, J.M.; van der Heide, Evert; Feijen, Jan; Gaymans, R.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

  17. Effect of protein supplementation and urea treatment on utilization of ...

    African Journals Online (AJOL)

    Authorised User

    Six Red Maasai sheep were used to investigate the effects of urea treatment and cotton seed cake supplementation of maize ... supplemented urea sprayed wheat straw with different amounts of cotton seed cake and observed a marked increase in straw intake, ..... Brain Power, Inc., Calabasas, CA. Streeter, C.L. & Horn ...

  18. The effects of urea, guanidinium chloride and sorbitol on porphyrin ...

    Indian Academy of Sciences (India)

    The effect of urea, Gdn and sorbitol on porphyrin aggregation has been inferred from the effect of these solutes on the hydration layer of porphyrin. It appears that the Gdn is more suitable than urea for decreasing the hydration layer of porphyrin while several osmolites like sorbitol are known to increase hydration layer and ...

  19. Application of methylol urea/natural rubber copolymer composite for ...

    African Journals Online (AJOL)

    This work is a follow up to our quest to develop emulsion paint from amino resin. Both pure urea methylol (MU) and methylol urea/Nature rubber (MU/NR) blend were prepared. Some physico-chemical properties such as viscosity, melting point, moisture uptake, refractive index, density, elongation at break and formaldehyde ...

  20. Reference Values for Plasma Electrolytes and Urea in Nigerian ...

    African Journals Online (AJOL)

    Reference values for plasma electrolytes and urea have been defined for Nigerian children and adolescents residing in Abeokuta and its environs, a location in southern Nigeria, by estimating plasma sodium, potassium bicarbonate and urea concentrations in a reference population. The study group comprised three ...

  1. Preparation and characterization of dialdehyde starch urea (DASU ...

    African Journals Online (AJOL)

    Dialdehyde starch urea (DASU) was prepared by the reaction of dialdehyde starch (DAS) from periodate oxidized cassava starch with urea, which was then used to adsorb Co(II), Pb(II) and Zn(II) ions from aqueous solution. Starch modified starches and starch complexes were characterized by Fourier transform infrared ...

  2. Differences in nitrogen and urea metabolism between goats bred for ...

    African Journals Online (AJOL)

    and 38% to excretion; in Boer goats proportionately less was recycled (48%) and more was excreted (52%). (P < 0.01). Urea N ... is suggested that higher N retention and urea recycling could be an adaptative mechanism consequent to increasing the demand for .... Catheters (l mID ill 12 mID OD; Dural Plastics, Australia).

  3. Effects of low urea concentrations on protein-water interactions.

    Science.gov (United States)

    Ferreira, Luisa A; Povarova, Olga I; Stepanenko, Olga V; Sulatskaya, Anna I; Madeira, Pedro P; Kuznetsova, Irina M; Turoverov, Konstantin K; Uversky, Vladimir N; Zaslavsky, Boris Y

    2017-01-01

    Solvent properties of aqueous media (dipolarity/polarizability, hydrogen bond donor acidity, and hydrogen bond acceptor basicity) were measured in the coexisting phases of Dextran-PEG aqueous two-phase systems (ATPSs) containing .5 and 2.0 M urea. The differences between the electrostatic and hydrophobic properties of the phases in the ATPSs were quantified by analysis of partitioning of the homologous series of sodium salts of dinitrophenylated amino acids with aliphatic alkyl side chains. Furthermore, partitioning of eleven different proteins in the ATPSs was studied. The analysis of protein partition behavior in a set of ATPSs with protective osmolytes (sorbitol, sucrose, trehalose, and TMAO) at the concentration of .5 M, in osmolyte-free ATPS, and in ATPSs with .5 or 2.0 M urea in terms of the solvent properties of the phases was performed. The results show unambiguously that even at the urea concentration of .5 M, this denaturant affects partitioning of all proteins (except concanavalin A) through direct urea-protein interactions and via its effect on the solvent properties of the media. The direct urea-protein interactions seem to prevail over the urea effects on the solvent properties of water at the concentration of .5 M urea and appear to be completely dominant at 2.0 M urea concentration.

  4. Interaction between dietary content of protein and sodium chloride on milk urea concentration, urinary urea excretion, renal recycling of urea, and urea transfer to the gastrointestinal tract in dairy cows

    NARCIS (Netherlands)

    Spek, J.W.; Bannink, A.; Gort, G.; Hendriks, W.H.; Dijkstra, J.

    2013-01-01

    Dietary protein and salt affect the concentration of milk urea nitrogen (MUN; mg of N/dL) and the relationship between MUN and excretion of urea nitrogen in urine (UUN; g of N/d) of dairy cattle. The aim of the present study was to examine the effects of dietary protein and sodium chloride (NaCl)

  5. Hydrolyzable polyureas bearing hindered urea bonds.

    Science.gov (United States)

    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.

  6. A field diagnostic test for the improvised explosive urea nitrate.

    Science.gov (United States)

    Almog, Joseph; Klein, Asne; Tamiri, Tsippy; Shloosh, Yael; Abramovich-Bar, Sara

    2005-05-01

    A sensitive, specific and simple color test for the improvised explosive urea nitrate is described. It is based on the formation of a red pigment upon the reaction between urea nitrate and p-dimethylaminocinnamaldehyde (p-DMAC) under neutral conditions. Urea itself, which is the starting material for urea nitrate, does not react with p-DMAC under the same conditions. Other potential sources of false positive response e.g., common fertilizers, medications containing the urea moiety and various amines, do not produce the red pigment with p-DMAC. Exhibits collected from 10 terrorist cases have been tested with p-DMAC. The results were in full agreement with those obtained by instrumental techniques including GC/MS, XRD and IR.

  7. Autumn urea application and cold hardiness of apple trees

    Directory of Open Access Journals (Sweden)

    Beata Meszka

    2013-12-01

    Full Text Available Effect of autumn urea application on cold hardiness of apple trees was investigated at Experimental Orchard in Dąbrowice on four apple cultivars ('Szampioii'. ´Jonagold´, ´Elstar' and 'Spartan´ of different sensitivity to low temperature injuries. During three-years experiment (2000-2002 no changes in frost resistance of apple trees after urea treatment in the end of October (during leaves fall were noted. After the earlier application of urea, at middle of October. significantly more damages of annual shoots of cv. ´Jonagold' occurred only in the season 2001. These damages did not influence later growth of apple trees. Spring observations indicated that for all apple's cultivars setting of buds was better on treated with urea than on untreated ones. Electrolyte leakage determinations confirmed the field results that urea did not cause decrease in low temperature resistance of apple trees.

  8. SUGAR CANE ENSILED WITH SALT OR UREA

    Directory of Open Access Journals (Sweden)

    Hélio Henrique Vilela

    2014-07-01

    Full Text Available Sugar cane silage is widely used in livestock production. Nevertheless, it presents a drawback which is alcoholic fermentation caused by yeasts and which can reduce its nutritional value. In this sense, the aim of this work was to evaluate the use of either doses of salt or urea in the ensiling of sugar cane with the objective of producing silages of better quality. For this purpose, an experiment consisted of completely randomized design with seven treatments and three replications was performed. The treatments consisted of the ensiling of sugar cane without the use of additives (control and ensiling utilizing 0.5, 1.0 and 1.5% of either salt or urea. Sugar cane was ensiled with 31.8% of DM in experimental PVC silos, which remained closed for 202 days. After this period, the silos were opened and a part of the central silage of each silo was utilized for evaluation of potential of hydrogen (pH and of the percentages of dry matter (DM, for crude protein (CP, neutral detergent fiber (NDF, acid detergent fiber (ADF, lignin and hemicellulose. By utilizing the weights of the silos, the production of effluents was also computed. The data were submitted to the analysis of variance and the means compared by the Skott-Knott test at 5% de significance. The percentage of DM (29.5% and lignin (9.9% as well as the effluent production (43.8 kg/t of natural matter were not influenced (P>0.05 by the treatments. Increased pH values (P

  9. Determination of blood urea using cation exchange column solid phase extraction combined with HPLC

    National Research Council Canada - National Science Library

    Hideharu SHINTANI; Takashi INOUE

    1994-01-01

    ...°C with detection at 200 nm. By comparing ultrafiltrated blood urea and native blood urea, the blood urea from the HPLC chromatogram was found to be completely free of blood admixtures and almost free of blood protein...

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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......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...... 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...

  11. Performance of lactating crossbred cows on pasture supplemented with conventional urea or slow release urea

    Directory of Open Access Journals (Sweden)

    D.C. Abreu

    2014-10-01

    Full Text Available The effect of using conventional urea (CU or slow release urea (SRU was evaluated by replacing soybean meal (SBM in concentrated supplements in levels of 2, 4 or 6% (dry matter basis on productive performance of crossbred Holstein x Zebu lactating dairy cows (499±61kg body weight and 167 days of lactation grazing on elephant grass (11.5% CP and 60% NDF under rotational grazing during the rainy season. A supplement control (no urea was used containing SBM as a protein source. A total of 21 cows were distributed an incomplete randomized block design with three periods of 21 days each (14 days of adaptation and seven days of collection. The animals entered the paddocks with a pasture height of 110-120cm and left when the grass reached the height of 40-50cm. The concentrated isonitrogenous supplements (24% crude protein, dry matter basis were provided in the amount of 3.2kg/cow/day (fed basis. There was no effect (P>0.05 on source of crude protein (SBM vs source NPN, source NPN, level of NPN, interaction between source NPN and level of NPN on milk production (10.0kg/day, fat milk production corrected to 3.5% (10.7kg/day, levels of fat (4.01%, protein (3.66%, lactose (4.16%, total solids (12.86% and non-fat solids (8.60% in milk. The replacement of CU by SRU does not promote improvement in the productive performance of crossbred dairy cows grazing on elephant grass during the rainy season. Urea (CU or SRU can be included in up to 6% of the DM concentrated supplements, replacing SBM, without affecting the productive performance of crossbred cows (Holstein x Zebu in pasture during the rainy season.

  12. Metribuzin mobility in soil columns as affected by urea fertiliser.

    Science.gov (United States)

    Singh, Neera

    2006-05-01

    Application of urea fertilisers to soils influences the soil solution characteristics and thus may affect the sorption of soil-applied herbicides. The present investigation reports the influence of urea co-application on sorption and leaching of metribuzin, a triazine herbicide. Urea application at 60 and 120 kg N ha(-1) increased metribuzin sorption in soils over that in untreated natural soil. The Kf (Freundlich adsorption coefficient) values of metribuzin for natural, 60 and 120 kg N ha(-1) treatments were 0.43, 0.46 and 0.84 microg(1 - 1/n) g(-1) ml1/n respectively. Downward mobility of metribuzin was studied in packed soil columns (300 mm length x 59 mm i.d.) at two irrigation intensities, 720 m3 ha(-1) (72 mm) and 3600 m3 ha(-1) (360 mm). After 720 m3 ha(-1) irrigation, metribuzin did not leach out of any column and was not detected in the leachate. Urea amendment slowed the leaching of metribuzin by 20 and 40% in 60 and 120 kg N ha(-1) urea-treated columns respectively. Also, following urea application, greater amounts of metribuzin were retained in the application zone. Upon increasing the irrigation intensity fivefold, urea application did not have any effect on metribuzin mobility, and its breakthrough from both natural and urea-amended columns occurred after 126 mm irrigation. However, there was a marked difference in the maximum concentration of metribuzin in the breakthrough curves obtained from natural and urea-amended columns. The study indicated that co-application of metribuzin and urea fertiliser is a safe practice as far as leaching of herbicide is concerned. Copyright 2006 Society of Chemical Industry.

  13. HUBUNGAN KADAR UREA DENGAN HOMOCITRULINE PADA GAGAL GINJAL TERMINAL

    Directory of Open Access Journals (Sweden)

    Verbrini Rifnayeni

    2015-09-01

    Full Text Available AbstrakPeningkatan kadar urea (uremia ditemukan pada gagal ginjal terminal.Tujuan penelitian ini adalah untuk mengetahui hubungan kadar urea dengan homocitruline pada pasien gagal ginjal terminal. Penelitian ini menggunakan rancangan analitik observasional cross sectional pada 23 pasien gagal ginjal terminal yang menjalani Hemodialisis di RSUP. Dr. M. Djamil Padang. Penelitian berlangsung sejak Februari hingga Oktober 2014. Subjek diambil dengan consecutive sampling. Sampel serum diperiksa kadar ureanya dengan metode enzimatik glutamate dehidrogenase. Homocitruline diperiksa secara indirek ELISA. Analisis statistik menggunakan uji korelasi Pearson. Hasil penelitian ini menunjukkan jumlah subjek sebanyak 52,2% perempuan dan 47,8 % laki-laki, dengan rerata umur 48,6+10,6 tahun, kadar urea 102,1+26,0 mg/dL, kadar homocitruline 1,2+0,7 ng/mL. Penelitian ini menunjukan ada korelasi negatif yang tidak signifikan (r=-0.2, p > 0.05 antara kadar urea dengan homocitruline pada pasien gagal ginjal terminal.AbstractIncrease urea (uremia can be found at end stage renal disease. This study was know correlation between urea with homocitruline level at end stage renal disease. This is cross sectional observational analytic study at 23 patients with end stage renal disease on hemodyalisis in M. Djamil Hospital, Padang, from February 2014 until October 2014, with consecutive sampling. Urea level was determined from serum sample by kinetic enzymatic glutamate dehydrogenase, and homocitruline by indirect ELISA. Statistical analysis was done by pearson correlation. The research showed that 52.2% are women and 47.8% are men with mean age is 48.6+10.6 years old, mean urea level is 102.1+26.0 mg/dL, homocitruline level is 1.2+0.7 ng/mL. The correlation between urea level and homocitruline was not significant (r=-0.2, p > 0.05. There was negative weak correlation between urea level and homocitruline at end stage renal disease.

  14. Development of melamine modified urea formaldehyde resins based o nstrong acidic pH catalyzed urea formaldehyde polymer

    Science.gov (United States)

    Chung-Yun Hse

    2009-01-01

    To upgrade the performance of urea-formaldehyde (UF) resin bonded particleboards, melamine modified urea-formaldehyde (MUF) resins based on strong acidic pH catalyzed UF polymers were investigated. The study was conducted in a series of two experiments: 1) formulation of MUF resins based on a UF polymer catalyzed with strong acidic pH and 2) determination of the...

  15. Hardness evaluation of cured urea-formaldehyde resins with different formaldehyde/urea mole ratios using nanoindentation method

    Science.gov (United States)

    Byung-Dae Park; Charles R. Frihart; Yan Yu; Adya P. Singh

    2013-01-01

    To understand the influence of formaldehyde/urea (F/U) mole ratio on the properties of urea–formaldehyde (UF) resins, this study investigated hardness of cured UF resins with different F/U mole ratios using a nanoindentation method. The traditional Brinell hardness (HB) method was also used...

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

    NARCIS (Netherlands)

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

    2016-01-01

    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

  17. Dispersion Interactions between Urea and Nucleobases Contribute to the Destabilization of RNA by Urea in Aqueous Solution

    Science.gov (United States)

    Kasavajhala, Koushik; Bikkina, Swetha; Patil, Indrajit; MacKerell, Alexander D.; Priyakumar, U. Deva

    2015-01-01

    Urea has long been used to investigate protein folding and, more recently, RNA folding. Studies have proposed that urea denatures RNA by participating in stacking interactions and hydrogen bonds with nucleic acid bases. In this study, the ability of urea to form unconventional stacking interactions with RNA bases is investigated using ab initio calculations (RI-MP2 and CCSD(T) methods with the aug-cc-pVDZ basis set). A total of 29 stable nucleobase-urea stacked complexes are identified in which the intermolecular interaction energies (up to −14 kcal/mol) are dominated by dispersion effects. Natural bond orbital (NBO) and atoms in molecules (AIM) calculations further confirm strong interactions between urea and nucleobases. Calculations on model systems with multiple urea and water molecules interacting with a guanine base lead to a hypothesis that urea molecules along with water are able to form cage-like structures capable of trapping nucleic acid bases in extrahelical states by forming both hydrogen bonded and dispersion interactions, thereby contributing to the unfolding of RNA in the presence of urea in aqueous solution. PMID:25668757

  18. A review of factors influencing milk urea concentration and its relationship with urinary urea excretion in lactating dairy cattle

    NARCIS (Netherlands)

    Spek, J.W.; Dijkstra, J.; Duinkerken, van G.; Bannink, A.

    2013-01-01

    Milk urea nitrogen (MUN) concentration in dairy cows may serve as an on-farm indicator to guide nutritional strategies and to help reduce emissions of nitrogen (N) to the environment. Excretion of urinary urea nitrogen (UUN) is positively related to MUN, but the relationship is highly variable. The

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

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhifang; Wan, Yizao [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Xiong, Guangyao [School of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang, Jiangxi 330013 (China); Guo, Ruisong [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Luo, Honglin, E-mail: hlluo@tju.edu.cn [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2013-09-01

    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 Al{sub 2}O{sub 3} 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.

  20. Dissolution of lignin in green urea aqueous solution

    Science.gov (United States)

    Wang, Jingyu; Li, Ying; Qiu, Xueqing; Liu, Di; Yang, Dongjie; Liu, Weifeng; Qian, Yong

    2017-12-01

    The dissolution problem is the main obstacle for the value-added modification and depolymerization of industrial lignin. Here, a green urea aqueous solution for complete dissolution of various lignin is presented and the dissolution mechanism is analyzed by AFM, DLS and NMR. The results show that the molecular interaction of lignin decreases from 32.3 mN/m in pure water to 11.3 mN/m in urea aqueous solution. The immobility of 1H NMR spectra and the shift of 17O NMR spectra of urea in different lignin/urea solutions indicate that the oxygen of carbonyl in urea and the hydrogen of hydroxyl in lignin form new hydrogen bonds and break the original hydrogen bonds among lignin molecules. The shift of 1H NMR spectra of lignin and the decrease of interactions in model compound polystyrene indicate that urea also breaks the π-π interactions between aromatic rings of lignin. Lignin dissolved in urea aqueous has good antioxidant activity and it can scavenge at least 63% free radicals in 16 min.

  1. Effect of urea on protein-ligand association.

    Science.gov (United States)

    Stepanian, Lora; Son, Ikbae; Chalikian, Tigran V

    2017-12-01

    We combine experimental and theoretical approaches to investigate the influence of a cosolvent on a ligand-protein association event. We apply fluorescence measurements to determining the affinity of the inhibitor tri-N-acetylglucosamine [(GlcNAc)3] for lysozyme at urea concentrations ranging from 0 to 8M. Notwithstanding that, at room temperature and neutral pH, lysozyme retains its native conformation up to the solubility limit of urea, the affinity of (GlcNAc)3 for the protein steadily decreases as the concentration of urea increases. We analyze the urea dependence of the binding free energy within the framework of a simplified statistical thermodynamics-based model that accounts for the excluded volume effect and direct solute-solvent interactions. The analysis reveals that the detrimental action of urea on the inhibitor-lysozyme binding originates from competition between the free energy contributions of the excluded volume effect and direct solute-solvent interactions. The free energy contribution of direct urea-solute interactions narrowly overcomes the excluded volume contribution thereby resulting in urea weakening the protein-ligand association. More broadly, the successful application of the simple model employed in this work points to the possibility of its use in quantifying the stabilizing/destabilizing action of individual cosolvents on biochemical folding and binding reactions. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Urea encapsulation in modified starch matrix for nutrients retention

    Science.gov (United States)

    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.

  3. Urea-Hydroxyapatite Nanohybrids for Slow Release of Nitrogen.

    Science.gov (United States)

    Kottegoda, Nilwala; Sandaruwan, Chanaka; Priyadarshana, Gayan; Siriwardhana, Asitha; Rathnayake, Upendra A; Berugoda Arachchige, Danushka Madushanka; Kumarasinghe, Asurusinghe R; Dahanayake, Damayanthi; Karunaratne, Veranja; Amaratunga, Gehan A J

    2017-02-28

    While slow release of chemicals has been widely applied for drug delivery, little work has been done on using this general nanotechnology-based principle for delivering nutrients to crops. In developing countries, the cost of fertilizers can be significant and is often the limiting factor for food supply. Thus, it is important to develop technologies that minimize the cost of fertilizers through efficient and targeted delivery. Urea is a rich source of nitrogen and therefore a commonly used fertilizer. We focus our work on the synthesis of environmentally benign nanoparticles carrying urea as the crop nutrient that can be released in a programmed manner for use as a nanofertilizer. In this study, the high solubility of urea molecules has been reduced by incorporating it into a matrix of hydroxyapatite nanoparticles. Hydroxyapatite nanoparticles have been selected due to their excellent biocompatibility while acting as a rich phosphorus source. In addition, the high surface area offered by nanoparticles allows binding of a large amount of urea molecules. The method reported here is simple and scalable, allowing the synthesis of a urea-modified hydroxyapatite nanohybrid as fertilizer having a ratio of urea to hydroxyapatite of 6:1 by weight. Specifically, a nanohybrid suspension was synthesized by in situ coating of hydroxyapatite with urea at the nanoscale. In addition to the stabilization imparted due to the high surface area to volume ratio of the nanoparticles, supplementary stabilization leading to high loading of urea was provided by flash drying the suspension to obtain a solid nanohybrid. This nanohybrid with a nitrogen weight of 40% provides a platform for its slow release. Its potential application in agriculture to maintain yield and reduce the amount of urea used is demonstrated.

  4. The Effects of Acid Activation on the Thermal Properties of Polyvinylpyrrolidone and Organoclay Composites

    Directory of Open Access Journals (Sweden)

    F. Kooli

    2015-01-01

    Full Text Available The thermal stabilities of polyvinylpyrrolidone-organoclays or organo-acid-activated clay composites prepared by chemical exchange reactions were assessed. The raw clay mineral was acid-activated prior to expansion by cetyltrimethylammonium surfactants. The acid activation process affected the intercalated amount of cetyltrimethylammonium cations in the resulting organoclays and, thus, the amount of polyvinylpyrrolidone in the composite. The content of cetyltrimethylammonium cations decreased with the extent of acid activation. The organophilic modification of the clay mineral was an important step in the intercalation of the polyvinylpyrrolidone molecules and, thus, in the expansion of the silicate sheets from 3.80 nm to 4.20 nm. The composites exhibited better crystalline order with intense reflections at lower angles. The thermal stability of organoclays, acid-activated clays, and composites was studied using thermogravimetric analysis and in situ X-ray diffraction. The decomposition of intercalated surfactants occurred at lower temperatures relative to the neat surfactant salt, and the basal spacing of the organoclays (or acid-activated clays shrunk to 2.0 nm at 215°C. However, the basal spacing of composites exhibited better stability and collapsed to 2.0 nm at 300°C. This type of material could offer an alternative stable product for engineering purposes in the design of new composites.

  5. Agronomic and Nitrate Leaching Impacts of Pelletized versus Granular Urea

    OpenAIRE

    Shah, Sanjay Bikram

    2000-01-01

    Agronomic and water quality impacts of urea particle size were evaluated through field and laboratory experiments and mathematical modeling. In a two-year field study, corn silage yield, corn nitrogen (N) removal, and nitrate-N (N03-N) leaching from urea pellets (1.5 g each) and granules (0.01-0.02 g each) applied at 184 kg-N/ha were compared. A control treatment (no N) and two other N application rates (110 and 258 kg-N/ha) were also included. Urea particle size impact on dissolution rate...

  6. Quantum crystallographic charge density of urea

    Directory of Open Access Journals (Sweden)

    Michael E. Wall

    2016-07-01

    Full Text Available Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement.

  7. Mechanochemical synthesis of thioureas, ureas and guanidines

    Directory of Open Access Journals (Sweden)

    Vjekoslav Štrukil

    2017-09-01

    Full Text Available In this review, the recent progress in the synthesis of ureas, thioureas and guanidines by solid-state mechanochemical ball milling is highlighted. While the literature is abundant on their preparation in conventional solution environment, it was not until the advent of solvent-free manual grinding using a mortar and pestle and automated ball milling that new synthetic opportunities have opened. The mechanochemical approach not only has enabled the quantitative synthesis of (thioureas and guanidines without using bulk solvents and the generation of byproducts, but it has also been established as a means to develop "click-type" chemistry for these classes of compounds and the concept of small molecule desymmetrization. Moreover, mechanochemistry has been demonstrated as an effective tool in reaction discovery, with emphasis on the reactivity differences in solution and in the solid state. These three classes of organic compounds share some structural features which are reflected in their physical and chemical properties, important for application as organocatalysts and sensors. On the other hand, the specific and unique nature of each of these functionalities render (thioureas and guanidines as the key constituents of pharmaceuticals and other biologically active compounds.

  8. Citrulline for urea cycle disorders in Japan.

    Science.gov (United States)

    Tanaka, Kenichi; Nakamura, Kimitoshi; Matsumoto, Shirou; Kido, Jun; Mitsubuchi, Hiroshi; Ohura, Toshihiro; Endo, Fumio

    2017-04-01

    The amino acid l-citrulline is used as a therapeutic agent for urea cycle disorders (UCD) including ornithine transcarbamylase deficiency (OTCD), carbamoyl phosphate synthetase I deficiency (CPSD), and N-acetylglutamate synthase deficiency. There are few reports, however, on the use of l-citrulline in Japan and little consensus regarding the effects of l-citrulline. We conducted a questionnaire survey of patients undergoing l-citrulline treatment for a UCD to evaluate the current status of this therapy. The survey included patient background, details of l-citrulline treatment, clinical examination data, treatment, frequency of vomiting, and liver transplantation. We retrospectively investigated 43 questionnaire respondents (OTCD, n = 33; CPSD, n = 10). The weight of male OTCD patients improved by +0.79 SD, and the ammonia level decreased by a mean of 44.3 μmol/L in all patients. The protein intake of all patients and of male OTCD patients increased by 0.14 g/kg/day and 0.17 g/kg/day, respectively. l-Citrulline effectively reduced ammonia level, increased protein intake, and improved weight gain in UCD patients. l-Citrulline should be considered a standard therapy in OTCD and CPSD patients. © 2016 Japan Pediatric Society.

  9. The role of H bonding and dipole-dipole interactions on the electrical polarizations and charge mobilities in linear arrays of urea, thiourea, and their derivatives

    Science.gov (United States)

    Pal, Shrinwantu; Manna, Arun K.; Pati, Swapan K.

    2008-11-01

    Computational studies using density functional theory are carried out on linear chains of urea, N,N'-dimethyl urea and N,N,N',N'-tetramethyl urea, and their sulfur analogs, viz., thiourea, N,N'-dimethyl thiourea and N,N,N',N'-tetramethyl thiourea with varying chain length, to understand the effect of hydrogen bonding and dipolar interactions on the optoelectronic response properties of such linear aggregates. While molecules of urea, N,N'-dimethyl urea, and the corresponding sulfur analogs, thiourea, N,N'-dimethyl thiourea, are stabilized in linear chains by hydrogen bonding, the molecules of N,N,N',N'-tetramethyl urea and N,N,N',N'-tetramethyl thiourea in the linear chains are stabilized by purely dipolar interactions. To understand the contributions of electrostatic and polarization effects on such intermolecular interactions, we study the effect of an external electric field on the intermolecular interactions in these systems. We find that the strength of hydrogen bonding increases while that of dipolar interactions decreases with increase in external field strength. We account for such findings by decomposing the interaction terms into charge-transfer and electrostatic interaction terms. The effects of these interactions on the linear and nonlinear optical properties together with transport properties such as carrier mobilities are estimated to understand their suitability for device applications.

  10. RESPONSE OF POPCORN (ZEA MAYS SSP. EVERTA L.) TO UREA AND SULFUR FERTILIZER AS WELL AS FOLIAR UREA APPLICATION

    OpenAIRE

    Ali Husain JASIM; Muna Muhammad GHANEE

    2016-01-01

    A field experiment was carried out in private field (Abu-Garaq, 10 km west of Hilla city) during the autumn season of 2014 in silt clay loam soil, to study the response of popcorn to spraying urea under different soil fertilization levels of urea and agricultural sulfur. Split – split blot design in randomized complete blocks design (RCBD) in three replications was used. The factors were: soil fertilizer with urea (0, 100 and 200 kg ha-1) which were given symbols (U0, U100 and U200) respectiv...

  11. New biomedical polyurethane ureas with high tear strengths

    NARCIS (Netherlands)

    deGroot, JH; deVrijer, R; Wildeboer, BS; Spaans, CS; Pennings, AJ

    Biodegradable polyurethanes ureas (PUU) were synthesized by a two step polymerization. First a poly (epsilon-caprolactone) prepolymer was terminated with three different diisocyanates: lysinediisocyanate (LDI), 1,6-hexanediisocyanate (HDI) and 1,4-butanediisocyanate (BDI). Second the prepolymers

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

    National Research Council Canada - National Science Library

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

    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...

  13. Improvement of Egyptian vacuum distillates by urea dewaxing

    National Research Council Canada - National Science Library

    Nassef, Ehssan M.R; Salah, Hesham S

    2015-01-01

    .... The effect of different compositions of methanol to water saturated with urea and yield of the oil, percent of wax, pour point, refractive index, viscosity, viscosity index and specific gravity...

  14. Deprotection of oximes using urea nitrate under microwave irradiation

    Indian Academy of Sciences (India)

    Abstract. 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.

  15. Influence of Ficoll on urea induced denaturation of fibrinogen

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Dietmar, E-mail: fink@daad-alumni.de [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 Rez (Czech Republic); Munoz Hernandez, Gerardo [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Division de Ciencias Naturales e Ingenieria, Universidad Autonoma Metropolitana-Cuajimalpa, Pedro Antonio de los Santos 84, Col. Sn. Miguel Chapultepec, C.P. 11850, Mexico, D.F. (Mexico); Alfonta, Lital, E-mail: alfontal@bgu.ac.il [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2012-02-15

    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.

  17. Reinvestigation of growth of thiourea urea zinc sulfate crystal.

    Science.gov (United States)

    Srinivasan, Bikshandarkoil R; Naik, Teja A; Tylczyński, Zbigniew; Priolkar, K R

    2014-01-03

    Reinvestigation of the growth of thiourea urea zinc sulfate crystal is reported. Aqueous reaction of thiourea, urea and zinc sulfate in 1:1:1 mol ratio results in the formation of the well known [Zn(tu)3(SO4)] (1) (tu=thiourea) crystal and not the 'so called' novel semiorganic nonlinear optical thiourea urea zinc sulfate (2) crystal, as claimed by Redrothu Hanumantha Rao, S. Kalainathan, Spectroscopic investigation, nucleation, growth, optical, thermal and second harmonic studies of novel semi-organic nonlinear optical crystal - Thiourea urea zinc sulfate, Spectrochim. Acta A97 (2012) 456-463. In this work, we demonstrate the usefulness of elemental analytical data, infrared and NMR spectra and X-ray powder pattern, for accurate product characterization. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Serum urea and creatinine levels in Nigerian human malaria patients

    African Journals Online (AJOL)

    Serum urea and creatinine levels were determined in malaria patients infected with P. falciparum. Serum urea levels decreased significantly (P<0.05) in both mild (4.10 ±1.10 mmol/L) and moderate (4.40 ±1.40 mmol/L) parasitaemia when compared to control subjects (5.50 ±1.40 mmol/L). On the other hand, serum ...

  19. INHIBITION OF SWARMING BY UREA AND ITS DIAGNOSTIC ...

    African Journals Online (AJOL)

    The anti-swarming property of urea and effects on antibiotic susceptibility among 52 uropathogenic Proteus strains from Lagos, Nigeria were investigated. Urea caused a reduction in swarming and number of swarmed cells at 0.5% (n = 42, DOCZ = 15.5mm), 0.75% (n= 24, DOCZ = 10.7mm), 1% (n = 17, DOCZ = 3.4mm) and ...

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Analysis of the Sub-Millimeter Rotational Spectrum of Urea

    Science.gov (United States)

    Thomas, Jessica R.; Fosnight, Alyssa M.; Medvedev, Ivan R.

    2013-06-01

    Urea, ((NH_{2})_{2}CO), has broad presence in biological species. As a byproduct of human metabolism, this molecule is commonly tested for in blood to diagnose different pathologies. Furthermore, urea is seen in interstellar medium and its detection could yield valuable insight into the mechanisms governing star formation. Despite the prevalence of urea, an absence exists in recorded frequencies of this molecule. The new generation of the sub-millimeter telescopes, such as ALMA, HERSCHEL, and SOFIA, allows detection of interstellar molecular spectra at unprecedented spatial and spectral resolutions. The knowledge of the precise frequencies of spectra transitions present in interstellar molecular clouds would alleviate the problem of spectral congestion and aid in molecular identification. This paper reports the most recent investigation of the submillimeter/terahertz gas phase spectrum of urea. Up until now, only the microwave laboratory spectrum of urea's vibrational ground state has been available. This paper reports the high-resolution spectra of urea in the sub-millimeter range, and extends the spectroscopic assignment of the rotational transitions in the vibrational ground state. Additionally, the assignment of the first vibrational state and tentative assignments of two additional vibrational states have been made.

  2. Characterization of the decomposition of compounds derived from imidazolidinyl urea in cosmetics and patch test materials.

    Science.gov (United States)

    Doi, Takahiro; Takeda, Akihiro; Asada, Akiko; Kajimura, Keiji

    2012-11-01

    Imidazolidinyl urea releases formaldehyde through decomposition. However, there have been few reports on the chemistry of imidazolidinyl urea in cosmetics. The aim of this study was to characterize imidazolidinyl urea-derived compounds in cosmetics and to determine which compounds are responsible for the cross-reactivity with diazolidinyl urea. We analysed imidazolidinyl urea dissolved in aqueous solutions, imidazolidinyl urea patch test materials and imidazolidinyl urea-preserved cosmetics by high-performance liquid chromatography/photodiode array detection and liquid chromatography/mass spectrometry. The results were compared with those obtained with a diazolidinyl urea aqueous solution. In the analysed cosmetic samples and patch test materials, imidazolidinyl urea was primarily composed of allantoin, (4-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (HU), (3,4-bis-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea (3,4-BHU), and (3-hydroxymethyl-2,5-dioxo-imidazolidine-4-yl)-urea. Two of the imidazolidinyl urea-derived major decomposition compounds - HU and 3,4-BHU - are common in the diazolidinyl urea-decomposed compound present in cosmetics. These compounds are possible causative agents of the cross-reactivity between diazolidinyl urea and imidazolidinyl urea. © 2012 John Wiley & Sons A/S.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    of 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...

  4. Pengaruh Suplementasi Baking Soda dalam Pakan terhadap Urea Darah dan Urea Susu Sapi Perah Laktasi

    Directory of Open Access Journals (Sweden)

    W. A. Harjanti

    2017-06-01

    Full Text Available The aim of the research was to assess the effect of suplementation of sodium bicarbonate in feed rations on the concentration of Blood Urea Nitrogen (BUN and Milk Urea Nitrogen (MUN of lactating dairy cattle. The materials used were 12 lactating Friesian Holstein cattle in the 1th lactation period and the month lactation of 5 and 6th. The experiment used a completely randomized design with 3 treatments and 4 replications. The experimental treatmens were basal ration (T0, and basal ration supplemented with 0,8 % (T0 and 1 % (T2 of sodium bicarbonate, on a dry matter (DM basis. The parameters determined were crude protein intake (CPI and the concentration of BUN and MUN. The data were analyzed using variance the F-test. The result showed that the CPI, and the concentration of BUN and MUN were not affected by the treatments. The CPI were 2.097,43 ; 2.079,19 and 2.053,17 g/d. The concentration of BUN were 14,04 ; 13,05 and 12,75 mg/dl, whereas the concentration of MUN were 12,43 ; 10,01 and 10,07 mg/dl for T0, T1 dan T2 respectively. Overall, 0,8 and 1% of sodium bicarbonate supplementations into feed ration was not found to significantly alter the quantity of crude protein intake and the concentration of BUN and MUN in lactating dairy cattle in the present study.

  5. Effect of sodium chloride intake on urine volume, urinary urea excretion, and milk urea concentration in lactating dairy cattle

    NARCIS (Netherlands)

    Spek, J.W.; Bannink, A.; Gort, G.; Hendriks, W.H.; Dijkstra, J.

    2012-01-01

    Milk urea nitrogen (MUN; mg of N/dL) has been shown to be related to excretion of urinary urea N (UUN; g of N/d) and total excretion of urinary N (UN; g of N/d) in dairy cows. In the present experiment, it was hypothesized that MUN and the relationship between MUN and UUN or UN is affected by urine

  6. Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

    OpenAIRE

    Latifah Omar; Osumanu Haruna Ahmed; Nik Muhamad Ab Majid

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 ? leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 + and NO3 ? release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 + and NO3 ? losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leachi...

  7. Kinetic and equilibrium studies of urea adsorption onto activated carbon: Adsorption mechanism

    OpenAIRE

    Kameda, Tomohito; Ito, Saya; Yoshioka, Toshiaki

    2017-01-01

    We found that activated carbon effectively removed urea from solution and that urea adsorption onto activated carbon followed a pseudo-second-order kinetic model. We classified the urea adsorption on activated carbon as physical adsorption and found that it was best described by the Halsey adsorption isotherm, suggesting that the multilayer adsorption of urea molecules on the adsorption sites of activated carbon best characterized the adsorption system. The mechanism of adsorption of urea by ...

  8. In vivo evaluation of two forms of urea in the skin by Raman spectroscopy after application of urea-containing cream.

    Science.gov (United States)

    Egawa, M; Sato, Y

    2015-08-01

    As urea is one of the natural moisturizing factor (NMF) components in the stratum corneum, it has been used in topical products to improve skin conditions. However, the penetration behavior of urea in the skin after application of urea-containing cream has not been determined as there has been no technique with which to measure the urea content in the skin in vivo non-invasively. We therefore applied Raman spectroscopy to evaluate the depth profile of urea content in the skin. We investigated changes in depth profiles of two forms of urea to evaluate the penetration behavior of urea after application of urea-containing cream. Commercially available moisturizing creams F and R in quantities of 2.2-mg/cm(2) and containing 20% (w/w) urea were applied to volar forearm skin of six Japanese subjects. Raman spectra of the skin were measured at 2-μm intervals from the skin surface toward the interior using a confocal Raman spectrometer (model 3510 SCA) before and 15, 60, and 120 min after the application of the creams. The amounts of the two forms of urea, urea in water solution and urea in a solid state, were calculated by adding the spectra of solid urea and the cream base to a previously reported algorithm including the spectrum of urea in water solution. The characteristic band of urea in water solution was observed at approximately 1004/cm and that of the solid state at approximately 1010/cm in the Raman spectra of the skin after application of either cream. There was more urea in water solution form in the area where cream F was applied than in the area where cream R was applied. There was more urea in a solid state in the area where cream R was applied than in the area where cream F was applied at all depths and measurement times. In particular, there was significantly more urea in a solid state below a depth of 2 μm in the area where cream R was applied than in the area where cream F was applied 15 min after application. The present study demonstrated that we can

  9. Minimal sampling protocol for accurate estimation of urea production: a study with oral [13C]urea in fed and fasted piglets

    NARCIS (Netherlands)

    Oosterveld, Michiel J. S.; Gemke, Reinoud J. B. J.; Dainty, Jack R.; Kulik, Willem; Jakobs, Cornelis; de Meer, Kees

    2005-01-01

    An oral [13C]urea protocol may provide a simple method for measurement of urea production. The validity of single pool calculations in relation to a reduced sampling protocol was assessed. In eight fed and five fasted piglets, plasma urea enrichments from a 10 h sampling protocol were measured

  10. Milk urea concentration in Holstein and Simmental cows

    Directory of Open Access Journals (Sweden)

    Darija Bendelja

    2011-03-01

    Full Text Available Determining the urea concentration in milk is a useful indicator of the nutritional protein status of the organism as well as of the ratio between the energy and the protein in ruminant rations, with increasing practical usage. In addition to nutrition, milk urea concentration is influenced by a whole range of factors, for example: breed, stage and number of lactations, body weight, daily production and chemical composition of milk, somatic cell count, season and milking. The objective of this research was to determine the impact of the cow breed (Holstein and Simmental, the number of lactation (1st, 2nd, 3rd, 4th, 5th, milking time (morning-evening and season (spring-summer and autumn-winter on milk urea concentration. The following was determined for each breed: daily milk yield, milk fat, protein and lactose content, urea concentration and somatic cell count in milk. Statistical data processing was carried out by applying General Linear Model procedure, SAS system (1999. The cow breed had a significant influence on daily milk yield and log somatic cell count (P<0.001, lactose content in milk (P<0.01, milk fat content and milk urea concentration (P<0.05. The number of lactations significantly influenced daily milk yield (P<0.001, protein content (P<0.001 and P<0.01 and milk urea concentration, but only for Holstein breed (P<0.05. Milking time significantly influenced the fat and protein content (P<0.001 in the milk of Holstein cows, that is, lactose content (P<0.05 and urea concentration (P<0.05 in the milk of Simmental cows. The season significantly influenced the fat and protein content of milk (P<0.001, that is, urea concentration and log somatic cell count (P<0.01. Determining of urea concentration in cow milk should also be systematically conducted in the Republic of Croatia, in order to determine standard physiological values characteristical for a particular cow breed, aiming to determine the balance of energy and protein in rations.

  11. The regulation of urea-biosynthesis enzymes in vertebrates

    Science.gov (United States)

    Mora, J.; Martuscelli, J.; Ortiz-Pineda, Juana; Soberón, G.

    1965-01-01

    1. Carbamoyl phosphate synthetase, ornithine transcarbamoylase, the arginine-synthetase system and arginase were measured in the livers of ammoniotelic, ureotelic and uricotelic animals. The chelonian reptiles, whose nitrogen excretory patterns vary according to the habitat, and the Mexican axolotl, a neotenic species, were also studied. 2. The levels of the activities of the first three enzymes mentioned correlate with the amount of nitrogen excreted as urea. 3. The terrestrial turtle, which excretes mainly uric acid, maintains a high arginase activity but has very low levels of the activities of the other three enzymes. 4. The first three enzymes of the urea cycle vary in the phylogenic scale in a co-ordinated manner, which suggests that they are under the same regulatory mechanism. 5. Urea formation from endogenous arginine in vitro has a low efficiency in the Mexican axolotl. 6. The induction of metamorphosis in the Mexican axolotl by the administration of l-tri-iodothyronine, which causes a shift from ammonio-ureotelism to complete ureotelism, is accompanied by an increase mainly in carbamoyl phosphate synthetase and also by an improvement in the efficiency of hydrolysis of endogenous arginine in vitro to give urea. 7. The results obtained by differential centrifugation of the urea-cycle enzymes in rat and Mexican-axolotl livers are presented. The location requirements for the integration of a metabolic cycle are discussed. PMID:14343146

  12. Porous Cross-Linked Polyimide-Urea Networks

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Nguyen, Baochau N. (Inventor)

    2015-01-01

    Porous cross-linked polyimide-urea networks are provided. The networks comprise a subunit comprising two anhydride end-capped polyamic acid oligomers in direct connection via a urea linkage. The oligomers (a) each comprise a repeating unit of a dianhydride and a diamine and a terminal anhydride group and (b) are formulated with 2 to 15 of the repeating units. The subunit was formed by reaction of the diamine and a diisocyanate to form a diamine-urea linkage-diamine group, followed by reaction of the diamine-urea linkage-diamine group with the dianhydride and the diamine to form the subunit. The subunit has been cross-linked via a cross-linking agent, comprising three or more amine groups, at a balanced stoichiometry of the amine groups to the terminal anhydride groups. The subunit has been chemically imidized to yield the porous cross-linked polyimide-urea network. Also provided are wet gels, aerogels, and thin films comprising the networks, and methods of making the networks.

  13. THE TEMPERATURE COEFFICIENT OF THE UREA DENATURATION OF EGG ALBUMIN.

    Science.gov (United States)

    Clark, J H

    1945-07-20

    Evidence is brought forward to show that at concentrations of urea high enough to split the egg albumin molecule the solubility changes produced by urea are profoundly modified. The degree of precipitation after dialysis is the net result of two changes produced by the urea: the first, normally spoken of as denaturation, which makes the protein insoluble in dilute solution and the second, a splitting of the molecule which makes it soluble. These two reactions may proceed independently and simultaneously or the second reaction may follow the first, taking place in the denatured molecule only. In view of the decrease in the opalescence with time, the latter process is more probable. Both of these reactions have positive temperature coefficients, but as the concentration of urea increases the second reaction is more affected by increase in temperature than the first, and consequently the resulting opalescence decreases rather than increases with temperature. This accounts for and explains reports of negative temperature coefficients of denaturation, when denaturation is measured by the amount of insoluble material found on dilution. The occurrence of these two reactions, one leading to an increase and the other to a decrease in the amount of insoluble protein, should be taken into account when denaturation changes in egg albumin with urea are studied.

  14. Urea enhances cell lysis of Schizosaccharomyces pombe ura4 mutants.

    Science.gov (United States)

    Nishino, Kohei; Kushima, Misaki; Kaino, Tomohiro; Matsuo, Yasuhiro; Kawamukai, Makoto

    2017-07-01

    Cell lysis is induced in Schizosaccharomyces pombe ∆ura4 cells grown in YPD medium, which contains yeast extract, polypeptone, and glucose. To identify the medium components that induce cell lysis, we first tested various kinds of yeast extracts from different suppliers. Cell lysis of ∆ura4 cells on YE medium was observed when yeast extracts from OXOID, BD, Oriental, and Difco were used, but not when using yeast extract from Kyokuto. To determine which compounds induced cell lysis, we subjected yeast extract and polypeptone to GC-MS analysis. Ten kinds of compounds were detected in OXOID and BD yeast extracts, but not in Kyokuto yeast extract. Among them was urea, which was also present in polypeptone, and it clearly induced cell lysis. Deletion of the ure2 gene, which is responsible for utilizing urea, abolished the lytic effect of urea. The effect of urea was suppressed by deletion of pub1, and a similar phenotype was observed in the presence of polypeptone. Thus, urea is an inducer of cell lysis in S. pombe ∆ura4 cells.

  15. Hydrotropic Solubilization by Urea Derivatives: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2013-01-01

    Full Text Available Hydrotropy is a phenomenon where the presence of a large quantity of one solute enhances the solubility of another solute. The mechanism of this phenomenon remains a topic of debate. This study employed molecular dynamics simulation to investigate the hydrotropic mechanism of a series of urea derivatives, that is, urea (UR, methylurea (MU, ethylurea (EU, and butylurea (BU. A poorly water-soluble compound, nifedipine (NF, was used as the model solute that was solubilized. Structural, dynamic, and energetic changes upon equilibration were analyzed to supply insights to the solubilization mechanism. The study demonstrated that NF and urea derivatives underwent significant nonstoichiometric molecular aggregation in the aqueous solution, a result consistent with the self-aggregation of urea derivatives under the same conditions. The analysis of hydrogen bonding and energy changes revealed that the aggregation was driven by the partial restoration of normal water structure. The energetic data also suggested that the promoted solubilization of NF is favored in the presence of urea derivatives. While the solutes aggregated to a varying degree, the systems were still in single-phase liquid state as attested by their active dynamics.

  16. Urea cycle disorders: brain MRI and neurological outcome

    Energy Technology Data Exchange (ETDEWEB)

    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.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Improving ammonium and nitrate release from urea using clinoptilolite zeolite and compost produced from agricultural wastes.

    Science.gov (United States)

    Omar, Latifah; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 (-) leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 (+) and NO3 (-) release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 (+) and NO3 (-) losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4 (+) and NO3 (-) release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3 (-) leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4 (+) retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4 (+) and NO3 (-) release from urea.

  19. Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

    Directory of Open Access Journals (Sweden)

    Latifah Omar

    2015-01-01

    Full Text Available Improper use of urea may cause environmental pollution through NH3 volatilization and NO3- leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4+ and NO3- release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4+ and NO3- losses from urea. Bekenu Series soil (Typic Paleudults was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4+ and NO3- release from urea (soil incubation study compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3- leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4+ retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4+ and NO3- release from urea.

  20. Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

    Science.gov (United States)

    Omar, Latifah; Ahmed, Osumanu Haruna; Majid, Nik Muhamad Ab.

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 − leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 + and NO3 − release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 + and NO3 − losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4 + and NO3 − release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3 − leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4 + retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4 + and NO3 − release from urea. PMID:25793220

  1. Gastric Na+K+ATPase activity and intestinal urea hydrolysis of the common vampire bat, Desmodus rotundus.

    Science.gov (United States)

    Harlow, H J; Braun, E J

    1997-11-01

    The blood diet of the vampire bat represents an extraordinarily high ratio of protein to other nutrients and the highest water consumption per body weight of any other mammal. This bat has a unique gastrointestinal morphology that is characterized by a reduced small intestine, absence of a large intestine and intestinal cecum and the presence of a water-absorptive gastric fundus. The present study demonstrates that the gastric fundus has a greater Na+K+ATPase activity for active ion transport compared with other equally sized mammals. This activity is believed to be necessary to establish a gradient favoring water absorption across what would otherwise be an osmotic disequilibrium. The absence of a large intestine and intestinal cecum may reflect a reduced urea hydrolysis by the vampire bat. The present study demonstrated that the vampire bat does not hydrolyze urea as does an equally sized non-sanguinivorous mammal. These data suggest that the blood diet and the relocation of water-absorptive tissue from the lower intestinal tract to the stomach is associated with an active ion transport mechanism in the gastric tissue and a reduced capacity for ureolytic microbes to hydrolyze urea in the intestine. Both processes are specializations for a diet high in protein and water.

  2. Distributions of imidacloprid, imidacloprid-olefin and imidacloprid-urea in green plant tissues and roots of rapeseed (Brassica napus) from artificially contaminated potting soil.

    Science.gov (United States)

    Seifrtova, Marcela; Halesova, Tatana; Sulcova, Klara; Riddellova, Katerina; Erban, Tomas

    2017-05-01

    Imidacloprid-urea is the primary imidacloprid soil metabolite, whereas imidacloprid-olefin is the main plant-relevant metabolite and is more toxic to insects than imidacloprid. We artificially contaminated potting soil and used quantitative UHPLC-QqQ-MS/MS to determine the imidacloprid, imidacloprid-olefin and imidacloprid-urea distributions in rapeseed green plant tissues and roots after 4 weeks of exposure. In soil, the imidacloprid/imidacloprid-urea molar ratios decreased similarly after the 250 and 2500 µg kg-1 imidacloprid treatments. The imidacloprid/imidacloprid-urea molar ratios in the root and soil were similar, whereas in the green plant tissue, imidacloprid-urea increased more than twofold compared with the root. Although imidacloprid-olefin was prevalent in the green plant tissues, with imidacloprid/imidacloprid-olefin molar ratios of 2.24 and 1.47 for the 250 and 2500 µg kg-1 treatments respectively, it was not detected in the root. However, imidacloprid-olefin was detected in the soil after the 2500 µg kg-1 imidacloprid treatment. Significant proportions of imidacloprid-olefin and imidacloprid-urea in green plant tissues were demonstrated. The greater imidacloprid supply increased the imidacloprid-olefin/imidacloprid molar ratio in the green plant tissues. The absence of imidacloprid-olefin in the root excluded its retransport from leaves. The similar imidacloprid/imidacloprid-urea ratios in the soil and root indicated that the root serves primarily for transporting these substances. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  3. TREATMENT OF IMPETIGO WITH SULFONAMIDE-UREA POWDER

    Science.gov (United States)

    Rees, Rees B.; Hamlin, Edwin M.; McGinley, James P.

    1952-01-01

    Sulfonamides can be used in the treatment of impetigo with vastly increased safety and with more effectiveness in powder rather than ointment form when combined with urea powder in a ratio of approximately three parts of sulfonamide to one of urea. Of 701 patients treated with such a mixture, 95.6 per cent were cured within a week. The only complication was local dermatitis which occurred in 0.57 per cent of patients. This compares favorably with results obtained with newer and expensive drugs which usually have the disadvantage of being used in a greasy vehicle. The low incidence of sensitivity reaction to the sulfonamide-urea powder is perhaps ascribable in part to the avoidance of a greasy vehicle. PMID:14935883

  4. Fluctuation functions in aqueous NaCl and urea.

    Science.gov (United States)

    Siu, David; Koga, Yoshikata

    2005-09-08

    We earlier devised a set of fluctuation functions that provide relative qualitative differences of the amplitude (intensity) and the wavelength (extensity) of fluctuations in entropy and volume and the entropy-volume cross fluctuations. We discuss the mixing schemes in aqueous NaCl and urea using these fluctuation functions. Our earlier studies by using the second and third derivatives of Gibbs energy indicated that their effects on H2O are qualitatively different. An NaCl hydrates 7.5 molecules of H2O but leaves the bulk H2O away from the hydration shell unperturbed. Urea, on the other hand, connects onto the hydrogen bond network of H2O but retards the degree of fluctuation inherent in H2O. The behavior of the fluctuation functions calculated here are consistent with the above mixing schemes. Furthermore, urea was found to reduce the wavelength of fluctuation more strongly than NaCl.

  5. Colorimetric detection of urea nitrate: the missing link.

    Science.gov (United States)

    Rozin, Rinat; Almog, Joseph

    2011-05-20

    Traces of the improvised explosive urea nitrate can be characterized by a sensitive colorimetric reaction with p-dimethylaminocinnamalaldehyde (p-DMAC, UN-1 reagent). As recently shown, the dark red product has a structure of a protonated Schiff base. The unprotonated free base, previously postulated in the literature to be the colored product, was now prepared and fully characterized. It shows totally different spectroscopic properties from the dark red compound. Similarly, the analogous free base of the reaction between urea nitrate and the one-vinyl shorter reagent, p-dimethylaminobenzaldehyde, was synthesized and characterized. Similar differences between the free and protonated forms were observed. The protonated Schiff base spontaneously decomposes to the free base over time. This study provides the missing link in the elucidation of the colorimetric reaction between urea nitrate and UN-1. Both colored products show characteristics of typical acid-base indicators. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  6. Biosensor Urea Berbasis Biopolimer Khitin Sebagai Matriks Immobilisasi

    Directory of Open Access Journals (Sweden)

    Nazruddin Nazaruddin

    2007-06-01

    Full Text Available Penelitian tentang biosensor urea menggunakan biopolimer khitin sebagai matriks immobilisasi telah dilakukan. Penelitian ini dilakukan untuk mengetahui kinerja biosensor yang dihasilkan yang meliputi sensitivitas, trayek pengukuran, limit deteksi, waktu respon, koefisien selektifitas, dan waktu hidup. Penelitian meliputi beberapa tahap yaitu pembuatan membran polimer khitin dan immobilisasi enzim urease, pelekatan membran khitin pada elektroda pH, dan pengukuran parameter kinerja elektroda. Hasil pengukuran menunjukkan sensitivitas biosensor urea berbasis membran khitin adalah 19,11 mV/dekade, trayek pengukuran 10-4 – 10-8 M, limit deteksi 10-8 M, waktu respon 3,10–6,02 menit, dengan urutan kekuatan ion penggangu: NH4Cl > NaCl > CH3COONa > campuran garam > KCl > CaCl2 > asam askorbat. Kata kunci: biosensor, immobilisasi, khitin, urea

  7. Android integrated urea biosensor for public health awareness

    Directory of Open Access Journals (Sweden)

    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.

  8. Waste-to-Chemicals for a Circular Economy: The Case of Urea Production (Waste-to-Urea).

    Science.gov (United States)

    Antonetti, Elena; Iaquaniello, Gaetano; Salladini, Annarita; Spadaccini, Luca; Perathoner, Siglinda; Centi, Gabriele

    2017-03-09

    The economics and environmental impact of a new technology for the production of urea from municipal solid waste, particularly the residue-derived fuel (RdF) fraction, is analyzed. Estimates indicate a cost of production of approximately €135 per ton of urea (internal rate of return more than 10 %) and savings of approximately 0.113 tons of CH4 and approximately 0.78 tons of CO2 per ton of urea produced. Thus, the results show that this waste-to-urea (WtU) technology is both economically valuable and environmentally advantageous (in terms of saving resources and limiting carbon footprint) for the production of chemicals from municipal solid waste in comparison with both the production of urea with conventional technology (starting from natural gas) and the use of RdF to produce electrical energy (waste-to-energy). A further benefit is the lower environmental impact of the solid residue produced from RdF conversion. The further benefit of this technology is the possibility to realize distributed fertilizer production. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Yuen Fei Wong

    2011-02-01

    Full Text Available 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.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.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 endogenous retinoic acid in the kidney after birth, particularly in the

  10. Characterization of the improvised explosive urea nitrate using electrospray ionization and atmospheric pressure chemical ionization.

    Science.gov (United States)

    Tamiri, Tsippy

    2005-01-01

    Mass spectra of urea nitrate were measured in electrospray ionization and in atmospheric pressure chemical ionization in the negative mode. In both ionization methods two characteristic adduct ions containing the intact molecule [urea nitrate+NO3]- and [urea nitrate+HNO3+NO3]- are shown. The structure of the two adduct ions was deduced using measurements of isotopically labeled urea nitrate. Collision-induced dissociation measurements of the adduct ions show typical losses enabling the identification of urea nitrate in trace amounts. Using these methods urea nitrate was identified in real cases. Copyright (c) 2005 John Wiley & Sons, Ltd.

  11. Reinvestigation of growth of urea thiosemicarbazone monohydrate crystal

    Science.gov (United States)

    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.

  12. Effect of Urea Addition on Soda Pulping of Oak Wood

    OpenAIRE

    Cho, Nam-Seok; Matsumoto, Yuji; Shin, Soo-Jeong; Oga, Shoji

    2008-01-01

    Many studies have been conducted to find a sulfur-free additive for alkaline pulping liquors that would have an effect similar to that of sulfide in kraft pulping. Some reagents that partially fulfill this role have been found, but they are too expensive to be used in the quantities required to make them effective. As an alternative method to solve air pollution problem and difficulty of pulp bleaching of kraft pulping process, NaOH-Urea pulping was applied. The properties of NaOH-Urea pul...

  13. Nonaaqua-praseodymium triiodide-thio-urea (1/2).

    Science.gov (United States)

    Antonenko, Taisia A; Alikberova, Lyudmila Yu; Albov, Dmitry V

    2012-02-01

    The title compound, [Pr(H(2)O)(9)]I(3)·2CS(NH(2))(2), an adduct of nona-aqua-praseodymium triiodide with two thio-urea mol-ecules, is composed from [Pr(H(2)O)(9)](3+) cations (polyhedron: monocapped tetra-gonal anti-prism), noncoordinated thio-urea mol-ecules and iodide anions. The components are evidently connected by hydrogen bonds but in the presence of heavy atoms water H atoms have not been located. The complex cation and one of the two independent iodide anions are located on a twofold axis.

  14. Reverse iontophoresis of urea in health and chronic kidney disease: a potential diagnostic and monitoring tool?

    Science.gov (United States)

    Ebah, Leonard M; Read, Ian; Sayce, Andrew; Morgan, Jane; Chaloner, Christopher; Brenchley, Paul; Mitra, Sandip

    2012-01-01

    Background Patients with chronic kidney disease (CKD) need regular monitoring, usually by blood urea and creatinine measurements, needing venepuncture, frequent attendances and a healthcare professional, with significant inconvenience. Noninvasive monitoring will potentially simplify and improve monitoring. We tested the potential of transdermal reverse iontophoresis of urea in patients with CKD and healthy controls. Methods Using a MIC 2® Iontophoresis Controller, reverse iontophoresis was applied on the forearm of five healthy subjects (controls) and 18 patients with CKD for 3–5 h. Urea extracted at the cathode was measured and compared with plasma urea. Results Reverse iontophoresis at 250 μA was entirely safe for the duration. Cathodal buffer urea linearly correlated with plasma urea after 2 h (r = 0·82, P urea (y) from cathodal urea after 2 and 3 h, respectively. Cathodal urea concentration in controls was significantly lower than in patients with CKD after a minimum current application of 2 h (P urea cut-off of 30 μM gave a sensitivity of 83·3% and positive predictive value of 87% CKD. During haemodialysis, the fall in cathodal urea was able to track that of blood urea. Conclusion Reverse iontophoresis is safe, can potentially discriminate patients with CKD and healthy subjects and is able to track blood urea changes on dialysis. Further development of the technology for routine use can lead to an exciting opportunity for its use in diagnostics and monitoring. PMID:22409780

  15. Hyperpolarized 13C-Urea MRI for the assessment of the urea gradient in the porcine kidney

    DEFF Research Database (Denmark)

    Søvsø Szocska Hansen, Esben; Stewart, Neil James; Wild, Jim Michael

    Renal anatomical and pathophysiological alterations are directly associated with the fluid and electrolyte balance in the kidney, which is regulated by the extracellular corticomedullary osmolality gradient. We introduce a novel magnetic resonance imaging (MRI) approach to monitor the corticomedu...... treatment resulted in an increased urea accumulation in the cortical space. This work demonstrates intra-renal functional assessment with hyperpolarized 13C-urea MRI in multi-papillary kidneys.......Renal anatomical and pathophysiological alterations are directly associated with the fluid and electrolyte balance in the kidney, which is regulated by the extracellular corticomedullary osmolality gradient. We introduce a novel magnetic resonance imaging (MRI) approach to monitor...

  16. Urea recycling contributes to nitrogen retention in calves fed milk replacer and low-protein solid feed

    DEFF Research Database (Denmark)

    Berends, Harma; van den Borne, Joost J G C; Røjen, Betina A.

    2014-01-01

    Urea recycling, with urea originating from catabolism of amino acids and hepatic detoxification of ammonia, is particularly relevant for ruminant animals, in which microbial protein contributes substantially to the metabolizable protein supply. However, the quantitative contribution of urea...

  17. Comparative changes in monthly blood urea nitrogen, total protein ...

    African Journals Online (AJOL)

    Sibanda M

    2015-03-29

    Mar 29, 2015 ... Comparative changes in monthly blood urea nitrogen, total protein concentrations, and body ... nitrogen (BUN) concentration, total protein (TP) concentration in blood serum and the body condition score ... BUN concentration, TP concentration and body condition scores of the animals were measured over.

  18. Influence of composted organic waste and urea fertilization on rice ...

    African Journals Online (AJOL)

    The field experiment was conducted at the University of Ghana's Soil and Irrigation Research Centre - Kpong during 2014 and 2015 cropping seasons to evaluate the influence of composted organic waste and urea fertilization on rice yield, Nitrogen-use efficiency and soil chemical characteristics. The study was laid out in a ...

  19. Calculations on the electronic excited states of ureas and oligoureas.

    Science.gov (United States)

    Oakley, Mark T; Guichard, Gilles; Hirst, Jonathan D

    2007-03-29

    We report CASPT2 calculations on the electronic excited states of several ureas. For monoureas, we find an electric dipole forbidden n --> pi* transition between 180 and 210 nm, dependent on the geometry and substituents of the urea. We find two intense pinb --> pi* transitions between 150 and 210 nm, which account for the absorptions seen in the experimental spectra. The n' --> pi* and pib --> pi* transitions are at wavelengths below 125 nm, which is below the lower limit of the experimental spectra. Parameter sets modeling the charge densities of the electronic transitions have been derived and permit calculations on larger oligoureas, using the exciton matrix method. For glycouril, a urea dimer, both the CASPT2 method and the matrix method yield similar results. Calculations of the electronic circular dichroism spectrum of an oligourea containing eight urea groups indicate that the experimental spectrum cannot be reproduced without the inclusion of electronic excitations involving the side chains. These calculations are one of the first attempts to understand the relationship between the structure and excited states of this class of macromolecule.

  20. The effect of ammoniation by urea on the nutritive

    African Journals Online (AJOL)

    of.75 glkg and 400 glkg wheat straw respectively (on an air dry base). It was then ensiled at ambient temperature in airtight plastic containers for six weeks. These conditions approximate optimum conditions for the ammoniation of wheat straw by an aqueous urea solution (Kritzinger &. Franck, 1981). After six weeks the ...

  1. Urea Utilization by Cattle as Influenced by Casein | Umunna ...

    African Journals Online (AJOL)

    Urea Utilization by Cattle as Influenced by Casein. NN Umunna, WR Woods, TJ Klopfenstein. Abstract. No abstract. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's ...

  2. Environmental factors influencing milk urea nitrogen in South African ...

    African Journals Online (AJOL)

    By knowing the milk urea nitrogen (MUN) content of dairy cows, the efficiency of dietary nitrogen utilization can be improved. The main objectives of this study were to identify and quantify environmental factors affecting MUN in South African Holstein cows. This will enable better interpretation of MUN results by accounting ...

  3. 75 FR 74746 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2010-12-01

    ..., following the division of the USSR in December 1991 into 15 independent states, Commerce divided the original antidumping duty order on solid urea from the USSR into 15 orders applicable to each independent... national markets (including barriers to importation in foreign markets or changes in market demand abroad...

  4. Effect of nitrogen concentration of urea ammonium nitrate, and ...

    African Journals Online (AJOL)

    Liquid urea ammonium nitrate (UAN) was applied to dryland Pennisetum clandestinum (Kikuyu (Chiov)) and Cynodon hybrid (Coastcross II (L.) (Pers.)) pastures at two levels (207 and 414 kg N/ha/season) and at three concentrations (10, 5; 21 and 42% N) of nitrogen. The degree of leaf scorch increased as both the amount ...

  5. Effect Of Acute Caprine Trypanosomiasis On Haemoglobin, Urea ...

    African Journals Online (AJOL)

    Haemoglobin concentation of the infected goats was only slightly decreased. However, the serum urea level was significantly increased (P <0.05) while Cl, K+ and HCO3 levels were slightly increased above pre-infection values by week two post infection (PI). Serum Na+ increased only in the first week PI but returned to ...

  6. Factors affecting adoption of urea deep placement technology by ...

    African Journals Online (AJOL)

    ... of government including the non-governmental organizations should gear efforts to link rice farmers to credible sources of USG for increased paddy rice yield to attain the much desired self-sufficiency in rice production in Kwara State, Nigeria. Keywords: Factors, Adoption, Urea deep placement technology, Rice, Farmers ...

  7. Effect of different catalysts on urea-formaldehyde resin synthesis

    Science.gov (United States)

    Qi-Ning Sun; Chung-Yun Hse; Todd F. Shupe

    2014-01-01

    Four catalysts (H2SO4, HCl, H3PO4, and NaOH/NH4OH) were studied in the preparation of melamine modified urea– formaldehyde (UFM) resins. 13C-nuclear magnetic resonance spectroscopic analysis of the UFM resins at different synthesis stages revealed the...

  8. Effect of management on serum electrolytes, urea and creatinine in ...

    African Journals Online (AJOL)

    Primary nephrotic syndrome (NS) and acute glomerulonephritis (AGN) are known to cause varying degrees of renal insufficiency depending on the severity. Certain drugs and management strategies used in these two disorders also have profound effect on the serum electrolyte and urea profiles. This study determines the ...

  9. Increases In Plasma Urea And Creatinine In Experimental ...

    African Journals Online (AJOL)

    Alterations in both plasma urea and creatinine levels were monitored over a period of twenty eight (28) days in experimentally infected rabbits. A total of 15 animals were randomly divided into three groups of n=5. The groups were control (group I), infected and treated (group II) and infected but untreated (group III) ...

  10. Effect of protein supplementation and urea treatment on utilization of ...

    African Journals Online (AJOL)

    Authorised User

    South African Society for Animal Science. 23. Effect of protein supplementation and urea treatment on utilization of maize stover by Red Maasai sheep. T.A. Woyengo, C.K. Gachuiri. #. , R.G. Wahome and P.N. Mbugua. Department of Animal Production, University of Nairobi, P.O. Box 29053, Nairobi, Kenya. Abstract. Six Red ...

  11. Performance and nutrient digestibility of rabbits fed urea treated ...

    African Journals Online (AJOL)

    The study was conducted to investigate the effect of varying levels of urea treated and untreated cowpea husk on the performance of weaner rabbits. Thirty-two mongrel weaner rabbits of both sexes, 6 – 8 weeks old with an average weight of 822g were randomly distributed to four dietary treatments with four rabbits per ...

  12. Effect of water treated and urea treated neem ( Azadirachta indica ...

    African Journals Online (AJOL)

    In a study to evaluate the carcass haematological and biochemical characteristics of broiler birds fed graded levels of water and urea-treated neem kernel cake (NKC), 300 day-old broilers (Cobb, 500) were randomly assigned to five dietary treatments for 56 days. Water and feed were fed adlibitum. The diets were ...

  13. Dietary management of urea cycle disorders : European practice

    NARCIS (Netherlands)

    Adam, S.; Almeida, M. F.; Assoun, M.; Baruteau, J.; Bernabei, S. M.; Bigot, S.; Champion, H.; Daly, A.; Dassy, M.; Dawson, S.; Dixon, M.; Dokoupil, K.; Dubois, S.; Dunlop, C.; Evans, S.; Eyskens, F.; Faria, A.; Favre, E.; Ferguson, C.; Goncalves, C.; Gribben, J.; Heddrich-Ellerbrok, M.; Jankowski, C.; Janssen-Regelink, R.; Jouault, C.; Laguerre, C.; Le Verge, S.; Link, R.; Lowry, S.; Luyten, K.; MacDonald, A.; Maritz, C.; McDowell, S.; Meyer, U.; Micciche, A.; Robertson, L. V.; Rocha, J. C.; Rohde, C.; Saruggia, I.; Sjoqvist, E.; Stafford, J.; Terry, A.; Thom, R.; Vande Kerckhove, K.; van Rijn, M.; van Teeffelen-Heithoff, A.; van Wegberg, A.; van Wyk, K.; Vasconcelos, C.; Vestergaard, H.; Webster, D.; White, F. J.; Wildgoose, J.; Zweers, H.; Robert, M.

    2013-01-01

    Background: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries. Methods: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1

  14. Haematological Indices and Blood Urea Nitrogen of Yankasa Ram ...

    African Journals Online (AJOL)

    0.05) from each other. No ill-health was encountered as a result of feeding treated Kyasuwa with urea and or poultry droppings. Key words: Haematological Indices, BUN, Yankasa ram lambs, treated Kyasuwa. INTRODUCTION. As the dry season ...

  15. Differences in nitrogen and urea metabolism between goats bred for ...

    African Journals Online (AJOL)

    % of flux to recycling and 38% to excretion; in Boer goats proportionately less was recycled (48%) and more was excreted (52%) (P < 0.01). Urea N flux and recycling rates (g N/d) increased (P < 0.05) as the amount of diet fed was increased.

  16. Urea in sugarcane-based diets for dairy cows

    Directory of Open Access Journals (Sweden)

    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.

  17. reactive blending of methylol urea with soybean oil

    African Journals Online (AJOL)

    GREGO

    2007-03-19

    Mar 19, 2007 ... lol urea resin and its blend with 25% SBO showed the. Osemeahon and Barminas 807 typical characteristic for ductile polymers: stress whiten- ing followed by necking and drawing (Tai and Li, 2001). The increase in both tensile strength and elongation at break agrees with the works of Wang and co- ...

  18. Potential application of urea-derived herbicides as cytokinins in ...

    Indian Academy of Sciences (India)

    MADU

    2Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli. 620 024, India. *Corresponding author (Fax, 91-80-23600814; Email, lipid@biochem.iisc.ernet.in). Various urea-derived herbicides and different cytokinin analogues were used to determine their effects on callusing response ...

  19. Emissions of gun propellant compositions with added urea

    NARCIS (Netherlands)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Effect of mycorrhizal inoculum and urea fertilizer on diseases ...

    African Journals Online (AJOL)

    A randomized block design with four replicates was used, with two applications of mycorrhizal inoculum. The inoculum contained spores of Glomus sp. and Gigaspora sp. in concentration of 2.103 spores.g-¹. A urea treatment and an absolute control were also used. The number of nodules per plant, the root colonization rate ...

  2. Effect of replacing groundnut cake with urea fermented brewer's ...

    African Journals Online (AJOL)

    The effect o replacing groundnut cake with urea fermented brewer's dried grains at 0 25 50, 75 and 100 % graded levels in broiler chick starter diets was investigated. Five dietary treatments were formulated to be isonitrogenous and isocaloric to provide 23 % crude protein and 2900 kcal/kg metabolizable energy.

  3. Comparative changes in monthly blood urea nitrogen, total protein ...

    African Journals Online (AJOL)

    The objective of this study was to determine the comparative changes in the monthly blood urea nitrogen (BUN) concentration, total protein (TP) concentration in blood serum and the body condition score of Nguni cows and heifers raised on sweetveld. Twenty-four clinically healthy animals in different parities, namely Parity ...

  4. Effects of urea-molasses-multinutrient block supplementation on ...

    African Journals Online (AJOL)

    The effect of urea-molasses-multinutrient blocks (UMMB) as an energy and protein supplement on reproductive performance and milk yield of dairy cows was investigated in 18 crossbred cows from eight smallholder farms. In treatment 1 nine, cows were fed a maximum of 1 kg (UMMB per cow per day in addition to the ...

  5. Comparative evaluation of raw and urea/toasted velvet bean ...

    African Journals Online (AJOL)

    Feeding trials lasting 28 days were conducted to investigate the nutritive value of raw and urea treated/toasted mucuna bean for broiler chicks. Raw mucuna bean contains 30.33% crude protein, 7.20% crude fibre, 6.9% ether extract and 5.0% ash. Mucuna bean seeds were divided into two batches. One batch was ground ...

  6. Effect of protein supplementation and urea treatment on utilization of ...

    African Journals Online (AJOL)

    Six Red Maasai sheep were used to investigate the effects of urea treatment and cotton seed cake supplementation of maize stover on intake, digestibility and rumen fermentation parameters. The basal feeds were Rhodes grass (Chloris gayana) hay (H), untreated maize (Zea mays) stover (US) and treated maize stover ...

  7. Urea adsorption by activated carbon prepared from palm kernel shell

    Science.gov (United States)

    Ooi, Chee-Heong; Sim, Yoke-Leng; Yeoh, Fei-Yee

    2017-07-01

    Dialysis treatment is crucial for patients suffer from renal failure. The dialysis system removes the uremic toxin to a safe level in a patient's body. One of the major limitations of the current hemodialysis system is the capability to efficiently remove uremic toxins from patient's body. Nanoporous materials can be applied to improve the treatment. Palm kernel shell (PKS) biomass generated from palm oil mills can be utilized to prepare high quality nanoporous activated carbon (AC) and applied for urea adsorption in the dialysis system. In this study, AC was prepared from PKS via different carbonization temperatures and followed by carbon dioxide gas activation processes. The physical and chemical properties of the samples were studied. The results show that the porous AC with BET surface areas ranging from 541 to 622 m2g-1 and with total pore volumes varying from 0.254 to 0.297 cm3g-1, are formed with different carbonization temperatures. The equilibrium constant for urea adsorption by AC samples carbonized at 400, 500 and 600 °C are 0.091, 0.287 and 0.334, respectively. The increase of carbonization temperatures from 400 to 600 °C resulted in the increase in urea adsorption by AC predominantly due to increase in surface area. The present study reveals the feasibility of preparing AC with good porosity from PKS and potentially applied in urea adsorption application.

  8. Synthesis and characterization of new thiourea and urea derivatives ...

    Indian Academy of Sciences (India)

    A new class of antimicrobial and antioxidant agents, based on thiourea and urea derivatives of 6-fluoro-3-(piperidin-4-yl)benzo[] isoxazole were synthesized by adopting a simple and efficient method. Synthesized compounds were characterized by spectral data of IR, 1H, 13C NMR and mass spectra. The compounds ...

  9. Influence of pig manure, urea and combinations of their reduced ...

    African Journals Online (AJOL)

    The influence of sole and combined application of pig manure and urea on the performance of Amaranthus cruentus at Umudike in a rainforest Ultisol was investigated for two years. The study was laid out in a randomized complete block design with four replications. There were six treatments consisting of pig manure ...

  10. Effect of mycorrhizal inoculum and urea fertilizer on diseases ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-08-18

    Aug 18, 2008 ... Diseases (rosette virus disease (RVD), Cercospora leaf spot (CLS) and poverty of soils in nutrients are ... Healthy plants infected plants. Figure 1. Effect of mycorrhizae and urea fertilizer on nodulation of groundnut crops 7 weeks after inoculation. .... between mycorrhizal fungi and the plants results in the.

  11. Melamine-modified urea formaldehyde resin for bonding particleboards

    Science.gov (United States)

    Chung-Yun Hse; Feng Fu; Hui Pan

    2008-01-01

    For the development of a cost-effective melamine-modified urea formaldehyde resin (MUF), the study evaluated the effects of reaction pH and melamine content on resin properties and bond performance of the MUF resin adhesive systems. Eight resins, each with three replicates, were prepared in a factorial experiment that included two formulation variables: two reaction...

  12. [Plasma urea along with every plasma creatinine test?

    NARCIS (Netherlands)

    Zwam, M. van; Wetzels, J.F.M.; Willems, H.L.

    2013-01-01

    The concentration of plasma creatinine and the estimated glomerular filtration rate, calculated from plasma creatinine, age, weight, and gender, are used to assess kidney function. In routine clinical practice the concentration of plasma urea is often determined at the same time as the creatinine

  13. Urea modified cottonseed protein adhesive for wood composite products

    Science.gov (United States)

    Cottonseed protein has the potential to be used as renewable and environmentally friendly adhesives in wood products industry. However, the industry application was limited by its low mechanical properties, low water resistance and viscosity. In this work, urea modified cottonseed protein adhesive w...

  14. Effect of Concentrate Mix Supplementation to Urea-Treated and ...

    African Journals Online (AJOL)

    The effects of feeding different levels of concentrate mixture to sheep fed urea treated maize stover basal diet on feed intake, digestibility, and nitrogen balance were evaluated at Haramaya University. The experiment was conducted in a randomized complete block design using twenty male Hararghe Highland sheep with a ...

  15. Crystal engineering with urea and thiourea hydrogen-bonding groups

    Energy Technology Data Exchange (ETDEWEB)

    Custelcean, Radu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division

    2007-09-11

    The utilization of N,N$'$-disubstituted ureas and thioureas as design elements in the synthesis of crystalline organic solids is reviewed. In conclusion, these hydrogen-bonding units are versatile yet predictable building blocks that can be rationally employed in both crystal assembly and functionalization.

  16. The effect of urea with urease inhibitors and urea on yield and nitrate content in potato tubers

    Directory of Open Access Journals (Sweden)

    Karel Drápal

    2013-01-01

    Full Text Available The three-year field trial was established on two localities – Žabčice and Valečov in 2010–2012. Seven variants of nitrogen fertilization in four replications have been involved in this experiment – 100% of urea (U, 80% of urea, 60% of urea, 100% of UreaStabil (US, 80% of UreaStabil and 60% of UreaStabil, whilst 100% corresponded to 90 kg N.ha−1 after subtracting the content of Nmin in the soil, and the control variant without fertilization by mineral nitrogen. The two varieties with different lengths of vegetation periods have been chosen for the experiment – the early variety Karin and the mid-early variety Red Anna. In all cases, samples for the yield and qualitative analyses have been taken according to the phenological phase – the beginning of physiological maturity. The obtained results show that the highest average yield has been achieved in the variant of 100% of urea – 40.95 t. ha−1, the yield of this variant was statistically significantly higher than the yield of the other variants of fertilization (P < 0.05. Variants treated by urea without the urease inhibitor reached an average yield of 37.62 t.ha−1. However, this yield was not statistically significantly higher when comparing to the urea with the urease inhibitor (P > 0.05. In regard to localities, a relatively high average yield (44.58 t.ha−1 has been achieved on a characteristically potato-growing locality Valečov. This yield was statistically significantly higher than the one attained on the Žabčice locality (P < 0.05. In respect to varieties, the mid-early variety Red Anna attained a higher average yield (39.65 t. ha−1. Likewise, this yield was statistically significantly higher than the one of the early variety Karin (P < 0.05. The best year was 2012, in which the average yield of 38.73 t.ha−1 was achieved. This yield was statistically significantly higher than the yield of the year 2010 (P < 0.05. As far as nitrates are concerned, the

  17. Distribution of urea in the waters of the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.

    at some levels and very low concentrations at others. Urea concentration increases towards the central west coast of India. Comparison with the other inorganic nutrients indicates that urea constitutes 10% of the available nitrogen in the euphotic zone (0...

  18. Synthesis of organic/inorganic hybrid gel with acid activated clay after γ-ray radiation.

    Science.gov (United States)

    Kim, Donghyun; Lee, Hoik; Sohn, Daewon

    2014-08-01

    A hybrid gel was prepared from acid activated clay (AA clay) and acrylic acid by gamma ray irradiation. Irradiated inorganic particles which have peroxide groups act as initiator because it generates oxide radicals by increasing temperature. Inorganic nanoparticles which are rigid part in hybrid gel also contribute to increase the mechanical property as a crosslinker. We prepared two hybrid gels to compare the effect of acid activated treatment of clay; one is synthesized with raw clay particles and another is synthesized with AA clay particles. The composition and structure of AA clay particles and raw clay particles were confirmed by X-ray diffraction (XRD), X-ray fluorescence instrument and surface area analyzer. And chemical and physical property of hybrid gel with different ratios of acrylic acid and clay particle was tested by Raman spectroscope and universal testing machine (UTM). The synthesized hydrogel with 76% gel contents can elongated approximately 1000% of its original size.

  19. Acid activation of Bentonite for use as a vegetable oil bleaching agent

    Energy Technology Data Exchange (ETDEWEB)

    Makhoukhi, B.; Didi, M. A.; Villemin, D.; Azzouz, A.

    2009-07-01

    The design of various experiments in order to assess and simulate the effects of the acid activation of an Algerian bentonite on the bleaching capacity of Colza oil is described. Three key parameters of the acidic activation, namely acid concentration, contact time and temperature, were considered. The calculations made indicated that all variables display advantageous effects up to a certain level on the effectiveness of bleaching, regarded as the response function. The acid concentration exerts a predominant individual effect as compared to the other parameters. Some small interactions between parameters were considered. High bleaching capacity reached 99% as optimal activation. Under accurate statistical measurements, synergy phenomena could be observed. Excessive activation is discussed in terms of loss in both porosity and acid strength. (Author) 14 refs.

  20. Urea pre-treatment of N2-annealed transition metal oxides for low cost and efficient counter electrodes in dyesensitized solar cell

    Science.gov (United States)

    Elbohy, Hytham

    Photovoltaic cells have shown great promise as an alternative to fossil fuel-based energy sources. Dye-sensitized solar cells (DSSCs) have shown potential as low-cost replacement to silicon solar cells owing to their reduced material costs and simple fabrication techniques. Platinum (Pt) was used as a catalyst in the counter electrode for DSSCs. Metal oxides have been used as an alternative material to Pt. The introduction of oxygen vacancies inside metal oxides helps to facilitate electron transport to the electrolyte to enhance the reduction process of triiodide ions. Annealing n-type metal oxides under a reducing agent gas such as hydrogen (H2) at temperature ≥400 °C helps to introduce more oxygen vacancies. In this dissertation, a novel method was developed to convert the electro-catalytically inactive commercial n-type WO3, SnO2-x and ZnO1-x SnO2, and ZnO into highly active WO3-x as counter electrodes (CEs) for DSSCs. These new metal oxides replaced Pt by controlling the number of introduced oxygen vacancies. All the metal oxides including WO3 annealing under N2, SnO2, and ZnO were pre-treated with urea at different wt% before environment at 470 °C for 2 hr. At high temperatures (e.g., 300-400 °C), urea easily decomposes to ammonia which then decomposes to H2 Higher wt% of urea leads to more reducing H2 and N2 gas and hence helps to create more oxygen vacancies. The urea treatment significantly improved the catalytic activity of all metal oxides, and solar cell power conversion efficiency (PCE) of DSSCs was increased by urea pre-treatment. All other characterizations including SEM, EDS, and Mott-Schottky performed for urea pre-treatment of WO3, SnO2 and ZnO support the hypothesis that urea treatment helps create oxygen vacancies (shallow defects states) in metal oxides. These oxygen vacancies facilitate the redox process in the iodide/triiodide electrolyte. The density of these oxygen vacancies can be engineered by controlling the urea wt% during

  1. Simple ureas derived from diisocyanates and their liquid chromatography on a 5-cm column.

    Science.gov (United States)

    Vogt, C R; Ko, C Y; Ryan, T R

    1977-04-11

    Aliphatic and aromatic diisocyanates were converted to ureas by a chromophoric derivatizing reagent. The ureas were isolated in the pure form characterized by various methods including nuclear magnetic resonance and mass spectrometry. A chromatographic analytical separation of the urea test solutions was established. The method was used to demonstrate the derivatization of the isocyanates and direct determination of the produced ureas from the reaction mixture.

  2. A Facile Method for the Preparation of Unsymmetrical Ureas Utilizing Zirconium(IV) Chloride

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Anna [Myongji University, Yongin (Korea, Republic of); Kim, Hee-Kwon [Chonbuk National University, Jeonju (Korea, Republic of); Thompson, David H. [Purdue University, West Lafayette (United States)

    2016-02-15

    A facile synthetic method for the preparation of unsymmetrical ureas from amines is described.Carbamoyl imidazole compounds were prepared by the reaction of 1,1-carbonyldiimidazole with primary or secondary amines, and further activation by treatment with zirconium(IV) chloride to generate the desired urea. This reaction protocol was applied to the synthesis of tri and tetrasubstituted ureas with high yields. This study provides an alternative guideline for the practical preparation of various unsymmetrical ureas.

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

    DEFF Research Database (Denmark)

    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....

  4. Urea-SCR Temperature Investigation for NOx Control of Diesel Engine

    OpenAIRE

    Asif Muhammad; Zhang Youtong; Lin Wei

    2015-01-01

    SCR (selective catalytic reduction) system is continuously being analyzed by many researchers worldwide on various concerns due to the stringent nitrogen oxides (NOx) emissions legislation for heavy-duty diesel engines. Urea-SCR includes AdBlue as urea source, which subsequently decomposes to NH3 (ammonia) being the reducing agent. Reaction temperature is a key factor for the performance of urea-SCR system, as urea decomposition rate is sensitive to a specific temperature range. This particul...

  5. Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

    Energy Technology Data Exchange (ETDEWEB)

    Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

  6. Mechanistic and functional insights into fatty acid activation in Mycobacterium tuberculosis

    OpenAIRE

    Arora, Pooja; Goyal, Aneesh; Natarajan, Vivek T.; Rajakumara, Eerappa; Verma, Priyanka; Gupta, Radhika; Yousuf, Malikmohamed; Trivedi, Omita A.; Mohanty, Debasisa; Tyagi, Anil; Sankaranarayanan, Rajan; Rajesh S Gokhale

    2009-01-01

    The recent discovery of fatty acyl-AMP ligases (FAALs) in Mycobacterium tuberculosis (Mtb) provided a new perspective to fatty acid activation dogma. These proteins convert fatty acids to corresponding adenylates, which is an intermediate of acyl-CoA-synthesizing fatty acyl-CoA ligases (FACLs). Presently, it is not evident how obligate pathogens like Mtb have evolved such new themes of functional versatility and whether the activation of fatty acids to acyl-adenylates could indeed be a genera...

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Acid activated montmorillonite as catalysts in methyl esterification reactions of lauric acid.

    Science.gov (United States)

    Zatta, Leandro; Ramos, Luiz Pereira; Wypych, Fernando

    2012-01-01

    The catalytic activity of acid activated montmorillonite in the esterification of free fatty acids (FFA) is reported. Standard Montmorillonite (MMT) type STx-1 provided by the Clay Mineral Society repository was activated using phosphoric, nitric and sulphuric acids under different conditions and the resulting materials were characterized and evaluated as catalysts in the methyl esterification of lauric acid. Blank reactions carried out in the absence of any added catalyst presented conversions of 32.64, 69.79 and 79.23%, for alcohol:lauric acid molar ratios of 60:1, 12:1 and 6:1, respectively. In the presence of the untreated clay and using molar ratios of 12:1 and 6:1 with 12% of catalyst, conversions of 70.92 and 82.30% were obtained, respectively. For the acid activated clays, conversions up to 93.08% of lauric acid to methyl laurate were obtained, much higher than those observed for the thermal conversion or using untreated montmorillonite. Relative good correlations were observed between the catalytic activity and the development of acid sites and textural properties of the resulting materials. Therefore, a simple acid activation was able to improve the catalytic activity and produce clay catalysts that are environmental friendly, cost effective, noncorrosive and reusable.

  9. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Science.gov (United States)

    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 of...

  10. Effect of diet and physiological state on recycling of urea in Merino ...

    African Journals Online (AJOL)

    The recycling of urea to the rumen was studied in Merino ewes during differentp hysiologicals tates using radioactivet racers. The results showed that although the proportion of urea recycled differed, similar amounts were recycled in dry and pregnant sheep over a wide range of N intake. Urea recycling increased ...

  11. Superspace group descriptions of the symmetries of incommensurate urea inclusion compounds

    NARCIS (Netherlands)

    vanSmaalen, S; Harris, KDM

    1996-01-01

    Urea inclusion compounds are a class of incommensurate composite crystals. The urea molecules form a three-dimensionally connected network, with approximate space group symmetry P6(1)22. This network contains tunnels (channels), which accommodate guest molecules. The periodicities of the urea

  12. Effect of Microbial Interaction on Urea Metabolism in Chinese Liquor Fermentation

    NARCIS (Netherlands)

    Wu, Qun; Lin, Jianchun; Cui, Kaixiang; Du, Rubin; Zhu, Yang; Xu, Yan

    2017-01-01

    Urea is the primary precursor of the carcinogen ethyl carbamate in fermented foods. Understanding urea metabolism is important for controlling ethyl carbamate production. Using Chinese liquor as a model system, we used metatranscriptome analysis to investigate urea metabolism in spontaneous food

  13. GC-MS DETERMINATION OF RATIOS OF STABLE-ISOTOPE LABELED TO NATURAL UREA USING [(CN2)-C-13-N-15]UREA FOR STUDYING UREA KINETICS IN SERUM AND AS A MEANS TO VALIDATE ROUTINE METHODS FOR THE QUANTITATIVE ASSAY OF UREA IN DIALYSATE

    NARCIS (Netherlands)

    WOLTHERS, BG; TEPPER, T; WITHAG, A; NAGEL, GT; DEHAAN, THY; VANLEEUWEN, JJ; STEGEMAN, CA; HUISMAN, RM

    A GC-MS determination of urea in serum or spent dialysate is described, using (CN2)-C-13-N-15-labelled urea and assaying the area ratio of labelled to natural urea by mass fragmentographic monitoring of fragments m/e 153 and 156, after its eventual conversion into the trimethylsilylether-derivative

  14. effect of combined use of urea and goat dung manure on celosia

    African Journals Online (AJOL)

    Three field experiments were conducted to investigate the separate and combined effects of urea and goat dung manure on leaf nutrient contents, growth and yield of Celosia argentea in southwest Nigeria. Each experiment involved 7 treatments namely: no treatment, 10t/ha goat dung, 125 kg/ha urea, 125 kg/ha urea + ...

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

    NARCIS (Netherlands)

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

    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

  16. 40 CFR 721.9920 - Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-.

    Science.gov (United States)

    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, (hexahydro-6...

  17. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Science.gov (United States)

    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 the...

  18. Effect of diet anil physiological state on recycling of urea in Merino ...

    African Journals Online (AJOL)

    The recycling of urea to the rumen was studied in Merino ewes during different physiological states using radioactive tracers. The results showed that although the proportion of urea recycled differed, similar amounts were recycled in dry and pregnant sheep over a wide range of N intake. Urea recycling increased ...

  19. RESPONSE OF POPCORN (ZEA MAYS SSP. EVERTA L. TO UREA AND SULFUR FERTILIZER AS WELL AS FOLIAR UREA APPLICATION

    Directory of Open Access Journals (Sweden)

    Ali Husain JASIM

    2016-06-01

    Full Text Available A field experiment was carried out in private field (Abu-Garaq, 10 km west of Hilla city during the autumn season of 2014 in silt clay loam soil, to study the response of popcorn to spraying urea under different soil fertilization levels of urea and agricultural sulfur. Split – split blot design in randomized complete blocks design (RCBD in three replications was used. The factors were: soil fertilizer with urea (0, 100 and 200 kg ha-1 which were given symbols (U0, U100 and U200 respectively, and three agricultural sulfur levels (0, 10 and 20 kg ha-1 which were given symbols (S0, S10, S20 respectively, and two levels of spraying urea (spraying and control. The spraying was done twice (at 12 leaves stage and silk appearance stage at concentration of %0.05 even full wet which were given symbols (A0, A1 respectively. The results showed that 200 kg ha-1 (U200 was superior significantly in ear rows number, grain number per row, the weight of 300 grain (19.42 , 45.5 , 45,2 g . U100 and U200 caused a significant effect in plant yield (160.11 g and 157.98 g and total grain yield (7.63 and 7.43 ton.ha-1 compared to control. Sulfur level 10 and 20 kg ha-1 (S10 and S20 was superior and gave the highest average of: ear rows number (18.97 and 18.77, weight of 300 grain (43.48 and 42.88g, respectively compared to control. Spraying urea (A1 was superior in ear row number (19.17. The interaction caused a significant effect in most of the studied traits.

  20. Molecular cloning and expression of a member of the aquaporin family with permeability to glycerol and urea in addition to water expressed at the basolateral membrane of kidney collecting duct cells.

    OpenAIRE

    Ishibashi, K.; Sasaki, S; Fushimi, K.; Uchida, S.; Kuwahara, M; Saito, H.; Furukawa, T; Nakajima, K.; Yamaguchi, Y.; Gojobori, T.

    1994-01-01

    Water transport in highly water-permeable membranes is conducted by water-selective pores--namely, water channels. The recent cloning of water channels revealed the water-selective characteristics of these proteins when expressed in Xenopus oocytes or reconstituted in liposomes. Currently, it is assumed that the function of water channels is to transport only water. We now report the cloning of a member of the water channel that also transports nonionic small molecules such as urea and glycer...

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

    OpenAIRE

    Osumanu H. Ahmed; Aminuddin Hussin; Husni M. H. Ahmad; Mohamadu B. Jalloh; Rahim, Anuar A.; Nik M.A. Majid

    2009-01-01

    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 s...

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

    Directory of Open Access Journals (Sweden)

    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

  3. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Science.gov (United States)

    Yahya, Noorhana; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-01

    The catalytic activity of hematite (α-Fe2O3) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe2O3 (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is -4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0-21 respectively. In addition, it induces magnetic moment value of 36.33 μB, which confirms the enhanced magnetic behaviour of hematite. α-Fe2O3 nanowires (NWs) synthesized by heating iron wire in a box furnace at (750-800) °C and as synthesized α-Fe2O3 nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe2O3 and Raman spectrum analyses confirms the α-Fe2O3 peaks at 410 cm-1, 500 cm-1 and 616 cm-1. The needle-like shape of hematite nanowires with length ranging from 16-25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe2O3 perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe2O3 NWs for urea production is lower than NPs in the range of 0-1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690-1600 cm-1. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process currently used by the current industry which utilizes high temperature and high pressure.

  4. 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

    DEFF Research Database (Denmark)

    Røjen, Betina Amdisen; Kristensen, Niels Bastian

    2012-01-01

    investigated. Three Danish Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in major splanchnic blood vessels were randomly allocated to a 3 × 3 Latin square design with 21-d periods. Treatments were ventral ruminal infusion of water for 24h (water INF), 24-h infusion of 15g...... concentration was observed. The portal flux of urea-N was not affected by treatment (i.e., even the combination of low ruminal ammonia and high arterial urea-N concentration with 6-h INF was not used by the cow to increase the uptake of urea-N across the PDV). Arterial urea-N extraction across the PDV......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...

  5. Growth of bulk single crystals of urea for photonic applications

    Science.gov (United States)

    Saranraj, Arumugam; Sathiyadhas, Sahaya Jude Dhas; Jose, Michael; Martin Britto Dhas, Sathiyadhas Amalapusham

    2017-08-01

    We report the growth of technologically important urea crystals of record size (48 × 16 × 8 mm3) by doping sulfuric acid and employing slow evaporation technique. The grown crystal was identified by single crystal X-Ray diffraction and FTIR spectral analysis. Optical properties of the grown crystal were analyzed by UV-Vis spectrum and the presence of H2SO4 was confirmed by EDAX analysis. Thermogravimetric analysis, Differential Scanning Calorimetry and Photo acoustic studies were also carried out to determine the thermal properties of the grown crystal. The dielectric properties for wide range of frequencies (1 Hz to 1 MHz) at different temperatures (35, 40, 60, 80, 100 °C) were analyzed. The second harmonic conversion efficiency of the grown H2SO4 doped urea crystal was found to be 3.75 times higher than the commercially available KDP crystals. [Figure not available: see fulltext.

  6. Growth of bulk single crystals of urea for photonic applications

    Science.gov (United States)

    Saranraj, Arumugam; Dhas, Sathiyadhas Sahaya Jude; Jose, Michael; Martin Britto Dhas, Sathiyadhas Amalapusham

    2018-01-01

    We report the growth of technologically important urea crystals of record size (48 × 16 × 8 mm3) by doping sulfuric acid and employing slow evaporation technique. The grown crystal was identified by single crystal X-Ray diffraction and FTIR spectral analysis. Optical properties of the grown crystal were analyzed by UV-Vis spectrum and the presence of H2SO4 was confirmed by EDAX analysis. Thermogravimetric analysis, Differential Scanning Calorimetry and Photo acoustic studies were also carried out to determine the thermal properties of the grown crystal. The dielectric properties for wide range of frequencies (1 Hz to 1 MHz) at different temperatures (35, 40, 60, 80, 100 °C) were analyzed. The second harmonic conversion efficiency of the grown H2SO4 doped urea crystal was found to be 3.75 times higher than the commercially available KDP crystals. [Figure not available: see fulltext.

  7. Urea- and Thiourea-Catalyzed Aminolysis of Carbonates.

    Science.gov (United States)

    Blain, Marine; Yau, Honman; Jean-Gérard, Ludivine; Auvergne, Rémi; Benazet, Dominique; Schreiner, Peter R; Caillol, Sylvain; Andrioletti, Bruno

    2016-08-23

    The aminolysis of (poly)carbonates by (poly)amines provides access to non-isocyanate polyurethanes (NIPUs) that are toxic-reagent-free analogues of polyurethanes (PUs). Owing to their low reactivity, the ring opening of cyclic carbonates requires the use of a catalyst. Herein, we report that the more available and cheaper ureas could advantageously be used for catalyzing the formation of NIPUs at the expense of the thiourea analogues. In addition, we demonstrate a medium-range pKa of the (thio)urea and an unqeual substitution pattern is critical for controlling the efficiency of the carbonate opening. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Quantifying why urea is a protein denaturant, whereas glycine betaine is a protein stabilizer

    Science.gov (United States)

    Guinn, Emily J.; Pegram, Laurel M.; Capp, Michael W.; Pollock, Michelle N.; Record, M. Thomas

    2011-01-01

    To explain the large, opposite effects of urea and glycine betaine (GB) on stability of folded proteins and protein complexes, we quantify and interpret preferential interactions of urea with 45 model compounds displaying protein functional groups and compare with a previous analysis of GB. This information is needed to use urea as a probe of coupled folding in protein processes and to tune molecular dynamics force fields. Preferential interactions between urea and model compounds relative to their interactions with water are determined by osmometry or solubility and dissected using a unique coarse-grained analysis to obtain interaction potentials quantifying the interaction of urea with each significant type of protein surface (aliphatic, aromatic hydrocarbon (C); polar and charged N and O). Microscopic local-bulk partition coefficients Kp for the accumulation or exclusion of urea in the water of hydration of these surfaces relative to bulk water are obtained. Kp values reveal that urea accumulates moderately at amide O and weakly at aliphatic C, whereas GB is excluded from both. These results provide both thermodynamic and molecular explanations for the opposite effects of urea and glycine betaine on protein stability, as well as deductions about strengths of amide NH—amide O and amide NH—amide N hydrogen bonds relative to hydrogen bonds to water. Interestingly, urea, like GB, is moderately accumulated at aromatic C surface. Urea m-values for protein folding and other protein processes are quantitatively interpreted and predicted using these urea interaction potentials or Kp values. PMID:21930943

  9. Mechanical Insight into Resistance of Betaine to Urea-Induced Protein Denaturation.

    Science.gov (United States)

    Chen, Jiantao; Gong, Xiangjun; Zeng, Chaoxi; Wang, Yonghua; Zhang, Guangzhao

    2016-12-08

    It is known that urea can induce protein denaturation that can be inhibited by osmolytes. Yet, experimental explorations on this mechanism at the molecular level are still lacking. We have investigated the resistance of betaine to the urea-induced denaturation of lysozyme in aqueous solutions using low-field NMR. Our study demonstrates that urea molecules directly interact with lysozyme, leading to denaturation. However, betaine molecules interacting with urea more strongly than lysozyme can pull the bound urea molecules from lysozyme so that the protein is protected from denaturation. The number of urea molecules bound to a betaine molecule is given under different conditions. Proton NMR spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy reveal that the interaction between betaine and urea is through hydrogen bonding.

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

    OpenAIRE

    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 ...

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

    OpenAIRE

    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...

  12. Reliable, rapid and simple voltammetric detection of urea nitrate explosive.

    Science.gov (United States)

    Cagan, Avi; Lu, Donglai; Cizek, Karel; La Belle, Jeff; Wang, Joseph

    2008-05-01

    A highly selective and rapid electrochemical assay of the improvised explosive urea nitrate (UN) is reported. The method involves a short ( approximately 10 s) acid-catalyzed reaction of UN with 4-nitrotoluene (NT) followed by a rapid ( approximately 2 s) square-wave voltammetric (SWV) detection of the 2,4-dinitrotoluene (DNT) product. The new protocol offers great promise for a reliable field detection of UN, with significant advantages of speed, sensitivity, portability, simplicity, and cost.

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

    OpenAIRE

    Das G.; Yoon HH

    2015-01-01

    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...

  14. A stochastic model for an urea decomposition system

    Directory of Open Access Journals (Sweden)

    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.

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

    OpenAIRE

    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...

  16. Deaktivasi Katalis Konverter-Hidrogen Di Pabrik Urea Kaltim-3

    Directory of Open Access Journals (Sweden)

    Agus Subekti

    2007-10-01

    Full Text Available Di pabrik urea, konverter-hidrogen adalah satu reaktor yang berfungsi untuk mengkonversi hidrogen yang terikut dalam karbondioksida dengan cara mengoksidasi dengan udara, sehingga karbondioksida umpan reaktor urea itu hanya mengandung tidak lebih dari 100 ppm hidrogen. Konversi dilangsungkan pada tekanan 145 kg/cm2 dan suhu umpan reaktor 130°C, menggunakan katalis platinum berpenyangga alumina (0,3%Pt/Al2O3. Dalam dua tahun terakhir, terjadi kenaikan kandungan hidrogen dalam karbondioksida umpan konverter-hidrogen Kaltim-3 yang menyebabkan peningkatan temperatur keluaran konverter dari biasanya sekitar 152oC menjadi sekitar 190°C. Hasil analisis kadar Pt, luas permukaan katalis dan dispersi Pt terhadap katalis-baru dan katalis-terpakai menunjukkan bahwa katalis konverter-hidrogen Kaltim-3 telah terdeaktivasi. Oleh karena itu, pada kesempatan perbaikan-tahunan Juli 2006 yang lalu, katalis tersebut telah diganti dengan yang baru. Selain itu telah dilakukan pula perbaikan kondisi operasi di pabrik amoniak Kaltim-3, sehingga kadar H2 dalam aliran CO2 umpan pabrik urea Kaltim-3 menjadi normal kembali (0,4%. Dengan tindakan-tindakan tersebut, sejak Agustus 2006 yang lalu konverter hidrogen Kaltim-3 dapat beroperasi secara normal kembali. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: A. Subekti, A.S. Arief, P. Praharso, S. Subagjo. (2007. Deaktivasi Katalis Konverter-Hidrogen Di Pabrik Urea Kaltim-3. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 52-55.  doi:10.9767/bcrec.2.2-3.7130.52-55][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.7130.52-55 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7130] 

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

    Science.gov (United States)

    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.

  18. Urochloa ruziziensis responses to sources and doses of urea

    Directory of Open Access Journals (Sweden)

    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. Improvement of Egyptian vacuum distillates by urea dewaxing

    Directory of Open Access Journals (Sweden)

    Ehssan M.R. Nassef

    2015-09-01

    Full Text Available The dewaxing of paraffinic lube stocks is an essential step in the production of lubricants to improve the operability of machines especially in winter. The present work deals with study of the urea dewaxing process of two types of Egyptian vacuum distillates. The effect of different compositions of methanol to water saturated with urea and yield of the oil, percent of wax, pour point, refractive index, viscosity, viscosity index and specific gravity of the oil produced from the two types of distillates (I and II were evaluated. The operating conditions of the urea adduct formation with n-paraffins using methanol to water mixture achieved the best pour point at −3.88 °C from an initial temperature of 4.4 °C for distillate I at (25/75 methanol to water. At the same ratio of methanol to water the best specific gravity of oil produced changed from 0.865 to 0.867, with viscosity index of 80. Percent yield of 50% for oil and percent wax of 50% were obtained. Results for distillate II, of higher specific gravity, are comparatively higher than those for distillate I. Experiments were carried out at room temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Synthesis of dimethyl carbonate from urea and methanol

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  2. The Lowest Vibrational States of Urea from the Rotational Spectrum

    Science.gov (United States)

    Kisiel, Zbigniew; Thomas, Jessica; Medvedev, Ivan

    2014-06-01

    The urea molecule, (NH_2)_2CO, has a complex potential energy surface resulting from a combination of the NH_2 torsion and NH_2 inversion motions. This leads to a distribution of lowest vibrational states that is expected to be significantly different from the more familiar picture from simple inversion or normal mode models. The broadband 207-500 GHz spectrum of urea recorded in Dayton has signal to noise sufficient for assignment of rotational transitions in excited vibrational states up to at least 500 cm-1. In addition to the previously reported analysis of the ground and the lowest excited state we have been able to assign transitions in at least five other excited vibrational states. Strongly perturbed transitions in a close doublet of such states have been fitted to within experimental accuracy with a coupled fit and a splitting in the region of 1 cm-1. These assignments combined with vibrational energy estimates from relative intensity measurements allow for empirical discrimination between different models for the energy level manifestation of the large amplitude motions in urea.^b P.D.Godfrey, R.D.Brown, A.N.Hunter J. Mol. Struct., 413-414, 405-414 (1997). N.Inostroza, M.L.Senent, Chem. Phys. Lett., 524, 25 (2012).

  3. 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

    NARCIS (Netherlands)

    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

  4. The effect of CP concentration in the diet on urea kinetics and microbial usage of recycled urea in cattle: a meta-analysis.

    Science.gov (United States)

    Batista, E D; Detmann, E; Valadares Filho, S C; Titgemeyer, E C; Valadares, R F D

    2017-08-01

    In ruminants, urea recycling is considered an evolutionary advantage. The amount of urea recycled mainly depends of the nitrogen (N) intake and the amount of organic matter (OM) digested in the rumen. Because recycled N contributes to meeting microbial N requirements, accurate estimates of urea recycling can improve the understanding of efficiency of N utilization and N losses to the environment. The objective of this study was to evaluate urea kinetics and microbial usage of recycled urea N in ruminants using a meta-analytical approach. Treatment mean values were compiled from 25 studies with ruminants (beef cattle, dairy cows and sheep) which were published from 2001 to 2016, totalling 107 treatment means. The data set was analyzed according to meta-analysis techniques using linear or non-linear mixed models, taking into account the random variations among experiments. Urea N synthesized in the liver (UER) and urea N recycled to the gut (GER) linearly increased (PCP concentration and the ratio of CP to digestible OM (CP:DOM). Maximum curvature analyses identified 17% dietary CP as the point where there was a prominent increase in hepatic synthesis of urea N, likely due to an excess of dietary N leading to greater ammonia absorption. The GER:UER decreased with increasing dietary CP concentration (PCP⩾19%, GER:UER reached near minimal values. The fraction of UER eliminated as urinary urea N and the contribution of urea N to total urinary N were positively associated with dietary CP (PCP was 17%. The fractions of GER excreted in the feces and utilized for anabolism decreased, whereas the fraction of GER returned to the ornithine cycle increased with dietary CP concentration (PCP and CP:DOM increased (PCP/kg DOM. The models obtained in this study contribute to the knowledge on N utilization, and they could be used in feeding models to predict urea recycling and thus to improve formulation of diets to reduce N losses that contribute to air and water pollution.

  5. Urea coated with oxidized charcoal reduces ammonia volatilization

    Directory of Open Access Journals (Sweden)

    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.

  6. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-15

    The catalytic activity of hematite (α-Fe{sub 2}O{sub 3}) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe{sub 2}O{sub 3} (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is −4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0–21 respectively. In addition, it induces magnetic moment value of 36.33 µB, which confirms the enhanced magnetic behaviour of hematite. α-Fe{sub 2}O{sub 3} nanowires (NWs) synthesized by heating iron wire in a box furnace at (750−800) °C and as synthesized α-Fe{sub 2}O{sub 3} nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe{sub 2}O{sub 3} and Raman spectrum analyses confirms the α-Fe{sub 2}O{sub 3} peaks at 410 cm{sup −1}, 500 cm{sup −1} and 616 cm{sup −1}. The needle-like shape of hematite nanowires with length ranging from 16–25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe{sub 2}O{sub 3} perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe{sub 2}O{sub 3} NWs for urea production is lower than NPs in the range of 0–1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690–1600 cm{sup −1}. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process

  7. Hydrogen production from urea wastewater using a combination of urea thermal hydrolyser-desorber loop and a hydrogen-permselective membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rahimpour, M.R.; Mottaghi, H.R.; Barmaki, M.M. [Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz71345 (Iran)

    2010-06-15

    This work presents novel application of palladium-based membrane in a wastewater treatment loop of urea plant for hydrogen production. Urea wastewater treatment loop is based on combined thermal hydrolysis-desorption operations. The wastewater of urea plant includes ammonia and urea which in the current treatment loop; urea decomposes to ammonia and carbon dioxide. The catalytic hydrogen-permselective membrane reactor is proposed for hydrogen production from desorbed ammonia of urea wastewater which much of it discharges to air and causes environmental pollution. Therefore hydrogen is produced from decomposition of ammonia on nickel-alumina catalyst bed simultaneously and permeates from reaction side to shell side through thin layer of palladium-silver membrane. Also a sweep gas is used in the shell side for increasing driving force. In this way, 4588 tons/yr hydrogen is produced and environmental problem of urea plant is solved. The membrane reactor and urea wastewater treatment loop are modeled mathematically and the predicted data of the model are consistent with the experimental and plant data that show validity of the model. Also the effects of key parameters on the performance of catalytic hydrogen-permselective membrane reactor such as the temperature, pressure, thickness of Pd-Ag layer, configuration of flow and sweep gas flow ratio were examined. (author)

  8. Salting effects on protein components in aqueous NaCl and urea solutions: toward understanding of urea-induced protein denaturation.

    Science.gov (United States)

    Li, Weifeng; Zhou, Ruhong; Mu, Yuguang

    2012-02-02

    The mechanism of urea-induced protein denaturation is explored through studying the salting effect of urea on 14 amino acid side chain analogues, and N-methylacetamide (NMA) which mimics the protein backbone. The solvation free energies of the 15 molecules were calculated in pure water, aqueous urea, and NaCl solutions. Our results show that NaCl displays strong capability to salt out all 15 molecules, while urea facilitates the solvation (salting-in) of all the 15 molecules on the other hand. The salting effect is found to be largely enthalpy-driven for both NaCl and urea. Our observations can explain the higher stability of protein's secondary and tertiary structures in typical salt solutions than that in pure water. Meanwhile, urea's capability to better solvate protein backbone and side-chain components can be extrapolated to explain protein's denaturation in aqueous urea solution. Urea salts in molecules through direct binding to solute surface, and the strength is linearly dependent on the number of heavy atoms of solute molecules. The van der Waals interactions are found to be the dominant force, which challenges a hydrogen-bonding-driven mechanism proposed previously.

  9. Reduction of Ammonia Volatilization through Mixing Urea with Humic and Fulvic Acids isolated from Palm Oil Mill Effluent Sludge

    OpenAIRE

    Shamsuddin Rosliza; Osumanu H. Ahmed; Nik M.A. Majid; Mohamadu B. Jalloh

    2009-01-01

    Problem statement: Ammonia volatilization from surface-applied urea may be substantial but it is possible to control it by mixing urea with acidic substances such as Humic Acids (HA) and Fulvic Acids (FA). The objective of this study was to compare the effects of urea-HA, urea-FA, urea-acidified (HA+FA) mixtures on ammonia loss, soil pH, soil exchangeable ammonium and available nitrate accumulation compared to urea alone. Approach: The effects of urea amended with or without HA and FA were ev...

  10. Changes in milk urea around insemination are negatively associated with conception success in dairy cows.

    Science.gov (United States)

    Albaaj, A; Foucras, G; Raboisson, D

    2017-04-01

    Dietary protein levels are a risk factor for poor reproductive performance. Conception is particularly impaired in cases of high blood or milk urea. The objective of this study was to investigate the association between conception and low milk urea or changes in milk urea around artificial insemination (AI). Data were obtained from the French Milk Control Program for a 4-yr period (2009-2012). Milk urea values between 250 and 450 mg/kg (4.3 and 7.7 mM) were considered intermediate (I), and values ≤150 mg/kg (2.6 mM) were considered low (L). Milk urea values before and after each AI were allocated into 4 classes representing the dynamics of milk urea (before-after; I-I, I-L, L-I, and L-L). Subclinical ketosis was defined using milk fat and protein contents before AI as proxies. A logistic regression with a Poisson correction and herd as a random variable was then performed on data from Holstein or all breeds of cows. The success of conception was decreased [relative risk (95% confidence interval) = 0.96 (0.94-0.99)] in low-urea cows compared with intermediate-urea cows after AI; no significant association was found for urea levels before AI. When combining data on urea before and after AI, I-L urea cows exhibited a 5 to 9% decrease in conception compared with I-I urea cows, and L-I urea cows showed no difference in conception success compared with I-I urea cows. A decreased conception success for L-L urea cows compared with I-I urea cows was observed for the analysis with cows of all breeds. This work revealed that a decrease in urea from intermediate (before AI) to low (after AI) is a risk factor for conception failure. Surveys of variation in milk urea in dairy cows close to breeding are highly recommended. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. ENSURING THE AVAILABILITY AND RELIABILITY OF UREA DOSING FOR ON-ROAD AND NON-ROAD

    Energy Technology Data Exchange (ETDEWEB)

    Barton, G; Lonsdale, B

    2003-08-24

    The purpose of this presentation is to address two important issues. The first issue is nationwide availability of urea. The second is assurance by the engine maker that the engine cannot operate without urea. In regard to the first issue, North American urea production can support SCR needs for the Heavy Duty truck industry. The existing distribution methods, pathways and technology could be utilized for urea supply with no new invention required. Urea usage and storage capacity on vehicles would support long distances between tank refills, as SCR could be initially rolled out with a limited infrastructure. The price of urea should be less than diesel fuel and urea SCR should have a fuel economy advantage over competing technologies. It can be in place by 2007. In regard to the second issue, sensor technology exists to monitor urea tank level and verify that the fluid in the tank is urea. NOx sensors are available to monitor tailpipe NOx, ensuring the entire SCR system is functioning properly, and inferring that urea is in the system. The monitoring system could be used to monitor compliance, record faults, and initiate enforcement actions as necessary. The monitoring system could initiate actions to encourage compliance.

  12. Urea nitrate, an exceptionally easy-to-make improvised explosive: studies towards trace characterization.

    Science.gov (United States)

    Tamiri, Tsippy; Rozin, Rinat; Lemberger, Nitay; Almog, Joseph

    2009-09-01

    Urea nitrate is a powerful improvised explosive, frequently used by terrorists in the Israeli arena. It was also used in the first World Trade Center bombing in New York in February 1993. It is difficult to identify urea nitrate in post-explosion debris, since only a very small fraction survives the blast. Also, in the presence of water, it readily decomposes to its original components, urea and nitric acid. It is suspected that post-blast debris of urea nitrate can be confused with ammonium nitrate, the main solid product of urea nitrate thermal decomposition. In a comprehensive study towards identification of urea nitrate in post-blast traces, a spectrophotometric technique for quantitative determination of urea nitrate was developed, and conditions were found for extraction and separation of un-exploded traces of urea nitrate with minimal decomposition. Nevertheless, out of 28 samples collected from a series of three controlled firings of urea nitrate charges, only one gave the typical adduct ion by liquid chromatography/mass spectrometry analysis. We found that urea nitrate can be extracted from solid mixtures to organic solvents by using Crown ethers as "host compounds." The adducts thus formed are solid, crystalline compounds that can be characterized by microanalysis and spectroscopic techniques.

  13. Testosterone prevents protein loss via the hepatic urea cycle in human.

    Science.gov (United States)

    Lam, Teresa; Poljak, Anne; McLean, Mark; Bahl, Neha; Ho, Ken K Y; Birzniece, Vita

    2017-04-01

    The urea cycle is a rate-limiting step for amino acid nitrogen elimination. The rate of urea synthesis is a true indicator of whole-body protein catabolism. Testosterone reduces protein and nitrogen loss. The effect of testosterone on hepatic urea synthesis in humans has not been studied. To determine whether testosterone reduces hepatic urea production. An open-label study. Eight hypogonadal men were studied at baseline, and after two weeks of transdermal testosterone replacement (Testogel, 100 mg/day). The rate of hepatic urea synthesis was measured by the urea turnover technique using stable isotope methodology, with 15 N 2 -urea as tracer. Whole-body leucine turnover was measured, from which leucine rate of appearance (LRa), an index of protein breakdown and leucine oxidation (Lox), a measure of irreversible protein loss, were calculated. Testosterone administration significantly reduced the rate of hepatic urea production (from 544.4 ± 71.8 to 431.7 ± 68.3 µmol/min; P  Testosterone treatment significantly reduced net protein loss, as measured by percent Lox/LRa, by 19.3 ± 5.8% ( P  testosterone administration ( r 2  = 0.59, P  Testosterone replacement reduces protein loss and hepatic urea synthesis. We conclude that testosterone regulates whole-body protein metabolism by suppressing the urea cycle. © 2017 European Society of Endocrinology.

  14. A study on the indirect urea dosing method in the Selective Catalytic Reduction system

    Science.gov (United States)

    Brzeżański, M.; Sala, R.

    2016-09-01

    This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution). The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio. Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

  15. Urea immunoliposome inhibits human vascular endothelial cell proliferation for hemangioma treatment

    Science.gov (United States)

    2013-01-01

    Background Urea injection has been used in hemangioma treatment as sclerotherapy. It shrinks vascular endothelial cells and induces degeneration, necrosis, and fibrosis. However, this treatment still has disadvantages, such as lacking targeting and difficulty in controlling the urea dosage. Thus, we designed a urea immunoliposome to improve the efficiency of treatment. Methods The urea liposome was prepared by reverse phase evaporation. Furthermore, the urea immunoliposome was generated by coupling the urea liposome with a vascular endothelial growth factor receptor (VEGFR) monoclonal antibody using the glutaraldehyde cross-linking method. The influence of the urea immunoliposome on cultured human hemangioma vascular endothelial cells was observed preliminarily. Results Urea immunoliposomes showed typical liposome morphology under a transmission electron microscope, with an encapsulation percentage of 54.4% and a coupling rate of 36.84% for anti-VEGFR. Treatment with the urea immunoliposome significantly inhibited the proliferation of hemangioma vascular endothelial cells (HVECs) in a time- and dose-dependent manner. Conclusions The urea immunoliposome that we developed distinctly and persistently inhibited the proliferation of HVECs and is expected to be used in clinical hemangioma treatment. PMID:24266957

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Exfoliation properties of acid-activated montmorillonites and their resulting organoclays.

    Science.gov (United States)

    Kooli, Fethi

    2009-01-20

    The intercalation process of acid-treated montmorillonite clays by a cationinc surfactant (decyltrimethylammonuium) from a hydroxide solution was affected by the temperature of acid activation. Although the cation exchange capacity of the treated clay at 90 degrees C (0.74 mequiv g(-1)) was lower compared to that treated at room temperature (0.84 mequiv g(-1)), the uptaken amount of the surfactant (1.24 mmol g(-1)) and thus the basal spacing (3.83 nm) were higher. These values depended on the initial loading concentrations. However, when the clay was treated at room temperature, the uptaken amounts of surfactant (0.81 mmol g(-1)) and the basal spacing (2.20 nm) were lower. These values were independent of the initial loading concentration. The higher basal spacing (3.83 nm) was also affected by the type of the exchange medium and the washing solution by a mixture of ethanolic solutions. The intercalation of the surfactants occurred in two different ways, and was related to exfoliation properties of the acid activated clays. The intercalated surfactant exhibited different conformations in the interlayer space and different thermal stability.

  18. Acid-activated spent bleaching earth as a sorbent for chromium (VI) in aqueous solution.

    Science.gov (United States)

    Low, K S; Lee, C K; Lee, T S

    2003-02-01

    Spent bleaching earth, an industrial waste produced after the bleaching of crude palm oil, was investigated for its potential in removing Cr(VI) from aqueous solution. The earth was treated with different amounts of sulfuric acid and under different activation temperatures. Results show that the optimum treatment process involved 10% sulfuric acid at 350 degrees C. The effects of contact time, pH, initial concentration, sorbent dosage, temperature, sorption isotherms and the presence of other anions on its sorption capacity were studied. Isotherm data could be fitted into a modified Langmuir isotherm model implying monolayer coverage of Cr(VI) on acid activated spent bleaching earth. The maximum sorption capacity derived from the Langmuir isotherm was 21.2 mg g(-1). This value was compared with those of some other low cost sorbents. Studies of anion effect on the uptake of Cr(VI) on acid activated spent bleaching earth provided the following order of suppression: EDTA >PO4(3-)>SO4(2-)>NO3(-)>Cl(-).

  19. Ammonia volatilization from enhanced-efficiency urea on no-till maize in brazilian cerrado with improved soil fertility

    OpenAIRE

    Eduardo Lopes Cancellier; Douglas Ramos Guelfi Silva; Valdemar Faquin; Bruno de Almeida Gonçalves; Leandro Lopes Cancellier; Carlos Roberto Spehar

    2016-01-01

    ABSTRACT High nitrogen losses by ammonia volatilization are expected when urea is used as the source of N. The use of controlled-release urea and urease inhibitors are possible strategies to reduce such losses and increase nitrogen use efficiency. This study aimed to evaluate nitrogen losses by ammonia volatilization from stabilized, slow and controlled release urea and its absorption by maize grown under no-till in an improved Cerrado soil. Four N sources were used: conventional urea, urea +...

  20. Design, synthesis and biological evaluation of benzamide and phenyltetrazole derivatives with amide and urea linkers as BCRP inhibitors.

    Science.gov (United States)

    Gujarati, Nehaben A; Zeng, Leli; Gupta, Pranav; Chen, Zhe-Sheng; Korlipara, Vijaya L

    2017-10-15

    Breast cancer resistant protein (BCRP/ABCG2), a 72kDa plasma membrane transporter protein is a member of ABC transporter superfamily. Increased expression of BCRP causes increased efflux and therefore, reduced intracellular accumulation of many unrelated chemotherapeutic agents leading to multidrug resistance (MDR). A series of 31 benzamide and phenyltetrazole derivatives with amide and urea linkers has been synthesized to serve as potential BCRP inhibitors in order to overcome BCRP-mediated MDR. The target derivatives were tested for their cytotoxicity and reversal effects in human non-small cell lung cancer cell line H460 and mitoxantrone resistant cell line H460/MX20 using the MTT assay. In the benzamide series, compounds 6 and 7 exhibited a fold resistance of 1.51 and 1.62, respectively at 10µM concentration which is similar to that of FTC, a known BCRP inhibitor. Compounds 27 and 31 were the most potent analogues in the phenyltetrazole series with amide linker with a fold resistance of 1.39 and 1.32, respectively at 10µM concentration. For the phenyltetrazole series with urea linker, 38 exhibited a fold resistance of 1.51 which is similar than that of FTC and is the most potent compound in this series. The target compounds did not exhibit reversal effect in P-gp overexpressing resistant cell line SW620/Ad300 suggesting that they are selective BCRP inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Effect of urea addition on giant reed ensilage and subsequent methane production by anaerobic digestion.

    Science.gov (United States)

    Liu, Shan; Ge, Xumeng; Liew, Lo Niee; Liu, Zhe; Li, Yebo

    2015-09-01

    The effect of urea addition on giant reed ensilage and sequential anaerobic digestion (AD) of the ensiled giant reed was evaluated. The dry matter loss during ensilage (up to 90 days) with or without urea addition was about 1%. Addition of 2% urea enhanced production of lactic acid by about 4 times, and reduced production of propionic acid by 2-8 times. Besides, urea addition reduced degradation of cellulose and hemicellulose, and increased degradation of lignin in giant reed during ensilage. Ensilage with or without urea addition had no significant effects on the enzymatic digestibility of giant reed, but ensilage with urea addition achieved a cumulative methane yield of 173 L/kg VS, which was 18% higher than that of fresh giant reed. The improved methane yield of giant reed could be attributed to the production of organic acids and ethanol during ensilage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Study of AOT-stabilized microemulsions of urea dispersed in carbon tetrachloride

    Energy Technology Data Exchange (ETDEWEB)

    Ruggirello, A.; Turco Liveri, V

    2003-03-15

    Measurements of some physico-chemical properties (density, viscosity, permittivity) of the urea/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/CCl{sub 4} system as a function of the volume fraction of the dispersed phase (0urea to AOT molar ratio (R{sub urea}) have been carried out at 25 deg. C. The experimental data analysis are consistent with the hypothesis that urea is entrapped as small-size molecular clusters within the hydrophilic core of the AOT reversed micelles and that this structure is preserved well above a threshold PHI value where a percolative transition occurs. Besides, X-ray diffraction spectra of samples at PHI=1, obtained by complete evaporation under vacuum of the apolar solvent of urea/AOT/CCl{sub 4} solutions, indicates that, even in the typical two-dimensional hexagonal structure of AOT liquid crystals, urea is encapsulated as uni-dimensional molecular clusters.

  3. The affect of urea on the kinetics of local unfolding processes in chymotrypsin inhibitor 2.

    Science.gov (United States)

    Lindgren, Matteus; Westlund, Per-Olof

    2010-09-01

    The dynamics of chymotrypsin inhibitor 2 (CI2) in water, as well as in 10M urea, have been studied by Molecular Dynamics simulations. The analysis aims at investigating how local protein processes are affected by urea and how the perturbation by urea on the local level manifests itself in the kinetics of the global unfolding. The results show that the effect of urea on local processes depends upon the type of process at hand. An isolated two-residue contact on the surface of CI2 has a decreased frequency of rupture in the urea solvent. This is in contrast to the increased frequency of rupture of the hydrogen bonds in secondary structure elements in the urea solvent. It is proposed that the increase in the unfolding rates of complex protein processes is based upon the retardation of the refolding rate of small scale, isolated processes. 2010 Elsevier B.V. All rights reserved.

  4. Discovery of potent, selective sulfonylfuran urea endothelial lipase inhibitors.

    Science.gov (United States)

    Goodman, Krista B; Bury, Michael J; Cheung, Mui; Cichy-Knight, Maria A; Dowdell, Sarah E; Dunn, Allison K; Lee, Dennis; Lieby, Jeffrey A; Moore, Michael L; Scherzer, Daryl A; Sha, Deyou; Suarez, Dominic P; Murphy, Dennis J; Harpel, Mark R; Manas, Eric S; McNulty, Dean E; Annan, Roland S; Matico, Rosalie E; Schwartz, Benjamin K; Trill, John J; Sweitzer, Thomas D; Wang, Da-Yuan; Keller, Paul M; Krawiec, John A; Jaye, Michael C

    2009-01-01

    Endothelial lipase (EL) activity has been implicated in HDL catabolism, vascular inflammation, and atherogenesis, and inhibitors are therefore expected to be useful for the treatment of cardiovascular disease. Sulfonylfuran urea 1 was identified in a high-throughput screening campaign as a potent and non-selective EL inhibitor. A lead optimization effort was undertaken to improve potency and selectivity, and modifications leading to improved LPL selectivity were identified. Radiolabeling studies were undertaken to establish the mechanism of action for these inhibitors, which were ultimately demonstrated to be irreversible inhibitors.

  5. LOW FRACTIONAL EXCRETION OF UREA IN HYPOTHYROIDISM INDUCED HYPONATREMIA

    OpenAIRE

    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...

  6. Single crystal: Urea bisthiourea sodium acetate synthesis, growth and characterization

    Science.gov (United States)

    Manickam, R.; Srinivasan, G.

    2017-05-01

    Crystals of urea bisthiourea sodium acetate (UBTSA) were successfully grown from an aqueous solution by slow evaporation method at room temperature. Recrystallization process was used to increase the purity of the grown crystal. The grown crystals were characterized by single crystal XRD, FT-Raman, UV and TGA/DTA analysis. Structure and unit cell parameters were determined by single crystal XRD. Functional groups of grown crystal and their modes of vibration were identified using FT-Raman spectral analysis. Absorbance percentage of the grown crystal was studied using UV analysis. Thermo gravimetric analysis and differential thermal analysis reveal that the good thermal stability of the material.

  7. Urea-formaldehyde resins: production, application, and testing

    Science.gov (United States)

    Nuryawan, A.; Risnasari, I.; Sucipto, T.; Heri Iswanto, A.; Rosmala Dewi, R.

    2017-07-01

    Urea-formaldehyde (UF) resin, one of the most important formaldehyde resin adhesives, is a polymeric condensation product of formaldehyde with urea, and being widely used for the manufacture of wood-based composite panels, such as plywood, particleboard, and fiberboard. In spite of its benefits such as fast curing, good performance in the panels (colorless), and lower cost; formaldehyde emission (FE) originated from either UF resin itself or composite products bonded by UF resins is considered a critical drawback as it affects human health particularly in indoor environment. In order to reduce the FE, lowering formaldehyde/urea (F/U) mole ratio in the synthesis of the UF resin was done. In this study, synthesis of UF resins was carried out following the conventional alkaline-acid two-step reaction with a second addition of urea, resulting in F/U mole ratio around 1.0, namely 0.95; 1.05, and 1.15. The UF resins produced were used as binder for particleboard making. The board was manufactured in the laboratory using shaving type particle of Gmelina wood, 8% UF resin based on oven dry particle, and 1% NH4Cl (20%wt) as hardener for the resin. The target of the thickness was 10 mm and the dimension was 25 cm x 25 cm. The resulted particleboard then was evaluated the physical and the mechanical properties by Japanese Industrial Standard (JIS) A 5908 (2003). Further, the resulted particleboard also was used for the mice cage’s wall in order to mimic the real living environment. After four weeks exposure in the cages, the mice then were evaluated their mucous organs as well as their blood. The experiment results were as follows: 1) It was possible to synthesis UF resins with low F/U mole ratio; 2) However, the particleboard bonded UF resins with low F/U mole ratio showed poor properties, particularly on the thickness swelling and modulus of elasticity; 3) There was no significant differences among the mucous organs of the mice after a month exposure FE originated from

  8. Growth and characterization of urea sulphamic acid single crystals

    Science.gov (United States)

    Chinnasamy, E.; Senthil, S.

    2017-05-01

    Single crystal of Urea Sulphamic acid (USA) single crystals were grown and harvested successfully at room temperature by slow solvent evaporation method. The cell parameters of the grown crystal were determined by single crystal X-ray diffraction analysis. The presence of various functional groups in the crystal is confirmed by FT-IR analysis. The optical transmission study reveals the transparency of the crystal and its optical band gap is found to be 4.74 eV. The crystal quality can be further examined by the time resolved Photoluminescence Spectroscopy. Laser damage threshold study was also carried for the grown crystal.

  9. Solid state NMR studies of the guest molecules in urea inclusion compounds

    OpenAIRE

    Yang, Xiaorong

    2007-01-01

    Urea inclusion compounds are suitable to study the dynamics of the guest molecules and the interactions between guest and guest as well as guest and host molecules under very confined spatial conditions. The understanding of the functional group interactions and the molecular dynamics can provide useful information for practical applications. 1,10-Dibromodecane and 1,11-dibromoundecane/urea inclusion compounds The structural features of urea inclusion compounds with the guest molecules...

  10. Flow injection analysis biosensor for urea analysis in adulterated milk using enzyme thermistor.

    Science.gov (United States)

    Mishra, Geetesh K; Mishra, Rupesh K; Bhand, Sunil

    2010-12-15

    Urea in adulterated milk is one of the major health concern, it is especially harmful to pregnant women, children, and the sick. A sophisticated and reliable detection system is needed to replace current diagnostic tools for the urea in the milk. In this work, we report a flow injection analysis-enzyme thermistor (FIA-ET) bio-sensing system for monitoring of urea in adulterated milk. This biosensor was made of the covalently immobilized enzyme urease (Jack bean) on controlled pore glass (CPG) and packed into a column inside thermistor, which selectively hydrolysed the urea present in the sample. The specific heat registered from the hydrolysis of urea was found proportional to the concentration of urea present in the milk sample. The biosensor showed a linear range 1-200 mM, with % R.S.D. 0.96 for urea in 100 mM phosphate buffer, pH 7.2. Good recoveries were obtained (97.56-108.7%) for urea up to 200 mM in the spiked milk samples with % R.S.D. 0.95. In the adulterated milk, a simple filtration strategy and matrix matching technique was used to analyse urea. The response time of the sensor was evaluated for urea, which was 2 min, and it gives satisfactory output. A good comparison was observed between the urea concentrations measured through FIA-ET and the colorimetric method. These results indicate that utilizing this system could be very effective to detect low and high level of urea in adulterated milk. The immobilized urease column exhibited a good operational stability up to 180 days when used continuously at room temperature. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Solution combustion synthesis of α-Al2O3 using urea

    OpenAIRE

    Zhuravlev, V. D.; Bamburov, V. G.; Beketov, A. R.; Perelyaeva, L. A.; BAKLANOVA I.V.; Sivtsova, O. V.; Vasil'ev, V. G.; Vladimirova, E. V.; Shevchenko, V.G.; Grigorov, I. G.

    2013-01-01

    The processes involved in the solution combustion synthesis of α-Al2O3 using urea as an organic fuel were investigated. The data describing the influence of the relative urea content on the characteristic features of the combustion process, the crystalline structure and the morphology of the aluminium oxide are presented herein. Our data demonstrate that the combustion of stable aluminium nitrate and urea complexes leads to the formation of α-alumina at temperatures of approximately 600-800 °...

  12. Urea, but not guanidinium, destabilizes proteins by forming hydrogen bonds to the peptide group

    OpenAIRE

    Lim, Woon Ki; Rösgen, Jörg; Englander, S. Walter

    2009-01-01

    The mechanism by which urea and guanidinium destabilize protein structure is controversial. We tested the possibility that these denaturants form hydrogen bonds with peptide groups by measuring their ability to block acid- and base-catalyzed peptide hydrogen exchange. The peptide hydrogen bonding found appears sufficient to explain the thermodynamic denaturing effect of urea. Results for guanidinium, however, are contrary to the expectation that it might H-bond. Evidently, urea and guanidiniu...

  13. Pembuatan Urea Pelepasan Terkendali Melalui Pelapisan Dengan Amilum Menggunakan Teknologi Fluidized Bed Spray

    OpenAIRE

    Ivanky, Khair; Wahyudi, Rizki Tri; Suherman, S

    2012-01-01

    Indonesia is one of the largest consumer of nitrogen fertilizer. However, the use of fertilizers has been inefficient because 20-70% content of nitrogenin fertilizers quickly dissolvein water. Therefore, the necessary coating urea with polymer to improve the efficiency of fertilizer nitrogen absorbed so much more. One way to improve the efficiency of urea fertilizer is urea coated with the coating material known as Slow Release Fertilizer (SRF) which is a nitrogen-controlled components. Coati...

  14. Urea stimulation of KCl cotransport induces abnormal volume reduction in sickle reticulocytes

    OpenAIRE

    Joiner, Clinton H.; Kirk Rettig, R.; Jiang, Maorong; Risinger, Mary; Franco, Robert S.

    2007-01-01

    KCl cotransport (KCC) activity contributes to pathologic dehydration in sickle (SS) red blood cells (RBCs). KCC activation by urea was measured in SS and normal (AA) RBCs as Cl-dependent Rb influx. KCC-mediated volume reduction was assessed by measuring reticulocyte cellular hemoglobin concentration (CHC) cytometrically. Urea activated KCC fluxes in fresh RBCs to levels seen in swollen cells, although SS RBCs required lower urea concentrations than did normal (AA) RBCs. Little additional KCC ...

  15. Silicone Doped Chitosan-Acrylamide Coencapsulated Urea Fertilizer: An Approach to Controlled Release Fertilizers

    OpenAIRE

    Siafu, Sempeho Ibahati

    2017-01-01

    In the absence of special management practices, urea is known to undergo chemical transformations resulting in severe losses (≈60–70%) of total fertilizer applied. In an attempt to design urea controlled release fertilizers in order to counterbalance the 60–70% loss, urea was cross-linked with chitosan and acrylamide under refluxed in situ copolymerization technique; the procedures were repeated with silicone doping prior cross-linking with MBA. The particles were characterized with FTIR/ATR,...

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

    OpenAIRE

    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 ...

  17. The Effect of Nanoclay on Physicochemical, Mechanical and Thermal Properties of New Urea- Glyoxal Resin

    OpenAIRE

    hamed yonesi korekhili; reza naghdi; mojtaba amiri

    2015-01-01

    In order to eliminate the harm of formaldehyde from panels bonded with UF resin to environment and human health at the source, the low volatile and nontoxic aldehyde of glyoxyal (G) was chosen to react with urea (U) to prepare the wood adhesive of urea-glyoxal (UG) resin a substitute for urea-formaldehyde (UF) resin. The urea-glyoxal (UG) resin was synthesized under weak acid conditions, and its different properties were measured. Also, the effect of nanoclay on physico-chemical, thermal and ...

  18. PCDD/F reduction in incinerator flue gas by adding urea to RDF feedstock.

    Science.gov (United States)

    Ruokojärvi, P; Tuppurainen, K; Mueller, C; Kilpinen, P; Ruuskanen, J

    2001-04-01

    The effect of urea on PCDD/F formation in a pilot incinerator was studied by incinerating urea with refuse-derived fuel (RDF) at three concentrations (0.1%, 0.5% and 1.0%, of the fuel feed). A distinct reduction in both PCDD/F and chlorophenol concentrations could be noticed when urea was introduced into the system. Partial-least-square (PLS) analysis of the data showed the importance of certain chlorophenol isomers as PCDD/F precursors, pointing to the possibility that the impact point of the urea inhibitor could be before the precursor molecules, i.e. chlorophenols, have been formed.

  19. Enhanced Productivity of a Lutein-Enriched Novel Acidophile Microalga Grown on Urea

    National Research Council Canada - National Science Library

    Casal, C; Cuaresma, M; Vega, J.M; Vilchez, C

    .... In this work, we show that mixotrophic cultivation on urea efficiently enhances growth and productivity of an acidophile microalga up to typical values for common microalgae, therefore approaching...

  20. Optical Tweezers Analysis of Double-Stranded DNA Denaturation in the Presence of Urea

    Science.gov (United States)

    Zhu, Chunli; Li, Jing

    2016-09-01

    Urea is a kind of denaturant prone to form hydrogen bonds with the electronegative centers of the nitrogenous bases, threatening the stability of hydrogen bonds between DNA base pairs. In this paper, the stability and stiffness of DNA double helix influenced by urea are investigated at single-molecule level using optical tweezers. Experimental results show that DNA's double helix stability and stiffness both decrease with increasing urea concentration. In addition, the re-forming of ruptured hydrogen bonds between the base pairs is blocked by urea as the tension on DNA is released.

  1. Urea thermolysis and NO{sub x} reduction with and without SCR catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Howard L.; DaCosta, Herbert F.M. [Cummins Technology Center, Cummins Inc., MC 50183, 1900 McKinley Avenue, Columbus, IN 47201 (United States)

    2003-10-31

    Urea-selective catalytic reduction (SCR) has been a leading contender for removal of nitrogen oxides (deNO{sub x}) 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){sub x}(HNCO){sub 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 NO{sub x} 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.

  2. Urea stimulation of KCl cotransport induces abnormal volume reduction in sickle reticulocytes.

    Science.gov (United States)

    Joiner, Clinton H; Rettig, R Kirk; Jiang, Maorong; Risinger, Mary; Franco, Robert S

    2007-02-15

    KCl cotransport (KCC) activity contributes to pathologic dehydration in sickle (SS) red blood cells (RBCs). KCC activation by urea was measured in SS and normal (AA) RBCs as Cl-dependent Rb influx. KCC-mediated volume reduction was assessed by measuring reticulocyte cellular hemoglobin concentration (CHC) cytometrically. Urea activated KCC fluxes in fresh RBCs to levels seen in swollen cells, although SS RBCs required lower urea concentrations than did normal (AA) RBCs. Little additional KCC stimulation by urea occurred in swollen AA or SS RBCs. The pH dependence of KCC in "euvolemic" SS RBCs treated with urea was similar to that in swollen cells. Urea triggered volume reduction in SS and AA reticulocytes, establishing a higher CHC. Volume reduction was Cl dependent and was limited by the KCC inhibitor, dihydro-indenyl-oxyalkanoic acid. Final CHC depended on urea concentration, but not on initial CHC. Under all activation conditions, volume reduction was exaggerated in SS reticulocytes and produced higher CHCs than in AA reticulocytes. The sulfhydryl-reducing agent, dithiothreitol, normalized the sensitivity of KCC activation to urea in SS RBCs and mitigated the urea-stimulated volume decrease in SS reticulocytes, suggesting that the dysfunctional activity of KCC in SS RBCs was due in part to reversible sulfhydryl oxidation.

  3. Structure and Dynamics of Urea/Water Mixtures Investigated by Vibrational Spectroscopy and Molecular Dynamics Simulation

    Science.gov (United States)

    Carr, J. K.; Buchanan, L. E.; Schmidt, J. R.; Zanni, M. T.; Skinner, J. L.

    2013-01-01

    Urea/water is an archetypical “biological” mixture, and is especially well known for its relevance to protein thermodynamics, as urea acts as a protein denaturant at high concentration. This behavior has given rise to an extended debate concerning urea’s influence on water structure. Based on a variety of methods and of definitions of water structure, urea has been variously described as a structure-breaker, a structure-maker, or as remarkably neutral towards water. Because of its sensitivity to microscopic structure and dynamics, vibrational spectroscopy can help resolve these debates. We report experimental and theoretical spectroscopic results for the OD stretch of HOD/H2O/urea mixtures (linear IR, 2DIR, and pump-probe anisotropy decay) and for the CO stretch of urea-D4/D2O mixtures (linear IR only). Theoretical results are obtained using existing approaches for water, and a modification of a frequency map developed for acetamide. All absorption spectra are remarkably insensitive to urea concentration, consistent with the idea that urea only very weakly perturbs water structure. Both this work and experiments by Rezus and Bakker, however, show that water’s rotational dynamics are slowed down by urea. Analysis of the simulations casts doubt on the suggestion that urea immobilizes particular doubly hydrogen bonded water molecules. PMID:23841646

  4. NUEVOS SISTEMAS SUPRAMOLECULARES: COMPUESTOS DE INCLUSION DE MATRICES BINARIAS DE UREA Y TIOUREA

    OpenAIRE

    MERCHAN VELEZ, JUAN EUGENIO

    2002-01-01

    Esta tesis constituye una incursión y contribución al conocimiento de la química supramolecular y de la química de las interacciones sutiles en el ámbito de compuestos polimoleculares derivados de las matrices binarias de urea y tiourea. Se sintetizaron y caracterizaron los compuestos de inclusión de las matrices aniónicas urea/cloruro, urea/bromuro, urea/yoduro, tiourea/cloruro, tiourea/bromuro, tiourea/yoduro incorporando como huésped el catión diquinuclidonio. Las matrices están f...

  5. Mechanistic and functional insights into fatty acid activation in Mycobacterium tuberculosis

    Science.gov (United States)

    Arora, Pooja; Goyal, Aneesh; Natarajan, Vivek T; Rajakumara, Eerappa; Verma, Priyanka; Gupta, Radhika; Yousuf, Malikmohamed; Trivedi, Omita A.; Mohanty, Debasisa; Tyagi, Anil; Sankaranarayanan, Rajan; Gokhale, Rajesh S.

    2009-01-01

    The recent discovery of fatty acyl-AMP ligases (FAALs) in Mycobacterium tuberculosis (Mtb) provided a new perspective to fatty acid activation dogma. These proteins convert fatty acids to corresponding adenylates, which is an intermediate of acyl-CoA-synthesizing fatty acyl-CoA ligases (FACLs). Presently, it is not evident how obligate pathogens like Mtb have evolved such new themes of functional versatility and whether the activation of fatty acids to acyl-adenylates could indeed be a general mechanism. Here, based on elucidation of the first structure of a FAAL protein and by generating loss- as well as gain-of-function mutants that interconvert FAAL and FACL activities, we demonstrate that an insertion motif dictates formation of acyl-adenylate. Since FAALs in Mtb are crucial nodes in biosynthetic network of virulent lipids, inhibitors directed against these proteins provide a unique multi-pronged approach of simultaneously disrupting several pathways. PMID:19182784

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

    Science.gov (United States)

    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.

  7. Acid activation of Bentonite for use as a vegetable oil bleaching agent

    Directory of Open Access Journals (Sweden)

    Villemin, D.

    2009-09-01

    Full Text Available The design of various experiments in order to assess and simulate the effects of the acid activation of an Algerian bentonite on the bleaching capacity of Colza oil is described. Three key parameters of the acidic activation, namely acid concentration, contact time and temperature, were considered. The calculations made indicated that all variables display advantageous effects up to a certain level on the effectiveness of bleaching, regarded as the responsefunction. The acid concentration exerts a predominant individual effect as compared to the other parameters. Some small interactions between parameters were considered. High bleaching capacity reached 99% as optimal activation. Under accurate statistical measurements, synergy phenomena could be observed. Excessive activation is discussed in terms of loss in both porosity and acid strength.Se describe el empleo del diseño de experimentos con objeto de evaluar y simular los efectos de la activación ácida de bentonita procedente de Argelia en la decoloración de aceite de colza. Para ello se evaluaron tres variables: concentración de ácido, tiempo de contacto y temperatura. Empleando como variable respuesta la efectividad en el proceso de decoloración, los resultados obtenidos indicaron que las tres variables proporcionaban un efecto beneficioso hasta un determinado nivel, siendo la concentración de ácido, el factor que producía una mayor variación en la variable respuesta. Se observaron pequeñas interacciones entre los efectos estudiados. Se obtuvo un 99 % de capacidad para la decoloración como valor óptimo. El tratamiento estadístico realizado indicó la presencia de un efecto sinérgico. Una activación excesiva se puede explicar en términos de una pérdida de porosidad y fuerza ácida.

  8. A Urea Potentiometric Biosensor Based on a Thiophene Copolymer

    Directory of Open Access Journals (Sweden)

    Cheng-Yuan (Kevin Lai

    2017-03-01

    Full Text Available A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid (P(3HT-co-3TAA was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO glass electrodes. Urease (Urs was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  11. PLATELET ADHESION TO POLYURETHANE UREA UNDER PULSATILE FLOW CONDITIONS

    Science.gov (United States)

    Navitsky, Michael A.; Taylor, Joshua O.; Smith, Alexander B.; Slattery, Margaret J.; Deutsch, Steven; Siedlecki, Christopher A.; Manning, Keefe B.

    2014-01-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s−1. The aim of the current work is to determine platelet adhesion properties to the polyurethane urea surface as a function of time varying shear exposure. A rotating disk system is used to study the influence of steady and pulsatile flow conditions (e.g. cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments retain the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk is rotated in platelet rich bovine plasma for two hours with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow is found to exponentially decay with increasing shear rate. Adhesion levels are found to depend upon peak platelet flux and shear rate regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

  12. Construction of ferrocene modified conducting polymer based amperometric urea biosensor.

    Science.gov (United States)

    Dervisevic, Muamer; Dervisevic, Esma; Senel, Mehmet; Cevik, Emre; Yildiz, Huseyin Bekir; Camurlu, Pınar

    2017-07-01

    Herein, an electrochemical urea sensing bio-electrode is reported that has been constructed by firstly electropolymerizing 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)aniline monomer (SNS-Aniline) on Pencil Graphite Electrode (PGE), then modifying the polymer coated electrode surface with di-amino-Ferrocene (DAFc) as the mediator, and lastly Urease enzyme through glutaraldehyde crosslinking. The effect of pH, temperature, polymer thickness, and applied potential on the electrode current response was investigated besides performing storage and operational stability experiments with the interference studies. The resulting urea biosensor's amperometric response was linear in the range of 0.1-8.5mM with the sensitivity of 0.54μA/mM, detection limit of 12μM, and short response time of 2s. The designed bio-electrode was tested with real human blood and urine samples where it showed excellent analytical performance with insignificant interference. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. FITC-tagged macromolecule-based alginate microspheres for urea sensoring

    Science.gov (United States)

    Joshi, Abhijeet; Chaudhari, Rashmi; Srivastava, Rohit

    2014-04-01

    Urea is an important biomarker for identification of kidney diseases. Early urea detection using a specific and sensitive technique can significantly reduce the mortality of patients. The research aims at developing fluorescence-based FITCmediated pH and urea measurement. A system containing FITC-dextran in alginate microspheres was developed using air-driven atomization. pH/Urea biosensor was characterized using optical microscopy, SEM, and CLSM. Urea biosensing studies were performed by exposing different standard solutions of pH and urea standard solutions using fluorescence spectroscopy (λex=488 nm and λem=520 nm). FITC-dextran was entrapped using an encapsulation unit and alginate microspheres were formed. The microspheres were found to be uniform and spherical in nature with sizes (50±10μ). FITC-dextran was found to be uniformly distributed in the alginate microspheres as per the CLSM scans. Urea biosensing studies indicate that a linear correlation was observed with increasing urea concentrations. The said microspheres can be used to detect changes in pH from 4-8 units owing to its linear response in this range. FITC dextran loaded alginate microspheres showed an improved range of detection upto 7 mM in comparison to 1.5 mM when in solution phase in a study with urea concentrations from 0-50 mM. The pH and urea detection was accurate to an extent of interday variation of 5%. FITC-dextran loaded alginate microspheres show a great potential for usage as a pH and urea biosensor for early detection of kidney diseases.

  14. [Source analysis of urea-N in Lake Taihu during summer].

    Science.gov (United States)

    Han, Xiao-Xi; Zhu, Guang-Wei; Xu, Hai; Wilhelm, Steven W; Qin, Bo-Qiang; Li, Zhao-Fu

    2014-07-01

    To study the effect of urea nitrogen on the ecosystem of Lake Taihu, we conducted urea and various nitrogen analysis for the water samples collected from the lake and surrounding rivers during summer. The ecological index analysis of 82 sites in rivers and lake yielded the following results: (1) The urea nitrogen contents in Taihu ranged from 0.011 to 0.161 mg x L(-1), which was high in the northwest and low in the southeast, related to the main pollution sources distribution of its drainage basin. (2) The dissolved nitrogen was dominated by inorganic nitrogen and the ratio between ammonia nitrogen and nitrate nitrogen was 5: 1. The average percentage of urea nitrogen in total nitrogen, dissolved nitrogen, dissolved organic nitrogen and bioavailable nitrogen was respectively 2.28%, 5.91%, 15.86%, and 6.22%, which showed a significant ecological function in Taihu. (3) Urea nitrogen concentration in river was more than twice that in lake, and the lake river concentration was slightly higher than the river into the lake. (3) In Taihu, there was a transformation relationship between urea nitrogen and the nitrogen in other forms. It showed that urea nitrogen had a significant positive correlation with permanganate index and the other forms of nitrogen, and a significant negative correlation with dissolved oxygen. In addition, urea nitrogen was weakly and positively correlated with chlorophyll a, while closely related to the spatial distribution of benthos and zooplankton species. All the results above showed that urea nitrogen was the bridge of organic and inorganic nitrogen transformation, and was the sign of nitrogen cycle of Lake Taihu, which was controlled by the circulating rate. High nitrogen content (especially the organic nitrogen) and low dissolved oxygen content were the key contributors to the increased urea nitrogen content. In Taihu, the urea nitrogen content was affected by both exogenous input and endogenous release.

  15. Effects of Controlled Release Urea on Wheat Yield and Nitrogen Utilization Efficiency Under Different Applied Conditions

    Directory of Open Access Journals (Sweden)

    XIA Wei-guang

    2014-02-01

    Full Text Available The field trial was conducted to study the effects of different nitrogen fertilizer applications on winter wheat yield, nitrogen utilization efficiency and economic benefit. 7 treatments were designed as CK(no nitrogen fertilizer applied, 100%PU10/0(conventional urea applied before sowing, N rate was 240 kg·hm-2, 100%PU6/4(conventional urea applied before sowing and at jointing with the ratio of 6∶4, N rate was 240 kg·hm-2, 80%PU6/4(conventional urea applied before sowing and at jointing with the ratio of 6∶4, N rate was 192 kg·hm-2, 100%CRU(resin coated controlled release urea applied before sowing, N rate was 240 kg·hm-2, 80%CRU(resin coated controlled release urea applied before sowing, N rate was 192 kg·hm-2, and 40%CRU+40%PU(resin coated controlled release urea and conventional urea applied before sowing, N rate was 192 kg·hm-2. The results showed that no matter on the efficiency of yield or that of nitrogen, resin coated controlled-release urea(CRU was better when compared with conventional urea(PU. Especially, the combined application treatment(40%CRU+40%PUwas the best with achieving the highest wheat yield of 7 709 kg·hm-2, the highest N fertilizer utilization efficiency of 36.44% and the maximum net income of 15 946 yuan·hm-2. And it could not only increase winter wheat yield with reducing the nitrogen fertilizer application, but also improve N fertilizer utilization efficiency and owe the highest ratio of output to input. Therefore, the combined application of the resin coated controlled-release urea and conventional urea(40%CRU+40%PUwas the optimal nitrogen fertilizer treatment under the conditions of this experiment.

  16. Controlling Ammonia Volatilization by Mixing Urea with Humic Acid, Fulvic Acid, Triple Superphosphate and Muriate of Potash

    OpenAIRE

    Shamsuddin Rosliza; Osumanu H. Ahmed; Nik M.A. Majid

    2009-01-01

    Problem statement: Inefficient use of inorganic fertilizer such as urea is caused by substantial losses of ammonia when urea is surface-applied. Ammonia losses can be controlled by adding acidic material such as TSP, HA or FA. In order to reduce ammonia loss and retain soil exchangeable ammonium and available nitrate as well as producing complete organic based fertilizer, this study was conducted to compare the effects of urea-TSP-MOP, urea-TSP-MOP-HA, urea-TSP-MOP-FA, urea-TSP-MOP-acidified ...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

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

    2008-04-20

    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.

  19. iiv vito estimation of body composition in cattle with tritium and urea

    African Journals Online (AJOL)

    scintillation counter using 1,0 g duplicate aliquots of radio-active water in l0 ml scintillation liquid as described by Meissner & Bieler (1975). Apparent urea or TOH space was calculated from the ratio of urea or tritium infused to the concentration at equilibrium,or at various other stages prior to equilibrium, after correction for ...

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    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.

  2. Study of a composite from reactive blending of methylol urea resin ...

    African Journals Online (AJOL)

    GREGO

    2007-03-19

    Mar 19, 2007 ... natural rubber (NR) with starch and studied both rheo- logical and curing ... sodium hydroxide pellets and sucrose were reagent grades products ... Resin synthesis. Trimethylol urea was prepared by reacting one mole (6.0 g) of urea with three moles (24.3 ml) of 37% (w/v) formaldehyde. Sodium dihydrogen ...

  3. Analysis of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Bunichiro Tomita; Chung-Yun Hse

    1995-01-01

    The 13C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation...

  4. Characteristics of urea-formaldehyde resins as related to glue bond quality of southern pine particleboard

    Science.gov (United States)

    C. -Y. Hse

    1974-01-01

    Forty-five urea resins were formulated and replicated by factorial arrangement of three variables: molar ratio of formaldehyde to urea (1.5, 1.7, 1.9, 2.1, and 2.3), reactant concentration (35, 42.5, and 50%), and reaction temperature (75°, 85°, and 95°C).

  5. Urea-ensiled rice straw as a feed for cattle in Thailand

    African Journals Online (AJOL)

    urea, with or without small amounts of salt and/or molasses. The wet straw is covered with a plastic sheet and ensiled for about 3weeks before it is fed to the animals. The urea-treated straw should be removed or the stack opened for one day ...

  6. Improving ryegrass-clover pasture dry matter yield and urea efficiency with gibberellic acid.

    Science.gov (United States)

    Zaman, Mohammad; Ghani, Anwar; Kurepin, Leonid V; Pharis, Richard P; Khan, Shabana; Smith, Terry J

    2014-09-01

    The effects of spraying gibberellic acid (GA3) at 20 or 30 g ha(-1), with or without application of urea, on pasture dry matter (DM) yield, herbage nitrogen (N) concentration and feed quality were investigated in 2011 and 2012 for managed pastoral systems in New Zealand across a range of sites, in both autumn and spring. On the Waikato site (autumn and spring, 2012), and at all five sites in 2011, liquid urea applied with GA3 at 20 or 30 g ha(-1) consistently produced significantly higher pasture shoot DM yield, relative to liquid urea alone. Application of GA3 alone reduced feed quality by lowering metabolizable energy, crude protein and organic matter digestibility values. However, a reduced feed quality was not observed when GA3 was applied together with liquid urea. Liquid urea applied with GA3 also reduced total N and nitrate-N concentration in herbage, relative to liquid urea applied alone. Application of GA3 together with liquid urea provides an opportunity for the strategic use of urea to meet both production and environmental goals. © 2014 Society of Chemical Industry.

  7. Effect of different doses of urea on the uptake of cadmium from soil ...

    African Journals Online (AJOL)

    The present investigation was conducted to study the effect of different doses of urea on cadmium uptake by canola (Brassica napus L.) applied in full and split doses. Nine different treatments of urea used were: 0 (control), 60, 90, 120 and 150 kg/ha applied to soil as full doses before sowing, and 60, 90, 120, and 150 kg/ha ...

  8. Effect of different doses of urea on the uptake of cadmium from soil ...

    African Journals Online (AJOL)

    Yomi

    2012-01-19

    Jan 19, 2012 ... The present investigation was conducted to study the effect of different doses of urea on cadmium uptake by canola (Brassica napus L.) applied in full and split doses. Nine different treatments of urea used were: 0 (control), 60, 90, 120 and 150 kg/ha applied to soil as full doses before sowing, and 60, 90,.

  9. Water-mediated interactions between trimethylamine-N-oxide and urea.

    Science.gov (United States)

    Hunger, Johannes; Ottosson, Niklas; Mazur, Kamila; Bonn, Mischa; Bakker, Huib J

    2015-01-07

    The amphiphilic osmolyte trimethylamine-N-oxide (TMAO) is commonly found in natural organisms, where it counteracts biochemical stress associated with urea in aqueous environments. Despite the important role of TMAO as osmoprotectant, the mechanism behind TMAO's action has remained elusive. Here, we study the interaction between urea, TMAO, and water in solution using broadband (100 MHz-1.6 THz) dielectric spectroscopy. We find that the previously reported tight hydrogen bonds between 3 water molecules and the hydrophilic amine oxide group of TMAO, remain intact at all investigated concentrations of urea, showing that no significant hydrogen bonding occurs between the two co-solutes. Despite the absence of direct TMAO-urea interactions, the solute reorientation times of urea and TMAO show an anomalous nonlinear increase with concentration, for ternary mixtures containing equal amounts of TMAO and urea. The nonlinear increase of the reorientation correlates with changes in the viscosity, showing that the combination of TMAO and urea cooperatively enhances the hydrogen-bond structure of the ternary solutions. This nonlinear increase is indicative of water mediated interaction between the two solutes and is not observed if urea is combined with other amphiphilic solutes.

  10. Effects of bentonite on plasma urea and creatinine of wistar albino rats.

    African Journals Online (AJOL)

    The in vivo effect of Nigerian calcium bentonite clay on wistar albino rat plasma urea and creatinine levels were investigated. The rats were fed for a period of four weeks with varying concentrations of the bentonite clay, and the urea and creatinine levels determined using spectrophotometric methods. Test results showed ...

  11. 76 FR 35405 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2011-06-17

    ... the individual members of the Commonwealth of Independent States. See Solid Urea From the Union of... Socialist Republics to the Commonwealth of Independent States and the Baltic States and Opportunity to... entitled ``Solid Urea from the Russian Federation--Affiliation Analysis.'' Level of Trade To the extent...

  12. Effect of replacing wheat bran with spineless cactus plus urea in ...

    African Journals Online (AJOL)

    Feeding behaviour was not altered by replacing wheat bran with spineless cactus plus urea. Nitrogen retention increased by 0.10 g/day, while plasmatic urea nitrogen increased by 0.20 mg/day for every 1% level of replacement. The maximum production of microbial nitrogen (15.9 g/day) and microbial protein synthesis ...

  13. Influence of urea application on growth, yield and mineral uptake in ...

    African Journals Online (AJOL)

    A pot experiment was conducted in a wire netting green house in order to assess the beneficial effect of urea on corn cultivars (C-20 and C-79) differing in yield production. Corn plants were grown in loam soil with alkaline in reaction. Application of varying urea levels did not change the physico-chemical properties of soil.

  14. Urea recycling in muskrats (Ondatra zibethicus): a potential nitrogen-conserving tactic?

    Science.gov (United States)

    Campbell, K L; MacArthur, R A

    1997-01-01

    The rate of 14C-urea hydrolysis was determined in 32 field-acclimatized muskrats maintained on natural diets during spring, summer, fall, and winter. We hypothesized that urea recycling occurs in muskrats during all seasons and that the conservation of tissue nitrogen via this mechanism is most prevalent in fall and winter, when forage protein levels are lowest. Muskrats exhibited higher rates of urea hydrolysis and a lower serum urea nitrogen-to-creatinine ratio in fall and winter than in spring and summer. Even after correcting for seasonal differences in blood urea pool size, the adjusted rate of urea hydrolysis was 67% higher in fall and winter than in spring and summer. There was no evidence that the maintenance nitrogen requirements of muskrats fed natural vegetation were affected by seasonal changes in the amino acid composition of the diet. We suggest that increased levels of urea recycling, coupled with adaptive mechanisms for reducing nitrogen excretion and possibly conserving carbon skeletons of essential amino acids, may allow muskrats to reduce their nitrogen requirements on fall and winter diets. Our finding that 14C-urea hydrolysis occurred during all four sampling periods suggests that nitrogen derived from this source may also be critical to supporting large hindgut microbe populations that enable this rodent to exploit the appreciable fiber content of its aquatic plant diet throughout the year.

  15. Psilocin, psilocybin, serotonin and urea in Panaeolus cyanescens from various origin

    NARCIS (Netherlands)

    Stijve, T.

    1992-01-01

    The occurrence of tryptamine derivatives and urea in Panaeolus cyanescens, also known as Copelandia cyanescens, from Australia, Hawaii and Thailand was investigated. All 70 collections contained psilocin, serotonin and urea. Those from Hawaii were also relatively rich in psilocybin, whereas the

  16. [Conductometric microdosage of blood and urine urea by use of a semi-automatic analyser].

    Science.gov (United States)

    Hanss, M; Policard, C; Pre, J

    1977-01-01

    The authors present the principle of a new method of urea estimation based on conductimetry. Its results are compared with those given by the colorimetric method using diacetylmonoxime. Correlation of the results was satisfactory. With the apparatus studied, it was possible to estimate very simply plasma and urinary urea with low volume samples 10 microliter). The titration took 30 seconds.

  17. Effect of urea additive on the thermal decomposition kinetics of flame retardant greige cotton nonwoven fabric

    Science.gov (United States)

    Sunghyun Nam; Brian D. Condon; Robert H. White; Qi Zhao; Fei Yao; Michael Santiago Cintrón

    2012-01-01

    Urea is well known to have a synergistic action with phosphorus-based flame retardants (FRs) in enhancing the FR performance of cellulosic materials, but the effect of urea on the thermal decomposition kinetics has not been thoroughly studied. In this study, the activation energy (Ea) for the thermal decomposition of greige...

  18. High molecular weight polyurethanes and a polyurethane urea based on 1,4-butanediisocyanate

    NARCIS (Netherlands)

    Spaans, CJ; de Groot, JH; Dekens, FG; Pennings, AJ

    New biomedical polyurethanes and a polyurethane urea based on epsilon-caprolactone and 1,4-butanediisocyanate have been developed. On degradation, only non-toxic products are produced. The polyurethane urea with poly(epsilon-caprolactone) soft segments and butanediisocyanate/butanediamine hard

  19. urea as a host for distinction of phthalic acid and terephthalic acid

    Indian Academy of Sciences (India)

    and adipic acid interact with 1, led to cocrystals with the host 1 through hydrogen bond interactions. The hydrogen bonds that ... cases anions interacts with the urea portion of the host, while in the co-crystals the hydrogen bonded urea taps are retained. ... and synthesis of hosts for selective binding of car- boxylic acids have ...

  20. Reduced loss of NH 3 by coating urea with biodegradable polymers ...

    African Journals Online (AJOL)

    In agricultural lands, the loss of NH3 from surface-applied urea and micronutrient deficiencies are the two most common problems, which can be solved by using coated urea with micronutrients and biodegradable natural materials. These coatings can improve the nutrient status in the soil and simultaneously reduce ...

  1. Effect of lime, urea and triple super phosphate on nitrogen and ...

    African Journals Online (AJOL)

    Liming and P application enhanced soil N and P mineralisation, respectively but urea retarded both. Key Words: Acidity, Andosol, incubation, Kenya, lime, TSP, urea. RÉSUMÉ Une étude a été conduite pour examiner la mineralisation du P et de l'N dans un Andosol mollique acide par l'incubation pendant 120 jours au ...

  2. A Role For Ca 2+ in the Thermal and Urea Denaturation of ...

    African Journals Online (AJOL)

    Giant African snail (Achatina achatina) becomes dormant (aestivate) under harsh environmental conditions like dry seasons. During this period the animal accumulates urea and is faced with thermal death. The stability towards thermal and urea denaturation of haemocyanin from aestivating and nonaestivating A. achatina ...

  3. A study of the effects of oral contraceptives on plasma urea of Wistar ...

    African Journals Online (AJOL)

    Oral contraceptives such as Microgynon a combined pill (0.15mg levonorgestrel and 0.03mg ethinylestradiol) and Primolut -N a mini pill (5mg norethisterone) were investigated for their in-vivo effects on wistar albino rat rattus rattus plasma urea levels. Test results showed that the drugs had a lowering effect on plasma urea ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Chermahini, Alireza Najafi, E-mail: anajafi@cc.iut.ac.ir [Department of Chemistry, Isfahan University of Technology, Isfahan, 841543111, Islamic Republic of Iran (Iran, Islamic Republic of); Teimouri, Abbas [Chemistry Department, Payame Noor University, 19395-4697, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Farrokhpour, Hossein [Department of Chemistry, Isfahan University of Technology, Isfahan, 841543111, Islamic Republic of Iran (Iran, Islamic Republic of)

    2014-11-30

    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 ΔE{sub g} 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.

  5. Voluntary intake of maize stover supplemented by urea lick in dorper ...

    African Journals Online (AJOL)

    Ten Dorper (16.0 to 37.0 kg) and Local (12.0 to 28.5kg) rams were used to determine the voluntary intake, digestibility, nitrogen retention of maize stover and live weight change. Dietary treatments were maize stover offered to meet the requirement for maintenance with urea lick, 1.5 or 2 times maintenance with urea lick.

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

    DEFF Research Database (Denmark)

    Reed, Galen D; von Morze, Cornelius; Verkman, Alan S

    2016-01-01

    In vivo spin spin relaxation time (T2) heterogeneity of hyperpolarized [(13)C,(15)N2]urea in the rat kidney was investigated. Selective quenching of the vascular hyperpolarized (13)C signal with a macromolecular relaxation agent revealed that a long-T2 component of the [(13)C,(15)N2]urea signal o...

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

    Science.gov (United States)

    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. Copyright © 2015 John Wiley & Sons, Ltd.

  8. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    Science.gov (United States)

    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 condensate...

  9. The Effect of Supplementation Urea and Sulfur in Mixed Cassava Waste Fermented and Soyabean Cake Waste on Digestibility of Protein and Blood Urea Male Sheep

    Directory of Open Access Journals (Sweden)

    M Bata

    1999-05-01

    Full Text Available Eighteen local male sheep were divided into 3 groups I,II and III based on the body weight 18.55±1.27, 15.79±0.67 and 13.14±1.33 kg respectively. Two level urea (2 and 3% and three levels Sulfur (0.02 and 0.3% as treatment, so pattern factorial 2x3 with Randomized Block Design used this experiment. All of the treatment get a same basal feed namely land-grass and concentrate with dry matter ratio 70:30.  The total intake of  dry matter was 4 % of body weight. The concentrate consist of cassava waste fermented  and soyabean cake waste with dry matter  ratio 77.50 : 22.50. Supplementation of urea and sulfur shown not significant interaction, but supplementation urea had effect high significantly (P<0.01 on digestibility of protein and sulfur only had effect significant  (P<0.05 on blood urea. These result had indication that enriched urea in the diet could increase protein digestibility and sulfur level 0.2% could prevent NH3 absorption from rumen. (Animal Production 1(2: 75-81 (1999   Key Words: cassava waste, soyabean cake waste, fermentation, digestibility, urea blood.

  10. Room temperature removal of NO by activated carbon fibres loaded with urea and La2O3.

    Science.gov (United States)

    Lu, Pei; Zeng, Zheng; Li, Caiting; Zeng, Guangming; Guo, Jing; Jiang, Xiao; Zhai, Yunbo; Fan, Xiaopeng

    2012-01-01

    In this paper, catalytic samples of 10, 20, 30, 40 and 50% (w/w) urea/activated carbon fibre (AFC), 10% urea--5% La2O3/ACF, 10% urea--10% La2O3/ACF, 10% urea--15% La2O3/ACF, 20% urea--5% La2O3/ACF, 20% urea--10% La2O3/ACF, and 20% urea-15% La2O3/ACF were prepared and used for removal of NO under the condition of: NO, 500 ppm; O2, 21%; N2, balance, gas space velocity = 10000 m3 x h(-1) m(-3), total gas flow = 266.7 mL min(-1), temperature = 30 degreesC, relative humidity = 0%. The physical and chemical properties of the prepared catalysts were characterized by surface area measurements (BET) and scanning electron microscopy studies. Furthermore, the catalytic stability of 10% urea--5% La2O3/ACF under different concentrations of NO and O2 were also studied. The results showed that, among the prepared urea/ACF samples, 20% urea/ACF yielded the highest NO conversion at room temperature. Meanwhile, among the prepared urea--La2O3/ACF catalysts, 10% urea--5% La2O3/ACF yielded the highest NO conversion. Both 20% urea/ACF and 10% urea--5% La2O3/ACF could yield over 95% NO conversion at ambient temperature. However, 10% urea--5% La2O3/ACF had a more stable activity than that of 20% urea/ACF. The catalytic and characterization experimental results, including BET, thermogravimetric analysis and Fourier transform infrared analysis, showed that the NO selective catalytic reduction mechanism of urea-La2O3/ACF was different from that of ACF and urea/ACF. The NO was purified by ACF mainly by adsorption, whereas there was mainly a reduction reaction when NO was purified by urea/ACF or urea-La2O3/ACF. ACF-C was not only the catalyst but also the reducing agent for urea/ACF, whereas, for urea-La2O3/ACF, the catalytic centre was La2O3, and ACF was mainly the carrier. These differences resulted in the higher and more stable NO removal by 10% urea--5% La2O3/ACF.

  11. Problems associated with the use of urea-formaldehyde foam for residential insulation. Part I. The effects of temperature and humidity on formaldehyde release from urea-formaldehyde foam insulation

    Energy Technology Data Exchange (ETDEWEB)

    Long, K.R.; Pierson, D.A.; Brennan, S.T.; Frank, C.W.; Hahne, R.A.

    1979-09-01

    The study is concerned primarily with those properties related to formaldehyde and its application as an ingredient in urea-formaldehyde resins. In particular the effects of temperature and humidity on urea-formaldehyde foam are discussed.

  12. Structural and dynamic properties of urea and thiourea inclusion compounds

    Science.gov (United States)

    Harris, Kenneth D. M.

    1996-01-01

    There is currently considerable interest in the chemistry and physics of solid inclusion compounds as a consequence of the wide range of important physico-chemical properties associated with them. In part, scientific interest in these materials is motivated by the desire to compare the structural, dynamic, and chemical properties of organic "guest" molecules embedded within different crystalline environments, and to investigate how the properties of the guest molecule may be influenced by the structural characteristics of its environment. This paper is focused upon urea and thiourea inclusion compounds containing a variety of different types of organic guest molecule. Aspects of the structural and dynamic properties of these inclusion compounds have been probed using solid-state NMR spectroscopy, X-ray diffraction, EXAFS spectroscopy, incoherent quasielastic neutron scattering, Raman spectroscopy, computer simulation and mathematical modelling. On the basis of the results from these investigations, the current level of understanding of the structural and dynamic properties of these materials is assessed.

  13. INFLUENCE OF ENVIRONMENTAL AND GENETICAL FACTORS ON UREA CONTENT IN HOLSTEIN BREED COWS MILK

    Directory of Open Access Journals (Sweden)

    Draženko Budimir

    2014-12-01

    Full Text Available The aims of this paper were to determine to which extent the environmental factors (order and stadium of lactation, age with the first calving, calving season, region and herd have the influence on the content of urea in milk, and connection of urea content in milk with other features of milk production with cows. The largest share of urea content in milk was recorded in the first lactation, in the period between 110 and 140 days, when it was around 23.6 mg/100 ml. In the end of the first lactation the average urea content in milk was around 21.6 mg/100 ml. The second lactation is chara¬cterized by somewhat bigger urea content, in the period immediately after calving when the highest values from all tracked lactations was recorded. The age of cows with their first calving also had an impact on urea con¬tent in milk. Cows that calved in the age from 24th to 26th month had the highest value of urea content, being 23.2 mg/100 ml for the stated period. The lowest value of urea content was recorded with cows that calved in the age of 18 months and it was below 20 mg/100 ml. Season of calving also influenced the urea content in milk. In winter season 2004 the lowest values of urea content in milk were recorded while in the autumn sea¬son of the same year the highest urea content in milk was measured (24 mg/100 ml. In the following calving season increase of urea content in milk followed. The differences in urea content in milk were determined between the counties. The highest value of heritabi-lity (0.08 was estimated by the model where, as a comparison group, the interaction between the herds and control day was used. In the research the share of variability was explained by the interaction herd-control day and it was 67%, while 25% of variability of urea con¬tent in milk remained unexplained. This model was used when estimating the breeding values. A model was also tested where the influence of herd was used as a comparison group, and by this

  14. Study of AOT-stabilized microemulsions of urea dispersed in carbon tetrachloride

    Science.gov (United States)

    Ruggirello, A.; Turco Liveri, V.

    2003-03-01

    Measurements of some physico-chemical properties (density, viscosity, permittivity) of the urea/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/CCl 4 system as a function of the volume fraction of the dispersed phase (0urea to AOT molar ratio ( Rurea) have been carried out at 25 °C. The experimental data analysis are consistent with the hypothesis that urea is entrapped as small-size molecular clusters within the hydrophilic core of the AOT reversed micelles and that this structure is preserved well above a threshold Φ value where a percolative transition occurs. Besides, X-ray diffraction spectra of samples at Φ=1, obtained by complete evaporation under vacuum of the apolar solvent of urea/AOT/CCl 4 solutions, indicates that, even in the typical two-dimensional hexagonal structure of AOT liquid crystals, urea is encapsulated as uni-dimensional molecular clusters.

  15. Vetiver grass is capable of removing TNT from soil in the presence of urea

    Energy Technology Data Exchange (ETDEWEB)

    Das, Padmini [Department of Earth and Environmental Studies, Montclair State University, One Normal Avenue, Montclair, NJ 07104 (United States); Datta, Rupali [Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931 (United States); Makris, Konstantinos C., E-mail: konstantinos.makris@cut.ac.c [Cyprus International Institute for Environmental and Public Health in Association with Harvard School Of Public Health, Cyprus University of Technology, Limassol (Cyprus); Sarkar, Dibyendu [Department of Earth and Environmental Studies, Montclair State University, One Normal Avenue, Montclair, NJ 07104 (United States)

    2010-05-15

    The high affinity of vetiver grass for 2,4,6 trinitrotoluene (TNT) and the catalytic effectiveness of urea in enhancing plant uptake of TNT in hydroponic media we earlier demonstrated were further illustrated in this soil-pot-experiment. Complete removal of TNT in urea-treated soil was accomplished by vetiver at the low initial soil-TNT concentration (40 mg kg{sup -1}), masking the effect of urea. Doubling the initial TNT concentration (80 mg kg{sup -1}) significantly (p < 0.002) increased TNT removal by vetiver, in the presence of urea. Without vetiver grass, no significant (p = 0.475) change in the soil-TNT concentrations was observed over a period of 48 days, suggesting that natural attenuation of soil TNT could not explain the documented TNT disappearance from soil. - Vetiver grass in the presence of urea effectively removes TNT from soil.

  16. Role of urea in the reduction of apple primary infections by Venturia inaequalis (Cooke Aderh

    Directory of Open Access Journals (Sweden)

    Beata Meszka

    2013-12-01

    Full Text Available The effect of pre-leaf fall of 5% urea treatment on primary infection of apple by Venturia inaequalis, the cause of scab, was investigated in commercial apple orchards of McIntosh cv. in different regions of Poland, at Miłobądz, Sinołęka and Dąbrowice. Additionally, the development of pseudothecia and maturation of ascospores were evaluated in the spring on apple leaves of two cultivars (McIntosh and Gloster treated with 5% solution of urea. Microscopic observations of leaves showed that urea treatment significantly reduced the number of pseudothecia (by ca. 90% and ascospore production. Low number of ascospores after urea treatment has strongly affected primary infection of apple by the fungus in all tested orchards. Reduction of leaf infection on control trees was usually more than 30%. Also efficacy of chemical control of apple scab was significantly higher on plots treated with urea.

  17. Effects of concentration on the microwave dielectric spectra of aqueous urea solutions

    Science.gov (United States)

    Lyashchenko, A. K.; Dunyashev, V. S.; Zasetsky, A. Yu.

    2017-05-01

    Several models of relaxation for the dielectric spectra of aqueous urea solutions in the microwave region are compared. The spectra are shown to contain two main Debye components arising from the rotational motions of urea and water molecules. Two essentially different concentration regions in urea solutions are identified. The first is characterized by a small increase in the mobility of water molecules (τ1 = 7.8 ps) and the existence of hydrated urea molecules (τ2 = 19 ps). Due to the aggregation of urea molecules, the relaxation times for the latter process grow considerably in highly concentrated solutions. At the same time, faster molecular motions (τ3 = 6 ps) are observed for water molecules.

  18. Chemodetection and Destruction of Host Urea Allows Helicobacter pylori to Locate the Epithelium

    Science.gov (United States)

    Huang, Julie Y.; Sweeney, Emily Goers; Sigal, Michael; Zhang, Hai C.; Remington, S. James; Cantrell, Michael A.; Kuo, Calvin J.; Guillemin, Karen; Amieva, Manuel R.

    2015-01-01

    SUMMARY The gastric pathogen Helicobacter pylori interacts intimately with the gastric mucosa to avoid the microbicidal acid in the stomach lumen. The cues H. pylori senses to locate and colonize the gastric epithelium have not been well defined. We show that metabolites emanating from human gastric organoids rapidly attract H. pylori. This response is largely controlled by the bacterial chemoreceptor TlpB, and the main attractant emanating from epithelia is urea. Our previous structural analyses show that TlpB binds urea with high affinity. Here we demonstrate that this tight binding controls highly sensitive responses, allowing detection of urea concentrations as low as 50 nanomolar. Attraction to urea requires that H. pylori urease simultaneously destroys the signal. We propose that H. pylori has evolved a sensitive urea chemodetection and destruction system that allows the bacterium to dynamically and locally modify the host environment to locate the epithelium. PMID:26269952

  19. LOW FRACTIONAL EXCRETION OF UREA IN HYPOTHYROIDISM INDUCED HYPONATREMIA

    Directory of Open Access Journals (Sweden)

    Algranati L

    2005-01-01

    Full Text Available 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 hiponatremia inducida por hipotiroidismo. En el presente reporte mostramos que la EFU y excreción fraccional de sodio (EFNa fueron baja (EFU: 29% y alta (EFNa: 2.2% respectivamente en un paciente que padecía hipotiroideo severo. El tratamiento con hormona tiroidea normalizó el valor de ambos índices.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 hypothyroidism. Because of that we presented a case report showing that the value of FEU and fractional excretion of sodium (FENa were low (FEU: 29% and high (FENa: 2.2 % respectively in a severe hypothyroid patient. Treatment based on thyroid hormone normalized both indeces.

  20. Slow-release urea in diets for lactating crossbred cows

    Directory of Open Access Journals (Sweden)

    Bruno Tadeu Santiago

    2015-05-01

    Full Text Available The objective of this study was to evaluate the performance of F1 (Holstein × Zebu cows in lactation according to different levels of substitution of soybean meal for a protein equivalent non-protein nitrogen originated from slow-release urea (SRU. Eight F1 (Holstein × Zebu cows in the first third of lactation, with an average milk yield of 12.7 kg (±3.1 kg/day and a live weight of 552 kg (±30 kg, were used. The experimental design was composed of two simultaneous 4 × 4 Latin squares, with the following treatments: 100% soybean meal and 0% SRU; 66% soybean meal and 34% SRU; 34% soybean meal and 66% SRU; and 0% soybean meal and 100% SRU. Sorghum silage, used as roughage, was supplied together with the concentrate. Feed intake and digestibility as well as milk yield and milk composition were measured. The obtained data were subjected to analysis of variance, adopting a 5% probability level. No intake variable showed significant differences among the treatments, and the mean values for the intakes of dry matter (DM, crude protein (CP and neutral detergent fiber (NDF were 18.35 2.62 and 5.85 kg/day, respectively. The results for apparent digestibility also did not show differences among treatments, with DM, CP and NDF averaging 58.16, 58.64 and 36.21%, respectively. Milk yield and composition were similar among the treatments. The average 4%-fat-corrected milk yield was 13.39 kg/animal day. Intake, digestibility and milk yield and composition variables are not changed according to the substitution of the soy protein for slow-release urea. Thus, for average-milk-yield crossbred.animals, this substitution depends on economic variables only.

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

    Directory of Open Access Journals (Sweden)

    Musso CG

    2005-02-01

    Full Text Available 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 hypothyroidism. Because of that we presented a case report showing that the value of FEU and fractional excretion of sodium (FENa were low (FEU: 29% and high (FENa: 2.2 % respectively in a severe hypothyroid patient. Treatment based on thyroid hormone normalized both indeces.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 hiponatremia inducida por hipotiroidismo. En el presente reporte mostramos que la EFU y excreción fraccional de sodio (EFNa fueron baja (EFU: 29% y alta (EFNa: 2.2% respectivamente en un paciente que padecía hipotiroidismo severo. El tratamiento con hormona tiroidea normalizó el valor de ambos índices.

  2. Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 2): Novel Analytical Methods of Urea Accumulated in the Stratum Corneum by Tape stripping and Colorimetry.

    Science.gov (United States)

    Goto, Norio; Morita, Yutaka; Terada, Katsuhide

    2016-01-01

    The transfer of urea from a urea formulation to the stratum corneum varies with the formulation base and form, and impacts the formulation's therapeutic effect. Consequently, determining the amount of urea transferred is essential for developing efficient formulations. This study assessed a simple method for measuring the amount of urea accumulated in the stratum corneum. Conventional methods rely on labeling urea used in the formulation with radiocarbon ((14)C) or other radioactive isotopes (RIs), retrieving the transferred urea from the stratum corneum by tape stripping, then quantitating the urea. The handling and use of RIs, however, is subject to legal regulation and can only be performed in sanctioned facilities, so methods employing RIs are neither simple nor convenient. We therefore developed a non-radiolabel method "tape stripping-colorimetry (T-C)" that combines tape stripping with colorimetry (urease-glutamate dehydrogenase (GLDH)) for the quantitative measurement of urea. Urea in the stratum corneum is collected by tape stripping and measured using urease-GLDH, which is commonly used to measure urea nitrogen in blood tests. The results indicate that accurate urea measurement by the T-C method requires the application of 1400 mg (on hairless rats) of a 20% urea solution on a 50 cm(2) (5×10 cm) area. Further, we determined the amount of urea accumulated in the stratum corneum using formulations with different urea concentrations, and the time course of urea accumulation from formulations differing in the rate of urea crystallization. We demonstrate that the T-C method is simple and convenient, with no need for (14)C or other RIs.

  3. Forensic utility of isotope ratio analysis of the explosive urea nitrate and its precursors.

    Science.gov (United States)

    Aranda, Roman; Stern, Libby A; Dietz, Marianne E; McCormick, Meghan C; Barrow, Jason A; Mothershead, Robert F

    2011-03-20

    Urea nitrate (UN) is an improvised explosive made from readily available materials. The carbon and nitrogen isotope composition of UN and its component ions, urea and nitrate, could aid in a forensic investigation. A method was developed to separate UN into its component ions for δ(15)N measurements by dissolving the sample with KOH, drying the sample, followed by removal of the urea by dissolution into 100% methanol. UN was synthesized to assess for preservation of the carbon and nitrogen isotope compositions of reactants (urea and nitric acid) and product UN. Based on nitrogen isotope mass balance, all UN samples contained varying amounts of excess nitric acid, making the ionic separation an essential step in the nitrogen isotope analysis. During UN synthesis experiments, isotopic composition of the reactants is preserved in the product UN, but the urea in the product UN is slightly enriched in (15)N (urea. Published isotopic compositions of UN reactants, urea and nitric acid, have large ranges (urea δ(15)N = -10.8 to +3.3‰; urea δ(13)C = -18.2 to -50.6‰; and nitric acid δ(15)N = -1.8 to +4.0‰). The preservation of isotopic composition of reactants in UN, along with a significant variability in isotopic composition of reactants, indicates that isotope ratio analysis may be used to test if urea or nitric acid collected during an investigation is a possible reactant for a specific UN sample. The carbon and nitrogen isotope ratios differ significantly between two field-collected UN samples, as well as the lab-synthesized UN samples. These observed variations suggest that this approach is useful for discriminating between materials which are otherwise chemically identical. Published by Elsevier Ireland Ltd.

  4. Design and implementation of mixing chambers to improve thermal decomposition of urea for NOX abatement

    KAUST Repository

    Lee, Junggil

    2012-10-01

    Urea-selective catalytic reduction (SCR) has been reported as the most promising technique for adherence to NOX emissions regulations. In the urea-SCR process, NH3 is generated by urea thermal decomposition and hydrolysis and is then used as a reductant of NOX in the SCR catalyst. Therefore, improving the NOX conversion efficiency of urea-SCR requires enhancement of thermal decomposition upstream of the SCR catalyst. In the present work, two types of mixing chambers were designed and fabricated to improve urea thermal decomposition, and experiments with and without a mixing chamber were carried out to analyze thermal-decomposition characteristics of urea in the exhaust pipe with respect to inlet velocity (4-12μm/s) and temperature (350°C-500°C). Urea thermal decomposition is greatly enhanced at higher gas temperatures. At an inlet velocity of 6μm/s in the A-type mixing chamber, NH3 concentrations generated along the exhaust pipe were about 171% and 157% greater than those without the mixing chamber for inlet temperatures of 400°C and 500°C, respectively. In the case of the B-type mixing chamber, NH3 concentrations generated at inlet temperatures of 400°C and 500°C were about 147% and 179% greater than those without the mixing chamber, respectively. Note that the implementation of mixing chambers significantly enhanced conversion of urea to NH3 because it increased the residence time of urea in the exhaust pipe and improved mixing between urea and exhaust gas. © 2012, Mary Ann Liebert, Inc.

  5. Physiological and molecular ontogeny of branchial and extra-branchial urea excretion in posthatch rainbow trout (Oncorhynchus mykiss)

    National Research Council Canada - National Science Library

    Zimmer, Alex M; Wood, Chris M

    2016-01-01

    All teleost fish produce ammonia as a metabolic waste product. In embryos, ammonia excretion is limited by the chorion, and fish must detoxify ammonia by synthesizing urea via the ornithine urea cycle (OUC...

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

    Directory of Open Access Journals (Sweden)

    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.

  7. FRACTAL ANALYSIS OF PHYSICAL ADSORPTION ON SURFACES OF ACID ACTIVATED BENTONITES FROM SERBIA

    Directory of Open Access Journals (Sweden)

    Ljiljana Rožić

    2008-11-01

    Full Text Available Solid surfaces are neither ideally regular, that is, morphological and energeticcally homogeneous, nor are they fully irregular or fractal. Instead, real solid surfaces exhibit a limited degree of organization quantified by the fractal dimension, D. Fractal analysis was applied to investigate the effect of concentrations of HCl solutions on the structural and textural properties of chemically activated bentonite from southern Serbia. Acid treatment of bentonites is applied in order to remove impurities and various exchangeable cations from bentonite clay. Important physical changes in acid-activated smectite are the increase of the specific surface area and of the average pore volume, depending on acid strength, time and temperature of a treatment. On the basis of the sorption-structure analysis, the fractal dimension of the bentonite surfaces was determined by Mahnke and Mögel method. The fractal dimension evaluated by this method was 2.11 for the AB3 and 1.94 for the AB4.5 sample. The estimation of the values of the fractal dimension of activated bentonites was performed in the region of small pores, 0.5 nm < rp < 2 nm.

  8. Adsorptive desulfurization of model oil using untreated, acid activated and magnetite nanoparticle loaded bentonite as adsorbent

    Directory of Open Access Journals (Sweden)

    Muhammad Ishaq

    2017-02-01

    Full Text Available The present research work focuses on a novel ultraclean desulfurization process of model oil by the adsorption method using untreated, acid activated and magnetite nanoparticle loaded bentonite as adsorbent. The parameters investigated are effect of contact time, adsorbent dose, initial dibenzothiophene (DBT concentration and temperature. Experimental tests were conducted in batch process. Pseudo first and second order kinetic equations were used to examine the experimental data. It was found that pseudo second order kinetic equation described the data of the DBT adsorption onto all types of adsorbents very well. The isotherm data were analyzed using Langmuir and Freundlich isotherm models. The Langmuir isotherm model fits the data very well for the adsorption of DBT onto all three forms of adsorbents. The adsorption of DBT was also investigated at different adsorbent doses and was found that the percentage adsorption of DBT was increased with increasing the adsorbent dose, while the adsorption in mg/g was decreased with increasing the adsorbent dose. The prepared adsorbents were analyzed by scanning electron microscopy (SEM, energy dispersive X-ray spectrometry (EDX and X-ray diffraction (XRD.

  9. Investigation the Plywood Manufacturing of Paulownia (paulownia tomentosa with Urea and Phenol Formaldehyde Adhesives

    Directory of Open Access Journals (Sweden)

    Meysam Mehdinia

    2012-01-01

    Full Text Available In recent years, the plywood and veneer industry of Iran has undergone negative growth due to shortage of proper diameter logs and also lack of innovative technologies for the use of low-diameter logs; Moreover, demands for lignocelluloses products has been growing as a consequence of  significant increase in population and expansion of construction Industry, especially in major cities. Hence, it is necessary to cultivate fast-growing species. For this purpose four logs of paulownia (120 cm length and 55 cm diameter were prepared from the Gorgan shast Kalate forests and then transported to Kosar factory in order to prepare veneers. Produced layers were transferred to the wood laboratory of Gorgan university. Then plywood was manufactured from paulownia species on the basis of the standard 3210 of ISIRI (Institute of Standards and Industrial Researches of Iran and common tests of plywood were made. The results showed that the mechanical properties of manufactured boards were upper than with standards defined by ISIRI and the physical properties of those manufactured with urea formaldehyde glue were lower than standards which can be considered as negative properties; Albeit, they were not significant and can be disregarded

  10. Understanding the interrelationship between the synthesis of urea and gluconeogenesis by formulating an overall balanced equation.

    Science.gov (United States)

    Ipata, Piero L; Pesi, Rossana

    2017-06-01

    It is well known that a strong metabolic interrelationship exists between ureagenesis and gluconeogenesis. In this paper, we present a detailed, overall equation, describing a possible metabolic link between ureagenesis and gluconeogenesis. We adopted a guided approach in which we strongly suggest that students, when faced with the problem of obtaining the overall equation of a metabolic pathway, carefully account for all atoms and charges of the single reactions, as well as the cellular localizations of the substrates, and the related transport systems. If this suggestion is always taken into account, a balanced, overall equation of a metabolic pathway will be obtained, which strongly facilitates the discussion of its physiological role. Unfortunately, textbooks often report unbalanced overall equations of metabolic pathways, including ureagenesis and gluconeogenesis. Most likely the reason is that metabolism and enzymology have been neglected for about three decades, owing to the remarkable advances of molecular biology and molecular genetics. In this paper, we strongly suggest that students, when faced with the problem of obtaining the overall reaction of a metabolic pathway, carefully control if the single reactions are properly balanced for atoms and charges. Following this suggestion, we were able to obtain an overall equation describing the metabolic interrelationship between ureagenesis and gluconeogenesis, in which urea and glucose are the final products. The aim is to better rationalize this topic and to convince students and teachers that metabolism is an important and rewarding chapter of human physiology. Copyright © 2017 the American Physiological Society.

  11. Effect of Mixing Urea with Humic Acid and Acid Sulphate Soil on Ammonia Loss, Exchangeable Ammonium and Available Nitrate

    OpenAIRE

    Mohd T.M. Yusuff; Osumanu H. Ahmed; Nik M.A. Majid

    2009-01-01

    Problem statement: Ammonia loss due to rapid hydrolysis of urea in soil following surface application can be substantial. Ammonia loss in agriculture is estimated to be 1 to 60%. This laboratory study compared the effect of three different urea-humic acid-acid sulphate soil mixtures on NH3 loss and soil ammonium and nitrate contents, with loss from surface applied urea without additives (urea alone). Approach: Humic acid, acid sulfate soil and soil use in the incubation study was analyzed for...

  12. Influence of slow-release urea on nitrogen balance and portal-drained visceral nutrient flux in beef steers

    DEFF Research Database (Denmark)

    Taylor-Edwards, C C; Elam, N A; Kitts, S E

    2009-01-01

    Two experiments were conducted to evaluate the effects of slow-release urea (SRU) versus feed-grade urea on portal-drained visceral (PDV) nutrient flux, nutrient digestibility, and total N balance in beef steers.......Two experiments were conducted to evaluate the effects of slow-release urea (SRU) versus feed-grade urea on portal-drained visceral (PDV) nutrient flux, nutrient digestibility, and total N balance in beef steers....

  13. Effects of Controlled-Release Urea on Grain Yield of Spring Maize, Nitrogen Use Efficiency and Nitrogen Balance

    OpenAIRE

    JI Jing-hong; LI Yu-ying; LIU Shuang-quan; TONG Yu-xin; REN Gui-lin; LI Jie; LIU Ying; ZHANG Ming-yi

    2017-01-01

    The effects of mixing controlled-released urea (CRU) (release period of resin coated urea is 90 days) and urea (U) on maize yield, nitrogen use efficiency and nitrogen balance were studied by 4 plot experiments (site:Shuangcheng, Binxian, Harbin and Zhaoyuan) in two years (from year 2011 to 2012) to clarify the effect of controlled release urea on spring maize and soil nitrogen balance. Results were as follow:Spring maize yield and nitrogen absorption were increased with the increasing nitrog...

  14. Physiological and molecular ontogeny of branchial and extra-branchial urea excretion in posthatch rainbow trout (Oncorhynchus mykiss)

    OpenAIRE

    Zimmer, Alex M.; Wood, Chris M.

    2015-01-01

    All teleost fish produce ammonia as a metabolic waste product. In embryos, ammonia excretion is limited by the chorion, and fish must detoxify ammonia by synthesizing urea via the ornithine urea cycle (OUC). Although urea is produced by embryos and larvae, urea excretion (Jurea) is typically low until yolk sac absorption, increasing thereafter. The aim of this study was to determine the physiological and molecular characteristics of Jurea by posthatch rainbow trout (Oncorhynchus mykiss). Foll...

  15. HIPERAMONEMIA NEONATAL CAUSADA POR DEFECTOS DEL CICLO DE LA UREA Neonatal hyperammonemia in urea cycle disorders patients

    Directory of Open Access Journals (Sweden)

    Yolanda Cifuentes C

    2010-12-01

    Full Text Available Los defectos del ciclo de la úrea se deben a deficiencias de diferentes enzimas; las manifestaciones clínicas son similares y están relacionadas con la hiperamonemia. Se presentan las historias clínicas de tres neonatos a término, sin evidencia de alteración al nacimiento. Se les detectó hiperamonemia y se sospechó enfermedad metabólica. La cromatografía de aminoácidos sugirió defectos del ciclo de la úrea. El manejo incluyó dieta con restricción de proteínas, administración de benzoato de sodio, exsanguinotransfusión y diálisis peritoneal pese a lo cual fallecieron. Se revisan las causas de hiperamonemia en el neonato y se propone una secuencia para su diagnósticoThe urea cycle disorders result from deficiency of activity of enzymes N-acetyl glutamate synthetase, carbamyl phosphate synthase, ornithine transcarbamylase, argininosuccinic acid synthetase, argininosuccinic acid lyase and arginase. Except for the last one, the clinical features are similar and related with the hiperammonaemia. It reports three full term, newborn cases, they had encephalopathy and needed respiratory support after be well in neonatal period. They had hyperammonemia as inborn error. The thin layer amino acids chromatography showed alanine and glutamine, in the siblings appeared citruline, suggesting urea cycle disorders. Despite protein restriction diet, sodium benzoate administration, blood exchange and peritoneal dialysis,babies died. High argininosuccinic acid levels in the first case and high citrulline levels with argininosuccinic acid absence in the third case, which was diagnosed as argininosuccinic aciduria with citrullinemia. This report provide an overview of neonatal hyperammonemia causes and propose a secuency for diagnosis

  16. 76 FR 23835 - Solid Urea From Russia and Ukraine; Scheduling of Full Five-Year Reviews Concerning the...

    Science.gov (United States)

    2011-04-28

    ... COMMISSION Solid Urea From Russia and Ukraine; Scheduling of Full Five-Year Reviews Concerning the Antidumping Duty Orders on Solid Urea From Russia and Ukraine AGENCY: United States International Trade... whether revocation of the antidumping duty orders on solid urea from Russia and Ukraine would be likely to...

  17. Synthetic conditions and chemical structures of urea-formaldehyde resins. I. Properties of the resins synthesized by three different procedures

    Science.gov (United States)

    Gu Ji-you; Mitsuo Higuchi; Mitsuhiro Morita; Chung-Yun Hse

    1995-01-01

    The properties and chemical structures of urea-formaldehyde (UF) resins synthesized by three different procedures were investigated. The procedures employed were: 1) methylolation under the conditions of pH 8 and a formaldehyde/urea (F/U) molar ratio of 2, followed by condensation at pH 5 and by additional incorporation of urea, 2) condensation under the conditions of...

  18. Uptake of dissolved inorganic nitrogen, urea and amino acids in the Scheldt estuary: comparison of organic carbon and nitrogen uptake

    NARCIS (Netherlands)

    Andersson, M.G.I.; Van Rijswijk, P.; Middelburg, J.J.

    2006-01-01

    Uptake of dissolved ammonium, nitrate, nitrite, urea and amino acids was studied in the Scheldt estuary in different seasons over a salinity gradient. The importance of inorganic nitrogen sources was compared to that of urea and amino acids and the relative use of urea and amino acid nitrogen and

  19. 75 FR 69065 - Draft Toxicological Review of Urea: In Support of Summary Information on the Integrated Risk...

    Science.gov (United States)

    2010-11-10

    ... AGENCY Draft Toxicological Review of Urea: In Support of Summary Information on the Integrated Risk... the draft human health assessment titled, ``Toxicological Review of Urea: In Support of Summary... workshop on the draft assessment for Urea will be held via teleconference on December 13, 2010, beginning...

  20. 75 FR 59716 - Draft Toxicological Review of Urea: In Support of Summary Information on the Integrated Risk...

    Science.gov (United States)

    2010-09-28

    ... AGENCY Draft Toxicological Review of Urea: In Support of Summary Information on the Integrated Risk... Urea: In Support of Summary Information on the Integrated Risk Information System (IRIS)'' [EPA/ 635/R..., 2010. The listening session on the draft assessment for urea will be held on November 16, 2010...

  1. Altered Nitrogen Balance and Decreased Urea Excretion in Male Rats Fed Cafeteria Diet Are Related to Arginine Availability

    Directory of Open Access Journals (Sweden)

    David Sabater

    2014-01-01

    rats, but low arginine levels point to a block in the urea cycle between ornithine and arginine, thereby preventing the elimination of excess nitrogen as urea. The ultimate consequence of this paradoxical block in the urea cycle seems to be the limitation of arginine production and/or availability.

  2. Combinatorial effects of aromatic 1,3 – disubstituted ureas and fluoride on in vitro inhibition of Streptococcus mutans biofilm formation

    Directory of Open Access Journals (Sweden)

    Gurmeet eKaur

    2016-06-01

    Full Text Available Dental caries occurs as a result of disequilibrium between acid producing pathogenic bacteria and alkali generating commensal bacteria within a dental biofilm (dental plaque. S. mutans has been reported as a primary cariogenic pathogen associated with dental caries. Emergence of multidrug resistant as well as fluoride resistant strains of Streptococcus mutans due to over usage of various antibiotics is a rising problem and prompted the researchers worldwide to search for alternative therapies. In this perspective, the present study was aimed to screen selective inhibitors against ComA, a bacteriocin associated ABC transporter, involved in the quorum sensing of S. mutans. In light of our previous in silico findings, 1,3- disubstituted urea derivatives which had better affinity to ComA were chemically synthesized in the present study for in vitro evaluation of S. mutans biofilm inhibition. The results revealed that 1,3- disubstituted urea derivatives showed good biofilm inhibition. In addition, the synthesized compounds exhibited potent synergy with a very low concentration of fluoride (31.25 ppm to 62.5 ppm in inhibiting the biofilm formation of S. mutans without affecting the bacterial growth. Further, the results were confirmed by confocal laser scanning microscopy. On the whole, from our experimental results we conclude that the combinatorial application of fluoride and disubstituted ureas has a potential synergistic effect which has a promising approach in combating multidrug resistant and fluoride resistant S. mutans in dental caries management.

  3. The improvement of rice straw quality by urea-molasses treatment

    Directory of Open Access Journals (Sweden)

    Tambak Manurung

    1996-03-01

    Full Text Available A study was conducted in Balai Penelitian Temak Bogor to evaluate the effect of urea-molasses treatment on the quality of rice straw . Five levels of urea were 0%, 0.5%, 1%, 1 .5% and 2% and 4 levels of molasses were 0%, I%, 2% and 3%. The study was conducted based on factorial completely randomized design with 3 replications . Urea and molasses were mixed with 5 kg chopped rice straw and stored for 21 days in plastic bag . Parameters observed were dry matter, organic matter, crude protein, crude fibre, and silica contents . Nutritive value of rice straw was measured by proximate analysis and its nutrient digestibility by in-vitro using rumen liquid of fistulated Ongole-crossed cattle . The results showed that urea and molasses treatment on rice straw decreased the dry matter and silica contents but increased the crude protein content of rice straw (P<0 .01. Dry matter and organic matter digestibility of rice straw didn't show the significant different among urea treatment but highly significant increased (P<0.01 by the molasses treatment. It was concluded that urea and molasses treatment on rice straw could improve the quality so that by the levels of 1 .5% urea and 3% molasses produced the similar quality with napier grass .

  4. Urea-SCR Temperature Investigation for NOx Control of Diesel Engine

    Directory of Open Access Journals (Sweden)

    Asif Muhammad

    2015-01-01

    Full Text Available SCR (selective catalytic reduction system is continuously being analyzed by many researchers worldwide on various concerns due to the stringent nitrogen oxides (NOx emissions legislation for heavy-duty diesel engines. Urea-SCR includes AdBlue as urea source, which subsequently decomposes to NH3 (ammonia being the reducing agent. Reaction temperature is a key factor for the performance of urea-SCR system, as urea decomposition rate is sensitive to a specific temperature range. This particular study was directed to investigate the temperature of the SCR system in diesel engine with the objective to confirm that whether the appropriate temperature is attained for occurrence of urea based catalytic reduction or otherwise and how the system performs on the prescribed temperature range. Diesel engine fitted with urea-SCR exhaust system has been operated on European standard cycle for emission testing to monitor the temperature and corresponding nitrogen oxides (NOx values on specified points. Moreover, mathematical expressions for approximation of reaction temperature are also proposed which are derived by applying energy conservation principal and gas laws. Results of the investigation have shown that during the whole testing cycle system temperature has remained in the range where urea-SCR can take place with best optimum rate and the system performance on account of NOx reduction was exemplary as excellent NOx conversion rate is achieved. It has also been confirmed that selective catalytic reduction (SCR is the best suitable technology for automotive engine-out NOx control.

  5. Structural characteristics that stabilize or destabilize different assembly levels of phycocyanin by urea.

    Science.gov (United States)

    Marx, Ailie; Adir, Noam

    2014-07-01

    Phycocyanin is one of the two phycobiliproteins always found in the Phycobilisome antenna complex. It is always situated at the ends of the peripheral rods, adjacent to the core cylinders composed of allophycocyanin. The basic phycocyanin monomer is an (αβ) dimer of globin-like subunits with three covalently linked phycocyanobilin cofactors. Monomers assemble further into trimers, hexamers, and rods which include non-pigmented linker proteins. Upon isolation in low ionic strength solution, rods quickly disintegrate into phycocyanin trimers, which lose contacts with other phycobiliproteins and with the linker proteins. The trimers, however, are quite stable and only the presence of high concentrations of chaotropic agents (such as urea), very acidic solutions, or elevated temperatures induces monomerization, followed by separation between the subunits. We have recently determined the crystal structures of phycocyanin from the thremophilic cyanobacterium Thermosynechococcus vulcanus in the presence of 2 or 4 M urea, and shown that 4 M urea monomerizes the phycocyanin trimers. In this paper, we will describe the phycocyanin structures in 2 and 4 M urea more completely. By mapping out the urea positions, we describe the structural elements within the trimeric interaction interface that may be interrupted by the presence of 4 M urea. In addition, we also identify what are the structural characteristics that prevent 4 M urea from inducing subunit dissociation.

  6. Urease inhibitor (NBPT and efficiency of single or split application of urea in wheat crop

    Directory of Open Access Journals (Sweden)

    Marcelo Curitiba Espindula

    2014-04-01

    Full Text Available NBPT (N-(n-butyl thiophosphoric triamide, a urease inhibitor, has been reported as one of the most promising compounds to maximize urea nitrogen use in agricultural systems. The objective of this study was to evaluate the performance of irrigated wheat fertilized with urea or urea + NBPT as single or split application. The experiment was conducted from June to October 2006 in Viçosa, MG, Brazil. The experimental design followed a 2×2 factorial scheme, in which urea or urea + NBPT were combined with two modes of application: full dose at sowing (60kg ha-1 or split (20kg ha-1 at sowing + 40kg ha-1 as topdressing at tillering, in randomized blocks with ten replications. The split application of nitrogen fertilization does not improve the yield wheat under used conditions. The use of urease inhibitor improves the grain yield of wheat crop when urea is applied in topdressing at tillering, but its use does not promote difference when urea is applied in the furrow at planting.

  7. The structural basis of urea-induced protein unfolding in β-catenin

    Science.gov (United States)

    Wang, Chao; Chen, Zhongzhou; Hong, Xia; Ning, Fangkun; Liu, Haolin; Zang, Jianye; Yan, Xiaoxue; Kemp, Jennifer; Musselman, Catherine A.; Kutateladze, Tatinna G.; Zhao, Rui; Jiang, Chengyu; Zhang, Gongyi

    2014-01-01

    Although urea and guanidine hydrochloride are commonly used to denature proteins, the molecular underpinnings of this process have remained unclear for a century. To address this question, crystal structures of β-catenin were determined at various urea concentrations. These structures contained at least 105 unique positions that were occupied by urea molecules, each of which interacted with the protein primarily via hydrogen bonds. Hydrogen-bond competition experiments showed that the denaturing effects of urea were neutralized when polyethylene glycol was added to the solution. These data suggest that urea primarily causes proteins to unfold by competing and disrupting hydrogen bonds in proteins. Moreover, circular-dichroism spectra and nuclear magnetic resonance (NMR) analysis revealed that a similar mechanism caused protein denaturation in the absence of urea at pH levels greater than 12. Taken together, the results led to the conclusion that the disruption of hydrogen bonds is a general mechanism of unfolding induced by urea, high pH and potentially other denaturing agents such as guanidine hydrochloride. Traditionally, the disruption of hydrophobic inter­actions instead of hydrogen bonds has been thought to be the most important cause of protein denaturation. PMID:25372676

  8. Can salivary creatinine and urea levels be used to diagnose chronic kidney disease in children as accurately as serum creatinine and urea levels? A case-control study.

    Science.gov (United States)

    Renda, Rahime

    2017-11-01

    Children with chronic kidney disease (CKD) develop many metabolic changes in blood that often necessitate frequent biochemical analysis. Serum analysis is an invasive and painful procedure. It would be highly beneficial if a noninvasive alternative process to serum analysis in children were identified. Saliva can be collected noninvasively, repeatedly, and without the use of healthcare personnel. The aims of this study were to compare serum and salivary urea and creatinine levels in children with CKD and healthy controls, and to determine if salivary creatinine and urea levels can be used to diagnose CKD in children as accurately as serum creatinine and urea levels. This case-control study included 35 children with CKD and 28 healthy children as controls. Saliva and blood samples were collected for measurement of urea and creatinine levels. The urea and creatinine levels in serum and saliva in the CKD and control groups were compared using the independent samples Mann-Whitney U test. Correlations between the serum and salivary urea and creatinine levels were determined using Pearson's correlation coefficient. Receiver operating characteristic analysis was used to assess the diagnostic performance of salivary creatinine and cutoff values were identified. In the CKD group, the mean salivary creatinine level was 0.45 mg/dL and the mean salivary urea level was 0.11 mg/dL, versus 28.83 mg/dL and 21.78 mg/dL, respectively, in the control group. Stage 4 and 5 CKD patients had a mean salivary urea level of 31.35 mg/dL, as compared to 17.78 mg/dL in the control group. Serum urea and creatinine, and salivary creatinine were significantly higher in the CKD patients (regardless of disease stage) than in the controls (p saliva creatinine levels observed in the present study, we think saliva analysis could be used as a noninvasive alternative to blood analysis for diagnosing CKD in children.

  9. [Urea in aerosol and rainwater over the East China Sea in winter and spring].

    Science.gov (United States)

    Bo, Shao-yi; Shi, Jin-hui; Gao, Hui-wang; Qi, Jian-hu; Qiao, Jia-jia; Zhang, Jing

    2009-01-01

    Organic nitrogen is a quantitatively important component of fixed nitrogen in atmospheric aerosol and rainwater. Urea as a possible candidate of organic nitrogen component might have a significant influence to the marine ecosystem since its bioavailability and broad range of natural and anthropogenic sources. 23 total suspended particulate samples, 4 size-segregated particles samples and 10 rainwater samples collected over the East China Sea from Nov. to Dec., 2006 and Feb. to Mar., 2007 were applied to analyze the concentrations of urea, nitrate and ammonium in aerosols and rainwater, respectively. In winter and spring, the concentrations of urea nitrogen were from 0.2 nmol m(-3) to 17.7 nmolx m(-3) and 6.5 nmol x m(-3) to 14.6 nmol x m(-3) in bulk aerosols, respectively and the corresponding concentrations were from 7.8 miromol x L(-1) to 18.1 micromol x L(-1) and 12.1 micromol x L(-1) to 35.3 micromol x L(-1) in rainwater. In both aerosols and rainwater over the East China Sea, the concentrations of urea nitrogen were higher in spring than those in winter. Urea nitrogen in aerosols contributed about 5% to the three measured nitrogen species and it was about 20% in rainwater. The size distribution of urea was markedly different from those of nitrate and ammonium,which had no pronounced difference among cascade stages. A slightly enhance urea contribution presented in the range of 0.43-0.65 microm in spring, which was 19.8%. In contrast, an enhancement presented in the range of 3.3-4.7 microm in winter, which was 19.8%. Factor analysis indicated that the sources of urea in aerosols were dominated by wind-blown soils in winter and sublime of urea in soils in spring, respectively.

  10. Trace analysis of urea nitrate in post-blast debris by GC/MS.

    Science.gov (United States)

    Almog, Joseph; Espino, Dario; Tamiri, Tsippy; Sonenfeld, Dana

    2013-01-10

    Urea nitrate (uronium nitrate, UN) is an improvised explosive that looks very much like sugar and is easily made from accessible starting materials, urea and nitric acid. During the last decade it has been frequently used by terrorists in the Israeli arena and in other countries as well. It is difficult to identify urea nitrate in post-explosion debris, since only a very small fraction survives the blast. Also, in the presence of water, it readily decomposes to its original components, urea and nitric acid, two ubiquitous substances with relatively low evidential value. By further modifying McCord's recent version of Clark's method for the detection of minute amounts of urea, we were able to identify with high degree of certainty traces of uronium ion, the main characteristic factor of urea nitrate, in post-blast residues by GC/MS. The analytical process is based on the initial formation of xanthenyl urea by the reaction of uronium cation with xanthydrol, followed by reaction with alcohol to form xanthylurethane, which is readily identified by GC/MS. The reaction mechanism was corroborated by the use of labeled (15)N-urea. By applying the technique to residues collected from scenes of controlled firing experiments, 4 out of 16 samples showed the presence of uronium cation as indicated by the formation of the corresponding xanthylurethane. Potential interferences such as urea and ammonium nitrate did not respond under standard conditions. However, under strongly acidic conditions (pHurea is converted into uronium ion, which is a nuisance, since it behaves as an authentic uronium cation. Such conditions, however, do not prevail at common crime scenes. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  11. Milk urea concentration as an indicator of ammonia emission from dairy cow barn under restricted grazing.

    Science.gov (United States)

    van Duinkerken, G; Smits, M C J; André, G; Sebek, L B J; Dijkstra, J

    2011-01-01

    Bulk milk urea concentration was evaluated to assess its potential as an indicator of ammonia emission from a dairy cow barn in a situation with restricted grazing. An experiment was carried out with a herd of, on average, 52 Holstein-Friesian dairy cows. The cows were housed in a naturally ventilated barn with cubicles and a slatted floor, were fed ensiled forages and feed supplements, and each day were allowed 8.5 h of grazing. The experiment was a balanced randomized block design, replicated 3 times. The experimental factor was the bulk milk urea level, which was adjusted to levels of 15, 35, and 55 mg of urea per 100 g of milk, respectively, by changing the level of nitrogen fertilization of the pasture, the herbage mass and grass regrowth age, and the level and type of feed supplement. Ammonia emission from the barn was measured using sulfur hexafluoride as the tracer gas. Ammonia emission generally increased upon an increase in adjusted milk urea levels. A dynamic regression model was used to predict ammonia emission from bulk milk urea concentration, temperature, and a slurry mixing index. This model accounted for 66% of the total variance in ammonia emission and showed that emission increases exponentially with increasing milk urea concentration. At levels of 20 and 30 mg of urea per 100 g of milk, ammonia emission increased by about 2.5 and 3.5%, respectively, when milk urea concentration increased by 1 mg/100 g. Furthermore, emissions from the barn increased 2.6% when temperature increased by 1°C. The study showed that bulk milk urea concentration is a useful indicator for ammonia emissions from a dairy cow barn in a situation with restricted grazing. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. Performance and serum chemistry profile of lambs fed on rations with increasing levels of urea

    Directory of Open Access Journals (Sweden)

    Diana Rosana Vivian

    2017-05-01

    Full Text Available Feed intake and efficiency, animal performance, and protein and energy metabolism were studied in lambs that were fed on increasing levels of urea (0.0, 0.5, 1.0, and 1.5% of dry matter [DM]. A completely randomized design was used, with four treatments (urea levels and six replicates. The lambs were fed ad libitum for 56 days until they reached an average body weight of 35 kg. The rations were composed of 34% Tifton 85 hay (Cynodon spp. and 66% concentrate. Crude protein (CP constituted 17% of the diet on a dry matter basis, and total digestible nutrients (TDN accounted for 65%, on average. The dry matter intake (DMI and crude protein intake (CPI were not influenced by the urea levels in the diet, presenting average values of 1.175 and 0.206 kg animal-1 day-1, respectively. The average daily gain (ADG, feed conversion ratio (FCR and gross feed efficiency (GFE were also not influenced by urea levels (0.225 kg day-1, 5.33 kg DM kg gain-1 and 0.195 kg gain kg DM-1, respectively. Except for urea and glucose concentrations, blood parameters did not change with increasing urea in the diets. The mean values for total protein, albumin, globulin and creatinine in the serum were 7.11 g dL-1, 3.36 g dL-1, 3.75 g dL-1 and 0.91 mg dL-1, respectively. Serum urea decreased linearly and serum glucose increased linearly with urea levels in the diet. The addition of 1.5% of urea to the diets did not change feed intake and efficiency or animal performance, and did not cause metabolic disorders in feedlot lambs in the finishing phase.

  13. Doubly ionic hydrogen bond interactions within the choline chloride-urea deep eutectic solvent.

    Science.gov (United States)

    Ashworth, Claire R; Matthews, Richard P; Welton, Tom; Hunt, Patricia A

    2016-07-21

    Deep eutectic solvents (DESs) are exemplars of systems with the ability to form neutral, ionic and doubly ionic H-bonds. Herein, the pairwise interactions of the constituent components of the choline chloride-urea DES are examined. Evidence is found for a tripodal CHCl doubly ionic H-bond motif. Moreover it is found that the covalency of doubly ionic H-bonds can be greater than, or comparable with, neutral and ionic examples. In contrast to many traditional solvents, an "alphabet soup" of many different types of H-bond (OHO[double bond, length as m-dash]C, NHO[double bond, length as m-dash]C, OHCl, NHCl, OHNH, CHCl, CHO[double bond, length as m-dash]C, NHOH and NHNH) can form. These H-bonds exhibit substantial flexibility in terms of number and strength. It is anticipated that H-bonding will have a significant impact on the entropy of the system and thus could play an important role in the formation of the eutectic. The 2 : 1 urea : choline-chloride eutectic point of this DES is often associated with the formation of a [Cl(urea)2](-) complexed anion. However, urea is found to form a H-bonded urea[choline](+) complexed cation that is energetically competitive with [Cl(urea)2](-). The negative charge on [Cl(urea)2](-) is found to remain localised on the chloride, moreover, the urea[choline](+) complexed cation forms the strongest H-bond studied here. Thus, there is potential to consider a urea[choline](+)·urea[Cl](-) interaction.

  14. Charge-signal multiplication mediated by urea wires inside Y-shaped carbon nanotubes.

    Science.gov (United States)

    Lv, Mei; He, Bing; Liu, Zengrong; Xiu, Peng; Tu, Yusong

    2014-07-28

    In previous studies, we reported molecular dynamics (MD) simulations showing that single-file water wires confined inside Y-shaped single-walled carbon nanotubes (Y-SWNTs) held strong and robust capability to convert and multiply charge signals [Y. S. Tu, P. Xiu, R. Z. Wan, J. Hu, R. H. Zhou, and H. P. Fang, Proc. Natl. Acad. Sci. U.S.A. 106, 18120 (2009); Y. Tu, H. Lu, Y. Zhang, T. Huynh, and R. Zhou, J. Chem. Phys. 138, 015104 (2013)]. It is fascinating to see whether the signal multiplication can be realized by other kinds of polar molecules with larger dipole moments (which make the experimental realization easier). In this article, we use MD simulations to study the urea-mediated signal conversion and multiplication with Y-SWNTs. We observe that when a Y-SWNT with an external charge of magnitude 1.0 e (the model of a signal at the single-electron level) is solvated in 1 M urea solutions, urea can induce drying of the Y-SWNT and fill its interiors in single-file, forming Y-shaped urea wires. The external charge can effectively control the dipole orientation of the urea wire inside the main channel (i.e., the signal can be readily converted), and this signal can further be multiplied into 2 (or more) output signals by modulating dipole orientations of urea wires in bifurcated branch channels of the Y-SWNT. This remarkable signal transduction capability arises from the strong dipole-induced ordering of urea wires under extreme confinement. We also discuss the advantage of urea as compared with water in the signal multiplication, as well as the robustness and biological implications of our findings. This study provides the possibility for multiplying signals by using urea molecules (or other polar organic molecules) with Y-shaped nanochannels and might also help understand the mechanism behind signal conduction in both physical and biological systems.

  15. Charge-signal multiplication mediated by urea wires inside Y-shaped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Mei; Liu, Zengrong [Department of Mathematics, and Institute of Systems Biology, Shanghai University, Shanghai 200444 (China); He, Bing [School of Computer Engineering and Science, Shanghai University, Shanghai 200444 (China); Xiu, Peng, E-mail: xiupeng2011@zju.edu.cn, E-mail: ystu@shu.edu.cn [Department of Engineering Mechanics, and Soft Matter Research Center, Zhejiang University, Hangzhou 310027 (China); Tu, Yusong, E-mail: xiupeng2011@zju.edu.cn, E-mail: ystu@shu.edu.cn [Department of Mathematics, and Institute of Systems Biology, Shanghai University, Shanghai 200444 (China); College of Physics Science and Technology, Yangzhou University, Yangzhou 225009 (China)

    2014-07-28

    In previous studies, we reported molecular dynamics (MD) simulations showing that single-file water wires confined inside Y-shaped single-walled carbon nanotubes (Y-SWNTs) held strong and robust capability to convert and multiply charge signals [Y. S. Tu, P. Xiu, R. Z. Wan, J. Hu, R. H. Zhou, and H. P. Fang, Proc. Natl. Acad. Sci. U.S.A. 106, 18120 (2009); Y. Tu, H. Lu, Y. Zhang, T. Huynh, and R. Zhou, J. Chem. Phys. 138, 015104 (2013)]. It is fascinating to see whether the signal multiplication can be realized by other kinds of polar molecules with larger dipole moments (which make the experimental realization easier). In this article, we use MD simulations to study the urea-mediated signal conversion and multiplication with Y-SWNTs. We observe that when a Y-SWNT with an external charge of magnitude 1.0 e (the model of a signal at the single-electron level) is solvated in 1 M urea solutions, urea can induce drying of the Y-SWNT and fill its interiors in single-file, forming Y-shaped urea wires. The external charge can effectively control the dipole orientation of the urea wire inside the main channel (i.e., the signal can be readily converted), and this signal can further be multiplied into 2 (or more) output signals by modulating dipole orientations of urea wires in bifurcated branch channels of the Y-SWNT. This remarkable signal transduction capability arises from the strong dipole-induced ordering of urea wires under extreme confinement. We also discuss the advantage of urea as compared with water in the signal multiplication, as well as the robustness and biological implications of our findings. This study provides the possibility for multiplying signals by using urea molecules (or other polar organic molecules) with Y-shaped nanochannels and might also help understand the mechanism behind signal conduction in both physical and biological systems.

  16. Effects of polymer coated slow-release urea on ruminal fermentation and nutrient total tract digestion of beef steers

    Directory of Open Access Journals (Sweden)

    Rodrigo Gardinal

    2016-02-01

    Full Text Available ABSTRACT The objective of this study was to evaluate the effects of polymer coated slow-release urea (SRU in high-forage diets of beef steers on nutrient intake and digestibility, ruminal fermentation, microbial protein synthesis, and energy balance. Eight 24-mo-old rumen-fistulated castrated Nellore steers (average body weight = 418.0±40.0 kg were used in a replicated 4 × 4 Latin square design. Animals were randomly distributed to receive one of the following diets: no urea inclusion; 1.0% inclusion of feed grade urea in the diet (dry matter [DM] basis; 1.0% inclusion of slow-release urea 1 in the diet (DM basis; and 1.0% inclusion of slow-release urea 2 in the diet (DM basis. Slow-release urea 2 had a similar composition to that of slow-release urea 1 and differed in that it contained 2.95% sulfur. A high-forage diet was provided (75% of total DM and corn silage was used as the forage source. Diets with urea had increased crude protein (CP intake, and CP and total digestible nutrients total tract digestion. Urea sources increased ruminal concentrations of ammonia nitrogen and acetate, and decreased butyrate concentrations. The polymer coated urea did not alter ruminal fermentation when compared with feed grade urea. Diets did not affect the energy balance of steers. Feed grade urea presented greater microbial protein synthesis than polymer coated slow-release urea. The partial replacement of soybean meal by 1% slow-release urea in a diet with 75% forage does not improve ruminal fermentation and microbial protein synthesis, and shows similar results as feeding feed grade urea to beef steers.

  17. Modulation of cadmium-induced phytotoxicity in Cabomba caroliniana by urea involves photosynthetic metabolism and antioxidant status.

    Science.gov (United States)

    Huang, Wenmin; Shao, Hui; Zhou, Sining; Zhou, Qin; Li, Wei; Xing, Wei

    2017-10-01

    Urea is a widespread organic pollutant, which can be a nitrogen source, playing different roles in the growth of submerged macrophytes depending on concentrations, while high cadmium (Cd) concentrations are often toxic to macrophytes. In order to evaluate the combined effect of urea and Cd on a submerged macrophyte, Cabomba caroliniana, the morphological and physiological responses of C. caroliniana in the presence of urea and Cd were studied. The results showed that high concentrations of urea (400mgL-1) and Cd (500µmolL-1) had negative effects on C. caroliniana. There were strong visible symptoms of toxicity after 4 days of exposure under Cd-alone, 400mgL-1 urea, and Cd+400mgL-1 urea treatments. In addition, 400mgL-1 urea and Cd had adverse effects on C. caroliniana's pigment system. Significant losses in chlorophyll fluorescence and photosynthetic rates, as well as Rubisco activity were also observed under Cd-alone, 400mgL-1 urea, and Cd+400mgL-1 urea treatments. 400mgL-1 urea markedly enhanced Cd toxicity in C. caroliniana, reflected by a sharp decrease in photosynthetic activity and more visible toxicity symptoms. The results of thiobarbituric acid reactive substances (TBARS) pointed to extreme oxidative stress in C. caroliniana induced under Cd or 400mgL-1 urea exposure. Exogenous ascorbate (AsA) protected C. caroliniana from adverse damage in 400mgL-1 urea, which further corroborated the oxidative stress claim under 400mgL-1 urea. However, results also demonstrated that lower urea concentration (10mgL-1) alleviated Cd-induced phytotoxicity by stimulating chlorophyll synthesis and photosynthetic activity, as well as activating the activity of catalase (CAT) and glutathione-S-transferase (GST), which may explain the alleviating effect of urea on C. caroliniana under Cd stress. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Increasing NBPT rates to reduce ammonia volatilization losses from urea applied over sugarcane straw

    OpenAIRE

    Acácio Bezerra de Mira

    2016-01-01

    Urea is the main nitrogen (N) fertilizer used worldwide, but N losses in the form of ammonia (NH3) is a major problem when this fertilizer is topdressed over crop residues. The treatment of urea with N-(n-butyl) thiophosphoric triamide (NBPT) decreases the activity of urease enzyme and volatilization losses in many crops. However, the amount of straw over the soil in green cane trash blanketing (GCTB) systems affect the effectiveness of NBPT-treated urea in reducing NH3 losses. The hypothesis...

  19. f-Ratios calculated with and without urea uptake in nitrogen uptake by phytoplankton

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.; Corre, P.L.; L'Helguen, S.

    -Sea Re,earrh 1. Vol. 42, No. Y. pp. lh6Y-1674. 1YY.5 0967-0637(95)000664 Copyright 0 1995 Elsex,ier Science L&J Printed in Great Britain. All rights reserved UYh70637/YS $Yso+o 00 NOTE f-Ratios calculated with and without urea uptake in nitrogen..., coastal, polar, oceanic and estuarine waters. Systematic urea uptake mcasurcmcnts thus become necessary, but where such data are lacking, corrections are possible with the ratio between thefvalues calculated with and without urea uptake for each...

  20. The improvement of rice straw quality by urea-molasses treatment

    OpenAIRE

    Tambak Manurung; Muhammad Zulbardi

    1996-01-01

    A study was conducted in Balai Penelitian Temak Bogor to evaluate the effect of urea-molasses treatment on the quality of rice straw . Five levels of urea were 0%, 0.5%, 1%, 1 .5% and 2% and 4 levels of molasses were 0%, I%, 2% and 3%. The study was conducted based on factorial completely randomized design with 3 replications . Urea and molasses were mixed with 5 kg chopped rice straw and stored for 21 days in plastic bag . Parameters observed were dry matter, organic matter, crude protein, c...

  1. Effect of Enhancing Urea-Humic Acid Mixture with Refined Acid Sulphate Soil

    OpenAIRE

    Mohd T.M. Yusuff; Osumanu H. Ahmed; Nik M.A. Majid

    2009-01-01

    Problem statement: Acid Sulphate Soil (ASS) is a problem soil partly because of its high acidity. This low pH could be exploited to reduce ammonia loss from urea by reducing soil microsite pH. The use Humic Acid (HA) to control ammonia loss from urea has been reported but the cost of this material is high. This laboratory study compared the effect of enhancing urea-humic acid mixtures with acid sulphate soil on NH3 loss, pH, exchangeable ammonium and available nitrate contents. Approach: Humi...

  2. Photocontrol of Anion Binding Affinity to a Bis-urea Receptor Derived from Stiff-Stilbene.

    Science.gov (United States)

    Wezenberg, Sander J; Feringa, Ben L

    2017-01-20

    Toward the development of photoresponsive anion receptors, a stiff-stilbene photoswitch has been equipped with two urea anion-binding motifs. Photoinduced E/Z isomerization has been studied in detail by UV-vis and NMR spectroscopy. Titration experiments ( 1 H NMR) reveal strong binding of acetate and phosphate to the (Z)-isomer, in which the urea groups are closely together. Isomerization to the (E)-form separates the urea motifs, resulting in much weaker binding. Additionally, geometry optimizations by density functional theory (DFT) illustrate that oxo-anion binding to the (Z)-form involves four hydrogen bonds.

  3. PRODUCTION OF HIGH DENSITY PARTICLEBOARD USING MELAMINE-UREA-FORMALDEHYDE RESIN

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2005-12-01

    Full Text Available This research was developed aiming to evaluate the effects of board density and melamine-urea-formaldehyde resin onthe properties of particleboard for semi-structural applications. The boards were manufactured with nominal density of 0.65 g/cm³and 0.90 g/cm³ using urea-formaldehyde resin as control and melamine-urea-formaldehyde. The results showed a better dimensionallystability and mechanical properties of the boards manufactured with higher density and MUF resin content. The fine furnish usedfor external layer of particleboard in the industrial process, could be used for high density homogeneous board to semi-strucuturaluses, such as flooring applications.

  4. Serapan Nitrogen dan Fosfor Tanaman Bunga Matahari yang Dipupuk Urea dan SP-36 pada Tanah Ultisol

    OpenAIRE

    Maryati, Maryati

    2007-01-01

    Phosphorus and Nitrogen Uptake by Sunflower Due to Urea and SP-36 Fertilization on UltisolABSTRACT. The objective of this research were to study the effect of nitrogen (N) from urea and phosphorus (P) from SP-36 fertilization on N and P uptake by sunflowers (Heliantus annuus L.) on Ultisol.The result of this experiment used was a randomized completely block design arranged in factorial pattern with three replications. The first factor was urea fertilizer (without N, 108.70, 217.40, and 326.10...

  5. A uranyl hybrid compound designed from urea-bearing dipropionic acid

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Yu-Bo; Xu, Cong; Liu, Wei-Sheng [Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University (China)

    2013-07-15

    A uranyl-urea-bearing dipropionate hybrid compound, in which the two acid groups are coordinated in different modes and the urea group serves as both a coordination functionality and a supramolecular synthon, is prepared. The effect of hydrogen-bonding interactions on the luminescence properties of the compound was explored by lifetime measurements. Thermogravimetric analyses were performed under a nitrogen atmosphere and in air. The ''uranophilicity'' of this urea-bearing ligand was examined by competition experiments in alkaline spring water. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Urea route to coat inorganic nanowires, carbon fibers and nanotubes by boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Gomathi, A.; Ramya Harika, M. [Chemistry and Physics of Materials Unit, DST Unit on Nanoscience and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India); Rao, C.N.R. [Chemistry and Physics of Materials Unit, DST Unit on Nanoscience and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)], E-mail: cnrrao@jncasr.ac.in

    2008-03-15

    A simple route involving urea as the nitrogen source has been employed to carry out boron nitride coating on carbon fibers, multi-walled carbon nanotubes and inorganic nanowires. The process involves heating the carbon fibers and nanotubes or inorganic nanowires in a mixture of H{sub 3}BO{sub 3} and urea, followed by a heat treatment at 1000 deg. C in a N{sub 2} atmosphere. We have been able to characterize the BN coating by transmission electron microscopy as well as X-ray photoelectron spectroscopy. The urea decomposition route affords a simple method to coat boron nitride on one-dimensional nanostructures.

  7. Effects of Controlled Release Urea on Wheat Yield and Nitrogen Utilization Efficiency Under Different Applied Conditions

    OpenAIRE

    XIA Wei-guang; WU Ji; GAO Feng-me; WANG Yun-qing; GUO Xi-sheng

    2014-01-01

    The field trial was conducted to study the effects of different nitrogen fertilizer applications on winter wheat yield, nitrogen utilization efficiency and economic benefit. 7 treatments were designed as CK(no nitrogen fertilizer applied), 100%PU10/0(conventional urea applied before sowing, N rate was 240 kg·hm-2), 100%PU6/4(conventional urea applied before sowing and at jointing with the ratio of 6∶4, N rate was 240 kg·hm-2), 80%PU6/4(conventional urea applied before sowing and at jointing w...

  8. Nucleation of urea from aqueous solution: Structure, critical size, and rate

    Science.gov (United States)

    Mandal, Taraknath; Larson, Ronald G.

    2017-04-01

    Using fully atomistic simulations, we find that the structure of the critical urea crystal nucleus (monoclinic, four molecules per unit cell) in an aqueous solution differs from the known crystal structure of bulk urea (orthorhombic, two molecules per unit cell). Following a frequently used "seeding technique" combined with the classical nucleation theory, we also find that at room temperature the critical nucleus is very large (containing ˜530 molecules) and the nucleation rate is very slow (˜5 × 10-24 cm-3 s-1) , suggesting that the homogeneous nucleation of urea is improbable at room temperature.

  9. Actual Therapeutic Indication of an Old Drug: Urea for Treatment of Severely Symptomatic and Mild Chronic Hyponatremia Related to SIADH

    Directory of Open Access Journals (Sweden)

    Guy Decaux

    2014-09-01

    Full Text Available Oral urea has been used in the past to treat various diseases like gastric ulcers, liver metastases, sickle cell disease, heart failure, brain oedema, glaucoma, Meniere disease, etc. We have demonstrated for years, the efficacy of urea to treat euvolemic (SIADH or hypervolemic hyponatremia. We briefly describe the indications of urea use in symptomatic and paucisymptomatic hyponatremic patients. Urea is a non-toxic, cheap product, and protects against osmotic demyelinating syndrome (ODS in experimental studies. Prospective studies showing the benefit to treat mild chronic hyponatremia due to SIADH and comparing water restriction, urea, high ceiling diuretics, and antivasopressin antagonist antagonist should be done.

  10. Deposits from Creams Containing 20% (w/w) Urea and Suppression of Crystallization (Part 1): Rate of Crystallization from Cream Containing 20% (w/w) Urea and Evaluation of the Properties of the Deposit.

    Science.gov (United States)

    Goto, Norio; Morita, Yutaka; Terada, Katsuhide

    2016-01-01

    Two creams containing 20% (w/w) urea and various emulsifiers, a nonionic surfactant (NS) and lecithin (LEC), were prepared, and the rate of crystallization following application of the cream and differences in the properties of the deposits were investigated. Post-application crystallization was slower with the LEC formulation. Differences in the crystals obtained from the two formulations and from a 20% aqueous solution of urea were evaluated by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), powder X-ray-DSC (PXRD-DSC) and Fourier transform infrared spectrophotometry (FT-IR). PXRD and PXRD-DSC measurements showed that the diffraction patterns of both formulations differed from that of urea. The NS formulation provided diffraction peaks for urea and a urea composite, whereas only the urea composite was evident in the LEC formulation. DSC scans of urea showed an endotherm at around 134°C, whereas the deposits from both formulations provided an endotherm 23-25°C below that of urea; the NS formulation also showed a peak at around 140°C. These results indicate a tendency for urea crystallization in the NS formulation. FT-IR measurements showed that both deposits have a urea-based structure. The effects of the LEC formulation components on the physical properties of urea were investigated by PXRD and showed that all diffraction peaks were evenly weakened, suggesting that urea tends to be amorphous and that the formulation impacts post-application urea crystallization. Consequently, the amorphous state of urea can be maintained post-application by optimizing the formulation, thereby increasing the clinical efficacy of the cream.

  11. A novel urea conductometric biosensor based on zeolite immobilized urease.

    Science.gov (United States)

    Kirdeciler, Salih Kaan; Soy, Esin; Oztürk, Seçkin; Kucherenko, Ivan; Soldatkin, Oleksandr; Dzyadevych, Sergei; Akata, Burcu

    2011-09-15

    A new approach was developed for urea determination where a thin film of silicalite and zeolite Beta deposited onto gold electrodes of a conductometric biosensor was used to immobilize the enzyme. Biosensor responses, operational and storage stabilities were compared with results obtained from the standard membrane methods for the same measurements. For this purpose, different surface modification techniques, which are simply named as Zeolite Membrane Transducers (ZMTs) and Zeolite Coated Transducers (ZCTs) were compared with Standard Membrane Transducers (SMTs). Silicalite and zeolite Beta with Si/Al ratios 40, 50 and 60 were used to modify the conductometric electrodes and to study the biosensor responses as a function of changing zeolitic parameters. During the measurements using ZCT electrodes, there was no need for any cross-linker to immobilize urease, which allowed the direct evaluation of the effect of changing Si/Al ratio for the same type of zeolite on the biosensor responses for the first time. It was seen that silicalite and zeolite Beta added electrodes in all cases lead to increased responses with respect to SMTs. The responses obtained from ZCTs were always higher than ZMTs as well. The responses obtained from zeolite Beta modified ZMTs and ZCTs increased as a function of increasing Si/Al ratio, which might be due to the increased hydrophobicity and/or the acid strength of the medium. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Modeled Urea Distribution Volume and Mortality in the HEMO Study

    Science.gov (United States)

    Greene, Tom; Depner, Thomas A.; Levin, Nathan W.; Chertow, Glenn M.

    2011-01-01

    Summary Background and objectives In the Hemodialysis (HEMO) Study, observed small decreases in achieved equilibrated Kt/Vurea were noncausally associated with markedly increased mortality. Here we examine the association of mortality with modeled volume (Vm), the denominator of equilibrated Kt/Vurea. Design, setting, participants, & measurements Parameters derived from modeled urea kinetics (including Vm) and blood pressure (BP) were obtained monthly in 1846 patients. Case mix–adjusted time-dependent Cox regressions were used to relate the relative mortality hazard at each time point to Vm and to the change in Vm over the preceding 6 months. Mixed effects models were used to relate Vm to changes in intradialytic systolic BP and to other factors at each follow-up visit. Results Mortality was associated with Vm and change in Vm over the preceding 6 months. The association between change in Vm and mortality was independent of vascular access complications. In contrast, mortality was inversely associated with V calculated from anthropometric measurements (Vant). In case mix–adjusted analysis using Vm as a time-dependent covariate, the association of mortality with Vm strengthened after statistical adjustment for Vant. After adjustment for Vant, higher Vm was associated with slightly smaller reductions in intradialytic systolic BP and with risk factors for mortality including recent hospitalization and reductions in serum albumin concentration and body weight. Conclusions An increase in Vm is a marker for illness and mortality risk in hemodialysis patients. PMID:21511841

  13. Urea is not a universal cryoprotectant among hibernating anurans: evidence from the freeze-tolerant boreal chorus frog (Pseudacris maculata).

    Science.gov (United States)

    Higgins, Steven A; Swanson, David L

    2013-02-01

    Freeze-tolerant organisms accumulate a diversity of low molecular weight compounds to combat negative effects of ice formation. Previous studies of anuran freeze tolerance have implicated urea as a cryoprotectant in the wood frog (Lithobates sylvatica). However, a cryoprotective role for urea has been identified only for wood frogs, though urea accumulation is an evolutionarily conserved mechanism for coping with osmotic stress in amphibians. To identify whether multiple solutes are involved in freezing tolerance in the boreal chorus frog (Pseudacris maculata), we examined seasonal and freezing-induced variation in several potential cryoprotectants. We further tested for a cryoprotective role for urea by comparing survival and recovery from freezing in control and urea-loaded chorus frogs. Tissue levels of glucose, urea, and glycerol did not vary significantly among seasons for heart, liver, or leg muscle. Furthermore, no changes in urea or glycerol levels were detected with exposure to freezing temperatures in these tissues. Urea-loading increased tissue urea concentrations, but failed to enhance freezing survival or facilitate recovery from freezing in chorus frogs in this study, suggesting little role for urea as a natural cryoprotectant in this species. These data suggest that urea may not universally serve as a primary cryoprotectant among freeze-tolerant, terrestrially hibernating anurans. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Urea derivatives on the move: cytokinin-like activity and adventitious rooting enhancement depend on chemical structure.

    Science.gov (United States)

    Ricci, A; Bertoletti, C

    2009-05-01

    Urea derivatives are synthetic compounds, some of which have proved to be positive regulators of cell division and differentiation. N-phenyl-N'-(2-chloro-4-pyridyl)urea (forchlorofenuron, CPPU) and N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ), well known urea cytokinin representatives, are extensively used in in vitro plant morphogenesis studies, as they show cytokinin-like activity often exceeding that of adenine compounds. In recent years, renewed interest in structure-activity relationship studies allowed identification of new urea cytokinins and other urea derivatives that specifically enhance adventitious root formation. In this review, we report the research history of urea derivatives, new insights into their biological activity, and recent progress on their mode of action.

  15. Identification of the fatty acid activation site on human ClC-2.

    Science.gov (United States)

    Cuppoletti, John; Tewari, Kirti P; Chakrabarti, Jayati; Malinowska, Danuta H

    2017-06-01

    Fatty acids (including lubiprostone and cobiprostone) are human ClC-2 (hClC-2) Cl- channel activators. Molecular and cellular mechanisms underlying this activation were examined. Role of a four-amino acid PKA activation site, RGET691, of hClC-2 was investigated using wild-type (WT) and mutant (AGET, RGEA, and AGAA) hClC-2 expressed in 293EBNA cells as well as involvement of PKA, intracellular cAMP concentration ([cAMP]i), EP2, or EP4 receptor agonist activity. All fatty acids [lubiprostone, cobiprostone, eicosatetraynoic acid (ETYA), oleic acid, and elaidic acid] caused significant rightward shifts in concentration-dependent Cl- current activation (increasing EC50s) with mutant compared with WT hClC-2 channels, without changing time and voltage dependence, current-voltage rectification, or methadone inhibition of the channel. As with lubiprostone, cobiprostone activation of hClC-2 occurred with PKA inhibitor (myristoylated protein kinase inhibitor) present or when using double PKA activation site (RRAA655/RGEA691) mutant. Cobiprostone did not activate human CFTR. Fatty acids did not increase [cAMP]i in hClC-2/293EBNA or T84 cells. Using T84 CFTR knockdown cells, cobiprostone increased hClC-2 Cl- currents without increasing [cAMP]i, while PGE2 and forskolin-IBMX increased both. Fatty acids were not agonists of EP2 or EP4 receptors. L-161,982, a supposed EP4-selective inhibitor, had no effect on lubiprostone-activated hClC-2 Cl- currents but significantly decreased T84 cell barrier function measured by transepithelial resistance and fluorescent dextran transepithelial movement. The present findings show that RGET691 of hClC-2 (possible binding site) plays an important functional role in fatty acid activation of hClC-2. PKA, [cAMP]i, and EP2 or EP4 receptors are not involved. These studies provide the molecular basis for fatty acid regulation of hClC-2. Copyright © 2017 the American Physiological Society.

  16. Numerical analysis of NOx reduction for compact design in marine urea-SCR system

    Directory of Open Access Journals (Sweden)

    Cheolyong Choi

    2015-11-01

    Full Text Available In order to design a compact urea selective catalytic reduction system, numerical simulation was conducted by computational fluid dynamics tool. A swirl type static mixer and a mixing chamber were considered as mixing units in the system. It had great influence on flow characteristics and urea decomposition into ammonia. The mixer caused flow recirculation and high level of turbulence intensity, and the chamber increased residence time of urea- water-solution injected. Because of those effects, reaction rates of urea decomposition were enhanced in the region. When those mixing units were combined, it showed the maximum because the recirculation zone was significantly developed. NH3 conversion was maximized in the zone due to widely distributed turbulence intensity and high value of uniformity index. It caused improvement of NOx reduction efficiency of the system. It was possible to reduce 55% length of the chamber and connecting pipe without decrease of NOx reduction efficiency.

  17. Numerical analysis of NOx reduction for compact design in marine urea-SCR system

    Science.gov (United States)

    Choi, Cheolyong; Sung, Yonmo; Choi, Gyung Min; Kim, Duck Jool

    2015-11-01

    In order to design a compact urea selective catalytic reduction system, numerical simulation was conducted by computational fluid dynamics tool. A swirl type static mixer and a mixing chamber were considered as mixing units in the system. It had great influence on flow characteristics and urea decomposition into ammonia. The mixer caused flow recirculation and high level of turbulence intensity, and the chamber increased residence time of urea-water-solution injected. Because of those effects, reaction rates of urea decomposition were enhanced in the region. When those mixing units were combined, it showed the maximum because the recirculation zone was significantly developed. NH3 conversion was maximized in the zone due to widely distributed turbulence intensity and high value of uniformity index. It caused improvement of NOx reduction efficiency of the system. It was possible to reduce 55% length of the chamber and connecting pipe without decrease of NOx reduction efficiency.

  18. EFFECT OF MILK UREA AND PROTEIN LEVELS ON FERTILITY INDICES IN COWS

    Directory of Open Access Journals (Sweden)

    Malgorzata JANKOWSKA

    2011-01-01

    Full Text Available An analysis of the effect of milk urea and protein levels in four consecutive lactations on fertility indices of Blackand- White Polish Holstein-Friesian cows, milk recorded in the Kujawsko-Pomorskie province has been made. Poorer fertility indices were found in first-calf heifers and second lactation cows receiving energy-deficient diets and in older (third and fourth lactation cows receiving excess dietary protein and energy. Best fertility was found in young cows fed excess protein (>3.60% regardless of milk urea levels, and in older cows having lower and optimum levels regardless of protein levels. Cow fertility is differentiated more by milk protein levels than by urea content. Fertility parameters were poorer in first and second lactation cows than in older cows. The coefficients of correlation between milk urea and protein levels and fertility indices were very low, with the only significant differences between protein content vs. calving interval and reproductive rest period.

  19. The influence of biuret on the growth kinetics of urea crystals from aqueous solutions

    Science.gov (United States)

    Davey, R.; Fila, W.; Garside, J.

    1986-12-01

    The growth kinetics of urea in the [001] and [110] directions are presented for both pure solutions and solutions containing up to 6% biuret. This impurity is formed during the synthesis of urea and acts as a powerful habit modifier. In pure solutions urea grows very quickly in the [001] but very slowly in the [110] direction. As a result long needle-like crystals are produced. In the presence of biuret [001] growth is dramatically reduced while [110] growth is virtually unaffected, so producing a crystal with a much lower length: breadth ratio. The influence of biuret is explained by the replacement of two urea molecules in the crystal lattice by a biuret molecule. The resulting disruption of the (001) face leaves insufficient NH 2-groups to satisfy the hydrogen bonding linkages.

  20. Investigation of the behavior of urea during the pelleting of straw in a laboratory hand press

    Energy Technology Data Exchange (ETDEWEB)

    Bergner, H.; Mueller, J.; Kijora, C. (Humboldt-Universitaet, Berlin (German Democratic Republic). Sektion Tierproduktion und Veterinaermedizin)

    1983-01-01

    Pellets containing /sup 14/C- and /sup 15/N-labelled urea (3%) were made in a self-developed laboratory hand press at temperatures of 100 /sup 0/C, 150 /sup 0/C, and 200 /sup 0/C. Transformation and decomposition processes on a large scale only took place at a temperature of 200 /sup 0/C. Partly, urea was decomposed (formation of CO/sub 2/ and NH/sub 3/) and, partly, polymerization products were formed (biuret and cyanic acid). Even at a temperature of 200 /sup 0/C there were 85.5% nondecomposed urea in the dissoluble filtrate. All the products formed, including urea, very probably undergo condensation reactions with straw.

  1. Nutritional status and fruit production of Carica papaya as a function of coated and conventional urea

    National Research Council Canada - National Science Library

    Silva Júnior, Gabriel B. da; Santos, Eduardo M. dos; Silva, Roberto L; Cavalcante, Ítalo H. L

    2016-01-01

    ABSTRACT As a strategy to minimize N losses in the soil, mineral N sources, such as polymer-coated urea, have been studied as possibility to increase the synchronization of N release by the fertilizer...

  2. Urea-SCR technology for deNOx after treatment of diesel exhausts

    CERN Document Server

    Nova, Isabella

    2014-01-01

    Of intense interest both to academics and industry professionals, this groundbreaking book-length treatment of selective catalytic reduction of NOx using ammonia/urea includes papers by researchers at the leading edge of diesel exhaust abatement.

  3. Biodegradable Poly (Ester Urethane) Urea Biomaterials For Applications in Combat Casualty Care

    National Research Council Canada - National Science Library

    Guelcher, S. A; Sriniwasan, A; Hollinger, J. O

    2006-01-01

    A family of biocompatible, biodegradable poly(ester urethane)urea (PEUUR) biomaterials has been developed that degrade to non-toxic by-products and support the attachment and proliferation of cells...

  4. Urea as nitrogen source for phytoplankton production in coastal waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.

    . Assimilation ratio (delta N: P) indicates that nitrate is in short supply. However, urea available in these waters can substitute nitrogen deficiencies for the high rate of phytoplankton production...

  5. Effect of xylanase, urea, Tween and Triton additives on bioethanol production of corn stover

    Science.gov (United States)

    Xin, Xiu; Lu, Jie; Yang, Rui-Feng; Song, Wen-jing; Li, Hai-ming; Wang, Hai-song; Zhou, Jing-hui

    2017-03-01

    Corn stover is a potential source of renewable biomass for conversion to bioethanol. Fed-batch semi-simultaneous saccharifcation and fermentation (S-SSF) of corn stover pretreated by liquid hot water (LHW) was investigated. The present study aimed to confirm the influence of xylanase, urea, Tween and Triton additives on bioethanol. Results show that the positive effect of xylanase, urea, Tween was observed. High ethanol concentration requires the addition of xylanase in the stage of saccharification. The optimal amount of xylanase was 0.2 g/g biomass and addition of Triton (Triton X-100) increases the effect of xylanase. Urea has a promotion effect on the whole fermentation process.When adding 0.1% urea in the fermentation stage,the best promoting rate is 24.2%. In the longitudinal comparison of the Tween series, under the same experimental conditions, the promoting effect of Tween series: Tween 40 > Tween 80 > Tween 20 > Tween 60.

  6. Synthesis, structure characterizations, and theoretical studies of novel tricyclic multiple(urea) molecules

    Science.gov (United States)

    Zhang, Junlin; Liu, Yingzhe; Bi, Fuqiang; Zhou, Jing; Wang, Bozhou

    2017-08-01

    Three novel Bn-protected tricyclic multiple(urea) molecules were synthesized and characterized by 1H NMR, 13C NMR, FT-IR and elementary analysis. Structures of the Bn-protected tricyclic tris(urea) and bis(urea) molecules were further characterized by X-ray single-crystal diffraction analysis, indicating the urea carbonyl group has great influence on the molecular conformation and chemical reactivity. The electrostatic potentials on isosurfaces of electron density of the crystal structures obtained were studied by B3LYP/6-311G(d,p) method and Hirshfeld surface analysis were carried out to identify and quantify the interaction nature and proportion in crystals.

  7. Investigating tumor perfusion and metabolism using multiple hyperpolarized 13C compounds: HP001, pyruvate and urea

    DEFF Research Database (Denmark)

    von Morze, Cornelius; Larson, Peder E.Z.; Hu, Simon

    2012-01-01

    The metabolically inactive hyperpolarized agents HP001 (bis-1,1-(hydroxymethyl)-[1-13C]cyclopropane-d8) and urea enable a new type of perfusion magnetic resonance imaging based on a direct signal source that is background-free. The addition of perfusion information to metabolic information obtained...... by spectroscopic imaging of hyperpolarized [1-13C]pyruvate would be of great value in exploring the relationship between perfusion and metabolism in cancer. In preclinical normal murine and cancer model studies, we performed both dynamic multislice imaging of the specialized hyperpolarized perfusion compound HP001...... of separate dynamic HP001 imaging and copolarized pyruvate/urea imaging were compared. A strong and significant correlation (R=0.73, P=.02) detected between the urea and HP001 data confirmed the value of copolarizing urea with pyruvate for simultaneous assessment of perfusion and metabolism....

  8. Hyperpolarized 13 C,15 N2 -urea T2 relaxation changes in acute kidney injury

    DEFF Research Database (Denmark)

    Mariager, Christian Østergaard; Nielsen, Per Mose; Qi, Haiyun

    2017-01-01

    PURPOSE: To investigate the correlation between renal ischemia and 13 C-urea T2 relaxation rate in an acute kidney injury (AKI) rat model. METHODS: Six rats subjected to unilateral renal ischemia were investigated. Creatinine clearance, urine output, plasma creatinine as well as blood-urea nitrogen...... (BUN) values were acquired before and after the procedure. 1 H T2* mapping was acquired using blood oxygenation level dependent (BOLD) MRI and hyperpolarized 13 C-urea T2 mapping was acquired using a 2D golden-angle radial approach. Kidney perfusion was estimated using noncontrast flow alternating...... inversion recovery arterial spin labeling. RESULTS: All rats showed clinical signs of AKI with increased plasma creatinine and increased BUN. Whole kidney 13 C-urea T2 significantly decreased 26% (P = 0.001) 24 h after reperfusion. A significantly different (3.7 times steeper; P = 0.008) osmolality gradient...

  9. PENGARUH PENAMBAHAN UREA TERHADAP PENINGKATAN PENCEMARAN NITRIT DAN NITRAT DALAM TANAH (Influence of Addition of Urea to Increased Pollution of Nitrite and Nitrate in The Soil

    Directory of Open Access Journals (Sweden)

    Aida Mawaddah

    2016-09-01

    Full Text Available ABSTRAK Nitrat dan nitrit merupakan sumber nitrogen bagi tanaman. Nitrogen sangat diperlukan tanaman untuk pertumbuhan dan perkembangan. Bentuk-bentuk nitrogen di lingkungan mengalami transformasi sebagai bagian dari siklus nitrogen seperti nitrifikasi dan denitrifikasi. Apabila kadar nitrogen dalam tanah rendah, maka urea digunakan sebagai sumber nitrogen. Perubahan urea menjadi nitrit atau nitrat pada beberapa sampel tanah perlu diketahui. Kadar nitrit dan nitrat yang tinggi dapat meningkatkan pencemaran di dalam tanah. Sampel tanah yang digunakan dalam penelitian ini adalah tanah pasir, tanah sawah, tanah pupuk kompos dan tanah pupuk kandang. Analisis nitrit dan nitrat dilakukan dengan menggunakan pereaksi asam p-amino benzoat (PABA yang dikopling dengan N-naftiletilendiamin (NEDA dan reduktor spongy cadmium. Sebelum digunakan untuk analisis nitrit dan nitrat, metode divalidasi terlebih dahulu. Hasil validasi metode analisis nitrit dan nitrat dengan pereaksi PABA/NEDA menunjukkan persentase perolehan kembali masing-masing antara 87,15–100,8% untuk nitrit dan 88,16–105,7% untuk nitrat. Setelah ditambah urea sebesar 0,66 g.kg-1 ke dalam tanah, konsentrasi nitrit dan nitrat pada semua sampel tanah mengalami peningkatan. Dari penelitian ini diketahui bahwa peningkatan kadar nitrit dan nitrat setelah ditambahkan urea sangat dipengaruhi oleh kondisi tanah.   ABSTRACT Nitrate and nitrite were sources of nitrogen for plants. Nitrogen is indispensable for the growth and development of plants. The forms of nitrogen in the environment undergoes a transformation as part of the nitrogen cycle like nitrification and denitrification. If nitrogen level in the soil is low, urea is used as a source of nitrogen. Changes of urea into nitrite or nitrate in some of soil samples need to be known. The levels of nitrite and nitrate are high can increase pollution in the soil. Some of soil samples which is used in this research were sandy soil, paddy soil

  10. The Kinetics of Urea in the Body after Liver Resection in the Experiment

    Directory of Open Access Journals (Sweden)

    P. N. Savilov

    2016-01-01

    Full Text Available Purpose. To study urea kinetics in the body after liver resection in the experiment.Material and Methods. Experiments were carried out on 45 white female rats weighing between 180 g and 220 g. Liver resection (LR was performed under ester anesthesia, wherein 15—20% of the organ weight was removed. Urea content was studied in biological fluids (arterial blood, venous — v.porta, v.hepatica, v.renalis — blood, choledochal bile, urine, and tissues of visceral organs (the thyroid gland, lungs, heart, liver, kidneys, spleen, stomach, intestine on days 3, 7, and 14 after LR. Results. LR, while reducing the urea content in the v. hepatica blood, does not lead to similar changes in the arterial blood. This is accompanied by increased urea reabsorption in kidneys and higher v.porta blood urea content, which, depending on the postoperative time, results either from reduced urea excretion into the small intestine lumen or from its greater production by enterocytes followed by metabolite intake into the portal blood flow. The urea intake from hepatocytes into the hepatic bile ducts did not change on day 3 after LR; however, it increased on day 7 and slowed down on day 14. LR caused no changes in the gastric tissues urea content; never theless, it led to its increased content in the duodenal and colonic tissues. Without affecting the cardiac muscleurea content, LR entailed its increase in the lungs and thyroid gland on postoperative days 3, 7, and 14. At the background of absence of similar changes in the arterial blood data indicates promotion of urea production by the cells of these organs or metabolite retention therein.Conclusions. LR not only changes urea kinetics in the portal system organs, but also activates extrahepatic mechanisms aimed at preventing development of the arterial blood urea deficit because of its abnormal intake from the resected organ into the central blood flow.

  11. Is urea formation regulated primarily by acid-base balance in vivo?

    Science.gov (United States)

    Halperin, M L; Chen, C B; Cheema-Dhadli, S; West, M L; Jungas, R L

    1986-04-01

    Large quantities of ammonium and bicarbonate are produced each day from the metabolism of dietary protein. It has recently been proposed that urea synthesis is regulated by the need to remove this large load of bicarbonate. The purpose of these experiments was to test whether the primary function of ureagenesis in vivo is to remove ammonium or bicarbonate. The first series of rats were given a constant acid load as hydrochloric acid or ammonium chloride; individual rats received a constant nitrogen load at a time when their plasma acid-base status ranged from normal (pH 7.4, 28 mM HCO3) to severe metabolic acidosis (pH 6.9, 6 mM HCO3). Urea plus ammonium excretions and the blood urea, glutamine, and ammonium concentrations were monitored with time. Within the constraints of non-steady-state conditions, the rate of urea synthesis was constant and the plasma glutamine and ammonium concentrations also remained constant; thus it appears that the rate of urea synthesis was not primarily regulated by the acid-base status of the animal in vivo over a wide range of plasma ammonium concentrations. In quantitative terms, the vast bulk of the ammonium load was converted to urea over 80 min; only a small quantity of ammonium appeared as circulating glutamine or urinary ammonium. Urea synthesis was proportional to the nitrogen load. A second series of rats received sodium bicarbonate; urea synthesis was not augmented by a bicarbonate load. We conclude from these studies that the need to dispose of excess bicarbonate does not primarily determine the rate of ureagenesis in vivo. The data support the classical view that ureagenesis is controlled by the quantity of ammonium to be removed.

  12. Acidification From Long-Term Use Of Urea And Its Effect On ...

    African Journals Online (AJOL)

    Burning of stover on land had a small and non-significant effect on the pH of the top soil (0-20cm). Application of urea also resulted in a significant (p<0.05) decrease in the exchangeable bases (Ca, Mg) in the soil. Compared to the control treatment, soil Ca and Mg decreased by 13 % and 28% respectively in urea treated ...

  13. Remediation of chromium-slag leakage with electricity cogeneration via a urea-Cr(VI) cell

    OpenAIRE

    Binbin Yu; Huimin Zhang; Wei Xu; Gang Li; Zucheng Wu

    2014-01-01

    Chromium pollution has been historically widespread throughout the world. Most available remediation technologies often require energy consumption. This study is aimed to develop electrochemical remediation for Cr(VI) in chromium-slag leakage with self-generated electricity. Dynamic leaching experiments of chromium-slag samples were conducted to survey the release and leaching behavior of Cr(VI). Based on previous work, a unique urea-Cr(VI) was designed, in which urea was employed as the fuel...

  14. Prerenal azotemia: differentiation of hyperureagenesis from renal hypoperfusion using urinary urea nitrogen data.

    Science.gov (United States)

    Sklar, A H; Riesenberg, L A; Ur Rehman, A; Smith, S; Rivera-Padilla, H

    1996-03-01

    Blood urea nitrogen (BUN) rises disproportionately to serum creatinine in patients with prerenal azotemia whether due to impaired hemodynamics or excessive ureagenesis. To determine whether urinary urea nitrogen excretion rates can distinguish between these caused of hyperuremia we performed a cross-sectional observational study to compare urinary urea nitrogen excretion rates in a highly selected group of patients with prerenal azotemia. Patients who had stable serum creatinine levels, BUN: serum creatinine ratios exceeding 20:1, and progressive azotemia were identified from the hospital laboratory data base. Using conventional clinicolaboratory criteria, 27 patients were diagnosed with either renal hypoperfusion (group I; n = 17) or hyperureagenesis ((group II; n = 10). Random urine sampling for electrolytes, osmolality, creatinine, and urea nitrogen was followed by 24 h collection for creatinine clearance and urinary urea nitrogen. There were no significant differences in age, gender, absolute levels of BUN, or BUN: serum creatinine ratios between the groups. Creatinine clearance (ml/min/1.73 m2) (ml/s/1.73 m2) was lower in group I than in group II (21 +/- 16 vs 36 +/- 13; p < 0.05) (0.35 +/- 0.27 vs 0.60 +/- 0.22; p < 0.05). Twenty-four hour urinary urea nitrogen levels were significantly different (group I, 4.8 +/- 2.9 vs. group II, 13.6 +/- 3.2 gm; p < 0.001) (group I, 171 +/- 300 vs. group II, 486 +/- 114 mmol; p < 0.001). Random urine urea excretion indices were less discriminating but nevertheless still capable of separating the groups. Timed as well as random urine urea nitrogen determinations may assist in differentiating prerenal azotemia due to renal hypoperfusion from hyperureagenesis. Differentiation of these causes of prerenal azotemia might prevent iatrogenic overhydration of patients with azotemia incorrectly attributed to hemodynamic disturbances.

  15. A Large Response Range Reflectometric Urea Biosensor Made from Silica-Gel Nanoparticles

    Directory of Open Access Journals (Sweden)

    Muawia Alqasaimeh

    2014-07-01

    Full Text Available A new silica-gel nanospheres (SiO2NPs composition was formulated, followed by biochemical surface functionalization to examine its potential in urea biosensor development. The SiO2NPs were basically synthesized based on sol–gel chemistry using a modified Stober method. The SiO2NPs surfaces were modified with amine (-NH2 functional groups for urease immobilization in the presence of glutaric acid (GA cross-linker. The chromoionophore pH-sensitive dye ETH 5294 was physically adsorbed on the functionalized SiO2NPs as pH transducer. The immobilized urease determined urea concentration reflectometrically based on the colour change of the immobilized chromoionophore as a result of the enzymatic hydrolysis of urea. The pH changes on the biosensor due to the catalytic enzyme reaction of immobilized urease were found to correlate with the urea concentrations over a linear response range of 50–500 mM (R2 = 0.96 with a detection limit of 10 mM urea. The biosensor response time was 9 min with reproducibility of less than 10% relative standard deviation (RSD. This optical urea biosensor did not show interferences by Na+, K+, Mg2+ and NH4+ ions. The biosensor performance has been validated using urine samples in comparison with a non-enzymatic method based on the use of p-dimethylaminobenzaldehyde (DMAB reagent and demonstrated a good correlation between the two different methods (R2 = 0.996 and regression slope of 1.0307. The SiO2NPs-based reflectometric urea biosensor showed improved dynamic linear response range when compared to other nanoparticle-based optical urea biosensors.

  16. Propiedades volumétricas deaminoácidos en soluciones acuosas de urea

    Directory of Open Access Journals (Sweden)

    Carmen María Romero

    2010-07-01

    Full Text Available A partir de medidas de densidad a 25.0° C se determinaron los volúmenes molares aparentes de algunos a-aminoácidos en soluciones acuosas de urea 0.5 y 2.0 M. Los resultados obtenidos se usan para calcular los voliímenes molares parciales límites V° de los solutos y los cambios de volumen asociados con su transferencia de agua a soluciones acuosas de urea.

  17. A waterborne chemical cue from Gulf toadfish, Opsanus beta, prompts pulsatile urea excretion in conspecifics.

    Science.gov (United States)

    Fulton, Jeremy; LeMoine, Christophe M R; Bucking, Carol; Brix, Kevin V; Walsh, Patrick J; McDonald, M Danielle

    2017-03-15

    The Gulf toadfish (Opsanus beta) has a fully functional ornithine urea cycle (O-UC) that allows it to excrete nitrogenous waste in the form of urea. Interestingly, urea is excreted in a pulse across the gill that lasts 1-3h and occurs once or twice a day. Both the stress hormone, cortisol, and the neurotransmitter, serotonin (5-HT) are involved in the control of pulsatile urea excretion. This and other evidence suggests that urea pulsing may be linked to toadfish social behavior. The hypothesis of the present study was that toadfish urea pulses can be triggered by waterborne chemical cues from conspecifics. Our findings indicate that exposure to seawater that held a donor conspecific for up to 48h (pre-conditioned seawater; PC-SW) induced a urea pulse within 7h in naïve conspecifics compared to a pulse latency of 20h when exposed to seawater alone. Factors such as PC-SW intensity and donor body mass influenced the pulse latency response of naïve conspecifics. Fractionation and heat treatment of PC-SW to narrow possible signal candidates revealed that the active chemical was both water-soluble and heat-stable. Fish exposed to urea, cortisol or 5-HT in seawater did not have a pulse latency that was significantly different than seawater alone; however, ammonia, perhaps in the form of NH4Cl, was found to be a factor in the pulse latency response of toadfish to PC-SW and could be one component of a multi-component cue used for chemical communication in toadfish. Further studies are needed to fully identify the chemical cue as well as determine its adaptive significance in this marine teleost fish. Copyright © 2016. Published by Elsevier Inc.

  18. The effect of saturation magnetization of nanocatalyst and oscillating magnetic field for green urea synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Alqasem, Bilal, E-mail: bilalalqasem@yahoo.com; Irfan, Muhammad; Qureshi, Saima; Rehman, Zia Ur; Shafie, Afza; Soleimani, Hassan

    2017-02-15

    Hematite and cupric oxide nanowires have been synthesized using the oxidation method for green urea production. Hematite nanowires were obtained by the oxidation of an iron wire at a temperature of 650 °C and ambient pressure in the presence of N{sub 2} and O{sub 2} gases. Cupric oxide nanowires were obtained by the same method at 700 °C, using a copper wire. The X-ray diffraction results show the formation of rhombohedral structure of α-Fe{sub 2}O{sub 3} and monoclinic phase of CuO. FE-SEM results reveal the formation of nanowires with dimensions ranging between 5–15 µm and 4–12 µm in length and a diametere ranging between 50–150 nm and 50–250 nm for α-Fe{sub 2}O{sub 3} and CuO respectively. The VSM results show that the saturation magnetization values for hematite and cupric oxide were 132.8700 and 0.0124 emu/g, respectively. The nanowires were used as catalyst for green urea synthesis in the presence of an oscillating and a static magnetic fields. The use of nanocatalyst with high saturation magnetization gives a higher yield of urea due to the increase in the singlet to triplet conversion. The highest yield of urea 11243 ppm was achieved by applying an oscillating magnetic field of frequency 0.5 MHz and using α-Fe{sub 2}O{sub 3} nanowires as nanocatalyst. - Highlights: • Effect of saturation magnetization of nanocatalyst on urea yield was investigated • Using nanocatalyst with high saturation magnetization value improved urea yield. • Effect of oscillating magnetic field frequency on the urea yield was investigated. • The highest urea yield was achieved by applying 0.5 MHz oscillating magnetic field.

  19. Use of different urea levels in the feeding of Alpine goats

    Directory of Open Access Journals (Sweden)

    Julicelly Gomes Barbosa

    2012-07-01

    Full Text Available The objective of this study was to evaluate intake, apparent digestibility, ingestive behavior and blood parameters of milking goats fed cactus pear (Opuntia ficus indica and increasing urea levels in substitution to soybean meal. Ten multiparous Alpine goats with average weight of 31±6.0 kg were used and distributed into (5 × 5 Latin squares and assessed during five 17-day periods, receiving five treatments with the following substitution levels: 0; 5; 10; 15 and 20 g/kg of urea. Neutral detergent fiber (NDF, non-fiber carbohydrates, ether extract, organic matter and water intake values showed differences, whith average values ranging from 1.03 to 1.13; 0.12 to 0.14; 1.76 to 2.10 kg/day and 0.77 to 1.48 kg/day, respectively. The NDF and crude protein apparent digestibility values were significantly affected by urea levels. In relation to the ingestive behavior, the urea levels did not influence the feeding, idleness or rumination parameters. Difference was observed for the following physiological variables: feces frequency (11.5 to 15.9 times per day, urine frequency (10.8 to 14.2 times per day and frequency of search for water (0.8 to 2.1 times per day. The urea levels influenced the blood parameters, whose average levels ranged from 29.83 to 40.76 mg/dL. Pear cactus and increasing urea levels in substitution to soybean meal do not alter the dry matter intake or ingestive behavior. The use of urea associated with forage cactus reduces water intake and increases the blood urea concentration of milking goats.

  20. Nitrogen Utilization in Sheep Fed a Low-Quality Hay with Oral Supplement of Urea

    OpenAIRE

    Fujihara, Tsutomu

    1993-01-01

    In order to investigate the effect of orally supplemented urea on utilization of low-quality roughage in sheep, digestion and nitrogen balance trials were conducted using 3 Japanese Corriedale rams fed a mixed hay supplemented with urea at 3 levels, i. e., 0, 15 and 30% of dietary nitrogen from hay, according to a 3X3 Latin square design. The results obtained were as follows; 1) The digestibility of crude protein was clearly (P