Sample records for urea combustion route

  1. Synthesis of La{sup 3+} doped nanocrystalline ceria powder by urea-formaldehyde gel combustion route

    SciTech Connect

    Biswas, M. [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)] [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India); Bandyopadhyay, S., E-mail: sbando@cgcri.res.in [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Nano LC synthesized by gel combustion, using urea-formaldehyde fuel for first time. Black-Right-Pointing-Pointer Largely single crystals were produced in average range of 20-30 nm. Black-Right-Pointing-Pointer La{sup 3+} doping increases cell dimension linearly. Black-Right-Pointing-Pointer La{sup 3+} doping introduces ionic point defects but does not change electronic band gap. Black-Right-Pointing-Pointer Presence of Ce{sup 3+} indicates that this synthesis route produces reactive powders. -- Abstract: Nanocrystalline ceria powders doped with various concentrations of lanthanum oxide have been prepared following gel combustion route using for the first time urea-formaldehyde as fuel. The synthesized products were characterized by XRD, FESEM, TEM, PL and UV-vis spectroscopy. Peak positions of XRD were refined and the lattice parameters were obtained by applying Cohen's method. Unit cell parameter increases with concentration of La{sup 3+} ion and the variation is consistently linear. XRD calculations showed the dependence of crystallite size on dopant concentrations at lower level. TEM observation revealed unagglomerated particles to be single crystals in the average range of 20-30 nm. Band gap of the La{sup 3+} doped ceria materials does not change with doping. Spectroscopic experiments proved the existence of Ce{sup 3+} in the formed powder.

  2. New synthetic route of polyoxometalate-based hybrids in choline chloride\\/urea eutectic media

    Microsoft Academic Search

    Shi-Ming Wang; Yun-Wu Li; Xiao-Jia Feng; Yang-Guang Li; En-Bo Wang

    2010-01-01

    The deep eutectic solvents synthetic method was initially explored as a facile synthesis route to prepare new polyoxometalate (POM)-based hybrids. Such a method can not only avoid poor solubility, lower yields and the potential explosion, but also act as a new type of noxious, convenient and environmental friendly organic reagents. Using the choline chloride\\/urea eutectic mixture as the deep eutectic

  3. Pulsatile urea excretion in the ureagenic toadfish Opsanus beta: an analysis of rates and routes

    PubMed

    Wood; Hopkins; Hogstrand; Walsh

    1995-01-01

    This study focused on the rates and routes of urea-N and ammonia-N excretion in the ureagenic toadfish and on the possibility that urea-N excretion occurs in pulses. Experimental approaches included the following: confinement in small individual containers with automated hourly sampling of water to follow temporal excretion patterns; divided chambers to separate excretion from the anterior and posterior parts of the fish; collection of urine and rectal fluid via chronic indwelling catheters; and gavage with [14C]-labelled polyethylene glycol 4000 to detect regurgitation of gastrointestinal fluids. When a standardized 'crowding' pre-treatment was employed to induce ureotelic behaviour, the fish exhibited significant elevations in the activity of glutamine synthetase in liver, kidney and gills, elevated plasma and bile urea-N levels, but unchanged ammonia-N and urea-N levels in most other body fluids. Unencumbered ureotelic fish confined in small containers excreted 82 % of their waste-N as urea-N and 18 % as ammonia-N; almost all (94 %) of this urea-N excretion occurred in a single pulse of less than 3 h duration about once every 24 h. This daily pulse did not occur by regurgitation of gut fluids, by excretion through prominent pores behind the pectoral fins or by discharge of rectal fluid or urine. Intestinal and urinary excretion accounted for less than 10 % of whole-body urea-N excretion and a negligible fraction of ammonia-N excretion. Pulsatile urea-N excretion occurred at the head end across the gills and/or body surface. Ammonia-N excretion, which was not pulsatile, also occurred largely through the head end. However, once the toadfish had been placed in divided chambers, urea-N excretion became continuous rather than pulsatile, and ammonia-N excretion increased greatly. A severe stress response was indicated by high levels of plasma cortisol, and the skin, which lacks scales, became a significant route of both ammonia-N and urea-N excretion. We speculate that the normal adaptive significance is that ureotelism facilitates cryptic behaviour, allowing the toadfish to virtually eliminate N-waste excretion during long periods while it remains sheltered in burrows. However, during severe stress, the effects of extremely high cortisol levels overwhelm the ammonia and urea retention mechanisms, and both substances leak across the general body surface. PMID:9319637

  4. Influence of double promotion on HDS catalysts prepared by urea-matrix combustion synthesis

    Microsoft Academic Search

    Sergio L. González-Cortés; Tian-Cun Xiao; Tsung-Wu Lin; Malcolm L. H. Green

    2006-01-01

    The stringent environmental regulations in the US, Japan and Europe are requiring significant improvement in the quality of transportation fuels. A new strategy based on urea-matrix combustion method for the synthesis of alumina-supported molybdate-based mixed oxides (i.e., bimetallic and trimetallic oxides) has been applied. This permits to control the alumina–mixed oxide interaction and therefore the HDS catalytic behaviour. The oxidic

  5. Structure and microstructure of combustion synthesized MgO nanoparticles and nanocrystalline MgO thin films synthesized by solution growth route

    Microsoft Academic Search

    K. Venkateswara Rao; C. S. Sunandana

    2008-01-01

    In this work we describe the synthesis, micro structure (XRD, SEM, AFM) of magnesium oxide nanoparticles and magnesium oxide\\u000a thin films synthesized by urea-based combustion method and solution growth route using magnesium nitrate as the source of\\u000a Mg. We used fuel-to-oxidizer ratio (?) as a control parameter to investigate how lattice parameter, particle size, and micro\\u000a strain vary with ? = 0.25–2

  6. Synthesis and Characterization of Nanosized Dy-Doped of Ceria Developed by Microwave Assisted Combustion Route

    Microsoft Academic Search

    S. A. Acharya; K. Singh; S. S. Bhoga

    2010-01-01

    Nanosized Ce1-xDyxO2-x\\/2 (DDC, x = 0.05—0.25 mol%) were synthesized by combustion routes induced by microwaves (MS) and compared with the same composition prepared by conventional (CS) method. The conventional and microwave sintering routes were also used to consolidate the pellets. The samples were characterized by X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and AC impedance spectroscopy.

  7. Dielectric properties of Bismuth Titanate (Bi4Ti3O12) synthesized using solution combustion route

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    Ferroelectric Bismuth Titanate (Bi4Ti3O12) was prepared by solution combustion route with glycine as fuel. The single phase Bismuth Titanate was obtained after calcination at 800 °C, which was confirmed with the help of X-ray diffraction studies and EDS analysis. SEM micrographs of the calcined powders show agglomerated particles, which is typical of combustion synthesis. Behavior of dielectric constant and dielectric loss as a function of temperature of as prepared sample are reported here. Ferroelectric to paraelectric phase transition occurs at the temperature Tc?650 °C. Impedance studies were made in the frequency range from 1 KHz to 1 MHz. The semicircles observed in the complex impedance diagrams indicate deviation from the Debye behavior. Activation energy of the sample around Tc is found to be ?0.35 eV and below Tc is ?0.13 eV, which was calculated using the Arrhenius plots.

  8. 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

  9. Nanostructures of the binary nitrides, BN, TiN, and NbN, prepared by the urea-route

    SciTech Connect

    Gomathi, A. [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India); Rao, C.N.R. [Chemistry and Physics of Materials Unit, CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)]. E-mail: cnrrao@jncasr.ac.in

    2006-05-25

    By heating mixtures of H{sub 3}BO{sub 3}, TiCl{sub 4}, and NbCl{sub 5} with urea in 1:6 molar ratios in the 900-1000 deg. C range, nanoparticles of BN, TiN, and NbN have been obtained, respectively. The nanoparticles are crystalline and have been characterized by electron microscopy and other techniques. By carrying out the urea reaction over Au islands deposited on Si substrates, nanowires of TiN could be obtained.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 15.65 nm 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. 5 h with pseudo first order rate constants of 5.85 × 10-3 and 8.38 × 10-3 min-1, respectively.

  11. 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.

  12. Correlation between structural and electrical properties of Mg 1?2 x Zn x Ni x Al 2O 4 ( x = 0.0–0.5) ceramic nanomaterials synthesized by a urea assisted microwave combustion method

    Microsoft Academic Search

    Muhammad Javed Iqbal; Bushra Ismail

    2010-01-01

    A urea assisted microwave combustion method was used to synthesize Mg1?2xNixZnxAl2O4 (x=0.0–0.5) ceramic materials. X-ray diffraction (XRD) analysis confirmed the formation of a single spinel phase with an average Scherrer crystallite size of in the range 24–51nm. The chemical composition of the synthesized compounds was determined by energy dispersive X-ray fluorescence (ED-XRF). The synthesized materials show crystalline morphology as evidenced

  13. An investigation of urea decomposition and selective non-catalytic removal of nitric oxide with urea 

    E-print Network

    Park, Yong Hun

    2004-09-30

    The use of urea (NH2CONH2) to remove nitric oxide (NO) from exhaust streams was investigated using a laboratory laminar-flow reactor. The experiments used a number of gas compositions to simulate different combustion exhaust ...

  14. Structural and optical properties of ZnO: K synthesized by sol-gel auto-combustion route

    NASA Astrophysics Data System (ADS)

    Krithiga, R.; Sankar, S.; Subhashree, G.; Bharathi, R. Niruban

    2015-06-01

    The structural and optical behavior of ZnO and ZnO doped with K synthesized by solution combustion route is reported in this article. The XRD patterns confirm the substitution of K atoms into ZnO lattice. There are no secondary peaks observed in the XRD patterns. The band gap of the K doped samples show a red shift on comparison with the bandgap of ZnO. The photoluminescence spectral study discloses the quenching behavior of UV emission and the aggrandizing blue emission when K content increases. The rich presence of defects is confirmed from the optical analysis and a practical mechanism, involving Zni for the origin of the blue emission in ZnO is discussed here.

  15. Combustion

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    The process whereby a substance is combined with oxygen with the production of heat. Burning is a familiar example of this process. The energy required to propel chemical rockets is provided by the combustion of fuel with an oxidant at very high temperatures. A common oxidant is liquid oxygen (often denoted by LOX). Others include hydrogen peroxide and nitrogen tetroxide....

  16. 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.

  17. 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. [Prof. C.N.R. Rao Centre for Advanced Materials, Tumkur University, Tumkur 572 103 (India); Department of Physics, Acharya Institute of Technology, Bangalore 560 107 (India); Nagabhushana, H., E-mail: bhushanvlc@gmail.com [Prof. C.N.R. Rao Centre for Advanced Materials, Tumkur University, Tumkur 572 103 (India); Sudheerkumar, K.H. [Department of Chemistry, B.M.S. Institute of Technology, Bangalore 560 064 (India); Dhananjaya, N. [Department of Physics, B.M.S. Institute of Technology, Bangalore 560 064 (India); Sharma, S.C. [Vice chancellor, Chhattisgarh Swamy Vivekananda Technical University, North Park Avenue, Sector – 8, Bhilai, Chhattisgarh 490 009 (India); Kavyashree, D. [Department of Physics, Channabasaveshwara Institute of Technology, Gubbi 572 216 (India); Shivakumara, C. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012 (India); Nagabhushana, B.M. [Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054 (India)

    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 ?-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.

  18. Combustion Study of Synergism of Urea-Sodium Polymetaphosphate on the Flame-Retardancy of a Cotton Fabric Monitored by TG

    Microsoft Academic Search

    Seyed Morteza Mostashari; Seyede Zahra Mostashari

    2009-01-01

    The synergism of sodium polymetaphosphate- urea on the flammability of a cotton fabric (woven, plain 144 g\\/m, the number of yarns 21 per 10 mm) has been investigated in this study. After impregnation with suitable individual additives and\\/or their appropriate admixed formulation onto the fabrics, their flammability has been assessed by using the described procedure. In this study the flame spread tests

  19. 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.

  20. EPR and photoluminescence studies of ZnO:Mn nanophosphors prepared by solution combustion route.

    PubMed

    Reddy, A Jagannatha; Kokila, M K; Nagabhushana, H; Rao, J L; Nagabhushana, B M; Shivakumara, C; Chakradhar, R P S

    2011-08-01

    Nanocrystalline ZnO:Mn (0.1 mol%) phosphors have been successfully prepared by self propagating, gas producing solution combustion method. The powder X-ray diffraction of as-formed ZnO:Mn sample shows, hexagonal wurtzite phase with particle size of ?40 nm. For Mn doped ZnO, the lattice parameters and volume of unit cell (a=3.23065 ?, c=5.27563 ? and V=47.684 (?)(3)) are found to be greater than that of undoped ZnO (a=3.19993 ?, c=5.22546 ? and V=46.336 (?)(3)). The SEM micrographs reveal that besides the spherical crystals, the powders also contained several voids and pores. The TEM photograph also shows the particles are approximately spherical in nature. The FTIR spectrum shows two peaks at ?3428 and 1598 cm(-1) which are attributed to O-H stretching and H-O-H bending vibration. The PL spectra of ZnO:Mn indicate a strong green emission peak at 526 nm and a weak red emission at 636 nm corresponding to (4)T(1)?(6)A(1) transition of Mn(2+) ions. The EPR spectrum exhibits fine structure transition which will be split into six hyperfine components due to (55)Mn hyperfine coupling giving rise to all 30 allowed transitions. From EPR spectra the spin-Hamiltonian parameters have been evaluated and discussed. The magnitude of the hyperfine splitting (A) constant indicates that there exists a moderately covalent bonding between the Mn(2+) ions and the surrounding ligands. The number of spins participating in resonance (N), its paramagnetic susceptibility (?) have been evaluated. PMID:21531616

  1. Investigation of structural and luminescence properties of Ho3+ doped YAlO3 nanophosphors synthesized through solution combustion route

    NASA Astrophysics Data System (ADS)

    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:Ho3+ (1-5 mol%) 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 (?30 nm). The direct energy band gap (Eg) values estimated from Tauc's relation were found to be in the range 5.76-5.99 eV. Photoluminescence (PL) studies show green (540 and 548 nm) and red (645 and 742 nm) emissions upon excited at 452 nm wavelength. The emission peaks at ?742 and 645 nm was associated with the transitions of 5F4 ? 5I7 and 5F5 ? 5I8 respectively. The higher energy bands located at 540 and 548 nm were associated with 5F4, 5S2 ? 5I8 transitions. Thermoluminescence (TL) studies of ?-irradiated YAlO3:Ho3+ (1-5 mol%) show two glow peaks at 223 and 325 °C recorded at a heating rate of 2.5 °C s-1. The 223 °C glow peak follow linear behavior up to 1 kGy and after that, it showed sub-linearity. Up to 1 kGy, 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.

  2. 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 ?-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

  3. Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)

    PubMed Central

    Summer, Heike; Grämer, René; Dröge, Peter

    2009-01-01

    Urea PAGE or denaturing urea polyacrylamide gel electrophoresis employs 6-8 M urea, which denatures secondary DNA or RNA structures and is used for their separation in a polyacrylamide gel matrix based on the molecular weight. Fragments between 2 to 500 bases, with length differences as small as a single nucleotide, can be separated using this method1. The migration of the sample is dependent on the chosen acrylamide concentration. A higher percentage of polyacrylamide resolves lower molecular weight fragments. The combination of urea and temperatures of 45-55 °C during the gel run allows for the separation of unstructured DNA or RNA molecules. In general this method is required to analyze or purify single stranded DNA or RNA fragments, such as synthesized or labeled oligonucleotides or products from enzymatic cleavage reactions. In this video article we show how to prepare and run the denaturing urea polyacrylamide gels. Technical tips are included, in addition to the original protocol 1,2. PMID:19865070

  4. Urea Cycle Disease Overview

    MedlinePLUS

    ... be delayed for months or years. Early in life, infants with urea cycle disorders develop toxic levels of ammonia build-up ... for the presence of a UCD. Amino acid analysis can be used to diagnose a specific urea cycle disorder. The amino acid arginine may be reduced ...

  5. 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., E-mail: vtv_chem@rediffmail.com [Walchand College of Arts and Science, Solapur 413 006 (India); Achary, S.N. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Meena, S.S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    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.

  6. ROUTE DEVIATION ROUTE: Red Route

    E-print Network

    Stuart, Steven J.

    ROUTE DEVIATION NOTICE: ROUTE: Red Route WHEN: Friday, Sept. 5th @ 4:00pm-8:00pm LOCATION: First Friday Parade Event College Avenue & Hwy 93 RE-ROUTED DIRECTIONS: The Red to Central bus ­ Will travelMillan Road. The Red to Clemson bus ­ Will travel its normal route from Central to Clemson University

  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 ?m 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. Detection of Interstellar Urea

    NASA Astrophysics Data System (ADS)

    Kuo, Hsin-Lun; Remijan, Anthony J.; Snyder, Lewis E.; Looney, Leslie W.; Friedel, Douglas N.; Lovas, Francis J.; McCall, Benjamin J.; Hollis, Jan M.

    2010-11-01

    Urea, a molecule discovered in human urine by H. M. Rouelle in 1773, has a significant role in prebiotic chemistry. Previous BIMA observations have suggested that interstellar urea [(NH2)2CO] is a compact hot core molecule such as other large molecules (e.g. methyl formate and acetic acid). We have conducted an extensive search for urea toward the high mass hot molecular core Sgr B2(N-LMH) using BIMA, CARMA and the IRAM 30 m. Because the spectral lines of heavy molecules like urea tend to be weak and hot cores display lines from a wide range of molecules, it is necessary to detect a number of urea lines and apply sophisticated statistical tests before having confidence in an identification. The 1 mm resolution of CARMA enables favorable coupling of the source size and synthesized beam size, which was found to be essential for the detection of weak signals. We have detected a total of 65 spectral lines (32 molecular transitions and 33 unidentified transitions), most of which are narrower than the SEST survey (Nummelin et al. 1998) due to the small synthesized beam (2.5" x 2") of CARMA. It significantly resolves out the contamination by extended emission and reveals the eight weak urea lines that were previously blended with nearby transitions. Our analysis indicates that these lines are likely to be urea since the resulting observed line frequencies are coincident with a set of overlapping connecting urea lines, and the observed line intensities are consistent with the expected line strengths of urea. In addition, we have developed a new statistical approach to examine the spatial correlation between the observed lines by applying the Student's t test to the high resolution channel maps obtained from CARMA. The t test shows consistent spatial distributions from all eight candidate lines, suggesting a common molecular origin, urea. Our t test method could have a broad impact on the next generation of arrays, such as ALMA, because the new arrays will require a method to systematically determine the credibility of detections of weaker signals from new and larger interstellar molecules.

  9. Nanocrystalline pirochromite spinel through solution combustion synthesis

    Microsoft Academic Search

    M. J. de Andrade; M. D. Lima; R. Bonadiman; C. P. Bergmann

    2006-01-01

    The production of magnesium–chromium oxides by solution combustion synthesis was investigated using glycine and urea for the first time. Ammonium dichromate, urea\\/glycine and ammonium nitrate aqueous solutions were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and

  10. EPR investigation on synthesis of Lithium zinc vanadate using sol-gel-combustion route and its optical properties

    NASA Astrophysics Data System (ADS)

    Pathak, Nimai; Gupta, Santosh K.; Prince, Angelina; Kadam, R. M.; Natarajan, V.

    2014-01-01

    The present work describes the synthesis of Lithium zinc vanadate (LiZnVO4) nanophosphor prepared by sol-gel-combustion method and its optical properties. The prepared sample was characterized by X-ray diffraction, SEM, electron paramagnetic resonance and photoluminescence spectroscopy. X-ray diffraction study showed the formation of pure LiZnVO4 at 600 °C with distorted phenacite structure. SEM investigation revealed that the phosphor powder has spherical morphology with particle size of about 100-200 nm. EPR study showed the change of coordination sphere around vanadium from axially distorted octahedral symmetry to tetrahedral geometry along with the change in oxidation state of vanadium ion from +4 to +5. The emission spectrum showed a broad emission at 543 nm with ?ex = 375 nm. The decay time obtained on mono-exponential fitting was 8.3 ?s. The colour coordinates of the system were evaluated using CIE index diagram to be 0.31 and 0.41, which suggest that the prepared material is a potential green emitting phosphor. A bright green colour emission was also observed directly from this phosphor upon excitation with an UV source.

  11. Physical and magnetic properties of highly aluminum doped strontium ferrite nanoparticles prepared by auto-combustion route

    NASA Astrophysics Data System (ADS)

    Luo, H.; Rai, B. K.; Mishra, S. R.; Nguyen, V. V.; Liu, J. P.

    2012-08-01

    Highly Al3+ ion doped nanocrystalline SrFe12-xAlxO19 (0?x?12), were prepared by the auto-combustion method and heat treated in air at 1100 °C for 12 h. The phase identification of the powders performed using x-ray diffraction show presence of high-purity hexaferrite phase and absence of any secondary phases. With Al3+ doping, the lattice parameters decrease due to smaller Al3+ ion replacing Fe3+ ions. Morphological analysis performed using transmission electron microscope show growth of needle shaped ferrites with high aspect ratio at Al3+ ion content exceeding x?2. Al3+ substitution modifies saturation magnetization (MS) and coercivity (HC). The room temperature MS values continuously reduced while HC value increased to a maximum value of 18,100 Oe at x=4, which is an unprecedented increase (˜321%) in the coercivity as compared to pure Sr-Ferrite. However, at higher Al3+ content x>4, a decline in magnetization and coercivity has been observed. The magnetic results indicate that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation.

  12. Chemiresistor urea sensor

    DOEpatents

    Glass, Robert S. (Livermore, CA)

    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. Molecular evolution of urea amidolyase and urea carboxylase in fungi

    PubMed Central

    2011-01-01

    Background Urea amidolyase breaks down urea into ammonia and carbon dioxide in a two-step process, while another enzyme, urease, does this in a one step-process. Urea amidolyase has been found only in some fungal species among eukaryotes. It contains two major domains: the amidase and urea carboxylase domains. A shorter form of urea amidolyase is known as urea carboxylase and has no amidase domain. Eukaryotic urea carboxylase has been found only in several fungal species and green algae. In order to elucidate the evolutionary origin of urea amidolyase and urea carboxylase, we studied the distribution of urea amidolyase, urea carboxylase, as well as other proteins including urease, across kingdoms. Results Among the 64 fungal species we examined, only those in two Ascomycota classes (Sordariomycetes and Saccharomycetes) had the urea amidolyase sequences. Urea carboxylase was found in many but not all of the species in the phylum Basidiomycota and in the subphylum Pezizomycotina (phylum Ascomycota). It was completely absent from the class Saccharomycetes (phylum Ascomycota; subphylum Saccharomycotina). Four Sordariomycetes species we examined had both the urea carboxylase and the urea amidolyase sequences. Phylogenetic analysis showed that these two enzymes appeared to have gone through independent evolution since their bacterial origin. The amidase domain and the urea carboxylase domain sequences from fungal urea amidolyases clustered strongly together with the amidase and urea carboxylase sequences, respectively, from a small number of beta- and gammaproteobacteria. On the other hand, fungal urea carboxylase proteins clustered together with another copy of urea carboxylases distributed broadly among bacteria. The urease proteins were found in all the fungal species examined except for those of the subphylum Saccharomycotina. Conclusions We conclude that the urea amidolyase genes currently found only in fungi are the results of a horizontal gene transfer event from beta-, gamma-, or related species of proteobacteria. The event took place before the divergence of the subphyla Pezizomycotina and Saccharomycotina but after the divergence of the subphylum Taphrinomycotina. Urea carboxylase genes currently found in fungi and other limited organisms were also likely derived from another ancestral gene in bacteria. Our study presented another important example showing plastic and opportunistic genome evolution in bacteria and fungi and their evolutionary interplay. PMID:21447149

  14. 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.

  15. Solution combustion synthesis of CeO{sub 2}-CeAlO{sub 3} nano-composites by mixture-of-fuels approach

    SciTech Connect

    Aruna, S.T. [Surface Engineering Division, National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560017 (India); Kini, N.S. [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)], E-mail: nagesh.kini@gmail.com; Rajam, K.S. [Surface Engineering Division, National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560017 (India)

    2009-04-02

    Nano-composites of CeO{sub 2}-CeAlO{sub 3} are synthesised by solution combustion method employing (a) urea and (b) a mixture of urea and glycine as fuels with corresponding metal nitrates. The as-prepared powders are all nano-sized (5-30 nm) and the same is confirmed by broadening of the X-ray diffraction peaks and transmission electron microscopy. A starting composition of Ce:Al in the atomic ratio 4:6 gives rise to different phases depending on the fuel being used for combustion. When urea alone is used as fuel, nano-crystalline CeO{sub 2} phase is formed with Al{sub 2}O{sub 3} being in the amorphous state. When the mixture of fuels is used, a mixture of nano-sized CeO{sub 2} and CeAlO{sub 3} phases is obtained. However, upon sintering at 1400 deg. C in air, the stable phases CeO{sub 2} and {alpha}-Al{sub 2}O{sub 3} are formed in both the cases. Combustion synthesis using mixture-of-fuels is proposed to be a route to stabilise low oxidation compounds such as CeAlO{sub 3}.

  16. Combustion synthesis: a new route for repair of gas turbine components—principles and metallurgical structure in the NiAl\\/RBD61\\/superalloy junction

    Microsoft Academic Search

    C Pascal; R. M Marin-Ayral; J. C Tédenac; C Merlet

    2003-01-01

    A new technique for repairing turbine blade materials based on combustion synthesis is described in this article. This process uses a local internal generation of heat provided by the NiAl combustion synthesis in order to rebuild damaged turbine components. In this study, a nickel base braze was inserted between a substrate of nickel base superalloy and a powders compact (Ni+Al).

  17. Toxicology of urea formaldehyde and polyurethane foam insulation.

    PubMed

    Harris, J C; Rumack, B H; Aldrich, F D

    1981-01-16

    Two types of foam insulation are in wide use. Urea formaldehyde foam is a relatively inexpensive, easily installed, and efficient insulation. Toxicity from this insulation is related to release of free formaldehyde into the home. Mild to incapacitating symptoms have been reported in occupants of urea formaldehyde-insulated homes. Airborne formaldehyde levels frequently have exceeded standards set for occupational exposure. The long-term consequences of such exposure are unknown. Because of publicity over the toxicity of urea formaldehyde foam, many physicians and patients have confused urea formaldehyde and polyurethane foam. Unlike urea formaldehyde, polyurethane foam is fully cured before construction. Toxicity occurs only during manufacture and curing. To date, there have been no reports to our knowledge of toxicity in occupants of polyurethane-insulated homes. However, toxicity caused by pyrolysis products may occur during combustion in homes insulated with either type of insulation. This report details 48 patients in whom complete medical data were obtained out of the first 100 patients contacting the Rocky Mountain Poison Center. PMID:7452848

  18. Urea dewaxing of naphthene oils

    SciTech Connect

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

    1985-03-12

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

  19. Structural and magnetic properties of Ni0.8Co0.2-2xCuxMnxFe2O4 spinel ferrites prepared via solution combustion route

    NASA Astrophysics Data System (ADS)

    Jadhav, Pragati; Patankar, Ketaki; Mathe, Vikas; Tarwal, N. L.; Jang, Jae-Hung; Puri, Vijaya

    2015-07-01

    Ni0.8Co0.2-2xCuxMnxFe2O4 ferrites (with x=0.01, 0.03, 0.05, 0.07 and 0.09) were prepared using solution combustion route. X-ray diffraction analysis indicates the presence of the characteristic most intense (311) peak along with other reflections confirming the formation of spinel ferrite in each composition. SEM images show formation of porous structured agglomerates with submicron sized grains. The microstrain measurement of ferrite series is non-linear with variation in dopant concentration for a given magnetic field. The magnetic hysteresis at room temperature indicates the ferrimagnetic behavior of synthesized ferrite system. The magnetic and mechanical properties were seen to be comparatively higher for x=0.07 composition. The presence of sexset in Mössbauer spectra confirms the ferrimagnetic nature of all the ferrites.

  20. Regulation of urea uptake in Pseudomonas aeruginosa

    Microsoft Academic Search

    Thomas Jahns

    1992-01-01

    The energy-dependent urea permease was studied in two strains ofPseudomonas aeruginosa, measuring the uptake (transport and metabolism) of14C-urea. In both strains urea uptakein vivo and urease activityin vitro differed significantly with respect to kinetic parameters, temperature and pH dependence and response to metabolic inhibitors. Ammonium strongly interfered both with the expression of the urea uptake system and its activity. The

  1. Effect of prilled urea and modified urea materials on yield and quality of geranium ( Pelargonium graveolens L. Her.)

    Microsoft Academic Search

    B. R. Rajeswara Rao; Kailash Singh; A. K. Bhattacharya; A. A. Naqvi

    1990-01-01

    Two field experiments were conducted to study the effect of prilled urea, neem cake coated urea, dicyandiamide treated urea and urea supergranules applied to a perennial aromatic herb, geranium (Pelargonium graveolens L. Her'.) grown on a sandy loam soil. Application of nitrogen increased the biomass and essential oil yields. Neem cake coated urea significantly increased the yields over prilled urea.

  2. Structure and properties of urea-plasticized starch films with different urea contents.

    PubMed

    Wang, Jia-Li; Cheng, Fei; Zhu, Pu-Xin

    2014-01-30

    Films of thermoplastic starch (TPS) plasticized with different contents of urea were prepared by using a solution casting method. Scanning electron microscopy, X-ray diffraction and IR spectroscopy were used to characterize structures of the TPS films, respectively. Water vapor sorption isotherms and tensile properties of the films were determined. TPS films showed more smooth and transparent in appearance and less B-type crystallinity than the starch film without urea. The effect of urea content on the structure and behavior of the TPS film could be divided in three stages: (1) below urea 10% where urea interacted with starch via H-bonding and the films showed an antiplasticization effect, (2) from urea 10% to 30% where an apparent plasticization effect appeared on the starch because of free urea molecules as the effective plasticizer, and (3) a macroscopic phase separation occurred due to supersaturation of urea when urea content was more than 30%. PMID:24299881

  3. 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.

  4. Urea biosensor for hemodialysis monitoring

    DOEpatents

    Glass, Robert S. (Livermore, CA)

    1999-01-01

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

  5. Transcriptional Responses of Uropathogenic Escherichia coli to Increased Environmental Osmolality Caused by Salt or Urea

    PubMed Central

    Withman, Benjamin; Gunasekera, Thusitha S.; Beesetty, Pavani; Agans, Richard

    2013-01-01

    Uropathogenic Escherichia coli (UPEC) is the most common causative agent of urinary tract infections in humans. The majority of urinary infections develop via ascending route through the urethra, where bacterial cells come in contact with human urine prior to reaching the bladder or kidneys. Since urine contains significant amounts of inorganic ions and urea, it imposes osmotic and denaturing stresses on bacterial cells. In this study, we determined the transcriptional adaptive responses of UPEC strain CFT073 to the presence of 0.3 M NaCl or 0.6 M urea in the growth medium. The cell responses to these two osmolytes were drastically different. Although most of the genes of the osmotically inducible regulon were overexpressed in medium with salt, urea failed to stimulate osmotic stress response. At the same time, UPEC colonization genes encoding type 1 and F1C fimbriae and capsule biosynthesis were transcriptionally induced in the presence of urea but did not respond to increased salt concentration. We speculate that urea can potentially be sensed by uropathogenic bacteria to initiate infection program. In addition, several molecular chaperone genes were overexpressed in the presence of urea, whereas adding NaCl to the medium led to an upregulation of a number of anaerobic metabolism pathways. PMID:23090957

  6. Some factors in liquid supplements affecting urea toxicity 

    E-print Network

    McClain, William Ray

    1979-01-01

    Experiment 1: Site of Rumen Sampling Experiment 2: Determination of Lethal Levels of Urea in Molasses-Urea or Water-Urea Solutions Sheep Work Cattle Work Experiment 3: Effect of Repetitive Doses of Urea on Toxicity Pooled Data of Experiments 2 and 3... DOSE OF UREA (SHEEP) COMPOSITION OF MAINTENANCE RATION (CATTLE). TREATMENT AND LEVEL OF INITIAL DOSE OF UREA (CATTLE) ~Pa e 15 18 19 TREATMENT, TIME INTERVAL, AND LEVEL OF UREA DRENCHED IN REPETITIVE DOSAGE EXPERIMENT 21 EFFECT OF THREE...

  7. Urea transformation of wetland microbial communities.

    PubMed

    Thorén, Ann-Karin

    2007-02-01

    Transformation of urea to ammonium is an important link in the nitrogen cycle in soil and water. Although microbial nitrogen transformations, such as nitrification and denitrification, are well studied in freshwater sediment and epiphytic biofilm in shallow waters, information about urea transformation in these environments is scarce. In this study, urea transformation of sedimentary, planktonic, and epiphytic microbial communities was quantified and urea transformation of epiphytic biofilms associated with three different common wetland macrophyte species is compared. The microbial communities were collected from a constructed wetland in October 2002 and urea transformation was quantified in the laboratory at in situ temperature (12 degrees C) with the use of the 14C-urea tracer method, which measures the release of 14CO2 as a direct result of urease activity. It was found that the urea transformation was 100 times higher in sediment (12-22 mmol urea-N m(-2) day(-1)) compared with the epiphytic activity on the surfaces of the submerged plant Elodea canadensis (0.1-0.2 mmol urea-N m(-2) day(-1)). The epiphytic activity of leaves of Typha latifolia was lower (0.001-0.03 mmol urea-N m(-2) day(-1)), while urea transformation was negligible in the water column and on the submerged leaves of the emergent plant Phragmites australis. However, because this wetland was dominated by dense beds of the submerged macrophyte E. canadensis, this plant provided a large surface area for epiphytic microbial activity-in the range of 23-33 m2 of plant surfaces per square meter of wetland. Thus, in the wetland system scale at the existing plant distribution and density, the submerged plant community had the potential to transform 2-7 mmol urea-N m(-2) day(-1) and was in the same magnitude as the urea transformation in the sediment. PMID:17268879

  8. Optical and EPR studies of Gd2Zr2O7 phosphors prepared via solution combustion method

    NASA Astrophysics Data System (ADS)

    Singh, Vijay; Sivaramaiah, Gobburu; Rao, J. L.; Hwan Kim, Sang

    2013-05-01

    Phosphor powder of Gd2Zr2O7 has been prepared by the urea combustion route. Phase evolution of the synthesized powder is determined by X-ray diffraction (XRD) technique. The structural environment between the Gd3+ and the zirconium oxide lattice has been investigated using electron paramagnetic resonance (EPR), diffuse reflectance and photoluminescence (PL) studies. The EPR spectrum of Gd2Zr2O7 phosphor exhibits a broad and intense signal at g?2.0 and this has been attributed to Gd3+ ions in octahedral symmetry with strong dipolar interactions between Gd3+ ions. The intensity of the spectrum increases with temperature lowering from 296 to 110 K following the usual Boltzmann law. The g value is invariant with temperature variation. The diffuse reflectance spectrum exhibits two sharp and weak bands characteristic of Gd3+ ions in octahedral symmetry. The photoluminescence spectrum exhibits several bands characteristic of Gd3+ ions in octahedral symmetry.

  9. Urea Transformation of Wetland Microbial Communities

    Microsoft Academic Search

    Ann-Karin Thorén

    2007-01-01

    Transformation of urea to ammonium is an important link in the nitrogen cycle in soil and water. Although microbial nitrogen\\u000a transformations, such as nitrification and denitrification, are well studied in freshwater sediment and epiphytic biofilm\\u000a in shallow waters, information about urea transformation in these environments is scarce. In this study, urea transformation\\u000a of sedimentary, planktonic, and epiphytic microbial communities was

  10. Factors influencing urea space estimates in goats

    Microsoft Academic Search

    A. Asmare; L. J. Dawson; R. Puchala; T. A. Gipson; M. Villaquiran; I. Tovar-Luna; G. Animut; T. Ngwa; T. Sahlu; R. C. Merkel; A. L. Goetsch

    2007-01-01

    Female Alpine goats, 18 approximately 17 months of age (yearling) and 18 approximately 5-month-old (growing), were used in an experiment to determine effects of animal age, urea dose (100, 130, and 160mg\\/kg BW), and time without feed and water (shrink; 0, 16, and 24h) on urea space (US) estimates. A 20% (w\\/v) urea solution was infused into a jugular vein,

  11. Low Temperature Urea Decomposition and SCR Performance

    Microsoft Academic Search

    C. Scott Sluder; John M. E. Storey; Samuel A. Lewis; Linda A. Lewis

    Urea-SCR systems are potentially a highly-effective means of NOX reduction for light-duty diesel vehicles. However, use of urea-SCR technologies at low temperatures presents unique technical challenges. This study was undertaken to provide more knowledge about low temperature urea decomposition and the resulting effects on SCR performance. Data are presented for experiments using two SCR catalysts of differing size with a

  12. Nicotine, acetanilide and urea multi-level 2 N-abundance reference materials for continuous-flow

    E-print Network

    Nicotine, acetanilide and urea multi-level 2 H-, 13 C- and 15 N-abundance reference materials the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i nicotines for oxidative C, N gas chroma- tography-combustion-isotope ratio mass-spectrometry (GC

  13. Substituted Ureas. Methods of Synthesis and Applications

    NASA Astrophysics Data System (ADS)

    Vishnyakova, T. P.; Golubeva, I. A.; Glebova, E. V.

    1985-03-01

    Systematic data on the method of synthesis of ureas by the interaction of compounds containing the amino-group with organic isocyanates, of amines and alkyl halides with alkali metal cyanates, and of primary and secondary amines with phosgene, carbon dioxide, urea, or nitrourea and by the carbonylation of amines are presented. The reactions involving the alkylation of urea and its interaction with various compounds containing functional groups are considered. The advantages and disadvantages of various methods are noted. The principal and practical applications of substituted ureas, including their applications as additives to organic materials, are discussed. The bibliography includes 314 references.

  14. Increasing urea-N efficiency in transplanted lowland rice by urea solution band placement

    Microsoft Academic Search

    P. Devasenapathy; S. P. Palaniappan

    1996-01-01

    Alternative N fertiliser management strategies are needed to increase N-use efficiency in wetland rice (Oryza sativa L.). In the wet season of 1993–1994, field experiments were conducted to evaluate the band placement of urea solution in comparison with broadcast prilled urea, neem-coated urea, or point-placement of urea supergranules. Both grain yield and N-use efficiency were higher with band placement of

  15. Spray combustion

    SciTech Connect

    Chigier, N. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering

    1995-12-31

    A survey is presented of the most recent developments in the field of spray combustion. Topics discussed are: physical processes of atomization; drop clusters; droplet arrays and streams; ideal sprays; cloud combustion; theoretical models of spray diffusion flames; spray diagnostic techniques; measurement of drop temperature; and spray combustion measurements. 67 refs.

  16. Simulating Combustion

    Microsoft Academic Search

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

    2006-01-01

    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

  17. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Urea nitrogen test system. 862.1770 Section 862...Chemistry Test Systems § 862.1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to...

  18. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Urea nitrogen test system. 862.1770 Section 862...Chemistry Test Systems § 862.1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to...

  19. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Urea nitrogen test system. 862.1770 Section 862...Chemistry Test Systems § 862.1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to...

  20. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Urea nitrogen test system. 862.1770 Section 862...Chemistry Test Systems § 862.1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to...

  1. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Urea nitrogen test system. 862.1770 Section 862...Chemistry Test Systems § 862.1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to...

  2. Routing Protocols Hierarchical Routing

    E-print Network

    Campbell, Andrew T.

    -AS routing protocol Gateway router · Direct link to router in another AS 3b 1d 3a 1c 2a AS3 AS1 AS2 1a 2c 2b for internal dests ­ Inter-AS & Intra-As sets entries for external dests #12;2 3b 1d 3a 1c 2a AS3 AS1 AS2 1a 2c ­ Router should forward packet towards one of the gateway routers, but which one? AS3 1. to propagate

  3. 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.

  4. 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.

  5. Rapid dissolution of cellulose in LiOH/urea and NaOH/urea aqueous solutions.

    PubMed

    Cai, Jie; Zhang, Lina

    2005-06-24

    Rapid dissolution of cellulose in LiOH/urea and NaOH/urea aqueous solutions was studied systematically. The dissolution behavior and solubility of cellulose were evaluated by using (13)C NMR, optical microscopy, wide-angle X-ray diffraction (WAXD), FT-IR spectroscopy, DSC, and viscometry. The experiment results revealed that cellulose having viscosity-average molecular weight ((overline) M eta) of 11.4 x 104 and 37.2 x 104 could be dissolved, respectively, in 7% NaOH/12% urea and 4.2% LiOH/12% urea aqueous solutions pre-cooled to -10 degrees C within 2 min, whereas all of them could not be dissolved in KOH/urea aqueous solution. The dissolution power of the solvent systems was in the order of LiOH/urea > NaOH/urea > KOH/urea aqueous solution. The results from DSC and (13)C NMR indicated that LiOH/urea and NaOH/urea aqueous solutions as non-derivatizing solvents broke the intra- and inter-molecular hydrogen bonding of cellulose and prevented the approach toward each other of the cellulose molecules, leading to the good dispersion of cellulose to form an actual solution. PMID:15954076

  6. Method for reducing nitrogen oxides in combustion effluents

    DOEpatents

    Zauderer, Bert (Merion Station, PA)

    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. A Novel Combustion Synthesis Preparation of CuO/ZnO/ZrO2/Pd for Oxidative Hydrogen Production from Methanol

    E-print Network

    Mukasyan, Alexander

    A Novel Combustion Synthesis Preparation of CuO/ZnO/ZrO2/Pd for Oxidative Hydrogen Production from pre- pared via three combustion synthesis routes including volume combustion, impregnated substrate combustion, and so-called second wave impregnation combustion methods. These catalysts were characterized via

  8. Combustion Group Group members

    E-print Network

    Wang, Wei

    Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy § New combustion and energy-conversion concepts #12;Introduction Combustion research thrusts Combustion Dynamics and Flame-Stabilization Research objectives § Obtain fundamental understanding of combustion

  9. Managing Urea-Containing Fertilizers1 Larry G. Bundy2

    E-print Network

    Balser, Teri C.

    of the reactions urea undergoes when added to soils. Urea is hydrolyzed or broken down to ammonia and carbon of the urea was hydrolyzed within 2 days after application at 50o F and over 80% was broken down within 4 days was hydrolyzed within 2 days at a temperature of 79o F. Alternatively, cold temperatures slow down urea

  10. Combustion chamber for internal combustion engine

    Microsoft Academic Search

    Isida

    1988-01-01

    This patent describes a combustion chamber for an internal combustion engine, comprising: a main combustion chamber hollowed out of the top of a piston; a subsidiary combustion chamber hollowed out of the piston top, the subsidiary combustion chamber communicating with and disposed in side by side relationship to the main combustion chamber; a fuel injection nozzle located generally between the

  11. Detection of Interstellar Urea with Carma

    NASA Astrophysics Data System (ADS)

    Kuo, H.-L.; Snyder, L. E.; Friedel, D. N.; Looney, L. W.; McCall, B. J.; Remijan, A. J.; Lovas, F. J.; Hollis, J. M.

    2010-06-01

    Urea, a molecule discovered in human urine by H. M. Rouelle in 1773, has a significant role in prebiotic chemistry. Previous BIMA observations have suggested that interstellar urea [(NH_2)_2CO] is a compact hot core molecule such as other large molecules, e.g. methyl formate and acetic acid (2009, 64th OSU Symposium On Molecular Spectroscopy, WI05). We have conducted an extensive search for urea toward the high mass hot molecular core Sgr B2(N-LMH) using CARMA and the IRAM 30 m. Because the spectral lines of heavy molecules like urea tend to be weak and hot cores display lines from a wide range of molecules, a major problem in identifying urea lines is confusion with lines of other molecules. Therefore, it is necessary to detect a number of urea lines and apply sophisticated statistical tests before having confidence in an identification. The 1 mm resolution of CARMA enables favorable coupling of the source size and synthesized beam size, which was found to be essential for the detection of weak signals. The 2.5^"×2^" synthesized beam of CARMA significantly resolves out the contamination by extended emission and reveals the eight weak urea lines that were previously blended with nearby transitions. Our analysis indicates that these lines are likely to be urea since the resulting observed line frequencies are coincident with a set of overlapping connecting urea lines, and the observed line intensities are consistent with the expected line strengths of urea. In addition, we have developed a new statistical approach to examine the spatial correlation between the observed lines by applying the Student T-test to the high resolution channel maps obtained from CARMA. The T-test shows similar spatial distributions from all eight candidate lines, suggesting a common molecular origin, urea. Our T-test method could have a broad impact on the next generation of arrays, such as ALMA, because the new arrays will require a method to systematically determine the credibility of detections of weaker signals from new and larger interstellar molecules.

  12. Reversible denaturation of cyclosporin synthetase by urea

    Microsoft Academic Search

    Joachim Dittmann; François Vaillant; Horst Kleinkauf; Alfons Lawen

    1996-01-01

    The reversible denaturation of the multifunctional polypeptide, cyclosporin synthetase, by urea was analyzed. It is possible to discriminate between at least two stages of enzyme denaturation. While at low urea concentration (up to 0.8 M) cyclosporin A formation is inhibited, synthesis of the diketopiperazine cyclo-(d-alanyl-N-methylleucyl), a molecule representing a partial sequence of cyclosporin A is still detectable. At higher concentrations

  13. The fractionation of lanolin with urea

    Microsoft Academic Search

    Abner Eisner; Wilfred R. Noble; John T. Scanlan

    1959-01-01

    Summary  A fractionation of lanolin was effected by contacting lanolin with urea in the presence of methyl alcohol. About 6–8% of the\\u000a lanolin formed a urea adduct which, upon decomposition, yielded a hard, nontacky wax fraction. In addition to the wax fraction,\\u000a a fluid fraction and a sticky semi-solid were also obtained. The latter two fractions were obtained by the solvent

  14. Nanostructured zinc oxide film for urea sensor

    Microsoft Academic Search

    Azahar Ali; Anees A. Ansari; Ajeet Kaushik; Pratima R. Solanki; A. Barik; M. K. Pandey; B. D. Malhotra

    2009-01-01

    Nanostructured zinc oxide (Nano-ZnO) film has been electrochemically deposited onto indium-tin-oxide (ITO) coated glass plate to co-immobilized urease (Urs) and glutamate dehydrogenase (GLDH) for urea detection. The observed reflection planes corresponding to wurtzite ZnO nanoparticles (~25nm) in XRD diffraction pattern and UV-visible absorption band at 338nm reveal the formation of Nano-ZnO. Urs-GLDH\\/Nano-ZnO\\/ITO bioelectrode shows high sensitivity for urea detection within

  15. Hepatic urea biosynthesis in the euryhaline elasmobranch Carcharhinus leucas.

    PubMed

    Anderson, W Gary; Good, Jonathan P; Pillans, Richard D; Hazon, Neil; Franklin, Craig E

    2005-10-01

    Plasma urea levels and hepatic urea production in the euryhaline bull shark, Carcharhinus leucas, acclimated to freshwater and seawater environments were measured. It was found that plasma urea concentration increased with salinity and that this increase was, in part, the result of a significant increase in hepatic production of urea. This study provides direct evidence that hepatic production of urea plays an important role in the osmoregulatory strategy of C. leucas. PMID:16161010

  16. 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

  17. Nanocrystalline perovskites for catalytic combustion and oxygen separation

    E-print Network

    Sangar, Neeraj, 1974-

    2002-01-01

    Nanocrystalline perovskites (Lal-xAMnl-yByO3) were successfully synthesized with higher surface area and smaller grain size by chemical co-precipitation compared to solid-state and complexation/combustion synthesis routes. ...

  18. Combustion Control

    E-print Network

    Riccardi, R. C.

    1984-01-01

    . Because each furnace is designed and operated differently, careful evaluation is required. Look at several options. The performance and efficiency of a combustion system depends upon several major factors. They are: 1) Fuel to air ratio control, 2) Fuel...

  19. An excess electron bound to urea. III. The urea dimer as an electron trap Piotr Skurski

    E-print Network

    Simons, Jack

    Simonsa) Henry Eyring Center for Theoretical Chemistry, Department of Chemistry, University of Utah, SaltAn excess electron bound to urea. III. The urea dimer as an electron trap Piotr Skurski Henry Eyring Center for Theoretical Chemistry Department of Chemistry, University of Utah, Salt Lake City, Utah

  20. 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]...

  1. A Method for Estimating Uptake and Produdion Rates for Urea in Seawater using Urea and

    E-print Network

    Hansell, Dennis

    estimatinguptakeand productionrates for urea in seawater using [j4"N]ureaand ["Clurea. Can. J.Fish. Aquat. Sci. 46: 19. Several models have been developed that attempt to describe the pathways sf the nitrogennutrientsmost have not been horougMy tested. Urea is an endproduct of hekrotrophic nitrogen metabolism thatcanbe

  2. Combustion synthesis

    Microsoft Academic Search

    Kashinath C Patil; Singanahally T Aruna; Sambandan Ekambaram

    1997-01-01

    Many innovative self-propagating high-temperature synthesis (SHS) techniques such as filtration, combustion, the centrifugal thermite process, field activated combustion, solid-state metathesis, flame synthesis and simultaneous SHS and densification have been developed for the synthesis of ‘advanced materials’. A novel gas producing self-propagating process initiated at low temperature using redox compounds and mixtures has been used for the preparation of fine particle

  3. Cycle Route

    NSDL National Science Digital Library

    2013-11-07

    If you're an avid cyclist or just a neophyte, you'll find this rather unique app most useful. Cycle Route can assist those with a passion for cycling plan out their route based on topography, elevation, main roads, and a range of other variables. Visitors just need to enter their origin and destination and they will be all set. The app returns a range of routes that users can take advantage of and there's also a mobile version as well. This version is compatible with all operating systems.

  4. Streamflow Routing

    NSDL National Science Digital Library

    2014-09-14

    This module offers a thorough introduction to streamflow routing methods and applications in the river forecasting process. Through the use of rich illustrations, animations, and interactions, this module explains key routing concepts, flow characteristics, and tools with a primary focus on hydrologic routing methods. As a foundation topic for the Basic Hydrologic Science Course, this module may be taken on its own or used as a supporting topic to provide factual scientific information to students as they complete the case-based forecasting modules.

  5. 69 FR 58957 - Solid Urea From Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan, Turkmenistan, Ukraine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2004-10-01

    ...Urea From Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan, Turkmenistan...urea from Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan, Turkmenistan...urea from Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan,...

  6. Combustion chamber for internal combustion engines

    Microsoft Academic Search

    Kawamura

    1988-01-01

    A combustion chamber for internal combustion engines, of the type including means for producing swirl within the combustion chamber is described comprising: a combustion chamber provided in the head portion of a piston in the form of a cavity recessed in the axial direction of the piston; fuel injection nozzle means disposed in the combustion chamber and positioned eccentrically with

  7. Combustion chamber for internal combustion engines

    Microsoft Academic Search

    N. Yanagisawa; Y. Sato

    1989-01-01

    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

  8. Combustion Group Group members

    E-print Network

    Wang, Wei

    Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy 2014 #12;Combustion Group Combustion Physics and Modeling Pollutants, Emissions, and Soot Formation Thermoacoustics and Combustion Dynamics Research focus § Examine mechanisms responsible for flame stabilization

  9. The incidence of urea cycle disorders.

    PubMed

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

    2013-01-01

    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 6million 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

  10. 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.

  11. Modelling of flame temperature of solution combustion synthesis of nanocrystalline calcium hydroxyapatite material and its parametric optimization

    Microsoft Academic Search

    Samir K. Ghosh; Sukhomay Pal; Sujit K. Roy; Surjya K. Pal; Debabrata Basu

    2010-01-01

    Hydroxyapatite (HAp), an important bio-ceramic was successfully synthesized by combustion in the aqueous system containing\\u000a calcium nitrate-di-ammonium hydrogen orthophosphate-urea. The combustion flame temperature of solution combustion reaction\\u000a depends on various process parameters, and it plays a significant role in the phase formation, phase stability and physical\\u000a characteristics of calcium hydroxyapatite powder. In this work, an attempt has been made to

  12. 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

  13. 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...

  14. Aldehyde-containing urea-absorbing polysaccharides

    NASA Technical Reports Server (NTRS)

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

    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.

  15. 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.

  16. Combustion Control 

    E-print Network

    Riccardi, R. C.

    1984-01-01

    . There are many opportunities to improve combustion system efficiency. However, there is no single correct way to maximize efficiency. Each technique must be evaluated and compared before a final selection is made. You have a choice of many energy saving systems...

  17. 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. ...

  18. Homogeneous precipitation of alumina precursors via enzymatic decomposition of urea

    Microsoft Academic Search

    Hidero Unuma; Shinichi Kato; Toshitaka Ota; Minoru Takahashi

    1998-01-01

    A modified homogeneous precipitation technique involving enzymatic decomposition of urea was proposed and was applied to the synthesis of alumina precursors. Spherical aluminum hydroxide aggregates were prepared at 298 K from aqueous solutions containing aluminum sulfate, urea and urease. In contrast to the conventional technique involving thermally induced decomposition of urea, the resultant aggregates were amorphous with no trace of

  19. Hemodialysis urea rebound: The effect of increasing dialysis efficiency

    Microsoft Academic Search

    David M. Spiegel; Penny L. Baker; Susan Babcock; Robert Contiguglia; Melvyn Klein

    1995-01-01

    Urea rebound has been documented to occur after hemodialysis, but the magnitude and causes are not clearly defined. In this study we evaluated the effect of high-flux hemodialysis on urea rebound and Kt\\/V. Blood urea nitrogen samples were obtained before, immediately after, and 30 minutes after hemodialysis in 49 patients. Rebound was evaluated with respect to dialysis efficiency, dialysis treatment

  20. Characterization of urea transport in Bufo arenarum oocytes.

    PubMed

    Silberstein, Claudia; Zotta, Elsa; Ripoche, Pierre; Ibarra, Cristina

    2003-07-01

    Xenopus laevis oocytes have been extensively used for expression cloning, structure/function relationships, and regulation analysis of transporter proteins. Urea transporters have been expressed in Xenopus oocytes and their properties have been described. In order to establish an alternative system in which urea transporters could be efficiently expressed and studied, we determined the urea transport properties of ovarian oocytes from Bufo arenarum, a toad species common in Argentina. Bufo oocytes presented a high urea permeability of 22.3 x 10(-6) cm/s, which was significantly inhibited by the incubation with phloretin. The urea uptake in these oocytes was also inhibited by mercurial reagents, and high-affinity urea analogues. The urea uptake was not sodium dependent. The activation energy was 3.2 Kcal/mol, suggesting that urea movement across membrane oocytes may be through a facilitated urea transporter. In contrast, Bufo oocytes showed a low permeability for mannitol and glycerol. From these results, we propose that one or several specific urea transporters are present in ovarian oocytes from Bufo arenarum. Therefore, these oocytes cannot be used in expression studies of foreign urea transporters. The importance of Bufo urea transporter is not known but could be implicated in osmotic regulation during the laying of eggs in water. PMID:12840834

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

    SciTech Connect

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

    2007-02-01

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

  2. Ammonia volatilization losses from prilled urea, urea supergranules (USG) and coated USG in rice fields

    Microsoft Academic Search

    K. Sudhakara; R. Prasad

    1986-01-01

    Summary  About 8.4 per cent of applied nitrogen was lost as ammonia during a week after application when prilled urea was broadcast\\u000a or banded and incorporated in soil 20 days after sowing of rice. Ammonia volatilization was reduced to 3.3 per cent when urea\\u000a supergranules (USG) were used. Coating of USG with DCD or neem cake showed no advantage. Ammonia volatilization

  3. Compound internal combustion and external combustion engine

    Microsoft Academic Search

    Marttila

    1986-01-01

    A compound engine is described comprising at least one internal combustion cylinder having an inlet and an outlet and one external combustion cylinder having an inlet and an outlet, each of the combustion cylinders having a reciprocable piston therein coupled to a common utilization output shaft, heat exchanger means associated with the external combustion cylinder for transferring heat to a

  4. Supersonic combustion

    NASA Astrophysics Data System (ADS)

    Gamba, Mirko

    2013-11-01

    Combustion in the supersonic regime presents several challenges over what the low-speed counterpart admits. Here we will review some of these challenges, and we will describe some of the key features of one of the canonical flow fields in supersonic combustion: the reacting transverse jet in a supersonic crossflow (JISCF). From a practical standpoint, the key challenges that limit our control of this combustion regime are fast mixing, robust flame holding and stability. In turn, these aspects are controlled by the complex effects introduced by chemistry, compressibility, shocks and shock/flow interactions, turbulence and the underlying coupling among them. Some of their properties will be discussed here. In particular, for a JISCF in a Mach 2.4 high enthalpy crossflow, the reaction zone structure, its dependence on near-wall events, boundary layer, and shock/boundary layer interaction will be described. We will demonstrate the paramount importance of the coupling between boundary layers and compressibility to provide mechanisms for flame stabilization at the wall. Mixing characteristics, overall structure, and the link to global parameters (momentum flux, velocity and density ratios) that characterize the JISCF, and possibly free shear supersonic flows in general, will also be highlighted from non-reacting experiments. Combustion in the supersonic regime presents several challenges over what the low-speed counterpart admits. Here we will review some of these challenges, and we will describe some of the key features of one of the canonical flow fields in supersonic combustion: the reacting transverse jet in a supersonic crossflow (JISCF). From a practical standpoint, the key challenges that limit our control of this combustion regime are fast mixing, robust flame holding and stability. In turn, these aspects are controlled by the complex effects introduced by chemistry, compressibility, shocks and shock/flow interactions, turbulence and the underlying coupling among them. Some of their properties will be discussed here. In particular, for a JISCF in a Mach 2.4 high enthalpy crossflow, the reaction zone structure, its dependence on near-wall events, boundary layer, and shock/boundary layer interaction will be described. We will demonstrate the paramount importance of the coupling between boundary layers and compressibility to provide mechanisms for flame stabilization at the wall. Mixing characteristics, overall structure, and the link to global parameters (momentum flux, velocity and density ratios) that characterize the JISCF, and possibly free shear supersonic flows in general, will also be highlighted from non-reacting experiments. Sponsored by DoE PSAAP at Stanford University.

  5. The Action of Certain Acid Reagents on the Substituted Ureas

    E-print Network

    Brewster, Ray Q.

    1915-01-01

    aniline and methyl phenyl urea chloride with pyridine - 6 Di-phenyl ethyl thio urea and phosgene with pyridine 7 Para mono brom di-phenyl thio urea and methyl phenyl urea chloride - 8 Di-phenyl thio urea and chlor formic ethyl ester with pyridine 9...°C. to 150°C. for an hour. A gas was given off which darkened lead acetate paper. The reaction product, a green resinous mass, on distillation with steam, gave phenyl mustard oil and a trace of methyl aniline. The gummy product remaining...

  6. Advanced Combustion

    SciTech Connect

    Holcomb, Gordon R. [NETL

    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).

  7. Combustion synthesis of fine-particle metal aluminates

    Microsoft Academic Search

    J. J. Kingsley; K. Suresh; K. C. Patil

    1990-01-01

    Fine-particle metal aluminates, MAl2O4 where M=Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu and Zn as well as 3CaO · Al2O3 (C3A), CaAl12O19 (CA6) and MgCeAl11O19 have been prepared by the combustion of mixtures of the respective metal nitrates (oxidizers) and urea or carbohydrazide (fuels) at 500 or 350‡ C, respectively, over a time of 5 min. The solid combustion

  8. Computation and simulation of the structural characteristics of the kidney urea transporter and behaviors of urea transport.

    PubMed

    Wang, Zhe; Yu, Tao; Sang, Jian-Ping; Zou, Xian-Wu; Yan, Chengfei; Zou, Xiaoqin

    2015-04-23

    Urea transporters are a family of membrane proteins that transport urea molecules across cell membranes and play important roles in a variety of physiological processes. Although the crystal structure of bacterial urea channel dvUT has been solved, there lacks an understanding of the dynamics of urea transport in dvUT. In this study, by using molecular dynamics simulations, Monte Carlo methods, and the adaptive biasing force approach, we built the equilibrium structure of dvUT, calculated the variation in the free energy of urea, determined the urea-binding sites of dvUT, gained insight into the microscopic process of urea transport, and studied the water permeability in dvUT including the analysis of a water chain in the pore. The strategy used in this work can be applied to studying transport behaviors of other membrane proteins. PMID:25781365

  9. Enzymatic Characterization of a Prokaryotic Urea Carboxylase

    Microsoft Academic Search

    Takeshi Kanamori; Norihisa Kanou; Haruyuki Atomi; Tadayuki Imanaka

    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

  10. Route 66

    NSDL National Science Digital Library

    Even though Route 66 hasn't formally existed in twenty years, it is part of America's love affair with cars, travel, and getting lost. This excellent travel itinerary created by the National Park Service's Heritage Education Services "aids the public to visit the historic places that recall those images and experiences that are reminders of our past and evidence of the influence of the automobile." The homepage features historic images of old motel facades and long-gone department stores along Route 66, mixed in with images of the Route today. To get a sense of the road's genealogy, visitors would do well to look through the illustrated "Essays". Here they can learn about the road's origins, its rise, decline, and renaissance over the past 85 years. Moving on, users can click on the "List of Sites" area to read about featured sites in each of the eight states that the road passes through. Finally, the "Learn More" area is a glorious cornucopia of related websites that tell the story of the places and people associated with the road, including Dell Rhea's Chicken Basket in Hinsdale, Illinois and the Seligman Historic District in Arizona.

  11. Dichloridobis(thio-urea-?S)nickel(II).

    PubMed

    Zouihri, Hafid

    2012-03-01

    The title complex, [NiCl(2)(CH(4)N(2)S)(2)], has been synthesized from the previously reported (diamino-methyl-idene)sulfonium chloride-thio-urea (3/2) salt [Zouihri (2012b ?). Acta Cryst. E68, o257]. The Ni(II) ion is coordinated in a distorted tetra-hedral geometry by two mol-ecules of thio-urea [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 thio-urea ligands is 6.36?(15)°. The crystal structure is characterized by intra- and inter-molecular 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

  12. Dichloridobis(thio­urea-?S)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. IMPROVEMENT IN PROPERTIES OF UREA BY PHOSPHOGYPSUM COATING

    Microsoft Academic Search

    Manish Vashishtha; Papireddy Dongara; Dhananjay Singh

    Particle coating is becoming increasingly important in fertilizer, pharmaceutical and food industries. The demand for coating granular fertilizers with minerals is increasing. Urea is coated with PhosphoGypsum, neem oil, polymeric suspensions and micronutrients like sulfer, zinc etc.Coating of PhosphoGypsum on urea fertilizer is a important application of coating process . Coating of urea particles is done to increase nitrogen use

  14. Use of urease inhibitors and urea fertilizers on winter wheat

    Microsoft Academic Search

    AJ Schlegel; DW Nelson; LE Sommers

    1987-01-01

    Phosphoroamide urease inhibitors were evaluated for their ability to increase grain protein and yield of winter wheat (Triticum aestivum L.) when added to surfaceapplied urea-based fertilizers. Six urease inhibitors [trichloroethyl phosphorodiamidate, diethyl phosphoric triamide, dimethyl phosphoric triamide, N-(diaminophosphinyl)-cyclohexylamine, N-benzyl-N-methyl phosphoric triamide, and phenylphosphorodiamide] were evaluated. Nitrogen treatments were urea prills, urea solution, and ureaammonium nitrate (UAN) solution broadcast and UAN

  15. Macrocyclic ureas: A simple building block for supramolecular structures

    Microsoft Academic Search

    Linda S. Shimizu

    There is great interest in developing new building blocks that predictably self-assemble into well-defined supramolecular structures. We have utilized the self-assembly of simple, rigid macrocyclic bis-ureas to reliably form columnar structures. Larger macrocycles assemble into porous crystals containing channels of predetermined dimensions. The self-assembly of these monomers is directed by the formation of strong urea-urea hydrogen bond and by the

  16. Urea and ethanolamine as a mixed plasticizer for thermoplastic starch

    Microsoft Academic Search

    X. F. Ma; J. G. Yu; J. J. Wan

    2006-01-01

    Mixtures of urea and ethanolamine were used as plasticizers for preparing thermoplastic starch (TPS) in a single-screw extruder. The interaction between urea\\/ethanolamine and starch was investigated using Fourier Transform Infrared (FT-IR). Glass transition temperature of TPS was tested by Differential scanning calorimetry (DSC). Both FT-IR and DSC proved that the mixture of urea and ethanolamine could form more stable and

  17. The Physiology and Evolution of Urea Transport in Fishes

    Microsoft Academic Search

    M. D. McDonald; C. P. Smith; P. J. Walsh

    2006-01-01

    This review summarizes what is currently known about urea transporters in fishes in the context of their physiology and evolution\\u000a within the vertebrates. The existence of urea transporters has been investigated in red blood cells and hepatocytes of fish\\u000a as well as in renal and branchial cells. Little is known about urea transport in red blood cells and hepatocytes, in

  18. Urea and glutamine synthesis: Environmental influences on nitrogen excretion

    Microsoft Academic Search

    Paul M. Anderson

    2001-01-01

    The focus of this chapter is on recent developments in our understanding of the expression of the urea cycle and the roles of glutamine synthetase (GSase) and glutamine-dependent carbamoyl-phosphate synthetase (CPSase III) in ammonia detoxification in fish, with emphasis on teleosts. Marine elasmobranch fishes have an active urea cycle, synthesizing and retaining urea for the purpose of osmoregulation. Well-characterized biochemical

  19. Simple Ant Routing Algorithm

    Microsoft Academic Search

    Fernando Correia; T. Vazao

    2008-01-01

    A mobile ad-hoc network has limited and scarce resources and thus routing protocols in such environments must be kept as simple as possible. This paper presents a MANET routing protocol, inspired in insect societies' biological models, the simple ant routing algorithm (SARA), which provides a simple and efficient routing solution. SARA uses a controlled neighbour broadcast route discovery procedure, aimed

  20. Combustion system for internal combustion engines

    Microsoft Academic Search

    I. Matsuno; H. Yamazoe

    1981-01-01

    A combustion system for internal combustion engines having an exhaust gas recirculating system which is operable by a lean airfuel mixture without aggravation of the combustion. The piston of the engine has a sub-piston projecting on the top thereof and the cylinder head is formed with a recess into which the sub-piston is insertable at a position near the top

  1. Combustion device of an internal combustion engine

    Microsoft Academic Search

    Okuma

    1986-01-01

    A combustion device of an internal combustion engine is described which consists of: a cylinder, a cylinder head closing one end of the cylinder; and a piston reciprocable in the cylinder; the head and piston having stepped portions adapted to interfit as the piston approaches the head so as to define a compression chamber, and a combustion chamber of greater

  2. Reciprocating internal combustion engine with continuous combustion

    Microsoft Academic Search

    Vogelsang

    1976-01-01

    The design of a reciprocating internal combustion engine having a continuous combustion is given. The combustion chamber must be connected with the cylinders of the engine by suitable transfer ports for supplying the gaseous medium to the cylinders and for discharging the burned mixture. In order to obtain a high efficiency, the transfer ports should be as short as possible.

  3. Urea in the management of advanced malignancies (preliminary report).

    PubMed

    Gandhi, G M; Anasuya, S R; Kawathekar, P; Bhaskarmall; Krishnamurthy, K R

    1977-01-01

    Twenty cases of advanced (Stage III) cancer of the cervix were treated with intratumour injection of 40% urea solution and local application of 50% urea ointment. Sixty percent of these patients had beneficial effect and in 25% of the patients there was minimal response. Patients with multiple secondaries in liver had very good symptomatic relief with oral urea. Urea therapy is a simple, cheap, and safe method of treating advanced stages of cancer, where very little can be done by the accepted lines of treatment such as surgery or radiotherapy. This line of treatment can be practiced even in a consulting room or primary health center. PMID:266635

  4. Surface modification of vesicles with methylol urea

    Microsoft Academic Search

    Jin-Chul Kim; Jong-Duk Kim

    2002-01-01

    Surface-modified vesicles were prepared using N-[3-(dimethylamino)propyl]-octadecanamide and stearic acid as bilayer-forming lipids, and N-methylol urea-dodecylamine conjugated (MU-DOA) as a surface modifier. The conjugation of MU to DOA was confirmed by FTIR\\u000a spectra. MU-DOA was incorporated into the vesicles by co-homogenization of the lipids and MU-DOA, and the incorporated MU-DOA\\u000a was then reacted with MU in aqueous bulk phase through a

  5. Combustion of coffee husks

    Microsoft Academic Search

    M Saenger; E.-U Hartge; J Werther; T Ogada; Z Siagi

    2001-01-01

    Combustion mechanisms of two types of coffee husks have been studied using single particle combustion techniques as well as combustion in a pilot-scale fluidised bed facility (FBC), 150 mm in diameter and 9 m high. Through measurements of weight-loss and particle temperatures, the processes of drying, devolatilisation and combustion of coffee husks were studied. Axial temperature profiles in the FBC

  6. Internal combustion engine

    Microsoft Academic Search

    Lowther

    1980-01-01

    An internal combustion engine method and apparatus are described wherein most or all of the air compression required for combustion is done outside of the internal combustion engine and out of heat exchange contact with the combustion chamber. The engine includes direct regeneration of exhaust heat and the compressor includes means for varying the compression ratio thereof in response to

  7. 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.

  8. Combustion fundamentals and applications

    SciTech Connect

    Not Available

    1987-01-01

    These proceedings collect papers given at a meeting on combustion kinetics. Topics include: Effects of piston bowl geometry on combustion characteristics of diesel engines, bipropellant combustion, coal char reactivity, sulfur and nitrogen-oxide emissions, mineral matter in coal and wood, methane, liquid fuels, and carbon particle combustion.

  9. Nitrous oxide emissions from anhydrous ammonia, urea, and polymer-coated urea in illinois cornfields.

    PubMed

    Fernández, Fabián G; Terry, Richard E; Coronel, Eric G

    2015-03-01

    The use of alternative N sources relative to conventional ones could mitigate soil-surface NO emissions. Our objective was to evaluate the effect of anhydrous ammonia (AA), urea, and polymer-coated urea (ESN) on NO emissions for continuous corn ( L.) production. Corn received 110 kg N ha in 2009 and 180 kg N ha in 2010 and 2011. Soil NO fluxes were measured one to three times per week early in the growing season and less frequently later, using vented non-steady state closed chambers and a gas chromatograph. Regardless of N source, NO emissions were largest immediately after substantial (>20 mm) rains, dropping to background levels thereafter. Averaged across N sources, 2.85% of the applied N was lost as NO. Emission differences for treatments only occurred in 2010, the year with maximum NO production. In the 2010 growing season, cumulative emissions (in kg NO-N ha) were lowest for the check (2.21), followed by ESN (9.77), and ESN was lower than urea (14.07) and AA (16.89). Emissions in 2010 based on unit of corn yield produced followed a similar pattern, and NO emissions calculated as percent of applied N showed that AA losses were 1.9 times greater than ESN. Across years, relative to AA, ESN reduced NO emissions, emissions per unit of corn yield, and emissions per unit of N applied, whereas urea produced intermediate values. The study indicates that, under high N loss potential (wet and warm conditions), ESN could reduce NO emissions more that urea and AA. PMID:26023960

  10. Coal combustion science

    SciTech Connect

    Hardesty, D.R. (ed.); 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.

  11. 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.

  12. 64 FR 48360 - Final Result of Expedited Sunset Review: Solid Urea from Romania

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-09-03

    ...Expedited Sunset Review: Solid Urea from Romania AGENCY: Import Administration, International...Expedited Sunset Review on Solid Urea from Romania...antidumping duty order on solid urea from Romania pursuant to section 751(c) of the...

  13. 64 FR 62653 - Continuation of Antidumping Duty Orders: Solid Urea From Belarus, Estonia, Lithuania, Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    1999-11-17

    ...Urea From Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan, Turkmenistan...urea from Belarus, Estonia, Lithuania, Romania, Russia, Tajikistan, Turkmenistan...antidumping duty order on solid urea from Romania would be likely to lead to...

  14. 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

    ...A-823-801] Solid Urea From the Russian Federation and Ukraine: Continuation of...orders on solid urea from the Russian Federation (Russia) and Ukraine would likely lead...See Solid Urea From the Russian Federation and Ukraine: Final...

  15. Nonhepatic hyperammonemic encephalopathy due to undiagnosed urea cycle disorder

    PubMed Central

    Nugent, Kenneth

    2015-01-01

    Ornithine transcarbamoylase deficiency is the most common inherited urea cycle disorder. In adults, its phenotypes are diverse. In asymptomatic patients with late presentations, symptom onset is often associated with a precipitating factor. We present a case of a woman with urea cycle disorder diagnosed after an acute peptic ulcer bleed and fasting. PMID:26130895

  16. Nitrification and Anammox with Urea as the Energy Source

    Microsoft Academic Search

    A. Olav Sliekers; Suzanne Haaijer; Markus Schmid; Harry Harhangi; Karin Verwegen; J. Gijs Kuenen; Mike S. M. Jetten

    2004-01-01

    Urea is present in many ecosystems and can be used as an energy source by chemolithotrophic aerobic ammonia oxidizing bacteria (AOB). Thus the utilization of urea in comparison to ammonia, by AOB as well as anaerobic ammonia oxidizing (Anammox) bacteria was investigated, using enrichments cultures, inoculated with activated sludge, and molecular ecological methods. In batch enrichment cultures grown with ammonia

  17. Evidence for Urea-Induced Hypometabolism in Isolated

    E-print Network

    Lee Jr., Richard E.

    to reduced metabolism of hibernating wood frogs (Rana sylvatica). Urea accumulation during dormancy (Malaclemys terrapin), and Gastropoda (Anguispira alternata), and one amphibian species (R. pipiens) that does treatment. However, _VO2 of organs from R. pipiens, the one species tested that does not accumulate urea

  18. 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...

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

    PubMed Central

    Kokubo, Hironori; Rösgen, Jörg; 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

  20. Efficiency and future potential of urea for temperate grassland

    Microsoft Academic Search

    C. J. Watson; R. J. Stevens; M. K. Garrett; C. H. McMurray

    1990-01-01

    The efficacy of urea as a grassland fertilizer under temperate conditions has been assessed in a wide variety of comparisons with either ammonium nitrate or calcium ammonium nitrate (CAN). Data from the British Isles have been evaluated and compared to results mainly from continental Europe.In general urea is as good as CAN early in the growing season, but less-effective in

  1. Fate and efficiency of urea fertilizer in wetland rice soil

    Microsoft Academic Search

    Sakorn Phongpan; Sorasith Vacharotayan; Kikuo Kumazawa

    1988-01-01

    Pot experiments conducted with a non-acid marine soil (Typic Tropaquepts) from the Central Region of Thailand showed that in general, urea, DAP, MAP, and urea supergranule were equally effective for increasing rice yield. Evidence indicated that soil incorporation of N fertilizers was superior to the broadcasting method. The grain and straw yields as well as N uptake by rice increased

  2. Foliar applied urea improves freezing protection to avocado and peach

    Microsoft Academic Search

    S. Zilkah; Z. Wiesmann; I. Klein; I. David

    1996-01-01

    The effect of foliar applied urea on freeze hardiness was evaluated under orchard and laboratory conditions. Freezing injury and senescence of avocado (Persea americana Mill.) cv. ‘Hass’ leaves in the orchard was inversely correlated to N content. Three foliar applications of 2% low-biuret urea caused a 26% nitrogen enrichment of leaves. Consequently, leaf freezing hardiness was increased and senescence retarded.

  3. Variability of urea concentration in camel milk in Kazakhstan

    E-print Network

    Paris-Sud XI, Université de

    Note Variability of urea concentration in camel milk in Kazakhstan Bernard FAYE 1*, Gaukhar-protein nitrogen in milk. The variability of its concentration was never reported in camel milk. The present communication aimed to give some reference values on urea content in camel milk and to explore some

  4. Relative ammonia loss from urea-based fertilizers applied to rice under different hydrological situations

    Microsoft Academic Search

    S. K. Patel; D. Panda; S. K. Mohanty

    1989-01-01

    Relative ammonia volatilization loss from prilled urea, urea supergranule (USG), neem cake-coated urea (NCU), rock phosphate-coated urea (RPCU), gypsum-coated urea (GCU), and prilled urea supplemented with dhaincha (Sesbania aculeata) green manure (Dh + PU) was measured in the fields under different hydrological situations of rice growing. Ammoniacal-N and pH of flood water were less with point placement of USG and

  5. Structure and permeation mechanism of a mammalian urea transporter

    PubMed Central

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

    2012-01-01

    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 ?. 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. PMID:22733730

  6. Dispersion interactions between urea and nucleobases contribute to the destabilization of RNA by urea in aqueous solution.

    PubMed

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

    2015-03-01

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

  7. Solution Combustion Synthesis Impregnated Layer Combustion Synthesis is a Novel

    E-print Network

    Mukasyan, Alexander

    Solution Combustion Synthesis Impregnated Layer Combustion Synthesis is a Novel Methodology Engineering University of Notre Dame University of Notre Dame #12;Outline: Overview of combustion synthesis Reaction system Combustion front analaysis Theoretical model results Conclusions Acknowledgements #12

  8. Combustion 2000

    SciTech Connect

    None

    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

  9. 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 s

  10. Combustion chamber for an internal-combustion engine

    Microsoft Academic Search

    Ishida

    1987-01-01

    A combustion chamber for an internal-combustion engine is described comprising: a main combustion chamber defined by a first recess in the top surface of the crown of a piston; an auxiliary combustion chamber defined by a second recess in the top surface of the crown of the piston beside the main combustion chamber, the volume of the auxiliary combustion chamber

  11. Combustion 2000

    SciTech Connect

    None

    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

  12. ChemTeacher: Combustion

    NSDL National Science Digital Library

    2011-01-01

    ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Combustion page includes resources for teaching students about the chemistry behind combustion.

  13. Maintain Combustion Systems 

    E-print Network

    Fletcher, R. J.

    1979-01-01

    Energy is consumed, and wasted, in liberal amounts in the combustion processes which supply heat energy to boilers and process heaters. Close attention to combustion systems can be extremely beneficial: Optimum air to fuel ratios, i.e., maintaining...

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

    PubMed Central

    Chow, Charles; Kurt, Ne?e; 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 ?-sheet self-associated aggregates previously reported for this protein at high temperatures, the soluble aggregates detected here have either ?-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. Preparation and characterization of urea-oxalic acid solid form

    NASA Astrophysics Data System (ADS)

    Onija, Oana; Borodi, Gh.; Kacso, Irina; Pop, M. N.; Dadarlat, D.; Bratu, I.; Jumate, N.

    2012-02-01

    The selective production of crystalline polymorphs is an outstanding problem in solid-state chemistry. In this study, the preparation of a new urea solid form is based on pure urea and oxalic acid (1:1), by grinding the components at room temperature. The resulted compound was investigated by X-ray powder diffraction (PXRD), thermal analysis (DSC, PPE) and infrared (FTIR) spectroscopy. The difference between the PXRD patterns of urea-oxalic acid and of the starting components evidenced a new compound. Using X-ray powder diffraction method, the lattice parameters were determined. Some thermal properties of the obtained compound were also investigated by the previous mentioned calorimetric techniques.

  16. Internal combustion engine with dual combustion chambers

    Microsoft Academic Search

    Simay

    1987-01-01

    This patent describes a spark-ignition. The overhead valve type internal combustion engine comprises: a cylinder closed at the top by a semi-spherical cylinder head; a piston reciprocating within the cylinder with the piston; cylinder and cylinder head defining at least one combustion chamber; and wherein the cylinder head includes an intake valve aperture, an exhaust valve aperture, and a spark

  17. Combustion Modeling in Internal Combustion Engines

    Microsoft Academic Search

    FRANK J. ZELEZNIK

    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

  18. Internal combustion engine

    Microsoft Academic Search

    G. Perrin; H. Bergmann

    1984-01-01

    An externally auto-ignited four-stroke internal combustion engine which includes a combustion chamber disposed in an upper surface of a piston such that, in an upper dead-center position of the piston, the combustion chamber receives almost all of the fuel-air mixture. The combustion chamber includes a planar bottom portion and has a cross-sectional shape of a truncated cone expanding in a

  19. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    Microsoft Academic Search

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2001-01-01

    The implementation of increasingly stringent Clean Air Act Regulations by the coal utility industry has resulted in an increase in the concentration of unburned carbon in coal combustion fly ash. In 1999, around 6 million tons of unburned carbon were disposed in the US, due to the present lack of efficient routes for its utilization. However, unburned carbon is a

  20. Internal combustion engine apparatus

    SciTech Connect

    Kondo, T.; Inaga, H.

    1986-12-23

    An internal combustion engine apparatus is described comprising, in combination, an internal combustion engine having an ignition system capable of step advance when a predetermined engine speed is reached between low and high ranges of engine speed; and a centrifugal clutch connected to an output shaft of the internal combustion engine, the centrifugal clutch being engaged and disengaged at substantially the predetermined engine speed.

  1. BOOK REVIEW: Turbulent Combustion

    Microsoft Academic Search

    Norbert Peters

    2001-01-01

    The book Turbulent Combustion by Norbert Peters is a concise monograph on single-phase gaseous low Mach number turbulent combustion. It is compiled from the author's review papers on this topic plus some additional material. Norbert Peters characterizes turbulent combustion both by the way fuel and air are mixed and by the ratio of turbulent and chemical time scales. This approach

  2. Internal combustion engine

    Microsoft Academic Search

    Amery

    1974-01-01

    A spark ignition internal combustion engine is described that uses a double-headed cylinder to achieve more complete combustion, and hence less unburned exhaust emissions, than existing internal combustion engine designs. The engine is of the piston type, with the piston mechanically arranged for both oscillatory and related vertically reciprocating motion. The cylinder is double-headed, and the heads are oriented with

  3. Internal combustion engine

    Microsoft Academic Search

    Thomas

    1976-01-01

    An internal combustion engine is described which utilizes a combustion cylinder formed in part of material which can withstand high temperatures in conjunction with a displacement or power piston having a ringless section capable of withstanding high temperatures and being backed up by a relatively low temperature lubricated ringed piston section. Means to inject fuel and water into the combustion

  4. Combustion synthesis and nanomaterials

    Microsoft Academic Search

    Singanahally T. Aruna; Alexander S. Mukasyan

    2008-01-01

    The recent developments and trends in combustion science towards the synthesis of nanomaterials are discussed. Different modifications made to conventional combustion approaches for preparation of nanomaterials are critically analyzed. Special attention is paid to various applications of combustion synthesized nanosized products.

  5. Ammonia volatilization from a flooded rice field fertilized with amended urea materials

    Microsoft Academic Search

    H. S. Chauhan; B. Mishra

    1989-01-01

    The extent of ammonia volatilization from prilled urea, urea supergranule and urea amended with neem seed cake, shell-lac and dicyandiamide was studied in a field experiment on flooded rice. The ammonia loss was measured by the closed acid trap method. The collected ammonia was highest from unamended prilled urea, accounting for 19 to 20 per cent of the applied N

  6. 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...

  7. Correcting Nitrogen Deficiencies in Cotton with Urea-Based Products

    E-print Network

    Livingston, Stephen; Stichler, Charles

    1995-11-22

    Correcting nitrogen deficiency is important for cotton plant growth. This publication explains nitrogen requirements, the problems associated with nitrogen deficiency, and ways to correct deficiencies using urea as a source of nitrogen....

  8. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...PAPERBOARD COMPONENTS Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium...a component of articles intended for use in producing, manufacturing,...

  9. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...PAPERBOARD COMPONENTS Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium...a component of articles intended for use in producing, manufacturing,...

  10. 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.

  11. Correcting Nitrogen Deficiencies in Cotton with Urea-Based Products 

    E-print Network

    Livingston, Stephen; Stichler, Charles

    1995-11-22

    Correcting nitrogen deficiency is important for cotton plant growth. This publication explains nitrogen requirements, the problems associated with nitrogen deficiency, and ways to correct deficiencies using urea as a source of nitrogen....

  12. 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.

  13. 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.

  14. Physics based modeling of urea selective catalytic reduction systems

    E-print Network

    Na, Hanbee

    2010-01-01

    This thesis addresses control-oriented modeling of urea-selective catalytic reduction (SCR) after-treatment systems used for reducing NO, emission in diesel vehicles. Starting from first-principles, appropriate simplifications ...

  15. 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.

  16. Materials for thermohydrolysis of urea in a fluidized bed

    Microsoft Academic Search

    O. Kröcher; M. Elsener

    2009-01-01

    The production of ammonia from urea was investigated in a fluidized bed reactor in order to avoid the formation of N2O in the selective non-catalytic reduction (SNCR) process, which occurs when urea is directly injected into an SNCR reactor.Among about 20 tested materials, ?-Al2O3 proved to be the best suited as a fluidized bed material due to its high catalytic

  17. Detoxication of Ammonia in Sheep Fed Soy Protein or Urea

    Microsoft Academic Search

    WILLIAM CHALUPA; JIMMY CLARK; PAMELA OPLIGER

    Urea-fed sheep were able to detoxify additional ammonia absorbed from the digestive tract by a mechanism involving increased concentrations of liver ornithine. Feeding urea as the sole nitrogen source caused decreases in activities of carbamyl phosphate synthetase, ornithine transcarbamylase and argüíase while no differences were noted in activities of arginine synthetase and argininosuccinase. Decreases in these enzyme systems were concluded

  18. Urea-requiring lactate dehydrogenases of marine elasmobranch fishes

    Microsoft Academic Search

    Paul H. Yancey; George N. Somero

    1978-01-01

    The kinetic properties — apparentKm of pyruvate, pyruvate inhibition pattern, and maximal velocity — of M4 (skeletal muscle) lactate dehydrogenases of marine elasmobranch fishes resemble those of the homologous lactate dehydrogenases of non-elasmobranchs only when physiological concentrations of urea (approximately 400 mM) are present in the assay medium. Urea increases the apparentKm of pyruvate to values typical of other vertebrates

  19. Pulsatile urea excretion in the gulf toadfish: mechanisms and controls

    Microsoft Academic Search

    Chris M. Wood; M. Danielle McDonald; Lena Sundin; Pierre Laurent; Patrick J. Walsh

    2003-01-01

    Opsanus beta expresses a full complement of ornithine–urea cycle (OUC) enzymes and is facultatively ureotelic, reducing ammonia-N excretion and maintaining urea-N excretion under conditions of crowding\\/confinement. The switch to ureotelism is keyed by a modest rise in cortisol associated with a substantial increase in cytosolic glutamine synthetase for trapping of ammonia-N and an upregulation of the capacity of the mitochondrial

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. Routing in hybrid networks 

    E-print Network

    Gupta, Avinash

    2001-01-01

    Hybrid networks are networks that have wired as well as wireless components. Several routing protocols exist for traditional wired networks and mobile ad-hoc networks. However, there are very few routing protocols designed for hybrid networks...

  7. EVALUATION OF UREA FERTILIZERS AND UREASE INHIBITORS FOR CORN AND WHEAT PRODUCTION (PHOSPHOROAMIDE, HYDROLYSIS)

    Microsoft Academic Search

    ALAN JAY SCHLEGEL

    1985-01-01

    Urea is the major solid N fertilizer in world agriculture, however, ammonia volatilization from surface-applied urea fertilizers can result in urea producing lower crop yields than other N fertilizers. Urease inhibitors retard urea hydrolysis and, in laboratory studies, reduce ammonia volatilization loss from urea fertilizers.^ Six phosphoroamide urease inhibitors trichloroethyl phosphorodiamidate, diethyl phosphoric triamide, dimethyl phosphoric triamide, N-(diaminophosphinyl)-cyclohexylamine, N-benzyl-N-methyl phosphoric

  8. Opportunities in pulse combustion

    SciTech Connect

    Brenchley, D.L.; Bomelburg, H.J.

    1985-10-01

    In most pulse combustors, the combustion occurs near the closed end of a tube where inlet valves operate in phase with the pressure amplitude variations. Thus, within the combustion zone, both the temperature and the pressure oscillate around a mean value. However, the development of practical applications of pulse combustion has been hampered because effective design requires the right combination of the combustor's dimensions, valve characteristics, fuel/oxidizer combination, and flow pattern. Pulse combustion has several additional advantages for energy conversion efficiency, including high combustion and thermal efficiency, high combustion intensity, and high convective heat transfer rates. Also, pulse combustion can be self-aspirating, generating a pressure boost without using a blower. This allows the use of a compact heat exchanger that may include a condensing section and may obviate the need for a chimney. In the last decade, these features have revived interest in pulse combustion research and development, which has resulted in the development of a pulse combustion air heater by Lennox, and a pulse combustion hydronic unit by Hydrotherm, Inc. To appraise this potential for energy savings, a systematic study was conducted of the many past and present attempts to use pulse combustion for practical purposes. The authors recommended areas where pulse combustion technology could possibly be applied in the future and identified areas in which additional R and D would be necessary. Many of the results of the study project derived from a special workshop on pulse combustion. This document highlights the main points of the study report, with particular emphasis on pulse combustion application in chemical engineering.

  9. Proxies For Anonymous Routing

    Microsoft Academic Search

    Michael G. Reed; Paul F. Syverson; David M. Goldschlag

    1996-01-01

    Using traffic analysis, it is possible to infer who is talking to whom over a public network. This paper describes a flexible communications infrastructure, onion routing, which is resistant to traffic analysis. Onion routing lives just beneath the application layer, and is designed to interface with a wide variety of unmodified Internet services by means of proxies. Onion routing has

  10. Catalyzed Decomposition of Urea. Molecular Dynamics Simulations of the Binding of Urea to Urease

    PubMed Central

    Estiu, Guillermina; Merz, Kenneth M.

    2008-01-01

    We present the results of molecular dynamics simulations on the urea/urease system. The starting structure was prepared from the 2.0Å crystal structure of Benini et al. of DAP-inhibited urease (PDB code 3UBP),1 and the trimeric structure (2479 residues) resulted in 180K atoms after solvation by water. The force field parameters were derived using the bonded model approach described by Hoops et al.2 Three different systems were analyzed, each one modeling a different protonation pattern for the His320 and His219 residues. In each case, the three monomers of urease have been analyzed separately. The time averaged structures observed in the three monomers suggest that urease could follow two different competitive mechanisms. A “protein assisted proton transfer” mechanism points to Asp221 as crucial for catalysis. An “Asp mediated proton transfer” involves the transfer of a proton from the bridging OH to a NH2 moiety of urea, assisted by Asp360 in the active site. The impact of the simulation results on our understanding of urease catalysis are discussed in detail. PMID:16584179

  11. Pulsatile urea excretion in the gulf toadfish: mechanisms and controls.

    PubMed

    Wood, Chris M; McDonald, M Danielle; Sundin, Lena; Laurent, Pierre; Walsh, Patrick J

    2003-12-01

    Opsanus beta expresses a full complement of ornithine-urea cycle (OUC) enzymes and is facultatively ureotelic, reducing ammonia-N excretion and maintaining urea-N excretion under conditions of crowding/confinement. The switch to ureotelism is keyed by a modest rise in cortisol associated with a substantial increase in cytosolic glutamine synthetase for trapping of ammonia-N and an upregulation of the capacity of the mitochondrial OUC to use glutamine-N. The entire day's urea-N production is excreted in 1 or 2 short-lasting pulses, which occur exclusively through the gills. The pulse event is not triggered by an internal urea-N threshold, is not due to pulsatile urea-N production, but reflects pulsatile activation of a specific branchial excretion mechanism that rapidly clears urea-N from the body fluids. A bidirectional facilitated diffusion transporter, with pharmacological similarity to the UT-A type transporters of the mammalian kidney, is activated in the gills, associated with an increased trafficking of dense-cored vesicles in the pavement cells. An 1814 kB cDNA ('tUT') coding for a 475-amino acid protein with approximately 62% homology to mammalian UT-A's has been cloned and facilitates phloretin-sensitive urea transport when expressed in Xenopus oocytes. tUT occurs only in gill tissue, but tUT mRNA levels do not change over the pulse cycle, suggesting that tUT regulation occurs at a level beyond mRNA. Circulating cortisol levels consistently decline prior to a pulse event and rise thereafter. When cortisol is experimentally clamped at high levels, natural pulse events are suppressed in size but not in frequency, an effect mediated through glucocorticoid receptors. The cortisol decline appears to be permissive, rather than the actual trigger of the pulse event. Fluctuations in circulating AVT levels do not correlate with pulses; and injections of AVT (at supraphysiological levels) elicit only minute urea-N pulses. However, circulating 5-hydroxytryptamine (5-HT) levels fluctuate considerably and physiological doses of 5-HT cause large urea-N pulse events. When the efferent cranial nerves to the gills are sectioned, natural urea pulse events persist, suggesting that direct motor output from the CNS to the gill is not the proximate control. PMID:14662293

  12. Combustion chamber system for kerosine internal combustion engine

    Microsoft Academic Search

    S. Yagi; J. Ootani; M. Araki; F. Yoshida

    1986-01-01

    A combustion chamber system is described for an overhead valve type kerosine internal combustion engine, comprising: a cylinder head; a piston slidable in a cylinder; a main combustion chamber defined by a lower surface of a cylinder head and an upper surface of the piston; an auxiliary combustion chamber defined within the cylinder head and spaced from the main combustion

  13. 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.

  14. 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.

  15. Recycling of polyurethane-urea RIM

    SciTech Connect

    Xiao, H.X.; Kresta, J.E.; Suthar, B.; Li, X.H. [Univ. of Detroit, Mercy, MI (United States)

    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.

  16. 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...

  17. Optimization of hierarchical routing protocols

    Microsoft Academic Search

    Jean-louis Rougier; Daniel Kofman; Annie Gravey

    2000-01-01

    This paper concentrates on hierarchical routing protocols and their optimization. In a hierarchical routing protocol the network is divided into independent routing areas so that a node has complete routing information on its partition, but only reduced routing information of the “outside world” (i.e. the other partitions). Such routing protocols have been introduced in the early 1980s in order to

  18. Structural, morphological and optical investigations on BaMgAl 10O 17:Eu 2+ elaborated by a microwave induced solution combustion synthesis

    Microsoft Academic Search

    Nathalie Pradal; Audrey Potdevin; Geneviève Chadeyron; Rachid Mahiou

    2011-01-01

    Blue-emitting Eu2+-doped barium magnesium aluminate (BaMgAl10O17:Eu2+) for advanced displays and lighting devices was prepared by a microwave induced solution combustion synthesis using urea as combustion fuel and nitrates as oxidizer. Purity control of as-synthesized blue phosphor particles was undertaken by modifying the fuel to oxidizer molar ratio. X-ray diffraction, scanning electron microscopy and photoluminescence were used to investigate powders crystallinity,

  19. 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.

  20. 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.

  1. A combustion synthesis method to obtain alternative cermet materials for SOFC anodes

    Microsoft Academic Search

    A Ringuedé; J. A Labrincha; J. R Frade

    2001-01-01

    Homogeneous mixtures of nanocrystalline powders of Ni–YSZ, (Ni,Co)–YSZ, (Ni,Fe)–YSZ, and (Ni,Cu)–YSZ were obtained by combustion synthesis from mixtures of molten nitrates and urea. Electrolyte\\/anode bilayers were then prepared by pressing a cermet layer onto a previously pressed yttria-stabilised zirconia (YSZ) electrolyte layer, at room temperatures, and then co-firing; this yields a porous cermet anode, and a dense YSZ layer with

  2. Nanocrystalline Cr 2O 3 and amorphous CrO 3 produced by solution combustion synthesis

    Microsoft Academic Search

    M. D. Lima; R. Bonadimann; M. J. de Andrade; J. C. Toniolo; C. P. Bergmann

    2006-01-01

    The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dichromate, glycine, urea and ammonium nitrate dissolved in aqueous solution were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and the fuel\\/oxidant ratio. Amorphous CrO3

  3. Preparation of ultrafine CeO 2 powders by microwave-induced combustion and precipitation

    Microsoft Academic Search

    Yen-Pei Fu; Cheng-Hsiung Lin; Chin-Shang Hsu

    2005-01-01

    A novel procedure for synthesizing submicron crystalline single-phase ceramic powder was investigated. Ultrafine CeO2 powder was successfully prepared by combustion of mixture of cerium nitrate (oxidizer) and urea (fuel) in microwave oven for 15min. The ultrafine powder was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), differential thermal analysis and thermogravimetric analysis (DTA\\/TG); surface

  4. VOC oxidation over CuO–CeO 2 catalysts prepared by a combustion method

    Microsoft Academic Search

    Dimitrios Delimaris; Theophilos Ioannides

    2009-01-01

    CuO–CeO2 catalysts were prepared via a urea combustion method and their performance in the oxidation of ethanol, ethyl acetate and toluene was evaluated. XRD, H2-TPR and N2 physisorption were employed in catalyst characterization. The specific surface area of mixed materials was higher than the one of single oxides. In ceria-rich materials, crystalline copper oxide phases are absent and segregation of

  5. 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.

  6. Lump wood combustion process

    NASA Astrophysics Data System (ADS)

    Kubesa, Petr; Horák, Ji?í; Branc, Michal; Krpec, Kamil; Hopan, František; Koloni?ný, 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.

  7. 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.

  8. 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

  9. 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

  10. Influence of modified forms of urea and nitrogen levels on weed growth and grain yield of lowland rice

    Microsoft Academic Search

    R. Venkitaswamy; S. Subramanian; V. Veerabadran

    1991-01-01

    The growth of weeds and their subsequent reduction of rice yield as affected by N source neem cake coated urea (NCU), dicyandiamide coated urea (DCU), rock phosphate coated urea (RPCU), urea supergranules (USG) and prilled urea (PU) was studied on a clay loam soil at Coimbatore, India. Experiments were conducted in northeast monsoon (NEM) 1981, summer 1982, and southwest monsoon

  11. Combustion under microgravity conditions

    SciTech Connect

    Berlad, A.L.

    1982-01-01

    Reduced gravity combustion experiments are frequently required to provide the information necessary for comprehensive understanding of combustion phenomena at normal gravitational conditions. Previous papers have dealt in detail with a broad range of combustion science experiments which require reduced gravity experimentation. This paper enlarges on these previous studies. Reduced gravity experiments are shown to be needed for comprehensive understanding of kinetic and thermokinetic oscillatory flame processes, the radiative ignition of solids, high pressure flame propagation and extinction phenomena, as well as a number of other combustion science areas of vital interest.

  12. 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.

  13. 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

  14. Combustion Synthesis of Magnesium Aluminate

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    In the system MgO-Al2O3, three compounds MgAl2O4, MgAl6O10 (also expressed as- Mg0.4Al2.4O4) and MgAl26O40 are well known. Importance of the first two is well established. Magnesium aluminate (MgAl2O4) spinel is a technologically important material due to its interesting thermal properties. The MgAl2O4 ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl2O4 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 MgAl6O10 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 MgAl2O4 and MgAl6O10 were formed in a single step, while MgAl26O40 was not formed by this procedure. Activation of MgAl6O10 by rare earth ions like Ce3+, Eu3+ and Tb3+ and ns2 ion Pb2+ could be achieved. Excitation bands for MgAl6O10 are at slightly shorter wavelengths compared to those reported for MgAl2O4.

  15. Development of novel chemical synthetic routes for nanocrystalline VN, Mo2N, and W2N nitride materials

    NASA Astrophysics Data System (ADS)

    Mishra, Pragnya Paramita; Panda, Rabi Narayan

    2015-06-01

    In this study, novel synthetic routes for the synthesis of VN, Mo2N and W2N binary nitrides have been presented. We have synthesized new precursors, i.e.V2O5 from citric acid based sol-gel method and Mo, W based ethylenediamine complex which are used for the nitridation experiments using solid urea (NH2CONH2) or ammonia (NH3(g)). We have successfully prepared phase pure nano-dimensional nitride materials. The estimated crystallite sizes and SEM particle sizes were found in the range of 4-16 nm and 111-870 nm, respectively. VN, Mo2N and W2N nitrides crystallize in fcc-cubic structures with the values of lattice parameters; 4.128, 4.165 and 4.175 Å for urea route and 4.112, 4.196 and 4.150Å for ammonia route, respectively.

  16. 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

  17. [Renal regulation of the excretion of urea in fasting camels].

    PubMed

    Leng, L; Bod'a, K; Tasenov, K T; Karinbaev, R S; Makasev, E K; Rachimberdiev, S A; Tlegenov, D K; Jurgalieva, L A

    1984-09-01

    Experiments were performed with young two-humped camels exposed to 36-hour starvation with free access to water. The renal functions were measured by the standard clearance method. In spite of the administration of 20 micrograms DDAVP, a higher urine flow rate was recorded in the camels subjected to control measurements (feed intake) than in the fasting period (1.45 +/- 0.06 vs. 0.96 +/- 0.06 ml . min-1, P less than less than 0.001). On the second day of fasting the camels had a significantly reduced glomerular filtration rate (GFR 317.5 +/- 23.2 vs. 170.2 +/- 17.4 ml . min-1, P less than 0.001), urea output (700.5 +/- 62.9 vs. 352.2 +/- 64.7 mumol . min-1, P less than 0.005), and fractional excretion of urea (26.9 +/- 2.8 vs. 17.9 +/- 1.7%, P less than 0.01), whereas their tubular resorption. of urea (Reab urea/GFR) increased (6.28 +/- 0.61 vs. 9.12 +/- 0.82 mumol . ml-1, P less than 0.02). No significant difference was found in the concentration of urea in plasma in the fed camels and in fasting camels (8.55 +/- 0.64 vs. 11.18 +/- 1.09 mmol . l-1, N. S.). The creatinine inulin clearance ratio (C creat/Cin) was 0.92 +/- 0.07 when the animals were fed and 1.17 +/- 0.05 when the animals starved (P less than 0.001); this suggests that the clearance of endogenous creatinine is not suitable for GFR measurement in camels under different conditions of nutrition. The kidneys of camels regulate the excretion of urea during short-time fasting mainly through the reduction of glomerular filtration rate and just partly through an increased tubular resorption. PMID:6438869

  18. Role for urea in nitrification by polar marine Archaea

    PubMed Central

    Alonso-Sáez, Laura; Waller, Alison S.; Mende, Daniel R.; Bakker, Kevin; Farnelid, Hanna; Yager, Patricia L.; Lovejoy, Connie; Tremblay, Jean-Éric; Potvin, Marianne; Heinrich, Friederike; Estrada, Marta; Riemann, Lasse; Bork, Peer; Pedrós-Alió, Carlos; Bertilsson, Stefan

    2012-01-01

    Despite the high abundance of Archaea in the global ocean, their metabolism and biogeochemical roles remain largely unresolved. We investigated the population dynamics and metabolic activity of Thaumarchaeota in polar environments, where these microorganisms are particularly abundant and exhibit seasonal growth. Thaumarchaeota were more abundant in deep Arctic and Antarctic waters and grew throughout the winter at surface and deeper Arctic halocline waters. However, in situ single-cell activity measurements revealed a low activity of this group in the uptake of both leucine and bicarbonate (<5% Thaumarchaeota cells active), which is inconsistent with known heterotrophic and autotrophic thaumarchaeal lifestyles. These results suggested the existence of alternative sources of carbon and energy. Our analysis of an environmental metagenome from the Arctic winter revealed that Thaumarchaeota had pathways for ammonia oxidation and, unexpectedly, an abundance of genes involved in urea transport and degradation. Quantitative PCR analysis confirmed that most polar Thaumarchaeota had the potential to oxidize ammonia, and a large fraction of them had urease genes, enabling the use of urea to fuel nitrification. Thaumarchaeota from Arctic deep waters had a higher abundance of urease genes than those near the surface suggesting genetic differences between closely related archaeal populations. In situ measurements of urea uptake and concentration in Arctic waters showed that small-sized prokaryotes incorporated the carbon from urea, and the availability of urea was often higher than that of ammonium. Therefore, the degradation of urea may be a relevant pathway for Thaumarchaeota and other microorganisms exposed to the low-energy conditions of dark polar waters. PMID:23027926

  19. Role for urea in nitrification by polar marine Archaea.

    PubMed

    Alonso-Sáez, Laura; Waller, Alison S; Mende, Daniel R; Bakker, Kevin; Farnelid, Hanna; Yager, Patricia L; Lovejoy, Connie; Tremblay, Jean-Éric; Potvin, Marianne; Heinrich, Friederike; Estrada, Marta; Riemann, Lasse; Bork, Peer; Pedrós-Alió, Carlos; Bertilsson, Stefan

    2012-10-30

    Despite the high abundance of Archaea in the global ocean, their metabolism and biogeochemical roles remain largely unresolved. We investigated the population dynamics and metabolic activity of Thaumarchaeota in polar environments, where these microorganisms are particularly abundant and exhibit seasonal growth. Thaumarchaeota were more abundant in deep Arctic and Antarctic waters and grew throughout the winter at surface and deeper Arctic halocline waters. However, in situ single-cell activity measurements revealed a low activity of this group in the uptake of both leucine and bicarbonate (<5% Thaumarchaeota cells active), which is inconsistent with known heterotrophic and autotrophic thaumarchaeal lifestyles. These results suggested the existence of alternative sources of carbon and energy. Our analysis of an environmental metagenome from the Arctic winter revealed that Thaumarchaeota had pathways for ammonia oxidation and, unexpectedly, an abundance of genes involved in urea transport and degradation. Quantitative PCR analysis confirmed that most polar Thaumarchaeota had the potential to oxidize ammonia, and a large fraction of them had urease genes, enabling the use of urea to fuel nitrification. Thaumarchaeota from Arctic deep waters had a higher abundance of urease genes than those near the surface suggesting genetic differences between closely related archaeal populations. In situ measurements of urea uptake and concentration in Arctic waters showed that small-sized prokaryotes incorporated the carbon from urea, and the availability of urea was often higher than that of ammonium. Therefore, the degradation of urea may be a relevant pathway for Thaumarchaeota and other microorganisms exposed to the low-energy conditions of dark polar waters. PMID:23027926

  20. Mineral Characterization for Combustion

    Microsoft Academic Search

    Colin R. Ward

    The material referred to as “mineral matter” in coal has been to the combustion engineer a close to random association of chemical elements. These “random” elements are transformed in the combustion process to ash, react to form boiler deposits (slagging); abrade the internal parts of the boiler (erosion), and produce vapor phases that react with the metals in the boiler

  1. Internal combustion piston engines

    Microsoft Academic Search

    Segaser

    1977-01-01

    Current worldwide production of internal combustion piston engines includes many diversified types of designs and a very broad range of sizes. Engine sizes range from a few horsepower in small mobile units to over 40,000 brake horsepower in large stationary and marine units. The key characteristics of internal combustion piston engines considered appropriate for use as prime movers in Integrated

  2. Fundamental aspects of combustion

    Microsoft Academic Search

    A. Linan; F. A. Williams

    1993-01-01

    This book is addressed to readers who have not specialized in combustion. Chapter 1 provides introductory information on combustion. Premixed flames and diffusion flames are the main topics of chapters 2 and 3, emphasizing the important roles played by asymptotic analysis and the diversity arising from chemical kinetics in flames. In an attempt to emphasize their common features, the subjects

  3. Fifteenth combustion research conference

    SciTech Connect

    NONE

    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.

  4. Rotary internal combustion engine

    Microsoft Academic Search

    Roggenburk

    1987-01-01

    This patent describes a rotary internal combustion engine, which comprises: a nonrotatable housing; means for supplying a combustion mixture; a rotatable shaft journalled within the housing; a compression portion rotatable with the shaft, the compression portion comprising a first rotor mounted on the shaft and cylinders and pistons, each of the pistons reciprocating within one of the cylinders to compress

  5. The modification of polyurethane foams using new boroorganic polyols (II) polyurethane foams from boron-modified hydroxypropyl urea derivatives.

    PubMed

    Zarzyka, Iwona

    2014-01-01

    The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150 °C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

  6. The Modification of Polyurethane Foams Using New Boroorganic Polyols (II) Polyurethane Foams from Boron-Modified Hydroxypropyl Urea Derivatives

    PubMed Central

    2014-01-01

    The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150°C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

  7. Theoretical study on the structures and properties of mixtures of urea and choline chloride.

    PubMed

    Sun, Hui; Li, Yan; Wu, Xue; Li, Guohui

    2013-06-01

    In this work, we investigated in detail the structural characteristics of mixtures of choline chloride and urea with different urea contents by performing molecular dynamic (MD) simulations, and offer possible explanations for the low melting point of the eutectic mixture of choline chloride and urea with a ratio of 1:2. The insertion of urea molecules was found to change the density distribution of cations and anions around the given cations significantly, disrupting the long-range ordered structure of choline chloride. Moreover, with increasing urea concentration, the hydrogen bond interactions between choline cations and Cl(-) anions decreased, while those among urea molecules obviously increased. From the hydrogen bond lifetimes, it was found that a ratio of 1:2 between choline chloride and urea is necessary for a reasonable strength of hydrogen bond interaction to maintain the low melting point of the mixture of choline chloride with urea. In addition, it was also deduced from the interaction energies that a urea content of 67.7 % may make the interactions of cation-anion, cation-urea and anion-urea modest, and thus results in the lower melting point of the eutectic mixture of choline chloride and urea. The present results may offer assistance to some extent for understanding the physicochemical properties of the eutectic mixture of choline chloride and urea, and give valuable information for the further development and application of deep eutectic solvents. PMID:23435478

  8. New Cytochrome P-450 Ligands Based on Urea Derivatives

    Microsoft Academic Search

    A. I. Khlebnikov; R. R. Akhmedzhanov; O. I. Naboka; A. A. Bakibaev; M. I. Tartynova; T. P. Novozheeva; A. S. Saratikov

    2005-01-01

    Cytochrome P-450 (CYPIIB1 isoform) ligands were constructed de novo on the basis of QSAR models derived using the frontal polygon (FP) method. The following compounds were designed and synthesized: 2-phenyl-6-benzyl-2,4,6,8-tetraazabicyclo[3.3.0]octane-3,7-dione, N-acetyl-N'-(1-phenylethyl)urea, and (1-phenyl-3-methylbutyl)urea. Their interaction with phenobarbital-induced microsomes isolated from rat liver was studied spectrophotometrically. The dissociation constants Ks of the enzyme - substrate complexes measured are in good agreement

  9. Urea impedimetric biosensor based on polymer degradation onto interdigitated electrodes

    Microsoft Academic Search

    M. Cortina; M. J. Esplandiu; S. Alegret; M. del Valle

    2006-01-01

    The measurement of urea was accomplished with an interdigitated\\u000a electrode by using ac impedance spectroscopy to follow capacitance\\u000a changes, which were produced during enzyme-catalyzed dissolution of a\\u000a polymer coating. The employed coating was the enteric polymer Eudragit\\u000a S-100, on which urease enzyme was immobilized by carbodiimide coupling.\\u000a Urea was determined in the 0.02-2 M range, proving that the combination\\u000a of

  10. What is Milk Urea Nitrogen and How is It Interpreted? Dr. Doo-Hong Min, Extension Forage Specialist, MSU UPES

    E-print Network

    in milk urea nitrogen. Excess concentrations of urea in the blood can affect milk production, reproductive causes of low milk production and fertility. Urea is an indicator of the balance of the rumen system so

  11. Internal combustion engine

    SciTech Connect

    Helmich, M.J.; Hoagland, M.C.; Hubbard, R.L.; Schaub, F.S.

    1981-12-22

    A method of combusting natural gas fuel in a two cycle, turbocharged internal combustion engine substantially reduces the production of nitrogen-oxygen emissions. An improved turbocharger design provides increased air charging pressure, produces a controlled lean air/fuel mixture and lowers peak combustion temperatures. A jet cell ignition device ensures uniform, reliable ignition of the lean air/fuel mixture under all operating conditions and the lean air/fuel mixture in turn encourages complete fuel combustion and provides excellent combustion characteristics with methane, ethane and heavier paraffinic hydrocarbon fuels. These structural modifications and adjustment of other operating parameters combine to reduce nitric oxide (NO) and nitrogen dioxide (NO/sub 2/) emissions by as much as 75% while effecting only a negligible increase in fuel consumption.

  12. Hierarchical Route Planner

    NASA Astrophysics Data System (ADS)

    Benton, John R.

    1988-03-01

    A two-level hierarchical route planner has been developed. The data input to the system is a cross-country mobility map. For a given vehicle type, this map specifies regions which are "GO" or "NO-GO." A line-thinning algorithm is used to generate a skeleton of the "GO" areas. This skeleton is then converted into a graph-theoretic structure. A first-level route planner using elevation-grid data is used to compute the traversal time of each arc of the graph. These traversal times become the weights used by the second level route planner. This route planner is an A* algorithm that is used to search for a specified number of non-competing routes, i.e., routes that have no arc-segments in common. Thus, the first level route planner does detailed planning over a small area but is subject to combinatorial explosion when a search over a wider area is required. The second level graph-search algorithm provides the capability to efficiently plan a route over a larger area but without detail about the precise path followed. This system was implemented in Common Lisp on a Lisp machine. The software has also been integrated into a workstation that was developed to provide support to Army robotic vehicle research. The workstation provides support for comparing the capabilities of alternative route finding algorithms.

  13. 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.

  14. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Polyamine urea-for-malde-hyde condensate (specific name). 721...urea-for-malde-hyde condensate (specific name). ...polyamine ureaformaldehyde condensate (PMN P-87-1456) is...uses are: (i) Release to water. Requirements as...

  15. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Polyamine urea-for-malde-hyde condensate (specific name). 721...urea-for-malde-hyde condensate (specific name). ...polyamine ureaformaldehyde condensate (PMN P-87-1456) is...uses are: (i) Release to water. Requirements as...

  16. 40 CFR 721.6440 - Polyamine urea-for-malde-hyde condensate (specific name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Polyamine urea-for-malde-hyde condensate (specific name). 721...urea-for-malde-hyde condensate (specific name). ...polyamine ureaformaldehyde condensate (PMN P-87-1456) is...uses are: (i) Release to water. Requirements as...

  17. Urea destabilizes RNA by forming stacking interactions and multiple hydrogen bonds with nucleic acid bases

    E-print Network

    U. Deva Priyakumar; Changbong Hyeon; D. Thirumalai; Alexander D. MacKerell Jr

    2009-12-07

    Urea titration of RNA by urea is an effective approach to investigate the forces stabilizing this biologically important molecule. We used all atom molecular dynamics simulations using two urea force fields and two RNA constructs to elucidate in atomic detail the destabilization mechanism of folded RNA in aqueous urea solutions. Urea denatures RNA by forming multiple hydrogen bonds with the RNA bases and has little influence on the phosphodiester backbone. Most significantly we discovered that urea engages in stacking interactions with the bases. We also estimate, for the first time, m-value for RNA, which is a measure of the strength of urea-RNA interactions. Our work provides a conceptual understanding of the mechanism by which urea enhances RNA folding rates.

  18. Urea destabilizes RNA by forming stacking interactions and multiple hydrogen bonds with nucleic acid bases

    E-print Network

    Priyakumar, U Deva; Thirumalai, D; MacKerell, Alexander D

    2009-01-01

    Urea titration of RNA by urea is an effective approach to investigate the forces stabilizing this biologically important molecule. We used all atom molecular dynamics simulations using two urea force fields and two RNA constructs to elucidate in atomic detail the destabilization mechanism of folded RNA in aqueous urea solutions. Urea denatures RNA by forming multiple hydrogen bonds with the RNA bases and has little influence on the phosphodiester backbone. Most significantly we discovered that urea engages in stacking interactions with the bases. We also estimate, for the first time, m-value for RNA, which is a measure of the strength of urea-RNA interactions. Our work provides a conceptual understanding of the mechanism by which urea enhances RNA folding rates.

  19. Oligomeric Structure and Functional Characterization of the Urea Transporter from Actinobacillus pleuropneunomiae

    PubMed Central

    Raunser, Stefan; Mathai, John C.; Abeyrathne, Priyanka D.; Rice, Amanda J.; Zeidel, Mark L.; Walz, Thomas

    2009-01-01

    Urea transporters facilitate urea permeation across cell membranes in prokaryotes and eukaryotes. Bacteria use urea either as a means to survive in acidic environments and/or as a nitrogen source. The urea transporter ApUT from Actinobacillus pleuropneumoniae, the pathogen that causes porcine pleurisy and pneumonia, was expressed in E. coli and purified. Analysis of the recombinant protein using cross-linking and blue-native gel electrophoresis established that ApUT is a dimer in detergent solution. To determine the urea transport kinetics of ApUT, purified protein was reconstituted into proteoliposomes, and urea efflux was measured by stopped-flow fluorometry. The measured urea flux was saturable, could be inhibited by phloretin, and was not affected by pH. Two-dimensional crystals of the biologically active ApUT show that it is also dimeric in a lipid membrane and provide the first structural information on a member of the urea transporter family. PMID:19361419

  20. 77 FR 42273 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-18

    ...Initiation of Antidumping and Countervailing Duty Administrative Reviews and Requests for Revocation...See Solid Urea From the Russian Federation: Extension...See Solid Urea from the Russian Federation: Final Results...explaining that price and quantity are not...

  1. 76 FR 35405 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-17

    ...Initiation of Antidumping and Countervailing Duty Administrative Reviews and Deferral of Initiation...See Solid Urea From the Russian Federation: Extension...exists between EuroChem and its franchisees. For...Solid Urea from the Russian...

  2. Computation of azimuthal combustion instabilities in an helicopter combustion chamber

    E-print Network

    Nicoud, Franck

    Computation of azimuthal combustion instabilities in an helicopter combustion chamber C. Sensiau to compute azimuthal combustion instabilities is presented. It requires a thermoacoustic model using a n - formulation for the coupling between acoutics and combustion. The parameters n and are computed from a LES

  3. catena-Poly[[[bis­(thio­urea-?S)copper(I)]-?-thio­urea-?2 S:S] iodide acetonitrile hemisolvate

    PubMed Central

    Jia, Li; Kong, Ling-Qian; Li, Da-Cheng

    2008-01-01

    The title complex, {[Cu(CH4N2S)3]I·0.5CH3CN}n, was formed by the reaction of CuI and thio­urea in acetonitrile. There are two independent CuI ions in the asymmetric unit which are coordinated by two terminal and two bridging thio­urea ligands to form a one-dimensional helical chain structure progagating in the a-axis direction. Each CuI ion is in a distorted tetra­hedral coordination environment. The crystal structure is stabilized by weak N—H?S and N—H?I hydrogen bonds. PMID:21202021

  4. Internal combustion engine with rotary combustion chamber

    Microsoft Academic Search

    C. N. Hansen; P. C. Cross

    1988-01-01

    This patent describes an internal combustion engine comprising: a block having at least one cylindrical wall surrounding a piston chamber, piston means located in the piston chamber, means operable to reciprocate the piston means in the chamber, head means mounted on the block covering the chamber. The head means having an air and fuel intake passage, an exhaust gas passage,

  5. Internal combustion engine with rotary combustion chamber

    Microsoft Academic Search

    C. N. Hansen; P. C. Cross

    1986-01-01

    This patent describes an internal combustion engine comprising: a block having at least one cylindrical wall surrounding a piston chamber, piston means located in the piston chamber means operable to reciprocate the piston means in the chamber, head means mounted on the block covering the chamber. The head means has an air and fuel intake passage, and exhaust gas passage,

  6. Internal combustion engine squish jet combustion chamber

    Microsoft Academic Search

    1986-01-01

    This patent describes a internal combustion engine block having a piston and cylinder head, one of which has: (a) a substantially cylindrical bowl opening into the face thereof; (b) a pair of squish jet passages having respective inlets communicating with the face thereof, and respective, transversely spaced, outlets directed substantially tangentially into the bowl, the outlet of a first one

  7. Regulation of urea permeability in frog urinary bladder by prostaglandin E 2

    Microsoft Academic Search

    Vera T. Bachteeva; Ekaterina M. Fock; Elena A. Lavrova; Elena V. Naboka; Rimma G. Parnova

    2002-01-01

    The present study was performed to investigate the role of prostaglandin E2 (PGE2) in the regulation of urea transport in the frog urinary bladder, which is known to occur via a specialized arginine-vasotocin- (AVT-) regulated urea transporter. The bladders isolated from Rana temporaria L. were filled with amphibian Ringer solution containing 370 Bq\\/ml (0.01 µCi\\/ml) of [14C]urea, and urea permeability

  8. Curing of urea-formaldehyde adhesives with collagen type hydrolysates under acid condition

    Microsoft Academic Search

    F. Langmaier; J. Šivarová; K. Kolomazník; M. Mládek

    2004-01-01

    Condensation of dimethylol urea and its mixtures with urea or hydrolysate of chrome-tanned leather waste (mass fraction in\\u000a mixture 0.05) in the presence of a variable quantity of phthalic acid, as acid curing agent (within mass fraction limits 0.01-0.1),\\u000a was studied through TG technique. During condensation of sole dimethylol urea or of its mixture with urea, oxy-methylene as\\u000a well as

  9. Irritant and protective action of urea-urease ammonia in rat gastric mucosa

    Microsoft Academic Search

    Joji Takeuchi; Tomohisa Ohuchi; Hiroyuki Harada; Susumu Okabe

    1995-01-01

    The effects of urea-urease-ammonia on the rat gastric mucosa were examined and compared with those of NH4OH and NH4Cl. The mucosal application of urea with urease produced a reduction in potential difference (PD) in a dose-related manner for urea, and a significant drop was observed by >0.1% urea in the presence of 100 units urease. Such PD reduction was also

  10. Glass fiber reinforced composites of phenolic–urea–epoxy resin blends

    Microsoft Academic Search

    M. M. Raj; L. M. Raj; P. N. Dave

    The present work aims to modify conventional epoxy resin by blending with four different phenolic–urea oligomers. These oligomers are similar to phenolic–urea resin matrix and simultaneously function as amino curing agent for epoxy matrix. In this context, phenolic–urea oligomers were prepared respectively by polycondensation reaction of four phenols namely phenol, m-cresol, resorcinol and 1,5-dihydroxy naphthalene, respectively with formaldehyde and urea

  11. Neuro-Fuzzy System for Post-Dialysis Urea Rebound Prediction

    Microsoft Academic Search

    A. T. Azar; A. H. Kandil; K. M. Wahba; A. M. Elgarhy; W. A. Massoud

    2008-01-01

    Measuring post dialysis urea rebound (PDUR) requires a 30- or 60-minute post-dialysis sampling, which is inconvenient. This paper presents a novel technique for predicting equilibrated urea concentration and post dialysis urea rebound in the form of a Takagi-Sugeno-Kang fuzzy inference system. The advantage of this neuro-fuzzy hybrid approach is that it doesn't require 30-60-minute post-dialysis urea sample. Adaptive neuro-fuzzy inference

  12. Refolding of urea-induced denaturation of model proteins by trimethylamine N-oxide

    Microsoft Academic Search

    Pankaj Attri; Pannuru Venkatesu

    2011-01-01

    The biomolecules are known to be stabilized by osmolytes, trimethylamine-N-oxide (TMAO) while urea, destabilizes the protein structures. The deleterious effect of urea on proteins has been counteracted by TMAO is well understood; nonetheless, refolding of urea-induced conformational changes of proteins by TMAO is still an active subject. To understand the refolding ability of TMAO from urea-induced denaturation of biomolecules, we

  13. Onion routing access configurations

    Microsoft Academic Search

    Paul Syverson; Michael Reed; David Goldschlag

    2000-01-01

    Onion Routing is an infrastructure for private communication over a public network. It provides anonymous connections that are strongly resistant to both eavesdropping and traffic analysis. Thus it hides not only the data being sent, but who is talking to whom. Onion Routing's anonymous connections are bidirectional and near real-time, and can be used anywhere a socket connection can be

  14. Internet Routing Instability

    Microsoft Academic Search

    Craig Labovitz; G. Robert Malan; Farnam Jahanian

    1997-01-01

    This paper examines the network inter-domain routing information exchanged between backbone service providers at the major U.S. public Internet exchange points. Internet routing instability, or the rapid fluctuation of network reachability information, is an important problem currently facing the Internet engineering community. High levels of network instability can lead to packet loss, increased network latency and time to convergence. At

  15. Implicit Multicast Routing Protocol

    Microsoft Academic Search

    Thiruvengadam Venketesan; Wu-hon F. Leung

    2005-01-01

    This paper describes the IMcast (Implicit Multicast ) routing protocol, developed to address several prob lems that are responsible for the slow deployment of IP Multi cast. We focus on transparent integration with legacy router s and in improving the efficiency of the routing tree. IMcas t packets carry unicast addresses in the destination field of IPv4 header and multicast

  16. Bendable Routing Tool

    NASA Technical Reports Server (NTRS)

    Mayer, Walter

    1987-01-01

    Tool extends routing bit into internal cavities or passages so burrs and similar defects removed. Bent so inserted through curving channels. Copper sheath gives stiffness to flexible shaft but can itself be bent. Several types of routing bits attached to shaft.

  17. Use of Two Sulfonyl Urea Herbicides in Lowbush Blueberry

    Microsoft Academic Search

    Klaus I. N. Jensen; Eric G. Specht

    2004-01-01

    The continuous use of the broad spectrum herbicide hexazinone since 1981 has resulted in many changes to the weedy flora of lowbush blueberry fields, including shifts to hexazinone-tolerant species. Many of these occur in patches and could best be controlled by selective, foliar herbicide treatments. Preliminary assessments of several sufonyl urea (SU) herbicides indicated that tribenuron (Spartan or Express 75%

  18. Growth and evaluation of some urea derivative crystals

    Microsoft Academic Search

    M Ardoino; L Zeng; C Razzetti; M Zha; L Zanotti; M Curti

    2000-01-01

    Looking for compounds with optical properties comparable or better than those of urea we have performed crystallization tests on phenylurea, 1,1-dimethylurea and 1,3-dimethylurea. Appreciable results have been obtained for 1,3-dimethylurea grown by the normal freezing method. The ingots display good keeping and mechanical properties. Phase matching has been achieved with an encouraging doubling efficiency.

  19. In situ poly(urea-formaldehyde) microencapsulation of dicyclopentadiene

    E-print Network

    Sottos, Nancy R.

    material are required for self-healing materials. Urea-formaldehyde microcapsules containing a mechanical trigger for the self-healing process when damage occurs in the host material and the capsules rupture. The key feature of self-healing materials is the highly engineered microencapsulated healing

  20. 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, ?-alanine, ?-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.

  1. 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...

  2. Using urea to decompose polylactic acid in bark compost

    Microsoft Academic Search

    Kenji Nakamura

    Polylactic acid (PLA) is a plastic of plant origin. Because it is biodegradable, it is used for various environmentally friendly materials, such as sand bags and mulching sheets for agriculture and construction. However, PLA biodegrades very slowly and only a few microorganisms can biodegrade it. We tested a biodegrading method that uses urea to accelerate the decomposition of PLA cloth

  3. 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...

  4. Corrosion testing of urea-formaldehyde foam insulating material

    Microsoft Academic Search

    R. Weil; A. Graviano; K. Sheppard

    1980-01-01

    Two tests of the corrosiveness of urea-formaldehyde (UF) foam insulating materials were compared. One test, the Timm test, had test coupons foamed in place. In the second, the Canadian test, blocks of foam already set were placed in contact with test coupons. The Timm test uses 10 gage thick coupons, while the Canadian test specifies 3 mil thick ones. Two

  5. Effect of alternative pathway therapy on branched chain amino acid metabolism in urea cycle disorder patients

    Microsoft Academic Search

    Fernando Scaglia; Susan Carter; William E O’Brien; Brendan Lee

    2004-01-01

    Urea cycle disorders (UCDs) are a group of inborn errors of hepatic metabolism caused by the loss of enzymatic activities that mediate the transfer of nitrogen from ammonia to urea. These disorders often result in life-threatening hyperammonemia and hyperglutaminemia. A combination of sodium phenylbutyrate and sodium phenylacetate\\/benzoate is used in the clinical management of children with urea cycle defects as

  6. Relationships Between Urea Dilution Measurements and Body Weight and Composition of Lactating Dairy Cows

    Microsoft Academic Search

    R. E. Agnew; T. Yan; W. J. McCaughey; J. D. McEvoy; D. C. Patterson; M. G. Porter; R. W. J. Steen

    2005-01-01

    The objective of the present study was to investigate the potential of the urea dilution technique, coupled with live animal measures to predict the body compo- nents of dairy cattle. The study involved 104 lactating Holstein-Friesian cows offered grass silage-based diets. Urea space volume (USV) was calculated from 2 collec- tion periods of blood samples following infusion of urea at

  7. 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...

  8. Inhibition of Smooth Muscle Proliferation by Urea-Based Alkanoic Acids via Peroxisome Proliferator-Activated

    E-print Network

    Hammock, Bruce D.

    Inhibition of Smooth Muscle Proliferation by Urea-Based Alkanoic Acids via Peroxisome Proliferator cell proliferation. We examined the possibility that urea-based alkanoic acids activate the nuclear--These results show that attenuation of smooth muscle cell proliferation by urea-based alkanoic acids is mediated

  9. Role of urea in the postprandial urine concentration cycle of the insectivorous bat Antrozous pallidus.

    PubMed

    Bassett, John E

    2004-02-01

    Insectivorous bats, which feed once daily, produce maximally concentrated urine only after feeding. The role of urea as an osmolyte in this process was investigated in pallid bats (Antrozous pallidus) in the laboratory. Following a 24-h fast, plasma and urine were sampled before and 2 h after feeding in postprandial (PP) animals and before and 2 h after similar treatment without feeding in nonfed (NF) animals. Food consumption by PP animals and handling of NF animals had no effect on blood water content as measured by hematocrit and plasma oncotic pressure. Food consumption increased both plasma osmolality (P(osm)) and plasma urea (P(urea)) by as much as 15%. Food consumption also increased urine osmolality (U(osm)) and urine urea (U(urea)) by 50-100%. Feeding increased U(osm) regardless of changes in P(osm), and elevation of U(osm) resulted primarily from increased U(urea). In NF bats, P(osm) and P(urea) were unchanged, while U(osm) and U(urea) increased by as much as 25%. Again, increased U(osm) resulted primarily from increased U(urea). The PP urine concentration cycle of pallid bats resulted from increased urea excretion in response to apparent rapid urea synthesis. Bats rapidly metabolized protein and excreted urea following feeding when body water was most plentiful. PMID:15123201

  10. Allophanate hydrolase of Oleomonas sagaranensis involved in an ATP-dependent degradation pathway specific to urea

    Microsoft Academic Search

    Takeshi Kanamori; Norihisa Kanou; Shingo Kusakabe; Haruyuki Atomi; Tadayuki Imanaka

    2005-01-01

    The first prokaryotic urea carboxylase has previously been purified and characterized from Oleomonas sagaranensis. As the results indicated the presence of an ATP-dependent urea degradation pathway in Bacteria, the characterization of the second component of this pathway, allophanate hydrolase, was carried out. The gene encoding allophanate hydrolase was found adjacent to the urea carboxylase gene. The purified, recombinant enzyme exhibited

  11. 75 FR 78243 - Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ...EPA-HQ-OPP-2010-0650; FRL-8855-5] Propionic Acid and Salts, Urea Sulfate, Methidathion...decisions for the pesticides propionic acid and salts, case no. 4078, urea sulfate...pesticides in the table below--propionic acid and salts, case 4078, urea...

  12. Effects of Urea Infusion on the Uterine Luminal Environment of Dairy Cows

    Microsoft Academic Search

    M. L. Rhoads; R. O. Gilbert; M. C. Lucy; W. R. Butler

    2004-01-01

    Previous research indicates that high plasma urea nitrogen (PUN) concentrations are associated with de- creased fertility in lactating dairy cows. The objective of this study was to monitor changes in the uterine environment during acute elevation of PUN. Lactating dairy cows (n = 8) were infused with saline or urea (0.01 g of urea\\/h per kg of body weight) through

  13. 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...

  14. 75 FR 51440 - Solid Urea from the Russian Federation: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-20

    ...solid urea from the Russian Federation. The...review was produced and exported by MCC...in the ``Issues and Decision Memorandum...Solid Urea from the Russian Federation for the...solid urea from the Russian Federation produced and exported by...

  15. Crystal Structure of Urea Carboxylase Provides Insights into the Carboxyltransfer Reaction*S

    E-print Network

    Tong, Liang

    , fungi, algae, and bacteria possess an enzymatic activity that converts urea to ammonium, enabling them in many bacteria, algae, and fungi and catalyzes the conversion of urea to allophanate, an essential step. In the digestive tracts of many ani- mals, the residing microbes utilize urea from the host to pro- duce biomass

  16. Urea cycling and ammonia absorption in vivo in the digestive tract of the rat

    E-print Network

    Paris-Sud XI, Université de

    Urea cycling and ammonia absorption in vivo in the digestive tract of the rat C. DEMIGNÉ C. RÉMÉSY. The transfer of blood urea into the digestive tract and ammonia absorption at that site have been studied in vivo in anesthetized rats. The vein-artery differences in urea and ammonia absorption were greater

  17. Streamflow Routing: International Edition

    NSDL National Science Digital Library

    2014-09-14

    Streamflow routing provides a set of methods for describing and predicting the movement of water from one point to another along a river. Typically, this process involves predicting the shape of a hydrograph downstream from a particular location in a channel, reservoir, or lake. This first requires an understanding of the basic flow regimes and how water is stored and released within a channel. From there, information and calculations based on flow and channel bed characteristics are implemented in hydrologic routing methods, which are storage-based, and hydraulic routing methods, which utilize fully-dynamic equations. This module offers a thorough introduction to these routing concepts and processes through illustrations, animations and sample exercises, with a primary focus on hydrologic routing methods.

  18. Four Lectures on Turbulent Combustion

    E-print Network

    Peters, Norbert

    Four Lectures on Turbulent Combustion N. Peters Institut f¨ur Technische Mechanik RWTH Aachen Turbulent Combustion: Introduction and Overview 1 1.1 Moment Methods in Modeling Turbulence with Combustion and Velocity Scales . . . . . . . . . . . 11 1.4 Regimes in Premixed Turbulent Combustion

  19. Sandia Combustion Research: Technical review

    SciTech Connect

    NONE

    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. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    Microsoft Academic Search

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-01-01

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization.

  1. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    Microsoft Academic Search

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2002-01-01

    The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization.

  2. 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.

  3. Consider Compressed Combustion

    E-print Network

    Crowther, R. H.

    1982-01-01

    , and costs. In addition, overall advantages for applications involving energy sharing, such as cogeneration are even greater. Thus, compressed combustion should be considered seriously as an economical alternative to conventional heaters, especially in energy...

  4. Consider Compressed Combustion 

    E-print Network

    Crowther, R. H.

    1982-01-01

    , and costs. In addition, overall advantages for applications involving energy sharing, such as cogeneration are even greater. Thus, compressed combustion should be considered seriously as an economical alternative to conventional heaters, especially in energy...

  5. Internal combustion engines and method of operating an internal combustion engine using staged combustion

    Microsoft Academic Search

    1991-01-01

    A method of operating an internal combustion engine with a split chamber design for stage combustion comprising the steps of: forming at least one primary combustion chamber and at least one secondary combustion chamber in association with a cylinder means having at least two regions formed therein and piston means within the engine, causing air within the cylinder means to

  6. Combustion and Emissions

    NSDL National Science Digital Library

    A flickering candle lights the way for a scientific investigation. This lesson uses hands-on demonstrations and web-based presentations to explore the science of combustion. Students become environmental experts as they learn about combustion emissions and how they affect human health and the environment. The lesson would be useful for physics and chemistry for grades 7-12 and would take multiple class periods to cover in full.

  7. Generalities on combustion instabilities

    NASA Astrophysics Data System (ADS)

    Kuentzmann, Paul

    The main manifestations of combustion instabilities are reviewed, and the specific characteristics of instabilities in solid-propellant rocket engines are analyzed, with the Minuteman III third-stage engine and the SRB engine of Titan 34 D considered as examples. The main approaches for predicting combustion instabilities are discussed, including the linear approach based on the acoustic balance, the nonlinear mode-coupling approach, and the nonlinear approach using numerical calculation. Projected directions for future research are also examined.

  8. Self-propagating high-temperature (combustion) synthesis (SHS) of powder-compacted materials

    Microsoft Academic Search

    H. C. Yi; J. J. Moore

    1990-01-01

    Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique currently being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. At the same time, the rapid heating and

  9. 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

  10. Combustible gas sensor

    SciTech Connect

    Vaughn, E.D.; Creason, S.C.

    1993-07-06

    In a combustible gas sensor having a housing defining an interior containing an electrically conductive reference element and an electrically conducting measurement element coated with a catalyst for the catalytic combustion of a combustible gas and circuitry for measuring the difference in resistance between said measurement element and said reference element as they are heated by combustion of said combustible gas and means for measuring the difference in resistance between said measurement element and said reference element thereby to determine the quantity of combustible gas in a sample, the improvement is described comprising: maintaining said reference element and said measurement element in a common confined space for direct fluid communication therebetween wherein said reference element and said measurement element are disposed in one end of a housing member, a disk having an upper and a lower surface and a slot opening in said lower surface is disposed in said one end of said housing with said reference element and said measurement element being received in said slot and said disk having means for introducing gaseous sample to be tested into said slot whereby said gaseous sample freely communicates with both the said reference element and said measurement element.

  11. METC Combustion Research Facility

    SciTech Connect

    Halow, J.S.; Maloney, D.J.; Richards, G.A.

    1993-11-01

    The objective of the Morgantown Energy Technology Center (METC) high pressure combustion facility is to provide a mid-scale facility for combustion and cleanup research to support DOE`s advanced gas turbine, pressurized, fluidized-bed combustion, and hot gas cleanup programs. The facility is intended to fill a gap between lab scale facilities typical of universities and large scale combustion/turbine test facilities typical of turbine manufacturers. The facility is now available to industry and university partners through cooperative programs with METC. High pressure combustion research is also important to other DOE programs. Integrated gasification combined cycle (IGCC) systems and second-generation, pressurized, fluidized-bed combustion (PFBC) systems use gas turbines/electric generators as primary power generators. The turbine combustors play an important role in achieving high efficiency and low emissions in these novel systems. These systems use a coal-derived fuel gas as fuel for the turbine combustor. The METC facility is designed to support coal fuel gas-fired combustors as well as the natural gas fired combustor used in the advanced turbine program.

  12. Sandia Combustion Research Program

    SciTech Connect

    Johnston, S.C.; Palmer, R.E.; Montana, C.A. (eds.)

    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.

  13. Coal combustion system

    DOEpatents

    Wilkes, Colin (Lebanon, IN); Mongia, Hukam C. (Carmel, IN); Tramm, Peter C. (Indianapolis, IN)

    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.

  14. 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.

  15. 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

  16. 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

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

    PubMed Central

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

    2012-01-01

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

  18. 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

  19. Internal combustion engines and method of operating an internal combustion engine using staged combustion

    SciTech Connect

    Stanley, R.S.

    1991-12-31

    A method of operating an internal combustion engine with a split chamber design for stage combustion comprising the steps of: forming at least one primary combustion chamber and at least one secondary combustion chamber in association with a cylinder means having at least two regions formed therein and piston means within the engine, causing air within the cylinder means to flow through the at least one primary combustion chamber at a predetermined rate and volume; admitting a predetermined amount of fuel to the at least one primary combustion chamber to form a fuel/air mixture, therein; igniting the fuel/air mixture within the at least one primary combustion chamber to generate a first stage of combustion; causing the flow of the the ignited fuel/air mixture to the at least one secondary combustion chamber for continued burning of the fuel/air mixture in a second stage of combustion within the at least one secondary combustion chamber. This patent also describes a split chamber, staged combustion internal combustion engine. It comprises means defining a cylinder having at least two regions formed therein, piston means; combustion chambers; fuel delivery means; and means for igniting the fuel in the primary combustion chamber.

  20. Effect of additives on the WGS activity of combustion synthesized CuO\\/CeO 2 catalysts

    Microsoft Academic Search

    T. Tabakova; V. Idakiev; J. Papavasiliou; G. Avgouropoulos; T. Ioannides

    2007-01-01

    This paper presents a study on the role of additives (samaria, lanthana, zirconia, and zinc oxide) to ceria as a support of copper catalysts for low-temperature WGSR. A single-step urea-combustion procedure was used for preparation of highly active catalysts. The results revealed the beneficial role of Sm2O3 and ZnO doping in increasing BET surface area and total pore volume of

  1. VOC oxidation over MnO x –CeO 2 catalysts prepared by a combustion method

    Microsoft Academic Search

    Dimitrios Delimaris; Theophilos Ioannides

    2008-01-01

    MnOx–CeO2 catalysts were prepared by a urea combustion method and their performance in the oxidation of ethanol, ethyl acetate and toluene was evaluated. XRD, XPS, H2-TPR and N2 physisorption were employed in catalyst characterization. Mn2+ and Mn3+ ions are present in the catalysts. In ceria-rich materials, crystalline manganese oxide phases are absent and Mn ions are homogeneously distributed between the

  2. Enhancement of urea, ammonia and carbon dioxide removal from industrial wastewater using a cascade of hydrolyser–desorber loops

    Microsoft Academic Search

    M. R. Rahimpour; H. R. Mottaghi; M. M. Barmaki

    2010-01-01

    In this study, removal of urea, ammonia and carbon dioxide from wastewater of conventional urea plant in both high and low concentration (ppm scale) levels using a cascade of hydrolyser–desorber loops has been investigated. In conventional urea plants, wastewater treatment sections including co-current configuration of hydrolyser were designed according to the old environmental standards. Nevertheless, the amounts of urea and

  3. Rotary internal combustion engine

    SciTech Connect

    Murray, J.L.

    1993-07-20

    A multi bank power plant is described comprising at least a first and a second rotary internal combustion engine connectable together in series, each of the engines comprising: a housing; a cam track internally disposed within the housing and adapted to receive a cam follower; an engine block disposed within the housing and rotatable about a central axis; an output shaft extending axially from each the engine block, each output shaft being coaxial with the other; means for coupling the output shafts together so that the output shafts rotate together in the same direction at the same speed; at least one radially arranged cylinder assembly on each block, each cylinder assembly including a cylinder having a longitudinal axis extending generally radially outwardly from the rotational axis of the block, the cylinder including means defining an end wall, a piston member disposed within the cylinder and adapted to reciprocate within the cylinder; a combustion chamber, means permitting periodic introduction of air and fuel into the combustion chamber, means for causing combustion of a compressed mixture of air and fuel within the combustion chamber, means permitting periodic exhaust of products of combustion of air and fuel from the combustion chamber, and means for imparting forces and motions of the piston within the cylinder to and from the cam track, the means comprising a cam follower operatively connected to the piston; wherein the cam track includes at least a first segment and at least a second segment thereof, the first segment having a generally positive slope wherein the segment has a generally increasing radial distance from the rotational axis of the engine block whereby as a piston moves outwardly in a cylinder on a power stroke while the cam follower is in radial register with the cam track segment, the reactive force of the respective cam follower against the cam track segment acts in a direction tending to impart rotation to the engine block.

  4. Proactive route maintenance in DSR

    Microsoft Academic Search

    Liang Qin; Thomas Kunz

    2002-01-01

    Most existing on-demand mobile ad hoc network routing protocols continue using a route until a link breaks. During the route reconstruction, packets can be dropped, which may cause significant throughput degradation. In this paper, we add a link breakage prediction algorithm to the Dynamic Source Routing (DSR) protocol. The mobile node uses signal power strength from the received packets to

  5. WhatRoute

    NSDL National Science Digital Library

    Christianson, Bryan

    2012-07-28

    How does your data travel? It's a great question, and one that can be answered via the use of WhatRoute. This application is a network diagnostic utility that allows users to see the geographical route of the paths that packets from your computer take as they traverse the Internet. The results can also be viewed via Google Earth, which is quite a dramatic experience. This version is compatible with computers running Mac OS X and newer.

  6. Route Award Considerations

    NASA Technical Reports Server (NTRS)

    Rogers, W. D., Jr.

    1972-01-01

    The organization, responsibilities, and functions of the Civil Aeronautics Board are discussed. Several examples of decisions made by the Civil Aeronautics Board on the award of specific air routes to competing air lines are presented. The manner in which route proceedings are initiated and examined is explained. Recommendations are made concerning actions which can be taken to improve the services provided to the flying public.

  7. Ordered interval routing schemes

    Microsoft Academic Search

    Mustaq Ahmed

    2009-01-01

    Abstract An Interval Routing Scheme (IRS) represents the routing tables in a network in a space-ecient,way by labeling each vertex with an unique integer address and the outgoing edges at each vertex with disjoint subintervals of these addresses. An IRS that has at most k intervals per edge label is called a k-IRS. In this thesis, we propose a new

  8. Industrial Vehicle Routing

    Microsoft Academic Search

    Geir Hasle; Oddvar Kloster

    Solving the Vehicle Routing Problem (VRP) is a key to efficiency in transportation and supply chain management. The VRP is\\u000a an NP-hard problem that comes in many guises. The VRP literature contains thousands of papers, and VRP research is regarded\\u000a as one of the great successes of OR. Vehicle routing decision support tools provide substantial savings in society every day,

  9. Model selection for urea kinetics in dialysis therapy

    Microsoft Academic Search

    F. Grandi; G. Avanzolini; A. Cappello; A. Santoro

    1993-01-01

    Single- and doublepi modeh of U- The parameters characterizing Model 1 are the urea kinetics during dialysis therapy are compared on the Production, G,, and the initial total volume, vo while basis of simulated and experimental data. The adopted initial condition is estimated by x(O)=C(O)\\/v,. criterium includes descriptive ability, accuracy of Fig.lb shows the second-order model (Model 2) where parameter

  10. Zinc oxide-chitosan nanobiocomposite for urea sensor

    Microsoft Academic Search

    Pratima R. Solanki; Ajeet Kaushik; Anees A. Ansari; G. Sumana; B. D. Malhotra

    2008-01-01

    Zinc oxide (ZnO)-chitosan (CH) nanobiocomposite film onto indium-tin-oxide (ITO) coated glass has been used to immobilize urease (Urs) and glutamate dehydrogenase (GLDH) for urea detection. The presence of ZnO nanoparticles in CH results in its increased surface area and enhanced electron transfer kinetics. The Urs-GLDH\\/CH-ZnO\\/ITO bioelectrode characterized using electrochemical, Fourier transform infrared, and scanning electron microscopy studies exhibit linearity of

  11. Odor evaluation of fatty methyl esters purified as urea adducts

    Microsoft Academic Search

    G. R. List; R. L. Hoffmann; Helen A. Moser; C. D. Evans

    1967-01-01

    Volatile oxidative cleavage products which are present in distilled fatty methyl esters make them unsuitable starting-materials\\u000a for odor evaluation studies. Sensory evaluation of treated and untreated esters shows that crystallization with urea removes\\u000a undersirable odor constituents which result from autoxidation, metal-catalyzed oxidation, light exposure, and distillation.\\u000a The method is simple and by clathrate formation gives, in high yields, pure fatty

  12. 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.

  13. Environmentally conscious coal combustion

    SciTech Connect

    Hickmott, D.D.; Brown, L.F.; Currier, R.P. [and others

    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.

  14. Internal combustion engine

    SciTech Connect

    Nyc, W.

    1991-06-25

    This patent describes an internal combustion engine. It comprises a tubular, annular cylinder having combustion ports positioned 180 degrees apart; a first piston set comprising a pair of piston heads connected by a shaft and facing in opposite directions, the first piston set being contained within the annular cylinder between the combustion ports, where the first piston set is adapted to travel in a reciprocating motion within one half of the annular cylinder; a second piston set comprising a pair of piston heads connected by a shaft and facing in opposite directions, the second piston set being contained within the annular cylinder between the combustion ports on the opposite side from the first piston set, where the second piston set is adapted to travel in a reciprocating motion within the opposite half of the annular cylinder such that both the first piston set and the second piston set approach one of the combustion ports at the same time; a rotating pawl shaft centered on the central axis of the annular cylinder, the pawl shaft having two pawls directly attached and extending radially from the pawl shaft, where the pawls face in opposite directions; a rotating pawl sleeve encircling the rotating shaft, the pawl sleeve having two pawls directly attached and extending radially from the pawl sleeve, where the pawls face in opposite directions.

  15. 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).

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

    DOEpatents

    Daniels, Michael A. (Idaho Falls, ID); Heaps, Ronald J. (Idaho Falls, ID); Steffler, Eric D (Idaho Falls, ID); Swank, William D. (Idaho Falls, ID)

    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.

  17. External combustion engine having a combustion expansion chamber

    NASA Astrophysics Data System (ADS)

    Duva, Anthony W.

    1993-03-01

    This patent application discloses an external combustion engine having a combustion expansion chamber. The engine includes a combustion chamber for generating a high-pressure, energized gas from a monopropellant fuel, and a cylinder for receiving the energized gas through a rotary valve to perform work on a cylinder disposed therein. A baffle plate is positioned between the combustion area and expansion area for reducing the pressure of the gas. The combustion area and expansion area are separated by a baffle plate having a flow area which is sufficiently large to eliminate the transmission of pressure pulsations from the combustion area to the expansion area while being small enough to provide for substantially complete combustion in the combustion area. The engine is particularly well suited for use in a torpedo.

  18. Simple and sensitive determination of urea in serum and urine.

    PubMed

    Orsonneau, J L; Massoubre, C; Cabanes, M; Lustenberger, P

    1992-05-01

    In this method for serum and urinary urea determination, the same reagent is used without predilution of urine samples. The method is based on the pH increase resulting from the ammonia released by urease hydrolysis of urea. o-Cresolphthalein complexone is used to monitor the pH change colorimetrically. Urea concentration and absorbance at 570 nm are linearly related for concentrations as great as 600 mmol/L for urine samples and 100 mmol/L for serum. There are no clinically significant interferences from physiological substances or drugs, and precision and accuracy are excellent (CV approximately 2%, except at very low concentrations in serum; analytical recovery was 99% in urine, 100% in serum). Results by this method (y) and by the Astra method (x) for urine correlated well (y = 0.991x - 2.87, Sy/x = 9.21, r = 0.994), as did the results by this method and by the total enzymatic method (x') for serum (y = 1.002x' + 0.192, Sy/x' = 0.598, r = 0.997). This method is applicable to automated as well as manual instruments, and one-reagent or two-reagent formats can be used. PMID:1582010

  19. 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

  20. Rigid urea and self-healing thiourea ethanolamine monolayers.

    PubMed

    Stefaniu, Cristina; Zaffalon, Pierre-Léonard; Carmine, Alessio; Verolet, Quentin; Fernandez, Samuel; Wesolowski, Tomasz A; Brezesinski, Gerald; Zumbuehl, Andreas

    2015-02-01

    A series of long-tail alkyl ethanolamine analogs containing amide-, urea-, and thiourea moieties was synthesized and the behavior of the corresponding monolayers was assessed on the Langmuir-Pockels trough combined with grazing incidence X-ray diffraction experiments and complemented by computer simulations. All compounds form stable monolayers at the soft air/water interface. The phase behavior is dominated by strong intermolecular headgroup hydrogen bond networks. While the amide analog forms well-defined monolayer structures, the stronger hydrogen bonds in the urea analogs lead to the formation of small three-dimensional crystallites already during spreading due to concentration fluctuations. The hydrogen bonds in the thiourea case form a two-dimensional network, which ruptures temporarily during compression and is recovered in a self-healing process, while in the urea clusters the hydrogen bonds form a more planar framework with gliding planes keeping the structure intact during compression. Because the thiourea analogs are able to self-heal after rupture, such compounds could have interesting properties as tight, ordered, and self-healing monolayers. PMID:25594235

  1. 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.

  2. PROACTIVE ROUTE MAINTENANCE IN DSR

    Microsoft Academic Search

    Liang Qin

    2001-01-01

    Existing on-demand ad hoc network routing protocols continue using a route until a linkbreaks. During the route reconstruction, packets can be dropped, which will causesignificant throughput degradation. In this thesis, we add a link breakage predictionalgorithm to one on-demand routing protocol: the Dynamic Source Routing (DSR)protocol. The mobile node that implements the prediction algorithm uses signal powerstrength from the received

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

    Microsoft Academic Search

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

    1995-01-01

    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 (Jnetamm; 85%) and urea (Jneturea; 74%) excretion occurred across the gill, with the remainder excreted across the skin, the

  4. Internal combustion engine squish jet combustion chamber

    SciTech Connect

    Evans, R.L.

    1986-02-25

    This patent describes a internal combustion engine block having a piston and cylinder head, one of which has: (a) a substantially cylindrical bowl opening into the face thereof; (b) a pair of squish jet passages having respective inlets communicating with the face thereof, and respective, transversely spaced, outlets directed substantially tangentially into the bowl, the outlet of a first one of the pair being directed upwardly, and the outlet of second one of the pair being directed downwardly from a position above the outlet of the first one, so that a counter-rotating, bilevel swirl can be produced in the bowl by the squish jet outlets.

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

    PubMed

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

    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 232nM. 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 150mM 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

  6. 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

  7. Hybrid rocket combustion study

    NASA Technical Reports Server (NTRS)

    Strand, L. D.; Ray, R. L.; Cohen, N. S.

    1993-01-01

    The objectives of this study of 'pure' or 'classic' hybrids are to (1) extend our understanding of the boundary layer combustion process and the critical engineering parameters that define this process, (2) develop an up-to-date hybrid fuel combustion model, and (3) apply the model to correlate the regression rate and scaling properties of potential fuel candidates. Tests were carried out with a hybrid slab window motor, using several diagnostic techniques, over a range of motor pressure and oxidizer mass flux conditions. The results basically confirmed turbulent boundary layer heat and mass transfer as the rate limiting process for hybrid fuel decomposition and combustion. The measured fuel regression rates showed good agreement with the analytical model predictions. The results of model scaling calculations to Shuttle SRM size conditions are presented.

  8. 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.

  9. Droplet Combustion Experiment

    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-1R mission (STS-94, July 1-17 1997). Advanced combustion experiments will be a part of investigations plarned for the International Space Station. (120KB JPEG, 655 x 736 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300167.html.

  10. 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.

  11. Internal combustion rotary engine

    SciTech Connect

    Chen, S.P.

    1993-08-24

    An internal combustion rotary engine is described comprising: an internal combustion chamber wherein a combustible fuel-air mixture is ignited for producing a driving gas flow; a central rotor having an outer surface in which at least one group of curved channels circumferentially-and-axially extending without radially extending through the central rotor; and at least one annular rotor each enclosing the central rotor having an inner surface in which a corresponding number of curved channels circumferentially-and-axially extending without radially extending through the annular rotor; when the curved channels in the central rotor communicate with the curved channels in the annular rotor, the driving gas flow circumferentially-and-axially passing between the outer surface of the central rotor and the inner surface of the annular rotor for rotating the central rotor and the annular rotor in opposite directions.

  12. Internal combustion engine

    DOEpatents

    Baker, Quentin A. (P.O. Box 6477, San Antonio, TX 78209); Mecredy, Henry E. (1630-C W. 6th, Austin, TX 78703); O'Neal, Glenn B. (6503 Wagner Way, San Antonio, TX 78256)

    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.

  13. 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.

  14. Internal combustion engine with two-stage combustion chamber

    Microsoft Academic Search

    Sertich

    1991-01-01

    This patent describes an improvement in an internal combustion engine of the type in which a piston reciprocates within a cylinder toward a top dead center position to compress a charge of fuel within a combustion chamber, within which combustion chamber the charge is ignited by ignition means so as to burn and drive the piston away from the top

  15. Low emission combustion system for internal combustion engines

    Microsoft Academic Search

    M. A. Paul; A. Paul

    1991-01-01

    This patent describes a combustion system for internal combustion engines having a cylinder and at least one piston reciprocal in the cylinder. It comprises a combustion chamber having the regions wherein the piston has a piston head with an outer perimeter portion, a central recessed portion and a baffle with convergent radial slots over the recessed portion, the piston cooperation

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

    PubMed Central

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

    2012-01-01

    Background Patients with chronic kidney disease (CKD) need regular monitoring, usually by blood urea and creatinine measurements, needing venepuncture, frequent attendances and a healthcare professional, with significant inconvenience. Noninvasive monitoring will potentially simplify and improve monitoring. We tested the potential of transdermal reverse iontophoresis of urea in patients with CKD and healthy controls. Methods Using a MIC 2® Iontophoresis Controller, reverse iontophoresis was applied on the forearm of five healthy subjects (controls) and 18 patients with CKD for 3–5 h. Urea extracted at the cathode was measured and compared with plasma urea. Results Reverse iontophoresis at 250 ?A was entirely safe for the duration. Cathodal buffer urea linearly correlated with plasma urea after 2 h (r = 0·82, P < 0·0001), to 3·5 h current application (r = 0·89, P = 0·007). The linear equations y = 0·24x + 1 and y = 0·21x + 4·63 predicted plasma urea (y) from cathodal urea after 2 and 3 h, respectively. Cathodal urea concentration in controls was significantly lower than in patients with CKD after a minimum current application of 2 h (P < 0·0001), with the separation between the two groups becoming more apparent with longer application (P = 0·003). A cathodal urea cut-off of 30 ?M gave a sensitivity of 83·3% and positive predictive value of 87% CKD. During haemodialysis, the fall in cathodal urea was able to track that of blood urea. Conclusion Reverse iontophoresis is safe, can potentially discriminate patients with CKD and healthy subjects and is able to track blood urea changes on dialysis. Further development of the technology for routine use can lead to an exciting opportunity for its use in diagnostics and monitoring. PMID:22409780

  17. 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...

  18. 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)

  19. Heat regenerative external combustion engine

    NASA Astrophysics Data System (ADS)

    Duva, Anthony W.

    1993-03-01

    It is an object of the invention to provide an external combustion expander-type engine having improved efficiency. It is another object of the invention to provide an external combustion engine in which afterburning in the exhaust channel is substantially prevented. Yet another object of the invention is to provide an external combustion engine which is less noisy than an external combustion engine of conventional design. These and other objects of the invention will become more apparent from the following description. The above objects of the invention are realized by providing a heat regenerative external combustion engine. The heat regenerative external combustion engine of the invention comprises a combustion chamber for combusting a monopropellant fuel in order to form an energized gas. The energized gas is then passed through a rotary valve to a cylinder having a reciprocating piston disposed therein. The gas is spent in moving the piston, thereby driving a drive shaft.

  20. 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. ...

  1. 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.

  2. Thermal ignition combustion system

    DOEpatents

    Kamo, Roy (Columbus, IN); Kakwani, Ramesh M. (Columbus, IN); Valdmanis, Edgars (Columbus, IN); Woods, Melvins E. (Columbus, IN)

    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.

  3. 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.

  4. Ideal combustion of solid fuels

    SciTech Connect

    Ling, S.C.; Pao, H.P.

    1988-01-01

    Unlike the unstable, runaway, combustion of micro-fuel particles, solid fuel in the reconstituted form of a specifically shaped charge was found to have stable and ideal combustion characteristics suitable for the automatic control of combustion rate and temperature. Consequently, most environmental and operational problems associated with the atomized-combustion process can be eliminated. The shaped-charge fuel is applicable for both large power generation as well as for small home heating. 1 ref., 3 figs.

  5. Reversed flow fluidized-bed combustion apparatus

    DOEpatents

    Shang, Jer-Yu (Fairfax, VA); Mei, Joseph S. (Morgantown, WV); Wilson, John S. (Morgantown, WV)

    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.

  6. Electrical properties of Ni\\/YSZ cermets obtained through combustion synthesis

    Microsoft Academic Search

    U Anselmi-Tamburini; G Chiodelli; M Arimondi; F Maglia; G Spinolo; Z. A Munir

    1998-01-01

    The synthesis of Ni\\/YSZ cermet with controlled microstructural characteristics presents a lot of interest for many solid-state electrochemical applications. These materials are generally obtained by reducing poorly sintered mixtures of YSZ with nickel oxide by hydrogen. We recently proposed an alternative route based on a thermite reaction performed in a combustion regime. This method makes it possible, in one step,

  7. Combustion and pollution control system

    Microsoft Academic Search

    Lindberg

    1983-01-01

    A controlled amount of a fluid (steam or water or a solution of water plus additives) is injected into an internal combustion engine to improve combustion, efficiency, and to reduce emissions. The amount of the fluid injected is controlled in response to engine need. The steam is generated by the heat produced by the engine. Combustion gas temperature is used

  8. Combustion and pollution control system

    Microsoft Academic Search

    Lindberg

    1984-01-01

    A controlled amount of a fluid (steam or water or a solution of water plus additives) is injected into an internal combustion engine to improve combustion, efficiency, and to reduce emissions. The amount of the fluid injected is controlled in response to engine need. The steam is generated by the heat produced by the engine. Combustion gas temperature is used

  9. Packed Bed Combustion: An Overview

    E-print Network

    Hallett, William L.H.

    Packed Bed Combustion: An Overview William Hallett Dept. of Mechanical Engineering Université d'Ottawa - University of Ottawa #12;Packed Bed Combustion - University of Ottawa - CICS 2005 Introduction air fuel feedproducts xbed grate Packed Bed Combustion: fairly large particles of solid fuel on a grate, air supplied

  10. 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.

  11. [Use of the Lachema Bio-La-Test for the determination of urea in milk].

    PubMed

    Zelený, J; Síchová, J

    1987-07-01

    The content of urea in milk was studied as a parameter of dairy cow nutrition. It is possible to use for the analysis whole milk where the values are lower by 5.96% than in defatted milk (this fact must be borne in mind when the results are interpreted). Protein can be removed from whole milk within 24 hours after sampling provided that it was placed in a refrigerator within four hours from milking to be stored there at 4 degrees C. In such a case the decrease in urea level is not greater than 4%. No significant differences were found between urea concentration in milk collected by stripping and that in bulk milk. It is not recommended to take samples at the end of milking because such milk contains less urea. Urea concentration in the bulk milk samples corresponds to the average urea concentration in the milk samples taken from dairy cows in the stable. PMID:3116744

  12. 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 90days) 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 173L/kgVS, 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

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

    NASA Astrophysics Data System (ADS)

    Ying, Hanze; Zhang, Yanfeng; Cheng, Jianjun

    2014-02-01

    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-urea)s 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.

  14. A modified manual method for the determination of urea in seawater using diacetylmonoxime reagent

    NASA Astrophysics Data System (ADS)

    Mulvenna, Pamela F.; Savidge, Graham

    1992-05-01

    A manual method for the quantitative determination of urea in seawater was developed based on the reaction of urea with diacetylmonoxime. Critical factors include the treatment of collection bottles, sample storage, pre-filtration techniques, water purification, reaction temperature and reproducible cooling of samples during analysis. The limit of detection was 0·14 ?g-at urea-N 1 -1 with Beer's Law being obeyed in the range tested of 0-15 ?g-at urea-N 1 -1. The precision (±1 SD) of replicate samples of 1,2 and 15 ?g-at urea-N 1 -1 was 0·024, 0·019 and 0·03 ?g-at urea-N 1 -1 ( n = 10) respectively.

  15. Trypsin-inspired poly(urethane-urea)s based on poly-lysine oligomer segment.

    PubMed

    Gu, Zhenqian; Wang, Fangjie; Lu, Haoxiang; Wang, Xinling; Zheng, Zhen

    2015-01-01

    A new kind of biodegradable poly(urethane-urea)s based on poly-lysine oligomer used as the soft segment was synthesized and characterized. In vitro degradation behavior of poly (urethane-urea)s was investigated, and was assessed by (1)H NMR and mass loss. The results indicated that the peptide bonds in poly(urethane-urea)s were effectively cleaved in simulated pancreatic juice containing trypsin, while those in buffer solution without trypsin remained unaffected. The degradability was obviously improved by introducing poly-lysine oligomer into the main chain of poly(urethane-urea)s. The results of cells viability test indicated that the poly (urethane-urea)s showed a good biocompatibility on endothelial cells. The thermostability and hydrophilicity of poly(urethane-urea)s increased with increase in poly-lysine oligomer content. PMID:25584962

  16. 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...

  17. Internal combustion engine

    Microsoft Academic Search

    Barrett

    1980-01-01

    An internal combustion engine having a piston assembly such that gaseous flow into a cylinder is through the piston assembly and wherein all gaseous flow in a cylinder is in a single direction. The piston assembly includes inner and outer piston members which are relatively movable so as to form a gaseous passage therethrough in certain conditions. The engine also

  18. Engine combustion chamber structure

    Microsoft Academic Search

    Tanaka

    1988-01-01

    This patent describes a combustion chamber structure comprising an upper wall surface which is shaped like a pent-roof and into which an intake passage opens, a piston having on a head portion thereof a bulged portion conforming to the upper wall surface in shape, a first bowl portion which is formed substantially at the center of the bulged portion and

  19. Internal combustion engine

    Microsoft Academic Search

    M. A. Laskaris; K. Broitman; S. E. Natale

    1991-01-01

    This patent describes improvement in a two-stroke internal combustion engine adapted to run on a diesel or a kerosene type of fuel, and including a piston connected to the crankshaft of the engine to move within a cylinder through a first stroke from a top dead center position to a bottom dead center position and through a second stroke from

  20. Combined Cycle Combustion Turbines

    E-print Network

    Combined Cycle Combustion Turbines Steven Simmons February 27 2014 1 #12;CCCT Today's Discussion 1 Meeting Pricing of 4 advanced units using information from Gas Turbine World Other cost estimates from E E3 EIA Gas Turbine World California Energy Commission Date 2010 Oct 2012, Dec 2013 Apr 2013 2013 Apr

  1. Internal combustion engine

    SciTech Connect

    Lacy, J.W.

    1991-01-22

    This patent describes an internal combustion engine. It comprises: an engine block, fuel injection means; rotatable shaft means; a wobbler member; a spider assembly; a pair of bearing members; a connecting rod; means for fixing the outer end of each connection rod; means for connecting the inner end of each connecting rod; and lubrication means.

  2. Sewage sludge combustion

    Microsoft Academic Search

    J. Werther; T. Ogada

    1999-01-01

    In the current review paper, various issues related to the combustion of sewage sludge are discussed. After briefly explaining the formation and treatment of sewage sludge, current and future sludge production are discussed. Thereafter, the four sludge disposal methods which are currently used, i.e. recycling in agriculture, landfilling, dumping into sea and incineration, are examined, and the future trend presented

  3. Combustion properties of biomass

    Microsoft Academic Search

    B. M Jenkins; L. L Baxter; T. R Miles

    1998-01-01

    Properties of biomass relevant to combustion are briefly reviewed. The compositions of biomass among fuel types are variable, especially with respect to inorganic constituents important to the critical problems of fouling and slagging. Alkali and alkaline earth metals, in combination with other fuel elements such as silica and sulfur, and facilitated by the presence of chlorine, are responsible for many

  4. 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.

  5. Combustion of agricultural residues

    Microsoft Academic Search

    J. Werther; M. Saengera; E.-U. Hartge; T. Ogadab; Z. Siagi

    2000-01-01

    In the current overview paper, various issues related to the combustion of agricultural residues are discussed. Attention has been given to the problems associated with the properties of the residues such as low bulk density, low ash melting points, high volatile matter contents and the presence of nitrogen, sulfur, chlorine and sometimes high moisture contents. Consequently the issues discussed include

  6. Rotary internal combustion engine

    Microsoft Academic Search

    J. L. Murray; J. O. Mosca

    1992-01-01

    This patent describes a rotary internal combustion engine. It includes a housing; a cam track internally disposed within the housing and adapted to receive a cam follower; an engine block disposed within the housing, the engine block being relatively rotatable within the housing about a central axis; means connectable to an external drive member for translating the relative rotation of

  7. Rotary internal combustion engine

    Microsoft Academic Search

    Kollen

    1987-01-01

    This patent describes a rotary internal combustion engine operating on fuel and air, comprising: a housing having a pair of communicating parallel axis rotor chambers; a pair of parallel axis rotors, one in each rotor chamber of the housing, the rotors each having on its outer periphery circumferentially spaced axial teeth with intervening circumferentially spaced axial passages. The rotors are

  8. Rotary internal combustion engine

    Microsoft Academic Search

    Frasca

    1987-01-01

    A rotary internal combustion engine is described having: a casing; a rotor mounted for rotation in the casing with at least one power take off means to outside the engine; an annular cavity formed between the casing and the rotor about the rotor axis; a wave surface on the rotor about the rotor axis which is a boundary surface of

  9. Advanced Combustion Engineering.

    ERIC Educational Resources Information Center

    Bartholomew, Calvin H.

    1987-01-01

    Describes the development of the Advanced Combustion Engineering Research Center (ACERC), which is a cooperative project of Brigham Young University, the University of Utah, and 25 governmental and industrial research laboratories. Discusses the research objectives, the academic program, the industrial relations and technology transfer program,…

  10. 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.

  11. 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

  12. Influence of emulsions with and without urea on water-binding capacity of the stratum corneum

    Microsoft Academic Search

    M. GLOOR; W. GEHRING; W. WOLF

    This study was undertaken to delineate the effects of emulsions with and without urea on the water-binding behavior of the stratum corneum at different relative humidities (RH). The heels of 54 human volunteers were treated with water-in-oil (w\\/o), and oil-in-water (o\\/w) emulsions with and without urea (urea content 10%). After treatment the water content was determined by measuring the weight

  13. Causes, kinetics and clinical implications of post-hemodialysis urea rebound

    Microsoft Academic Search

    Luciano A Pedrini; Samir Zereik; Samir Rasmy

    1988-01-01

    Causes, kinetics and clinical implications of post-hemodialysis urea rebound. The rapid increase in end-dialysis urea concentration (Co) immediately after the end of dialysis (HD), which greatly exceeds that expected as an effect of urea generation and defined as “net rebound,” was assessed in 21 chronic HD patients. The curve of serial values of net rebound correlated (r = 0.70) with

  14. Molecular cloning of urea transporters from the kidneys of baleen and toothed whales

    Microsoft Academic Search

    Naoko Birukawa; Hironori Ando; Mutsuo Goto; Naohisa Kanda; Luis A. Pastene; Akihisa Urano

    2008-01-01

    Urea transport in the kidney is important for the production of concentrated urine. This process is mediated by urea transporters (UTs) encoded by two genes, UT-A (Slc14a2) and UT-B (Slc14a1). Our previous study demonstrated that cetaceans produce highly concentrated urine than terrestrial mammals, and that baleen whales showed higher concentrations of urinary urea than sperm whales. Therefore, we hypothesized that

  15. Juvenile amphibians do not avoid potentially lethal levels of urea on soil substrate.

    PubMed

    Hatch, A C; Belden, L K; Scheessele, E; Blaustein, A R

    2001-10-01

    We examined the effects of a forest fertilizer (urea) on newly metamorphosed terrestrial amphibians (Western toads, Bufo boreas; Cascades frogs, Rana cascadae; long-toed salamanders, Ambystoma macrodactylum; and roughskin newts, Taricha granulosa). We examined avoidance behavior of Western toads and Cascades frogs on both paper towel and soil substrates dosed with urea (control and 100 kg N/ha and an additional treatment of 50 kg N/ha for Western toads on soil substrate) and avoidance behavior of long-toed salamanders on soil substrate dosed with urea. We further examined the survival and feeding behavior of all four species exposed to urea on soil substrate (100 kg N/ha) for 5 d. Juvenile Western toads and Cascades frogs avoided paper towels dosed with urea but did not avoid urea-dosed soil substrate. However, Western toads and Cascades frogs both suffered significant mortality when exposed to urea on a soil substrate for 5 d. Furthermore, after adjusting for weight, we found that urea-exposed juvenile Western toads and Cascades frogs consumed significantly fewer prey items (crickets) compared with nonexposed control animals. Long-toed salamanders did not discriminate against soil substrate dosed with urea, and neither long-toed salamanders nor roughskin newts died or reduced prey consumption as a result of urea exposure. Juvenile amphibians may not be able to detect and avoid harmful levels of urea fertilizer on a natural substrate. Furthermore, anthropogenic stressors such as urea fertilizer can significantly reduce the survival and prey consumption of juvenile amphibians. These effects are important to consider in light of possible threats to the conservation status of many amphibian species. PMID:11596767

  16. Artificial Neural Network for accurate prediction of post-dialysis urea rebound

    Microsoft Academic Search

    A. T. Azar; Valentina E. Balas; Teodora Olariu

    2010-01-01

    Total dialysis dose (Kt\\/V) is considered to be a major determinant of morbidity and mortality in hemodialyzed patients. The continuous growth of the blood urea concentration over the 30- to 60-min period following dialysis, a phenomenon known as urea rebound, is a critical factor in determining the true dose of hemodialysis. The misestimation of the equilibrated (true) post-dialysis blood urea

  17. Fate of urea nitrogen applied to a banana crop in the wet tropics of Queensland

    Microsoft Academic Search

    P. Prasertsak; J. R. Freney; P. G. Saffigna; O. T. Denmead; B. G. Prove

    2001-01-01

    This paper reports a study in the wet tropics of Queensland on the fate of urea applied to a dry or wet soil surface under banana plants. The transformations of urea were followed in cylindrical microplots (10.3 cm diameter × 23 cm long), a nitrogen (N) balance was conducted in macroplots (3.85 m × 2.0 m) with 15N labelled urea,

  18. Urea cycle enzymes through the development of pacu ( Piaractus mesopotamicus ): the role of ornithine carbamoyl transferase

    Microsoft Academic Search

    Paulo Sérgio Monzani; Gilberto Moraes

    2008-01-01

    The present work reports the activities of urea cycle enzymes during the ontogenic development of the teleost pacu (Piaractus mesopotamicus). Urea cycle enzymes from the kidney and liver of adult fish were compared with those from the fish's embryonic phases. Samples\\u000a were evaluated over all phases of embryonic development, the larval period and alevin. Ammonia and urea concentrations were\\u000a determined

  19. Heat regenerative external combustion engine

    NASA Astrophysics Data System (ADS)

    Duva, Anthony W.

    1993-10-01

    A heat regenerative external combustion engine is disclosed. The engine includes fuel inlet means which extends along the exhaust passage and/or combustion chamber in order to preheat the fuel, To provide for preheating by gases in both the combustion chamber and the exhaust passage, the combustion chamber is arranged annularly around the drive shaft and between the cylinders. This configuration also is advantageous in that it reduces the noise of combustion. The engine of the invention is particularly well-suited for use in a torpedo.

  20. Rules of Designing Routing Metrics for Greedy, Face, and Combined Greedy-Face Routing

    Microsoft Academic Search

    Yujun Li; Yaling Yang; Xianliang Lu

    2010-01-01

    Different geographic routing protocols have different requirements on routing metric designs to ensure proper operation. Combining a wrong type of routing metrics with a geographic routing protocol may produce unexpected results, such as geographic routing loops and unreachable nodes. In this paper, we propose a novel routing algebra system to investigate the compatibilities between routing metrics and three geographic routing

  1. 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.

  2. Multihop cognitive radio networks: to route or not to route

    Microsoft Academic Search

    Hicham Khalife; Naceur Malouch; Serge Fdida

    2009-01-01

    Routing is a fundamental issue to consider when dealing with multihop cognitive radio networks. We investigate in this work, the potential routing approaches that can be employed in such adaptive wireless networks. We argue that in multihop cognitive radio environments no general routing solution can be proposed, but cognitive environments can be classified into three separate categories, each requiring specific

  3. On the Correlation between Route Dynamics and Routing Ashwin Sridharan

    E-print Network

    Moon, Sue B.

    On the Correlation between Route Dynamics and Routing Loops Ashwin Sridharan and Sue. B. Moon of routing loops be- ing formed which, coupled with the size of the network, may also last longer. Hengartner, University of Pennsylvania, Philadelphia, PA. ¤ Sue B. Moon, Sprint ATL, Burlingame, CA.¢ Christophe Diot

  4. 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

  5. Poly(Urethane–Urea) Varnishes Containing Tributyltin Groups

    Microsoft Academic Search

    Constantin Gaina; Viorica Gaina; Mariana Cristea

    2009-01-01

    New poly(urethane–urea) varnishes containing tributyltin groups were prepared by the reaction of dibenzyldiisocyanate in excess\\u000a with a macrodiol (PEGA-2000), trimethylolpropane, diethylene glycol and a bisalcohol maleimide monomer containing tributyltin\\u000a carboxylate group. Tributyltin maleimide monomers were obtained from 4-{3,4-bis[(2-hydroxyethyl)sulfanyl]-2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl}benzoic acid and bis(tributyltin) oxide. Structure of monomers and polymers was confirmed by the IR, NMR spectroscopy\\u000a and elemental analysis. The polymer films

  6. Significantly enhanced dehydrogenation properties of calcium borohydride combined with urea.

    PubMed

    Chu, Hailiang; Qiu, Shujun; Liu, Lin; Zou, Yongjin; Xiang, Cuili; Zhang, Huanzhi; Xu, Fen; Sun, Lixian; Zhou, Huaiying; Wu, Guotao

    2014-11-01

    The interaction of [BH(x)]- and [NH(x)]-containing species gives rise to molecular hydrogen and the establishment of the B-N bond. Up to now, metal amides and ammonia are the commonly used [NH(x)] sources. Herein, urea, an organic carbonyl diamide, was used to react with Ca(BH4)2. A new type of complex hydride Ca(BH4)2·4CO(NH2)2 was synthesized with release of ca. 5.2 wt% hydrogen below 250 °C. PMID:25186984

  7. Fairness in optimal routing algorithms 

    E-print Network

    Goos, Jeffrey Alan

    1988-01-01

    . Tsei Dr. Pierce E. Cantrell A study of fairness in multiple path optimal routing algorithms is discussed. Fair- ness measures are developed to evaluate multiple path routing in virtual circuit and datagram implementations. Several objective...

  8. 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.

  9. Hydrologic Flood Routing.

    ERIC Educational Resources Information Center

    Heggen, Richard J.

    1982-01-01

    Discusses a short classroom-based BASIC program which routes stream flow through a system of channels and reservoirs. The program is suitable for analyses of open channel conveyance systems, flood detention reservoirs, and combinations of the two. (Author/JN)

  10. Delayed internet routing convergence

    Microsoft Academic Search

    Craig Labovitz; Abha Ahuja; Abhijit Bose; Farnam Jahanian

    2000-01-01

    This paper examines the latency in Internet path failure, failover and repair due to the convergence properties of interdomain routing. Unlike switches in the public telephony network which exhibit failover on the order of milliseconds, our experimental measurements show that inter-domain routers in the packet switched Internet may take tens of minutes to reach a consistent view of the network

  11. Autonomic MANET Routing Protocols

    Microsoft Academic Search

    Yangcheng Huang; Sidath Handurukande; Saleem N. Bhatti

    2009-01-01

    In Mobile Ad hoc Networks (MANETs), timers have been used widely to maintain routing (state) informa- tion. The use of fixed-interval timers is simple to implement but, in practise, may be difficult to configure in dynamic operational environments, and so may give reduced perfor- mance in the presence of frequent topology changes. This paper proposes a self-tuning timer approach within

  12. CHEMICAL ROUTES TO NANOMATERIALS

    Microsoft Academic Search

    C. N. R. Rao

    Chemistry has played a major role in the synthesis and assembly of nanostructures. Thus, nanocrystals of metals, semiconducting chalcogenides and oxides of varying shapes and dimensions have been prepared by employing single-source precursors, solvothermal conditions and other soft chemical routes. A specially interesting innovation is the synthesis of ultrathin nanocrystalline films at the liquid-liquid interface. Nanowires of a variety of

  13. Delayed Internet routing convergence

    Microsoft Academic Search

    Craig Labovitz; Abha Ahuja; Abhijit Bose; Farnam Jahanian

    2001-01-01

    This paper examines the latency in Internet path failure, failover, and repair due to the convergence properties of interdomain routing. Unlike circuit-switched paths which exhibit failover on the order of milliseconds, our experimental measurements show that interdomain routers in the packet-switched Internet may take tens of minutes to reach a consistent view of the network topology after a fault. These

  14. Time Resolved FTIR Analysis of Combustion of Ethanol and Gasoline Combustion in AN Internal Combustion Engine

    NASA Astrophysics Data System (ADS)

    White, Allen R.; Sakai, Stephen; Devasher, Rebecca B.

    2011-06-01

    In order to pursue In Situ measurements in an internal combustion engine, a MegaTech Mark III transparent spark ignition engine was modified with a sapphire combustion chamber. This modification will allow the transmission of infrared radiation for time-resolved spectroscopic measurements by an infrared spectrometer. By using a Step-scan equipped Fourier transform spectrometer, temporally resolved infrared spectral data were acquired and compared for combustion in the modified Mark III engine. Measurements performed with the FTIR system provide insight into the energy transfer vectors that precede combustion and also provides an in situ measurement of the progress of combustion. Measurements were performed using ethanol and gasoline.

  15. 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

  16. 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

  17. Multi-objective routing in ATM networks 

    E-print Network

    Mennenga, Menno

    1996-01-01

    . Complete Sharing (CS) Admission Strategy 2. Hold-Hack n (HBn) Admission Strategy C. Routing Conlrol . 1. A New Congestion Measure . 2. Cost Functions . a. Min Hop Routing b. Max-Min Routing . c. Exponential Routing VI EXPERIMENTAL PROCEDURE...

  18. Onion Routing and Online Anonymity

    Microsoft Academic Search

    Matt Hooks; Jadrian Miles

    In this paper we present a technical description of onion routing, an anonymizing protocol that protects users against trac analysis. Onion routing combines the concepts of proxy redirection and layered mixed-key cryptography to hide the routing of requests from every participant in the network except the originator of the request. We also analyze the performance and potential legal threats against

  19. Certificateless Onion Routing Dario Catalano

    E-print Network

    Catalano, Dario

    Certificateless Onion Routing Dario Catalano Dipartimento di Matematica e Informatica Università di 10532 rosario@us.ibm.com ABSTRACT Onion routing protocols allow users to establish anonymous channels- posed in recent years, and TOR, a real-life implementation, provides an onion routing service

  20. Fast printed circuit board routing

    Microsoft Academic Search

    Jeremy Dion

    1987-01-01

    This paper describes the algorithms in a printed circuit board router used for fully automatic routing of high-density circuit boards. Completely automatic routing and running times of a few minutes have resulted from a new data structure for efficient representation of the routing grid, quick searches for optimal solutions, and generalizations of Lee's algorithm.

  1. Compass routing on geometric networks

    Microsoft Academic Search

    Evangelos Kranakis; Harvinder Singh; Jorge Urrutia

    1999-01-01

    this paper we study local routing algorithms on geometric networks. Formally speaking, suppose that we want to travel from a vertex s to a vertex t of a geometric network. A routing algorithm is called a local routing algorithm if it satisfies the following conditions:

  2. Cognitively Ergonomic Route Alexander Klippel

    E-print Network

    Bremen, Universität

    Cognitively Ergonomic Route Directions Alexander Klippel C R C - S p a t i a l I n f o r m a t i o principles that allow us to define what makes route directions cognitively ergonomic, technical aspects for cognitively ergonomic route directions (Denis, 1997; Lovelace, Hegarty, & Montello, 1999; Tversky & Lee, 1999

  3. BGP and RON Internet Routing

    E-print Network

    BGP and RON #12;Internet Routing Internet split into Autonomous Systems (ASes). BGP routing-4Transit Transit #12;BGP 2 things: Exporting (advertising) and Importing (picking) Routes 1 Simple this case, the Internet and BGP). RON 1 RON 2 RON 3 RON 4 #12;RON RON 1 RON 2 RON 3 RON 4 #12;RON RON 1 RON

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

    PubMed

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

    2014-07-01

    To study the effect of urea nitrogen on the ecosystem of Lake Taihu, we conducted urea and various nitrogen analysis for the water samples collected from the lake and surrounding rivers during summer. The ecological index analysis of 82 sites in rivers and lake yielded the following results: (1) The urea nitrogen contents in Taihu ranged from 0.011 to 0.161 mg x L(-1), which was high in the northwest and low in the southeast, related to the main pollution sources distribution of its drainage basin. (2) The dissolved nitrogen was dominated by inorganic nitrogen and the ratio between ammonia nitrogen and nitrate nitrogen was 5: 1. The average percentage of urea nitrogen in total nitrogen, dissolved nitrogen, dissolved organic nitrogen and bioavailable nitrogen was respectively 2.28%, 5.91%, 15.86%, and 6.22%, which showed a significant ecological function in Taihu. (3) Urea nitrogen concentration in river was more than twice that in lake, and the lake river concentration was slightly higher than the river into the lake. (3) In Taihu, there was a transformation relationship between urea nitrogen and the nitrogen in other forms. It showed that urea nitrogen had a significant positive correlation with permanganate index and the other forms of nitrogen, and a significant negative correlation with dissolved oxygen. In addition, urea nitrogen was weakly and positively correlated with chlorophyll a, while closely related to the spatial distribution of benthos and zooplankton species. All the results above showed that urea nitrogen was the bridge of organic and inorganic nitrogen transformation, and was the sign of nitrogen cycle of Lake Taihu, which was controlled by the circulating rate. High nitrogen content (especially the organic nitrogen) and low dissolved oxygen content were the key contributors to the increased urea nitrogen content. In Taihu, the urea nitrogen content was affected by both exogenous input and endogenous release. PMID:25244836

  5. Banding of urea increased ammonia volatilization in a dry acidic soil.

    PubMed

    Rochette, Philippe; Macdonald, J Douglas; Angers, Denis A; Chantigny, Martin H; Gasser, Marc-Olivier; Bertrand, Normand

    2009-01-01

    Volatilization of ammonia following application of urea contributes to smog formation and degradation of natural ecosystems. The objective of this study was to evaluate the impact of (i) incorporation and banding of urea and (ii) surface broadcast of slow-release urea types on NH(3) volatilization in a dry acidic soil. Volatilization was measured using wind tunnels for 25 d after standard urea (140 kg N ha(-1)) was broadcast, broadcast and incorporated (0-5 cm), or incorporated in shallow bands (3-5 cm) to a conventionally tilled silty loam soil. Urea supplemented with a urease inhibitor or coated with a polymer was also broadcast at the soil surface. Little N diffused out of the polymer-coated granules and ammonia losses were low (4% of applied N). Use of a urease inhibitor also resulted in a low NH(3) loss (5% of applied N) while maintaining soil mineral N at levels similar to plots where untreated urea was broadcast. The rate of hydrolysis of urea broadcast at the soil surface was slowed by the lack of moisture and NH(3) loss (9% applied N) was the lowest of all treatments with standard urea. Incorporation of broadcast urea increased emissions (16% applied N) by increasing urea hydrolysis relative to surface application. Furthermore, incorporation in band also increased emissions (27% applied N) due to a localized increase in soil pH from 6.0 to 8.7. We conclude that incorporating urea in bands in a dry acidic soil can increase NH(3) volatilization compared to broadcast application followed by incorporation. PMID:19465713

  6. 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 ?mol.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

  7. On the urea induced hydrophobic collapse of a water soluble polymer.

    PubMed

    Rodríguez-Ropero, Francisco; van der Vegt, Nico F A

    2015-04-01

    Stabilization of macromolecular folded states in solution by protective osmolytes has been traditionally explained on the basis of preferential osmolyte depletion from the macromolecule's first solvation shell. However recent theoretical and experimental studies suggest that protective osmolytes may directly interact with the macromolecule. An example is the stabilization of the collapsed globular state of poly(N-isopropylacrylamide) (PNiPAM) by urea in aqueous solution. Based on Molecular Dynamics simulations we have characterized the mechanism through which urea stabilizes the collapsed state of PNiPAM in water. Analysis and comparison of the different components of the excess chemical potentials of folded and unfolded PNiPAM chains in aqueous urea solutions indicates that enthalpic interactions play no role in stabilizing the collapsed state. We instead find that with increasing urea, solvation of the unfolded state is entropically penalized over solvation of the folded state, thereby shifting the folding equilibrium in favour of the folded state. The unfavourable entropy contribution to the excess chemical potential of unfolded PNiPAM chains results from two urea effects: (1) an increasing cost of cavity formation with increasing urea, (2) larger fluctuations in the energy component corresponding to PNiPAM-(co)solvent attractive interactions. These energy fluctuations are particularly relevant at low urea concentrations (<3 M) and result from attractive polymer-urea van der Waals interactions that drive the formation of "urea clouds" but bias the spatial distribution of urea and water molecules with a corresponding reduction of the entropy. We further find indications that urea increases the entropy of the globular state. PMID:25684267

  8. Internal Combustion Engine Flows

    NASA Astrophysics Data System (ADS)

    McCleney, Amy; Puzinauskas, Paul; Gibson, Kendrick

    2009-11-01

    An automobile engine's performance can be enhanced by a more complete combustion reaction which results in less fuel consumption and lower emissions. The combustion improvement can be accomplished through an increase in turbulence from tumble flow, a circulatory motion inside the cylinder. In previous research, this increase is created by changing the intake ports on the engine so the flow is more precisely directed in the cylinder. In this study, the following three experiments were conducted: a detailed vane characterization experiment to direct the flow; a study of the effect of the piston shape on the flow; and a seeding settling experiment to determine experimentation quality. These experiments offer insight into the flow structure inside the test cylinder, as observed using particle image velocimetry and impulse swirl meter testing.

  9. Binding of carboxylic acids by fluorescent pyridyl ureas.

    PubMed

    Jordan, Lisa M; Boyle, Paul D; Sargent, Andrew L; Allen, William E

    2010-12-17

    Fluorescent pyrid-2-yl ureas were prepared by treating halogenated 2-aminopyridines with hexyl isocyanate, followed by Sonogashira coupling with arylacetylenes. The sensors emit light of ?360 nm with quantum yields of 0.05-0.1 in acetonitrile solution. Addition of strong organic acids (pK(a) < 13 in CH(3)CN) shifts the fluorescence band to lower energy, and clean isoemissive behavior is observed. Fluorescence response curves (i.e., F/F(0) vs [acid](total)) are hyperbolic in shape for CCl(3)COOH and CF(3)COOH, with association constants on the order of 10(3) M(-1) for both acids. (1)H NMR titrations and DFT analyses indicate that trihaloacetic acids bind in ionized form to the receptors. Pyridine protonation disrupts an intramolecular H-bond, thereby unfolding an array of ureido NH donors for recognition of the corresponding carboxylates. Methanesulfonic acid protonates the sensors, but no evidence for conjugate base binding at the urea moiety is found by NMR. An isosteric control compound that lacks an integrated pyridine does not undergo significant fluorescence changes upon acidification. PMID:21080667

  10. Internal combustion engine using premixed combustion of stratified charges

    DOEpatents

    Marriott, Craig D. (Rochester Hills, MI); 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.

  11. Catalytic combustion nears application

    SciTech Connect

    NONE

    1994-11-01

    This article is a brief review of efforts to develope a catalytic combustion system with emissions levels less than 10 ppm. Two efforts are discussed: (1) tests by General Electric using a GE Frame 7E/9E and 7F/9F gas turbine, and (2) tests by AES using a Kawasaki M1A-13A industrial gas turbine. The latter also employs a heat recovery steam generator and produces 3 MWe and 28,000 lbm/hr of steam.

  12. Catalytic Combustion of Syngas

    Microsoft Academic Search

    John Mantzaras

    2008-01-01

    The catalytic combustion of syngas\\/air mixtures over Pt has been investigated numerically in a channel-flow configuration using 2D steady and transient computer codes with detailed hetero-\\/homogeneous chemistry, transport, and heat transfer mechanisms in the solid. Simulations were carried out for syngas compositions with varying H2 and CO contents, pressures of 1 to 15 bar, and linear velocities relevant to power

  13. THE FIRST TURBULENT COMBUSTION

    Microsoft Academic Search

    CARL H. GIBSON

    2005-01-01

    The first turbulent combustion arises in a hot-big-bang cosmological model (Gibson, 2004) where nonlinear exothermic turbulence permitted by quantum mechanics, general relativity, multidimensional superstring theory, and fluid mechanics cascades from Planck to strong-force freeze-out scales with gravity balancing turbulent inertial-vortex forces. Interactions between Planck scale spinning and non-spinning black holes produce high Reynolds number turbulence and temperature mixing with huge

  14. 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.

  15. Engine combustion chamber structure

    SciTech Connect

    Tanaka, H.

    1988-09-13

    This patent describes a combustion chamber structure comprising an upper wall surface which is shaped like a pent-roof and into which an intake passage opens, a piston having on a head portion thereof a bulged portion conforming to the upper wall surface in shape, a first bowl portion which is formed substantially at the center of the bulged portion and which is substantially semispherical in shape, a pair of second bowl portions which respectively extend on opposite sides of the first bowl portion to the corresponding ends of the bulged portion of the piston along the edge of the bulged portion and are in communication with the first bowl portion, a swirl generating means which is adapted to generate a swirl of intake air in the combustion chamber when the engine load is light, and a spark plug disposed to substantially face the center of the first bowl portion from the upper wall surface; the swirl generating means being adapted to generate the swirl of intake air in a tangential direction in the combustion chamber; and the diameter of the first bowl portion being larger than the width of the second bowl portion.

  16. Ant Routing in Mobile Ad Hoc Networks

    Microsoft Academic Search

    S. S. Dhillon; X. Arbona; Piet Van Mieghem

    2007-01-01

    We study the performance of ant routing for static and dynamic network topologies. We also compare the per- formance of ant routing with AODV and DSR for ad hoc networks. The simulations show that the ant routing al- gorithm performs well for static topologies. However, the routing overhead in ant routing is more than AODV and DSR. Therefore, ant routing

  17. A journey into multicomputer routing algorithms

    Microsoft Academic Search

    Miltos D. Grammatikakis; D. Frank Hsu; Miro Kraetzl

    1995-01-01

    We survey various aspects of packet routing, namely (partial) permutation, h-relation routing, routing to random destinations, dynamic routing, isotonic routing, fault tolerant routing, and related sorting results. We present theoretical results for general graphs and the hypercube topology, assuming both SIMD and MIMD communication models

  18. Masked Proportional Routing

    NASA Technical Reports Server (NTRS)

    Wolpert, David

    2004-01-01

    Masked proportional routing is an improved procedure for choosing links between adjacent nodes of a network for the purpose of transporting an entity from a source node ("A") to a destination node ("B"). The entity could be, for example, a physical object to be shipped, in which case the nodes would represent waypoints and the links would represent roads or other paths between waypoints. For another example, the entity could be a message or packet of data to be transmitted from A to B, in which case the nodes could be computer-controlled switching stations and the links could be communication channels between the stations. In yet another example, an entity could represent a workpiece while links and nodes could represent, respectively, manufacturing processes and stages in the progress of the workpiece towards a finished product. More generally, the nodes could represent states of an entity and the links could represent allowed transitions of the entity. The purpose of masked proportional routing and of related prior routing procedures is to schedule transitions of entities from their initial states ("A") to their final states ("B") in such a manner as to minimize a cost or to attain some other measure of optimality or efficiency. Masked proportional routing follows a distributed (in the sense of decentralized) approach to probabilistically or deterministically choosing the links. It was developed to satisfy a need for a routing procedure that 1. Does not always choose the same link(s), even for two instances characterized by identical estimated values of associated cost functions; 2. Enables a graceful transition from one set of links to another set of links as the circumstances of operation of the network change over time; 3. Is preferably amenable to separate optimization of different portions of the network; 4. Is preferably usable in a network in which some of the routing decisions are made by one or more other procedure(s); 5. Preferably does not cause an entity to visit the same node twice; and 6. Preferably can be modified so that separate entities moving from A to B do not arrive out of order.

  19. Internal combustion engine with rotary combustion chamber

    SciTech Connect

    Hansen, C.N.; Cross, P.C.

    1986-09-23

    This patent describes an internal combustion engine comprising: a block having at least one cylindrical wall surrounding a piston chamber, piston means located in the piston chamber means operable to reciprocate the piston means in the chamber, head means mounted on the block covering the chamber. The head means has an air and fuel intake passage, and exhaust gas passage, a rotary valve assembly operatively associated with the head means for controlling the flow of air and fuel into the rotary valve assembly and piston chamber and the flow of exhaust gas from rotary valve assembly and the piston chamber. The means has a housing with a bore open to the piston chamber accommodating the rotary valve assembly, the valve assembly comprising a cylindrical sleeve located in the bore, the sleeve having an inner surface, an ignition hole, and intake and exhaust ports aligned with the intake passage and exhaust gas passage, spark generating means mounted on the housing operable to generate a spark. The rotatable valving means is located within the sleeve for controlling the flow of air and fuel into the rotary valve assembly and piston chamber and the flow of exhaust gases out of the rotary valve assembly and piston chamber.

  20. 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

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

    Microsoft Academic Search

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

    1999-01-01

    A field study made with rice at the Indian Agricultural Research Institute, New Delhi, showed that coating urea with neem\\u000a oil, neem cake or neem oil microemulsion improved rice growth and resulted in more grain and straw than did commercial prilled\\u000a urea.

  2. Coating of prilled urea with neem (Azadirachta indica juss) oil for efficient nitrogen use in rice

    PubMed

    Prasad; Singh; Saxena; Devkumar

    1999-11-01

    A field study made with rice at the Indian Agricultural Research Institute, New Delhi, showed that coating urea with neem oil, neem cake or neem oil microemulsion improved rice growth and resulted in more grain and straw than did commercial prilled urea. PMID:10551949

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Salt-stabilized globular protein structure in 7 M aqueous urea solution

    E-print Network

    Wider, Gerhard

    1 Salt-stabilized globular protein structure in 7 M aqueous urea solution V. Dötsch,1 G. Wider, G Hochschule- Hönggerberg, CH-8093 Zürich, Switzerland Keywords Protein folding; Urea denaturation; Salt changing the solution conditions. In this paper we describe the influence of various salts or non

  5. Soy flour adhesive modified with urea, citric acid and boric acid

    Microsoft Academic Search

    F. Li; X. P. Li; W. H. Wang

    2010-01-01

    Purpose – The purpose of this paper is to investigate an adhesive prepared from soy flour (SF) modified with urea, citric acid and boric acid as an environmentally friendly product for the wood industry. Design\\/methodology\\/approach – Urea solution was prepared at 30°C and then SF was added and stirred at 30°C for 2 hours. Citric acid solution was added and

  6. 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 (...

  7. 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...

  8. Concentration of ?-Linoleic Acid of Perilla Oil by Gradient Cooling Urea Inclusion

    Microsoft Academic Search

    Hai-bo GU; Xue-yi MA; Jing-bo WU; Qi ZHANG; Wen-bing YUAN; Yi-ping CHEN

    2009-01-01

    In this study, production of ?-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized. The fatty acid composition was determined after ethyl esterification by gas chromatography (GC). In this process, orthogonal experiment was carried out. Under optimum conditions, the maximum amount of ?-linoleic acid (91.5%) was obtained at a urea to fatty acid ratio of

  9. Effect of Granular Urea Placement on Nitrous Oxide Production from a Silt Loam Soil

    E-print Network

    Lawrence, Rick L.

    Effect of Granular Urea Placement on Nitrous Oxide Production from a Silt Loam Soil Richard Engel1 emission patterns and losses from urea prills applied to a silt loam soil using band, nest, and broadcast, and the soil is classified as an Amsterdam silt loam (fine-silty, mixed, superactive, frigid Typic Haplustolls

  10. Effect of urea on sodium bis(2-ethylhexyl) sulfosuccinate thin films on solid substrates

    Microsoft Academic Search

    Carmen Lúcia Costa Amaral; Mário José Politi

    2004-01-01

    The effect of urea on sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles films deposited on hydrophobic and hydrophilic glass substrates was studied by optical and electron microscopy. Films growth in the absence of urea presented a droplet aspect, whereas in its presence, the films had a more tubular structure and seemed to merge one into the other suggesting a less rigid

  11. 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...

  12. Factors Influencing Intake of High Urea-Containing Rations by Lactating Dairy Cows

    Microsoft Academic Search

    A. F. Kertz; M. K. Koepke; L. E. Davidson; N. L. Betz; J. R. Norris; L. V. Skoch; B. R. Cords; D. T. Hopkins

    1982-01-01

    In a series of experiments we inves- tigated effects of several factors on intake of urea by lactating dairy cows. Cows given an unfamiliar ingredient or altered moisture in the ration reduced their in- take, and this effect was attributed to a newness factor. Addition of urea to a ration may have a similar effect. An experimental design providing both

  13. Morphological and functional characteristics of the kidney of cartilaginous fishes: with special reference to urea reabsorption.

    PubMed

    Hyodo, Susumu; Kakumura, Keigo; Takagi, Wataru; Hasegawa, Kumi; Yamaguchi, Yoko

    2014-12-15

    For adaptation to high-salinity marine environments, cartilaginous fishes (sharks, skates, rays, and chimaeras) adopt a unique urea-based osmoregulation strategy. Their kidneys reabsorb nearly all filtered urea from the primary urine, and this is an essential component of urea retention in their body fluid. Anatomical investigations have revealed the extraordinarily elaborate nephron system in the kidney of cartilaginous fishes, e.g., the four-loop configuration of each nephron, the occurrence of distinct sinus and bundle zones, and the sac-like peritubular sheath in the bundle zone, in which the nephron segments are arranged in a countercurrent fashion. These anatomical and morphological characteristics have been considered to be important for urea reabsorption; however, a mechanism for urea reabsorption is still largely unknown. This review focuses on recent progress in the identification and mapping of various pumps, channels, and transporters on the nephron segments in the kidney of cartilaginous fishes. The molecules include urea transporters, Na(+)/K(+)-ATPase, Na(+)-K(+)-Cl(-) cotransporters, and aquaporins, which most probably all contribute to the urea reabsorption process. Although research is still in progress, a possible model for urea reabsorption in the kidney of cartilaginous fishes is discussed based on the anatomical features of nephron segments and vascular systems and on the results of molecular mapping. The molecular anatomical approach thus provides a powerful tool for understanding the physiological processes that take place in the highly elaborate kidney of cartilaginous fishes. PMID:25339681

  14. Crystalline Bis-urea Nanochannel Architectures Tailored for Single-File Diffusion Studies.

    PubMed

    Bowers, Clifford R; Dvoyashkin, Muslim; Salpage, Sahan R; Akel, Christopher; Bhase, Hrishi; Geer, Michael F; Shimizu, Linda S

    2015-06-23

    Urea is a versatile building block that can be modified to self-assemble into a multitude of structures. One-dimensional nanochannels with zigzag architecture and cross-sectional dimensions of only ?3.7 Å × 4.8 Å are formed by the columnar assembly of phenyl ether bis-urea macrocycles. Nanochannels formed by phenylethynylene bis-urea macrocycles have a round cross-section with a diameter of ?9.0 Å. This work compares the Xe atom packing and diffusion inside the crystalline channels of these two bis-ureas using hyperpolarized Xe-129 NMR. The elliptical channel structure of the phenyl ether bis-urea macrocycle produces a Xe-129 powder pattern line shape characteristic of an asymmetric chemical shift tensor with shifts extending to well over 300 ppm with respect to the bulk gas, reflecting extreme confinement of the Xe atom. The wider channels formed by phenylethynylene bis-urea, in contrast, present an isotropic dynamically average electronic environment. Completely different diffusion dynamics are revealed in the two bis-ureas using hyperpolarized spin-tracer exchange NMR. Thus, a simple replacement of phenyl ether with phenylethynylene as the rigid linker unit results in a transition from single-file to Fickian diffusion dynamics. Self-assembled bis-urea macrocycles are found to be highly suitable materials for fundamental molecular transport studies on micrometer length scales. PMID:26035000

  15. 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.

  16. Microbial protein production determined by urinary allantoin and renal urea sparing in normal

    E-print Network

    Paris-Sud XI, Université de

    Short note Microbial protein production determined by urinary allantoin and renal urea sparing. Renal functional tests for urea handling studies, and determination of urinary allantoin as an indirect of allantoin, thereby leading to an underestimation of the amount of microbial protein entering in the duodenum

  17. Determination of urea and its thermal decomposition products by high-performance liquid chromatography

    Microsoft Academic Search

    Manfred Koebel; Martin Elsener

    1995-01-01

    The thermal decomposition of urea can yield a wide variety of products; apart from ammonia and isocyanic acid, addition compounds of higher molecular mass may appear. In order to detect their presence in exhaust gases from a selective catalytic reduction (SCR) process using urea as a reducing agent, a chromatographic method was developed. The chromatographic separation is performed on an

  18. 75 FR 51055 - Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ...EPA-HQ-OPP-2010-0650; FRL-8840-5] Propionic Acid and Salts, and Urea Sulfate; Registration...decisions for the pesticides propionic acid and salts, and urea sulfate and opens...decisions. The active ingredient propionic acid is a fungicide and bactericide that...

  19. Comparison of hydrogen bonding in polydimethylsiloxane and polyether based urethane and urea copolymers

    Microsoft Academic Search

    E. Yilgör; E. Burgaz; E. Yurtsever

    2000-01-01

    Hydrogen bonding in polydimethylsiloxane and polyether based urethane and urea type segmented copolymers was investigated by infrared spectroscopy, differential scanning calorimetry and quantum mechanical calculations. Hydrogen bonding in model urethane and urea compounds was compared with those of the copolymers, in order to determine the extent of interaction and resulting phase mixing between hard and soft segments in these copolymers.

  20. Peptidyl-urea based inhibitors of soluble epoxide hydrolases Christophe Morisseau,a

    E-print Network

    Hammock, Bruce D.

    Peptidyl-urea based inhibitors of soluble epoxide hydrolases Christophe Morisseau,a John W. Newman a series of amino acid derived cyclohexyl and adamantyl ureas and tested them as inhibitors of the human than previously described sEH inhibitors. While our lead compound 2 showed low apparent bioavailability

  1. Milk Urea Testing as a Tool to Monitor Reproductive Performance in Ontario Dairy Herds

    Microsoft Academic Search

    S. M. Godden; D. F. Kelton; K. D. Lissemore; J. S. Walton; K. E. Leslie; J. H. Lumsden

    2001-01-01

    Dairy herd improvement test-day data, including milk urea concentrations measured using infrared test method, were collected from 60 commercial Ontario Holstein dairy herds for a 13-mo period between Decem- ber 1, 1995, and December 31, 1996. The objective of the study was to describe, at the cow and the group level, the relationship between DHI milk urea concen- trations and

  2. 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 ...

  3. 77 FR 64464 - Solid Urea From the Russian Federation: Antidumping Duty Administrative Review; 2010-2011

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ...order on solid urea from the Russian Federation (Russia). The...Department of Commerce, 14th Street and Constitution Avenue NW., Washington...Russia. See Solid Urea From the Russian Federation: Preliminary Results...is provided for convenience and customs purposes, the...

  4. 76 FR 66690 - Solid Urea From the Russian Federation: Final Results of Antidumping Duty Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-27

    ...on solid urea from the Russian Federation. The solid...this review was produced and exported by MCC EuroChem...versions of the Issues and Decision Memorandum are...on solid urea from the Russian Federation produced and exported by EuroChem...

  5. 78 FR 67335 - Solid Urea From the Russian Federation: Final Results of Antidumping Duty Administrative Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ...A-821-801] Solid Urea From the Russian Federation: Final Results of...2011-2012 AGENCY: Enforcement and Compliance (formerly Import...order on solid urea from the Russian Federation (Russia). For...Operations, Office I, Enforcement and Compliance (E&C),...

  6. 13C-urea breath test in the management of Helicobacter pylori infection

    Microsoft Academic Search

    J. P. Gisbert; J. M. Pajares

    2005-01-01

    The urea breath test is a noninvasive and very accurate test for the diagnosis of Helicobacter pylori infection. However, false negative urea breath test results have been reported to occur in a considerable percentage of the individuals taking proton pump inhibitors; the interval needed to be completely confident that false negative tests had been excluded has varied among the different

  7. 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

  8. 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.

  9. 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.

  10. CATALYTIC COMBUSTION OF PROPANE IN A MEMBRANE REACTOR WITH SEPARATE FEED OF REACTANTS III. ROLE OF CATALYST LOAD ON REACTOR PERFORMANCE

    Microsoft Academic Search

    GUIDO SARACCO; JAN WILLEM VELDSINK; GEERT F. VERSTEEG; WIM P. M. VAN SWAAIJ

    1996-01-01

    This paper deals with a pilot plant study on the catalytic combustion of propane in a membrane reactor with separate feed of reactants. The importance of the amount of catalyst (1% b.w. Pt on ?-Al2O3), deposited on the pore walls of the membrane, is investigated. Two membranes were prepared by the so called urea method, intruding different amounts of the

  11. Dielectric behavior and a. c. conductivity studies on Co0.4Ni0.6Fe2O4 nanoparticles synthesized via combustion method

    Microsoft Academic Search

    B. J. Madhu; K. Bindu; S. Hamsa; C. P. Sowmya; A. Manjunath; G. H. Virupakshappa; B. Shruthi

    2011-01-01

    Cobalt-Nickel (Co0.4Ni0.6Fe2O4) ferrite nanoparticles were prepared by solution combustion method using cobalt nitrate & nickel nitrate as oxidizers and urea as a fuel. The structures of the sample were studied with X-ray diffraction (XRD) using Cu-Ka radiation. The X-ray diffraction analysis revealed the nanocrystalline nature in the prepared ferrite samples. The dependence of dielectric properties such as dielectric constant (??)

  12. 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. (Univ. of Udine (Italy)); Ferroni, E. (Univ. of Florence (Italy)); Kevan, L. (Univ. of Houston, TX (USA))

    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.

  13. 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.

  14. 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.

  15. Hiding Routing Information

    Microsoft Academic Search

    David M. Goldschlag; Michael G. Reed; Paul F. Syverson

    1996-01-01

    . This paper describes an architecture, Onion Routing, thatlimits a network's vulnerability to traffic analysis. The architecture providesanonymous socket connections by means of proxy servers. It providesreal-time, bi-directional, anonymous communication for any protocolthat can be adapted to use a proxy service. Specifically, the architectureprovides for bi-directional communication even though no-one butthe initiator's proxy server knows anything but previous and next

  16. Photonic IP routing

    Microsoft Academic Search

    K.-I. Kitayama; N. Wada

    1999-01-01

    A photonic Internet protocol (IP) routing is proposed in which the IP address, mapped onto optical code, is recognized by performing optical correlation in the time domain in a parallel manner. Preliminary experiment shows that it can process 6.5×109 packets per second. It will help overcome the bottleneck in current electrical IP routers; i.e., the time it takes to look

  17. 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).

  18. Filtration combustion of liquid monofuels

    Microsoft Academic Search

    N. A. Kakutkina

    2008-01-01

    A one-dimensional two-temperature model for filtration combustion of liquid monofuels is proposed. The model is used to analyze\\u000a the filtration combustion of liquid hydrazine in narrow tubes. Two steady-state regimes are found. In regime I, the dominant\\u000a mechanism of heat transfer from the combustion products in the preflame zone is heat conduction in the gas, and in regime\\u000a II, this

  19. Combustion limits of liquid monofuels

    Microsoft Academic Search

    N. A. Kakutkina

    2009-01-01

    A mathematical model for steady-state nonadiabatic waves of filtration combustion of liquid monofuels in narrow tubes is proposed.\\u000a Using this model, it is shown that combustion in this system can proceed in two regimes with different dominant mechanisms\\u000a of heat transfer from combustion products to the preflame zone. The nature and parametric dependences of the limits of both\\u000a regimes are

  20. Filtration Combustion of Liquid Monofuels

    Microsoft Academic Search

    N. A. Kakutkina; V. A. Bunev

    2001-01-01

    A one-dimensional one-temperature model for filtration combustion of liquid monofuels is proposed which describes qualitatively the behavior of steady-state combustion waves of a liquid monofuel under filtration in a porous medium or tube. A comparison of experimental data on the combustion of hydrazine in a porous medium and in narrow tubes with calculations by the model shows that the model

  1. 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

  2. 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.

  3. Routing Metric Designs for Greedy, Face and Combined-Greedy-Face Routing

    Microsoft Academic Search

    Yujun Li; Yaling Yang; Xianliang Lu

    2009-01-01

    Different geographic routing protocols have differ- ent requirements on routing metric designs to ensure proper operation. Combining a wrong type of routing metrics with a geographic routing protocol may produce unexpected results, such as geographic routing loops and unreachable nodes. In this paper, we propose a novel routing algebra system to investigate the compatibilities between routing metrics and three geographic

  4. 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.

  5. Gas turbine slagging combustion system

    SciTech Connect

    Solbes, A.; Iwata, H.

    1990-05-01

    This paper in an apparatus for combustion of carbonaceous fuel wherein preheated oxidizer gas and particulate fuel are introduced into a substantially cylindrical primary combustor. It comprises: a head end and an exit end, and wherein the flow velocities, mass flow rates, and combustion temperatures are regulated in minimize the concentration of volatized and liquid slag in the output gaseous products of combustion, and wherein the walls of the combustion chamber are maintained within a temperature range such that a layer of solidified slay is retained on the inside surfaces of the wall.

  6. Synthesis and magnetic properties of quasi-single domain M-type barium hexaferrite powders via sol–gel auto-combustion: Effects of pH and the ratio of citric acid to metal ions (CA\\/M)

    Microsoft Academic Search

    Liu Junliang; Zhang Wei; Guo Cuijing; Zeng Yanwei

    2009-01-01

    Quasi-single magnetic domain M-type barium hexaferrite powders have been synthesized via sol–gel auto-combustion route, followed by secondary heating treatment at 800°C for 4h, using barium nitrate, ferrite nitrate, ammonium nitrate, citric acid, and ammonia solution as the starting materials. The auto-combustion producing powders were ?-Fe2O3 and BaCO3 with aid of additional ammonium nitrate to increase the combustion temperature. The influences

  7. Experimental and modeling study of the effect of CO and H2 on the urea DeNO(x) process in a 150kW laboratory reactor.

    PubMed

    Javed, M Tayyeb; Nimmo, W; Gibbs, B M

    2008-01-01

    An experimental and modeling investigation has been performed to study the effect of process additives, H2 and CO on NO(x) removal from flue gases by a selective non-catalytic reduction process using urea as a reducing agent. Experiments were performed with a flow reactor in which flue gas was generated by the combustion of propane in air at 3% excess oxygen and the desired levels of initial NO(x) (500ppm) were achieved by doping the flame with ammonia. Experiments were performed throughout the temperature range of interest, i.e. from 850 to 1200 degrees C for investigation of the effects of the process additives on the performance of aqueous urea DeNO(x). Subsequently, computational kinetic modeling with SENKIN code was performed to analyze the performance of urea providing a direct comparison of modeling prediction with experimental measurements. With CO addition, a downwards shift of 215 degrees C in the peak reduction temperature from 1125 to 910 degrees C was observed during the experimentation while the kinetic modeling suggests it to be 150 degrees C, i.e. from 1020 to 870 degrees C. The addition of H2 impairs the peak NO(x) reduction but suggests a low temperature application of the process. A downward shift of 250 degrees C in the peak reduction temperature, from 1020 to 770 degrees C, was observed during kinetic modeling studies. The kinetic modeling shows a good qualitative agreement with the experimental observations and reveals additional information about the process. PMID:17845815

  8. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding from the experimental component of the research was that hydrates can burn completely, and that they burn most rapidly just after ignition and then burn steadily when some of the water in the dissociated zone is allowed to drain away. Excessive surfactant in the water creates a foam layer around the hydrate that acts as an insulator. The layer prevents sufficient heat flux from reaching the hydrate surface below the foam to release additional methane and the hydrate flame extinguishes. No self-healing or ice-freezing processes were observed in any of the combustion experiments. There is some variability, but a typical hydrate flame is receiving between one and two moles of water vapor from the liquid dissociated zone of the hydrate for each mole of methane it receives from the dissociating solid region. This limits the flame temperature to approximately 1800 K. In the theoretical portion of the study, a physical model using an energy balance from methane combustion was developed to understand the energy transfer between the three phases of gas, liquid and solid during the hydrate burn. Also this study provides an understanding of the different factors impacting the hydrate's continuous burn, such as the amount of water vapor in the flame. The theoretical study revealed how the water layer thickness on the hydrate surface, and its effect on the temperature gradient through the dissociated zone, plays a significant role in the hydrate dissociation rate and methane release rate. Motivated by the above mentioned observation from the theoretical analysis, a 1-D two-phase numerical simulation based on a moving front model for hydrate dissociation from a thermal source was developed. This model was focused on the dynamic growth of the dissociated zone and its effect on the dissociation rate. The model indicated that the rate of hydrate dissociation with a thermal source is a function of the dissociated zone thickness. It shows that in order for a continuous dissociation and methane release, some of the water from the dissociated zone needs to be drained. The results

  9. 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...

  10. 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.

  11. PATHWAYS FOR UREA PRODUCTION DURING EARLY LIFE OF AN AIR BREATHING TELEOST, THE AFRICAN CATFISH CLARIAS GARIEPINUS BURCHELL

    Microsoft Academic Search

    BENDIK F. TERJESEN; TERRY D. CHADWICK; JOHAN A. J. VERRETH; IVAR RØNNESTAD

    Embryos and larvae of the African catfish Clarias gariepinus excrete significant quantities of urea. The present study focused on the potential urea-generating pathways during early development of this teleost; uricolysis, argininolysis and the ornithine-urea cycle (OUC). Uricase, allantoinase, allantoicase and ureidoglycollate lyase of the uricolytic pathway were expressed in all early life stages and in adult liver of C. gariepinus.

  12. NITROGEN AND PHOSPHORUS UTILIZATION BY BEEF CATTLE FED THREE DIETARY CRUDE PROTEIN LEVELS WITH THREE LEVELS OF SUPPLEMENTAL UREA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three dietary CP levels (11.5, 13.0, and 14.5\\% of DM) and three supplemental urea levels (100, 50, and 0\\% of supplemental CP from urea) were fed to determine performance, serum urea N (SUN), and N and P balance. Crossbred steers (n = 27; average BW = 315 kg) were blocked by weight and individuall...

  13. 75 FR 40827 - Petitions Concerning Whether Ammonia or Urea Sold or Distributed and Used for Certain Purposes...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ...Concerning Whether Ammonia or Urea Sold or Distributed and Used for Certain Purposes Should...concerning whether ammonia or urea sold or distributed and used for certain purposes should...concerning whether ammonia or urea sold or distributed and used for certain purposes...

  14. 76 FR 19747 - Solid Urea From the Russian Federation and Ukraine: Final Results of the Expedited Sunset Reviews...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-08

    ...A-823-801] Solid Urea From the Russian Federation and Ukraine: Final Results...orders on solid urea from the Russian Federation (Russia) and Ukraine, pursuant to section...Orders on Solid Urea From the Russian Federation and Ukraine'' from Gary...

  15. Counteraction of urea-induced protein denaturation by trimethylamine N-oxide: A chemical chaperone at atomic resolution

    Microsoft Academic Search

    Brian J. Bennion; Valerie Daggett

    2004-01-01

    Proteins are very sensitive to their solvent environments. Urea is a common chemical denaturant of proteins, yet some animals contain high concentrations of urea. These animals have evolved an interesting mechanism to counteract the effects of urea by using trimethylamine N-oxide (TMAO). The molecular basis for the ability of TMAO to act as a chemical chaperone remains unknown. Here, we

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Regulation of urea permeability in frog urinary bladder by prostaglandin E(2).

    PubMed

    Bachteeva, Vera T; Fock, Ekaterina M; Lavrova, Elena A; Naboka, Elena V; Parnova, Rimma G

    2002-05-01

    The present study was performed to investigate the role of prostaglandin E(2) (PGE(2)) in the regulation of urea transport in the frog urinary bladder, which is known to occur via a specialized arginine-vasotocin- (AVT-) regulated urea transporter. The bladders isolated from Rana temporaria L. were filled with amphibian Ringer solution containing 370 Bq/ml (0.01 microCi/ml) of [14C]urea, and urea permeability ( P(urea)) was determined by sampling the serosal and mucosal bathing medium at 30-min intervals for measurement of radioactivity. It was found that, from the serosal side, PGE(2) (10 nM to 1 microM) caused a dose-dependent increase in P(urea) [(7.2+/-1.8)x10(-6) cm/s in the presence of 0.5 microM PGE(2)versus (1.0+/-0.2)x10(-6) cm/s in control, n=9, P<0.001]. As in response to AVT, the PGE(2)-induced P(urea)reached a maximum in 1-1.5 h after the agonist was added. The stimulatory effects of PGE(2) and AVT applied together were not additive. PGE(2)-induced urea transport was strongly inhibited by nearly 75% in the presence of mucosal or serosal phloretin (10(-4) M). P(urea) was enhanced up to (4.7+/-0.8)x10(-6) cm/s (n=12, P<0.001) by butaprost (5 x 10(-6) M), a selective EP(2) receptor agonist, while sulprostone (EP(1)/EP(3) agonist, 10(-6) M) caused no changes in P(urea). PGE(2)dose-dependently increased the content of cAMP in mucosal epithelial cells (control: 18.0+/-1.8; 10(-6) M PGE(2): 74.2+/-9.3 pmol cAMP/mg protein per 30 min, n=7, P<0.001). Phorbol esters did not alter PGE(2)-induced P(urea), whereas H-89 (20 microM), a protein kinase A inhibitor, reduced it by 45.1+/-9.9% ( n=5, P<0.05). PGE(2)did not change the AVT-stimulated P(urea) measured in isoosmotic conditions, but inhibited the last one in the presence of a serosa-to-mucosa osmotic gradient. The data obtained show that, in the frog urinary bladder, PGE(2)is a stimulator of phloretin-inhibitable urea transport. Its effect seems to be mediated by EP(2) receptor-coupled generation of intracellular cAMP. PMID:11976928

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

    PubMed

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

    2012-10-01

    Effects of supplemental energy sources on nutrient digestion and urea kinetics at 2 levels of degradable intake protein were evaluated in cattle (Bos taurus). Six ruminally and duodenally cannulated steers (208 ± 17 kg) were used in a 6 × 6 Latin square with treatments arranged as a 3 × 2 factorial. Energy treatments included a control, 600 g glucose dosed ruminally once daily, and 480 g VFA infused ruminally over 8 h daily. Casein (120 or 240 g) was dosed ruminally once daily. Steers had ad libitum access to prairie hay (5.8% CP). Jugular infusion of (15)N(15)N-urea with measurement of enrichment in urine was used to measure urea kinetics. Infusing VFA decreased (P < 0.01) forage intake by 27%. Supplementing glucose decreased (P < 0.01) total tract NDF digestibility and tended to decrease ruminal NDF digestibility; depressions in response to glucose tended to be greater at the lower level of casein. Increasing casein decreased (P < 0.02) ruminal pH. Infusing VFA decreased pH only during infusions, whereas glucose decreased pH 2 h after dosing. Ruminal concentrations of NH(3), acetate, and propionate decreased and butyrate concentration increased when glucose was supplemented. Increasing casein supplementation increased (P < 0.01) ruminal concentrations of NH(3), acetate, and propionate. Supplemental energy decreased (P = 0.03) plasma urea-N concentration, but casein level did not affect it (P = 0.16). Microbial N flow was greater (P < 0.04) for 240 than for 120 g/d casein but was not affected by supplemental energy (P = 0.23). Urea-N entry rate and gut entry of urea-N were not affected (P ? 0.12) by supplemental energy or casein, but the proportion of urea production that was recycled to the gut was less (P = 0.01) when 240 g/d rather than 120 g/d casein was provided. Compared with VFA, glucose tended (P = 0.07) to increase the proportion of urea-N entry rate that was recycled to the gut. Supplementation with glucose led to more (P = 0.01) microbial uptake of recycled urea than did supplementation with VFA. Urea recycling did not differ greatly among treatments despite impacts on ruminal pH and NH(3) and on plasma urea-N that were expected to alter urea transport across ruminal epithelium. Lack of treatment effects on urea production indicate that the complete diets did not provide excessive amounts of N and that increases of intestinally available AA were used efficiently by cattle for protein deposition. PMID:22851247

  2. Reciprocating piston internal combustion engine

    Microsoft Academic Search

    Wakeman

    1981-01-01

    A low compression ratio internal combustion engine is disclosed that includes a piston and cylinder arrangement the working volume of which is bounded in part by the piston crown and the cylinder head and in part by inlet valve means whereby an inlet charge can enter the working volume and exhaust valve means whereby products of combustion occuring within the

  3. Reciprocating piston internal combustion engine

    Microsoft Academic Search

    Hayashi

    1986-01-01

    A reciprocating piston internal combustion engine is described which consists of: a piston movably disposed within an engine cylinder, the piston having a top surface and a piston ring, the engine cylinder and the top surface of the piston defining a combustion chamber, the piston having first and second sections which are divided by a vertical plane containing an axis

  4. Gas turbine slagging combustion system

    Microsoft Academic Search

    A. Solbes; H. Iwata

    1990-01-01

    This paper in an apparatus for combustion of carbonaceous fuel wherein preheated oxidizer gas and particulate fuel are introduced into a substantially cylindrical primary combustor. It comprises: a head end and an exit end, and wherein the flow velocities, mass flow rates, and combustion temperatures are regulated in minimize the concentration of volatized and liquid slag in the output gaseous

  5. Liquid propellant rocket combustion instability

    NASA Technical Reports Server (NTRS)

    Harrje, D. T.

    1972-01-01

    The solution of problems of combustion instability for more effective communication between the various workers in this field is considered. The extent of combustion instability problems in liquid propellant rocket engines and recommendations for their solution are discussed. The most significant developments, both theoretical and experimental, are presented, with emphasis on fundamental principles and relationships between alternative approaches.

  6. Rotary reciprical combustion engines

    SciTech Connect

    Blount, D.H.

    1992-10-20

    This patent describes a rotary-reciprocal combustion engine having a cycle which includes the four strokes of intake, compression, expansion and exhaustion, the engine. It comprises: a housing formed with a peripheral wall with side walls, a rotor in the housing, the inner surface of the peripheral inner wall being cylindrical; a shaft; mounted in the center of the housing, passing through the rotor's hub and extending through the side walls of the housing, the hub having means to allow the rotor to reciprocate on the shaft while the shaft is rotating with the rotor; a reciprocal and rotary guide having means to guide the rotary and reciprocal motions of the rotor while keeping the rotor's piston in continuous sealing contact with the cylinder chamber walls and varying the volume of the cylinder chambers enabling a compression of a gaseous mixture to take place after aspirating a gaseous mixture; an ignition system having means for igniting compressed gaseous mixture and expansion of the cylinder chambers due to pressure of the combustion products.

  7. Structural characteristics that stabilize or destabilize different assembly levels of phycocyanin by urea.

    PubMed

    Marx, Ailie; Adir, Noam

    2014-07-01

    Phycocyanin is one of the two phycobiliproteins always found in the Phycobilisome antenna complex. It is always situated at the ends of the peripheral rods, adjacent to the core cylinders composed of allophycocyanin. The basic phycocyanin monomer is an (??) dimer of globin-like subunits with three covalently linked phycocyanobilin cofactors. Monomers assemble further into trimers, hexamers, and rods which include non-pigmented linker proteins. Upon isolation in low ionic strength solution, rods quickly disintegrate into phycocyanin trimers, which lose contacts with other phycobiliproteins and with the linker proteins. The trimers, however, are quite stable and only the presence of high concentrations of chaotropic agents (such as urea), very acidic solutions, or elevated temperatures induces monomerization, followed by separation between the subunits. We have recently determined the crystal structures of phycocyanin from the thremophilic cyanobacterium Thermosynechococcus vulcanus in the presence of 2 or 4 M urea, and shown that 4 M urea monomerizes the phycocyanin trimers. In this paper, we will describe the phycocyanin structures in 2 and 4 M urea more completely. By mapping out the urea positions, we describe the structural elements within the trimeric interaction interface that may be interrupted by the presence of 4 M urea. In addition, we also identify what are the structural characteristics that prevent 4 M urea from inducing subunit dissociation. PMID:24687534

  8. Urea Monitor Based on Chemiluminescence and Electrolysis as a Marker for Dialysis Efficiency

    NASA Astrophysics Data System (ADS)

    Ozaki, Masahiro; Okabayashi, Tohru; Ishimaru, Teppei; Hayashi, Kunihito; Hori, Jun'ya; Yamamoto, Isao; Nakagawa, Masuo

    We have developed a practical urea monitor based on a chemiluminescent (CL) reaction of urea and hypobromous acid produced by electrolysis of sodium bromide (NaBr) for measuring urea concentration in spent dialysate at set intervals. A reagent containing 4×10-2 M hypobromous acid is produced by electrolysis of an electrolyte containing 5.9 M NaBr and 0.2 M sodium hydroxide (NaOH). Chemiluminescence is emitted by injection of spent hemodialysis fluid (0.11 ml) into the reagent, and the CL-intensity is measured by a photomultiplier tube using the photon counting technique. The CL-intensity is proportional to the 0.9th power of the urea concentration between 7×10-4 and 2×10-2 M. The urea monitor can determine the urea concentration in spent dialysate samples collected from the waste line of a dialyzer, and the time for the intermittent measurements including the cleaning cycle of the reaction chamber is 3 min. The urea concentrations measured by the monitor are in close agreement with those measured by the conventional enzyme colorimetric method using urease for the spent dialysate collected during a hemodialysis treatment, and the correlation coefficient is 0.93.

  9. Replacing soybean meal for wet brewer's grains or urea on the performance of lactating dairy cows.

    PubMed

    Imaizumi, Hugo; Batistel, Fernanda; de Souza, Jonas; Santos, Flávio Augusto Portela

    2015-06-01

    The purpose of this research was to evaluate the partial replacement of soybean meal (SBM) for wet brewer's grains (WBG) or urea on the performance of lactating dairy cows. The second investigated whether WBG ensiled with corn kept animal performance in low- and high-producing dairy cows compared with WBG. In experiment I, 40 Holstein cows were used in 4?×?4 Latin square design. The treatments comprised WBG or urea as partial replacement for SBM, as follows: control (diet based on SBM and 1 % of urea), 10 % of WBG, 20 % of WBG, and 2 % of urea. Dry matter intake (DMI) was not affected by treatments. WBG increased milk yield linearly, but it decreased with urea. Milk fat content responded quadratically to WBG levels. Milk protein content decreased, while plasma urea nitrogen increased with high urea addition. In experiment II, 42 Holstein cows were divided into two groups according to production levels. Eighteen cows composed the group of low producing, while the high-producing group comprised 24 cows. The experimental design was a crossover with two periods of 14 days. The experimental treatments consisted of feeding WBG or WBG ensiled with ground corn. Regardless of the production level, no difference in milk yield and milk composition between treatments was observed. PMID:25854784

  10. Safety assessment of diammonium phosphate and urea used in the manufacture of cigarettes.

    PubMed

    Stavanja, Mari S; Curtin, Geoffrey M; Ayres, Paul H; Bombick, Elizabeth R; Borgerding, Michael F; Morgan, Walter T; Garner, Charles D; Pence, Deborah H; Swauger, James E

    2008-04-01

    A tiered testing strategy has been employed to evaluate the potential for new ingredients, tobacco processes, and technological developments to alter the mainstream smoke or biological activity that results from burning cigarette tobacco. The foundation of this evaluation strategy is comparative testing, typically including chemical and biological assessments. In the manufacture of cigarettes, diammonium phosphate (DAP) and urea have been historically used as ingredients added to tobacco, to reconstituted tobacco sheet, and to other processed tobaccos. As part of ongoing stewardship efforts, a toxicological assessment of cigarettes with and without DAP and urea was conducted. Chemical and biological analyses were conducted for test cigarettes added 0.5% DAP and 0.2% urea in the final blend and also for those added 1.0% DAP and 0.41% urea in the final blend compared to reference cigarettes without added DAP or urea. Principal components of this evaluation included a determination of selected mainstream smoke constituent yields, an Ames assay in Salmonella typhimurium strains TA98 and TA100, a sister chromatid exchange assay in Chinese hamster ovary cells, a 13-week inhalation study of mainstream cigarette smoke in Sprague-Dawley rats, and a 30-week dermal tumor-promotion evaluation of mainstream cigarette smoke condensate in SENCAR mice. Comparative evaluations demonstrated that the addition of DAP and urea to cigarettes at up to 1% and 0.41%, respectively, does not alter the biological activity compared to reference cigarettes without DAP or urea. PMID:18272354

  11. Molecular and functional characterization of a urea transporter from the kidney of the Atlantic stingray.

    PubMed

    Janech, Michael G; Fitzgibbon, Wayne R; Chen, Ruihua; Nowak, Mark W; Miller, Donald H; Paul, Richard V; Ploth, David W

    2003-05-01

    In general, marine elasmobranch fishes (sharks, skates, and rays) maintain body fluid osmolality above seawater, principally by retaining large amounts of urea. Maintenance of the high urea concentration is due in large part to efficient renal urea reabsorption. Regulation of renal urea reabsorption also appears to play a role in maintenance of fluid homeostasis of elasmobranchs that move between habitats of different salinities. We identified and cloned a novel 2.7-kb cDNA from the kidney of the euryhaline Atlantic stingray Dasyatis sabina (GenBank accession no. AF443781). This cDNA putatively encoded a 431-amino acid protein (strUT-1) that had a high degree of sequence identity (71%) to the shark kidney facilitated urea transporter (UT). However, the predicted COOH-terminal region of strUT-1 appears to contain an additional sequence that is unique among cloned renal UTs. Injection of strUT-1 cRNA into Xenopus oocytes induced a 33-fold increase in [(14)C]urea uptake that was inhibited by phloretin. Four mRNA bands were detected in kidney by Northern blot: a transcript at 2.8 kb corresponding to the expected size of strUT-1 mRNA and bands at 3.8, 4.5, and 5.5 kb. Identification of a facilitated UT in the kidney of the Atlantic stingray provides further support for the proposal that passive mechanisms contribute to urea reabsorption by elasmobranch kidney. PMID:12388386

  12. NMR Studies of Cu/zeolite SCR Catalysts Hydrothermally Aged with Urea

    SciTech Connect

    Cheng, Yisun; Hoard, John; Lambert, Christine; Kwak, Ja Hun; Peden, Charles HF

    2008-06-26

    The effects of hydrothermal aging of Cu/zeolite urea-SCR catalysts on their reactivity and material properties was assessed by performance tests and multiple characterization techniques that included 27Al NMR and XRD. Three aging protocols were used that consisted of varying temperature during hydrothermal aging with or without exposure to aqueous urea solution. Differences in behavior were even found for samples hydrothermally aged immediately following exposure to the urea solution or if the sample was dried overnight before hydrothermal aging. The combination of urea and high temperature exposure increased the deactivation of Cu/zeolite SCR catalysts beyond that observed by hydrothermal aging alone, with an immediate high temperature exposure following wetting of the catalyst core with aqueous urea causing the most significant deterioration in performance. The impact of urea on SCR catalyst durability was also found to increase with the aging temperature. NMR analysis suggested that aging with urea resulted in relatively more dealumination of the zeolite for the SCR catalysts in this study.

  13. [FTIR spectra study on the swellbility and controlled-release mechanism of polyurethane coated urea].

    PubMed

    Wu, Shu; Ru, Tie-Jun; Wang, Jin-Ming

    2013-05-01

    The nutrient release experiment of polyurethane coated urea (PCU) was carried out in pure water at 25 degrees C. With the release of urea, the structural variation of polyurethane coating was investigated by Fourier transform infrared spectroscopy (FTIR), then a series of curves were collated and compared so as to better reflect the relation between diffusion rate of urea and coating structure. It was found that when the nutrient was released by 50% wt, new absorption peaks at 3 435, 3 342, 1 671, 1 621, 1 448 and 1 159 cm(-1) appear in the FTIR spectra of polyurethane coating, moreover, the height of these absorption peaks was increased gradually when the nutrient was released by 70% wt, more importantly, these new absorption peaks are consistent with the characteristic absorption peaks of urea fertilizer, the spectra of urea were mainly characterized by bands at 3 440, 3 346, 1 672, 1 621 and 1 461 cm(-1). The results show that the IR spectra variation was caused by the content of urea, existing in the polyurethane coating, and was increased gradually, The more the urea content, the greater the swelling degree of the polyurethane coating. The swelling of polyurethane coating leads to the pores size change, and release rate is increased, so the "S" pattern curve of the nitrogen accumulative release is formed. PMID:23905318

  14. Control of combustion-generated nitrogen oxides by selective non-catalytic reduction.

    PubMed

    Javed, M Tayyeb; Irfan, Naseem; Gibbs, B M

    2007-05-01

    Controlling nitrogen oxides (NO(x)) emissions is becoming a daunting technical challenge as increasingly strict emission limits are being imposed. The stringent regulations have prompted the innovation and characterization of NO(x) control technologies suitable for various applications. This paper presents a review on NO(x) removal techniques with particular reference to selective non-catalytic reduction (SNCR) technology. This includes initially how SNCR emerged as a technology along with a comparison with other relevant technologies. A review of various features related to selective non-catalytic gas phase injection of ammonia and ammonium salts (as reducing agent) is presented. The use of urea solution as a reducing agent and its performance in laboratory and pilot scale tests as well as large-scale applications is also discussed. Use of cyanuric acid as a potential reducing agent is also presented. The underlying reaction mechanisms have been reviewed for ammonia, urea and cyanuric acid for the explanation of various observations. Computational fluid dynamics (CFD) modeling as applied to SNCR is also presented. Subsequently the use of SNCR coupled with other in-combustion and post-combustion NO(x) control techniques is elaborated. Additionally, a two-stage NO(x) removal strategy to control un-reacted ammonia slip and to improve overall efficiency is discussed. At the end a summary is given which highlights various areas needing further research. PMID:16842901

  15. Modeling the kinetics of non-isothermal heterogeneous interaction during combustion synthesis of advanced micro- and nanocrystalline materials

    Microsoft Academic Search

    Boris B. Khina

    2008-01-01

    The combustion synthesis (CS), or self-propagating high-temperature synthesis (SHS) is a cost and energy efficient route for producing a wide range of refractory compounds (carbides, silicides, intermetallics) and advanced micro- and nanocrystalline materials. However, despite 40 years of extensive studies and industrial applications, intricate phase formation mechanisms that operate during CS are still not well understood. This hinders the development

  16. Enhanced-efficiency fertilizers in nitrous oxide emissions from urea applied to sugarcane.

    PubMed

    Soares, Johnny R; Cantarella, Heitor; Vargas, Vitor P; Carmo, Janaina B; Martins, Acácio A; Sousa, Rafael M; Andrade, Cristiano A

    2015-03-01

    The environmental benefits of producing biofuels from sugarcane have been questioned due to greenhouse gas emissions during the biomass production stage, especially nitrous oxide (NO) associated with nitrogen (N) fertilization. The objective of this work was to evaluate the use of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4 dimethylpyrazole phosphate (DMPP) and a controlled-release fertilizer (CRF) to reduce NO emissions from urea, applied at a rate of 120 kg ha of N. Two field experiments in ratoon cycle sugarcane were performed in Brazil. The treatments were (i) no N (control), (ii) urea, (iii) urea+DCD, (iv) urea+DMPP, and (v) CRF. Measurements of NO fluxes were performed using static chambers with four replications. The measurements were conducted three times per week during the first 3 mo and biweekly afterward for a total of 217 and 382 d in the first and second seasons, respectively. The cumulative NO-N emissions in the first ratoon cycle were 1098 g ha in the control treatment and 1924 g ha with urea (0.7% of the total N applied). Addition of NIs to urea reduced NO emissions by more than 90%, which did not differ from those of the plots without N. The CRF treatment showed NO emissions no different from those of urea. The results were similar in the second ratoon: the treatment with urea showed NO emissions of 0.75% of N applied N. Application of NIs resulted in a strong reduction in NO emissions, but CRF increased emissions compared with urea. We therefore conclude that both NIs can be options for mitigation of greenhouse gas emission in sugarcane used for bioenergy. PMID:26023961

  17. Influence of urea fertilizer placement on nitrous oxide production from a silt loam soil.

    PubMed

    Engel, R; Liang, D L; Wallander, R; Bembenek, A

    2010-01-01

    Urea placement in band or nests has been shown to enhance N use efficiency, but limited work has been done to assess its affect on N(2)O emissions. This study compared N(2)O emissions from urea prills applied to an Amsterdam silt loam (fine-silty, mixed, superactive, frigid Typic Haplustolls) using broadcast, band, and nest placements. Experiments were conducted in greenhouse pots (200 kg N ha(-1)) and in canola (Brassica rapa L.) seeded fields using rates of 100 kg N ha(-1) (recommended) and 200 kg N ha(-1). Urea placement affected N(2)O emission patterns and cumulative N(2)O losses in the greenhouse and field. Urea prills placed in nests, and sometimes bands delayed N(2)O production with peak flux activity occurring later, and elevated emission activity being more prolonged than for broadcast applications. Differences were more obvious at 200 kg N ha(-1). These effects were attributed to a delay in urea hydrolysis and inhibition of nitrification. The fraction of applied urea-N lost as N(2)O for broadcast, band, and nest placements applied at the recommended rate averaged 2.0, 2.7, and 5.8 g N kg(-1) N, respectively. The fraction of applied urea-N lost as N(2)O averaged 2.9, 10.4, and 9.2 g N kg(-1) N for broadcast, band, and nest placements when urea-N rate was increased from 100 to 200 kg N ha(-1), respectively. Greater N(2)O production with nest placement may in part be due to significant soil NO(2)-N accumulations. Potential benefits to crop fertilizer use efficiency that come with placement of urea in concentrated zones may lead to enhanced N(2)O production. PMID:20048299

  18. Effects of urea on the microstructure and phase behavior of aqueous solutions of polyoxyethylene surfactants

    PubMed Central

    Bianco, Carolina L.; Schneider, Craig S.; Santonicola, Mariagabriella; Lenhoff, Abraham M.; Kaler, Eric W.

    2010-01-01

    Membrane proteins are made soluble in aqueous buffers by the addition of various surfactants (detergents) to form so-called protein-detergent complexes (PDCs). Properties of membrane proteins are commonly assessed by unfolding the protein in the presence of surfactant in a buffer solution by adding urea. The stability of the protein under these conditions is then monitored by biophysical methods such as fluorescence or circular dichroism spectroscopy. Often overlooked in these experiments is the effect of urea on the phase behavior and micellar microstructure of the different surfactants used to form the PDCs. Here the effect of urea on five polyoxyethylene surfactants – n-octylytetraoxyethylene (C8E4), n-octylpentaoxyethylene (C8E5), n-decylhexaoxyethylene (C10E6), n-dodecylhexaoxyethylene (C12E6) and n-dodecyloctaoxylethylene (C12E8) – is explored. The presence of urea increases the critical micelle concentration (CMC) of all surfactants studied, indicating that the concentration of both the surfactant and urea should be considered in membrane protein folding studies. The cloud point temperature of all surfactants studied also increases with increasing urea concentration. Small-angle neutron scattering shows a urea-induced transition from an elongated to a globular shape for micelles of C8E4 and C12E6. In contrast, C8E5 and C12E8 form more globular micelles at room temperature and the micelles remain globular as the urea concentration is increased. The effects of increasing urea concentration on micelle structure are analogous to those of decreasing the temperature. The large changes in micelle structure observed here could also affect membrane protein unfolding studies by changing the structure of the PDC. PMID:21359094

  19. Urea transporter and glutamine synthetase regulation and localization in gulf toadfish gill.

    PubMed

    McDonald, M Danielle; Vulesevic, Branka; Perry, Steve F; Walsh, Patrick J

    2009-03-01

    The goal of the present study was to investigate the role of circulating cortisol and urea in the transcriptional regulation of branchial glutamine synthetase (GS), which incorporates NH(3) into glutamate to form glutamine, and the toadfish urea transporter, tUT, which is involved in urea excretion across the gill of the gulf toadfish. GS (of which there are two isoforms, LGS and GGS) and tUT mRNA expression and activity were measured in toadfish exposed to treatments that would induce variable stress responses. In addition, the role of circulating urea in tUT regulation was investigated by infusing toadfish with urea alone or in combination with intraperitoneal injection of RU486, a corticosteroid type II receptor antagonist. There was a 4.8-fold upregulation in the mRNA expression of the gill-specific GS isoform (GGS) in response to cortisol infusion and a similar upregulation in the more ubiquitous isoform (LGS). Furthermore, there was a significant 1.9-fold and 3.3-fold upregulation in the mRNA expression of the toadfish urea transporter, tUT, in response to stress through crowding or exogenous cortisol loading through infusion, respectively. In addition, tUT was found to have a urea-sensitive component to transcriptional regulation that was independent of circulating cortisol concentrations. However, the changes measured in mRNA expression of GGS, LGS and tUT did not correspond with changes in protein activity. To determine the cell type(s) involved in glutamine production and urea excretion, we attempted to localize GGS, LGS and tUT using in situ hybridization. This study is the first to show that GGS and tUT expression appear to occur in gill mitochondria-rich cells of toadfish, suggesting that these cells play a combined glutamine production and urea excretion role, which may have implications for predator avoidance. PMID:19218522

  20. Effect of 10.5 M Aqueous Urea on Helicobacter pylori Urease: A Molecular Dynamics Study.

    PubMed

    Minkara, Mona S; Weaver, Michael N; Merz, Kenneth M

    2015-07-01

    The effects of a 10.5 M solution of aqueous urea on Helicobacter pylori urease were investigated over the course of a 500 ns molecular dynamics (MD) simulation. The enzyme was solvated by 25321 water molecules, and additionally, 4788 urea molecules were added to the solution. Although concentrated urea solutions are known laboratory denaturants, the protein secondary structure is retained throughout the simulation largely because of the short simulation time (urea denaturation occurs on the millisecond time scale). The relatively constant solvent accessible surface area over the last 400 ns of the simulation further confirms the overall lack of denaturation. The wide-open flap state observed previously in Klebsiella areogenes urease [Roberts, B. P., et al. (2012) J. Am. Chem. Soc. 134, 9934] and H. pylori [Minkara, M. S., et al. (2014) J. Chem. Theory Comput. 10, 1852-1862] was also identified in this aqueous urea simulation. Over the course of the trajectory, we were able to observe urea molecules entering the active site in proportions related to the extent of opening of the active site-covering flap. Furthermore, urea molecules were observed to approach the pentacoordinate Ni(2+) ion in position to bind in a manner consistent with the proposed initial coordination step of the hydrolysis mechanism. We also observed a specific and unique pattern in the regions of the protein with a high root-mean-square fluctuation (rmsf). The high-rmsf regions in the ?-chain form a horseshoelike arrangement surrounding the active site-covering flap on the surface of the protein. We hypothesize that the function of these regions is to both attract and shuttle urea toward the loop of the active site-covering flap before entry into the cavity. Indeed, urea is observed to interact with these regions for extended periods of simulation time before active site ingress. PMID:26057619