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Sample records for urea combustion route

  1. Carbon Coated CoO Electrode Synthesized by Urea-Assisted Auto Combustion for Rechargeable Lithium Battery.

    PubMed

    Rai, Alok Kumar; Anh, Ly Tuan; Gim, Jihyeon; Mathew, Vinod; Kim, Jaekook

    2015-01-01

    A simple and low cost urea-assisted auto-combustion route was investigated for the synthesis of carbon coated CoO nanocomposite. CHN analysis determined the carbon content in CoO/C nanocomposite to be very low as 0.27 wt%. The results show that the CoO/C nanocomposite electrode displays marked lower charge transfer resistance, high lithium storage capacity, and much better rate capability than original CoO nanoparticles electrode. PMID:26328398

  2. Urea

    Integrated Risk Information System (IRIS)

    Urea ; CASRN : 57 - 13 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects ) a

  3. Synthesis of Nanoscale Nd-Doped Ceria Via Urea-Formaldehyde Combustion Method

    NASA Astrophysics Data System (ADS)

    Biswas, M.; Bandyopadhyay, S.

    2013-11-01

    Nanocrystalline neodymium-doped ceria solid solutions with Nd3+ concentrations varying from 4 to 20 mol pct have been synthesized by gel combustion method, using urea-formaldehyde as fuel for Nd doping. The combustion reaction is explained through differential scanning calorimetry (DSC)-differential thermogravimetric analysis (TGA), whereas the synthesized materials are characterized through X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The phase obtained from the exothermic reaction contains Nd-substituted CeO2. The deviation of the lattice parameter from Vegard's law and the decrease in crystallite size with dopant concentration has been explained. The as-synthesized particles are largely nanoporous single crystallites, existing in loosely held spherical-shaped agglomerates. The size of the agglomerates increases with increasing dopant content. High-resolution TEM (HRTEM) reveals the fact that the unit cells are strained.

  4. TG-FTIR study on urea-formaldehyde resin residue during pyrolysis and combustion.

    PubMed

    Jiang, Xuguang; Li, Chunyu; Chi, Yong; Yan, Jianhua

    2010-01-15

    The pyrolysis and combustion characteristics of urea-formaldehyde resin (UFR) residue were investigated by using thermogravimetric analysis, coupled with Fourier transform infrared spectroscopy (TG-FTIR). It is indicated that the pyrolysis process can be subdivided into three stages: drying the sample, fast thermal decomposition and further cracking process. The total weight loss of 90 wt.% at 950 degrees C is found in pyrolysis, while 74 wt.% of the original mass lost in the second stage is between 195 degrees C and 430 degrees C. The emissions of carbon dioxide, isocyanic acid, ammonia, hydrocyanic acid and carbon monoxide are identified in UFR residue pyrolysis, moreover, isocyanic acid emitted at low temperature is found as the most important nitrogen-containing gaseous product in UFR residue pyrolysis, and there is a large amount of hydrocyanic acid emitted at high temperature. The similar TG and emission characteristics as the first two stages during pyrolysis are found in UFR residue combustion at low temperature. The combustion process almost finishes at 600 degrees C; moreover, carbon dioxide and water are identified as the main gaseous products at high temperature. It is indicated that the UFR residue should be pyrolyzed at low temperature to remove the initial nitrogen, and the gaseous products during pyrolysis should be burnt in high temperature furnace under oxygen-rich conditions for pollutant controlling. PMID:19735979

  5. Urea route to homoleptic cyanates--characterization and luminescence properties of [M(OCN)2(urea)] and M(OCN)2 with M=Sr, Eu.

    PubMed

    Pagano, Sandro; Montana, Giuseppe; Wickleder, Claudia; Schnick, Wolfgang

    2009-06-15

    A novel approach for the synthesis of urea complexes and homoleptic cyanates of alkaline earth metals and europium is described. Direct reaction of urea with elemental Sr or Eu in closed ampoules at temperatures above 120 degrees C yields [M(OCN)2(urea)] with M=Sr, Eu. According to single-crystal X-ray diffraction, the isotypic complexes exhibit a layer structure ([Eu(OCN)2(urea)]: P2(1)/c, a=7.826(2), b=7.130(1), c=12.916(3) A, beta=99.76(3) degrees , Z=4, V=710.3(2) A3). Furthermore, they were characterized by vibrational spectroscopy, thermal analysis, magnetic measurements, and photoluminescence studies. Thermal treatment of the compounds [M(OCN)2(urea)] to 160-240 degrees C affords evaporation of urea and the subsequent formation of solvent-free homoleptic cyanates of Sr and Eu. The crystal structures of Sr(OCN)2 and Eu(OCN)2 were determined from X-ray powder diffraction data and refined by the Rietveld method. Both compounds crystallize in the orthorhombic space group Fddd and adopt the Sr(N3)2 type structure (Sr(OCN)2: a=6.1510(4), b=11.268(1), c=11.848(1) A, V=821.1(2) A3; Eu(OCN)2: a=6.1514(6), b=11.2863(12), c=11.8201(12) A, V=820.63(15) A3). The cyanates are stable up to 450 degrees C. Above 500 degrees C beta-Sr(CN)2 and Eu2O2(CN)2 are formed. Excitation and emission spectra of [Eu(OCN)2(urea)], [Sr(OCN)2(urea)]:Eu2+, Eu(OCN)2, Sr(OCN)2:Eu2+ at different temperatures are reported. A strong green emission for all examined Eu-containing compounds due to a 4f(6)5d(1)-4f(7) transition is observed at low temperatures. The luminescence properties are discussed in detail and are comparable to those of thiocyanates. Compared to the latter, a blue shift of the emission bands is observed due to the higher ionicity. PMID:19444832

  6. Route to chaos for combustion instability in ducted laminar premixed flames.

    PubMed

    Kabiraj, Lipika; Saurabh, Aditya; Wahi, Pankaj; Sujith, R I

    2012-06-01

    Complex thermoacoustic oscillations are observed experimentally in a simple laboratory combustor that burns lean premixed fuel-air mixture, as a result of nonlinear interaction between the acoustic field and the combustion processes. The application of nonlinear time series analysis, particularly techniques based on phase space reconstruction from acquired pressure data, reveals rich dynamical behavior and the existence of several complex states. A route to chaos for thermoacoustic instability is established experimentally for the first time. We show that, as the location of the heat source is gradually varied, self-excited periodic thermoacoustic oscillations undergo transition to chaos via the Ruelle-Takens scenario. PMID:22757536

  7. A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol-gel auto combustion method and their photocatalytic properties.

    PubMed

    Nassar, Mostafa Y; Ahmed, Ibrahim S; Samir, Ihab

    2014-10-15

    In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65nm was obtained at 800°C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5h with pseudo first order rate constants of 5.85×10(-3) and 8.38×10(-3)min(-1), respectively. PMID:24835935

  8. Synthesis of monodisperse spherical nanometer ZrO{sub 2} (Y{sub 2}O{sub 3}) powders via the coupling route of w/o emulsion with urea homogenous precipitation

    SciTech Connect

    Chang, Ying; Dong, Shijie; Wang, Huihu; Du, Kuanhe; Zhu, Qingbiao; Luo, Ping

    2012-03-15

    Graphical abstract: In this paper, the weight loss and reaction evolution of ZrO{sub 2} precursor powders are determined by TG-DTA, and 600 Degree-Sign C is the most reasonable calcination temperature of precursor according to the TG-DTA. At the same time, we study the effect of reaction conditions upon the particle sizes, such as concentration of zirconium nitrate solution, reaction temperature and urea content. TEM micrographs of zirconia powders indicated that ZrO{sub 2} nano-powders prepared via the coupling route of w/o emulsion with homogenous precipitation possess spherical shape and excellent dispersing. Highlights: Black-Right-Pointing-Pointer The monodisperse spherical nanometer ZrO{sub 2} (Y{sub 2}O{sub 3}) powders have been prepared via the coupling route of w/o emulsion with urea homogenous precipitation. Black-Right-Pointing-Pointer The principle of the coupling route of emulsion with homogenous precipitation has been studied. Black-Right-Pointing-Pointer The concentration of zirconium nitrate, reaction temperature of water bath and the quantity of urea effect regularly on the average particle size of products. -- Abstract: Using xylol as the oil phase, span-80 as the surfactant, and an aqueous solution containing zirconium (3 mol% Y{sub 2}O{sub 3}) and urea as the water phase, tetragonal phase ZrO{sub 2} nano-powders have been prepared via the coupling route of w/o emulsion with urea homogenous precipitation. The effects of the zirconium concentration, the reaction temperature and the urea content on the average size of the products have been examined. The as-prepared ZrO{sub 2} powders and the precursor powders were characterized by TGA-DTA, XRD, TEM and BET. Experimental results indicate that ZrO{sub 2} powders prepared via the coupling route of w/o emulsion with urea homogenous precipitation possess some excellent characteristics, such as well-rounded spherical shape and excellent dispersing.

  9. Landslide remediation on Ohio State Route 83 using clean coal combustion by-products

    SciTech Connect

    Payette, R.; Chen, X.Y.; Wolfe, W.; Beeghly, J.

    1995-12-31

    In the present work, a flue gas desulfurization (FGD) by-product was used to reconstruct the failed portion of a highway embankment. The construction process and the stability of the repaired embankment are examined. State Route 83 in Cumberland, Ohio has been damaged by a slow moving slide which has forced the Ohio Department of Transportation to repair the roadway several times. In the most recent repair FGD by-products obtained from American Electric Power`s Tidd PFBC plant were used to construct a wall through the failure plane to prevent further slippage. In order to evaluate the utility of using coal combustion by-products in this type of highway project the site was divided into three test sections. In the first repair section, natural soil removed form the slide area was recompacted and replaced according to standard ODOT construction practices. In the second section the natural soil was field mixed with the Tidd PFBC ash in approximately equal proportions. The third section was all Tidd ash. The three test sections were capped by a layer of compacted Tidd ash or crushed stone to provide a wearing surface to allow ODOT to open the roadway before applying a permanent asphalt surface. Measurement of slope movement as well as water levels and quality have begun at the site in order to evaluate long term project performance. The completion of this project should lead to increased acceptance of FGD materials in construction projects. Monetary savings will be realized in avoiding some of the disposal costs for the waste, as well as in the reduced reliance on alternative engineering materials.

  10. Influence of fuel on phase formation of ZnFe2O4 prepared by self-propagated combustion route

    NASA Astrophysics Data System (ADS)

    Venkatesan, K.; Babu, D. Rajan

    2015-06-01

    Zinc iron oxide (ZnFe2O4) nanoparticles were prepared by self-propagated combustion route.The fuel plays a major role on the formation of structure and particle size. Here three different fuels like alanine, glycine and proline were used to synthesis the zinc iron oxide nanoparticle. Influence of combustion nature through the fuel, the phase formation, particle size, band gap and surface morphology has been modified. The prepared powder was characterized by powder X-ray diffraction method (PXRD), field-emission scanning electron microscopy (FE-SEM) and the composition of the material was analysed by X-ray energy dispersive spectroscopy (EDAX).The elemental mapping was confirmed the uniform distribution of Zn, Fe and O elements in the prepared material of ZnFe2O4.

  11. Banyan latex: a facile fuel for the multifunctional properties of MgO nanoparticles prepared via auto ignited combustion route

    NASA Astrophysics Data System (ADS)

    Kumar, M. R. Anil; Nagaswarupa, H. P.; Anantharaju, K. S.; Gurushantha, K.; Pratapkumar, C.; Prashantha, S. C.; Shashishekar, T. R.; Nagabhushana, H.; Sharma, S. C.; Vidya, Y. S.; Daruka Prasad, B.; Vivek Babu, C. S.; Vishnu Mahesh, K. R.

    2015-09-01

    MgO nanoparticles (MNPs) were prepared by a solution combustion route using banyan tree (BT) latex and glycine as fuels. The powder x-ray diffraction results indicate the formation of a single cubic phase and the crystallite size obtained from transmission electron microscopy was found to be ˜10-15 nm. Scanning electron microscopy result reveals spherical-shaped particles obtained with BT latex. However, in a chemical route, porous and agglomerated particles were obtained. The energy band gap of MNPs obtained using BT latex and a chemical route were found to be in the range 4.85-5.0 eV. Photoluminescence peaks observed at 473, 514, and 588 nm when excited at 433 nm, which were attributed to surface defects. The enhanced photocatalytic activities of spherical MgO were due to smaller crystallite size, higher surface defects, dye sensitization, and capability to reduce the electron-hole pair recombination. Further, green-synthesized MNPs exhibit superior antifungal activity against various plant pathogens. The present studies demonstrated a green engineering route for the synthesis of multifunctional MNPs using BT latex.

  12. Scale control in urea solutions

    SciTech Connect

    Dubin, L.; Diep, D.V.

    1997-08-01

    Legislation to control NO{sub x} emissions, one cause of acid rain and ozone induced smog, has created an impetus to control NO{sub x} emissions. Selective Non Catalytic Reduction (SNCR) using urea chemistry is utilized to control NO{sub x} emissions from boilers, municipal waste incinerators, refinery furnaces, recovery boilers, utilities and other stationary combustion sources. Control requires injecting urea-based solutions into the flue gas at specified temperatures. Urea solutions accelerate CaCO{sub 3} precipitation in industrial waters used for dilution, and thereby interfere with proper application of the urea solution. The negative effect of urea solutions on hardness stability is discussed as well as how CaCO{sub 3} precipitation in urea solution can be controlled by suitable scale inhibitors.

  13. Nanocrystalline particle coatings on alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route.

    PubMed

    Kim, Sang Woo; Jung, Young Mi

    2007-11-01

    We have suggested ultrafine particle coating processes for preparing nanocrystalline particle coated alpha-alumina powders by a carbonate precipitation and thermal-assisted combustion route, which is environmentally friendly. The nanometric ammonium aluminum carbonate hydroxide (AACH) as a precursor for coating of alumina was produced from precipitation reaction of ammonium aluminum sulfate and ammonium hydrogen carbonate. The synthetic crystalline size and morphology were greatly dependent on pH and temperature. By adding ammonium aluminum sulfate solution dispersed the alpha-alumina core particle in the ammonium hydrogen carbonate aqueous solution, nanometric AACH with a size of 5 nm was tightly bonded and uniformly coated on the core powder due to formation of surface complexes by the adsorption of carbonates, hydroxyl and ammonia groups on the surface of aluminum oxide. The synthetic precursor rapidly converted to amorphous- and y-alumina phase without significant change in the morphological features through decomposition of surface complexes and thermal-assisted phase transformation. As a result, the nanocrystalline polymorphic particle coated alpha-alumina core powders with highly uniform distribution were prepared from the route of carbonate precipitation and thermal-assisted combustion. PMID:18047085

  14. Structural, dielectric and magnetic properties of cobalt ferrite prepared using auto combustion and ceramic route

    NASA Astrophysics Data System (ADS)

    Murugesan, C.; Perumal, M.; Chandrasekaran, G.

    2014-09-01

    Cobalt ferrite is synthesized by using low temperature auto combustion and high temperature ceramic methods. The prepared samples have values of lattice constant equal to 8.40 Å and 8.38 Å for auto combustion and ceramic methods respectively. The FTIR spectrum of samples of the auto combustion method shows a high frequency vibrational band at 580 cm-1 assigned to tetrahedral site and a low frequency vibrational band at 409 cm-1 assigned to octahedral site which are shifted to 590 cm-1 and 412 cm-1 for the ceramic method sample. SEM micrographs of samples show a substantial difference in surface morphology and size of the grains between the two methods. The frequency dependent dielectric constant and ac conductivity of the samples measured from 1 Hz to 2 MHz at room temperature are reported. The room temperature magnetic hysteresis parameters of the samples are measured using VSM. The measured values of saturation magnetization, coercivity and remanent magnetization are 42 emu/g, 1553 Oe, 18.5 emu/g for the auto combustion method, 66.7 emu/g, 379.6 Oe, and 17.3 emu/g for the ceramic method, respectively. The difference in preparation methods and size of the grains causes interesting changes in electrical and magnetic properties.

  15. Hydrogen-Assisted IC Engine Combustion as a Route to Hydrogen Implementation

    SciTech Connect

    Andre Boehman; Daniel Haworth

    2008-09-30

    The 'Freedom Car' Initiative announced by the Bush Administration has placed a significant emphasis on development of a hydrogen economy in the United States. While the hydrogen-fueled fuel-cell vehicle that is the focus of the 'Freedom Car' program would rely on electrochemical energy conversion, and despite the large amount of resources being devoted to its objectives, near-term implementation of hydrogen in the transportation sector is not likely to arise from fuel cell cars. Instead, fuel blending and ''hydrogen-assisted'' combustion are more realizable pathways for wide-scale hydrogen utilization within the next ten years. Thus, a large potential avenue for utilization of hydrogen in transportation applications is through blending with natural gas, since there is an existing market for natural-gas vehicles of various classes, and since hydrogen can provide a means of achieving even stricter emissions standards. Another potential avenue is through use of hydrogen to 'assist' diesel combustion to permit alternate combustion strategies that can achieve lower emissions and higher efficiency. This project focused on developing the underlying fundamental information to support technologies that will facilitate the introduction of coal-derived hydrogen into the market. Two paths were envisioned for hydrogen utilization in transportation applications. One is for hydrogen to be mixed with other fuels, specifically natural gas, to enhance performance in existing natural gas-fueled vehicles (e.g., transit buses) and provide a practical and marketable avenue to begin using hydrogen in the field. A second is to use hydrogen to enable alternative combustion modes in existing diesel engines, such as homogeneous charge compression ignition, to permit enhanced efficiency and reduced emissions. Thus, this project on hydrogen-assisted combustion encompassed two major objectives: (1) Optimization of hydrogen-natural gas mixture composition and utilization through laboratory studies of spark-ignition engine operation on H{sub 2}-NG and numerical simulation of the impact of hydrogen blending on the physical and chemical processes within the engine; and (2) Examination of hydrogen-assisted combustion in advanced compression-ignition engine processes. To that end, numerical capabilities were applied to the study of hydrogen assisted combustion and experimental facilities were developed to achieve the project objectives.

  16. Spray-combustion synthesis: Efficient solution route to high-performance oxide transistors

    PubMed Central

    Yu, Xinge; Smith, Jeremy; Zhou, Nanjia; Zeng, Li; Guo, Peijun; Xia, Yu; Alvarez, Ana; Aghion, Stefano; Lin, Hui; Yu, Junsheng; Chang, Robert P. H.; Bedzyk, Michael J.; Ferragut, Rafael; Marks, Tobin J.; Facchetti, Antonio

    2015-01-01

    Metal-oxide (MO) semiconductors have emerged as enabling materials for next generation thin-film electronics owing to their high carrier mobilities, even in the amorphous state, large-area uniformity, low cost, and optical transparency, which are applicable to flat-panel displays, flexible circuitry, and photovoltaic cells. Impressive progress in solution-processed MO electronics has been achieved using methodologies such as sol gel, deep-UV irradiation, preformed nanostructures, and combustion synthesis. Nevertheless, because of incomplete lattice condensation and film densification, high-quality solution-processed MO films having technologically relevant thicknesses achievable in a single step have yet to be shown. Here, we report a low-temperature, thickness-controlled coating process to create high-performance, solution-processed MO electronics: spray-combustion synthesis (SCS). We also report for the first time, to our knowledge, indium-gallium-zinc-oxide (IGZO) transistors having densification, nanoporosity, electron mobility, trap densities, bias stability, and film transport approaching those of sputtered films and compatible with conventional fabrication (FAB) operations. PMID:25733848

  17. Spray-combustion synthesis: efficient solution route to high-performance oxide transistors.

    PubMed

    Yu, Xinge; Smith, Jeremy; Zhou, Nanjia; Zeng, Li; Guo, Peijun; Xia, Yu; Alvarez, Ana; Aghion, Stefano; Lin, Hui; Yu, Junsheng; Chang, Robert P H; Bedzyk, Michael J; Ferragut, Rafael; Marks, Tobin J; Facchetti, Antonio

    2015-03-17

    Metal-oxide (MO) semiconductors have emerged as enabling materials for next generation thin-film electronics owing to their high carrier mobilities, even in the amorphous state, large-area uniformity, low cost, and optical transparency, which are applicable to flat-panel displays, flexible circuitry, and photovoltaic cells. Impressive progress in solution-processed MO electronics has been achieved using methodologies such as sol gel, deep-UV irradiation, preformed nanostructures, and combustion synthesis. Nevertheless, because of incomplete lattice condensation and film densification, high-quality solution-processed MO films having technologically relevant thicknesses achievable in a single step have yet to be shown. Here, we report a low-temperature, thickness-controlled coating process to create high-performance, solution-processed MO electronics: spray-combustion synthesis (SCS). We also report for the first time, to our knowledge, indium-gallium-zinc-oxide (IGZO) transistors having densification, nanoporosity, electron mobility, trap densities, bias stability, and film transport approaching those of sputtered films and compatible with conventional fabrication (FAB) operations. PMID:25733848

  18. Comparison of structural and luminescence properties of Dy{sub 2}O{sub 3} nanopowders synthesized by co-precipitation and green combustion routes

    SciTech Connect

    Chandrasekhar, M.; Nagabhushana, H.; Sudheerkumar, K.H.; Dhananjaya, N.; Sharma, S.C.; Kavyashree, D.; Shivakumara, C.; Nagabhushana, B.M.

    2014-07-01

    Highlights: • Dy{sub 2}O{sub 3} nanopowders were prepared by co-precipitation and eco-friendly green combustion route using plant latex. • Both the products show excellent chromaticity coordinates in the white region, which were quite useful for white LED’s. • Thermoluminescence response of the Dy{sub 2}O{sub 3} product prepared by green synthesis was higher when compared to co-precipitation route. • Structural parameters of Dy{sub 2}O{sub 3} were estimated using Rietveld refinement. • The development of nanosize materials using eco-friendly resources was an attractive non-hazardous chemical route. - Abstract: Dysprosium oxide (Dy{sub 2}O{sub 3}) nanopowders were prepared by co-precipitation (CP) and eco-friendly green combustion (GC) routes. SEM micrographs prepared by CP route show smooth rods with various lengths and diameters while, GC route show porous, agglomerated particles. The results were further confirmed by TEM. Thermoluminescence (TL) responses of the nanopowder prepared by both the routes were studied using γ-rays. A well resolved glow peak at 353 °C along with less intense peak at 183 °C was observed in GC route while, in CP a single glow peak at 364 °C was observed. The kinetic parameters were estimated using Chen’s glow peak route. Photoluminescence (PL) of Dy{sub 2}O{sub 3} shows peaks at 481, 577, 666 and 756 nm which were attributed to Dy{sup 3+} transitions of {sup 4}F{sub 9/2}⟶{sup 6}H{sub 15/2}, {sup 6}H{sub 13/2}, {sup 6}H{sub 11/2} and {sup 6}H{sub 9/2}, respectively. Color co-ordinate values were located in the white region as a result the product may be useful for the fabrication of WLED’S.

  19. A comparative study on structural, morphological and luminescence characteristics of Zn3(VO4)2 phosphor prepared via hydrothermal and citrate-gel combustion routes

    NASA Astrophysics Data System (ADS)

    Pitale, Shreyas S.; Gohain, Mukut; Nagpure, I. M.; Ntwaeaborwa, O. M.; Bezuidenhoudt, Barend C. B.; Swart, H. C.

    2012-05-01

    Comparison of structural, morphological and spectroscopic properties of zinc vanadate Zn3(VO4)2 phosphor synthesized via two different methods, viz. citrate-gel combustion and hydrothermal reaction, is presented. Highly crystalline and pure phase micro-rods are achieved by citrate-gel combustion route. The hydrothermal reaction products exhibit ribbon like structures. X-ray photoelectron spectroscopic investigation reveals the presence of multiple oxidation states of vanadium in the hydrothermally synthesized phosphor. Luminescence properties have also been compared and the effect of divalent cationic substitution (Ca, Mg) is presented.

  20. Combustion

    NASA Technical Reports Server (NTRS)

    Bulzan, Dan

    2007-01-01

    An overview of the emissions related research being conducted as part of the Fundamental Aeronautics Subsonics Fixed Wing Project is presented. The overview includes project metrics, milestones, and descriptions of major research areas. The overview also includes information on some of the emissions research being conducted under NASA Research Announcements. Objective: Development of comprehensive detailed and reduced kinetic mechanisms of jet fuels for chemically-reacting flow modeling. Scientific Challenges: 1) Developing experimental facilities capable of handling higher hydrocarbons and providing benchmark combustion data. 2) Determining and understanding ignition and combustion characteristics, such as laminar flame speeds, extinction stretch rates, and autoignition delays, of jet fuels and hydrocarbons relevant to jet surrogates. 3) Developing comprehensive kinetic models for jet fuels.

  1. Investigation of structural and luminescence properties of Ho(3+) doped YAlO3 nanophosphors synthesized through solution combustion route.

    PubMed

    Premkumar, H B; Ravikumar, B S; Sunitha, D V; Nagabhushana, H; Sharma, S C; Savitha, M B; Mohandas Bhat, S; Nagabhushana, B M; Chakradhar, R P S

    2013-11-01

    YAlO3:Ho(3+) (1-5mol%) nanophosphors have been prepared by solution combustion route using oxalyl dihydrazide (ODH) as a fuel. The final product was well characterized by powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis, etc. PXRD patterns confirm the formation of highly crystalline orthorhombic phase structure. SEM and TEM studies show the particles are dumbbell shape, highly agglomerated and nano-size (∼30nm). The direct energy band gap (Eg) values estimated from Tauc's relation were found to be in the range 5.76-5.99eV. Photoluminescence (PL) studies show green (540 and 548nm) and red (645 and 742nm) emissions upon excited at 452nm wavelength. The emission peaks at ∼742 and 645nm was associated with the transitions of (5)F4→(5)I7 and (5)F5→(5)I8 respectively. The higher energy bands located at 540 and 548nm were associated with (5)F4, (5)S2→(5)I8 transitions. Thermoluminescence (TL) studies of γ-irradiated YAlO3:Ho(3+) (1-5mol%) show two glow peaks at 223 and 325°C recorded at a heating rate of 2.5°Cs(-1). The 223°C glow peak follow linear behavior up to 1kGy and after that, it showed sub-linearity. Up to 1kGy, the phosphor is quite useful in radiation dosimetry. The kinetic parameters (E, b and s) were estimated from glow peak shape method. The CIE coordinate values lies within the green region. Therefore, the present phosphors may have potential application in WLEDs as green phosphor. PMID:23835056

  2. A single phase, red emissive Mg2SiO4:Sm3+ nanophosphor prepared via rapid propellant combustion route

    NASA Astrophysics Data System (ADS)

    Naik, Ramachandra; Prashantha, S. C.; Nagabhushana, H.; Sharma, S. C.; Nagaswarupa, H. P.; Anantharaju, K. S.; Nagabhushana, B. M.; Premkumar, H. B.; Girish, K. M.

    2015-04-01

    Mg2SiO4:Sm3+ (1-11 mol%) nanoparticles were prepared by a rapid low temperature solution combustion route. The powder X-ray diffraction (PXRD) patterns exhibit orthorhombic structure with α-phase. The average crystallite size estimated using Scherer's method, W-H plot and strain-size plots were found to be in the range 25-50 nm and the same was confirmed by Transmission Electron Microscopy (TEM). Scanning electron microscopy (SEM) pictures show porous structure and crystallites were agglomerated. The effect of Sm3+ cations on luminescence of Mg2SiO4 was well studied. Interestingly the samples could be effectively excited with 315 nm and emitted light in the red region, which was suitable for the demands of high efficiency WLEDs. The emission spectra consists of four main peaks which can be assigned to the intra 4-f orbital transitions of Sm3+ ions 4G5/2 → 6H5/2 (576 nm), 4G5/2 → 6H7/2 (611 nm), 4G5/2 → 6H9/2 (656 nm) and 4G5/2 → 6H11/2 (713 nm). The optimal luminescence intensity was obtained for 5 mol% Sm3+ ions. The CIE (Commission International de I'Eclairage) chromaticity co-ordinates were calculated from emission spectra, the values (0.588, 0.386) were close to the NTSC (National Television Standard Committee) standard value of red emission. Coordinated color temperature (CCT) was found to be 1756 K. Therefore optimized Mg2SiO4:Sm3+ (5 mol%) phosphor was quite useful for solid state lighting.

  3. A single phase, red emissive Mg2SiO4:Sm3+ nanophosphor prepared via rapid propellant combustion route.

    PubMed

    Naik, Ramachandra; Prashantha, S C; Nagabhushana, H; Sharma, S C; Nagaswarupa, H P; Anantharaju, K S; Nagabhushana, B M; Premkumar, H B; Girish, K M

    2015-04-01

    Mg2SiO4:Sm3+ (1-11 mol%) nanoparticles were prepared by a rapid low temperature solution combustion route. The powder X-ray diffraction (PXRD) patterns exhibit orthorhombic structure with α-phase. The average crystallite size estimated using Scherer's method, W-H plot and strain-size plots were found to be in the range 25-50 nm and the same was confirmed by Transmission Electron Microscopy (TEM). Scanning electron microscopy (SEM) pictures show porous structure and crystallites were agglomerated. The effect of Sm3+ cations on luminescence of Mg2SiO4 was well studied. Interestingly the samples could be effectively excited with 315 nm and emitted light in the red region, which was suitable for the demands of high efficiency WLEDs. The emission spectra consists of four main peaks which can be assigned to the intra 4-f orbital transitions of Sm3+ ions 4G5/2→6H5/2 (576 nm), 4G5/2→6H7/2 (611 nm), 4G5/2→6H9/2 (656 nm) and 4G5/2→6H11/2 (713 nm). The optimal luminescence intensity was obtained for 5 mol% Sm3+ ions. The CIE (Commission International de I'Eclairage) chromaticity co-ordinates were calculated from emission spectra, the values (0.588, 0.386) were close to the NTSC (National Television Standard Committee) standard value of red emission. Coordinated color temperature (CCT) was found to be 1756 K. Therefore optimized Mg2SiO4:Sm3+ (5 mol%) phosphor was quite useful for solid state lighting. PMID:25638435

  4. UREA INFRASTRUCTURE FOR UREA SCR NOX REDUCTION

    SciTech Connect

    Bunting, Bruce G.

    2000-08-20

    Urea SCR is currently the only proven NOX aftertreatment for diesel engines - high NOX reduction possible - some SCR catalyst systems are robust against fuel sulfur - durability has been demonstrated - many systems in the field - long history in other markets - Major limitations to acceptance - distribution of urea solution to end user - ensuring that urea solution is added to vehicle.

  5. Xenobiotic-urea conjugates; chemical or biological?

    PubMed

    Mitchell, Stephen C

    2014-12-01

    1. Although the major pathways involved in drug metabolism have been elucidated, there remain those routes that may be considered as minor, esoteric, or even artifactual. 2. Conjugation with urea, an abundant, non-toxic, small water soluble molecule, is such a disputed and debatable Phase II pathway. 3. The present article collates data gleaned from the literature concerning xenobiotic-urea conjugation, presents pertinent information resurrecting the controversy and poses questions as to the nature of the phenomenon. PMID:25144804

  6. A facile gel-combustion route for fine particle synthesis of spinel ferrichromite: X-ray and Mössbauer study on effect of Mg and Ni content

    SciTech Connect

    Vader, V.T.; Achary, S.N.; Meena, S.S.

    2014-02-01

    Highlights: • A novel and facile synthesis route. • Transformation of system from random to inverse spinel. • Appearance of superparamagnetism phase. - Abstract: A novel nitrate–citrate gel combustion route was used to prepare fine particle of a series Mg{sub 1−x}Ni{sub x}FeCrO{sub 4} (0.0 ≤ x ≤ 1.0) and its structural properties were investigated. The in situ oxidizing environment provided by the nitrate ions in the gel increases the rate of oxidation and lowers the decomposition temperature of component. All the samples after sintering were characterized at room temperature by X-ray diffraction (XRD) method and Mössbauer spectroscopy techniques. The X-ray and Mössbauer studies confirmed the single phase cubic spinel structure with all Fe ions in 3+ charge state. XRD and Mössbauer studies revealed that the samples of x = 0.0, and 0.2 are random spinel and show rather broad lines, while x = 0.4–1.0 are inverse spinel.

  7. A new solution combustion route to synthesize LiCoO 2 and LiMn 2O 4

    NASA Astrophysics Data System (ADS)

    Kalyani, P.; Kalaiselvi, N.; Muniyandi, N.

    Commercially important, high-voltage, lithium cathodes, such as LiCoO 2 and LiMn 2O 4 have been synthesized from nitrates, following the 'soft-chemistry' approach using starch as the combustion-assisting component. The minimum temperature required for phase formation and the degree of crystallinity has been evaluated from thermal studies and X-ray diffraction analysis, respectively. The starch-assisted combustion (SAC) method produces mono-dispersed powders of grain size below 1.5 μm as observed from scanning electron microscopy and particle-size analysis. The electrochemical activity of the synthesized oxide powders has been examined via cyclic voltammetric and charge-discharge studies using lithium coin cells. Cyclic voltammetric data shows excellent reversibility with respect to Li + and confirms the effect of crystallinity of the compounds on the electrochemical performance of the cathode materials. The electrochemical stability and performance of the cathodes over 30 cycles have been demonstrated with a capacity fade of <10% of the initial capacity. The simplicity and flexibility of this approach towards the synthesis of various other cathode materials is also discussed.

  8. Synthesis and spectroscopic characterization of nanoparticles of TiO2 doped with Pt produced via the self-combustion route

    NASA Astrophysics Data System (ADS)

    Lopera, A. A.; Chavarriaga, E. A.; Estupiñan, H. A.; Valencia, I. C.; Paucar, C.; Garcia, C. P.

    2016-05-01

    Titanium oxide (TiO2) is the most important semiconductor used in photocatalysis. For that reason, most recent scientific studies have focused on improving the absorbance of this material in the visible region. In this paper, we report on the production of nanopowders of TiO2 doped with platinum via the solution combustion synthesis method, using glycine as a fuel at concentrations of 0.3, 0.6, 0.9, and 1.2% w/w of Pt with respect to TiO2 (Pt / TiO2), in order to study the influence of the dopant content on the absorbance spectrum in the visible region. The structure of the samples was characterized using x-ray diffraction and Raman spectroscopy, which confirmed the production of a pure anatase phase. VIS diffuse reflectance spectroscopy confirmed that in the visible region the samples doped with Pt absorb within the range of 400 nm to 800 nm. Field emission scanning electron microscopy and transmission electron microscopy showed the formation of TiO2 nanoparticles with an average size of 13 nm and with spherical morphology. Colorimetry (Commission Internationale de l’Eclairage L *, a *, b *) confirmed photocatalytic activity for the degradation of rhodamine B using visible light. It was concluded that the route of synthesis and the Pt content play important roles in the absorbance spectrum and the activation energy of TiO2.

  9. Water and urea transport in renal microvillus membrane vesicles

    SciTech Connect

    Verkman, A.S.; Dix, J.A.; Seifter, J.L.

    1985-05-01

    Light scattering was used to measure the water and urea permeability of brush border membrane vesicles (BBMV) isolated from rabbit renal cortex. In stop-flow experiments, exposure of BBMV to a 200 mM inwardly directed mannitol gradient gave a monophasic time course of decreasing BBMV volume corresponding to an osmotic water permeability (Pf) of 1.1 X 10(-2) cm/s at 37 degrees C. The temperature dependence of Pf was biphasic with delta H = 2 kcal/mol for T less than 33 degrees C and delta H = 14 kcal/mol for T greater than 33 degrees C. A 200 mM inwardly directed urea gradient gave a biphasic time course of BBMV volume due to rapid water efflux followed by slower urea influx with urea permeability (Purea) of 2.4 X 10(-6) cm/s. Preincubation of BBMV with increasing (urea) reversibly inhibited both urea flux and thiourea flux according to a single-site inhibition model, suggesting a saturable urea carrier. Comparison of BBMV Pf and Purea with proximal tubule transepithelial water and urea transport rates suggests that the permeability of the tubular apical membrane (BBMV) is high enough to support a transcellular route for both osmotic water and urea transport.

  10. Urea Utilization by Leptospira

    PubMed Central

    Kadis, Solomon; Pugh, William L.

    1974-01-01

    One representative of each of five different pathogenic serotypes of Leptospira as well as one saprophytic strain were capable of growing on medium containing urea in place of an ammonium salt as a nitrogen source. Growth of all of the organisms tested on 1% urea was substantial, but only those that exhibited strong urease activity could grow to any appreciable extent on urea at a concentration as high as 2%. Intact urea-grown cells of the pathogenic serotypes tested (grippotyphosa and icterohaemorrhagiae) exhibited urease activity, with the level of activity of the former being considerably greater. No urease could be detected in cells of the saprophytic strain. When the pathogenic leptospires were sonicated or treated with toluene, the urease activity was greatly enhanced. When cultivated on NH4Cl, neither intact nor disrupted cells of any of the strains tested exhibited any urease activity. Cells of the grippotyphosa and icterohaemorrhagiae strains exhibited diauxic growth when cultivated in the presence of both NH4Cl and urea, whereas only monophasic growth could be detected for the saprophytic test strain. The experimental data on urea utilization and urease activity, when considered in the light of previously reported findings on leptospiral pathology, renal physiology, and the role of urease in other bacterial infections, suggests a significant role for leptospiral urease (in addition to other factors) in determining localization of the organism in the kidney and contributing to the resultant kidney pathology. PMID:4426709

  11. Phase evolution and morphology of nanocrystalline BaCe0.9Er0.1O3-δ proton conducting oxide synthesised by a novel modified solution combustion route

    NASA Astrophysics Data System (ADS)

    Babu, A. S.; Bauri, Ranjit

    2015-12-01

    Pure BaCeO3 and 10 mol% Er2O3 doped BaCeO3 (BCE) was synthesised by a novel modified solution combustion synthesis (MCS) route wherein the pH of the precursor solution was varied and the phase formation and morphology were compared with those obtained in conventional solution combustion synthesis (SCS). X-ray diffraction (XRD) studies confirmed the presence of the undesirable BaCO3 phase in the calcined powders prepared using SCS route whereas the powders synthesised with the modified (MCS) route exhibited a single perovskite phase after calcination. Variation in the pH of the precursor solution resulted in a morphology change from a mix of irregular and globular at pH 4 to more spherical at pH 6 and 8. Fourier transform infrared spectroscopy (FT-IR) studies revealed that calcination time has more pronounced effect on phase formation than calcination temperature. A calcination time of 10 h at 1000 °C resulted in negligible amount of BaCO3. Such prolonged calcination treatment resulted in substantial grain growth in the SCS sample while the MCS samples were still in the nanocrystalline form. Absence of the ceria peak (464 cm-1) in the Raman spectra confirmed the presence of a single perovskite BaCeO3 phase in the sintered pellets as well.

  12. Chemiresistor urea sensor

    DOEpatents

    Glass, Robert S.

    1997-01-01

    A sensor to detect and quantify urea in fluids resulting from hemodialysis procedures, and in blood and other body fluids. The sensor is based upon a chemiresistor, which consists of an interdigitated array of metal fingers between which a resistance measured. The interdigitated array is fabricated on a suitable substrate. The surface of the array of fingers is covered with a coating containing the enzyme urease which catalyzes the hydrolysis of urea to form the ammonium ion, the bicarbonate ion, and hydroxide-chemical products which provide the basis for the measured signal. In a typical application, the sensor could be used at bedside, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. Also, the chemiresistor used to detect urea, can be utilized with a reference chemiresistor which does not contain urease, and connected in a differential measurement arrangement, such that the reference chemiresistor would cancel out any fluctuations due to background effects.

  13. Recent Developments In Urea

    NASA Astrophysics Data System (ADS)

    Rosker, Mark J.

    1987-03-01

    Recent developments relating to the application of the urea crystal to non-linear optics reviewed. The urea crystal has been shown to be a useful material for non-linear optics applications. Urea has been studied within the context of both frequency upconversion1 and, more recently, optical parametric oscillation (0P0).2-4 It is particularly the latter application which will be discussed. Urea is an organic crystal within the 42m space group class, the same as the ADP ismorphs. It is optically clear from 200 nm to 1.4 μm, which is consistent with parametric oscillation in the visible and near infrared. Its birefringence is approximately twice that of ADP, which leads to an OPO producing light at shorter wavelengths than for most other non-linear crystals. The non-linear coefficient of urea is approximately 2.5 times that of ADP. While a relatively soft crystal, urea can be optically polished to a flatness of less than an optical wavelength using methods similar to those of ADP. The thermal behavior of urea is excellent; the temperature-dependence of the phase-matching angle is much smaller then ADP. Urea is a hygroscopic crystal, a fact which complicates its practical use. Typically, this problem is overcome by immersing the crystal in an index matching liquid such as hexane. The most difficult problem with regards to the use of urea has been and continues to crystal growth. However, high quality urea crystals of length greater than 20 mm in the (110) direction have been grown from solution in the laboratory. Solution growth requires precise temperature control over very long growth times (on the order of one year). Recently, crystal sizes on the order of 1 cm3 have become commercially available. The urea crystal is positive uniaxial, a characteristic which is advantageous for OPO ications. By utilizing type II (o -> o + e) phase-matching and resonating the ordinary wave, the degree of Poynting vector walk-off of the signal from the pump due to double action is significantly reduced. Furthermore, noncritical phase matching is allowed use the effective d coefficient is a maximum at 90°. The urea optical parametric oscillator has generally consisted of a very simple design. Feedback is accomplished by the use of flat dichroic mirrors, which allow for only one of the generated waves to be resonated. The pump wave is collinear with these generated waves. The pump frequency has usually been 355 nm. Frequency tuning is accomplished through the angular rotation of the crystal. The frequency range covered extends from 498 to 1.23 μm, which is obtained with a single crystal and a single set of dichroic mirrors. Never, a small gap between 640 and 790 nm exists in this range; this is due to metrical obstructions of the particular crystals used and is not thought to be intrinsic.) The mirror reflectivity at the resonated wavelength need not be high, as the total number of round trips allowed during the 7 ns pump pulse is small. The linewidth of the oscillator output was measured to be about 1.2 A near 90° phase-matching.

  14. Urea Cycle Disorders.

    PubMed

    Kleppe, Soledad; Mian, Asad; Lee, Brendan

    2003-07-01

    Urea cycle disorders comprise a group of inborn errors of metabolism that represent unique gene-nutrient interactions whose significant morbidity arises from acute and chronic neurotoxicity associated with often massive hyperammonemia. Current paradigms of treatment are focused on controlling the flux of nitrogen transfer through the hepatic urea cycle by a combination of dietary and pharmacologic approaches. Evolving paradigms include the development of cell and gene therapies. Current research is focused on understanding the pathophysiology of ammonia-mediated toxicity and prevention of neural injury. PMID:12791198

  15. Hereditary urea cycle abnormality

    MedlinePlus

    ... and get enough fluids. Most patients with urea cycle disorders will need to stay in the hospital at some point. During such times, they may be treated with medicines that help the body remove nitrogen-containing wastes. Dialysis may help rid the body ...

  16. Influence of fuel/oxidizer ratio on lattice parameters and morphology of combustion synthesized ZnO powders

    NASA Astrophysics Data System (ADS)

    Sharma, Suchinder K.; Pitale, Shreyas S.; Manzar Malik, M.; Dubey, R. N.; Qureshi, M. S.; Ojha, Siddharth

    2010-02-01

    We report synthesis of ZnO powders via dry combustion route. Among various parameters affecting the product formation during combustion synthesis, one is Fuel-to-oxidizer (F/O) ratio. In the present work, we have used urea as fuel and as a habit modifier. The crystallinity of ZnO is insensitive to F/O variations and fuel lean combustion procedures also leads to appropriate ZnO phase formation. Profile fitting analysis is carried out to correlate the observed and standard diffraction patterns for various samples coded SSD1 to SSD13. Williamson-Hall plot elucidates important contribution of size and strain in the diffraction pattern. Good correlation of lattice parameters is found to exist between calculated and standard values. Wealth of morphological forms (hexagonal pyramidal, spheriulitic, platelet ) and a systematic growth trend is observed. Tailored morphological and consequentially engineered physical properties can be harnessed from ZnO when urea is used. The hexagonal pyramids are anticipated to be suitable for electronic and optoelectronic devices such as field emitters, optoelectronic devices for medical diagnostics, etc. The same morphology can be easily achieved via variation in urea content through cost effective technique.

  17. [Monitoring urea content during hemodialysis].

    PubMed

    Eventov, V L; Andrianova, M Iu; Nefedkin, S I; Eventova, O V

    2003-01-01

    The urea content monitoring during hemodialysis enables the feed-back within the system "patient--artificial kidney--patient". The existing methods of determining the concentration of urea in the dialyzing solution require an expendable reagent, i.e. urease, they are discrete and need often a calibration. The electrochemical urea analyzer, worked out by the authors, is easy in use, it provides a continues information about the urea concentration and does not virtually need any calibration. Besides, the plotter, belonging to the set, provides the graphic information about the dynamic changes of urea content. PMID:12924215

  18. Chemiresistor urea sensor

    DOEpatents

    Glass, R.S.

    1997-12-16

    A sensor is disclosed to detect and quantify urea in fluids resulting from hemodialysis procedures, and in blood and other body fluids. The sensor is based upon a chemiresistor, which consists of an interdigitated array of metal fingers between which a resistance measured. The interdigitated array is fabricated on a suitable substrate. The surface of the array of fingers is covered with a coating containing the enzyme urease which catalyzes the hydrolysis of urea to form the ammonium ion, the bicarbonate ion, and hydroxide-chemical products which provide the basis for the measured signal. In a typical application, the sensor could be used at bedside, in conjunction with an appropriate electronics/computer system, in order to determine the hemodialysis endpoint. Also, the chemiresistor used to detect urea, can be utilized with a reference chemiresistor which does not contain urease, and connected in a differential measurement arrangement, such that the reference chemiresistor would cancel out any fluctuations due to background effects. 16 figs.

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

    PubMed

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

    2016-01-01

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

  20. Study of influence of fuel on dielectric and ferroelectric properties of bismuth titanate ceramics synthesized using solution based combustion technique

    NASA Astrophysics Data System (ADS)

    Subohi, Oroosa; Kumar, G. S.; Malik, M. M.; Kurchania, Rajnish

    2015-03-01

    The effect of fuel characteristics on the processing and properties of bismuth titanate (BIT) ceramics obtained by solution combustion route using different fuels are reported in this paper. Dextrose, urea and glycine were used as fuel in this study. The obtained bismuth titanate ceramics were characterized by using XRD, SEM at different stages of sample preparation. It was observed that BIT obtained by using dextrose as fuel shows higher dielectric constant and higher remnant polarization due to smaller grain size and lesser c-axis growth as compared to the samples with urea and glycine as fuel. The electrical behavior of the samples with respect to temperature and frequency was also investigated to understand relaxation phenomenon.

  1. Utilizing maleic acid as a novel fuel for synthesis of PbFe{sub 12}O{sub 19} nanoceramics via sol–gel auto-combustion route

    SciTech Connect

    Ansari, Fatemeh; Soofivand, Faezeh; Salavati-Niasari, Masoud

    2015-05-15

    PbFe{sub 12}O{sub 19} nanostructures were prepared in an aqueous solution by the sol–gel auto-combustion method using Pb(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} as starting materials and various carboxylic acids, including oxalic acid, malonic acid, succinic acid and maleic acid as fuel and reducing and capping agents. The as-synthesized products were characterized by X- ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectroscopy. The effect of carboxylic acid type, Pb{sup +} {sup 2} to carboxylic acid molar ratio, and calcination temperature was investigated on the morphology of the products and several experiments were carried out to obtain the optimal reaction conditions. It was found that the phase and the morphology of the products are influenced by the investigated parameters. Furthermore, vibrating sample magnetometer (VSM) was used to study the magnetic properties of PbFe{sub 12}O{sub 19} samples. - Graphical abstract: Display Omitted - Highlights: • PbFe{sub 12}O{sub 19} nanoceramics were synthesized from Fe(NO{sub 3}){sub 3} and Pb(NO{sub 3}){sub 2} via the sol–gel auto combustion method. • The maleic acid can be instead of common capping agent and fuel in auto-combustion sol–gel. • The synthesized PbFe{sub 12}O{sub 19} is a hard magnetic material. • The specific saturation magnetization and coercivity are 27 emu/g and 1900 Oe, respectively.

  2. Preparation of a Library of Unsymmetrical Ureas Based on 8-Azabicyclo [3.2.1]Octane Scaffold

    PubMed Central

    Agarkov, Anton; Gilbertson, Scott R.

    2011-01-01

    This paper reports the preparation of a library of unsymmetrical ureas based on 8-azabicyclo [3.2.1]octane scaffold. The reported synthetic route uses nortropane-8-carbonyl chlorides as key intermediates that, when treated with a slight excess of amine, give the corresponding ureas in high yield (129 examples). PMID:18611055

  3. Quantum chemistry-assisted synthesis route development

    NASA Astrophysics Data System (ADS)

    Hori, Kenji; Sumimoto, Michinori; Murafuji, Toshihiro

    2015-12-01

    We have been investigating "quantum chemistry-assisted synthesis route development" using in silico screenings and applied the method to several targets. Another example was conducted to develop synthesis routes for a urea derivative, namely 1-(4-(trifluoromethyl)-2-oxo-2H-chromen-7-yl)urea. While five synthesis routes were examined, only three routes passed the second in silico screening. Among them, the reaction of 7-amino-4-(trifluoromethyl)-2H-chromen-2-one and O-methyl carbamate with BF3 as an additive was ranked as the first choice for synthetic work. We were able to experimentally obtain the target compound even though its yield was as low as 21 %. The theoretical result was thus consistent with that observed. The summary of transition state data base (TSDB) is also provided. TSDB is the key to reducing time of in silico screenings.

  4. Mössbauer and magnetic studies of nanocrystalline zinc ferrites synthesized by microwave combustion method

    NASA Astrophysics Data System (ADS)

    Mahmoud, Mohamed; Hassan, Azza Mohamed; Ahmed, Mamdouh Abdel aal; Zhu, Kaixin; Ganeshraja, Ayyakannu Sundaram; Wang, Junhu

    2016-12-01

    Zinc ferrite nano-crystals were synthesized by a microwave assisted combustion route with varying the urea to metal nitrates (U/N) molar ratio The process takes only a few minutes to obtain Zinc ferrite powders. The Effect of U/N ratio on the obtained phases, particle size, magnetization and structural properties has been investigated. The specimens were characterized by XRD, Mössbauer and VSM techniques. The sample prepared with urea/metal nitrate ratio of 1/1 was a poorly crystalline phase with very small crystallite size. A second phase is also detected in the sample. The crystallite size increases while the second phase decrease with increasing the urea ratio. The saturation magnetization and coercivity of the as prepared nano-particles changed with the change of the U/N ratio. The powder with the highest U/N ratio showed the presence of an unusually high saturation magnetization of 16 emu/g at room temperature. The crystallinity of the as prepared powder was developed by annealing the samples at 700 ∘C and 900 ∘C. Both the saturation magnetization ( Ms) and the remnant magnetization ( Mr) were found to be highly dependent upon the annealing temperature. Mössbauer studies show magnetic ordering in the powder even at room temperature. The Mössbauer and the magnetic parameters of this fraction are different from the standard values for bulk zinc ferrite.

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

    PubMed

    Zimmer, Alex M; Wood, Chris M

    2016-02-01

    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

  6. Urea Biosynthesis Using Liver Slices

    ERIC Educational Resources Information Center

    Teal, A. R.

    1976-01-01

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

  7. What Is a Urea Cycle Disorder?

    MedlinePlus

    ... urine and removed from the body. In urea cycle disorders, the nitrogen accumulates in the form of ammonia, a highly toxic substance, resulting in hyperammonemia (elevated blood ... and severity of urea cycle disorders is highly variable. This depends on the ...

  8. Combustion synthesis and thermoluminescence in YAlO3:Dy3+

    NASA Astrophysics Data System (ADS)

    Dhadade, I. H.; Moharil, S. V.; Dhoble, S. J.; Rahangdale, S. R.

    2016-05-01

    In the Y2O3-Al2O3 system, compounds Y3Al5O12 (yttrium aluminum garnet, YAG),YAlO3 (yttrium aluminum perovskite, YAP), and Y4Al2O9(yttrium aluminate monoclinic, YAM) are well known. Though several soft chemical routes have been explored for synthesis of YAG, YAP and YAM, most of these methods are complex. Moreover, phase pure materials are not obtained in one step and prolonged annealing at temperatures around 1000°C is necessary. In this paper, one step combustion synthesis of the compound YAlO3:Dy3+ is reported using a modified procedure and employing mixed (glycine + urea) fuel. Powder X-ray diffraction patterns confirm the pervoskite phase of YAlO3. Thermoluminescence study shows linear response in wide dose range (0.2 - 1 KGy) suggest the possibility of the present phosphor in dosimeter application.

  9. 40 CFR 721.9892 - Alkylated urea.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  10. Urea biosensor for hemodialysis monitoring

    DOEpatents

    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.

  11. Urea biosensor for hemodialysis monitoring

    DOEpatents

    Glass, Robert S.

    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.

  12. Combustion noise

    NASA Technical Reports Server (NTRS)

    Strahle, W. C.

    1977-01-01

    A review of the subject of combustion generated noise is presented. Combustion noise is an important noise source in industrial furnaces and process heaters, turbopropulsion and gas turbine systems, flaring operations, Diesel engines, and rocket engines. The state-of-the-art in combustion noise importance, understanding, prediction and scaling is presented for these systems. The fundamentals and available theories of combustion noise are given. Controversies in the field are discussed and recommendations for future research are made.

  13. Quantitative and qualitative 1H, 13C, and 15N NMR spectroscopic investigation of the urea-formaldehyde resin synthesis.

    PubMed

    Steinhof, Oliver; Kibrik, Éléonore J; Scherr, Günter; Hasse, Hans

    2014-04-01

    Urea-formaldehyde resins are bulk products of the chemical industry. Their synthesis involves a complex reaction network. The present work contributes to its elucidation by presenting results from detailed NMR spectroscopic studies with different methods. Besides (1)H NMR and (13)C NMR, (15)N NMR spectroscopy is also applied. (15)N-enriched urea was used for the investigations. A detailed NMR signal assignment and a model of the reaction network of the hydroxymethylation step of the synthesis are presented. Because of its higher spectral dispersion and the fact that all key reactions directly involve the nitrogen centers, (15)N NMR provides a much larger amount of detail than do (1)H and (13)C NMR spectroscopy. Symmetric and asymmetric dimethylol urea can be clearly distinguished and separated from monomethylol urea, trimethylol urea, and methylene-bridged urea. The existence of hemiformals of methylol urea is confirmed. 1,3,5-Oxadiazinan-4-on (uron) and its derivatives were not found in the reaction mixtures investigated here but were prepared via alternative routes. The molar ratios of formaldehyde to urea were 1, 2, and 4, the pH values 7.5 and 8.5, and the reaction temperature 60 °C. PMID:24496721

  14. 21 CFR 184.1923 - Urea.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Urea. 184.1923 Section 184.1923 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS § 184.1923 Urea. (a) Urea (CO(NH2)2, CAS Reg. No....

  15. 21 CFR 184.1923 - Urea.

    Code of Federal Regulations, 2010 CFR

    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... Substances Affirmed as GRAS § 184.1923 Urea. (a) Urea (CO(NH2)2, CAS Reg. No. 57-13-6) is the diamide...

  16. Extraction of urea and ammonium ion

    NASA Technical Reports Server (NTRS)

    Anselmi, R. T.; Husted, R. R.; Schulz, J. R.

    1977-01-01

    Water purification system keeps urea and ammonium ion concentration below toxic limits in recirculated water of closed loop aquatic habitat. Urea is first converted to ammonium ions and carbon dioxide by enzygmatic action. Ammonium ions are removed by ion exchange. Bioburden is controlled by filtration through 0.45 micron millipore filters.

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

    PubMed

    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. PMID:26973192

  18. 21 CFR 184.1923 - Urea.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false 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....

  19. Urea Transporter Physiology Studied in Knockout Mice

    PubMed Central

    Li, Xuechen; Chen, Guangping; Yang, Baoxue

    2012-01-01

    In mammals, there are two types of urea transporters; urea transporter (UT)-A and UT-B. The UT-A transporters are mainly expressed in kidney epithelial cells while UT-B demonstrates a broader distribution in kidney, heart, brain, testis, urinary tract, and other tissues. Over the past few years, multiple urea transporter knockout mouse models have been generated enabling us to explore the physiological roles of the different urea transporters. In the kidney, deletion of UT-A1/UT-A3 results in polyuria and a severe urine concentrating defect, indicating that intrarenal recycling of urea plays a crucial role in the overall capacity to concentrate urine. Since UT-B has a wide tissue distribution, multiple phenotypic abnormalities have been found in UT-B null mice, such as defective urine concentration, exacerbated heart blockage with aging, depression-like behavior, and earlier male sexual maturation. This review summarizes the new insights of urea transporter functions in different organs, gleaned from studies of urea transporter knockout mice, and explores some of the potential pharmacological prospects of urea transporters. PMID:22745630

  20. Simulating Combustion

    NASA Astrophysics Data System (ADS)

    Merker, G.; Schwarz, C.; Stiesch, G.; Otto, F.

    The content spans from simple thermodynamics of the combustion engine to complex models for the description of the air/fuel mixture, ignition, combustion and pollutant formation considering the engine periphery of petrol and diesel engines. Thus the emphasis of the book is on the simulation models and how they are applicable for the development of modern combustion engines. Computers can be used as the engineers testbench following the rules and recommendations described here.

  1. Urea transport through composite polyallylamine membranes

    NASA Technical Reports Server (NTRS)

    Ballou, E. V.; Kubo, L. Y.; Spitze, L. A.; Wydeven, T.; Clark, J. A.

    1977-01-01

    Polyallylamine composite reverse osmosis membranes were prepared by plasma polymerization and deposition onto small-pored cellulose acetate/cellulose nitrate films. The polyallylamine coated the porous substrate with a thin uniform polymer film which exhibited water permeability and urea rejection, of interest because of the potential application of reverse osmosis to urine purification in closed environmental systems. The flux of C-14 labeled urea was studied under the influence of osmotic gradients provided by sodium chloride solutions. The urea flux was found to be enhanced by an osmotic pressure gradient in the same direction and diminished, but not prevented, by an opposing osmotic pressure gradient. Consideration is given to the mechanism of the urea transport, as well as to the influence of concentration polarization on the experimental results. The minimization of coupled flow in pores of a critical size range is apparently necessary to improve urea rejection.

  2. Ammonia sanitisation of sewage sludge using urea.

    PubMed

    Fidjeland, Jørgen; Lalander, Cecilia; Jönsson, Håkan; Vinnerås, Björn

    2013-01-01

    The aim of the study was to develop a simple, low-cost treatment for sewage sludge using urea as a sanitising agent. Sewage sludge was spiked with Enterococcus faecalis and Salmonella typhimurium, treated with 0.5, 1, 1.5 and 2% w/w urea at laboratory scale, and the viability was monitored during 4 months of storage at 4, 10 and 22 °C (only 0.5%). A linear relationship was identified between Salmonella spp. inactivation rate and ammonia (NH3) concentration. Temperature had a positive impact on Salmonella spp. inactivation at higher temperatures, but in the range 4-10 °C temperature influenced this inactivation merely by its impact on the ammonia equilibrium. Enterococcus spp. was more persistent and a lag phase of up to 11 weeks was observed. Higher temperature and ammonia concentration reduced the lag phase duration significantly, and also had a clear effect on the inactivation rate for the treatments with 0.5% urea at 22 °C and 2% urea at 4 and 10 °C. Urea sanitisation of sewage sludge can give a 2 log10 reduction of Enterococcus spp. and more than a 5 log10 reduction of Salmonella spp. within 6 weeks with either 0.5% w/w urea at 22 °C or 2% urea at 10 °C. PMID:24185072

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

    PubMed Central

    Muhamad, N; Walker, LR; Simcock, DC; Pedley, KC; Simpson, HV; 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 glutamate dehydrogenase. Results Infective L3 T. circumcincta secreted or excreted urea at 25% of the rate of NH3/NH4 +. The rate of urea efflux was about 84 pmol h−1 (103 larvae)−1 over 4 hours, corresponding to about 11 nmol h−1 mg−1 protein. We could not detect urea aminohydrolase activity, but urea production by both creatine amidinohydrolase and arginine amidinohydrolase could be detected. The apparent K m and V max of creatine amidinohydrolase were 1.1 mM and 48 nmol h−1 mg−1 protein, respectively, and the activity was greatest at pH 8. The apparent K m and V max of arginine amidinohydrolase were 0.7 mM and 62 nmol h−1 mg−1 protein, respectively, and the activity was greatest at pH 7.9. Conclusion The activity of creatine amidinohydrolase and arginine amidinohydrolase was sufficient to account for the rate of urea secretion or excretion. PMID:23682271

  4. Enzymatic Characterization of a Prokaryotic Urea Carboxylase

    PubMed Central

    Kanamori, Takeshi; Kanou, Norihisa; Atomi, Haruyuki; Imanaka, Tadayuki

    2004-01-01

    We identified the first prokaryotic urea carboxylase (UCA) from a member of the alpha subclass of the class Proteobacteria, Oleomonas sagaranensis. This enzyme (O. sagaranensis Uca) was composed of 1,171 amino acids, and its N-terminal region resembled the biotin carboxylase domains of various biotin-dependent carboxylases. The C-terminal region of the enzyme harbored the Met-Lys-Met motif found in biotin carboxyl carrier proteins. The primary structure of the enzyme was 45% identical to that of the urea carboxylase domain of urea amidolyase from Saccharomyces cerevisiae. O. sagaranensis Uca did not harbor the allophanate hydrolase domain found in the yeast enzyme, but a separate gene with structural similarity was found to be adjacent to the uca gene. Purified recombinant O. sagaranensis Uca displayed ATP-dependent carboxylase activity towards urea (Vmax = 21.2 μmol mg−1 min−1) but not towards acetyl coenzyme A (acetyl-CoA) and propionyl-CoA, indicating that the gene encoded a bona fide UCA and not an acetyl-CoA or propionyl-CoA carboxylase. The enzyme also exhibited high levels of activity towards acetamide and formamide. Kinetic parameters of the enzyme reaction were determined with ATP, urea, acetamide, and formamide. O. sagaranensis could grow on urea, acetamide, and formamide as sole nitrogen sources; moreover, ATP-dependent urea-degrading activity was found in cells grown with urea but not in cells grown with ammonia. The results suggest that the UCA of this organism may be involved in the assimilation of these compounds as nitrogen sources. Furthermore, orthologues of the O. sagaranensis uca gene were found to be widely distributed among Bacteria. This implies that there are two systems of urea degradation in Bacteria, a pathway catalyzed by the previously described ureases and the UCA-allophanate hydrolase pathway identified in this study. PMID:15090492

  5. Hydrothermal synthesis of Mg-Al hydrotalcites by urea hydrolysis

    SciTech Connect

    Rao, M. Mohan . E-mail: mandapati@iict.res.in; Reddy, B. Ramachandra; Jayalakshmi, M.; Jaya, V. Swarna; Sridhar, B.

    2005-02-15

    We report a simple method to prepare hydrotalcites involving both urea hydrolysis and hydrothermal synthetic conditions. Out of a series of Mg/Al ratios tried, pure hydrotalcite like phase was obtained for Mg/Al ratios of 1:1 and 2:1. Unlike in conventional co-precipitation method we succeeded in preparing Mg/Al ratio of 1:1 by this route. The high temperature (180 deg. C) applied and pressure developed in the autoclave during the synthesis might have altered the topochemical transformation. The materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared, thermo gravimetric and differential thermal analysis and transmission electron microscopy.

  6. Method for reducing nitrogen oxides in combustion effluents

    DOEpatents

    Zauderer, Bert

    2000-01-01

    Method for reducing nitrogen oxides (NO.sub.x) in the gas stream from the combustion of fossil fuels is disclosed. In a narrow gas temperature zone, NO.sub.x is converted to nitrogen by reaction with urea or ammonia with negligible remaining ammonia and other reaction pollutants. Specially designed injectors are used to introduce air atomized water droplets containing dissolved urea or ammonia into the gaseous combustion products in a manner that widely disperses the droplets exclusively in the optimum reaction temperature zone. The injector operates in a manner that forms droplet of a size that results in their vaporization exclusively in this optimum NO.sub.x -urea/ammonia reaction temperature zone. Also disclosed is a design of a system to effectively accomplish this injection.

  7. Urea and deuterium mixtures at high pressures

    SciTech Connect

    Donnelly, M. Husband, R. J.; Frantzana, A. D.; Loveday, J. S.; Bull, C. L.; Klotz, S.

    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.

  8. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2010 CFR

    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...

  9. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  10. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 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...

  11. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 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...

  12. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 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...

  13. Combustion detector

    NASA Technical Reports Server (NTRS)

    Trimpi, R. L.; Nealy, J. E.; Grose, W. L. (Inventor)

    1973-01-01

    A device has been developed for generating a rapid response signal upon the radiation-emitting combustion reaction of certain gases in order to provide a means for the detection and identification of such reaction and concurrently discriminate against spurious signals. This combustion might be the first stage of a coal mine explosion process, and thereby this device could provide a warning of the impending explosion in time to initiate quenching action. This device has the capability of distinguishing between the light emitted from a combustion reaction and the light emitted by miners' lamps, electric lamps, welding sparks or other spurious events so that the quenching mechanism is triggered only when an explosion-initiating combustion occurs.

  14. Combustion physics

    NASA Astrophysics Data System (ADS)

    Jones, A. R.

    1985-11-01

    Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

  15. Transport of sodium and urea in outer medullary descending vasa recta.

    PubMed Central

    Pallone, T L; Work, J; Myers, R L; Jamison, R L

    1994-01-01

    We dissected and perfused outer medullary vasa recta (OMVR) from vascular bundles in the rat. Permeabilities of sodium (PNa) and urea (Pu) were simultaneously determined from the lumen-to-bath efflux of 22Na and [14C]urea. PNa and Pu were also measured by in vivo microperfusion of descending (DVR) and ascending vasa recta (AVR) at the papillary tip of Munich-Wistar rats. In some OMVR PNa was indistinguishable from zero. The mean +/- SE of PNa (x 10(-5), cm/s) in OMVR was 76 +/- 9. Pu in OMVR was always very high (x 10(-5), cm/s), 360 +/- 14. There was no correlation between OMVR PNa and Pu. Inner medullary AVR and DVR had PNa of 115 +/- 10 and 75 +/- 10, respectively, and Pu of 121 +/- 10 and 76 +/- 11, respectively. PNa and Pu in papillary vasa recta were always nearly identical and highly correlated. Transport of [14C] urea in OMVR was reversibly inhibited by addition of unlabeled urea or phloretin to the bath and lumen, providing evidence for carrier-mediated transport. These data suggest that sodium and urea might traverse the wall of inner medullary vasa recta by a paracellular pathway while urea also crosses by a transcellular route in OMVR. Electron microscopic examination of seven in vitro perfused OMVR revealed no fenestrations and exposure of these vessels to 10 microM calcium ionophore A23187 or 1 nM angiotensin II resulted in reversible contraction, suggesting that in vitro perfused OMVR are DVR only. Images PMID:8282790

  16. Synthesis and Characterization of Branched Poly(ester urea)s with Different Branch Density

    NASA Astrophysics Data System (ADS)

    Yu, Jiayi; Becker, Matthew

    2015-03-01

    A new class of L-phenylalanine-based poly(ester urea)s (PEU) was developed that possess tunable mechanical properties, water uptake ability and degradation rates. Our preliminary data has shown that 1,6-hexanediol L - phenylalanine-based poly(ester urea)s possesses an elastic modulus nearly double that of poly(lactic acid). My work details the synthesis of a series of L - phenylalanine-based poly(ester urea)s possessing a variation in diol chain length and in branch density and shows how these subtle structural differences influence the mechanical properties and in vitro biodegradation rates. The elastic moduli span a range of values that overlap with several currently clinically available degradable polymers. Increasingly the diol chain lengths increases the amount of flexible segment in the chemical structure, which results in reduced elastic modulus values and increased values of elongation at break. Increasing the amount of branch monomer incorporated into the system reduces the molecular entanglement, which also results in decreased elastic modulus values and increased values of elongation at break. The L - phenylalanine-based poly(ester urea)s also exhibited a diol length dependent degradation process that varied between 1-5 % over 16 weeks. Compared with PLLA, PEUs degrade more quickly and the rate can be tuned by changing the diol chain length. PEUs absorb more water and the water uptake ability can be tuned by changing the branch density. This work was supported by Akron Functional Materials Center.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Biofuels combustion.

    PubMed

    Westbrook, Charles K

    2013-01-01

    This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly. PMID:23298249

  19. Biofuels Combustion

    NASA Astrophysics Data System (ADS)

    Westbrook, Charles K.

    2013-04-01

    This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly.

  20. Bubble Combustion

    NASA Technical Reports Server (NTRS)

    Corrigan, Jackie

    2004-01-01

    A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

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

    PubMed Central

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

    2013-01-01

    The branchial mechanism of urea retention in elasmobranchs was investigated using an in vitro isolated-perfused head preparation, as well as in vivo samples, in the spiny dogfish shark. Both in vivo and in control saline perfusions containing 350 mmol L−1 urea, calculated intracellular urea concentrations in gill epithelial cells were close to extracellular concentrations. Urea efflux to the external water fell only non-significantly, and calculated gill intracellular urea concentration did not change when perfusate urea concentration was reduced from 350 to 175 mmol L−1 with osmotic compensation by 175 mmol L−1 mannitol. However, when the urea analogues thiourea or acetamide were present in the perfusate at concentrations equimolar (175 mmol L−1) to those of urea (175 mmol L−1), urea efflux rates were increased 4-fold and 6.5-fold respectively, and calculated gill intracellular urea concentrations were depressed by about 55%. Analogue efflux rates were similar to urea efflux rates. Previous studies have argued that either the basolateral or apical membranes provided the limiting permeability barrier, and/or that a back-transporter on the basolateral membranes of gill cells is responsible for urea retention. The present results provide new evidence that the apical membrane is the limiting factor in maintaining gill urea impermeability, and raise the prospect that a urea back-transporter, which can be competitively inhibited by thiourea and acetamide, operates at the apical membrane. PMID:23638369

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

    PubMed

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

    2013-01-01

    The branchial mechanism of urea retention in elasmobranchs was investigated using an in vitro isolated-perfused head preparation, as well as in vivo samples, in the spiny dogfish shark. Both in vivo and in control saline perfusions containing 350 mmol L(-1) urea, calculated intracellular urea concentrations in gill epithelial cells were close to extracellular concentrations. Urea efflux to the external water fell only non-significantly, and calculated gill intracellular urea concentration did not change when perfusate urea concentration was reduced from 350 to 175 mmol L(-1) with osmotic compensation by 175 mmol L(-1) mannitol. However, when the urea analogues thiourea or acetamide were present in the perfusate at concentrations equimolar (175 mmol L(-1)) to those of urea (175 mmol L(-1)), urea efflux rates were increased 4-fold and 6.5-fold respectively, and calculated gill intracellular urea concentrations were depressed by about 55%. Analogue efflux rates were similar to urea efflux rates. Previous studies have argued that either the basolateral or apical membranes provided the limiting permeability barrier, and/or that a back-transporter on the basolateral membranes of gill cells is responsible for urea retention. The present results provide new evidence that the apical membrane is the limiting factor in maintaining gill urea impermeability, and raise the prospect that a urea back-transporter, which can be competitively inhibited by thiourea and acetamide, operates at the apical membrane. PMID:23638369

  3. Urea synthesis in enterocytes of developing pigs.

    PubMed

    Wu, G

    1995-12-15

    Urea synthesis from ammonia, glutamine and arginine was determined in enterocytes from newborn (0-day-old), 2-21-day-old suckling, and 29-58-day-old post-weaning pigs. Pigs were weaned at 21 days of age. Cells were incubated for 30 min at 37 degrees C in Krebs-Henseleit bicarbonate buffer (pH 7.4) containing (i) 0.5-2 mM NH4Cl plus 0.05-2 mM ornithine and 2 mM aspartate, (ii) 1-5 mM glutamine, or (iii) 0.5-2 mM arginine. In enterocytes from newborn and suckling pigs, there was no measurable synthesis of urea from ammonia, glutamine or arginine, and analysis of amino acids by a sensitive fluorimetric HPLC method revealed the formation of negligible amounts of ornithine from arginine. In contrast, in cells from post-weaning pigs, relatively large amounts of urea and ornithine were produced from ammonia, glutamine and arginine in a dose-dependent manner. To elucidate the mechanism of the developmental change of urea synthesis in pig enterocytes, the activities of urea-cycle enzymes were determined. The activities of enterocyte carbamoyl phosphate synthase I and ornithine carbamoyltransferase were lower in post-weaning pigs than in suckling ones, whereas there was no difference in arginino-succinate lyase. The activities of argininosuccinate synthase and arginase were increased by 4-fold and 50-100-fold, respectively, in enterocytes from post-weaning pigs compared with suckling pigs. The induction of arginase appears to be sufficient to account for the formation of urea from ammonia, glutamine and arginine in post-weaning pig enterocytes. These results demonstrate for the first time the presence of synthesis of urea from extracellular or intramitochondrially generated ammonia in enterocytes of post-weaning pigs. This hitherto unrecognized urea synthesis in these cells may be a first line of defence against the potential toxicity of ammonia produced by the extensive intestinal degradation of glutamine (a major fuel for enterocytes) and derived from diet and luminal micro-organisms. PMID:8554511

  4. The incidence of urea cycle disorders

    PubMed Central

    Summar, Marshall L.; Koelker, Stefan; Freedenberg, Debra; Le Mons, Cynthia; Haberle, Johannes; Lee, Hye-Seung; Kirmse, Brian

    2014-01-01

    A key question for urea cycle disorders is their incidence. In the United States two UCDs, argininosuccinic synthetase and lyase deficiency, are currently detected by newborn screening. We used newborn screening data on over 6 million births and data from the large US and European longitudinal registries to determine how common these conditions are. The incidence for the United States is predicted to be 1 urea cycle disorder patient for every 35,000 births presenting about 113 new patients per year across all age groups. PMID:23972786

  5. 1H NMR relaxation in urea

    NASA Astrophysics Data System (ADS)

    Taylor, R. E.; Bacher, Alfred D.; Dybowski, C.

    2007-11-01

    Proton NMR spin-lattice relaxation times T1 were measured for urea as a function of temperature. An activation energy of 46.3 ± 4.7 kJ/mol was extracted and compared with the range of 38-65 kJ/mol previously reported in the literature as measured by different magnetic resonance techniques. In addition, proton NMR spin-lattice relaxation times in the rotating frame T1 ρ were measured as a function of temperature. These measurements provide acquisition conditions for the 13C and 15N CP/MAS spectra of pure urea in the crystalline phase.

  6. Urea recycling from the renal pelvis in sheep: A study with ( sup 14 C)urea

    SciTech Connect

    Cirio, A.; Boivin, R. )

    1990-05-01

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

  7. [Effects of urea and coated urea on harmful gases concentrations in plastic greenhouse].

    PubMed

    Zhou, Xihong; Zeng, Qingru; Mao, Xiaoyun; Zhang, Litian; Liao, Bohan; Tie, Baiqing; Liao, Zongwen

    2006-09-01

    With simulation test and plastic greenhouse experiment, this paper studied the effects of urea and minerals- coated urea on the soil pH and harmful gases concentrations in plastic greenhouse. The results showed that under simulated condition, the application of these'two N fertilizers led to an initial increase of soil pH, which reached the maximum (an increment of > 50%) within the first week and dropped to the initial level by the end of the fifth week. In plastic greenhouse, applying urea and coated urea resulted in the increase of NH3, NO2 and O3 concentrations. The daily volatilization amount of NH3 and NO2 was higher in urea treatment than in coated urea treatment, and the highest value in urea treatment was 42.36 microg x m(-3) x d(-1) for NH3, 41.95 microg x m(-3) x d(-1) for NO2, and 86.00 microg x m(-3) x d(-1) for O3. The volatilization intensity of NH3 and NO2 was influenced by temperature and sunlight, while the O3 concentration was influenced by sunlight. PMID:17147165

  8. Turbulent combustion

    SciTech Connect

    Talbot, L.; Cheng, R.K.

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  9. Synthesis, thermal and spectral characterization of nanosized Ni(x)Mg(1-x)Al2O4 powders as new ceramic pigments via combustion route using 3-methylpyrozole-5-one as fuel.

    PubMed

    Ahmed, Ibrahim S; Shama, Sayed A; Dessouki, Hassan A; Ali, Ayman A

    2011-10-15

    New Ni(x)Mg(1-x)Al(2)O(4) nanosized in different composition (0.1≤x≤0.8) powders have been synthesized successively for first time by using low temperature combustion reaction (LTCR) of corresponding metal chlorides, carbonates and nitrates as salts with 3-methylpyrozole-5-one (3MP5O) as fuel at 300°C in open air furnace. Magnesium aluminate spinel (MgAl(2)O(4)) was used as crystalline host network for the synthesis of nickel-based nano ceramic pigments. The structure of prepared samples was characterized by using different techniques such as thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). UV/Visible and Diffuse reflectance spectroscopy (DRS) using CIE-L*a*b* parameters methods have been used for color measurements. The obtained results reveal that Ni(x)Mg(1-x)Al(2)O(4) powder of samples is formed in the single crystalline and pure phase with average particle size of 6.35-33.11 nm in the temperature range 500-1200°C. The density, particle size, shape and color are determined for all prepared samples with different calcination time and temperature. PMID:21783407

  10. Generation of semicarbazide from natural azine development in foods, followed by reaction with urea compounds.

    PubMed

    Abernethy, Grant A

    2015-01-01

    This paper proposes a mechanism to explain the trace levels of natural semicarbazide occasionally observed in foods. The analytical derivative of semicarbazide, 2-nitrobenzaldehyde semicarbazone, is often measured as a metabolite marker to detect the widely banned antibiotic nitrofurazone. However, this marker is not specific as semicarbazide may be present in foods for several reasons other than exposure to nitrofurazone. In some cases, an entirely natural origin of semicarbazide is suspected, although up until now there was no explanation about how semicarbazide could occur naturally. In this work, semicarbazide is proposed as being generated from natural food compounds via an azine intermediate. Hydrazine, in the form of azines or hydrazones, may be generated in dilute aqueous solution from the natural food compounds ammonia, hydrogen peroxide and acetone, following known oxidation chemistry. When this mixture was prepared in the presence of ureas such as allantoin, urea, biuret or hydroxyurea, and then analysed by the standard method for the determination of semicarbazide, 2-nitrobenzaldehyde semicarbazone was detected. 2-Nitrobenzaldehyde aldazine was also found, and it may be a general marker for azines in foods. This proposal, that azine formation is central to semicarbazide development, provides a convergence of the published mechanisms for semicarbazide. The reaction starts with hydrogen peroxide, peracetic acid, atmospheric oxygen or hypochlorite; generates hydrazine either by an oxaziridine intermediate or via the chlorination of ammonia; and then either route may converge on azine formation, followed by reaction with a urea compound. Additionally, carbamate ion may speculatively generate semicarbazide by reaction with hydrazine, which might be a significant route in the case of the hypochlorite treatment of foods or food contact surfaces. Significantly, detection of 2-nitrobenzaldehyde semicarbazone may be somewhat artefactual because semicarbazide can form during the acid conditions of analysis, which can free hydrazine in the presence of urea compounds. PMID:26140456

  11. Continuous Crystallization of Urea-Water Mixture

    NASA Astrophysics Data System (ADS)

    Hokamura, Taku; Ohkubo, Hidetoshi; Watanabe, Satoshi; Seki, Mitsuo; Murakoshi, Hiromichi

    Ice slurries have been used as environmentally-friendly secondary refrigerants. In addition to such ice slurries, aqueous solutions in slurry-state have also been put to practical use at temperatures below 0 oC. Urea-water mixture is a multi-component substance that has a eutectic point. If we can form a two-phase fluid substance by the liquid-solid phases at the eutectic point, it can be used as a fluid latent heat storage material, which will maintain the secondary refrigerant in a heat exchanger at constant temperature. In the present study, we propose a urea-water mixture as a novel functional thermal fluid that can be used as a fluid latent heat material. To demonstrate its feasibility, we first measured the latent heat and density of a urea-water mixture, and then used a counter-flow double tube heat exchanger to produce a liquid-solid two-phase flow of the urea-water mixture. This work demonstrates that it is possible to make a fluid latent heat storage material continuously from an aqueous solution at the eutectic point by flowing it through a double tube heat exchanger equipped with a stirrer.

  12. APPLICATION OF MILK UREA NITROGEN VALUES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Statistical analyses using both linear and multi-component regression and mixed effects models have been applied to a number of databases relating milk urea nitrogen (MUN) to factors important for N utilization in lactating dairy cows. Concentrations of MUN are highly correlated to BUN, which is a s...

  13. Aldehyde-containing urea-absorbing polysaccharides

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A novel aldehyde containing polymer (ACP) is prepared by reaction of a polysaccharide with periodate to introduce aldehyde groups onto the C2 - C3 carbon atoms. By introduction of ether and ester groups onto the pendant primary hydroxyl solubility characteristics are modified. The ACP is utilized to absorb nitrogen bases such as urea in vitro or in vivo.

  14. Characterization of urease from Sporosarcina ureae.

    PubMed

    McCoy, D D; Cetin, A; Hausinger, R P

    1992-01-01

    Alkaline stable (pH 7.75-12.5) urease from Sporosarcina ureae was purified over 400-fold by ion exchange and hydrophobic interaction chromatography. The cytoplasmic enzyme was remarkably active with a specific activity of greater than 9300 mumol urea degraded min-1 mg protein-1 at pH 7.5, where it has optimal activity. Although S. ureae is closely related to Bacillus pasteurii, known to possess a homopolymeric urease containing 1 nickel per subunit [M(r) = 65000], the S. ureae enzyme is comprised of three subunits [apparent M(r) = 63,100 (alpha), 14,500 (beta), and 8500 (gamma)] in an estimated alpha beta gamma 2 stoichiometry and contains 2.1 +/- 0.6 nickel ions per alpha beta gamma 2 unit as measured by atomic absorption spectrometry. Stationary phase cultures sometimes possessed low levels of urease activity, but the specific activity of cell extracts of partially purified urease preparations from such cultures could be elevated by heat treatment, dilution, or dialysis to values comparable to those observed in samples from exponentially grown cells. PMID:1510567

  15. Synthesis and characterization of chitosan alkyl urea.

    PubMed

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

    2016-07-10

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

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

    PubMed Central

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

    PubMed

    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. PMID:25440717

  18. A test of improved force field parameters for urea: molecular-dynamics simulations of urea crystals.

    PubMed

    Özpınar, Gül Altınbaş; Beierlein, Frank R; Peukert, Wolfgang; Zahn, Dirk; Clark, Timothy

    2012-08-01

    Molecular-dynamics (MD) simulations of urea crystals of different shapes (cubic, rectangular prismatic, and sheet) have been performed using our previously published force field for urea. This force field has been validated by calculating values for the cohesive energy, sublimation temperature, and melting point from the MD data. The cohesive energies computed from simulations of cubic and rectangular prismatic urea crystals in vacuo at 300 K agreed very well with the experimental sublimation enthalpies reported at 298 K. We also found very good agreement between the melting points as observed experimentally and from simulations. Annealing the crystals just below the melting point leads to reconstruction to form crystal faces that are consistent with experimental observations. The simulations reveal a melting mechanism that involves surface (corner/edge) melting well below the melting point, and rotational disordering of the urea molecules in the corner/edge regions of the crystal, which then facilitates the translational motion of these molecules. PMID:22281810

  19. Regenerative combustion device

    DOEpatents

    West, Phillip B.

    2004-03-16

    A regenerative combustion device having a combustion zone, and chemicals contained within the combustion zone, such as water, having a first equilibrium state, and a second combustible state. Means for transforming the chemicals from the first equilibrium state to the second combustible state, such as electrodes, are disposed within the chemicals. An igniter, such as a spark plug or similar device, is disposed within the combustion zone for igniting combustion of the chemicals in the second combustible state. The combustion products are contained within the combustion zone, and the chemicals are selected such that the combustion products naturally chemically revert into the chemicals in the first equilibrium state following combustion. The combustion device may thus be repeatedly reused, requiring only a brief wait after each ignition to allow the regeneration of combustible gasses within the head space.

  20. Advanced Combustion

    SciTech Connect

    Holcomb, Gordon R.

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  1. MICROWAVE-ASSISTED PREPARATION OF CYCLIC UREAS FROM DIAMINES

    EPA Science Inventory

    Rajender S. Varma* and Yong-Jin Kim
    Cyclic ureas are useful intermediates for a variety of pharmaceuticals and pesticides. One of the attractive approaches for the synthesis of cyclic ureas uses condensation of diamines with urea as a carbonyl source under dynamic evacuation. ...

  2. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  3. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  5. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  6. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium nitrate-urea complex. 176.320 Section 176... Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a..., packaging, transporting, or holding food, subject to the provisions of this section. (a) Sodium...

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    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...

  8. 3. VIEW WEST, ROUTE 130 SOUTH FROM ROUTE 30 EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW WEST, ROUTE 130 SOUTH FROM ROUTE 30 EAST ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  9. 12. VIEW EAST, ROUTE 30 EAST FROM ROUTE 130 SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. VIEW EAST, ROUTE 30 EAST FROM ROUTE 130 SOUTH ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  10. 4. VIEW SOUTH, ROUTE 30 EAST FROM ROUTE 130 NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW SOUTH, ROUTE 30 EAST FROM ROUTE 130 NORTH ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  11. 1. VIEW NORTH, ROUTE 130 NORTH FROM ROUTE 30 EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW NORTH, ROUTE 130 NORTH FROM ROUTE 30 EAST ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  12. 2. VIEW SOUTHEAST, ROUTE 30 EAST FROM ROUTE 30 EAST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTHEAST, ROUTE 30 EAST FROM ROUTE 30 EAST ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  13. 13. VIEW SOUTH, ROUTE 130 SOUTH FROM ROUTE 130 SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW SOUTH, ROUTE 130 SOUTH FROM ROUTE 130 SOUTH ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  14. Solution combustion synthesis of strontium aluminate, SrAl2O4, powders: single-fuel versus fuel-mixture approach.

    PubMed

    Ianoş, Robert; Istratie, Roxana; Păcurariu, Cornelia; Lazău, Radu

    2016-01-14

    The solution combustion synthesis of strontium aluminate, SrAl2O4, via the classic single-fuel approach and the modern fuel-mixture approach was investigated in relation to the synthesis conditions, powder properties and thermodynamic aspects. The single-fuel approach (urea or glycine) did not yield SrAl2O4 directly from the combustion reaction. The absence of SrAl2O4 was explained by the low amount of energy released during the combustion process, in spite of the highly negative values of the standard enthalpy of reaction and standard Gibbs free energy. In the case of single-fuel recipes, the maximum combustion temperatures measured by thermal imaging (482 °C - urea, 941 °C - glycine) were much lower than the calculated adiabatic temperatures (1864 °C - urea, 2147 °C - glycine). The fuel-mixture approach (urea and glycine) clearly represented a better option, since (α,β)-SrAl2O4 resulted directly from the combustion reaction. The maximum combustion temperature measured in the case of a urea and glycine fuel mixture was the highest one (1559 °C), which was relatively close to the calculated adiabatic temperature (1930 °C). The addition of a small amount of flux, such as H3BO3, enabled the formation of pure α-SrAl2O4 directly from the combustion reaction. PMID:26661942

  15. State alternative route designations

    SciTech Connect

    Not Available

    1989-07-01

    Pursuant to the Hazardous Materials Transportation Act (HMTA), the Department of Transportation (DOT) has promulgated a comprehensive set of regulations regarding the highway transportation of high-level radioactive materials. These regulations, under HM-164 and HM-164A, establish interstate highways as the preferred routes for the transportation of radioactive materials within and through the states. The regulations also provide a methodology by which a state may select alternative routes. First,the state must establish a ``state routing agency,`` defined as an entity authorized to use the state legal process to impose routing requirements on carriers of radioactive material (49 CFR 171.8). Once identified, the state routing agency must select routes in accordance with Large Quantity Shipments of Radioactive Materials or an equivalent routing analysis. Adjoining states and localities should be consulted on the impact of proposed alternative routes as a prerequisite of final route selection. Lastly, the states must provide written notice of DOT of any alternative route designation before the routes are deemed effective.

  16. State alternative route designations

    SciTech Connect

    Not Available

    1989-07-01

    Pursuant to the Hazardous Materials Transportation Act (HMTA), the Department of Transportation (DOT) has promulgated a comprehensive set of regulations regarding the highway transportation of high-level radioactive materials. These regulations, under HM-164 and HM-164A, establish interstate highways as the preferred routes for the transportation of radioactive materials within and through the states. The regulations also provide a methodology by which a state may select alternative routes. First,the state must establish a state routing agency,'' defined as an entity authorized to use the state legal process to impose routing requirements on carriers of radioactive material (49 CFR 171.8). Once identified, the state routing agency must select routes in accordance with Large Quantity Shipments of Radioactive Materials or an equivalent routing analysis. Adjoining states and localities should be consulted on the impact of proposed alternative routes as a prerequisite of final route selection. Lastly, the states must provide written notice of DOT of any alternative route designation before the routes are deemed effective.

  17. Defining Dynamic Route Structure

    NASA Technical Reports Server (NTRS)

    Zelinski, Shannon; Jastrzebski, Michael

    2011-01-01

    This poster describes a method for defining route structure from flight tracks. Dynamically generated route structures could be useful in guiding dynamic airspace configuration and helping controllers retain situational awareness under dynamically changing traffic conditions. Individual merge and diverge intersections between pairs of flights are identified, clustered, and grouped into nodes of a route structure network. Links are placed between nodes to represent major traffic flows. A parametric analysis determined the algorithm input parameters producing route structures of current day flight plans that are closest to todays airway structure. These parameters are then used to define and analyze the dynamic route structure over the course of a day for current day flight paths. Route structures are also compared between current day flight paths and more user preferred paths such as great circle and weather avoidance routing.

  18. Osmoregulation in Drosophila melanogaster selected for urea tolerance.

    PubMed

    Pierce, V A; Mueller, L D; Gibbs, A G

    1999-09-01

    Animals may adapt to hyperosmolar environments by either osmoregulating or osmoconforming. Osmoconforming animals generally accumulate organic osmolytes including sugars, amino acids or, in a few cases, urea. In the latter case, they also accumulate 'urea-counteracting' solutes to mitigate the toxic effects of urea. We examined the osmoregulatory adaptation of Drosophila melanogaster larvae selected to live in 300 mmol l(-)(1) urea. Larvae are strong osmoregulators in environments with high NaCl or sucrose levels, but have increased hemolymph osmolarity on urea food. The increase in osmolarity on urea food is smaller in the selected larvae relative to unselected control larvae, and their respective hemolymph urea concentrations can account for the observed increases in total osmolarity. No other hemolymph components appear to act as urea-counteractants. Urea is calculated to be in equilibrium across body compartments in both selected and control larvae, indicating that the selected larvae are not sequestering it to lower their hemolymph osmolarity. The major physiological adaptation to urea does not appear to involve increased tolerance or improved osmoregulation per se, but rather mechanisms (e.g. metabolism, decreased uptake or increased excretion) that reduce overall urea levels and the consequent toxicity. PMID:10441086

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

    PubMed

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

    2016-01-27

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

  20. Neurological implications of urea cycle disorders

    PubMed Central

    Summar, M.; Leonard, J. V.

    2013-01-01

    Summary The urea cycle disorders constitute a group of rare congenital disorders caused by a deficiency of the enzymes or transport proteins required to remove ammonia from the body. Via a series of biochemical steps, nitrogen, the waste product of protein metabolism, is removed from the blood and converted into urea. A consequence of these disorders is hyperammonaemia, resulting in central nervous system dysfunction with mental status changes, brain oedema, seizures, coma, and potentially death. Both acute and chronic hyperammonaemia result in alterations of neurotransmitter systems. In acute hyperammonaemia, activation of the NMDA receptor leads to excitotoxic cell death, changes in energy metabolism and alterations in protein expression of the astrocyte that affect volume regulation and contribute to oedema. Neuropathological evaluation demonstrates alterations in the astrocyte morphology. Imaging studies, in particular 1H MRS, can reveal markers of impaired metabolism such as elevations of glutamine and reduction of myoinositol. In contrast, chronic hyperammonaemia leads to adaptive responses in the NMDA receptor and impairments in the glutamate–nitric oxide–cGMP pathway, leading to alterations in cognition and learning. Therapy of acute hyperammonaemia has relied on ammonia-lowering agents but in recent years there has been considerable interest in neuroprotective strategies. Recent studies have suggested restoration of learning abilities by pharmacological manipulation of brain cGMP with phosphodiesterase inhibitors. Thus, both strategies are intriguing areas for potential investigation in human urea cycle disorders. PMID:18038189

  1. Combustibility of titanium powders

    NASA Technical Reports Server (NTRS)

    Popov, Ye. I.; Poyarkov, V. G.; Finayev, Yu. A.

    1989-01-01

    The combustion of compact samples was studied; the mechanism of autoignition is defined. Several studies are made of the combustibility of titanium using 50 samples. The data provide a clear idea of the combustibility of titanium powders.

  2. Synthesis of functional materials in combustion reactions

    SciTech Connect

    Zhuravlev, V. D. Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

    2015-12-15

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating–reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al{sub 2}O{sub 3}, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO{sub 2}, and manganites, cobaltites, and aluminates of rare earth elements.

  3. Synthesis of functional materials in combustion reactions

    NASA Astrophysics Data System (ADS)

    Zhuravlev, V. D.; Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

    2015-12-01

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating-reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al2O3, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO2, and manganites, cobaltites, and aluminates of rare earth elements.

  4. The effect of urea:nitrate ratio on the structure and luminescence properties of YVO4:Dy3+ phosphors

    NASA Astrophysics Data System (ADS)

    Foka, K. E.; Dejene, B. F.; Swart, H. C.

    2016-01-01

    YVO4:Dy3+ phosphor has been successfully synthesised using combustion method. The dependence of the properties of YVO4:Dy3+ phosphor upon urea:nitrate concentration was investigated. The single tetragonal phase was observed by x-ray diffraction spectra. A highly crystalline YVO4:Dy3+ sample was obtained when increasing the ratio of the urea to 2. The estimated crystalline sizes from the Scherrer's formula were found to be 20, 38, 33, 30, and 27 nm for the sample prepared with the ratio of 1, 2, 2.5, 3 and 4, respectively. The formation of agglomerated particles was observed by Scanning electron microscope images and it was observed that when increasing the concentration of urea further, flake-like particles formed. The diffuse reflectance spectra of YVO4:Dy3+ with various ratios of urea indicated that the determined optical band gap was ranging from 3.3 to 2.3 eV. Luminescence properties of YVO4:Dy3+ showed that the phosphor emit yellow colour at 573 nm and blue colour at 482 nm corresponding to 4F9/2→6H13/2 and 4F9/2→6H15/2 transitions, respectively. A very weak band at 663 nm which correspond to the 4F9/2→6H11/2 transition was also observed. It was found that the Photoluminescent emission intensity increased with an increase in the ratio of urea and reached a maximum at 2 then decreased when increasing the ratio of urea further.

  5. View southwest along Route Canterbury Road (Route 169) showing commercial ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View southwest along Route Canterbury Road (Route 169) showing commercial and residential buildings on the east and west sides of the road - Brooklyn Green, North Green, South Green, & West Green, parts of Brown Road, Canterbury Road (Route 169), Hartford Road (Route 6), Hyde Road, Pomfret Road (Route 169), Prince Hill Road, Providence Road (Route 6), Wauregan Road (Routes 169 & 205), & Wolf Den Road, Brooklyn, Windham County, CT

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

    PubMed

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

    2016-05-01

    The relationship between milk urea nitrogen (MUN; mg of N/dL) and urinary N excretion is affected, among others, by diurnal dynamics in MUN, which in turn is largely influenced by feed intake pattern and characteristics of urea transfer from blood plasma to milk and vice versa. This study aimed to obtain insight in urea transfer characteristics within the mammary gland and from the mammary gland to blood plasma in dairy cows at various concentrations of plasma urea nitrogen (PUN; mg of N/dL) and MUN. Urea transfer from milk to blood plasma and urea transfer within the mammary gland itself was evaluated in a 4×4 Latin square design using 4 lactating multiparous Holstein-Friesian cows (milk production of 39.8±4.70kg/d and 90±3.9 d in milk). Treatments consisted of 4 primed continuous intravenous urea infusions of 0, 5, 10, and 15g of urea/h. Boluses of [(15)N(15)N]urea were injected in cistern milk at 20, 60, and 100 min before the 1700h milking. Milk was collected in portions of approximately 2 L at the 1700h milking. Milk samples were analyzed for urea and enrichment of (15)N-urea. Results from one cow were discarded because of leakage of milk from the teats after injection of boluses of [(15)N(15)N]urea. Increasing urea infusion rate linearly increased PUN from 11.4 (0g of urea/h) to 25.9mg/dL (15g of urea/h) and MUN from 10.3 (0g of urea/h) to 23.5 (15g of urea/h) mg of N/dL. The percentage of injected [(15)N(15)N]urea recovered from milk at the time of injection was not affected by urea infusion rate and varied between 65.1 and 73.0%, indicating that a substantial portion of injected [(15)N(15)N]urea was not accounted for by collected milk. The estimated fractional disappearance rate of (15)N-urea from milk to blood (Kurea; per hour) linearly increased from 0.429 (0g of urea/h) to 0.641 per hour (15g of urea/h). Cistern injected [(15)N(15)N]urea diffused within 20 min after injection toward alveoli milk. Calculations with the average Kurea estimated in this study show that 89% of an initial difference between PUN and MUN will have disappeared after 4 h. In conclusion, urea disappearance from milk in the mammary gland is substantial, as well as the intramammary urea exchange between cistern, duct, and alveoli milk. However, results have to be interpreted with caution given the lack of full recovery of dosed (15)N urea at time of injection. Information on Kurea is useful to quantify the effects of diurnal variation in PUN on MUN, which enhances the utility of MUN as an indicator for N excretion in urine. PMID:26947294

  7. Contact Graph Routing

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic. The information carried by CGR contact plan messages is useful not only for dynamic route computation, but also for the implementation of rate control, congestion forecasting, transmission episode initiation and termination, timeout interval computation, and retransmission timer suspension and resumption.

  8. Combustion chemistry

    SciTech Connect

    Brown, N.J.

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  9. Gaseous emissions from waste combustion.

    PubMed

    Werther, Joachim

    2007-06-18

    An overview is given on methods and technologies for limiting the gaseous emissions from waste combustion. With the guideline 2000/76/EC recent European legislation has set stringent limits not only for the mono-combustion of waste in specialized incineration plants but also for co-combustion in coal-fired power plants. With increased awareness of environmental issues and stepwise decrease of emission limits and inclusion of more and more substances into the network of regulations a multitude of emission abatement methods and technologies have been developed over the last decades. The result is the state-of-the-art waste incinerator with a number of specialized process steps for the individual components in the flue gas. The present work highlights some new developments which can be summarized under the common goal of reducing the costs of flue gas treatment by applying systems which combine the treatment of several noxious substances in one reactor or by taking new, simpler routes instead of the previously used complicated ones or - in the case of flue gas desulphurisation - by reducing the amount of limestone consumption. Cost reduction is also the driving force for new processes of conditioning of nonhomogenous waste before combustion. Pyrolysis or gasification is used for chemical conditioning whereas physical conditioning means comminution, classification and sorting processes. Conditioning yields a fuel which can be used in power plants either as a co-fuel or a mono-fuel and which will burn there under much better controlled conditions and therefore with less emissions than the nonhomogeneous waste in a conventional waste incinerator. Also for cost reasons, co-combustion of wastes in coal-fired power stations is strongly pressing into the market. Recent investigations reveal that the co-firing of waste can also have beneficial effects on the operating behavior of the boiler and on the gaseous emissions. PMID:17339077

  10. Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction.

    PubMed

    Periyasamy, Sivakumar; Subramanian, Palaniappan; Levi, Elena; Aurbach, Doron; Gedanken, Aharon; Schechter, Alex

    2016-05-18

    Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively. PMID:27123873

  11. ROUTE-SPECIFIC DOSIMETRY

    EPA Science Inventory

    The capacity to perform route-to-route extrapolation of toxicity data is becoming increasingly crucial to the Agency, with a number of strategies suggested and demonstrated. One strategy involves using a combination of existing data and modeling approaches. This strategy propos...

  12. One step combustion synthesis and thermoluminescence in Y3Al5O12:Ce3+

    NASA Astrophysics Data System (ADS)

    Dhadade, I. H.; Moharil, S. V.; Dhoble, S. J.; Rahangdale, S. R.

    2016-05-01

    In the present paper one step combustion synthesis of compound Y3Al5O12:Ce3+ is reported using a modified procedure and employing mixed (Urea + Glycine) as fuel. Powder X-ray diffraction confirms the formation of said compound. Thermoluminescence study over the wide gamma exposure (1KGy - 13 KGy) Suggests the possible use of the phosphor in dosimetric application.

  13. Urea hydrolysis and calcium carbonate reaction fronts

    NASA Astrophysics Data System (ADS)

    Fox, D. T.; Redden, G. D.; Henriksen, J.; Fujita, Y.; Guo, L.; Huang, H.

    2010-12-01

    The mobility of toxic or radioactive metal contaminants in subsurface environments can be reduced by the formation of mineral precipitates that form co-precipitates with the contaminants or that isolate them from the mobile fluid phase. An engineering challenge is to control the spatial distribution of precipitation reactions with respect to: 1) the location of a contaminant, and 2) where reactants are introduced into the subsurface. One strategy being explored for immobilizing contaminants, such as Sr-90, involves stimulating mineral precipitation by forming carbonate ions and hydroxide via the in situ, microbially mediated hydrolysis of urea. A series of column experiments have been conducted to explore how the construction or design of such an in situ reactant production strategy can affect the temporal and spatial distribution of calcium carbonate precipitation, and how the distribution is coupled to changes in permeability. The columns were constructed with silica gel as the porous media. An interval midway through the column contained an adsorbed urease enzyme in order to simulate a biologically active zone. A series of influent solutions were injected to characterize hydraulic properties of the column (e.g., bromide tracer), profiles of chemical conditions and reaction products as the enzyme catalyzes urea hydrolysis (e.g., pH, ammonia, urea), and changes that occur due to CaCO3 precipitation with the introduction of a calcium+urea solutions. In one experiment, hydraulic conductivity was reduced as precipitate accumulated in a layer within the column that had a higher fraction of fine grained silica gel. Subsequent reduction of permeability and flow (for a constant head condition) resulted in displacement of the hydrolysis and precipitation reaction profiles upstream. In another experiment, which lacked the physical heterogeneity (fine grained layer), the precipitation reaction did not result in loss of permeability or flow velocity and the reaction profile, characterized by the pH profile and hydrolysis reaction species, was extended downstream of the enzyme zone. Downstream extension of the reaction profile was due partially to the partial mobility of the enzyme in the column. The experiments are helping to illustrate the complexity of transient reaction fronts as well as the needs and challenges for advanced modeling approaches. A modeling platform developed at the Idaho National Laboratory, which is capable of simulating tightly coupled physical-chemical processes (the Reactive Transport simulator), is being applied to pre-experimental simulations and post-experimental interpretation of results.

  14. Action of Urea on Tobacco Mosaic Virus

    PubMed Central

    Buzzell, Anne

    1962-01-01

    The rate of urea degradation is not uniform over the tobacco mosaic virus (TMV) rod, as might be expected since the protein subunits appear to be chemically identical. Only two stable intermediates are formed; the four components with sedimentation constants, S4020, about 80, 120, 140, and 165 correspond to the two intermediates with and without RNA tails. Analysis of the reaction kinetics for the disappearance of whole virus and of the first intermediate was made in terms of a new hypothesis concerning protein bonding. PMID:13875271

  15. The SLC14 gene family of urea transporters.

    PubMed

    Shayakul, Chairat; Hediger, Matthias A

    2004-02-01

    Carrier-mediated urea transport allows rapid urea movement across the cell membrane, which is particularly important in the process of urinary concentration and for rapid urea equilibrium in non-renal tissues. Urea transporters mediate passive urea uptake that is inhibited by phloretin and urea analogues. Facilitated urea transporters are divided into two classes: (1) the renal tubular/testicular type of urea transporter, UT-A1 to -A5, encoded by alternative splicing of the SLC14A2 gene, and (2) the erythrocyte urea transporter UT-B1 encoded by the SLC14A1 gene. The primary structure of urea transporters is unique, consisting of two extended, hydrophobic, membrane-spanning domains and an extracellular glycosylated-connecting loop. UT-A1 is the result of a gene duplication of this two-halves-structure, and the duplicated portions are linked together by a large intracellular hydrophilic loop, carrying several putative protein kinase A (PKA) and -C (PKC) phosphorylation sites. UT-A1 is located in the apical membrane of the kidney inner medullary collecting duct cells, where it is stimulated acutely by cAMP-mediated phosphorylation in response to the antidiuretic hormone vasopressin. Vasopressin also up-regulates UT-A2 mRNA/protein expression in the descending thin limb of the loops of Henle. UT-A1 and UT-A2 are regulated independently and respond differently to changes in dietary protein content. UT-A3 and UT-A4 are located in the rat kidney medulla and UT-A5 in the mouse testis. The widely expressed UT-B participates in urea recycling in the descending vasa recta, as demonstrated by a relatively mild "urea-selective" urinary concentrating defect in transgenic UT-B null mice and individuals with the Jk(null) blood group. PMID:12856182

  16. Urea kinetics of a carnivore, Felis silvestris catus.

    PubMed

    Russell, K; Lobley, G E; Rawlings, J; Millward, D J; Harper, E J

    2000-11-01

    The effect of two levels of dietary protein energy, moderate (20%; MP) and high (70%; HP), on urea kinetics in eleven domestic cats was studied. After a 3-week prefeed, a single dose of [(15)N(15)N]urea was administered, and urine and faeces collected over the subsequent 5 d. For each 24 h period, total urea and enrichment of [(15)N(15)N]- and [(15)N(14)N]urea in urine were determined, and a model applied to calculate urea production, entry into the gastrointestinal tract, recycling to urine or faeces and, by difference, retention by the body and potentially available for anabolism. Urea production and excretion increased with dietary protein level Most of the urea produced was excreted, with only a small proportion entering the gut, and with the pattern of urea disposal not significantly different between the HP and MP diets. Thus, the percentages of urea production available to the gut were 15% (MP) and 12% (HP), of which 57% (MP) and 59% (HP) was recycled in the ornithine cycle, 40% (MP and HP) was potentially available for anabolism and the rest lost as faecal N. As a percentage of urea produced the amount potentially available for anabolism was very low at 6.41% (MP diet) and 4.79% (HP diet). In absolute terms urea entering the gut, being recycled in the ornithine cycle and potentially available for anabolism was significantly higher on the HP diet These results show that cats operate urea turnover, but at a lower rate, and with less nutritional sensitivity than has been reported for other species. PMID:11177172

  17. The electrophoresis of transferrins in urea/polyacrylamide gels.

    PubMed Central

    Evans, R W; Williams, J

    1980-01-01

    The denaturation of transferrin by urea has been studied by (a) electrophoresis in polyacrylamide gels incorporating a urea gradient, (b) measurements of the loss of iron-binding capacity and (c) u.v. difference spectrometry. In human serum transferrin and hen ovotransferrin the N-terminal and C-terminal domains of the iron-free protein were found to denature at different urea concentrations. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 7. PMID:7213345

  18. Rotary internal combustion engine

    SciTech Connect

    Le, L.K.

    1990-11-20

    This patent describes an internal combustion engine comprising; a rotary compressor mechanism; a rotary expander mechanism; and combustion chamber means disposed between the compressor mechanism and the expander mechanism, whereby compressed air is delivered to the combustion chamber through the compressor discharge port, and pressurized gas is delivered from the combustion chamber into the expander mechanism through the pressurized gas intake port.

  19. New potent calcimimetics: II. Discovery of benzothiazole trisubstituted ureas.

    PubMed

    Deprez, Pierre; Temal, Taoues; Jary, Hélène; Auberval, Marielle; Lively, Sarah; Guédin, Denis; Vevert, Jean-Paul

    2013-04-15

    Following the identification of trisubstituted ureas as a promising new chemical series of allosteric modulators of the calcium sensing receptor (CaSR), we further explored the SAR around the urea substitution, leading to the discovery of benzothiazole urea compound 13. This compound is a potent calcimimetic with an EC50=20 nM (luciferase assay). Evaluated in an in vivo model of chronic renal failure (short term and long term in 5/6 nephrectomized rats), benzothiazole urea 13 significantly decreased PTH levels after oral administration while keeping calcemia within the normal range. PMID:23499504

  20. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Increased emphasis is placed on fundamental and generic research at Lewis Research Center with less systems development efforts. This is especially true in combustion research, where the study of combustion fundamentals has grown significantly in order to better address the perceived long term technical needs of the aerospace industry. The main thrusts for this combustion fundamentals program area are as follows: analytical models of combustion processes, model verification experiments, fundamental combustion experiments, and advanced numeric techniques.

  1. Coal combustion science

    SciTech Connect

    Hardesty, D.R.; Baxter, L.L.; Fletcher, T.H.; Mitchell, R.E.

    1990-11-01

    The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center (PETC) Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency (IEA) Coal Combustion Science Project. Specific tasks include: coal devolatilization, coal char combustion, and fate of mineral matter during coal combustion. 91 refs., 40 figs., 9 tabs.

  2. Understanding individual routing behaviour.

    PubMed

    Lima, Antonio; Stanojevic, Rade; Papagiannaki, Dina; Rodriguez, Pablo; González, Marta C

    2016-03-01

    Knowing how individuals move between places is fundamental to advance our understanding of human mobility (González et al. 2008 Nature 453, 779-782. (doi:10.1038/nature06958)), improve our urban infrastructure (Prato 2009 J. Choice Model. 2, 65-100. (doi:10.1016/S1755-5345(13)70005-8)) and drive the development of transportation systems. Current route-choice models that are used in transportation planning are based on the widely accepted assumption that people follow the minimum cost path (Wardrop 1952 Proc. Inst. Civ. Eng. 1, 325-362. (doi:10.1680/ipeds.1952.11362)), despite little empirical support. Fine-grained location traces collected by smart devices give us today an unprecedented opportunity to learn how citizens organize their travel plans into a set of routes, and how similar behaviour patterns emerge among distinct individual choices. Here we study 92 419 anonymized GPS trajectories describing the movement of personal cars over an 18-month period. We group user trips by origin-destination and we find that most drivers use a small number of routes for their routine journeys, and tend to have a preferred route for frequent trips. In contrast to the cost minimization assumption, we also find that a significant fraction of drivers' routes are not optimal. We present a spatial probability distribution that bounds the route selection space within an ellipse, having the origin and the destination as focal points, characterized by high eccentricity independent of the scale. While individual routing choices are not captured by path optimization, their spatial bounds are similar, even for trips performed by distinct individuals and at various scales. These basic discoveries can inform realistic route-choice models that are not based on optimization, having an impact on several applications, such as infrastructure planning, routing recommendation systems and new mobility solutions. PMID:26962031

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

    NASA Astrophysics Data System (ADS)

    Banchorndhevakul, Siriwattana

    2002-08-01

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

  4. Routing Vehicles with Ants

    NASA Astrophysics Data System (ADS)

    Tan, Wen Fang; Lee, Lai Soon; Majid, Zanariah Abdul; Seow, Hsin Vonn

    Routing vehicles involve the design of an optimal set of routes for a fleet of vehicles to serve a number of customers with known demands. This research develops an Ant Colony Optimization for the vehicle routing with one central depot and identical vehicles. The procedure simulates the behavior of real ants that always find the shortest path between their nest and a food source through a form of communication, pheromone trail. Finally, preliminary results on the learning of the algorithm testing on benchmark data set will be presented in this paper.

  5. Combustion 2000

    SciTech Connect

    2000-06-30

    This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench Scale Activities

  6. Combustion 2000

    SciTech Connect

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    This report is a presentation of work carried out on Phase II of the HIPPS program under DOE contract DE-AC22-95PC95144 from June 1995 to March 2001. The objective of this report is to emphasize the results and achievements of the program and not to archive every detail of the past six years of effort. These details are already available in the twenty-two quarterly reports previously submitted to DOE and in the final report from Phase I. The report is divided into three major foci, indicative of the three operational groupings of the program as it evolved, was restructured, or overtaken by events. In each of these areas, the results exceeded DOE goals and expectations. HIPPS Systems and Cycles (including thermodynamic cycles, power cycle alternatives, baseline plant costs and new opportunities) HITAF Components and Designs (including design of heat exchangers, materials, ash management and combustor design) Testing Program for Radiative and Convective Air Heaters (including the design and construction of the test furnace and the results of the tests) There are several topics that were part of the original program but whose importance was diminished when the contract was significantly modified. The elimination of the subsystem testing and the Phase III demonstration lessened the relevance of subtasks related to these efforts. For example, the cross flow mixing study, the CFD modeling of the convective air heater and the power island analysis are important to a commercial plant design but not to the R&D product contained in this report. These topics are of course, discussed in the quarterly reports under this contract. The DOE goal for the High Performance Power Plant System ( HIPPS ) is high thermodynamic efficiency and significantly reduced emissions. Specifically, the goal is a 300 MWe plant with > 47% (HHV) overall efficiency and {le} 0.1 NSPS emissions. This plant must fire at least 65% coal with the balance being made up by a premium fuel such as natural gas. To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization issues of fabrication and reliability, availability and maintenance. The program that has sought to develop and implement these HIPPS designs is outlined below.

  7. Class network routing

    DOEpatents

    Bhanot, Gyan; Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Takken, Todd E.; Vranas, Pavlos M.

    2009-09-08

    Class network routing is implemented in a network such as a computer network comprising a plurality of parallel compute processors at nodes thereof. Class network routing allows a compute processor to broadcast a message to a range (one or more) of other compute processors in the computer network, such as processors in a column or a row. Normally this type of operation requires a separate message to be sent to each processor. With class network routing pursuant to the invention, a single message is sufficient, which generally reduces the total number of messages in the network as well as the latency to do a broadcast. Class network routing is also applied to dense matrix inversion algorithms on distributed memory parallel supercomputers with hardware class function (multicast) capability. This is achieved by exploiting the fact that the communication patterns of dense matrix inversion can be served by hardware class functions, which results in faster execution times.

  8. Ammonia and urea excretion in the tidepool sculpin (Oligocottus maculosus): sites of excretion, effects of reduced salinity and mechanisms of urea transport.

    PubMed

    Wright, P A; Part, P; Wood, C M

    1995-04-01

    Tidepool sculpins live in a variable environment where water temperature, salinity, gas tensions, and pH can change considerably with the daily tide cycle. Tidepool sculpins are primarily ammoniotelic, with 8-17% of nitrogen wastes excreted as urea. The majority of net ammonia (J(net) amm; 85%) and urea (J(net) urea; 74%) excretion occurred across the gill, with the remainder excreted across the skin, the kidney, and/or gut. Acute (2h) exposure to 50% seawater significantly increased J(net) urea (2.8-fold), but reduced J(net) amm (3.5-fold). In fish exposed to 50% seawater for 1 week, J(net) urea returned to control values, but J(net) amm remained slightly depressed. Unidirectional urea influx (J(in) urea) and efflux (J(out) urea) were measured using(14)C-urea to determine if urea was excreted across the gills by simple diffusion or by a carrier-mediated mechanism. J(in) urea increased in a linear manner with increasing urea water levels (0-11 mmol N l(-1)), while J(out) urea was independent of external urea concentrations. As well, J(net) urea and J(out inurea) were not significantly different from one another, indicating the absence of "back transport". Urea analogs and transport inhibitors added to the water did not have any consistent effect on unidirectional urea flux. These results demonstrate that ammonia and urea excretion rates and sites of excretion in tidepool sculpins are very similar to those found in other marine and freshwater teleosts. Urea and ammonia may play a role in osmoregulation as excretion rates and tissue levels were influenced by changes in water salinity. Finally, we found no evidence for a specific urea carrier; branchial urea excretion is likely dependent on simple diffusion. PMID:24197359

  9. Railroad Routing Model

    Energy Science and Technology Software Center (ESTSC)

    1995-01-05

    INTERLINE/PC is an interactive program designed to simulate the routing practices of the United States rail system. The rail industry is divided into a large number of independent competing companies. The INTERLINE data base represents these rail companies as 94 separate subnetworks. An additional two subnetworks represent navigable inland/intracoastal and deep draft marine routes. Interchange points between individual rail systems and waterway systems are also identified.

  10. Regulation of urea production by glucose infusion in vivo.

    PubMed

    Jahoor, F; Wolfe, R R

    1987-11-01

    We have investigated the acute in vivo regulation of urea production in normal postabsorptive volunteers by administering a primed constant infusion of 15N2-urea to measure urea production during the constant intravenous infusion of equivalent molar quantities of exogenous nitrogen, given as alanine or glutamine, either with or without a simultaneous infusion of glucose at 4 mg.kg-.min-1. These responses were compared with the response to the infusion of glucose alone. Both amino acid infusions elicited significant (P less than 0.05) and identical (26%) increases in urea production over 4 h. When the glucose infusion was added to the amino acid infusions, urea production remained constant, despite the comparable increases in plasma total nonessential amino nitrogen, as were observed with the amino acid infusions alone. Glucose infused alone elicited a significant (P less than 0.05) reduction (18%) in urea production but no corresponding change in plasma total amino nitrogen. We conclude that 1) infused glucose or its hormonal response suppresses urea production by blunting the normal hepatic ureagenic response to a fixed nitrogen load, 2) this suppressive effect is not mediated via a reduction in substrate (nitrogen) supply, and 3) the inhibition of hepatic gluconeogenesis from amino acids represents one component of this suppressive effect, and direct suppression of urea cycle activity probably represents another component. PMID:3688224

  11. Measuring urea persistence, distribution and transport on coastal plain soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The persistence and mobility of urea, an organic form of nitrogen present in animal manures and commercial fertilizers, has rarely been studied and measured, because it is assumed to undergo rapid hydrolysis to ammonia. However, preliminary studies have shown urea to exist in leachate and runoff sev...

  12. 40 CFR 721.9925 - Aminoethylethylene urea methacrylamide.

    Code of Federal Regulations, 2010 CFR

    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...

  13. Urea kinetics in neonates receiving total parenteral nutrition.

    PubMed

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

    1993-07-01

    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. Urea production was mean (SD) 84 (44) mg nitrogen/kg/day, or 50% of intake. Urinary excretion of urea, 39 (16) mg nitrogen/kg/day, was 40% of production. Therefore 54% of urea production was salvaged through the lower bowel, 45 (35) mg nitrogen/kg/day. It is concluded that even in infants who have never had a regular dietary intake the microflora of the lower bowel is sufficiently developed to salvage urea nitrogen for further metabolic interaction, however it is not clear whether the rate of salvage is adequate to satisfy the metabolic demand. PMID:8346947

  14. Molecular Basis of the Apparent Near Ideality of Urea Solutions

    PubMed Central

    Kokubo, Hironori; Rsgen, Jrg; Bolen, D. Wayne; Pettitt, B. Montgomery

    2007-01-01

    Activity coefficients of urea solutions are calculated to explore the mechanism of its solution properties, which form the basis for its well-known use as a strong protein denaturant. We perform free energy simulations of urea solutions in different urea concentrations using two urea models (OPLS and KBFF models) to calculate and decompose the activity coefficients. For the case of urea, we clarify the concept of the ideal solution in different concentration scales and standard states and its effect on our subsequent analysis. The analytical form of activity coefficients depends on the concentration units and standard states. For both models studied, urea displays a weak concentration dependence for excess chemical potential. However, for the OPLS force-field model, this results from contributions that are independent of concentration to the van der Waals and electrostatic components whereas for the KBFF model those components are nontrivial but oppose each other. The strong ideality of urea solutions in some concentration scales (incidentally implying a lack of water perturbation) is discussed in terms of recent data and ideas on the mechanism of urea denaturation of proteins. PMID:17693466

  15. 75 FR 74746 - Solid Urea From Russia and Ukraine

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-01

    ... from Russia and Ukraine (64 FR 62653). Following second five-year reviews by Commerce and the... imports of solid urea from Russia and Ukraine (71 FR 581). The Commission is now conducting third reviews... COMMISSION Solid Urea From Russia and Ukraine AGENCY: United States International Trade Commission....

  16. Combustion chamber for internal combustion engines

    SciTech Connect

    Yanagisawa, N.; Sato, Y.

    1989-01-24

    A combustion chamber is described for an internal combustion engine, comprising: a main combustion chamber defined by a recess in the top of a piston of the engine, the main combustion chamber being formed with its opening diameter progressively enlarged downwards in the axial direction of the main combustion chamber, and a lip part formed along the periphery of the opening of the main combustion chamber, the lip part protruding radially and inwardly; a swirl chamber formed inside a cylinder head of the engine; a passage for connecting the main combustion chamber with the swirl chamber, the passage being defined in the cylinder head and having a wall portion tangentially aligned with a portion of the wall of the swirl chamber corresponding to the upstream end of the swirl chamber such that the compressed air introduced into the swirl chamber is substantially directed along the wall of the swirl chamber to swirl therein, the passage having a longitudinal axis generally directed to the central portion of the main combustion chamber; and a fuel injection nozzle means for supplying fuel mist into the swirl chamber through the passage as well as into the main combustion chamber, the fuel injection nozzle means directing fuel mist into the swirl chamber substantially parallel to the tangential wall portion such that the fuel mist is carried by the compressed air directed along the tangential wall and revolved with the swirl chamber.

  17. Combustion 2000

    SciTech Connect

    1999-12-31

    This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site-specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench Scale Activities

  18. Structure and permeation mechanism of a mammalian urea transporter

    SciTech Connect

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

    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.

  19. Postmortem Blood Sugar and Blood Urea Nitrogen Determinations

    PubMed Central

    Fekete, John F.; Kerenyi, Norbert A.

    1965-01-01

    Glucose and urea nitrogen determinations were made on blood and cerebrospinal fluid samples collected during 160 postmortem examinations in order to determine the usefulness of such tests in diagnosing diabetes and uremia at the time of autopsy. The results indicated that: (1) Blood is unsuitable for postmortem glucose determination, and no postmortem normal can be established. (2) Cerebrospinal fluid gave more uniform but very low glucose values. (3) Diabetics as a group had very high postmortem glucose levels but showed a marked overlap with non-diabetics. (4) Infants less than 3 months of age showed high postmortem glucose values. (5) Postmortem blood urea nitrogen and cerebrospinal fluid urea nitrogen levels were within normal limits in previously healthy persons who died suddenly from accidental causes. (6) Hospital autopsy cases had high urea nitrogen levels. (7) Postmortem urea nitrogen levels higher than 100 mg.% were indicative of uremia. PMID:14285288

  20. 8. VIEW NORTHEAST, ROUTE 130 NORTH FROM ROUTE 30 WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW NORTHEAST, ROUTE 130 NORTH FROM ROUTE 30 WEST FROM WOODLYNNE AVENUE ISLAND - White Horse Pike Rond Point, Intersection of Crescent Boulevard (U.S. Route 130), White Horse Pike (U.S. Route 30), & Clay Avenue, Collingswood, Camden County, NJ

  1. 1. Intersection of US Route 4 and NH Route 143, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Intersection of US Route 4 and NH Route 143, showing farmhouse on left, barn at right. Looking east. - Batchelder-Edgerly Farmstead, Barn, U.S. Route 4, southwest side, southeast corner of New Hampshire Route 43, Northwood, Rockingham County, NH

  2. Fundamentals of Gas Turbine combustion

    NASA Technical Reports Server (NTRS)

    Gerstein, M.

    1979-01-01

    Combustion problems and research recommendations are discussed in the areas of atomization and vaporization, combustion chemistry, combustion dynamics, and combustion modelling. The recommendations considered of highest priority in these areas are presented.

  3. Combustion oscillation control

    SciTech Connect

    Richards, G.A.; Janus, M.C.

    1996-12-31

    Premixing of fuel and air can avoid high temperatures which produce thermal NOx, but oscillating combustion must be eliminated. Combustion oscillations can also occur in Integrated Gasification Combined Cycle turbines. As an alternative to design or operating modifications, METC is investigating active combustion control (ACC) to eliminate oscillations; ACC uses repeated adjustment of some combustion parameter to control the variation in heat release that drives oscillations.

  4. Mechanisms of droplet combustion

    NASA Technical Reports Server (NTRS)

    Law, C. K.

    1982-01-01

    The fundamental physico-chemical mechanisms governing droplet vaporization and combustion are discussed. Specific topics include governing equations and simplifications, the classical d(2)-Law solution and its subsequent modification, finite-rate kinetics and the flame structure, droplet dynamics, near- and super-critical combustion, combustion of multicomponent fuel blends/emulsions/suspensions, and droplet interaction. Potential research topics are suggested.

  5. Urea production and salvage during pregnancy in normal Jamaican women.

    PubMed

    Forrester, T; Badaloo, A V; Persaud, C; Jackson, A A

    1994-09-01

    The pattern of aggregate nitrogen demand during pregnancy and the fetal and maternal components are unclear. Excess demand enhances efficiency of nitrogen utilization. Urea salvage contributes to enhanced efficiency. Dietary protein intake, urea production, and salvage of urea nitrogen were measured in eight nonpregnant control subjects, and trimesterly in nine pregnant women. Production was measured after prime-intermittent intravenous doses of [15N 15N]-urea by dilution of label in urinary urea. Dietary protein intake was greater in trimester 1 than in nonpregnant women (167 +/- 36 vs 224 +/- 60 mg N.kg-1.d-1), and increased further in trimester 2 (266 +/- 59 mg N.kg-1.d-1). Urea production was not higher during pregnancy. Despite higher protein intake, urea salvage was higher in pregnancy (40 +/- 24 nonpregnant vs 77 +/- 23, 61 +/- 31, and 51 +/- 12 mg N.kg-1.d-1). Therefore, the demand-supply gap for nitrogen was greatest early in pregnancy when fetoplacental growth is slowest, and implies heightened maternal demand. PMID:8074063

  6. Chemical assay of urea for automated sensing in milk.

    PubMed

    Jenkins, D M; Delwiche, M J; Depeters, E J; Bondurant, R H

    1999-09-01

    Results of a new chemical assay for urea involving enzymatic hydrolysis to ammonium and carbonate and subsequent measurement of CO2 partial pressure are presented. The assay is simple to implement in an automated version, and the hardware used is not prone to fouling and damage by raw milk. The assay sensitivity at 24 degrees C is about 0.367 kPa per milligram per deciliter of urea N. The assay has no dependence on milk fat in the sample, and effects of milk proteins and lactose are slight (less than 2% change in sensitivity per change in w/v percent). Observed sensitivities to urea in spiked milk samples were not significantly different from each other or from standards in distilled water or 0.1 M phosphate-buffered saline. The standard error of the assay is about 0.3 mg/dl of urea N (0.1 mM) in standard solution, and about 1 mg/dl of urea N (0.3 mM) in milk in a range of 0 to 30 mg/dl of urea N (0 to 11 mM). The assay holds promise for use in an on-line sensor to measure milk urea N in the milking parlor. PMID:10509259

  7. Collective network routing

    DOEpatents

    Hoenicke, Dirk

    2014-12-02

    Disclosed are a unified method and apparatus to classify, route, and process injected data packets into a network so as to belong to a plurality of logical networks, each implementing a specific flow of data on top of a common physical network. The method allows to locally identify collectives of packets for local processing, such as the computation of the sum, difference, maximum, minimum, or other logical operations among the identified packet collective. Packets are injected together with a class-attribute and an opcode attribute. Network routers, employing the described method, use the packet attributes to look-up the class-specific route information from a local route table, which contains the local incoming and outgoing directions as part of the specifically implemented global data flow of the particular virtual network.

  8. Urea encapsulation in modified starch matrix for nutrients retention

    NASA Astrophysics Data System (ADS)

    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.

  9. Molecular Mechanisms of Urea Transport in Health and Disease

    PubMed Central

    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

  10. A solid phase honey-like channel method for synthesizing urea-ammonium chloride cocrystals on industrial scale

    NASA Astrophysics Data System (ADS)

    Xue, Bingchun; Mao, Meiling; Liu, Yanhong; Guo, Jinyu; Li, Jing; Liu, Erbao

    2016-05-01

    Unanticipated a new and simple urea-ammonium chloride cocrystal synthesis method on industrial scale was found during attempts to produce a kind of granulated compound fertilizer. The aggregation of fertilizer powder can make the interaction among particles from loose to close, which generate mechanical pressure and in turn act as the driving force to benefit cocrystal growth. Additionally, the honeycomb-like channels constructed by other coexisting compound make the water evaporates more moderate, which can help the formation of supersaturated solution at suitable rate, further promote the growth of cocrystal. This approach possibly opens a new route toward the developing methodologies for cocrystal synthesis.

  11. Route based forecasting

    NASA Astrophysics Data System (ADS)

    Zuurendonk, I. W.; Wokke, M. J. J.

    2009-09-01

    Road surface temperatures can differ several degrees on a very short distance due to local effects. In order to get more insight in the local temperature differences and to develop safer gritting routes, Meteogroup has developed a system for route based temperature forecasting. The standard version of the road model is addressed to forecast road surface temperature and condition for a specific location. This model consists of two parts. First a physical part, based on the energy balance equations. The second part of the model performs a statistical correction on the calculated physical road surface temperature. The road model is able to create a forecast for one specific location. From infrared measurements, we know that large local differences in road surface temperature exist on a route. Differences can be up to 5 degrees Celsius over a distance of several hundreds of meters. Based on those measurements, the idea came up to develop a system that forecasts road surface temperature and condition for an entire route: route based forecasting. The route is split up in sections with equal properties. For each section a temperature and condition will be calculated. The main factors that influence the road surface temperature are modelled in this forecasting system: The local weather conditions: temperature, dew point temperature, wind, precipitation, weather type, cloudiness. The sky view: A very sheltered place will receive less radiation during daytime and emit less radiation during nighttime. For a very open spot, the effects are reversed. The solar view: A road section with trees on the southern side, will receive less solar radiation during daytime than a section with tress on the southern side. The route based forecast shows by means of a clear Google Maps presentation which sections will be slippery at what time of the coming night. The final goal of this type of forecast, is to make dynamical gritting possible: a variable salt amount and a different gritting route. This will contribute to safety on the roads (colder spots will be treated earlier) and also it is financially interesting (less salt necessary and fewer kilometers to drive).

  12. 9. BUILDING NO. 424, ORDNANCE FACILITY (COMBUSTIBLE CARTRIDGE CASE FACTORY), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BUILDING NO. 424, ORDNANCE FACILITY (COMBUSTIBLE CARTRIDGE CASE FACTORY), VIEW EAST LOOKING AT NORTHWEST AND SOUTHWEST FACADES. BUILDING NO. 427-A, MAGAZINE, IN LEFT BACKGROUND; BUILDING NO.S 424-E, MIX HOUSE, AND 424-D, MAGAZINE, IN RIGHT BACKGROUND. - Picatinny Arsenal, 400 Area, Gun Bag Loading District, State Route 15 near I-80, Dover, Morris County, NJ

  13. Combustion and core noise

    NASA Astrophysics Data System (ADS)

    Mahan, J. Robert; Karchmer, Allen

    1991-08-01

    Two types of aircraft power plant are considered: the gas turbine and the reciprocating engine. The engine types considered are: the reciprocating engine, the turbojet engine, the turboprop engine, and the turbofan engine. Combustion noise in gas turbine engines is discussed, and reciprocating-engine combustion noise is also briefly described. The following subject areas are covered: configuration variables, operational variables, characteristics of combustion and core noise, sources of combustion noise, combustion noise theory and comparison with experiment, available prediction methods, diagnostic techniques, measurement techniques, data interpretation, and example applications.

  14. Structural Characterization of Apomyoglobin Self-Associated Species in Aqueous Buffer and Urea Solution

    PubMed Central

    Chow, Charles; Kurt, Neşe; Murphy, Regina M.; Cavagnero, Silvia

    2006-01-01

    The biophysical characterization of nonfunctional protein aggregates at physiologically relevant temperatures is much needed to gain deeper insights into the kinetic and thermodynamic relationships between protein folding and misfolding. Dynamic and static laser light scattering have been employed for the detection and detailed characterization of apomyoglobin (apoMb) soluble aggregates populated at room temperature upon dissolving the purified protein in buffer at pH 6.0, both in the presence and absence of high concentrations of urea. Unlike the β-sheet self-associated aggregates previously reported for this protein at high temperatures, the soluble aggregates detected here have either α-helical or random coil secondary structure, depending on solvent and solution conditions. Hydrodynamic diameters range from 80 to 130 nm, with semiflexible chain-like morphology. The combined use of low pH and high urea concentration leads to structural unfolding and complete elimination of the large aggregates. Even upon starting from this virtually monomeric unfolded state, however, protein refolding leads to the formation of severely self-associated species with native-like secondary structure. Under these conditions, kinetic apoMb refolding proceeds via two parallel routes: one leading to native monomer, and the other leading to a misfolded and heavily self-associated state bearing native-like secondary structure. PMID:16214860

  15. Hydrolyzable Polyureas Bearing Hindered Urea Bonds

    PubMed Central

    2015-01-01

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

  16. Hydrolyzable polyureas bearing hindered urea bonds.

    PubMed

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

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

  17. Submarine cable route survey

    SciTech Connect

    Herrouin, G.; Scuiller, T.

    1995-12-31

    The growth of telecommunication market is very significant. From the beginning of the nineties, more and more the use of optical fiber submarine cables is privileged to that of satellites. These submarine telecommunication highways require accurate surveys in order to select the optimum route and determine the cable characteristics. Advanced technology tools used for these surveys are presented along with their implementation.

  18. Influence of Ficoll on urea induced denaturation of fibrinogen

    NASA Astrophysics Data System (ADS)

    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.

  19. Hydrogen production via urea electrolysis using a gel electrolyte

    NASA Astrophysics Data System (ADS)

    King, Rebecca L.; Botte, Gerardine G.

    2011-03-01

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

  20. Refinement of the pressure assay for milk urea nitrogen.

    PubMed

    Jenkins, D M; Delwiche, M J; DePeters, E J; BonDurant, R H

    2000-09-01

    We report improvements in the application of a pressure-based assay for urea. The assay involved the enzymatic hydrolysis of urea and subsequent measurement of CO2 partial pressure. Effects of the preservative bronopol on the assay and their implications for laboratory applications are discussed. A method of remediating these effects with cysteine is described. A method is also described wherein these additives can be used to prepare standards of known urea concentration in milk. The improved assay can be used to measure urea N in unadulterated milk or in bronopol preserved milk with an accuracy of +/-0.7 mg/dl (0.25 mM) in the range from 0 to 30 mg/dl (0 to 10.7 mM). PMID:11003237

  1. Microdetermination of urea in urine using p-dimethylaminobenzaldehyde /PDAB/

    NASA Technical Reports Server (NTRS)

    Geiger, P. J.

    1969-01-01

    Adaptation of the p-dimethylaminobenzaldehyde method for determining urea concentration in urine is an improved micromechanical method. Accuracy and precision are satisfactory. This method avoids extra steps of deproteinizing or removing normal urinary chromogens.

  2. Formation of urea and guanidine by irradiation of ammonium cyanide.

    NASA Technical Reports Server (NTRS)

    Lohrmann, R.

    1972-01-01

    Aqueous solutions of ammonium cyanide yield urea, cyanamide and guanidine when exposed to sunlight or an unfiltered 254 nm ultraviolet source. The prebiotic significance of these results is discussed.

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

    EPA Science Inventory

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

  4. Online measurement of urea concentration in spent dialysate during hemodialysis

    NASA Astrophysics Data System (ADS)

    Olesberg, Jonathon T.; Armitage, Ben; Arnold, Mark A.; Flanigan, Michael

    2002-05-01

    We describe on-line optical measurements of urea concentration during the regular hemodialysis treatment of several patients. The spectral measurements were performed in the effluent dialysate stream after the dialysis membrane using an FTIR spectrometer equipped with a flow-through cell. Spectra were recorded across the 5000-4000 cm-1 (2.0-2.5 micrometers at 1-minute intervals. Optically determined concentrations matched concentrations obtained from standard chemical assays with a root-mean-square error of 0.29 mM for urea (0.8 mg/dl urea nitrogen), 0.03 mM for creatinine, 0.11 mM for lactate, and 0.22 mM for glucose. The observed concentration ranges were 0-11 mM for urea, 0-0.35 mM for creatinine, 0-0.75 mM for lactate, and 9-12.5 mM for glucose.

  5. Exploring the cocrystallization potential of urea and benzamide.

    PubMed

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

    2016-05-01

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

  6. Combustion modeling in internal combustion engines

    NASA Technical Reports Server (NTRS)

    Zeleznik, F. J.

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to be significant in the applications of the model.

  7. Urea Metabolism in Beef Steers Fed Tall Fescue, Orchardgrass, or Gamagrass Hays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two experiments were conducted to assess effects of endophyte treatments (Exp. 1), forage species, and supplementation (Exp. 2) on urea production, excretion, and recycling in beef steers. Infusion of 15,15N-urea and enrichment of urea in urine samples were used to calculate urea N entry and recyc...

  8. Boiler using combustible fluid

    DOEpatents

    Baumgartner, H.; Meier, J.G.

    1974-07-03

    A fluid fuel boiler is described comprising a combustion chamber, a cover on the combustion chamber having an opening for introducing a combustion-supporting gaseous fluid through said openings, means to impart rotation to the gaseous fluid about an axis of the combustion chamber, a burner for introducing a fluid fuel into the chamber mixed with the gaseous fluid for combustion thereof, the cover having a generally frustro-conical configuration diverging from the opening toward the interior of the chamber at an angle of between 15/sup 0/ and 55/sup 0/; means defining said combustion chamber having means defining a plurality of axial hot gas flow paths from a downstream portion of the combustion chamber to flow hot gases into an upstream portion of the combustion chamber, and means for diverting some of the hot gas flow along paths in a direction circumferentially of the combustion chamber, with the latter paths being immersed in the water flow path thereby to improve heat transfer and terminating in a gas outlet, the combustion chamber comprising at least one modular element, joined axially to the frustro-conical cover and coaxial therewith. The modular element comprises an inner ring and means of defining the circumferential, radial, and spiral flow paths of the hot gases.

  9. Laser applications in combustion and combustion diagnostics

    SciTech Connect

    Liou, L.C.

    1993-01-01

    Lasers have become one of the most widely used tools in the scientific community, particularly in the field of combustion. Since the laser is a nonintrusive source of high-intensity energy that can be precisely controlled, it can be used as an ignition source in applications such as solid or liquid rockets, supersonic jet engines, and space-based microgravity experiments. Furthermore, due to the unique characteristics of lasers they are ideally suited for combustion diagnostics. The laser is an invaluable tool for studying the complex physical aspects of the combustion process in systems from boiler furnaces to rocket engines because parameters such as spray patterns, drop sizes, and the interactions between the fuel and oxidizer can readily be determined. This conference was the first of its kind, providing a forum for researchers in this field to exchange information and engage in technical discussions. It also underlined the importance of laser applications in combustion and combustion diagnostics. The papers in this proceedings are organized into three topical sessions: Laser Ignition, which includes theoretical and experimental results, and design considerations for various applications of laser ignition; Combustion Diagnostics, which presents well-established methods such as laser Doppler velocimetry, laser-induced fluorescence, Raman scattering and Raleigh scattering; and Droplet Diagnostics and Scattering, which studies the interaction between electromagnetic waves and droplets, and the hydrodynamics of a droplet. Papers have been processed for inclusion on the data base.

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

    PubMed

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

    2016-07-19

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

  11. NiO nanoparticle-based urea biosensor.

    PubMed

    Tyagi, Manisha; Tomar, Monika; Gupta, Vinay

    2013-03-15

    NiO nanoparticles (NiO-NPs) have been exploited successfully for the fabrication of a urea biosensor. A thin film of NiO nanoparticles deposited on an indium tin oxide (ITO) coated glass substrate serves as an efficient matrix for the immobilisation of urease (Ur), the specific enzyme for urea detection. The prepared bioelectrode (Ur/NiO-NP/ITO/glass) is utilised for urea sensing using cyclic voltammetry and UV-visible spectroscopy. NiO nanoparticles act as electro-catalytic species that are based on the shuttling of electrons between Ni(2+) and Ni(3+) in the octahedral site and result in an enhanced electrochemical current response. The prepared bioelectrode (Ur/NiO-NPs/ITO/glass) exhibits a high sensitivity of 21.3 μA/(mM (*) cm(2)) and a good linearity in a wide range (0.83-16.65 Mm) of urea concentrations with fast response time of 5s. The low value of the Michaelis-Menten constant (K(m)=0.34 mM) indicates the high affinity of Ur towards the analyte (urea). The high catalytic activity, along with the redox behaviour of NiO-NPs, makes it an efficient matrix for the realisation of a urea biosensor. PMID:22947517

  12. Urea and ureolytic activity in lakes of different trophic status.

    PubMed

    Siuda, Waldemar; Chróst, Ryszard J

    2006-01-01

    Urea and uraease (U-ase) activity were determined in water samples taken from the surface layers of 17 lakes of different trophic status. Urea concentrations were inversely correlated with the trophic status of the studied lakes and varied from below the detection limit to 25 micromol l(-1). Maximal potential ureolytic activity (V(max)) ranged from 0.2 to 7.0 micromol l(-1) h(-1). The highest urea concentrations and the lowest U-ase activities were recorded in the spring, whereas the lowest urea concentrations and the highest rates of urea hydrolysis were observed late in summer, during heavy phytoplankton blooms. Since in the majority of the Great Mazurian Lakes microplankton growth was limited by nitrogen supply, urea was an important N source for both auto- and heterotrophic planktonic microorganisms throughout the growth period. U-ase activity was mainly related to the seston. Only up to 25% of total activity could be attributed to free enzymes dissolved in lake water. In epilimnetic water samples the bulk of the ureolytic activity originated from seston-attached bacteria. However, a positive, statistically significant correlation between ureolytic activity and chlorophyll a (Chl(a)) concentrations suggests that phytoplankton may also be responsible for at least a some of the observed ureolytic activity in the highly eutrophic Great Mazurian Lakes. PMID:17338274

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Recycling of polyurethane-urea RIM

    SciTech Connect

    Xiao, H.X.; Kresta, J.E.; Suthar, B.; Li, X.H.

    1997-12-31

    Polyurethane-urea (PUU) RIM are crosslinked materials, which cannot be reprocessed or recycled by using the conventional process. The chemical decrosslinking reaction or transesterification of themosetting polyurethanes by using various inorganic and organic catalysts were investigated. The recycling of waste PUU RIM materials (unpainted, painted and filler reinforced) through decrosslinking (transesterification) using low molecular weight glycols in presence of catalyst was evaluated. It was established that the transestification of PUU RIM can be carried out at the low glycol (EG)/RIM ratio (15/84.5) and that the usual recovery step for the excess glycol (EG) can be avoided resulting in an economical process. The process was scaled up in a 50 gallon reactor at the LymTal International Inc. successfully. It was established that the products from the decrosslinking of PUU RIM are a mixture of the liquid oligomers (LOs) containing urethane, OH and NH{sub 2} groups. These functional groups in LOs exhibit many potential applications as raw materials in the preparation of RIM coatings, adhesives, foams, sealants and composites. PUU RIM made from LOs exhibited promising and interesting results. Both solvent-based and waterborne urethane coatings could be made from LOs. Urethane adhesives made from LOs showed improvement of properties with increasing amounts of LOs. Structural adhesives based on epoxy and LOs were prepared and the effects of equivalent ratios and curing conditions on the adhesive strength of the epoxy/LO adhesives were investigated. Solvent-free coating based on epoxy and LOs was prepared and their properties were determined. Both wood fiber and glass fabric reinforced composites were prepared by using epoxy and LOs and they exhibited interesting properties for different potential applications.

  15. Lump wood combustion process

    NASA Astrophysics Data System (ADS)

    Kubesa, Petr; Horák, Jiří; Branc, Michal; Krpec, Kamil; Hopan, František; Koloničný, Jan; Ochodek, Tadeáš; Drastichová, Vendula; Martiník, Lubomír; Malcho, Milan

    2014-08-01

    The article deals with the combustion process for lump wood in low-power fireplaces (units to dozens of kW). Such a combustion process is cyclical in its nature, and what combustion facility users are most interested in is the frequency, at which fuel needs to be stoked to the fireplace. The paper defines the basic terms such as burnout curve and burning rate curve, which are closely related to the stocking frequency. The fuel burning rate is directly dependent on the immediate thermal power of the fireplace. This is also related to the temperature achieved in the fireplace, magnitude of flue gas losses and the ability to generate conditions favouring the full burnout of the fuel's combustible component, which, at once ensures the minimum production of combustible pollutants. Another part of the paper describes experiments conducted in traditional fireplaces with a grate, at which well-dried lump wood was combusted.

  16. Combustion of Micropowdered Biomass

    NASA Astrophysics Data System (ADS)

    Geil, Ethan; Thorne, Robert

    2009-03-01

    Combustion of finely powdered biomass has the potential to replace heating oil, which accounts for a significant fraction of US oil consumption, in heating, cooling and local power generation applications. When ground to 30-150 micron powders and dispersed in air, wood and other biomass can undergo deflagrating combustion, as occurs with gaseous and dispersed liquid fuels. Combustion is very nearly complete, and in contrast to sugar/starch or cellulose-derived ethanol, nearly all of the available plant mass is converted to usable energy so the economics are much more promising. We are exploring the fundamental combustion science of biomass powders in this size range. In particular, we are examining how powder size, powder composition (including the fraction of volatile organics) and other parameters affect the combustion regime and the combustion products.

  17. Coal combustion products

    USGS Publications Warehouse

    Kalyoncu, R.S.; Olson, D.W.

    2001-01-01

    Coal-burning powerplants, which supply more than half of U.S. electricity, also generate coal combustion products, which can be both a resource and a disposal problem. The U.S. Geological Survey collaborates with the American Coal Ash Association in preparing its annual report on coal combustion products. This Fact Sheet answers questions about present and potential uses of coal combustion products.

  18. Tripropellant combustion process

    NASA Technical Reports Server (NTRS)

    Kmiec, T. D.; Carroll, R. G.

    1988-01-01

    The addition of small amounts of hydrogen to the combustion of LOX/hydrocarbon propellants in large rocket booster engines has the potential to enhance the system stability. Programs being conducted to evaluate the effects of hydrogen on the combustion of LOX/hydrocarbon propellants at supercritical pressures are described. Combustion instability has been a problem during the development of large hydrocarbon fueled rocket engines. At the higher combustion chamber pressures expected for the next generation of booster engines, the effect of unstable combustion could be even more destructive. The tripropellant engine cycle takes advantage of the superior cooling characteristics of hydrogen to cool the combustion chamber and a small amount of the hydrogen coolant can be used in the combustion process to enhance the system stability. Three aspects of work that will be accomplished to evaluate tripropellant combustion are described. The first is laboratory demonstration of the benefits through the evaluation of drop size, ignition delay and burning rate. The second is analytical modeling of the combustion process using the empirical relationship determined in the laboratory. The third is a subscale demonstration in which the system stability will be evaluated. The approach for each aspect is described and the analytical models that will be used are presented.

  19. Combustion Byproducts Recycling Consortium

    SciTech Connect

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    Ashlines: To promote and support the commercially viable and environmentally sound recycling of coal combustion byproducts for productive uses through scientific research, development, and field testing.

  20. Droplet Combustion Experiment

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha

    1998-01-01

    Liquid fuel combustion provides a major portion of the world's energy supply. In most practical combustion devices, liquid burns after being separated into a droplet spray. Essential to the design of efficient combustion systems is a knowledge of droplet combustion behavior. The microgravity environment aboard spacecraft provides an opportunity to investigate the complex interactions between the physical and chemical combustion processes involved in droplet combustion without the complications of natural buoyancy. Launched on STS-83 and STS-94 (April 4 and July 1, 1997), the Droplet Combustion Experiment (DCE) investigated the fundamentals of droplet combustion under a range of pressures (0.25 to 1 atm), oxygen mole fractions (<0.5), and droplet sizes (1.5 to 5 mm). Principal DCE flight hardware features were a chamber to supply selected test environments, the use of crew-inserted bottles, and a vent system to remove unwanted gaseous combustion products. The internal apparatus contained the droplet deployment and ignition mechanisms to burn single, freely deployed droplets in microgravity. Diagnostics systems included a 35-mm high-speed motion picture camera (see the following sequence of photos) with a backlight to photograph burning droplets and a camcorder to monitor experiment operations. Additional diagnostics included an ultraviolet-light-sensitive CCD (charge couple discharge) camera to obtain flame radiation from hydroxyl radicals (see the final figure) and a 35-mm SLR (single-lens-reflex) camera to obtain color still photographs of the flames.

  1. Diesel engine combustion processes

    SciTech Connect

    1995-12-31

    Diesel Engine Combustion Processes guides the engineer and research technician toward engine designs which will give the ``best payoff`` in terms of emissions and fuel economy. Contents include: Three-dimensional modeling of soot and NO in a direct-injection diesel engine; Prechamber for lean burn for low NOx; Modeling and identification of a diesel combustion process with the downhill gradient search method; The droplet group micro-explosions in W/O diesel fuel emulsion sprays; Combustion process of diesel spray in high temperature air; Combustion process of diesel engines at regions with different altitude; and more.

  2. Salvage of blood urea nitrogen in sheep is highly dependent on plasma urea concentration and the efficiency of capture within the diegestive tract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective was to establish the relationships between transfer of blood urea-N to the digestive tract (GIT) and utilisation of recycled urea-N within the GIT, and to determine which of these two mechanisms of the urea recycling process places greater limits on N salvage by growing sheep. Four gro...

  3. Ionic liquid self-combustion synthesis of BiOBr/Bi24O31Br10 heterojunctions with exceptional visible-light photocatalytic performances.

    PubMed

    Li, Fa-tang; Wang, Qing; Ran, Jingrun; Hao, Ying-juan; Wang, Xiao-jing; Zhao, Dishun; Qiao, Shi Zhang

    2015-01-21

    Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L(-1) of RhB and 30 mg L(-1) of MO under visible-light (λ > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed. PMID:25482071

  4. Robustness of airline route networks

    NASA Astrophysics Data System (ADS)

    Lordan, Oriol; Sallan, Jose M.; Escorihuela, Nuria; Gonzalez-Prieto, David

    2016-03-01

    Airlines shape their route network by defining their routes through supply and demand considerations, paying little attention to network performance indicators, such as network robustness. However, the collapse of an airline network can produce high financial costs for the airline and all its geographical area of influence. The aim of this study is to analyze the topology and robustness of the network route of airlines following Low Cost Carriers (LCCs) and Full Service Carriers (FSCs) business models. Results show that FSC hubs are more central than LCC bases in their route network. As a result, LCC route networks are more robust than FSC networks.

  5. Urea-formaldehyde resins and free formaldehyde content.

    PubMed

    Vargha, V

    1998-01-01

    Specifications of wood adhesives must be in correlation with the requirements for the corresponding wood products, for which they will be used. Formaldehyde emission of wood products bonded with urea-formaldehyde resin based adhesives is strictly regulated by standards and there is a compromise is between formaldehyde emission and performance, such as strength, or water resistance. Since values of formaldehyde emission depend on the test method used, in Europe urea-formaldehyde resins for adhesives may generally be classified according to HCHO emission in the particleboard rating of Emission 0 to Emission I class (E-0 to E-1). According to DIN EN 120, particleboard quality E1 emits <6.5 mg/100 g dry article determined with the perforator method. Although a great number of factors effect the formaldehyde emission of the cured products, such as the hardener system, the type of wood etc., the emission of formaldehyde is in strict correlation with the free formaldehyde content of the resin before the curing process. E1 emission class can be achieved, if the free formaldehyde content of the resin is lower than 0.2% by mass. Urea-formaldehyde resins containing. higher than 0.5% free formaldehyde by mass exceed emission class E2, and are not accepted. Since the free formaldehyde content of the urea-formaldehyde resin effects the emission of formaldehyde in the cured product, low formaldehyde content must be ensured during resin synthesis. This can be achieved by properly selecting synthesis conditions as well as raw materials. The quality of raw materials is an essential and determining factor for the synthesis of urea formaldehyde resins. The principal changes which may take place in the formaldehyde solution on storage are the polymerization and precipitation of the polymer, Cannizzaro reaction, methylal formation, oxydation to formic acid, condensation to hydroxyaldehydes and sugars. Any of these reactions are detrimental to product quality. The state of formaldehyde is also an essential factor, since the reaction of poly(methylene glycol)s with urea leads to methylene ether linkages resulting in emission of formaldehyde during storage and later on during the process of curing. Hydrolysis, isomerisation and decomposition of urea may take place simultaneously during improper storage conditions, such as high humidity, high temperatures, industrial atmosphere. The side products formed affect the reaction with formaldehyde during the synthesis resulting in high free formaldehyde content of urea-formaldehyde resins. The relation between synthesis conditions, free formaldehyde content and performance of urea-formaldehyde resins are discussed in detail. PMID:10526993

  6. Southern States' Routing Agency Report

    SciTech Connect

    Not Available

    1988-02-01

    The Southern States' Routing Agency Report is a compendium of 16-southern states' routing programs and authorities for high-level radioactive materials transportation. The report includes the identification of each state's designated routing agency and state legislation and regulations pertaining specifically to the shipment routing of high-level radioactive materials. Using information collected and compiled by the Hazardous Materials Information Group at Oak Ridge National Laboratory, the report also addresses local government routing restrictions for high-level radioactive materials transportation. Whether local or state routing restrictions have been legally challenged and found to be inconsistent and preempted by the federal Hazardous Materials Transportation Act of 1974 (49 App. USC. 1801 et seq.) is noted. Finally, the state agency and contact designated by each state's governor to receive advance notification and shipment routing information under 10 Code of Federal Regulations (CFR) Parts 71 and 73 is listed.

  7. Southern States` Routing Agency Report

    SciTech Connect

    Not Available

    1988-02-01

    The Southern States` Routing Agency Report is a compendium of 16-southern states` routing programs and authorities for high-level radioactive materials transportation. The report includes the identification of each state`s designated routing agency and state legislation and regulations pertaining specifically to the shipment routing of high-level radioactive materials. Using information collected and compiled by the Hazardous Materials Information Group at Oak Ridge National Laboratory, the report also addresses local government routing restrictions for high-level radioactive materials transportation. Whether local or state routing restrictions have been legally challenged and found to be inconsistent and preempted by the federal Hazardous Materials Transportation Act of 1974 (49 App. USC. 1801 et seq.) is noted. Finally, the state agency and contact designated by each state`s governor to receive advance notification and shipment routing information under 10 Code of Federal Regulations (CFR) Parts 71 and 73 is listed.

  8. Combustion Synthesis of Magnesium Aluminate

    SciTech Connect

    Kale, M. A.; Joshi, C. P.; Moharil, S. V.

    2011-10-20

    In the system MgO-Al{sub 2}O{sub 3}, three compounds MgAl{sub 2}O{sub 4}, MgAl{sub 6}O{sub 10}(also expressed as-Mg{sub 0.4}Al{sub 2.4}O{sub 4}) and MgAl{sub 26}O{sub 40} are well known. Importance of the first two is well established. Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel is a technologically important material due to its interesting thermal properties. The MgAl{sub 2}O{sub 4} ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl{sub 2}O{sub 4} is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl{sub 6}O{sub 10} has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl{sub 2}O{sub 4} and MgAl{sub 6}O{sub 10} were formed in a single step, while MgAl{sub 26}O{sub 40} was not formed by this procedure. Activation of MgAl{sub 6}O{sub 10} by rare earth ions like Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+} and ns{sup 2} ion Pb{sup 2+} could be achieved. Excitation bands for MgAl{sub 6}O{sub 10} are at slightly shorter wavelengths compared to those reported for MgAl{sub 2}O{sub 4}.

  9. THE REGULATION OF UREA-BIOSYNTHESIS ENZYMES IN VERTEBRATES.

    PubMed

    MORA, J; MARTUSCELLI, J; ORTIZ PINEDA, J; SOBERON, G

    1965-07-01

    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

  10. Urease immobilized fluorescent gold nanoparticles for urea sensing.

    PubMed

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

    2015-05-01

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

  11. Ammonium assimilation in Proteus vulgaris, Bacillus pasteurii, and Sporosarcina ureae.

    PubMed

    Mrsdorf, G; Kaltwasser, H

    1989-01-01

    No active uptake of ammonium was detected in Proteus vulgaris, Bacillus pasteurii, and Sporosarcina ureae, which indicates that these bacteria depend on the passive diffusion of ammonia across the cell membrane. In P. vulgaris the glutamine synthetase-glutamate synthase (GS-GOGAT) pathway and glutamate dehydrogenase (GDH) were present, and these enzymes exhibited high affinities for ammonium. In B. pasteurii and S. ureae, however, no GS activity was detected, and GOGAT activity was only present in S. ureae. GDH enzymes were present in these two organisms, but showed only low affinity for ammonium, with apparent Km-values of 55.2 mM in B. pasteurii and 36.7 mM in S. ureae, respectively. These observations explain why P. vulgaris is able to grow at neutral pH and low ammonium concentration (2 mM), while B. pasteurii and S. ureae require high ammonium concentration (40 mM) and alkaline pH for growth. PMID:2570557

  12. The regulation of urea-biosynthesis enzymes in vertebrates

    PubMed Central

    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

  13. [Dialysis adequacy: the clinical illogicality of Kt/V urea].

    PubMed

    Basile, Carlo

    2011-01-01

    In the 1980s Gotch and Sargent proposed a mathematical model based on the dialytic removal of urea, introducing the concept of Kt/V urea. The main issue which justifies the fact that Kt/V urea be considered the key of the adequacy of dialysis is that it is related to mortality. However, many studies have highlighted the limits of Kt/V urea: mainly, scaling for the volume of distribution is a confounding factor since gender and body mass index directly affect morbidity and mortality in dialysis patients. On the other hand, several observational studies and preliminary randomized controlled trials have suggested that longer and/or more frequent treatments may lead to better outcomes. In conclusion, an assessment of the amount of dialysis delivered is vital. Kt/V urea, although not perfect, is a useful marker of adequacy. However, the most logical approach in order to diminish the mortality on dialysis must be the individualized prescription of the duration and/or frequency of dialysis treatment, developed through a global assessment of the proven predictors of morbidity and mortality. These parameters include nutrition, albuminemia, mineral metabolism, inflammatory markers, volume control, blood pressure, maintenance of residual renal function, and hemodynamic stability. Each of these variables seems to be associated with the duration and/or frequency of dialysis treatments. Even though several observational studies and preliminary randomized controlled trials seem to confirm these associations, time has come for interventional studies to confirm these complex relationships. PMID:21488028

  14. Blood urea content for evaluating dietary protein quality.

    PubMed

    Bassily, N S; Michael, K G; Said, A K

    1982-01-01

    The protein quality of broad beans was evaluated by using three different methods: the net protein ratio (NPR), the net protein utilization (NPU) and the relative protein value (RPV). Casein was used as a reference protein. The relationship between the values obtained on rats by each method and serum urea concentrations were examined. Serum urea concentration increased by increasing the dietary protein content. It showed a positive correlation of 0.70 and 0.60 for broad beans and casein respectively. NPR values increased by decreasing the level of dietary protein. There was no relationship between the NPR and the serum urea contents in animals fed the casein and broad bean diets. The NPU values indicated that protein utilization was greatest at low dietary protein levels and decreases by increasing the protein content of diet. Serum urea concentration showed an inverse proportion with the NPU values. This was demonstrated by correlations of -0.67 and -0.75 for broad beans and casein respectively. The highest RPV for broad beans was obtained by using the change in body water and the lowest by using the change in body nitrogen as a response parameter. An inverse relationship exists between serum urea concentration and the RPV for broad beans. PMID:7155186

  15. Porous Cross-Linked Polyimide-Urea Networks

    NASA Technical Reports Server (NTRS)

    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.

  16. Fifteenth combustion research conference

    SciTech Connect

    1993-06-01

    The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers.

  17. Coal Combustion Science

    SciTech Connect

    Hardesty, D.R.; Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. )

    1991-08-01

    The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

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

    SciTech Connect

    Levin, Elena J.; Quick, Matthias; Zhou, Ming

    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.

  19. VHDL Control Routing Simulator

    SciTech Connect

    Venard, J.

    1995-07-10

    The control router simulates a backplane consisting of up to 16 slot. Slot 0, reserved for a control module (cr-ctrl), generates the system clocks and provides the serial interface to the Gating Logic. The remaining 15 slots (1-15) contain routing modules (cr mod), each having up to 64 serial inputs and outputs with FIFOs. Messages to be transmitted to the Control Router are taken from text files. There are currently 17 such source files. In the model, the serial output of each source is connected to multiple receivers, so that there are 8 identical messages transmitted to the router for each message file entry.

  20. Thermoluminescent properties of Mn-doped YAP synthesized by the solution combustion method

    NASA Astrophysics Data System (ADS)

    Zhydachevskii, Ya.; Kamińska, I.; Fronc, K.; Reszka, A.; Paszkowicz, W.; Warchol, S.; Berkowski, M.; Elbaum, D.; Suchocki, A.

    2014-11-01

    The work describes results of Mn-doped YAlO3 (YAP) nanocrystalline materials synthesized by the solution combustion method using urea as a fuel. The materials were characterized by X-ray powder diffraction, scanning electron microscopy and luminescence techniques. The combustion synthesis method with codoping with Hf4+ ions allows to obtain highly efficient YAP:Mn2+ phosphor with negligible emission from Mn4+ ions that can be applicable for thermoluminescent dosimetry of ionizing radiation. Namely, the phosphor has a single dominating thermal glow peak at about 200 °C with the green emission near 530 nm related to Mn2+(Y) ions.

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

    PubMed

    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. PMID:25793220

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

    PubMed Central

    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

  3. Japan's microgravity combustion science program

    NASA Technical Reports Server (NTRS)

    Sato, Junichi

    1993-01-01

    Most of energy used by us is generated by combustion of fuels. On the other hand, combustion is responsible for contamination of our living earth. Combustion, also, gives us damage to our life as fire or explosive accidents. Therefore, clean and safe combustion is now eagerly required. Knowledge of the combustion process in combustors is needed to achieve proper designs that have stable operation, high efficiency, and low emission levels. However, current understanding on combustion is far from complete. Especially, there is few useful information on practical liquid and solid particle cloud combustion. Studies on combustion process under microgravity condition will provide many informations for basic questions related to combustors.

  4. New Routing Metrics for ADHOC Network Routing Protocols

    NASA Astrophysics Data System (ADS)

    Reddy, P. C.

    2014-12-01

    The performance and reliability of Internet is measured using different quantities. When the quantities measured are essential and have wide range of acceptance then they are called metrics. Performance metrics enable comparison and selection among the alternatives. In computer networks, metrics are used to evaluate an application, protocol etc. Routing in adhoc networks is nontrivial. Routing protocols for adhoc networks are still evolving and there is need for continuous evaluation of them. In the literature existing, several routing protocols are evaluated using standard metrics under different conditions. This paper proposes new metrics for evaluation of routing protocols and uses them to evaluate the adhoc network routing protocols AODV, DSR, DSDV and TORA. Simulation environment is created using NS-2 simulator. Typical range of speeds, pause times and data rates are used. The results provide new insights in to the working of the routing protocols.

  5. Intelligent route surveillance

    NASA Astrophysics Data System (ADS)

    Schoemaker, Robin; Sandbrink, Rody; van Voorthuijsen, Graeme

    2009-05-01

    Intelligence on abnormal and suspicious behaviour along roads in operational domains is extremely valuable for countering the IED (Improvised Explosive Device) threat. Local sensor networks at strategic spots can gather data for continuous monitoring of daily vehicle activity. Unattended intelligent ground sensor networks use simple sensing nodes, e.g. seismic, magnetic, radar, or acoustic, or combinations of these in one housing. The nodes deliver rudimentary data at any time to be processed with software that filters out the required information. At TNO (Netherlands Organisation for Applied Scientific Research) research has started on how to equip a sensor network with data analysis software to determine whether behaviour is suspicious or not. Furthermore, the nodes should be expendable, if necessary, and be small in size such that they are hard to detect by adversaries. The network should be self-configuring and self-sustaining and should be reliable, efficient, and effective during operational tasks - especially route surveillance - as well as robust in time and space. If data from these networks are combined with data from other remote sensing devices (e.g. UAVs (Unmanned Aerial Vehicles)/aerostats), an even more accurate assessment of the tactical situation is possible. This paper shall focus on the concepts of operation towards a working intelligent route surveillance (IRS) research demonstrator network for monitoring suspicious behaviour in IED sensitive domains.

  6. Fuel mixture approach for solution combustion synthesis of Ca{sub 3}Al{sub 2}O{sub 6} powders

    SciTech Connect

    Ianos, Robert Lazau, Ioan; Pacurariu, Cornelia; Barvinschi, Paul

    2009-07-15

    Single-phase 3CaO.Al{sub 2}O{sub 3} powders were prepared via solution combustion synthesis using a fuel mixture of urea and {beta}-alanine. The concept of using this fuel mixture comes from the individual reactivity of calcium nitrate and aluminum nitrate with respect to urea and {beta}-alanine. It was proved that urea is the optimum fuel for Al(NO{sub 3}){sub 3} whereas {beta}-alanine is the most suitable fuel for Ca(NO{sub 3}){sub 2}. X-ray diffraction and thermal analysis investigations revealed that heating at 300 deg. C the precursor mixture containing the desired metal nitrates, urea and {beta}-alanine triggers a vigorous combustion reaction, which yields single-phase nanocrystalline 3CaO.Al{sub 2}O{sub 3} powder (33.3 nm). In this case additional annealing was no longer required. The use of a single fuel failed to ensure the formation of 3CaO.Al{sub 2}O{sub 3} directly from the combustion reaction. After annealing at 900 deg. C for 1 h, the powders obtained by using a single fuel (urea or {beta}-alanine) developed a phase composition comprising of 3CaO.Al{sub 2}O{sub 3}, 12CaO.7Al{sub 2}O{sub 3} and CaO.

  7. Deactivation of free and stabilized acid phosphatase by urea.

    PubMed

    Gianfreda, L; Marrucci, G; Greco, G

    1986-11-01

    Tests on acid phosphatase (E.G. 3.1.3.2) deactivation by urea have been performed at two pH values. Two conditions have been used: native enzyme operating batch-wise in dilute solution and stabilized enzyme in continuous flow ultrafiltration membrane reactor. Stabilization is achieved by confining the enzyme within a concentrated solution of a linear chain polymer that forms a polarization layer over the membrane. The results provide significant information on the kinetics and thermodynamics of the complex phenomena taking place during deactivation. Deactivation by urea is also compared with thermal deactivation. PMID:18555278

  8. Design and testing of an independently controlled urea SCR retrofit system for the reduction of NOx emissions from marine diesels.

    PubMed

    Johnson, Derek R; Bedick, Clinton R; Clark, Nigel N; McKain, David L

    2009-05-15

    Diesel engine emissions for on-road, stationary and marine applications are regulated in the United States via standards set by the Environmental Protection Agency (EPA). A major component of diesel exhaust that is difficult to reduce is nitrogen oxides (NOx). Selective catalytic reduction (SCR) has been in use for many years for stationary applications, including external combustion boilers, and is promising for NOx abatement as a retrofit for mobile applications where diesel compression ignition engines are used. The research presented in this paper is the first phase of a program focused on the reduction of NOx by use of a stand-alone urea injection system, applicable to marine diesel engines typical of work boats (e.g., tugs). Most current urea SCR systems communicate with engine controls to predict NOx emissions based on signals such as torque and engine speed, however many marine engines in use still employ mechanical injection technology and lack electronic communication abilities. The system developed and discussed in this paper controls NOx emissions independentof engine operating parameters and measures NOx and exhaust flow using the following exhaust sensor inputs: absolute pressure, differential pressure, temperature, and NOx concentration. These sensor inputs were integrated into an independent controller and open loop architecture to estimate the necessary amount of urea needed, and the controller uses pulse width modulation (PWM) to power an automotive fuel injector for airless urea delivery. The system was tested in a transient test cell on a 350 hp engine certified at 4 g/bhp-hr of NOx, with a goal of reducing the engine out NOx levels by 50%. NOx reduction capabilities of 41-67% were shown on the non road transient cycle (NRTC) and ICOMIA E5 steady state cycles with system optimization during testing to minimize the dilute ammonia slip to cycle averages of 5-7 ppm. The goal of 50% reduction of NOx can be achieved dependent upon cycle. Further research with control optimization, urea distribution and possible use of oxidation catalysts is recommended to improve the NOx reduction capabilities while minimizing ammonia slip. PMID:19544914

  9. Asymmetric effect of route-length difference and bottleneck on route choice in two-route traffic system

    NASA Astrophysics Data System (ADS)

    Hino, Yuki; Nagatani, Takashi

    2015-06-01

    We study the traffic behavior in the asymmetric two-route traffic system with real-time information. In the asymmetric two-route system, the length on route A is different from that on route B and there exists a bottleneck on route A. We extend the symmetric two-route dynamic model to the asymmetric case. We investigate the asymmetric effects of the route-length difference and bottleneck on the route choice with real-time information. The travel time on each route depends on the road length, bottleneck, and vehicular density. We derive the dependence of the travel time and mean density on the route-length ratio. We show where, when, and how the congestion occurs by the route choice in the asymmetric two-route system. We clarify the effect of the route-length ratio on the traffic behavior in the route choice.

  10. Combustion in supersonic flow

    SciTech Connect

    Northam, G.B.

    1985-01-01

    A workshop on combustion in supersonic flow was held in conjunction with the 21st JANNAF Combustion Meeting at Laurel, Maryland on October 3 to 4 1984. The objective of the workshop was to establish the level of current understanding of supersonic combustion. The workshop was attended by approximately fifty representatives from government laboratories, engine companies, and universities. Twenty different speakers made presentations in their area of expertise during the first day of the workshop. On the second day, the presentations were discussed, deficiencies in the current understanding defined, and a list of recommended programs generated to address these deficiencies. The agenda for the workshop is given.

  11. N[sub 2]O formation in combustion systems

    SciTech Connect

    Not Available

    1990-03-01

    The objective of this project is to characterize N[sub 2]O emissions from combustion sources emphasizing N[sub 2]O emissions from post-combustion selective gas phase NO[sub x] reduction processes and reburning. The processes to be evaluated include selective noncatalytic NO[sub x] control (ammonia, urea and cyanuric acid injection), and reburning. The project includes pilot-scale testing at two facilities supported by chemical kinetic modeling. Testing is being performed on both a gas-fired plug flow combustor and a pulverized-coal fired combustor. Work performed to date has included the performance of the initial detailed chemical kinetics calculations. These calculations showed that both urea and cyanuric acid produce significant quantities of N[sub 2]O, while NH[sub 3] injection produced negligible amounts, These kinetics data support limited test results reported for cyanuric acid and ammonia injection. Laboratory work to evaluate the selective gas phase NO[sub x] reduction processes listed above has begun. Testing to evaluate reburning at the coal-fired facility is being performed in parallel with the testing at the gas-fired facility. Following completion of the test work, additional kinetics calculations will be performed.

  12. Synthesis of glycerol carbonate from glycerol and urea with gold-based catalysts.

    PubMed

    Hammond, Ceri; Lopez-Sanchez, Jose A; Ab Rahim, Mohd Hasbi; Dimitratos, Nikolaos; Jenkins, Robert L; Carley, Albert F; He, Qian; Kiely, Christopher J; Knight, David W; Hutchings, Graham J

    2011-04-21

    The reaction of glycerol with urea to form glycerol carbonate is mostly reported in the patent literature and to date there have been very few fundamental studies of the reaction mechanism. Furthermore, most previous studies have involved homogeneous catalysts whereas the identification of heterogeneous catalysts for this reaction would be highly beneficial. This is a very attractive reaction that utilises two inexpensive and readily available raw materials in a chemical cycle that overall, results in the chemical fixation of CO(2). This reaction also provides a route to up-grade waste glycerol produced in large quantities during the production of biodiesel. Previous reports are largely based on the utilisation of high concentrations of metal sulfates or oxides, which suffer from low intrinsic activity and selectivity. We have identified heterogeneous catalysts based on gallium, zinc, and gold supported on a range of oxides and the zeolite ZSM-5, which facilitate this reaction. The addition of each component to ZSM-5 leads to an increase in the reaction yield towards glycerol carbonate, but supported gold catalysts display the highest activity. For gold-based catalysts, MgO is the support of choice. Catalysts have been characterised by XRD, TEM, STEM and XPS, and the reaction has been studied with time-on-line analysis of products via a combination of FT-IR spectroscopy, HPLC, (13)C NMR and GC-MS analysis to evaluate the reaction pathway. Our proposed mechanism suggests that glycerol carbonate forms via the cyclization of a 2,3-dihydroxypropyl carbamate and that a subsequent reaction of glycerol carbonate with urea yields the carbamate of glycerol carbonate. Stability and reactivity studies indicate that consecutive reactions of glycerol carbonate can limit the selectivity achieved and reaction conditions can be selected to avoid this. The effect of the catalyst in the proposed mechanism is discussed. PMID:21258674

  13. Biohydrogen production: strategies to improve process efficiency through microbial routes.

    PubMed

    Chandrasekhar, Kuppam; Lee, Yong-Jik; Lee, Dong-Woo

    2015-01-01

    The current fossil fuel-based generation of energy has led to large-scale industrial development. However, the reliance on fossil fuels leads to the significant depletion of natural resources of buried combustible geologic deposits and to negative effects on the global climate with emissions of greenhouse gases. Accordingly, enormous efforts are directed to transition from fossil fuels to nonpolluting and renewable energy sources. One potential alternative is biohydrogen (H2), a clean energy carrier with high-energy yields; upon the combustion of H2, H2O is the only major by-product. In recent decades, the attractive and renewable characteristics of H2 led us to develop a variety of biological routes for the production of H2. Based on the mode of H2 generation, the biological routes for H2 production are categorized into four groups: photobiological fermentation, anaerobic fermentation, enzymatic and microbial electrolysis, and a combination of these processes. Thus, this review primarily focuses on the evaluation of the biological routes for the production of H2. In particular, we assess the efficiency and feasibility of these bioprocesses with respect to the factors that affect operations, and we delineate the limitations. Additionally, alternative options such as bioaugmentation, multiple process integration, and microbial electrolysis to improve process efficiency are discussed to address industrial-level applications. PMID:25874756

  14. Biohydrogen Production: Strategies to Improve Process Efficiency through Microbial Routes

    PubMed Central

    Chandrasekhar, Kuppam; Lee, Yong-Jik; Lee, Dong-Woo

    2015-01-01

    The current fossil fuel-based generation of energy has led to large-scale industrial development. However, the reliance on fossil fuels leads to the significant depletion of natural resources of buried combustible geologic deposits and to negative effects on the global climate with emissions of greenhouse gases. Accordingly, enormous efforts are directed to transition from fossil fuels to nonpolluting and renewable energy sources. One potential alternative is biohydrogen (H2), a clean energy carrier with high-energy yields; upon the combustion of H2, H2O is the only major by-product. In recent decades, the attractive and renewable characteristics of H2 led us to develop a variety of biological routes for the production of H2. Based on the mode of H2 generation, the biological routes for H2 production are categorized into four groups: photobiological fermentation, anaerobic fermentation, enzymatic and microbial electrolysis, and a combination of these processes. Thus, this review primarily focuses on the evaluation of the biological routes for the production of H2. In particular, we assess the efficiency and feasibility of these bioprocesses with respect to the factors that affect operations, and we delineate the limitations. Additionally, alternative options such as bioaugmentation, multiple process integration, and microbial electrolysis to improve process efficiency are discussed to address industrial-level applications. PMID:25874756

  15. VHDL Control Routing Simulator

    Energy Science and Technology Software Center (ESTSC)

    1995-07-10

    The control router simulates a backplane consisting of up to 16 slot. Slot 0, reserved for a control module (cr-ctrl), generates the system clocks and provides the serial interface to the Gating Logic. The remaining 15 slots (1-15) contain routing modules (cr mod), each having up to 64 serial inputs and outputs with FIFOs. Messages to be transmitted to the Control Router are taken from text files. There are currently 17 such source files. Inmore » the model, the serial output of each source is connected to multiple receivers, so that there are 8 identical messages transmitted to the router for each message file entry.« less

  16. Vertex routing models

    NASA Astrophysics Data System (ADS)

    Markovic, D.; Gros, C.

    2009-07-01

    A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, allowing to define a measure for the information centrality of a vertex given by the number of attractors passing through this vertex. We find the number of vertices having a nonzero information centrality to be extensive/subextensive for models with/without a memory trace in the thermodynamic limit. We evaluate the distribution of the number of cycles, of the cycle length and of the maximal basins of attraction, finding a complete scaling collapse in the thermodynamic limit for the latter. Possible implications of our results for the information flow in social networks are discussed.

  17. Dry low combustion system with means for eliminating combustion noise

    DOEpatents

    Verdouw, Albert J.; Smith, Duane; McCormick, Keith; Razdan, Mohan K.

    2004-02-17

    A combustion system including a plurality of axially staged tubular premixers to control emissions and minimize combustion noise. The combustion system includes a radial inflow premixer that delivers the combustion mixture across a contoured dome into the combustion chamber. The axially staged premixers having a twist mixing apparatus to rotate the fluid flow and cause improved mixing without causing flow recirculation that could lead to pre-ignition or flashback.

  18. Transgenic Restoration of Urea Transporter A1 Confers Maximal Urinary Concentration in the Absence of Urea Transporter A3.

    PubMed

    Klein, Janet D; Wang, Yanhua; Mistry, Abinash; LaRocque, Lauren M; Molina, Patrick A; Rogers, Richard T; Blount, Mitsi A; Sands, Jeff M

    2016-05-01

    Urea has a critical role in urinary concentration. Mice lacking the inner medullary collecting duct (IMCD) urea transporter A1 (UT-A1) and urea transporter A3 (UT-A3) have very low levels of urea permeability and are unable to concentrate urine. To investigate the role of UT-A1 in the concentration of urine, we transgenically expressed UT-A1 in knockout mice lacking UT-A1 and UT-A3 using a construct with a UT-A1 gene that cannot be spliced to produce UT-A3. This construct was inserted behind the original UT-A promoter to yield a mouse expressing only UT-A1 (UT-A1(+/+)/UT-A3(-/-)). Western blot analysis demonstrated UT-A1 in the inner medulla of UT-A1(+/+)/UT-A3(-/-) and wild-type mice, but not in UT-A1/UT-A3 knockout mice, and an absence of UT-A3 in UT-A1(+/+)/UT-A3(-/-) and UT-A1/UT-A3 knockout mice. Immunohistochemistry in UT-A1(+/+)/UT-A3(-/-) mice also showed negative UT-A3 staining in kidney and other tissues and positive UT-A1 staining only in the IMCD. Urea permeability in isolated perfused IMCDs showed basal permeability in the UT-A1(+/+)/UT-A3(-/-) mice was similar to levels in wild-type mice, but vasopressin stimulation of urea permeability in wild-type mice was significantly greater (100% increase) than in UT-A1(+/+)/UT-A3(-/-) mice (8% increase). Notably, basal urine osmolalities in both wild-type and UT-A1(+/+)/UT-A3(-/-) mice increased upon overnight water restriction. We conclude that transgenic expression of UT-A1 restores basal urea permeability to the level in wild-type mice but does not restore vasopressin-stimulated levels of urea permeability. This information suggests that transgenic expression of UT-A1 alone in mice lacking UT-A1 and UT-A3 is sufficient to restore urine-concentrating ability. PMID:26407594

  19. Sandia Combustion Research: Technical review

    SciTech Connect

    1995-07-01

    This report contains reports from research programs conducted at the Sandia Combustion Research Facility. Research is presented under the following topics: laser based diagnostics; combustion chemistry; reacting flow; combustion in engines and commercial burners; coal combustion; and industrial processing. Individual projects were processed separately for entry onto the DOE databases.

  20. A solution growth route to nanocrystalline nickel oxide thin films

    NASA Astrophysics Data System (ADS)

    Pejova, Biljana; Kocareva, Tanja; Najdoski, Metodija; Grozdanov, Ivan

    2000-10-01

    A chemical route for preparation of NiO thin films on glass substrates from solution containing nickel(2+) ions and urea is presented. The deposition process is based on the fact that urea decomposes to CO 2 and NH 3 by heating at higher temperature. The as-deposited and post-deposition heat-treated materials were characterized by X-ray analysis and FTIR spectroscopy. The results of some optical and electrical measurements made on these films are discussed. X-ray analysis confirmed that as-deposited film is 3Ni(OH) 2·2H 2O, while the post-deposition heat-treated one is nickel oxide with an average crystal size of 13 nm. According to the optical investigations, the absorption coefficient of the deposited material increases upon annealing, the absorption of the annealed films gradually decrease with an increase of the wavelength in the 390-820 nm region. The optical band gap for the post-deposition heat-treated films is 3.6 eV. While the as-deposited thin films are dielectric, the post-deposition treated ones are characterized by resistivity of several MΩs/cm 2 at room temperature.

  1. Combustion Technology Outreach

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Lewis' High Speed Research (HSR) Propulsion Project Office initiated a targeted outreach effort to market combustion-related technologies developed at Lewis for the next generation of supersonic civil transport vehicles. These combustion-related innovations range from emissions measurement and reduction technologies, to diagnostics, spray technologies, NOx and SOx reduction of burners, noise reduction, sensors, and fuel-injection technologies. The Ohio Aerospace Institute and the Great Lakes Industrial Technology Center joined forces to assist Lewis' HSR Office in this outreach activity. From a database of thousands of nonaerospace firms considered likely to be interested in Lewis' combustion and emission-related technologies, the outreach team selected 41 companies to contact. The selected companies represent oil-gas refineries, vehicle/parts suppliers, and manufacturers of residential furnaces, power turbines, nonautomobile engines, and diesel internal combustion engines.

  2. Studies in premixed combustion

    SciTech Connect

    Sivashinsky, G.I.

    1992-01-01

    This report discusses the following topics on premixed combustion: theory of turbulent flame propagation; pattern formation in premixed flames and related problems; and pattern formation in extended systems. (LSP)

  3. Dynamic effects of combustion

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.

    1982-01-01

    The dynamic effects of combustion are due to the evolution of exothermic energy and its deposition in the compressible medium where the process takes place. The paper examines the dynamics of combustion phenomena, including ignition, turbulent flame propagation (inflammation), explosion, and detonation, with emphasis on their exothermic characteristics. Ignition and explosion are treated as problems of nonlinear mechanics, and their dynamic behavior is described in terms of phase space models and cinematographic laser shear interferograms. The results of a numerical random vortex model of turbulent flame propagation are confirmed in a combustion tunnel experiment, where it was observed that a fresh mixture of burnt and unburnt gases can sustain combustion with a relatively small expenditure of overall mass flow, due to the increasing specific volume of burnt gases inside the flame front. An isentropic pressure wave is found to precede the accelerating flame in the process of detonation, and components of this presssure wave are shown to propagate at local sonic velocities.

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

    PubMed

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

    2016-05-01

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

    J Drugs Dermatol. 2016;15(5):633-639. PMID:27168272

  5. Prebiotic formation of polyamino acids in molten urea

    NASA Astrophysics Data System (ADS)

    Mita, H.; Nomoto, S.; Terasaki, M.; Shimoyama, A.; Yamamoto, Y.

    2005-04-01

    It is important for research into the origins of life to elucidate polyamino acid formation under prebiotic conditions. Only a limited set of amino acids has been reported to polymerize thermally. In this paper we demonstrate a novel thermal polymerization mechanism in a molten urea of alkylamino acids (i.e. glycine, alanine, β-alanine, α-aminobutyric acid, valine, norvaline, leucine and norleucine), which had been thought to be incapable of undergoing thermal polymerization. Also, aspartic acid was found to polymerize in molten urea at a lower temperature than that at which aspartic acid alone had previously been thermally polymerized. Individual oligomers produced in heating experiments on urea-amino acid mixtures were analysed using a liquid chromatograph mass spectrometer. Major products in the reaction mixture were three different types of polyamino acid derivatives: N-carbamoylpolyamino acids, polyamino acids containing a hydantoin ring at the N-terminal position and unidentified derivatives with molecular weights that were greater by 78 than those of the corresponding peptide forms. The polymerization reaction occurred by taking advantage of the high polarity of molten urea as well as its dehydrating ability. Under the presumed prebiotic conditions employed here, many types of amino acids were thus revealed to undergo thermal polymerization.

  6. Reduction in slow intercompartmental clearance of urea during dialysis

    SciTech Connect

    Bowsher, D.J.; Krejcie, T.C.; Avram, M.J.; Chow, M.J.; Del Greco, F.; Atkinson, A.J. Jr.

    1985-04-01

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

  7. Peptidyl-urea based inhibitors of soluble epoxide hydrolases

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. New urea-absorbing polymers for artificial kidney machines

    NASA Technical Reports Server (NTRS)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr.

    1975-01-01

    Etherified polymer is made from modified cellulose derivative which is reacted with periodate. It will absorb 2 grams of urea per 100 grams of polymer. Indications are that polymers could be used to help remove uremic wastes in artificial kidneys, or they could be administered orally as therapy for uremia.

  9. ANTIMICROBIAL ACTIVITIES OF N-CHLORAMINES AND DIAZOLIDINYL UREA

    EPA Science Inventory

    A combination of MICs of an N-chloramine, a simple chlorinated amino acid, and diazolidinyl urea gave synergistic activity against bacteria, but not fungi. The two compounds at a higher concentration, 0.1 and 0.3%, respectively, gave synergistic inhibition of fungi; kill times we...

  10. Hydration free energy difference of acetone, acetamide, and urea

    NASA Astrophysics Data System (ADS)

    Jedlovszky, Pál; Idrissi, Abdenacer

    2008-10-01

    The hydration free energy and hydration entropy difference of urea and acetone, and of acetamide and acetone have been calculated both by free energy perturbation and by the method of thermodynamic integration. The obtained results show a striking asymmetry between the thermodynamic changes accompanying the replacement of the first and second CH3 group of acetone by NH2. Thus, the first CH3/NH2 exchange is found to lead to an about 10kJ /mol decrease in the energy, 8kJ/mol decrease in the Helmholtz free energy, and 5-10J/molK decrease in the entropy of hydration, while similar values accompanying the second CH3/NH2 exchange are found to be about -65kJ /mol, -35kJ/mol and -100J/molK, respectively. These results indicate that the two NH2 groups of the urea molecule have a strong synergetic effect on the thermodynamics of the hydration of urea. The fact that the replacement of the two CH3 groups of acetone by NH2 leads to a strong decrease in the hydration entropy indicates that urea clearly has an ordering effect on nearby water.

  11. Spectrophotometric determination of urea in dermatologic formulations and cosmetics.

    PubMed

    Bojic, Jorgovanka; Radovanovic, Blaga; Dimitrijevic, Jasmina

    2008-06-01

    A rapid, relatively sensitive, and low-cost method for the determination of water-soluble urea content in dermatological therapy products and cosmetics is proposed using a new spectrophotometric assay with water as the only extraction solvent. Spectrophotometric methods involve addition of a known excess of bromate to urea in an acid medium, followed by the determination of residual bromine and chlorine reacting with methyl orange and measurement of absorbance at 505 nm. The absorbance increases linearly with urea concentration (r = 0.9998). The systems obey Beer's law for 6 - 90 microg ml(-1). The calculated apparent molar absorbance values are found to be 4.537 x 10(3) dm(3) mol(-1) cm(-1) and the Sandell's sensitivity is 0.013 microg cm(-2). The variables affecting the rate of the reaction were investigated. The relative standard deviation for five-replication determination of 60 microg ml(-1) urea was 2.1% and the detection limit of the method is 0.34 ng ml(-1). PMID:18544867

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  14. NEW QUATERNARY AMMONIUM ION REAGENTS FROM UREA FOR FABRIC TREATMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, we showed a one step conversion of urea to tertiary amines in water (J. Org. Chem., 2000, 65, 9234-9237). Of these, we used triallylamine to quaternize PEG, PPG, and aryl bromides (Figure 1). One and two-dimensional NMR and chemical ionization mass spectrometries were used to characteriz...

  15. Cleaner co-combustion of lignite-biomass-waste blends by utilising inhibiting compounds of toxic emissions.

    PubMed

    Skodras, G; Palladas, A; Kaldis, S P; Sakellaropoulos, G P

    2007-04-01

    In this paper, the co-combustion behaviour of coal with wastes and biomass and the related toxic gaseous emissions were investigated. The objective of this work is to add on towards a cleaner co-combustion of lignite-waste-biomass blends by utilizing compounds that could inhibit the formation of toxic pollutants. A series of co-combustion tests was performed in a pilot scale incinerator, and the emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured. The co-combustion behaviour of lignite with olive kernels, MDF and sawdust was studied and the ability of additives such as urea, almond shells and municipal sewage sludge to reduce the PCDD/F emissions was examined. All blends were proven good fuels and reproducible combustion conditions were achieved. The addition of inhibitors prior to combustion showed in some cases, relatively high PCDD/F emissions reduction. Among the inhibitors tested, urea seems to achieve a reduction of PCDD/F emissions for all fuel blends, while an unstable behaviour was observed for the others. PMID:17204304

  16. Thermoluminescent dosimetric comparison for two different MgB4O7:Dy production routes

    NASA Astrophysics Data System (ADS)

    Souza, L. F.; Vidal, R. M.; Souza, S. O.; Souza, D. N.

    2014-11-01

    There are several routes employed for the production of synthetic magnesium tetraborate, for example, sol-gel method, combustion, wet reaction synthesis, solid-state route and precipitation (crystal growth). The most commonly used synthesis methods are the wet reaction (precipitation) and solid-state synthesis; both production routes are efficient, but is very difficult to find a direct comparison for them. The present work proposes a direct comparison of both production routes used for magnesium tetraborate synthesis for thermoluminescent (TL) dosimetry. In this work, MgB4O7:Dy was prepared by both methods, wet reaction or precipitation-route 1, and solid-state synthesis -route 2, with the same amount of dopant (0.1%). In the first part of work, the crystalline phases were confirmed by X-ray diffraction (XRD) and it was observed that MgB4O7:Dy can be obtained satisfactorily through both routes, although a very intense crystalline phase of H3BO3 for the powder produced through route 1 was observed. The dose response curve of MgB4O7 pellets (produced for both routes) presents linear behavior when the materials are irradiated with 60Co in the dose range of 10-100 Gy. The results showed that both methods produce MgB4O7:Dy efficiently; however, solid-state synthesis produces MgB4O7:Dy more sensitive to gamma radiation.

  17. Combustion furnace and burner

    SciTech Connect

    McElroy, J. G.

    1985-12-03

    The combustion system includes a hearth lined with refractory, a combustion chamber formed in the refractory, an air manifold mounted on the hearth, a plurality of gas manifold extending through the air manifold and into the combustion chamber, and a diffuser mounted on the manifolds to cause turbulence in the air/gas mixture. The gas manifolds include aspirating means for combining the air and gas. The combustion chamber is elongated and has an elongated neck with a flue gas exit slot over which the work piece passes. The flue gas from the combustion of the air/gas mixture in the combustion chamber increases in velocity as the flue gas passes through the elongated neck and exits the flue gas exit slot. The slot has a length sufficient to permit the work piece to rotate 360/sup 0/ as the work piece rotates and travels through the hearth. This causes the work piece to be uniformly heated over every square inch of its surface.

  18. Coal combustion system

    DOEpatents

    Wilkes, Colin; Mongia, Hukam C.; Tramm, Peter C.

    1988-01-01

    In a coal combustion system suitable for a gas turbine engine, pulverized coal is transported to a rich zone combustor and burned at an equivalence ratio exceeding 1 at a temperature above the slagging temperature of the coal so that combustible hot gas and molten slag issue from the rich zone combustor. A coolant screen of water stretches across a throat of a quench stage and cools the combustible gas and molten slag to below the slagging temperature of the coal so that the slag freezes and shatters into small pellets. The pelletized slag is separated from the combustible gas in a first inertia separator. Residual ash is separated from the combustible gas in a second inertia separator. The combustible gas is mixed with secondary air in a lean zone combustor and burned at an equivalence ratio of less than 1 to produce hot gas motive at temperature above the coal slagging temperature. The motive fluid is cooled in a dilution stage to an acceptable turbine inlet temperature before being transported to the turbine.

  19. Sandia Combustion Research Program

    SciTech Connect

    Johnston, S.C.; Palmer, R.E.; Montana, C.A.

    1988-01-01

    During the late 1970s, in response to a national energy crisis, Sandia proposed to the US Department of Energy (DOE) a new, ambitious program in combustion research. Shortly thereafter, the Combustion Research Facility (CRF) was established at Sandia's Livermore location. Designated a ''user facility,'' the charter of the CRF was to develop and maintain special-purpose resources to support a nationwide initiative-involving US inventories, industry, and national laboratories--to improve our understanding and control of combustion. This report includes descriptions several research projects which have been simulated by working groups and involve the on-site participation of industry scientists. DOE's Industry Technology Fellowship program, supported through the Office of Energy Research, has been instrumental in the success of some of these joint efforts. The remainder of this report presents results of calendar year 1988, separated thematically into eleven categories. Referred journal articles appearing in print during 1988 and selected other publications are included at the end of Section 11. Our traditional'' research activities--combustion chemistry, reacting flows, diagnostics, engine and coal combustion--have been supplemented by a new effort aimed at understanding combustion-related issues in the management of toxic and hazardous materials.

  20. Urea in dry-rolled corn diets: finishing steer performance, nutrient digestion, and microbial protein production.

    PubMed

    Milton, C T; Brandt, R T; Titgemeyer, E C

    1997-05-01

    In Exp. 1, 88 yearling steers (332 kg) were fed dry-rolled corn finishing diets to evaluate effects of dietary urea level on performance and carcass characteristics. Diets contained 0, .5, 1.0, or 1.5% urea (DM basis), which supplied all supplemental N, and 10% chopped prairie hay. Gains (P = .10) and gain efficiency (G/F; P < .05) were increased by .5% urea, with little improvement by additional urea. Regression analysis estimated optimal dietary urea at .9% of DM for ADG and G/F. Fat thickness (P < .05) and yield grade (P < .10) increased linearly with dietary urea level. In Exp. 2, four ruminally and duodenally cannulated steers (557 kg) were fed the diets used in Exp. 1 to evaluate effects of dietary urea on site and extent of digestion. True ruminal OM and starch digestion were increased 25 and 37%, respectively, by .5% urea, but higher urea levels did not differ from .5%. Flows of total N and microbial N to the duodenum were not affected by urea level. In Exp. 3, 100 yearling steers (347 kg) were fed dry-rolled corn finishing diets that contained 10% alfalfa hay as the dietary roughage to evaluate effects of dietary urea level on performance and carcass characteristics. Urea levels were 0, .35, .70, 1.05, or 1.40% urea (DM basis), with no other supplemental N provided. Dry matter intake (P = .10), ADG (P < .05), and G/F (P < .05) increased with intermediate concentrations of urea but decreased with the highest concentration. Regression analysis indicated that the optimal dietary urea level was .5% of DM for ADG and G/F. Urea increased dietary energy utilization but not metabolizable protein supply. PMID:9159292

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

    NASA Technical Reports Server (NTRS)

    Wydeven, T.; Leban, M.

    1973-01-01

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

  2. Beyond conventional routes, an unprecedented metal-free chemoselective synthesis of anthranilate esters via a multicomponent reaction (MCR) strategy.

    PubMed

    Sarkar, Satavisha; Khan, Abu T

    2015-08-14

    A hitherto unreported route for the synthesis of anthranilate esters is demonstrated using 2-nitrobenzaldehyde, malonitrile and an alcohol or amine via a metal and oxidant free multicomponent reaction (MCR) strategy. This process simultaneously installs an ester and urea or urethane functionality via CO and CN bond formations via concurrent oxidation of the aldehyde group and reduction of the nitro group involving an intramolecular redox process. PMID:26159632

  3. Dynamic Message Routing Using Processes

    NASA Astrophysics Data System (ADS)

    Scheibler, Thorsten; Karastoyanova, Dimka; Leymann, Frank

    The Enterprise Service Bus (ESB) is composable middleware that provides applications with services such as message routing and transformation, service composition, dynamic discovery, transactional support, coordination, security features, and others. In an ESB supporting SOAP message exchange, routing algorithms typically follow the sequential SOAP message processing model, where SOAP headers are the main artefacts used to specify the message route and the processing of the payload by intermediaries along that route. This model supports neither alternative nor parallel message routes. In the case of a failing intermediary node this leads to a failure in the message delivery. Moreover, the execution order of services on SOAP message payloads at the intermediaries cannot be prescribed. In this paper, we demonstrate how these deficiencies of the SOAP message processing model can be addressed. We introduce an approach that allows for specifying SOAP message routing logic in terms of BPEL processes. We show that parallel and alternative routes for SOAP messages can be modelled and executed, and the order of services that process a message at intermediaries can be predefined to accommodate the correct processing sequence as required by the concrete application domain. Features like dynamic discovery of services and flexible service composition are leveraged to enable flexible SOAP message routing.

  4. Producing gestures facilitates route learning.

    PubMed

    So, Wing Chee; Ching, Terence Han-Wei; Lim, Phoebe Elizabeth; Cheng, Xiaoqin; Ip, Kit Yee

    2014-01-01

    The present study investigates whether producing gestures would facilitate route learning in a navigation task and whether its facilitation effect is comparable to that of hand movements that leave physical visible traces. In two experiments, we focused on gestures produced without accompanying speech, i.e., co-thought gestures (e.g., an index finger traces the spatial sequence of a route in the air). Adult participants were asked to study routes shown in four diagrams, one at a time. Participants reproduced the routes (verbally in Experiment 1 and non-verbally in Experiment 2) without rehearsal or after rehearsal by mentally simulating the route, by drawing it, or by gesturing (either in the air or on paper). Participants who moved their hands (either in the form of gestures or drawing) recalled better than those who mentally simulated the routes and those who did not rehearse, suggesting that hand movements produced during rehearsal facilitate route learning. Interestingly, participants who gestured the routes in the air or on paper recalled better than those who drew them on paper in both experiments, suggesting that the facilitation effect of co-thought gesture holds for both verbal and nonverbal recall modalities. It is possibly because, co-thought gesture, as a kind of representational action, consolidates spatial sequence better than drawing and thus exerting more powerful influence on spatial representation. PMID:25426624

  5. Fate and surface transport of urea in a coastal plain soil: a rainfall simulation study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface transport of urea has rarely been studied since it is assumed to undergo rapid hydrolysis to ammonia. However, studies have shown urea to exist in estuarine and coastal waters. Urea in small amounts can trigger the diatom Pseudo-nitzschia spp. to produce the toxin domoic acid, which is o...

  6. Use of natural and biobased materials for controlled-release of urea in water: Environmental applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea pearls were encapsulated in cloisite-based matrices using different natural materials (lignin, beeswax and latex) to control the release of urea over time. It was found that all cloisite-based fertilizer tablets showed better release profiles than neat urea tablets. The best release profile was...

  7. EFFECT OF FOLIAR APPLICATION OF UREA WITH NBPT ON THE PHYSIOLOGY AND YIELD OF COTTON

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea is the most recommended foliar N source, due to its relatively low toxicity, quick absorption, and low cost. However, reports of yield improvements with foliar urea application are not consistent. The objectives of this research were to study foliar urea assimilation in cotton and to test the ...

  8. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  9. 40 CFR 721.9920 - Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-.

    Code of Federal Regulations, 2010 CFR

    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,...

  10. Enantioselective Michael Addition/Iminium Ion Cyclization Cascades of Tryptamine-Derived Ureas

    PubMed Central

    2013-01-01

    A Michael addition/iminium ion cyclization cascade of enones with tryptamine-derived ureas under BINOL phosphoric acid (BPA) catalysis is reported. The cascade reaction tolerates a wide variety of easily synthesized tryptamine-derived ureas, including those bearing substituents on the distal nitrogen atom of the urea moiety, affording polyheterocyclic products in good yields and good to excellent enantioselectivities. PMID:23721179

  11. Past Tense Route Priming

    PubMed Central

    Cohen-Shikora, Emily R.; Balota, David A.

    2013-01-01

    The present research examined whether lexical (whole word) or more rule-based (morphological constituent) processes can be locally biased by experimental list context in past tense verb inflection. In Experiment 1, younger and older adults completed a past tense inflection task in which list context was manipulated across blocks containing regular past tense verbs (e.g. REACH-REACHED) or irregular past tense verbs (TEACH-TAUGHT). Critical targets, consisting of half regular and half irregular verbs, were embedded within blocks and participants' inflection response latency and accuracy were assessed. The results yielded a cross-over interaction in response latencies. In the regular context there was a robust regularity effect: regular target verbs were conjugated faster than irregular target verbs. In contrast, in the irregular context, irregular target verbs were conjugated faster than regular target verbs. Experiment 2 used the same targets but in the context of either standard nonwords or nonwords ending in “-ED” to test the possibility of a phonological basis for the effect. The effect of context was eliminated. The results support the notion that distinct processes in past tense verb production can be locally biased by list context and, as shown in Experiment 2, this route priming effect was not due to phonological priming. PMID:23291293

  12. 14 CFR 121.115 - Route width.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Route width. 121.115 Section 121.115..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Areas and Routes for Supplemental Operations § 121.115 Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory...

  13. 14 CFR 121.95 - Route width.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Route width. 121.95 Section 121.95..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route width. (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and...

  14. 14 CFR 121.95 - Route width.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Route width. 121.95 Section 121.95..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route width. (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and...

  15. 14 CFR 121.115 - Route width.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Route width. 121.115 Section 121.115..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Areas and Routes for Supplemental Operations § 121.115 Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory...

  16. 14 CFR 121.115 - Route width.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Route width. 121.115 Section 121.115..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Areas and Routes for Supplemental Operations § 121.115 Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory...

  17. 14 CFR 121.115 - Route width.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Route width. 121.115 Section 121.115..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Areas and Routes for Supplemental Operations § 121.115 Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory...

  18. 14 CFR 121.95 - Route width.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Route width. 121.95 Section 121.95..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route width. (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and...

  19. 14 CFR 121.95 - Route width.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Route width. 121.95 Section 121.95..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route width. (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and...

  20. 14 CFR 121.95 - Route width.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Route width. 121.95 Section 121.95..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Routes: Domestic and Flag Operations § 121.95 Route width. (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and...

  1. 14 CFR 121.115 - Route width.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Route width. 121.115 Section 121.115..., FLAG, AND SUPPLEMENTAL OPERATIONS Approval of Areas and Routes for Supplemental Operations § 121.115 Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory...

  2. Combustion synthesis of YAG:Ce and related phosphors

    NASA Astrophysics Data System (ADS)

    Gupta, K. V. K.; Muley, A.; Yadav, P.; Joshi, C. P.; Moharil, S. V.

    2011-11-01

    YAG:Ce is an important phosphor having applications in various fields ranging from solid state lighting to scintillation detectors. YAG phosphors doped with activators are mainly synthesized by solid state reaction techniques that require high sintering temperatures (above 1500C) to eliminate YAM and YAP phases. Though several soft chemical routes have been explored for synthesis of YAG, most of these methods are complex and phase pure materials are not obtained in one step, but prolonged annealing at temperatures around 1000C or above become necessary. One step combustion synthesis of YAG:Ce3+ and related phosphors carried out at 500C furnace temperature is reported here. Activation with Ce3+ could be achieved during the synthesis without taking recourse to any post-combustion thermal treatment. LEDs prepared from the combustion synthesized YAG:Ce3+, exhibited properties comparable to those produced from the commercial phosphor.

  3. Structure Study of Cellulose Fibers Wet-Spun from Environmentally Friendly NaOH/Urea Aqueous Solutions

    SciTech Connect

    Chen,X.; Burger, C.; Wan, F.; Zhang, J.; Rong, L.; Hsiao, B.; Chu, B.; Cai, J.; Zhang, L.

    2007-01-01

    In this study, structure changes of regenerated cellulose fibers wet-spun from a cotton linter pulp (degree of polymerization {approx}620) solution in an NaOH/urea solvent under different conditions were investigated by simultaneous synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS). WAXD results indicated that the increase in flow rate during spinning produced a better crystal orientation and a higher degree of crystallinity, whereas a 2-fold increase in draw ratio only affected the crystal orientation. When coagulated in a H{sub 2}SO{sub 4}/Na{sub 2}SO{sub 4} aqueous solution at 15 {sup o}C, the regenerated fibers exhibited the highest crystallinity and a crystal orientation comparable to that of commercial rayon fibers by the viscose method. SAXS patterns exhibited a pair of meridional maxima in all regenerated cellulose fibers, indicating the existence of a lamellar structure. A fibrillar superstructure was observed only at higher flow rates (>20 m/min). The conformation of cellulose molecules in NaOH/urea aqueous solution was also investigated by static and dynamic light scattering. It was found that cellulose chains formed aggregates with a radius of gyration, R{sub g}, of about 232 nm and an apparent hydrodynamic radius, R{sub h}, of about 172 nm. The NaOH/urea solvent system is low-cost and environmentally friendly, which may offer an alternative route to replace more hazardous existing methods for the production of regenerated cellulose fibers.

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

    PubMed Central

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

    2014-01-01

    We present the first account of the structurefunction 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

  5. Dynamics of nanoparticle combustion

    NASA Astrophysics Data System (ADS)

    Allen, David James

    A heterogeneous shock tube was used to ignite and measure the combustion behavior of the nano-aluminum suspension behind reflected shock waves. The burning time and particle temperatures were measured using optical diagnostics. In order to use pyrometry measurements for nano-aluminum particles, the emissivity of nano-alumina particles was also measured using the shock tube to heat the particles to known temperatures. The burning time and peak particle temperature results suggested that heat transfer models currently used for burning nanoparticles may significantly overestimate heat losses during combustion. By applying conventional non-continuum heat transfer correlations to burning nano-aluminum particles, the observed peak temperatures, which greatly exceed the ambient temperature, should only be observable if the burning time were very short, of the order of 1 mus, whereas the observed burning time is two orders of magnitude larger. These observations can be reconciled if the energy accommodation coefficient for these conditions is of the order of 0.005, which is the value suggested by Altman, instead of approximately unity, which is the common assumption. A simple model was developed for nano-aluminum particle combustion focusing on a surface controlled reaction as evidenced by experimental data and heat transfer to the surroundings. The simple model supports a low energy accommodation coefficient as suggested by Altman. This result has significant implications on the heat transfer and performance of the nanoparticles in combustion environments. Direct measurement is needed in order to decouple the accommodation coefficient from the assumed combustion mechanism in the simple model. Time-resolved laser induced incandescence measurements were performed to measure the accommodation coefficient of nano-alumina particles in various gaseous environments. The accommodation coefficient was found to be 0.03, 0.07, and 0.15 in helium, nitrogen, and argon respectively at 300 K and 2 atm is each environment. These values represent upper limits for the accommodation coefficient as scaling suggests that the accommodation coefficient will decrease with increasing particle and ambient temperature to values similar to those observed during shock tube measurements. The accommodation coefficient values measured using LII are similar to what has been seen for other metallic nanoparticles and significantly smaller than values used in soot measurements. The results will allow for additional modeling of the accommodation coefficient to be extended to other environments and support previous measurements of high combustion temperatures during nano-aluminum combustion. Further constant volume combustion measurements were used to determine the macroscopic effect of a low energy accommodation coefficient on the heat release to the ambient surrounding in a aerosolized aluminum combusting medium.

  6. High efficiency RCCI combustion

    NASA Astrophysics Data System (ADS)

    Splitter, Derek A.

    An experimental investigation of the pragmatic limits of Reactivity Controlled Compression Ignition (RCCI) engine efficiency was performed. The study utilized engine experiments combined with zero-dimensional modeling. Initially, simulations were used to suggest conditions of high engine efficiency with RCCI. Preliminary simulations suggested that high efficiency could be obtained by using a very dilute charge with a high compression ratio. Moreover, the preliminary simulations further suggested that with simultaneous 50% reductions in heat transfer and incomplete combustion, 60% gross thermal efficiency may be achievable with RCCI. Following the initial simulations, experiments to investigate the combustion process, fuel effects, and methods to reduce heat transfer and incomplete combustion reduction were conducted. The results demonstrated that the engine cycle and combustion process are linked, and if high efficiency is to be had, then the combustion event must be tailored to the initial cycle conditions. It was found that reductions to engine heat transfer are a key enabler to increasing engine efficiency. In addition, it was found that the piston oil jet gallery cooling in RCCI may be unnecessary, as it had a negative impact on efficiency. Without piston oil gallery cooling, it was found that RCCI was nearly adiabatic, achieving 95% of the theoretical maximum cycle efficiency (air standard Otto cycle efficiency).

  7. Microgravity Combustion Diagnostics Workshop

    NASA Technical Reports Server (NTRS)

    Santoro, Gilbert J. (Editor); Greenberg, Paul S. (Editor); Piltch, Nancy D. (Editor)

    1988-01-01

    Through the Microgravity Science and Applications Division (MSAD) of the Office of Space Science and Applications (OSSA) at NASA Headquarters, a program entitled, Advanced Technology Development (ATD) was promulgated with the objective of providing advanced technologies that will enable the development of future microgravity science and applications experimental flight hardware. Among the ATD projects one, Microgravity Combustion Diagnostics (MCD), has the objective of developing advanced diagnostic techniques and technologies to provide nonperturbing measurements of combustion characteristics and parameters that will enhance the scientific integrity and quality of microgravity combustion experiments. As part of the approach to this project, a workshop was held on July 28 and 29, 1987, at the NASA Lewis Research Center. A small group of laser combustion diagnosticians met with a group of microgravity combustion experimenters to discuss the science requirements, the state-of-the-art of laser diagnostic technology, and plan the direction for near-, intermediate-, and long-term programs. This publication describes the proceedings of that workshop.

  8. Environmentally conscious coal combustion

    SciTech Connect

    Hickmott, D.D.; Brown, L.F.; Currier, R.P.

    1997-08-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to evaluate the environmental impacts of home-scale coal combustion on the Navajo Reservation and develop strategies to reduce adverse health effects associated with home-scale coal combustion. Principal accomplishments of this project were: (1) determination of the metal and gaseous emissions of a representative stove on the Navajo Reservation; (2) recognition of cyclic gaseous emissions in combustion in home-scale combustors; (3) `back of the envelope` calculation that home-scale coal combustion may impact Navajo health; and (4) identification that improved coal stoves require the ability to burn diverse feedstocks (coal, wood, biomass). Ultimately the results of Navajo home-scale coal combustion studies will be extended to the Developing World, particularly China, where a significant number (> 150 million) of households continue to heat their homes with low-grade coal.

  9. Advanced Subsonic Combustion Rig

    NASA Technical Reports Server (NTRS)

    Lee, Chi-Ming

    1998-01-01

    Researchers from the NASA Lewis Research Center have obtained the first combustion/emissions data under extreme future engine operating conditions. In Lewis' new world-class 60-atm combustor research facility--the Advanced Subsonic Combustion Rig (ASCR)--a flametube was used to conduct combustion experiments in environments as extreme as 900 psia and 3400 F. The greatest challenge for combustion researchers is the uncertainty of the effects of pressure on the formation of nitrogen oxides (NOx). Consequently, U.S. engine manufacturers are using these data to guide their future combustor designs. The flametube's metal housing has an inside diameter of 12 in. and a length of 10.5 in. The flametube can be used with a variety of different flow paths. Each flow path is lined with a high-temperature, castable refractory material (alumina) to minimize heat loss. Upstream of the flametube is the injector section, which has an inside diameter of 13 in. and a length of 0.5-in. It was designed to provide for quick changeovers. This flametube is being used to provide all U.S. engine manufacturers early assessments of advanced combustion concepts at full power conditions prior to engine production. To date, seven concepts from engine manufacturers have been evaluated and improved. This collaborated development can potentially give U.S. engine manufacturers the competitive advantage of being first in the market with advanced low-emission technologies.

  10. Chelate effects in sulfate binding by amide/urea-based ligands.

    PubMed

    Jia, Chuandong; Wang, Qi-Qiang; Begum, Rowshan Ara; Day, Victor W; Bowman-James, Kristin

    2015-07-01

    The influence of chelate and mini-chelate effects on sulfate binding was explored for six amide-, amide/amine-, urea-, and urea/amine-based ligands. Two of the urea-based hosts were selective for SO4(2-) in water-mixed DMSO-d6 systems. Results indicated that the mini-chelate effect provided by a single urea group with two NH binding sites appears to provide enhanced binding over two amide groups. Furthermore, additional urea binding sites incorporated into the host framework appeared to overcome to some extent competing hydration effects with increasing water content. PMID:25966663

  11. Synthesis and stacked conformations of symmetrical and unsymmetrical oligo-ureas of metaphenylenediamine.

    PubMed

    Clayden, Jonathan; Lemiègre, Loïc; Helliwell, Madeleine

    2007-03-30

    The addition of substituted anilines to nitro-substituted isocyanates followed by reduction generates new aniline-substituted ureas, which can be further extended in a one- or two-directional iterative manner to form oligomeric ureas based on a m-phenylenediamine monomer. Oligo-ureas with up to eight urea linkages are reported. Fully N-substituted oligo-ureas are crystalline, and the X-ray crystal structures display ring-stacked conformations. 1H NMR studies indicate that the stacked conformation persists in solution. PMID:17343415

  12. [Effect of urea on penetration kinetics of vitamin A acid in human skin].

    PubMed

    Wohlrab, W

    1990-09-01

    It is well known that urea can considerably increase the release of drugs from ointment bases and that it is one of the most effective penetration promoters for topically applied drugs. In our present study, therefore, we investigated the influence of urea on the penetration kinetics of vitamin A acid (VAA) into the various layers of human skin. When a vehicle containing urea was applied to the skin, we found increased VAA concentrations depending on the penetration of urea. We discuss the significance of the synergistic properties of VAA and urea in the topical treatment of various skin disease. PMID:2264369

  13. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    NASA Astrophysics Data System (ADS)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17-10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  14. Combustible structural composites and methods of forming combustible structural composites

    SciTech Connect

    Daniels, Michael A.; Heaps, Ronald J.; Steffler, Eric D.; Swank, W. David

    2013-04-02

    Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the combustible structural composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

  15. Combustible structural composites and methods of forming combustible structural composites

    DOEpatents

    Daniels, Michael A.; Heaps, Ronald J.; Steffler, Eric D; Swank, William D.

    2011-08-30

    Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the combustible structural composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

  16. 49 CFR 236.797 - Route, interlocked.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Route, interlocked. 236.797 Section 236.797 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Route, interlocked. A route within interlocking limits....

  17. 49 CFR 236.797 - Route, interlocked.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Route, interlocked. 236.797 Section 236.797 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Route, interlocked. A route within interlocking limits....

  18. 49 CFR 236.797 - Route, interlocked.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Route, interlocked. 236.797 Section 236.797 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Route, interlocked. A route within interlocking limits....

  19. 49 CFR 236.797 - Route, interlocked.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Route, interlocked. 236.797 Section 236.797 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Route, interlocked. A route within interlocking limits....

  20. 49 CFR 236.797 - Route, interlocked.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Route, interlocked. 236.797 Section 236.797 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Route, interlocked. A route within interlocking limits....

  1. Characterization of degeneration process in thermo-acoustic combustion instability using dynamical systems theory

    NASA Astrophysics Data System (ADS)

    Hayashi, Kenta; Gotoda, Hiroshi; Okuno, Yuta; Tachibana, Shigeru; Tokyo University of Science Collaboration; Japan Aerospace Exploration Agency Collaboration

    2015-11-01

    We have experimentally investigated the degeneration process of combustion instability in a lean premixed gas-turbine model combustor on the basis of dynamical systems theory. Our previous study reported that with increasing the equivalence ratio, the dynamical behavior of combustion state close to lean blowout transits from stochastic fluctuations to periodic thermoacoustic combustion oscillations via low-dimensional chaotic oscillations. The further increase in the equivalence ratio gives rise to the quasi-periodic oscillations and the subsequent chaotic oscillations with small amplitudes. The route to chaotic oscillations is quantitatively shown by the use of nonlinear time series analysis involving the color recurrence plots, permutation entropy and local predictor.

  2. Thermodynamics and combustion modeling

    NASA Technical Reports Server (NTRS)

    Zeleznik, Frank J.

    1986-01-01

    Modeling fluid phase phenomena blends the conservation equations of continuum mechanics with the property equations of thermodynamics. The thermodynamic contribution becomes especially important when the phenomena involve chemical reactions as they do in combustion systems. The successful study of combustion processes requires (1) the availability of accurate thermodynamic properties for both the reactants and the products of reaction and (2) the computational capabilities to use the properties. A discussion is given of some aspects of the problem of estimating accurate thermodynamic properties both for reactants and products of reaction. Also, some examples of the use of thermodynamic properties for modeling chemically reacting systems are presented. These examples include one-dimensional flow systems and the internal combustion engine.

  3. Internal combustion engine

    DOEpatents

    Baker, Quentin A.; Mecredy, Henry E.; O'Neal, Glenn B.

    1991-01-01

    An improved engine is provided that more efficiently consumes difficult fuels such as coal slurries or powdered coal. The engine includes a precombustion chamber having a portion thereof formed by an ignition plug. The precombustion chamber is arranged so that when the piston is proximate the head, the precombustion chamber is sealed from the main cylinder or the main combustion chamber and when the piston is remote from the head, the precombustion chamber and main combustion chamber are in communication. The time for burning of fuel in the precombustion chamber can be regulated by the distance required to move the piston from the top dead center position to the position wherein the precombustion chamber and main combustion chamber are in communication.

  4. Droplet Combustion Experiment movie

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Droplet Combustion Experiment (DCE) was designed to investigate the fundamental combustion aspects of single, isolated droplets under different pressures and ambient oxygen concentrations for a range of droplet sizes varying between 2 and 5 mm. The DCE principal investigator was Forman Williams, University of California, San Diego. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1 mission (STS-83, April 4-8 1997; the shortened mission was reflown as MSL-1R on STS-94). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (1.1 MB, 12-second MPEG, screen 320 x 240 pixels; downlinked video, higher quality not available)A still JPG composite of this movie is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300164.html.

  5. Ames Hybrid Combustion Facility

    NASA Technical Reports Server (NTRS)

    Zilliac, Greg; Karabeyoglu, Mustafa A.; Cantwell, Brian; Hunt, Rusty; DeZilwa, Shane; Shoffstall, Mike; Soderman, Paul T.; Bencze, Daniel P. (Technical Monitor)

    2003-01-01

    The report summarizes the design, fabrication, safety features, environmental impact, and operation of the Ames Hybrid-Fuel Combustion Facility (HCF). The facility is used in conducting research into the scalability and combustion processes of advanced paraffin-based hybrid fuels for the purpose of assessing their applicability to practical rocket systems. The facility was designed to deliver gaseous oxygen at rates between 0.5 and 16.0 kg/sec to a combustion chamber operating at pressures ranging from 300 to 900. The required run times were of the order of 10 to 20 sec. The facility proved to be robust and reliable and has been used to generate a database of regression-rate measurements of paraffin at oxygen mass flux levels comparable to those of moderate-sized hybrid rocket motors.

  6. Combustion improver fuel additive

    SciTech Connect

    Kitchen, G.H. III

    1986-04-29

    A fuel additive is described for improving the combustion efficiency and storage stability of stored fuel which is capable of reducing the amount of macroscopic sludge particles formed from polymerization reactions promoted by bacteria and oxidation in fuel and improving the combustion efficiency of the fuel and reducing the soot emissions and scale formation of such fuel in a combustion chamber when used in amounts of from about one part of additive composition to between 3000 to about 10,000 parts by weight of fuel and containing in parts by weight per 100 parts by weight of additive about 50 parts by weight of a polymerizate of ethylene diamine, about 15 parts by weight of a naphtha solvent, about 15 parts by weight of a polyalphaolefin based synthetic oil, about 0.05 parts by weight of a miscible biocide, and about 20 parts by weight of manganese linoleate.

  7. Fluidized-bed combustion

    SciTech Connect

    Botros, P E

    1990-04-01

    This report describes the activities of the Morgantown Energy Technology Center's research and development program in fluidized-bed combustion from October 1, 1987, to September 30, 1989. The Department of Energy program involves atmospheric and pressurized systems. Demonstrations of industrial-scale atmospheric systems are being completed, and smaller boilers are being explored. These systems include vortex, multi-solid, spouted, dual-sided, air-cooled, pulsed, and waste-fired fluidized-beds. Combustion of low-rank coal, components, and erosion are being studied. In pressurized combustion, first-generation, combined-cycle power plants are being tested, and second-generation, advanced-cycle systems are being designed and cost evaluated. Research in coal devolatilization, metal wastage, tube corrosion, and fluidization also supports this area. 52 refs., 24 figs., 3 tabs.

  8. Choline chloride/urea as an effective plasticizer for production of cellulose films.

    PubMed

    Wang, Sha; Peng, Xinwen; Zhong, Linxin; Jing, Shuangshuang; Cao, Xuefei; Lu, Fachuang; Sun, Runcang

    2015-03-01

    Recently, choline chloride/urea (ChCl/urea), a typical deep eutectic solvent (DES), has been found to possess various applications in organic synthesis, electrochemistry, and nanomaterial preparation. Herein we reported the first attempt to plasticize regenerated cellulose film (RCF) using ChCl/urea as an effective plasticizer. Meanwhile, RCFs plasticized with glycerol and sorbitol were also prepared for comparison. The plasticized RCFs were investigated by Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), atomic force microscopy (AFM), and mechanical testing. Transparent and soft RCFs could be successfully prepared in the presence of ChCl/urea, and high elongation at break (34.88%) suggested a significant plasticizing efficiency. No new crystal and phase separation occurred to ChCl/urea plasticized RCFs. The thermal stability of ChCl/urea plasticized RCF was lowered. These results indicated that ChCl/urea was an effective plasticizer for producing cellulose films. PMID:25498618

  9. The use of urea by Evernia prunastri thalli.

    PubMed

    Blanco, M J; Suárez, C; Vicente, C

    1984-10-01

    Thalli of Evernia prunastri floated on 40 mM urea synthesize urease (EC3.5.1.5) which is, in part, retained in the cells as well as secreted into the external medium. By using [(14)C]urea, it has been shown that the (14)CO2 evolved by the action of urease is mainly incorporated into phenolic compounds. Evernic acid has the highest radioactivity when incubations are carried out in the light. The orsellinate moiety of this molecule contains ten times more radioactivity than the everninic acid moiety. This could be explained by the assumption that orsellinic acid is the first product of cyclisation of the polyketide chain in the biosynthetic pathway. PMID:24253163

  10. 49 CFR 356.9 - Elimination of routing restrictions-regular route carriers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 5 2011-10-01 2011-10-01 false Elimination of routing restrictions-regular route... REGULATIONS MOTOR CARRIER ROUTING REGULATIONS § 356.9 Elimination of routing restrictions—regular route carriers. (a) Regular route authorities—construction. All certificates that, either singly or...

  11. 49 CFR 356.9 - Elimination of routing restrictions-regular route carriers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false Elimination of routing restrictions-regular route... REGULATIONS MOTOR CARRIER ROUTING REGULATIONS § 356.9 Elimination of routing restrictions—regular route carriers. (a) Regular route authorities—construction. All certificates that, either singly or...

  12. 49 CFR 356.9 - Elimination of routing restrictions-regular route carriers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 5 2012-10-01 2012-10-01 false Elimination of routing restrictions-regular route... REGULATIONS MOTOR CARRIER ROUTING REGULATIONS § 356.9 Elimination of routing restrictions—regular route carriers. (a) Regular route authorities—construction. All certificates that, either singly or...

  13. 49 CFR 356.9 - Elimination of routing restrictions-regular route carriers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false Elimination of routing restrictions-regular route... REGULATIONS MOTOR CARRIER ROUTING REGULATIONS § 356.9 Elimination of routing restrictions—regular route carriers. (a) Regular route authorities—construction. All certificates that, either singly or...

  14. 49 CFR 356.9 - Elimination of routing restrictions-regular route carriers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Elimination of routing restrictions-regular route... REGULATIONS MOTOR CARRIER ROUTING REGULATIONS § 356.9 Elimination of routing restrictions—regular route carriers. (a) Regular route authorities—construction. All certificates that, either singly or...

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

    NASA Technical Reports Server (NTRS)

    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.

  16. Growth of urea crystals by physical vapor transport

    NASA Technical Reports Server (NTRS)

    Feigelson, R. S.; Route, R. K.; Kao, T.-M.

    1985-01-01

    This work demonstrates that high optical quality crystals of urea can be grown by the physical vapor transport method. The unique features of this method are compared with growth from methanol/water solutions. High growth rates, exceeding 2.5 mm/day, were achieved, and cm-size optical quality single crystals were obtained. Details of the growth technique and the physical properties of the crystals are presented.

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

    PubMed

    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. PMID:18427677

  18. Thermal ignition combustion system

    DOEpatents

    Kamo, Roy; Kakwani, Ramesh M.; Valdmanis, Edgars; Woods, Melvins E.

    1988-01-01

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m.degree. C. and a specific heat greater than 480 J/kg.degree. C. with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber.

  19. Studies in combustion dynamics

    SciTech Connect

    Koszykowski, M.L.

    1993-12-01

    The goal of this program is to develop a fundamental understanding and a quantitative predictive capability in combustion modeling. A large part of the understanding of the chemistry of combustion processes comes from {open_quotes}chemical kinetic modeling.{close_quotes} However, successful modeling is not an isolated activity. It necessarily involves the integration of methods and results from several diverse disciplines and activities including theoretical chemistry, elementary reaction kinetics, fluid mechanics and computational science. Recently the authors have developed and utilized new tools for parallel processing to implement the first numerical model of a turbulent diffusion flame including a {open_quotes}full{close_quotes} chemical mechanism.

  20. Thermal ignition combustion system

    DOEpatents

    Kamo, R.; Kakwani, R.M.; Valdmanis, E.; Woods, M.E.

    1988-04-19

    The thermal ignition combustion system comprises means for providing walls defining an ignition chamber, the walls being made of a material having a thermal conductivity greater than 20 W/m C and a specific heat greater than 480 J/kg C with the ignition chamber being in constant communication with the main combustion chamber, means for maintaining the temperature of the walls above a threshold temperature capable of causing ignition of a fuel, and means for conducting fuel to the ignition chamber. 8 figs.

  1. Combustibility of tetraphenylborate solids

    SciTech Connect

    Walker, D.D.

    1989-05-03

    Liquid slurries expected under normal in-tank processing (ITP) operations are not ignitible because of their high water content. However, deposits of dry solids from the slurries are combustible and produce dense, black smoke when burned. The dry solids burn similarly to Styrofoam and more easily than sawdust. It is the opinion of fire hazard experts that a benzene vapor deflagration could ignite the dry solids. A tetraphenylborate solids fire will rapidly plug the waste tank HEPA ventilation filters due to the nature of the smoke produced. To prevent ignition and combustion of these solids, the waste tanks have been equipped with a nitrogen inerting system.

  2. Computer experiment on aqueous solution. IV. Molecular dynamics calculation on the hydration of urea in an infinitely dilute aqueous solution with a new urea-water pair potential

    NASA Astrophysics Data System (ADS)

    Tanaka, H.; Touhara, Hidekazu; Nakanishi, Koichiro; Watanabe, Nobuatsu

    1984-05-01

    A molecular dynamics calculation on aqueous solution of urea has been carried out using constant temperature technique. The total number of molecules was 216, one of which was urea and the temperature was set to 298.15 K and an experimental value was used for the density. For water-water interaction, the MCY (Matsuoka-Clementi-Yoshimine) potential was used, whereas a new potential function was determined for urea-water interaction from SCF LCAO calculations for more than 800 different dimeric configurations with an STO-3G basis set and subsequent multiparameter fitting of the MO results thus obtained to an appropriate functional form by a nonlinear optimization method. The molecular dynamics calculation has been carried out up to 64 000 time steps and from the final 40 000 time steps, thermodynamic quantities, structural and energetic distribution functions, and time-dependent properties were obtained. The original water structure in the vicinity of urea molecule is slightly changed energetically by incorporation of the urea molecule. However, this energy difference is insignificant for the whole system. Instead of the possibility to form strong hydrogen bonding as estimated from the potential function, it is found that urea molecule could enter into the water structure without any appreciable distortion. This fact was confirmed by the angular dependence of any distribution function around the urea molecule. The hydrophilic region does not show a large energetic stabilization between water molecules and the system is stabilized slightly by including urea-water interaction. In contrast to this, the energy for water molecules in the hydrophobic region (above and below the plane containing urea molecule) becomes lower than that of pure water, although this region is small and water molecules cannot form a strong hydrogen bond with urea. This fact reveals that the role of each functional region, which may be either hydrophobic or hydrophilic, is similar to that of alcohol in aqueous solution, although the whole hydration structure of urea molecule is somewhat different from that of alcohol. Reflecting strong interaction of urea-water, the diffusion coefficient for shell water molecules in the vicinity of urea (within 5 Å from urea molecule) becomes smaller by 10%. Moreover, the hydration structure around urea continues for a long time (16 ps), though the energetic relaxation time is very short.

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

    PubMed

    Yang, Huayiu; Menz, Jochen; Hussermann, 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. PMID:25957355

  4. Transparency of a flame at combustion of forest combustible materials

    NASA Astrophysics Data System (ADS)

    Tsvyk, Ruvim S.

    2003-03-01

    In activity the outcomes of experimental researches of a spectral transparency of a flame are adduced at combustion of wood combustible materials in range 0.6×6 microns at the altitude 0.1m above a surface of combustion. The conditions of a surface forest fires were modeled at absence of a wind.

  5. In Route to Sampling Station

    USGS scientists (from left) Judy Drexler, Brian Bergamaschi, Tamara Kraus, Bryan Downing and Katy O’Donnell in route to a sampling station aboard the USGS R/V Mary Landsteiner. Location: Northern San Francisco Estuary, CA...

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Holešová, Sylva; Valášková, Marta; Hlaváč, Dominik; Madejová, Jana; Samlíková, Magda; Tokarský, Jonáš; Pazdziora, Erich

    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.

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

    PubMed Central

    Das, Gautam; Yoon, Hyon Hee

    2015-01-01

    An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 (μA · cm−2·mM−1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM) with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity) after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. PMID:26346240

  9. Manometric biosensor for on-line measurement of milk urea.

    PubMed

    Jenkins, Daniel M; Delwiche, Michael J

    2002-06-01

    Performance of a prototype sensor for on-line measurement of urea in milk during milking was evaluated. The sensor was based on a manometric assay of the carbon dioxide generated by the enzymatic hydrolysis of urea. Temperature compensation of the sensor was described briefly, and was shown to be effective. The calibration of the sensor was described and resulted in a standard calibration error of about 0.15 mM of urea. The standard error of the sensor in milk was shown to be about 0.25 mM (given a physiological range of about 2-7 mM in cow milk). The sensor was simple, inexpensive, suffered from no interferences in raw milk, and completed a measurement cycle in about 5 min (less than the time to milk a typical cow). A custom made sampling device, whereby milk was passively collected from the milk line under vacuum, was shown to collect an ample volume within 10 s to run a test with the sensor. No measurable bubbles or foam were introduced from the sampling mechanism so that the milk sampled was not diminished in density compared to samples taken by other methods. PMID:11959478

  10. Developing hypothetical inhibition mechanism of novel urea transporter B inhibitor.

    PubMed

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

    2014-01-01

    Urea transporter B (UT-B) is a membrane channel protein that specifically transports urea. UT-B null mouse exhibited urea selective urine concentrating ability deficiency, which suggests the potential clinical applications of the UT-B inhibitors as novel diuretics. Primary high-throughput virtual screening (HTVS) of 50000 small-molecular drug-like compounds identified 2319 hit compounds. These 2319 compounds were screened by high-throughput screening using an erythrocyte osmotic lysis assay. Based on the pharmacological data, putative UT-B binding sites were identified by structure-based drug design and validated by ligand-based and QSAR model. Additionally, UT-B structural and functional characteristics under inhibitors treated and untreated conditions were simulated by molecular dynamics (MD). As the result, we identified four classes of compounds with UT-B inhibitory activity and predicted a human UT-B model, based on which computative binding sites were identified and validated. A novel potential mechanism of UT-B inhibitory activity was discovered by comparing UT-B from different species. Results suggest residue PHE198 in rat and mouse UT-B might block the inhibitor migration pathway. Inhibitory mechanisms of UT-B inhibitors and the functions of key residues in UT-B were proposed. The binding site analysis provides a structural basis for lead identification and optimization of UT-B inhibitors. PMID:25047372

  11. An improved generalized AMBER force field (GAFF) for urea.

    PubMed

    Ozpinar, Gül Altinbaş; Peukert, Wolfgang; Clark, Timothy

    2010-09-01

    We describe an improved force field parameter set for the generalized AMBER force field (GAFF) for urea. Quantum chemical computations were used to obtain geometrical and energetic parameters of urea dimers and larger oligomers using AM1 semiempirical MO theory, density functional theory at the B3LYP/6-31G(d,p) level, MP2 and CCSD ab initio calculations with the 6-311++G(d,p), aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ basis sets, and with the CBS-QB3 and CBS-APNO complete basis set methods. Seven different urea dimer structures were optimized at the MP2/aug-cc-pVDZ level to obtain accurate interaction energies. Atomic partial charges were calculated at the MP2/aug-cc-pVDZ level with the restrained electrostatic potential (RESP) fitting approach. The interaction energies computed with these new RESP charges in the force field are consistent with those obtained from CCSD and MP2 calculations. The linear dimer structure calculated using the force field with modified geometrical parameters and the new RESP charge set agrees well with available experimental data. PMID:20162312

  12. Dichloridobis(thio­urea-κS)nickel(II)

    PubMed Central

    Zouihri, Hafid

    2012-01-01

    The title complex, [NiCl2(CH4N2S)2], has been synthesized from the previously reported (diamino­methyl­idene)sulfonium chloride–thio­urea (3/2) salt [Zouihri (2012b ▶). Acta Cryst. E68, o257]. The NiII ion is coordinated in a distorted tetra­hedral geometry by two mol­ecules of thio­urea [Ni—S = 2.3079 (7) and 2.3177 (6) Å] and two chloride anions [Ni—Cl = 2.2516 (7) and 2.2726 (7) Å]. The bond angles at the Ni atom lie between 96.69 (2) and 115.40 (3)°, while the dihedral angle between the mean planes of the two thio­urea ligands is 6.36 (15)°. The crystal structure is characterized by intra- and inter­molecular N—H⋯Cl hydrogen bonds, which lead to the formation of two-dimensional networks lying parallel to the ab plane. The networks are linked via classical N—H⋯Cl and N—H⋯S hydrogen bonds, forming a three-dimensional arrangement. PMID:22412454

  13. MUNICIPAL WASTEWATER SLUDGE COMBUSTION TECHNOLOGY

    EPA Science Inventory

    The publication describes and evaluates the various municipal sludge combustion systems. It also emphasizes the necessity for considering and evaluating the costs involved in the total sludge management train, including dewatering, combustion, air pollution control, and ash dispo...

  14. Toxicology of Biodiesel Combustion products

    EPA Science Inventory

    1. Introduction The toxicology of combusted biodiesel is an emerging field. Much of the current knowledge about biological responses and health effects stems from studies of exposures to other fuel sources (typically petroleum diesel, gasoline, and wood) incompletely combusted. ...

  15. Combuster. [low nitrogen oxide formation

    NASA Technical Reports Server (NTRS)

    Mckay, R. A. (Inventor)

    1978-01-01

    A combuster is provided for utilizing a combustible mixture containing fuel and air, to heat a load fluid such as water or air, in a manner that minimizes the formation of nitrogen oxide. The combustible mixture passes through a small diameter tube where the mixture is heated to its combustion temperature, while the load fluid flows past the outside of the tube to receive heat. The tube is of a diameter small enough that the combustible mixture cannot form a flame, and yet is not subject to wall quench, so that combustion occurs, but at a temperature less than under free flame conditions. Most of the heat required for heating the combustible mixture to its combustion temperature, is obtained from heat flow through the walls of the pipe to the mixture.

  16. A Combustion Laboratory for Undergraduates.

    ERIC Educational Resources Information Center

    Peters, James E.

    1985-01-01

    Describes a combustion laboratory facility and experiments for a senior-level (undergraduate) course in mechanical engineering. The experiment reinforces basic thermodynamic concepts and provides many students with their first opportunity to work with a combustion system. (DH)

  17. Reduction of NO{sub x} emissions from a dry process preheater kiln with calciner through the use of the urea-based SNCR process

    SciTech Connect

    Steuch, H.E.; Hille, J.T.; Sun, W.H.; Bisnett, M.J.; Kirk, D.W.

    1996-07-01

    The post combustion reduction of NO{sub x} using urea has proven to be an effective method in controlling NO{sub x} from various combustion sources. Such a reduction process has been successfully demonstrated in a week-long test at Ash Grove`s dry process cement kiln system located in Seattle. This system is equipped with planetary coolers, a 5-stage preheater and an air-through-the-kiln calciner. Testing was done under ten different kiln/calciner operating conditions. Using three to four injectors, NO{sub x} was efficiently reduced from 350--600 lb per hour lb/ton of clinker to less than 100 lb per hour. This calculates to a NO{sub x} reduction of greater than 80% for most cases. Chemical utilization was greater than 50%. A high degree of mixing and a long residence time at an appropriate temperature present in the preheater tower contributed to these excellent results. An average ammonia slip was four ppm above a baseline level at a normalized stoichiometric ratio of 1. This demonstration confirms expectations that dry process cement kilns with 4+ preheater stages are an ideal application for the selective noncatalytic reduction of NO{sub x} with urea. NO{sub x} was efficiently and effectively reduced with minimal byproduct emissions and virtually no effect on plant operations.

  18. Fuel-Rich Catalytic Combustion

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Olson, Sandra L.

    1987-01-01

    Two-stage combustion system reduces particulate emissions. Program on catalytic oxidation of iso-octane demonstrates feasibility of two-stage combustion system for reducing particulate emissions. With fuel-rich (fuel/air equivalence ratios of 4.8 to 7.8) catalytic-combustion preburner as first stage, combustion process free of soot at reactor-outlet temperatures of 1,200 K or less.

  19. Expression of urea transporters in potassium-depleted mouse kidney.

    PubMed

    Jung, Ju-Young; Madsen, Kirsten M; Han, Ki-Hwan; Yang, Chul-Woo; Knepper, Mark A; Sands, Jeff M; Kim, Jin

    2003-12-01

    Urea transport in the kidney is mediated by a family of transporter proteins that include the renal urea transporter (UT-A) and the erythrocyte urea transporter (UT-B). The purpose of this study was to determine the location of the urea transporter isoforms in the mouse kidney and to examine the effects of prolonged potassium depletion on the expression and distribution of these transporters by ultrastructural immunocytochemistry. C57BL6 mice were fed a low-potassium diet for 2 wk, and control animals received normal chow. After 2 wk on a low-potassium diet, urinary volume increased and urinary osmolality decreased (833 +/- 30 vs. 1,919 +/- 174 mosmol/kgH2O), as previously demonstrated. Kidneys were processed for immunocytochemistry with antibodies against UT-A1 (L446), UT-A1 and UT-A2 (L194), UT-A3 (Q2), and UT-B. In normal mice, UT-A1 and UT-A3 were expressed mainly in the cytoplasm of the terminal inner medullary collecting duct (IMCD). UT-A2 immunoreactivity was observed mainly on the basolateral membrane of the type 1 epithelium of the descending thin limb (DTL) of short-looped nephrons. The intensity of UT-A1 and UT-A3 immunoreactivity in the IMCD was markedly reduced in potassium-depleted mice. In contrast, there was a significant increase in UT-A2 immunoreactivity in the DTL. The intensity of UT-B immunoreactivity in the descending vasa recta (DVR) was reduced in potassium-depleted animals compared with controls. In control animals, UT-B immunoreactivity was predominantly observed in the plasma membrane, whereas in potassium-depleted mice, it was mainly observed in cytoplasmic granules in endothelial cells of the DVR. In summary, potassium depletion is associated with reduced expression of UT-A1, UT-A3, and UT-B but increased expression of UT-A2. We conclude that reduced expression of urea transporters may play a role in the impaired urine-concentrating ability associated with potassium deprivation. PMID:12952854

  20. Protocol Independent Adaptive Route Update for VANET

    PubMed Central

    Rasheed, Asim; Qayyum, Amir

    2014-01-01

    High relative node velocity and high active node density have presented challenges to existing routing approaches within highly scaled ad hoc wireless networks, such as Vehicular Ad hoc Networks (VANET). Efficient routing requires finding optimum route with minimum delay, updating it on availability of a better one, and repairing it on link breakages. Current routing protocols are generally focused on finding and maintaining an efficient route, with very less emphasis on route update. Adaptive route update usually becomes impractical for dense networks due to large routing overheads. This paper presents an adaptive route update approach which can provide solution for any baseline routing protocol. The proposed adaptation eliminates the classification of reactive and proactive by categorizing them as logical conditions to find and update the route. PMID:24723807

  1. Protocol independent adaptive route update for VANET.

    PubMed

    Rasheed, Asim; Ajmal, Sana; Qayyum, Amir

    2014-01-01

    High relative node velocity and high active node density have presented challenges to existing routing approaches within highly scaled ad hoc wireless networks, such as Vehicular Ad hoc Networks (VANET). Efficient routing requires finding optimum route with minimum delay, updating it on availability of a better one, and repairing it on link breakages. Current routing protocols are generally focused on finding and maintaining an efficient route, with very less emphasis on route update. Adaptive route update usually becomes impractical for dense networks due to large routing overheads. This paper presents an adaptive route update approach which can provide solution for any baseline routing protocol. The proposed adaptation eliminates the classification of reactive and proactive by categorizing them as logical conditions to find and update the route. PMID:24723807

  2. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The various physical processes that occur in the gas turbine combustor and the development of analytical models that accurately describe these processes are discussed. Aspects covered include fuel sprays; fluid mixing; combustion dynamics; radiation and chemistry and numeric techniques which can be applied to highly turbulent, recirculating, reacting flow fields.

  3. Nonlinear Combustion Instability Prediction

    NASA Technical Reports Server (NTRS)

    Flandro, Gary

    2010-01-01

    The liquid rocket engine stability prediction software (LCI) predicts combustion stability of systems using LOX-LH2 propellants. Both longitudinal and transverse mode stability characteristics are calculated. This software has the unique feature of being able to predict system limit amplitude.

  4. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1992-01-01

    This report summarizes research activity on the Spray Combustion Stability Project, characterizes accomplishments and current status, and discusses projected future work. The purpose is to provide a concise conceptual overview of the research effort to date so the reader can quickly assimilate the gist of the research results and place them within the context of their potential impact on liquid rocket engine design technology.

  5. Supersonic-combustion rocket

    NASA Technical Reports Server (NTRS)

    Weber, R. J.; Franciscus, L. C. (Inventor)

    1973-01-01

    A supersonic combustion rocket is provided in which a small rocket motor is substituted for heavy turbo pumps in a conventional rocket engine. The substitution results in a substantial reduction in rocket engine weight. The flame emanating from the small rocket motor can act to ignite non-hypergolic fuels.

  6. Monopropellant combustion system

    NASA Technical Reports Server (NTRS)

    Berg, Gerald R. (Inventor); Mueller, Donn C. (Inventor); Parish, Mark W. (Inventor)

    2005-01-01

    An apparatus and method are provided for decomposition of a propellant. The propellant includes an ionic salt and an additional fuel. Means are provided for decomposing a major portion of the ionic salt. Means are provided for combusting the additional fuel and decomposition products of the ionic salt.

  7. Combustible dust tests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugar dust explosion in Georgia on February 7, 2008 killed 14 workers and injured many others (OSHA, 2009). As a consequence of this explosion, OSHA revised its Combustible Dust National Emphasis (NEP) program. The NEP targets 64 industries with more than 1,000 inspections and has found more tha...

  8. WASTE COMBUSTION SYSTEM ANALYSIS

    EPA Science Inventory

    The report gives results of a study of biomass combustion alternatives. The objective was to evaluate the thermal performance and costs of available and developing biomass systems. The characteristics of available biomass fuels were reviewed, and the performance parameters of alt...

  9. Urea increases tolerance of yeast inorganic pyrophosphatase activity to ethanol: the other side of urea interaction with proteins.

    PubMed

    Lopes, D H; Sola-Penna, M

    2001-10-01

    Ethanol is the major product of yeast sugar fermentation and yet, at certain concentrations, it is very toxic to yeast cells. The major targets for ethanol's toxicity are the plasma membrane and the cytosolic enzymes: ethanol alters membrane organization and permeability and inactivates and unfolds globular cytosolic enzymes. The effects of ethanol on the plasma membrane are attenuated by the presence of trehalose, a disaccharide of glucose that is accumulated simultaneously with urea. The data presented in this paper show that trehalose is not effective at protecting yeast cytosolic inorganic pyrophosphatase against the inactivation of its catalytic activity promoted by alcohols. In contrast, 1 M trehalose increased the toxicity of alcohols against pyrophosphatase by at least 34%. On the other hand, 1.5 M urea attenuated the inactivation of pyrophosphatase promoted by alcohols by approximately 50%. Here we propose that, in the presence of alcohols, urea functions as a molecular filter, enriching the vicinity of the protein with water and excluding alcohol molecules. Conversely, trehalose tends to increase the interaction of alcohols with protein molecules, by withdrawing water, leading to a stronger inactivation promoted for a given concentration of alcohol in the bulk solution on pyrophosphatase activity. PMID:11566028

  10. Advances in urea cycle neuroimaging: Proceedings from the 4th International Symposium on urea cycle disorders, Barcelona, Spain, September 2013.

    PubMed

    Pacheco-Colón, Ileana; Fricke, Stanley; VanMeter, John; Gropman, Andrea L

    2014-01-01

    Our previous imaging research performed as part of a Urea Cycle Rare Disorders Consortium (UCRDC) grant, has identified specific biomarkers of neurologic injury in ornithine transcarbamylase deficiency, OTCD. While characterization of mutations can be achieved in most cases, this information does not necessarily predict the severity of the underlying neurological syndrome. The biochemical consequences of any mutation may be modified additionally by a large number of factors, including contributions of other enzymes and transport systems that mediate flux through the urea cycle, diet and other environmental factors. These factors likely vary from one patient to another, and they give rise to heterogeneity of clinical severity. Affected cognitive domains include non-verbal learning, fine motor processing, reaction time, visual memory, attention, and executive function. Deficits in these capacities may be seen in symptomatic patients, as well as asymptomatic carriers with normal IQ and correlate with variances in brain structure and function in these patients. Using neuroimaging we can identify biomarkers that reflect the downstream impact of UCDs on cognition. This manuscript is a summary of the presentation from the 4th International Consortium on urea cycle disorders held in, Barcelona, Spain, September 2, 2014. PMID:25066103

  11. Advances in Urea cycle Neuroimaging: Proceedings from the 4th International symposium on Urea cycle disorders, Barcelona, Spain, September 2013

    PubMed Central

    Pacheco-Colon, Ileana; Fricke, Stanley; VanMeter, John; Gropman, M.D.

    2014-01-01

    Our previous imaging research performed as part of a Urea Cycle Rare Disorders Consortium (UCRDC) grant, has identified specific biomarkers of neurologic injury in ornithine transcarbamylase deficiency, OTCD. While characterization of mutations can be achieved in most cases, this information does not necessarily predict the severity of the underlying neurological syndrome. The biochemical consequences of any mutation may be modified additionally by a large number of factors, including contributions of other enzymes and transport systems that mediate flux through the urea cycle, diet and other environmental factors. These factors likely vary from one patient to another, and they give rise to heterogeneity of clinical severity. Affected cognitive domains include non-verbal learning, fine motor processing, reaction time, visual memory, attention, and executive function. Deficits in these capacities may be seen in symptomatic patients, as well as asymptomatic carriers with normal IQ and correlate with variances in brain structure and function in these patients. Using neuroimaging we can identify biomarkers that reflect the downstream impact of UCDs on cognition. This manuscript is a summary of the presentation from the 4th International Consortium on Urea cycle disorders held in, Barcelona, Spain, September 2, 2014. PMID:25066103

  12. Proceedings of the Combustion Institute. Volume 30

    SciTech Connect

    2005-01-15

    Papers discussed combustion theory and modelling, turbulent combustion, laser diagnostics and control, chemical kinetics, computational combustion, flames, detonations, droplet combustion, catalysis/materials synthesis, pulse detonations engines, diagnosis, engine combustion, heterogeneous combustion, pollutants (PAH and soot), kinetics, flame diagnosis, propulsion, laminar diffusion flames, lifted turbulent flames, nanoparticles, premixed turbulent flames, solid oxide fuel cells, laminar flames, stationary power systems, and plasma supported flames.

  13. Reversed flow fluidized-bed combustion apparatus

    DOEpatents

    Shang, Jer-Yu; Mei, Joseph S.; Wilson, John S.

    1984-01-01

    The present invention is directed to a fluidized-bed combustion apparatus provided with a U-shaped combustion zone. A cyclone is disposed in the combustion zone for recycling solid particulate material. The combustion zone configuration and the recycling feature provide relatively long residence times and low freeboard heights to maximize combustion of combustible material, reduce nitrogen oxides, and enhance sulfur oxide reduction.

  14. Active urea transport and an unusual basolateral membrane composition in the gills of a marine elasmobranch.

    PubMed

    Fines, G A; Ballantyne, J S; Wright, P A

    2001-01-01

    In elasmobranch fishes, urea occurs at high concentrations (350-600 mM) in the body fluids and tissues, where it plays an important role in osmoregulation. Retention of urea by the gill against this huge blood-to-water diffusion gradient requires specialized adaptations to the epithelial cell membranes. Experiments were performed to determine the mechanisms and structural features that facilitate urea retention by the gill of the spiny dogfish Squalus acanthias. Analysis of urea uptake by gill basolateral membrane vesicles revealed the presence of a phloretin-sensitive (half inhibition 0.09 mM), sodium-coupled, secondary active urea transporter (Michaelis constant = 10.1 mM, maximal velocity = 0.34 micromol. h(-1). mg protein(-1)). We propose that this system actively transports urea out of the gill epithelial cells back into the blood against the urea concentration gradient. Lipid analyses of the basolateral membrane revealed high levels of cholesterol contributing to the highest reported cholesterol-to-phospholipid molar ratio (3.68). This unique combination of active urea transport and modification of the phospholipid bilayer membrane is responsible for decreasing the gill permeability to urea and facilitating urea retention by the gill of Squalus acanthias. PMID:11124129

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

    PubMed

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

    2015-10-15

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

  16. Preferential Solvation in Urea Solutions at Different Concentrations: Properties from Simulation Studies

    SciTech Connect

    Kokubo, Hironori; Pettitt, Bernard M.

    2007-04-21

    We performed molecular dynamics simulations of urea solutions at different concentrations with two urea models (OPLS and KBFF) to examine the structures responsible for the thermodynamic solution properties. Our simulation results showed that hydrogen-bonding properties such as the average number of hydrogen bonds and their lifetime distributions were nearly constant at all concentrations between infinite dilution and the solubility limit. This implies that the characterization of urea-water solutions in the molarity concentration scale as nearly ideal is a result of facile local hydrogen bonding rather than a global property. Thus, urea concentration does not influence the local propensity for hydrogen bonds, only how they are satisfied. By comparison, the KBFF model of urea donated fewer hydrogen bonds than OPLS. We found that the KBFF urea model in TIP3P water better reproduced the experimental density and diffusion constant data. Preferential solvation analysis showed that there were weak urea-urea and water-water associations in OPLS solution at short distances, but there were no strong associations. We divided urea molecules into large, medium, and small clusters to examine fluctuation properties and found that any particular urea molecule did not stay in the same cluster for a long time. We found neither persistent nor large clusters.

  17. Preferential Solvation in Urea Solutions at Different Concentrations: Properties from Simulation Studies.

    SciTech Connect

    Kokubo, Hironori; Pettitt, Bernard M.

    2007-02-15

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We performed molecular dynamics simulations of urea solutions at different concentrations with two urea models (OPLS and KBFF) to examine the structures responsible for the thermodynamic solution properties. Our simulation results showed that hydrogen-bonding properties such as the average number of hydrogen bonds and their lifetime distributions were nearly constant at all concentrations between infinite dilution and the solubility limit. This implies that the characterization of urea-water solutions in the molarity concentration scale as nearly ideal is a result of facile local hydrogen bonding rather than a global property. Thus, urea concentration does not influence the local propensity for hydrogen bonds, only how they are satisfied. By comparison, the KBFF model of urea donated fewer hydrogen bonds than OPLS. We found that the KBFF urea model in TIP3P water better reproduced the experimental density and diffusion constant data. Preferential solvation analysis showed that there were weak urea-urea and water-water associations in OPLS solution at short distances, but there were no strong associations. We divided urea molecules into large, medium, and small clusters to examine fluctuation properties and found that any particular urea molecule did not stay in the same cluster for a long time. We found neither persistent nor large clusters.

  18. Cow level sampling factors affecting analysis and interpretation of milk urea concentrations in 2 dairy herds.

    PubMed Central

    Eicher, R; Bouchard, E; Tremblay, A

    1999-01-01

    The goals of this study were to determine the influence of the variations among udder quarters, the somatic cell count, the time of sampling during the day, sample conservation, and centrifugation on milk urea (UREA) concentrations, and to propose a sample collection procedure for herds that are not on a Dairy Herd Improvement (DHI) program. Forty cows from 2 herds with different feeding practices were randomly selected. The quarter sampled and the somatic cell count did not significantly influence UREA concentrations. Milk urea concentrations were highest in the morning. The diurnal pattern was not influenced by intrinsic factors like parity, days postpartum, or daily milk yield. The UREA concentrations were significantly higher after refrigeration for one week (mean UREA change = +0.41 +/- 0.24 mmol/L, P = 0.0001) and freezing for one month (mean UREA change = +1.52 +/- 1.25 mmol/L, P = 0.0001). Urea concentrations were slightly higher in lactoserum than in whole milk (mean UREA difference = +0.17 +/- 0.24 mmol/L, P = 0.0001). Although this study included only 2 herds and does not allow extrapolation, differences were found in the diurnal pattern of UREA in these 2 herds, which possibly reflect differences in feeding strategy. With consideration of these results, a 6-point sampling procedure for herds that are not on a DHI program is proposed. PMID:10416068

  19. Transport and transformation of de-icing urea from airport runways in a constructed wetland system.

    PubMed

    Thorén, A K; Legrand, C; Herrmann, J

    2003-01-01

    Urea, NH2-CO-NH2, is used as a de-icing agent at Kalmar Airport, southeast Sweden. During 1998-2001, urea contributed on average 30% of the yearly nitrogen (N) transport of 41,000 kg via Törnebybäcken stream to the coastal zone of the Baltic Sea. In order to reduce stream transport of N from airport, agricultural and other diffuse sources, a wetland was constructed in 1996. Annual wetland retention of total-N varied in the range of 2,500-8,100 kg (6-36% of influent) during 1998-2001, according to mass balances calculated from monthly sampling. During airport de-icing, January-March 2001,660 kg urea-N out of 2,600 kg applied urea-N reached the wetland according to daily sampling. This indicated that 75% of the urea was transformed before entering the wetland. Urea was found to be only a minor part (8%) of total-N in the wetland influent. Calculations of cumulative urea-N loads at the wetland inlet and outlet respectively, showed a significant urea transformation during February 2001 with approximately 40% of the incoming urea-N being transformed in the wetland system. These results show that significant amounts of urea can be transformed in a wetland system at air temperatures around 0 degree C. PMID:14621175

  20. Cow level sampling factors affecting analysis and interpretation of milk urea concentrations in 2 dairy herds.

    PubMed

    Eicher, R; Bouchard, E; Tremblay, A

    1999-07-01

    The goals of this study were to determine the influence of the variations among udder quarters, the somatic cell count, the time of sampling during the day, sample conservation, and centrifugation on milk urea (UREA) concentrations, and to propose a sample collection procedure for herds that are not on a Dairy Herd Improvement (DHI) program. Forty cows from 2 herds with different feeding practices were randomly selected. The quarter sampled and the somatic cell count did not significantly influence UREA concentrations. Milk urea concentrations were highest in the morning. The diurnal pattern was not influenced by intrinsic factors like parity, days postpartum, or daily milk yield. The UREA concentrations were significantly higher after refrigeration for one week (mean UREA change = +0.41 +/- 0.24 mmol/L, P = 0.0001) and freezing for one month (mean UREA change = +1.52 +/- 1.25 mmol/L, P = 0.0001). Urea concentrations were slightly higher in lactoserum than in whole milk (mean UREA difference = +0.17 +/- 0.24 mmol/L, P = 0.0001). Although this study included only 2 herds and does not allow extrapolation, differences were found in the diurnal pattern of UREA in these 2 herds, which possibly reflect differences in feeding strategy. With consideration of these results, a 6-point sampling procedure for herds that are not on a DHI program is proposed. PMID:10416068

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

    SciTech Connect

    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.

  2. Low emission internal combustion engine

    DOEpatents

    Karaba, Albert M.

    1979-01-01

    A low emission, internal combustion compression ignition engine having a cylinder, a piston movable in the cylinder and a pre-combustion chamber communicating with the cylinder near the top thereof and in which low emissions of NO.sub.x are achieved by constructing the pre-combustion chamber to have a volume of between 70% and 85% of the combined pre-chamber and main combustion chamber volume when the piston is at top dead center and by variably controlling the initiation of fuel injection into the pre-combustion chamber.

  3. 49 CFR 236.767 - Locking, route.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, route. 236.767 Section 236.767... Locking, route. Electric locking, effective when a train passes a signal displaying an aspect for it to... within the route entered. It may be so arranged that as a train clears a track section of the route,...

  4. 49 CFR 236.767 - Locking, route.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Locking, route. 236.767 Section 236.767... Locking, route. Electric locking, effective when a train passes a signal displaying an aspect for it to... within the route entered. It may be so arranged that as a train clears a track section of the route,...

  5. 49 CFR 236.767 - Locking, route.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Locking, route. 236.767 Section 236.767... Locking, route. Electric locking, effective when a train passes a signal displaying an aspect for it to... within the route entered. It may be so arranged that as a train clears a track section of the route,...

  6. 46 CFR 45.175 - Applicable routes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Applicable routes. 45.175 Section 45.175 Shipping COAST... Barges on Lake Michigan Routes § 45.175 Applicable routes. This subpart applies to the following routes... “Milwaukee route”); (b) Burns Harbor, IN (the “Burns Harbor route”); (c) St. Joseph, MI (the “St....

  7. 46 CFR 45.175 - Applicable routes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Applicable routes. 45.175 Section 45.175 Shipping COAST... Barges on Lake Michigan Routes § 45.175 Applicable routes. This subpart applies to the following routes... “Milwaukee route”); (b) Burns Harbor, IN (the “Burns Harbor route”); (c) St. Joseph, MI (the “St....

  8. 49 CFR 236.767 - Locking, route.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Locking, route. 236.767 Section 236.767... Locking, route. Electric locking, effective when a train passes a signal displaying an aspect for it to... within the route entered. It may be so arranged that as a train clears a track section of the route,...

  9. 46 CFR 45.175 - Applicable routes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Applicable routes. 45.175 Section 45.175 Shipping COAST... Barges on Lake Michigan Routes § 45.175 Applicable routes. This subpart applies to the following routes... “Milwaukee route”); (b) Burns Harbor, IN (the “Burns Harbor route”); (c) St. Joseph, MI (the “St....

  10. 49 CFR 236.767 - Locking, route.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Locking, route. 236.767 Section 236.767... Locking, route. Electric locking, effective when a train passes a signal displaying an aspect for it to... within the route entered. It may be so arranged that as a train clears a track section of the route,...

  11. 46 CFR 45.175 - Applicable routes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Applicable routes. 45.175 Section 45.175 Shipping COAST... Barges on Lake Michigan Routes § 45.175 Applicable routes. This subpart applies to the following routes... “Milwaukee route”); (b) Burns Harbor, IN (the “Burns Harbor route”); (c) St. Joseph, MI (the “St....

  12. 46 CFR 45.175 - Applicable routes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Applicable routes. 45.175 Section 45.175 Shipping COAST... Barges on Lake Michigan Routes § 45.175 Applicable routes. This subpart applies to the following routes on Lake Michigan, between Chicago (Calumet Harbor), IL, and— (a) Milwaukee, WI (the “Milwaukee...

  13. Research avenues in combustion aerodynamics

    SciTech Connect

    Lilley, D.G.

    1994-12-31

    Practical combustion systems incorporate interdependent phenomena of three-dimensional multicomponent flow fields with complex multiphase chemical kinetics, evaporation and heat transfer processes all occurring simultaneously. An overview is presented here of the prospects for improved understanding of combustion processes, with particular emphasis on fluid dynamics and modeling, as applied to practical combustion systems. Extensive measurements should cover a wide range of physical variables, and include mean and time-dependent data and correlations obtained nonintrusively, so as to aid the modeler. Regarding combustion studies, after success with fluid dynamic model laws with a given fuel, extension to a wider range of fuels is required. Applied combustion research needs include the clean and efficient combustion of fossil fuels and future low-grade liquid and solid fuels, and the associated reduction of pollution through combustion control. Fundamental combustion research needs to be done in the areas of interactions between turbulence and kinetics, nonintrusive optical diagnostics, computer model development, gas and solid phase kinetics, droplet/particle cloud combustion, soot formation and chemistry, and flame structure. Both experimental and theoretical combustion engineers need greater understanding of combustion processes.

  14. Central East Pacific Flight Routing

    NASA Technical Reports Server (NTRS)

    Grabbe, Shon; Sridhar, Banavar; Kopardekar, Parimal; Cheng, Nadia

    2006-01-01

    With the introduction of the Federal Aviation Administration s Advanced Technology and Oceanic Procedures system at the Oakland Oceanic Center, a level of automation now exists in the oceanic environment to potentially begin accommodating increased user preferred routing requests. This paper presents the results of an initial feasibility assessment which examines the potential benefits of transitioning from the fixed Central East Pacific routes to user preferred routes. As a surrogate for the actual user-provided routing requests, a minimum-travel-time, wind-optimal dynamic programming algorithm was developed and utilized in this paper. After first describing the characteristics (e.g., origin airport, destination airport, vertical distribution and temporal distribution) of the westbound flights utilizing the Central East Pacific routes on Dec. 14-16 and 19-20, the results of both a flight-plan-based simulation and a wind-optimal-based simulation are presented. Whereas the lateral and longitudinal distribution of the aircraft trajectories in these two simulations varied dramatically, the number of simulated first-loss-of-separation events remained relatively constant. One area of concern that was uncovered in this initial analysis was a potential workload issue associated with the redistribution of traffic in the oceanic sectors due to thc prevailing wind patterns.

  15. Mssbauer and magnetization studies of nickel ferrite nanoparticles synthesized by the microwave-combustion method

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. H.; Elshahawy, A. M.; Makhlouf, Salah A.; Hamdeh, H. H.

    2013-10-01

    Nanocrystalline nickel ferrite was synthesized from its stoichiometric metal nitrates and urea mixtures, using a microwave assisted combustion method. The process was a convenient, inexpensive and an efficient method for formation of NiFe2O4 nanomaterials. Effect of urea/metal nitrates ratio on the obtained phases, particle size and magnetic properties has been investigated by various techniques. Saturation magnetization of 50 emu/g was observed at room temperature for larger particles, and it decreases with decreasing particle size. The coercivity attains a maximum value of 170 Oe when the particle size was ~20 nm, and decreases with increasing particle size. Mssbauer spectra measured at RT for some representative samples show a combination of ordered and superparamagnetic behavior, whereas those collected at 20 K elucidate the nature of the obtained phases and cation distribution.

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

    PubMed

    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. PMID:26094194

  17. [Rate of controlled-release urea pervasion through membrane determined by ultraviolet spectrophotometry].

    PubMed

    Zuo, Xiu-jin; Wang, Zhen-xin; Dai, Xiao-min; Zhou, Yi; Ma, Xiao-jun

    2006-06-01

    Application of controlled-release nitrogenous fertilizers can improve the efficiency of fertilizers and reduce the environmental pollution. Controlled-release urea (coated urea) is one of the controlled-release nitrogenous fertilizers developed quickly in the recent years. The rate of controlled-release urea pervasion through membrane is the most important index of the capacity of controlled release. There is a maximum absorption at lambda=426 nm with complex in acidic solution, using p-dimethylaminozenzaldehyde as color reagent, and the absorbance exhibits a linear reponses to the urea concentration over the range of 7.5-210 microg x mL(-1). The method for determining the rate of controlled-release urea pervasion through membrane was realized through determining the content of urea in the liquor, the recovery efficiency of the method is 96.1%-103.9%. PMID:16961255

  18. Dynamic urea bond for the design of reversible and self-healing polymers

    PubMed Central

    Ying, Hanze; Zhang, Yanfeng; Cheng, Jianjun

    2014-01-01

    Polymers bearing dynamic covalent bonds may exhibit dynamic properties, such as self-healing, shape memory and environmental adaptation. However, most dynamic covalent chemistries developed so far require either catalyst or change of environmental conditions to facilitate bond reversion and dynamic property change in bulk materials. Here we report the rational design of hindered urea bonds (urea with bulky substituent attached to its nitrogen) and the use of them to make polyureas and poly(urethane-ureas) capable of catalyst-free dynamic property change and autonomous repairing at low temperature. Given the simplicity of the hindered urea bond chemistry (reaction of a bulky amine with an isocyanate), incorporation of the catalyst-free dynamic covalent urea bonds to conventional polyurea or urea-containing polymers that typically have stable bulk properties may further broaden the scope of applications of these widely used materials. PMID:24492620

  19. Route Flap Damping Made Usable

    NASA Astrophysics Data System (ADS)

    Pelsser, Cristel; Maennel, Olaf; Mohapatra, Pradosh; Bush, Randy; Patel, Keyur

    The Border Gateway Protocol (BGP), the de facto inter-domain routing protocol of the Internet, is known to be noisy. The protocol has two main mechanisms to ameliorate this, MinRouteAdvertisementInterval (MRAI), and Route Flap Damping (RFD). MRAI deals with very short bursts on the order of a few to 30 seconds. RFD deals with longer bursts, minutes to hours. Unfortunately, RFD was found to severely penalize sites for being well-connected because topological richness amplifies the number of update messages exchanged. So most operators have disabled it. Through measurement, this paper explores the avenue of absolutely minimal change to code, and shows that a few RFD algorithmic constants and limits can be trivially modified, with the result being damping a non-trivial amount of long term churn without penalizing well-behaved prefixes' normal convergence process.

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

    PubMed

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

    2015-12-01

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

  1. Combustion engine system

    NASA Technical Reports Server (NTRS)

    Houseman, John (Inventor); Voecks, Gerald E. (Inventor)

    1986-01-01

    A flow through catalytic reactor which selectively catalytically decomposes methanol into a soot free hydrogen rich product gas utilizing engine exhaust at temperatures of 200 to 650 C to provide the heat for vaporizing and decomposing the methanol is described. The reactor is combined with either a spark ignited or compression ignited internal combustion engine or a gas turbine to provide a combustion engine system. The system may be fueled entirely by the hydrogen rich gas produced in the methanol decomposition reactor or the system may be operated on mixed fuels for transient power gain and for cold start of the engine system. The reactor includes a decomposition zone formed by a plurality of elongated cylinders which contain a body of vapor permeable, methanol decomposition catalyst preferably a shift catalyst such as copper-zinc.

  2. Internal combustion engines

    SciTech Connect

    Frankl, G.

    1980-02-05

    An engine system includes a compression ignition engine, a turbo -supercharger for supplying air under pressure to the engine, an intercooler disposed between the outlet of the compressor of the turbo-charger and the engine, an air heater the output of which is connected to the engine and a valve operable to cause the air from the compressor to be delivered through the intercooler or through the air heater to the engine. In addition the valve can be opened a small amount when it is required to initiate combustion in the air heater so that only a small flow of air takes place through the heater. When the combustion has started the valve is moved to the position in which all the air from the compressor of the turbo-charger flows to the engine through the air heater.

  3. Dynamic features of combustion

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.

    1985-01-01

    The dynamic features of combustion are discussed for four important cases: ignition, inflammation, explosion, and detonation. Ignition, the initiation of a self-sustained exothermic process, is considered in the simplest case of a closed thermodynamic system and its stochastic distribution. Inflammation, the initiation and propagation of self-sustained flames, is presented for turbulent flow. Explosion, the dynamic effects caused by the deposition of exothermic energy in a compressible medium, is illustrated by self-similar blast waves with energy deposition at the front and the adiabatic non-self-similar wave. Detonation, the most comprehensive illustration of all the dynamic effects of combustion, is discussed with a phenomenological account of the development and structure of the wave.

  4. Fluidized bed combustion

    SciTech Connect

    Sowards, N.K.; Murphy, M.L.

    1992-04-07

    This patent describes a method of incinerating a fuel containing difficult to remove tramp comprising wire. It comprises placing of a fluid bed within a downwardly and inwardly tapered centrally hollow air distributor disposed within a lower portion of a vessel; introducing fuel comprising combustible material and tramp comprising wire into the fluid bed; incinerating the combustible material in the fluid bed accommodating downward migration within the fluid bed of the wire without a central obstruction to such migration; in the course of performing the incinerating step, fluidizing the bed solely by introducing inwardly at several tiered locations directed air into the bed only around the tapered periphery along the lower portion of the vessel from a plurality of inwardly and downwardly parallel sites as causing the bed material and tramp to migrate downwardly and inwardly without central bed obstruction toward a discharge site.

  5. N,N′-Diphenyl­thio­urea acetone monosolvate

    PubMed Central

    Okuniewski, Andrzej; Chojnacki, Jaroslaw; Becker, Barbara

    2011-01-01

    In the title compound, C13H12N2S·C3H6O, the phenyl rings of the thio­urea mol­ecule are in syn and anti positions in relation to the C=S bond. Two mol­ecules are connected by N—H⋯S=C hydrogen bonds into a centrosymmetric dimer. An additional N—H⋯O=C hydrogen bond to the acetone solvent mol­ecule and some weak C—H⋯π inter­actions reinforce the crystal structure. PMID:21522765

  6. C-13 NMR identification of urea-formaldehyde resins

    SciTech Connect

    Meyer, B.; Nunlist, R.

    1980-10-01

    The work shows that adhesive and foam resins differ significantly in qualitative and quantitative composition, and that the differences in the C-13 NMR spectra can be readily recognized, even by an untrained person. The fingerprints of resins are so characteristic that NMR operators who are not familiar with urea-formaldehyde resin chemistry, can rapidly learn how to distinguish between particleboard or plywood adhesives and foam resins, as well as between different manufacturers and individual batches. Thus, the NMR method lends itself extremely well to quality control.

  7. Expression of urea transporters in the developing rat kidney.

    PubMed

    Kim, Young-Hee; Kim, Dong-Un; Han, Ki-Hwan; Jung, Ju-Young; Sands, Jeff M; Knepper, Mark A; Madsen, Kirsten M; Kim, Jin

    2002-03-01

    Urea transport in the kidney is mediated by a family of transporter proteins that includes renal urea transporters (UT-A) and erythrocyte urea transporters (UT-B). Because newborn rats are not capable of producing concentrated urine, we examined the time of expression and the distribution of UT-A and UT-B in the developing rat kidney by light and electron microscopic immunocytochemistry. Kidneys from 16-, 18-, and 20-day-old fetuses, 1-, 4-, 7-, 14-, and 21-day-old pups, and adult animals were studied. In the adult kidney, UT-A was expressed intensely in the inner medullary collecting duct (IMCD) and terminal portion of the short-loop descending thin limb (DTL) and weakly in long-loop DTL in the outer part of the inner medulla. UT-A immunoreactivity was not present in the fetal kidney but was observed in the IMCD and DTL in 1-day-old pups. The intensity of UT-A immunostaining in the IMCD gradually increased during postnatal development. In 4- and 7-day-old pups, UT-A immunoreactivity was present in the DTL at the border between the outer and inner medulla. In 14- and 21-day-old pups, strong UT-A immunostaining was observed in the terminal part of short-loop DTL in the outer medulla, and weak labeling remained in long-loop DTL descending into the outer part of the inner medulla. In the adult kidney, there was intense staining for UT-B in descending vasa recta (DVR) and weak labeling of glomeruli. In the developing kidney, UT-B was first observed in the DVR of a 20-day-old fetus. After birth there was a striking increase in the number of UT-B-positive DVR, in association with the formation of vascular bundles. The intensity of immunostaining remained strong in the outer medulla but gradually decreased in the inner medulla. We conclude that the expression of urea transporters in short-loop DTL and DVR coincides with the development of the ability to produce a concentrated urine. PMID:11832436

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

    PubMed

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

    2014-08-28

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

  9. A current perspective on the compensatory effects of urea and methylamine on protein stability and function.

    PubMed

    Rahman, Safikur; Warepam, Marina; Singh, Laishram R; Dar, Tanveer Ali

    2015-11-01

    Urea is a strong denaturant and inhibits many enzymes but is accumulated intracellularly at very high concentrations (up to 3-4 M) in mammalian kidney and in many marine fishes. It is known that the harmful effects of urea on the macromolecular structure and function is offset by the accumulation of an osmolytic agent called methylamine. Intracellular concentration of urea to methylamines falls in the ratio of 2:1 to 3:2 (molar ratio). At this ratio, the thermodynamic effects of urea and methylamines on protein stability and function are believed to be algebraically additive. The mechanism of urea-methylamine counteraction has been widely investigated on various approaches including, thermodynamic, structural and functional aspects. Recent advances have also revealed atomic level insights of counteraction and various molecular dynamic simulation studies have yielded significant molecular level informations on the interaction between urea and methylamines with proteins. It is worthwhile that urea-methylamine system not only plays pivotal role for the survival and functioning of the renal medullary cells but also is a key osmoregulatory component of the marine elasmobranchs, holocephalans and coelacanths. Therefore, it is important to combine all discoveries and discuss the developments in context to physiology of the mammalian kidney and adaptation of the marine organisms. In this article we have for the first time reviewed all major developments on urea-counteraction systems to date. We have also discussed about other additional urea-counteraction systems discovered so far including urea-NaCl, urea-myoinsoitol and urea-molecular chaperone systems. Insights for the possible future research have also been highlighted. PMID:26095775

  10. The Biginelli Reaction Is a Urea-Catalyzed Organocatalytic Multicomponent Reaction.

    PubMed

    Puripat, Maneeporn; Ramozzi, Romain; Hatanaka, Miho; Parasuk, Waraporn; Parasuk, Vudhichai; Morokuma, Keiji

    2015-07-17

    The recently developed artificial force induced reaction (AFIR) method was applied to search systematically all possible multicomponent pathways for the Biginelli reaction mechanism. The most favorable pathway starts with the condensation of the urea and benzaldehyde, followed by the addition of ethyl acetoacetate. Remarkably, a second urea molecule catalyzes nearly every step of the reaction. Thus, the Biginelli reaction is a urea-catalyzed multicomponent reaction. The reaction mechanism was found to be identical in both protic and aprotic solvents. PMID:26066623

  11. Routing Algorithm Exploits Spatial Relations

    NASA Technical Reports Server (NTRS)

    Okino, Clayton; Jennings, Esther

    2004-01-01

    A recently developed routing algorithm for broadcasting in an ad hoc wireless communication network takes account of, and exploits, the spatial relationships among the locations of nodes, in addition to transmission power levels and distances between the nodes. In contrast, most prior algorithms for discovering routes through ad hoc networks rely heavily on transmission power levels and utilize limited graph-topology techniques that do not involve consideration of the aforesaid spatial relationships. The present algorithm extracts the relevant spatial-relationship information by use of a construct denoted the relative-neighborhood graph (RNG).

  12. Spontaneous combustion of hydrogen

    NASA Technical Reports Server (NTRS)

    Nusselt, Wilhelm; Pothmann, PH

    1923-01-01

    It is shown by the author's experiments that hydrogen which escapes to the atmosphere through openings in the system may burn spontaneously if it contains dust. Purely thermal reasoning can not account for the combustion. It seems to be rather an electrical ignition. In order to determine whether the cause of the spontaneous ignition was thermo-chemical, thermo-mechanical, or thermo-electrical, the experiments in this paper were performed.

  13. Combustion powered linear actuator

    DOEpatents

    Fischer, Gary J.

    2007-09-04

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  14. Thiomonas sp. CB2 is able to degrade urea and promote toxic metal precipitation in acid mine drainage waters supplemented with urea.

    PubMed

    Farasin, Julien; Andres, Jérémy; Casiot, Corinne; Barbe, Valérie; Faerber, Jacques; Halter, David; Heintz, Dimitri; Koechler, Sandrine; Lièvremont, Didier; Lugan, Raphael; Marchal, Marie; Plewniak, Frédéric; Seby, Fabienne; Bertin, Philippe N; Arsène-Ploetze, Florence

    2015-01-01

    The acid mine drainage (AMD) in Carnoulès (France) is characterized by the presence of toxic metals such as arsenic. Several bacterial strains belonging to the Thiomonas genus, which were isolated from this AMD, are able to withstand these conditions. Their genomes carry several genomic islands (GEIs), which are known to be potentially advantageous in some particular ecological niches. This study focused on the role of the "urea island" present in the Thiomonas CB2 strain, which carry the genes involved in urea degradation processes. First, genomic comparisons showed that the genome of Thiomonas sp. CB2, which is able to degrade urea, contains a urea genomic island which is incomplete in the genome of other strains showing no urease activity. The urease activity of Thiomonas sp. CB2 enabled this bacterium to maintain a neutral pH in cell cultures in vitro and prevented the occurrence of cell death during the growth of the bacterium in a chemically defined medium. In AMD water supplemented with urea, the degradation of urea promotes iron, aluminum and arsenic precipitation. Our data show that ureC was expressed in situ, which suggests that the ability to degrade urea may be expressed in some Thiomonas strains in AMD, and that this urease activity may contribute to their survival in contaminated environments. PMID:26441922

  15. Thiomonas sp. CB2 is able to degrade urea and promote toxic metal precipitation in acid mine drainage waters supplemented with urea

    PubMed Central

    Farasin, Julien; Andres, Jérémy; Casiot, Corinne; Barbe, Valérie; Faerber, Jacques; Halter, David; Heintz, Dimitri; Koechler, Sandrine; Lièvremont, Didier; Lugan, Raphael; Marchal, Marie; Plewniak, Frédéric; Seby, Fabienne; Bertin, Philippe N.; Arsène-Ploetze, Florence

    2015-01-01

    The acid mine drainage (AMD) in Carnoulès (France) is characterized by the presence of toxic metals such as arsenic. Several bacterial strains belonging to the Thiomonas genus, which were isolated from this AMD, are able to withstand these conditions. Their genomes carry several genomic islands (GEIs), which are known to be potentially advantageous in some particular ecological niches. This study focused on the role of the “urea island” present in the Thiomonas CB2 strain, which carry the genes involved in urea degradation processes. First, genomic comparisons showed that the genome of Thiomonas sp. CB2, which is able to degrade urea, contains a urea genomic island which is incomplete in the genome of other strains showing no urease activity. The urease activity of Thiomonas sp. CB2 enabled this bacterium to maintain a neutral pH in cell cultures in vitro and prevented the occurrence of cell death during the growth of the bacterium in a chemically defined medium. In AMD water supplemented with urea, the degradation of urea promotes iron, aluminum and arsenic precipitation. Our data show that ureC was expressed in situ, which suggests that the ability to degrade urea may be expressed in some Thiomonas strains in AMD, and that this urease activity may contribute to their survival in contaminated environments. PMID:26441922

  16. Strobes: an oscillatory combustion.

    PubMed

    Corbel, Justine M L; Lingen, Joost N J; Zevenbergen, John F; Gijzeman, Onno L J; Meijerink, Andries

    2012-04-26

    Strobe compositions belong to the class of solid combustions. They are mixtures of powdered ingredients. When ignited, the combustion front evolves in an oscillatory fashion, and flashes of light are produced by intermittence. They have fascinated many scientists since their discovery at the beginning of the 20th century. However, the chemical and physical processes involved in this curious oscillatory combustion remain unknown. Several theories have been proposed: One claims that two different reactions occur: one during the slow dark phase and another during the fast flash phase. The alternation between the phases is ascribed to heat variations. Other theories suggest that the formation of intermediate species during the dark phase and the change of phase are caused by variations in their concentration. A ternary strobe composition with ammonium perchlorate, magnalium, and barium sulfate is analyzed. The role of barium sulfate is studied by replacing it by other metal sulfates that have different physical properties (melting points), and the burning of the compositions is recorded with a high-speed camera and a spectrometer coupled with a charge-coupled device (CCD) camera. Experimental results show noticeable differences in the physical and chemical processes involved in the strobe reactions. PMID:22486459

  17. Droplet Combustion Experiment (DCE)

    NASA Technical Reports Server (NTRS)

    Haggard, John B., Jr.; Nayagan, Vedha; Dryer, Frederick L.; Williams, Forman A.

    1998-01-01

    The first space-based experiments were performed on the combustion of free, individual liquid fuel droplets in oxidizing atmospheres. The fuel was heptane, with initial droplet diameters ranging about from 1 mm to 4 mm. The atmospheres were mixtures of helium and oxygen, at pressures of 1.00, 0.50 and 0.25 bar, with oxygen mole fractions between 20% and 40%, as well as normal Spacelab cabin air. The temperatures of the atmospheres and of the initial liquid fuel were nominally 300 K. A total of 44 droplets were burned successfully on the two flights, 8 on the shortened STS-83 mission and 36 on STS-94. The results spanned the full range of heptane droplet combustion behavior, from radiative flame extinction at larger droplet diameters in the more dilute atmospheres to diffusive extinction in the less dilute atmospheres, with the droplet disappearing prior to flame extinction at the highest oxygen concentrations. Quasisteady histories of droplet diameters were observed along with unsteady histories of flame diameters. New and detailed information was obtained on burning rates, flame characteristics and soot behavior. The results have motivated new computational and theoretical investigations of droplet combustion, improving knowledge of the chemical kinetics, fluid mechanics and heat and mass transfer processes involved in burning liquid fuels.

  18. Spray combustion modeling

    NASA Technical Reports Server (NTRS)

    Bellan, J.

    1997-01-01

    Concern over the future availability of high quality liquid fuels or use in furnaces and boilers prompted the U. S. Department of Energy (DOE) to consider alternate fuels as replacements for the high grade liquid fuels used in the 1970's and 1980's. Alternate fuels were defined to be combinations of a large percentage of viscous, low volatility fuels resulting from the low end of distillation mixed with a small percentage of relatively low viscosity, high volatility fuels yielded by the high end of distillation. The addition of high volatility fuels was meant to promote desirable characteristics to a fuel that would otherwise be difficult to atomize and burn and whose combustion would yield a high amount of pollutants. Several questions thus needed to be answered before alternate fuels became commercially viable. These questions were related to fuel atomization, evaporation, ignition, combustion and pollutant formation. This final report describes the results of the most significant studies on ignition and combustion of alternative fuels.

  19. Device for improved combustion

    SciTech Connect

    Polomchak, R.W.; Yacko, M.

    1988-03-08

    A device for improved combustion is described comprising: a tubular housing member having a first end and a second end, the first and second ends each having a circular opening therethrough; a combustion chamber disposed about the second end of the-tubular-housing member; a first conduit member extending from the first end of the tubular housing member and in fluid communication with the circular opening in the first end of the tubular housing member so as to allow the passage of air therethrough; a second conduit member axially disposed within the first conduit member and extending through the first conduit member and through the tubular housing member to the circular opening the second end of the tubular housing member so as to allow the passage of fuel therethrough; means for effecting turbulence in the air passing through the tubular housing member; means for effecting turbulence in the fuel passing through the second conduit member; means for intermixing and emitting the turbulent air and the fuel in a mushroom shaped configuration with the turbulent air surrounding the mushroom shaped configuration so as to substantially eliminate noxious waste gases as by-product of combustion of the air and fuel mixture.

  20. Spray combustion stability

    NASA Technical Reports Server (NTRS)

    Liang, Pak-Yan; Jeng, S. M.; Litchford, Ronald

    1995-01-01

    The central purpose of this project is the improvement of liquid-fueled rocket motor design technology in order to assist the establishment of economical commercial access to space through the development of engines with enhanced performance and reliability. Specific research effort in the project is focused on spray physics and associated combustion instability phenomena. Results garnered from this work will contribute to the development of new computational tools for design of stable liquid propellant rocket engines. The specific objectives of the research effort include identifying and evaluating physical submodels which pertain to spray combustion stability with the idea of enhancing or refining existing submodels with a more comprehensive approach. In particular, any refinements to the spray combustion physical submodels which are achieved during the project will be channeled back to Rocketdyne for incorporation in their ARICC liquid rocket combustor code as second generation improvements. Also, as the ARICC code forms the basis or future CFD development, some effort is devoted to an evaluation of the code's capability for modeling oscillating pressure waves within the combustor.

  1. Ionic liquid self-combustion synthesis of BiOBr/Bi24O31Br10 heterojunctions with exceptional visible-light photocatalytic performances

    NASA Astrophysics Data System (ADS)

    Li, Fa-Tang; Wang, Qing; Ran, Jingrun; Hao, Ying-Juan; Wang, Xiao-Jing; Zhao, Dishun; Qiao, Shi Zhang

    2014-12-01

    Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L-1 of RhB and 30 mg L-1 of MO under visible-light (λ > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed.Heterostructured BiOBr/Bi24O31Br10 nanocomposites with surface oxygen vacancies are constructed by a facile in situ route of one-step self-combustion of ionic liquids. The compositions can be easily controlled by simply adjusting the fuel ratio of urea and 2-bromoethylamine hydrobromide (BTH). BTH serves not only as a fuel, but also as a complexing agent for ionic liquids and a reactant to supply the Br element. The heterojunctions show remarkable adsorptive ability for both the cationic dye of rhodamine B (RhB) and the anionic dye of methylene orange (MO) at high concentrations, which is attributed to the abundant surface oxygen vacancies. The sample containing 75.2% BiOBr and 24.8% Bi24O31Br10 exhibits the highest photocatalytic activity. Its reaction rate constant is 4.0 and 9.0 times that of pure BiOBr in degrading 50 mg L-1 of RhB and 30 mg L-1 of MO under visible-light (λ > 400 nm) irradiation, respectively, which is attributed to the narrow band gap and highly efficient transfer efficiency of charge carriers. Different photocatalytic reaction processes and mechanisms over pure BiOBr and heterojunctions are proposed. Electronic supplementary information (ESI) available: XRD pattern for composition calculation (Fig. S1), SEM photographs (Fig. S2), N2 absorption-desorption isotherms (Fig. S3), STEM images (Fig. S4), time-course variation of ln(C0/C) of dyes (Fig. S5), Appearance photographs for adsorption of dyes (Fig. S6), UV-Vis absorption spectra of NBT (Fig. S7), pseudo-first order rate constants for RhB and MO degradation (Tables S1 and S2), electronegativity, calculated CB and VB edge positions (Table S3). See DOI: 10.1039/c4nr05451b

  2. UREA: APPARENT CARRIER-MEDIATED TRANSPORT BY FACILITATED DIFFUSION IN DOGFISH ERYTHROCYTES.

    PubMed

    MURDAUGH, H V; ROBIN, E D; HEARN, C D

    1964-04-01

    The exposure of erythrocytes from the elasmobranch, Squalus acanthias, to solutions isosmotic with plasma (IM) but containing urea or hydroxyurea as the sole solute does not produce hemolysis. Exposure of these cells to IM methylurea, thiourea and acetamide does produce hemolysis. Low concentrations of urea, which are associated with hemolysis, protect dogfish red cells against hemolysis by methylurea and thiourea. Dogfish red cells exposed to mediums containing high concentrations of urea, or no urea, reach 95 percent of their equilibrium concentration in less than 5 minutes. PMID:14107461

  3. Internal combustion engine using premixed combustion of stratified charges

    DOEpatents

    Marriott, Craig D.; Reitz, Rolf D. (Madison, WI

    2003-12-30

    During a combustion cycle, a first stoichiometrically lean fuel charge is injected well prior to top dead center, preferably during the intake stroke. This first fuel charge is substantially mixed with the combustion chamber air during subsequent motion of the piston towards top dead center. A subsequent fuel charge is then injected prior to top dead center to create a stratified, locally richer mixture (but still leaner than stoichiometric) within the combustion chamber. The locally rich region within the combustion chamber has sufficient fuel density to autoignite, and its self-ignition serves to activate ignition for the lean mixture existing within the remainder of the combustion chamber. Because the mixture within the combustion chamber is overall premixed and relatively lean, NO.sub.x and soot production are significantly diminished.

  4. The Diesel Combustion Collaboratory: Combustion Researchers Collaborating over the Internet

    SciTech Connect

    C. M. Pancerella; L. A. Rahn; C. Yang

    2000-02-01

    The Diesel Combustion Collaborator (DCC) is a pilot project to develop and deploy collaborative technologies to combustion researchers distributed throughout the DOE national laboratories, academia, and industry. The result is a problem-solving environment for combustion research. Researchers collaborate over the Internet using DCC tools, which include: a distributed execution management system for running combustion models on widely distributed computers, including supercomputers; web-accessible data archiving capabilities for sharing graphical experimental or modeling data; electronic notebooks and shared workspaces for facilitating collaboration; visualization of combustion data; and video-conferencing and data-conferencing among researchers at remote sites. Security is a key aspect of the collaborative tools. In many cases, the authors have integrated these tools to allow data, including large combustion data sets, to flow seamlessly, for example, from modeling tools to data archives. In this paper the authors describe the work of a larger collaborative effort to design, implement and deploy the DCC.

  5. Gaseous emissions during concurrent combustion of biomass and non-recyclable municipal solid waste

    PubMed Central

    2011-01-01

    Background Biomass and municipal solid waste offer sustainable sources of energy; for example to meet heat and electricity demand in the form of combined cooling, heat and power. Combustion of biomass has a lesser impact than solid fossil fuels (e.g. coal) upon gas pollutant emissions, whilst energy recovery from municipal solid waste is a beneficial component of an integrated, sustainable waste management programme. Concurrent combustion of these fuels using a fluidised bed combustor may be a successful method of overcoming some of the disadvantages of biomass (high fuel supply and distribution costs, combustion characteristics) and characteristics of municipal solid waste (heterogeneous content, conflict with materials recycling). It should be considered that combustion of municipal solid waste may be a financially attractive disposal route if a 'gate fee' value exists for accepting waste for combustion, which will reduce the net cost of utilising relatively more expensive biomass fuels. Results Emissions of nitrogen monoxide and sulphur dioxide for combustion of biomass are suppressed after substitution of biomass for municipal solid waste materials as the input fuel mixture. Interactions between these and other pollutants such as hydrogen chloride, nitrous oxide and carbon monoxide indicate complex, competing reactions occur between intermediates of these compounds to determine final resultant emissions. Conclusions Fluidised bed concurrent combustion is an appropriate technique to exploit biomass and municipal solid waste resources, without the use of fossil fuels. The addition of municipal solid waste to biomass combustion has the effect of reducing emissions of some gaseous pollutants. PMID:21284885

  6. Gas separation process using membranes with permeate sweep to remove CO.sub.2 from gaseous fuel combustion exhaust

    DOEpatents

    Wijmans Johannes G.; Merkel, Timothy C.; Baker, Richard W.

    2012-05-15

    A gas separation process for treating exhaust gases from the combustion of gaseous fuels, and gaseous fuel combustion processes including such gas separation. The invention involves routing a first portion of the exhaust stream to a carbon dioxide capture step, while simultaneously flowing a second portion of the exhaust gas stream across the feed side of a membrane, flowing a sweep gas stream, usually air, across the permeate side, then passing the permeate/sweep gas back to the combustor.

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

    PubMed

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

    2012-01-01

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

  8. Synthesis of highly elastic biodegradable poly(urethane urea).

    PubMed

    Asplund, J O Basse; Bowden, Tim; Mathisen, Torbjörn; Hilborn, Jöns

    2007-03-01

    Linear poly(urethane urea) containing a biodegradable soft segment and a hard segment built solely from methyl-2,6-diisocyanatehexanoate (LDI) is presented, using a procedure where no chain extender is required. By having LDI in excess, together with a soft segment, and adding water in the vapor phase continuously creates amines in situ resulting in hard segments containing multiple LDI units linked via urea linkages. As soft segments, polymers of trimethylene carbonate (TMC) and copolymers of TMC, epsilon-caprolactone, and D,L-lactic acid (DLLA) were used. High inherent viscosity, 0.95-1.65 dL/g, was afforded even when DLLA-containing soft segments were used, which usually undergo aminolysis. With a hard segment content between 12% and 18%, all of the materials showed very high elongation at breakage, ranging from 1600% to 4700%, and an elastic modulus from 2.1 to 140 MPa. This one-pot synthesis is simple and has now been shown to be applicable to a large number of systems. PMID:17263577

  9. Urea-based SNCR goes mainstream at utilities

    SciTech Connect

    1995-05-01

    Utilities are using urea-based Selective Non-Catalytic Reduction (SNCR) for complying with Clean Air Act Amendments (CAAA) for NO{sub x} reduction at power plants. Electric utilities, particularly in the Northeast, are required to reduce NO{sub x} emissions in accordance with state ozone abatement plans, as required by CAAA. But owners and operators must retrofit existing boilers while taking into account the different technology options, economic ramifications, outage scheduling, and potential rate and regulatory ramifications. In the past year-and-a-half, utilities awarded commercial contracts for 11 NO{sub x-} reduction boiler retrofits with urea-based SNCR, Nalco Fuel Tech`s NO{sub x}OUT Process. These 11 boilers burn coal or No. 6 fuel oil. Prior commercial applications were limited to gas-fired boilers located in California, where the Electric Power Research Institute (EPRI) originally developed the technology. Nalco Fuel Tech, EPRI`s sole licensing agent, further developed the technology in terms of utility boiler applications, and now installs it and licenses it.

  10. Nitrogen leaching from Douglas-fir forests after urea fertilization.

    PubMed

    Flint, Cynthia M; Harrison, Rob B; Strahm, Brian D; Adams, A B

    2008-01-01

    Leaching of nitrogen (N) after forest fertilization has the potential to pollute ground and surface water. The purpose of this study was to quantify N leaching through the primary rooting zone of N-limited Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] forests the year after fertilization (224 kg N ha(-1) as urea) and to calculate changes in the N pools of the overstory trees, understory vegetation, and soil. At six sites on production forests in the Hood Canal watershed, Washington, tension lysimeters and estimates of the soil water flux were used to quantify the mobilization and leaching of NO(3)-N, NH(4)-N, and dissolved organic nitrogen below the observed rooting depth. Soil and vegetation samples were collected before fertilization and 1 and 6 mo after fertilization. In the year after fertilization, the total leaching beyond the primary rooting zone in excess of control plots was 4.2 kg N ha(-1) (p = 0.03), which was equal to 2% of the total N applied. The peak NO(3)-N concentration that leached beyond the rooting zone of fertilized plots was 0.2 mg NO(3)-N L(-1). Six months after fertilization, 26% of the applied N was accounted for in the overstory, and 27% was accounted for in the O+A horizon of the soil. The results of this study indicate that forest fertilization can lead to small N leaching fluxes out of the primary rooting zone during the first year after urea application. PMID:18689739

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

    PubMed Central

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

    2012-01-01

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

  12. Roots/Routes: Part II

    ERIC Educational Resources Information Center

    Swanson, Dalene M.

    2009-01-01

    This narrative acts as an articulation of a journey of many routes. Following Part I of the same research journey of rootedness/routedness, it debates the nature of transformation and transcendence beyond personal and political paradoxes informed by neoliberalism and related repressive globalizing discourses. Through a more personal, descriptive,…

  13. Judaism and the Silk Route.

    ERIC Educational Resources Information Center

    Foltz, Richard

    1998-01-01

    Demonstrates that the Judeans traveled along the Ancient Silk Route. Discusses the Iranian influence on the formation of Jewish religious ideas. Considers the development of Jewish trade networks, focusing on the Radanites (Jewish traders), the Jewish presence in the Far East, and the survival of Judaism in central Asia. (CMK)

  14. Dynamic Weather Routes Architecture Overview

    NASA Technical Reports Server (NTRS)

    Eslami, Hassan; Eshow, Michelle

    2014-01-01

    Dynamic Weather Routes Architecture Overview, presents the high level software architecture of DWR, based on the CTAS software framework and the Direct-To automation tool. The document also covers external and internal data flows, required dataset, changes to the Direct-To software for DWR, collection of software statistics, and the code structure.

  15. Roots/Routes: Part I

    ERIC Educational Resources Information Center

    Swanson, Dalene M.

    2009-01-01

    This narrative and poetic rendering acts as an articulation of a journey of many routes. It is a storying of critical research issues and events as performances of lived experience. It is a metissage of hybrid, but interrelated, themes that find cohesion through fragmentation and coalescence, severance, and regrowth. These themes are invoked by…

  16. Fourth International Microgravity Combustion Workshop

    NASA Technical Reports Server (NTRS)

    Sacksteder, Kurt R. (Compiler)

    1997-01-01

    This Conference Publication contains 84 papers presented at the Fourth International Microgravity Combustion Workshop held in Cleveland, Ohio, from May 19 to 21, 1997. The purpose of the workshop was twofold: to exchange information about the progress and promise of combustion science in microgravity and to provide a forum to discuss which areas in microgravity combustion science need to be expanded profitably and which should be included in upcoming NASA Research Announcements (NRA).

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Nitrogen doped TiO2 nano-particles: Phase control by solution combustion method

    NASA Astrophysics Data System (ADS)

    Bapna, Komal; Choudhary, R. J.; Phase, D. M.; Shastri, Sheetal; Prasad, R.; Ahuja, B. L.

    2016-05-01

    N-doped TiO2 nano powders were prepared by sol-gel solution combustion method. The influence of different fuels (urea and citric acid) used in obtaining N-TiO2 nano particles in similar conditions (heat treatment, amount of precursors) has been investigated. The growth of different phases of TiO2 (anatase and rutile) is strongly affected by the ligands and the dehydration reaction. Reduction in the band gap of TiO2 and features observed in the XPS spectra confirm the incorporation of N into TiO2 matrix.

  20. Light Duty Efficient, Clean Combustion

    SciTech Connect

    Stanton, Donald W.

    2011-06-03

    Cummins has successfully completed the Light Duty Efficient Clean Combustion (LDECC) cooperative program with DoE. This program was established in 2007 in support of the Department of Energy’s Vehicles Technologies Advanced Combustion and Emissions Control initiative to remove critical barriers to the commercialization of advanced, high efficiency, emissions compliant internal combustion (IC) engines for light duty vehicles. Work in this area expanded the fundamental knowledge of engine combustion to new regimes and advanced the knowledge of fuel requirements for these diesel engines to realize their full potential. All of our objectives were met with fuel efficiency improvement targets exceeded.

  1. Combustion characteristics of husk charcoal

    SciTech Connect

    Shimizu, H.; Kimura, T.; Nishiyama, Y.; Terui, T.

    1984-07-01

    This paper analyzes the factors involved in the extraordinary temperature generation in husk combustion furnaces, and investigates methods of protecting furnaces from heat damage. The combustion characteristics of fixed carbon in rice husks are examined in relation to the air flow rate using different husk charcoals. The theoretical flame temperature in a practical bed was determined from the combustion propagation velocity. It is determined that deviation from the regression line relating the combustion propagation velocity with the specific air flow rate showed a slight correlation with the bulk density of the charcoal samples used.

  2. Microgravity Smoldering Combustion Takes Flight

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Microgravity Smoldering Combustion (MSC) experiment lifted off aboard the Space Shuttle Endeavour in September 1995 on the STS-69 mission. This experiment is part of series of studies focused on the smolder characteristics of porous, combustible materials in a microgravity environment. Smoldering is a nonflaming form of combustion that takes place in the interior of combustible materials. Common examples of smoldering are nonflaming embers, charcoal briquettes, and cigarettes. The objective of the study is to provide a better understanding of the controlling mechanisms of smoldering, both in microgravity and Earth gravity. As with other forms of combustion, gravity affects the availability of air and the transport of heat, and therefore, the rate of combustion. Results of the microgravity experiments will be compared with identical experiments carried out in Earth's gravity. They also will be used to verify present theories of smoldering combustion and will provide new insights into the process of smoldering combustion, enhancing our fundamental understanding of this frequently encountered combustion process and guiding improvement in fire safety practices.

  3. [Effects of coated controlled release urea combined with conventional urea on winter wheat growth and soil NO3- -N].

    PubMed

    Yi, Wen-ping; Sun, Zhe; Wu, Liang; Shi, Gui-fang; Zhu, Guo-liang; Li, Ya-xing; Gu, Jia-lin; Xu, Qiu-ming

    2011-03-01

    Field experiments were conducted to study the effects of different dosages coated controlled release urea (PCU60, 60 d release duration) combined with conventional urea (U) used as basal on the winter wheat grain yield, nitrogen (N) recovery rate, and soil NO3- -N content, etc. Five treatments were installed, i.e., U (CK), 10% PCU60+90% U (PU1), 20% PCU60+80% U (PU2), 30% PCU60+70% U (PU3), and 40% PCU60+60% U (PU4). In the meantime, a comparative analysis was also carried out on the PCU60 N release characteristics under field condition and in 25 "C static water. At the same N dosage, all the test indices in treatment PU4 were significantly higher, with the grain yield, N recovery rate, total N accumulation amount, total tiller number and aboveground biomass at ripening stage, and economic benefit increased by 5.6%, 14.6%, 7.2%, 2.6%, 7.5%, and 984.3 yuan x hm(-2), respectively, compared with those in treatment U. The accumulation amount of NO3- -N in 0-100 cm soil layer in all treatments ranged in 39.70-49.93 kg x hm-2, and was the lowest (39.70 kg x hm(-2)) in treatment PU4. The N release pattern of PCU60 under field condition better fitted the N absorption characteristics of winter wheat. PMID:21657025

  4. Combustion Byproducts Recycling Consortium

    SciTech Connect

    Ziemkiewicz, Paul; Vandivort, Tamara; Pflughoeft-Hassett, Debra; Chugh, Y Paul; Hower, James

    2008-08-31

    Each year, over 100 million tons of solid byproducts are produced by coal-burning electric utilities in the United States. Annual production of flue gas desulfurization (FGD) byproducts continues to increase as the result of more stringent sulfur emission restrictions. In addition, stricter limits on NOx emissions mandated by the 1990 Clean Air Act have resulted in utility burner/boiler modifications that frequently yield higher carbon concentrations in fly ash, which restricts the use of the ash as a cement replacement. Controlling ammonia in ash is also of concern. If newer, “clean coal” combustion and gasification technologies are adopted, their byproducts may also present a management challenge. The objective of the Combustion Byproducts Recycling Consortium (CBRC) is to develop and demonstrate technologies to address issues related to the recycling of byproducts associated with coal combustion processes. A goal of CBRC is that these technologies, by the year 2010, will lead to an overall ash utilization rate from the current 34% to 50% by such measures as increasing the current rate of FGD byproduct use and increasing in the number of uses considered “allowable” under state regulations. Another issue of interest to the CBRC would be to examine the environmental impact of both byproduct utilization and disposal. No byproduct utilization technology is likely to be adopted by industry unless it is more cost-effective than landfilling. Therefore, it is extremely important that the utility industry provide guidance to the R&D program. Government agencies and privatesector organizations that may be able to utilize these materials in the conduct of their missions should also provide input. The CBRC will serve as an effective vehicle for acquiring and maintaining guidance from these diverse organizations so that the proper balance in the R&D program is achieved.

  5. Combustion Branch Website Development

    NASA Technical Reports Server (NTRS)

    Bishop, Eric

    2004-01-01

    The NASA combustion branch is a leader in developing and applying combustion science to focused aerospace propulsion systems concepts. It is widely recognized for unique facilities, analytical tools, and personnel. In order to better communicate the outstanding research being done in this Branch to the public and other research organization, a more substantial website was desired. The objective of this project was to build an up-to-date site that reflects current research in a usable and attractive manner. In order to accomplish this, information was requested from all researchers in the Combustion branch, on their professional skills and on the current projects. This information was used to fill in the Personnel and Research sections of the website. A digital camera was used to photograph all personnel and these photographs were included in the personnel section as well. The design of the site was implemented using the latest web standards: xhtml and external css stylesheets. This implementation conforms to the guidelines recommended by the w3c. It also helps to ensure that the web site is accessible by disabled users, and complies with Section 508 Federal legislation (which mandates that all Federal websites be accessible). Graphics for the new site were generated using the gimp (www.gimp.org) an open-source graphics program similar to Adobe Photoshop. Also, all graphics on the site were of a reasonable size (less than 20k, most less than 2k) so that the page would load quickly. Technologies such as Macromedia Flash and Javascript were avoided, as these only function on some clients which have the proper software installed or enabled. The website was tested on different platforms with many different browsers to ensure there were no compatibility issues. The website was tested on windows with MS IE 6, MSIE 5 , Netscape 7, Mozilla and Opera. On a Mac, the site was tested with MS IE 5 , Netscape 7 and Safari.

  6. Combustion Byproducts Recycling Consortium

    SciTech Connect

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    Each year, over 100 million tons of solid byproducts are produced by coal-burning electric utilities in the United States. Annual production of flue gas desulfurization (FGD) byproducts continues to increase as the result of more stringent sulfur emission restrictions. In addition, stricter limits on NOx emissions mandated by the 1990 Clean Air Act have resulted in utility burner/boiler modifications that frequently yield higher carbon concentrations in fly ash, which restricts the use of the ash as a cement replacement. Controlling ammonia in ash is also of concern. If newer, 'clean coal' combustion and gasification technologies are adopted, their byproducts may also present a management challenge. The objective of the Combustion Byproducts Recycling Consortium (CBRC) is to develop and demonstrate technologies to address issues related to the recycling of byproducts associated with coal combustion processes. A goal of CBRC is that these technologies, by the year 2010, will lead to an overall ash utilization rate from the current 34% to 50% by such measures as increasing the current rate of FGD byproduct use and increasing in the number of uses considered 'allowable' under state regulations. Another issue of interest to the CBRC would be to examine the environmental impact of both byproduct utilization and disposal. No byproduct utilization technology is likely to be adopted by industry unless it is more cost-effective than landfilling. Therefore, it is extremely important that the utility industry provide guidance to the R&D program. Government agencies and private-sector organizations that may be able to utilize these materials in the conduct of their missions should also provide input. The CBRC will serve as an effective vehicle for acquiring and maintaining guidance from these diverse organizations so that the proper balance in the R&D program is achieved.

  7. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

    A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

  8. Spray combustion stability

    NASA Technical Reports Server (NTRS)

    Liang, Pak-Yan; Jeng, San-Mou; Litchford, Ronald

    1989-01-01

    The central purpose of this project is the improvement of liquid-fueled rocket motor design technology in order to assist the establishment of economical commercial access to space through the development of engines with enhanced performance and reliability. Specific research effort is focused on spray physics and associated combustion instability phenomena. Results concerning high pressure droplet gasification model, droplet turbulent dispersion model, and spray atomization model will contribute to the development of new computational tools for design of stable liquid propellant rocket engines.

  9. Liquid propellant combustion waves

    NASA Astrophysics Data System (ADS)

    Yoon, W. S.; Chung, T. J.

    1991-06-01

    Design of efficient and stable combustors depends on accurate analysis of flowfields. This study examines combustion waves arising from hydrogen-air reactions in the scramjet flame holders with various ramp angles. Two-step Taylor-Galerkin finite element methods are used to solve the Navier-Stokes system of equations. Fluctuation quantities are calculated from the Navier-Stokes solution as a function of time. From these data the energy growth rate parameters and energy growth factors using the entropy-controlled instability method are determined.

  10. Stand-alone sensors monitor for combustible gas leaks

    SciTech Connect

    Not Available

    1991-01-01

    Elizabeth Gas Co., a gas distribution company in New Jersey, has added a network of combustible gas sensors to a computer system already in place for continuous monitoring of gas leaks. The computer center at the company's Erie St. facility controls all dispatching, which includes routing gas through the system and controlling gas pressure. The system uses redundant Hewlett-Packard A900 central processing units (CPU), 6 monitors, including a Mitsubishi 35-in. color monitor, and Fisher control software. The company's primary tank farm, which contains over a million gallons of propane and LNG, is located near several chemical plants, an oil refinery and a residential neighborhood. To monitor for combustible leaks at the site, the company installed 49 stand-alone combustible gas sensors manufactured by Mine Safety Appliances Co. (MSA) of Pittsburgh, Pa. The sensors are designed to measure the concentrations of propane and LNG and trigger alarms at 20% of the lower explosive limit (LEL). The sensors are diffusion types that sample ambient air rather than drawing in samples through a pump. Using the principle of catalytic oxidation, the sensors produce a signal proportional to the concentration of combustible gas in the atmosphere. If gas is detected above 20% of the LEL, a relay driver signal is sent into a remote annunciator panel which contains LED alarm displays for each sensor. The remote annunciator panel also houses a 24 VDC power supply.

  11. Emergency response mobile robot for operations in combustible atmospheres

    NASA Astrophysics Data System (ADS)

    Stone, Henry W.; Ohm, Timothy R.

    1995-08-01

    A mobile, self-powered, self-contained, and remote-controlled robot is presented. The robot is capable of safely operating in a combustible atmosphere and providing information about the atmosphere to the operator. The robot includes non-sparking and non-arcing electro-mechanical and electronic components designed to prevent the robot from igniting the combustible atmosphere. The robot also includes positively pressurized enclosures that house the electromechanical and electronic components of the robot and prevent intrusion of the combustible atmosphere into the enclosures. The enclosures are interconnected such that a pressurized gas injected into any one of the enclosures is routed to all the other enclosures through the interconnections. It is preferred that one or more sealed internal channels through structures intervening between the enclosures be employed. Pressure transducers for detecting if the pressure within the enclosures falls below a predetermined level are included. The robot also has a sensing device for determining the types of combustible substances in the surrounding atmosphere, as well as the concentrations of each type of substance relative to a pre-determined lower explosive limit (LEL). In addition, the sensing device can determine the percent level of oxygen present in the surrounding atmosphere.

  12. An emergency response mobile robot for operations in combustible atmospheres

    NASA Astrophysics Data System (ADS)

    Stone, Henry W.; Ohm, Timothy R.

    1993-11-01

    A mobile, self-powered, self-contained, and remote-controlled robot is presented. The robot is capable of safely operating in a combustible atmosphere and providing information about the atmosphere to the operator. The robot includes non-sparking and non-arcing electro-mechanical and electronic components designed to prevent the robot from igniting the combustible atmosphere. The robot also includes positively pressurized enclosures that house the electromechanical and electronic components of the robot and prevent intrusion of the combustible atmosphere into the enclosures. The enclosures are interconnected such that a pressurized gas injected into any one of the enclosures is routed to all the other enclosures through the interconnections. It is preferred that one or more sealed internal channels through structures intervening between the enclosures be employed. Pressure transducers for detecting if the pressure within the enclosures falls below a predetermined level are included. The robot also has a sensing device for determining the types of combustible substances in the surrounding atmosphere, as well as the concentrations of each type of substance relative to a pre-determined lower explosive limit (LEL). In addition, the sensing device can determine the percent level of oxygen present in the surrounding atmosphere.

  13. Emergency response mobile robot for operations in combustible atmospheres

    NASA Technical Reports Server (NTRS)

    Stone, Henry W. (Inventor); Ohm, Timothy R. (Inventor)

    1995-01-01

    A mobile, self-powered, self-contained, and remote-controlled robot is presented. The robot is capable of safely operating in a combustible atmosphere and providing information about the atmosphere to the operator. The robot includes non-sparking and non-arcing electro-mechanical and electronic components designed to prevent the robot from igniting the combustible atmosphere. The robot also includes positively pressurized enclosures that house the electromechanical and electronic components of the robot and prevent intrusion of the combustible atmosphere into the enclosures. The enclosures are interconnected such that a pressurized gas injected into any one of the enclosures is routed to all the other enclosures through the interconnections. It is preferred that one or more sealed internal channels through structures intervening between the enclosures be employed. Pressure transducers for detecting if the pressure within the enclosures falls below a predetermined level are included. The robot also has a sensing device for determining the types of combustible substances in the surrounding atmosphere, as well as the concentrations of each type of substance relative to a pre-determined lower explosive limit (LEL). In addition, the sensing device can determine the percent level of oxygen present in the surrounding atmosphere.

  14. An emergency response mobile robot for operations in combustible atmospheres

    NASA Technical Reports Server (NTRS)

    Stone, Henry W. (Inventor); Ohm, Timothy R. (Inventor)

    1993-01-01

    A mobile, self-powered, self-contained, and remote-controlled robot is presented. The robot is capable of safely operating in a combustible atmosphere and providing information about the atmosphere to the operator. The robot includes non-sparking and non-arcing electro-mechanical and electronic components designed to prevent the robot from igniting the combustible atmosphere. The robot also includes positively pressurized enclosures that house the electromechanical and electronic components of the robot and prevent intrusion of the combustible atmosphere into the enclosures. The enclosures are interconnected such that a pressurized gas injected into any one of the enclosures is routed to all the other enclosures through the interconnections. It is preferred that one or more sealed internal channels through structures intervening between the enclosures be employed. Pressure transducers for detecting if the pressure within the enclosures falls below a predetermined level are included. The robot also has a sensing device for determining the types of combustible substances in the surrounding atmosphere, as well as the concentrations of each type of substance relative to a pre-determined lower explosive limit (LEL). In addition, the sensing device can determine the percent level of oxygen present in the surrounding atmosphere.

  15. The mechanism of passage of endogenous urea through the rumen wall and the role of ureolytic epithelial bacteria in the urea flux.

    PubMed

    Cheng, K J; Wallace, R J

    1979-11-01

    1. The rumen urea concentration in gnotobiotic lambs lacking ureolytic bacteria was equal to that of blood. 2. Bacterial urease (EC 3.5.1.5) activity in sheep fed by intraruminal and intra-abomasal infusion was inversely related to rumen ammonia concentration. 3. A model is proposed for the facilitation and control of urea flux by wall-found ureolytic bacteria. PMID:508714

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

    EPA Science Inventory

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

  17. Role of rumen butyrate in regulation of nitrogen utilization and urea nitrogen kinetics in growing sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Butyrate, a major rumen VFA, has been indirectly linked to enhancement of urea recycling based on increased expression of urea transporter (UT-B) in the rumen epithelia of steers fed a rumen butyrate-enhancing diet. Two studies were conducted to quantify the effect of elevated rumen butyrate concent...

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

    NASA Technical Reports Server (NTRS)

    Mueller, W. A. (Inventor)

    1978-01-01

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

  19. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... polymer (generic). 721.10533 Section 721.10533 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical... as amine-modified urea-formaldehyde polymer (PMN P-12-182) is subject to reporting under this...

  20. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... polymer (generic). 721.10533 Section 721.10533 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical... as amine-modified urea-formaldehyde polymer (PMN P-12-182) is subject to reporting under this...

  1. A Gas-Sensor-Based Urea Enzyme Electrode: Its Construction and Use in the Undergraduate Laboratory.

    ERIC Educational Resources Information Center

    Riechel, Thomas L.

    1984-01-01

    Describes an undergraduate experiment for the potentiometric determination of urea based on the physical entrapment of urease on the tip of an ammonia gas sensor. An advantage of this technique is the ease with which the ammonia electrode can be converted to a urea electrode. (JN)

  2. Nitrogen regulation involved in the accumulation of urea in Saccharomyces cerevisiae.

    PubMed

    Zhao, Xinrui; Zou, Huijun; Fu, Jianwei; Chen, Jian; Zhou, Jingwen; Du, Guocheng

    2013-11-01

    Rice wine is a popular traditional alcoholic drink with a long history in China. However, the presence of the potential carcinogen ethyl carbamate (EC) raises a series of food safety concerns. Although the metabolic pathway of urea (the major precusor of EC) has been characterized in Saccharomyces cerevisiae, the regulation of urea accumulation remains unclear, making the efficient elimination of urea difficult. To demonstrate the regulatory mechanisms governing urea accumulation, three key nitrogen sources that can inhibit urea utilization for a commercial S. cerevisiae strain were identified. In addition, regulators of nitrogen catabolite repression (NCR) and target of rapamycin (TOR) pathways were identified as being involved in urea accumulation by real-time quantitative PCR. Based on these results, preferred nitrogen sources were found to repress urea utilization by converting them to glutamine or glutamate. Moreover, the results indicated that the manner of urea metabolism regulation was different for two positive regulators involved in NCR; Gln3p can be retained in the cytoplasm by glutamine, while Gat1p can be retained by glutamine and glutamate. Furthermore, this was confirmed by fluorescence location detection. These new findings provide new targets for eliminating EC and other harmful nitrogen-containing compounds in fermented foods. PMID:23996237

  3. CLINICAL CONSEQUENCES OF UREA CYCLE ENZYME DEFICIENCIES AND POTENTIAL LINKS TO ARGININE AND NITRIC OXIDE METABOLISM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea cycle disorders (UCD) are human conditions caused by the dysregulation of nitrogen transfer from ammonia nitrogen into urea. The biochemistry and the genetics of these disorders were well elucidated. Earlier diagnosis and improved treatments led to an emerging, longer-lived cohort of patients. ...

  4. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 30 2013-07-01 2012-07-01 true Applicability; description of the urea subcategory. 418.30 Section 418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory §...

  5. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the urea subcategory. 418.30 Section 418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory §...

  6. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 29 2014-07-01 2012-07-01 true Applicability; description of the urea subcategory. 418.30 Section 418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory §...

  7. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 30 2012-07-01 2012-07-01 false Applicability; description of the urea subcategory. 418.30 Section 418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory §...

  8. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 29 2011-07-01 2009-07-01 true Applicability; description of the urea subcategory. 418.30 Section 418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory §...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  10. EFFECTS OF DIETARY CRUDE PROTEIN ON SERUM AND URINE UREA NITROGEN IN FEEDLOT STEERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of dietary CP concentration and source on serum urea N (SUN) and urine urea N (UUN). A metabolism trial with three collection periods (approximately d 35, 95, and 155 on feed) was conducted using twenty seven crossbred steers (average BW = 353.2 ± 8.4 kg). Treatments were ...

  11. Effect of urea on growth and microcystins production of Microcystis aeruginosa.

    PubMed

    Wu, Xuanhao; Yan, Yangwei; Wang, Pinfei; Ni, Lanqi; Gao, Jiayi; Dai, Ruihua

    2015-04-01

    The effects of urea on the growth and toxin content of Microcystis aeruginosa isolated from Dianchi Lake in China were investigated. Experiments were carried out in lab using (15)N isotopic technique to characterize urea-N biosynthesis to microcystins. High urea concentration (3.6 mmol-N L(-1)) would restrict the growth of M.aeruginosa and the production of microcystin-LR, while low urea concentration (0.4-1.4 mmol-N L(-1)) would promote the growth of M.aeruginosa and the production of microcystin-LR. The (15)N labeling experiment further demonstrated that there existed selectivity when M.aeruginosa assimilated urea to form its structure. The majority of M.aeruginosa assimilated 1 urea molecule at first which was biosynthesized into the Ala or Leu residue. On day 18, The m/z=1004 parent ion assimilated 9 (15)N except that the Mdha residue did not assimilate any urea-(15)N. The results give deeper insight to the biosynthesis of urea into microcystins. PMID:25638406

  12. Interaction-component analysis of the urea effect on amino acid analogs.

    PubMed

    Karino, Yasuhito; Matubayasi, Nobuyuki

    2013-03-28

    Transfer energetics from pure water to a urea-water mixture is examined for a set of amino acid analog solutes by using molecular dynamics simulation and free-energy calculation. The free energy of transfer from pure-water solvent to 8 M urea-water mixed solvent is calculated for each solute, and the urea-water mixture is shown to be a more favorable solvent than pure water. The correlation of the transfer free energy is then examined against the corresponding changes upon transfer of the average sum of solute-solvent interaction energy and its electrostatic and van der Waals components. A strong correlation is observed against the change in solute-solvent energy, with a dominant contribution from the van der Waals component for neutral solutes. The electrostatic component exhibits a weak correlation due to the compensation between the contributions from urea and water. The transfer free energy is further decomposed into the contributions from urea and water within an approximate framework of the energy-representation theory of solvation. It is found that urea makes a favorable contribution to the transfer free energy. The contribution from water depends on the hydrophobicity/hydrophilicity of the solute. Urea and water act cooperatively for hydrophobic solute, and are competitive against each other for hydrophilic solute. The effect of excluded volume is also addressed, and is seen to be minor in the transfer energetics due to the compensation between the contributions from urea and water. PMID:23416730

  13. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    Code of Federal Regulations, 2010 CFR

    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...

  14. Biomechanical studies on aliphatic physically crosslinked poly(urethane urea) for blood contact applications.

    PubMed

    Thomas, Vinoy; Muthu, Jayabalan

    2008-07-01

    Hydrophobic and physically crosslinked (virtually crosslinked through hydrogen bonding) aliphatic poly(urethane urea)s were developed and characterized for its biomechanical properties. The aging under induced-stress (bend samples) condition reveals resistance of poly(urethane urea) to environmental stress corrosion cracking (ESC) in hydrolytic media, Ringer's solution and phosphate buffered saline at 50 degrees C. The strain-induced (20% tensile strain) and aged polymer in hydrolytic enzyme medium, papain and in buffer reveals increase of elastic modulus in papain enzyme and papain buffer. The increase of elastic modulus is attributed to unidirectional reorganisation of chains under continually strained conditions. The polymer exposed in boiling alcoholic potassium hydroxide solution (accelerated hydrolytic chemical degradation) reveals no degradation. A comparative evaluation of poly(ether urethane urea)s reveals inferior properties. Poly(ether urethane urea)s polymer undergo hydrolytic degradation in boiling alcoholic potassium hydroxide solution. The candidate poly(urethane urea) HFL 18-PUU is more promising elastomer for long-term biomechanically sensitive blood contact applications such as heart valve and blood pump diaphragm of left ventricular assist device. PMID:18305906

  15. Evaluation of milk urea nitrogen as a management tool to reduce ammonia emissions from dairy farms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this study was to compile and evaluate relationships between feed nitrogen (N) intake, milk urea N (MUN), urinary urea N (UUN) and ammonia (NH3) emissions from dairy farms to aid policy development. Regression relationships between MUN (within the range of 10 to 25 mg/dL), UUN, and re...

  16. Synthesis of urea in cometary model ices and implications for Comet 67P/Churyumov-Gerasimenko.

    PubMed

    Förstel, M; Maksyutenko, P; Jones, B M; Sun, B-J; Chang, A H H; Kaiser, R I

    2015-12-24

    Urea is considered a fundamental building block in prebiotic chemistry. Its formation on early Earth has not yet been explained satisfactorily and exogenous delivery has been considered. We report on the synthesis along with the first online and in situ identification of urea after exposing inorganic ices to ionizing radiation. PMID:26564002

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

    PubMed

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

    2016-06-01

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

  18. UREA PRODUCTION, RECYCLING AND EXCRETION IN FORAGE-FED BEEF STEERS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two experiments with growing beef steers fed hays of warm season (gamagrass and switchgrass) or cool season (tall fescue) grasses showed a strong linear relationship between urea production by the animal and urinary urea excretion as functions of nitrogen (crude protein) intake. The nature of the r...

  19. 40 CFR 721.9920 - Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Urea, (hexahydro-6-methyl-2... Specific Chemical Substances § 721.9920 Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-. (a) Chemical...-methyl-2oxopyrimidinyl)- (PMN P-89-303) is subject to reporting under this section for the...

  20. 76 FR 78885 - Solid Urea From the Russian Federation and Ukraine: Continuation of Antidumping Duty Orders

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-20

    ... also Solid Urea From Russia and Ukraine, 75 FR 74746 (December 1, 2010). \\1\\ On July 14, 1987, the... States within a reasonably foreseeable time. See Solid Urea From Russia and Ukraine, 76 FR 77015... Russian Federation (Russia) and Ukraine would likely lead to a continuation or recurrence of dumping...

  1. Label-free and pH-sensitive colorimetric materials for the sensing of urea.

    PubMed

    Li, Lu; Long, Yue; Gao, Jin-Ming; Song, Kai; Yang, Guoqiang

    2016-02-18

    This communication demonstrates a facile method for naked-eye detection of urea based on the structure color change of pH-sensitive photonic crystals. The insertion of urease provides excellent selectivity over other molecules. The detection of urea in different concentration ranges could be realized by changing the molar ratio between the functional monomer and cross-linker. PMID:26847584

  2. Electron spin echo modulation study of sodium dodecyl sulfate and dodecyltrimethylammonium bromide micellar solutions in the presence of urea: Evidence for urea interaction at the micellar surface

    SciTech Connect

    Baglioni, P. ); Ferroni, E. ); Kevan, L. )

    1990-05-17

    Electron spin echo studies have been carried out for a series of x-doxylstearic acid (x-DSA, x = 5,7,10,12,16) and 4-octanoyl-2,2,6,6-tetramethylpiperidine-1-oxy (C{sub 8}-TEMPO) spin probes in micellar solutions of anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) in D{sub 2}O and in the presence of 2 or 6 M urea or urea-d{sub 4}. Modulation effects due to the interaction of the unpaired electron with urea and water deuteriums show that urea does not affect the bent conformation of the x-DSA probe in the micelle. The analysis of the deuterium modulation depth and the Fourier transformation of the two-pulse electron spin echo spectra show that urea interacts with the surfactant polar headgroups at the micelle surface. These results support recent molecular dynamics and Monte Carlo calculations of micellar systems and are in agreement with direct interaction of urea at micellar surfaces in which it replaces some water molecules in the surface region.

  3. Some Factors Affecting Combustion in an Internal-Combustion Engine

    NASA Technical Reports Server (NTRS)

    Rothrock, A M; Cohn, Mildred

    1936-01-01

    An investigation of the combustion of gasoline, safety, and diesel fuels was made in the NACA combustion apparatus under conditions of temperature that permitted ignition by spark with direct fuel injection, in spite of the compression ratio of 12.7 employed. The influence of such variables as injection advance angle, jacket temperature, engine speed, and spark position was studied. The most pronounced effect was that an increase in the injection advance angle (beyond a certain minimum value) caused a decrease in the extent and rate of combustion. In almost all cases combustion improved with increased temperature. The results show that at low air temperatures the rates of combustion vary with the volatility of the fuel, but that at high temperatures this relationship does not exist and the rates depend to a greater extent on the chemical nature of the fuel.

  4. Preliminary assessment of combustion modes for internal combustion wave rotors

    NASA Technical Reports Server (NTRS)

    Nalim, M. Razi

    1995-01-01

    Combustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Several modes of combustion are considered and the factors that determine the applicability of three modes are evaluated in detail; premixed autoignition/detonation, premixed deflagration, and non-premixed compression ignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The compression/autoignition modes will require inlet temperatures in excess of 1500 R for reliable ignition with most hydrocarbon fuels; otherwise, a supplementary ignition method must be provided. Examples of combustion mode selection are presented for two core engine applications that had been previously designed with equivalent 4-port wave rotor topping cycles using external combustion.

  5. Formaldehyde emissions from combustion sources and solid formaldehyde resin containing products: potential impact on indoor formaldehyde concentrations

    SciTech Connect

    Matthews, T.G.; Reed, T.J.; Tromberg, B.J.; Daffron, C.R.; Hawthorne, A.R.

    1984-04-12

    The formaldehyde (CH/sub 2/O) emission rates of combustion sources and solid CH/sub 2/O resin-containing products commonly found in domestic environments are surveyed. The potential impact of these sources on indoor CH/sub 2/O concentrations are estimated using simple steady-state, indoor pollutant concentration models. Source emission rates, product loadings for solid emission sources, duty cycles for combustion sources, and potential permeation barriers are considered in the model. The strongest contributors to indoor CH/sub 2/O are pressed-wood products and foam insulation containing urea formaldehyde resins. Combustion sources and phenol-formaldehyde resin-bonded products are generally weak emitters. 26 references, 1 figure, 9 tables.

  6. Multicast Routing of Hierarchical Data

    NASA Technical Reports Server (NTRS)

    Shacham, Nachum

    1992-01-01

    The issue of multicast of broadband, real-time data in a heterogeneous environment, in which the data recipients differ in their reception abilities, is considered. Traditional multicast schemes, which are designed to deliver all the source data to all recipients, offer limited performance in such an environment, since they must either force the source to overcompress its signal or restrict the destination population to those who can receive the full signal. We present an approach for resolving this issue by combining hierarchical source coding techniques, which allow recipients to trade off reception bandwidth for signal quality, and sophisticated routing algorithms that deliver to each destination the maximum possible signal quality. The field of hierarchical coding is briefly surveyed and new multicast routing algorithms are presented. The algorithms are compared in terms of network utilization efficiency, lengths of paths, and the required mechanisms for forwarding packets on the resulting paths.

  7. Daisy Found on 'Route 66'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This composite image from the panoramic camera on NASA's Mars Exploration Rover Spirit gives an approximately true-color rendering of a daisy-like pattern of brushed circles that Spirit produced on a rock called 'Route 66.' Spirit used the rock abrasion tool to complete this 6-position 'RAT daisy' on sol 99. It took this image on sol 100, April 14, 2004.

    The purpose for these large brushings is to create a large enough patch of treated surface area for the miniature thermal emission spectrometer to analyze. Scientists had previously conducted a brushing like this one on the rock 'Mazatzal.' The brushed area of Route 66 looks very different from the brushed area of Mazatzal, leading scientists to think that the rocks although both light in tone actually have different coating types.

  8. Plasma igniter for internal-combustion engines

    NASA Technical Reports Server (NTRS)

    Breshears, R. R.; Fitzgerald, D. J.

    1978-01-01

    Hot ionized gas (plasma) ignites air/fuel mixture in internal combustion engines more effectively than spark. Electromagnetic forces propel plasma into combustion zone. Combustion rate is not limited by flame-front speed.

  9. Path planning during combustion mode switch

    SciTech Connect

    Jiang, Li; Ravi, Nikhil

    2015-12-29

    Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

  10. AIR EMISSIONS FROM SCRAP TIRE COMBUSTION

    EPA Science Inventory

    The report discusses air emissions from two types of scrap tire combustion: uncontrolled and controlled. Uncontrolled sources are open tire fires, which produce many unhealthful products of incomplete combustion and release them directly into the atmosphere. Controlled combustion...

  11. Two different mechanisms for urea action at the LAC and TNA operons in Escherichia coli.

    PubMed

    Blazy, B; Ullmann, A

    1990-02-01

    Urea, at concentrations which do not interfere with bacterial growth, specifically inhibits the expression of catabolite sensitive operons. To search for the target and the mechanism of urea action we measured lactose (lac) and tryptophanase (tna) specific mRNA synthesis in vivo and in vitro. We show that urea acts by two different mechanisms at these two catabolite sensitive operons, resembling the manner in which catabolite repression regulates lac and tna. At the lac promoter, urea abolishes transcription initiation or blocks an early step in mRNA elongation without interfering with the binding of RNA polymerase and catabolite gene activator protein (CAP). At the tna promoter, urea does not abolish transcription initiation but could interfere with tnaC translation. PMID:2160052

  12. Urea-montmorillonite-extruded nanocomposites: a novel slow-release material.

    PubMed

    Pereira, Elaine I; Minussi, Fernando B; da Cruz, Camila C T; Bernardi, Alberto C C; Ribeiro, Caue

    2012-05-30

    The present study describes the preparation and characterization of a novel urea slow-release nanocomposite, based on urea intercalation into montmorillonite clay by an extrusion process at room temperature. Nanocomposites with urea contents ranging from 50 to 80 wt % were successfully produced and characterized. Analyses by XRD, DTA, and SEM-EDX confirmed the effectiveness of this simple process to exfoliate the clay lamellae into the urea matrix, forming a product that can be classified as a nanocomposite, due to the exfoliation degree attained. Diametral compression tests showed that the samples were very deformable, and the release rate of active components in water showed that the nanocomposite showed a slow release behavior for urea dissolution, even in low montmorillonite amounts (20% in weight). PMID:22574809

  13. Solution conformation of an oligonucleotide containing a urea deoxyribose residue in front of a thymine.

    PubMed Central

    Gervais, V; Guy, A; Téoule, R; Fazakerley, G V

    1992-01-01

    Urea residues are produced by ionizing radiation on thymine residues in DNA. We have studied an oligodeoxynucleotide containing a thymine opposite the urea residue, by one and two dimensional NMR spectroscopy. The urea deoxyribose exists as two isomers with respect to the orientation about the peptide bond. For the trans isomer we find that the thymine and urea site are positioned within the helix and are probably hydrogen bonded. The oligonucleotide adopts a globally B form structure although conformational changes are observed around the mismatch site. A minor species is observed, in which the urea deoxyribose and the opposite base adopt an extrahelical position and this corresponds to the isomer cis for the peptide bond. PMID:1480468

  14. Coal combustion ash haulback

    SciTech Connect

    Gray, R.E.; Gray, T.A.

    1998-12-31

    Coal mining disturbs large tracts of land which must be reclaimed. Unfortunately, iron sulfides which are common in most coals and the adjacent strata weather, forming acid mine drainage (AMD) which degrades surface and ground water. Burning of coal produces combustion by products, most of which are placed in ponds or landfills. Suitable disposal areas are difficult to find and permit, especially in urban areas. This has led to ash haulback--where the waste generated during coal burning is hauled back to a mine for disposal. The potential advantages of coal combustion ash haulback are: Disposal occurs in a disturbed area (mine) rather than disturb additional land near the power plant; The same vehicles used to haul coal from the mine can be used to return the ash to the mine; Ash, if alkaline, may provide neutralization of acidic water or mine overburden commonly found at coal mines; and Low permeability ash could reduce ground water flow through the mine backfill, thus reducing leaching of acid forming constituents or metals. Placement of ash in surface mines provides an efficient, cost-effective method of disposal while at the same time contributing to reclamation of the mine. Wise natural resource management suggests a reasonable approach to disposal of coal ash is to return it to its original location--the mine.

  15. Combustion driven oscillations

    NASA Astrophysics Data System (ADS)

    Mugridge, B. D.

    1980-06-01

    Combustion driven oscillations can occur when a turbulent flame is enclosed in a tube or cavity. Interaction between heat fluctuations and the internal standing wave field at one of the natural frequencies of the air column produces strong organ pipe tones. The sound power emitted by this thermal-acoustic interaction depends on the impedance either side of the combustion zone and on a transfer function defining the response of the flame to sound wave disturbances. If this power exceeds the rate at which energy is dissipated at the cavity boundaries then there is a growth of the internal pressure field and an increase in the radiated sound. Plane wave theory is used to calculate the flame transfer function and adjacent impedances for a simple gas fired tube assembly. The predicted instability frequencies are then compared with experimental data. The results indicate that the flame transfer function plays a dominant role in determining the acoustic stability of the cavity and that insufficient data is available for accurately predicting unsteady flame front behavior.

  16. Blind Alley Aware ACO Routing Algorithm

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Masaya; Otani, Kazuo

    2010-10-01

    The routing problem is applied to various engineering fields. Many researchers study this problem. In this paper, we propose a new routing algorithm which is based on Ant Colony Optimization. The proposed algorithm introduces the tabu search mechanism to escape the blind alley. Thus, the proposed algorithm enables to find the shortest route, even if the map data contains the blind alley. Experiments using map data prove the effectiveness in comparison with Dijkstra algorithm which is the most popular conventional routing algorithm.

  17. Interfaces For Planning Vehicle Routes

    NASA Technical Reports Server (NTRS)

    Feyereisen ,Thea Lynn (Inventor); Misiak, Christopher J. (Inventor); Riley, Victor A. (Inventor)

    2001-01-01

    A system for producing vehicle routes such as aircraft flight plans in the presence of weather and other hazards defines static and moving hazards with polygons drawn on a display containing graphic hazard regions. Different hazard types and intensities are displayed differently. Both lateral and vertical geographic depictions are displayed, and hazards can be displayed temporally as well. Users input information and thresholds for hazards.

  18. Structure of the regular surface layer of Sporosarcina ureae.

    PubMed Central

    Stewart, M; Beveridge, T J

    1980-01-01

    Optical diffraction and computer image processing of electron micrographs were employed to analyze the structure of the regular surface layer of Sporosarcina ureae at high resolution. Negatively stained preparations of regular surface layer fragments showed two types of tetragonal pattern, each having p4 symmetry in projection with a = 12.8 nm. Although the two patterns differed greatly in overall appearance, both had a common pattern of areas of high stain density which we interpret as arising from gaps or holes in the structure. We speculate that these holes may be related to a protective role of the regular surface layer, whereby hostile environmental agents (such as muramidases) larger than about 2 nm would be screened from the underlying layers of the bacterial surface, while the free passage of nutrients and waste products into and out of the cell would still be allowed. Images PMID:7372574

  19. Motion Control of Urea-Powered Biocompatible Hollow Microcapsules.

    PubMed

    Ma, Xing; Wang, Xu; Hahn, Kersten; Sánchez, Samuel

    2016-03-22

    The quest for biocompatible microswimmers powered by compatible fuel and with full motion control over their self-propulsion is a long-standing challenge in the field of active matter and microrobotics. Here, we present an active hybrid microcapsule motor based on Janus hollow mesoporous silica microparticles powered by the biocatalytic decomposition of urea at physiological concentrations. The directional self-propelled motion lasts longer than 10 min with an average velocity of up to 5 body lengths per second. Additionally, we control the velocity of the micromotor by chemically inhibiting and reactivating the enzymatic activity of urease. The incorporation of magnetic material within the Janus structure provides remote magnetic control on the movement direction. Furthermore, the mesoporous/hollow structure can load both small molecules and larger particles up to hundreds of nanometers, making the hybrid micromotor an active and controllable drug delivery microsystem. PMID:26863183

  20. Discovery of nitroaryl urea derivatives with antiproliferative properties.

    PubMed

    Wróbel, Tomasz M; Kiełbus, Michał; Kaczor, Agnieszka A; Kryštof, Vladimír; Karczmarzyk, Zbigniew; Wysocki, Waldemar; Fruziński, Andrzej; Król, Sylwia K; Grabarska, Aneta; Stepulak, Andrzej; Matosiuk, Dariusz

    2016-08-01

    A series of urea derivatives bearing nitroaryl moiety has been synthesized and assayed for their potential antiproliferative activities. Some of the tested compounds displayed activity in RK33 laryngeal cancer cells and TE671 rhabdomyosarcoma cells while being generally less toxic to healthy HSF human fibroblasts cells. One compound was demonstrated to be a moderate CDK2 inhibitor with IC50 = 14.3 µM. Its structure was solved by an X-ray crystallography and molecular modelling was performed to determine structure-activity relationship. Obtained compounds constitute novel structures and generally demonstrated greater cytotoxicity in comparison to cisplatin. This study offers new structural motifs with potential for further development. PMID:26114307

  1. Urea cycle defects and hyperammonemia: effects on functional imaging

    PubMed Central

    Prust, Morgan; Breeden, Andrew; Fricke, Stanley; VanMeter, John

    2012-01-01

    The urea-cycle disorders (UCDs) are a group of congenital enzyme and carrier deficiencies predisposing to hyperammonemia (HA). HA causes changes in the central nervous system (CNS) including alterations of neurotransmitter function, cell volume, and energy deprivation ultimately leading to cerebral edema. Neuropathological findings of UCDs primarily reflect changes in astrocyte morphology. Neurological features accompanying acute HA include changes in behavior and consciousness in the short term, and potential for impairments in memory and executive function as long-term effects. Plasma measures of ammonia and glutamine, although useful for clinical monitoring, prove poor markers of CNS function. Multimodal neuroimaging has potential to investigate impact on cognitive function by interrogating neural networks, connectivity and biochemistry. As neuroimaging methods become increasingly sophisticated, they will play a critical role in clinical monitoring and treatment of metabolic disease. We describe our findings in UCDs; with focus on Ornithine Transcarbamylase deficiency (OTCD) the only X linked UCD. PMID:23149878

  2. Cellulose aerogels from aqueous alkali hydroxide-urea solution.

    PubMed

    Cai, Jie; Kimura, Satoshi; Wada, Masahisa; Kuga, Shigenori; Zhang, Lina

    2008-01-01

    Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2. Their morphology, pore structure, and physical properties were characterized by scanning and transmission electron microscopy, X-ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400-500 m2 g(-1)) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors. PMID:18605678

  3. Smooth Side of 'Route 66'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image was taken by the microscopic imager onboard NASA's Mars Exploration Rover Spirit on sol 99 (April 13, 2004). It is a close-up look at a portion of the rock called 'Route 66,' which was brushed by the rover's rock abrasion tool.

    This image intrigues scientists because it looks very different from the microscopic images taken of other brushed rocks at the Gusev Crater location. The surface of Route 66 is very shiny and specularly reflective, which may indicate a glassy surface, or perhaps a very smooth, discontinuous coating. The unique coating appears mottled and may be multi-layered.

    Other interesting features in this brushed area of Route 66 are the very thin, arc-shaped lines that are visible in the upper left quadrant of the image. An initial hypothesis suggests that these arcs may have been caused by the rock abrasion tool when the instrument made its initial contact with the surface.

    Scientists will use the combined data from the rover's Moessbauer spectrometer and alpha particle X-ray spectrometer along with color versions of this image to try to reach stronger conclusions about what they are seeing and what processes caused the features.

  4. Down-regulation of Hepatic Urea Synthesis by Oxypurines

    PubMed Central

    Nissim, Itzhak; Horyn, Oksana; Nissim, Ilana; Daikhin, Yevgeny; Caldovic, Ljubica; Barcelona, Belen; Cervera, Javier; Tuchman, Mendel; Yudkoff, Marc

    2011-01-01

    We previously reported that isobutylmethylxanthine (IBMX), a derivative of oxypurine, inhibits citrulline synthesis by an as yet unknown mechanism. Here, we demonstrate that IBMX and other oxypurines containing a 2,6-dione group interfere with the binding of glutamate to the active site of N-acetylglutamate synthetase (NAGS), thereby decreasing synthesis of N-acetylglutamate, the obligatory activator of carbamoyl phosphate synthase-1 (CPS1). The result is reduction of citrulline and urea synthesis. Experiments were performed with 15N-labeled substrates, purified hepatic CPS1, and recombinant mouse NAGS as well as isolated mitochondria. We also used isolated hepatocytes to examine the action of various oxypurines on ureagenesis and to assess the ameliorating affect of N-carbamylglutamate and/or l-arginine on NAGS inhibition. Among various oxypurines tested, only IBMX, xanthine, or uric acid significantly increased the apparent Km for glutamate and decreased velocity of NAGS, with little effect on CPS1. The inhibition of NAGS is time- and dose-dependent and leads to decreased formation of the CPS1-N-acetylglutamate complex and consequent inhibition of citrulline and urea synthesis. However, such inhibition was reversed by supplementation with N-carbamylglutamate. The data demonstrate that xanthine and uric acid, both physiologically occurring oxypurines, inhibit the hepatic synthesis of N-acetylglutamate. An important and novel concept emerging from this study is that xanthine and/or uric acid may have a role in the regulation of ureagenesis and, thus, nitrogen homeostasis in normal and disease states. PMID:21540182

  5. 46 CFR 176.110 - Routes permitted.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Routes permitted. 176.110 Section 176.110 Shipping COAST...) INSPECTION AND CERTIFICATION General Provisions; Certificate of Inspection § 176.110 Routes permitted. (a... as a route, is described on the Certificate of Inspection under the major headings...

  6. 46 CFR 176.110 - Routes permitted.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Routes permitted. 176.110 Section 176.110 Shipping COAST...) INSPECTION AND CERTIFICATION Certificate of Inspection § 176.110 Routes permitted. (a) The area of operation... recorded on the vessel's Certificate of Inspection. Each area of operation, referred to as a route,...

  7. 46 CFR 176.110 - Routes permitted.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Routes permitted. 176.110 Section 176.110 Shipping COAST...) INSPECTION AND CERTIFICATION General Provisions; Certificate of Inspection § 176.110 Routes permitted. (a... as a route, is described on the Certificate of Inspection under the major headings...

  8. 7 CFR 1000.3 - Route disposition.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 9 2013-01-01 2013-01-01 false Route disposition. 1000.3 Section 1000.3 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (MARKETING AGREEMENTS... Definitions § 1000.3 Route disposition. Route disposition means a delivery to a retail or wholesale...

  9. 46 CFR 115.110 - Routes permitted.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Routes permitted. 115.110 Section 115.110 Shipping COAST... Provisions; Certificate of Inspection § 115.110 Routes permitted. (a) The area of operation for each vessel...'s Certificate of Inspection. Each area of operation, referred to as a route, is described on...

  10. 46 CFR 176.110 - Routes permitted.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Routes permitted. 176.110 Section 176.110 Shipping COAST...) INSPECTION AND CERTIFICATION Certificate of Inspection § 176.110 Routes permitted. (a) The area of operation... recorded on the vessel's Certificate of Inspection. Each area of operation, referred to as a route,...

  11. 49 CFR 236.796 - Routes, conflicting.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Routes, conflicting. 236.796 Section 236.796 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Routes, conflicting. Two or more routes, opposing, converging or intersecting, over which...

  12. 7 CFR 1000.3 - Route disposition.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 9 2011-01-01 2011-01-01 false Route disposition. 1000.3 Section 1000.3 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Definitions § 1000.3 Route disposition. Route disposition means a delivery to a retail or wholesale...

  13. 7 CFR 1000.3 - Route disposition.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 9 2010-01-01 2009-01-01 true Route disposition. 1000.3 Section 1000.3 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Definitions § 1000.3 Route disposition. Route disposition means a delivery to a retail or wholesale...

  14. 49 CFR 236.379 - Route locking.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Route locking. 236.379 Section 236.379 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... and Tests § 236.379 Route locking. Route locking or other type of switch locking shall be tested...

  15. 49 CFR 236.408 - Route locking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Route locking. 236.408 Section 236.408 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Standards § 236.408 Route locking. Route locking shall be provided where switches are power-operated....

  16. 49 CFR 236.408 - Route locking.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Route locking. 236.408 Section 236.408 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Standards § 236.408 Route locking. Route locking shall be provided where switches are power-operated....

  17. 49 CFR 236.379 - Route locking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Route locking. 236.379 Section 236.379 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... and Tests § 236.379 Route locking. Route locking or other type of switch locking shall be tested...

  18. 46 CFR 176.110 - Routes permitted.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Routes permitted. 176.110 Section 176.110 Shipping COAST...) INSPECTION AND CERTIFICATION General Provisions; Certificate of Inspection § 176.110 Routes permitted. (a... as a route, is described on the Certificate of Inspection under the major headings...

  19. 49 CFR 236.796 - Routes, conflicting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Routes, conflicting. 236.796 Section 236.796 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Routes, conflicting. Two or more routes, opposing, converging or intersecting, over which...

  20. 49 CFR 236.796 - Routes, conflicting.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Routes, conflicting. 236.796 Section 236.796 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Routes, conflicting. Two or more routes, opposing, converging or intersecting, over which...