Sample records for urea combustion route

  1. [Inhibition of chlorobenzene formation via various routes during waste incineration by ammonium sulfate and urea].

    PubMed

    Yan, Mi; Qi, Zhi-Fu; Li, Xiao-Dong; Hu, Yan-Jun; Chen, Tong

    2014-01-01

    Chlorobenzene (CBz) is the precursor of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) generated in the processes of waste incineration, and it is regarded as a good indicator of PCDD/Fs for realizing PCDD/Fs online monitoring, moreover, pentachlorobenzene (PeCBz) and Hexachlorobenzene (HxCBz) belong to Persistent Organic Pollutants (POPs). However, the emission control of CBz in waste incineration does not attract enough attention, so this study focused on the inhibition of the 3 CBz formation routes in waste combustion by ammonium sulfate and urea, including CB formation from fly ash, CB formation from 1,2-dichlorobenzene (1,2-DiCBz) and the combustion of model medical waste. The results showed that both ammonium sulfate and urea reduced CBz yield during these three thermal processes. For instance, the inhibition rates of tetrachlorobenzene (TeCBz), PeCBz and HxCBz were 66.8%, 57.4% and 50.4%, respectively, when 1% urea was co-combusted with medical waste. By comparing the effect of ammonium sulfate and urea on CBz formation by three routes, urea was considered as a comparatively stable inhibitor for CBz. PMID:24720230

  2. Novel route for layered double hydroxides preparation by enzymatic decomposition of urea

    NASA Astrophysics Data System (ADS)

    Vial, S.; Prevot, V.; Forano, C.

    2006-05-01

    This study presents a new route for the preparation of a series of layered double hydroxide materials with controlled textural properties. It concerns the biogenesis of hydrotalcite like phases by Jack bean urease through the enzymatic decomposition process of urea. Different conditions of LDH biogenesis are investigated (urease activity, urea concentration). A comparative study with the precipitation method based on the thermal decomposition of urea (90 °C) is conducted in order to asses the effect of the various urea hydrolysis conditions (kinetic, temperature) and the presence of enzyme in the reaction medium on the structural and textural properties of the as prepared LDH materials. Mechanisms of formation of the LDH phases for both synthesis processes are discussed on basis of their pH control. The PXRD and SEM analysis of samples prepared by the thermal process evidence higher crystallinity and greater particle sizes than LDH obtained in mild biogenic conditions. In the latter case, presence of urease or effect of some M(II) metals may inhibit the crystallization.

  3. Synthesis of nanocrystalline yttria doped ceria powder by urea-formaldehyde polymer gel auto-combustion process

    SciTech Connect

    Biswas, M. [Ceramic Division, Naval Materials Research Laboratory, Defence Research and Development Organization, Shil Badlapur Road, Anandnagar P.O., Addl. Ambernath, Thane 421 506 (India); Prabhakaran, K. [Ceramic Division, Naval Materials Research Laboratory, Defence Research and Development Organization, Shil Badlapur Road, Anandnagar P.O., Addl. Ambernath, Thane 421 506 (India)]. E-mail: kp2952002@yahoo.co.uk; Gokhale, N.M. [Ceramic Division, Naval Materials Research Laboratory, Defence Research and Development Organization, Shil Badlapur Road, Anandnagar P.O., Addl. Ambernath, Thane 421 506 (India); Sharma, S.C. [Ceramic Division, Naval Materials Research Laboratory, Defence Research and Development Organization, Shil Badlapur Road, Anandnagar P.O., Addl. Ambernath, Thane 421 506 (India)

    2007-04-12

    Nanocrystalline yttria doped ceria powder has been prepared by auto-combustion of a transparent gel formed by heating an aqueous acidic solution containing methylol urea, urea, cerium(III) nitrate and yttrium(III) nitrate. The TGA and DSC studies showed the combustion reaction of the gel initiated at 225 deg. C and completed within a short period of time. XRD spectrum of the combustion product reveals the formation of phase pure cubic yttria doped ceria during the combustion process. Loose agglomerate of yttria doped ceria particle obtained by the combustion reaction could be easily deagglomerated by planetary ball milling and the powder obtained contains particles in the size range of 0.05-3.3 {mu}m with D {sub 50} value of 0.13 {mu}m. The powder particles are aggregate of nanocrystallites with a wide size range of 14-105 nm. Pellets prepared by pressing the yttria doped ceria powder sintered to 95.2% TD at 1400 deg. C.

  4. Synthesis of mesoporous silica-alumina materials via urea-templated sol-gel route and their catalytic performance for THF polymerization

    NASA Astrophysics Data System (ADS)

    Ge, Yuanyuan; Jia, Zhiqi; Gao, Chunguang; Gao, Pengfei; Zhao, Lili; Zhao, Yongxiang

    2014-10-01

    A series of mesoporous silica-alumina materials was successfully synthesized by using urea as a low-cost template via sol-gel routes. The characterization results showed that the employ of urea enhanced the porosity of the silica-alumina materials and made the pore size distributions become narrower. The specific surface area, pore volume and pore diameter of SAU-X firstly increased and then decreased as the urea concentration increased from 0 to 60 wt %, and the maximums were obtained at 40 wt % urea concentration. All samples were tested for the THF polymerization. Among them, SAU-40 exhibited the highest activity and the longest catalyst life due to its superior porosity.

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

    SciTech Connect

    Chang, Ying [Department of Materials, College of Chemical and Environment Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)] [Department of Materials, College of Chemical and Environment Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China); Dong, Shijie, E-mail: dongsjsj@163.com [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)] [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China); Wang, Huihu [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)] [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China); Du, Kuanhe; Zhu, Qingbiao [Department of Materials, College of Chemical and Environment Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)] [Department of Materials, College of Chemical and Environment Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China); Luo, Ping [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)] [School of Mechanical Engineering, Hubei University of Technology, Wuhan, Hubei 430068 (China)

    2012-03-15

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

  6. 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.

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

    SciTech Connect

    Payette, R. [Ohio Dept. of Transportation, Jacksontown, OH (United States). District 5; Chen, X.Y.; Wolfe, W. [Ohio State Univ., Columbus, OH (United States); Beeghly, J. [Dravo Lime Co., Pittsburgh, PA (United States)

    1995-12-31

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

  8. Combustion synthesis and thermal expansion measurements of the rare earth-uranium ternary oxides RE 6UO 12 (RE=La, Nd and Sm)

    NASA Astrophysics Data System (ADS)

    Jena, Hrudananda; Asuvathraman, R.; Govindan Kutty, K. V.

    2000-08-01

    Rare earth-uranium ternary oxides were synthesized by a solution combustion route. The starting materials were the corresponding metal nitrates and urea. In these preparations, the metal nitrates act as oxidizer and urea as fuel. Highly exothermic decomposition of the metal nitrate-urea complexes on heating at about 500 K leads to a combustion process yielding RE 6UO 12 fine powders. Thermal expansion measurements of these compounds were carried out in the temperature range of 298-1173 K by high temperature X-ray powder diffractometry. The observed axial thermal expansion behaviour is explained on the basis of the crystal chemistry of the compounds.

  9. A comparative study on structural, morphological and luminescence characteristics of Zn 3(VO 4) 2 phosphor prepared via hydrothermal and citrate-gel combustion routes

    Microsoft Academic Search

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    SciTech Connect

    Andre Boehman; Daniel Haworth

    2008-09-30

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

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

    PubMed

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

    2015-03-17

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

  13. 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.

  14. Combustion

    NSDL National Science Digital Library

    2014-01-28

    In this chemistry activity, learners discover that the weight of the product of combustion is greater than that of the starting material. Learners will compare the weight of steel wool before and after it is heated. Learners are asked to consider why the steel wool weighs more (oxidation) as well as write the balanced chemical equation for the burning of steel. This activity uses an open flame; adult supervision is recommended. The resource includes notes for educators and extension ideas.

  15. Nano crystalline ceria-neodymia solid solutions by combustion route: effect of agglomeration on powder properties.

    PubMed

    Bedekar, Vinila; Tyagi, A K

    2007-09-01

    About 8 compositions in the system Ce(1-x)Nd(x)O(2-x/2) (0.0 < or = x < or = 0.50) were prepared by the combustion process using glycine as a fuel and corresponding metal nitrates as the oxidants. The oxidant-to-fuel ratio was taken as 1:1.0. The products were characterized by X-ray diffraction (XRD), surface area, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering, sinterability etc. The crystallite size of powders, as obtained by the line broadening method, was typically in the range of 7 to 16 nm. The deagglomeration studies carried out showed that the average agglomerate size of these powders increases with increasing content of Nd in CeO2. The powders were sintered at 1200 degrees C to yield densities in the range of 80-95% of theoretical densities. This wide variation in the sintered density was explained based on the powder properties. An interesting observation was that the nature and size of the agglomerates plays an important role in governing properties such as sintered density and in turn ionic conductivity of nano ceramics. PMID:18019152

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

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

    PubMed

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

    2015-04-01

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

  18. Controlling the composition, microstructure, electrical and magnetic properties of LiFe5O8 powders synthesized by sol gel auto-combustion method using urea as a fuel

    NASA Astrophysics Data System (ADS)

    Rashad, M. M.; El-Shaarawy, M. G.; Shash, N. M.; Maklad, M. H.; Afifi, F. A.

    2015-01-01

    Nanocrystalline lithium ferrite LiFe5O8 powders were synthesized by the sol gel auto-combustion method from the corresponding metal nitrates using urea as a fuel. DTA results showed that the LiFe5O8 phase started to form at temperature around 385 °C. X-ray diffraction analysis indicates that all compositions were formed in a single-phase cubic spinel structure at different annealing temperatures from 400 to 800 °C for 2 h. The lattice parameter was found to decrease whereas the particle size was increased with annealing temperature. The frequency exponent "s" of lithium ferrite lies in the range 0.5?s?1, which confirmed the electron hopping between Fe2+ and Fe3+ ions. The electron mobility in LiFe5O8 samples ranged from 0.05 to 0.29 eV, which clearly indicated that the present lithium ferrites have semiconductor-like behavior. The saturation magnetization was increased on increasing the annealing temperature up to 800 °C. High saturation magnetization (Ms=51.9 emu/g) was achieved for the ferrite powders produced at annealing temperature 800 °C for 2 h.

  19. Water and urea transport in renal microvillus membrane vesicles

    SciTech Connect

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

    1985-05-01

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

  20. The urea cycle disorders.

    PubMed

    Helman, Guy; Pacheco-Colón, Ileana; Gropman, Andrea L

    2014-07-01

    The urea cycle is the primary nitrogen-disposal pathway in humans. It requires the coordinated function of six enzymes and two mitochondrial transporters to catalyze the conversion of a molecule of ammonia, the ?-nitrogen of aspartate, and bicarbonate into urea. Whereas ammonia is toxic, urea is relatively inert, soluble in water, and readily excreted by the kidney in the urine. Accumulation of ammonia and other toxic intermediates of the cycle lead to predominantly neurologic sequelae. The disorders may present at any age from the neonatal period to adulthood, with the more severely affected patients presenting earlier in life. Patients are at risk for metabolic decompensation throughout life, often triggered by illness, fasting, surgery and postoperative states, peripartum, stress, and increased exogenous protein load. Here the authors address neurologic presentations of ornithine transcarbamylase deficiency in detail, the most common of the urea cycle disorders, neuropathology, neurophysiology, and our studies in neuroimaging. Special attention to late-onset presentations is given. PMID:25192511

  1. Urea Cycle Disease Overview

    MedlinePLUS

    ... such as ammonia. Ammonia is a product of protein digestion and the urea cycle is required for the body to excrete ammonia. In patients with partial enzyme deficiencies, the first recognized clinical episode may be ...

  2. Synthesis of nanosized bismuth ferrite (BiFeO 3 ) by a combustion method starting from Fe(NO 3 ) 3 ·9H 2 OBi(NO 3 ) 3 ·9H 2 O-glycine or urea systems

    Microsoft Academic Search

    Carmen Paraschiv; B. Jurca; Adelina Ianculescu; Oana Carp

    2008-01-01

    Two bismuth ferrite potential precursors systems, namely Fe(NO3)3·9H2O-Bi(NO3)3·9H2O-glycine\\/urea with different metal nitrate\\/organic compound molar ratios have been investigated in order to evaluate their\\u000a suitability as BiFeO3 precursors. The presence into the precursor of both reducing (glycine and urea) and oxidizing (NO3?) components, modifies dramatically their thermal behaviour comparative with the raw materials, both from the decomposition\\u000a stoichiometries and temperature occurrence

  3. 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.

  4. 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.

  5. 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.

  6. Combustion synthesis: A suitable method to prepare Al 2 O 3 doped materials for thermoluminescent dosimetry

    Microsoft Academic Search

    Vinícius S. M. de Barros; Walter M. de Azevedo; Helen J. Khoury; Pedro Linhares Filho

    2008-01-01

    In this work we present an alternative route to synthesize rare-earth doped aluminum oxide materials for thermoluminescent (TL) dosimetry using the combustion synthesis (CS) technique. The samples were prepared by mixing aluminum nitrate (Al(NO3)3·9H2O), urea (CO(NH2)2), and europium nitrate (Eu(NO3)3), terbium nitrate (Tb(NO3)3) and tetra-ethyl-ortho-silicate (TEOS, C8H20O4Si) in appropriate amounts as dopants in an aqueous solution. The excess water was

  7. Flash synthesis of Li2TiO3 powder by microwave-induced solution combustion

    NASA Astrophysics Data System (ADS)

    Zhou, Qilai; Tao, Liyao; Gao, Yue; Xue, Lihong; Yan, Youwei

    2014-12-01

    Nano-crystalline Li2TiO3 powder was prepared by a microwave-induced solution combustion synthesis (MSCS) route using urea as fuel. It is observed that combustion reaction, which did not occur by conventional heating, happened when microwave heating was induced. The as-synthesized Li2TiO3 powder exhibits a narrow size distribution. In MSCS, the total metal ion concentration (Cm) in the starting solution plays an important role. By changing Cm values in starting solution, SCS process including ignition time, combustion period and reaction rate can be controlled. The as-prepared powder could be sintered up to 92.6% of the theoretical density at 1223 K.

  8. Towards optoelectronic urea biosensors.

    PubMed

    Pokrzywnicka, Marta; Koncki, Robert; Tymecki, ?ukasz

    2015-03-01

    Integration of immobilized enzymes with light-emitting diodes (LEDs) leads to the development of optoelectronic enzyme-based biosensors. In this work, urease, used as a model enzyme, immobilized in the form of an open-tubular microbioreactor or biosensing membrane that has been integrated with two red LEDs. It forms complete, fiberless, miniaturized, and extremely economic biooptoelectronic devices useful for nonstationary measurements under flow analysis conditions. Both enzyme-based biodevices, operating according to the paired emitter detector diode (PEDD) principle, allow relatively fast, highly sensitive, and well-reproducible urea detection in the millimolar range of concentrations. Potential analytical applications of the developed urea bioPEDDs have been announced. Both presented constructions will be easily adapted for the development of other optoelectronic biosensors exploring various enzyme-based schemes of biodetection. PMID:25619983

  9. Quinine and Urea

    NSDL National Science Digital Library

    The WebWare molecules of the month are discussed in two laboratory articles in this issue. Quinine is studied in the article "A Fluorimetric Approach to Studying the Effects of Ionic Strength on Reaction Rates: An Undergraduate Steady-State Fluorescence Laboratory Experiment" by Stephen W. Bigger, Peter J. Watkins, and Bruce Verity. Urea, a typical protein denaturant, is used as a cosolvent in the article "Transfer Free Energy and the Hydrophobic Effect" by Joseph M. Serafin.

  10. 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.

  11. Uptake of urea C and urea N by the coastal marine diatom Thalassiosira pseudonana

    Microsoft Academic Search

    NEIL M. PRICE; Paul J.-Harrison

    1988-01-01

    Urea uptake rates of Thalassiusiru pseudonana (clone 3H) were determined using (14C)urea, (15N)urea, and by measuring disappearance of dissolved urea from the medium after adding 10 lg-atoms urea-N liter-'. In nitrate-sufficient cultures, the average (14C)urea uptake rate was 60% of the urea disappearance rate. Nitrate uptake continued in the presence of urea at a reduced rate, and only 15% of

  12. Urea and urea nitrate decomposition pathways: a quantum chemistry study.

    PubMed

    Tokmakov, Igor V; Alavi, Saman; Thompson, Donald L

    2006-03-01

    Electronic structure calculations have been performed to investigate the initial steps in the gas-phase decomposition of urea and urea nitrate. The most favorable decomposition pathway for an isolated urea molecule leads to HNCO and NH3. Gaseous urea nitrate formed by the association of urea and HNO3 has two isomeric forms, both of which are acid-base complexes stabilized by the hydrogen-bonding interactions involving the acidic proton of HNO3 and either the O or N atoms of urea, with binding energies (D0(o), calculated at the G2M level with BSSE correction) of 13.7 and 8.3 kcal/mol, respectively, and with estimated standard enthalpies of formation (delta(f)H298(o) of -102.3 and -97.1 kcal/mol, respectively. Both isomers can undergo relatively facile double proton transfer within cyclic hydrogen-bonded structures. In both cases, HNO3 plays a catalytic role for the (1,3) H-shifts in urea by acting as a donor of the first and an acceptor of the second protons transferred in a relay fashion. The double proton transfer in the carbonyl/hydrogen bond complex mediates the keto-enol tautomerization of urea, and in the other complex the result is the breakdown of the urea part to the HNCO and NH3 fragments. The enolic form of urea is not expected to accumulate in significant quantities due to its very fast conversion back to H2NC(O)NH2 which is barrierless in the presence of HNO3. The HNO3-catalyzed breakdown of urea to HNCO and NH3 is predicted to be the most favorable decomposition pathway for gaseous urea nitrate. Thus, HNCO + NH3 + HNO3 and their association products (e.g., ammonium nitrate and isocyanate) are expected to be the major initial products of the urea nitrate decomposition. This prediction is consistent with the experimental T-jump/FTIR data [Hiyoshi et al. 12th Int. Detonation Symp., Aug 11-16, San Diego, CA, 2002]. PMID:16494387

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  14. Urea nitrogen for potatoes

    Microsoft Academic Search

    K. B. Tyler; O. A. Lorenz; F. H. Takatori; J. C. Bishop

    1962-01-01

    Summary and Conclusions  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a The source of nitrogen influenced the total yield of potato tubers, the nutrient concentrations in the potato petiole and\\u000a the appearance of growing plants, especially in fields of low available phosphorus.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a Urea resulted in higher nitrate-nitrogen, calcium, and magnesium concentrations in the plant petiole, but in lower phosphate-phosphorus\\u000a concentrations as compared with ammonium sulfate.\\u000a \\u000a \\u000a \\u000a \\u000a 3. 

  15. Synthesis of LiCo 1- xNi xO 2 from a low temperature solution combustion route and characterization

    NASA Astrophysics Data System (ADS)

    Suresh, P.; Rodrigues, S.; Shukla, A. K.; Shivashankar, S. A.; Munichandraiah, N.

    Nickel substituted lithium-cobalt oxides, LiCo 1- xNi xO 2 (0< x<0.4), have been synthesized in a very short time by a solution combustion method at 350 °C using diformyl hydrazine as a fuel. Pure phases with hexagonal lattice structure have been obtained. These compounds facilitate reversible insertion/extraction of Li + ions with good discharge capacity between 3.0 and 4.4 V versus Li/Li +. Results of the studies by powder X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic charge-discharge cycling and ac impedance measurements are presented.

  16. Urea Biosynthesis Using Liver Slices

    ERIC Educational Resources Information Center

    Teal, A. R.

    1976-01-01

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

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

    E-print Network

    Park, Yong Hun

    2004-09-30

    was injected into the gases as a urea-water solution. The decomposition processes of the urea-water solutions and urea powder were examined. For both the nitric oxide removal and the urea decomposition experiments, a Fourier transform infrared (FTIR...

  18. OSMOREGULATION IN DROSOPHILA MELANOGASTERSELECTED FOR UREA TOLERANCE

    Microsoft Academic Search

    VALERIE A. PIERCE; LAURENCE D. MUELLER; ALLEN G. GIBBS

    Animals may adapt to hyperosmolar environments by either osmoregulating or osmoconforming. Osmoconforming animals generally accumulate organic osmolytes including sugars, amino acids or, in a few cases, urea. In the latter case, they also accumulate 'urea- counteracting' solutes to mitigate the toxic effects of urea. We examined the osmoregulatory adaptation of Drosophila melanogaster larvae selected to live in 300 mmol l

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Spectroscopic characterization of urea aqueous solutions: experimental phase diagram of the urea-water binary system.

    PubMed

    Durickovic, Ivana; Thiébaud, Laura; Bourson, Patrice; Kauffmann, Thomas; Marchetti, Mario

    2013-10-01

    Raman spectroscopy was used to analyze mixtures of urea and water in order to identify the influence of the urea concentration on the solution's freezing point. Our approach consisted in the analysis of urea aqueous solutions and the determination of their phase transitions at low temperatures. Hence, Raman spectra of these solutions were acquired in a -30 to 10 °C temperature range. This enabled us to build the experimental phase diagram of the urea-water binary system. PMID:24067578

  4. A technique for predicting urea release from coated urea in wetland soil

    Microsoft Academic Search

    N. K. Savant; J. R. Clemmons; A. F. James

    1982-01-01

    A simple technique for measuring urea release from different coated urea fertilizer materials in simulated wetland soil has been developed and tested. The laboratory soil system used simulates physical, chemical, and microbiological environments of wetland soils under field conditions. Laboratory and field values for urea release are in good agreement.

  5. Critical conditions for combustion of materials made from polymer fibers

    SciTech Connect

    Vilkova, S.A.; Krupkin, V.G.; Margolin, A.D.

    1986-11-01

    The authors comparatively test the following polymer fibers for their combustion and flame resistant properties: unmodified viscose fiber; viscose fiber modified with a salt of polyethylene-polyamine; viscose fiber modified with diamidomethylphosphate and urea; copolymer fibers Verel and Canekalon; polyacrylonitrile fiber; polyvinylchloride fiber; polycaproamide fiber; and polyester fiber. They determine and graphically depict the relation between the limiting combustion dimensions and the concentration of oxygen in the atmosphere and account also for the effect of chlorine content on the combustion process.

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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.

  12. Transport characteristics of urea transporter-B.

    PubMed

    Yang, Baoxue

    2014-01-01

    UT-B represents the major urea transporter in erythrocytes, in addition to being expressed in kidney descending vasa recta, brain, spleen, ureter, bladder, and testis. Expression of urea transporter UT-B confers high urea permeability to mammalian erythrocytes. Erythrocyte membranes are also permeable to various urea analogues, suggesting common transport pathways for urea and structurally similar solutes. UT-B is highly permeable to urea and the chemical analogues formamide, acetamide, methylurea, methylformamide, ammonium carbamate, and acrylamide, each with a Ps > 5.0 × 10(-6) cm/s at 10 °C. The amides formamide, acetamide, acrylamide, and butyramide efficiently diffuse across lipid bilayers. The urea analogues dimethylurea, acryalmide, methylurea, thiourea, and methylformamide inhibit UT-B-mediated urea transport by >60 % by a pore-blocking mechanism. UT-B is also a water channel in erythrocytes and has a single-channel water permeability that is similar to aquaporin-1. Whether UT-B is an NH3 channel still needs further study. Urea permeability (Purea) in erythrocytes differs between different mammals. Carnivores (dog, fox, cat) exhibit high Purea. In contrast, herbivores (cow, donkey, sheep) show much lower Purea. Erythrocyte Purea in human and pig (omnivores) was intermediate. Rodents and lagomorphs (mouse, rat, rabbit) have Purea intermediate between carnivores and omnivores. Birds that do not excrete urea and do not express UT-B in their erythrocytes have very low values. In contrast to Purea, water permeability is relatively similar in all mammals studied. This chapter will provide information about the transporter characteristics of UT-B. PMID:25298342

  13. Combustion noise

    NASA Technical Reports Server (NTRS)

    Strahle, W. C.

    1977-01-01

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

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

    PubMed Central

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

    2013-01-01

    Background Like several other parasites, Teladorsagia circumcincta secretes or excretes urea, but neither the rate of efflux nor the possible metabolic sources of the urea has been considered. Methods Parasites were maintained by passage through sheep. Urea efflux was measured using phenol/hypochlorite after treatment with urea aminohydrolase. The kinetics of creatine amidinohydrolase and arginine amidinohydrolase were characterised by coupling the reactions with urea aminohydrolase and glutamate dehydrogenase. Results Infective L3 T. circumcincta secreted or excreted urea at 25% of the rate of NH3/NH4 +. The rate of urea efflux was about 84 pmol h?1 (103 larvae)?1 over 4 hours, corresponding to about 11 nmol h?1 mg?1 protein. We could not detect urea aminohydrolase activity, but urea production by both creatine amidinohydrolase and arginine amidinohydrolase could be detected. The apparent K m and V max of creatine amidinohydrolase were 1.1 mM and 48 nmol h?1 mg?1 protein, respectively, and the activity was greatest at pH 8. The apparent K m and V max of arginine amidinohydrolase were 0.7 mM and 62 nmol h?1 mg?1 protein, respectively, and the activity was greatest at pH 7.9. Conclusion The activity of creatine amidinohydrolase and arginine amidinohydrolase was sufficient to account for the rate of urea secretion or excretion. PMID:23682271

  15. Effect of oxygenated liquid additives on the urea based SNCR process

    Microsoft Academic Search

    M. Tayyeb Javed; W. Nimmo; Asif Mahmood; Naseem Irfan

    2009-01-01

    An experimental investigation was performed to study the effect of oxygenated liquid additives, H2O2, C2H5OH, C2H4(OH)2 and C3H5(OH)3 on NOx removal from flue gases by the selective non-catalytic reduction (SNCR) process using urea as a reducing agent. Experiments were performed with a 150kW pilot scale reactor in which a simulated flue gas was generated by the combustion of methane operating

  16. Combustion monitoring

    SciTech Connect

    Not Available

    1993-07-01

    This article describes application analysis system to lean-burn engines, engines that feature EGR, or other engines in which unfavorable combustion occurs, to control engine roughness, lower fuel consumption, and reduce NOx emission and combustion inconsistencies among cylinders. The idea of monitoring combustion of an internal combustion engine, and using the obtained data to control combustion, is not new. Two well-known methods have been developed: one involves combustion-pressure analysis, and the other measures ionic currents in combustion gas. Although highly precise analysis can be achieved by the former, there are problems in the installation of combustion pressure sensors, and their durability and cost. There are also problems in installing ionic-current sensors, and the reliability of data obtained from such sensors is questionable. Researchers at Honda R and D Co. and NGK Spark Plug Co. have developed a method which uses spark-plug-voltage analysis for monitoring combustion. Voltage is measured by noncontact sensors in the high-voltage zone near the spark plugs. Monitoring is done in real time by processing waveform data and measuring the ion density. This monitoring system can control combustion during fluctuations of the air/fuel ratio (A/F), exhaust gas recirculation (EGR), and ignition timing for lean-burn or other conventional engines. By controlling combustion near the lean, EGR, and timing limits, it is possible to reduce fuel consumption and exhaust emissions, while maintaining driveability.

  17. Streamflow Routing

    NSDL National Science Digital Library

    COMET

    2006-03-17

    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.

  18. Urea reduction ratio that considers effects of ultrafiltration and intradialytic urea generation

    Microsoft Academic Search

    Yuk Lun Cheng; Koon Shing Choi; Ka Foon Chau; Chun Sang Li; Cheen Unn Yung; Alex W Yu; Kwan Keung Wong

    2001-01-01

    We modified the urea reduction ratio (URR) equation to correct the effects of ultrafiltration and intradialytic urea generation on the delivered dose of hemodialysis: muRR = 1?R1+2?UFBW+0.01?t×100% where mURR is modified URR, R is postdialysis plasma urea nitrogen (PUN) to predialysis PUN ratio, UF is ultrafiltrate volume in liters, BW is postdialysis body weight in kilograms, and t is dialysis

  19. Urea release from silicate- and polymer-coated urea in water and a simulated wetland soil

    Microsoft Academic Search

    NK Savant; AF James; GH McClellan

    1983-01-01

    Urea release rates in water (38°C) and in a simulated wetland soil system under greenhouse conditions from silicate- and polymer-coated urea (SPCU) materials have been studied. The SPCU materials were prepared by the Korea Advanced Institute of Science and Technology (KAIST), Seoul, Korea, in cooperation with the International Fertilizer Development Center (IFDC). Average urea release (\\u000a$$\\\\overline {UR} $$\\u000a)

  20. ESTIMATION OF BOVINE CARCASS COMPOSITION BY THE UREA DILUTION TECHNIQUE

    Microsoft Academic Search

    S. W. Kock; R. L. Preston

    2010-01-01

    SUMMARY One hundred and thirteen beef type steers of varying live weight and degrees of fatness were used to study the reliability and usefulness of urea space measured at varying times after urea infusion for estimating body composition in the live animal. Urea space measured 12 min following urea infusion proved to be the best time as judged from correlation

  1. Urea and deuterium mixtures at high pressures.

    PubMed

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

    2015-03-28

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D2 mixtures that indicate no inclusion compound forms up to 3.7 GPa. PMID:25833592

  2. What Is a Urea Cycle Disorder?

    MedlinePLUS

    ... involves a series of biochemical steps in which nitrogen, a waste product of protein metabolism, is removed ... from the body. In urea cycle disorders, the nitrogen accumulates in the form of ammonia, a highly ...

  3. High nonlinear optical anisotropy of urea nanofibers

    NASA Astrophysics Data System (ADS)

    Isakov, D.; de Matos Gomes, E.; Belsley, M.; Almeida, B.; Martins, A.; Neves, N.; Reis, R.

    2010-07-01

    Nanofibers consisting of the optically nonlinear organic molecule urea embedded in both poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) polymers were produced by the electrospinning technique. The second-harmonic generation produced by aligned fiber mats of these materials displays a strong dependence on the polarization of the incident light. In PVA-urea nanofibers the effectiveness in generating of the second-harmonic light is as high as that of a pure urea powder with an average grain size of 110 ?m. The results suggest that single crystalline urea nanofibers were achieved with a long-range crystalline order extending into the range of 2-4 ?m with PVA as the host polymer.

  4. Detection of Interstellar Urea with Carma

    Microsoft Academic Search

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

    2010-01-01

    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

  5. a Search for Interstellar Urea with Carma

    Microsoft Academic Search

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

    2009-01-01

    Urea, a molecule discovered in human urine by H. M Rouelle in 1773, also plays 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 the other large molecules methyl formate and acetic acid (2008, 63rd OSU Symposium On Molecular Spectroscopy, RF11). We have conducted an extensive

  6. 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

  7. Nitrous Oxide Gas Fluxes in a Potato Field Following Application of Urea and Coated Urea Fertilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Application of urea and other forms of nitrogen (N) fertilizer can generate atmospheric emissions of nitrous oxide (N2O), which is a potent greenhouse gas. Field experiments were conducted on a loamy sand soil in Becker, Minnesota to evaluate the effects of soluble and coated forms of urea on N2O fl...

  8. 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]...

  9. 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.

  10. Low-temperature heat capacity of urea

    NASA Astrophysics Data System (ADS)

    Andersson, O.; Matsuo, T.; Suga, H.; Ferloni, P.

    1993-01-01

    The heat capacity of urea was measured with an adiabatic calorimeter in the temperature range 15 310 K. The data were extrapolated to 0 K by a model function to derive some standard thermodynamic functions including the enthalpy increments ? {0/T}H, the entropy increments ? {0/T}S, and the Giauque function (= ? {0/TS}- ? {0/T} H/T). A simple model for the reproduction of the experimental heat capacities of urea, based on the Debye and Einstein functions, is described. The Debye characteristic temperature determined in this way was compared with those calculated from properties other than the heat capacity. Any positive evidence of a suggested phase transition in urea around 190 K was not observed in the present heat capacity measurements. Possible existence of a phase with a Gibbs energy lower than that realized in the present investigation is discussed briefly.

  11. The incidence of urea cycle disorders

    PubMed Central

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

    2014-01-01

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

  12. Wood plastic composite at different urea concentrations

    NASA Astrophysics Data System (ADS)

    Husain, M. M.; Khan, Mubarak A.; Ali, K. M. Idriss; Hasan, A. J. M. Moynul

    1995-04-01

    Wood plastic composite (WPC) has been prepared with a low grade wood simul ( Salmalia malabarica) of Bangladesh under Co-60 gamma irradiation using MMA as the bulk monomer combined with methanol as the swelling solvent at different urea concentrations. Effect of a second solute such as NVP, TPGDA and TMPTA in the impregnating solution is evaluated. NVP appears to be the best co-additive/second solute among all the additives used to yield the composite with the highest polymer loading (PL) and tensile strength (TS) at 0.5% urea concentration.

  13. Combustion Physics.

    ERIC Educational Resources Information Center

    Jones, A. R.

    1985-01-01

    Discusses how physics is used to improve the efficiency of combustion, pointing out that the interdisciplinary topic has applications to problems of real industrial relevance and practical value. (JN)

  14. Combustion & Health

    E-print Network

    Hamilton, W.

    2012-01-01

    ) ? Combustion of fossil fuels for ? Electricity ? Industrial processes ? Vehicle propulsion ? Cooking and heat ? Other ? Munitions ? Fireworks ? Light ? Cigarettes, hookahs? FFCOMBUSTION & HEALTH FFCOMBUSTION: THE THREAT ? SCALE (think health... for public health and strategies to reduce GHG ? Reduce CO2 emissions by 50% by 2030 ? Reduction in PM2.5 deaths greatly offset costs in all models FFCOMBUSTION & HEALTH FFCOMBUSTION: PM EXPOSURE ? Combustion is source of most concern ? Health...

  15. Urea: a comprehensive review of the clinical literature

    E-print Network

    Pan, Michael; Heinecke, Gillian; Bernardo, Sebastian; Tsui, Cindy; Levitt, Jacob

    2013-01-01

    effect of salicylic acid and urea in human skin. Skinsalicylic acid alone CT Single 4-hour application on back skinsalicylic acid ointment, and paraffin-based moisturizers [17]. The beneficial effects of urea on ichthyotic skin

  16. A blend of dietary fibers increases urea disposal in the large intestine and lowers urinary nitrogen excretion in rats fed a low protein diet

    Microsoft Academic Search

    Hassan Younes; Christian Demigné; Stephen R. Behr; Keith A. Garieb; Christian Rémésy

    1996-01-01

    The presence of rapidly fermented indigestible carbohydrates in the diet has been shown to influence intestinal fermentations and the route of excretion of urea nitrogen. The objective of the present study was to determine the effects of a dietary fiber blend on nitrogen excretion in the rat. The dietary fiber blend studied (the “oligo\\/fiber blend”) was comprised of 41.2% fructooligosaccharides,

  17. 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

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

    PubMed

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

    2015-02-01

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

  19. 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.

  20. Foliar urea fertilization of cereals: A review

    Microsoft Academic Search

    M. J. Gooding; W. P. Davies

    1992-01-01

    It has been suggested that there are several potential benefits of providing nitrogen to cereals via the foliage as urea solution. These include: reduced nitrogen losses through denitrification and leaching compared with nitrogen fertilizer applications to the soil; the ability to provide nitrogen when root activity is impaired e.g., in saline or dry conditions, and uptake late in the season

  1. 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.

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-09

    ...340-E and 340-H (Third Review)] Solid Urea From Russia and Ukraine Determination...revocation of the antidumping duty orders on solid urea from Russia and Ukraine would be likely...Publication 4279 (December 2011), entitled Solid Urea from Russia and Ukraine:...

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-21

    ...731-TA-340-E and 340-H (Third Review)] Solid Urea From Russia and Ukraine AGENCY: United...concerning the antidumping duty orders on solid urea from Russia and Ukraine...revocation of the antidumping duty orders on solid urea from Russia and Ukraine would be...

  4. 75 FR 74746 - Solid Urea From Russia and Ukraine

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-01

    ...731-TA-340-E and 340-H (Third Review)] Solid Urea From Russia and Ukraine AGENCY: United...concerning the antidumping duty orders on solid urea from Russia and Ukraine...revocation of the antidumping duty orders on solid urea from Russia and Ukraine would be...

  5. 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. ...

  6. Protecting group free synthesis of urea-linked glycoconjugates: efficient synthesis of ?-urea glycosides in aqueous solution.

    PubMed

    Ichikawa, Yoshiyasu; Minami, Takahiro; Kusaba, Shohei; Saeki, Nobuyoshi; Tonegawa, Yuta; Tomita, Yumiko; Nakano, Keiji; Kotsuki, Hiyoshizo; Masuda, Toshiya

    2014-06-21

    A method for the protecting group free synthesis of ?-urea-linked glycoconjugates has been developed. The one step process, involving reactions between urea and D-glucose, N-acetyl-D-glucosamine or D-xylose in acidic aqueous solution, furnishes the corresponding ?-urea glycosides in modest yields. This simple and efficient procedure is applicable to the synthesis of ?-urea tethered amino acid-carbohydrate conjugates. PMID:24796538

  7. Reduction of NOx emissions from a dry process preheater kiln with calciner through the use of the urea based SNCR process

    Microsoft Academic Search

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

    1995-01-01

    The post combustion reduction of NOx using urea has proven to be an effective method in controlling NOx from various combustion sources. Such a reduction process has been successfully demonstrated in a week-long test at Ash Grove's dry process cement kiln system located in Seattle. This system is equipped with planetary coolers, a 5-stage preheater and an air-through-the-kiln calciner, Testing

  8. Reduction of NOx emissions from a dry process preheater kiln with calciner through the use of the urea-based SNCR process

    Microsoft Academic Search

    Hans E. Steuch; Jon T. Hille; William H. Sun; Michael J. Bisnett; Douglas W. Kirk

    1996-01-01

    The post combustion reduction of NOx using urea has proven to be an effective method in controlling NOx from various combustion sources, such a reduction process has been successfully demonstrated in a week-long test at Ash Grove's dry process cement kiln system located in Seattle. This system is equipped with planetary coolers, a 5-stage preheater and an air-through-the-kiln calciner. Testing

  9. 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. ...

  10. 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...

  11. Turbulent combustion

    SciTech Connect

    Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

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

  12. Small-Molecule Inhibitors of Urea Transporters

    PubMed Central

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

    2015-01-01

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

  13. Thermolysis of Urea Complexes of Uranyl Nitrate

    Microsoft Academic Search

    N. N. Kostyuk

    2005-01-01

    Quantitative parameters of thermolysis of uranyl nitrate urea complexes, [UO2(NO3)2{(NH2)2CO}2], [UO2(H2O){(NH2)2CO}4](NO3)2, and [UO2(H2O){(NH2)2CO}5](NO3)2 at 175, 200, and 225C were measured. Thermolysis of [UO2(NO3)2{(NH2)2CO}2] at 200C affords the biuret complex of uranyl nitrate in a 90% yield. The urea ligands in the hydrated complexes completely\\u000a transform into biuret at 175C. Thermolysis of [UO2(H2O){(NH2)2CO}5](NO3)2 yields the biuret-cyanurate complexes of uranyl nitrate. The

  14. 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

  15. 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

  16. 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).

  17. Urea perturbation and the reversibility of nucleohistone conformation

    PubMed Central

    Chang, Catherine; Li, Hsueh Jei

    1974-01-01

    Urea effect on conformation and thermal stabilities in nucleohistone and NaCl-treated partially dehistonized nucleohistones has been studied by circular dichroism (CD) and thermal denaturation. Urea imposes a CD change at 278mm of DNA base pairs in native and NaCl-treated nucleohistones which can be decomposed into two parts: a decrease in ??278 for histone-free base pairs and an increase for histone-bound base pairs. The reduction by urea of ??220 of bound histones is approximately proportional to the increase of ??278 of histone-bound base pairs. Urea also lowers the melting temperatures of base pairs both free and bound by histones. The presence of urea indeed destroys the secondary structure of bound histones, causing changes in the conformation and thermal stabilities of histone-bound base pairs in nucleohistone. Such a urea perturbation on nucleohistone conformation is reversible. PMID:10793727

  18. 14C-urea breath test in C pylori gastritis

    Microsoft Academic Search

    E A Rauws; E A Royen; W Langenberg; J V Woensel; A A Vrij; G N Tytgat

    1989-01-01

    14C-urea breath test was used to detect Campylobacter pylori colonisation in 129 consecutive non-ulcer dyspepsia patients. Fasting patients were given 3 microCi (110 kBq) of 14C-labelled urea after a test meal. Breath samples were collected at 10 minute intervals for 90 minutes and the C-14 activity was counted on a liquid scintillation analyser. Urea derived 14CO2 appears in the exhaled

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

    E-print Network

    Brewster, Ray Q.

    1915-01-01

    3 ureas similar compounds are obtained only under jcery favor- able conditions. These products have been obtained, however, by McCrefcth (Ber. 8, 1181) by the addition od anilides to isocyanates. For instance, the acyl derivative of diphenyl urea... is produced by the action of phenyl isocyanate and acetanilide. The acyl ureas and the acyl derivatives of the isourea ethers are not extremely stable and, when heated above their melting points, decompose into anilides and cyanates or anilides...

  20. American Routes

    NSDL National Science Digital Library

    Spitzer, Nicholas R.

    In the past year or so, it would seem that many musical artists and impresarios are making quite a show of coming back to support the Big Easy in its time of need. One particular two-hour radio show has been doing just that (and other things) since 1998, American Routes. The show's website was created and is hosted by Nick Spitzer. Each show truly runs the gamut of American music, and in any given week one might find gospel, soul, roots rock and rockabilly featured during their program. Visitors can make their way through the online archive here and listen at their leisure, or learn about upcoming shows and guests. It's quite easy to see how the program might be incorporated into a musicology course, and educators may wish to consider using some of the shows in the classroom. While not all of the music from each show is available (due to copyright restrictions), the delightful interviews with people like Les Paul. Abbey Lincoln, and Rosanne Cash may be listened to in their entirety. Finally, visitors will want to view Spitzer's multimedia lecture, "Rebuilding the "Land of Dreams": Expressive Culture and New Orleans' Authentic Future".

  1. Catalytic Combustion Effects in Internal Combustion Engines

    Microsoft Academic Search

    R. L. Jones

    1997-01-01

    A review of the brief history of catalytic combustion in internal combustion (IC) engines suggests that catalytic combustion may aid in fuel ignition, but can also cause increased flame-quenching because of surface catalytic oxidation of unburned fuel in the gas boundary layer. The effect of catalytic combustion on heat transfer measurements in engines is also discussed, with the controversial Woschni

  2. 1-Methyl-3-phenyl­thio­urea

    PubMed Central

    Su, Hou-xiang

    2014-01-01

    The title compound, C8H10N2S, was prepared by reaction of methyl­amine solution, KOH and phenyl-iso­thio­cyanate in ethanol. It adopts a syn-Me and anti-Ph conformation relative to the C=S double bond. The dihedral angle between the N—C(=S)—N thio­urea and phenyl planes is 67.83?(6)°. In the crystal, the mol­ecules centrosymmetrical dimers by pairs of N(Ph)—H?S hydrogen bonds. The dimers are linked by N(Me)—H?S hydrogen bonds into layers parallel to (100). PMID:24860341

  3. Urea formaldehyde foam: a dangerous insulation

    SciTech Connect

    Keough, C.

    1980-12-01

    Insulating a home with urea formaldehyde foam can lead to severe health problems due to poisoning from formaldehyde gas. Respiratory problems, allergies, memory loss, and mental problems can result from exposure to foam insulation fumes. Research is now under way at the Chemical Industry Inst., Univ. of Washington, and other institutions to learn more about the health effects of formaldehyde foam and to develop possible remedies to these problems. Several states are either banning or controlling the use of this type of home insulation.

  4. 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

    ...A-821-801] Solid Urea from the Russian Federation: Final Results of Antidumping...antidumping duty order on solid urea from the Russian Federation. The solid urea subject to...antidumping duty order on solid urea from the Russian Federation. See Solid Urea From the...

  5. 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

    ...A-821-801] Solid Urea From the Russian Federation: Final Results of Antidumping...antidumping duty order on solid urea from the Russian Federation. The solid urea subject to...antidumping duty order on solid urea from the Russian Federation. See Solid Urea From the...

  6. Regenerative combustion device

    DOEpatents

    West, Phillip B.

    2004-03-16

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

  7. Combustion chemistry

    SciTech Connect

    Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

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

  8. 78 FR 46571 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-01

    ...A-821-801] Solid Urea From the Russian Federation: Preliminary Results of Antidumping...antidumping duty order on solid urea from the Russian Federation (Russia). The period of...Administrative Review: Solid Urea from the Russian Federation'' dated concurrently...

  9. 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 Antidumping...antidumping duty order on solid urea from the Russian Federation (Russia). For the final...1\\ See Solid Urea From the Russian Federation: Preliminary Results of...

  10. Ocean urea fertilization for carbon credits poses high ecological risks

    Microsoft Academic Search

    Patricia M. Glibert; Rhodora Azanza; Michele Burford; Ken Furuya; Eva Abal; Adnan Al-Azri; Faiza Al-Yamani; Per Andersen; Donald M. Anderson; John Beardall; G. Mine Berg; Larry Brand; Deborah Bronk; Justin Brookes; JoAnn M. Burkholder; Allan Cembella; William P. Cochlan; Jackie L. Collier; Yves Collos; Robert Diaz; Martina Doblin; Thomas Drennen; Sonya Dyhrman; Yasuwo Fukuyo; Miles Furnas; James Galloway; Edna Granéli; Dao Viet Ha; Gustaaf Hallegraeff; John Harrison; Paul J. Harrison; Cynthia A. Heil; Kirsten Heimann; Robert Howarth; Cécile Jauzein; Austin A. Kana; Todd M. Kana; Hakgyoon Kim; Raphael Kudela; Catherine Legrand; Michael Mallin; Margaret Mulholland; Shauna Murray; Judith O’Neil; Grant Pitcher; Yuzao Qi; Nancy Rabalais; Robin Raine; Sybil Seitzinger; Paulo S. Salomon; Caroline Solomon; Diane K. Stoecker; Gires Usup; Joanne Wilson; Kedong Yin; Mingjiang Zhou; Mingyuan Zhu

    2008-01-01

    The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to

  11. Polyelectrolyte-coated alginate microspheres for optical urea sensing

    Microsoft Academic Search

    M. Swati; R. Srivastava

    2009-01-01

    An optical biosensor based on urease immobilized alginate microspheres and its application for determination of urea levels in the dialysate is described. Ammonium ions liberated in urease catalyzed hydrolysis of urea lead to an increase in the pH of the medium, thereby causing the color of a pH sensitive dye to change. In this work, cresol red, immobilized in polyelectrolyte

  12. 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.

  13. Final report of the safety assessment of Urea.

    PubMed

    2005-01-01

    Although Urea is officially described as a buffering agent, humectant, and skin-conditioning agent-humectant for use in cosmetic products, there is a report stating that Urea also is used in cosmetics for its desquamating and antimicrobial action. In 2001, the Food and Drug Administration (FDA) reported that Urea was used in 239 formulations. Concentrations of use for Urea ranged from 0.01% to 10%. Urea is generally recognized as safe by FDA for the following uses: side-seam cements for food contact; an inhibitor or stabilizer in pesticide formulations and formulations applied to animals; internal sizing for paper and paperboard and surface sizing and coating of paper and paper board that contact water-in-oil dairy emulsions, low-moisture fats and oils, moist bakery products, dry solids with surface containing no free fats or oil, and dry solids with the surface of fat or oil; and to facilitate fermentation of wine. Urea is the end product of mammalian protein metabolism and the chief nitrogenous compound of urine. Urea concentrations in muscle, liver, and fetuses of rats increased after a subcutaneous injection of Urea. Urea diffused readily through the placenta and into other maternal and fetal organs. The half-life of Urea injected into rabbits was on the order of several hours, and the reutilization rate was 32.2% to 88.8%. Urea given to rats by a bolus injection or continuous infusion resulted in distribution to the following brain regions: frontal lobe, caudate nucleus, hippocampus, thalamus plus hypothalamus, pons and white matter (corpus callosum). The permeability constant after treatment with Urea of whole skin and the dermis of rabbits was 2.37 +/- 0.13 (x 10(6)) and 1.20 +/- 0.09 (x10(3)) cm/min, respectively. The absorption of Urea across normal and abraded human skin was 9.5% +/- 2.3% and 67.9% +/- 5.6%, respectively. Urea increased the skin penetration of other compounds, including hydrocortisone. No toxicity was observed for Urea at levels as high as 2000 mg/kg in acute oral studies using female rats or mice. No signs of toxicity were observed in male piglets dosed orally with up to 4 g/kg Urea for 5 days. Dogs dosed orally with 5 to 30 g/L Urea for 4 to 10 days had signs of toxicity, including weakness, anorexia, vomiting and retching, diarrhea and a decreased body temperature, which led to a deep torpor or coma. No significant microscopic changes were observed in the skin of male nude mice dermally exposed to 100% Urea for 24 h. No observable effect on fetal development was seen in rats and mice dosed orally with an aqueous solution of Urea (2000 mg/kg) on days 10 and 12 of gestation. The mean number of implants, live fetuses, percent fetal resorptions, mean fetal weight, and percent fetuses malformed were comparable to control group. A detergent containing 15% Urea was injected into pregnant ICR-JCl mice and dams and fetuses had no significant differences when compared to control animals. Urea given orally did not enhance the developmental toxicity of N-nitrosomethylurea. Female Sprague-Dawley rats injected in the uterine horn with 0.05 ml Urea on day 3 (preimplantation) or on day 7 (post implantation) exhibited no maternal mortality or morbidity; a dose-dependent reduction in embryo survival was seen with preimplantation treatment. Urea injected intra-amniotically induces mid-trimester abortions in humans. Urea was not genotoxic in several bacterial and mammalian assays; although in assays where Urea was used at a high concentration, genotoxicity was found, many in in vitro assays. Urea is commonly used in studies of DNA because it causes uncoiling of DNA molecules. Urea was not carcinogenic in Fisher 344 rats or C57B1/6 mice fed diets containing up to 4.5% Urea. Exposure of normal human skin to 60% Urea produced no significant irritation in one study, but 5% Urea was slightly irritating and 20% Urea was irritating in other reports. Burning sensations are the most frequently reported effect of Urea used alone or with other agents in treatment of diseased skin. Overall, there are few reports of sensiti

  14. 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

  15. Urea movement across erythrocyte membrane during artificial kidney treatment

    Microsoft Academic Search

    Alfred K Cheung; Michael F Alford; Marcella M Wilson; John K Leypoldt; Lee W Henderson

    1983-01-01

    Urea movement across erythrocyte membrane during artificial kidney treatment. Previous work by other investigators indicates that erythrocyte urea and creatinine in uremic whole blood leaving the hemodialyzer do not move down the concentration gradients established by loss of these solutes across the dialyzer membrane. This puzzling disequilibrium is at odds with work indicating ready movement of both solutes across the

  16. Structure and permeation mechanism of a mammalian urea transporter

    SciTech Connect

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

    2012-09-17

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

  17. Urea-prostaglandin versus hypertonic saline for instillation abortion.

    PubMed

    Binkin, N J; Schulz, K F; Grimes, D A; Cates, W

    1983-08-15

    Authorities have suggested use of a combination of hyperosmolar urea and low-dose prostaglandin F2 alpha as a second-trimester intra-amniotic abortifacient to avoid the disadvantages of hypertonic saline solution. To examine the safety and efficacy of urea-prostaglandin compared with the instillation of saline solution, we analyzed data from a prospective multicenter study conducted in the United States between 1975 and 1978. Both agents were highly effective in producing an abortion. However, urea-prostaglandin had a significantly lower rate of serious complications when compared with saline solution (1.03 versus 2.18 per 100 abortions; p less than 0.001). Urea-prostaglandin also had a significantly shorter induction-to-abortion time (14.2 versus 25.6 hours; p less than 0.001). Urea-prostaglandin, therefore, appears to be superior to hypertonic saline solution as an abortifacient. PMID:6576633

  18. 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

  19. UF foam insulation faces restrictions. [Urea formaldehyde

    SciTech Connect

    Betts, M.

    1980-04-28

    Health concerns may tighten the regulations on urea formaldehyde (UF) foam insulation after a National Academy of Sciences report recommended the lowest practical level of use inside buildings. A two-year cancer study indicates that UF poses high risks in addition to causing eye, skin, and nasal irritations. The Consumer Product Safety Commission (CPSC) is preparing a notice to warn building owners of the risks and has set a high priority for regulating formaldehyde use. A state ban in Massachusetts has prompted builders to use other materials, while manufacturers of the insulation have sued to have the ban lifted. Commercial and public buildings without good ventilating systems report occupant discomfort associated with the foam insulation. Industry standards for installation and application have been improved. (DCK)

  20. Combustion Group Group members

    E-print Network

    Wang, Wei

    , Soot § Emerging fuel sources: biofuels, renewable fuels, fuel-flexible engine and propulsion systems- physical processes § Control and mitigation of pollutant emissions § Develop combustion models Combustion Physics Combustion Modeling and Numerical Methods Pollutants, Emissions, and Soot Formation

  1. Dual stage combustion furnace

    SciTech Connect

    Goetzman, R.G.

    1984-11-27

    A dual stage combustion furnace has primary and secondary combustion chambers. The primary combustion chamber contains a solid fuel, such as wood or coal. The secondary combustion chamber is formed adjacent to and in communication with the primary combustion chamber for containing and igniting volatile combustion gases produced in the primary chamber. A plurality of hollow members, which provide a grate, extend through the primary chamber, and into the secondary chamber. Volatile gases given off in the primary combustion chamber are then ignited and burned in the secondary combustion chamber upon combination with heated air passing through the hollow grate members.

  2. Urea excretion in the hibernating Columbian ground squirrel (Spermophilus columbianus).

    PubMed

    Passmore, J C; Pfeiffer, E W; Templeton, J R

    1975-04-01

    Hibernation was induced in Columbian ground squirrels by placing them in refrigerated cages equipped with urine-collection pans. On arousal, urine and blood were collected from each animal, which was then allowed to reenter hibernation. After several days the animal was sacrificed and bladder urine and another blood sample were taken. In addition, four active non-hibernating ground squirrels were placed in a cage at room temperature with neither food or water. Urine was collected at 9 and 26 hours and blood was collected at 0 and 26 hours. Although only seven of ten hibernating squirrels had a higher blood-urea level when sacrificed than during the previous arousal, the other three had very high levels in the arousal period and probably further excreted urea before entering hibernation. When total body urea was calculated on a body weight basis, all except one animal showed a greater level of urea during hibernation than in the previous arousal. During their period of dehydration, the non-hibernating summer squirrels showed a marked decrease in blood urea. The osmotic concentration of the urine from these squirrels was due less to urea than that excreted during arousal by hibernating squirrels. Thus, it appears that urea accumulates in the blood during hibernation and is excreted in the urine during arousal. PMID:1127412

  3. 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...

  4. Urea encapsulation in modified starch matrix for nutrients retention

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  5. 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

  6. Timing driven maze routing

    Microsoft Academic Search

    Sung-Woo Hur; Ashok Jagannathan; John Lillis

    1999-01-01

    Abstract—This paper studies a natural formulation of the timing-driven maze,routing problem. A multigraph model ap- propriate for global routing applications is adopted; the model naturally captures blockages, limited routing and wire-sizing resources, layer assignment, etc. Each edge in the multigraph is annotated with resistance and capacitance values associated with the particular wiring segment. The timing-driven maze routing problem is then

  7. 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

  8. Some factors in liquid supplements affecting urea toxicity

    E-print Network

    McClain, William Ray

    1979-01-01

    -U solution died. Two out of four (50/) cattle receiving their origi- nal dose of a M-U solution (24 and 25 g level) exhibited toxicity com- pared to four out of five (80X) that received the same dose of urea in W-U solutions. Mean rumen pH, rumen and blood... phosphoric acid was added to a sub-toxic dose of urea, rumen pH and ammonia concentrations were lowered. Blood ammonia concentra- tions were not affected by phosphoric acid. Urea was found in consid- erable quantities in the rumen fluid as much as three...

  9. 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

  10. Turbulent combustion modeling

    Microsoft Academic Search

    Denis Veynante; Luc Vervisch

    2002-01-01

    Numerical simulation of flames is a growing field bringing important improvements to our understanding of combustion. The main issues and related closures of turbulent combustion modeling are reviewed. Combustion problems involve strong coupling between chemistry, transport and fluid dynamics. The basic properties of laminar flames are first presented along with the major tools developed for modeling turbulent combustion. The links

  11. for the Zone Routing Protocol

    Microsoft Academic Search

    Marc R. Pearlman; Zygmunt J. Haas

    The zone routing protocol (ZRP) is a hybrid routing protocol that proactively maintains routes within a local region of the network (which we refer to as the routing zone). Knowledge of this routing zone topology is leveraged by the ZRP to improve the efficiency of a reactive route query\\/reply mechanism. The ZRP can be configured for a particular network through

  12. 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.

  13. 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.

  14. Urea, ammonium sulfate and dicyandiamide transformations in Costa Rican soils

    Microsoft Academic Search

    K. Vilsmeier; E. Bornemisza; A. Amberger

    1987-01-01

    The transformations of urea, ammonium sulfate and dicyandiamide (DCD) were studied in an Inceptisol and three Andisols from Costa Rica, considering the influence of temperature and DCD as a nitrification inhibitor.

  15. Phloretin sensitive active urea absorption in frog skin.

    PubMed

    Svelto, M; Casavola, V; Valenti, G; Lippe, C

    1982-09-01

    This report presents evidence for urea active absorption by isolated skin of Rana esculenta. One of the supporting factors of such evidence is that at a low concentration the urea influx is five times greater than the outflux, in the absence of a chemical gradient. The transport shows a saturation kinetics with an apparent Km = 1.33 mM and is inhibited by un uncoupling agent (FCCP). 5 x 10(-4) M Phloretin, added to the external side, markedly inhibits inward urea transport, whereas it is ineffective when added to the serosal fluid. This provides evidence for a phloretin-sensitive mechanism located at the external side of the epithelium. Phloretin stimulates the sodium active transport; the possible coupling of urea and sodium movement is analysed. PMID:6983053

  16. Urea biosensors based on PVC membrane containing palmitic acid.

    PubMed

    Karaku?, Emine; Pekyardimci, Sule; Esma, Kiliç

    2005-01-01

    A new urea biosensor was prepared by immobilizing urease with four different procedures on poly(vinylchloride) (PVC) ammonium membrane electrode containing palmitic acid by using nonactine as an ammonium-ionophore. The analytical characteristics were investigated and were compared those of the biosensor prepared by using carboxylated PVC. The effect of pH, buffer concentration, temperature, urease concentration, stirring rate and enzyme immobilization procedures on the response to urea of the enzyme electrode were investigated. The linear working range and sensitivity of the biosensor were also determined. The urea biosensor prepared by using the PVC membranes containing palmitic acid showed more effective performance than those of the carboxylated PVC based biosensors. Additionally, urea assay in serum was successfully carried out by using the standard addition method. PMID:16152697

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

    EPA Science Inventory

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

  18. Hydrolyzable polyureas bearing hindered urea bonds.

    PubMed

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

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

  19. 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.

  20. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1983-01-01

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

  1. 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

  2. Managing Urea-Containing Fertilizers1 Larry G. Bundy2

    E-print Network

    Balser, Teri C.

    soil pH levels are shown in Table 1. At pH values below 7, less than 0.6 % of the N is present is an increase in soil pH in the zone where urea hydrolysis has occurred. This pH increase is important for gaseous loss of ammonia from the soil. Figure 3 illustrates the effect of urea hydrolysis on soil pH over

  3. Agronomic performance of urea briquette applicator in transplanted rice

    Microsoft Academic Search

    N. K. Savant; P. S. Ongkingco; F. D. Garcia; S. S. Dhane; R. R. Khadse; S. A. Chavan; K. S. Rao

    1992-01-01

    Field trials were conducted in the Philippines and India during 1989 and 1990 seasons to study comparative yield responses of transplanted rice (Oryza sativa L.) to pillow-shaped urea briquettes (UB) deep placed by an applicator (prototype developed by IFDC) and by hand immediately after transplanting. The applicator-placed UB consistently increased grain yields over the split-applied prilled urea, and the additional

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  5. Creatine metabolism in urea cycle defects.

    PubMed

    Boenzi, Sara; Pastore, Anna; Martinelli, Diego; Goffredo, Bianca Maria; Boiani, Arianna; Rizzo, Cristiano; Dionisi-Vici, Carlo

    2012-07-01

    Creatine (Cr) and phosphocreatine play an essential role in energy storage and transmission. Maintenance of creatine pool is provided by the diet and by de novo synthesis, which utilizes arginine, glycine and s-adenosylmethionine as substrates. Three primary Cr deficiencies exists: arginine:glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency and the defect of Cr transporter SLC6A8. Secondary Cr deficiency is characteristic of ornithine-aminotransferase deficiency, whereas non-uniform Cr abnormalities have anecdotally been reported in patients with urea cycle defects (UCDs), a disease category related to arginine metabolism in which Cr must be acquired by de novo synthesis because of low dietary intake. To evaluate the relationships between ureagenesis and Cr synthesis, we systematically measured plasma Cr in a large series of UCD patients (i.e., OTC, ASS, ASL deficiencies, HHH syndrome and lysinuric protein intolerance). Plasma Cr concentrations in UCDs followed two different trends: patients with OTC and ASS deficiencies and HHH syndrome presented a significant Cr decrease, whereas in ASL deficiency and lysinuric protein intolerance Cr levels were significantly increased (23.5 vs. 82.6 ?mol/L; p < 0.0001). This trend distribution appears to be regulated upon cellular arginine availability, highlighting its crucial role for both ureagenesis and Cr synthesis. Although decreased Cr contributes to the neurological symptoms in primary Cr deficiencies, still remains to be explored if an altered Cr metabolism may participate to CNS dysfunction also in patients with UCDs. Since arginine in most UCDs becomes a semi-essential aminoacid, measuring plasma Cr concentrations might be of help to optimize the dose of arginine substitution. PMID:22644604

  6. Optimal Node Routing

    Microsoft Academic Search

    Yossi Azar; Yoel Chaiutin

    2006-01-01

    \\u000a We study route selection for packet switching in the competitive throughput model. In contrast to previous papers which considered\\u000a competitive algorithms for packet scheduling, we consider the packet routing problem (output port selection in a node). We\\u000a model the node routing problem as follows: a node has an arbitrary number of input ports and an arbitrary number of output\\u000a queues.

  7. 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

  8. 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.

  9. 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.

  10. ChemTeacher: Combustion

    NSDL National Science Digital Library

    2012-07-23

    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.

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

    SciTech Connect

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

    2010-03-19

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

  12. 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

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

    PubMed

    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

  14. Porous Cross-Linked Polyimide-Urea Networks

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  15. 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

  16. Gasoline combustion engine

    Microsoft Academic Search

    J. M. Curran; J. D. Weaver; R. A. Weaver

    1987-01-01

    This patent describes a combination of a gasoline internal combustion engine powered by a flammable gasoline fuel and having mixing chamber means wherein the fuel is admixed with air to form a combustible mixture for burning and operation of the engine; and means for introducing the air and fuel into the mixing chamber means to provide the combustible mixture. The

  17. Combustion Group Group members

    E-print Network

    Wang, Wei

    2014 #12;Combustion Group Combustion Physics and Modeling Pollutants, Emissions, and Soot Formation · Coupling between reaction chemistry and soot-precursor · LES-modeling of large- scale industrial DeNOx facilities · Reduced-order modeling for process- control Research focus · Analysis of intrinsic combustion

  18. 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

  19. 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

  20. Catalytic hydrolysis of urea with fly ash for generation of ammonia in a batch reactor for flue gas conditioning and NOx reduction

    SciTech Connect

    Sahu, J.N.; Gangadharan, P.; Patwardhan, A.V.; Meikap, B.C. [Indian Institute of Technology, Kharagpur (India). Dept. of Chemical Engineering

    2009-01-15

    Ammonia is a highly volatile noxious material with adverse physiological effects, which become intolerable even at very low concentrations and present substantial environmental and operating hazards and risk. Yet ammonia has long been known to be used for feedstock of flue gas conditioning and NOx reduction. Urea as the source of ammonia for the production of ammonia has the obvious advantages that no ammonia shipping, handling, and storage is required. The process of this invention minimizes the risks and hazards associated with the transport, storage, and use of anhydrous and aqueous ammonia. Yet no such rapid urea conversion process is available as per requirement of high conversion in shorter time, so here we study the catalytic hydrolysis of urea for fast conversion in a batch reactor. The catalyst used in this study is fly ash, a waste material originating in great amounts in combustion processes. A number of experiments were carried out in a batch reactor at different catalytic doses, temperatures, times, and at a constant concentration of urea solution 10% by weight, and equilibrium and kinetic studies have been made.

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

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

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

  2. Route 66 University

    NSDL National Science Digital Library

    Millions of people learned about Route 66 and how it wound from Chicago to L.A. courtesy of Nat Cole, others from its namesake 1960s television series, and now interested parties can learn online about that fabled stretch of road on this Route 66 University website. Neophytes may want to begin by perusing the section dedicated to maps of the route, allowing them to visualize how it winds through Illinois, Missouri, Kansas, and other states. The site's main page also contains sections that provide electronic postcards, an events calendar, and the "Campus Rag," which provides timely information about the history of this road. The essays and articles here are a true delight, as they range from reminiscences of Route 66 from novelist Michael Lund to a 1996 interview with Roy Rogers. Another section of the site that is worth taking a look at is called "I Rememberâ?¦," and features first-hand memories of life along Route 66.

  3. Streamflow Routing: International Edition

    NSDL National Science Digital Library

    COMET

    2010-10-19

    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.

  4. Fundamentals of Gas Turbine combustion

    NASA Technical Reports Server (NTRS)

    Gerstein, M.

    1979-01-01

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

  5. 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

  6. 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.

  7. 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.

  8. 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.

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

    PubMed

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

    2015-01-21

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

  10. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory § 418.30 Applicability; description of the urea...

  11. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...418.30 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory § 418.30 Applicability; description of the urea...

  12. 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.

  13. 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.

  14. Virtual ring routing: network routing inspired by DHTs

    Microsoft Academic Search

    Matthew Caesar; Miguel Castro; Edmund B. Nightingale; Greg O'shea; Antony I. T. Rowstron

    2006-01-01

    This paper presents Virtual Ring Routing (VRR), a new network routing protocol that occupies a unique point in the design space. VRR is inspired by overlay routing algorithms in Distributed Hash Tables (DHTs) but it does not rely on an underlying network routing protocol. It is implemented directly on top of the link layer. VRR provides both traditional point-to-point network

  15. Combustion Synthesis of Magnesium Aluminate

    SciTech Connect

    Kale, M. A. [Physics Department, S.V.S.S. College of Engineering and Research, Nagpur 4411 10 (India); Joshi, C. P. [Physics Department, Ramdeobaba Engineering College, Katol Road, Nagpur 440 013 (India); Moharil, S. V. [Physics Department, RTM Nagpur University, Nagpur, 440033 (India)

    2011-10-20

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

  16. Erythrocyte permeability to urea and water: comparative study in rodents, ruminants, carnivores, humans, and birds.

    PubMed

    Liu, Lifeng; Lei, Tianluo; Bankir, Lise; Zhao, Dan; Gai, Xiaodong; Zhao, Xuejian; Yang, Baoxue

    2011-01-01

    Mammalian erythrocytes exhibit high urea permeability (P (urea)) due to UT-B expression in their cytoplasmic membrane. This high P (urea) allows fast equilibration of urea in erythrocytes during their transit in the hyperosmotic renal medulla. It also allows more urea (in addition to that in plasma) to participate in counter-current exchange between ascending and descending vasa recta, thus improving the trapping of urea in the medulla and improving urine concentrating ability. To determine if P (urea) in erythrocytes is related to diet and urine concentrating ability, we measured P (urea) in erythrocytes from 11 different mammals and 5 birds using stopped-flow light scattering. Carnivores (dog, fox, cat) exhibited high P (urea) (in x10(-5) cm/s, 5.3 ± 0.6, 3.8 ± 0.5 and 2.8 ± 0.7, respectively). In contrast, herbivores (cow, donkey, sheep) showed much lower P (urea) (0.8 ± 0.2, 0.7 ± 0.2, 1.0 ± 0.1, respectively). Erythrocyte P (urea) in human (1.1 ± 0.2), and pig (1.5 ± 0.1), the two omnivores, was intermediate. Rodents and lagomorphs (mouse, rat, rabbit) had P (urea) intermediate between carnivores and omnivores (3.3 ± 0.4, 2.5 ± 0.3 and 2.4 ± 0.3, respectively). Birds that do not excrete urea and do not express UT-B in their erythrocytes had very low values (<0.1 × 10(-5) cm/s). In contrast to P (urea), water permeability, measured simultaneously, was relatively similar in all mammals. The species differences in erythrocytes P (urea) most probably reflect adaptation to the different types of diet and resulting different needs for concentrating urea in the urine. PMID:20878327

  17. UTILIZATION BY SHEEP OF WHOLE SHELLED CORN IMPREGNATED WITH UREA, CALCIUM, POTASSIUM AND SULFUR

    Microsoft Academic Search

    L. L. Koeln; K. E. Webb; J. P. Fontenot

    2010-01-01

    Twenty-eight growing wether lambs (33.9 kg), adapted to urea for 40 d, were used in a metabo- lism study to determine if urea impregnation of corn could improve urea utilization. The following diets were compared: 1) whole shelled corn alone, 2) whole shelled corn impregnated with urea, calcium (Ca) as CaC12, potassium (K) as KC~H302, and sulfur (S) as Na2S203.SH20,

  18. Effect of oxygenated liquid additives on the urea based SNCR process.

    PubMed

    Tayyeb Javed, M; Nimmo, W; Mahmood, Asif; Irfan, Naseem

    2009-08-01

    An experimental investigation was performed to study the effect of oxygenated liquid additives, H(2)O(2), C(2)H(5)OH, C(2)H(4)(OH)(2) and C(3)H(5)(OH)(3) on NO(x) removal from flue gases by the selective non-catalytic reduction (SNCR) process using urea as a reducing agent. Experiments were performed with a 150kW pilot scale reactor in which a simulated flue gas was generated by the combustion of methane operating with 6% excess oxygen in flue gases. The desired levels of initial NO(x) (500ppm) were achieved by doping the fuel gas with ammonia. Experiments were performed throughout the temperature range of interest, i.e. from 800 to 1200 degrees C for the investigation of the effects of the process additives on the performance of aqueous urea DeNO(x). With H(2)O(2) addition a downward shift of 150 degrees C in the peak reduction temperature from 1130 to 980 degrees C was observed during the experimentation, however, the peak reduction efficiency was reduced from 81 to 63% when no additive was used. The gradual addition of C(2)H(5)OH up to a molar ratio of 2.0 further impairs the peak NO(x) reduction efficiency by reducing it to 50% but this is accompanied by a downward shift of 180 degrees C in the peak reduction temperature. Further exploration using C(2)H(4)(OH)(2) suggested that a 50% reduction could be attained for all the temperatures higher than 940 degrees C. The use of C(3)H(5)(OH)(3) as a secondary additive has a significant effect on the peak reduction efficiency that decreased to 40% the reductions were achievable at a much lower temperature of 800 degrees C showing a downward shift of 330 degrees C. PMID:19540035

  19. Evidence for Urea-Induced Hypometabolism in Isolated

    E-print Network

    Lee Jr., Richard E.

    Evidence for Urea-Induced Hypometabolism in Isolated Organs of Dormant Ectotherms TIMOTHY J. MUIR� in isolated organs of dormant ectotherms. J. Exp. Zool. 313A:28­34. When faced with unfavorable environmental conditions such as low water availability or extreme temperature, terrestrial ectotherms often enter

  20. Human Utilization of Urea Nitrogen in Low Calorie Diets

    Microsoft Academic Search

    DANIEL LINO GALLINA; ANDJOSE MIGUEL DOMÃ NGUEZ

    To evaluate the role of calorie intake on the ability of nonprotein nitrogen to substitute for part of a high biological value protein, urea was added to the low caloric milk diets of five obese women during periods of negative nitro gen balance. In five studies, negative nitrogen balance was induced by decreasing milk nitrogen intake to 3.7 g\\/day and

  1. Reduction in slow intercompartmental clearance of urea during dialysis

    SciTech Connect

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

    1985-04-01

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

  2. Urea–formaldehyde (UF) adhesive resins for wood

    Microsoft Academic Search

    M. Dunky

    1998-01-01

    Urea–formaldehyde (UF) resins are the most important type of adhesive resins for the production of wood based panels. They convince by their high reactivity and good performance in the production and by their low price, however they lack in water resistance of the hardened resin owing to the reversibility of the aminomethylene link and hence the susceptibility to hydrolysis. This

  3. New urea-absorbing polymers for artificial kidney machines

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  4. 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

  5. Prebiotic formation of polyamino acids in molten urea

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    It is important for research into the origins of life to elucidate polyamino acid formation under prebiotic conditions. Only a limited set of amino acids has been reported to polymerize thermally. In this paper we demonstrate a novel thermal polymerization mechanism in a molten urea of alkylamino acids (i.e. glycine, alanine, ?-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.

  6. 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...

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

    EPA Science Inventory

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

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

    PubMed

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

    2009-05-15

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

  9. 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.

  10. The Torus Routing Chip

    Microsoft Academic Search

    William J. Dally; Charles L. Seitz

    1986-01-01

    The torus routing chip (TRC) is a selftimed chip that performs deadlock-freecut-through routing ink-aryn-cube multiprocessor interconnection networks using a new method of deadlock avoidance calledvirtual channels. A prototype TRC with byte wide self-timed communication channels achieved on first silicon a throughput of 64 Mbits\\/s in each dimension, about an order of magnitude better performance than the communication networks used by

  11. 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.

  12. 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...

  13. 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

    ...A-821-801] Solid Urea From the Russian Federation: Preliminary Results of Antidumping...antidumping duty order on solid urea from the Russian Federation (Russia). The review covers...June 16, 2011. See Solid Urea From the Russian Federation: Extension of Time Limit...

  14. 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

    ...A-821-801] Solid Urea From the Russian Federation: Preliminary Results of Antidumping...antidumping duty order on solid urea from the Russian Federation. The review covers one producer...antidumping duty order on solid urea from the Russian Federation.\\2\\ On March 26,...

  15. 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

    ...A-821-801] Solid Urea From the Russian Federation: Antidumping Duty Administrative...antidumping duty order on solid urea from the Russian Federation (Russia). The period of...from Russia. See Solid Urea From the Russian Federation: Preliminary Results of...

  16. 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...antidumping duty orders on solid urea from the Russian Federation (Russia) and Ukraine would...orders be revoked. See Solid Urea From the Russian Federation and Ukraine: Final...

  17. A Journal of Integrative Biology Metabolic Depression Induced by Urea in Organs

    E-print Network

    Lee Jr., Richard E.

    to different seasons. The depressive effect of urea on metabolism was not consistent across organs, seasons. Metabolic depression induced by urea in organs of the wood frog, Rana sylvatica: effects of seasonA Journal of Integrative Biology Metabolic Depression Induced by Urea in Organs of the Wood Frog

  18. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Urea-formaldehyde resins in molded articles. 177.1900...Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the...

  19. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Amine-modified urea-formaldehyde polymer (generic). 721.10533...721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical...generically as amine-modified urea-formaldehyde polymer (PMN P-12-182) is...

  20. 40 CFR 721.10533 - Amine-modified urea-formaldehyde polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Amine-modified urea-formaldehyde polymer (generic). 721.10533...721.10533 Amine-modified urea-formaldehyde polymer (generic). (a) Chemical...generically as amine-modified urea-formaldehyde polymer (PMN P-12-182) is...

  1. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177.1900...Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the...

  2. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Urea-formaldehyde resins in molded articles. 177.1900...Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the...

  3. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Urea-formaldehyde resins in molded articles. 177.1900...Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the...

  4. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Urea-formaldehyde resins in molded articles. 177.1900...Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the...

  5. Evidence for urea-induced hypometabolism in isolated organs of dormant ectotherms.

    PubMed

    Muir, Timothy J; Costanzo, Jon P; Lee, Richard E

    2010-01-01

    Many organisms endure extended periods of dormancy by depressing their metabolism, which effectively prolongs the use of their endogenous energy stores. Though the mechanisms of hypometabolism are varied and incompletely understood, recent work suggests that urea accumulation in autumn and early winter contributes to reduced metabolism of hibernating wood frogs (Rana sylvatica). Urea accumulation during dormancy is a widespread phenomenon, and it has long been presumed that numerous species from diverse taxa benefit from its hypometabolic effect. To investigate the phylogenetic prevalence of urea-induced hypometabolism, we studied four species of urea accumulators from the clades Amphibia (Spea bombifrons and Ambystoma tigrinum), Reptilia (Malaclemys terrapin), and Gastropoda (Anguispira alternata), and one amphibian species (R. pipiens) that does not accumulate urea during dormancy. We measured rates of oxygen consumption (VO(2)) of excised organ samples from dormant animals in the presence or absence of physiological concentrations of urea. Three of the four urea-accumulating species had at least one organ whose VO(2) was significantly decreased by urea treatment. However, VO(2) of organs from R. pipiens, the one species tested that does not accumulate urea during dormancy, was not affected by urea treatment. Our results support the hypothesis that urea accumulation can reduce metabolic rate of dormant animals and provide a base for further investigation into the evolution of urea-induced hypometabolism. PMID:19739087

  6. 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...

  7. 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

  8. 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

  9. The effect of conditioning agents on the corrosive properties of molten urea

    Microsoft Academic Search

    D. E. Nichols; D. T. Nguyen; M. M. Norton; B. R. Parker; L. E. Daniels

    1991-01-01

    From the process case histories of the failure of several heat exchanger tube bundles, it was revealed that molten urea containing lignosulfonate as a granulation conditioning-hardening agent (Urea LS{trademark}) is corrosive to Types 304 and 316 stainless steel. The results of field and laboratory immersion corrosion tests indicated that the corrosivity of molten urea is strongly dependent on the process

  10. The effect of conditioning agents on the corrosive properties of molten urea

    Microsoft Academic Search

    D. E. Nichols; D. T. Nguyen; M. M. Norton; B. R. Parker; L. E. Daniels

    1991-01-01

    From the process case histories of the failure of several heat exchanger tube bundles, it was revealed that molten urea containing lignosulfonate as a granulation conditioning-hardening agent (Urea LS[trademark]) is corrosive to Types 304 and 316 stainless steel. The results of field and laboratory immersion corrosion tests indicated that the corrosivity of molten urea is strongly dependent on the process

  11. 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.

  12. Flow Routing on Flat Terrains

    Microsoft Academic Search

    Taylor Hamilton; Giovanna Thron

    Most current flow routing algorithms use digital elevation models (DEMs) to con- struct flow models. In order to success- fully use current techniques for flow rout- ing, they flood local minima and then find a way of routing the flow across the flat surfaces. In this paper, we examine an al- ternative method for computing flow rout- ing on these

  13. Chapters 12, 13 Routing overview

    E-print Network

    Autonomous Systems Autonomous System Numbers AS Numbers were 16 bit values before 2007 After 2007, 32-bit,on is not routed through an enemy's domains Separate IGP and EGP routing tables (hierarchical routing summary Type Name Protocol Port/ protocol number Intra-AS routing interior gateway

  14. Droplet Combustion Experiment

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha

    1998-01-01

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

  15. Ethanol sensors based on Pt-doped tin oxide nanopowders synthesised by gel-combustion

    Microsoft Academic Search

    G. Neri; A. Bonavita; G. Micali; N. Donato; F. A. Deorsola; P. Mossino; I. Amato; B. De Benedetti

    2006-01-01

    The ethanol sensing properties of SnO2 powders prepared by a gel-combustion method have been investigated. SnO2 powders with different average crystallite size, ?D?, ranging from 6 up to 100nm, were synthesized by this process starting from metallic tin as raw material and citric acid and\\/or urea as fuel substances. The average crystallite size of the synthesized powders was found to

  16. Dur3 is the major urea transporter in Candida albicans and is co-regulated with the urea amidolyase Dur1,2

    PubMed Central

    Navarathna, Dhammika H. M. L. P.; Das, Aditi; Morschhäuser, Joachim; Nickerson, Kenneth W.; Roberts, David D.

    2011-01-01

    Hemiascomycetes, including the pathogen Candida albicans, acquire nitrogen from urea using the urea amidolyase Dur1,2, whereas all other higher fungi use primarily the nickel-containing urease. Urea metabolism via Dur1,2 is important for resistance to innate host immunity in C. albicans infections. To further characterize urea metabolism in C. albicans we examined the function of seven putative urea transporters. Gene disruption established that Dur3, encoded by orf 19.781, is the predominant transporter. [14C]Urea uptake was energy-dependent and decreased approximately sevenfold in a dur3? mutant. DUR1,2 and DUR3 expression was strongly induced by urea, whereas the other putative transporter genes were induced less than twofold. Immediate induction of DUR3 by urea was independent of its metabolism via Dur1,2, but further slow induction of DUR3 required the Dur1,2 pathway. We investigated the role of the GATA transcription factors Gat1 and Gln3 in DUR1,2 and DUR3 expression. Urea induction of DUR1,2 was reduced in a gat1? mutant, strongly reduced in a gln3? mutant, and abolished in a gat1? gln3? double mutant. In contrast, DUR3 induction by urea was preserved in both single mutants but reduced in the double mutant, suggesting that additional signalling mechanisms regulate DUR3 expression. These results establish Dur3 as the major urea transporter in C. albicans and provide additional insights into the control of urea utilization by this pathogen. PMID:20884691

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

    SciTech Connect

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

    2007-01-01

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

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

    PubMed Central

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

    2014-01-01

    We present the first account of the structure–function relationships of a protein of the subfamily of urea/H+ membrane transporters of fungi and plants, using Aspergillus nidulans UreA as a study model. Based on the crystal structures of the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT) and of the Nucleobase-Cation-Symport-1 benzylhydantoin transporter from Microbacterium liquefaciens (Mhp1), we constructed a three-dimensional model of UreA which, combined with site-directed and classical random mutagenesis, led to the identification of amino acids important for UreA function. Our approach allowed us to suggest roles for these residues in the binding, recognition and translocation of urea, and in the sorting of UreA to the membrane. Residues W82, Y106, A110, T133, N275, D286, Y388, Y437 and S446, located in transmembrane helixes 2, 3, 7 and 11, were found to be involved in the binding, recognition and/or translocation of urea and the sorting of UreA to the membrane. Y106, A110, T133 and Y437 seem to play a role in substrate selectivity, while S446 is necessary for proper sorting of UreA to the membrane. Other amino acids identified by random classical mutagenesis (G99, R141, A163, G168 and P639) may be important for the basic transporter's structure, its proper folding or its correct traffic to the membrane. PMID:24966243

  19. Coal Combustion Science

    SciTech Connect

    Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

    1991-08-01

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

  20. 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.

  1. Internal Combustion Engine Flows

    Microsoft Academic Search

    Amy McCleney; Paul Puzinauskas; Kendrick Gibson

    2009-01-01

    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

  2. ASRM combustion instability studies

    NASA Technical Reports Server (NTRS)

    Strand, L. D.

    1992-01-01

    The objectives of this task were to measure and compare the combustion response characteristics of the selected propellant formulation for the Space Shuttle Advanced Solid Rocket Motor (ASRM) with those of the current Redesigned Solid Rocket Motor (RSRM) formulation. Tests were also carried out to characterize the combustion response of the selected propellant formulation for the ASRM igniter motor.

  3. Combustion of Biomass

    Microsoft Academic Search

    A. Demirbas

    2007-01-01

    In this article, combustion properties of biomass fuels in boiler power systems are briefly reviewed. Brief summaries of the basic concepts involved in the combustion of biomass fuels are presented. Biomass is an attractive renewable fuel in utility boilers. The compositions of biomass among fuel types are variable. Ash composition for the biomass is fundamentally different from ash composition for

  4. 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

  5. ANALYSIS OF HEXAMINE COMBUSTION

    Microsoft Academic Search

    James R. Merritt; Lorie Herington; S. Bart Jones; Yousry Sayed

    1991-01-01

    Hexamine was combusted under varying amounts of oxygen in a modified Parr combustion bomb. The products were collected and analyzed by gas chromatography, ion chromatography, ion-selective electrodes, and calorimetric tests. The primary products were nitrogen and carbon dioxide, with small amounts of nitrogen monoxide, nitrogen dioxide, and ammonia. Other possible products such as hydrogen cyanide, dinitrogen monoxide, and carbon monoxide

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. Combustion of Syngas in Internal Combustion Engines

    Microsoft Academic Search

    André L. Boehman; Olivier Le Corre

    2008-01-01

    The combustion of synthesis gas will play an important role in advanced power systems based on the gasification of fuel feedstocks and combined cycle power production. While the most commonly discussed option is to burn syngas in gas turbine engines, another possibility is to burn the syngas in stationary reciprocating engines. Whether spark ignited or compression ignited, syngas could serve

  8. Combustion system. [combustion system for wood wastes

    Microsoft Academic Search

    Mott

    1977-01-01

    A combustion chamber capable of being directly fueled with green bark, green sawdust and the like material is described. The chamber has a grate at the feed end disposed towards the bottom of the chamber and a reduced outlet and means for delivering particles of fuel material generally downwardly towards the grate while separating and enveloping the particles with pressurized

  9. Dual stage combustion furnace

    SciTech Connect

    Goetzman, R.G.

    1986-12-23

    This patent describes a solid fuel burning furnace having a primary combustion chamber, the primary combustion chamber having a wall and a hollow grate supporting a bed of fuel for superheating secondary air passing there through. The improvement described here comprises an afterburner which comprises an exhaust pipe which extends through the wall of the chamber entirely above the bed and defines a secondary combustion chamber entirely within the primary combustion chamber. The exhaust pipe has a throat with an open end which projects into the primary combustion chamber above the bed, a tube around the exhaust pipe defining a passage for secondary air toward the throat of the exhaust pipe, a conduit between the hollow grate and the passage for communicating superheated air toward the throat, and ignitor means in the exhaust pipe.

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

    PubMed Central

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

    2013-01-01

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

  11. 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

  12. Synthesis by the solution combustion process and magnetic properties of iron oxide (Fe 3 O 4 and ?-Fe 2 O 3 ) particles

    Microsoft Academic Search

    Juliano Toniolo; Antonio S. Takimi; Mônica J. Andrade; Renato Bonadiman; Carlos P. Bergmann

    2007-01-01

    This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea\\u000a as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different\\u000a fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe3O4) and hematite (?-Fe2O3) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by

  13. 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

  14. Rock Climbing Route Setting

    E-print Network

    Caleb Phillips; Elizabeth Bradley; Caleb Phillips; Elizabeth Bradley

    2009-01-01

    In this paper we apply chaotic systems to the task of sequence variation for the purpose of aiding humans in setting indoor rock climbing routes. This work expands on prior work where similar variations were used to assist in dance choreography and music composition. We present a formalization for transcription of rock climbing problems and a variation generator which is tuned for our domain and addresses some confounding problems, including a new approach to automatic selection of variation initial conditions. We analyze our system with a pilot study in a small university rock climbing gym as well as a large blinded study in a commercial climbing gym in cooperation with experienced climbers and expert route setters. Our results show that our system is capable of assisting a human setter in producing routes which are at least as good as, and in some cases better than, those produced traditionally. 1

  15. 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.

  16. The Triangular Trade Route

    NSDL National Science Digital Library

    Ms. Caldwell

    2009-07-07

    What is the Triangular Trade Route? After completeing this project, you should be able to explain the Triangular Trade Route in detail. These details should include the reason for trade, the countries involved, and the main goods that were traded. Getting Started: Each number will give you instructions. Follow the instructions, answering the questions on a loose leaf sheet of paper. Your answers will be collected. 1. What do you already know about trade? Answer this question in your own words. There is no right or wrong answer. 2. Have you ever traded ...

  17. Potent Urea and Carbamate Inhibitors of Soluble Epoxide Hydrolases

    Microsoft Academic Search

    Christophe Morisseau; Marvin H. Goodrow; Deanna Dowdy; Jiang Zheng; Jessica F. Greene; James R. Sanborn; Bruce D. Hammock

    1999-01-01

    The soluble epoxide hydrolase (sEH) plays a significant role in the biosynthesis of inflammation mediators as well as xenobiotic transformations. Herein, we report the discovery of substituted ureas and carbamates as potent inhibitors of sEH. Some of these selective, competitive tightbinding inhibitors with nanomolar Ki values interacted stoichiometrically with the homogenous recombinant murine and human sEHs. These inhibitors enhance cytotoxicity

  18. Rotational viscometry for the study of urea-formaldehyde resins

    Microsoft Academic Search

    Aime Suurpere; Peep Christjanson; Kadri Siimer

    Rotational viscometry as a generally recognized method for rheological measurements of non-Newtonian liquids was used for the study of commercial urea-formaldehyde resins. The measurement results were analysed using the power law function with evaluation of the consistency and flow indices. The resins were observed during their storage until alkali-promoted poly- condensation led to gelation. It is suitable to differentiate two

  19. Growth of urea crystals by physical vapor transport

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  20. Novel imidazolium chiral ionic liquids that contain a urea functionality

    Microsoft Academic Search

    Bukuo Ni; Allan D. Headley

    2006-01-01

    Nine chiral room temperature ionic liquids (RTILs), which contain a chiral moiety and a urea functionality bonded to a imidazolium ring, have been designed and synthesized. The synthesis of these ionic liquids is concise and practical due to the commercial availability of the starting materials. These novel RTILs were readily prepared from 1-(3-aminopropyl)imidazole and amino acid ester derived isocyanates. We

  1. Antimicrobial activities of N-chloramines and diazolidinyl urea.

    PubMed Central

    Llabres, C M; Ahearn, D G

    1985-01-01

    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 were 1 h for Trichophyton tonsurans, 3 h for Aspergillus niger and Fusarium moniliforme, and 6 h for Aspergillus fumigatus. PMID:3920962

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  4. Diagnosis and treatment of urea cycle disorder in Japan.

    PubMed

    Nakamura, Kimitoshi; Kido, Jun; Mitsubuchi, Hiroshi; Endo, Fumio

    2014-08-01

    Urea cycle disorder (UCD) is an inborn error of the metabolic pathway producing urea from ammonia, which occurs primarily in the liver. Decreased excretion of nitrogen in the urea cycle due to deficiency of carbamoyl phosphate synthase I (CPSI), ornithine transcarbamylase (OTC), argininosuccinate synthase (ASS), argininosuccinate lyase (ASL), and N-acetyl glutamate synthase (NAGS) causes hyperammonemia. We examined the clinical manifestations, treatment, and prognosis of 177 patients with UCD from January 1999 to March 2009 in Japan. Compared with a previous study conducted in Japan, a larger number of patients survived without mental retardation, even when the peak blood ammonia was >360 ?mol/L. In those with peak blood ammonia >360 ?mol/L, an indicator of poor prognosis, the frequency of convulsions, mental retardation, brain abnormality on magnetic resonance imaging, hemodialysis, liver transplantation, and intake of non-protein formulas was significantly higher than in those with peak blood ammonia <360 ?mol/L. In this article, we have reported the current state of UCD to evaluate prognosis and its relationship with peak blood ammonia and hemodialysis. PMID:25039902

  5. Differential stability of the bovine prion protein upon urea unfolding

    PubMed Central

    Julien, Olivier; Chatterjee, Subhrangsu; Thiessen, Angela; Graether, Steffen P; Sykes, Brian D

    2009-01-01

    Prion diseases, or transmissible spongiform encephalopathies, are a group of infectious neurological diseases associated with the structural conversion of an endogenous protein (PrP) in the central nervous system. There are two major forms of this protein: the native and noninfectious cellular form, PrPC; and the misfolded, infectious, and proteinase K-resistant form, PrPSc. The C-terminal domain of PrPC is mainly ?-helical in structure, whereas PrPSc in known to aggregate into an assembly of ?-sheets, forming amyloid fibrils. To identify the regions of PrPC potentially involved in the initial steps of the conversion to the infectious conformation, we have used high-resolution NMR spectroscopy to characterize the stability and structure of bovine recombinant PrPC (residues 121 to 230) during unfolding with the denaturant urea. Analysis of the 800 MHz 1H NMR spectra reveals region-specific information about the structural changes occurring upon unfolding. Our data suggest that the dissociation of the native ?-sheet of PrPC is a primary step in the urea-induced unfolding process, while strong hydrophobic interactions between helices ?1 and ?3, and between ?2 and ?3, stabilize these regions even at very high concentrations of urea. PMID:19693935

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

    NASA Astrophysics Data System (ADS)

    Kisiel, Zbigniew; Thomas, Jessica; Medvedev, Ivan

    2014-06-01

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

  7. 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.

  8. Japan's microgravity combustion science program

    NASA Technical Reports Server (NTRS)

    Sato, Junichi

    1993-01-01

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

  9. Route guidance information for elderly passengers: route naming methods

    E-print Network

    Higgins, Laura Lynne

    1993-01-01

    ROUTE GUIDANCE INFORMATION FOR ELDERLY PASSENGERS: ROUTE NAMING METHODS A Thesis by LAURA LYNNE HIGGINS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE December 1993 Major Subject: Industrial Engineering ROUTE GUIDANCE INFORMATION FOR ELDERLY BUS PASSENGERS: ROUTE NAMING METHODS A Thesis by LAURA LYNNE HIGGINS Submitted to Texas A&M University in partial fulfillment of the requirements...

  10. Route oscillations in I-BGP with route reflection

    Microsoft Academic Search

    Anindya Basu; Chih-hao Luke Ong; April Rasala; F. Bruce Shepherd; Gordon T. Wilfong

    2002-01-01

    We study the route oscillation problem [16, 19] in the Internal Border Gateway Protocol (I-BGP)[18] when route reflection is used. We propose a formal model of I-BGP and use it to show that even deciding whether an I-BGP configuration with route reflection can converge is an NP-Complete problem. We then propose a modification to I-BGP and show that route reflection

  11. Route repetition and route retracing: effects of cognitive aging.

    PubMed

    Wiener, Jan M; Kmecova, Hana; de Condappa, Olivier

    2012-01-01

    Retracing a recently traveled route is a frequent navigation task when learning novel routes or exploring unfamiliar environments. In the present study we utilized virtual environments technology to investigate age-related differences in repeating and retracing a learned route. In the training phase of the experiment participants were guided along a route consisting of multiple intersections each featuring one unique landmark. In the subsequent test phase, they were guided along short sections of the route and asked to indicate overall travel direction (repetition or retracing), the direction required to continue along the route, and the next landmark they would encounter. Results demonstrate age-related deficits in all three tasks. More specifically, in contrast to younger participants, the older participants had greater problems during route retracing than during route repetition. While route repetition can be solved with egocentric response or route strategies, successfully retracing a route requires allocentric processing. The age-related deficits in route retracing are discussed in the context of impaired allocentric processing and shift from allocentric to egocentric navigation strategies as a consequence of age-related hippocampal degeneration. PMID:22661944

  12. Protocolli di Routing esterno

    E-print Network

    Mellia, Marco

    1 Protocolli di Routing esterno EGP BGP EGP: Exterior Gateway Protocol · Storicamente, il primo" ARPAnet) · EGP va in crisi con l'introduzione di dorsali e cammini multipli tra due host e per questo motivo è stato sostituito con BGP Funzioni di EGP · Neighbor Acquisition: un router richiede ad un

  13. Protocolli di Routing esterno

    E-print Network

    Mellia, Marco

    1 Protocolli di Routing esterno EGP BGP EGP: Exterior Gateway Protocol . Storicamente, il primo'' ARPAnet) . EGP va in crisi con l'introduzione di dorsali e cammini multipli tra due host e per questo motivo è stato sostituito con BGP Funzioni di EGP . Neighbor Acquisition: un router richiede ad un

  14. FAST ROUTE to Cloudification

    Microsoft Academic Search

    Tony Shan; Winnie W. Hua

    2010-01-01

    This paper presents a methodical approach to effectively designing real-world Cloud solutions that facilitate migration to a paradigm of a robust and industrialized Cloud ecosystem. To systemize the development of Cloud services and a federated fabric, a holistic framework is constructed, composed of Foundation, Applicability, Strategization, Transformation roadmapping, Reference models, Operationalization, Unification, Tooling, and Ecosystem (FAST ROUTE). This comprehensive method

  15. 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.

  16. 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

  17. Interactions of urea with native and unfolded proteins: a volumetric study.

    PubMed

    Son, Ikbae; Shek, Yuen Lai; Tikhomirova, Anna; Baltasar, Eduardo Hidalgo; Chalikian, Tigran V

    2014-11-26

    We describe a statistical thermodynamic approach to analyzing urea-dependent volumetric properties of proteins. We use this approach to analyze our urea-dependent data on the partial molar volume and adiabatic compressibility of lysozyme, apocytochrome c, ribonuclease A, and ?-chymotrypsinogen A. The analysis produces the thermodynamic properties of elementary urea-protein association reactions while also yielding estimates of the effective solvent-accessible surface areas of the native and unfolded protein states. Lysozyme and apocytochrome c do not undergo urea-induced transitions. The former remains folded, while the latter is unfolded between 0 and 8 M urea. In contrast, ribonuclease A and ?-chymotrypsinogen A exhibit urea-induced unfolding transitions. Thus, our data permit us to characterize urea-protein interactions in both the native and unfolded states. We interpreted the urea-dependent volumetric properties of the proteins in terms of the equilibrium constant, k, and changes in volume, ?V0, and compressibility, ?KT0, for a reaction in which urea binds to a protein with a concomitant release of two waters of hydration to the bulk. Comparison of the values of k, ?V0, and ?KT0 with the similar data obtained on small molecules mimicking protein groups reveals lack of cooperative effects involved in urea-protein interactions. In general, the volumetric approach, while providing a unique characterization of cosolvent-protein interactions, offers a practical way for evaluating the effective solvent accessible surface area of biologically significant fully or partially unfolded polypeptides. PMID:25365737

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

    SciTech Connect

    Barton, G; Lonsdale, B

    2003-08-24

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

  19. Routes to Novel Azo compounds 

    E-print Network

    Iannarelli, Paul M.

    Routes to novel heterocyclic azo compounds and components of use as potential inkjet dyes were investigated. A new route to fluorenones from biphenyl acid chlorides using FVP (Flash Vacuum Pyrolysis) has been discovered. ...

  20. Studies in premixed combustion

    SciTech Connect

    Sivashinsky, G.I.

    1992-01-01

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

  1. Combustion Technology Outreach

    NASA Technical Reports Server (NTRS)

    1995-01-01

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

  2. External combustion engine having a combustion expansion chamber

    Microsoft Academic Search

    Anthony W. Duva

    1993-01-01

    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

  3. Consider Compressed Combustion

    E-print Network

    Crowther, R. H.

    1982-01-01

    configuration. In Table I, combustion gases are directed across tube banks in a manner that is roughly comparable to flue gas flow in a conventional heater. There are actually two important concepts under test in these preliminary design estimates.... The first is emphasis on convective heat transfer as opposed to radiant heat transfer in conventional heaters, even when combustion gases flow so slowly that no significant compression is needed. The convective ver sus radiant aspect of compressed...

  4. Internal combustion engine

    Microsoft Academic Search

    Bernauer

    1980-01-01

    An internal combustion engine is described that has walls delimiting the working space or spaces of the internal combustion engine, in which a hydrogen-impervious, encapsulated metal hydride storage device is provided which is in heat-conducting contact with these walls; the interior of the encapsulation is adapted to be selectively connected to a source of hydrogen and\\/or to a separate further

  5. 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.

  6. Timing-driven maze routing

    Microsoft Academic Search

    Sung-woo Hur; Ashok Jagannathan; John Lillis

    2000-01-01

    Abstract—This paper studies a natural formulation of the timing-driven maze,routing problem. A multigraph model appropriate for global routing applications is adopted; the model naturally captures blockages, limited routing and wire-sizing resources, layer assignment, etc. Each edge in the multigraph is annotated with resistance and capacitance values associated with the particular wiring segment. The timing-driven maze routing problem is then to

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Cognitively Ergonomic Route Alexander Klippel

    E-print Network

    Klippel, Alexander

    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

  12. Geographic routing without location information

    Microsoft Academic Search

    Ananth Rao; Sylvia Ratnasamy; Christos Papadimitriou; Scott Shenker; Ion Stoica

    2003-01-01

    For many years, scalable routing for wireless communication systems was a compelling but elusive goal. Recently, several routing algorithms that exploit geographic information (e.g. GPSR) have been proposed to achieve this goal. These algorithms refer to nodes by their location, not address, and use those coordinates to route greedily, when possible, towards the destination. However, there are many situations where

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

    DOEpatents

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

    2004-02-17

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

  14. 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.

  15. 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

  16. 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.

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

    PubMed

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

    2015-04-01

    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

  18. Internal combustion engine

    SciTech Connect

    Williams, G.J.

    1986-06-03

    A variable power internal combustion engine is described which consists of: a separate air compressor for receiving and compressing a flow of air to a given pressure, the compressor having an inlet valve introducing a flow of air into the compressor and an outlet valve for exhausting compressed air out of the compressor into a compressed air storage means, at least one expander having a cylinder, a cylinder head closing an end of the cylinder, a piston reciprocally mounted in the cylinder for movement away from the cylinder head in a power stroke from an initial position defining a combustion chamber within the cylinder between the cylinder head and the piston, the compressed air storage means receiving the pressurized flow of air from the compressor and being of a volume adequate to provide compressed air in the combustion chamber essentially at the given pressure essentially over the power output of the engine, means for introducing an amount of combustible fuel in the compressed charge to be present with compressed air in the combustion chamber and providing combustion of the amount of fuel in the cylinder with the inlet and exhaust valves closed, cam shaft means in contact with the piston for absorbing and storing the energy of the power stroke of the piston and controlling movement of the piston within the cylinder during the exhaust stroke; the means for varying the volume of the combustion chamber being controlled in accordance with power requirements to provide variable power output and improved efficiency of the engine at power outputs reduced relative to a given design power output of the engine by providing a variable expansion ratio of a minimum of at least about 30 to 1 at the given design power output and higher with reduced power output.

  19. 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

  20. Speciation of hydroxyl-Al polymers formed through simultaneous hydrolysis of aluminum salts and urea

    Microsoft Academic Search

    Chenghong Feng; Qunshan Wei; Shuifeng Wang; Baoyou Shi; Hongxiao Tang

    2007-01-01

    Urea hydrolysis has always been used to prepare alumina gels and little attention has been paid to the reactive polymeric Al species that is formed before alumina sol–gels occur. Based on the hydrolysis process of aluminum in urea solution at 90°C, speciation and transformation of the reactive hydroxyl-Al polymers obtained by urea hydrolysis was investigated with Ferron assay, solution-state and

  1. Imprecision of the hemodialysis dose when measured directly from urea removal

    Microsoft Academic Search

    THOMAS A. DEPNER; TOM GREENE; FRANK A. GOTCH; JOHN T. DAUGIRDAS; PRAKASH R. KESHAVIAH; ROBERT A. STAR

    1999-01-01

    Imprecision of the hemodialysis dose when measured directly from urea removal.BackgroundThe postdialysis blood urea nitrogen (BUN; Ct) is a pivotal parameter for assessing hemodialysis adequacy by conventional blood-side methods, but Ct is relatively unstable because of hemodialysis-induced disequilibrium. The uncertainty associated with this method is potentially reduced or eliminated by measuring urea removed on the dialysate side, a more direct

  2. Effect of cycloheximide on urea facilitated transport through toad gallbladder epithelium.

    PubMed

    Casavola, V; Curci, S; Lippe, C

    1980-03-01

    Transepithelial urea outfluxes across toad gallbladder were determined before and after the addition of cycloheximide. The drug inhibits the movement of urea but has no effect on thiourea and antipyrine outfluxes. The inhibition of amide transport is time dependent as also shown in counterflow experiments. These results are consistent with the hypothesis that cycloheximide inhibits the synthesis of membrane proteic sites involved in urea mediated transport. PMID:6770342

  3. Role of UTB Urea Transporters in the Urine Concentrating Mechanism of the Rat Kidney

    Microsoft Academic Search

    Anita T. Layton

    2007-01-01

    A mathematical model of the renal medulla of the rat kidney was used to investigate urine concentrating mechanism function\\u000a in animals lacking the UTB urea transporter. The UTB transporter is believed to mediate countercurrent urea exchange between\\u000a descending vasa recta (DVR) and ascending vasa recta (AVR) by facilitating urea transport across DVR endothelia. The model\\u000a represents the outer medulla (OM)

  4. Design, synthesis and evaluation of non-urea inhibitors of soluble epoxide hydrolase

    PubMed Central

    Pecic, Stevan; Deng, Shi-Xian; Morisseau, Christophe; Hammock, Bruce D.; Landry, Donald W.

    2012-01-01

    Inhibition of soluble epoxide hydrolase (sEH) has been proposed as a new pharmaceutical approach for treating hypertension and vascular inflammation. The most potent sEH inhibitors reported in literature to date are urea derivatives. However, these compounds have limited pharmacokinetic profiles. We investigated non-urea amide derivatives as sEH inhibitors and identified a potent human sEH inhibitor 14–34 having potency comparable to urea-based inhibitors. PMID:22079754

  5. Rituximab by subcutaneous route.

    PubMed

    Solal-Celigny, Philippe

    2015-04-01

    Rituximab has become a keystone of the treatment of B-cell lymphoproliferation. The standard administration route is intravenous infusion with risks of infusion-related reactions. In order to make administration easier, increase convenience for the patient and improve cost effectiveness, a subcutaneous (sc.) form has recently been developed. Early phase clinical studies in patients with follicular lymphoma have shown that a fixed dose of 1400 mg by sc. route yielded at least non-inferior pharmacokinetics that are at least as good as those of intravenous rituximab, as measured by Ctrough levels. The safety profile was also comparable. Preliminary analyses of clinical efficacy showed at least non-inferior response rates. Although additional information is required, these results suggest that sc. rituximab may become a useful option for treating patients with B-cell non-Hodgkin's lymphoma. PMID:25749209

  6. Mixing-controlled supersonic combustion.

    NASA Technical Reports Server (NTRS)

    Ferri, A.

    1973-01-01

    The technology of supersonic combustion and its practical significance for hypersonic flight are reviewed. It is shown that this technology makes possible a good qualitative and quantitative understanding of the physical phenomena related to the process of supersonic combustion. Some of the more important, summarized aspects of this technology include the physical description of the supersonic combustion flame, the chemical reaction rates and the diffusion process involved, the interaction between combustion and fluid dynamics, and the mathematical methods of supersonic combustion analysis.

  7. Southern States' Routing Agency Report

    SciTech Connect

    Not Available

    1988-02-01

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

  8. 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. Metabolic control of urea catabolism in Chlamydomonas reinhardi and Chlorella pyrenoidosa.

    PubMed Central

    Hodson, R C; Williams, S K; Davidson, W R

    1975-01-01

    In the unicellular green alga Chlamydomonas reinhardi (strain y-1), synthesis of the enzymes required for urea hydrolysis is under substrate induction control by urea and under end product repression control by ammonia. Hydrolysis of urea if effected by the sequential action of the discrete enzymes urea carboxylase and allophanate lyase, collectively called urea amidolyase. The carboxylase converts urea to allophanate in a reaction requiring biotin, adenosine 5'-triphosphate, and Mg2+. The lyase hydrolzyes allophanate to ammonium ions and bicarbonate. Neither activity is present in more than trace amounts when cultures are grown with ammonia or urea plus ammonia, or when they are starved for nitrogen for 8 h. Urea in the absence of ammonia induces both activities 10 to 100 times the basal levels. Addition of ammonia to an induced culture causes complete cessation of carboxylase accumulation and an 80% depression of lyase accumulation. Ammonia does not reduce urea uptake by repressed cells, so it does not prevent induction by the mechanism of inducer exclusion. The unicellular green alga Chlorella pyrenoidosa (strain 3 Emerson) also has discrete carboxylase and lyase enzymes, but only the carboxylase exhibits metabolic control. PMID:1116994

  10. 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.

  11. 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.

  12. Microgravity Combustion Diagnostics Workshop

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  13. Functional materials from self-assembled bis-urea macrocycles.

    PubMed

    Shimizu, Linda S; Salpage, Sahan R; Korous, Arthur A

    2014-07-15

    CONSPECTUS: This Account highlights the work from our laboratories on bis-urea macrocycles constructed from two C-shaped spacers and two urea groups. These simple molecular units assembled with high fidelity into columnar structures guided by the three-centered urea hydrogen bonding motif and aryl stacking interactions. Individual columns are aligned and closely packed together to afford functional and homogeneous microporous crystals. This approach allows for precise and rational control over the dimensions of the columnar structure simply by changing the small molecular unit. When the macrocyclic unit lacks a cavity, columnar assembly gives strong pillars. Strong pillars with external functional groups such as basic lone pairs can expand like clays to accept guests between the pillars. Macrocycles that contain sizable interior cavities assemble into porous molecular crystals with aligned, well-defined columnar pores that are accessible to gases and guests. Herein, we examine the optimal design of the macrocyclic unit that leads to columnar assembly in high fidelity and probe the feasibility of incorporating a second functional group within the macrocycles. The porous molecular crystals prepared through the self-assembly of bis-urea macrocycles display surface areas similar to zeolites but lower than MOFs. Their simple one-dimensional channels are well-suited for studying binding, investigating transport, diffusion and exchange, and monitoring the effects of encapsulation on reaction mechanism and product distribution. Guests that complement the size, shape, and polarity of the channels can be absorbed into these porous crystals with repeatable stoichiometry to form solid host-guest complexes. Heating or extraction with an organic solvent enables desorption or removal of the guest and subsequent recovery of the solid host. Further, these porous crystals can be used as containers for the selective [2 + 2] cycloadditions of small enones such as 2-cyclohexenone or 3-methyl-cyclopentenone, while larger hosts bind and facilitate the photodimerization of coumarin. When the host framework incorporates benzophenone, a triplet sensitizer, UV-irradiation in the presence of oxygen efficiently generates singlet oxygen. Complexes of this host were employed to influence the selectivity of photooxidations of 2-methyl-2-butene and cumene with singlet oxygen. Small systematic changes in the channel and bound reactants should enable systematic evaluation of the effects of channel dimensions, guest dimensions, and channel-guest interactions on the processes of absorption, diffusion, and reaction of guests within these nanochannels. Such studies could help in the development of new materials for separations, gas storage, and catalysis. PMID:24784767

  14. 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.

  15. 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.

  16. 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.

  17. 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-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. (199KB JPEG, 1311 x 1477 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-0300165.html.

  18. 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.

  19. Fluidized-bed combustion

    SciTech Connect

    Botros, P E

    1990-04-01

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

  20. Thermal ignition combustion system

    DOEpatents

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

    1988-04-19

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

  1. 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.

  2. Studies in combustion dynamics

    SciTech Connect

    Koszykowski, M.L. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

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

  3. New Routing Metrics for ADHOC Network Routing Protocols

    NASA Astrophysics Data System (ADS)

    Reddy, P. C.

    2014-12-01

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

  4. 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.

  5. Urea transport mediated by aquaporin water channel proteins.

    PubMed

    Li, Chunling; Wang, Weidong

    2014-01-01

    Aquaporins (AQPs) are a family of membrane water channels that basically function as regulators of intracellular and intercellular water flow. To date, thirteen aquaporins have been characterized. They are distributed wildly in specific cell types in multiple organs and tissues. Each AQP channel consists of six membrane-spanning alpha-helices that have a central water-transporting pore. Four AQP monomers assemble to form tetramers, which are the functional units in the membrane. Some of AQPs also transport urea, glycerol, ammonia, hydrogen peroxide, and gas molecules. AQP-mediated osmotic water transport across epithelial plasma membranes facilitates transcellular fluid transport and thus water reabsorption. AQP-mediated urea and glycerol transport is involved in energy metabolism and epidermal hydration. AQP-mediated CO2 and NH3 transport across membrane maintains intracellular acid-base homeostasis. AQPs are also involved in the pathophysiology of a wide range of human diseases (including water disbalance in kidney and brain, neuroinflammatory disease, obesity, and cancer). Further work is required to determine whether aquaporins are viable therapeutic targets or reliable diagnostic and prognostic biomarkers. PMID:25298348

  6. Kinetic investigation of erucamide synthesis using fatty acid and urea.

    PubMed

    Awasthi, Neeraj Praphulla; Upadhayay, Santosh K; Singh, R P

    2008-01-01

    Fatty acid amides like erucamide are mainly used for lubrication and as slip agent to decrease friction in polymer and plastic industry. Erucamide is normally synthesized by ammonolysis of triglycerides or fatty acids at 200 degrees C and at high pressure (345-690 kPa.). However using urea in place of ammonia the economic synthesis of erucamide is possible at atmospheric pressure at approx 190 degrees C. In present investigation, the kinetics of synthesis of erucamide by ammonolysis of erucic acid has been investigated. The optimum conditions for the synthesis of erucamide have also been determined. 1:4 molar ratio of erucic acid to urea, 190 degrees C temperature and catalyst [P2O5 with (NH4)2H PO4, {(1:1) w/w }] concentration 3% (by wt. of erucic acid) were the optimum condition for synthesis of erucamide from erucic acid and can obtain a maximum yield of 92% of pure erucamide. Some other catalysts as titanium-iso -propoxide, phosphorus pent oxide were also tried but these catalysts were not economical. PMID:18685229

  7. Platelet adhesion to polyurethane urea under pulsatile flow conditions.

    PubMed

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

    2014-12-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s(-1). The aim of the current work is to determine the properties of platelet adhesion to the polyurethane urea surface as a function of time-varying shear exposure. A rotating disk system was used to study the influence of steady and pulsatile flow conditions (e.g., cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments were conducted with the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk was rotated in platelet-rich bovine plasma for 2 h, with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow was found to decay exponentially with increasing shear rate. Adhesion levels were found to depend upon peak platelet flux and shear rate, regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

  8. Dichloridobis(N,N?-diethyl­thio­urea-?S)mercury(II)

    PubMed Central

    Mufakkar, Muhammad; Tahir, M. Nawaz; Sadaf, Haseeba; Ahmad, Saeed; Waheed, Abdul

    2010-01-01

    There are two mol­ecules in the asymmetric unit of the title compound, [HgCl2(C5H12N2S)2]. In both mol­ecules, the N,N?-diethyl­thio­urea ligands exhibit a cis,trans geometry around their C—N amide bonds. The shapes of the mol­ecules are, to a large extent, determined by intra­molecular N—H?Cl hydrogen bonds formed by the N—H groups from the cis amide groups. In one mol­ecule, these groups are involved in three-center hydrogen bonds involving both chloride ligands, whereas in the other mol­ecule only one Cl ligand takes part in intra­molecular hydrogen bonding. The coordination around the Hg atom is distorted tetra­hedral with an S2Cl2 donor set. Inter­molecular hydrogen bonds between N—H groups from the trans amide units of the thio­amide ligands and the chloride ligands connect the mol­ecules into a polymeric chain extending along the c axis. One of the ethyl groups of the N,N?-diethyl­thio­urea ligands is disordered over two positions in one of the mol­ecules, with an occupancy of 0.654?(17) for the major component. PMID:21588084

  9. Dichloridobis(N,N'-diethyl-thio-urea-?S)mercury(II).

    PubMed

    Mufakkar, Muhammad; Tahir, M Nawaz; Sadaf, Haseeba; Ahmad, Saeed; Waheed, Abdul

    2010-01-01

    There are two mol-ecules in the asymmetric unit of the title compound, [HgCl(2)(C(5)H(12)N(2)S)(2)]. In both mol-ecules, the N,N'-diethyl-thio-urea ligands exhibit a cis,trans geometry around their C-N amide bonds. The shapes of the mol-ecules are, to a large extent, determined by intra-molecular N-H?Cl hydrogen bonds formed by the N-H groups from the cis amide groups. In one mol-ecule, these groups are involved in three-center hydrogen bonds involving both chloride ligands, whereas in the other mol-ecule only one Cl ligand takes part in intra-molecular hydrogen bonding. The coordination around the Hg atom is distorted tetra-hedral with an S(2)Cl(2) donor set. Inter-molecular hydrogen bonds between N-H groups from the trans amide units of the thio-amide ligands and the chloride ligands connect the mol-ecules into a polymeric chain extending along the c axis. One of the ethyl groups of the N,N'-diethyl-thio-urea ligands is disordered over two positions in one of the mol-ecules, with an occupancy of 0.654?(17) for the major component. PMID:21588084

  10. Serratia ureilytica sp. nov., a novel urea-utilizing species.

    PubMed

    Bhadra, Bhaskar; Roy, Pradosh; Chakraborty, Ranadhir

    2005-09-01

    A Gram-negative, rod-shaped, urea-dissolving and non-spore-forming bacterium, designated strain NiVa 51(T), was isolated from water of the River Torsa in Hasimara, Jalpaiguri district, West Bengal, India. On the basis of 16S rRNA gene sequence similarity, strain NiVa 51(T) was shown to belong to the gamma-Proteobacteria and to be related to Serratia marcescens subsp. sakuensis (98.35%) and S. marcescens subsp. marcescens (98.30%); however, strain NiVa 51(T) exhibited only 43.7% similarity to S. marcescens by DNA-DNA hybridization. The G+C content of the genomic DNA of the isolate was 60 mol%. Both biochemical characteristics and fatty acid analysis data supported the affiliation of strain NiVa 51(T) to the genus Serratia. Furthermore, strain NiVa 51(T) was found to utilize urea as nitrogen source. The results of DNA-DNA hybridization as well as physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain NiVa 51(T) from recognized Serratia species. Strain NiVa 51(T) therefore represents a novel species, for which the name Serratia ureilytica sp. nov. is proposed, with type strain NiVa 51(T) (=LMG 22860(T)=CCUG 50595(T)). PMID:16166724

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

    PubMed

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

    2012-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Joshi, Abhijeet; Chaudhari, Rashmi; Srivastava, Rohit

    2014-04-01

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

  14. 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

  15. Application of comprehensive combustion modeling to practical combustion systems

    SciTech Connect

    Hill, S.C.; Smoot, L.D. [Brigham Young Univ., Salt Lake City, UT (United States). Advanced Combustion Engineering Research Center

    1996-12-31

    Comprehensive combustion modeling has become an indispensable tool for the design and optimization of practical combustion systems. Comprehensive combustion modeling involves the numerical solution of partial differential equations which describe the physical processes occurring in combustion systems. This paper discusses the information required to create such a model of practical combustion systems and the computational and personnel resources required to apply the model. The procedures to create the model, solve the problem and analyze the results are also described. The information which can be obtained from comprehensive combustion simulations is discussed, and typical applications and some limitations of these simulations are also described. The paper also presents the results of several simulations of practical combustion systems compared with experimental data to illustrate potential applications of combustion modeling.

  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. Combustible structural composites and methods of forming combustible structural composites

    DOEpatents

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

    2013-04-02

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

  18. 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.

  19. Project Sponsors: UCI Combustion

    E-print Network

    Mease, Kenneth D.

    mechanisms that lead the formation and emission of NOx in specific applications. · Test the effect of fuel it represents. In a CRN, the flow and flame patterns in the combustion volume are divided into zones represented those reaction structures. For that reason, the flame profiles, volume of the reactors, residence time

  20. Combustion control with flames

    Microsoft Academic Search

    Isenberg

    1984-01-01

    A combustion control process and apparatus provides a reference flame of known or constant composition which is in ionic communication with the main flame which is to be controlled. Both the reference and main flames are supported by electrically insulated burner nozzles and the flames are in mutual electrical communication through ionized gases. The potential difference is measured between the

  1. COMBUSTION OF HAZARDOUS WASTE

    EPA Science Inventory

    Of the 260 MMT of hazardous waste generated annually in the United States, 1.70 MMT are disposed of in incinerators, 3.50 MMT are burned in boilers and 0.35 MMT are burned in other industrial processes. The paper is an overview of the technologies that can be used to combust haza...

  2. Spray combustion stability project

    NASA Technical Reports Server (NTRS)

    Jeng, San-Mou; Litchford, Ron J.

    1992-01-01

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

  3. Turbulent Combustion Luc Vervisch

    E-print Network

    Kern, Michel

    ) the mesh size stays very small... For a 1 cm3 simulation depending on the fuel: Jet-flame DNS: 3 cm3)(DNS):: Synthetic problem Laboratory flame at lower Re Real jet-flame Chemistry: · Single-step · Reduced · Tabulated;19 "Perfect" combustion modes: Fuel + Oxidizer () Products Engines, gas turbines... Laboratory experiment

  4. Droplet Combustion Experiment Operates

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Fuel ignites and burns in the Droplet Combustion Experiment (DCE) on STS-94 on July 12, 1997, MET:11/07:00 (approximate). DCE used various fuels -- in drops ranging from 1 mm (0.04 inches) to 5 mm (0.2 inches) -- and mixtures of oxidizers and inert gases to learn more about the physics of combustion in the simplest burning configuration, a sphere. The 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 experiment elapsed time is shown at the bottom of the composite image. 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. (119KB JPEG, 658 x 982 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-0300171.html.

  5. Combustion Fundamentals Research

    NASA Technical Reports Server (NTRS)

    1984-01-01

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

  6. COMBUSTION OF CHLORINATED HYDROCARBONS

    Microsoft Academic Search

    A. K. GUPTA

    1986-01-01

    Thermal destruction by incineration of chlorinated hydrocarbons (CHC) is an attractive method for the volume reduction and ultimate disposal of wastes. The present paper provides further insight into the fundamental properties of CHC for understanding the mechanism, rates of oxidation and other combustion characteristics, e.g., flame stability, ignition delay, sooting characteristics. CHC compounds require longer residence time at elevated temperatures

  7. 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

  8. 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

  9. Fragments, Combustion and Earthquakes

    E-print Network

    Oscar Sotolongo-Costa; Antonio Posadas

    2005-03-16

    This paper is devoted to show the advantages of introducing a geometric viewpoint and a non extensive formulation in the description of apparently unrelated phenomena: combustion and earthquakes. Here, it is shown how the introduction of a fragmentation analysis based on that formulation leads to find a common point for description of these phenomena

  10. 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

  11. 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.

  12. 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.

  13. Solid Surface Combustion Experiment

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Solid Surface Combustion Experiment (SSCE), designed to supply information on flame spread over solid fuel surfaces in the reduced-gravity environment of space, is pictured during Day 4 operations. The middeck experiment measured the rate of spreading, the solid-phase temperature, and the gas-phase temperature of flames spreading over rectangular fuel beds.

  14. Route 66 Oral Histories

    NSDL National Science Digital Library

    The folks at Missouri State University have interviewed a range of business owners along the celebrated Route 66 to tell the amazing story of what life was like living along this American landmark. Visitors can read through interviews with a variety of people, including the long-time owner of the Boots Motel in Carthage, Missouri and Sheldon and Julia Chaney, owner of a popular gas station. It's the type of popular oral history that makes for excellent reading and contemplation. They plan on adding more material in the future, so curious visitors would do well to make return visits to see what's added next.

  15. Tetra­aqua­bis­(thio­urea-?S)cadmium(II) triaqua­tris(thio­urea-?S)cadmium(II) disulfate

    PubMed Central

    Parvez, Masood; Jalilehvand, Farideh; Amini, Zahra

    2012-01-01

    The title compound, [Cd(CH4N2S)2(H2O)4][Cd(CH4N2S)3(H2O)3](SO4)2, contains two mol­ecules of each of the Cd complexes and four sulfate ions in the asymmetric unit: all the Cd atoms exhibit distorted octa­hedral geometries. The Cd—S and Cd—O bond lengths around the Cd atoms in the bis­(thio­urea) cations are in the ranges 2.580?(4)–2.599?(4) and 2.323?(8)–2.421?(9)?Å, respectively, and the S atoms are in a cis orientation. In the tris­(thio­urea) cations, the corresponding bond lengths around the Cd atoms are slightly longer and are in the ranges 2.559?(4)–2.706?(3) and 2.303?(7)–2.480?(10)?Å, respectively, and the S atoms are in a fac disposition. The crystal structure features numerous N—H?O, N—H?N, O—H?O and O—H?N hydrogen bonds. Two O atoms of a sulfate anion were found to be disordered over two orientations in a 0.620?(9):0.380?(9) ratio. The crystal studied was a racemic twin with BASF = 0.17?(5) PMID:22807774

  16. Greedy Routing with Bounded Stretch

    Microsoft Academic Search

    Roland Flury; Sriram V. Pemmaraju; Roger Wattenhofer

    2009-01-01

    Greedy routing is a novel routing paradigm where messages are always forwarded to the neighbor that is closest to the destination. Our main result is a polynomial-time algorithm that embeds combinatorial unit disk graphs (CUDGs - a CUDG is a UDG without any geometric information) into O(log2n)- dimensional space, permitting greedy routing with constant stretch. To the best of our

  17. High Affinity Carboxylate Binding Using Neutral Urea-Based Receptors with

    E-print Network

    Smith, Bradley D.

    High Affinity Carboxylate Binding Using Neutral Urea-Based Receptors with Internal Lewis Acid to date have employed either Lewis acid-base,3 hydrogen bond- ing,4 and/or ion-dipole interactions.5 Most binding ability of neutral urea-based receptors. It is likely that this strategy can be incorporated

  18. The Comparative Value of Urea and Linseed Meal for Milk Production

    Microsoft Academic Search

    I. W. Rupel; G. Bohstedt; E. B. Hart

    1943-01-01

    In earlier work (5), we established the fact that for the growth of calves urea nitrogen could be successfully used for at least a partial supply of the protein nitrogen. This protein supply, from such a simple substance as urea, was made possible through the multiplication of the microorganisms of the rumen. This intervention of microorganisms and the use of

  19. Potential for Ammonia Volatilization from Urea in Dryland Kentucky Bluegrass Seed Production Systems

    Microsoft Academic Search

    Christopher Proctor; Richard Koenig; William Johnston

    2010-01-01

    Urea replaced ammonium nitrate (AN) as a nitrogen (N) source for dryland Kentucky bluegrass seed production in the inland Pacific Northwest in the United States. This study assessed ammonia (NH3) volatilization, N recovery, and seed yield from urea as compared to AN. Laboratory incubations indicate NH3 volatilization is greater from soil covered by fresh residue than soil alone or covered

  20. Relative Humidity Controls Ammonia Loss from Urea Applied to Loblolly Pine

    Microsoft Academic Search

    Miguel L. Cabrera; David E. Kissel; J. R. Craig; Nikolla Qafoku; N. Vaio; John A. Rema; Larry A. Morris

    2010-01-01

    In the United States of America, approximately 600,000 ha of southern pine are fertilized with urea each year, with NH3 volatilization losses ranging from <1% to >50% depending on environmental conditions. Previous work showed that timing of rainfall after urea application plays a significant role in controlling NH3 loss, but the effect of other environmental variables is not well understood.

  1. 75 FR 19610 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ...A-821-801] Solid Urea From the Russian Federation: Preliminary Results of Antidumping...antidumping duty order on solid urea from the Russian Federation. The review covers one producer...new independent state, including the Russian Federation (Russia). Pursuant to...

  2. 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

  3. 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

  4. 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

  5. Facilitated transport of urea across the gall-bladder luminal membrane.

    PubMed

    Curci, S; Casavola, V; Lippe, C

    1978-05-01

    Counterflow experiments demonstrate the existence of urea counter-transport on the epithelium luminal surface. This phenomenon disappears when 10(-4) M phloretin is added to the perfusion fluid. Moreover counterflow experiments made using thiourea as elicitor, demonstrate that the phenomenon is specific for the urea. PMID:80981

  6. 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...

  7. Changes in the concentrations of glucose, non-esterifed fatty acids, urea, insulin,

    E-print Network

    Paris-Sud XI, Université de

    700 (iEq'L ' and 110 ng-niL-1, respectively). Glucose and insulin levels remained unchanged duringChanges in the concentrations of glucose, non-esterifed fatty acids, urea, insulin, cortisol in the jugular vein, and the evolution of glu- cose, insulin, urea, non-esterified fatty acids (UEFA), calcium

  8. Does urea reabsorption occur via the glucose pathway in the kidney of the freshwater rainbow trout?

    Microsoft Academic Search

    Carol Bucking; Chris M. Wood

    2004-01-01

    This study tested the hypothesis that the renal reabsorption of urea occurs via the glucose transport pathway in the freshwater rainbow trout (Oncorhynchus mykiss). The relationship between glucose transport and urea transport was examined by experimentally elevating the rate of renal glucose reabsorption via infusion of the fish with exogenous glucose, and by inactivating the glucose transporters via the administration

  9. Evidence for urea-induced hypometabolism in isolated organs of dormant ectotherms

    Microsoft Academic Search

    Timothy J. Muir; Jon P. Costanzo; RICHARD E. LEE JR

    2010-01-01

    Many organisms endure extended periods of dormancy by depressing their metabolism, which effectively prolongs the use of their endogenous energy stores. Though the mechanisms of hypometabolism are varied and incompletely understood, recent work suggests that urea accumulation in autumn and early winter contributes to reduced metabolism of hibernating wood frogs (Rana sylvatica). Urea accumulation during dormancy is a widespread phenomenon,

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

    PubMed

    Campbell, K L; MacArthur, R A

    1997-01-01

    The rate of 14C-urea hydrolysis was determined in 32 field-acclimatized muskrats maintained on natural diets during spring, summer, fall, and winter. We hypothesized that urea recycling occurs in muskrats during all seasons and that the conservation of tissue nitrogen via this mechanism is most prevalent in fall and winter, when forage protein levels are lowest. Muskrats exhibited higher rates of urea hydrolysis and a lower serum urea nitrogen-to-creatinine ratio in fall and winter than in spring and summer. Even after correcting for seasonal differences in blood urea pool size, the adjusted rate of urea hydrolysis was 67% higher in fall and winter than in spring and summer. There was no evidence that the maintenance nitrogen requirements of muskrats fed natural vegetation were affected by seasonal changes in the amino acid composition of the diet. We suggest that increased levels of urea recycling, coupled with adaptive mechanisms for reducing nitrogen excretion and possibly conserving carbon skeletons of essential amino acids, may allow muskrats to reduce their nitrogen requirements on fall and winter diets. Our finding that 14C-urea hydrolysis occurred during all four sampling periods suggests that nitrogen derived from this source may also be critical to supporting large hindgut microbe populations that enable this rodent to exploit the appreciable fiber content of its aquatic plant diet throughout the year. PMID:9231395

  11. 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.

  12. 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...

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

    PubMed

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

    2015-01-01

    The amphiphilic osmolyte trimethylamine-N-oxide (TMAO) is commonly found in natural organisms, where it counteracts biochemical stress associated with urea in aqueous environments. Despite the important role of TMAO as osmoprotectant, the mechanism behind TMAO's action has remained elusive. Here, we study the interaction between urea, TMAO, and water in solution using broadband (100 MHz-1.6 THz) dielectric spectroscopy. We find that the previously reported tight hydrogen bonds between 3 water molecules and the hydrophilic amine oxide group of TMAO, remain intact at all investigated concentrations of urea, showing that no significant hydrogen bonding occurs between the two co-solutes. Despite the absence of direct TMAO-urea interactions, the solute reorientation times of urea and TMAO show an anomalous nonlinear increase with concentration, for ternary mixtures containing equal amounts of TMAO and urea. The nonlinear increase of the reorientation correlates with changes in the viscosity, showing that the combination of TMAO and urea cooperatively enhances the hydrogen-bond structure of the ternary solutions. This nonlinear increase is indicative of water mediated interaction between the two solutes and is not observed if urea is combined with other amphiphilic solutes. PMID:25138965

  14. Influence of Urea and Ammonium Sulfate on Soil Acidity Indices in Lowland Rice Production

    Microsoft Academic Search

    N. K. Fageria; A. B. dos Santos; M. F. Moraes

    2010-01-01

    Urea and ammonium sulfate are principal nitrogen (N) sources for crop production. Two field experiments were conducted during three consecutive years to evaluate influence of urea and ammonium sulfate application on grain yield, soil pH, calcium (Ca) saturation, magnesium (Mg) saturation, base saturation, aluminum (Al) saturation, and acidity (H + Al) saturation in lowland rice production. Grain yield was significantly

  15. 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, placement of urea in small holes or nests is a common practice particularly for production of row crops. Placement of fertilizer N in concentrated zones, such as subsurface bands and nests, has been promoted

  16. 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 (3.6mmol-NL(-1)) would restrict the growth of M.aeruginosa and the production of microcystin-LR, while low urea concentration (0.4-1.4mmol-NL(-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

  17. CLINICAL CONSEQUENCES OF UREA CYCLE ENZYME DEFICIENCIES AND POTENTIAL LINKS TO ARGININE AND NITRIC OXIDE METABOLISM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Urea cycle disorders (UCD) are human conditions caused by the dysregulation of nitrogen transfer from ammonia nitrogen into urea. The biochemistry and the genetics of these disorders were well elucidated. Earlier diagnosis and improved treatments led to an emerging, longer-lived cohort of patients. ...

  18. Urea as a PCDD/F inhibitor in municipal waste incineration.

    PubMed

    Ruokojärvi, P; Asikainen, A; Ruuskanen, J; Tuppurainen, K; Mueller, C; Kilpinen, P; Yli-Keturi, N

    2001-03-01

    Emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from municipal waste incineration have been widely studied because of their extensive toxicity, and many efforts have been made to restrict their emissions. Although a number of chemical compounds have been shown in laboratory-scale tests to inhibit the formation of PCDD/Fs, few have been tested in pilot- or full-scale plants. This work evaluates the effect of urea as a PCDD/F inhibitor in a pilot-scale incinerator that uses refuse-derived fuel (RDF). The decomposition of urea under the test conditions was also studied using detailed kinetic modeling. An aqueous solution of urea was injected into the flue gas stream after the furnace at approximately 730 degrees C, with varied urea concentrations and flue gas residence times used between the furnace and the sampling point. The results demonstrate that urea can successfully inhibit PCDD/F formation in waste incineration if concentrations and injection points are properly adjusted. The kinetic model showed that urea can be rapidly decomposed under appropriate flue gas conditions, indicating that in addition to the urea molecule itself, decomposition products of urea can also be responsible for the reduction of PCDD/F production during incineration. PMID:11266105

  19. Microwave reflectivity measurement of silicon urea polyvinyl alcohol \\/ epoxy resin composites in X and Ku bands

    Microsoft Academic Search

    M. Murugan; V. K. Kokate

    2009-01-01

    In the paper presented here, a thermally stable epoxy resin modified urea - polyvinyl alcohol - silicon blends have been prepared by in situ polymerization technique. For this, the materials were modified with triethylene tetramine (hardener) to obtain highly cross-linked thermosetting resins. The authors have synthesized the polymer composites; silicon-urea-polyvinyl alcohol in three ratios in weight percentages with analytical reagent

  20. 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 (...

  1. UREA PRODUCTION, RECYCLING AND EXCRETION IN FORAGE-FED BEEF STEERS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two experiments with growing beef steers fed hays of warm season (gamagrass and switchgrass) or cool season (tall fescue) grasses showed a strong linear relationship between urea production by the animal and urinary urea excretion as functions of nitrogen (crude protein) intake. The nature of the r...

  2. Nitrogen digestion and urea recycling in Hokkaido native horses fed hay-based diets.

    PubMed

    Obitsu, Taketo; Hata, Hiroshi; Taniguchi, Kohzo

    2015-02-01

    Nitrogen (N) digestion and urea-N metabolism in Hokkaido native horses fed roughage-based diets containing different types and levels of protein sources were studied. Horses (173 ± 4.8 kg) fitted with an ileum cannula were fed four diets consisting of 100% timothy hay (TH), 88% TH and 12% soybean meal (SBM), 79% TH and 21% SBM, and 51% TH and 49% alfalfa hay at 2.2% of body weight. Dietary protein content varied from 5% to 15% of dry matter. Apparent N digestibilities in the pre-cecum and total tract for the TH diet were lower than those for other diets. However, the proportion of post-ileum N digestion to N intake was not affected by the diets. Urea-N production was linearly related to N intake, but gut urea-N entry was not affected by the diets. The proportion of gut urea-N entry to urea-N production tended to be higher for the TH diet (57%) than the two SBM diets (39%). Anabolic use of urea-N entering the gut was not affected by the diets (20-36% of gut urea-N entry). These results indicate that urea-N recycling provides additional N sources for microbial fermentation in the hindgut of Hokkaido native horses fed low-quality roughages. PMID:25040128

  3. Combustion - Terascale direct numerical simulations of turbulent combustion

    Microsoft Academic Search

    Jacqueline Chen

    2006-01-01

    Combustion currently provides 85% of our nation's energy needs. Furthermore, because of the large infrastructure costs combustion will continue to be the predominant source of energy for the near and middle term. Concerns over U.S. dependence on imported oil coupled with pollution and greenhouse gas emission issues require that we develop a new generation of combustion systems that provide both

  4. 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 of an annular helicopter combustor. First it is shown that the casing and geometrical details such as primary is commonly observed by turbine manufacturers.10 Moreover, since helicopter combustion chambers usually

  5. 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

  6. Southern States` Routing Agency Report

    SciTech Connect

    Not Available

    1990-03-01

    The Southern States` Routing Agency Report is a compendium of 16-southern states` routing program for the transportation of high-level radioactive materials. The report identifies the state-designated routing agencies as defined under 49 Code of Federal Regulations (CFR) Part 171 and provides a reference to the source and scope of the agencies` rulemaking authority. Additionally, the state agency and contact designated by the state`s governor to receive advance notification and shipment routing information under 10 CFR Parts 71 and 73 are also listed.

  7. Southern States' Routing Agency Report

    SciTech Connect

    Not Available

    1990-03-01

    The Southern States' Routing Agency Report is a compendium of 16-southern states' routing program for the transportation of high-level radioactive materials. The report identifies the state-designated routing agencies as defined under 49 Code of Federal Regulations (CFR) Part 171 and provides a reference to the source and scope of the agencies' rulemaking authority. Additionally, the state agency and contact designated by the state's governor to receive advance notification and shipment routing information under 10 CFR Parts 71 and 73 are also listed.

  8. Access Routes for Nutritional Therapy

    Microsoft Academic Search

    2000-01-01

    Enteral nutrition (EN) and total\\u000a parenteral nutrition (TPN) may provide life-sustaining therapy for\\u000a surgical patients. The duration of nutritional therapy (enteral or\\u000a parenteral) implies distinct access routes. We review the main aspects\\u000a related to access routes for nutrient delivery. The enteral route,\\u000a whenever feasible, is preferred. For EN lasting less than 6 weeks,\\u000a nasoenteric tubes are the route of choice.

  9. Intelligent route surveillance

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  10. 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.

  11. 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...

  12. 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. ...

  13. Combuster. [low nitrogen oxide formation

    NASA Technical Reports Server (NTRS)

    Mckay, R. A. (inventor)

    1978-01-01

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

  14. 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)

  15. Conformational studies on phospholipase C from Bacillus cereus. The effect of urea on the enzyme.

    PubMed Central

    Little, C

    1978-01-01

    1. When heated in 8 M-urea, phospholipase C(EC 3.1.4.3) from Bacillus cereus undergoes conformational transitions depending on the temperatures used. These transitions were studied by examining protein fluorescence, iodide quenching of protein fluorescence, u.v. difference spectroscopy, chemical availability of histidine residues in the enzyme, circular dichroism and catalytic activity. 2. Unless simultaneously exposed to elevated temperatures the enzyme appears to be unaffected by 8 M-urea. Removal of the two zinc atoms from the enzyme renders phospholipase C very sensitive to denaturation by 8 M-urea as indicated by fluorescence emission spectra and circular dichroism. 3. Both the native and the zinc-free enzymes are markedly more resistant to irreversible thermal inactivation in the presence of 8 M-urea than in its absence. 4. The response of the enzyme to 8 M-urea and the role of zinc in stabilizing the enzyme are discussed. PMID:105729

  16. Fuel-Rich Catalytic Combustion

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Olson, Sandra L.

    1987-01-01

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

  17. Integration of commercial routing with flood search routing

    Microsoft Academic Search

    C. B. Duncombe

    1998-01-01

    Integration of commercial personal communications services (PCS) technology with tactical communication systems portends to offer tremendous advantages to the warfighter, not the least of which are improved quality wireless access, and light weight and portable phones. Integration of the two systems will require conversion of signaling and routing protocols. This paper addresses the routing issues for integration of a code

  18. DYNAMIC ROUTES THROUGH VIRTUAL PATHS ROUTING FOR AD HOC NETWORKS

    E-print Network

    Richard III, Golden G.

    DYNAMIC ROUTES THROUGH VIRTUAL PATHS ROUTING FOR AD HOC NETWORKS Abdulrahman H. Altalhi Golden G and selected based on multiple criteria. The rest of this paper is organized as follows. In Section 2, we describe, in a high level, the design and operations of the VPR protocol. In Section 3, we detail

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Flame combustion of carbonaceous fuels

    Microsoft Academic Search

    W. J. Hampton; R. L. Hatch; G. R. James

    1984-01-01

    A method for improving the flame combustion of carbonaceous fuels. The method enables the reduction of oxides of nitrogen generated by the flame combustion, and enables an improvement in boiler efficiency. An ionic sodium or potassium compound, or a combination of them, is supplied with the combustible mixture of fuel and air so as intimately and uniformly to be present

  1. Biomass combustion for power generation

    Microsoft Academic Search

    Richard van den Broek; Ad van Wijk

    1996-01-01

    An overview is given of the state of the art of biomass combustion power generation technologies with a capacity of more than 10 MWe. Biomass combustion technologies have been compared on a qualitative basis and a selection of individual biomass combustion power plants has been compared on a quantitative basis. Collected data were modified for comparison of the various power

  2. Combustion for rubbish and refuse

    Microsoft Academic Search

    Good

    1980-01-01

    An incinerator design and a method for burning both sorted and unsorted rubbish and refuse cleanly and efficiently are presented. Rubbish is inserted in a non-clogging hopper where it is preheated and preliminarily combusted as it moves downwardly to a primary combustion chamber where air is added. A moving grate beneath the primary combustion chamber draws ashes and uncombusted materials

  3. 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

  4. A decade of combustion research

    Microsoft Academic Search

    L. Douglas Smoot

    1997-01-01

    The Advanced Combustion Engineering Research Center (ACERC) at Brigham Young University and the University of Utah, in cooperation with other universities, 37 industrial members and six governmental members, has marked a decade of combustion research. This review emphasizes the contributions of ACERC over this past decade. While the state-of-the-art relating to fossil fuel combustion is discussed, the paper does not

  5. Routing Discovery Algorithm Using Parallel Chase Packet

    Microsoft Academic Search

    Muneer Bani Yassein; Jordan Amera Al-Ameri; Yaser M. Khamayseh; Wail E. Mardini

    2013-01-01

    On demand routing protocols for ad hoc networks such as Ad Hoc On Demand Distance Vector (AODV) initiate a route discovery process when a route is needed by flooding the network with a route request packet. The route discovery process in such protocols depends on a simple flooding as a broadcast technique due to its simplicity. Simple flooding results in

  6. Autonomous routing algorithms for networks with wide-spread failures : a case for differential backlog routing

    E-print Network

    Khan, Wajahat Faheem

    2008-01-01

    We study the performance of a differential backlog routing algorithm in a network with random failures. Differential Backlog routing is a novel routing algorithm where packets are routed through multiple paths to their ...

  7. 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

  8. Macrocyclic bis(ureas) as ligands for anion complexation.

    PubMed

    Kretschmer, Claudia; Dittmann, Gertrud; Beck, Johannes

    2014-01-01

    Two macrocyclic bis(ureas) 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3) molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and act as complexing agents towards a series of anions (Cl(-), Br(-), I(-), NO3 (-), HSO4 (-)). The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via (1)H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions. PMID:25161744

  9. Macrocyclic bis(ureas) as ligands for anion complexation

    PubMed Central

    Kretschmer, Claudia; Dittmann, Gertrud

    2014-01-01

    Summary Two macrocyclic bis(ureas) 1 and 2, both based on diphenylurea, have been synthesized. Compound 1 represents the smaller ring with two ethynylene groups as linkers and 2 the larger ring with two butadiynylene groups. On thermal treatment to 130 °C molecule 1 splits up into two dihydroindoloquinolinone (3) molecules. Both compounds 1 and 2 form adducts with polar molecules such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and act as complexing agents towards a series of anions (Cl?, Br?, I?, NO3 ?, HSO4 ?). The crystal structures of 3, 2·2DMSO, 2·2DMF, and of the complex NEt4[Br·2] have been determined. Quantitative investigations of the complexation equilibria were performed via 1H NMR titrations. While 1 is a rather weak complexing agent, the large ring of 2 binds anions with association constants up to log K = 7.93 for chloride ions. PMID:25161744

  10. Urea cycle defects and hyperammonemia: effects on functional imaging.

    PubMed

    Gropman, Andrea L; Prust, Morgan; Breeden, Andrew; Fricke, Stanley; VanMeter, John

    2013-06-01

    The urea-cycle disorders (UCDs) are a group of congenital enzyme and carrier deficiencies predisposing to hyperammonemia (HA). HA causes changes in the central nervous system (CNS) including alterations of neurotransmitter function, cell volume, and energy deprivation ultimately leading to cerebral edema. Neuropathological findings of UCDs primarily reflect changes in astrocyte morphology. Neurological features accompanying acute HA include changes in behavior and consciousness in the short term, and potential for impairments in memory and executive function as long-term effects. Plasma measures of ammonia and glutamine, although useful for clinical monitoring, prove poor markers of CNS function. Multimodal neuroimaging has potential to investigate impact on cognitive function by interrogating neural networks, connectivity and biochemistry. As neuroimaging methods become increasingly sophisticated, they will play a critical role in clinical monitoring and treatment of metabolic disease. We describe our findings in UCDs; with focus on Ornithine Transcarbamylase deficiency (OTCD) the only X linked UCD. PMID:23149878

  11. On the Action of Acyl Reagents on the Substituted Ureas

    E-print Network

    Roberts, R. Chester

    1914-05-15

    .19 ANALYSIS OF BASE FOR NITROGEN (KJELDAHL). .1246 gram base required 8.76 Cc. N/lO acid. Calculated for (CI9H24N2 Ptmnd Nitrogen 10.00 9.86 The base Is dl-para-tolylisovaleramldlne. ^NC 6H 4CH 3 (CHjgCb 3H« C^ * V NHC6II4CH3 7 DI-PHENYL UREA and META.... .1149 gram substance required 9.49 Cc. N/lO acid. Calculated for CI3HI0°3N2 Pound Nitrogen 11.57 11.50 11.56 The di-phenyl meta-nitrobenzamidine does not seem to have been made from the literature. The para» compound has been made by treating para...

  12. Combustion engine system

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  13. 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.

  14. Combustion of Gaseous Mixtures

    NASA Technical Reports Server (NTRS)

    Duchene, R

    1932-01-01

    This report not only presents matters of practical importance in the classification of engine fuels, for which other means have proved inadequate, but also makes a few suggestions. It confirms the results of Withrow and Boyd which localize the explosive wave in the last portions of the mixture burned. This being the case, it may be assumed that the greater the normal combustion, the less the energy developed in the explosive form. In order to combat the detonation, it is therefore necessary to try to render the normal combustion swift and complete, as produced in carbureted mixtures containing benzene (benzol), in which the flame propagation, beginning at the spark, yields a progressive and pronounced darkening on the photographic film.

  15. 76 FR 23835 - Solid Urea From Russia and Ukraine; Scheduling of Full Five-Year Reviews Concerning the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

    ...731-TA-340-E and 340-H (Third Review)] Solid Urea From Russia and Ukraine; Scheduling...Concerning the Antidumping Duty Orders on Solid Urea From Russia and Ukraine AGENCY: United...revocation of the antidumping duty orders on solid urea from Russia and Ukraine would be...

  16. 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...antidumping duty orders on solid urea from the Russian Federation (Russia) and Ukraine, pursuant...Antidumping Duty Orders on Solid Urea From the Russian Federation and Ukraine'' from Gary...

  17. 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...

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

    E-print Network

    What is Milk Urea Nitrogen and How is It Interpreted? Dr. Doo-Hong Min, Extension Forage Specialist, MSU UPES Milk urea nitrogen (MUN) is another tool to assess the protein and energy balance status of a group of dairy cows and can be used for minimizing feed costs while maximizing production. Milk urea

  19. 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

  20. Stratified charge internal combustion

    SciTech Connect

    Larabie, L.

    1986-12-23

    This patent describes a stove comprising an enclosure having a front wall, a rear wall, top and bottom walls, and two side walls, a smoke outlet made in the top wall, an upper and a lower partition fixedly mounted to the walls in vertically-shaped relationship within the enclosure, intermediate and parallel to the top and bottom walls, a smoke space, and a cooling oven space being defined above the upper partition and between the upper and lower partitions, respectively. A grate extends within the enclosure intermediate the lower partition and the bottom wall, a combustion chamber and an ash-pit are defined above and below the grate respectively. An air intake is located in the combustion chamber. The grate comprises hollow cylindrical metallic ducts, which criss cross in order to form an X and which open outwardly at each end. The ends of each duct extend through and are fixed to the side walls permitting the ambient air to circulate through the ducts. Each of the ducts have an intermediate crossing portion that is substantially flattened, the grate being able to support a solid combustible, yet allowing therethrough by gravity the cinders into the ash-pit. Lateral semi-cylindrical upright pipes are closed at both ends and are fixedly secured to and projecting from the exterior face of each of the side walls between the top wall and the outer ends of the ducts. The side walls have first and second openings making communication between the combustion chamber and the pipes and between the latter and the smoke space, respectively.

  1. Combustion powered linear actuator

    DOEpatents

    Fischer, Gary J. (Albuquerque, NM)

    2007-09-04

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

  2. Hydrogen assisted diesel combustion

    Microsoft Academic Search

    Gregory K. Lilik; Hedan Zhang; José Martin Herreros; Daniel C. Haworth; André L. Boehman

    2010-01-01

    Hydrogen assisted diesel combustion was investigated on a DDC\\/VM Motori 2.5L, 4-cylinder, turbocharged, common rail, direct injection light-duty diesel engine, with a focus on exhaust emissions. Hydrogen was substituted for diesel fuel on an energy basis of 0%, 2.5%, 5%, 7.5%, 10% and 15% by aspiration of hydrogen into the engine's intake air. Four speed and load conditions were investigated

  3. Random Walks in Routing Landscapes

    Microsoft Academic Search

    T. Michalareas; Lionel Sacks

    2001-01-01

    In this paper we present a combinatorial optimisation view on the routing problem for connectionless packet networks by using the metaphor of a landscape. We examine the main properties of the routing landscapes as we define them and how they can help us on the evaluation of the problem difficulty and the generation of effective algorithms. We also present the

  4. Anonymous connections and onion routing

    Microsoft Academic Search

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

    1998-01-01

    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. Onion routing's anonymous connections are bidirectional, near real-time, and can be used anywhere a socket connection can be used. Any identifying information must be in the data stream carried over an anonymous connection. An

  5. Producing Gestures Facilitates Route Learning

    PubMed Central

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

    2014-01-01

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

  6. The Revised ARPANET Routing Metric

    Microsoft Academic Search

    A. Khanna; John A. Zinky

    1989-01-01

    The ARPANBT routing metric was revised in July 1987, re- sulting in substantial performance improvements, especially in terms of user delay and effective network capacity. These revisions only affect the individual link costs (or metrics) on which the PSN (packet switching node) bases its rout- ing decisions. They do not affect the SPF (\\

  7. Scalable VPN routing via relaying

    Microsoft Academic Search

    Changhoon Kim; Alexandre Gerber; Carsten Lund; Dan Pei; Subhabrata Sen

    2008-01-01

    Enterprise customers are increasingly adopting MPLS (Multipro- tocol Label Switching) VPN (Virtual Private Network) service that offers direct any-to-any reachability among the customer s ites via a provider network. Unfortunately this direct reachabilit y model makes the service provider's routing tables grow very large as the number of VPNs and the number of routes per customer increase. As a result,

  8. Supplemental methionine and urea for gestating beef cows consuming low quality forage diets.

    PubMed

    Waterman, R C; Löest, C A; Bryant, W D; Petersen, M K

    2007-03-01

    A study was conducted to evaluate Met requirements of late-gestation beef cows consuming low quality forages on the premise that inadequate supply of metabolizable AA may limit protein accretion during pregnancy. Five ruminally cannulated, multiparous late-gestation beef cows (490 +/- 27 kg), of predominantly Angus (> or =75%) with Hereford and Simmental breeding, were used in a 5 x 5 Latin square experiment to evaluate the effects of postruminal dl-Met supplementation on N retention, serum metabolites, and plasma AA concentrations during the third trimester of pregnancy. The basal diet was fed individually, and weights of refusals were recorded for N intake determination. Treatments consisted of no urea, urea (0.053 +/- 0.002 g/kg of BW daily), urea + 5 g of Met/d, urea + 10 g of Met/d, and urea + 15 g of Met/d. Cows were adapted to the experimental diet 30 d before the beginning of the study, with periods lasting for 14 d; 4 d to allow for clearance of the previous treatment effects, 4 d for adaptation to the treatments, and 6 d for total fecal and urine collection. Blood samples were collected every 4 h on d 13 of each period for analysis of serum metabolites and plasma AA. Inclusion of urea increased DM and OM intakes (urea vs. no urea; P = 0.05), but no further improvement in intake was observed with inclusion of Met. Serum urea concentrations increased with inclusion of urea (P = 0.03) and responded quadratically (P = 0.06) when Met was added, with the lowest concentration observed in the urea + 5 g of Met/d treatment. More N was retained with the inclusion of urea (P = 0.04), and N retention increased linearly (P = 0.07) with inclusion of Met. Plasma Met concentration increased linearly (P < 0.01) with inclusion of Met. These data suggest that Met was a limiting AA and that supplementation of a combination of urea and 5 g/d of rumen-protected Met to low quality, forage diets will improve N retention and promote protein accretion during late pregnancy. PMID:17060412

  9. Relationship of whole body nitrogen utilization to urea kinetics in growing steers.

    PubMed

    Titgemeyer, E C; Spivey, K S; Parr, S L; Brake, D W; Jones, M L

    2012-10-01

    Urea kinetics were measured in 2 experiments, with treatments designed to change protein deposition by the animal. Our hypothesis was that increased protein deposition by cattle (Bos taurus) would reduce urea production and recycling to the gastrointestinal tract. Urea kinetics were measured by continuous intravenous infusion of (15)N(15)N-urea followed by measurement of enrichment in urinary urea at plateau. In Exp. 1, 6 steers (139 kg) were maintained in a model in which leucine was the most limiting AA. Treatments were arranged as a 2 × 3 factorial and were provided to steers in a 6 × 6 Latin square design. Leucine treatments included 0 or 4 g/d of abomasally supplemented L-leucine, and energy treatments included control, abomasal glucose infusion (382 g DM/d), or ruminal VFA infusion (150 g/d of acetic acid, 150 g/d of propionic acid, and 50 g/d of butyric acid). Leucine supplementation increased (P < 0.01) N retention, and energy supplementation tended to increase (P = 0.09) N retention without differences between glucose and VFA supplements (P = 0.86). Energy supplementation did not strikingly improve the efficiency of leucine utilization. Although both leucine and energy supplementation reduced urinary urea excretion (P ? 0.02), treatments did not affect urea production (P ? 0.34) or urea recycling to the gut (P ? 0.30). The magnitude of change in protein deposition may have been too small to significantly affect urea kinetics. In Exp. 2, 6 steers (168 kg) were maintained in a model wherein methionine was the most limiting AA. Steers were placed in 2 concurrent 3 × 3 Latin squares. Steers in one square were implanted with 24 mg of estradiol and 120 mg trenbolone acetate, and steers in the other square were not implanted. Treatments in each square were 0, 3, or 10 g/d of L-methionine. Implantation numerically improved N retention (P = 0.13) and reduced urea production rate (P = 0.03), urinary urea excretion (P < 0.01), and urea recycling to the gastrointestinal tract (P = 0.14). Effects of methionine were similar to implantation, but smaller in magnitude. When protein deposition by the body is increased markedly, ruminally available N in the diet may need to be increased to offset reductions in urea recycling. PMID:22851238

  10. Spray combustion stability

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  11. 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.

  12. Flame combustion of carbonaceous fuels

    SciTech Connect

    Hampton, W.J.; Hatch, R.L.; James, G.R.

    1984-05-08

    A method for improving the flame combustion of carbonaceous fuels. The method enables the reduction of oxides of nitrogen generated by the flame combustion, and enables an improvement in boiler efficiency. An ionic sodium or potassium compound, or a combination of them, is supplied with the combustible mixture of fuel and air so as intimately and uniformly to be present where and when the flame exists. Preferably the compound is supplied in an aqueous solution, and can be intimately mixed with the fuel, or with the atomizing air or steam, or with the combustion air. The process is useful with both single-stage and staged (multiple-staged) combustion systems.

  13. 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.

  14. Deterministic 1-k Routing on Meshes With Applications to Worm-Hole Routing

    E-print Network

    Deterministic 1-k Routing on Meshes With Applications to Worm-Hole Routing Jop F. Sibeyn Michael. 1-k routing also has implications for hot-potato worm-hole routing, which is of great importance this algorithm considerably reduces the routing time of hot-potato worm-hole routing. Non-trivial extensions

  15. A novel DHT Routing Protocol for MANETs

    E-print Network

    Chellamani, Deepak

    2010-04-30

    The central challenge in Mobile Ad hoc Networks (MANETs) is to provide a stable routing strategy without depending on any central administration. This work presents and examines the working of Radio Ring Routing Protocol (RRRP), a DHT based routing...

  16. An adaptive control strategy for urea-SCR aftertreatment system

    Microsoft Academic Search

    Mona Meisami-Azad; Javad Mohammadpour; Karolos M. Grigoriadis; Michael P. Harold

    2010-01-01

    Hydrocarbons, carbon monoxide, and other polluting emissions produced by diesel engines are usually much lower than those from gasoline engines. However, higher combustion temperature in diesel engines cause substantially larger percentage of nitrogen oxides (NOx) emissions. Selective catalyst reduction (SCR) is a well proven technology for reducing NOx emissions from automotive sources and in particular, heavy-duty truck diesel engines. In

  17. [The nature of urea transport across the skin of of Rana esculenta].

    PubMed

    Svelto, M; Casavola, V; Valenti, G; Lippe, C

    1982-06-30

    In several epithelial tissues such as toad bladder, gallbladder and human red cells, it has been established that urea movement implies a phloretin sensitive mediated transport. In the skin of the toad Bufo viridis also it has been described an active transport of urea. Our data, obtained on the frog skin seem to demonstrate the existence of some specific mechanism for urea transport towards the inside solution. In fact, two molecules having the some molecular diameter, such as urea and thiourea, show a large difference in permeability at low concentration. In addition 0.1 mM urea influxes and outfluxes, measured on paired skin halves in the absence of concentration gradient, exhibit an evident asymmetry. Further approaches with phloretin experiments were made in order to characterize the urea transport system. Phloretin (5.10(-4)M) added to the external solution significantly inhibits the urea influx. Little can be said at this time about the composition or kinetics of the carrier involved in the transport. PMID:6980654

  18. A newly prepared surface-treated oxystarch for removal of urea.

    PubMed

    Shimizu, T; Fujishige, S

    1983-07-01

    There is an urgent need to develop an efficient technique to remove urea from the blood or gastrointestinal tract of uremic patients. Activated charcoals have a low sorption capacity for urea although they effectively remove other uremic toxic substances. To provide an urea-reactive adsorbent, a chemically modified oxystarch with albumin or gelatin has been prepared. Elemental analysis and Fourier transform infrared (FT-IR) spectroscopic analysis demonstrate that the reaction of a small amount of protein (albumin or gelatin) with oxystarch has taken place possibly by chemical combination. The influence of the dialdehyde content of the oxystarch on urea sorption, its sorption isotherm, and the adsorption rates have been investigated. It was found that the swelling factor of the oxystarch is closely related to the sorption activity under physiological conditions (pH 7.2-7.4 at 37 degrees C). Adsorption studies have shown that sorption capacity is increased by surface treatment and can reach 6-8.2 g urea/kg-dried adsorbent (initial urea concentration was 70 mg/dL). The oxystarch had 49.2% of glucose unit oxidized and was surface treated with albumin. These results suggest that the newly prepared surface-treated oxystarch would be utilized as an effective chemisorbent for urea removal under physiological conditions. PMID:6885841

  19. 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.

  20. Proceedings of the Combustion Institute. Volume 30

    SciTech Connect

    NONE

    2005-01-15

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

  1. Charge-signal multiplication mediated by urea wires inside Y-shaped carbon nanotubes.

    PubMed

    Lv, Mei; He, Bing; Liu, Zengrong; Xiu, Peng; Tu, Yusong

    2014-07-28

    In previous studies, we reported molecular dynamics (MD) simulations showing that single-file water wires confined inside Y-shaped single-walled carbon nanotubes (Y-SWNTs) held strong and robust capability to convert and multiply charge signals [Y. S. Tu, P. Xiu, R. Z. Wan, J. Hu, R. H. Zhou, and H. P. Fang, Proc. Natl. Acad. Sci. U.S.A. 106, 18120 (2009); Y. Tu, H. Lu, Y. Zhang, T. Huynh, and R. Zhou, J. Chem. Phys. 138, 015104 (2013)]. It is fascinating to see whether the signal multiplication can be realized by other kinds of polar molecules with larger dipole moments (which make the experimental realization easier). In this article, we use MD simulations to study the urea-mediated signal conversion and multiplication with Y-SWNTs. We observe that when a Y-SWNT with an external charge of magnitude 1.0 e (the model of a signal at the single-electron level) is solvated in 1 M urea solutions, urea can induce drying of the Y-SWNT and fill its interiors in single-file, forming Y-shaped urea wires. The external charge can effectively control the dipole orientation of the urea wire inside the main channel (i.e., the signal can be readily converted), and this signal can further be multiplied into 2 (or more) output signals by modulating dipole orientations of urea wires in bifurcated branch channels of the Y-SWNT. This remarkable signal transduction capability arises from the strong dipole-induced ordering of urea wires under extreme confinement. We also discuss the advantage of urea as compared with water in the signal multiplication, as well as the robustness and biological implications of our findings. This study provides the possibility for multiplying signals by using urea molecules (or other polar organic molecules) with Y-shaped nanochannels and might also help understand the mechanism behind signal conduction in both physical and biological systems. PMID:25084937

  2. Charge-signal multiplication mediated by urea wires inside Y-shaped carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lv, Mei; He, Bing; Liu, Zengrong; Xiu, Peng; Tu, Yusong

    2014-07-01

    In previous studies, we reported molecular dynamics (MD) simulations showing that single-file water wires confined inside Y-shaped single-walled carbon nanotubes (Y-SWNTs) held strong and robust capability to convert and multiply charge signals [Y. S. Tu, P. Xiu, R. Z. Wan, J. Hu, R. H. Zhou, and H. P. Fang, Proc. Natl. Acad. Sci. U.S.A. 106, 18120 (2009); Y. Tu, H. Lu, Y. Zhang, T. Huynh, and R. Zhou, J. Chem. Phys. 138, 015104 (2013)]. It is fascinating to see whether the signal multiplication can be realized by other kinds of polar molecules with larger dipole moments (which make the experimental realization easier). In this article, we use MD simulations to study the urea-mediated signal conversion and multiplication with Y-SWNTs. We observe that when a Y-SWNT with an external charge of magnitude 1.0 e (the model of a signal at the single-electron level) is solvated in 1 M urea solutions, urea can induce drying of the Y-SWNT and fill its interiors in single-file, forming Y-shaped urea wires. The external charge can effectively control the dipole orientation of the urea wire inside the main channel (i.e., the signal can be readily converted), and this signal can further be multiplied into 2 (or more) output signals by modulating dipole orientations of urea wires in bifurcated branch channels of the Y-SWNT. This remarkable signal transduction capability arises from the strong dipole-induced ordering of urea wires under extreme confinement. We also discuss the advantage of urea as compared with water in the signal multiplication, as well as the robustness and biological implications of our findings. This study provides the possibility for multiplying signals by using urea molecules (or other polar organic molecules) with Y-shaped nanochannels and might also help understand the mechanism behind signal conduction in both physical and biological systems.

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

    PubMed

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

    2010-09-29

    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 (C(8)E(4)), n-octylpentaoxyethylene (C(8)E(5)), n-decylhexaoxyethylene (C(10)E(6)), n-dodecylhexaoxyethylene (C(12)E(6)) and n-dodecyloctaoxylethylene (C(12)E(8)) - 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 C(8)E(4) and C(12)E(6). In contrast, C(8)E(5) and C(12)E(8) 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

  4. An alternative explanation for the collapse of unfolded proteins in an aqueous mixture of urea and guanidinium chloride

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2014-09-01

    Molecular dynamics simulations have shown that a totally unfolded protein in aqueous 8 M urea undergoes a collapse transition on replacing urea molecules by guanidinium chloride, GdmCl, assuming a compact conformation in 4 M urea + 4 M GdmCl [J. Am. Chem. Soc. 134 (2012) 18266]. This is unexpected because GdmCl is a denaturant stronger than urea. It is shown that such collapse can originate from an increase in the magnitude of the solvent-excluded volume effect due the high density of urea + GdmCl mixtures, coupled to their low water number density that pushes denaturant molecules toward the protein surface.

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

    PubMed

    Taylor-Edwards, C C; Hibbard, G; Kitts, S E; McLeod, K R; Axe, D E; Vanzant, E S; Kristensen, N B; Harmon, D L

    2009-01-01

    Two experiments were conducted to evaluate the effects of slow-release urea (SRU) versus feed-grade urea on ruminal metabolite characteristics in steers and DMI, gain, and G:F in growing beef steers. Experiment 1 used 12 ruminally cannulated steers (529 +/- 16 kg of BW) to monitor the behavior of SRU in the ruminal environment. Compared with feed-grade urea, SRU decreased ruminal ammonia concentration (P = 0.02) and tended to increase ruminal urease activity (P = 0.06) without affecting ruminal VFA molar proportions or total concentrations (P > 0.20). After 35 d of feeding, the in situ degradation rate of SRU was not different between animals fed urea or SRU (P = 0.48). Experiment 2 used 180 Angus-cross steers (330 +/- 2.3 kg) fed corn silage-based diets supplemented with urea or SRU for 56 d to evaluate the effects on feed intake, gain, and G:F. The design was a randomized complete block with a 2 x 4 + 1 factorial arrangement of treatments. Treatments included no supplemental urea (control) or urea or SRU at 0.4, 0.8, 1.2, or 1.6% of diet DM. Over the entire 56 d experiment, there were interactions of urea source x concentration for gain (P = 0.04) and G:F (P = 0.01) because SRU reduced ADG and G:F at the 0.4 and 1.6% supplementation concentrations but was equivalent to urea at the 0.8 and 1.2% supplementation concentrations; these effects were due to urea source x concentration interactions for gain (P = 0.06) and G:F (P = 0.05) during d 29 to 56 of the experiment. The SRU reduced DMI during d 29 to 56 (P = 0.01) but not during d 0 to 28, so that over the entire experiment there was no difference in DMI for urea source (P = 0.19). These collective results demonstrate that SRU releases N slowly in the rumen with no apparent adaptation within 35 d. Supplementation of SRU may limit N availability at low (0.4%) concentrations but is equivalent to urea at 0.8 and 1.2% concentrations. PMID:18820164

  6. [Determination of urea distribution space on the basis of hemodialysis quantification].

    PubMed

    Erben, J; Schück, O; Moucka, P; Fixa, P; Hájková, B; Herout, V; Stilec, R; Zahradník, J; Palicka, V

    1993-12-01

    By using direct dialysis quantification--DDQ--in 124 haemodialyses made in 14 patients the authors assessed the urea output in mmol in the dialyzation fluid collected after every dialysis. The evaluation of total body fluids, which accounts roughly for 60% of the total body weight, was replaced by a calculated distribution space of urea (Vu) according to the Du/Ppre--Ppost formula. This equation was modified with regard to the degree of ultrafiltration and urea formation. The authors found a 5% difference between the values of the modified Vu equation and total body fluids corresponding to 60% of the body weight. PMID:8310663

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

    SciTech Connect

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

    2000-02-01

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

  8. 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.

  9. Combustion Byproducts Recycling Consortium

    SciTech Connect

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

    2008-08-31

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

  10. Combustion Branch Website Development

    NASA Technical Reports Server (NTRS)

    Bishop, Eric

    2004-01-01

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

  11. Lagrangian Simulation of Combustion

    SciTech Connect

    Ahmed F. Ghoniem

    2008-05-01

    A Lagrangian approach for the simulation of reactive flows has been developed during the course of this project, and has been applied to a number of significant and challenging problems including the transverse jet simulations. An efficient strategy for parallel domain decomposition has also been developed to enable the implementation of the approach on massively parallel architecture. Since 2005, we focused our efforts on the development of a semi-Lagrangian treatment of diffusion, and fast and accurate Lagrangian simulation tools for multiphysics problems including combustion.

  12. Hybrid fluidized bed combuster

    SciTech Connect

    Kantesaria, Prabhudas P. (Windsor, CT); Matthews, Francis T. (Poquonock, CT)

    1982-01-01

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

  13. 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.

  14. Combustion Experiment Apparatus

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Interior of a combustion experiment apparatus used in the 2.2-second drop tower at NASA's Glenn Research Center. This was shown to students participating in the second Dropping in a Microgravity Environment (DIME) competition held April 23-25, 2002, at NASA's Glenn Research Center. Competitors included two teams from Sycamore High School, Cincinnati, OH, and one each from Bay High School, Bay Village, OH, and COSI Academy, Columbus, OH. DIME is part of NASA's education and outreach activities. Details are on line at http://microgravity.grc.nasa.gov/DIME_2002.html.

  15. Breaking Up with Combustion

    NSDL National Science Digital Library

    Maisie Shaw

    2010-01-01

    This activity teaches combustion as the interaction of a fuel source and oxygen. A burning candle is observed, then extinguished—first by a glass cup placed over it to cut off the oxygen supply, then using carbon dioxide generated by vinegar and baking soda. Some background information is provided about how car engines use gasoline as fuel, and how humans use food as fuel— both are similar to how the candle uses wax as fuel. The activity is written for a kit that can be checked out of the library, but the kit is not required.

  16. 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

  17. Salt Potentiates Methylamine Counteraction System to Offset the Deleterious Effects of Urea on Protein Stability and Function

    PubMed Central

    Singh, Laishram R.; Warepam, Marina; Ahmad, Faizan; Dar, Tanveer Ali

    2015-01-01

    Cellular methylamines are osmolytes (low molecular weight organic compounds) believed to offset the urea’s harmful effects on the stability and function of proteins in mammalian kidney and marine invertebrates. Although urea and methylamines are found at 2:1 molar ratio in tissues, their opposing effects on protein structure and function have been questioned on several grounds including failure to counteraction or partial counteraction. Here we investigated the possible involvement of cellular salt, NaCl, in urea-methylamine counteraction on protein stability and function. We found that NaCl mediates methylamine counteracting system from no or partial counteraction to complete counteraction of urea’s effect on protein stability and function. These conclusions were drawn from the systematic thermodynamic stability and functional activity measurements of lysozyme and RNase-A. Our results revealed that salts might be involved in protein interaction with charged osmolytes and hence in the urea-methylamine counteraction. PMID:25793733

  18. Effects of fertilizer-urea on growth, photosynthetic activity and microcystins production of Microcystis aeruginosa isolated from Dianchi Lake.

    PubMed

    Huang, Wenmin; Bi, Yonghong; Hu, Zhengyu

    2014-05-01

    Urea is the most frequently applied nitrogen (N) fertilizer in agriculture, while its loss is assumed triggering algal blooms in adjacent water bodies. In this context the present study assessed the growth, photosynthetic activity as well as toxin production of Microcystis aeruginosa at different urea concentrations (0.125, 1.25, 12.5, 250 and 2,500 mg/L) using BG11 (containing 250 mg/L NO3(-)-N) as control. The results showed for all endpoints that M. aeruginosa is capable of using urea as N source: the two highest urea treatments delivered comparable values like the control. Low urea concentrations (0.125 and 1.25 mg/L), which were comparable to environmental urea levels, did not sustainably promote the growth, photosynthesis and toxin production of the test species. While, in certain microenvironments urea might potentially reach the concentrations that may affect M. aeruginosa. PMID:24515350

  19. Protocol Independent Adaptive Route Update for VANET

    PubMed Central

    Rasheed, Asim; Qayyum, Amir

    2014-01-01

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

  20. Protocol independent adaptive route update for VANET.

    PubMed

    Rasheed, Asim; Ajmal, Sana; Qayyum, Amir

    2014-01-01

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

  1. Past Tense Route Priming

    PubMed Central

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

    2013-01-01

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

  2. Routing Physarum with repellents.

    PubMed

    Adamatzky, A

    2010-04-01

    Plasmodium of Physarum polycephalum is a single cell with many nuclei. Plasmodium is an easy-to-experiment-with biological substrate, a multi-functional bio-material used to implement novel and future computing architectures. The plasmodium exhibits typical features of excitable chemical systems and capable for distributed sensing, parallel information processing and decentralized actuation. Plasmodium of P. polycephalum is proved to be a universal storage modification machine. Actively growing zones of the plasmodium are considered to be elementary processors of the growing computing machine, as well as messages traveling in the spatially extended non-linear medium. Controlling propagation of the messages and computing processes is a prerequisite for a successful implementation of working prototypes of plasmodium machines. In laboratory experiments and computer simulation we show that active growing zones of plasmodium can be precisely routed using repelling diffusion gradients generated by crystals of sodium chloride. We demonstrate how to achieve controllable reflection, splitting/multiplication and merging of plasmodium's active zones. PMID:20401510

  3. PCI: Toward cleaner combustion

    SciTech Connect

    NONE

    1997-01-01

    Westinghouse Electric Corp. and Precision Combustion Inc. (PCI) have announced that they will cooperate on the development of a catalytic combustion system for possible use in the upcoming A.T.S. engine. As we learned during a recent visit, this is only one of many catalyst applications being explored by PCI. This paper discuses these developments and applications, which include: an ultra-low-emission catalytic converter for reciprocating auto exhaust systems, which would meet the American U.L.E.V. (ultra-low emission vehicle) regulations (0.2 gm/mi NO{sub x}, 1.7 gm/mi CO, 0.04 gm/mi hydrocarbons). This is named Microlith{sup TM}; a `flashback arrestor` to limit flash-back in gas turbines; a catalytic igniter, particularly suited to aero gas turbines. This would replace the spark ignition system, and would provide lean flame stabilization, as well as re-ignition in case of a flameout; a catalytic glow plug for diesel engines; and a catalytic muffler for very small reciprocating engines, such as those on lawn mowers.

  4. Coal combustion ash haulback

    SciTech Connect

    Gray, R.E.; Gray, T.A. [GAI Consultants, Inc., Monroeville, PA (United States)

    1998-12-31

    Coal mining disturbs large tracts of land which must be reclaimed. Unfortunately, iron sulfides which are common in most coals and the adjacent strata weather, forming acid mine drainage (AMD) which degrades surface and ground water. Burning of coal produces combustion by products, most of which are placed in ponds or landfills. Suitable disposal areas are difficult to find and permit, especially in urban areas. This has led to ash haulback--where the waste generated during coal burning is hauled back to a mine for disposal. The potential advantages of coal combustion ash haulback are: Disposal occurs in a disturbed area (mine) rather than disturb additional land near the power plant; The same vehicles used to haul coal from the mine can be used to return the ash to the mine; Ash, if alkaline, may provide neutralization of acidic water or mine overburden commonly found at coal mines; and Low permeability ash could reduce ground water flow through the mine backfill, thus reducing leaching of acid forming constituents or metals. Placement of ash in surface mines provides an efficient, cost-effective method of disposal while at the same time contributing to reclamation of the mine. Wise natural resource management suggests a reasonable approach to disposal of coal ash is to return it to its original location--the mine.

  5. Fuel Flexibility in Combustion

    SciTech Connect

    Freeman, M.C.; O'Dowd, W.J.; Mathur, M.P. (U.S. DOE National Energy Technology Laboratory); Walbert, G.F. (Parsons Infrastructure and Technology, Inc.)

    2001-11-06

    This poster presents research findings from cofiring studies of various biomass feedstocks such as pentachlorophenol (PCP) and creosote-treated wood, lumber mill and furniture waste sawdusts, pallets, feedlot biomass (cattle manure), hybrid willow, and switchgrass with several bituminous and subbituminous coals. This research includes evaluation of advanced instrumentation and the study of interrelated combustion/emissions issues, such as char burnout, impacts on SO2, NOx, fine particulate (PM2.5), mercury (Hg) and other trace emissions, as well as issues impacting heat transfer, such as ash deposition slagging/fouling behavior. Biomass cofiring in large industrial and utility coal-fired boilers is a practical approach for increasing renewable energy given the wide availability, capital investment, and established performance of coal-fired boilers for providing efficient, low cost power. Although some utility biomass cofiring is successfully practiced in the U.S. and abroad, establishing long-term reliability and improving economics are still significant needs, along with research to support advanced combustion in future Vision 21 systems. Biomass cofiring in Vision 21 systems may reduce fossil CO2 emissions per MWe at capital and operations/maintenance cost savings relative to other technology options. Because an increasing number (currently 14) states have recently passed legislation establishing renewable portfolio standards (RPS), goals, or set-asides that will impact new power generation by 2009 and beyond, cofiring may broaden the appeal of Vision 21 systems to solve other environmental issues, including reducing landfill requirements. Legislation has been proposed to establish a federal RPS as well as extend IRS Section 29/45 tax credits (e.g., $0.005-0.010/kW-hr) for cofiring residues to supplement existing incentives, such as a $0.015/kW-hr tax credit for closed loop biomass (e.g., energy crops, such as switchgrass, hybrid willow) gasification. In addition, the coproduction/cogeneration concepts embodied in Vision 21 may also lend itself well to the type of utility/industry partnering involved in cofiring approaches. In light of the cost limitations in shipping distance (e.g., 50-100 miles or less) from collection to end-use based on the low energy density of biomass, resource availability is a site-specific consideration. Biomass fuels also exhibit significant differences in fuel characteristics, including volatility and ash chemistry that can also influence cofiring performance. Pilot-scale biomass cofiring tests have been conducted in the 150 kWt Combustion and Environmental Research Facility (CERF). A key aspect of the present work is to examine biomass char conversion for a range of initial particle sizes at various residence times for combustion relative to fuel processing/handling issues. In addition, a number of biomass cofiring R&D as well as full-scale utility demonstrations are providing technical insights to assist in cofiring technology commercialization. The paper will also discuss research plans, including lignin cofiring for ethanol/power co-production, novel concepts involving animal waste utilization, advanced combustion studies, and tri-firing concepts with other fuels.

  6. 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).

  7. Ammonia Loss from Urea Surface-Applied to Cold Soils Rick Engel and Clain Jones

    E-print Network

    Lawrence, Rick L.

    Ammonia Loss from Urea Surface-Applied to Cold Soils Rick Engel and Clain Jones Montana State spring is a common management practice for dryland winter wheat production in Montana. Soil temperatures during this time are often cold (

  8. Nickel-cobalt bimetallic anode catalysts for direct urea fuel cell.

    PubMed

    Xu, Wei; Zhang, Huimin; Li, Gang; Wu, Zucheng

    2014-01-01

    Nickel is an ideal non-noble metal anode catalyst for direct urea fuel cell (DUFC) due to its high activity. However, there exists a large overpotential toward urea electrooxidation. Herein, NiCo/C bimetallic nanoparticles were prepared with various Co contents (0, 10, 20, 30 and 40 wt%) to improve the activity. The best Co ratio was 10% in the aspect of cell performance, with a maximum power density of 1.57 mW cm(-2) when 0.33 M urea was used as fuel, O2 as oxidant at 60 °C. The effects of temperature and urea concentration on DUFC performance were investigated. Besides, direct urine fuel cell reaches a maximum power density of 0.19 mW cm(-2) with an open circuit voltage of 0.38 V at 60 °C. PMID:25168632

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

    NASA Astrophysics Data System (ADS)

    Chermahini, Alireza Najafi; Teimouri, Abbas; Farrokhpour, Hossein

    2014-11-01

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

  10. [Long-term study "Neurodermatitis therapy using urea-containing Externa". Experience report of a pediatrician].

    PubMed

    Schweingel, D

    1992-01-01

    The experience gained in the pediatric sector within the framework of a neurodermatitis study on the use of urea and urea/hydrocortisone combinations will be reported. Particularly in young children, these preparations yield very good results, even after short-term use. The compliance of the patients is increased because, using alternating therapy, these preparations quickly make it possible for the patients to responsibly help determine their own therapy. The active participation of the parents in therapy makes it easier for the therapist to improve access to the psychosomatic environment of the disease. The consistent use of urea/hydrocortisone and urea preparations is a valuable enhancement of an all-encompassing neurodermatic therapy. PMID:1555939

  11. DEVELOPMENT OF UREA-SCR FOR HEAVY-DUTY TRUCKS DEMONSTRATION UPDATE

    SciTech Connect

    Miller, William

    2000-08-20

    This study included engine cell and vehicle tests. The engine cell tests are aimed at determining NOX reduction using the US transient and OICA emissions test cycles. These cycles will be included in future US HD emissions standards. The vehicle tests will show urea-SCR system performance during real-world operation. These tests will prove that the technology can be successfully implemented and demonstrated over-the-road. The program objectives are to: (a) apply urea-SCR to a US HD diesel engine; (b) determine engine cell emissions reduction during US-transient and OICA cycles; (c) apply urea-SCR to a US HD diesel truck; and (d) determine NOX reduction and urea consumption during over-the-road operation.

  12. Nickel-cobalt bimetallic anode catalysts for direct urea fuel cell

    PubMed Central

    Xu, Wei; Zhang, Huimin; Li, Gang; Wu, Zucheng

    2014-01-01

    Nickel is an ideal non-noble metal anode catalyst for direct urea fuel cell (DUFC) due to its high activity. However, there exists a large overpotential toward urea electrooxidation. Herein, NiCo/C bimetallic nanoparticles were prepared with various Co contents (0, 10, 20, 30 and 40?wt%) to improve the activity. The best Co ratio was 10% in the aspect of cell performance, with a maximum power density of 1.57?mW cm?2 when 0.33?M urea was used as fuel, O2 as oxidant at 60°C. The effects of temperature and urea concentration on DUFC performance were investigated. Besides, direct urine fuel cell reaches a maximum power density of 0.19?mW cm?2 with an open circuit voltage of 0.38?V at 60°C. PMID:25168632

  13. Polymorphic transformation of cellulose I to cellulose II by alkali pretreatment and urea as an additive.

    PubMed

    Gupta, P K; Uniyal, Vanshi; Naithani, Sanjay

    2013-05-15

    The effect on crystalline structure transformation from cellulose I to cellulose II polymorph was studied of the cotton linter treated with NaOH with and without urea as an additive, analyzed by wide-angle X-ray diffraction analysis. Cotton linter treated with increasing NaOH concentration showed at 15 wt% sudden transformation from cellulose I to cellulose II polymorph. But when urea 5 wt% was used as additive along with 15 wt% NaOH concentration the magnitude of the transformation reduced largely. The crystallinity index showed a gradual decrease with increasing concentration of NaOH. The crystallinity index showed a gradual decrease with increasing concentration of NaOH with or without addition of urea, nevertheless with addition of urea a further slight more transformation was also observed. PMID:23544641

  14. Urea, sugar, nonesterified fatty acid and cholesterol content of the blood in prolonged weightlessness

    NASA Technical Reports Server (NTRS)

    Balakhovskiy, I. S.; Orlova, T. A.

    1975-01-01

    Biochemical blood composition studies on astronauts during weightlessness flight simulation tests and during actual space flights showed some disturbances of metabolic processes. Increases in blood sugar, fatty acid and cholesterol, and urea content are noted.

  15. Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea

    E-print Network

    Hammock, Bruce D.

    Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea (recently also known as Rhizobium radiobacter) using both genotypic and phenotypic characterization, ureaformaldehyde, slow-release fertilizer, soil, nitrogen, isolation, Agrobacterium tumefaciens, Rhizobium

  16. Epoxy-terminated self-assembled monolayers containing internal urea or amide groups.

    PubMed

    Ramin, Michaël A; Le Bourdon, Gwénaëlle; Heuzé, Karine; Degueil, Marie; Buffeteau, Thierry; Bennetau, Bernard; Vellutini, Luc

    2015-03-10

    We report the synthesis of new coupling agents with internal amide or urea groups possessing an epoxy-terminal group and trimethoxysilyl-anchoring group. The structural characterizations of the corresponding self-assembled monolayers (SAMs) were performed by polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS). The molecular assembly is mainly based on the intermolecular hydrogen-bonding between adjacent amide or urea groups in the monolayers. Because of the steric hindrance of amide or urea groups, the distance between the alkyl chains is too large to establish van der Waals interactions, inducing their disorder. The reactivity of the epoxy-terminal groups was successfully investigated through reaction with a fluorescent probe. We show that SAMs containing internal urea or amide groups exhibited a higher density of accessible epoxide groups than the corresponding long-chain (C22) glycidyl-terminated SAM. PMID:25679263

  17. Effect of perfusate hematocrit on urea permeability-surface area in isolated dog lung

    SciTech Connect

    Parker, R.E.; Roselli, R.J.; Haselton, F.R.; Harris, T.R.

    1986-10-01

    Seven dog lower left lung lobes were statically inflated and perfused at a constant rate for each lobe with a perfusate in which the hematocrit was altered over a wide range. The permeability-surface area of urea was calculated from multiple indicator dilution curves using two separate injectates for each hematocrit level. One injectate contained only /sup 125/I-albumin as the vascular reference tracer and the other contained both /sup 51/Cr-erythrocytes and /sup 125/I-albumin as the vascular reference tracers; both contained (/sup 14/C)urea as the permeating tracer. The results strongly indicate that the phenomenon of erythrocyte trapping of urea does not affect the calculation of urea permeability-surface area product provided the appropriate albumin-erythrocyte composite reference tracer is utilized in its calculation.

  18. Effects of dietary urea supplementation on ruminal ammonia concentrations and microbial protein synthesis

    E-print Network

    Kang, Joan Huei

    1978-01-01

    ?IIIEIITAL D . ETS COIIPOS1TIOITS (AIP, -DI?Y BASIS) xp. Ifuri. Diet (%) Feed Intake (kg/day) . k Ba al 7 5 8. 5 III IV V VI Basal + Ii% C. P. E. of' urea 8. 5 Basal + 2% C. P. E. of' urea 9 ' 6 Basal + 5% C. P. E. of urea 10. 8 Basal + 4. 5% C. P... ?'? j ? s ~ pjj C, P, . s urea 26 90 + 2i90 . 64 + . 06 . 43 + ~ 15 579+ 17JJ (CO;TIHDED) '~~y3j-3 4: (Con I)inued) . ': oi; TiP, P , j)/ Dl"1r )HAPP, D)P!)jr Corrected 3acterial Crude Protein Yeilds DAP u v!oJ e/p;m lag 8!jj/1002m DHD r...

  19. SANS and DLS Studies of Protein Unfolding in Presence of Urea and Surfactant

    SciTech Connect

    Aswal, V. K.; Chodankar, S. N.; Wagh, A. G. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kohlbrecher, J.; Vavrin, R. [Laboratory for Neutron Scattering, ETH Zurich and Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2008-03-17

    Small-angle neutron scattering (SANS) and dynamic light scattering (DLS) have been used to study conformational changes in protein bovine serum albumin (BSA) during its unfolding in presence of protein denaturating agents urea and surfactant. On addition of urea, the BSA protein unfolds for urea concentrations greater than 4 M and acquires a random coil configuration with its radius of gyration increasing with urea concentration. The addition of surfactant unfolds the protein by the formation of micelle-like aggregates of surfactants along the unfolded polypeptide chains of the protein. The fractal dimension of such a protein-surfactant complex decreases and the overall size of the complex increases on increasing the surfactant concentration. The conformation of the unfolded protein in the complex has been determined directly using contrast variation SANS measurements by contrast matching the surfactant to the medium. Results of DLS measurements are found to be in good agreement with those obtained using SANS.

  20. Structures of interpolymer complexes based on carboxymethylcellulose and urea-formaldehyde resin

    Microsoft Academic Search

    M. M. Khafizov

    2005-01-01

    Interaction of carboxymethylcellulose with polymeric condensation products of urea and formaldehyde was studied. The structure\\u000a of the final product was found to depend on the nature and structure of the components involved in the interaction.

  1. New techniques for geographic routing

    E-print Network

    Leong, Ben Wing Lup

    2006-01-01

    As wireless sensor networks continue to grow in size, we are faced with the prospect of emerging wireless networks with hundreds or thousands of nodes. Geographic routing algorithms are a promising alternative to tradition ...

  2. New Techniques for Geographic Routing

    E-print Network

    Leong, Ben

    2006-06-14

    As wireless sensor networks continue to grow in size, we are facedwith the prospect of emerging wireless networks with hundreds orthousands of nodes. Geographic routing algorithms are a promisingalternative to tradition ...

  3. Network knowledge and route choice

    E-print Network

    Ramming, Michael Scott

    2002-01-01

    Models of urban traveler route choice are reviewed in the context of Intelligent Transportation Systems, particularly Advanced Traveler Information S ystems. Existing models suffer from assumptions of perfect information ...

  4. Dynamic flow control strategies of vehicle SCR Urea Dosing System

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Zhang, Youtong; Asif, Malik

    2015-01-01

    Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine's operating conditions. That will lead to low NO X conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between -8% and 10% to -4% and 2% and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms. The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NO X emission remains almost unchanged. The trade-off between NO X conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine's operating conditions quickly.

  5. Defects in amino acid catabolism and the urea cycle.

    PubMed

    Hoffmann, Georg F; Kölker, Stefan

    2013-01-01

    Symptoms in patients with defects in amino acid catabolism and the urea cycle usually develop because of intoxication of accumulating metabolites. The cumulative prevalence of these disorders is considerable (at least>1:2000 newborns). Timely and correct intervention during the initial presentation and during later episodes is most important. Evaluation of metabolic parameters should be performed on an emergency basis in every patient with symptoms of unexplained metabolic crisis, intoxication, and/or unexplained encephalopathy. A substantial number of patients develop acute encephalopathy or chronic and fluctuating progressive neurological disease. The so-called cerebral organic acid disorders present with (progressive) neurological symptoms: ataxia, myoclonus, extrapyramidal symptoms, and "metabolic stroke." Important diagnostic clues, such as white matter abnormalities, cortical or cerebellar atrophy, and injury of the basal ganglia can be derived from cranial magnetic resonance imaging (MRI). Long-term neurological disease is common, particularly in untreated patients, and the manifestations are varied, the most frequent being (1) mental defect, (2) epilepsy, and (3) movement disorders. Successful treatment strategies are becoming increasingly available. They mostly require an experienced interdisciplinary team including a neuropediatrician and/or later on a neurologist. PMID:23622399

  6. Dynamic flow control strategies of vehicle SCR Urea Dosing System

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Zhang, Youtong; Asif, Malik

    2015-03-01

    Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine's operating conditions. That will lead to low NO X conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between -8% and 10% to -4% and 2% and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms. The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NO X emission remains almost unchanged. The trade-off between NO X conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine's operating conditions quickly.

  7. Composite propellant combustion modeling studies

    NASA Technical Reports Server (NTRS)

    Ramohalli, K.

    1977-01-01

    A review is presented of theoretical and experimental studies of composite propellant combustion. The theoretical investigations include a model of the combustion of a nonmetallized ammonium perchlorate (AP) propellant (noting time scales for vapor-phase combustion and the condensed phase) and response functions in pressure-coupled oscillations. The experimental studies are discussed with reference to scale-modeling apparatus, flame standoff distance versus velocity as a function of pressure, and results from T-burner firings of a nonmetallized AP/polysulfide propellant. Research applications including problems with nitramine propellants, the feasibility of stop-restart rockets with salt quench, and combustion problems in large boosters are outlined.

  8. 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.

  9. Flammability of Heterogeneously Combusting Metals

    NASA Technical Reports Server (NTRS)

    Jones, Peter D.

    1998-01-01

    Most engineering materials, including some metals, most notably aluminum, burn in homogeneous combustion. 'Homogeneous' refers to both the fuel and the oxidizer being in the same phase, which is usually gaseous. The fuel and oxidizer are well mixed in the combustion reaction zone, and heat is released according to some relation like q(sub c) = delta H(sub c)c[((rho/rho(sub 0))]exp a)(exp -E(sub c)/RT), Eq. (1) where the pressure exponent a is usually close to unity. As long as there is enough heat released, combustion is sustained. It is useful to conceive of a threshold pressure beyond which there is sufficient heat to keep the temperature high enough to sustain combustion, and beneath which the heat is so low that temperature drains away and the combustion is extinguished. Some materials burn in heterogeneous combustion, in which the fuel and oxidizer are in different phases. These include iron and nickel based alloys, which burn in the liquid phase with gaseous oxygen. Heterogeneous combustion takes place on the surface of the material (fuel). Products of combustion may appear as a solid slag (oxide) which progressively covers the fuel. Propagation of the combustion melts and exposes fresh fuel. Heterogeneous combustion heat release also follows the general form of Eq.(1), except that the pressure exponent a tends to be much less than 1. Therefore, the increase in heat release with increasing pressure is not as dramatic as it is in homogeneous combustion. Although the concept of a threshold pressure still holds in heterogeneous combustion, the threshold is more difficult to identify experimentally, and pressure itself becomes less important relative to the heat transfer paths extant in any specific application. However, the constants C, a, and E(sub c) may still be identified by suitable data reduction from heterogeneous combustion experiments, and may be applied in a heat transfer model to judge the flammability of a material in any particular actual-use situation. In order to support the above assertions, two investigations are undertaken: 1) PCT data are examined in detail to discover the pressure dependence of heterogeneous combustion experiment results; and 2) heterogeneous combustion in a PCT situation is described by a heat transfer model, which is solved first in simplified form for a simple actual-use situation, and then extended to apply to PCT data reduction (combustion constant identification).

  10. Anonymous Connections and Onion Routing

    Microsoft Academic Search

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

    1997-01-01

    Onion Routing provides anonymous connections that are strongly resistant to both eavesdropping and tra c analysis. Unmodi ed Internet applications can use these anonymous connections by means of prox-ies. The proxies may also make communication anony-mous by removing identifying information from the data stream. Onion routing has been implemented on Sun Solaris 2.X with proxies for Web browsing, remote logins,

  11. Fairness in optimal routing algorithms

    E-print Network

    Goos, Jeffrey Alan

    1988-01-01

    FAIRNESS IN OPTIMAL ROUTING ALGORITHMS A Thesis by JEFFREY ALAN GOOS Submitted to the Office of Graduate Studies of Texas AkM University in partial fulfiHment of the requirements for the degree of MASTER OF SCIENCE December 1988 Major... Subject: Electrical Engineering FAIRNESS IN OPTIMAL ROUTING ALGORITHMS A Thesis by JEFFREY ALAN GOOS Approved as to style and content by: Wei K. Tsai (Co-Chairman of Committee) C Pierce E. Cantrell (Co-Chairman of Committee) Jer D. Gibson...

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

    DOEpatents

    Wijmans Johannes G. (Menlo Park, CA); Merkel, Timothy C. (Menlo Park, CA); Baker, Richard W. (Palo Alto, CA)

    2012-05-15

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

  13. Milk urea as nutritional indicator in sheep grazing legume-based pastures

    Microsoft Academic Search

    G. Molle; V. Giovanetti; A. Cabiddu; M. Cuccureddu; G. Scanu; M. Decandia

    A three-year study was carried out to assess the effects of different grass-legume mixtures on: (i) dietary CP and NEL (Net Energy for milk production) concentrations and milk urea level; and (ii) the relationship between milk urea and several dietary variables. Replicate groups of Sardinian sheep in early-mid lactation (January-May) rotationally grazed plots of three grass-legume mixtures consisting of common

  14. Effect of High-Urea Supplementation on Feed Intake and Milk Production of Dairy Cows1

    Microsoft Academic Search

    H. H. Van Horn; C. F. Foreman; J. E. Rodriguez

    1967-01-01

    Two experiments were conducted to study the effects of urea on ration palatabil- ity, milk yield, and economy of nitrogen utilization. In Experiment 1 concentrate acceptability was studied with 20 cows assigned to two 5 × 5 Latin squares bal- anced for residual effects. Addition of 2.2 and 2.7% urea and 15.9 and 19.0% col~l cobs to the concentrates significantly

  15. Wetting of soy protein adhesives modified by urea on wood surfaces

    Microsoft Academic Search

    Hua-Neng Xu; Qiu-Yun Shen; Xiao-Kun Ouyang; Li-Ye Yang

    Wetting of soy protein adhesives modified by urea on wood surfaces was investigated with sessile liquid droplet method. Dynamic\\u000a contact angles were used to illustrate the wetting process. The effects of wood surface roughness and urea concentration on\\u000a contact angles were investigated. Moreover, two wetting models were used to describe the dynamic contact angle process, in\\u000a which the contact angle

  16. EFFECTS OF INCREMENTAL UREA SUPPLEMENTATION ON RUMINAL AMMONIA CONCENTRATION AND BACTERIAL PROTEIN FORMATION 1 ,2

    Microsoft Academic Search

    J. H. Kang-Meznarich; G. A. Broderick; Texas A

    Summary Increments of O, I, 2, 3, 4.5 and 6.5% crude protein equivalent (CPE) were added as urea to a basal diet containing 75% corn and 20% cottonseed hulls (8.3% protein from all natural sources) and fed to two nonlactating Holstein cows. Ruminal ammonia nitrogen (N) levels increased (P<.05) with each increment of urea and ranged from 1.3 (basal) to

  17. Urea-SCR: a promising technique to reduce NO x emissions from automotive diesel engines

    Microsoft Academic Search

    M. Koebel; M. Elsener; M. Kleemann

    2000-01-01

    Urea-SCR, the selective catalytic reduction using urea as reducing agent, has been investigated for about 10 years in detail and today is a well established technique for DeNOx of stationary diesel engines. It is presently also considered as the most promising way to diminish NOx emissions originating from heavy duty vehicles, especially trucks.The paper discusses the fundamental problems and challenges

  18. Evaluation of calcium chloride and ammonium thiosulfate as ammonia volatilization inhibitors for surface-applied urea

    E-print Network

    Sloan, John J.

    1989-01-01

    EVALUATION OF CALCIUM CHLORIDE AND AMMONIUM THIOSULFATE AS AMMONIA VOLATILIZATION INHIBITORS FOR SURFACE-APPLIED UREA A Thesis by JOHN J. SLOAN Submitted to the Office of Graduate Studies of Texas AgcM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1989 Ma!or Subject: Soil Science EVALUATION OF CALCIUM CHLORIDE AND AMMONIUM THIOSULFATE AS AMMONIA VOLATILIZATION INHIBITORS FOR SURFACE-APPLIED UREA A Thesis by JOHN J. SLOAN Approved as to style...

  19. A Large Response Range Reflectometric Urea Biosensor Made from Silica-Gel Nanoparticles

    PubMed Central

    Alqasaimeh, Muawia; Heng, Lee Yook; Ahmad, Musa; Raj, A.S. Santhana; Ling, Tan Ling

    2014-01-01

    A new silica-gel nanospheres (SiO2NPs) composition was formulated, followed by biochemical surface functionalization to examine its potential in urea biosensor development. The SiO2NPs were basically synthesized based on sol–gel chemistry using a modified Stober method. The SiO2NPs surfaces were modified with amine (-NH2) functional groups for urease immobilization in the presence of glutaric acid (GA) cross-linker. The chromoionophore pH-sensitive dye ETH 5294 was physically adsorbed on the functionalized SiO2NPs as pH transducer. The immobilized urease determined urea concentration reflectometrically based on the colour change of the immobilized chromoionophore as a result of the enzymatic hydrolysis of urea. The pH changes on the biosensor due to the catalytic enzyme reaction of immobilized urease were found to correlate with the urea concentrations over a linear response range of 50–500 mM (R2 = 0.96) with a detection limit of 10 mM urea. The biosensor response time was 9 min with reproducibility of less than 10% relative standard deviation (RSD). This optical urea biosensor did not show interferences by Na+, K+, Mg2+ and NH4+ ions. The biosensor performance has been validated using urine samples in comparison with a non-enzymatic method based on the use of p-dimethylaminobenzaldehyde (DMAB) reagent and demonstrated a good correlation between the two different methods (R2 = 0.996 and regression slope of 1.0307). The SiO2NPs-based reflectometric urea biosensor showed improved dynamic linear response range when compared to other nanoparticle-based optical urea biosensors. PMID:25054632

  20. Lactational performance of high producing dairy cows fed diets containing salmon meal and urea.

    PubMed

    Windschitl, P M

    1991-10-01

    Thirty Holstein cows were used in a 12-wk trial to study the effects of salmon meal and urea on lactational performance. Two experimental diets, one containing 5.6% salmon meal and the other 5.2% salmon meal plus .42% urea, were compared with a soybean meal control diet. Salmon meal and urea replaced a portion of the soybean meal. Dietary undegraded intake protein levels (expressed as percentage of CP) were 28.8, 35.6, and 32.4% for soybean meal, salmon meal, and salmon meal plus urea. Total mixed diets (average 17.3% CP, 17.6% ADF) consisting of 60% concentrate mixture and 40% bromegrass silage (DM basis) were fed twice daily. Total DMI was lower with salmon meal compared with soybean meal (20.2 versus 22.2 kg/d); salmon meal plus urea (21.2 kg/d) was intermediate. Actual milk production was similar for all diets (average 41.1 kg/d). Percentage milk fat and 4% FCM yield were lower with salmon meal (2.56%, 31.6 kg/d) and salmon meal plus urea (2.50%, 31.4 kg/d) than with soybean meal (3.03%, 35.9 kg/d). Gross efficiency (weight FCM/weight DMI) was higher for soybean meal than for salmon meal and salmon meal plus urea. Acetate: propionate tended to be higher with the soybean meal diet. The use of a high oil fish meal to provide a source of rumen undegraded intake protein, alone or in combination with urea, resulted in a decrease in milk fat percentage and yield without any beneficial effects on milk production or lactational efficiency. PMID:1744278

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

    PubMed

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

    2015-03-01

    Even though urea and nitrate are the two major nitrogen (N) forms applied as fertilizers in agriculture and occur concomitantly in soils, the reciprocal influence of these two N sources on the mechanisms of their acquisition are poorly understood. Therefore, molecular and physiological aspects of urea and nitrate uptake were investigated in maize (Zea mays), a crop plant consuming high amounts of N. In roots, urea uptake was stimulated by the presence of urea in the external solution, indicating the presence of an inducible transport system. On the other hand, the presence of nitrate depressed the induction of urea uptake and, at the same time, the induction of nitrate uptake was depressed by the presence of urea. The expression of about 60,000 transcripts of maize in roots was monitored by microarray analyses and the transcriptional patterns of those genes involved in nitrogen acquisition were analyzed by real-time reverse transcription-PCR (RT-PCR). In comparison with the treatment without added N, the exposure of maize roots to urea modulated the expression of only very few genes, such as asparagine synthase. On the other hand, the concomitant presence of urea and nitrate enhanced the overexpression of genes involved in nitrate transport (NRT2) and assimilation (nitrate and nitrite reductase, glutamine synthetase 2), and a specific response of 41 transcripts was determined, including glutamine synthetase 1-5, glutamine oxoglutarate aminotransferase, shikimate kinase and arogenate dehydrogenase. Also based on the real-time RT-PCR analysis, the transcriptional modulation induced by both sources might determine an increase in N metabolism promoting a more efficient assimilation of the N that is taken up. PMID:25524070

  2. Residual kidney function and plasma urea concentration in patients with chronic renal failure

    Microsoft Academic Search

    J. Erben; H. Nádvorníková; V. Teplan; O. Mare?ková; I. Skála; V. Reitschlägerová

    1990-01-01

    The relationships between the plasma levels of urea (Purea), renal clearance of urea (Curea) and creatinine (Ccr) at an intake of 0.5 g protein\\/kg body weight\\/day were followed in 10 patients with chronic renal failure (CRF) under balance\\u000a conditions. Under these conditions, Purea attained a value of 30 mmol\\/l when Curea had decreased below 3.8 ml\\/min. By contrast, no correlation

  3. Design, synthesis and evaluation of non-urea inhibitors of soluble epoxide hydrolase

    E-print Network

    Hammock, Bruce D.

    , these inhibitors suffered from rapid metabolism in vivo.16 Recent studies have focused on piperidine-based di- and trisubstituted ureas, such as N-(1-(2,2,2-trifluoroethanoyl)piperidin-4-yl)-N0 -(adamant-1-yl)ur- ea (TPAU) and N-(1-acetylpiperidin-4-yl)-N0 -(adamant-1-yl)urea (APAU).17,18 Some of these piperidine-based compounds

  4. New solvents and functional materials prepared from cellulose solutions in alkali\\/urea aqueous system

    Microsoft Academic Search

    Xiaogang Luo; Lina Zhang

    2010-01-01

    Cellulose, the most abundant renewable polysaccharide on earth, has safe, biocompatible, hydrophilic and biodegradable natures, and is one of the best candidates for food packing and other functional materials. However, cellulose is hard to dissolve in most common solvents, which limited its development and application. In this paper, the quick dissolution of cellulose in NaOH\\/urea, NaOH\\/thiourea and LiOH\\/urea aqueous systems

  5. Adhesive properties of soy proteins modified by urea and guanidine hydrochloride

    Microsoft Academic Search

    Weining Huang; Xiuzhi Sun

    2000-01-01

    An investigation was conducted on the adhesive and water-resistance properties of soy protein isolates that were modified\\u000a by varying solutions of urea (1, 3, 5, and 8 M) or guanidine hydrochloride (GH) (0.5, 1, and 3 M) and applied on walnut, cherry,\\u000a and pine plywoods. Soy proteins modified by 1 and 3 M urea showed greater shear strengths than did

  6. A Durable Flame Retardant Finish for Cotton Based On Thpc and Urea

    Microsoft Academic Search

    Darrell J. Donaldson; Floyd L. Normand; George L. Drake; Wilson A. Reeves

    1974-01-01

    Sodium phosphate salts catalyzed the reaction of THPC with urea. Cotton textiles treated with a solution containing 26.6% THPC, 8.4% urea, 4% dibasic sodium phosphate and sufficient NaOH to adjust the pH to 6, dried 85°C and cured at 160°C for 1 to 2 minutes passed the DOC FF 3-71 flame test after 50 laundry cycles. The samples retained 90

  7. Benzothiophene piperazine and piperidine urea inhibitors of fatty acid amide hydrolase (FAAH)

    PubMed Central

    Johnson, Douglas S.; Ahn, Kay; Kesten, Suzanne; Lazerwith, Scott E.; Song, Yuntao; Morris, Mark; Fay, Lorraine; Gregory, Tracy; Stiff, Cory; Dunbar, James B.; Liimatta, Marya; Beidler, David; Smith, Sarah; Nomanbhoy, Tyzoon K.; Cravatt, Benjamin F.

    2011-01-01

    The synthesis and structure–activity relationships (SAR) of a series of benzothiophene piperazine and piperidine urea FAAH inhibitors is described. These compounds inhibit FAAH by covalently modifying the enzyme’s active site serine nucleophile. Activity-based protein profiling (ABPP) revealed that these urea inhibitors were completely selective for FAAH relative to other mammalian serine hydrolases. Several compounds showed in vivo activity in a rat complete Freund’s adjuvant (CFA) model of inflammatory pain. PMID:19386497

  8. Benzothiophene piperazine and piperidine urea inhibitors of fatty acid amide hydrolase (FAAH).

    PubMed

    Johnson, Douglas S; Ahn, Kay; Kesten, Suzanne; Lazerwith, Scott E; Song, Yuntao; Morris, Mark; Fay, Lorraine; Gregory, Tracy; Stiff, Cory; Dunbar, James B; Liimatta, Marya; Beidler, David; Smith, Sarah; Nomanbhoy, Tyzoon K; Cravatt, Benjamin F

    2009-05-15

    The synthesis and structure-activity relationships (SAR) of a series of benzothiophene piperazine and piperidine urea FAAH inhibitors is described. These compounds inhibit FAAH by covalently modifying the enzyme's active site serine nucleophile. Activity-based protein profiling (ABPP) revealed that these urea inhibitors were completely selective for FAAH relative to other mammalian serine hydrolases. Several compounds showed in vivo activity in a rat complete Freund's adjuvant (CFA) model of inflammatory pain. PMID:19386497

  9. Genetics of larval urea and ammonia tolerance and cross-tolerance in Drosophila melanogaster

    Microsoft Academic Search

    Daniel J. Borash; Masakazu Shimada

    2001-01-01

    Five laboratory populations of Drosophila melanogaster previously selected for over 60 generations for larval resistance to ammonium chloride (NH4Cl), and five populations selected for over 60 generations for larval resistance to urea, were investigated to determine the genetic mechanisms through which such tolerance had evolved. To examine the genetics of tolerance to urea and ammonia, egg-to-adult survivorship and developmental time

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

    Microsoft Academic Search

    Tsippy Tamiri; Rinat Rozin; Nitay Lemberger; Joseph Almog

    2009-01-01

    Urea nitrate is a powerful improvised explosive, frequently used by terrorists in the Israeli arena. It was also used in the\\u000a first World Trade Center bombing in New York in February 1993. It is difficult to identify urea nitrate in post-explosion\\u000a debris, since only a very small fraction survives the blast. Also, in the presence of water, it readily decomposes

  11. Routing Around Decoys Max Schuchard1

    E-print Network

    Minnesota, University of

    , University of California, Berkeley ABSTRACT Decoy Routing is a new approach to Internet censorship circum routing aims to ham- per nation-state level Internet censorship by having routers, rather than end hosts routing systems. We explore China, Syria, Iran, and Egypt as routing capable ad- versaries, and evaluate

  12. Introduction HYBRID FLAME: combustion of a combustible gas and

    E-print Network

    Barthelat, Francois

    Future Work Verify data obtained for methane and aluminum flame Run test with constant equivalence ratioIntroduction HYBRID FLAME: combustion of a combustible gas and dust particles Hybrid Flames: occur may propagate at given conditions Quenching distances: important parameter for flame ignition

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

    PubMed

    Peterson, B T; Harris, T R; Brigham, K L

    1983-02-01

    The objective of this work was to compare the blood-tissue transport properties of 14C-urea and 24Na in the lung circulation. The extraction of both substances was measured relative to intravascular reference tracers (125I-albumin for 24Na, 51Cr red cells and 125I-albumin for 14C-urea) in single-pass transpulmonary multiple indicator curves measured in awake sheep. Sheep were studied in baseline condition, after infusion of histamine solution (4 micrograms/kg-min for 4 hr), and after microvascular pressure was elevated. Permeability-surface area was computed for both sodium (PSn) and urea (PSu) by the Crone extraction model and by a mathematical model. In spite of the fact that the free diffusion coefficients of sodium and urea are approximately equal, the mean ratio of Crone PSn/PSu for baseline studies was 0.76. PSu was significantly increased by histamine infusion but PSn was not. The variation in PSn with histamine and increased pressure was marked. Thus, neither manipulation altered the ratio PSn/PSu in a consistent fashion. Correction of PS for extravascular distribution volumes of urea and Na did not change the PS ratio significantly. We concluded that the diffusional resistance to sodium is higher than expected from its diffusivity, possibly because of charge, and that PS for urea is more sensitive to changes in lung vascular permeability. PMID:6341042

  14. Urea degradation by electrochemically generated reactive chlorine species: products and reaction pathways.

    PubMed

    Cho, Kangwoo; Hoffmann, Michael R

    2014-10-01

    This study investigated the transformation of urea by electrochemically generated reactive chlorine species (RCS). Solutions of urea with chloride ions were electrolyzed using a bismuth doped TiO2 (BiOx/TiO2) anode coupled with a stainless steel cathode at applied anodic potentials (Ea) of either +2.2 V or +3.0 V versus the normal hydrogen electrode. In NaCl solution, the current efficiency of RCS generation was near 30% at both potentials. In divided cell experiments, the pseudo-first-order rate of total nitrogen decay was an order of magnitude higher at Ea of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl2(-)·) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N2 (91%) and NO3(-) (9%). The higher reaction selectivity with respect to N2 production can be ascribed to a low operational ratio of free available chlorine to N. The mass-balance analysis recovered urea-C as CO2 at 77%, while CO generation most likely accounts for the residual carbon. In light of these results, we propose a reaction mechanism involving chloramines and chloramides as reaction intermediates, where the initial chlorination is the rate-determining step in the overall sequence of reactions. PMID:25219459

  15. The effect of conditioning agents on the corrosive properties of molten urea

    SciTech Connect

    Nichols, D E; Nguyen, D T; Norton, M M; Parker, B R; Daniels, L E

    1991-01-01

    From the process case histories of the failure of several heat exchanger tube bundles, it was revealed that molten urea containing lignosulfonate as a granulation conditioning-hardening agent (Urea LS[trademark]) is corrosive to Types 304 and 316 stainless steel. The results of field and laboratory immersion corrosion tests indicated that the corrosivity of molten urea is strongly dependent on the process temperature rather than the conditioner composition. At temperatures below 295F, molten Urea LS[trademark] is not aggressive to these stainless steels. However, at temperatures above 300F, the corrosion of these stainless steels is extremely severe. The corrosion rate of Types 304, 304L, 316, and 316L is as high as hundreds of mils per year. The corrosion mechanism tends to be more general than localized. The results of the laboratory corrosion test also revealed that among alloying elements, copper is detrimental to corrosion resistance of stainless steel exposed to molten Urea LS[trademark], chromium is the most beneficial, and nickel has only a minor effect. Thus, copper-free and chromium stainless steels have superior corrosion resistance to the molten Urea LS[trademark] at a wide range of temperatures up to 345F.

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

    PubMed Central

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

    2013-01-01

    Helicobacter pylori survival in acidic environments relies on cytoplasmic hydrolysis of gastric urea into ammonia and carbon dioxide, which buffer the pathogen’s periplasm. Urea uptake is greatly enhanced and regulated by HpUreI, a proton-gated inner membrane channel protein essential for gastric survival of H. pylori. The crystal structure of HpUreI describes a static snapshot of the channel with two constriction sites near the center of the bilayer that are too narrow to allow passage of urea or even water. Here we describe the urea transport mechanism at atomic resolution, revealed by unrestrained microsecond equilibrium molecular dynamics simulations of the hexameric channel assembly. Two consecutive constrictions open to allow conduction of urea, which is guided through the channel by interplay between conserved residues that determine proton rejection and solute selectivity. Remarkably, HpUreI conducts water at rates equivalent to aquaporins, which might be essential for efficient transport of urea at small concentration gradients. PMID:24305683

  17. Comparison of Templating Abilities of Urea and Thioruea During Photodimerization of Bipyridylethyelene and Stilbazole Crystals.

    PubMed

    Bhogala, Balakrishna R; Captain, Burjor; Ramamurthy, Vaidhyanathan

    2014-09-28

    Photodimerization of cocrystals of four bispyridylethylenes and two stilbazoles with urea as a template in the solid state has been investigated following our success with thiourea. Four investigated olefins photodimerized quantitatively to a single dimer in the crystalline state only. The reactivity of urea-olefin crystals is understood on the basis of their packing arrangements in the crystalline state. In reactive crystals the adjacent reactive molecules are within 4.2 Å and parallel, whereas the unreactive ones have their adjacent molecules are farther than 4.6Å and nonparallel. Thus, with the knowledge of crystal packing the reactivity of urea-olefin crystals is predictable on the basis of Schmidt's topochemical postulates. The templating property of urea, similar to thiourea, derives from its ability to form hydrogen bonds with itself and the guest olefins. Despite the similarities in molecular structures of urea and thiourea their subtle electronic properties, yet to be fully understood, affect the crystal packing and consequently their reactivity in the crystalline state. Further work is needed to fully exploit the templating properties of urea. PMID:25263180

  18. Studies on in vitro degradation and in vivo digestion of a slow ammonia releasing urea product.

    PubMed

    Virk, A S; Steingass, H; Menke, K H

    1989-01-01

    a slow ammonia releasing urea product (Uromalt) has been produced by autoclaving and drying of germinated barley and urea. In vitro degradability of nitrogen (IVDN, Raab et al., 1983) was in average 62 +/- 9% in 4 hours, compared to 76 +/- 8% with an autoclaved and dried mixture of urea and not-germinated barley. Mixtures of urea with Leucaena l. or Azadarichta indica (Neem cake) showed degradabilities of about 80 and 93%, respectively, when dried at 39 degrees C, but of 65% when dried at 100 degrees C. For comparison, degradabilities of proteins of ground nut, guar, sunflower, mustard, rape and sesame cake/meal have been determined. When growing lambs were fed a ration containing 15% Uromalt, faecal N-excretion was significantly higher on the expense of urinary N-excretion, compared with groups fed isonitrogenous rations containing soya bean meal with or without urea and molasses. N-retention was not significantly affected. It is concluded that this slow ammonia releasing urea product can be used in cases where molasses or other feedingstuffs rich in rapidly fermentable carbohydrates are not available. PMID:2735818

  19. Determination of derivatized urea in exhaled breath condensate by LC-MS.

    PubMed

    Quan, Zhe; Purser, Christine; Baker, Rodney C; Dwyer, Terry; Bhagat, Rajesh; Sheng, Yinghong; Leszczynski, Jerzy R

    2010-02-01

    Elevation in one or more compounds in exhaled breath condensate (EBC) has been reported to be related to one or another lung disease. The increased concentration might be caused by increased chemicals in the airway surface liquid. However, it might also be due to an increased delivery of liquid samples into the airstream. Being evenly distributed throughout the body, urea is a likely candidate for a marker of such dilution. A liquid chromatography-tandem mass spectrometry method was developed for determination of EBC urea. Urea in EBC samples was converted to 2-hydroxypyrimidine (2-HPM) through a one step reaction, along with (15)N(2)-urea added as an internal standard. The product ion m/z 97/42 was selected for quantification with m/z 99/43 from (15)N(2)-2-HPM as a standard. Concentrations of urea in EBC from five lung cancer patients were found to be 35.1, 2.2, 103.5, 19.3, and 3.6 microM, respectively. The highest values were in patients dying of respiratory distress, whose lungs were filled with fluid. Lower values were seen in patients whose conditions were improving. Lately, one of the low EBC urea values was observed in a patient whose airway status did not contribute to his poor clinical condition. PMID:20109293

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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