Water Injected Turbomachinery

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Shouse, D. T.; Roquemore, W. M.

2005-01-01

From antiquity, water has been a source of cooling, lubrication, and power for energy transfer devices. More recent applications in gas turbines demonstrate an added facet, emissions control. Fogging gas turbine inlets or direct injection of water into gas turbine combustors, decreases NOx and increases power. Herein we demonstrate that injection of water into the air upstream of the combustor reduces NOx by factors up to three in a natural gas fueled Trapped Vortex Combustor (TVC) and up to two in a liquid JP-8 fueled (TVC) for a range in water/fuel and fuel/air ratios.

Investigation of a low NOx full-scale annular combustor

NASA Technical Reports Server (NTRS)

1982-01-01

An atmospheric test program was conducted to evaluate a low NOx annular combustor concept suitable for a supersonic, high-altitude aircraft application. The lean premixed combustor, known as the vortex air blast (VAB) concept, was tested as a 22.0-cm diameter model in the early development phases to arrive at basic design and performance criteria. Final demonstration testing was carried out on a full scale combustor of 0.66-m diameter. Variable geometry dilution ports were incorporated to allow operation of the combustor across the range of conditions between idle (T(in) = 422 K, T(out) = 917 K) and cruise (T(in) = 833 K, T(out) - 1778 K). Test results show that the design could meet the program NOx goal of 1.0 g NO2/kg fuel at a one-atmospheric simulated cruise condition.

Exhaust gas emissions of a vortex breakdown stabilized combustor

NASA Technical Reports Server (NTRS)

Yetter, R. A.; Gouldin, F. C.

1976-01-01

Exhaust gas emission data are described for a swirl stabilized continuous combustor. The combustor consists of confined concentric jets with premixed fuel and air in the inner jet and air in the outer jet. Swirl may be induced in both inner and outer jets with the sense of rotation in the same or opposite directions (co-swirl and counter-swirl). The combustor limits NO emissions by lean operation without sacrificing CO and unburned hydrocarbon emission performance, when commercial-grade methane and air fired at one atmosphere without preheat are used. Relative swirl direction and magnitude are found to have significant effects on exhaust gas concentrations, exit temperatures, and combustor efficiencies. Counter-swirl gives a large recirculation zone, a short luminous combustion zone, and large slip velocities in the interjet shear layer. For maximum counter-swirl conditions, the efficiency is low.

Wide range operation of advanced low NOx combustors for supersonic high-altitude aircraft gas turbines

NASA Technical Reports Server (NTRS)

Roberts, P. B.; Fiorito, R. J.

1977-01-01

An initial rig program tested the Jet Induced Circulation (JIC) and Vortex Air Blast (VAB) systems in small can combustor configurations for NOx emissions at a simulated high altitude, supersonic cruise condition. The VAB combustor demonstrated the capability of meeting the NOx goal of 1.0 g NO2/kg fuel at the cruise condition. In addition, the program served to demonstrate the limited low-emissions range available from the lean, premixed combustor. A follow-on effort was concerned with the problem of operating these lean, premixed combustors with acceptable emissions at simulated engine idle conditions. Various techniques have been demonstrated that allow satisfactory operation on both the JIC and VAB combustors at idle with CO emissions below 20 g/kg fuel. The VAB combustor was limited by flashback/autoignition phenomena at the cruise conditions to a pressure of 8 atmospheres. The JIC combustor was operated up to the full design cruise pressure of 14 atmospheres without encountering an autoignition limitation although the NOx levels, in the 2-3 g NO2/kg fuel range, exceeded the program goal.

Wide range operation of advanced low NOx aircraft gas turbine combustors

NASA Technical Reports Server (NTRS)

Roberts, P. B.; Fiorito, R. J.; Butze, H. F.

1978-01-01

The paper summarizes the results of an experimental test rig program designed to define and demonstrates techniques which would allow the jet-induced circulation and vortex air blast combustors to operate stably with acceptable emissions at simulated engine idle without compromise to the low NOx emissions under the high-altitude supersonic cruise condition. The discussion focuses on the test results of the key combustor modifications for both the simulated engine idle and cruise conditions. Several range-augmentation techniques are demonstrated that allow the lean-reaction premixed aircraft gas turbine combustor to operate with low NOx emissons at engine cruise and acceptable CO and UHC levels at engine idle. These techniques involve several combinations, including variable geometry and fuel switching designs.

On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid ^4{He}

NASA Astrophysics Data System (ADS)

Niemetz, M.; Hänninen, R.; Schoepe, W.

2017-05-01

The flow of superfluid ^4{He} around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity v_c that scales as ω ^{1/2} and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as T^4 until background damping, measured in the empty cell, becomes dominant for T < 0.1 K. Increasing the velocity amplitude above v_c leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as (v^2 - v_c^2). In a small velocity interval Δ v {/} v_c ≤ 3% above v_c, the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with Δ v^2. We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially.

Advanced Low NO Sub X Combustors for Supersonic High-Altitude Aircraft Gas Turbines

NASA Technical Reports Server (NTRS)

Roberts, P. B.; White, D. J.; Shekleton, J. R.

1975-01-01

A test rig program was conducted with the objective of evaluating and minimizing the exhaust emissions, in particular NO sub x, of three advanced aircraft combustor concepts at a simulated, high altitude cruise condition. The three combustor designs, all members of the lean reaction, premixed family, are the Jet Induced Circulation (JIC) combustor, the Vortex Air Blast (VAB) combustor, and a catalytic combustor. They were rig tested in the form of reverse flow can combustors in the 0.127 m. (5.0 in.) size range. Various configuration modifications were applied to each of the initial JIC and VAB combustor model designs in an effort to reduce the emissions levels. The VAB combustor demonstrated a NO sub x level of 1.1 gm NO2/kg fuel with essentially 100% combustion efficiency at the simulated cruise combustor condition of 50.7 N/sq cm (5 atm), 833 K (1500 R) inlet pressure and temperature respectively and 1778 K (3200 R) outlet temperature on Jet-A1 fuel. Early tests on the catalytic combustor were unsuccessful due to a catalyst deposition problem and were discontinued in favor of the JIC and VAB tests. In addition emissions data were obtained on the JIC and VAB combustors at low combustor inlet pressure and temperatures that indicate the potential performance at engine off-design conditions.

High freestream turbulence studies on a scaled-up stator vane

NASA Astrophysics Data System (ADS)

Radomsky, Roger William, Jr.

2000-10-01

Today's gas turbine engines are operating at combustor exit temperatures far exceeding the maximum temperatures of the component alloys downstream of the combustor. These higher temperatures are necessary to increase the efficiency of the engine, and, as such, durability of the downstream components becomes an issue. The highly turbulent flowfield that exists at the exit of the combustor complicates issues further by increasing heat transfer from the hot gas to the component surface. To account for the high heat transfer rates, and provide a better prediction of the applied heat loads, detailed heat transfer and flowfield information is needed at turbulence levels representative those exiting a combustor. Flowfield measurements at high freestream turbulence levels indicated that turbulence, which was isotropic at the inlet, became highly anisotropic in the test section as a result of surface curvature and strain. Turbulent kinetic energy levels were shown to increase in the passage by as much as 131% and 31% for the 10% and 19.5% turbulence levels. Although the turbulent kinetic energy was high, the turbulence level based upon local velocity decreased quickly to levels of 3% and 6% near the suction surface for the 10% and 19.5% turbulence levels. For the pressure surface, local turbulence levels were as high as 10% and 16% for the 10% and 19.5% turbulence levels. High local turbulence levels and heat transfer augmentation were observed near the stagnation location, by as much as 50%, and along the pressure surface, by as much as 80%, where airfoil geometries have shown degradation after prolonged usage. Endwall flowfield measurements on a plane at the stagnation location showed that a horseshoe vortex developed in the juncture region of the vane at high freestream. turbulence similar to that at low freestream turbulence. Measurements near the center of the vortex indicated that the vortex was highly unsteady. In regions where strong secondary flows (horseshoe and passage vortex) were present, these vortices dominated the heat transfer and the augmentations due to high freestream turbulence were small.

Numerical Investigation of Cavity-Vane Interactions within the Ultra Combat Combustor

DTIC Science & Technology

2006-03-01

nozzle guide vane and the turbine blades are highly dependent on the temperature distribution of the combustor exit. 20 PatternFactor = T4max − T4avg...Procedure for the Calculation of Gaseous Emissions from Aircraft Turbine Engines ”. Society of Automotive Engineers , June 1996. 5. Bernard, Peter S. and...Whipkey. “Locked Vortex Afterbodies”. Journal of Aircraft , Volume 16, No. 5, May 1979. 17. Liu, Feng and William Sirignano. “ Turbojet and Turbofan

Performance Investigation on an Ultra-compact Interstage Turbine Burner with Trapped-vortex Slot Inlet

NASA Astrophysics Data System (ADS)

Zhang, Hongtao; Luo, Guangqi; Guan, Lei; Zeng, Jianchen

2017-10-01

Ultra-Compact Combustor (UCC), which is one of mainstream design concepts of Interstage Turbine Burner (ITB), has the advantages of compact structure and high combustion efficiency. A design concept of an UCC with trapped-vortex slot inlet was proposed and numerical simulation of the stability, emissions, internal flow velocity and temperature distribution was carried out. The results indicated that the UCC with trapped-vortex slot inlet could enhance the mixing of combustion mixture and the mainstream airflow, improve the combustion efficiency, outlet temperature and the uniformity of outlet temperature field.

Pollution technology program, can-annular combustor engines

NASA Technical Reports Server (NTRS)

Roberts, R.; Fiorentino, A. J.; Greene, W.

1976-01-01

A Pollution Reduction Technology Program to develop and demonstrate the combustor technology necessary to reduce exhaust emissions for aircraft engines using can-annular combustors is described. The program consisted of design, fabrication, experimental rig testing and assessment of results and was conducted in three program elements. The combustor configurations of each program element represented increasing potential for meeting the 1979 Environmental Protection Agency (EPA) emission standards, while also representing increasing complexity and difficulty of development and adaptation to an operational engine. Experimental test rig results indicate that significant reductions were made to the emission levels of the baseline JT8D-17 combustor by concepts in all three program elements. One of the Element I single-stage combustors reduced carbon monoxide to a level near, and total unburned hydrocarbons (THC) and smoke to levels below the 1979 EPA standards with little or no improvement in oxides of nitrogen. The Element II two-stage advanced Vorbix (vortex burning and mixing) concept met the standard for THC and achieved significant reductions in CO and NOx relative to the baseline. Although the Element III prevaporized-premixed concept reduced high power NOx below the Element II results, there was no improvement to the integrated EPA parameter relative to the Vorbix combustor.

Measurement and Computation of Supersonic Flow in a Lobed Diffuser-Mixer for Trapped Vortex Combustors

NASA Technical Reports Server (NTRS)

Brankovic, Andreja; Ryder, Robert C., Jr.; Hendricks, Robert C.; Liu, Nan-Suey; Gallagher, John R.; Shouse, Dale T.; Roquemore, W. Melvyn; Cooper, Clayton S.; Burrus, David L.; Hendricks, John A.

2002-01-01

The trapped vortex combustor (TVC) pioneered by Air Force Research Laboratories (AFRL) is under consideration as an alternative to conventional gas turbine combustors. The TVC has demonstrated excellent operational characteristics such as high combustion efficiency, low NO(x) emissions, effective flame stabilization, excellent high-altitude relight capability, and operation in the lean-burn or rich burn-quick quench-lean burn (RQL) modes of combustion. It also has excellent potential for lowering the engine combustor weight. This performance at low to moderate combustor mach numbers has stimulated interest in its ability to operate at higher combustion mach number, and for aerospace, this implies potentially higher flight mach numbers. To this end, a lobed diffuser-mixer that enhances the fuel-air mixing in the TVC combustor core was designed and evaluated, with special attention paid to the potential shock system entering the combustor core. For the present investigation, the lobed diffuser-mixer combustor rig is in a full annular configuration featuring sixfold symmetry among the lobes, symmetry within each lobe, and plain parallel, symmetric incident flow. During hardware cold-flow testing, significant discrepancies were found between computed and measured values for the pitot-probe-averaged static pressure profiles at the lobe exit plane. Computational fluid dynamics (CFD) simulations were initiated to determine whether the static pressure probe was causing high local flow-field disturbances in the supersonic flow exiting the diffuser-mixer and whether shock wave impingement on the pitot probe tip, pressure ports, or surface was the cause of the discrepancies. Simulations were performed with and without the pitot probe present in the modeling. A comparison of static pressure profiles without the probe showed that static pressure was off by nearly a factor of 2 over much of the radial profile, even when taking into account potential axial displacement of the probe by up to 0.25 in. (0.64 cm). Including the pitot probe in the CFD modeling and data interpretation lead to good agreement between measurement and prediction. Graphical inspection of the results showed that the shock waves impinging on the probe surface were highly nonuniform, with static pressure varying circumferentially among the pressure ports by over 10 percent in some cases. As part of the measurement methodology, such measurements should be routinely supplemented with CFD analyses that include the pitot probe as part of the flow-path geometry.

Hysteresis and precession of a swirling jet normal to a wall.

PubMed

Shtern, V; Mi, J

2004-01-01

Interaction of a swirling jet with a no-slip surface has striking features of fundamental and practical interest. Different flow states and transitions among them occur at the same conditions in combustors, vortex tubes, and tornadoes. The jet axis can undergo precession and bending in combustors; this precession enhances large-scale mixing and reduces emissions of NOx. To explore the mechanisms of these phenomena, we address conically similar swirling jets normal to a wall. In addition to the Serrin model of tornadolike flows, a new model is developed where the flow is singularity free on the axis. New analytical and numerical solutions of the Navier-Stokes equations explain occurrence of multiple states and show that hysteresis is a common feature of wall-normal vortices or swirling jets no matter where sources of motion are located. Then we study the jet stability with the aid of a new approach accounting for deceleration and nonparallelism of the base flow. An appropriate transformation of variables reduces the stability problem for this strongly nonparallel flow to a set of ordinary differential equations. A particular flow whose stability is studied in detail is a half-line vortex normal to a rigid plane-a model of a tornado and of a swirling jet issuing from a nozzle in a combustor. Helical counter-rotating disturbances appear to be first growing as Reynolds number increases. Disturbance frequency changes its sign along the neutral curve while the wave number remains positive. Short disturbance waves propagate downstream and long waves propagate upstream. This helical instability causes bending of the vortex axis and its precession-the effects observed in technological flows and in tornadoes.

Can Water-Injected Turbomachines Provide Cost-Effective Emissions and Maintenance Reductions?

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Daggett, David L.; Shouse, Dale T.; Roquemore, William M.; Brankovic, Andreja; Ryder, Robert C., Jr.

2011-01-01

An investigation has been performed to evaluate the effect of water injection on the performance of the Air Force Research Laboratory (AFRL, Wright-Patterson Air Force Base (WPAFB)) experimental trapped vortex combustor (TVC) over a range of fuel-to-air and water-to-fuel ratios. Performance is characterized by combustor exit quantities: temperature and emissions measurements using rakes, and overall pressure drop, from upstream plenum to combustor exit. Combustor visualization is performed using gray-scale and color still photographs and high-frame-rate videos. A parallel investigation evaluated the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid fueled combustor (e.g., TVC) that uses water injection for control of pollutant emissions and turbine inlet temperature. Generally, reasonable agreement is found between data and NO(x) computations. Based on a study assessing the feasibility and performance impact of using water injection on a Boeing 747-400 aircraft to reduce NO(x) emissions during takeoff, retrofitting does not appear to be cost effective; however, an operator of a newly designed engine and airframe might be able to save up to 1.0 percent in operating costs. Other challenges of water injection will be discussed.

Effects of streamwise vortex breakdown on supersonic combustion.

PubMed

Hiejima, Toshihiko

2016-04-01

This paper presents a numerical simulation study of the combustion structure of streamwise vortex breakdown at Mach number 2.48. Hydrogen fuel is injected into a combustor at sonic speed from the rear of a hypermixer strut that can generate streamwise vortices. The results show that the burning behavior is enhanced at the points of the shock waves that are incident on the vortex and therefore the vortex breakdown in the subsonic region occurs due to combustion. The breakdown domain in the mainstream is found to form a flame-holding region suited to combustion and to lead to a stable combustion field with detached flames. In this way, streamwise vortex breakdown has an essential role in combustion enhancement and the formation of flames that hold under supersonic inflow conditions. Finally, the combustion property defined here is shown to coincide with the produced-water mass flow. This property shows that the amount of combustion is saturated at equivalence ratios over 0.4, although there is a slight increase beyond 1.

Combustion Dynamic Characteristics Identification in a 9-point LDI Combustor Under Choked Outlet Boundary Conditions

NASA Technical Reports Server (NTRS)

He, Zhuohui J.; Chang, Clarence T.

2017-01-01

Combustion dynamics data were collected at the NASA Glenn Research Center's CE-5 flame tube test facility under combustor outlet choked conditions. Two 9-point Swirl-Venturi Lean Direct Injection (SV-LDI) configurations were tested in a rectangular cuboid combustor geometry. Combustion dynamic data were measured at different engine operational conditions up to inlet air pressure and temperature of 24.13 bar and 828 K, respectively. In this study, the effects of acoustic cavity resonance, precessing vortex core (PVC), and non-uniform thermal expansion on the dynamic noise spectrum are identified by comparing the dynamic data that collected at various combustor inlet conditions along with combustor geometric calculations. The results show that the acoustic cavity resonance noises were seen in the counter-rotating pilot configuration but not in the co-rotating pilot configuration. Dynamic pressure noise band at around 0.9 kHz was only detected at the P'41 location (9.8 cm after fuel injector face) but not at the P'42 location (29 cm after the fuel injector face); the amplitude of this noise band depended on the thermal expansion ratio (T4/T3). The noise band at around 1.8 kHz was found to depend on the inlet air pressure or the air density inside the combustor. The PVC frequency was not observed in these two configurations.

Vortex dynamics in type-II superconductors under strong pinning conditions

NASA Astrophysics Data System (ADS)

Thomann, A. U.; Geshkenbein, V. B.; Blatter, G.

2017-10-01

We study effects of pinning on the dynamics of a vortex lattice in a type-II superconductor in the strong-pinning situation and determine the force-velocity (or current-voltage) characteristic combining analytical and numerical methods. Our analysis deals with a small density np of defects that act with a large force fp on the vortices, thereby inducing bistable configurations that are a characteristic feature of strong pinning theory. We determine the velocity-dependent average pinning-force density 〈Fp(v ) 〉 and find that it changes on the velocity scale vp˜fp/η a03 , where η is the viscosity of vortex motion and a0 the distance between vortices. In the small pin-density limit, this velocity is much larger than the typical flow velocity vc˜Fc/η of the free vortex system at drives near the critical force density Fc=〈Fp(v =0 ) 〉 ∝npfp . As a result, we find a generic excess-force characteristic, a nearly linear force-velocity characteristic shifted by the critical force density Fc; the linear flux-flow regime is approached only at large drives. Our analysis provides a derivation of Coulomb's law of dry friction for the case of strong vortex pinning.

Mixing enhancement of reacting parallel fuel jets in a supersonic combustor

NASA Technical Reports Server (NTRS)

Drummond, J. P.

1991-01-01

Pursuant to a NASA-Langley development program for a scramjet HST propulsion system entailing the optimization of the scramjet combustor's fuel-air mixing and reaction characteristics, a numerical study has been conducted of the candidate parallel fuel injectors. Attention is given to a method for flow mixing-process and combustion-efficiency enhancement in which a supersonic circular hydrogen jet coflows with a supersonic air stream. When enhanced by a planar oblique shock, the injector configuration exhibited a substantial degree of induced vorticity in the fuel stream which increased mixing and chemical reaction rates, relative to the unshocked configuration. The resulting heat release was effective in breaking down the stable hydrogen vortex pair that had inhibited more extensive fuel-air mixing.

An experimental study of interacting swirl flows in a model gas turbine combustor

NASA Astrophysics Data System (ADS)

Vishwanath, Rahul B.; Tilak, Paidipati Mallikarjuna; Chaudhuri, Swetaprovo

2018-03-01

In this experimental work, we analyze the flow structures emerging from the mutual interaction between adjacent swirling flows at variable degrees of swirl, issued into a semi-confined chamber, as it could happen in a three cup sector of an annular premixed combustor of a modern gas turbine engine. Stereoscopic particle image velocimetry ( sPIV) is used to characterize both the non-reacting and reacting flow fields in the central diametrical (vertical) plane of the swirlers and the corresponding transverse (horizontal) planes at different heights above the swirlers. A central swirling flow with a fixed swirl vane angle is allowed to interact with its neighboring flows of varied swirl levels, with constant inlet bulk flow velocity through the central port. It is found that the presence of straight jets with zero swirl or co-rotating swirling jets with increasing swirl on both sides of the central swirling jet, significantly alters its structures. As such, an increase in the amount of swirl in the neighboring flows increases the recirculation levels in central swirling flow leading to a bubble-type vortex breakdown, not formed otherwise. It is shown with the aid of Helmholtz decomposition that the transition from conical to bubble-type breakdown is captured well by the radial momentum induced by the azimuthal vorticity. Simultaneous sPIV and OH-planar laser-induced fluorescence (PLIF) are employed to identify the influence of the neighboring jets on the reacting vortex breakdown states. Significant changes in the vortex breakdown size and structure are observed due to variation in swirl levels of the neighboring jets alongside reaction and concomitant flow dilatation.

Fundamental Understanding of Propellant/Nozzle Interaction for Rocket Nozzle Erosion Minimization Under Very High Pressure Conditions

DTIC Science & Technology

2005-08-31

conditions; with X-ray radiography for erosion rate measurements. A vortex combustor was also designed to simulate propellant product species and to...DATES COVERED Interim Progress Report, August 1, 2004 to July 31, 2005 4. TITLE AND SUBTITLE Fundamental Understanding of Propellant /Nozzle...nozzle erosion by solid- propellant combustion products. Several processes can affect the nozzle erosion rate at high pressure and temperature

Advanced coal-fueled industrial cogeneration gas turbine system particle removal system development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephenson, M.

1994-03-01

Solar Turbines developed a direct coal-fueled turbine system (DCFT) and tested each component in subscale facilities and the combustion system was tested at full-scale. The combustion system was comprised of a two-stage slagging combustor with an impact separator between the two combustors. Greater than 90 percent of the native ash in the coal was removed as liquid slag with this system. In the first combustor, coal water slurry mixture (CWM) was injected into a combustion chamber which was operated loan to suppress NO{sub x} formation. The slurry was introduced through four fuel injectors that created a toroidal vortex because ofmore » the combustor geometry and angle of orientation of the injectors. The liquid slag that was formed was directed downward toward an impaction plate made of a refractory material. Sixty to seventy percent of the coal-borne ash was collected in this fashion. An impact separator was used to remove additional slag that had escaped the primary combustor. The combined particulate collection efficiency from both combustors was above 95 percent. Unfortunately, a great deal of the original sulfur from the coal still remained in the gas stream and needed to be separated. To accomplish this, dolomite or hydrated lime were injected in the secondary combustor to react with the sulfur dioxide and form calcium sulfite and sulfates. This solution for the sulfur problem increased the dust concentrations to as much as 6000 ppmw. A downstream particulate control system was required, and one that could operate at 150 psia, 1850-1900{degrees}F and with low pressure drop. Solar designed and tested a particulate rejection system to remove essentially all particulate from the high temperature, high pressure gas stream. A thorough research and development program was aimed at identifying candidate technologies and testing them with Solar`s coal-fired system. This topical report summarizes these activities over a period beginning in 1987 and ending in 1992.« less

An Experimental Study of Swirling Flows as Applied to Annular Combustors

NASA Technical Reports Server (NTRS)

Seal, Michael Damian, II

1997-01-01

This thesis presents an experimental study of swirling flows with direct applications to gas turbine combustors. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models. In order to determine the characteristics of swirling flows the concentration fields of a round, swirling jet were analyzed for varying amount of swirl. The experimental method used was a light scattering concentration measurement technique known as marker nephelometry. Results indicated the formation of a zone of recirculating fluid for swirl ratios (rotational speed x jet radius over mass average axial velocity) above a certain critical value. The size of this recirculation zone, as well as the spread angle of the jet, was found to increase with increase in the amount of applied swirl. The annular combustor model flowfield simulated the cold-flow characteristics of typical current annular combustors: swirl, recirculation, primary air cross jets and high levels of turbulence. The measurements in the combustor model made by the Laser Doppler Velocimetry technique, allowed the evaluation of the mean and rms velocities in the three coordinate directions, one Reynold's shear stress component and the turbulence kinetic energy: The primary cross jets were found to have a very strong effect on both the mean and turbulence flowfields. These cross jets, along with a large step change in area and wall jet inlet flow pattern, reduced the overall swirl in the test section to negligible levels. The formation of the strong recirculation zone is due mainly to the cross jets and the large step change in area. The cross jets were also found to drive a four-celled vortex-type motion (parallel to the combustor longitudinal axis) near the cross jet injection plane.

Modeling and Simulation of Swirl Stabilized Turbulent Non-Premixed Flames

NASA Astrophysics Data System (ADS)

Badillo-Rios, Salvador; Karagozian, Ann

2017-11-01

Flame stabilization is an important design criterion for many combustion chambers, especially at lean conditions and/or high power output, where insufficient stabilization can result in dangerous oscillations and noisy or damaged combustors. At high flow rates, swirling flow can offer a suitable stabilization mechanism, although understanding the dynamics of swirl-stabilized turbulent flames remains a significant challenge. Utilizing the General Equation and Mesh Solver (GEMS) code, which solves the Navier-Stokes equations along with the energy equation and five species equations, 2D axisymmetric and full 3D parametric studies and simulations are performed to guide the design and development of an experimental swirl combustor configuration and to study the effects of swirl on statistically stationary combustion. Results show that as the momentum of air is directed into the inner air inlet rather than the outer inlet of the swirl combustor, the central recirculating region becomes stronger and more unsteady, improving mixing and burning efficiency in that region. A high temperature region is found to occur as a result of burning of the trapped fuel from the central toroidal vortex. The effects of other parameters on flowfield and flame-stabilization dynamics are explored. Supported by ERC, Inc. (PS150006) and AFOSR (Dr. Chiping Li).

Flow and heat transfer experiments in the turbine airfoil/endwall region

NASA Astrophysics Data System (ADS)

Chung, Jin Taek

An experimental investigation of the three-dimensional flow and heat transfer near the junction between the endwall and suction wall of a gas turbine was performed. A large-scale, two-half-blade facility which simulates a turbine cascade was introduced. The simulator consists of two large half-blade sections, one wall simulating the pressure surface and the other wall simulating the suction surface. The advantage of this configuration is that the features of the secondary flow are large, because of the relatively large test section, and the flow is easily accessible with probes. Qualification of this simulator was by comparison to a multi-blade cascade flow. Various flow visualization techniques--oil and lampblack, ink and oil of wintergeeen, a single tuft probe, and a tuft grid--were employed to confirm that the important features of the cascade flow were replicated in this simulator. The triangular region on the suction surface, which was affected by the passage vortex, and the endwall secondary crossflow were observed by shear stress visualization and the liquid crystal measurement techniques. In order to investigate the effects of the turbulence level on the secondary flow in a turbine passage, a turbulence generator, designed to reproduce the characteristics of a combustor exit flow, was built. The generator was designed not only to generate a high turbulence level but to produce three main features of a combustor exit flow. The generator produced a turbulence intensity level of about 10 percent and an integral length scale of 5 centimeters. It was observed that the endwall secondary flow, including the passage vortex, is not significantly influenced by freestream turbulence levels up to 10 percent. A flow management technique using a boundary layer fence designed to reduce some harmful effects of secondary flow in the endwall region of a turbine passage was introduced. The boundary layer fence is effective in changing the passage of the vortex and reducing the influence of the vortex near the suction wall. The fence was even more effective in reducing secondary flows for high levels of freestream turbulence (approximately 10 percent).

Lagrangian coherent structures during combustion instability in a premixed-flame backward-step combustor.

PubMed

Sampath, Ramgopal; Mathur, Manikandan; Chakravarthy, Satyanarayanan R

2016-12-01

This paper quantitatively examines the occurrence of large-scale coherent structures in the flow field during combustion instability in comparison with the flow-combustion-acoustic system when it is stable. For this purpose, the features in the recirculation zone of the confined flow past a backward-facing step are studied in terms of Lagrangian coherent structures. The experiments are conducted at a Reynolds number of 18600 and an equivalence ratio of 0.9 of the premixed fuel-air mixture for two combustor lengths, the long duct corresponding to instability and the short one to the stable case. Simultaneous measurements of the velocity field using time-resolved particle image velocimetry and the CH^{*} chemiluminescence of the flame along with pressure time traces are obtained. The extracted ridges of the finite-time Lyapunov exponent (FTLE) fields delineate dynamically distinct regions of the flow field. The presence of large-scale vortical structures and their modulation over different time instants are well captured by the FTLE ridges for the long combustor where high-amplitude acoustic oscillations are self-excited. In contrast, small-scale vortices signifying Kelvin-Helmholtz instability are observed in the short duct case. Saddle-type flow features are found to separate the distinct flow structures for both combustor lengths. The FTLE ridges are found to align with the flame boundaries in the upstream regions, whereas farther downstream, the alignment is weaker due to dilatation of the flow by the flame's heat release. Specifically, the FTLE ridges encompass the flame curl-up for both the combustor lengths, and thus act as the surrogate flame boundaries. The flame is found to propagate upstream from an earlier vortex roll-up to a newer one along the backward-time FTLE ridge connecting the two structures.

Improved pressure-velocity coupling algorithm based on minimization of global residual norm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatwani, A.U.; Turan, A.

1991-01-01

In this paper an improved pressure velocity coupling algorithm is proposed based on the minimization of the global residual norm. The procedure is applied to SIMPLE and SIMPLEC algorithms to automatically select the pressure underrelaxation factor to minimize the global residual norm at each iteration level. Test computations for three-dimensional turbulent, isothermal flow is a toroidal vortex combustor indicate that velocity underrelaxation factors as high as 0.7 can be used to obtain a converged solution in 300 iterations.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Technical Reports Server (NTRS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-01-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Augmentation of Stagnation Region Heat Transfer Due to Turbulence From a DLN Can Combustor

NASA Technical Reports Server (NTRS)

VanFossen, G. James; Bunker, Ronald S.

2000-01-01

Heat transfer measurements have been made in the stagnation region of a flat plate with a circular leading edge. Electrically heated aluminum strips placed symmetrically about the leading edge stagnation region were used to measure spanwise averaged heat transfer coefficients. The maximum Reynolds number obtained, based on leading edge diameter, was about 100,000. The model was immersed in the flow field downstream of an approximately half scale model of a can-type combustor from a low NO(x), ground based power-generating turbine. The tests were conducted with room temperature air; no fuel was added. Room air flowed into the combustor through six vane type fuel/air swirlers. The combustor can contained no dilution holes. The fuel/air swirlers all swirled the incoming airflow in a counter clockwise direction (facing downstream). A 5-hole probe flow field survey in the plane of the model stagnation point showed the flow was one big vortex with flow angles up to 36' at the outer edges of the rectangular test section. Hot wire measurements showed test section flow had very high levels of turbulence, around 28.5 percent, and had a relatively large axial-length scale-to-leading edge diameter ratio of 0.5. X-wire measurements showed the turbulence to be nearly isotropic. Stagnation heat transfer augmentation over laminar levels was around 77 percent and was about 14 percent higher than predicted by a previously developed correlation for isotropic grid generated turbulence.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-07-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-06-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

High-speed laser diagnostics for the study of flame dynamics in a lean premixed gas turbine model combustor

NASA Astrophysics Data System (ADS)

Boxx, Isaac; Arndt, Christoph M.; Carter, Campbell D.; Meier, Wolfgang

2012-03-01

A series of measurements was taken on two technically premixed, swirl-stabilized methane-air flames (at overall equivalence ratios of ϕ = 0.73 and 0.83) in an optically accessible gas turbine model combustor. The primary diagnostics used were combined planar laser-induced fluorescence of the OH radical and stereoscopic particle image velocimetry (PIV) with simultaneous repetition rates of 10 kHz and a measurement duration of 0.8 s. Also measured were acoustic pulsations and OH chemiluminescence. Analysis revealed strong local periodicity in the thermoacoustically self-excited (or ` noisy') flame (ϕ = 0.73) in the regions of the flow corresponding to the inner shear layer and the jet-inflow. This periodicity appears to be the result of a helical precessing vortex core (PVC) present in that region of the combustor. The PVC has a precession frequency double (at 570 Hz) that of the thermo-acoustic pulsation (at 288 Hz). A comparison of the various data sets and analysis techniques applied to each flame suggests a strong coupling between the PVC and the thermo-acoustic pulsation in the noisy flame. Measurements of the stable (` quiet') flame (ϕ = 0.83) revealed a global fluctuation in both velocity and heat-release around 364 Hz, but no clear evidence of a PVC.

Low NO.sub.x multistage combustor

DOEpatents

Becker, Frederick E.; Breault, Ronald W.; Litka, Anthony F.; McClaine, Andrew W.; Shukla, Kailash

2000-01-01

A high efficiency, Vortex Inertial Staged Air (VIStA) combustor provides ultra-low NO.sub.X production of about 20 ppmvd or less with CO emissions of less than 50 ppmvd, both at 3% O.sub.2. Prompt NO.sub.X production is reduced by partially reforming the fuel in a first combustion stage to CO and H.sub.2. This is achieved in the first stage by operating with a fuel rich mixture, and by recirculating partially oxidized combustion products, with control over stoichiometry, recirculation rate and residence time. Thermal NO.sub.X production is reduced in the first stage by reducing the occurrence of high temperature combustion gas regions. This is achieved by providing the first stage burner with a thoroughly pre-mixed fuel/oxidant composition, and by recirculating part of the combustion products to further mix the gases and provide a more uniform temperature in the first stage. In a second stage combustor thermal NO.sub.X production is controlled by inducing a large flow of flue gas recirculation in the second stage combustion zone to minimize the ultimate temperature of the flame. One or both of the first and second stage burners can be cooled to further reduce the combustion temperature and to improve the recirculation efficiency. Both of these factors tend to reduce production of NO.sub.X.

Dynamic behavior of turbulent flow in a widely-spaced co-axial jet diffusion flame combustor

NASA Astrophysics Data System (ADS)

Sturgess, G. J.; Syed, S. A.

1983-01-01

Reacting flows in a bluff-body stabilized diffusion flame research combustor operated by the Wright Aeronautical Propulsion Laboratory exhibit the presence of coherent structures where, because of dynamic behavior the flame consists of large, discrete flame eddies passing down the combustion tunnel separated in time by axial regions where no flame is visible. It is proposed that the formation of these structures and their subsequent behavior are the result of vortex-shedding from the flameholder and, in the main, interaction with the organ-pipe natural frequencies of the long combustion tunnel. A simulation of the flow is made based on a finite difference solution of the time-average, steady state, elliptic form of the Reynolds equations using the two-equation turbulence model and a 'mixed is burned' combustion model for closure. The simulation of the eddies and, in conjunction with a universal Strouhal number-Reynolds number correlation, provides successful prediction of the flame frequencies.

Experimental and Numerical Investigation of Vortical Structures in Lean Premixed Swirl-Stabilized Combustion

NASA Astrophysics Data System (ADS)

Taamallah, Soufien; Chakroun, Nadim; Shanbhogue, Santosh; Kewlani, Gaurav; Ghoniem, Ahmed

2015-11-01

A combined experimental and LES investigation is performed to identify the origin of major flow dynamics and vortical structures in a model gas turbine's swirl-stabilized turbulent combustor. Swirling flows in combustion lead to the formation of complex flow dynamics and vortical structures that can interact with flames and influence its stabilization. Our experimental results for non-reacting flow show the existence of large scale precession motion. The precessing vortex core (PVC) dynamics disappears with combustion but only above a threshold of equivalence ratio. In addition, large scale vortices along the inner shear layer (ISL) are observed. These structures interact with the ISL stabilized flame and contribute to its wrinkling. Next, the LES setup is validated against the flow field's low-order statistics and point temperature measurement in relevant areas of the chamber. Finally, we show that LES is capable of predicting the precession motion as well as the ISL vortices in the reacting case: we find that ISL vortices originate from a vortex core that is formed right downstream of the swirler's centerbody. The vortex core has a conical spiral shape resembling a corkscrew that interacts - as it winds out - with the flame when it reaches the ISL.

Near-zero emissions combustor system for syngas and biofuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yongho, Kim; Rosocha, Louis

2010-01-01

A multi-institutional plasma combustion team was awarded a research project from the DOE/NNSA GIPP (Global Initiative for Prolifereation Prevention) office. The Institute of High Current Electronics (Tomsk, Russia); Leonardo Technologies, Inc. (an American-based industrial partner), in conjunction with the Los Alamos National Laboratory are participating in the project to develop novel plasma assisted combustion technologies. The purpose of this project is to develop prototypes of marketable systems for more stable and cleaner combustion of syngas/biofuels and to demonstrate that this technology can be used for a variety of combustion applications - with a major focus on contemporary gas turbines. Inmore » this paper, an overview of the project, along with descriptions of the plasma-based combustors and associated power supplies will be presented. Worldwide, it is recognized that a variety of combustion fuels will be required to meet the needs for supplying gas-turbine engines (electricity generation, propulsion), internal combustion engines (propulsion, transportation), and burners (heat and electricity generation) in the 21st Century. Biofuels and biofuel blends have already been applied to these needs, but experience difficulties in modifications to combustion processes and combustor design and the need for flame stabilization techniques to address current and future environmental and energy-efficiency challenges. In addition, municipal solid waste (MSW) has shown promise as a feedstock for heat and/or electricity-generating plants. However, current combustion techniques that use such fuels have problems with achieving environmentally-acceptable air/exhaust emissions and can also benefit from increased combustion efficiency. This project involves a novel technology (a form of plasma-assisted combustion) that can address the above issues. Plasma-assisted combustion (PAC) is a growing field that is receiving worldwide attention at present. The project is focused on research necessary to develop a novel, high-efficiency, low-emissions (near-zero, or as low as reasonably achievable), advanced combustion technology for electricity and heat production from biofuels and fuels derived from MSW. For any type of combustion technology, including the advanced technology of this project, two problems of special interest must be addressed: developing and optimizing the combustion chambers and the systems for igniting and sustaining the fuel-burning process. For MSW in particular, there are new challenges over gaseous or liquid fuels because solid fuels must be ground into fine particulates ({approx} 10 {micro}m diameter), fed into the advanced combustor, and combusted under plasma-assisted conditions that are quite different than gaseous or liquid fuels. The principal idea of the combustion chamber design is to use so-called reverse vortex gas flow, which allows efficient cooling of the chamber wall and flame stabilization in the central area of the combustor (Tornado chamber). Considerable progress has been made in design ing an advanced, reverse vortex flow combustion chamber for biofuels, although it was not tested on biofuels and a system that could be fully commercialized has never been completed.« less

Assessment of swirl spray interaction in lab scale combustor using time-resolved measurements

NASA Astrophysics Data System (ADS)

Rajamanickam, Kuppuraj; Jain, Manish; Basu, Saptarshi

2017-11-01

Liquid fuel injection in highly turbulent swirling flows becomes common practice in gas turbine combustors to improve the flame stabilization. It is well known that the vortex bubble breakdown (VBB) phenomenon in strong swirling jets exhibits complicated flow structures in the spatial domain. In this study, the interaction of hollow cone liquid sheet with such coaxial swirling flow field has been studied experimentally using time-resolved measurements. In particular, much attention is focused towards the near field breakup mechanism (i.e. primary atomization) of liquid sheet. The detailed swirling gas flow field characterization is carried out using time-resolved PIV ( 3.5 kHz). Furthermore, the complicated breakup mechanisms and interaction of the liquid sheet are imaged with the help of high-speed shadow imaging system. Subsequently, proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) is implemented over the instantaneous data sets to retrieve the modal information associated with the interaction dynamics. This helps to delineate more quantitative nature of interaction process between the liquid sheet and swirling gas phase flow field.

Tomographic reconstruction of heat release rate perturbations induced by helical modes in turbulent swirl flames

NASA Astrophysics Data System (ADS)

Moeck, Jonas P.; Bourgouin, Jean-François; Durox, Daniel; Schuller, Thierry; Candel, Sébastien

2013-04-01

Swirl flows with vortex breakdown are widely used in industrial combustion systems for flame stabilization. This type of flow is known to sustain a hydrodynamic instability with a rotating helical structure, one common manifestation of it being the precessing vortex core. The role of this unsteady flow mode in combustion is not well understood, and its interaction with combustion instabilities and flame stabilization remains unclear. It is therefore important to assess the structure of the perturbation in the flame that is induced by this helical mode. Based on principles of tomographic reconstruction, a method is presented to determine the 3-D distribution of the heat release rate perturbation associated with the helical mode. Since this flow instability is rotating, a phase-resolved sequence of projection images of light emitted from the flame is identical to the Radon transform of the light intensity distribution in the combustor volume and thus can be used for tomographic reconstruction. This is achieved with one stationary camera only, a vast reduction in experimental and hardware requirements compared to a multi-camera setup or camera repositioning, which is typically required for tomographic reconstruction. Different approaches to extract the coherent part of the oscillation from the images are discussed. Two novel tomographic reconstruction algorithms specifically tailored to the structure of the heat release rate perturbations related to the helical mode are derived. The reconstruction techniques are first applied to an artificial field to illustrate the accuracy. High-speed imaging data acquired in a turbulent swirl-stabilized combustor setup with strong helical mode oscillations are then used to reconstruct the 3-D structure of the associated perturbation in the flame.

Laser-based investigations in gas turbine model combustors

NASA Astrophysics Data System (ADS)

Meier, W.; Boxx, I.; Stöhr, M.; Carter, C. D.

2010-10-01

Dynamic processes in gas turbine (GT) combustors play a key role in flame stabilization and extinction, combustion instabilities and pollutant formation, and present a challenge for experimental as well as numerical investigations. These phenomena were investigated in two gas turbine model combustors for premixed and partially premixed CH4/air swirl flames at atmospheric pressure. Optical access through large quartz windows enabled the application of laser Raman scattering, planar laser-induced fluorescence (PLIF) of OH, particle image velocimetry (PIV) at repetition rates up to 10 kHz and the simultaneous application of OH PLIF and PIV at a repetition rate of 5 kHz. Effects of unmixedness and reaction progress in lean premixed GT flames were revealed and quantified by Raman scattering. In a thermo-acoustically unstable flame, the cyclic variation in mixture fraction and its role for the feedback mechanism of the instability are addressed. In a partially premixed oscillating swirl flame, the cyclic variations of the heat release and the flow field were characterized by chemiluminescence imaging and PIV, respectively. Using phase-correlated Raman scattering measurements, significant phase-dependent variations of the mixture fraction and fuel distributions were revealed. The flame structures and the shape of the reaction zones were visualized by planar imaging of OH distribution. The simultaneous OH PLIF/PIV high-speed measurements revealed the time history of the flow field-flame interaction and demonstrated the development of a local flame extinction event. Further, the influence of a precessing vortex core on the flame topology and its dynamics is discussed.

Study of the mechanisms for flame stabilization in gas turbine model combustors using kHz laser diagnostics

NASA Astrophysics Data System (ADS)

Boxx, Isaac; Carter, Campbell D.; Stöhr, Michael; Meier, Wolfgang

2013-05-01

An image-processing routine was developed to autonomously identify and statistically characterize flame-kernel events, wherein OH (from a planar laser-induced fluorescence, PLIF, measurement) appears in the probe region away from the contiguous OH layer. This routine was applied to datasets from two gas turbine model combustors that consist of thousands of joint OH-velocity images from kHz framerate OH-PLIF and particle image velocimetry (PIV). Phase sorting of the kernel centroids with respect to the dominant fluid-dynamic structure of the combustors (a helical precessing vortex core, PVC) indicates through-plane transport of reacting fluid best explains their sudden appearance in the PLIF images. The concentration of flame-kernel events around the periphery of the mean location of the PVC indicates they are likely the result of wrinkling and/or breakup of the primary flame sheet associated with the passage of the PVC as it circumscribes the burner centerline. The prevailing through-plane velocity of the swirling flow-field transports these fragments into the imaging plane of the OH-PLIF system. The lack of flame-kernel events near the center of the PVC (in which there is lower strain and longer fluid-dynamic residence times) indicates that auto-ignition is not a likely explanation for these flame kernels in a majority of cases. The lack of flame-kernel centroid variation in one flame in which there is no PVC further supports this explanation.

Fast and slow active control of combustion instabilities in liquid-fueled combustors

NASA Astrophysics Data System (ADS)

Lee, Jae-Yeon

This thesis describes an experimental investigation of two different novel active control approaches that are employed to suppress combustion instabilities in liquid-fueled combustors. A "fast" active controller requires continuous modulation of the fuel injection rate at the frequency of the instability with proper phase and gain. Use of developed optical tools reveals that the "fast" active control system suppresses the instability by changing the nearly flat distribution of the phase between pressure and heat release oscillations to a gradually varying phase distribution, thus dividing the combustion zone into regions that alternately damp and drive combustor oscillations. The effects of these driving/damping regions tend to counter one another, which result in significant damping of the unstable oscillations. In contrast, a "slow" active controller operates at a rate commensurate with that at which operating conditions change during combustor operation. Consequently, "slow" controllers need infrequent activation in response to changes in engine operating conditions to assure stable operation at all times. Using two types of fuel injectors that can produce large controllable variation of fuel spray properties, it is shown that by changing the spray characteristics it is possible to significantly damp combustion instabilities. Similar to the aforementioned result of the "fast" active control study, "slow" change of the fuel spray properties also modifies the nearly flat phase distribution during unstable operation to a gradually varying phase distribution, resulting in combustor "stabilization". Furthermore, deconvolutions of CH*-chemiluminescence images reveal the presence of vortex-flame interaction during unstable operation. Strong driving of instabilities occurs where the mean axial velocity of the flow is approximately zero, a short distance downstream of the flame holder where a significant fraction of the fuel burns in phase with the pressure oscillations. It is shown that the "fast" and "slow" active control approaches suppress combustion instabilities in a different manner. Nevertheless, the both control approaches successfully suppress combustion instabilities by modifying the temporal and spatial behavior of the combustion process heat release that is responsible for driving the instability.

Modeling and simulation of combustion dynamics in lean-premixed swirl-stabilized gas-turbine engines

NASA Astrophysics Data System (ADS)

Huang, Ying

This research focuses on the modeling and simulation of combustion dynamics in lean-premixed gas-turbines engines. The primary objectives are: (1) to establish an efficient and accurate numerical framework for the treatment of unsteady flame dynamics; and (2) to investigate the parameters and mechanisms responsible for driving flow oscillations in a lean-premixed gas-turbine combustor. The energy transfer mechanisms among mean flow motions, periodic motions and background turbulent motions in turbulent reacting flow are first explored using a triple decomposition technique. Then a comprehensive numerical study of the combustion dynamics in a lean-premixed swirl-stabilized combustor is performed. The analysis treats the conservation equations in three dimensions and takes into account finite-rate chemical reactions and variable thermophysical properties. Turbulence closure is achieved using a large-eddy-simulation (LES) technique. The compressible-flow version of the Smagorinsky model is employed to describe subgrid-scale turbulent motions and their effect on large-scale structures. A level-set flamelet library approach is used to simulate premixed turbulent combustion. In this approach, the mean flame location is modeled using a level-set G-equation, where G is defined as a distance function. Thermophysical properties are obtained using a presumed probability density function (PDF) along with a laminar flamelet library. The governing equations and the associated boundary conditions are solved by means of a four-step Runge-Kutta scheme along with the implementation of the message passing interface (MPI) parallel computing architecture. The analysis allows for a detailed investigation into the interaction between turbulent flow motions and oscillatory combustion of a swirl-stabilized injector. Results show good agreement with an analytical solution and experimental data in terms of acoustic properties and flame evolution. A study of flame bifurcation from a stable state to an unstable state indicates that the inlet flow temperature and equivalence ratio are the two most important variables determining the stability characteristics of the combustor. Under unstable operating conditions, several physical processes responsible for driving combustion instabilities in the chamber have been identified and quantified. These processes include vortex shedding and acoustic interaction, coupling between the flame evolution and local flow oscillations, vortex and flame interaction and coupling between heat release and acoustic motions. The effects of inlet swirl number on the flow development and flame dynamics in the chamber are also carefully studied. In the last part of this thesis, an analytical model is developed using triple decomposition techniques to model the combustion response of turbulent premixed flames to acoustic oscillations.

Propagation of a premixed flame in a divided-chamber combustor

NASA Technical Reports Server (NTRS)

Cattolica, R. J.; Barr, P. K.; Mansour, N. N.

1989-01-01

Experimental observations on the propagation of lean premixed ethylene-air flames in a divided-chamber combustion vessel have been compared with the results of numerical simulations based on a flame sheet-vortex dynamics model in axisymmetric coordinates. Flame speeds were found to increase from 10-24 cm/s as the equivalence ratio was varied from 0.5-0.65 in the experiments. Using the associated increase in gas velocity with equivalence ratio, the estimated Reynolds number in the experiment was changed from 1870 to 8090. Good agreement between experimental and theoretical results was obtained for the prechamber flame propagation rates and for the spatial and temporal development of the flame in the main combustion chamber at the lowest Reynolds number.

Gas turbine engine

DOEpatents

Lawlor, Shawn P.; Roberts, II, William Byron

2016-03-08

A gas turbine engine with a compressor rotor having compressor impulse blades that delivers gas at supersonic conditions to a stator. The stator includes a one or more aerodynamic ducts that each have a converging portion and a diverging portion for deceleration of the selected gas to subsonic conditions and to deliver a high pressure oxidant containing gas to flameholders. The flameholders may be provided as trapped vortex combustors, for combustion of a fuel to produce hot pressurized combustion gases. The hot pressurized combustion gases are choked before passing out of an aerodynamic duct to a turbine. Work is recovered in a turbine by expanding the combustion gases through impulse blades. By balancing the axial loading on compressor impulse blades and turbine impulse blades, asymmetrical thrust is minimized or avoided.

Vitamin C Nutrition in Cattle

PubMed Central

Matsui, T.

2012-01-01

Domestic animals, including ruminants, can synthesize vitamin C (VC) in their liver; as such, the dietary requirement for VC has not been confirmed in these animals. The adequacy of VC has been evaluated by quantifying VC levels in plasma, but the reported values in bovine plasma have been widely variable. Plasma VC concentration is decreased by heat stress, hepatic lesions, fattening, and infectious diseases such as mastitis in cattle. Therefore, VC supplementation is potentially beneficial for cattle with low plasma VC concentration. This review discusses the methods for determination of plasma VC concentration in cattle, VC nutrition, and the efficacy of VC supplementation in calves, dairy cattle, and beef cattle. Additionally I propose a reference range for plasma VC concentration in Japanese Black cattle. PMID:25049602

The effect of vortex merging and non-merging on the transfer of modal turbulent kinetic energy content

NASA Astrophysics Data System (ADS)

Ground, Cody; Vergine, Fabrizio; Maddalena, Luca

2016-08-01

A defining feature of the turbulent free shear layer is that its growth is hindered by compressibility effects, thus limiting its potential to sufficiently mix the injected fuel and surrounding airstream at the supersonic Mach numbers intrinsic to the combustor of air-breathing hypersonic vehicles. The introduction of streamwise vorticity is often proposed in an attempt to counteract these undesired effects. This fact makes the strategy of introducing multiple streamwise vortices and imposing upon them certain modes of mutual interaction in order to potentially enhance mixing an intriguing concept. However, many underlying fundamental characteristics of the flowfields in the presence such interactions are not yet well understood; therefore, the fundamental physics of these flowfields should be independently investigated before the explicit mixing performance is characterized. In this work, experimental measurements are taken with the stereoscopic particle image velocimetry technique on two specifically targeted modes of vortex interaction—the merging and non-merging of two corotating vortices. The fluctuating velocity fields are analyzed utilizing the proper orthogonal decomposition (POD) in order to identify the content, organization, and distribution of the modal turbulent kinetic energy content of the fluctuating velocity eigenmodes. The effects of the two modes of vortex interaction are revealed by the POD analysis which shows distinct differences in the modal features of the two cases. When comparing the low-order eigenmodes of the two cases, the size of the structures contained within the first ten modes is seen to increase as the flow progresses downstream for the merging case, whereas the opposite is true for the non-merging case. Additionally, the relative modal energy contribution of the first ten eigenmodes increases as the vortices evolve downstream for the merging case, whereas in the non-merging case the relative modal energy contribution decreases. The POD results show that the vortex merging process reorients and redistributes the relative turbulent kinetic energy content toward the larger-scale structures within the low-order POD eigenmodes. This result suggests that by specifically designing the vortex generation system to impose preselected modes of vortex interaction upon the flow it is possible to exert some form of control over the downstream evolution and distribution of the global and modal turbulent kinetic energy content.

Transcript Profile of Flowering Regulatory Genes in VcFT-Overexpressing Blueberry Plants

PubMed Central

Walworth, Aaron E.; Chai, Benli; Song, Guo-qing

2016-01-01

In order to identify genetic components in flowering pathways of highbush blueberry (Vaccinium corymbosum L.), a transcriptome reference composed of 254,396 transcripts and 179,853 gene contigs was developed by assembly of 72.7 million reads using Trinity. Using this transcriptome reference and a query of flowering pathway genes of herbaceous plants, we identified potential flowering pathway genes/transcripts of blueberry. Transcriptome analysis of flowering pathway genes was then conducted on leaf tissue samples of transgenic blueberry cv. Aurora (‘VcFT-Aurora’), which overexpresses a blueberry FLOWERING LOCUS T-like gene (VcFT). Sixty-one blueberry transcripts of 40 genes showed high similarities to 33 known flowering-related genes of herbaceous plants, of which 17 down-regulated and 16 up-regulated genes were identified in ‘VcFT-Aurora’. All down-regulated genes encoded transcription factors/enzymes upstream in the signaling pathway containing VcFT. A blueberry CONSTANS-LIKE 5-like (VcCOL5) gene was down-regulated and associated with five other differentially expressed (DE) genes in the photoperiod-mediated flowering pathway. Three down-regulated genes, i.e., a MADS-AFFECTING FLOWERING 2-like gene (VcMAF2), a MADS-AFFECTING FLOWERING 5-like gene (VcMAF5), and a VERNALIZATION1-like gene (VcVRN1), may function as integrators in place of FLOWERING LOCUS C (FLC) in the vernalization pathway. Because no CONSTAN1-like or FLOWERING LOCUS C-like genes were found in blueberry, VcCOL5 and VcMAF2/VcMAF5 or VRN1 might be the major integrator(s) in the photoperiod- and vernalization-mediated flowering pathway, respectively. The major down-stream genes of VcFT, i.e., SUPPRESSOR of Overexpression of Constans 1-like (VcSOC1), LEAFY-like (VcLFY), APETALA1-like (VcAP1), CAULIFLOWER 1-like (VcCAL1), and FRUITFULL-like (VcFUL) genes were present and showed high similarity to their orthologues in herbaceous plants. Moreover, overexpression of VcFT promoted expression of all of these VcFT downstream genes. These results suggest that VcFT’s down-stream genes appear conserved in blueberry. PMID:27271296

Transcript Profile of Flowering Regulatory Genes in VcFT-Overexpressing Blueberry Plants.

PubMed

Walworth, Aaron E; Chai, Benli; Song, Guo-Qing

2016-01-01

In order to identify genetic components in flowering pathways of highbush blueberry (Vaccinium corymbosum L.), a transcriptome reference composed of 254,396 transcripts and 179,853 gene contigs was developed by assembly of 72.7 million reads using Trinity. Using this transcriptome reference and a query of flowering pathway genes of herbaceous plants, we identified potential flowering pathway genes/transcripts of blueberry. Transcriptome analysis of flowering pathway genes was then conducted on leaf tissue samples of transgenic blueberry cv. Aurora ('VcFT-Aurora'), which overexpresses a blueberry FLOWERING LOCUS T-like gene (VcFT). Sixty-one blueberry transcripts of 40 genes showed high similarities to 33 known flowering-related genes of herbaceous plants, of which 17 down-regulated and 16 up-regulated genes were identified in 'VcFT-Aurora'. All down-regulated genes encoded transcription factors/enzymes upstream in the signaling pathway containing VcFT. A blueberry CONSTANS-LIKE 5-like (VcCOL5) gene was down-regulated and associated with five other differentially expressed (DE) genes in the photoperiod-mediated flowering pathway. Three down-regulated genes, i.e., a MADS-AFFECTING FLOWERING 2-like gene (VcMAF2), a MADS-AFFECTING FLOWERING 5-like gene (VcMAF5), and a VERNALIZATION1-like gene (VcVRN1), may function as integrators in place of FLOWERING LOCUS C (FLC) in the vernalization pathway. Because no CONSTAN1-like or FLOWERING LOCUS C-like genes were found in blueberry, VcCOL5 and VcMAF2/VcMAF5 or VRN1 might be the major integrator(s) in the photoperiod- and vernalization-mediated flowering pathway, respectively. The major down-stream genes of VcFT, i.e., SUPPRESSOR of Overexpression of Constans 1-like (VcSOC1), LEAFY-like (VcLFY), APETALA1-like (VcAP1), CAULIFLOWER 1-like (VcCAL1), and FRUITFULL-like (VcFUL) genes were present and showed high similarity to their orthologues in herbaceous plants. Moreover, overexpression of VcFT promoted expression of all of these VcFT downstream genes. These results suggest that VcFT's down-stream genes appear conserved in blueberry.

Transcriptome Analysis of Skin from SMP30/GNL Knockout Mice Reveals the Effect of Ascorbic Acid Deficiency on Skin and Hair.

PubMed

Wakame, Koji; Komatsu, Ken-Ichi; Nakata, Akifumi; Sato, Keisuke; Takaguri, Akira; Masutomi, Hirofumi; Nagashima, Takayuki; Uchiyama, Hironobu

2017-01-01

Senescence marker protein-30/gluconolactonase knockout mice (SMP-30/GNL-KO) are a very useful model for clarifying the involvement of vitamin C (VC) in aging-related diseases. In this study, the effects of VC deficiency on skin and hair growth were investigated using SMP-30/GNL-KO mice by RNA sequencing. SMP-30/GNL-KO mice were given water containing 1.5 g/l VC until up to 8 weeks after birth to maintain a VC concentration in their organs and plasma equivalent to that in wild-type mice. The mice were then divided into two groups: a VC(+) group, where VC was administered, and a VC(-) group, where VC was not administered. Skin samples were collected at 4 and 8 weeks after the treatment. RNA was extracted from each skin sample, followed by cDNA synthesis and RNA-seq. In addition, hair growth was compared between the VC(-) and VC(+) groups after shaving. Skin samples were collected from the shaved area for histological examination by hematoxylin & eosin (HE) staining. RNA-seq revealed that there were 1,736 (FDR<0.001) differentially expressed genes in the VC(-) and VC(+) groups. From the functional analysis of the differentially expressed genes in the VC(-) and VC(+) groups, predicted functionalities including cell death and cytotoxicity increased in the VC(+) group. Furthermore, it was predicted that the difference in hair growth between the VC(-) and VC(+) groups was caused by the expression of genes including keratin-related genes and the Sonic hedgehog gene. It was confirmed that hair growth was significantly promoted; hair growth from hair papilla cells was also confirmed by HE staining of the shaved backs of SMP-30/GNL-KO mice in the VC(+) group. RNA-seq of the skin from VC-deficient mice showed the effects of VC deficiency on the expression of genes involved in cell growth and the hair cycle. Visual inspection suggested that changes in the expression of the genes are involved in delaying hair growth in the VC(-) group. Further research on the relationship among VC deficiency, the hair cycle, and skin cell growth may contribute to research on hair restoration and skin aging. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

A Study on the Rectification Property of Self-Assembled Viologen Single Molecules Using a Scanning Tunneling Microscopy.

PubMed

Lee, Nam-Suk; Shin, Hoon-Kyu; Kwon, Young-Soo

2015-02-01

An ultrahigh vacuum scanning tunneling microscopy (UHV-STM) and a scanning tunneling spectroscopy (STS) are used measure the rectification property of self-assembled viologen single molecules (VC8SH, VC10SH, HSC8VC8SH, and HSC10VC10SH) in the previous study. Using STM we observe viologen single molecules in the self-assembled octanethiol (OT) SAM matrix. In the OT matrix a mixed phase that includes a c(4 x 2) superlattice of high-density standing up-phase is observed. We indicate high peak current-like rectifications at + 1.68 V(VC8SH), + 1.56 V(VC10SH), + 1.14 V(HSC8VC8SH), and + 1.04 V(HSC10VC10SH) based on the experiment implemented in this study. In addition, transition voltages (Vtrans) from direct tunneling to the Fowler-Nordheim tunneling are presented at 1.08 V(VC8SH), 0.97 V(VC10SH), 0.99 V(HSC8VC8SH), and 0.89 V(HSC1VC1SH).

VC-dimension of univariate decision trees.

PubMed

Yildiz, Olcay Taner

2015-02-01

In this paper, we give and prove the lower bounds of the Vapnik-Chervonenkis (VC)-dimension of the univariate decision tree hypothesis class. The VC-dimension of the univariate decision tree depends on the VC-dimension values of its subtrees and the number of inputs. Via a search algorithm that calculates the VC-dimension of univariate decision trees exhaustively, we show that our VC-dimension bounds are tight for simple trees. To verify that the VC-dimension bounds are useful, we also use them to get VC-generalization bounds for complexity control using structural risk minimization in decision trees, i.e., pruning. Our simulation results show that structural risk minimization pruning using the VC-dimension bounds finds trees that are more accurate as those pruned using cross validation.

Characterization of an Isolate That Uses Vinyl Chloride as a Growth Substrate under Aerobic Conditions

PubMed Central

Verce, Matthew F.; Ulrich, Ricky L.; Freedman, David L.

2000-01-01

An aerobic enrichment culture was developed by using vinyl chloride (VC) as the sole organic carbon and electron donor source. VC concentrations as high as 7.3 mM were biodegraded without apparent inhibition. VC use did not occur when nitrate was provided as the electron acceptor. A gram-negative, rod-shaped, motile isolate was obtained from the enrichment culture and identified based on biochemical characteristics and the sequence of its 16S rRNA gene as Pseudomonas aeruginosa, designated strain MF1. The observed yield of MF1 when it was grown on VC was 0.20 mg of total suspended solids (TSS)/mg of VC. Ethene, acetate, glyoxylate, and glycolate also served as growth substrates, while ethane, chloroacetate, glycolaldehyde, and phenol did not. Stoichiometric release of chloride and minimal accumulation of soluble metabolites following VC consumption indicated that the predominant fate for VC is mineralization and incorporation into cell material. MF1 resumed consumption of VC after at least 24 days when none was provided, unlike various mycobacteria that lost their VC-degrading ability after brief periods in the absence of VC. When deprived of oxygen for 2.5 days, MF1 did not regain the ability to grow on VC, and a portion of the VC was transformed into VC-epoxide. Acetylene inhibited VC consumption by MF1, suggesting the involvement of a monooxygenase in the initial step of VC metabolism. The maximum specific VC utilization rate for MF1 was 0.41 μmol of VC/mg of TSS/day, the maximum specific growth rate was 0.0048/day, and the Monod half-saturation coefficient was 0.26 μM. A higher yield and faster kinetics occurred when MF1 grew on ethene. When grown on ethene, MF1 was able to switch to VC as a substrate without a lag. It therefore appears feasible to grow MF1 on a nontoxic substrate and then apply it to environments that do not exhibit a capacity for aerobic biodegradation of VC. PMID:10919818

The enriched fraction of Vernonia cinerea L. induces apoptosis and inhibits multi-drug resistance transporters in human epithelial cancer cells.

PubMed

Appadath Beeran, Asmy; Maliyakkal, Naseer; Rao, Chamallamudi Mallikarjuna; Udupa, Nayanabhirama

2014-12-02

Vernonia cinerea Less. (VC) of the family Asteraceaes is considered as the sacred plant; 'Dasapushpam' which is ethnopharmacologically significant to the people of Kerala in India. In fact, VC has been used in the traditional system of medicine (Ayurveda) for the treatment of various ailments including cancer. Cytotoxicity of the ethanolic extract of VC (VC-ET), petroleum ether fraction (VC-PET), dichloromethane fraction (VC-DCM), n-butyl alcohol fraction (VC-BT), and rest fraction (VC-R) was evaluated in cervical carcinoma (HeLa), lung adenocarcinoma (A549), breast cancer (MCF-7), and colon carcinoma (Caco-2) cells using Sulforhodamine B (SRB) assay. The apoptotic effects of VC-DCM were assessed in cancer cells using Annexin V assay. The effects of VC-DCM on multi-drug resistance (MDR) transporters in HeLa, A549, MCF-7, and Caco-2 cells were evaluated using flow cytometry based functional assays. Similarly, drug uptake in cancer cells and sensitization of cancer cells towards chemotherapeutic drugs in the presence of VC-DCM were studied using Daunorubicin (DNR) accumulation assay and SRB assay, respectively. Cytotoxicity assay revealed that the enriched fraction of VC (VC-DCM) possessed dose-dependent cytotoxic effects in human epithelial cancer cells (HeLa, A549, MCF-7, and Caco-2). Further, treatment of cancer cells (HeLa, A549, MCF-7, and Caco-2) with VC-DCM led to a significant increase in both early and late apoptosis, indicating the induction of apoptosis. Interestingly, VC-DCM significantly inhibited functional activity of MDR transporters (ABC-B1 and ABC-G2), enhanced DNR-uptake in cancer cells, and sensitized cancer cells towards chemotherapeutic drug-mediated cytotoxicity, thus indicating the ability of VC-DCM to reverse MDR in cancer and enhance the cytotoxic effects of anticancer drugs. A methodological investigation on the anti-cancer properties of Vernonia cinerea Less. (VC) revealed that an enriched fraction of VC (VC-DCM) possessed cytotoxic effects, triggered apoptosis, inhibited MDR transporters, enhanced drug uptake, and sensitized cancer cells towards anticancer drug-mediated cytotoxicity in human epithelial cancer cells. Thus, VC appears to be promising for an effective treatment of various drug-resistant human epithelial cancers. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Identification and expression analysis of MATE genes involved in flavonoid transport in blueberry plants.

PubMed

Chen, Li; Liu, Yushan; Liu, Hongdi; Kang, Limin; Geng, Jinman; Gai, Yuzhuo; Ding, Yunlong; Sun, Haiyue; Li, Yadong

2015-01-01

Multidrug and toxic compound extrusion (MATE) proteins are the most recently identified family of multidrug transporters. In plants, this family is remarkably large compared to the human and bacteria counterpart, highlighting the importance of MATE proteins in this kingdom. Here 33 Unigenes annotated as MATE transporters were found in the blueberry fruit transcriptome, of which eight full-length cDNA sequences were identified and cloned. These proteins are composed of 477-517 residues, with molecular masses ~54 kDa, and theoretical isoelectric points from 5.35 to 8.41. Bioinformatics analysis predicted 10-12 putative transmembrane segments for VcMATEs, and localization to the plasma membrane without an N-terminal signal peptide. All blueberry MATE proteins shared 32.1-84.4% identity, among which VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8, and VcMATE9 were more similar to the MATE-type flavonoid transporters. Phylogenetic analysis showed VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8 and VcMATE9 clustered with MATE-type flavonoid transporters, indicating that they might be involved in flavonoid transport. VcMATE1 and VcMATE4 may be involved in the transport of secondary metabolites, the detoxification of xenobiotics, or the export of toxic cations. Real-time quantitative PCR demonstrated that the expression profile of the eight VcMATE genes varied spatially and temporally. Analysis of expression and anthocyanin accumulation indicated that there were some correlation between the expression profile and the accumulation of anthocyanins. These results showed VcMATEs might be involved in diverse physiological functions, and anthocyanins across the membranes might be mutually maintained by MATE-type flavonoid transporters and other mechanisms. This study will enrich the MATE-based transport mechanisms of secondary metabolite, and provide a new biotechonology strategy to develop better nutritional blueberry cultivars.

Identification and Expression Analysis of MATE Genes Involved in Flavonoid Transport in Blueberry Plants

PubMed Central

Chen, Li; Liu, Yushan; Liu, Hongdi; Kang, Limin; Geng, Jinman; Gai, Yuzhuo; Ding, Yunlong; Sun, Haiyue; Li, Yadong

2015-01-01

Multidrug and toxic compound extrusion (MATE) proteins are the most recently identified family of multidrug transporters. In plants, this family is remarkably large compared to the human and bacteria counterpart, highlighting the importance of MATE proteins in this kingdom. Here 33 Unigenes annotated as MATE transporters were found in the blueberry fruit transcriptome, of which eight full-length cDNA sequences were identified and cloned. These proteins are composed of 477–517 residues, with molecular masses ~54 kDa, and theoretical isoelectric points from 5.35 to 8.41. Bioinformatics analysis predicted 10–12 putative transmembrane segments for VcMATEs, and localization to the plasma membrane without an N-terminal signal peptide. All blueberry MATE proteins shared 32.1–84.4% identity, among which VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8, and VcMATE9 were more similar to the MATE-type flavonoid transporters. Phylogenetic analysis showed VcMATE2, VcMATE3, VcMATE5, VcMATE7, VcMATE8 and VcMATE9 clustered with MATE-type flavonoid transporters, indicating that they might be involved in flavonoid transport. VcMATE1 and VcMATE4 may be involved in the transport of secondary metabolites, the detoxification of xenobiotics, or the export of toxic cations. Real-time quantitative PCR demonstrated that the expression profile of the eight VcMATE genes varied spatially and temporally. Analysis of expression and anthocyanin accumulation indicated that there were some correlation between the expression profile and the accumulation of anthocyanins. These results showed VcMATEs might be involved in diverse physiological functions, and anthocyanins across the membranes might be mutually maintained by MATE-type flavonoid transporters and other mechanisms. This study will enrich the MATE-based transport mechanisms of secondary metabolite, and provide a new biotechonology strategy to develop better nutritional blueberry cultivars. PMID:25781331

Vitamin C impacts anxiety-like behavior and stress-induced anorexia relative to social environment in SMP30/GNL knockout mice.

PubMed

Koizumi, Miwako; Kondo, Yoshitaka; Isaka, Ayumi; Ishigami, Akihito; Suzuki, Emiko

2016-12-01

The role of endogenous vitamin C (VC) in emotion and psychiatric measures has long been uncertain. We aimed to investigate how an individual's VC status impacts his or her mental health. Our hypothesis is that body VC levels modulate anxiety, anorexia, and depressive phenotypes under the influence of psychosocial rearing environments and sex. The VC status of senescence marker protein-30/gluconolactonase knockout mice, which lack the ability to synthesize VC, were continuously shifted from adequate (VC+) to depleted (VC-) by providing a water with or without VC. Despite weight loss in both sexes, suppressed feeding was specifically seen in males only during the VC- phase. Anxiety responses in the novelty-suppressed feeding paradigm were worse during the VC-, especially in females. Sensitivity to the forced swim test as determined by the initial latency was significantly shorter in the socially stable animals compared with socially unstable animals during the VC+ condition. The stress coping underlying depressive phenotypes was assessed by immobility duration in a series of forced swim tests. No significant differences were apparent between contrasting VC status. Homeostatic symptoms following stressful behavioral tests consisted of a great loss of appetite during the VC-. It should be noted that anorexia is extremely serious for the females. We conclude that endogenous VC status is critical for determining vulnerability to anxiety and anorexia in a sex-specific manner. Copyright © 2016 Elsevier Inc. All rights reserved.

Receptivity of a precessing vortex core to open-loop forcing in a swirling jet and its predictability by linear stability adjoint theory

NASA Astrophysics Data System (ADS)

Müller, Jens; Lückoff, Finn; Oberleithner, Kilian

2017-11-01

The precessing vortex core (PVC) is a dominant coherent structure which occurs in swirling jets such as in swirl-stabilised gas turbine combustors. It stems from a global hydrodynamic instability caused by an internal feedback mechanism within the jet core. In this work, open-loop forcing is applied to a generic non-reacting swirling jet to investigate its receptivity to external actuation regarding lock-in behaviour of the PVC for different streamwise positions and Reynolds numbers. The forcing is periodically exerted by zero net mass flux synthetic jets which are introduced radially through slits inside the duct walls upstream of the swirling jet's exit plane. Time-resolved pressure measurements are conducted to identify the PVC frequency and stereo PIV combined with proper orthogonal decomposition in the duct and free field is used to extract the mean flow and the PVC mode. The data is used in a global linear stability framework to gain the adjoint of the PVC which reveals the regions of highest receptivity to periodic forcing based on mean flow input only. This theoretical receptivity model is compared with the experimentally obtained receptivity results and the validity and applicability of the adjoint model for the prediction of optimal forcing positions is discussed.

Integrated Physics-based Modeling and Experiments for Improved Prediction of Combustion Dynamics in Low-Emission Systems

NASA Technical Reports Server (NTRS)

Anderson, William E.; Lucht, Robert P.; Mongia, Hukam

2015-01-01

Concurrent simulation and experiment was undertaken to assess the ability of a hybrid RANS-LES model to predict combustion dynamics in a single-element lean direct-inject (LDI) combustor showing self-excited instabilities. High frequency pressure modes produced by Fourier and modal decomposition analysis were compared quantitatively, and trends with equivalence ratio and inlet temperature were compared qualitatively. High frequency OH PLIF and PIV measurements were also taken. Submodels for chemical kinetics and primary and secondary atomization were also tested against the measured behavior. For a point-wise comparison, the amplitudes matched within a factor of two. The dependence on equivalence ratio was matched. Preliminary results from simulation using an 18-reaction kinetics model indicated instability amplitudes closer to measurement. Analysis of the simulations suggested a band of modes around 1400 Hz were due to a vortex bubble breakdown and a band of modes around 6 kHz were due to a precessing vortex core hydrodynamic instability. The primary needs are directly coupled and validated ab initio models of the atomizer free surface flow and the primary atomization processes, and more detailed study of the coupling between the 3D swirling flow and the local thermoacoustics in the diverging venturi section.

Rotationally resolved state-to-state photoionization and the photoelectron study of vanadium monocarbide and its cations (VC/VC(+)).

PubMed

Chang, Yih Chung; Luo, Zhihong; Pan, Yi; Zhang, Zheng; Song, Ying-Nan; Kuang, Sophie Yajin; Yin, Qing Zhu; Lau, Kai-Chung; Ng, C Y

2015-04-21

By employing two-color visible (VIS)-ultraviolet (UV) laser photoionization and pulsed field ionization-photoelectron (PFI-PE) techniques, we have obtained highly rotationally resolved photoelectron spectra for vanadium monocarbide cations (VC(+)). The state-to-state VIS-UV-PFI-PE spectra thus obtained allow unambiguous assignments for the photoionization rotational transitions, resulting in a highly precise value for the adiabatic ionization energy (IE) of vanadium monocarbide (VC), IE(VC) = 57512.0 ± 0.8 cm(-1) (7.13058 ± 0.00010 eV), which is defined as the energy of the VC(+)(X(3)Δ1; v(+) = 0; J(+) = 1) ← VC(X(2)Δ3/2; v'' = 0; J'' = 3/2) photoionization transition. The spectroscopic constants for VC(+)(X(3)Δ1) determined in the present study include the harmonic vibrational frequency ωe(+) = 896.4 ± 0.8 cm(-1), the anharmonicity constant ωe(+)xe(+) = 5.7 ± 0.8 cm(-1), the rotational constants Be(+) = 0.6338 ± 0.0025 cm(-1) and αe(+) = 0.0033 ± 0.0007 cm(-1), the equilibrium bond length re(+) = 1.6549 ± 0.0003 Å, and the spin-orbit coupling constant A = 75.2 ± 0.8 cm(-1) for VC(+)(X(3)Δ1,2,3). These highly precise energetic and spectroscopic data are used to benchmark state-of-the-art CCSDTQ/CBS calculations. In general, good agreement is found between the theoretical predictions and experimental results. The theoretical calculations yield the values, IE(VC) = 7.126 eV; the 0 K bond dissociation energies: D0(V-C) = 4.023 eV and D0(V(+)-C) = 3.663 eV; and heats of formation: ΔH°(f0)(VC) = 835.2, ΔH°(f298)(VC) = 840.4, ΔH°(f0)(VC(+)) = 1522.8, and ΔH°(f298)(VC(+)) = 1528.0 kJ mol(-1).

Vespa crabro immunotherapy versus Vespula-venom immunotherapy in Vespa crabro allergy: a comparison study in field re-stings.

PubMed

Macchia, Donatella; Cortellini, Gabriele; Mauro, Marina; Meucci, Elisa; Quercia, Oliviero; Manfredi, Mariangela; Massolo, Alessandro; Valentini, Maurizio; Severino, Maurizio; Passalacqua, Giovanni

2018-01-01

In ascertained allergic sensitization to Vespa crabro (VC) venom, the European guidelines still consider venom immunotherapy (VIT) with Vespula (VE) venom sufficient to achieve an adequate protection against VC. However, antigen 5 immunoblotting studies showed that a genuine sensitization to VC venom may exist. In such cases, a specific VC venom would be preferable for VIT treatment. Since in the last few years, VC venom extracts became available for diagnosis and desensitization, we assessed the efficacy and safety of VIT with a VC-VIT, compared to VE extract. Patients stung by VC, and carefully diagnosed for specific sensitization and indication to VIT underwent a 5-year course of immunotherapy with either VE or VC extracts . The severity of reactions at the first sting (pre-VIT) and after field re-stings (during VIT) were compared. Eighty-three patients, treated with VE extract and 130 patients treated with VC extract completed the 5-year course of VIT. Only a fraction of those patients (43,8%) were field-re-stung by VC: 64 patients on VC VIT and 69 on VE VIT. In the VC VIT group, reactions at re-sting were: 50 negative, 12 large local reactions, 4 systemic reactions (Muller grade I). In this group the VC VIT efficacy was 93,8%. In the VE VIT treated group the reactions at VC re-sting were: 51 negative, 10 large local reactions and 9 systemic reactions (5 Muller I, 3 Mueller III, 1 Muller IV). In this group the overall efficacy of VIT was 87,0%. The difference in efficacy between the two groups was not statistically significant, as previously reported in literature. Nonetheless, field sting systemic reactions Muller III and IV were recorded only in those patients receiving VE VIT. This observation suggests that in patients with ascertained VC-induced allergic reactions a specific VC VIT, where available, would be more adequate, at least concerning the safety profile.

Transcriptional analysis of Volvox photoreceptors suggests the existence of different cell-type specific light-signaling pathways.

PubMed

Kianianmomeni, Arash; Hallmann, Armin

2015-02-01

Photosynthetic organisms, e.g., plants including green algae, use a sophisticated light-sensing system, composed of primary photoreceptors and additional downstream signaling components, to monitor changes in the ambient light environment towards adjust their growth and development. Although a variety of cellular processes, e.g., initiation of cleavage division and final cellular differentiation, have been shown to be light-regulated in the green alga Volvox carteri, little is known about the underlying light perception and signaling pathways. This multicellular alga possesses at least 12 photoreceptors, i.e., one phototropin (VcPhot), four cryptochromes (VcCRYa, VcCRYp, VcCRYd1, and VcCRYd2), and seven members of rhodopsin-like photoreceptors (VR1, VChR1, VChR2, VcHKR1, VcHKR2, VcHKR3, and VcHKR4), which display distinct light-dependent chemical processes based on their protein architectures and associated chromophores. Gene expression analyses could show that the transcript levels of some of the photoreceptor genes (e.g., VChR1 and VcHKR1) accumulate during division cleavages, while others (e.g., VcCRYa, VcCRYp, and VcPhot) accumulate during final cellular differentiation. However, the pattern of transcript accumulation changes when the alga switches to the sexual development. Eight photoreceptor genes, e.g., VcPhot, VcCRYp, and VcHKR1, are highly expressed in the somatic cells, while only the animal-type rhodopsin VR1 was found to be highly expressed in the reproductive cells/embryos during both asexual and sexual life cycles. Moreover, accumulation of VChR1 and VcCRYa transcripts is more sensitive to light and changes in response to more than one light quality. Obviously, different regulatory mechanisms underlying gene expression control transcript accumulation of photoreceptors not only during development, but also in a cell-type specific way and in response to various external signals such as light quality. The transcriptional patterns described in this study show that Volvox photoreceptors are mostly expressed in a cell-type specific manner. This gives reason to believe that cell-type specific light-signaling pathways allow differential regulation of cellular and developmental processes in response to the environmental light cues.

Erosion and corrosion resistance of laser cladded AISI 420 stainless steel reinforced with VC

NASA Astrophysics Data System (ADS)

Zhang, Zhe; Yu, Ting; Kovacevic, Radovan

2017-07-01

Metal Matrix Composites (MMC) fabricated by the laser cladding process have been widely applied as protective coatings in industries to improve the wear, erosion, and corrosion resistance of components and prolong their service life. In this study, the AISI 420/VC metal matrix composites with different weight percentage (0 wt.%-40 wt.%) of Vanadium Carbide (VC) were fabricated on a mild steel A36 by a high power direct diode laser. An induction heater was used to preheat the substrate in order to avoid cracks during the cladding process. The effect of carbide content on the microstructure, elements distribution, phases, and microhardness was investigated in detail. The erosion resistance of the coatings was tested by using the abrasive waterjet (AWJ) cutting machine. The corrosion resistance of the coatings was studied utilizing potentiodynamic polarization. The results showed that the surface roughness and crack susceptibility of the laser cladded layer were increased with the increase in VC fraction. The volume fraction of the precipitated carbides was increased with the increase in the VC content. The phases of the coating without VC consisted of martensite and austenite. New phases such as precipitated VC, V8C7, M7C3, and M23C6 were formed when the primary VC was added. The microhardness of the clads was increased with the increase in VC. The erosion resistance of the cladded layer was improved after the introduction of VC. The erosion resistance was increased with the increase in the VC content. No obvious improvement of erosion resistance was observed when the VC fraction was above 30 wt.%. The corrosion resistance of the clads was decreased with the increase in the VC content, demonstrating the negative effect of VC on the corrosion resistance of AISI 420 stainless steel

Numerical simulation of a turbulent flame stabilized behind a rearward-facing step

NASA Technical Reports Server (NTRS)

Hsiao, C. C.; Oppenheim, A. K.; Chorin, A. J.; Ghoniem, A. F.

1985-01-01

Flow of combustible mixtures in a plane channel past a smooth contraction followed by an abrupt expansion, in a typical dump combustor configuration, is modeled by a two-dimensional numerical technique based on the random vortex method. Both the inert and the reacting case are considered. In the latter, the flame is treated as an interface, self-advancing at a prescribed normal burning speed, while the dynamic effects of expansion due to the exothermicity of combustion are expressed by volumetric source lines delineated by its front. Solutions are shown to be in satisfactory agreement with experimental results, especially with respect to global properties such as the average velocity profiles and the reattachment length. The stochastic turbulent velocity components manifest interesting differences, especially near the walls where three-dimensional effects of turbulence are expected to be of importance.

Overexpression of blueberry FLOWERING LOCUS T is associated with changes in the expression of phytohormone-related genes in blueberry plants.

PubMed

Gao, Xuan; Walworth, Aaron E; Mackie, Charity; Song, Guo-Qing

2016-01-01

Flowering locus T ( FT ) is a primary integrator in the regulation of plant flowering. Overexpressing a blueberry ( Vaccinium corymbosum L.) FT gene ( VcFT ) (herein VcFT -OX) resulted in early flowering and dwarfing in 'Aurora' plants (herein 'VcFT-Aurora'). In this study, we found that VcFT -OX reduced shoot regeneration from leaf explants. To investigate the potential roles of the phytohormone pathway genes associated with VcFT -OX, differentially expressed ( DE ) genes in leaf tissues of 'VcFT-Aurora' plants were annotated and analyzed using non-transgenic 'Aurora' plants as a control. Three DE floral genes, including the blueberry SUPPRESSOR of Overexpression of constans 1 ( VcSOC1 ) (gibberellin related), Abscisic acid responsive elements-binding factor 2 ( VcABF2 ) and protein related to ABI3/VP1 ( VcABI3/VP1 ) (ethylene-related), are present under both the phytohormone-responsive and the dwarfing-related Gene Ontology terms. The gene networks of the DE genes overall showed the molecular basis of the multifunctional aspects of VcFT overexpression beyond flowering promotion and suggested that phytohormone changes could be signaling molecules with important roles in the phenotypic changes driven by VcFT -OX.

Overexpression of blueberry FLOWERING LOCUS T is associated with changes in the expression of phytohormone-related genes in blueberry plants

PubMed Central

Gao, Xuan; Walworth, Aaron E; Mackie, Charity; Song, Guo-qing

2016-01-01

Flowering locus T (FT) is a primary integrator in the regulation of plant flowering. Overexpressing a blueberry (Vaccinium corymbosum L.) FT gene (VcFT) (herein VcFT-OX) resulted in early flowering and dwarfing in ‘Aurora’ plants (herein ‘VcFT-Aurora’). In this study, we found that VcFT-OX reduced shoot regeneration from leaf explants. To investigate the potential roles of the phytohormone pathway genes associated with VcFT-OX, differentially expressed (DE) genes in leaf tissues of ‘VcFT-Aurora’ plants were annotated and analyzed using non-transgenic ‘Aurora’ plants as a control. Three DE floral genes, including the blueberry SUPPRESSOR of Overexpression of constans 1 (VcSOC1) (gibberellin related), Abscisic acid responsive elements-binding factor 2 (VcABF2) and protein related to ABI3/VP1 (VcABI3/VP1) (ethylene-related), are present under both the phytohormone-responsive and the dwarfing-related Gene Ontology terms. The gene networks of the DE genes overall showed the molecular basis of the multifunctional aspects of VcFT overexpression beyond flowering promotion and suggested that phytohormone changes could be signaling molecules with important roles in the phenotypic changes driven by VcFT-OX. PMID:27818778

Effect of contaminant concentration on aerobic microbial mineralization of DCE and VC in stream-bed sediments

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

1998-01-01

Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2- 14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.Discharge of DCE and VC to an aerobic surface water system simultaneously represents a significant environmental concern and, potentially, a non-engineered opportunity for efficient contaminant bioremediation. The potential for bioremediation, however, depends on the ability of the stream-bed microbial community to efficiently and completely degrade DCE and VC over a range of contaminant concentrations. The purposes of the studies reported here were to assess the potential for aerobic DCE and VC mineralization by stream-bed microorganisms and to evaluate the effects of DCE and VC concentrations on the apparent rates of aerobic mineralization. Bed-sediment microorganisms indigenous to a creek, where DCE-contaminated groundwater continuously discharges, demonstrated rapid mineralization of DCE and VC under aerobic conditions. Over 8 days, the recovery of [1,2-14C]DCE radioactivity as 14CO2 ranged from 17% to 100%, and the recovery of [1,2-14C]VC radioactivity as 14CO2 ranged from 45% to 100%. Rates of DCE and VC mineralization increased significantly with increasing contaminant concentration, and the response of apparent mineralization rates to changes in DCE and VC concentrations was adequately described by Michaelis-Menten kinetics.

Assessing Intracranial Vascular Compliance Using Dynamic Arterial Spin Labeling

PubMed Central

Yan, Lirong; Liu, Collin Y.; Smith, Robert X.; Jog, Mayank; Langham, Michael; Krasileva, Kate; Chen, Yufen; Ringman, John M.; Wang, Danny J.J.

2015-01-01

Vascular compliance (VC) is an important marker for a number of cardiovascular diseases and dementia, which is typically assessed in central and peripheral arteries indirectly by quantifying pulse wave velocity (PWV), and/or pulse pressure waveform. To date, very few methods are available for the quantification of intracranial VC. In the present study, a novel MRI technique for in-vivo assessment of intracranial VC was introduced, where dynamic arterial spin labeling (ASL) scans were synchronized with the systolic and diastolic phases of the cardiac cycle. VC is defined as the ratio of change in arterial cerebral blood volume (ΔCBV) and change in arterial pressure (ΔBP). Intracranial VC was assessed in different vascular components using the proposed dynamic ASL method. Our results show that VC mainly occurs in large arteries, gradually decreases in small arteries and arterioles. The comparison of intracranial VC between young and elderly subjects shows that aging is accompanied by a reduction of intracranial VC, in good agreement with the literature. Furthermore, a positive association between intracranial VC and cerebral perfusion measured using pseudo-continuous ASL with 3D GRASE MRI was observed independent of aging effects, suggesting loss of VC is associated with a decline in perfusion. Finally, a significant positive correlation between intracranial and central (aortic arch) VC was observed using an ungated phase-contrast 1D projection PWV technique. The proposed dynamic ASL method offers a promising approach for assessing intracranial VC in a range of cardiovascular diseases and dementia. PMID:26364865

Converting virtual community members into online buyers.

PubMed

Gupta, Sumeet; Kim, Hee-Woong; Shin, Seon-Jin

2010-10-01

Although many online vendors have sponsored virtual communities (VCs) in the hope of reaping commercial benefits from it, not many have been successful in reaping commercial benefits from their VC. Online vendors can benefit greatly from having a VC, if the VC members can be converted into online buyers. This study examines the conversion of a VC member into an online buyer. Using a classical-conditioning approach, this study finds that members' committed participation in the VC is the springboard for online vendors to convert VC members into online buyers.

SU-F-P-61: Does It Matter Not to Use Optimization Points at the Apex for Vaginal Cylinder HDR Brachytherapy Planning?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Y

2016-06-15

Purpose: To test the impact of the use of apex optimization points for new vaginal cylinder (VC) applicators. Methods: New “ClickFit” single channel VC applicators (Varian) that have a different top thicknesses but the same diameters as the old VC applicators (2.3 cm diameter, 2.6 cm, 3.0 cm, and 3.5 cm) were compared using phantom studies. Old VC applicator plans without apex optimization points were also compared to the plans with the optimization points. The apex doses were monitored at 5 mm depth doses (8 points) where a prescription dose (Rx) of 6Gy was prescribed. VC surface doses (8 points)more » were also analyzed. Results: The new VC applicator plans without apex optimization points presented significantly lower 5mm depth doses than Rx (on average −31 ± 7%, p <0.00001) due to their thicker VC tops (3.4 ± 1.1 mm thicker with the range of 1.2 to 4.4 mm) than the old VC applicators. Old VC applicator plans also showed a statistically significant reduction (p <0.00001) due to Ir-192 source anisotropic effect at the apex region but the % reduction over Rx was only −7 ± 9%. However, by adding apex optimization points to the new VC applicator plans, the plans improved 5 mm depth doses (−7 ± 9% over Rx) that were not statistically different from old VC plans (p = 0.923), along with apex VC surface doses (−22 ± 10% over old VC versus −46 ± 7% without using apex optimization points). Conclusion: The use of apex optimization points are important in order to avoid significant additional cold doses (−24 ± 2%) at the prescription depth (5 mm) of apex, especially for the new VC applicators that have thicker tops.« less

Induction of cell death in renal cell carcinoma with combination of D-fraction and vitamin C.

PubMed

Alexander, Bobby; Fishman, Andrew I; Eshghi, Majid; Choudhury, Muhammad; Konno, Sensuke

2013-09-01

Although several conventional therapeutic options for advanced renal cell carcinoma (RCC) are currently available, the unsatisfactory outcomes demand establishing more effective interventions. D-fraction (PDF), a bioactive proteoglucan of Maitake mushroom, demonstrates anticancer and immunomodulatory activities, which are also shown to be potentiated by vitamin C (VC). We thus hypothesized that a combination of PDF and VC (PDF + VC) could be an alternative approach to more effectively inhibit the growth of RCC. We examined the dose-dependent effects of PDF + VC on RCC cell viability and also performed biochemical assays to explore the growth regulatory mechanism. Human RCC, ACHN cell line, was employed and exposed to varying concentrations of PDF or VC and their combinations. Cell viability at specified times was determined by MTT assay. Lipid peroxidation assay, cell cycle analysis, and Western blot analysis were also performed. PDF or VC alone led to the significant reduction in cell viability at 72 hours with PDF >500 µg/mL and VC ≥300 µM. When various combinations of PDF and VC were tested, the combination of the ineffective concentrations of PDF (300 µg/mL) and VC (200 µM) resulted in ~90% cell death in 24 hours. Lipid peroxidation assay then indicated significantly (~2.5 fold) elevated oxidative stress with this PDF + VC. Cell cycle analysis also indicated a G1 cell cycle arrest following a 6-hour PDF + VC treatment. Western blots further revealed a downregulation of Bcl2, an upregulation of Bax, and proteolytic activation of PARP (poly[ADP-ribose] polymerase) in PDF + VC-treated cells, indicating induction of apoptosis. The present study demonstrates that the combination of PDF and VC can become highly cytotoxic, inducing severe cell death in ACHN cells. This cytotoxic mechanism appears to be primarily attributed to oxidative stress, accompanied by a G1 cell cycle arrest. Such cell death induced by PDF + VC could be more likely linked to apoptosis, as indicated by the modulation of apoptosis regulators (Bcl2, Bax, and PARP). Therefore, as PDF and VC may work synergistically to induce apoptotic cell death, they may have clinical implications in an alternative, improved therapeutic modality for advanced RCC.

Statistical mechanics of the vertex-cover problem

NASA Astrophysics Data System (ADS)

Hartmann, Alexander K.; Weigt, Martin

2003-10-01

We review recent progress in the study of the vertex-cover problem (VC). The VC belongs to the class of NP-complete graph theoretical problems, which plays a central role in theoretical computer science. On ensembles of random graphs, VC exhibits a coverable-uncoverable phase transition. Very close to this transition, depending on the solution algorithm, easy-hard transitions in the typical running time of the algorithms occur. We explain a statistical mechanics approach, which works by mapping the VC to a hard-core lattice gas, and then applying techniques such as the replica trick or the cavity approach. Using these methods, the phase diagram of the VC could be obtained exactly for connectivities c < e, where the VC is replica symmetric. Recently, this result could be confirmed using traditional mathematical techniques. For c > e, the solution of the VC exhibits full replica symmetry breaking. The statistical mechanics approach can also be used to study analytically the typical running time of simple complete and incomplete algorithms for the VC. Finally, we describe recent results for the VC when studied on other ensembles of finite- and infinite-dimensional graphs.

Effects of dietary vitamin C on the immune function of shrimps, Penaeus chinensis

NASA Astrophysics Data System (ADS)

Wang, Weiqing; Li, Aijie; Cheung, Siugin

2002-04-01

Prepared in this experiment were six groups of diets, i.e. VC0, VC1, VC2, VC3, VC4 and VC5 with the contents of vitamin C (VCmg(100 g)-1 diet) of 0, 100, 200, 400, 800, and 1200 respectively. It was found that vitamin C increased the concentrations of immunoglobulin-like (IgG-like, IgA-like and IgM-like) substances in the serum of Penaeus chinensis after a feeding period of 3 weeks. The differences among groups were significant (P<0.01), but there was no difference in the contents of complement3-like and complement4-like substances in the serum (P>0.05). Phenoloxidase (PO) activity in the serum of VC3 group shrimps was higher than that of VC0 and other groups, but no significant difference was observed between VC0 group and other groups. Furthermore, bactericidal activity of the serum to Vibrio parahaemolyticus in shrimps fed with the VC1 diet was higher than that in the other groups (P<0.01), while no difference was demonstrated among all groups for the bactericidal activity to Vibrio alginolyticus (P>0.05). It is, therefore, suggested that vitamin C (100 400 mg(100 g)-1 diets) could be used as an immunostimulant of P. chinensis.

Enhanced Antioxidant Activity of Mugwort Herb and Vitamin C in Combination on Shelf-life of Chicken Nuggets

PubMed Central

Choi, Yun-Sang; Lee, Mi-Ai

2014-01-01

The effect of mugwort extract (ME) and vitamin C (VC), added individually or in combination, on color, lipid oxidation, and sensory characteristics of chicken nuggets stored for 12 d was investigated. Eight treatments of chicken nuggets contained the following: Control (no antioxidant added), VC (0.05% VC), ME 0.05 (0.05% ME), ME 0.1 (0.1% ME), ME 0.2 (0.2% ME), VC+ME 0.05 (0.05% VC + 0.05% ME) and VC+ME 0.1 (0.05% VC + 0.1% ME), VC+ME 0.2 (0.05% VC + 0.2% ME). Results showed that the mixture of 0.05% VC and 0.2% ME was most effective for delaying lipid oxidation (thiobarbituric acid reactive substances, conjugated dienies, and peroxide formation) when compared to the control or ME alone added. The color values of all treatments were significantly affected by adding ME. Additionally, the total color difference (ΔE), chroma (C*), and hue angle (H°) values of all treatments, except for VC, were lower than those of the control as the amount of ME increased. The sensory characteristics (flavor, odor, and overall acceptability) did not differ significantly in any of the chicken nugget samples, whereas storage time had a significant effect. The results suggest that the possibility of utilizing chicken nuggets with a mixture of mugwort extract and vitamin C for the increase of shelf-life and quality. PMID:26761491

Vascular calcification on plain radiographs is associated with carotid intima media thickness, malnutrition and cardiovascular events in dialysis patients: a prospective observational study

PubMed Central

2013-01-01

Background Vascular calcification (VC) and carotid intima media thickness (CIMT) are strongly associated with cardiovascular (CV) disease. We hypothesized that significant VC on plain radiographs is associated with CIMT and CV events in dialysis patients. In addition, we evaluated risk factors for VC progression on plain radiographs in dialysis patients. Methods In this 2-year observational, prospective study, 67 dialysis patients were included. We checked plain radiographs at baseline and after 2 years. Laboratory tests and malnutrition score were obtained at baseline, after 12 months, and after 24 months. Results The mean age of patients was 56.3 ± 10.3 years and duration of dialysis was 41.3 ± 34.5 months. The prevalence of significant VC was 61.2% and the prevalence of carotid artery atheromatous plaques was 55.6%. Mean CIMT, malnutrition scores, CRP level and prevalence of carotid atheromatous plaques were significantly higher in patients with significant VC. Serum albumin and total iron binding capacity were significantly lower in patients with significant VC compared to patients without significant VC. During a mean observational period of 22 months, patients without significant VC showed lower CV events by the Kaplan-Meyer method (p = 0.010). Progression of VC was found in 35.7% among 56 patients followed up. Hemoglobin after 24 months was an independent factor for progression of VC (Exp(B) = 0.344, 95% Confidence Interval = 0.13 – 0.96, p = 0.034). Conclusions Significant VC on plain radiograph was associated with CIMT, malnutrition, inflammation, and CV events in dialysis patients. Conditions which increase hemoglobin level may retard progression of VC in dialysis patients. PMID:23360132

Vitamin C and vitamin E supplementation alleviates oxidative stress induced by dexamethasone and improves fertility of breeder roosters.

PubMed

Min, Yuna; Sun, Tongtong; Niu, Zhuye; Liu, Fuzhu

2016-08-01

This study was conducted to determine the effect of supplemental dietary vitamin C (VC) and vitamin E (VE) on improving semen quality and antioxidative status in breeder roosters challenged with dexamethasone (DEX). 120 45-week-old Lveyang black-boned breeder roosters were divided into 5 experimental treatments, including negative group, positive group, and three trial groups, which were fed basal diet supplemented with 300mg/kg VC, 200mg/kg VE, or 300mg/kg VC and 200mg/kg VE (VC+VE). At 49 weeks of age, the positive control and trial groups were subcutaneously injected 3 times every other day with DEX 4 mg/kg body weight, the negative control group was sham injected with saline. At 50 weeks of age, average daily feed intake of birds challenged with DEX significantly increased (P<0.05), however, serum testosterone significantly decreased (P<0.05). Dietary supplementation of VC+VE enhanced serum testosterone and sperm motility remarkably (P<0.05). There were no differences in sperm viability between the DEX-treated groups. During the post-stress recovery period (52 weeks of age), dietary supplementation of VE and VC+VE significantly increased the body weight of birds under oxidative stress (P<0.01). VC, VE, and VC+VE groups had greater sperm viability than control group (P<0.01). Additionally, there was a decrease in the semen plasma malondialdehyde content (P<0.05) of the VC and VC+VE groups, and in the testicular malondialdehyde content (P<0.01) of the VE and VC+VE groups. In summary, VC, VE, especially their combination alleviate the oxidative stress induced by DEX and are favorable for the fertility of breeder roosters. Copyright © 2016. Published by Elsevier B.V.

Differences in substrate specificity of V. cholerae FabH enzymes suggest new approaches for the development of novel antibiotics and biofuels.

PubMed

Hou, Jing; Zheng, Heping; Tzou, Wen-Shyong; Cooper, David R; Chruszcz, Maksymilian; Chordia, Mahendra D; Kwon, Keehwan; Grabowski, Marek; Minor, Wladek

2018-06-19

Vibrio cholerae, the causative pathogen of the life-threatening infection cholera, encodes two copies of β-ketoacyl-ACP synthase III (vcFabH1 and vcFabH2). vcFabH1 and vcFabH2 are pathogenic proteins associated with fatty acid synthesis, lipid metabolism, and potential applications in biofuel production. Our biochemical assays characterize vcFabH1 as exhibiting specificity for acetyl-CoA and CoA thioesters with short acyl chains, similar to that observed for FabH homologs found in most Gram-negative bacteria. vcFabH2 prefers medium chain-length acyl-CoA thioesters, particularly octanoyl-CoA, which is a pattern of specificity rarely seen in bacteria. Structural characterization of one vcFabH and six vcFabH2 structures determined in either apo-form or in complex with acetyl-CoA/octanoyl-CoA indicate that the substrate binding pockets of vcFabH1 and vcFabH2 are of different sizes, accounting for variations in substrate chain-length specificity. An unusual and unique feature of vcFabH2 is its C-terminal fragment that interacts with both the substrate-entrance loop and the dimer interface of the enzyme. Our discovery of the pattern of substrate specificity of both vcFabH1 and vcFabH2 can potentially aid the development of novel antibacterial agents against V. cholerae. Additionally, the distinctive substrate preference of FabH2 in V. cholerae and related facultative anaerobes conceivably make it an attractive component of genetically engineered bacteria used for commercial biofuel production. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Solid waste management of temple floral offerings by vermicomposting using Eisenia fetida.

PubMed

Singh, Akanksha; Jain, Akansha; Sarma, Birinchi K; Abhilash, P C; Singh, Harikesh B

2013-05-01

Recycling of temple waste (TW) mainly comprising of floral offerings was done through vermitechnology using Eisenia fetida and its impact on seed germination and plant growth parameters was studied by comparing with kitchen waste (KW) and farmyard waste (FYW) vermicompost (VC). The worm biomass was found to be maximum in TW VC compared to KW and FYW VCs at both 40 and 120days old VCs. Physico-chemical analysis of worm-worked substrates showed better results in TW VC especially in terms of electrical conductivity, C/N, C/P and TK. 10% TW VC-water extract (VCE) showed stimulatory effect on germination percentage of chickpea seeds while KW and FYW VCE proved effective at higher concentration. Variation in growth parameters was also observed with change in the VC-soil ratio and TW VC showed enhanced shoot length, root length, number of secondary roots and total biomass at 12.5% VC compared to KW and FYW VC. Copyright © 2013 Elsevier Ltd. All rights reserved.

Unlocking the Keys to Vortex/Flame Interactions in Turbulent Gas-Jet Diffusion Flames--Dynamic Behavior Explored on the Space Shuttle

NASA Technical Reports Server (NTRS)

Stocker, Dennis P.

1999-01-01

Most combustion processes in industrial applications (e.g., furnaces and engines) and in nature (e.g., forest fires) are turbulent. A better understanding of turbulent combustion could lead to improved combustor design, with enhanced efficiency and reduced emissions. Despite its importance, turbulent combustion is poorly understood because of its complexity. The rapidly changing and random behavior of such flames currently prevents detailed analysis, whether experimentally or computationally. However, it is possible to learn about the fundamental behavior of turbulent flames by exploring the controlled interaction of steady laminar flames and artificially induced flow vortices. These interactions are an inherent part of turbulent flames, and understanding them is essential to the characterization of turbulent combustion. Well-controlled and defined experiments of vortex interaction with laminar flames are not possible in normal gravity because of the interference of buoyancy- (i.e., gravity) induced vortices. Therefore, a joint microgravity study was established by researchers from the Science and Technology Development Corp. and the NASA Lewis Research Center. The experimental study culminated in the conduct of the Turbulent Gas-Jet Diffusion Flames (TGDF) Experiment on the STS-87 space shuttle mission in November 1997. The fully automated hardware, shown in photo, was designed and built at Lewis. During the mission, the experiment was housed in a Get Away Special (GAS) canister in the cargo bay.

Analytical screening of low emissions, high performance duct burners for supersonic cruise aircraft engines

NASA Technical Reports Server (NTRS)

Lohmann, R. A.; Riecke, G. T.

1977-01-01

An analytical screening study was conducted to identify duct burner concepts capable of providing low emissions and high performance in advanced supersonic engines. Duct burner configurations ranging from current augmenter technology to advanced concepts such as premix-prevaporized burners were defined. Aerothermal and mechanical design studies provided the basis for screening these configurations using the criteria of emissions, performance, engine compatibility, cost, weight and relative risk. Technology levels derived from recently defined experimental low emissions main burners are required to achieve both low emissions and high performance goals. A configuration based on the Vorbix (Vortex burning and mixing) combustor concept was analytically determined to meet the performance goals and is consistent with the fan duct envelope of a variable cycle engine. The duct burner configuration has a moderate risk level compatible with the schedule of anticipated experimental programs.

Numerical Simulation of the RTA Combustion Rig

NASA Technical Reports Server (NTRS)

Davoudzadeh, Farhad; Buehrle, Robert; Liu, Nan-Suey; Winslow, Ralph

2005-01-01

The Revolutionary Turbine Accelerator (RTA)/Turbine Based Combined Cycle (TBCC) project is investigating turbine-based propulsion systems for access to space. NASA Glenn Research Center and GE Aircraft Engines (GEAE) planned to develop a ground demonstrator engine for validation testing. The demonstrator (RTA-1) is a variable cycle, turbofan ramjet designed to transition from an augmented turbofan to a ramjet that produces the thrust required to accelerate the vehicle from Sea Level Static (SLS) to Mach 4. The RTA-1 is designed to accommodate a large variation in bypass ratios from sea level static to Mach 4 conditions. Key components of this engine are new, such as a nickel alloy fan, advanced trapped vortex combustor, a Variable Area Bypass Injector (VABI), radial flameholders, and multiple fueling zones. A means to mitigate risks to the RTA development program was the use of extensive component rig tests and computational fluid dynamics (CFD) analysis.

Annular vortex combustor

DOEpatents

Nieh, Sen; Fu, Tim T.

1992-01-01

An apparatus for burning coal water fuel, dry ultrafine coal, pulverized l and other liquid and gaseous fuels including a vertically extending outer wall and an inner, vertically extending cylinder located concentrically within the outer wall, the annnular space between the outer wall and the inner cylinder defining a combustion chamber and the all space within the inner cylinder defining an exhaust chamber. Fuel and atomizing air are injected tangentially near the bottom of the combustion chamber and secondary air is introduced at selected points along the length of the combustion chamber. Combustion occurs along the spiral flow path in the combustion chamber and the combined effects of centrifugal, gravitational and aerodynamic forces cause particles of masses or sizes greater than the threshold to be trapped in a stratified manner until completely burned out. Remaining ash particles are then small enough to be entrained by the flue gas and exit the system via the exhaust chamber in the opposite direction.

Experimental clean combustor program, phase 2

NASA Technical Reports Server (NTRS)

Roberts, R.; Peduzzi, A.; Vitti, G. E.

1976-01-01

Combustor pollution reduction technology for commercial CTOL engines was generated and this technology was demonstrated in a full-scale JT9D engine in 1976. Component rig refinement of the two best combustor concepts were tested. These concepts are the vorbix combustor, and a hybrid combustor which combines the pilot zone of the staged premix combustor and the main zone of the swirl-can combustor. Both concepts significantly reduced all pollutant emissions relative to the JT9D-7 engine combustor. However, neither concept met all program goals. The hybrid combustor met pollution goals for unburned hydrocarbons and carbon monoxide but did not achieve the oxides of nitrogen goal. This combustor had significant performance deficiencies. The Vorbix combustor met goals for unburned hydrocarbons and oxides of nitrogen but did not achieve the carbon monoxide goal. Performance of the vorbix combustor approached the engine requirements. On the basis of these results, the vorbix combustor was selected for the engine demonstration program. A control study was conducted to establish fuel control requirements imposed by the low-emission combustor concepts and to identify conceptual control system designs. Concurrent efforts were also completed on two addendums: an alternate fuels addendum and a combustion noise addendum.

Vaccination coverage among children in Germany estimated by analysis of health insurance claims data

PubMed Central

Rieck, Thorsten; Feig, Marcel; Eckmanns, Tim; Benzler, Justus; Siedler, Anette; Wichmann, Ole

2014-01-01

In Germany, the national routine childhood immunization schedule comprises 12 vaccinations. Primary immunizations should be completed by 24 mo of age. However, nationwide monitoring of vaccination coverage (VC) is performed only at school entry. We utilized health insurance claims data covering ~85% of the total population with the objectives to (1) assess VC of all recommended childhood vaccinations in birth-cohorts 2004–2009, (2) analyze cross-sectional (at 24 and 36 mo) and longitudinal trends, and (3) validate the method internally and externally. Counting vaccine doses in a retrospective cohort fashion, we assembled individual vaccination histories and summarized VC to nationwide figures. For most long-established vaccinations, VC at 24 mo was at moderate levels (~73–80%) and increased slightly across birth-cohorts. One dose measles VC was high (94%), but low (69%) for the second dose. VC with a full course of recently introduced varicella, pneumococcal, and meningococcal C vaccines increased across birth-cohorts from below 10% above 60%, 70%, and 80%, respectively. At 36 mo, VC had increased further by up to 15 percentage points depending on vaccination. Longitudinal analysis suggested a continued VC increase until school entry. Validation of VC figures with primary data showed an overall good agreement. In conclusion, analysis of health insurance claims data allows for the estimation of VC among children in Germany considering completeness and timeliness of vaccination series. This approach provides valid nationwide VC figures for all currently recommended pediatric vaccinations and fills the information gap between early infancy and late assessment at school entry. PMID:24192604

75 FR 70690 - Visteon Corporation Springfield Plant Formerly Known as VC Regional Assembly & Manufacturing, LLC...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-18

... Springfield Plant Formerly Known as VC Regional Assembly & Manufacturing, LLC Including On-Site Leased Workers... formerly known as VC Regional Assembly & Manufacturing, LLC. Workers separated from employment at the... name VC Regional Assembly & Manufacturing, LLC. Accordingly, the Department is amending this...

Theoretical studies to understand surface chemistry on carbon anodes for lithium-ion batteries: how does vinylene carbonate play its role as an electrolyte additive?

PubMed

Wang, Yixuan; Nakamura, Shinichiro; Tasaki, Ken; Balbuena, Perla B

2002-04-24

To elucidate the role of vinylene carbonate (VC) as a solvent additive in organic polar solutions for lithium-ion batteries, reductive decompositions for vinylene carbonate (VC) and ethylene carbonate (EC) molecules have been comprehensively investigated both in the gas phase and in solution by means of density functional theory calculations. The salt and solvent effects are incorporated with the clusters (EC)nLi+(VC) (n = 0-3), and further corrections that account for bulk solvent effects are added using the polarized continuum model (PCM). The electron affinities of (EC)nLi+(VC) (n = 0-3) monotonically decrease when the number of EC molecules increases; a sharp decrease of about 20.0 kcal/mol is found from n = 0 to 1 and a more gentle variation for n > 1. For (EC)nLi+(VC) (n = 1-3), the reduction of VC brings about more stable ion-pair intermediates than those due to reduction of the EC molecule by 3.1, 6.1, and 5.3 kcal/mol, respectively. This finding qualitatively agrees with the experimental fact that the reduction potential of VC in the presence of Li salt is more negative than that of EC. The calculated reduction potentials corresponding to radical anion formation are close to the experimental potentials determined with cyclic voltammetry on a gold electrode surface (-2.67, -3.19 eV on the physical scale for VC and EC respectively vs experimental values -2.96 and -2.94 eV). Regarding the decomposition mechanisms, the VC and EC moieties undergo homolytic ring opening from their respective reduction intermediates, and the energy barrier of VC is about one time higher than that of EC (e.g., 20.1 vs 8.8 kcal/mol for (EC)2Li+(VC)); both are weakly affected by the explicit solvent molecules and by a bulk solvent represented by a continuum model. Alternatively, starting from the VC-reduction intermediate, the ring opening of the EC moiety via an intramolecular electron-transfer transition state has also been located; its barrier lies between those of EC and VC (e.g., 17.2 kcal/mol for (EC)2Li+(VC)). On the basis of these results, we suggest the following explanation about the role that VC may play as additive in EC-based lithium-ion battery electrolytes; VC is initially reduced to a more stable intermediate than that from EC reduction. One possibility then is that the reduced VC decomposes to form a radical anion via a barrier of about 20 kcal/mol, which undergoes a series of reactions to give rise to more active film-forming products than those resulting from EC reduction, such as lithium divinylene dicarbonate, Li-C carbides, lithium vinylene dicarbonate, R-O-Li compound, and even oligomers with repeated vinylene and carbonate-vinylene units. Another possibility starting from the VC-reduction intermediate is that the ring opening occurs on the unreduced EC moiety instead of being on the reduced VC, via an intramolecular electron transfer transition state, the energy barrier of which is lower than that of the former, in which VC just helps the intermediate formation and is not consumed. The factors that determine the additive functioning mechanism are briefly discussed, and consequently a general rule for the selection of electrolyte additive is proposed.

Toward a high-throughput method for determining vicine and convicine levels in faba bean seeds using flow injection analysis combined with tandem mass spectrometry.

PubMed

Purves, Randy W; Khazaei, Hamid; Vandenberg, Albert

2018-08-01

Although faba bean provides environmental and health benefits, vicine and convicine (v-c) limit its use as a source of vegetable protein. Crop improvement efforts to minimize v-c concentration require low-cost, rapid screening methods to distinguish between high and low v-c genotypes to accelerate development of new cultivars and to detect out-crossing events. To assist crop breeders, we developed a unique and rapid screening method that uses a 60 s instrumental analysis step to accurately distinguish between high and low v-c genotypes. The method involves flow injection analysis (FIA) coupled with tandem mass spectrometry (i.e., selective reaction monitoring, SRM). Using seeds with known v-c levels as calibrants, measured v-c levels were comparable with liquid chromatography (LC)-SRM results and the method was used to screen 370 faba bean genotypes. Widespread use of FIA-SRM will accelerate breeding of low v-c faba bean, thereby alleviating concerns about anti-nutritional effects of v-c in this crop. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ghrelin improves vascular autophagy in rats with vascular calcification.

PubMed

Xu, Mingming; Liu, Lin; Song, Chenfang; Chen, Wei; Gui, Shuyan

2017-06-15

This study aimed to investigate whether ghrelin ameliorated vascular calcification (VC) through improving autophagy. VC model was induced by nicotine plus vitamin D 3 in rats and β-glycerophosphate in vascular smooth muscle cell (VSMC). Calcium deposition was detected by von Kossa staining or alizarin red S staining. ALP activity was also detected. Western blot was used to assess the protein expression. Ghrelin treatment attenuated the elevation of calcium deposition and ALP activity in VC model both in vivo and in vitro. Interesting, the protein levels of autophagy markers, LC3 and beclin1 were significantly upregulated by ghrelin in VC model. An autophagy inhibitor, 3-methyladenine blocks the ameliorative effect of ghrelin on VC. Furthermore, protein expressions of phosphate-AMPK were increased by ghrelin treatment both in calcified aorta and VSMC. The effect of ghrelin on autophagy induction and VC attenuation was prevented by AMPK inhibitor, compound C. Our results suggested that ghrelin improved autophagy through AMPK activation, which was resulted in VC amelioration. These data maybe throw light on prevention and therapy of VC. Copyright © 2016 Elsevier Inc. All rights reserved.

Cell damage and death by autoschizis in human bladder (RT4) carcinoma cells resulting from treatment with ascorbate and menadione.

PubMed

Gilloteaux, Jacques; Jamison, James M; Neal, Deborah R; Loukas, Marios; Doberzstyn, Theresa; Summers, Jack L

2010-05-01

A human bladder carcinoma cell line RT4 was sham-treated with buffer or treated with ascorbate (VC) alone, menadione alone (VK(3)), or a combination of ascorbate:menadione (VC+VK(3)) for 1, 2, and 4 h. Cytotoxic damage was found to be treatment-dependent in this sequence: VC+VK(3)>VC>VK(3)>sham. The combined treatment induced the greatest oxidative stress, with early tumor cell injury affecting the cytoskeletal architecture and contributing to the self-excisions of pieces of cytoplasm freed from organelles. Additional damage, including a reduction in cell size, organelle alterations, nuclear damage, and nucleic acid degradation as well as compromised lysosome integrity, is caused by reactivation of DNases and the redox cycling of VC or VC+VK(3). In addition, cell death caused by VC+VK(3) treatment as well as by prolonged VC treatment is consistent with cell demise by autoschizis, not apoptosis. This report confirms and complements previous observations about this new mode of tumor cell death. It supports the contention that a combination of VC+VK(3), also named Apatone, could be co-administered as a nontoxic adjuvant with radiation and/or chemotherapies to kill bladder tumor cells and other cancer cells without any supplementary risk or side effects for patients.

Artificially-built solid electrolyte interphase via surface-bonded vinylene carbonate derivative on graphite by molecular layer deposition

NASA Astrophysics Data System (ADS)

Chae, Seulki; Lee, Jeong Beom; Lee, Jae Gil; Lee, Tae-jin; Soon, Jiyong; Ryu, Ji Heon; Lee, Jin Seok; Oh, Seung M.

2017-12-01

Vinylene carbonate (VC) is attached in a ring-opened form on a graphite surface by molecular layer deposition (MLD) method, and its role as a solid electrolyte interphase (SEI) former is studied. When VC is added into the electrolyte solution of a graphite/LiNi0.5Mn1.5O4 (LNMO) full-cell, it is reductively decomposed to form an effective SEI on the graphite electrode. However, VC in the electrolyte solution has serious adverse effects due to its poor stability against electrochemical oxidation on the LNMO positive electrode. A excessive acid generation as a result of VC oxidation is observed, causing metal dissolution from the LNMO electrode. The dissolved metal ions are plated on the graphite electrode to destroy the SEI layer, eventually causing serious capacity fading and poor Coulombic efficiency. The VC derivative on the graphite surface also forms an effective SEI layer on the graphite negative electrode via reductive decomposition. The detrimental effects on the LNMO positive electrode, however, can be avoided because the bonded VC derivative on the graphite surface cannot move to the LNMO electrode. Consequently, the graphite/LNMO full-cell fabricated with the VC-attached graphite outperforms the cells without VC or with VC in the electrolyte, in terms of Coulombic efficiency and capacity retention.

Solid waste management of temple floral offerings by vermicomposting using Eisenia fetida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Akanksha, E-mail: bhuaks29@gmail.com; Jain, Akansha, E-mail: akansha007@rediffmail.com; Sarma, Birinchi K., E-mail: birinchi_ks@yahoo.com

2013-05-15

Highlights: ► Effective management of temple floral offerings using E. fetida. ► Physico-chemical properties in TW VC were better especially EC, C/N, C/P and TK. ► TW VC as plant growth promoter at much lower application rates than KW and FYW VC. - Abstract: Recycling of temple waste (TW) mainly comprising of floral offerings was done through vermitechnology using Eisenia fetida and its impact on seed germination and plant growth parameters was studied by comparing with kitchen waste (KW) and farmyard waste (FYW) vermicompost (VC). The worm biomass was found to be maximum in TW VC compared to KW andmore » FYW VCs at both 40 and 120 days old VCs. Physico-chemical analysis of worm-worked substrates showed better results in TW VC especially in terms of electrical conductivity, C/N, C/P and TK. 10% TW VC–water extract (VCE) showed stimulatory effect on germination percentage of chickpea seeds while KW and FYW VCE proved effective at higher concentration. Variation in growth parameters was also observed with change in the VC–soil ratio and TW VC showed enhanced shoot length, root length, number of secondary roots and total biomass at 12.5% VC compared to KW and FYW VC.« less

Crystal Structure of VC0702 at 2.0 angstrom: A Conserved Hypothetical Protein from Vibrio Cholerae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ni, Shuisong; Forouhar, Farhad; Bussiere, Dirksen E.

2006-06-01

VC0702, a conserved hypothetical protein of unknown function from Vibrio cholerae, resides in a putative three-gene operon containing the MbaA gene, which is involved in regulating formation of the extracellular matrix of biofilms in Vibrio cholerae. The VC0702 crystal structure has been determined at 2.0? and refined to Rwork=22.8% and Rfree=26.3%. VC0702 crystallized in an orthorhombic crystal lattice in the C2221 space group with dimensions of a=66.61 ?, b=88.118 ?, and c=118.35 ? with a homodimer in the asymmetric unit. VC0702 belongs to the Pfam DUF84 and COG1986 family of proteins. Sequence conservation within the DUF84 and COG1986 families wasmore » used to identify a conserved patch of surface residues that define a cleft and potential substrate-binding site in VC0702. The three-dimensional structure of VC0702 is similar to that of Mj0226 from Methanococcus janeshii, which has been identified as a novel NTPase. The NTP-binding site in Mj0226 is similarly located in comparison to the conserved patch of surface residues in VC0702. Furthermore, the NTP binds to MJ0226 in a cleft and deep cavity, features that are present in the VC0702 structure as well, suggesting that VC0702 may have a biochemical function involving NTP binding that is associated with a cellular function of regulating biofilm formation in Vibrio cholerae.« less

Active Site and Remote Contributions to Catalysis in Methylthioadenosine Nucleosidases

DOE PAGES

Thomas, Keisha; Cameron, Scott A.; Almo, Steven C.; ...

2015-03-25

5'-Methylthioadenosine/S-adenosyl-l-homocysteine nucleosidases (MTANs) catalyze the hydrolysis of 5'-methylthioadenosine to adenine and 5-methylthioribose. The amino acid sequences of the MTANs from Vibrio cholerae (VcMTAN) and Escherichia coli (EcMTAN) are 60% identical and 75% similar. Protein structure folds and kinetic properties are similar. However, binding of transition-state analogues is dominated by favorable entropy in VcMTAN and by enthalpy in EcMTAN. Catalytic sites of VcMTAN and EcMTAN in contact with reactants differ by two residues; Ala113 and Val153 in VcMTAN are Pro113 and Ile152, respectively, in EcMTAN. Here, we mutated the VcMTAN catalytic site residues to match those of EcMTAN in anticipation ofmore » altering its properties toward EcMTAN. Inhibition of VcMTAN by transition-state analogues required filling both active sites of the homodimer. However, in the Val153Ile mutant or double mutants, transition-state analogue binding at one site caused complete inhibition. Therefore, a single amino acid, Val153, alters the catalytic site cooperativity in VcMTAN. The transition-state analogue affinity and thermodynamics in mutant VcMTAN became even more unlike those of EcMTAN, the opposite of expectations from catalytic site similarity; thus, catalytic site contacts in VcMTAN are unable to recapitulate the properties of EcMTAN. X-ray crystal structures of EcMTAN, VcMTAN, and a multiple-site mutant of VcMTAN most closely resembling EcMTAN in catalytic site contacts show no major protein conformational differences. In conclusion, the overall protein architectures of these closely related proteins are implicated in contributing to the catalytic site differences.« less

Active Site and Remote Contributions to Catalysis in Methylthioadenosine Nucleosidases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, Keisha; Cameron, Scott A.; Almo, Steven C.

5'-Methylthioadenosine/S-adenosyl-l-homocysteine nucleosidases (MTANs) catalyze the hydrolysis of 5'-methylthioadenosine to adenine and 5-methylthioribose. The amino acid sequences of the MTANs from Vibrio cholerae (VcMTAN) and Escherichia coli (EcMTAN) are 60% identical and 75% similar. Protein structure folds and kinetic properties are similar. However, binding of transition-state analogues is dominated by favorable entropy in VcMTAN and by enthalpy in EcMTAN. Catalytic sites of VcMTAN and EcMTAN in contact with reactants differ by two residues; Ala113 and Val153 in VcMTAN are Pro113 and Ile152, respectively, in EcMTAN. Here, we mutated the VcMTAN catalytic site residues to match those of EcMTAN in anticipation ofmore » altering its properties toward EcMTAN. Inhibition of VcMTAN by transition-state analogues required filling both active sites of the homodimer. However, in the Val153Ile mutant or double mutants, transition-state analogue binding at one site caused complete inhibition. Therefore, a single amino acid, Val153, alters the catalytic site cooperativity in VcMTAN. The transition-state analogue affinity and thermodynamics in mutant VcMTAN became even more unlike those of EcMTAN, the opposite of expectations from catalytic site similarity; thus, catalytic site contacts in VcMTAN are unable to recapitulate the properties of EcMTAN. X-ray crystal structures of EcMTAN, VcMTAN, and a multiple-site mutant of VcMTAN most closely resembling EcMTAN in catalytic site contacts show no major protein conformational differences. In conclusion, the overall protein architectures of these closely related proteins are implicated in contributing to the catalytic site differences.« less

Effect of the fungus Pochonia chlamydosporia on Echinostoma paraensei (Trematoda: Echinostomatidae).

PubMed

Lelis, Rosane Teixeira; Braga, Fabio Ribeiro; de Carvalho, Lorendane Millena; de Paula, Alessandra Teixeira; Araujo, Juliana Milani; Fausto, Mariana Costa; Junior, Arnaldo Maldonado; Rodrigues, João Victor Facchini; de Freitas Soares, Filippe Elias; Garcia, Juberlan Silva; de Araújo, Jackson Victor

2014-11-01

Echinostoma paraensei is a trematode of the genus Echinostoma that causes echinostomiasis in humans. The objectives of this study were to: evaluate the ovicidal activity of the nematophagous fungus Pochonia chlamydosporia (VC1 and VC4) on a solid medium 2% water-agar (2% WA) against E. paraensei eggs (assay A); evaluate ovicidal effect (destruction of eggs) of the isolate VC4 in supplemented culture media (assay B); and evaluate the ovicidal ability of the crude extract (VC4) on E. paraensei eggs (assay C). Eggs of E. paraensei (assay A) were placed in Petri dishes containing 2% WA with an isolate of the fungus P. chlamydosporia (VC1 and VC4) grown for 10 days, and without fungus as a control and evaluated regarding their destruction. In assay B, eggs of E. paraensei were placed in Petri dishes with different supplemented culture media and with VC4 isolate and the destruction of eggs was examined at the end of 25 days of interaction. In assay C, effects of the crude extract of P. chlamydosporia (VC4) on eggs were evaluated at the end of 7 days. In assay A, there was no difference (p>0.05) in ovicidal activity among the tested isolates (VC1 and VC4); however, the highest percentage for ovicidal activity (type 3 effect) was demonstrated by the isolate VC4. In assay B, the culture medium starch-agar showed the best results for the destruction of the eggs, with a percentage of 46.6% at the end of the assay. In assay C, the crude extract of VC4 was effective in the destruction of E. paraensei eggs, with a percentage reduction of 53%. The results of this study demonstrate that a rich culture medium with a greater availability of carbon and nitrogen may interfere directly in the predatory characteristics of ovicidal fungi. Copyright © 2014 Elsevier B.V. All rights reserved.

Long-term immunogenicity of an initial booster dose of an inactivated, Vero cell culture-derived Japanese encephalitis vaccine (JE-VC) and the safety and immunogenicity of a second JE-VC booster dose in children previously vaccinated with an inactivated, mouse brain-derived Japanese encephalitis vaccine.

PubMed

Yun, Ki Wook; Lee, Hoan Jong; Park, Ji Young; Cho, Hye-Kyung; Kim, Yae-Jean; Kim, Kyung-Hyo; Kim, Nam Hee; Hong, Young Jin; Kim, Dong Ho; Kim, Hwang Min; Cha, Sung-Ho

2018-03-07

This study was performed with the aim of determining the long-term immunogenicity of an inactivated, Vero cell culture-derived Japanese encephalitis (JE) vaccine (JE-VC) and an inactivated, mouse brain-derived JE vaccine (JE-MB) after the 1st booster dose at 2 years of age, as well as the safety and immunogenicity of the 2nd booster dose of JE-VC at 6 years of age, in children primed and given a 1st booster dose of either JE-VC or JE-MB. In this multicenter, open-label clinical trial, the study population consisted of healthy Korean children (aged 6 years) who participated in the previous JE vaccine trial. All subjects were subcutaneously vaccinated once for the booster immunization with Boryung Cell Culture Japanese Encephalitis Vaccine® (JE-VC). Approximately 4 years after the 1st booster dose of JE-VC, the seroprotection rate (SPR) and geometric mean titer (GMT) of the neutralizing antibody were 100% and 1113.8, respectively. In children primed and given a 1st booster dose of JE-MB, the SPR and GMT were 88.5% and 56.3, respectively. After the 2nd booster dose of JE-VC, all participants primed and given a 1st booster dose of either JE-MB or JE-VC were seroprotective against JE virus. The GMT of the neutralizing antibody was higher in children primed and given a 1st booster dose of JE-VC (8144.1) than in those primed and given a 1st booster dose of JE-MB (942.5) after the vaccination (p < 0.001). In addition, the 2nd booster dose of JE-VC showed a good safety profile with no serious vaccine-related adverse events. The 1st booster dose of JE-VC and JE-MB showed long-term immunogenicity of at least 4 years, and the 2nd booster dose of JE-VC showed a good safety and immunogenicity profile in children primed and given a 1st booster dose of either JE-VC or JE-MB. ClinicalTtrials.gov Identifier: NCT02532569. Copyright © 2018 Elsevier Ltd. All rights reserved.

Clocked combustor can array

DOEpatents

Kim, Won-Wook; McMahan, Kevin Weston; Srinivasan, Shiva Kumar

2017-01-17

The present application provides a clocked combustor can array for coherence reduction in a gas turbine engine. The clocked combustor can array may include a number of combustor cans positioned in a circumferential array. A first set of the combustor cans may have a first orientation and a second set of the combustor cans may have a second orientation.

Quality control of climatological time series in the province of macerata (adriatic side of central italy)

NASA Astrophysics Data System (ADS)

Gentilucci, Matteo; Bisci, Carlo; Fazzini, Massimiliano; Tognetti, Danilo

2016-04-01

The analysis is focused on more than 100 meteorological recording stations located in the Province of Macerata (Marche region, Adriatic side of Central Italy) and in its neighbours; it aims to check the time series of their climatological data (temperatures and precipitations), covering about one century of observations, in order to remove or rectify any errors. This small area (about 2.800Km2) features many different climate types, because of its varied topography ranging, moving westward, from the Adriatic coast to the Appennines (over 2.100m of altitude). In this irregular context, it is difficult to establish a common procedure for each sector; therefore, it has been followed the general guidelines of the WMO, with some important difference (mostly in the method). Data are classified on the basis of validation codes (VC): missing datum (VC=-1), correct or verified datum (VC=0), datum under investigation (VC=1), datum removed after the analysis (VC=2), datum reconstructed through interpolation or by estimating the errors of digitization (VC=3). The first step was the "Logical Control", consisting in the investigation of gross errors of digitization: the data found in this phase of the analysis has been removed without any other control (VC=2). The second step, represented by the "Internal Consistency Check", leads to the elimination (VC=2) of all the data out of range, estimated on the basis of the climate zone for each investigated variable. The third one is the "Tolerance Test", carried out comparing each datum with the historical record it belongs to, in order to apply this test, the normal distribution of data has been evaluated. The "Tolerance Test" usually defines only suspect data (VC=1) to be verified with further tests, such as the "Temporal Consistency" and the "Spatial Consistency". The "Temporal Consistency" allows an evaluation of the time sequence of data, setting a specified range for each station basing upon its historical records. Data out of range have been considered under investigation (VC=1). Data are finally compared with the ones contemporaneously recorded in a set of neighboring meteorological stations through the "Spatial Consistency" test, thus eliminating every suspicious datum (recoded VC=2 or VC=0, depending upon the results of this analysis). This procedure uses a series of different statistic steps to avoid uncertainties: at its end, all the investigated data are either accepted (VC=0) or refused (VC=2). Refused and missing data (VC=-1 and VC=2) have been reconstructed through interpolation using co-kriging techniques (assigning VC=3), when necessary, in the final stage of the process. All the above procedure has been developed using a database managing software in a GIS (ESRI ArcGIS ®) environment. The refused data are 1.286 in 77.021 (1,67%) for the precipitations and 375 in 1.821.054 for the temperatures (0,02%).

Experimental clean combustor program; noise measurement addendum, Phase 2

NASA Technical Reports Server (NTRS)

Emmerling, J. J.; Bekofske, K. L.

1976-01-01

Combustor noise measurements were performed using wave guide probes. Test results from two full scale annular combustor configurations in a combustor test rig are presented. A CF6-50 combustor represented a current design, and a double annular combustor represented the advanced clean combustor configuration. The overall acoustic power levels were found to correlate with the steady state heat release rate and inlet temperature. A theoretical analysis for the attenuation of combustor noise propagating through a turbine was extended from a subsonic relative flow condition to include the case of supersonic flow at the discharge side. The predicted attenuation from this analysis was compared to both engine data and extrapolated component combustor data. The attenuation of combustor noise through the CF6-50 turbine was found to be greater than 14 dB by both the analysis and the data.

Numerical investigation of the influence of elevated turbulence levels on the cooling effectiveness of an anti-vortex hole geometry

NASA Astrophysics Data System (ADS)

Repko, Timothy William

A novel film cooling hole geometry for use in gas turbine engines has been investigated numerically by solving the Reynolds Averaged Navier-Stokes equations in a commercial CFD code (STAR-CCM+) with varying turbulence intensity and length scale using the k-o SST turbulence model. Both steady and unsteady results were considered in order to investigate the effects of freestream turbulence intensity and length scale on this novel anti-vortex hole (AVH) concept. The AVH geometry utilizes two side holes, one on each side of the main hole, to attempt to mitigate the vorticity from the jet from the main hole. The AVH concept has been shown by past research to provide a substantial improvement over conventional film cooling hole designs. Past research has been limited to low turbulence intensity and small length scales that are not representative of the turbulent flow exiting the combustor. Three turbulence intensities (Tu = 5, 10 and 20%) and three length scales normalized by the main cooling hole diameter (Λ x/dm = 1, 3, 6) were considered in this study for a total of nine turbulence conditions. The highest intensity, largest length scale turbulence case (Tu = 20, Λx/dm = 6) is considered most representative of engine conditions and was shown to have the best cooling performance. Results show that the turbulence in the hot gases exiting the combustor can aid in the film cooling for the AVH geometry at high blowing ratios (BR = 2.0), where the blowing ratio is essentially the ratio of the jet-to-mainstream mass flux ratios. Length scale was shown to have an insignificant effect on the cooling performance at low turbulence intensity and a moderate effect at higher turbulence intensities. The adiabatic film cooling effectiveness was shown to increase as the turbulence intensity was elevated. The convective heat transfer coefficient was also shown to increase at the turbulence intensity was elevated. An increase in the heat transfer coefficient is a deleterious effect and must be weighed against the improvements in the adiabatic cooling effectiveness. The net heat flux reduction (NHFR) is the parameter used to quantify the net benefit of film cooling. As a general trend, the NHFR was shown to increase with the turbulence intensity in all cases.

Vortex dynamics studies in supersonic flow

NASA Astrophysics Data System (ADS)

Vergine, Fabrizio

This dissertation covers the study of selected vortex interaction scenarios both in cold and high enthalpy reacting flows. Specifically, the experimental results and the analysis of the flowfields resulting from two selected supersonic vortex interaction modes in a Mach 2.5 cold flow are presented. Additionally, the experiment design, based on vortex dynamics concepts, and the reacting plume survey of two pylon injectors in a Mach 2.4 high enthalpy flow are shown. All the cold flow experiments were conducted in the supersonic wind tunnel of the Aerodynamics Research Center at the University of Texas at Arlington. A strut injector equipped with specified ramp configurations was designed and used to produce the flowfields of interest. The reacting flow experiments were conducted in the the Expansion Tube Facility located in the High Temperature Gasdynamics Laboratory of Stanford University. A detailed description of the supersonic wind tunnel, the instrumentation, the strut injector and the supersonic wake flow downstream is shown as part of the characterization of the facility. As Stereoscopic Particle Image Velocimetry was the principal flow measurement technique used in this work to probe the streamwise vortices shed from ramps mounted on the strut, this dissertation provides a deep overview of the challenges and the application of the aforementioned technique to the survey of vortical flows. Moreover, the dissertation provides the comprehensive analysis of the mean and fluctuating velocity flowfields associated with two distinct vortex dynamics scenarios, as chosen by means of the outcomes of the simulations of a reduced order model developed in the research group. Specifically, the same streamwise vortices (strength, size and Reynolds number) were used experimentally to investigate both a case in which the resulting dynamics evolve in a vortex merging scenario and a case where the merging process is voluntarily avoided in order to focus the analysis on the fundamental differences associated with the amalgamation processes alone. The results from the mean flow highlight major differences between the two cases and will justify the use of the inviscid reduced order model used to predict the main flow physics. The analysis of the turbulence quantities based on concepts borrowed from incompressible turbulence theory explains interesting features of the fluctuating flowfields, suggesting that turbulence associated with the inspected flow conditions is essentially incompressible. Once the interactions among the vortical structures in cold flow were assessed, these vortex dynamics concepts were probed in a reacting environment. The dissertation describes the design phase of two pylon injectors based on the prediction capabilities of the aforementioned model. Then, the results of a set of combustion experiments conducted utilizing hydrogen fuel injected into Mach 2.4, high-enthalpy (2.8˜MJ/kg) air flow are discussed. The results show that, for the heat release levels considered in this study, the morphology of the plume and its evolution is very similar to the results produced by the code, enabling an interpretation of the phenomena based on vortex dynamics considerations. The persistence of the streamwise vortical structures created by the selected ramp configurations is shown together with the effectiveness of the coherent structures in successfully anchoring the flame very close to the injection point. The work shows the possibility of a new approach in the design of injection strategies (i.e., not limited to injection devices) suitable for adoption in scramjet combustors based on the ability to predict, with basic vortex dynamics concepts and a highly reduced computational cost, the main features of flows of technological interest.

Broad specification fuels combustion technology program

NASA Technical Reports Server (NTRS)

Dodds, W. J.; Ekstedt, E. E.

1984-01-01

Design and development efforts to evolve promising aircraft gas turbine combustor configurations for burning broadened-properties fuels were discussed. Design and experimental evaluations of three different combustor concepts in sector combustor rig tests was conducted. The combustor concepts were a state of the art single-annular combustor, a staged double-annular combustor, and a short single-annular combustor with variable geometry to control primary zone stoichiometry. A total of 25 different configurations of the three combustor concepts were evaluated. Testing was conducted over the full range of CF6-80A engine combustor inlet conditions, using four fuels containing between 12% and 14% hydrogen by weight. Good progress was made toward meeting specific program emissions and performance goals with each of the three combustor concepts. The effects of reduced fuel hydrogen content, including increased flame radiation, liner metal temperature, smoke, and NOx emissions were documented. The most significant effect on the baseline combustor was a projected 33% life reduction, for a reduction from 14% to 13% fuel hydrogen content, due to increased liner temperatures.

Radial midframe baffle for can-annular combustor arrangement having tangentially oriented combustor cans

DOEpatents

Rodriguez, Jose L.

2015-09-15

A can-annular gas turbine engine combustion arrangement (10), including: a combustor can (12) comprising a combustor inlet (38) and a combustor outlet circumferentially and axially offset from the combustor inlet; an outer casing (24) defining a plenum (22) in which the combustor can is disposed; and baffles (70) configured to divide the plenum into radial sectors (72) and configured to inhibit circumferential motion of compressed air (16) within the plenum.

Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

2012-01-01

Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to a normally unstable high-power condition, thus enabling the high-power condition.

Scramjet Combustor Characteristics at Hypervelocity Condition over Mach 10 Flight

NASA Astrophysics Data System (ADS)

Takahashi, M.; Komuro, T.; Sato, K.; Kodera, M.; Tanno, H.; Itoh, K.

2009-01-01

To investigate possibility of reduction of a scramjet combustor size without thrust performance loss, a two-dimensional constant-area combustor of a previous engine model was replaced with the one with 23% lower-height. With the application of the lower-height combustor, the pressure in the combustor becomes 50% higher and the combustor length for the optimal performance becomes 43% shorter than the original combustor. The combustion tests of the modified engine model were conducted using a large free-piston driven shock tunnel at flow conditions corresponding to the flight Mach number from 9 to 14. CFD was also applied to the engine internal flows. The results showed that the mixing and combustion heat release progress faster to the distance and the combustor performance similar to that of the previous engine was obtained with the modified engine. The reduction of the combustor size without the thrust performance loss is successfully achieved by applying the lower-height combustor.

Experimental clean combustor program, phase 1

NASA Technical Reports Server (NTRS)

Bahr, D. W.; Gleason, C. C.

1975-01-01

Full annular versions of advanced combustor designs, sized to fit within the CF6-50 engine, were defined, manufactured, and tested at high pressure conditions. Configurations were screened, and significant reductions in CO, HC, and NOx emissions levels were achieved with two of these advanced combustor design concepts. Emissions and performance data at a typical AST cruise condition were also obtained along with combustor noise data as a part of an addendum to the basic program. The two promising combustor design approaches evolved in these efforts were the Double Annular Combustor and the Radial/Axial Combustor. With versions of these two basic combustor designs, CO and HC emissions levels at or near the target levels were obtained. Although the low target NOx emissions level was not obtained with these two advanced combustor designs, significant reductions were relative to the NOx levels of current technology combustors. Smoke emission levels below the target value were obtained.

Treatment of Severe Edema in Children with Nephrotic Syndrome with Diuretics Alone — A Prospective Study

PubMed Central

Kapur, Gaurav; Valentini, Rudolph P.; Imam, Abubakr A.; Mattoo, Tej K.

2009-01-01

Background and objective: Severe edema in children with nephrotic syndrome (NS) may be associated with volume contraction (VC) or volume expansion (VE). Usually, severe edema in children is treated with intravenous (IV) albumin and diuretics, which is appropriate for VC patients. However, in VE patients, this can precipitate fluid overload. The objective of this study was to evaluate treatment of severe edema in NS with diuretics alone. Design, setting, participants, & measurements: Thirty NS patients with severe edema were enrolled in this prospective study in two phases. VC was diagnosed based on fractional excretion of sodium (FeNa) <1%. VC patients received IV albumin and furosemide. VE patients received IV furosemide and oral spironolactone. On the basis of phase 1 observations, FeNa <0.2% identified VC in 20 phase 2 patients. Results: All phase 1 patients had FeNa <1%. Phase 1 patients when reanalyzed based on a FeNa cutoff of 0.2%; it was noted that VC patients had higher BUN, BUN/creatinine ratio, urine osmolality, and lower FeNa and urine sodium compared with VE patients. Similar results were observed in phase 2. VC patients had significantly higher renin, aldosterone, and antidiuretic hormone levels. In phase 2, 11 VE patients received diuretics alone and 9 VC patients received albumin and furosemide. There was no difference in hospital stay and weight loss in VC and VE groups after treatment. Conclusions: FeNa is useful in distinguishing VC versus VE in NS children with severe edema. The use of diuretics alone in VE patients is safe and effective. PMID:19406963

Perineuronal nets labeled by monoclonal antibody VC1.1 ensheath interneurons expressing parvalbumin and calbindin in the rat amygdala

PubMed Central

McDonald, Alexander J.; Hamilton, Patricia G.; Barnstable, Colin J.

2018-01-01

Perineuronal nets (PNNs) are specialized condensations of extracellular matrix that ensheath particular neuronal subpopulations in the brain and spinal cord. PNNs regulate synaptic plasticity, including the encoding of fear memories by the amygdala. The present immunohistochemical investigation studied PNN structure and distribution, as well as the neurochemistry of their ensheathed neurons, in the rat amygdala using monoclonal antibody VC1.1, which recognizes a glucuronic acid 3-sulfate glycan associated with PNNs in the cerebral cortex. VC1.1+ PNNs surrounded the cell bodies and dendrites of a subset of nonpyramidal neurons in cortex-like portions of the amygdala (basolateral amygdalar complex, cortical nuclei, nucleus of the lateral olfactory tract, and amygdalohippocampal region). There was also significant neuropilar VC1.1 immunoreactivity whose density varied in different amygdalar nuclei. Cell counts in the basolateral nucleus revealed that virtually all neurons ensheathed by VC1.1+ PNNs were parvalbumin-positive (PV+) interneurons, and these VC1.1+/PV+ cells constituted 60% of all PV+ interneurons, including all of the larger PV+ neurons. Approximately 70% of VC1.1+ neurons were calbindin-positive (CB+), and these VC1.1+/CB+ cells constituted about 40% of all CB+ neurons. Colocalization of VC1.1 with Vicia villosa agglutinin (VVA) binding, which stains terminal N-acetylgalactosamines, revealed that VC1.1+ PNNs were largely a subset of VVA+ PNNs. This investigation provides baseline data regarding PNNs in the rat which should be useful for future studies of their function in this species. PMID:29094304

Anaerobic degradation of vinyl chloride in aquifer microcosms.

PubMed

Smits, Theo H M; Assal, Antoine; Hunkeler, Daniel; Holliger, Christof

2011-01-01

The anaerobic degradation potential at a chloroethene-contaminated site was investigated by operating two anoxic column aquifer microcosms enriched in iron(III). One column was fed with vinyl chloride (VC) only (column A) and one with VC and acetate (column B). In column A, after about 600 pore volume exchanges (PVEs), VC started to disappear and reached almost zero VC recovery in the effluent after 1000 PVEs. No formation of ethene was observed. In column B, effluent VC was almost always only a fraction of influent VC. Formation of ethene was observed after 800 PVEs and started to become an important degradation product after 1550 PVEs. However, ethene was never observed in stoichiometric amounts compared with disappeared VC. The average stable isotope enrichment factor for VC disappearance in column A was determined to be -4.3‰. In column B, the isotope enrichment factor shifted from -10.7 to -18.5‰ concurrent with an increase in ethene production. Batch microcosms inoculated with column material showed similar isotope enrichment factors as the column microcosms. These results indicated that two degradation processes occurred, one in column A and two in parallel in column B with increasing importance of reductive dechlorination with time. This study suggests that in addition to reductive dechlorination, other degradation processes such as anaerobic oxidation should be taken into account when evaluating natural attenuation of VC and that isotope analysis can help to differentiate between different pathways of VC removal. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

Effect of altered arterial perfusion pressure on vascular conductance and muscle blood flow dynamic response during exercise in humans.

PubMed

Villar, Rodrigo; Hughson, Richard L

2013-03-01

Changes in vascular conductance (VC) are required to counter changes in muscle perfusion pressure (MPP) to maintain muscle blood flow (MBF) during exercise. We investigated the recruitment of VC as a function of peak VC measured in three body positions at two different work rates to test the hypothesis that adaptations in VC compensated changes in MPP at low-power output (LPO), but not at high-power output (HPO). Eleven healthy volunteers exercised at LPO and HPO (repeated plantar flexion contractions at 20-30% maximal voluntary contraction, respectively) in horizontal (HOR), 35° head-down tilt (HDT), and 45° head-up tilt (HUT). Muscle blood flow velocity and popliteal diameter were measured by ultrasound to determine MBF, and VC was estimated by dividing MBF flow by MPP. Peak VC was unaffected by body position. The rates of increase in MBF and VC were significantly faster in HUT and slower in HDT than HOR, and rates were faster in LPO than HPO. During LPO exercise, the increase in, and steady-state values of, MBF were less for HUT and HDT than HOR; the increase in VC was less in HUT than HOR and HDT. During HPO exercise, MBF in the HDT was reduced compared with HOR and HUT, even though VC reached 92% VC peak, which was greater than HOR, which was, in turn, greater than HUT. Reduced MBF during HPO HDT exercise had the functional consequence of a significant increase in muscle electromyographic index, revealing the effects of MPP on O2 delivery during exercise.

Fuel cell system with combustor-heated reformer

DOEpatents

Pettit, William Henry

2000-01-01

A fuel cell system including a fuel reformer heated by a catalytic combustor fired by anode effluent and/or fuel from a liquid fuel supply providing fuel for the fuel cell. The combustor includes a vaporizer section heated by the combustor exhaust gases for vaporizing the fuel before feeding it into the combustor. Cathode effluent is used as the principle oxidant for the combustor.

The effect of incomplete fuel-air mixing on the lean blowout limit, lean stability limit and NO(x) emissions in lean premixed gas turbine combustors

NASA Technical Reports Server (NTRS)

Shih, W.-P.; Lee, J. G.; Santavicca, D. A.

1994-01-01

Gas turbine engines for both land-based and aircraft propulsion applications are facing regulations on NOx emissions which cannot be met with current combustor technology. A number of alternative combustor strategies are being investigated which have the potential capability of achieving ultra-low NOx emissions, including lean premixed combustors, direct injection combustors, rich burn-quick quench-lean burn combustors and catalytic combustors. The research reported in this paper addresses the effect of incomplete fuel-air mixing on the lean limit performance and the NOx emissions characteristics of lean premixed combustors.

HSCT Sector Combustor Evaluations for Demonstration Engine

NASA Technical Reports Server (NTRS)

Greenfield, Stuart; Heberling, Paul; Kastl, John; Matulaitis, John; Huff, Cynthia

2004-01-01

In LET Task 10, critical development issues of the HSCT lean-burn low emissions combustor were addressed with a range of engineering tools. Laser diagnostics and CFD analysis were applied to develop a clearer understanding of the fuel-air premixing process and premixed combustion. Subcomponent tests evaluated the emissions and operability performance of the fuel-air premixers. Sector combustor tests evaluated the performance of the integrated combustor system. A 3-cup sector was designed and procured for laser diagnostics studies at NASA Glenn. The results of these efforts supported the earlier selection of the Cyclone Swirler as the pilot stage premixer and the IMFH (Integrated Mixer Flame Holder) tube as the main stage premixer of the LPP combustor. In the combustor system preliminary design subtask, initial efforts to transform the sector combustor design into a practical subscale engine combustor met with significant challenges. Concerns about the durability of a stepped combustor dome and the need for a removable fuel injection system resulted in the invention and refinement of the MRA (Multistage Radial Axial) combustor system in 1994. The MRA combustor was selected for the HSR Phase II LPP subscale combustor testing in the CPC Program.

Myosin Vc Interacts with Rab32 and Rab38 Proteins and Works in the Biogenesis and Secretion of Melanosomes*

PubMed Central

Bultema, Jarred J.; Boyle, Judith A.; Malenke, Parker B.; Martin, Faye E.; Dell'Angelica, Esteban C.; Cheney, Richard E.; Di Pietro, Santiago M.

2014-01-01

Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion. PMID:25324551

Activity of the nematophagous fungi Pochonia chlamydosporia, Duddingtonia flagrans and Monacrosporium thaumasium on egg capsules of Dipylidium caninum.

PubMed

Araujo, Juliana Milani; de Araújo, Jackson Victor; Braga, Fabio Ribeiro; Carvalho, Rogério Oliva; Ferreira, Sebastião Rodrigo

2009-12-03

Nematophagous fungi are potential biological control agents of helminths. The in vitro ovicidal effect of four isolates of the nematophagous fungi Pochonia chlamydosporia (VC1 and VC4), Duddingtonia flagrans (AC001) and Monacrosporium thaumasium (NF34) was evaluated on egg capsules of Dipylidium caninum, a cestode parasite of dogs, cats and humans. One thousand egg capsules of D. caninum were plated on 2% water-agar with the grown isolates and control without fungus. The ovicidal activity of these fungi was evaluated 5, 10 and 15 days after incubation. Only P. chlamydosporia showed ovicidal activity (p<0.05) on D. caninum egg capsules, of 19.6% (VC1) and 20% (VC4) on the 5th day; 44.2% (VC1) and 31.5% (VC4) on the 10th day; and 49.2% (VC1) and 41.9% (VC4) on the 15th day. D. flagrans and M. thaumasium caused no morphological damage to egg capsules. The results demonstrated that P. chlamydosporia was in vitro effective against capsules and eggs of D. caninum, and can be considered as a potential biological control agent for this helminth.

Effect of various halide salts on the incompatibility of cyanocobalamin and ascorbic acid in aqueous solution.

PubMed

Ichikawa, Makoto; Ide, Nagatoshi; Shiraishi, Sumihiro; Ono, Kazuhisa

2005-06-01

Combination of cyanocobalamin (VB12) and ascorbic acid (VC) has been widely seen in pharmaceutical products and dietary supplements. However, VB12 has been reported that its behavior in stability in aqueous solution is quite different when VC is mixed. In the present study, we examined the stabilities of these vitamins in acetate buffer (pH 4.8) using high performance liquid chromatography. Degradation of VB12 was not observed in the absence of VC in the buffer. However, when VC was mixed in the VB12 solution, VB12 concentrations decreased in accordance with VC degradation. VB12 and VC degradations were inhibited by adding sodium halides to acetate buffer at pH 4.8. These stabilization effects were also observed in the range from pH 3.5 to 5.3 and by adding potassium, magnesium, and calcium halides. Furthermore, our data demonstrated that increases in the halide anion concentrations and atomic number (Cl-

Exposure to Vinyl Chloride and Its Influence on Western Diet-Induced Cardiac Remodeling.

PubMed

Liang, Yaqin; Lang, Anna L; Zhang, Jian; Chen, Jing; Wang, Kai; Chen, Liya; Beier, Juliane I; Qian, Yan; Cai, Lu

2018-06-18

Obesity, usually caused by high fat diets (HFD), is a major public health issue worldwide, causing obesity associated cardiomyopathy. Moreover, the environmental toxicant vinyl chloride (VC) can exacerbate HFD-induced fatty liver disease. However, whether VC serves to enhance obesity-associated cardiomyopathy remains unclear. This study aims to investigate the interaction of western diet (WD) containing relatively low fat (42%) with VC on cardiac remodeling and its underling mechanisms. Adult male C57BL/6J mice were exposed to WD coinhalation of low-dose VC (<1 ppm/d) for 12 weeks. Results showed that WD feeding for 12 weeks caused slight cardiac systolic dysfunction without significant hypertrophy or fibrosis, even with VC. Nevertheless, WD upregulated NF-κB function and expression of IL-1β and PAI-1, while VC showed no significant impact on these effects. In contrast, WD together with VC significantly increased the expression of CHOP and TGF-β1, key markers for endoplasmic reticulum stress and profibrotic cytokine, respectively. In summary, exposure to low-dose of environmental toxicant VC while a WD is consumed for a relatively short time does not have significant impact on cardiac remodeling except for a mild systolic dysfunction of the heart.

Influence of supplementing vitamin C to yearling steers fed a high sulfur diet during the finishing period on meat color, tenderness and protein degradation, and fatty acid profile of the longissimus muscle.

PubMed

Pogge, Danielle J; Lonergan, Steven M; Hansen, Stephanie L

2014-08-01

The objective was to determine the influence of vitamin C (VC) supplemented for approximately 102 d during the finishing period on color, tenderness, and fatty acid profile of longissimus thoracis (LT; n=136) from steers fed a 0.55% sulfur diet. Treatments included 4 supplemental VC concentrations: 1) 0 (CON), 2) 5 (5VC), 3) 10 (10VC), or 4) 20 (20VC) gVC·h(-1)∙d(-1) in a common diet. Increasing supplemental VC decreased (P<0.01) L*, but increased (P<0.01) vitamin E and tended to increase (P≤0.07) calcium and iron content of steaks. No VC (P≥0.25) effect was noted for WBSF, calpain-1 autolysis, troponin T degradation, or most fatty acid profiles. A quadratic effect (P≤0.03) was observed for cholesterol and CLA content of LT. Under the conditions of our study, supplementing VC to steers fed a 0.55% sulfur diet late in the finishing period did not influence color or tenderness, but increased the vitamin E content. Copyright © 2014 Elsevier Ltd. All rights reserved.

The in vitro antitumor activity of vitamins C and K3 against ovarian carcinoma.

PubMed

von Gruenigen, Vivian E; Jamison, James M; Gilloteaux, Jacques; Lorimer, Heather E; Summers, Marcia; Pollard, Robert R; Gwin, Carley A; Summers, Jack L

2003-01-01

The objective was to evaluate the cytotoxic effect and mechanism of action of vitamins C (VC) and K3 (VK3) on ovarian carcinoma. Cytotoxicity assays were performed on ovarian cancer cell lines with VC, VK3 or a VC/VK3 combination. FIC index was employed to evaluate synergism. Flow cytometry was accomplished at 90% cytotoxic doses. Light, transmission electron microscopy and DNA isolation were performed. Antitumor activity was exhibited by both VC, VK3 and VC/VK3. VC/VK3 demonstrated synergistic activity. VC/VK3 may induce a G1 block in the cell cycle. Combined vitamin treatment resulted in cells that maintain apparently intact nuclei while extruding pieces of organelle-free cytoplasm. Degradation of chromosomal DNA was observed. Cell death (autoschizis) displayed characteristics of both apoptosis and necrosis. The cytotoxic effects observed may enable vitamins C and K3 to play an adjuvant role in the treatment of ovarian cancer.

Cheating prevention in visual cryptography.

PubMed

Hu, Chih-Ming; Tzeng, Wen-Guey

2007-01-01

Visual cryptography (VC) is a method of encrypting a secret image into shares such that stacking a sufficient number of shares reveals the secret image. Shares are usually presented in transparencies. Each participant holds a transparency. Most of the previous research work on VC focuses on improving two parameters: pixel expansion and contrast. In this paper, we studied the cheating problem in VC and extended VC. We considered the attacks of malicious adversaries who may deviate from the scheme in any way. We presented three cheating methods and applied them on attacking existent VC or extended VC schemes. We improved one cheat-preventing scheme. We proposed a generic method that converts a VCS to another VCS that has the property of cheating prevention. The overhead of the conversion is near optimal in both contrast degression and pixel expansion.

Contact inspection of Si nanowire with SEM voltage contrast

NASA Astrophysics Data System (ADS)

Ohashi, Takeyoshi; Yamaguchi, Atsuko; Hasumi, Kazuhisa; Ikota, Masami; Lorusso, Gian; Horiguchi, Naoto

2018-03-01

A methodology to evaluate the electrical contact between nanowire (NW) and source/drain (SD) in NW FETs was investigated with SEM voltage contrast (VC). The electrical defects were robustly detected by VC. The validity of the inspection result was verified by TEM physical observations. Moreover, estimation of the parasitic resistance and capacitance was achieved from the quantitative analysis of VC images which were acquired with different scan conditions of electron beam (EB). A model considering the dynamics of EB-induce charging was proposed to calculate the VC. The resistance and capacitance can be determined by comparing the model-based VC with experimentally obtained VC. Quantitative estimation of resistance and capacitance would be valuable not only for more accurate inspection, but also for identification of the defect point.

Rich burn combustor technology at Pratt and Whitney

NASA Technical Reports Server (NTRS)

Lohmann, Robert P.; Rosfjord, T. J.

1992-01-01

The topics covered include the following: near term objectives; rich burn quick quench combustor (RBQC); RBQC critical technology areas; cylindrical RBQQ combustor rig; modular RBQQ combustor; cylindrical rig objectives; quench zone mixing; noneffusive cooled liner; variable geometry requirements; and sector combustor rig.

Measurement of vascular calcification using CT fistulograms.

PubMed

Toussaint, Nigel D; Lau, Ken K; Polkinghorne, Kevan R; Kerr, Peter G

2007-02-01

Vascular calcification (VC), precipitated by calcium and phosphate imbalance, is a major contributor to cardiovascular disease (CVD) in chronic kidney disease (CKD). Electron-beam computed tomography (EBCT) quantitatively assesses coronary artery calcification (CAC), with VC scores predictive of atherosclerosis and cardiac events in the general and CKD population. EBCT is not readily available but spiral CT can also provide quantitative assessment of the extent of VC. CT fistulograms can be used as initial investigation for arterio-venous fistula (AVF) problems in haemodialysis (HD). The images obtained include thoracic aorta, brachio-cephalic, subclavian and common carotid arteries which allow assessment of the extent of VC in these vessels. No study to date has combined the CT fistulogram with concurrent determination of VC. We hypothesize that a single investigation for AVF management may also provide information on VC. We retrospectively analysed CT fistulograms on 28 HD patients determining VC scores (in Hounsfield units) in AVF, subclavian and carotid arteries and aorta. We correlated these scores with patient demographics, serum markers of mineral metabolism (time averaged for the period 6 months prior to CT) and calcium-based phosphate binders. Patients (60.7% male) had a median age of 59 years and 46.4% were diabetic. The mean duration of dialysis was 17.5 months. CT fistulograms showed predominantly aortic (75% of patients) and subclavian (75%) calcifications, with only 21.4% having carotid VC and minimal VC at the level of AVF. Median VC scores were 619.8 (0-1481.4) for aorta and 521.7 (0-1139.6) for subclavian (scores of >400 indicate severe atherosclerotic disease), but there was no significant correlation with serum markers or duration of HD. Increasing age correlated significantly with greater VC in aortic (R = 0.53, P = 0.003) and subclavian (R = 0.40, P = 0.03) vessels, as well as with the number of VC sites involved. CAC was present in most patients (89.3%) but CAC scores were not able to be determined because of cardiac movement. Concurrent determination of the degree of calcification in certain vessels may be possible from CT studies assessing AVF structure. VC scores provided by CT fistulograms could contribute to HD patient CVD risk assessment but studies with larger patient numbers are required to determine their relevance.

Accessory cells with a veiled morphology and movement pattern generated from monocytes after avoidance of plastic adherence and of NADPH oxidase activation. A comparison with GM-CSF/IL-4-induced monocyte-derived dendritic cells.

PubMed

Ruwhof, Cindy; Canning, Martha O; Grotenhuis, Kristel; de Wit, Harm J; Florencia, Zenovia Z; de Haan-Meulman, Meeny; Drexhage, Hemmo A

2002-07-01

Veiled cells (VC) present in afferent lymph transport antigen from the periphery to the draining lymph nodes. Although VC in lymph form a heterogeneous population, some of the cells clearly belong on morphological grounds to the Langerhans cell (LC)/ dendritic cell (DC) series. Here we show that culturing monocytes for 24 hrs while avoiding plastic adherence (polypropylene tubes) and avoiding the activation of NADPH oxidase (blocking agents) results in the generation of a population of veiled accessory cells. The generated VC were actively moving cells like lymph-borne VC in vivo. The monocyte (mo)-derived VC population existed of CD14(dim/-) and CD14(brighT) cells. Of these the CD14(dim/-) VC were as good in stimulating allogeneic T cell proliferation as immature DC (iDC) obtained after one week of adherent culture of monocytes in granulocyte-macrophage-colony stimulating factor (GM-CSF)/interleukin (IL)-4. This underscores the accessory cell function of the mo-derived CD14(dim/-) VC. Although the CD14(dim/-)VC had a modest expression of the DC-specific marker CD83 and were positive for S100, expression of the DC-specific markers CD1a, Langerin, DC-SIGN, and DC-LAMP were absent. This indicates that the here generated CD14(dim/-) VC can not be considered as classical LC/DC. It was also impossible to turn the CD14(dim/-) mo-derived VC population into typical DC by culture for one week in GM-CSF/IL-4 or LPS. In fact the cells died tinder such circumstances, gaining some macrophage characteristics before dying. The IL-12 production from mo-derived CD14(dim/-) VC was lower, whereas the production of IL-10 was higher as compared to iDC. Consequently the T cells that were stimulated by these mo-derived VC produced less IFN-gamma as compared with T cells stimulated by iDC. Our data indicate that it is possible to rapidly generate a population of CD14(dim/-) veiled accessory cells from monocytes. The marker pattern and cytokine production of these VC indicate that this population is not a classical DC population. The cells might earlier be related to the veiled macrophage-like cells also earlier described in afferent lymph.

Three-dimensional color Doppler echocardiography for direct measurement of vena contracta area in mitral regurgitation: in vitro validation and clinical experience.

PubMed

Little, Stephen H; Pirat, Bahar; Kumar, Rahul; Igo, Stephen R; McCulloch, Marti; Hartley, Craig J; Xu, Jiaqiong; Zoghbi, William A

2008-11-01

Our goal was to prospectively compare the accuracy of real-time three-dimensional (3D) color Doppler vena contracta (VC) area and two-dimensional (2D) VC diameter in an in vitro model and in the clinical assessment of mitral regurgitation (MR) severity. Real-time 3D color Doppler allows direct measurement of VC area and may be more accurate for assessment of MR than the conventional VC diameter measurement by 2D color Doppler. Using a circulatory loop with an incorporated imaging chamber, various pulsatile flow rates of MR were driven through 4 differently sized orifices. In a clinical study of patients with at least mild MR, regurgitation severity was assessed quantitatively using Doppler-derived effective regurgitant orifice area (EROA), and semiquantitatively as recommended by the American Society of Echocardiography. We describe a step-by-step process to accurately identify the 3D-VC area and compare that measure against known orifice areas (in vitro study) and EROA (clinical study). In vitro, 3D-VC area demonstrated the strongest correlation with known orifice area (r = 0.92, p < 0.001), whereas 2D-VC diameter had a weak correlation with orifice area (r = 0.56, p = 0.01). In a clinical study of 61 patients, 3D-VC area correlated with Doppler-derived EROA (r = 0.85, p < 0.001); the relation was stronger than for 2D-VC diameter (r = 0.67, p < 0.001). The advantage of 3D-VC area over 2D-VC diameter was more pronounced in eccentric jets (r = 0.87, p < 0.001 vs. r = 0.6, p < 0.001, respectively) and in moderate-to-severe or severe MR (r = 0.80, p < 0.001 vs. r = 0.18, p = 0.4, respectively). Measurement of VC area is feasible with real-time 3D color Doppler and provides a simple parameter that accurately reflects MR severity, particularly in eccentric and clinically significant MR where geometric assumptions may be challenging.

Three-Dimensional Color Doppler Echocardiography for Direct Measurement of Vena Contracta Area in Mitral Regurgitation

PubMed Central

Little, Stephen H.; Pirat, Bahar; Kumar, Rahul; Igo, Stephen R.; McCulloch, Marti; Hartley, Craig J.; Xu, Jiaqiong; Zoghbi, William A.

2012-01-01

OBJECTIVES Our goal was to prospectively compare the accuracy of real-time three-dimensional (3D) color Doppler vena contracta (VC) area and two-dimensional (2D) VC diameter in an in vitro model and in the clinical assessment of mitral regurgitation (MR) severity. BACKGROUND Real-time 3D color Doppler allows direct measurement of VC area and may be more accurate for assessment of MR than the conventional VC diameter measurement by 2D color Doppler. METHODS Using a circulatory loop with an incorporated imaging chamber, various pulsatile flow rates of MR were driven through 4 differently sized orifices. In a clinical study of patients with at least mild MR, regurgitation severity was assessed quantitatively using Doppler-derived effective regurgitant orifice area (EROA), and semiquantitatively as recommended by the American Society of Echocardiography. We describe a step-by-step process to accurately identify the 3D-VC area and compare that measure against known orifice areas (in vitro study) and EROA (clinical study). RESULTS In vitro, 3D-VC area demonstrated the strongest correlation with known orifice area (r = 0.92, p < 0.001), whereas 2D-VC diameter had a weak correlation with orifice area (r = 0.56, p = 0.01). In a clinical study of 61 patients, 3D-VC area correlated with Doppler-derived EROA (r = 0.85, p < 0.001); the relation was stronger than for 2D-VC diameter (r = 0.67, p < 0.001). The advantage of 3D-VC area over 2D-VC diameter was more pronounced in eccentric jets (r = 0.87, p < 0.001 vs. r = 0.6, p < 0.001, respectively) and in moderate-to-severe or severe MR (r = 0.80, p < 0.001 vs. r = 0.18, p = 0.4, respectively). CONCLUSIONS Measurement of VC area is feasible with real-time 3D color Doppler and provides a simple parameter that accurately reflects MR severity, particularly in eccentric and clinically significant MR where geometric assumptions may be challenging. PMID:19356505

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Bei-Jing; Wang, Jian-Hua

Excess enthalpy combustion is a promising approach to stabilize flame in micro-combustors. Using a Swiss-roll combustor configuration, excess enthalpy combustion can be conveniently achieved. In this work, three types of Swiss-roll combustors with double spiral-shaped channels were designed and fabricated. The combustors were tested using methane/air mixtures of various equivalence ratios. Both temperature distributions and extinction limits were determined for each combustor configuration at different methane mass flow rates. Results indicate that the Swiss-roll combustors developed in the current study greatly enhance combustion stability in center regions of the combustors. At the same time, excess enthalpy combustors of the Swiss-rollmore » configuration significantly extend the extinction limits of methane/air mixtures. In addition, the effects of combustor configurations and thermal insulation arrangements on temperature distributions and extinction limits were evaluated. With heat losses to the environment being significant, the use of thermal insulations further enhances the flame stability in center regions of the Swiss-roll combustors and extends flammable ranges. (author)« less

Microbial mineralization of dichloroethene and vinyl chloride under hypoxic conditions

USGS Publications Warehouse

Bradley, Paul M.; Chapelle, Francis H.

2011-01-01

Mineralization of 14C-radiolabled vinyl chloride ([1,2-14C] VC) and cis-dichloroethene ([1,2-14C] cis-DCE) under hypoxic (initial dissolved oxygen (DO) concentrations about 0.1 mg/L) and nominally anoxic (DO minimum detection limit = 0.01 mg/L) was examined in chloroethene-exposed sediments from two groundwater and two surface water sites. The results show significant VC and dichloroethene (DCE) mineralization under hypoxic conditions. All the sample treatments exhibited pseudo-first-order kinetics for DCE and VC mineralization over an extended range of substrate concentrations. First-order rates for VC mineralization were approximately 1 to 2 orders of magnitude higher in hypoxic groundwater sediment treatments and at least three times higher in hypoxic surface water sediment treatments than in the respective anoxic treatments. For VC, oxygen-linked processes accounted for 65 to 85% of mineralization at DO concentrations below 0.1 mg/L, and 14CO2 was the only degradation product observed in VC treatments under hypoxic conditions. Because the lower detection limit for DO concentrations measured in the field is typically 0.1 to 0.5 mg/L, these results indicate that oxygen-linked VC and DCE biodegradation can be significant under field conditions that appear anoxic. Furthermore, because rates of VC mineralization exceeded rates of DCE mineralization under hypoxic conditions, DCE accumulation without concomitant accumulation of VC may not be evidence of a DCE degradative “stall” in chloroethene plumes. Significantly, mineralization of VC above the level that could reasonably be attributed to residual DO contamination was also observed in several nominally anoxic (DO minimum detection limit = 0.01 mg/L) microcosm treatments.

Prediction of post-operative pulmonary function after lobectomy for primary lung cancer: A comparison among counting method, effective lobar volume, and lobar collapsibility using inspiratory/expiratory CT.

PubMed

Yabuuchi, Hidetake; Kawanami, Satoshi; Kamitani, Takeshi; Yonezawa, Masato; Yamasaki, Yuzo; Yamanouchi, Torahiko; Nagao, Michinobu; Okamoto, Tatsuro; Honda, Hiroshi

2016-11-01

To compare the predictabilities of postoperative pulmonary function after lobectomy for primary lung cancer among counting method, effective lobar volume, and lobar collapsibility. Forty-nine patients who underwent lobectomy for primary lung cancer were enrolled. All patients underwent inspiratory/expiratory CT and pulmonary function tests 2 weeks before surgery and postoperative pulmonary function tests 6-7 months after surgery. Pulmonary function losses (ΔFEV 1.0 and ΔVC) were calculated from the pulmonary function tests. Predictive postoperative pulmonary function losses (ppoΔFEV 1.0 and ppoΔVC) were calculated using counting method, effective volume, and lobar collapsibility. Correlations and agreements between ΔFEV 1.0 and ppoFEV 1.0 and those between ΔVC and ppoΔVC were tested among three methods using Spearman's correlation coefficient and Bland-Altman plots. ΔFEV 1.0 and ppoΔFEV 1.0insp-exp were strongly correlated (r=0.72), whereas ΔFEV 1.0 and ppoΔFEV 1.0count and ΔFEV 1.0 and Pred. ΔFEV 1.0eff.vol. were moderately correlated (r=0.50, 0.56). ΔVC and ppoΔVC eff.vol. (r=0.71) were strongly correlated, whereas ΔVC and ppoΔVC count , and ΔVC and ppoΔVC insp-exp were moderately correlated (r=0.55, 0.42). Volumetry from inspiratory/expiratory CT data could be useful to predict postoperative pulmonary function after lobectomy for primary lung cancer. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Involvement of Linear Plasmids in Aerobic Biodegradation of Vinyl Chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

BRIGMON, ROBINL.

2004-06-14

Pseudomonas putida strain AJ and Ochrobactrum strain TD were isolated from hazardous waste sites based on their ability to use vinyl chloride (VC) as a sole source of carbon and energy under aerobic conditions. Strains AJ and TD also use ethene and ethylene oxide as growth substrates. Strain AJ contained a linear megaplasmid (approximately 260 kb) when grown on VC or ethene, but no circular plasmids. While growing on ethylene oxide, the size of the linear plasmid in strain AJ decreased to approximately 100 kb, although its ability to use VC as a substrate was retained. The linear plasmids inmore » strain AJ were cured and its ability to consume VC, ethene, and ethylene oxide was lost following growth on a rich substrate (Luria-Bertani broth) through at least three transfers. Strain TD contained three linear plasmids, ranging in size from approximately 100 kb to 320 kb, when growing on VC or ethene. As with strain AJ, the linear plasmids in strain TD were cured following growth on Luria -Bertani broth and its ability to consume VC and ethene was lost. Further analysis of these linear plasmids may help reveal the pathway for VC biodegradation in strains AJ and TD and explain why this process occurs at many but not all sites where groundwater is contaminated with chloroethenes. Metabolism of VC and ethene by strains AJ and TD is initiated by an alkene monooxygenase. Their yields during growth on VC (0.15-0.20 mg total suspended solids per mg VC) are similar to the yields reported for other isolates i.e., Mycobacterium sp., Nocardioides sp., and Pseudomonas sp.« less

Origin of VC-only plumes from naturally enhanced dechlorination in a peat-rich hydrogeologic setting

NASA Astrophysics Data System (ADS)

Filippini, Maria; Amorosi, Alessandro; Campo, Bruno; Herrero-Martìn, Sara; Nijenhuis, Ivonne; Parker, Beth L.; Gargini, Alessandro

2016-09-01

The occurrence of vinyl chloride (VC) is often a main concern at sites contaminated with chlorinated solvents due to its high degree of toxicity and carcinogenicity. VC occurrence in aquifers is most often related to the degradation of higher chlorinated ethenes or ethanes and it is generally detected in plumes along with parent contaminants. However, specific combination of stratigraphic, hydrogeologic and geochemical conditions can enhance the degradation of parents and lead to the formation of plumes almost entirely composed of VC (i.e. VC-only plumes). This paper investigates the causes of VC-only plumes in the aquifers below the city of Ferrara (northern Italy) by combining multiple lines of evidence. The City of Ferrara is located on an alluvial lowland, built by the River Po, and is made up of alternating unconsolidated sandy aquifer and silt-clay aquitard deposits of fluvial origin. This region has been strongly impacted by prior industrial activities, with the occurrence of chlorinated compounds at several sites. VC-only plumes with uncertain source location were found at two contaminated sites. The source zone of a third plume composed of chloroethenes from PCE to VC was investigated for high resolution depositional facies architecture and contaminant distribution (contaminant concentration and Compound Specific Isotope Analysis - CSIA). The investigation suggested that degradation of PCE and TCE takes place during contaminant migration through peat-rich (swamp) layers related to the Holocene transgression, which locally act as a ;reactor; for stimulating degradation with the accumulation of VC in the strongly reducing environment of the peat. Regional-scale stratigraphic architecture showed the ubiquitous occurrence of swamp layers at distinct stratigraphic levels in the investigated system and their apparent linkage to the in situ creation of the VC-only plumes.

Magnesium prevents phosphate-induced calcification in human aortic vascular smooth muscle cells.

PubMed

Louvet, Loïc; Büchel, Janine; Steppan, Sonja; Passlick-Deetjen, Jutta; Massy, Ziad A

2013-04-01

Vascular calcification (VC) is prevalent in patients suffering from chronic kidney disease. Factors promoting calcification include abnormalities in mineral metabolism, particularly high phosphate levels. Inorganic phosphate (Pi) is a classical inducer of in vitro VC. Recently, an inverse relationship between serum magnesium concentrations and VC has been reported. The present study aimed to investigate the effects of magnesium on Pi-induced VC at the cellular level using primary HAVSMC. Alive and fixed HAVSMC were assessed during 14 days in the presence of Pi with increasing concentrations of magnesium (Mg(2+)) chloride. Mineralization was measured using quantification of calcium, von Kossa and alizarin red stainings. Cell viability and secretion of classical VC markers were also assessed using adequate tests. Involvement of transient receptor potential melastatin (TRPM) 7 was assessed using 2-aminoethoxy-diphenylborate (2-APB) inhibitor. Co-incubation with Mg(2+) significantly decreased Pi-induced VC in live HAVSMC, no effect was found in fixed cells. At potent concentrations in Pi-induced HAVSMC, Mg(2+) significantly improved cell viability and restored to basal level increased secretions of osteocalcin and matrix gla protein, whereas a decrease in osteopontin secretion was partially restored. The block of TRPM7 with 2-APB at 10(-4) M led to the inefficiency of Mg(2+) to prevent VC. Increasing Mg(2+) concentrations significantly reduced VC, improved cell viability and modulated secretion of VC markers during cell-mediated matrix mineralization clearly pointing to a cellular role for Mg(2+) and 2-APB further involved TRPM7 and a potential Mg(2+) entry to exert its effects. Further investigations are needed to shed light on additional cellular mechanism(s) by which Mg(2+) is able to prevent VC.

Selectivity of Vibrio cholerae H-NOX for Gaseous Ligands Follows “Sliding Scale Rule” Hypothesis

PubMed Central

Wu, Gang; Liu, Wen; Berka, Vladimir; Tsai, Ah-lim

2014-01-01

Vc H-NOX (or VCA0720) is an H-NOX (heme-nitric oxide and oxygen binding) protein from facultative aerobic bacterium Vibrio cholerae. It shares significant sequence homology with soluble guanylyl cyclase (sGC), a NO sensor protein commonly found in animals. Similar to sGC, Vc H-NOX binds strongly to NO and CO with affinities of 0.27 nM and 0.77 μM, respectively, but weakly to O2. When positioned in “sliding scale” plot {Tsai, A.-L. et. al. (2012) Biochemistry, 51, pp172-86}, the line connecting logKD(NO) and logKD(CO) of Vc H-NOX is almost superimposable with that of Ns H-NOX. Therefore, the measured affinities and kinetic parameters of gaseous ligands to Vc H-NOX provide more evidence to validate the “sliding scale rule” hypothesis. Like sGC, Vc H-NOX binds NO in multiple steps, forming first a 6-coordinate heme-NO complex with a rate of 1.1 × 109 M−1s−1, and then converts to a 5c heme-NO complex at a rate also dependent on [NO]. Although the formation of oxyferrous Vc H-NOX is not detectable under normal atmospheric oxygen level, ferrous Vc H-NOX is oxidized to ferric form at a rate of 0.06 s−1 when mixed with O2. Ferric Vc H-NOX exists as a mixture of high- and low-spin states and is influenced by binding to different ligands. Characterization of both ferric and ferrous Vc H-NOX and their complexes with various ligands lay the foundation for understanding the possible dual roles in gas and redox sensing of Vc H-NOX. PMID:24351060

Myosin vc interacts with Rab32 and Rab38 proteins and works in the biogenesis and secretion of melanosomes.

PubMed

Bultema, Jarred J; Boyle, Judith A; Malenke, Parker B; Martin, Faye E; Dell'Angelica, Esteban C; Cheney, Richard E; Di Pietro, Santiago M

2014-11-28

Class V myosins are actin-based motors with conserved functions in vesicle and organelle trafficking. Herein we report the discovery of a function for Myosin Vc in melanosome biogenesis as an effector of melanosome-associated Rab GTPases. We isolated Myosin Vc in a yeast two-hybrid screening for proteins that interact with Rab38, a Rab protein involved in the biogenesis of melanosomes and other lysosome-related organelles. Rab38 and its close homolog Rab32 bind to Myosin Vc but not to Myosin Va or Myosin Vb. Binding depends on residues in the switch II region of Rab32 and Rab38 and regions of the Myosin Vc coiled-coil tail domain. Myosin Vc also interacts with Rab7a and Rab8a but not with Rab11, Rab17, and Rab27. Although Myosin Vc is not particularly abundant on pigmented melanosomes, its knockdown in MNT-1 melanocytes caused defects in the trafficking of integral membrane proteins to melanosomes with substantially increased surface expression of Tyrp1, nearly complete loss of Tyrp2, and significant Vamp7 mislocalization. Knockdown of Myosin Vc in MNT-1 cells more than doubled the abundance of pigmented melanosomes but did not change the number of unpigmented melanosomes. Together the data demonstrate a novel role for Myosin Vc in melanosome biogenesis and secretion. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Experimental clean combustor program, alternate fuels addendum, phase 2

NASA Technical Reports Server (NTRS)

Gleason, C. C.; Bahr, D. W.

1976-01-01

The characteristics of current and advanced low-emissions combustors when operated with special test fuels simulating broader range combustion properties of petroleum or coal derived fuels were studied. Five fuels were evaluated; conventional JP-5, conventional No. 2 Diesel, two different blends of Jet A and commercial aromatic mixtures - zylene bottoms and haphthalene charge stock, and a fuel derived from shale oil crude which was refined to Jet A specifications. Three CF6-50 engine size combustor types were evaluated; the standard production combustor, a radial/axial staged combustor, and a double annular combustor. Performance and pollutant emissons characteristics at idle and simulated takeoff conditions were evaluated in a full annular combustor rig. Altitude relight characteristics were evaluated in a 60 degree sector combustor rig. Carboning and flashback characteristics at simulated takeoff conditions were evaluated in a 12 degree sector combustor rig. For the five fuels tested, effects were moderate, but well defined.

Exhaust gas measurements in a propane fueled swirl stabilized combustor

NASA Technical Reports Server (NTRS)

Aanad, M. S.

1982-01-01

Exhaust gas temperature, velocity, and composition are measured and combustor efficiencies are calculated in a lean premixed swirl stabilized laboratory combustor. The radial profiles of the data between the co- and the counter swirl cases show significant differences. Co-swirl cases show evidence of poor turbulent mixing across the combustor in comparison to the counter-swirl cases. NO sub x levels are low in the combustor but substantial amounts of CO are present. Combustion efficiencies are low and surprisingly constant with varying outer swirl in contradiction to previous results under a slightly different inner swirl condition. This difference in the efficiency trends is expected to be a result of the high sensitivity of the combustor to changes in the inner swirl. Combustor operation is found to be the same for propane and methane fuels. A mechanism is proposed to explain the combustor operation and a few important characteristics determining combustor efficiency are identified.

Enhanced electrocatalytic activity and stability of Pd 3V/C nanoparticles with a trace amount of Pt decoration for the oxygen reduction reaction

DOE PAGES

Liu, Sufen; Han, Lili; Zhu, Jing; ...

2015-09-14

In this study, carbon supported Pd 3V bimetallic alloy nanoparticles (Pd 3V/C) have been successfully synthesized via a simple impregnation–reduction method, followed by high temperature treatment under a H 2 atmosphere. Electrochemical tests reveal that the half-wave potential of Pd 3V/C-500 shifts positively 40 mV compared with Pd/C. However, the catalytic activity of Pd 3V/C-500 suffers from serious degradation after 1k cycles. By a spontaneous displacement reaction or co-reduction method, a trace amount of Pt was decorated on the surface or inside of the Pd 3V/C nanoparticles. The catalytic activity and stability of the Pd 3V@Pt/C and Pt-Pd 3V/C catalystsmore » for the oxygen reduction reaction (ORR) are enhanced significantly, and are comparable to commercial Pt/C. In addition, the Pt mass activity of Pd 3V@Pt/C and Pt-Pd 3V/C improves by factors of 10.9 and 6.5 at 0.80 V relative to Pt/C. Moreover, Pt-decorated Pd 3V/C nanoparticles show almost no obvious morphology change after durability tests, because the Pt-rich shell plays an important role in preventing degradation.« less

Patients' Experiences with Specialist Care via Video Consultation in Primary Healthcare in Rural Areas

PubMed Central

Johansson, Annette M.; Lindberg, Inger; Söderberg, Siv

2014-01-01

Introduction. Video consultation (VC) can improve access to specialist care, especially for individuals who live in rural areas that are long distances from specialist clinics. Aim. The aim of this study was to describe patients' experiences with specialist care via VC encounters. Method. Interviews were conducted with 26 patients who had participated in a VC encounter. The data were analysed using thematic content analysis. Result. The analysis resulted in two themes. The theme “confident with the technology” was constructed from the categories “possibilities and obstacles in using VC encounters” and “advantages and disadvantages of the technology.” The theme “personal satisfaction with the VC encounters” was constructed from the categories “support from the healthcare personnel,” “perceived security,” and “satisfaction with the specialist consultation.” Conclusion. The patients who did not think that the VC was the best care still considered that the visit was adequate because they did not have to travel. An important finding was that the patients' perceived even short distances to specialty care as expensive journeys because many patients had low incomes. Among the patients who had more than one VC, the second encounter was perceived as safer. Additionally, good communication was essential for the patient's perception of security during the VC encounter. PMID:25243009

Patients' Experiences with Specialist Care via Video Consultation in Primary Healthcare in Rural Areas.

PubMed

Johansson, Annette M; Lindberg, Inger; Söderberg, Siv

2014-01-01

Introduction. Video consultation (VC) can improve access to specialist care, especially for individuals who live in rural areas that are long distances from specialist clinics. Aim. The aim of this study was to describe patients' experiences with specialist care via VC encounters. Method. Interviews were conducted with 26 patients who had participated in a VC encounter. The data were analysed using thematic content analysis. Result. The analysis resulted in two themes. The theme "confident with the technology" was constructed from the categories "possibilities and obstacles in using VC encounters" and "advantages and disadvantages of the technology." The theme "personal satisfaction with the VC encounters" was constructed from the categories "support from the healthcare personnel," "perceived security," and "satisfaction with the specialist consultation." Conclusion. The patients who did not think that the VC was the best care still considered that the visit was adequate because they did not have to travel. An important finding was that the patients' perceived even short distances to specialty care as expensive journeys because many patients had low incomes. Among the patients who had more than one VC, the second encounter was perceived as safer. Additionally, good communication was essential for the patient's perception of security during the VC encounter.

Exploring the views of emergency department staff on the use of videoconferencing for mental health emergencies in southwestern Ontario.

PubMed

Pangka, Kyle R; Chandrasena, Ranjith; Wijeratne, Nishardi; Mann, Miriam

2015-01-01

Patients presenting to a rural emergency department (ED) with mental health symptoms have difficulty accessing services of mental health professionals [1,2]. Videoconferencing (VC) has been found to improve patient access to health services that require specialist care in rural EDs [3,4,5]. Although previous studies highlight the benefit of using VC for patients presenting with mental health emergencies, no study has investigated the current views and use of VC for mental health emergencies in EDs in Southwestern Ontario [3,5,6]. To explore the views of ED staff regarding the use of VC in mental health emergencies, structured telephone interviews were conducted with representatives from EDs in the Erie St. Clair and Southwest Local Health Integration Networks (LHIN). Participants noted that using VC for mental health emergencies may improve patient experience and benefit crisis response teams. VC was perceived by some participants as a means to expedite the direct assessment of a patient presenting with a mental health emergency by a mental health specialist. However several participants stated that using VC for mental health emergencies strains ED resources. Lack of use and difficulty accessing a psychiatrist were identified as potential barriers to implementing the use of VC for mental health emergencies.

A Relationship Between Visual Complexity and Aesthetic Appraisal of Car Front Images: An Eye-Tracker Study.

PubMed

Chassy, Philippe; Lindell, Trym A E; Jones, Jessica A; Paramei, Galina V

2015-01-01

Image aesthetic pleasure (AP) is conjectured to be related to image visual complexity (VC). The aim of the present study was to investigate whether (a) two image attributes, AP and VC, are reflected in eye-movement parameters; and (b) subjective measures of AP and VC are related. Participants (N=26) explored car front images (M=50) while their eye movements were recorded. Following image exposure (10 seconds), its VC and AP were rated. Fixation count was found to positively correlate with the subjective VC and its objective proxy, JPEG compression size, suggesting that this eye-movement parameter can be considered an objective behavioral measure of VC. AP, in comparison, positively correlated with average dwelling time. Subjective measures of AP and VC were related too, following an inverted U-shape function best-fit by a quadratic equation. In addition, AP was found to be modulated by car prestige. Our findings reveal a close relationship between subjective and objective measures of complexity and aesthetic appraisal, which is interpreted within a prototype-based theory framework. © The Author(s) 2015.

Ascorbic acid enhances oxidative stress tolerance and biological control efficacy of Pichia caribbica against postharvest blue mold decay of apples.

PubMed

Li, Chaolan; Zhang, Hongyin; Yang, Qiya; Komla, Mahunu Gustav; Zhang, Xiaoyun; Zhu, Shuyun

2014-07-30

The effect of ascorbic acid (VC) on improving oxidative stress tolerance of Pichia caribbica and biocontrol efficacy against blue mold caused by Penicillium expansum on apples was investigated. P. caribbica showed susceptibility to the oxidative stress in vitro test, and 250 μg/mL VC treatment improved its oxidative stress tolerance. The higher viability exhibited by VC-treated yeast was associated with a lower intracellular ROS level. The activities of antioxidant enzymes of P. caribbica were improved by VC treatment, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). Additionally, VC-treated yeast exhibited greater biocontrol activity against P. expansum and faster growth when stored at 25 and 4 °C, respectively, compared to the performance of the non-VC-treated yeast. In response to the VC treatment under oxidative stress, several differentially expressed proteins were identified in P. caribbica, and most of the poteins were confirmed to be related to basic metabolism. Therefore, the application of ascorbic acid is a useful approach to improve oxidative stress tolerance of P. caribbica and its biocontrol efficacy on apples.

Combustion Characteristics Analysis of Improved Combustor Structure of Micro Turbine Engine

NASA Astrophysics Data System (ADS)

Chen, Hai

2018-05-01

In order to improve the performance of micro combustor, the 60 slots of the original combustor were modified into 120 slots for the MIT 6-wafer micro-combustor. The performance of the micro combustor with the improved and original design was compared through numerical simulation, and stable operating ranges was studied. It was found that the improved combustor can stabilize the flame under the condition of higher fuel/air mixture mass flow rate.

40 CFR 60.53b - Standards for municipal waste combustor operating practices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Circulating fluidized bed combustor 100 4 Pulverized coal/refuse-derived fuel mixed fuel-fired combustor 150 4 Spreader stoker coal/refuse-derived fuel mixed fuel-fired combustor 150 24 a Measured at the combustor... activated carbon injection rate during dioxin/furan or mercury testing. [60 FR 65419, Dec. 19, 1995, as...

Using Virtual Technology to Promote Functional Communication in Aphasia: Preliminary Evidence From Interactive Dialogues With Human and Virtual Clinicians.

PubMed

Kalinyak-Fliszar, Michelene; Martin, Nadine; Keshner, Emily; Rudnicky, Alex; Shi, Justin; Teodoro, Gregory

2015-11-01

We investigated the feasibility of using a virtual clinician (VC) to promote functional communication abilities of persons with aphasia (PWAs). We aimed to determine whether the quantity and quality of verbal output in dialogues with a VC would be the same or greater than those with a human clinician (HC). Four PWAs practiced dialogues for 2 sessions each with a HC and VC. Dialogues from before and after practice were transcribed and analyzed for content. We compared measures taken before and after practice in the VC and HC conditions. Results were mixed. Participants either produced more verbal output with the VC or showed no difference on this measure between the VC and HC conditions. Participants also showed some improvement in postpractice narratives. Results provide support for the feasibility and applicability of virtual technology to real-life communication contexts to improve functional communication in PWAs.

Combustor for a low-emissions gas turbine engine

DOEpatents

Glezer, Boris; Greenwood, Stuart A.; Dutta, Partha; Moon, Hee-Koo

2000-01-01

Many government entities regulated emission from gas turbine engines including CO. CO production is generally reduced when CO reacts with excess oxygen at elevated temperatures to form CO2. Many manufactures use film cooling of a combustor liner adjacent to a combustion zone to increase durability of the combustion liner. Film cooling quenches reactions of CO with excess oxygen to form CO2. Cooling the combustor liner on a cold side (backside) away from the combustion zone reduces quenching. Furthermore, placing a plurality of concavities on the cold side enhances the cooling of the combustor liner. Concavities result in very little pressure reduction such that air used to cool the combustor liner may also be used in the combustion zone. An expandable combustor housing maintains a predetermined distance between the combustor housing and combustor liner.

Rolling contact mounting arrangement for a ceramic combustor

DOEpatents

Boyd, G.L.; Shaffer, J.E.

1995-10-17

A combustor assembly having a preestablished rate of thermal expansion is mounted within a gas turbine engine housing having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the combustor assembly. The combustor assembly is constructed of a inlet end portion, a outlet end portion and a plurality of combustor ring segments positioned between the end portions. A mounting assembly is positioned between the combustor assembly and the gas turbine engine housing to allow for the difference in the rate of thermal expansion while maintaining axially compressive force on the combustor assembly to maintain contact between the separate components. 3 figs.

Rolling contact mounting arrangement for a ceramic combustor

DOEpatents

Boyd, Gary L.; Shaffer, James E.

1995-01-01

A combustor assembly having a preestablished rate of thermal expansion is mounted within a gas turbine engine housing having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the combustor assembly. The combustor assembly is constructed of a inlet end portion, a outlet end portion and a plurality of combustor ring segments positioned between the end portions. A mounting assembly is positioned between the combustor assembly and the gas turbine engine housing to allow for the difference in the rate of thermal expansion while maintaining axially compressive force on the combustor assembly to maintain contact between the separate components.

In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002

PubMed Central

Imanse, Sierra M.; Cornwell, Emily R.; Getchell, Rodman G.; Kurath, Gael; Bowser, Paul R.

2014-01-01

Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both an in vitro and in vivo approach. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml−1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb. PMID:25722533

In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002

USGS Publications Warehouse

Imanse, Sierra M.; Cornwell, Emily R.; Getchell, Rodman G.; Kurath, Gael; Bowser, Paul R.

2014-01-01

Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both in vitro and in vivo approaches. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml− 1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb.

Experimental clean combustor program, phase 2

NASA Technical Reports Server (NTRS)

Gleason, C. C.; Rogers, D. W.; Bahr, D. W.

1976-01-01

The primary objectives of this three-phase program are to develop technology for the design of advanced combustors with significantly lower pollutant emission levels than those of current combustors, and to demonstrate these pollutant emission reductions in CF6-50C engine tests. The purpose of the Phase 2 Program was to further develop the two most promising concepts identified in the Phase 1 Program, the double annular combustor and the radial/axial staged combustor, and to design a combustor and breadboard fuel splitter control for CF6-50 engine demonstration testing in the Phase 3 Program. Noise measurement and alternate fuels addendums to the basic program were conducted to obtain additional experimental data. Twenty-one full annular and fifty-two sector combustor configurations were evaluated. Both combustor types demonstrated the capability for significantly reducing pollutant emission levels. The most promising results were obtained with the double annular combustor. Rig test results corrected to CF-50C engine conditions produced EPA emission parameters for CO, HC, and NOX of 3.4, 0.4, and 4.5 respectively. These levels represent CO, HC, and NOX reductions of 69, 90, and 42 percent respectively from current combustor emission levels. The combustor also met smoke emission level requirements and development engine performance and installation requirements.

Prevalence of Vibrio cholerae in Coastal Alternative Supplies of Drinking Water and Association with Bacillus-Like Spore Formers.

PubMed

Shishir, Md Asaduzzaman; Mamun, Md Al; Mian, Md Mahmuduzzaman; Ferdous, Umme Tamanna; Akter, Noor Jahan; Suravi, Rajia Sultana; Datta, Suvamoy; Kabir, Md Ehsanul

2018-01-01

The scarcity of hygienic drinking water is a normal phenomenon in the coastal areas of Bangladesh due to the high salinity of ground water. The inhabitants of this locality, therefore, live on alternative supplies of water including rain-fed pond water, and rainwater with persistent complex microbial interactions therein, often contaminated with life-threatening pathogens. Hence, this study was aimed at analyzing the prevalence of Vibrio cholerae ( Vc ) in the alternative drinking waters of Mathbaria, a coastal subdistrict neighboring the Bay of Bengal, the efficacy of pond sand filter (PSF) and the co-association among Bacillus -like spore formers (Sf) and Vc . Vc presumably entrapped into the membrane filter was enriched in alkaline peptone water medium and was isolated on selective thiosulfate-citrate-bile salts-sucrose and taurocholate-tellurite-gelatin agar media. They were finally identified by immunochromatographic one step rapid test and serology test. A total of 26% Vc positive samples were obtained out of 100 [ponds-48, household (HH)-29, and PSFs-23] where 13% cases were pathogenic ( Vc O1) and 13% were non-pathogenic ( Vc non-O1/non-O139). The distribution of Vc as observed was 33, 26, and 13.8% in waters derived from pond surface, PSF, and HH reservoirs, respectively, and for pathogenic type, it was 62.5%, 50%, and nil, respectively. Although none of the samples was identified with pathogenic Vc O139, the statistics represents a significant and augmentative risk of cholera outbreak in the focused area. The antibiotic sensitivity pattern in this study resembled the trend observed during last few years for Vc . The PSF demonstrated its inability to remove Vc from any of the samples and in addition, the filter itself was evidenced to be the source of pathogens and spores in further contamination and transmission. The development of biofilm in the PSF could be hypothesized as the reservoir in contaminating pathogen-free water samples. From the test of homogeneity, the risk levels of alternative water sources were estimated equal regarding Vc . Simultaneously, it was determined statistically that the prevalence of Vc , by no means, is influenced by Bacillus -like Sf be it for pond surface, HH, or PSF derived water.

Prevalence of Vibrio cholerae in Coastal Alternative Supplies of Drinking Water and Association with Bacillus-Like Spore Formers

PubMed Central

Shishir, Md. Asaduzzaman; Mamun, Md. Al; Mian, Md. Mahmuduzzaman; Ferdous, Umme Tamanna; Akter, Noor Jahan; Suravi, Rajia Sultana; Datta, Suvamoy; Kabir, Md. Ehsanul

2018-01-01

The scarcity of hygienic drinking water is a normal phenomenon in the coastal areas of Bangladesh due to the high salinity of ground water. The inhabitants of this locality, therefore, live on alternative supplies of water including rain-fed pond water, and rainwater with persistent complex microbial interactions therein, often contaminated with life-threatening pathogens. Hence, this study was aimed at analyzing the prevalence of Vibrio cholerae (Vc) in the alternative drinking waters of Mathbaria, a coastal subdistrict neighboring the Bay of Bengal, the efficacy of pond sand filter (PSF) and the co-association among Bacillus-like spore formers (Sf) and Vc. Vc presumably entrapped into the membrane filter was enriched in alkaline peptone water medium and was isolated on selective thiosulfate-citrate-bile salts-sucrose and taurocholate-tellurite-gelatin agar media. They were finally identified by immunochromatographic one step rapid test and serology test. A total of 26% Vc positive samples were obtained out of 100 [ponds—48, household (HH)—29, and PSFs—23] where 13% cases were pathogenic (Vc O1) and 13% were non-pathogenic (Vc non-O1/non-O139). The distribution of Vc as observed was 33, 26, and 13.8% in waters derived from pond surface, PSF, and HH reservoirs, respectively, and for pathogenic type, it was 62.5%, 50%, and nil, respectively. Although none of the samples was identified with pathogenic Vc O139, the statistics represents a significant and augmentative risk of cholera outbreak in the focused area. The antibiotic sensitivity pattern in this study resembled the trend observed during last few years for Vc. The PSF demonstrated its inability to remove Vc from any of the samples and in addition, the filter itself was evidenced to be the source of pathogens and spores in further contamination and transmission. The development of biofilm in the PSF could be hypothesized as the reservoir in contaminating pathogen-free water samples. From the test of homogeneity, the risk levels of alternative water sources were estimated equal regarding Vc. Simultaneously, it was determined statistically that the prevalence of Vc, by no means, is influenced by Bacillus-like Sf be it for pond surface, HH, or PSF derived water. PMID:29536001

Differential Cav2.1 and Cav2.3 channel inhibition by baclofen and α-conotoxin Vc1.1 via GABAB receptor activation

PubMed Central

McArthur, Jeffrey R.; Cuny, Hartmut; Clark, Richard J.; Adams, David J.

2014-01-01

Neuronal Cav2.1 (P/Q-type), Cav2.2 (N-type), and Cav2.3 (R-type) calcium channels contribute to synaptic transmission and are modulated through G protein–coupled receptor pathways. The analgesic α-conotoxin Vc1.1 acts through γ-aminobutyric acid type B (GABAB) receptors (GABABRs) to inhibit Cav2.2 channels. We investigated GABABR-mediated modulation by Vc1.1, a cyclized form of Vc1.1 (c-Vc1.1), and the GABABR agonist baclofen of human Cav2.1 or Cav2.3 channels heterologously expressed in human embryonic kidney cells. 50 µM baclofen inhibited Cav2.1 and Cav2.3 channel Ba2+ currents by ∼40%, whereas c-Vc1.1 did not affect Cav2.1 but potently inhibited Cav2.3, with a half-maximal inhibitory concentration of ∼300 pM. Depolarizing paired pulses revealed that ∼75% of the baclofen inhibition of Cav2.1 was voltage dependent and could be relieved by strong depolarization. In contrast, baclofen or Vc1.1 inhibition of Cav2.3 channels was solely mediated through voltage-independent pathways that could be disrupted by pertussis toxin, guanosine 5′-[β-thio]diphosphate trilithium salt, or the GABABR antagonist CGP55845. Overexpression of the kinase c-Src significantly increased inhibition of Cav2.3 by c-Vc1.1. Conversely, coexpression of a catalytically inactive double mutant form of c-Src or pretreatment with a phosphorylated pp60c-Src peptide abolished the effect of c-Vc1.1. Site-directed mutational analyses of Cav2.3 demonstrated that tyrosines 1761 and 1765 within exon 37 are critical for inhibition of Cav2.3 by c-Vc1.1 and are involved in baclofen inhibition of these channels. Remarkably, point mutations introducing specific c-Src phosphorylation sites into human Cav2.1 channels conferred c-Vc1.1 sensitivity. Our findings show that Vc1.1 inhibition of Cav2.3, which defines Cav2.3 channels as potential targets for analgesic α-conotoxins, is caused by specific c-Src phosphorylation sites in the C terminus. PMID:24688019

Mass of chlorinated volatile organic compounds removed by Pump-and-Treat, Naval Air Warfare Center, West Trenton, New Jersey, 1996-2010

USGS Publications Warehouse

Lacombe, Pierre J.

2011-01-01

Pump and Treat (P&T) remediation is the primary technique used to contain and remove trichloroethylene (TCE) and its degradation products cis 1-2,dichloroethylene (cDCE) and vinyl chloride (VC) from groundwater at the Naval Air Warfare Center (NAWC), West Trenton, NJ. Three methods were used to determine the masses of TCE, cDCE, and VC removed from groundwater by the P&T system since it became fully operational in 1996. Method 1, is based on the flow volume and concentrations of TCE, cDCE, and VC in groundwater that entered the P&T building as influent. Method 2 is based on withdrawal volume from each active recovery well and the concentrations of TCE, cDCE, and VC in the water samples from each well. Method 3 compares the maximum monthly amount of TCE, cDCE, and VC from Method 1 and Method 2. The greater of the two values is selected to represent the masses of TCE, cDCE and VC removed from groundwater each month. Previously published P&T monthly reports used Method 1 to determine the mass of TCE, cDCE, and VC removed. The reports state that 8,666 pounds (lbs) of TCE, 13,689 lbs of cDCE, and 2,455 lbs of VC were removed by the P&T system during 1996-2010. By using Method 2, the mass removed was determined to be 8,985 lbs of TCE, 17,801 lbs of cDCE, and 3,056 lbs of VC removed, and Method 3, resulted in 10,602 lbs of TCE, 21,029 lbs of cDCE, and 3,496 lbs of VC removed. To determine the mass of original TCE removed from groundwater, the individual masses of TCE, cDCE, and VC (determined using Methods 1, 2, and 3) were converted to numbers of moles, summed, and converted to pounds of original TCE. By using the molar conversion the mass of original TCE removed from groundwater by Methods 1, 2, and 3 was 32,381 lbs, 39,535 lbs, and 46,452 lbs, respectively, during 1996-2010. P&T monthly reports state that 24,805 lbs of summed TCE, cDCE, and VC were removed from groundwater. The simple summing method underestimates the mass of original TCE removed by the P&T system.

Analytical fuel property effects--small combustors

NASA Technical Reports Server (NTRS)

Sutton, R. D.; Troth, D. L.; Miles, G. A.

1984-01-01

The consequences of using broad-property fuels in both conventional and advanced state-of-the-art small gas turbine combustors are assessed. Eight combustor concepts were selected for initial screening, of these, four final combustor concepts were chosen for further detailed analysis. These included the dual orifice injector baseline combustor (a current production 250-C30 engine combustor) two baseline airblast injected modifications, short and piloted prechamber combustors, and an advanced airblast injected, variable geometry air staged combustor. Final predictions employed the use of the STAC-I computer code. This quasi 2-D model includes real fuel properties, effects of injector type on atomization, detailed droplet dynamics, and multistep chemical kinetics. In general, fuel property effects on various combustor concepts can be classified as chemical or physical in nature. Predictions indicate that fuel chemistry has a significant effect on flame radiation, liner wall temperature, and smoke emission. Fuel physical properties that govern atomization quality and evaporation rates are predicted to affect ignition and lean-blowout limits, combustion efficiency, unburned hydrocarbon, and carbon monoxide emissions.

Clean catalytic combustor program

NASA Technical Reports Server (NTRS)

Ekstedt, E. E.; Lyon, T. F.; Sabla, P. E.; Dodds, W. J.

1983-01-01

A combustor program was conducted to evolve and to identify the technology needed for, and to establish the credibility of, using combustors with catalytic reactors in modern high-pressure-ratio aircraft turbine engines. Two selected catalytic combustor concepts were designed, fabricated, and evaluated. The combustors were sized for use in the NASA/General Electric Energy Efficient Engine (E3). One of the combustor designs was a basic parallel-staged double-annular combustor. The second design was also a parallel-staged combustor but employed reverse flow cannular catalytic reactors. Subcomponent tests of fuel injection systems and of catalytic reactors for use in the combustion system were also conducted. Very low-level pollutant emissions and excellent combustor performance were achieved. However, it was obvious from these tests that extensive development of fuel/air preparation systems and considerable advancement in the steady-state operating temperature capability of catalytic reactor materials will be required prior to the consideration of catalytic combustion systems for use in high-pressure-ratio aircraft turbine engines.

[Accidents of the everyday life (AcVC) in children in Dakar: about 201 cases].

PubMed

Mohamed, Azhar Salim; Sagna, Aloïse; Fall, Mbaye; Ndoye, Ndeye Aby; Mbaye, Papa Alassane; Fall, Aimé Lakh; Diaby, Alou; Ndour, Oumar; Ngom, Gabriel

2017-01-01

Accidents of everyday life (AcVC) are common in children and can led to disabling injuries and death. This study aimed to analyze the epidemiological aspects of AcVC and the related injury mechanisms in Dakar. We conducted a descriptive, cross-sectional study conducted from 1 January 2013 to 30 June 2013. All the children victims of domestic accidents, sport and leisure accidents or school accidents were included. We studied some general parameters and some parameters related to each type of AcVC. Two hundred and one children were included, accounting for 27% of emergency consultations. There were 148 boys and 53 girls. Children less than 5 years of age were most affected (37.8%). Football and wrestling game were the main causes of AcVC. AcVC occur mainly at home (58.2%) and in the areas of sport and recreation (31.8%). The fractures predominated in the different types of AcVC: 54.9% of domestic accidents, 68.8% of sport and recreation accidents and 40% of school accidents. From an epidemiological perspective, our results are superimposable to literature. Fractures predominated contrary to literature where bruises were preponderant. Wrestling game is the main cause of these fractures, after football. The acquisition of knowledge about the epidemiological aspects of AcVC and the related injury mechanisms will allow for prevention campaigns in Dakar.

MRI-Based Evaluation of the Vaginal Cuff in Brachytherapy Planning: Are We Missing the Target?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Christina Hunter; Prisciandaro, Joann I.; Maturen, Katherine E.

2016-06-01

Purpose: Although recurrences and toxicity occur after vaginal cuff (VC) brachytherapy, little is known about dosimetry due to the inability to clearly visualize the VC on computed tomography (CT). T2-weighted (T2W) magnetic resonance imaging (MRI) is superior to CT in this setting, and we hypothesized that it could provide previously unascertainable dosimetric information. Methods and Materials: In a cohort of 32 patients who underwent cylinder-based brachytherapy for endometrial cancer with available MR simulation images, the VC was retrospectively contoured on T2W images, and cases were replanned to treat the upper VC to a dose of 7 Gy/fraction prescribed to 5 mm. Relevantmore » dose-volume parameters for the VC were calculated. Results: T2W MRI identified significant underdosing not observed on CT or T1-weighted imaging. Over two-thirds (69%) of patients had at least 1 cm{sup 3} of VC that received less than 75% of the prescription dose and half (50%) of patients had a least 1 cm{sup 3} of VC that received less than 50% of the prescription dose. The mean minimum point dose to the VC was 2.4 Gy, or 34% of the intended prescription dose (range: 0.53-6.4 Gy). Conclusions: We identified previously unreported VC underdosing in over two-thirds of our patients, with most of these patients having volumes of undistended VC that received less than half of the prescription dose. The maximum dimension was along the craniocaudal axis in some patients or left-right/anterior-posterior axis in others, suggesting that suture material may be restricting access to the vaginal apex and that alternative applicators may be needed when the diameter of the apex is larger than the introitus. Additional follow-up will be needed to determine whether underdosing is associated with isolated VC failure or whether low failure rates across the cohort suggest that some patients are being exposed to excessive dose and unnecessary risk of toxicity.« less

Involvement of Trigeminal Transition Zone and Laminated Subnucleus Caudalis in Masseter Muscle Hypersensitivity Associated with Tooth Inflammation

PubMed Central

Shimizu, Kohei; Matsumoto, Kunihito; Noma, Noboru; Matsuura, Shingo; Ohara, Kinuyo; Komiya, Hiroki; Watase, Tetsuro; Ogiso, Bunnai; Tsuboi, Yoshiyuki; Shinoda, Masamichi; Hatori, Keisuke; Nakaya, Yuka; Iwata, Koichi

2014-01-01

A rat model of pulpitis/periapical periodontitis was used to study mechanisms underlying extraterritorial enhancement of masseter response associated with tooth inflammation. Periapical bone loss gradually increased and peaked at 6 weeks after complete Freund’s adjuvant (CFA) application to the upper molar tooth pulp (M1). On day 3, the number of Fos-immunoreactive (IR) cells was significantly larger in M1 CFA rats compared with M1 vehicle (veh) rats in the trigeminal subnucleus interpolaris/caudalis transition zone (Vi/Vc). The number of Fos-IR cells was significantly larger in M1 CFA and masseter (Mass) capsaicin applied (M1 CFA/Mass cap) rats compared with M1 veh/Mass veh rats in the contralateral Vc and Vi/Vc. The number of phosphorylated extracellular signal-regulated kinase (pERK)-IR cells was significantly larger in M1 CFA/Mass cap and M1 veh/Mass cap rats compared to Mass-vehicle applied rats with M1 vehicle or CFA in the Vi/Vc. Pulpal CFA application caused significant increase in the number of Fos-IR cells in the Vi/Vc but not Vc on week 6. The number of pERK-IR cells was significantly lager in the rats with capsaicin application to the Mass compared to Mass-vehicle treated rats after pulpal CFA- or vehicle-application. However, capsaicin application to the Mass did not further affect the number of Fos-IR cells in the Vi/Vc in pulpal CFA-applied rats. The digastric electromyographic (d-EMG) activity after Mass-capsaicin application was significantly increased on day 3 and lasted longer at 6 weeks after pulpal CFA application, and these increase and duration were significantly attenuated by i.t. PD98059, a MEK1 inhibitor. These findings suggest that Vi/Vc and Vc neuronal excitation is involved in the facilitation of extraterritorial hyperalgesia for Mass primed with periapical periodontitis or acute pulpal-inflammation. Furthermore, phosphorylation of ERK in the Vi/Vc and Vc play pivotal roles in masseter hyperalgesia after pulpitis or periapical periodontitis. PMID:25279551

Joint Dictionary Learning-Based Non-Negative Matrix Factorization for Voice Conversion to Improve Speech Intelligibility After Oral Surgery.

PubMed

Fu, Szu-Wei; Li, Pei-Chun; Lai, Ying-Hui; Yang, Cheng-Chien; Hsieh, Li-Chun; Tsao, Yu

2017-11-01

Objective: This paper focuses on machine learning based voice conversion (VC) techniques for improving the speech intelligibility of surgical patients who have had parts of their articulators removed. Because of the removal of parts of the articulator, a patient's speech may be distorted and difficult to understand. To overcome this problem, VC methods can be applied to convert the distorted speech such that it is clear and more intelligible. To design an effective VC method, two key points must be considered: 1) the amount of training data may be limited (because speaking for a long time is usually difficult for postoperative patients); 2) rapid conversion is desirable (for better communication). Methods: We propose a novel joint dictionary learning based non-negative matrix factorization (JD-NMF) algorithm. Compared to conventional VC techniques, JD-NMF can perform VC efficiently and effectively with only a small amount of training data. Results: The experimental results demonstrate that the proposed JD-NMF method not only achieves notably higher short-time objective intelligibility (STOI) scores (a standardized objective intelligibility evaluation metric) than those obtained using the original unconverted speech but is also significantly more efficient and effective than a conventional exemplar-based NMF VC method. Conclusion: The proposed JD-NMF method may outperform the state-of-the-art exemplar-based NMF VC method in terms of STOI scores under the desired scenario. Significance: We confirmed the advantages of the proposed joint training criterion for the NMF-based VC. Moreover, we verified that the proposed JD-NMF can effectively improve the speech intelligibility scores of oral surgery patients. Objective: This paper focuses on machine learning based voice conversion (VC) techniques for improving the speech intelligibility of surgical patients who have had parts of their articulators removed. Because of the removal of parts of the articulator, a patient's speech may be distorted and difficult to understand. To overcome this problem, VC methods can be applied to convert the distorted speech such that it is clear and more intelligible. To design an effective VC method, two key points must be considered: 1) the amount of training data may be limited (because speaking for a long time is usually difficult for postoperative patients); 2) rapid conversion is desirable (for better communication). Methods: We propose a novel joint dictionary learning based non-negative matrix factorization (JD-NMF) algorithm. Compared to conventional VC techniques, JD-NMF can perform VC efficiently and effectively with only a small amount of training data. Results: The experimental results demonstrate that the proposed JD-NMF method not only achieves notably higher short-time objective intelligibility (STOI) scores (a standardized objective intelligibility evaluation metric) than those obtained using the original unconverted speech but is also significantly more efficient and effective than a conventional exemplar-based NMF VC method. Conclusion: The proposed JD-NMF method may outperform the state-of-the-art exemplar-based NMF VC method in terms of STOI scores under the desired scenario. Significance: We confirmed the advantages of the proposed joint training criterion for the NMF-based VC. Moreover, we verified that the proposed JD-NMF can effectively improve the speech intelligibility scores of oral surgery patients.

Brca2 (XRCC11) Deficiency Results in Radioresistant DNA Synthesis and a Higher Frequency of Spontaneous Deletions

PubMed Central

Kraakman-van der Zwet, Maria; Overkamp, Wilhelmina J. I.; van Lange, Rebecca E. E.; Essers, Jeroen; van Duijn-Goedhart, Annemarie; Wiggers, Ingrid; Swaminathan, Srividya; van Buul, Paul P. W.; Errami, Abdellatif; Tan, Raoul T. L.; Jaspers, Nicolaas G. J.; Sharan, Shyam K.; Kanaar, Roland; Zdzienicka, Małgorzata Z.

2002-01-01

We show here that the radiosensitive Chinese hamster cell mutant (V-C8) of group XRCC11 is defective in the breast cancer susceptibility gene Brca2. The very complex phenotype of V-C8 cells is complemented by a single human chromosome 13 providing the BRCA2 gene, as well as by the murine Brca2 gene. The Brca2 deficiency in V-C8 cells causes hypersensitivity to various DNA-damaging agents with an extreme sensitivity toward interstrand DNA cross-linking agents. Furthermore, V-C8 cells show radioresistant DNA synthesis after ionizing radiation, suggesting that Brca2 deficiency affects cell cycle checkpoint regulation. In addition, V-C8 cells display tremendous chromosomal instability and a high frequency of abnormal centrosomes. The mutation spectrum at the hprt locus showed that the majority of spontaneous mutations in V-C8 cells are deletions, in contrast to wild-type V79 cells. A mechanistic explanation for the genome instability phenotype of Brca2-deficient cells is provided by the observation that the nuclear localization of the central DNA repair protein in homologous recombination, Rad51, is reduced in V-C8 cells. PMID:11756561

Insights on the SO2 Poisoning of Pt3Co/VC and Pt/VC Fuel Cell Catalysts

DTIC Science & Technology

2010-01-01

catalyst is performed at the cathode of proton exchange membrane fuel cells ( PEMFCs ) in order to link previously reported results at the elec- trode...stripping voltammetry and underpotential deposition (upd) of copper adatoms. Then the performance of PEMFC cathodes employing 30wt.% Pt3Co/VC and 50wt.% Pt/VC...proton exchange membrane fuel cells( PEMFCs )in order to link previously reported results at the elec- trode/solution interface to the FC environment. First

Adaptive Controls Method Demonstrated for the Active Suppression of Instabilities in Engine Combustors

NASA Technical Reports Server (NTRS)

Kopasakis, George

2004-01-01

An adaptive feedback control method was demonstrated that suppresses thermoacoustic instabilities in a liquid-fueled combustor of a type used in aircraft engines. Extensive research has been done to develop lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle to reduce the environmental impact of aerospace propulsion systems. However, these lean-burning combustors are susceptible to thermoacoustic instabilities (high-frequency pressure waves), which can fatigue combustor components and even the downstream turbine blades. This can significantly decrease the safe operating lives of the combustor and turbine. Thus, suppressing the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors under NASA's Propulsion and Power Program. This control methodology has been developed and tested in a partnership of the NASA Glenn Research Center, Pratt & Whitney, United Technologies Research Center, and the Georgia Institute of Technology. Initial combustor rig testing of the controls algorithm was completed during 2002. Subsequently, the test results were analyzed and improvements to the method were incorporated in 2003, which culminated in the final status of this controls algorithm. This control methodology is based on adaptive phase shifting. The combustor pressure oscillations are sensed and phase shifted, and a high-frequency fuel valve is actuated to put pressure oscillations into the combustor to cancel pressure oscillations produced by the instability.

Idealized gas turbine combustor for performance research and validation of large eddy simulations.

PubMed

Williams, Timothy C; Schefer, Robert W; Oefelein, Joseph C; Shaddix, Christopher R

2007-03-01

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine combustors, and unrestrictive access for laser and optical diagnostic measurements. After discussing the design detail, a preliminary investigation of the performance and operating envelope of the combustor is presented. With the combustor operating on premixed methane/air, both the equivalence ratio and the inlet velocity were systematically varied and the flame structure was recorded via digital photography. Interesting lean flame blowout and resonance characteristics were observed. In addition, the combustor exhibited a large region of stable, acoustically clean combustion that is suitable for preliminary validation of LES models.

Methods for reducing pollutant emissions from jet aircraft

NASA Technical Reports Server (NTRS)

Butze, H. F.

1971-01-01

Pollutant emissions from jet aircraft and combustion research aimed at reducing these emissions are defined. The problem of smoke formation and results achieved in smoke reduction from commercial combustors are discussed. Expermental results of parametric tests performed on both conventional and experimental combustors over a range of combustor-inlet conditions are presented. Combustor design techniques for reducing pollutant emissions are discussed. Improved fuel atomization resulting from the use of air-assist fuel nozzles has brought about significant reductions in hydrocarbon and carbon monoxide emissions at idle. Diffuser tests have shown that the combustor-inlet airflow profile can be controlled through the use of diffuser-wall bleed and that it may thus be possible to reduce emissions by controlling combustor airflow distribution. Emissions of nitric oxide from a shortlength annular swirl-can combustor were significantly lower than those from a conventional combustor operating at similar conditions.

Test results of low NO(x) catalytic combustors for gas turbines

NASA Astrophysics Data System (ADS)

Ozawa, Y.; Hirano, J.; Sato, M.; Saiga, M.; Watanabe, S.

1994-07-01

Catalytic combustion is an ultralow NO(x) combustion method, so it is expected that this method will be applied to a gas turbine combustor. However, it is difficult to develop a catalytic combustor because catalytic reliability at high temperature is still insufficient. To overcome this difficulty, we designed a catalytic combust gas at a combustion temperature of 1300 C while keeping the catalytic temperature below 1000 C. After performing preliminary tests using LPG, we designed two types of combustor for natural gas with a capacity equivalent to one combustor used in a 20 MW class multican-type gas turbine. Combustion tests were conducted at atmospheric pressure using natural gas. As a result, it was confirmed that a combustor in which catalytic combustor segments were arranged alternately with premixing nozzles could achieve low NO(x) and high combustion efficiency in the range from 1000 C to 1300 C of the combustor exit gas temperature.

Structural and biochemical studies on Vibrio cholerae Hsp31 reveals a novel dimeric form and Glutathione-independent Glyoxalase activity

PubMed Central

Dey, Sanjay

2017-01-01

Vibrio cholerae experiences a highly hostile environment at human intestine which triggers the induction of various heat shock genes. The hchA gene product of V. cholerae O395, referred to a hypothetical intracellular protease/amidase VcHsp31, is one such stress-inducible homodimeric protein. Our current study demonstrates that VcHsp31 is endowed with molecular chaperone, amidopeptidase and robust methylglyoxalase activities. Through site directed mutagenesis coupled with biochemical assays on VcHsp31, we have confirmed the role of residues in the vicinity of the active site towards amidopeptidase and methylglyoxalase activities. VcHsp31 suppresses the aggregation of insulin in vitro in a dose dependent manner. Through crystal structures of VcHsp31 and its mutants, grown at various temperatures, we demonstrate that VcHsp31 acquires two (Type-I and Type-II) dimeric forms. Type-I dimer is similar to EcHsp31 where two VcHsp31 monomers associate in eclipsed manner through several intersubunit hydrogen bonds involving their P-domains. Type-II dimer is a novel dimeric organization, where some of the intersubunit hydrogen bonds are abrogated and each monomer swings out in the opposite directions centering at their P-domains, like twisting of wet cloth. Normal mode analysis (NMA) of Type-I dimer shows similar movement of the individual monomers. Upon swinging, a dimeric surface of ~400Å2, mostly hydrophobic in nature, is uncovered which might bind partially unfolded protein substrates. We propose that, in solution, VcHsp31 remains as an equilibrium mixture of both the dimers. With increase in temperature, transformation to Type-II form having more exposed hydrophobic surface, occurs progressively accounting for the temperature dependent increase of chaperone activity of VcHsp31. PMID:28235098

Rapid detection of the Vibrio cholerae ctx gene in food enrichments using real-time polymerase chain reaction.

PubMed

Fedio, Willis; Blackstone, George M; Kikuta-Oshima, Lynne; Wendakoon, Chitra; McGrath, Timothy H; DePaola, Angelo

2007-01-01

A real-time polymerase chain reaction (qPCR) assay for the detection of the ctxA gene of toxigenic Vibrio cholerae (Vc) was validated against standard culture techniques. The first experimental phase determined optimal enrichment conditions for detection by culture and qPCR of Vc in shrimp, bottled water, milk, and potato salad. The conditions tested included temperature (35 and 42 degrees C), time (6 and 18 h), and effect of shaking (0 and 100 rpm). No definitive trends were found with enrichment temperature or shaking on Vc isolation frequency or detection by qPCR. Generally, Vc was detected by qPCR more frequently than Vc was isolated, but this difference was significant only in the 35 degrees C 6 h enrichment without shaking. In the second phase of experiments, shrimp, bottled water, milk, potato salad, and oysters were inoculated with each of 3 toxigenic Vc strains (Latin American O1 strain, an O139 strain, and an O1 strain from the U.S. Gulf Coast) and enriched under static conditions at 42OC for 6 and 18 h. Overall, detection frequency of ctx by qPCR was 98% (88/90) and 100% (90/90) after 6 and 18 h enrichments, respectively, while Vc isolation frequency was 87% (78/90) and 83% (75/90) after 6 and 18 h, respectively. Toxigenic Vc can be detected by qPCR within an 8 h work day using the 6 h enrichment procedure, assuming an initial level of at least 1-2 colony-forming units/g; however, overnight enrichment may be necessary to detect lower levels. These data indicate that the qPCR assay for ctx is a more reliable, sensitive, and rapid alternative to standard Vc culture methods and is applicable to diverse food products.

New echocardiographic windows for quantitative determination of aortic regurgitation volume using color Doppler flow convergence and vena contracta

NASA Technical Reports Server (NTRS)

Shiota, T.; Jones, M.; Agler, D. A.; McDonald, R. W.; Marcella, C. P.; Qin, J. X.; Zetts, A. D.; Greenberg, N. L.; Cardon, L. A.; Sun, J. P.;

Ascidian sperm glycosylphosphatidylinositol-anchored CRISP-like protein as a binding partner for an allorecognizable sperm receptor on the vitelline coat.

PubMed

Urayama, Satoshi; Harada, Yoshito; Nakagawa, Yoko; Ban, Susumu; Akasaka, Mari; Kawasaki, Nana; Sawada, Hitoshi

2008-08-01

Although ascidians are hermaphroditic, many species including Halocynthia roretzi are self-sterile. We previously reported that a vitelline coat polymorphic protein HrVC70, consisting of 12 EGF (epidermal growth factor)-like repeats, is a candidate allorecognition protein in H. roretzi, because the isolated HrVC70 shows higher affinity to nonself-sperm than to self-sperm. Here, we show that a sperm 35-kDa glycosylphosphatidylinositol-anchored CRISP (cysteine-rich secretory protein)-like protein HrUrabin in a low density detergent-insoluble membrane fraction is a physiological binding partner for HrVC70. We found that HrVC70 specifically interacts with HrUrabin, which had been separated by SDS-PAGE and transferred onto a nitrocellulose membrane. HrUrabin has an N-linked sugar chain, essential for binding to HrVC70. HrUrabin mRNA is expressed in the testis but not in the ovary, and the protein appears to be localized on the surface of sperm head and tail. Anti-HrUrabin antibody, which neutralizes the interaction between HrUrabin and HrVC70, potently inhibited fertilization and allorecognizable sperm-binding to HrVC70-agarose. However, no significant difference in the binding ability of HrUrabin to HrVC70 was observed in autologous and allogeneic combinations by Far Western analyses. These results indicate that sperm-egg binding in H. roretzi is mediated by the molecular interaction between HrUrabin on the sperm surface and HrVC70 on the vitelline coat, but that HrUrabin per se is unlikely to be a direct allorecognition protein.

Hepatitis C videoconferencing: the impact on continuing medical education for rural healthcare providers.

PubMed

Rossaro, Lorenzo; Tran, Thu P; Ransibrahmanakul, Kanat; Rainwater, Julie A; Csik, Genell; Cole, Stacey L; Prosser, Colette C; Nesbitt, Thomas S

2007-06-01

This study compared the impact of multipoint videoconferencing (VC) versus standard lecturing (ST) on primary care providers' (MDs, NPs/PAs, and RNs) education regarding hepatitis C virus (HCV). The hypothesis was that the educational impact of teaching through telemedicine is comparable to the traditional method. The aim was to provide participants clinically relevant information and knowledge about the natural history, diagnosis, and management of HCV. Improved knowledge was scored from a 10-item quiz administered before and after the educational intervention. Comparison of the pretest knowledge scores within provider groups showed no statistically significant difference in baseline knowledge for the ST versus VC method. However, for all practitioners combined, the VC group scored significantly lower on the pretest than the ST group (p < 0.05). All three types of learners improved their knowledge scores following intervention. On average, MDs and NP/PAs correctly answered two to 3.5 more questions in the posttest. RNs showed the greatest improvements, correctly answering an average of four to five more questions following intervention. Improvement in knowledge scores between the two methods was statistically significant in favor of VC for the MDs (VC = 3.56 +/- 1.92 vs. ST = 2.13 +/- 1.89, p < 0.001) and all groups combined (VC 4.37 +/- 1.92 vs ST 3.06 +/- 1.89, p < 0.001). The results of this study indicate that VC is equivalent, if not better, than standard continuing medical education (CME). VC can potentially improve clinician education regarding the history, diagnosis, and management of HCV, thereby making a substantial impact on the clinical course of patients with this condition. In addition, VC has the potential to eliminate the financial and geographic barriers to professional education for rural practitioners.

New echocardiographic windows for quantitative determination of aortic regurgitation volume using color Doppler flow convergence and vena contracta.

PubMed

Shiota, T; Jones, M; Agler, D A; McDonald, R W; Marcella, C P; Qin, J X; Zetts, A D; Greenberg, N L; Cardon, L A; Sun, J P; Sahn, D J; Thomas, J D

1999-04-01

Color Doppler images of aortic regurgitation (AR) flow acceleration, flow convergence (FC), and the vena contracta (VC) have been reported to be useful for evaluating severity of AR. However, clinical application of these methods has been limited because of the difficulty in clearly imaging the FC and VC. This study aimed to explore new windows for imaging the FC and VC to evaluate AR volumes in patients and to validate this in animals with chronic AR. Forty patients with AR and 17 hemodynamic states in 4 sheep with strictly quantified AR volumes were evaluated. A Toshiba SSH 380A with a 3.75-MHz transducer was used to image the FC and VC. After routine echo Doppler imaging, patients were repositioned in the right lateral decubitus position, and the FC and VC were imaged from high right parasternal windows. In only 15 of the 40 patients was it possible to image clearly and measure accurately the FC and VC from conventional (left decubitus) apical or parasternal views. In contrast, 31 of 40 patients had clearly imaged FC regions and VCs using the new windows. In patients, AR volumes derived from the FC and VC methods combined with continuous velocity agreed well with each other (r = 0.97, mean difference = -7.9 ml +/- 9.9 ml/beat). In chronic animal model studies, AR volumes derived from both the VC and the FC agreed well with the electromagnetically derived AR volumes (r = 0.92, mean difference = -1.3 +/- 4.0 ml/beat). By imaging from high right parasternal windows in the right decubitus position, complementary use of the FC and VC methods can provide clinically valuable information about AR volumes.

Experimental Assessment of the Emissions Control Potential of a Rich/Quench/Lean Combustor for High Speed Civil Transport Aircraft Engines

NASA Technical Reports Server (NTRS)

Rosfjord, T. J.; Padget, F. C.; Tacina, Robert R. (Technical Monitor)

2001-01-01

In support of Pratt & Whitney efforts to define the Rich burn/Quick mix/Lean burn (RQL) combustor for the High Speed Civil Transport (HSCT) aircraft engine, UTRC conducted a flametube-scale study of the RQL concept. Extensive combustor testing was performed at the Supersonic Cruise (SSC) condition of a HSCT engine cycle, Data obtained from probe traverses near the exit of the mixing section confirmed that the mixing section was the critical component in controlling combustor emissions. Circular-hole configurations, which produced rapidly-, highly-penetrating jets, were most effective in limiting NOx. The spatial profiles of NOx and CO at the mixer exit were not directly interpretable using a simple flow model based on jet penetration, and a greater understanding of the flow and chemical processes in this section are required to optimize it. Neither the rich-combustor equivalence ratio nor its residence time was a direct contributor to the exit NOx. Based on this study, it was also concluded that (1) While NOx formation in both the mixing section and the lean combustor contribute to the overall emission, the NOx formation in the mixing section dominates. The gas composition exiting the rich combustor can be reasonably represented by the equilibrium composition corresponding to the rich combustor operating condition. Negligible NOx exits the rich combustor. (2) At the SSC condition, the oxidation processes occurring in the mixing section consume 99 percent of the CO exiting the rich combustor. Soot formed in the rich combustor is also highly oxidized, with combustor exit SAE Smoke Number <3. (3) Mixing section configurations which demonstrated enhanced emissions control at SSC also performed better at part-power conditions. Data from mixer exit traverses reflected the expected mixing behavior for off-design jet to crossflow momentum-flux ratios. (4) Low power operating conditions require that the RQL combustor operate as a lean-lean combustor to achieve low CO and high efficiency. (5) A RQL combustor can achieve the emissions goal of EINOX = 5 at the Supersonic Cruise operating condition for a HSCT engine.

Experimental Assessment of the Emissions Control Potential of a Rich/Quench/ Lean Combustor for High Speed Civil Transport Aircraft Engines

NASA Technical Reports Server (NTRS)

Tacina, Robert R. (Technical Monitor); Rosfjord, T. J.; Padget, F. C.

2001-01-01

In support of Pratt & Whitney efforts to define the Rich burn/Quick mix/Lean burn (RQL) combustor for the High Speed Civil Transport (HSCT) aircraft engine, UTRC conducted a flametube-scale study of the RQL concept. Extensive combustor testing was performed at the Supersonic Cruise (SSC) condition of an HSCT engine cycle. Data obtained from probe traverses near the exit of the mixing section confirmed that the mixing section was the critical component in controlling combustor emissions. Circular-hole configurations, which produced rapidly-, highly-penetrating jets, were most effective in limiting NO(x). The spatial profiles of NO(x) and CO at the mixer exit were not directly interpretable using a simple flow model based on jet penetration, and a greater understanding of the flow and chemical processes in this section are required to optimize it. Neither the rich-combustor equivalence ratio nor its residence time was a direct contributor to the exit NO(x). Based on this study, it was also concluded that: (1) While NO(x) formation in both the mixing section and the lean combustor contribute to the overall emission, the NOx formation in the mixing section dominates. The gas composition exiting the rich combustor can be reasonably represented by the equilibrium composition corresponding to the rich combustor operating condition. Negligible NO(x) exits the rich combustor. (2) At the SSC condition, the oxidation processes occurring in the mixing section consume 99 percent of the CO exiting the rich combustor. Soot formed in the rich combustor is also highly oxidized, with combustor exit SAE Smoke Number <3. (3) Mixing section configurations which demonstrated enhanced emissions control at SSC also performed better at part-power conditions. Data from mixer exit traverses reflected the expected mixing behavior for off-design jet to crossflow momentum-flux ratios. (4) Low power operating conditions require that the RQL combustor operate as a lean-lean combustor to achieve low CO and high efficiency. (5) An RQL combustor can achieve the emissions goal of EINO(x) = 5 at the Supersonic Cruise operating condition for an HSCT engine.

Investigation of "6X" Scramjet Inlet Configurations

NASA Technical Reports Server (NTRS)

Alter, Stephen J.

2012-01-01

This work represents an initial attempt to determine what, if any, issues arise from scaling demonstration supersonic combustion scramjets to a flight scale making the engine a viable candidate for both military weapon and civilian access to space applications. The original vehicle sizes tested and flown to date, were designed to prove a concept. With the proven designs, use of the technology for applications as weapon systems or space flight are only possible at six to ten times the original scale. To determine effects of scaling, computations were performed with hypersonic inlets designed to operate a nominal Mach 4 and Mach 5 conditions that are possible within the eight foot high temperature tunnel at NASA Langley Research Center. The total pressure recovery for these inlets is about 70%, while maintaining self start conditions, and providing operable inflow to combustors. Based on this study, the primary scaling effect detected is the strength of a vortex created along the cowl edge causing adverse boundary layer growth in the inlet.

Innovative Adaptive Control Method Demonstrated for Active Suppression of Instabilities in Engine Combustors

NASA Technical Reports Server (NTRS)

Kopasakis, George

2005-01-01

This year, an improved adaptive-feedback control method was demonstrated that suppresses thermoacoustic instabilities in a liquid-fueled combustor of a type used in aircraft engines. Extensive research has been done to develop lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle to reduce the environmental impact of aerospace propulsion systems. However, these lean-burning combustors are susceptible to thermoacoustic instabilities (high-frequency pressure waves), which can fatigue combustor components and even downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppressing the thermoacoustic combustor instabilities is an enabling technology for meeting the low-emission goals of the NASA Ultra-Efficient Engine Technology (UEET) Project.

Systems Characterization of Combustor Instabilities With Controls Design Emphasis

NASA Technical Reports Server (NTRS)

Kopasakis, George

2004-01-01

This effort performed test data analysis in order to characterize the general behavior of combustor instabilities with emphasis on controls design. The analysis is performed on data obtained from two configurations of a laboratory combustor rig and from a developmental aero-engine combustor. The study has characterized several dynamic behaviors associated with combustor instabilities. These are: frequency and phase randomness, amplitude modulations, net random phase walks, random noise, exponential growth and intra-harmonic couplings. Finally, the very cause of combustor instabilities was explored and it could be attributed to a more general source-load type impedance interaction that includes the thermo-acoustic coupling. Performing these characterizations on different combustors allows for more accurate identification of the cause of these phenomena and their effect on instability.

Effects of Vernonia cinerea on reproductive performance in streptozotocin-induced diabetic rats.

PubMed

Pomjunya, Atchariya; Ratthanophart, Jasada; Fungfuang, Wirasak

2017-03-23

The present study investigated the effects of Vernonia cinerea (VC) on the reproductive function in streptozotocin (STZ)-induced diabetic male rats. Six-week-old male Sprague-Dawley rats were randomly divided into four groups: group 1, normal control rats; group 2, diabetic untreated rats; group 3, diabetic rats treated with VC (10 mg/kg); and group 4, diabetic rats treated with VC (40 mg/kg). Diabetes mellitus (DM) was induced by intraperitoneal injection of STZ (60 mg/kg). All animals were treated for 30 consecutive days. Body weight, blood glucose, food intake, epididymal sperm parameters, testicular microstructure and serum testosterone levels were evaluated. VC treatment significantly restored the sperm motility and testosterone concentration, and decreased the testicular histopathological changes in DM rats. Moreover, high-dose VC exhibited an antidibetic activity and significantly improved the sperm count. In conclusion, we found, for the first time, that administration of VC significantly restored the testicular function and testosterone concentration in diabetic male rats.

Effects of Vernonia cinerea on reproductive performance in streptozotocin-induced diabetic rats

PubMed Central

POMJUNYA, Atchariya; RATTHANOPHART, Jasada; FUNGFUANG, Wirasak

2017-01-01

The present study investigated the effects of Vernonia cinerea (VC) on the reproductive function in streptozotocin (STZ)-induced diabetic male rats. Six-week-old male Sprague-Dawley rats were randomly divided into four groups: group 1, normal control rats; group 2, diabetic untreated rats; group 3, diabetic rats treated with VC (10 mg/kg); and group 4, diabetic rats treated with VC (40 mg/kg). Diabetes mellitus (DM) was induced by intraperitoneal injection of STZ (60 mg/kg). All animals were treated for 30 consecutive days. Body weight, blood glucose, food intake, epididymal sperm parameters, testicular microstructure and serum testosterone levels were evaluated. VC treatment significantly restored the sperm motility and testosterone concentration, and decreased the testicular histopathological changes in DM rats. Moreover, high-dose VC exhibited an antidibetic activity and significantly improved the sperm count. In conclusion, we found, for the first time, that administration of VC significantly restored the testicular function and testosterone concentration in diabetic male rats. PMID:28190818

Quantification of vicine and convicine in faba bean seeds using hydrophilic interaction liquid chromatography.

PubMed

Purves, Randy W; Khazaei, Hamid; Vandenberg, Albert

2018-02-01

Faba bean (Vicia faba L.) provides environmental and health benefits; however, the presence of the pyrimidine glycosides vicine and convicine (v-c) in its seeds limits consumption. Low v-c genotypes have been introduced, but the convicine levels in these genotypes have not been quantified. To improve detection, the polar nature of v-c was exploited by implementing hydrophilic interaction liquid chromatography (HILIC). A sample preparation method using a two-step extraction was developed for use with UV and/or tandem mass spectrometry (SRM) detection. The HILIC-UV method was suitable for over three orders of magnitude, covering the range of v-c concentrations in faba bean seeds across all genotypes tested. The linear range of HILIC-SRM was slightly less (∼3 orders of magnitude), but improved sensitivity and selectivity make it more suitable for quantifying low v-c samples. The analysis of 13 genotypes suggests that v-c concentrations in faba bean seeds may be independent quantitative traits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Immunohistochemical expression of basement membrane proteins of verrucous carcinoma of the oral mucosa.

PubMed

Arduino, Paolo G; Carrozzo, Marco; Pagano, Marco; Broccoletti, Roberto; Scully, Crispian; Gandolfo, Sergio

2010-06-01

Squamous cell carcinoma (SCC) of the oral cavity is an extremely invasive tumour of stratified squamous epithelium that spreads throughout degradation of the basement membrane (BM) and extra-cellular matrix. Oral verrucous carcinoma (VC) is a rare low-grade variant of oral SCC that penetrates into the subepithelial connective tissue. It also has a different clinical behaviour from classical oral SCC. We investigated the immunohistochemical expression of laminin, laminin-5, collagen IV and fibronectin in VC, severe epithelial dysplasia (SED) and SCC in order to analyse if the pattern of these molecules expression contributes to the differences in the biological behaviour of these diseases. The staining pattern of laminin was less intensive in SCC compared with SED and VC, and collagen IV expression was increased in VC compared with SED. Discontinuities of laminin, collagen IV and fibronectin were more evident in SED than in VC. This study indicates that VC has a biological behaviour different from SED or SCC, observable by immunohistochemistry in the BM zone.

[Lung dysfunction in patients with mild chronic obstructive bronchitis].

PubMed

Nefedov, V B; Popova, L A; Shergina, E A

2004-01-01

VC, FVC, FEV1, FEV1/VC%, PEF, MEF25, MEF50, MEF75, TCL, TGV, RV, Ravt, Riin, Rex, DLCO-SS, PaO2, and PaO2 were determined in 33 patients with mild chronic obstructive lung disease (FEV1 > 70% of the normal value). All the patients were found to have impaired bronchial patency; most (63.6%) patients had lung volume and capacity changes, almost half (45.5%) the patients had pulmonary gas exchange dysfunction. Impaired bronchial patency mainly appeared as decreased MEF50, MEF15, and FEV1/VC%; altered lung volumes and capacities manifested chiefly by increased RV and decreased VC; pulmonary gas exchange dysfunction showed up primarily as lowered PaO2. The magnitude of the observed functional changes was generally slight. MEF50, MEF75, FEV1/VC%, and VC dropped to 59-20 and 79-70% of the normal value, respectively. RV increased up to 142-196% of the normal value; PaO2 reduced up to 79-60% mm Hg.

Low NO(x) Combustor Development

NASA Technical Reports Server (NTRS)

Kastl, J. A.; Herberling, P. V.; Matulaitis, J. M.

2005-01-01

The goal of these efforts was the development of an ultra-low emissions, lean-burn combustor for the High Speed Civil Transport. The HSCT Mach 2.4 FLADE C1 Cycle was selected as the baseline engine cycle. A preliminary compilation of performance requirements for the HSCT combustor system was developed. The emissions goals of the program, baseline engine cycle, and standard combustor performance requirements were considered in developing the compilation of performance requirements. Seven combustor system designs were developed. The development of these system designs was facilitated by the use of spreadsheet-type models which predicted performance of the combustor systems over the entire flight envelope of the HSCT. A chemical kinetic model was developed for an LPP combustor and employed to study NO(x) formation kinetics, and CO burnout. These predictions helped to define the combustor residence time. Five fuel-air mixer concepts were analyzed for use in the combustor system designs. One of the seven system designs, one using the Swirl-Jet and Cyclone Swirler fuel-air mixers, was selected for a preliminary mechanical design study.

Dietary l-Lysine Prevents Arterial Calcification in Adenine-Induced Uremic Rats

PubMed Central

Shimomura, Akihiro; Matsui, Isao; Hamano, Takayuki; Ishimoto, Takuya; Katou, Yumiko; Takehana, Kenji; Inoue, Kazunori; Kusunoki, Yasuo; Mori, Daisuke; Nakano, Chikako; Obi, Yoshitsugu; Fujii, Naohiko; Takabatake, Yoshitsugu; Nakano, Takayoshi; Tsubakihara, Yoshiharu; Rakugi, Hiromi

2014-01-01

Vascular calcification (VC) is a life-threatening complication of CKD. Severe protein restriction causes a shortage of essential amino acids, and exacerbates VC in rats. Therefore, we investigated the effects of dietary l-lysine, the first-limiting amino acid of cereal grains, on VC. Male Sprague-Dawley rats at age 13 weeks were divided randomly into four groups: low-protein (LP) diet (group LP), LP diet+adenine (group Ade), LP diet+adenine+glycine (group Gly) as a control amino acid group, and LP diet+adenine+l-lysine·HCl (group Lys). At age 18 weeks, group LP had no VC, whereas groups Ade and Gly had comparable levels of severe VC. l-Lysine supplementation almost completely ameliorated VC. Physical parameters and serum creatinine, urea nitrogen, and phosphate did not differ among groups Ade, Gly, and Lys. Notably, serum calcium in group Lys was slightly but significantly higher than in groups Ade and Gly. Dietary l-lysine strongly suppressed plasma intact parathyroid hormone in adenine rats and supported a proper bone-vascular axis. The conserved orientation of the femoral apatite in group Lys also evidenced the bone-protective effects of l-lysine. Dietary l-lysine elevated plasma alanine, proline, arginine, and homoarginine but not lysine. Analyses in vitro demonstrated that alanine and proline inhibit apoptosis of cultured vascular smooth muscle cells, and that arginine and homoarginine attenuate mineral precipitations in a supersaturated calcium/phosphate solution. In conclusion, dietary supplementation of l-lysine ameliorated VC by modifying key pathways that exacerbate VC. PMID:24652795

Evaluating How Post-Bronchodilator Vital Capacities Affect the Diagnosis of Obstruction in Pulmonary Function Tests.

PubMed

Blagev, Denitza P; Sorenson, Dean; Linares-Perdomo, Olinto; Bamberg, Stacy; Hegewald, Matthew; Morris, Alan H

2016-11-01

Although the ratio of FEV 1 to the vital capacity (VC) is universally accepted as the cornerstone of pulmonary function test (PFT) interpretation, FVC remains in common use. We sought to determine what the differences in PFT interpretation were when the largest measured vital capacity (VC max ) was used instead of the FVC. We included 12,238 consecutive PFTs obtained for routine clinical care. We interpreted all PFTs first using FVC in the interpretation algorithm and then again using the VC max , obtained either before or after administration of inhaled bronchodilator. Six percent of PFTs had an interpretive change when VC max was used instead of FVC. The most common changes were: new diagnosis of obstruction and exclusion of restriction (previously suggested by low FVC without total lung capacity measured by body plethysmography). A nonspecific pattern occurred in 3% of all PFT interpretations with FVC. One fifth of these 3% produced a new diagnosis of obstruction with VC max . The largest factors predicting a change in PFT interpretation with VC max were a positive bronchodilator response and the administration of a bronchodilator. Larger FVCs decreased the odds of PFT interpretation change. Surprisingly, the increased numbers of PFT tests did not increase odds of PFT interpretation change. Six percent of PFTs have a different interpretation when VC max is used instead of FVC. Evaluating borderline or ambiguous PFTs using the VC max may be informative in diagnosing obstruction and excluding restriction. Copyright © 2016 by Daedalus Enterprises.

Steam reformer with catalytic combustor

DOEpatents

Voecks, Gerald E.

1990-03-20

A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

Small gas turbine combustor experimental study - Compliant metal/ceramic liner and performance evaluation

NASA Technical Reports Server (NTRS)

Acosta, W. A.; Norgren, C. T.

1986-01-01

Combustor research relating to the development of fuel efficient small gas turbine engines capable of meeting future commercial and military aviation needs is currently underway at NASA Lewis. As part of this combustor research, a basic reverse-flow combustor has been used to investigate advanced liner wall cooling techniques. Liner temperature, performance, and exhaust emissions of the experimental combustor utilizing compliant metal/ceramic liners were determined and compared with three previously reported combustors that featured: (1)splash film-cooled liner walls; (2) transpiration cooled liner walls; and (3) counter-flow film cooled panels.

Small gas turbine combustor experimental study: Compliant metal/ceramic liner and performance evaluation

NASA Technical Reports Server (NTRS)

Acosta, W. A.; Norgren, C. T.

1986-01-01

Combustor research relating to the development of fuel efficient small gas turbine engines capable of meeting future commercial and military aviation needs is currently underway at NASA Lewis. As part of this combustor research, a basic reverse-flow combustor has been used to investigate advanced liner wall cooling techniques. Liner temperature, performance, and exhaust emissions of the experimental combustor utilizing compliant metal/ceramic liners were determined and compared with three previously reported combustors that featured: (1) splash film-cooled liner walls; (2) transpiration cooled liner walls; and (3) counter-flow film cooled panels.

Computations of soot and and NO sub x emissions from gas turbine combustors

NASA Technical Reports Server (NTRS)

Srivatsa, S. K.

1982-01-01

An analytical program was conducted to compute the soot and NOx emissions from a combustor and the radiation heat transfer to the combustor walls. The program involved the formulation of an emission and radiation model and the incorporation of this model into the Garrett 3-D Combustor Perfomance Computer Program. Computations were performed for the idle, cruise, and take-off conditions of a JT8D can combustor. The predicted soot and NOx emissions and the radiation heat transfer to the combustor walls agree reasonably well with the limited experimental data available.

Energy Efficient Engine: Combustor component performance program

NASA Technical Reports Server (NTRS)

Dubiel, D. J.

1986-01-01

The results of the Combustor Component Performance analysis as developed under the Energy Efficient Engine (EEE) program are presented. This study was conducted to demonstrate the aerothermal and environmental goals established for the EEE program and to identify areas where refinements might be made to meet future combustor requirements. In this study, a full annular combustor test rig was used to establish emission levels and combustor performance for comparison with those indicated by the supporting technology program. In addition, a combustor sector test rig was employed to examine differences in emissions and liner temperatures obtained during the full annular performance and supporting technology tests.

Steam reformer with catalytic combustor

NASA Technical Reports Server (NTRS)

Voecks, Gerald E. (Inventor)

1990-01-01

A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

Downhole steam generator with improved preheating/cooling features

DOEpatents

Donaldson, A. Burl; Hoke, Donald E.; Mulac, Anthony J.

1983-01-01

An apparatus for downhole steam generation employing dual-stage preheaters for liquid fuel and for the water. A first heat exchange jacket for the fuel surrounds the fuel/oxidant mixing section of the combustor assembly downstream of the fuel nozzle and contacts the top of the combustor unit of the combustor assembly, thereby receiving heat directly from the combustion of the fuel/oxidant. A second stage heat exchange jacket surrounds an upper portion of the oxidant supply line adjacent the fuel nozzle receiving further heat from the compression heat which results from pressurization of the oxidant. The combustor unit includes an inner combustor sleeve whose inner wall defines the combustion zone. The inner combustor sleeve is surrounded by two concentric water channels, one defined by the space between the inner combustor sleeve and an intermediate sleeve, and the second defined by the space between the intermediate sleeve and an outer cylindrical housing. The channels are connected by an annular passage adjacent the top of the combustor assembly and the countercurrent nature of the water flow provides efficient cooling of the inner combustor sleeve. An annular water ejector with a plurality of nozzles is provided to direct water downwardly into the combustor unit at the boundary of the combustion zone and along the lower section of the intermediate sleeve.

Downhole steam generator with improved preheating/cooling features. [Patent application

DOEpatents

Donaldson, A.B.; Hoke, D.E.; Mulac, A.J.

1980-10-10

An apparatus is described for downhole steam generation employing dual-stage preheaters for liquid fuel and for the water. A first heat exchange jacket for the fuel surrounds the fuel/oxidant mixing section of the combustor assembly downstream of the fuel nozzle and contacts the top of the combustor unit of the combustor assembly, thereby receiving heat directly from the combustion of the fuel/oxidant. A second stage heat exchange jacket surrounds an upper portion of the oxidant supply line adjacent the fuel nozzle receiving further heat from the compression heat which results from pressurization of the oxidant. The combustor unit includes an inner combustor sleeve whose inner wall defines the combustion zone. The inner combustor sleeve is surrounded by two concentric water channels, one defined by the space between the inner combustor sleeve and an intermediate sleeve, and the second defined by the space between the intermediate sleeve and an outer cylindrical housing. The channels are connected by an annular passage adjacent the top of the combustor assembly and the countercurrent nature of the water flow provides efficient cooling of the inner combustor sleeve. An annular water ejector with a plurality of nozzles is provided to direct water downwardly into the combustor unit at the boundary of the combustion zone and along the lower section of the intermediate sleeve.

Photosynthesis, Earth System Models and the Arctic

NASA Astrophysics Data System (ADS)

Rogers, A.; Sloan, V. L.; Xu, C.; Wullschleger, S. D.

2013-12-01

The primary goal of Earth System Models (ESMs) is to improve understanding and projection of future global change. In order to do this they must accurately represent the huge carbon fluxes associated with the terrestrial carbon cycle. Photosynthetic CO2 uptake is the largest of these fluxes, and is well described by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis. Most ESMs use a derivation of the FvCB model to calculate gross primary productivity (GPP). One of the key parameters required by the FvCB model is an estimate of the maximum rate of carboxylation by the enzyme Rubisco (Vc,max). In ESMs the parameter Vc,max is usually fixed for a given plant functional type (PFT). Although Arctic GPP a small flux relative to global GPP, uncertainty is large. Only four ESMs currently have an explicit Arctic PFT and the data used to derive Vc,max for the Arctic PFT in these models relies on small data sets and unjustified assumptions. As part of a multidisciplinary project to improve the representation of the Arctic in ESMs (Next Generation Ecosystem Experiments - Arctic) we examined the derivation of Vc,max in current Arctic PFTs and estimated Vc,max for 12 species representing both dominant vegetation and key PFTs growing on the Barrow Environmental Observatory, Barrow, AK. The values of Vc,max currently used to represent Arctic PFTs in ESMs are 70% lower than the values we measured in these species. Separate measurements of CO2 assimilation (A) made at ambient conditions were compared with A modeled using the Vc,max values we measured in Barrow and those used by the ESMs. The A modeled with the Vc,max values used by the ESMs was 80% lower than the observed A. When our measured Vc,max values were used, modeled A was within 5% of observed A. Examination of the derivation of Vc,max in ESMs identified that the cause of the relatively low Vc,max value was the result of underestimating both the leaf N content and the investment of that N in Rubisco. Here we have identified possible improvements to the derivation of Vc,max in ESMs and provided new physiological characterization of Arctic species that is mechanistically consistent with observed leaf level CO2 uptake. These data suggest that the Arctic tundra has a much greater capacity for CO2 uptake than is currently represented in ESMs. Our parameterization can be used in future model projections to improve representation of the Arctic landscape in ESMs.

Effects of faba beans with different concentrations of vicine and convicine on egg production, egg quality and red blood cells in laying hens.

PubMed

Lessire, M; Gallo, V; Prato, M; Akide-Ndunge, O; Mandili, G; Marget, P; Arese, P; Duc, G

2017-08-01

The faba bean (Vicia faba L.) is a potential source of proteins for poultry, mainly for laying hens whose protein requirements are lower than those of other birds such as growing broilers and turkeys. However, this feedstuff contains anti-nutritional factors, that is, vicine (V) and convicine (C) that are already known to reduce laying hen performance. The aim of the experiment reported here was to evaluate the effects of a wide range of dietary V and C concentrations in laying hens. Two trials were performed with laying hens fed diets including 20% or 25% of faba bean genotypes highly contrasting in V+C content. In Trial 1, faba beans from two tannin-containing cultivars, but with high or low V+C content were dehulled in order to eliminate the tannin effect. In addition to the contrasting levels of V+C in the two cultivars, two intermediate levels of V+C were obtained by mixing the two cultivars (70/30 and 30/70). In Trial 2, two isogenic zero-tannin faba bean genotypes with high or low V+C content were used. In both trials, a classical corn-soybean diet was also offered to control hens. Each experimental diet was given to 48 laying hens for 140 (Trial 1) or 89 (Trial 2) days. Laying performance and egg quality were measured. The redox sensitivity of red blood cells (RBCs) was assessed by measuring hemolysis and reduced glutathione (GSH) concentration in these cells. Egg weight was significantly reduced by the diets containing the highest concentrations of V+C (P<0.0001) in Trial 1 and slightly reduced (P<0.10) in Trial 2, but only weak linear relationships between egg weight and dietary V+C concentration were established. No negative effect of V+C level was observed for egg quality parameters. In contrast, certain parameters (i.e. Haugh units, yolk color) were improved by feeding low V+C diets (P<0.05). Hemolysis of RBCs was higher in hens fed high V+C diets. A decrease in GSH concentration in RBCs of hens fed the highest levels of V+C was observed. Faba bean genotypes with low concentrations of V+C can therefore be used in laying hen diets up to 25% without any detrimental effects on performance levels or egg characteristics, without any risk of hemolysis of RBCs.

Fundamental Insights into Combustion Instability Predictions in Aerospace Propulsion

NASA Astrophysics Data System (ADS)

Huang, Cheng

Integrated multi-fidelity modeling has been performed for combustion instability in aerospace propulsion, which includes two levels of analysis: first, computational fluid dynamics (CFD) using hybrid RANS/LES simulations for underlying physics investigations (high-fidelity modeling); second, modal decomposition techniques for diagnostics (analysis & validation); third, development of flame response model using model reduction techniques for practical design applications (low-order model). For the high-fidelity modeling, the relevant CFD code development work is moving towards combustion instability prediction for liquid propulsion system. A laboratory-scale single-element lean direct injection (LDI) gas turbine combustor is used for configuration that produces self-excited combustion instability. The model gas turbine combustor is featured with an air inlet section, air plenum, swirler-venturi-injector assembly, combustion chamber, and exit nozzle. The combustor uses liquid fuel (Jet-A/FT-SPK) and heated air up to 800K. Combustion dynamics investigations are performed with the same geometry and operating conditions concurrently between the experiment and computation at both high (φ=0.6) and low (φ=0.36) equivalence ratios. The simulation is able to reach reasonable agreement with experiment measurements in terms of the pressure signal. Computational analyses are also performed using an acoustically-open geometry to investigate the characteristic hydrodynamics in the combustor with both constant and perturbed inlet mass flow rates. Two hydrodynamic modes are identified by using Dynamic Mode Decomposition (DMD) analysis: Vortex Breakdown Bubble (VBB) and swirling modes. Following that, the closed geometry simulation results are analyzed in three steps. In step one, a detailed cycle analysis shows two physically important couplings in the combustor: first, the acoustic compression enhances the spray drop breakup and vaporization, and generates more gaseous fuel for reaction; second, the acoustic compression couples with the unsteady hydrodynamics found in the open-geometry simulation, enhances the fuel/air mixing, and triggers a large amount of heat addition. In step two, a modal analysis using DMD extracts the dynamic features of important modes in the combustor, and identifies the presence of Precessing Vortex Core (PVC) mode and its nonlinear interactions with acoustic modes. Moreover, the DMD analysis helps to establish the couplings between the hydrodynamics and acoustics in terms of frequencies. In step 3, Rayleigh index analysis provides a quantitative assessment of acoustics/combustion couplings and identifies local regions for instability driving/damping. Two modal decomposition techniques, Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD), are assessed in terms of their capabilities in extracting important information from the original simulation dataset and in validating the computational results using the experiment measurement. A POD analysis provides a series of modes with decreasing energy content and it offers an efficient and optimized way to represent a large dataset. The frequency-based DMD technique provides modes that correspond to all single frequencies. For the low-order modeling, fundamental aspects are examined to study necessary conditions, criteria and approaches to develop a reduced-order model (ROM) that is able to represent generic combustion/flame responses, which then can be used in an engineering level tool to provide efficient predictions of combustion instability for practical design applications. Explorations are focused on model reduction techniques by using the so-called POD/Galerkin method. The method uses the numerical solutions of the model equations as the database for building a set of POD eigen-bases. Specifically, the numerical solutions are calculated by perturbing quantities of interest such as the inlet conditions. The POD-derived eigen-bases are, in turn, used in conjunction with a Galerkin procedure to reduce the governing partial differential equation to an ordinary differential equation, which constitutes the ROM. Once the ROM is established, it can then be used as a lower-order test-bed to predict detailed results within certain parametric ranges at a fraction of the cost of solving the full governing equations. A detailed assessment is performed on the method in two parts. In part one, a one-dimensional scalar reaction-advection model equation is used for fundamental investigations, which include verification of the POD eigen-basis calculation and of the ROM development procedure. Moreover, certain criteria during ROM development are established: 1. a necessary number of POD modes that should be included to guarantee a stable ROM; 2. the need for the numerical discretization scheme to be consistent between the original CFD and the developed ROM. Furthermore, the predictive capabilities of the resulting ROM are evaluated to test its limits and to validate the values of applying broadband forcing in improving the ROM performance. In part two, the exploration is extended to a vector system of equations. Using the one-dimensional Euler equation is used as a model equation. A numerical stability issue is identified during the ROM development, the cause of which is further studied and attributed to the normalization methods implemented to generate coupled POD eigen-bases for vector variables. (Abstract shortened by UMI.).

Comparisons of a Three-Dimensional, Full Navier Stokes Computer Model with High Mach Number Combuster Test Data

NASA Technical Reports Server (NTRS)

Watkins, William B.

1990-01-01

Comparisons between scramjet combustor data and a three-dimensional full Navier-Stokes calculation have been made to verify and substantiate computational fluid dynamics (CFD) codes and application procedures. High Mach number scramjet combustor development will rely heavily on CFD applications to provide wind tunnel-equivalent data of quality sufficient to design, build and fly hypersonic aircraft. Therefore. detailed comparisons between CFD results and test data are imperative. An experimental case is presented, for which combustor wall static pressures were measured and flow-fieid interferograms were obtained. A computer model was done of the experiment, and counterpart parameters are compared with experiment. The experiment involved a subscale combustor designed and fabricated for the National Aero-Space Plane Program, and tested in the Calspan Corporation 96" hypersonic shock tunnel. The combustor inlet ramp was inclined at a 20 angle to the shock tunnel nozzle axis, and resulting combustor entrance flow conditions simulated freestream M=10. The combustor body and cowl walls were instrumented with static pressure transducers, and the combustor lateral walls contained windows through which flowfield holographic interferograms were obtained. The CFD calculation involved a three-dimensional time-averaged full Navier-Stokes code applied to the axial flow segment containing fuel injection and combustion. The full Navier-Stokes approach allowed for mixed supersonic and subsonic flow, downstream-upstream communication in subsonic flow regions, and effects of adverse pressure gradients. The code included hydrogen-air chemistry in the combustor segment which begins near fuel injection and continues through combustor exhaust. Combustor ramp and inlet segments on the combustor lateral centerline were modelled as two dimensional. Comparisons to be shown include calculated versus measured wall static pressures as functions of axial flow coordinate, and calculated path-averaged density contours versus an holographic Interferogram.

Quantifying the Presence and Activity of Aerobic, Vinyl Chloride-Degrading Microorganisms in Dilute Groundwater Plumes by Using Real-Time PCR

DTIC Science & Technology

2013-07-01

throughout the observation period. A 0.25-ml Pressure-Lok gas -tight syringe with a side-ported needle was used to take 0.1 ml headspace samples during...33. Biodegradation of methane, VC and a methane+VC mixture by methane enrichment cultures derived from Carver well RB63I. These results indicate that...VC and a methane+VC mixture by methane enrichment cultures derived from Carver well RB63I. These results are a repeat of the experiment depicted in

Comparison of Lyophilized Glutaraldehyde-Preserved Bovine Pericardium with Different Vascular Prostheses for Use as Vocal Cords Implants: Experimental Study

PubMed Central

Olmos-Zuñiga, J. Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel; Sotres-Vega, Avelina; Hernández-Jiménez, Claudia; Baltazares-Lipp, Matilde; Arredondo del Bosque, Fernando; Santillan-Doherty, Patricio

2015-01-01

This study compared the use of lyophilized glutaraldehyde-preserved bovine pericardium (LGPBP), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and Teflon felt (TF) as implants for vocal cords (VC) medialization and aimed to assess the endoscopic, macroscopic, and microscopic VC changes after medialization in a canine model. In 18 mongrel dogs, the right VC were medialized with LGPBP and the left were implanted as follows: Group I (n = 6): LGPBP and PTFE; Group II (n = 6): LGPBP and PET; Group III (n = 6): LGPBP and TF. Surgical handling of the implants was compared. Three months after surgery, macroscopic and microscopic changes of VC and implants were evaluated. LGPBP offered the best surgical handling (p = 0.005, Kruskal-Wallis). TF implants showed extrusion (p = 0.005, Kruskal-Wallis) and severe inflammation. All VC formed fibrous capsules around the implants; the ones developed by LGPBP implants were thinner (p = 0.001, ANOVA, Tukey). VC implanted with synthetic materials showed eosinophilic infiltration (p = 0.01, Kruskal-Wallis). We concluded that the LGPBP could be used as an implant for VC medialization because it is biocompatible, easy to handle and remove during surgical procedures, and nonabsorbable or extrudable and produces an inflammatory reaction similar to PTFE and PET. PMID:26075232

Listening to Schneiderian Voices: A Novel Phenomenological Analysis

PubMed Central

Rosen, Cherise; Chase, Kayla A.; Jones, Nev; Grossman, Linda S.; Gin, Hannah; Sharma, Rajiv P.

2016-01-01

Background/Aims This paper reports on analyses designed to elucidate phenomenological characteristics, content and experience specifically targeting participants with Schneiderian voices conversing/commenting (VC) while exploring difference in clinical presentation and quality of life compared to those with voices not conversing (VNC). Methods This mixed-method investigation of Schneiderian voices included standardized clinical metrics and exploratory phenomenological interviews designed to elicit in-depth information about characteristics, content, meaning and personification of AVHs. Results The subjective experience of VC show a striking pattern of VC that are experienced as internal at initial onset and during longer-term course of illness when compared to the VNC group. Participants in the VC group were more likely to attribute origins of their voices to an external source such as God, telepathic communication, or mediumistic sources. VC and VNC were described as characterological entities that were distinct from self (I/we versus you). We also found an association between VC and positive, cognitive, and depression symptom profile. However, we did not find a significant group difference in overall quality of life. Conclusions The clinical portrait of VC is complex, multisensory, and distinct, and suggests a need for further research into biopsychosocial interface between subjective experience, socioenvironmental constraints, individual psychology, and biological architecture of intersecting symptoms. PMID:27304081

Potential protection of vitamin C against liver-lesioned mice.

PubMed

Su, Min; Chen, Hongqiu; Wei, Chaohe; Chen, Ning; Wu, Wei

2014-10-01

Pathologically, liver injury can result from sustained trauma to hepatocytes, including acute damage. Thus, attenuation of hepatocellular lesion may help improve liver functions. The purpose of this study was to explore the potential advantages of vitamin C (VC) intake on acutely intralesional liver in carbon tetrachloride (CCl4)-exposed mice. Here our data showed that VC supplementation contributed to ameliorated vital signs of CCl4-lesioned mice, resulting in dose-dependent reduction of hepatomegaly. VC lowered the levels of liver functional enzymes including alanine aminotransferase (ALT) and glutamic-oxaloacetic transaminase (AST) in serum, while concentration of lactic acid concentration in blood plasma was decreased. VC-administered CCl4-lesioned mice manifested increased activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), while the malondialdehyde (MDA) content was reduced in liver tissue. Moreover, VC consumption attenuated hepatotoxic injuries of CCl4-lesioned mice, in which the number of TNF-α positive cells was dose-dependently reduced. Furthermore, intrahepatic expression of TRL-4 mRNA, a vital inflammation-regulator, was down-regulated in VC-administered mice. Overall, we conclude that VC has the potentiality of anti-hepatotoxicity that is capable of ameliorating liver functions, speculating that therapeutic mechanism relates to normalizing metabolism and blocking inflammatory stress in the liver. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of lyophilized glutaraldehyde-preserved bovine pericardium with different vascular prostheses for use as vocal cords implants: experimental study.

PubMed

Olmos-Zuñiga, J Raúl; Jasso-Victoria, Rogelio; Gaxiola-Gaxiola, Miguel; Sotres-Vega, Avelina; Hernández-Jiménez, Claudia; Baltazares-Lipp, Matilde; Arredondo del Bosque, Fernando; Santillan-Doherty, Patricio

2015-01-01

This study compared the use of lyophilized glutaraldehyde-preserved bovine pericardium (LGPBP), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), and Teflon felt (TF) as implants for vocal cords (VC) medialization and aimed to assess the endoscopic, macroscopic, and microscopic VC changes after medialization in a canine model. In 18 mongrel dogs, the right VC were medialized with LGPBP and the left were implanted as follows: Group I (n = 6): LGPBP and PTFE; Group II (n = 6): LGPBP and PET; Group III (n = 6): LGPBP and TF. Surgical handling of the implants was compared. Three months after surgery, macroscopic and microscopic changes of VC and implants were evaluated. LGPBP offered the best surgical handling (p = 0.005, Kruskal-Wallis). TF implants showed extrusion (p = 0.005, Kruskal-Wallis) and severe inflammation. All VC formed fibrous capsules around the implants; the ones developed by LGPBP implants were thinner (p = 0.001, ANOVA, Tukey). VC implanted with synthetic materials showed eosinophilic infiltration (p = 0.01, Kruskal-Wallis). We concluded that the LGPBP could be used as an implant for VC medialization because it is biocompatible, easy to handle and remove during surgical procedures, and nonabsorbable or extrudable and produces an inflammatory reaction similar to PTFE and PET.

Improving the representation of Arctic photosynthesis in Earth system models

NASA Astrophysics Data System (ADS)

Rogers, A.; Serbin, S.; Ely, K.; Sloan, V. L.; Wyatt, R. A.; Kubien, D. S.; Ali, A. A.; Xu, C.; Wullschleger, S. D.

2015-12-01

The primary goal of Earth System Models (ESMs) is to improve understanding and projection of future global change. In order to do this they must accurately represent the carbon fluxes associated with the terrestrial carbon cycle. Although Arctic carbon fluxes are small - relative to global carbon fluxes - uncertainty is large. As part of a multidisciplinary project to improve the representation of the Arctic in ESMs (Next Generation Ecosystem Experiments - Arctic) we are examining the photosynthetic parameterization of the Arctic plant functional type (PFT) in ESMs. Photosynthetic CO2 uptake is well described by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis. Most ESMs use a derivation of the FvCB model to calculate gross primary productivity. Two key parameters required by the FvCB model are an estimate of the maximum rate of carboxylation by the enzyme Rubisco (Vc,max) and the maximum rate of electron transport (Jmax). In ESMs the parameter Vc,max is usually fixed for a given PFT. Only four ESMs currently have an explicit Arctic PFT and the data used to derive Vc,max for the Arctic PFT in these models relies on small data sets and unjustified assumptions. We examined the derivation of Vc,max and Jmax in current Arctic PFTs and estimated Vc,max and Jmax for 7 species representing both dominant vegetation and key Arctic PFTs growing on the Barrow Environmental Observatory, Barrow, AK. The values of Vc,max currently used to represent Arctic PFTs in ESMs are 70% lower than the values we measured in these species. Examination of the derivation of Vc,max in ESMs identified that the cause of the relatively low Vc,max value was the result of underestimating both the leaf N content and the investment of that N in Rubisco. Contemporary temperature response functions for Vc,max also appear to underestimate Vc,max at low temperature. ESMs typically use a single multiplier (JVratio) to convert Vc,max to Jmax for all PFTs. We found that the JVratio of Arctic plants is higher than current estimates suggesting that the Arctic PFT will be more responsive to rising carbon dioxide than currently projected. Our data suggest that the Arctic tundra has a much greater capacity for CO2 uptake, particularly at low temperature, and will be more CO2 responsive than is currently represented in ESMs.

A randomized comparison of a novel nitinol-frame low-dose-copper intrauterine contraceptive and a copper T380S intrauterine contraceptive.

PubMed

Reeves, Matthew F; Katz, Bob H; Canela, Juan M; Hathaway, Mark J; Tal, Michael G

2017-06-01

We sought to compare VeraCept (VC175), a novel nitinol intrauterine contraceptive (IUC) with 175 square-mm of copper surface area, to a copper T380S IUC. We enrolled parous women into a randomized subject-blinded comparison of VC175 and a copper T380S in a 2:1 fashion at a single clinic. The primary outcomes were total adverse events and continuation at 12 months. We also examined pain on insertion, ease of placement, expulsion, tolerability and pregnancy. Subjective ratings were on a 5-point Likert scale (0, no pain to 5, worst pain). We followed subjects through 24-month follow-up. We enrolled 300 women with 199 randomized to VC175 and 101 to the T380S. Insertion was successful in 198 subjects for VC175 and 100 for the T380S. Mean age was 25 years (range 18, 41), and median parity was 2 (range 1, 8), with 39% having only had Cesarean deliveries. No subjects developed clinical infection or reported serious adverse events. In the VC175 and T380S groups, mean pain at insertion was 1.4 and 2.4, respectively (p<.01). At the 12-month primary endpoint for VC175 and T380S, respectively, continuation was 84% and 68% (p<.002) with expulsions in 5.0% and 12.0% (p<.05) and removal for pain/bleeding in 3.5% and 17.0% (p<.01). At the 24-month visit for VC175 and T380S, respectively, continuation was 77% and 62% (p<.02 by log-rank). One ectopic pregnancy was identified at the 12-month follow-up in a VC175 user. No other pregnancies were diagnosed. With 297.3 and 132.4 woman-years, pregnancy rates were 0.3 and 0.0 per 100 woman-years for VC175 and T380S, respectively. VC175 resulted in less pain at insertion, fewer expulsions and higher total continuation than the T380S, with similar contraceptive efficacy. VC175 is a promising new intrauterine copper contraceptive on a nitinol frame that warrants further clinical trials. Copyright © 2017 Elsevier Inc. All rights reserved.

Are there sex differences in the capillary blood volume and diffusing capacity response to exercise?

PubMed

Bouwsema, Melissa M; Tedjasaputra, Vincent; Stickland, Michael K

2017-03-01

Previous work suggests that women may exhibit a greater respiratory limitation in exercise compared with height-matched men. Diffusion capacity (Dl CO ) increases with incremental exercise, and the smaller lungs of women may limit membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) in response to the increased oxygen demand. We hypothesized that women would have lower Dl CO , Dl CO relative to cardiac output (Dl CO /Q̇), Dm, Vc, and pulmonary transit time, secondary to lower Vc at peak exercise. Sixteen women (112 ± 12% predicted relative V̇o 2peak ) and sixteen men (118 ± 22% predicted relative V̇o 2peak ) were matched for height and weight. Hemoglobin-corrected diffusing capacity (Dl CO ), Vc, and Dm were determined via the multiple-[Formula: see text] Dl CO technique at rest and during incremental exercise up to 90% of V̇o 2peak Both groups increased Dl CO , Vc, and Dm with exercise intensity, but women had 20% lower Dl CO ( P < 0.001), 18% lower Vc ( P = 0.002), and 22% lower Dm ( P < 0.001) compared with men across all workloads, and neither group exhibited a plateau in Vc. When expressed relative to alveolar volume (Va), the between-sex difference was eliminated. The drop in Dl CO /Q̇ was proportionally less in women than men, and mean pulmonary transit time did not drop below 0.3 s in either group. Women demonstrate consistently lower Dl CO , Vc, and Dm compared with height-matched men during exercise; however, these differences disappear with correction for lung size. These results suggest that after differences in lung volume are accounted for there is no intrinsic sex difference in the Dl CO , Vc, or Dm response to exercise. NEW & NOTEWORTHY Women demonstrate lower diffusing capacity-to-cardiac output ratio (Dl CO /Q̇), pulmonary capillary blood volume (Vc), and membrane diffusing capacity (Dm) compared with height-matched men during exercise. However, these differences disappear after correction for lung size. The drop in Dl CO /Q̇ was proportionally less in women, and pulmonary transit time did not drop below 0.3 s in either group. After differences in lung volume are accounted for, there is no intrinsic sex difference in Dl CO , Vc, or Dm response to exercise. Copyright © 2017 the American Physiological Society.

System and method for controlling a combustor assembly

DOEpatents

York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Stevenson, Christian Xavier

2013-03-05

A system and method for controlling a combustor assembly are disclosed. The system includes a combustor assembly. The combustor assembly includes a combustor and a fuel nozzle assembly. The combustor includes a casing. The fuel nozzle assembly is positioned at least partially within the casing and includes a fuel nozzle. The fuel nozzle assembly further defines a head end. The system further includes a viewing device configured for capturing an image of at least a portion of the head end, and a processor communicatively coupled to the viewing device, the processor configured to compare the image to a standard image for the head end.

Simulated Altitude Performance of Combustor of Westinghouse 19XB-1 Jet-Propulsion Engine

NASA Technical Reports Server (NTRS)

Childs, J. Howard; McCafferty, Richard J.

1948-01-01

A 19XB-1 combustor was operated under conditions simulating zero-ram operation of the 19XB-1 turbojet engine at various altitudes and engine speeds. The combustion efficiencies and the altitude operational limits were determined; data were also obtained on the character of the combustion, the pressure drop through the combustor, and the combustor-outlet temperature and velocity profiles. At altitudes about 10,000 feet below the operational limits, the flames were yellow and steady and the temperature rise through the combustor increased with fuel-air ratio throughout the range of fuel-air ratios investigated. At altitudes near the operational limits, the flames were blue and flickering and the combustor was sluggish in its response to changes in fuel flow. At these high altitudes, the temperature rise through the combustor increased very slowly as the fuel flow was increased and attained a maximum at a fuel-air ratio much leaner than the over-all stoichiometric; further increases in fuel flow resulted in decreased values of combustor temperature rise and increased resonance until a rich-limit blow-out occurred. The approximate operational ceiling of the engine as determined by the combustor, using AN-F-28, Amendment-3, fuel, was 30,400 feet at a simulated engine speed of 7500 rpm and increased as the engine speed was increased. At an engine speed of 16,000 rpm, the operational ceiling was approximately 48,000 feet. Throughout the range of simulated altitudes and engine speeds investigated, the combustion efficiency increased with increasing engine speed and with decreasing altitude. The combustion efficiency varied from over 99 percent at operating conditions simulating high engine speed and low altitude operation to less than 50 percent at conditions simulating operation at altitudes near the operational limits. The isothermal total pressure drop through the combustor was 1.82 times as great as the inlet dynamic pressure. As expected from theoretical considerations, a straight-line correlation was obtained when the ratio of the combustor total pressure drop to the combustor-inlet dynamic pressure was plotted as a function of the ratio of the combustor-inlet air density to the combustor-outlet gas density. The combustor-outlet temperature profiles were, in general, more uniform for runs in which the temperature rise was low and the combustion efficiency was high. Inspection of the combustor basket after 36 hours of operation showed very little deterioration and no appreciable carbon deposits.

Vital capacity and COPD: the Swedish CArdioPulmonary bioImage Study (SCAPIS).

PubMed

Torén, Kjell; Olin, Anna-Carin; Lindberg, Anne; Vikgren, Jenny; Schiöler, Linus; Brandberg, John; Johnsson, Åse; Engström, Gunnar; Persson, H Lennart; Sköld, Magnus; Hedner, Jan; Lindberg, Eva; Malinovschi, Andrei; Piitulainen, Eeva; Wollmer, Per; Rosengren, Annika; Janson, Christer; Blomberg, Anders; Bergström, Göran

2016-01-01

Spirometric diagnosis of chronic obstructive pulmonary disease (COPD) is based on the ratio of forced expiratory volume in 1 second (FEV1)/vital capacity (VC), either as a fixed value <0.7 or below the lower limit of normal (LLN). Forced vital capacity (FVC) is a proxy for VC. The first aim was to compare the use of FVC and VC, assessed as the highest value of FVC or slow vital capacity (SVC), when assessing the FEV1/VC ratio in a general population setting. The second aim was to evaluate the characteristics of subjects with COPD who obtained a higher SVC than FVC. Subjects (n=1,050) aged 50-64 years were investigated with FEV1, FVC, and SVC after bronchodilation. Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPDFVC was defined as FEV1/FVC <0.7, GOLDCOPDVC as FEV1/VC <0.7 using the maximum value of FVC or SVC, LLNCOPDFVC as FEV1/FVC below the LLN, and LLNCOPDVC as FEV1/VC below the LLN using the maximum value of FVC or SVC. Prevalence of GOLDCOPDFVC was 10.0% (95% confidence interval [CI] 8.2-12.0) and the prevalence of LLNCOPDFVC was 9.5% (95% CI 7.8-11.4). When estimates were based on VC, the prevalence became higher; 16.4% (95% CI 14.3-18.9) and 15.6% (95% CI 13.5-17.9) for GOLDCOPDVC and LLNCOPDVC, respectively. The group of additional subjects classified as having COPD based on VC, had lower FEV1, more wheeze and higher residual volume compared to subjects without any COPD. The prevalence of COPD was significantly higher when the ratio FEV1/VC was calculated using the highest value of SVC or FVC compared with using FVC only. Subjects classified as having COPD when using the VC concept were more obstructive and with indications of air trapping. Hence, the use of only FVC when assessing airflow limitation may result in a considerable under diagnosis of subjects with mild COPD.

Experimental Clean Combustor Program (ECCP), phase 3. [commercial aircraft turbofan engine tests with double annular combustor

NASA Technical Reports Server (NTRS)

Gleason, C. C.; Bahr, D. W.

1979-01-01

A double annular advanced technology combustor with low pollutant emission levels was evaluated in a series of CF6-50 engine tests. Engine lightoff was readily obtained and no difficulties were encountered with combustor staging. Engine acceleration and deceleration were smooth, responsive and essentially the same as those obtainable with the CF6-50 combustor. The emission reductions obtained in carbon monoxide, hydrocarbons, and nitrogen oxide levels were 55, 95, and 30 percent, respectively, at an idle power setting of 3.3 percent of takeoff power on an EPA parameter basis. Acceptable smoke levels were also obtained. The exit temperature distribution of the combustor was found to be its major performance deficiency. In all other important combustion system performance aspects, the combustor was found to be generally satisfactory.

Integrated CFD modeling of gas turbine combustors

NASA Technical Reports Server (NTRS)

Fuller, E. J.; Smith, C. E.

1993-01-01

3D, curvilinear, multi-domain CFD analysis is becoming a valuable tool in gas turbine combustor design. Used as a supplement to experimental testing. CFD analysis can provide improved understanding of combustor aerodynamics and used to qualitatively assess new combustor designs. This paper discusses recent advancements in CFD combustor methodology, including the timely integration of the design (i.e. CAD) and analysis (i.e. CFD) processes. Allied Signal's F124 combustor was analyzed at maximum power conditions. The assumption of turbulence levels at the nozzle/swirler inlet was shown to be very important in the prediction of combustor exit temperatures. Predicted exit temperatures were compared to experimental rake data, and good overall agreement was seen. Exit radial temperature profiles were well predicted, while the predicted pattern factor was 25 percent higher than the harmonic-averaged experimental pattern factor.

Multifuel evaluation of rich/quench/lean combustor

NASA Technical Reports Server (NTRS)

Novick, A. S.; Troth, D. L.; Notardonato, J.

1982-01-01

Test results on the RQL low NO(x) industrial gas turbine engine are reported. The air-staged combustor comprises an initial rich burning zone, followed by a quench zone, and a lean reaction and dilution zone. The combustor was tested as part of the DoE/NASA program to define the technology for developing a durable, low-emission gas turbine combustor capable of operation with minimally processed petroleum residual, synthetic, or low/mid-heating value gaseous fuels. The properties of three liquid and two gaseous fuels burned in the combustor trials are detailed. The combustor featured air staging, variable geometry, and generative/convective cooling. The lean/rich mixtures could be varied in zones simultaneously or separately while maintaining a specified pressure drop. Low NO(x) and smoke emissions were produced with each fuel burned, while high combustor efficiencies were obtained.

Dietary L-lysine prevents arterial calcification in adenine-induced uremic rats.

PubMed

Shimomura, Akihiro; Matsui, Isao; Hamano, Takayuki; Ishimoto, Takuya; Katou, Yumiko; Takehana, Kenji; Inoue, Kazunori; Kusunoki, Yasuo; Mori, Daisuke; Nakano, Chikako; Obi, Yoshitsugu; Fujii, Naohiko; Takabatake, Yoshitsugu; Nakano, Takayoshi; Tsubakihara, Yoshiharu; Isaka, Yoshitaka; Rakugi, Hiromi

2014-09-01

Vascular calcification (VC) is a life-threatening complication of CKD. Severe protein restriction causes a shortage of essential amino acids, and exacerbates VC in rats. Therefore, we investigated the effects of dietary l-lysine, the first-limiting amino acid of cereal grains, on VC. Male Sprague-Dawley rats at age 13 weeks were divided randomly into four groups: low-protein (LP) diet (group LP), LP diet+adenine (group Ade), LP diet+adenine+glycine (group Gly) as a control amino acid group, and LP diet+adenine+l-lysine·HCl (group Lys). At age 18 weeks, group LP had no VC, whereas groups Ade and Gly had comparable levels of severe VC. l-Lysine supplementation almost completely ameliorated VC. Physical parameters and serum creatinine, urea nitrogen, and phosphate did not differ among groups Ade, Gly, and Lys. Notably, serum calcium in group Lys was slightly but significantly higher than in groups Ade and Gly. Dietary l-lysine strongly suppressed plasma intact parathyroid hormone in adenine rats and supported a proper bone-vascular axis. The conserved orientation of the femoral apatite in group Lys also evidenced the bone-protective effects of l-lysine. Dietary l-lysine elevated plasma alanine, proline, arginine, and homoarginine but not lysine. Analyses in vitro demonstrated that alanine and proline inhibit apoptosis of cultured vascular smooth muscle cells, and that arginine and homoarginine attenuate mineral precipitations in a supersaturated calcium/phosphate solution. In conclusion, dietary supplementation of l-lysine ameliorated VC by modifying key pathways that exacerbate VC. Copyright © 2014 by the American Society of Nephrology.

Calcium Overload Accelerates Phosphate-Induced Vascular Calcification Via Pit-1, but not the Calcium-Sensing Receptor.

PubMed

Masumoto, Asuka; Sonou, Tomohiro; Ohya, Masaki; Yashiro, Mitsuru; Nakashima, Yuri; Okuda, Kouji; Iwashita, Yuko; Mima, Toru; Negi, Shigeo; Shigematsu, Takashi

2017-07-01

Vascular calcification (VC) is a risk factor of cardiovascular and all-cause mortality in patients with chronic kidney disease (CKD). CKD-mineral and bone metabolism disorder is an important problem in patients with renal failure. Abnormal levels of serum phosphate and calcium affect CKD-mineral and bone metabolism disorder and contribute to bone disease, VC, and cardiovascular disease. Hypercalcemia is a contributing factor in progression of VC in patients with CKD. However, the mechanisms of how calcium promotes intracellular calcification are still unclear. This study aimed to examine the mechanisms underlying calcium-induced calcification in a rat aortic tissue culture model. Aortic segments from 7-week-old male Sprague-Dawley rats were cultured in serum-supplemented medium for 10 days. We added high calcium (HiCa; calcium 3.0 mM) to high phosphate (HPi; phosphate 3.8 mM) medium to accelerate phosphate and calcium-induced VC. We used phosphonoformic acid and the calcimimetic R-568 to determine whether the mechanism of calcification involves Pit-1 or the calcium-sensing receptor. Medial VC was significantly augmented by HPi+HiCa medium compared with HPi alone (300%, p＜0.05), and was associated with upregulation of Pit-1 protein. Pit-1 protein concentrations in HPi+HiCa medium were greater than those in HPi medium. Phosphonoformic acid completely negated the augmentation of medial VC induced by HPi+HiCa. R-568 had no additive direct effect on medial VC. These results indicated that exposure to HPi+HiCa accelerates medial VC, and this is mediated through Pit-1, not the calcium-sensing receptor.

Exploratory analysis of a phase III trial of pirfenidone identifies a subpopulation of patients with idiopathic pulmonary fibrosis as benefiting from treatment

PubMed Central

2011-01-01

Background A phase III trial in Japan showed that pirfenidone is effective for idiopathic pulmonary fibrosis (IPF). To find out which patients specifically benefit from pirfenidone, we analyzed in an exploratory manner the data from the phase III trial. Methods The patients in the phase III trial were stratified by baseline percentage predicted vital capacity (%VC), arterial oxygen partial pressure (PaO2), and the lowest oxygen saturation by pulse oximetry (SpO2) during the 6-minute steady-state exercise test (6MET). In the subpopulations, changes in VC and subjective symptoms (cough and dyspnea on the Fletcher, Hugh-Jones [F, H-J] Classification scale) were evaluated in patients treated with high-dose (1800 mg/day) pirfenidone, low-dose (1200 mg/day) pirfenidone, and placebo at week 52. Results Significant efficacy of pirfenidone in reducing the decline in VC could be seen in a subpopulation having %VC ≥ 70% and SpO2 < 90% at baseline. This favorable effect was accompanied by categorical change in VC and progression-free survival time. In the subpopulation, pirfenidone significantly suppressed cough and dyspnea. Conclusions IPF patients having %VC ≥ 70% and SpO2 < 90% at baseline will most likely benefit from pirfenidone when evaluated using changes in VC (and %VC), and cough and dyspnea symptoms. This subpopulation could expect to benefit most from pirfenidone treatment. Trial Registration This clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13th, 2005 (Registration Number: JAPICCTI-050121). PMID:22035508

Additive effect on reductive decomposition and binding of carbonate-based solvent toward solid electrolyte interphase formation in lithium-ion battery.

PubMed

Ushirogata, Keisuke; Sodeyama, Keitaro; Okuno, Yukihiro; Tateyama, Yoshitaka

2013-08-14

The solid-electrolyte interphase (SEI) formed through the reductive decomposition of solvent molecules plays a crucial role in the stability and capability of a lithium-ion battery (LIB). Here we investigated the effects of adding vinylene carbonate (VC) to ethylene carbonate (EC) solvent, a typical electrolyte in LIBs, on the reductive decomposition. We focused on both thermodynamics and kinetics of the possible processes and used density functional theory-based molecular dynamics with explicit solvent and Blue-moon ensemble technique for the free energy change. We considered Li(+) in only EC solvent (EC system) and in EC solvent with a VC additive (EC/VC system) to elucidate the additive effects. In addition to clarifying the equilibrium properties, we evaluated the free energy changes along several EC or VC decomposition pathways under one-electron (1e) reduction condition. Two-electron (2e) reduction and attacks of anion radicals to intact molecules were also examined. The present results completely reproduce the gaseous products observed in the experiments. We also found a new mechanism involving the VC additive: the VC additive preferentially reacts with the EC anion radical to suppress the 2e reduction of EC and enhance the initial SEI formation, contrary to the conventional scenario in which VC additive is sacrificially reduced and its radical oligomerization becomes the source of SEI. Because our mechanism needs only 1e reduction, the irreversible capacity at the SEI formation will decrease, which is also consistent with the experimental observations. These results reveal the primary role of VC additive in the EC solvent.

Combustor and combustor screech mitigation methods

DOEpatents

Kim, Kwanwoo; Johnson, Thomas Edward; Uhm, Jong Ho; Kraemer, Gilbert Otto

2014-05-27

The present application provides for a combustor for use with a gas turbine engine. The combustor may include a cap member and a number of fuel nozzles extending through the cap member. One or more of the fuel nozzles may be provided in a non-flush position with respect to the cap member.

The vitamin C:vitamin K3 system - enhancers and inhibitors of the anticancer effect.

PubMed

Lamson, Davis W; Gu, Yu-Huan; Plaza, Steven M; Brignall, Matthew S; Brinton, Cathy A; Sadlon, Angela E

2010-12-01

The oxidizing anticancer system of vitamin C and vitamin K₃ (VC:VK₃, producing hydrogen peroxide via superoxide) was combined individually with melatonin, curcumin, quercetin, or cholecalciferol (VD₃) to determine interactions. Substrates were LNCaP and PC-3 prostate cancer cell lines. Three of the tested antioxidants displayed differences in cell line cytotoxicity. Melatonin combined with VC:VK₃ quenched the oxidizing effect, while VC:VK₃ applied 24 hours after melatonin showed no quenching. With increasing curcumin concentrations, an apparent combined effect of VC:VK₃ and curcumin occurred in LNCaP cells, but not PC-3 cells. Quercetin alone was cytotoxic on both cell lines, but demonstrated an additional 50-percent cytotoxicity on PC-3 cells when combined with VC:VK₃. VD₃ was effective against both cell lines, with more effect on PC-3. This effect was negated on LNCaP cells with the addition of VC:VK₃. In conclusion, a natural antioxidant can enhance or decrease the cytotoxicity of an oxidizing anticancer system in vitro, but generalizations about antioxidants cannot be made.

Chromosome aberrations detected by conventional karyotyping using novel mitogens in chronic lymphocytic leukemia with "normal" FISH: correlations with clinicobiologic parameters.

PubMed

Rigolin, Gian Matteo; Cibien, Francesca; Martinelli, Sara; Formigaro, Luca; Rizzotto, Lara; Tammiso, Elisa; Saccenti, Elena; Bardi, Antonella; Cavazzini, Francesco; Ciccone, Maria; Nichele, Ilaria; Pizzolo, Giovanni; Zaja, Francesco; Fanin, Renato; Galieni, Piero; Dalsass, Alessia; Mestichelli, Francesca; Testa, Nicoletta; Negrini, Massimo; Cuneo, Antonio

2012-03-08

It is unclear whether karyotype aberrations that occur in regions uncovered by the standard fluorescence in situ hybridization (FISH) panel have prognostic relevance in chronic lymphocytic leukemia (CLL). We evaluated the significance of karyotypic aberrations in a learning cohort (LC; n = 64) and a validation cohort (VC; n = 84) of patients with chronic lymphocytic leukemia with "normal" FISH. An abnormal karyotype was found in 21.5% and 35.7% of cases in the LC and VC, respectively, and was associated with a lower immunophenotypic score (P = .030 in the LC, P = .035 in the VC), advanced stage (P = .040 in the VC), and need for treatment (P = .002 in the LC, P = < .0001 in the VC). The abnormal karyotype correlated with shorter time to first treatment and shorter survival in both the LC and the VC, representing the strongest prognostic parameter. In patients with chronic lymphocytic leukemia with normal FISH, karyotypic aberrations by conventional cytogenetics with novel mitogens identify a subset of cases with adverse prognostic features.

Myo-Inositol content determined by myo-inositol biosynthesis and oxidation in blueberry fruit.

PubMed

Song, Fangyuan; Su, Hongyan; Yang, Nan; Zhu, Luying; Cheng, Jieshan; Wang, Lei; Cheng, Xianhao

2016-11-01

Myo-inositol metabolism in plant edible organs has become the focus of many recent studies because of its benefits to human health and unique functions in plant development. In this study, myo-inositol contents were analyzed during the development of two blueberry cultivars, cv 'Berkeley' and cv 'Bluecrop'. Furthermore, two VcMIPS 1/2 (Vaccinium corymbosum MIPS) genes, one VcIMP (Vaccinium corymbosum IMP) gene and one VcMIOX (Vaccinium corymbosum MIOX) gene were isolated for the first time from blueberry. The expression patterns of VcMIPS2, VcIMP and VcMIOX genes showed a relationship with the change profiles of myo-inositol content during fruit ripening. The results were further confirmed by the analyses of the enzyme activity. Results indicated that both myo-inositol biosynthesis and oxidation played important roles in determining of myo-inositol levels during the development of blueberry. To our knowledge, this report is the first to discuss myo-inositol levels in fruits in terms of biosynthesis and catabolism. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of myofibroblasts expression in oral squamous cell carcinoma, verrucous carcinoma, high risk epithelial dysplasia, low risk epithelial dysplasia and normal oral mucosa.

PubMed

Chaudhary, Minal; Gadbail, Amol Ramchandra; Vidhale, Gaurav; Mankar Gadbail, Mugdha P; Gondivkar, Shailesh M; Gawande, Madhuri; Patil, Swati

2012-09-01

The aim was to evaluate and compare the presence of myofibroblasts in oral squamous cell carcinoma (OSCC), verrucous carcinoma (VC), high-risk epithelial dysplasia (HRED), low-risk epithelial dysplasia (LRED), and normal oral mucosa (NOM). The study consisted of 37 OSCC, 15 VC, 15 HRED, 15 LRED and 15 NOM. α-smooth muscle actin (α-SMA) antibody was used to identify myofibroblasts. The α-SMA expression was not observed in NOM and LRED. The α-SMA was expressed in 97.29% of OSCC, 86.66% of VC, 46.66 % of HRED. The α-SMA expression was significantly higher in OSCC than VC (p = 0.023) and HRED (p < 0.000). The α-SMA expression was significantly higher in VC than HRED (p = 0.043). Myofibroblastic expression, as highlighted by α-SMA, is undetectable in NOM and LRED but increases as the disease progresses from potentially malignant disorders, as HRED to VC to invasive OSCC. Thus, proliferation of myofibroblasts may be used as a stromal marker of oral premalignancy and malignancy.

Controlled pilot oxidizer for a gas turbine combustor

DOEpatents

Laster, Walter R.; Bandaru, Ramarao V.

2010-07-13

A combustor (22) for a gas turbine (10) includes a main burner oxidizer flow path (34) delivering a first portion (32) of an oxidizer flow (e.g., 16) to a main burner (28) of the combustor and a pilot oxidizer flow path (38) delivering a second portion (36) of the oxidizer flow to a pilot (30) of the combustor. The combustor also includes a flow controller (42) disposed in the pilot oxidizer flow path for controlling an amount of the second portion delivered to the pilot.

Cross-protection elicited by primary and booster vaccinations against Japanese encephalitis: a two-year follow-up study.

PubMed

Erra, Elina O; Askling, Helena Hervius; Yoksan, Sutee; Rombo, Lars; Riutta, Jukka; Vene, Sirkka; Lindquist, Lars; Vapalahti, Olli; Kantele, Anu

2013-12-17

The inactivated Vero cell-derived vaccine (JE-VC, IXIARO) has replaced the traditional mouse brain-derived preparations (JE-MB) in travelers' vaccinations against Japanese encephalitis. We showed recently that a single JE-VC dose efficiently boosts immunity in JE-MB-primed vaccinees, and that JE-VC elicits cross-protective immunity against non-vaccine genotypes, including the emerging genotype I. While these studies only provided short-term data, the present investigation evaluates the longevity of seroprotection in the same volunteers. The study comprised 48 travelers who had received (1) JE-VC primary series, (2) JE-MB primary series followed by a single JE-VC booster dose, or (3) JE-MB primary series and a single JE-MB booster dose. Serum samples were collected two years after the last vaccine dose, and evaluated with the plaque-reduction neutralization test against seven Japanese encephalitis virus strains representing genotypes I-IV. PRNT50 titers ≥ 10 were considered protective. Two years after the primary series with JE-VC, 87-93% of the vaccinees proved to be cross-protected against test strains representing genotypes II-IV and 73% against those of genotype I. After a single homologous or heterologous booster dose to JE-MB-primed subjects, the two-year seroprotection rates against genotype I-IV strains were 89-100%. After JE-VC primary series, seroprotection appeared to wane first against genotype I. The first booster should not be delayed beyond two years. In JE-MB-primed subjects, a single JE-VC booster provided cross-protective immunity against genotype I-IV strains in almost all vaccinees, suggesting an interval of two years or even longer for the second booster. These data further support the use of a single JE-VC dose for boosting JE-MB immunity. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

A Novel Anti-CD22 Anthracycline-Based Antibody-Drug Conjugate (ADC) That Overcomes Resistance to Auristatin-Based ADCs.

PubMed

Yu, Shang-Fan; Zheng, Bing; Go, MaryAnn; Lau, Jeff; Spencer, Susan; Raab, Helga; Soriano, Robert; Jhunjhunwala, Suchit; Cohen, Robert; Caruso, Michele; Polakis, Paul; Flygare, John; Polson, Andrew G

2015-07-15

We are interested in identifying mechanisms of resistance to the current generation of antibody-drug conjugates (ADC) and developing ADCs that can overcome this resistance. Pinatuzumab vedotin (anti-CD22-vc-MMAE) and polatuzumab vedotin (anti-CD79b-vc-MMAE) are ADCs that contain the microtubule inhibitor monomethyl auristatin E (MMAE) attached to the antibody by the protease-cleavable linker maleimidocaproyl-valine-citrulline-p-aminobenzoyloxycarbonyl (MC-vc-PAB). Early clinical trial data suggest that these ADCs have promising efficacy for the treatment of non-Hodgkin lymphoma (NHL); however, some patients do not respond or become resistant to the ADCs. Anthracyclines are very effective in NHL, but ADCs containing the anthracycline doxorubicin were not clinically efficacious probably due to the low drug potency and inadequate linker technology. The anthracycline analogue PNU-159682 is thousands of times more cytotoxic than doxorubicin, so we used it to develop a new class of ADCs. We used the same MC-vc-PAB linker and antibody in pinatuzumab vedotin but replaced the MMAE with a derivative of PNU-159682 to make anti-CD22-NMS249 and tested it for in vivo efficacy in xenograft tumors resistant to MMAE-based ADCs. We derived cell lines from in vivo xenograft tumors that were made resistant to anti-CD22-vc-MMAE and anti-CD79b-vc-MMAE. We identified P-gp (ABCB1/MDR1) as the major driver of resistance to the vc-MMAE-based conjugates. Anti-CD22-NMS249 was at least as effective as anti-CD22-vc-MMAE in xenograft models of the parental cell lines and maintained its efficacy in the resistant cell lines. These studies provide proof of concept for an anthracycline-based ADC that could be used to treat B-cell malignancies that are resistant to vc-MMAE conjugates. ©2015 American Association for Cancer Research.

Identification and localization of the sperm CRISP family protein CiUrabin involved in gamete interaction in the ascidian Ciona intestinalis.

PubMed

Yamaguchi, Akira; Saito, Takako; Yamada, Lixy; Taniguchi, Hisaaki; Harada, Yoshito; Sawada, Hitoshi

2011-07-01

Ascidians are hermaphrodites, and most release sperm and eggs nearly simultaneously. Many species, including Halocynthia roretzi and Ciona intestinalis, are self-sterile. We previously reported that the interaction between a 12 EGF-like repeat-containing vitelline-coat (VC) protein, HrVC70, and a sperm GPI-anchored CRISP, HrUrabin, in lipid rafts plays a key role in self-/nonself-recognizable gamete interaction in H. roretzi. On the other hand, we recently identified two pairs of polymorphic genes responsible for self-incompatibility in C. intestinalis by positional cloning: The sperm polycystin 1-like receptors s-Themis-A/B and its fibrinogen-like ligand v-Themis-A/B on the VC. However, it is not known if the orthologs of HrVC70 and HrUrabin also participate in gamete interaction in C. intestinalis since they are from different orders. Here, we tested for a C. intestinalis ortholog (CiUrabin) of HrUrabin by searching the genome database and proteomes of sperm lipid rafts. The identified CiUrabin belongs to the CRISP family, with a PR domain and a GPI-anchor-attachment site. CiUrabin appears to be specifically expressed in the testis and localized at the surface of the sperm head, as revealed by Northern blotting and immunocytochemistry, respectively. The specific interaction between CiVC57, a C. intestinalis ortholog of HrVC70, and CiUrabin was confirmed by Far Western analysis, similarly to the interaction between HrVC70 and HrUrabin. The molecular interaction between CiVC57 and CiUrabin may be involved in the primary binding of sperm to the VC prior to the allorecognition process, mediated by v-Themis-A/B and s-Themis-A/B, during fertilization of C. intestinalis. Copyright © 2011 Wiley-Liss, Inc.

Financial and Temporal Advantages of Virtual Consultation in Veterans Requiring Specialty Care.

PubMed

Abbott, Daniel E; Macke, Ryan A; Kurtz, Jodi; Safdar, Nasia; Greenberg, Caprice C; Weber, Sharon M; Voils, Corrine I; Fisher, Deborah A; Maloney, James D

2018-01-01

Access to specialty health care in the Veterans Affairs (VA) system continues to be problematic. Given the potential temporal and fiscal benefits of telehealth, the Madison VA developed a virtual consultation (VC) mechanism to expedite diagnostic and therapeutic interventions for Veterans with incidentally discovered pulmonary nodules. Materials and. VC, a remote encounter between referring provider and thoracic surgeon for incidentally discovered pulmonary nodules, was implemented at the Madison VA between 2009 and 2011. Time from request to completion of consultation, hospital cost, and travel costs were determined for 157 veterans. These endpoints were then compared with in-person consultations over a concurrent 6-mo period. For the entire study cohort, the mean time to completion of VC was 3.2 d (SD ± 4.4 d). For the 6-mo period of first VC availability, the mean time to VC completion versus in-person consultation was 2.8 d (SD ± 2.8 d) and 20.5 d (SD ± 15.6 d), respectively (p < 0.05). Following initial VC, 84 (53%) veterans were scheduled for virtual follow-up alone; no veteran required an additional office visit before further diagnostic or therapeutic intervention. VA hospital cost was $228 per in-person consultation versus $120 per episode for VC - a 47.4% decrease. The average distance form veteran home to center was 86 miles, with an average travel reimbursement of $112 per in-person consultation, versus no travel cost associated with VC. VC for incidentally discovered pulmonary nodules significantly decreases time to consultation completion, hospital cost, and veteran travel cost. These data suggest that a significant opportunity exists for expansion of telehealth into additional practice settings within the VA system. © Association of Military Surgeons of the United States 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Turbine combustor with fuel nozzles having inner and outer fuel circuits

DOEpatents

Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo

2013-12-24

A combustor cap assembly for a turbine engine includes a combustor cap and a plurality of fuel nozzles mounted on the combustor cap. One or more of the fuel nozzles would include two separate fuel circuits which are individually controllable. The combustor cap assembly would be controlled so that individual fuel circuits of the fuel nozzles are operated or deliberately shut off to provide for physical separation between the flow of fuel delivered by adjacent fuel nozzles and/or so that adjacent fuel nozzles operate at different pressure differentials. Operating a combustor cap assembly in this fashion helps to reduce or eliminate the generation of undesirable and potentially harmful noise.

Lean-rich axial stage combustion in a can-annular gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laster, Walter R.; Szedlacsek, Peter

2016-06-14

An apparatus and method for lean/rich combustion in a gas turbine engine (10), which includes a combustor (12), a transition (14) and a combustor extender (16) that is positioned between the combustor (12) and the transition (14) to connect the combustor (12) to the transition (14). Openings (18) are formed along an outer surface (20) of the combustor extender (16). The gas turbine (10) also includes a fuel manifold (28) to extend along the outer surface (20) of the combustor extender (16), with fuel nozzles (30) to align with the respective openings (18). A method (200) for axial stage combustionmore » in the gas turbine engine (10) is also presented.« less

A conceptual design of shock-eliminating clover combustor for large scale scramjet engine

NASA Astrophysics Data System (ADS)

Sun, Ming-bo; Zhao, Yu-xin; Zhao, Guo-yan; Liu, Yuan

2017-01-01

A new concept of shock-eliminating clover combustor is proposed for large scale scramjet engine to fulfill the requirements of fuel penetration, total pressure recovery and cooling. To generate the circular-to-clover transition shape of the combustor, the streamline tracing technique is used based on an axisymmetric expansion parent flowfield calculated using the method of characteristics. The combustor is examined using inviscid and viscous numerical simulations and a pure circular shape is calculated for comparison. The results showed that the combustor avoids the shock wave generation and produces low total pressure losses in a wide range of flight condition with various Mach number. The flameholding device for this combustor is briefly discussed.

The NASA pollution-reduction technology program for small jet aircraft engines

NASA Technical Reports Server (NTRS)

Fear, J. S.

1976-01-01

Three advanced combustor concepts, designed for the AiResearch TFE 731-2 turbofan engine, were evaluated in screening tests. Goals for carbon monoxide and unburned hydrocarbons were met or closely approached with two of the concepts with relatively modest departures from conventional combustor design practices. A more advanced premixing/prevaporizing combustor, while appearing to have the potential for meeting the oxides of nitrogen goal as well, will require extensive development to make it a practical combustion system. Smoke numbers for the two combustor concepts were well within the EPA smoke standard. Phase 2, Combustor-Engine Compatibility Testing, which is in its early stages, and planned Phase 3, Combustor-Engine Demonstration Testing, are also described.

Results of the pollution reduction technology program for turboprop engines

NASA Technical Reports Server (NTRS)

Mularz, E. J.

1976-01-01

A program was performed to evolve and demonstrate advanced combustor technology aimed at achieving the 1979 EPA standards for turboprop engines (Class P2). The engine selected for this program was the 501-D22A turboprop. Three combustor concepts were designed and tested in a combustor rig at the exact combustor operating conditions of the 50-D22A engine over the EPA landing-takeoff cycle. Each combustor concept exhibited pollutant emissions well below the EPA standards, achieving substantial reductions in unburned hydrocarbons, carbon monoxide, and smoke emissions compared with emissions from the production combustor of this engine. Oxides of nitrogen emissions remained well below the EPA standards, also.

Raising venture capital in the biopharma industry.

PubMed

Leytes, Lev J

2002-11-15

Raising venture capital (VC) is both an art and a science. Future entrepreneurs should carefully consider the various issues of VC financing that have a strong impact on the success of their business. In addition to attracting the best venture capital firms, these issues include such subtle but important points as the timing of financing (especially of the first round), external support sources, desirable qualities of a VC firm, amount to be raised, establishing a productive interface between the founders and the venture capitalists, and most importantly the effects of well-executed VC funding on hiring senior executives and scientific leaders.

An Adaptive Instability Suppression Controls Method for Aircraft Gas Turbine Engine Combustors

NASA Technical Reports Server (NTRS)

Kopasakis, George; DeLaat, John C.; Chang, Clarence T.

2008-01-01

An adaptive controls method for instability suppression in gas turbine engine combustors has been developed and successfully tested with a realistic aircraft engine combustor rig. This testing was part of a program that demonstrated, for the first time, successful active combustor instability control in an aircraft gas turbine engine-like environment. The controls method is called Adaptive Sliding Phasor Averaged Control. Testing of the control method has been conducted in an experimental rig with different configurations designed to simulate combustors with instabilities of about 530 and 315 Hz. Results demonstrate the effectiveness of this method in suppressing combustor instabilities. In addition, a dramatic improvement in suppression of the instability was achieved by focusing control on the second harmonic of the instability. This is believed to be due to a phenomena discovered and reported earlier, the so called Intra-Harmonic Coupling. These results may have implications for future research in combustor instability control.

Computational Analysis of Dynamic SPK(S8)-JP8 Fueled Combustor-Sector Performance

NASA Technical Reports Server (NTRS)

Ryder, R.; Hendricks, Roberts C.; Huber, M. L.; Shouse, D. T.

2010-01-01

Civil and military flight tests using blends of synthetic and biomass fueling with jet fuel up to 50:50 are currently considered as "drop-in" fuels. They are fully compatible with aircraft performance, emissions and fueling systems, yet the design and operations of such fueling systems and combustors must be capable of running fuels from a range of feedstock sources. This paper provides Smart Combustor or Fuel Flexible Combustor designers with computational tools, preliminary performance, emissions and particulates combustor sector data. The baseline fuel is kerosene-JP-8+100 (military) or Jet A (civil). Results for synthetic paraffinic kerosene (SPK) fuel blends show little change with respect to baseline performance, yet do show lower emissions. The evolution of a validated combustor design procedure is fundamental to the development of dynamic fueling of combustor systems for gas turbine engines that comply with multiple feedstock sources satisfying both new and legacy systems.

Method of making an aero-derivative gas turbine engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebe, David J.

A method of making an aero-derivative gas turbine engine (100) is provided. A combustor outer casing (68) is removed from an existing aero gas turbine engine (60). An annular combustor (84) is removed from the existing aero gas turbine engine. A first row of turbine vanes (38) is removed from the existing aero gas turbine engine. A can annular combustor assembly (122) is installed within the existing aero gas turbine engine. The can annular combustor assembly is configured to accelerate and orient combustion gasses directly onto a first row of turbine blades of the existing aero gas turbine engine. Amore » can annular combustor assembly outer casing (108) is installed to produce the aero-derivative gas turbine engine (100). The can annular combustor assembly is installed within an axial span (85) of the existing aero gas turbine engine vacated by the annular combustor and the first row of turbine vanes.« less

Pollution measurements of a swirl-can combustor

NASA Technical Reports Server (NTRS)

Niedzwiecki, R. W.; Jones, R. E.

1972-01-01

Pollutant levels of oxides of nitrogen, unburned hydrocarbons, and carbon monoxide were measured for an experimental, annular, swirl can combustor. The combustor was 42 inches in diameter, incorporated 120 modules, and was specifically designed for elevated exit temperature performance. Test conditions included combustor inlet temperatures of 600, 900 and 1050 F, inlet pressures of 5 to 6 atmospheres, reference velocities of 69 to 120 feet per second and fuel-air ratios of 0.014 to 0.0695. Tests were also conducted at a simulated engine idle condition. Results demonstrated that swirl can combustors produce oxides of nitrogen levels substantially lower than conventional combustor designs. These reductions are attributed to reduced dwell times resulting from short combustor length, quick mixing of combustion gases with diluent air, and to uniform fuel distributions resulting from the swirl can approach. Radial staging of fuel at idle conditions resulted in increases in combustion efficiencies and corresponding reductions in pollutant levels.

Energy efficient engine combustor test hardware detailed design report

NASA Technical Reports Server (NTRS)

Zeisser, M. H.; Greene, W.; Dubiel, D. J.

1982-01-01

The combustor for the Energy Efficient Engine is an annular, two-zone component. As designed, it either meets or exceeds all program goals for performance, safety, durability, and emissions, with the exception of oxides of nitrogen. When compared to the configuration investigated under the NASA-sponsored Experimental Clean Combustor Program, which was used as a basis for design, the Energy Efficient Engine combustor component has several technology advancements. The prediffuser section is designed with short, strutless, curved-walls to provide a uniform inlet airflow profile. Emissions control is achieved by a two-zone combustor that utilizes two types of fuel injectors to improve fuel atomization for more complete combustion. The combustor liners are a segmented configuration to meet the durability requirements at the high combustor operating pressures and temperatures. Liner cooling is accomplished with a counter-parallel FINWALL technique, which provides more effective heat transfer with less coolant.

40 CFR 60.53a - Standard for municipal waste combustor organics.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Municipal Waste Combustors for Which Construction Is Commenced After December 20, 1989 and On or Before September 20, 1994 § 60.53a Standard for municipal waste combustor organics. (a) [Reserved] (b) On and after... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for municipal waste combustor...

40 CFR 60.55b - Standards for municipal waste combustor fugitive ash emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Performance for Large Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standards for municipal waste combustor... municipal waste combustor fugitive ash emissions. (a) On and after the date on which the initial performance...

40 CFR 60.55b - Standards for municipal waste combustor fugitive ash emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Performance for Large Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standards for municipal waste combustor... municipal waste combustor fugitive ash emissions. (a) On and after the date on which the initial performance...

40 CFR 60.54a - Standard for municipal waste combustor acid gases.

Code of Federal Regulations, 2014 CFR

2014-07-01

... for Municipal Waste Combustors for Which Construction Is Commenced After December 20, 1989 and On or Before September 20, 1994 § 60.54a Standard for municipal waste combustor acid gases. (a)-(b) [Reserved... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for municipal waste combustor...

40 CFR 60.54b - Standards for municipal waste combustor operator training and certification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Standards of Performance for Large Municipal Waste Combustors for Which Construction is Commenced After... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standards for municipal waste combustor... Standards for municipal waste combustor operator training and certification. (a) No later than the date 6...

40 CFR 60.53b - Standards for municipal waste combustor operating practices.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Performance for Large Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standards for municipal waste combustor... municipal waste combustor operating practices. (a) On and after the date on which the initial performance...

Performance and emission characteristics of swirl-can combustors to near-stoichiometric fuel-air ratio

NASA Technical Reports Server (NTRS)

Diehl, L. A.; Trout, A. M.

1976-01-01

Emissions and performance characteristics were determined for two full annular swirl-can combustors operated to near stoichiometric fuel-air ratio. Test condition variations were as follows: combustor inlet-air temperatures, 589, 756, 839, and 894 K; reference velocities, 24 to 37 meters per second; inlet pressure, 62 newtons per square centimeter; and fuel-air ratios, 0.015 to 0.065. The combustor average exit temperature and combustor efficiency were calculated from the combustor exhaust gas composition. For fuel-air ratios greater than 0.04, the combustion efficiency decreased with increasing fuel-air ratios in a near-linear manner. Increasing the combustor inlet air temperature tended to offset this decrease. Maximum oxides of nitrogen emission indices occurred at intermediate fuel-air ratios and were dependent on combustor design. Carbon monoxide levels were extremely high and were the primary cause of poor combustion efficiency at the higher fuel-air ratios. Unburned hydrocarbons were low for all test conditions. For high fuel-air ratios SAE smoke numbers greater than 25 were produced, except at the highest inlet-air temperatures.

Lipid mediator profile in vernix caseosa reflects skin barrier development.

PubMed

Checa, Antonio; Holm, Tina; Sjödin, Marcus O D; Reinke, Stacey N; Alm, Johan; Scheynius, Annika; Wheelock, Craig E

2015-11-02

Vernix caseosa (VC) is a protective layer that covers the skin of most human newborns. This study characterized the VC lipid mediator profile, and examined its relationship to gestational period, gender of the newborn and maternal lifestyle. VC collected at birth from 156 newborns within the ALADDIN birth cohort was analyzed and 3 different groups of lipid mediators (eicosanoids and related oxylipin analogs, endocannabinoids and sphingolipids) were screened using LC-MS/MS. A total of 54 compounds were detected in VC. A number of associations between lipid mediators and the gestational period were observed, including increases in the ceramide to sphingomyelin ratio as well as the endocannabinoids anandamide and 2-arachidonoylglycerol. Gender-specific differences in lipid mediator levels were observed for all 3 lipid classes. In addition, levels of the linoleic acid oxidation products 9(10)-epoxy-12Z-octadecenoic and 12(13)-epoxy-9Z-octadecenoic acid (EpOMEs) as well as 12,13-dihydroxy-9Z-octadecenoic acid (DiHOME) were increased in VC of children from mothers with an anthroposophic lifestyle. Accordingly, VC was found to be rich in multiple classes of bioactive lipid mediators, which evidence lifestyle, gender and gestational week dependencies. Levels of lipid mediators in VC may therefore be useful as early stage non-invasive markers of the development of the skin as a protective barrier.

Differential enumeration of subpopulations in concentrated frozen and lyophilized cultures of Lactobacillus delbrueckii ssp. bulgaricus.

PubMed

Shao, Yuyu; Wang, Zhaoxia; Bao, Qiuhua; Zhang, Heping

2017-11-01

Differential enumeration of subpopulations in concentrated frozen and lyophilized cultures of Lactobacillus delbrueckii ssp. bulgaricus ND02 derived from 2 propagation procedures was determined. The subpopulations consisted of 3 categories (physiological states): viable cells capable of forming colonies on agar plates (VC+), viable cells incapable of forming colonies on agar plates (VC-), widely referred to as viable but nonculturable (VBNC) cells, and nonviable or dead cells (NVC). Counts of VC+ were recorded using a conventional plate count procedure. A fluorescent vital staining procedure that discriminates between viable (VC+ and VC-) and NVC cells was used to determine the number of viable and nonviable cells. Both propagation procedures had 2 variables: in procedure (P)1, the propagation medium was rich in yeast extract (4.0%) and the pH was maintained at 5.7; in P2, the medium was devoid of yeast extract and the pH was maintained at 5.1. The results showed that post-propagation operations-concentration of cells by centrifugation and subsequent freezing or lyophilization of cell concentrate-induced different degrees of transience from VC+ to VC- states in cells derived from P1 and P2. Compared with cells derived from P2, cells from P1 were more labile to stress associated with centrifugation, freezing, and lyophilization, as revealed by differential counting. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A quantitative PCR assay for aerobic, vinyl chloride- and ethene-assimilating microorganisms in groundwater.

PubMed

Jin, Yang Oh; Mattes, Timothy E

2010-12-01

Vinyl chloride (VC) is a known human carcinogen that is primarily formed in groundwater via incomplete anaerobic dechlorination of chloroethenes. Aerobic, ethene-degrading bacteria (etheneotrophs), which are capable of both fortuitous and growth-linked VC oxidation, could be important in natural attenuation of VC plumes that escape anaerobic treatment. In this work, we developed a quantitative, real-time PCR (qPCR) assay for etheneotrophs in groundwater. We designed and tested degenerate qPCR primers for two functional genes involved in aerobic, growth-coupled VC- and ethene-oxidation (etnC and etnE). Primer specificity to these target genes was tested by comparison to nucleotide sequence databases, PCR analysis of template DNA extracted from isolates and environmental samples, and sequencing of qPCR products obtained from VC-contaminated groundwater. The assay was made quantitative by constructing standard curves (threshold cycle vs log gene copy number) with DNA amplified from Mycobacterium strain JS60, an etheneotrophic isolate. Analysis of groundwater samples from three different VC-contaminated sites revealed that etnC abundance ranged from 1.6 × 10(3) - 1.0 × 10(5) copies/L groundwater while etnE abundance ranged from 4.3 × 10(3) - 6.3 × 10(5) copies/L groundwater. Our data suggest this novel environmental measurement method will be useful for supporting VC bioremediation strategies, assisting in site closure, and conducting microbial ecology studies involving etheneotrophs.

Magnesium prevents phosphate-induced vascular calcification via TRPM7 and Pit-1 in an aortic tissue culture model.

PubMed

Sonou, Tomohiro; Ohya, Masaki; Yashiro, Mitsuru; Masumoto, Asuka; Nakashima, Yuri; Ito, Teppei; Mima, Toru; Negi, Shigeo; Kimura-Suda, Hiromi; Shigematsu, Takashi

2017-06-01

Previous clinical and experimental studies have indicated that magnesium may prevent vascular calcification (VC), but mechanistic characterization has not been reported. This study investigated the influence of increasing magnesium concentrations on VC in a rat aortic tissue culture model. Aortic segments from male Sprague-Dawley rats were incubated in serum-supplemented high-phosphate medium for 10 days. The magnesium concentration in this medium was increased to demonstrate its role in preventing VC, which was assessed by imaging and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) mapping. Magnesium supplementation of high-phosphate medium dose-dependently suppressed VC (quantified as aortic calcium content), and almost ablated it at 2.4 mm magnesium. The FTIR images and SEM-EDX maps indicated that the distribution of phosphate (as hydroxyapatite), phosphorus and Mg corresponded with calcium content in the aortic ring and VC. The inhibitory effect of magnesium supplementation on VC was partially reduced by 2-aminoethoxy-diphenylborate, an inhibitor of TRPM7. Furthermore, phosphate transporter-1 (Pit-1) protein expression was increased in tissues cultured in HP medium and was gradually-and dose dependently-decreased by magnesium. We conclude that a mechanism involving TRPM7 and Pit-1 underpins the magnesium-mediated reversal of high-phosphate-associated VC.

FORMATION OF 7-(2-0XOETHYL)GUANINE FROM LIPID PEROXIDATION AND VINYL CHLORIDE EXPOSURE IN MALE SPRAGUE DAWLEY RATS

EPA Science Inventory

Vinyl Chloride (VC) is a known human and animal carcinogen that induces hepatic angiosarcomas. Other than occupational exposure and smoking, VC is also found in Superfund sites at ppb concentrations. VC is metabolized to chloroethylene oxide by CYP450 2E1 to induce four major DNA...

A Comparison of Intellectual Assessments over Video Conferencing and In-Person for Individuals with ID: Preliminary Data

ERIC Educational Resources Information Center

Temple, V.; Drummond, C.; Valiquette, S.; Jozsvai, E.

2010-01-01

Background: Video conferencing (VC) technology has great potential to increase accessibility to healthcare services for those living in rural or underserved communities. Previous studies have had some success in validating a small number of psychological tests for VC administration; however, VC has not been investigated for use with persons with…

Flame stabilization and mixing characteristics in a Stagnation Point Reverse Flow combustor

NASA Astrophysics Data System (ADS)

Bobba, Mohan K.

A novel combustor design, referred to as the Stagnation Point Reverse-Flow (SPRF) combustor, was recently developed that is able to operate stably at very lean fuel-air mixtures and with low NOx emissions even when the fuel and air are not premixed before entering the combustor. The primary objective of this work is to elucidate the underlying physics behind the excellent stability and emissions performance of the SPRF combustor. The approach is to experimentally characterize velocities, species mixing, heat release and flame structure in an atmospheric pressure SPRF combustor with the help of various optical diagnostic techniques: OH PLIF, chemiluminescence imaging, PIV and Spontaneous Raman Scattering. Results indicate that the combustor is primarily stabilized in a region downstream of the injector that is characterized by low average velocities and high turbulence levels; this is also the region where most of the heat release occurs. High turbulence levels in the shear layer lead to increased product entrainment levels, elevating the reaction rates and thereby enhancing the combustor stability. The effect of product entrainment on chemical timescales and the flame structure is illustrated with simple reactor models. Although reactants are found to burn in a highly preheated (1300 K) and turbulent environment due to mixing with hot product gases, the residence times are sufficiently long compared to the ignition timescales such that the reactants do not autoignite. Turbulent flame structure analysis indicates that the flame is primarily in the thin reaction zones regime throughout the combustor, and it tends to become more flamelet like with increasing distance from the injector. Fuel-air mixing measurements in case of non-premixed operation indicate that the fuel is shielded from hot products until it is fully mixed with air, providing nearly premixed performance without the safety issues associated with premixing. The reduction in NOx emissions in the SPRF combustor are primarily due to its ability to stably operate under ultra lean (and nearly premixed) condition within the combustor. Further, to extend the usefulness of this combustor configuration to various applications, combustor geometry scaling rules were developed with the help of simplified coaxial and opposed jet models.

Active Control of Combustor Instability Shown to Help Lower Emissions

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Chang, Clarence T.

2002-01-01

In a quest to reduce the environmental impact of aerospace propulsion systems, extensive research is being done in the development of lean-burning (low fuel-to-air ratio) combustors that can reduce emissions throughout the mission cycle. However, these lean-burning combustors have an increased susceptibility to thermoacoustic instabilities, or high-pressure oscillations much like sound waves, that can cause severe high-frequency vibrations in the combustor. These pressure waves can fatigue the combustor components and even the downstream turbine blades. This can significantly decrease the safe operating life of the combustor and turbine. Thus, suppression of the thermoacoustic combustor instabilities is an enabling technology for lean, low-emissions combustors. Under the Aerospace Propulsion and Power Base Research and Technology Program, the NASA Glenn Research Center, in partnership with Pratt & Whitney and United Technologies Research Center, is developing technologies for the active control of combustion instabilities. With active combustion control, the fuel is pulsed to put pressure oscillations into the system. This cancels out the pressure oscillations being produced by the instabilities. Thus, the engine can have lower pollutant emissions and long life.The use of active combustion instability control to reduce thermo-acoustic-driven combustor pressure oscillations was demonstrated on a single-nozzle combustor rig at United Technologies. This rig has many of the complexities of a real engine combustor (i.e., an actual fuel nozzle and swirler, dilution cooling, etc.). Control was demonstrated through modeling, developing, and testing a fuel-delivery system able to the 280-Hz instability frequency. The preceding figure shows the capability of this system to provide high-frequency fuel modulations. Because of the high-shear contrarotating airflow in the fuel injector, there was some concern that the fuel pulses would be attenuated to the point where they would not be effective for control. Testing in the combustor rig showed that open-loop pulsing of the fuel was, in fact, able to effectively modulate the combustor pressure. To suppress the combustor pressure oscillations due to thermoacoustic instabilities, it is desirable to time the injection of the fuel so that it interferes with the instability. A closed-loop control scheme was developed that uses combustion pressure feedback and a phase-shifting controller to time the fuel-injection pulses. Some suppression of the pressure oscillations at the 280-Hz instability frequency was demonstrated (see the next figure). However, the overall peak-to- peak pressure oscillations in the combustor were only mildly reduced. Improvements to control hardware and control methods are being continued to gain improved closed-loop reduction of the pressure oscillations.pulse the fuel at

Intramuscular Immunization of Mice with the Live-Attenuated Herpes Simplex Virus 1 Vaccine Strain VC2 Expressing Equine Herpesvirus 1 (EHV-1) Glycoprotein D Generates Anti-EHV-1 Immune Responses in Mice.

PubMed

Liu, Shiliang A; Stanfield, Brent A; Chouljenko, Vladimir N; Naidu, Shan; Langohr, Ingeborg; Del Piero, Fabio; Ferracone, Jacqueline; Roy, Alma A; Kousoulas, Konstantin G

2017-06-15

Vaccination remains the best option to combat equine herpesvirus 1 (EHV-1) infection, and several different strategies of vaccination have been investigated and developed over the past few decades. Herein, we report that the live-attenuated herpes simplex virus 1 (HSV-1) VC2 vaccine strain, which has been shown to be unable to enter into neurons and establish latency in mice, can be utilized as a vector for the heterologous expression of EHV-1 glycoprotein D (gD) and that the intramuscular immunization of mice results in strong antiviral humoral and cellular immune responses. The VC2-EHV-1-gD recombinant virus was constructed by inserting an EHV-1 gD expression cassette under the control of the cytomegalovirus immediate early promoter into the VC2 vector in place of the HSV-1 thymidine kinase (UL23) gene. The vaccines were introduced into mice through intramuscular injection. Vaccination with both the VC2-EHV-1-gD vaccine and the commercially available vaccine Vetera EHV XP 1/4 (Vetera; Boehringer Ingelheim Vetmedica) resulted in the production of neutralizing antibodies, the levels of which were significantly higher in comparison to those in VC2- and mock-vaccinated animals ( P < 0.01 or P < 0.001). Analysis of EHV-1-reactive IgG subtypes demonstrated that vaccination with the VC2-EHV-1-gD vaccine stimulated robust IgG1 and IgG2a antibodies after three vaccinations ( P < 0.001). Interestingly, Vetera-vaccinated mice produced significantly higher levels of IgM than mice in the other groups before and after challenge ( P < 0.01 or P < 0.05). Vaccination with VC2-EHV-1-gD stimulated strong cellular immune responses, characterized by the upregulation of both interferon- and tumor necrosis factor-positive CD4 + T cells and CD8 + T cells. Overall, the data suggest that the HSV-1 VC2 vaccine strain may be used as a viral vector for the vaccination of horses as well as, potentially, for the vaccination of other economically important animals. IMPORTANCE A novel virus-vectored VC2-EHV-1-gD vaccine was constructed using the live-attenuated HSV-1 VC2 vaccine strain. This vaccine stimulated strong humoral and cellular immune responses in mice, suggesting that it could protect horses against EHV-1 infection. Copyright © 2017 American Society for Microbiology.

Chromosome aberrations detected by conventional karyotyping using novel mitogens in chronic lymphocytic leukemia: Clinical and biologic correlations.

PubMed

Rigolin, Gian Matteo; del Giudice, Ilaria; Formigaro, Luca; Saccenti, Elena; Martinelli, Sara; Cavallari, Maurizio; Lista, Enrico; Tammiso, Elisa; Volta, Eleonora; Lupini, Laura; Bassi, Cristian; Bardi, Antonella; Sofritti, Olga; Daghia, Giulia; Cavazzini, Francesco; Marinelli, Marilisa; Tavolaro, Simona; Guarini, Anna; Negrini, Massimo; Foà, Robin; Cuneo, Antonio

2015-12-01

To clarify whether karyotype aberrations (KA) involving regions not covered by the standard fluorescence in situ hybridization (FISH) panel have independent prognostic relevance, we evaluated KA by conventional cytogenetics in a learning cohort (LC; n = 166) and a validation cohort (VC; n = 250) of untreated chronic lymphocytic leukemia (CLL) patients. In the VC, novel mitogens were used to improve metaphase generation and TP53, NOTCH1, and SF3B1 mutations were assessed. KA undetected by FISH were found in 35 and 35% of the cases in the LC and VC, respectively. In addition to FISH, KA allowed reclassification of 23 and 26% of cases in the LC and VC, respectively, into a higher cytogenetic risk group. By multivariate analysis, both in the LC and VC, KA other than isolated 13q deletion correlated with a shorter time to first treatment (TFT; P < 0.001 and 0.003, respectively), while a complex karyotype predicted a worse overall survival (OS, P = 0.015 and 0.010, respectively). In the VC, where a comprehensive biologic assessment was performed, a shorter TFT was also predicted by stage (P < 0.001), IGHV mutational status (P = 0.05), and del(17p)/TP53 mutations (P = 0.033) while stage (P = 0.023) and del(17p)/TP53 mutations (P = 0.024) independently predicted a shorter OS. FISH results did not independently impact on TFT and OS, in the LC and VC cohorts; this was also the case for NOTCH1 and SF3B1 mutations in the VC. We suggest that in CLL, conventional karyotyping with novel mitogens could be more effective than FISH for the detection of KA allowing for a more precise refinement of prognosis. © 2015 Wiley Periodicals, Inc.

The Vaccinium corymbosum FLOWERING LOCUS T-like gene (VcFT): a flowering activator reverses photoperiodic and chilling requirements in blueberry.

PubMed

Song, Guo-qing; Walworth, Aaron; Zhao, Dongyan; Jiang, Ning; Hancock, James F

2013-11-01

The blueberry FLOWERING LOCUS T ( FT )-like gene ( VcFT ) cloned from the cDNA of a tetraploid, northern highbush blueberry ( Vaccinium corymbosum L.) is able to reverse the photoperiodic and chilling requirements and drive early and continuous flowering. Blueberry is a woody perennial bush with a longer juvenile period than annual crops, requiring vernalization to flower normally. Few studies have been reported on the molecular mechanism of flowering in blueberry or other woody plants. Because FLOWERING LOCUS T (FT) from Arabidopsis thaliana plays a multifaceted role in generating mobile molecular signals to regulate plant flowering time, isolation and functional analysis of the blueberry (Vaccinium corymbosum L.) FT-like gene (VcFT) will facilitate the elucidation of molecular mechanisms of flowering in woody plants. Based on EST sequences, a 525-bpVcFT was identified and cloned from the cDNA of a tetraploid, northern highbush blueberry cultivar, Bluecrop. Ectopic expression of 35S:VcFT in tobacco induced flowering an average of 28 days earlier than wild-type plants. Expression of the 35S:VcFT in the blueberry cultivar Aurora resulted in an extremely early flowering phenotype, which flowered not only during in vitro culture, a growth stage when nontransgenic shoots had not yet flowered, but also in 6-10-week old, soil-grown transgenic plants, in contrast to the fact that at least 1 year and 800 chilling hours are required for the appearance of the first flower of both nontransgenic 'Aurora' and transgenic controls with the gusA. These results demonstrate that the VcFT is a functional floral activator and overexpression of the VcFT is able to reverse the photoperiodic and chilling requirements and drive early and continuous flowering.

TR-ESR Investigation on Reaction of Vitamin C with Excited Triplet of 9,10-phenanthrenequinone in Reversed Micelle Solutions

NASA Astrophysics Data System (ADS)

Xu, Xin-sheng; Shi, Lei; Liu, Yi; Ji, Xue-han; Cui, Zhi-feng

2011-04-01

Time-resolved electron spin resonance has been used to study quenching reactions between the antioxidant Vitamin C (VC) and the triplet excited states of 9,10-phenanthrenequinone (PAQ) in ethylene glycol-water (EG-H2O) homogeneous and inhomogeneous reversed micelle solutions. Reversed micelle solutions were used to be the models of physiological environment of biological cell and tissue. In PAQ/EG-H2O homogeneous solution, the excited triplet of PAQ (3PAQ*) abstracts hydrogen atom from solvent EG. In PAQ/VC/EG-H2O solution, 3PAQ* abstracts hydrogen atom not only from solvent EG but also from VC. The quenching rate constant of 3PAQ* by VC is close to the diffusion-controlled value of 1.41 × 108 L/(mol ·s). In hexadecyltrimethylammonium bromide (CTAB)/EG-H2O and aerosol OT (AOT)/EG-H2O reversed micelle solutions, 3PAQ* and VC react around the water-oil interface of the reversed micelle. Exit of 3PAQ* from the lipid phase slows down the quenching reaction. For Triton X-100 (TX-100)/EG-H2O reversed micelle solution, PAQ and VC coexist inside the hydrophilic polyethylene glycol core, and the quenching rate constant of 3PAQ* by VC is larger than those in AOT/EG-H2O and CTAB/EG-H2O reversed micelle solutions, even a little larger than that in EG-H2O homogeneous solution. The strong emissive chemically induced dynamic electron polarization of As.- resulted from the effective TM spin polarization transfer in hydrogen abstraction of 3PAQ* from VC.

Effects of Vacancy Cluster Defects on Electrical and Thermodynamic Properties of Silicon Crystals

PubMed Central

Huang, Pei-Hsing; Lu, Chi-Ming

2014-01-01

A first-principle plane-wave pseudopotential method based on the density function theory (DFT) was employed to investigate the effects of vacancy cluster (VC) defects on the band structure and thermoelectric properties of silicon (Si) crystals. Simulation results showed that various VC defects changed the energy band and localized electron density distribution of Si crystals and caused the band gap to decrease with increasing VC size. The results can be ascribed to the formation of a defect level produced by the dangling bonds, floating bonds, or high-strain atoms surrounding the VC defects. The appearance of imaginary frequencies in the phonon spectrum of defective Si crystals indicates that the defect-region structure is dynamically unstable and demonstrates phase changes. The phonon dispersion relation and phonon density of state were also investigated using density functional perturbation theory. The obtained Debye temperature (θ D) for a perfect Si crystal had a minimum value of 448 K at T = 42 K and a maximum value of 671 K at the high-temperature limit, which is consistent with the experimental results reported by Flubacher. Moreover, the Debye temperature decreased with increases in the VC size. VC defects had minimal effects on the heat capacity (C v) value when temperatures were below 150 K. As the temperature was higher than 150 K, the heat capacity gradually increased with increasing temperature until it achieved a constant value of 11.8 cal/cell·K. The heat capacity significantly decreased as the VC size increased. For a 2 × 2 × 2 superlattice Si crystal containing a hexagonal ring VC (HRVC10), the heat capacity decreased by approximately 17%. PMID:24526923

Oxidative Stress Response Induced by Butachlor in Zebrafish Embryo/Larvae: The Protective Effect of Vitamin C.

PubMed

Xiang, Qingqing; Xu, Bofan; Ding, Yilun; Liu, Xiaoyi; Zhou, Ying; Ahmad, Farooq

2018-02-01

The widespread contamination and persistence of the herbicide butachlor in the environment resulted in the exposure of non-target organisms. The present study investigated the toxicity effect of butachlor (1-15 µmol/L) and the protective effect of vitamin C (VC) against butachlor-induced toxicity in zebrafish. It was found that butachlor significantly increased the mortality and malformation rates in a dose-dependent manner, which caused elevation in reactive oxygen species (ROS) and malondialdehyde (MDA) after 72 h exposure. Compared with butachlor treatment group, the protective effect of VC against butachlor-induced toxicity were observed after adding 40, 80 mg/L VC respectively. VC significantly decreased the mortality, malformation rates, ROS, MDA, and normalized antioxidant enzymes activities of zebrafish after 72 h exposure. The result shows VC has mitigative effect on butachlor-induced toxicity and it can be used as an effective antioxidant in aquaculture.

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.

Code of Federal Regulations, 2010 CFR

2010-07-01

... combustor metals, acid gases, organics, and nitrogen oxides. 62.14103 Section 62.14103 Protection of... combustor metals, acid gases, organics, and nitrogen oxides. (a) The emission limits for municipal waste combustor metals are specified in paragraphs (a)(1) through (a)(3) of this section. (1) The owner or...

40 CFR 60.52a - Standard for municipal waste combustor metals.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Municipal Waste Combustors for Which Construction Is Commenced After December 20, 1989 and On or Before September 20, 1994 § 60.52a Standard for municipal waste combustor metals. (a) On and after the date on... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for municipal waste combustor...

40 CFR Table 3 to Subpart Cb of... - Municipal Waste Combustor Operating Guidelines

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Municipal Waste Combustor Operating... and Compliance Times for Large Municipal Waste Combustors That are Constructed on or Before September 20, 1994 Pt. 60, Subpt. Cb, Table 3 Table 3 to Subpart Cb of Part 60—Municipal Waste Combustor...

System and method for reducing combustion dynamics in a combustor

DOEpatents

Uhm, Jong Ho; Ziminsky, Willy Steve; Johnson, Thomas Edward; Srinivasan, Shiva; York, William David

2016-11-29

A system for reducing combustion dynamics in a combustor includes an end cap that extends radially across the combustor and includes an upstream surface axially separated from a downstream surface. A combustion chamber is downstream of the end cap, and tubes extend from the upstream surface through the downstream surface. Each tube provides fluid communication through the end cap to the combustion chamber. The system further includes means for reducing combustion dynamics in the combustor. A method for reducing combustion dynamics in a combustor includes flowing a working fluid through tubes that extend axially through an end cap that extends radially across the combustor and obstructing at least a portion of the working fluid flowing through a first set of the tubes.

The 3-D CFD modeling of gas turbine combustor-integral bleed flow interaction

NASA Technical Reports Server (NTRS)

Chen, D. Y.; Reynolds, R. S.

1993-01-01

An advanced 3-D Computational Fluid Dynamics (CFD) model was developed to analyze the flow interaction between a gas turbine combustor and an integral bleed plenum. In this model, the elliptic governing equations of continuity, momentum and the k-e turbulence model were solved on a boundary-fitted, curvilinear, orthogonal grid system. The model was first validated against test data from public literature and then applied to a gas turbine combustor with integral bleed. The model predictions agreed well with data from combustor rig testing. The model predictions also indicated strong flow interaction between the combustor and the integral bleed. Integral bleed flow distribution was found to have a great effect on the pressure distribution around the gas turbine combustor.

Gas turbine combustor

NASA Technical Reports Server (NTRS)

Burd, Steven W. (Inventor); Cheung, Albert K. (Inventor); Dempsey, Dae K. (Inventor); Hoke, James B. (Inventor); Kramer, Stephen K. (Inventor); Ols, John T. (Inventor); Smith, Reid Dyer Curtis (Inventor); Sowa, William A. (Inventor)

2011-01-01

A gas turbine engine has a combustor module including an annular combustor having a liner assembly that defines an annular combustion chamber having a length, L. The liner assembly includes a radially inner liner, a radially outer liner that circumscribes the inner liner, and a bulkhead, having a height, H1, which extends between the respective forward ends of the inner liner and the outer liner. The combustor has an exit height, H3, at the respective aft ends of the inner liner and the outer liner interior. The annular combustor has a ratio H1/H3 having a value less than or equal to 1.7. The annular combustor may also have a ration L/H3 having a value less than or equal to 6.0.

Apparatus and method for gas turbine active combustion control system

NASA Technical Reports Server (NTRS)

Knobloch, Aaron (Inventor); Mancini, Alfred Albert (Inventor); Myers, William J. (Inventor); Fortin, Jeffrey B. (Inventor); Umeh, Chukwueloka (Inventor); Kammer, Leonardo C. (Inventor); Shah, Minesh (Inventor)

2011-01-01

An Active Combustion Control System and method provides for monitoring combustor pressure and modulating fuel to a gas turbine combustor to prevent combustion dynamics and/or flame extinguishments. The system includes an actuator, wherein the actuator periodically injects pulsed fuel into the combustor. The apparatus also includes a sensor connected to the combustion chamber down stream from an inlet, where the sensor generates a signal detecting the pressure oscillations in the combustor. The apparatus controls the actuator in response to the sensor. The apparatus prompts the actuator to periodically inject pulsed fuel into the combustor at a predetermined sympathetic frequency and magnitude, thereby controlling the amplitude of the pressure oscillations in the combustor by modulating the natural oscillations.

Strategies for Increasing the Market Share of Recycled Products—A Games Theory Approach

NASA Astrophysics Data System (ADS)

Batzias, Dimitris F.; Pollalis, Yannis A.

2009-08-01

A methodological framework (including 28 activity stages and 10 decision nodes) has been designed under the form of an algorithmic procedure for the development of strategies for increasing the market share of recycled products within a games theory context. A case example is presented referring to a paper market, where a recycling company (RC) is in competition with a virgin-raw-material-using company (VC). The strategies of the VC, for increasing its market share, are the strengthening of (and advertisement based on) the high quality (VC1), the high reliability (VC2), the combination quality and reliability, putting emphasis on the first component (VC3), the combination quality and reliability, putting emphasis on the second component (VC4). The strategies of the RC, for increasing its market share, are proper advertisement based on the low price of produced recycled paper satisfying minimum quality requirements (RC1), the combination of low price with sensitization of the public as regards environmental and materials-saving issues, putting emphasis on the first component (RC2), the same combination, putting emphasis on the second component (RC3). Analysis of all possible situations for the case example under examination is also presented.

VcBBX, VcMYB21, and VcR2R3MYB Transcription Factors Are Involved in UV-B-Induced Anthocyanin Biosynthesis in the Peel of Harvested Blueberry Fruit.

PubMed

Nguyen, Chau T T; Lim, Sooyeon; Lee, Jeong Gu; Lee, Eun Jin

2017-03-15

This study was carried out to better understand the mechanism responsible for increasing the anthocyanins in blueberries after UV-B radiation at 6.0 kJ m -2 for 20 min. UV-B induced upregulation of genes involved in anthocyanin biosynthesis in blueberry fruit compared to a nontreated control. Phenylalanine ammonia lyase, chalcone synthase, and flavanone 3'-hydroxylase, which are enzymes that function upstream of anthocyanin biosynthesis, were significantly expressed by UV-B. Expression levels of VcBBX, VcMYB21, and VcR2R3MYB transcription factors (TFs) were upregulated by UV-B in the same manner as the anthocyanin biosynthesis genes. The significant increase in the expression of TFs occurred immediately after UV-B treatment and was then maximized within 3 h. In accordance with these changes, individual anthocyanin contents in the fruits treated with UV-B significantly increased within 6 h and were 2-3-fold higher than the control. Our results indicated that UV-B radiation stimulates an increase in anthocyanin biosynthesis, which could be upregulated by the TFs studied.

Self-assembly of Carbon Vacancies in Sub-stoichiometric ZrC1−x

PubMed Central

Zhang, Yanhui; Liu, Bin; Wang, Jingyang

2015-01-01

Sub-stoichiometric interstitial compounds, including binary transition metal carbides (MC1−x), maintain structural stability even if they accommodate abundant anion vacancies. This unique character endows them with variable-composition, diverse-configuration and controllable-performance through composition and structure design. Herein, the evolution of carbon vacancy (VC) configuration in sub-stoichiometric ZrC1−x is investigated by combining the cluster expansion method and first-principles calculations. We report the interesting self-assembly of VCs and the fingerprint VC configuration (VC triplet constructed by 3rd nearest neighboring vacancies) in all the low energy structures of ZrC1−x. When VC concentration is higher than the critical value of 0.5 (x > 0.5), the 2nd nearest neighboring VC configurations with strongly repulsive interaction inevitably appear, and meanwhile, the system energy (or formation enthalpy) of ZrC1−x increases sharply which suggests the material may lose phase stability. The present results clarify why ZrC1−x bears a huge amount of VCs, tends towards VC ordering, and retains stability up to a stoichiometry of x = 0.5. PMID:26667083

Histone Methylation Restrains the Expression of Subtype-Specific Genes during Terminal Neuronal Differentiation in Caenorhabditis elegans

PubMed Central

Chiang, Victor; Chalfie, Martin

2013-01-01

Although epigenetic control of stem cell fate choice is well established, little is known about epigenetic regulation of terminal neuronal differentiation. We found that some differences among the subtypes of Caenorhabditis elegans VC neurons, particularly the expression of the transcription factor gene unc-4, require histone modification, most likely H3K9 methylation. An EGF signal from the vulva alleviated the epigenetic repression of unc-4 in vulval VC neurons but not the more distant nonvulval VC cells, which kept unc-4 silenced. Loss of the H3K9 methyltransferase MET-2 or H3K9me2/3 binding proteins HPL-2 and LIN-61 or a novel chromodomain protein CEC-3 caused ectopic unc-4 expression in all VC neurons. Downstream of the EGF signaling in vulval VC neurons, the transcription factor LIN-11 and histone demethylases removed the suppressive histone marks and derepressed unc-4. Behaviorally, expression of UNC-4 in all the VC neurons caused an imbalance in the egg-laying circuit. Thus, epigenetic mechanisms help establish subtype-specific gene expression, which are needed for optimal activity of a neural circuit. PMID:24348272

Influence of supplemental vitamin C on postmortem protein degradation and fatty acid profiles of the longissimus thoracis of steers fed varying concentrations of dietary sulfur.

PubMed

Pogge, Danielle J; Lonergan, Steven M; Hansen, Stephanie L

2014-02-01

The objective was to examine the effects of supplemental vitamin C (VC) on postmortem protein degradation and fatty acid profiles of cattle receiving varying concentrations of dietary sulfur (S). A longissimus muscle was collected from 120 Angus-cross steers assigned to a 3 × 2 factorial, evaluating three concentrations of dietary S (0.22, 0.34, and 0.55%) and two concentrations of supplemental VC (0 or 10 g h(-1)d(-1)). Increasing dietary S and VC supplementation (P<0.001) increased the percent polyunsaturated fatty acids of steaks. Addition of VC tended to increase (P = 0.09) both Fe and 2-thiobarbituric acid content of longissimus thoracis. Increasing S increased (P = 0.03) the proportion of 80-kDa subunit of μ-calpain. Addition of VC within the high S treatment increased (P = 0.05) the abundance of 76-kDa subunit of μ-calpain. Increasing S decreased troponin T degradation (P = 0.07) and protein carbonylation (P<0.01). Supplemental VC appears to alleviate negative effects of high S on autolysis of μ-calpain and protein degradation. © 2013.

Improving the representation of Arctic photosynthesis in Earth System Models

NASA Astrophysics Data System (ADS)

Rogers, A.; Serbin, S.; Sloan, V. L.; Norby, R. J.; Wullschleger, S. D.

2014-12-01

The primary goal of Earth System Models (ESMs) is to improve understanding and projection of future global change. In order to do this models must accurately represent the terrestrial carbon cycle. Although Arctic carbon fluxes are small relative to global carbon fluxes, uncertainty is large. Photosynthetic CO2 uptake is well described by the Farquhar, von Caemmerer and Berry (FvCB) model of photosynthesis and most ESMs use a derivation of the FvCB model to calculate gross primary productivity. Two key parameters required by the FvCB model are an estimate of the maximum rate of carboxylation by the enzyme Rubisco (Vc,max) and the maximum rate of electron transport (Jmax). In ESMs the parameter Vc,max is typically fixed for a given plant functional type (PFT). Only four ESMs currently have an explicit Arctic PFT and the data used to derive Vc,max in these models relies on small data sets and unjustified assumptions. We examined the derivation of Vc,max and Jmax in current Arctic PFTs and estimated Vc,max and Jmax for a range of Arctic PFTs growing on the Barrow Environmental Observatory, Barrow, AK. We found that the values of Vc,max currently used to represent Arctic plants in ESMs are 70% lower than the values we measured, and contemporary temperature response functions for Vc,max also appear to underestimate Vc,max at low temperature. ESMs typically use a single multiplier (JVratio) to convert Vc,max to Jmax, however we found that the JVratio of Arctic plants is higher than current estimates suggesting that Arctic PFTs will be more responsive to rising carbon dioxide than currently projected. In addition we are exploring remotely sensed methods to scale up key biochemical (e.g. leaf N, leaf mass area) and physiological (e.g. Vc,max and Jmax) properties that drive model representation of photosynthesis in the Arctic. Our data suggest that the Arctic tundra has a much greater capacity for CO2 uptake, particularly at low temperature, and will be more CO2 responsive than is currently represented in ESMs. As we build robust relationships between physiology and spectral signatures we hope to provide spatially and temporally resolved trait maps of key model parameters that can be ingested by new model frameworks, or used to validate emergent model properties.

The clinical significance of 5% change in vital capacity in patients with idiopathic pulmonary fibrosis: extended analysis of the pirfenidone trial

PubMed Central

2011-01-01

Background Our phase III clinical trial of pirfenidone for patients with idiopathic pulmonary fibrosis (IPF) revealed the efficacy in reducing the decline of vital capacity (VC) and increasing the progression-free survival (PFS) time by pirfenidone. Recently, marginal decline in forced VC (FVC) has been reported to be associated with poor outcome in IPF. We sought to evaluate the efficacy of pirfenidone from the aspects of 5% change in VC. Methods Improvement ratings based on 5% change in absolute VC, i.e., "improved (VC ≥ 5% increase)", "stable (VC < 5% change)", and "worsened (VC ≥ 5% decrease)" at month 3, 6, 9 and 12 were compared between high-dose pirfenidone (1800 mg/day; n = 108) and placebo (n = 104) groups, and (high-dose and low-dose (1200 mg/day; n = 55)) pirfenidone (n = 163) and placebo groups. PFS times with defining the disease progression as death or a ≥ 5% decline in VC were also compared between high-dose pirfenidone and placebo groups, and low-dose pirfenidone and placebo groups. Furthermore, considering "worsened" and "non-worsened (improved and stable)" of the ratings at months 3 and 12 as "positive" and "negative", respectively, and the positive and negative predictive values of the ratings were calculated in each group. Results In the comparison of the improvement ratings, the statistically significant differences were clearly revealed at months 3, 6, 9, and 12 between pirfenidone and placebo groups. Risk reductions by pirfenidone to placebo were approximately 35% over the study period. In the comparison of the PFS times, statistically significant difference was also observed between pirfenidone and placebo groups. The positive/negative predictive values in placebo and pirfenidone groups were 86.1%/50.8% and 87.1%/71.7%, respectively. Further, the baseline characteristics of patients worsened at month 3 had generally severe impairment, and their clinical outcomes including mortality were also significantly worsened after 1 year. Conclusions The efficacy of pirfenidone in Japanese phase III trial was supported by the rating of 5% decline in VC, and the VC changes at month 3 may be used as a prognostic factor of IPF. Trial Registration This clinical trial was registered with the Japan Pharmaceutical Information Center (JAPIC) on September 13th, 2005 (Registration Number: JAPICCTI-050121). PMID:21756364

Dichloroethene and Vinyl Chloride Degradation Potential in Wetland Sediments at Twin Lakes and Pen Branch, Savannah River National Laboratory, South Carolina

USGS Publications Warehouse

Bradley, Paul M.

2007-01-01

A series of 14C-radiotracer-based microcosm experiments was conducted to assess the mechanisms and products of degradation of dichloroethene (DCE) and vinyl chloride (VC) in wetland sediments at the Department of Energy (DOE) Savannah River National Laboratory. This project investigated the potential for biotic and abiotic DCE and VC degradation in wetland sediments from the Twin Lakes area of the C-BRP investigative unit and from the portion of Pen Branch located directly down gradient from the CMP investigative unit. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC to 14CO2 was observed in all viable sediment microcosms prepared under oxic conditions. These results indicate that microbial mineralization processes, involving direct oxidation or cometabolic oxidation, are the primary mechanisms of DCE and VC biodegradation in Twin Lake and Pen Branch sediments under oxic conditions. Substantial degradation of [1,2-14C] DCE and [1,2-14C] VC was observed in all viable sediment microcosms incubated under anoxic conditions. Production of 14CO2 was observed in all sediment microcosms under anoxic conditions. In general, the accumulation of mineralization products (14CO2 and 14CH4) was comparable to the accumulation of those reduced daughter products (14C-VC, 14C-ethene or 14C-ethane) traditionally identified with chloroethene reductive dechlorination. These results indicate that microbial mineralization processes can be an important component of DCE and VC degradation in Twin Lake and Pen Branch sediments under anoxic conditions. These results demonstrate that an evaluation of the efficiency of in situ DCE and VC biodegradation in Twin Lakes and Pen Branch that is based solely on the observed accumulation of reduced daughter products may underestimate substantially the total extent of contaminant biodegradation and, thus, the contribution of biodegradation to overall contaminant attenuation. No evidence of abiotic degradation of [1,2-14C] DCE or [1,2-14C] VC was observed in heat-sterilized control treatments in this study under oxic or anoxic conditions. Efforts to enrich and isolate microorganisms involved in the mineralization of [1,2-14C] cis-DCE and/or [1,2-14C] VC were unsuccessful.

Performance of a Model Rich Burn-quick Mix-lean Burn Combustor at Elevated Temperature and Pressure

NASA Technical Reports Server (NTRS)

Peterson, Christopher O.; Sowa, William A.; Samuelsen, G. S.

2002-01-01

As interest in pollutant emission from stationary and aero-engine gas turbines increases, combustor engineers must consider various configurations. One configuration of increasing interest is the staged, rich burn - quick mix - lean burn (RQL) combustor. This report summarizes an investigation conducted in a recently developed high pressure gas turbine combustor facility. The model RQL combustor was plenum fed and modular in design. The fuel used for this study is Jet-A which was injected from a simplex atomizer. Emission (CO2, CO, O2, UHC, NOx) measurements were obtained using a stationary exit plane water-cooled probe and a traversing water-cooled probe which sampled from the rich zone exit and the lean zone entrance. The RQL combustor was operated at inlet temperatures ranging from 367 to 700 K, pressures ranging from 200 to 1000 kPa, and combustor reference velocities ranging from 10 to 20 m/s. Variations were also made in the rich zone and lean zone equivalence ratios. Several significant trends were observed. NOx production increased with reaction temperature, lean zone equivalence ratio and residence time and decreased with increased rich zone equivalence ratio. NOx production in the model RQL combustor increased to the 0.4 power with increased pressure. This correlation, compared to those obtained for non-staged combustors (0.5 to 0.7), suggests a reduced dependence on NOx on pressure for staged combustors. Emissions profiles suggest that rich zone mixing is not uniform and that the rich zone contributes on the order of 16 percent to the total NOx produced.

Rich catalytic injection

DOEpatents

Veninger, Albert [Coventry, CT

2008-12-30

A gas turbine engine includes a compressor, a rich catalytic injector, a combustor, and a turbine. The rich catalytic injector includes a rich catalytic device, a mixing zone, and an injection assembly. The injection assembly provides an interface between the mixing zone and the combustor. The injection assembly can inject diffusion fuel into the combustor, provides flame aerodynamic stabilization in the combustor, and may include an ignition device.

Combustion Dynamics in Multi-Nozzle Combustors Operating on High-Hydrogen Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santavicca, Dom; Lieuwen, Tim

Actual gas turbine combustors for power generation applications employ multi-nozzle combustor configurations. Researchers at Penn State and Georgia Tech have extended previous work on the flame response in single-nozzle combustors to the more realistic case of multi-nozzle combustors. Research at Georgia Tech has shown that asymmetry of both the flow field and the acoustic forcing can have a significant effect on flame response and that such behavior is important in multi-flame configurations. As a result, the structure of the flame and its response to forcing is three-dimensional. Research at Penn State has led to the development of a three-dimensional chemiluminescencemore » flame imaging technique that can be used to characterize the unforced (steady) and forced (unsteady) flame structure of multi-nozzle combustors. Important aspects of the flame response in multi-nozzle combustors which are being studied include flame-flame and flame-wall interactions. Research at Penn State using the recently developed three-dimensional flame imaging technique has shown that spatial variations in local flame confinement must be accounted for to accurately predict global flame response in a multi-nozzle can combustor.« less

CFD Analysis of Emissions for a Candidate N+3 Combustor

NASA Technical Reports Server (NTRS)

Ajmani, Kumud

2015-01-01

An effort was undertaken to analyze the performance of a model Lean-Direct Injection (LDI) combustor designed to meet emissions and performance goals for NASA's N+3 program. Computational predictions of Emissions Index (EINOx) and combustor exit temperature were obtained for operation at typical power conditions expected of a small-core, high pressure-ratio (greater than 50), high T3 inlet temperature (greater than 950K) N+3 combustor. Reacting-flow computations were performed with the National Combustion Code (NCC) for a model N+3 LDI combustor, which consisted of a nine-element LDI flame-tube derived from a previous generation (N+2) thirteen-element LDI design. A consistent approach to mesh-optimization, spraymodeling and kinetics-modeling was used, in order to leverage the lessons learned from previous N+2 flame-tube analysis with the NCC. The NCC predictions for the current, non-optimized N+3 combustor operating indicated a 74% increase in NOx emissions as compared to that of the emissions-optimized, parent N+2 LDI combustor.

CFD Analysis of Emissions for a Candidate N+3 Combustor

NASA Technical Reports Server (NTRS)

Ajmani, Kumud

2015-01-01

An effort was undertaken to analyze the performance of a model Lean-Direct Injection (LDI) combustor designed to meet emissions and performance goals for NASA's N+3 program. Computational predictions of Emissions Index (EINOx) and combustor exit temperature were obtained for operation at typical power conditions expected of a small-core, high pressure-ratio (greater than 50), high T3 inlet temperature (greater than 950K) N+3 combustor. Reacting-flow computations were performed with the National Combustion Code (NCC) for a model N+3 LDI combustor, which consisted of a nine-element LDI flame-tube derived from a previous generation (N+2) thirteen-element LDI design. A consistent approach to mesh-optimization, spray-modeling and kinetics-modeling was used, in order to leverage the lessons learned from previous N+2 flame-tube analysis with the NCC. The NCC predictions for the current, non-optimized N+3 combustor operating indicated a 74% increase in NOx emissions as compared to that of the emissions-optimized, parent N+2 LDI combustor.

Energy efficient engine pin fin and ceramic composite segmented liner combustor sector rig test report

NASA Technical Reports Server (NTRS)

Dubiel, D. J.; Lohmann, R. P.; Tanrikut, S.; Morris, P. M.

1986-01-01

Under the NASA-sponsored Energy Efficient Engine program, Pratt and Whitney has successfully completed a comprehensive test program using a 90-degree sector combustor rig that featured an advanced two-stage combustor with a succession of advanced segmented liners. Building on the successful characteristics of the first generation counter-parallel Finwall cooled segmented liner, design features of an improved performance metallic segmented liner were substantiated through representative high pressure and temperature testing in a combustor atmosphere. This second generation liner was substantially lighter and lower in cost than the predecessor configuration. The final test in this series provided an evaluation of ceramic composite liner segments in a representative combustor environment. It was demonstrated that the unique properties of ceramic composites, low density, high fracture toughness, and thermal fatigue resistance can be advantageously exploited in high temperature components. Overall, this Combustor Section Rig Test program has provided a firm basis for the design of advanced combustor liners.

Effects of broadened property fuels on radiant heat flux to gas turbine combustor liners

NASA Technical Reports Server (NTRS)

Haggard, J. B., Jr.

1983-01-01

The effects of fuel type, inlet air pressure, inlet air temperature, and fuel/air ratio on the combustor radiation were investigated. Combustor liner radiant heat flux measurements were made in the spectral region between 0.14 and 6.5 microns at three locations in a modified commercial aviation can combustor. Two fuels, Jet A and a heavier distillate research fuel called ERBS were used. The use of ERBS fuel as opposed to Jet A under similar operating conditions resulted in increased radiation to the combustor liner and hence increased backside liner temperature. This increased radiation resulted in liner temperature increases always less than 73 C. The increased radiation is shown by way of calculations to be the result of increased soot concentrations in the combustor. The increased liner temperatures indicated can substantially affect engine maintenance costs by reducing combustor liner life up to 1/3 because of the rapid decay in liner material properties when operated beyond their design conditions.

Effects of duration of vitamin C supplementation during the finishing period on postmortem protein degradation, tenderness, and meat color of the longissimus muscle of calf-fed steers consuming a 0.31 or 0.59% sulfur diet.

PubMed

Pogge, D J; Lonergan, S M; Hansen, S L

2015-05-01

High-S (HS) diets have been identified as a causative agent in the development of oxidative stress in cattle, which in postmortem muscle can negatively alter meat quality. Vitamin C (VC) is a potent antioxidant produced endogenously by cattle; however, exogenous supplementation of VC may be useful when HS diets are fed to cattle. The objective of this study was to examine the impact of duration of VC supplementation, for the first 56, 90, or 127 d, during the finishing period on meat color and tenderness of the longissimus thoracis (LT) collected from calf-fed steers consuming a 0.31 or 0.59% S diet. Angus steers ( n= 42) were stratified to pens by initial BW (304 ± 13 kg) and GeneMax marbling score (4.3 ± 0.12), and each pen was randomly assigned to 1 of 7 treatments (6 steers/pen, 1 pen/treatment), including HS (0.59% S, a combination of dried distillers grains plus solubles and sodium sulfate) control (HS CON), HS CON + 10 g VC·steer·(-1)d(-1) for the first 56 d (HS VC56), 90 d (HS VC90), or 127 d (HS VC127), low S (LS; 0.31% S) + 10 g VC·steer·(-1)d(-1) for the first 56 d (LS VC56), 90 d (LS VC90), or 127 d (LS VC127). Steers were harvested (n = 40) and, after a 24-h chill, rib sections (LT) were collected. pH was determined on each rib section before division into 3 sections for determination of 1) 7-d retail display and color and Warner-Bratzler shear force (WBSF), 2) 14-d WBSF determination, and 3) protein degradation and collagen content (2 d postmortem). Data were analyzed by ANOVA as a completely randomized design, with the fixed effect of treatment. Individual feed intake was recorded, and steer was the experimental unit. The HS steers had a greater and lesser percent of the 80- and 76-kDa subunits of calpain-1 (P ≤ 0.05), respectively, and tended to have less (P = 0.08) troponin T degradation (d2), and more (P = 0.02) collagen than LS steers. Increasing days of VC supplementation decreased (P = 0.05) the percentage of the 80 kDa subunit of calpain-1 in HS steers but actually increased it in LS steers (P= 0.003). Supplementing VC, regardless of dietary S, did not affect meat collagen, WBSF, or color (P ≥ 0.12). a* and b* values were greater (P ≤ 0.05) in the LS treatments compared to the HS treatments. Increasing the days of VC supplementation to steers fed a HS diet appears to alleviate the negative effects of the HS diet on calpain-1 but has no effect on muscle tenderness or meat color.

Experimental investigation of a reacting transverse jet in a high pressure oscillating vitiated crossflow

NASA Astrophysics Data System (ADS)

Fugger, Christopher A.

Staged combustion is one design approach in a gas turbine engine to reduce pollutant emission levels. In axially staged combustion, portions of the air and fuel are injected downstream of a lean premixed low NOx primary combustion zone. The gas residence time at elevated temperatures is decreased resulting in lower thermal NOx, and the reduced oxygen and high temperature vitiated primary zone flow further help to reduce pollutant emissions and quickly complete combustion. One implementation of axially staged combustion is transverse fuel jet injection. An important consideration for staged combustion systems, though, is how the primary and secondary combustion zones can couple through the acoustic resonances of the chamber. These couplings can lead to additional source terms that pump energy into the resonant acoustic field and help sustain the high-amplitude combustor pressure oscillations. An understanding of these couplings is important so that it may be possible to design a secondary combustion system that provides inherent damping to the combustor system. To systematically characterize the coupling of a reacting jet in unsteady crossflow in detail, the effects of an an unsteady pressure flowfield and an unsteady velocity flowfield are separately investigated. An optically accessible resonant combustion chamber was designed and built as part of this work to generate a standing wave unsteady vitiated crossflow at a chamber pressure of 0.9 MPa. The location of transverse jet injection corresponds to one of two locations, where one location is the pressure node and the other location the pressure anti-node of the resonant chamber acoustic mode. The injection location is optically accessible, and the dynamic interactions between the transverse jet flow and the 1st and 2nd axial combustor modes are measured using 10 kHz OH-PLIF and 2D PIV. This document analyzes five test cases: two non-reacting jets and three reacting jets. All cases correspond to jet injection near a pressure node of the 1st axial combustor mode, where the dominant flowfield fluctuations are a time-varying crossflow velocity. For the non-reacting jets, the nominal jet-to-crossflow momentum flux ratio is 19. For the reacting jets, the nominal jet-to-crossflow momentum flux ratio is 6. Two cross sectional planes parallel to the jet injection wall are investigated: 1 and 2.7 jet diameters from the jet injection wall. The combustor crossflow high frequency wall mounted pressure data is given for each test case. The velocity and OH-PLIF data is presented as instantaneous snapshots, time and phase averaged flowfields, modal decompositions using Proper Orthogonal Decomposition and Dynamic Mode Decomposition, and a jet cycle analysis relative to the crossflow acoustic cycle. Analysis of the five test cases shows that the jet cross sectional velocity and OH-PLIF dynamics display a multitude of dynamics. These are often organized into shear layer dynamics and wake dynamics, but are not mutually exclusive. For large unsteady crossflow velocity oscillations at the 1st axial combustor mode, both dynamics show strong organization at the unsteady crossflow frequency. Deciphering these dynamics is complicated by the fact that the ostensible jet response to the time-varying crossflow is a time-varying jet penetration. This drives the jet toward and away from the jet injection wall. These motions are perpendicular to the laser sheet and creates significant out-of-plane motions. The amplitude of crossflow unsteadiness appears to play a role in the sharpness of the wake dynamics. For the non-reacting cases, the wake dynamics are strong and dominant spectral features in the flowfield. For the reacting cases, the wake dynamics are spectrally distinct in the lower amplitude crossflow unsteadiness case, but a large unsteady amplitude crossflow appears to suppress the spectral bands in the frequency range corresponding to wake vortex dynamics.

Fuel properties effect on the performance of a small high temperature rise combustor

NASA Technical Reports Server (NTRS)

Acosta, Waldo A.; Beckel, Stephen A.

1989-01-01

The performance of an advanced small high temperature rise combustor was experimentally determined at NASA-Lewis. The combustor was designed to meet the requirements of advanced high temperature, high pressure ratio turboshaft engines. The combustor featured an advanced fuel injector and an advanced segmented liner design. The full size combustor was evaluated at power conditions ranging from idle to maximum power. The effect of broad fuel properties was studied by evaluating the combustor with three different fuels. The fuels used were JP-5, a blend of Diesel Fuel Marine/Home Heating Oil, and a blend of Suntec C/Home Heating Oil. The fuel properties effect on the performance of the combustion in terms of pattern factor, liner temperatures, and exhaust emissions are documented.

Performance of a small annular turbojet combustor designed for low cost

NASA Technical Reports Server (NTRS)

Fear, J. S.

1972-01-01

Performance investigations were conducted on a combustor utilizing several cost-reducing innovations and designed for use in a low-cost 4448-N thrust turbojet engine for commercial light aircraft. Low-cost features included simple, air-atomizing fuel injectors; combustor liners of perforated sheet; and the use of inexpensive type 304 stainless-steel material. Combustion efficiencies at the cruise and sea-level-takeoff design points were approximately 97 and 98 percent, respectively. The combustor isothermal pressure loss was 6.3 percent at the cruise-condition diffuser inlet Mach number of 0.34. The combustor exit temperature pattern factor was less than 0.24 at both the cruise and sea-level-takeoff design points. The combustor exit average radial temperature profiles at all conditions were in very good agreement with the design profile.

Real-Time Control of Lean Blowout in a Turbine Engine for Minimizing No(x) Emissions

NASA Technical Reports Server (NTRS)

Zinn, Ben

2004-01-01

This report describes research on the development and demonstration of a controlled combustor operates with minimal NO, emissions, thus meeting one of NASA s UEET program goals. NO(x) emissions have been successfully minimized by operating a premixed, lean burning combustor (modeling a lean prevaporized, premixed LPP combustor) safely near its lean blowout (LBO) limit over a range of operating conditions. This was accomplished by integrating the combustor with an LBO precursor sensor and closed-loop, rule-based control system that allowed the combustor to operate far closer to the point of LBO than an uncontrolled combustor would be allowed to in a current engine. Since leaner operation generally leads to lower NO, emissions, engine NO, was reduced without loss of safety.

Gas turbine combustor transition

DOEpatents

Coslow, Billy Joe; Whidden, Graydon Lane

1999-01-01

A method of converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit.

Gas turbine combustor transition

DOEpatents

Coslow, B.J.; Whidden, G.L.

1999-05-25

A method is described for converting a steam cooled transition to an air cooled transition in a gas turbine having a compressor in fluid communication with a combustor, a turbine section in fluid communication with the combustor, the transition disposed in a combustor shell and having a cooling circuit connecting a steam outlet and a steam inlet and wherein hot gas flows from the combustor through the transition and to the turbine section, includes forming an air outlet in the transition in fluid communication with the cooling circuit and providing for an air inlet in the transition in fluid communication with the cooling circuit. 7 figs.

A NEW LC-MS/MS METHOD FOR THE DETECTION AND QUANTIFICATION OF ENDOGENOUS AND VINYL CHLORIDE INDUCED 7-(2-0XOETHYL)GUANINE IN SPRAGUE DAWLEY MALE RATS

EPA Science Inventory

Vinyl chloride (VC) is an industrial chemical that is known to be carcinogenic to animals and humans. VC primarily induces hepatic angiosarcomas following high exposures (≥50 ppm). VC is also found in Superfund sites at ppb concentrations as a result of microbial metabolism of tr...

Exploring Online Learning at Primary Schools: Students' Perspectives on Cyber Home Learning System through Video Conferencing (CHLS-VC)

ERIC Educational Resources Information Center

Lee, June; Yoon, Seo Young; Lee, Chung Hyun

2013-01-01

The purposes of the study are to investigate CHLS (Cyber Home Learning System) in online video conferencing environment in primary school level and to explore the students' responses on CHLS-VC (Cyber Home Learning System through Video Conferencing) in order to explore the possibility of using CHLS-VC as a supportive online learning system. The…

Scalar and vector form factors of D →π (K )ℓν decays with Nf=2 +1 +1 twisted fermions

NASA Astrophysics Data System (ADS)

Lubicz, V.; Riggio, L.; Salerno, G.; Simula, S.; Tarantino, C.; ETM Collaboration

2017-09-01

We present a lattice determination of the vector and scalar form factors of the D →π ℓν and D →K ℓν semileptonic decays, which are relevant for the extraction of the CKM matrix elements |Vc d| and |Vc s| from experimental data. Our analysis is based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2 +1 +1 flavors of dynamical quarks, at three different values of the lattice spacing (a ≃0.062 ,0.082 ,0.089 fm ) and with pion masses as small as 210 MeV. Quark momenta are injected on the lattice using nonperiodic boundary conditions. The matrix elements of both vector and scalar currents are determined for plenty of kinematical conditions in which parent and child mesons are either moving or at rest. Lorentz symmetry breaking due to hypercubic effects is clearly observed in the data and included in the decomposition of the current matrix elements in terms of additional form factors. After the extrapolations to the physical pion mass and to the continuum limit, we determine the vector and scalar form factors in the whole kinematical region from q2=0 up to qmax2=(MD-Mπ (K ))2 accessible in the experiments, obtaining a good overall agreement with experiments, except in the region at high values of q2 where some deviations are visible. A set of synthetic data points, representing our results for f+Dπ (K )(q2) and f0D π (K )(q2) for several selected values of q2, is provided and also the corresponding covariance matrix is available. At zero four-momentum transfer, we get f+D→π(0 )=0.612 (35 ) and f+D→K(0 )=0.765 (31 ). Using the experimental averages for |Vc d|f+D→π(0 ) and |Vc s|f+D→K(0 ), we extract |Vc d|=0.2330 (137 ) and |Vc s|=0.945 (38 ), respectively. The second row of the CKM matrix is found to be in agreement with unitarity within the current uncertainties: |Vc d|2+|Vc s|2+|Vc b|2=0.949 (78 ).

Selected data fron continental scientific drilling core holes VC-1 and VC-2a, Valles Caldera, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musgrave, J.A.; Goff, F.; Shevenell, L.

1989-02-01

This report presents geochemical and isotopic data on rocks and water and wellbore geophysical data from the Continental Scientific Drilling Program core holes VC-1 and VC-2a, Valles Caldera, New Mexico. These core holes were drilled as a portion of a broader program that seeks to answer fundamental questions about magma, water/rock interactions, ore deposits, and volcanology. The data in this report will assist the interpretation of the hydrothermal system in the Jemez Mountains and will stimulate further research in magmatic processes, hydrothermal alteration, ore deposits, hydrology, structural geology, and hydrothermal solution chemistry. 37 refs., 36 figs., 28 tabs.

A Situation Awareness Assistant for Human Deep Space Exploration

NASA Technical Reports Server (NTRS)

Boy, Guy A.; Platt, Donald

2013-01-01

This paper presents the development and testing of a Virtual Camera (VC) system to improve astronaut and mission operations situation awareness while exploring other planetary bodies. In this embodiment, the VC is implemented using a tablet-based computer system to navigate through inter active database application. It is claimed that the advanced interaction media capability of the VC can improve situation awareness as the distribution of hu man space exploration roles change in deep space exploration. The VC is being developed and tested for usability and capability to improve situation awareness. Work completed thus far as well as what is needed to complete the project will be described. Planned testing will also be described.

Techniques for enhancing durability and equivalence ratio control in a rich-lean, three-stage ground power gas turbine combustor

NASA Technical Reports Server (NTRS)

Schultz, D. F.

1982-01-01

Rig tests of a can-type combustor were performed to demonstrate two advanced ground power engine combustor concepts: steam cooled rich-burn combustor primary zones for enhanced durability; and variable combustor geometry for three stage combustion equivalence ratio control. Both concepts proved to be highly successful in achieving their desired objectives. The steam cooling reduced peak liner temperatures to less than 800 K. This offers the potential of both long life and reduced use of strategic materials for liner fabrication. Three degrees of variable geometry were successfully implemented to control airflow distribution within the combustor. One was a variable blade angle axial flow air swirler to control primary airflow while the other two consisted of rotating bands to control secondary and tertiary or dilution air flow.

Parametric study of flame radiation characteristics of a tubular-can combustor

NASA Technical Reports Server (NTRS)

Humenik, F. M.; Claus, R. W.; Neely, G. M.

1983-01-01

A series of combustor tests were conducted with a tubular-can combustor to study flame radiation characteristics and effects with parametric variations in combustor operating conditions. Two alternate combustor assemblies using a different fuel nozzle were compared. Spectral and total radiation detectors were positioned at three stations along the length of the combustor can. Data were obtained for a range of pressures from 0.34 to 2.07 MPa (50 to 300 psia), inlet temperatures from 533 to 700K (500 to 800 F), for Jet A (13.9 deg hydrogen) and ERBS (12.9% hydrogen) fuels, and with fuel-air ratios nominally from 0.008 to 0.021. Spectral radiation data, total radiant heat flux data, and liner temperature data are presented to illustrate the flame radiation characteristics and effects in the primary, secondary, and tertiary combustion zones.

Combustor air flow control method for fuel cell apparatus

DOEpatents

Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

2001-01-01

A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

NASA Broad Specification Fuels Combustion Technology program - Pratt and Whitney Aircraft Phase I results and status

NASA Technical Reports Server (NTRS)

Lohmann, R. P.; Fear, J. S.

1982-01-01

In connection with increases in the cost of fuels and the reduced availability of high quality petroleum crude, a modification of fuel specifications has been considered to allow acceptance of poorer quality fuels. To obtain the information upon which a selection of appropriate fuels for aircraft can be based, the Broad Specification Fuels Combustion Technology program was formulated by NASA. A description is presented of program-related investigations conducted by an American aerospace company. The specific objective of Phase I of this program has been to evaluate the impact of the use of broadened properties fuels on combustor design through comprehensive combustor rig testing. Attention is given to combustor concepts, experimental evaluation, results obtained with single stage combustors, the stage combustor concept, and the capability of a variable geometry combustor.

NASA/General Electric broad-specification fuels combustion technology program - Phase I results and status

NASA Technical Reports Server (NTRS)

Dodds, W. J.; Ekstedt, E. E.; Bahr, D. W.; Fear, J. S.

1982-01-01

A program is being conducted to develop the technology required to utilize fuels with broadened properties in aircraft gas turbine engines. The first phase of this program consisted of the experimental evaluation of three different combustor concepts to determine their potential for meeting several specific emissions and performance goals, when operated on broadened property fuels. The three concepts were a single annular combustor; a double annular combustor; and a short single annular combustor with variable geometry. All of these concepts were sized for the General Electric CF6-80 engine. A total of 24 different configurations of these concepts were evaluated in a high pressure test facility, using four test fuels having hydrogen contents between 11.8 and 14%. Fuel effects on combustor performance, durability and emissions, and combustor design features to offset these effects were demonstrated.

Alternate-Fueled Combustor-Sector Performance. Parts A and B; (A) Combustor Performance; (B) Combustor Emissions

NASA Technical Reports Server (NTRS)

Shouse, D. T.; Hendricks, R. C.; Lynch, A.; Frayne, C. W.; Stutrud, J. S.; Corporan, E.; Hankins, T.

2012-01-01

Alternate aviation fuels for military or commercial use are required to satisfy MIL-DTL-83133F(2008) or ASTM D 7566 (2010) standards, respectively, and are classified as "drop-in" fuel replacements. To satisfy legacy issues, blends to 50% alternate fuel with petroleum fuels are certified individually on the basis of processing and assumed to be feedstock agnostic. Adherence to alternate fuels and fuel blends requires "smart fueling systems" or advanced fuel-flexible systems, including combustors and engines, without significant sacrifice in performance or emissions requirements. This paper provides preliminary performance (Part A) and emissions and particulates (Part B) combustor sector data. The data are for nominal inlet conditions at 225 psia and 800 F (1.551 MPa and 700 K), for synthetic-paraffinic-kerosene- (SPK-) type (Fisher-Tropsch (FT)) fuel and blends with JP-8+100 relative to JP-8+100 as baseline fueling. Assessments are made of the change in combustor efficiency, wall temperatures, emissions, and luminosity with SPK of 0%, 50%, and 100% fueling composition at 3% combustor pressure drop. The performance results (Part A) indicate no quantifiable differences in combustor efficiency, a general trend to lower liner and higher core flow temperatures with increased FT fuel blends. In general, emissions data (Part B) show little differences, but with percent increase in FT-SPK-type fueling, particulate emissions and wall temperatures are less than with baseline JP-8. High-speed photography illustrates both luminosity and combustor dynamic flame characteristics.

NOx Emissions Characteristics and Correlation Equations of Two P and W's Axially Staged Sector Combustors Developed Under NASA Environmentally Responsible Aviation (ERA) Project

NASA Technical Reports Server (NTRS)

He, Zhuohui J.

2017-01-01

Two P&W (Pratt & Whitney)'s axially staged sector combustors have been developed under NASA's Environmentally Responsible Aviation (ERA) project. One combustor was developed under ERA Phase I, and the other was developed under ERA Phase II. Nitrogen oxides (NOx) emissions characteristics and correlation equations for these two sector combustors are reported in this article. The Phase I design was to optimize the NOx emissions reduction potential, while the Phase II design was more practical and robust. Multiple injection points and fuel staging strategies are used in the combustor design. Pilot-stage injectors are located on the front dome plate of the combustor, and main-stage injectors are positioned on the top and bottom (Phase I) or on the top only (Phase II) of the combustor liners downstream. Low power configuration uses only pilot-stage injectors. Main-stage injectors are added to high power configuration to help distribute fuel more evenly and achieve lean burn throughout the combustor yielding very low NOx emissions. The ICAO (International Civil Aviation Organization) landing-takeoff NOx emissions are verified to be 88 percent (Phase I) and 76 percent (Phase II) under the ICAO CAEP/6 (Committee on Aviation Environmental Protection 6th Meeting) standard, exceeding the ERA project goal of 75 percent reduction, and the combustors proved to have stable combustion with room to maneuver on fuel flow splits for operability.

Molecular dynamics coupled with a virtual system for effective conformational sampling.

PubMed

Hayami, Tomonori; Kasahara, Kota; Nakamura, Haruki; Higo, Junichi

2018-07-15

An enhanced conformational sampling method is proposed: virtual-system coupled canonical molecular dynamics (VcMD). Although VcMD enhances sampling along a reaction coordinate, this method is free from estimation of a canonical distribution function along the reaction coordinate. This method introduces a virtual system that does not necessarily obey a physical law. To enhance sampling the virtual system couples with a molecular system to be studied. Resultant snapshots produce a canonical ensemble. This method was applied to a system consisting of two short peptides in an explicit solvent. Conventional molecular dynamics simulation, which is ten times longer than VcMD, was performed along with adaptive umbrella sampling. Free-energy landscapes computed from the three simulations mutually converged well. The VcMD provided quicker association/dissociation motions of peptides than the conventional molecular dynamics did. The VcMD method is applicable to various complicated systems because of its methodological simplicity. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Biodegradation of trichloroethylene and its anaerobic daughter products in freshwater wetland sediments

USGS Publications Warehouse

Lorah, M.M.; Olsen, L.D.

2001-01-01

Laboratory microcosms were prepared under methanogenic, sulfate-reducing, and aerobic conditions using sediment and groundwater from a freshwater wetland that is a discharge area for a trichloroethylene (TCE) to evaluate potential biodegradation rates of TCE and its anaerobic daughter products (cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, and vinyl chloride (VC)). Anaerobic degradation of TCE was about an order of magnitude faster under methanogenic conditions than under sulfate-reducing conditions. Both 12DCE and VC were found under sulfate-reducing conditions in the microcosms containing the wetland sediment, but their production, especially for VC, was substantially slower than under methanogenic conditions. Methane concentrations remained approximately constant (when losses in the formalin-amended controls are considered) in the microcosms amended with TCE and increased in the microcosms amended with the 12DCE isomers and VC during the first 18-25 days of incubation. The most rapid decrease in concentrations of TCE, cis-12DCE, trans-12DCE, and VC was found after aerobic methane-oxidizing conditions were definitely established.

Barriers and Opportunities to Advancing Women in Leadership Roles in Vector Control: Perspectives from a Stakeholder Survey.

PubMed

Hayden, Mary H; Barrett, Erika; Bernard, Guyah; Toko, Eunice N; Agawo, Maurice; Okello, Amanda M; Gunn, Jayleen K L; Ernst, Kacey C

2018-05-01

Increasing the active participation of professional women in vector control (VC) activities may help promote greater gender equity in the workplace and reduce the burden of vector-borne diseases. This stakeholder survey examined the current roles and perspective of professionals employed in the VC sector in Kenya, Indonesia, India, and other countries. The largest barriers that women face in pursuing leadership roles in the VC sector include lack of awareness of career opportunities, limitations based on cultural norms, and the belief that VC is men's work. These barriers could be addressed through improving education and recruitment campaigns, as well as supporting higher education and mentoring programs. Females were almost six times more likely to be encouraged to pursue leadership positions in their organization compared with male respondents (odds ratio = 5.9, P > 0.03, 95% confidence interval: 1.19, 29.42). These findings suggest that once women are recruited into the VC workforce, they face minimal discrimination and have increased leadership opportunities.

Performance and Pollution Measurements of Two-Row Swirl-Can Combustor Having 72 Modules

NASA Technical Reports Server (NTRS)

Biaglow, James A.; Trout, Arthur M.

1975-01-01

A test program was conducted to evaluate the performance and gaseous-pollutant levels of an experimental full-annulus 72-module swirl-can combustor. A comparison of data with those for a 120-module swirl-can combustor showed no significant difference in performance or levels of gaseous pollutants. Oxides of nitrogen were correlated for the 72- and 120-swirl-can combustors by using a previously developed parameter.

Low NOx Fuel Flexible Combustor Integration Project Overview

NASA Technical Reports Server (NTRS)

Walton, Joanne C.; Chang, Clarence T.; Lee, Chi-Ming; Kramer, Stephen

2015-01-01

The Integrated Technology Demonstration (ITD) 40A Low NOx Fuel Flexible Combustor Integration development is being conducted as part of the NASA Environmentally Responsible Aviation (ERA) Project. Phase 2 of this effort began in 2012 and will end in 2015. This document describes the ERA goals, how the fuel flexible combustor integration development fulfills the ERA combustor goals, and outlines the work to be conducted during project execution.

Results and status of the NASA aircraft engine emission reduction technology programs

NASA Technical Reports Server (NTRS)

Jones, R. E.; Diehl, L. A.; Petrash, D. A.; Grobman, J.

1978-01-01

The results of an aircraft engine emission reduction study are reviewed in detail. The capability of combustor concepts to produce significantly lower levels of exhaust emissions than present production combustors was evaluated. The development status of each combustor concept is discussed relative to its potential for implementation in aircraft engines. Also, the ability of these combustor concepts to achieve proposed NME and NCE EPA standards is discussed.

Low NOx Heavy Fuel Combustor Concept Program

NASA Technical Reports Server (NTRS)

Novick, A. S.; Troth, D. L.

1981-01-01

The development of the technology required to operate an industrial gas turbine combustion system on minimally processed, heavy petroleum or residual fuels having high levels of fuel-bound nitrogen (FBN) while producing acceptable levels of exhaust emissions is discussed. Three combustor concepts were designed and fabricated. Three fuels were supplied for the combustor test demonstrations: a typical middle distillate fuel, a heavy residual fuel, and a synthetic coal-derived fuel. The primary concept was an air staged, variable-geometry combustor designed to produce low emissions from fuels having high levels of FBN. This combustor used a long residence time, fuel-rich primary combustion zone followed by a quick-quench air mixer to rapidly dilute the fuel rich products for the fuel-lean final burnout of the fuel. This combustor, called the rich quench lean (RQL) combustor, was extensively tested using each fuel over the entire power range of the model 570 K engine. Also, a series of parameteric tests was conducted to determine the combustor's sensitivity to rich-zone equivalence ratio, lean-zone equivalence ratio, rich-zone residence time, and overall system pressure drop. Minimum nitrogen oxide emissions were measured at 50 to 55 ppmv at maximum continuous power for all three fuels. Smoke was less than a 10 SAE smoke number.

Cyclone reactor with internal separation and axial recirculation

DOEpatents

Becker, F.E.; Smolensky, L.A.

1988-07-19

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture is described. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combustor chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture may be tangentially withdrawn from the outlet end and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture. 10 figs.

Cyclone reactor with internal separation and axial recirculation

DOEpatents

Becker, Frederick E.; Smolensky, Leo A.

1989-01-01

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combuston chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture of flue gas and ash may be tangentially withdrawn from the outlet end of the combustor chamber and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture.

Influence of harvest residues and vegetation on microsite soil and air temperatures in a young conifer plantation.

Treesearch

W.D. Devine; C.A. Harrington

2007-01-01

This study examines the effects of bole-only harvesting with and without vegetation control (BO+VC; BO-VC) and total-tree harvesting plus removal of legacy woody debris with vegetation control (TTP+VC) on microsite soil and air temperatures in a young Douglas-fir plantation. Mean soil temperature and the diurnal range in soil temperature during the growing season...

Short-term effect of volume recruitment-derecruitment manoeuvre on chest-wall motion in Duchenne muscular dystrophy.

PubMed

Meric, Henri; Falaize, Line; Pradon, Didier; Lacombe, Matthieu; Petitjean, Michel; Orlikowski, David; Prigent, Hélène; Lofaso, Frédéric

2017-05-01

Because progressive respiratory muscle weakness leads to decreased chest-wall motion with eventual ribcage stiffening, the purpose was to compare vital capacity (VC) and contributions of chest-wall compartments before and after volume recruitment-derecruitment manoeuvres (VRDM) in Duchenne muscular dystrophy (DMD). We studied nine patients with DMD and VC lower than 30% of predicted. VRDM was performed using 15 insufflations-exsufflations of +30 to -30 cmH 2 O. VC and three-dimensional chest-wall motion were measured, as well as oxygen saturation, transcutaneous partial pressure of carbon dioxide and the rapid shallow breathing index (respiratory rate/tidal volume) before (baseline) and immediately and 1 hour after VRDM. VC increased significantly immediately after VRDM (108% ± 7% of baseline, p = 0.018) but returned to baseline within 1 hour, and the rapid shallow breathing index increased significantly. The non-dominant side systematically increased immediately after VRDM ( p = 0.0077), and in the six patients with abnormal breathing asymmetry (difference >10% of VC) at baseline, this asymmetry was corrected immediately and/or 1 hour after VRDM. VRDM improved VC and reduced chest-wall motion asymmetry, but this beneficial effect waned rapidly with respiratory muscle fatigue, suggesting that VRDM may need to be repeated during the day to produce lasting benefits.

Multifactor analysis and simulation of the surface runoff and soil infiltration at different slope gradients

NASA Astrophysics Data System (ADS)

Huang, J.; Kang, Q.; Yang, J. X.; Jin, P. W.

2017-08-01

The surface runoff and soil infiltration exert significant influence on soil erosion. The effects of slope gradient/length (SG/SL), individual rainfall amount/intensity (IRA/IRI), vegetation cover (VC) and antecedent soil moisture (ASM) on the runoff depth (RD) and soil infiltration (INF) were evaluated in a series of natural rainfall experiments in the South of China. RD is found to correlate positively with IRA, IRI, and ASM factors and negatively with SG and VC. RD decreased followed by its increase with SG and ASM, it increased with a further decrease with SL, exhibited a linear growth with IRA and IRI, and exponential drop with VC. Meanwhile, INF exhibits a positive correlation with SL, IRA and IRI and VC, and a negative one with SG and ASM. INF was going up and then down with SG, linearly rising with SL, IRA and IRI, increasing by a logit function with VC, and linearly falling with ASM. The VC level above 60% can effectively lower the surface runoff and significantly enhance soil infiltration. Two RD and INF prediction models, accounting for the above six factors, were constructed using the multiple nonlinear regression method. The verification of those models disclosed a high Nash-Sutcliffe coefficient and low root-mean-square error, demonstrating good predictability of both models.

Delivering patient education by group videoconferencing into the home: Lessons learnt from the Telehealth Literacy Project.

PubMed

Banbury, Annie; Parkinson, Lynne; Nancarrow, Susan; Dart, Jared; Gray, Leonard C; Buckley, Jennene

2016-12-01

We examined the procedures for implementing group videoconference (VC) education for older people delivered into the home environment to identify the most common themes affecting the optimum delivery of VC home-based groups to older people. Participants (n = 52) were involved in a six-week group VC patient education program. There were a total of 44 sessions, undertaken by nine groups, with an average of four participants (range 1-7) and the facilitator. Participants could see and hear each other in real-time whilst in their homes with customised tablets or a desktop computer. The data presented here are based on a program log maintained by the facilitator throughout the implementation phase of the project and post intervention. The VC group experience is influenced by factors including the VC device location, connection processes, meeting times, use of visual aids and test calls. Social presence can be improved by communication protocols and strategies. Robust information technology (IT) support is essential in mitigating technical problems to enhance users' experience. Group patient education can be delivered by VC into homes of older people. However, careful pre-program planning, training and support should be considered when implementing such programs. © The Author(s) 2016.

Effects of vegetation cover of natural grassland on runoff and sediment yield in loess hilly region of China.

PubMed

Zhao, Xining; Chen, Xiaoli; Huang, Jun; Wu, Pute; Helmers, Matthew J

2014-02-01

The effects of vegetation cover (VC) on runoff and sediment yield were investigated from rainfall simulation experiments in the Loess Plateau of China. Five VCs from 0% to 80% and three different rainfall intensities (I₂.₀, ₁.₅, ₀.₇₅) were implemented. The results indicated that runoff and sediment yields in slopes were significantly affected by I and VC, and when the VC amounted to 40% there occurred obvious benefits of runoff and sediment reductions and then amplitude decreased with the increase of VC. The runoff reduction benefits at I₁.₅ and I₀.₇₅ were much greater than that at I₂.₀, while the sediment reduction benefits had no significant difference among different rainfall intensities. At I₂.₀, the natural grassland slopes with high VC exhibited the characteristics of high runoff but low sediment production. There existed a power function relationship between cumulative runoff and sediment yield. The increase in cumulative sediment yield was less than the increase in cumulative runoff with increasing VC, and the sediment reduction benefit was greater than runoff reduction on natural grassland slopes. The ratio of runoff reduction to sediment reduction can be used as a comprehensive index for assessing the benefits of runoff and sediment reduction in natural grassland. © 2013 Society of Chemical Industry.

Microscopic aspects of autoschizic cell death in human ovarian carcinoma (2774) cells following vitamin C, vitamin K3 or vitamin C:K3 treatment.

PubMed

Gilloteaux, Jacques; Jamison, James M; Arnold, David; Taper, Henryk S; Von Gruenigen, Vivian E; Summers, Jack L

2003-08-01

Human ovarian carcinoma cells (MDAH 2774) were treated with sodium ascorbate (VC), menadione (VK3), or with a VC:VK3 combination for 1 h and then studied using light microscopy (LM) and scanning (SEM) and transmission electron (TEM) microscopy. Plasma membrane damage (blisters and blebs, hairy aspect) results from vitamin C (VC) treatment, while cytoskeletal damage and self-morsellation are caused by vitamin K3 (VK3) treatment. VC:VK3-treated cells exhibit exacerbated injuries characteristic of both VC and VK3 treatment as well as a significant decrease in cell diameters from 20-35 microm for control cells to 7-12 microm for VC:VK3 treatment. Moreover, after a 1-h exposure to the vitamin combination, autoschizis (43%), apoptosis (3%), and oncosis (1.9%) are observed at the percentages indicated. All cellular changes associated with autoschizis observed with SEM were confirmed by LM and TEM observations and are consistent with cell death by autoschizis: decrease in cell size, cytoplasmic self-excisions, degradation of the nucleus and nucleolus without formation of apoptotic bodies and, ultimately, karyorrhexis and karyolysis. These results also suggest that the vitamin combination may find clinical use in the treatment of ovarian cancer.

Microscopic Aspects of Autoschizic Cell Death in Human Ovarian Carcinoma (2774) Cells Following Vitamin C, Vitamin K3 or Vitamin C:K3 Treatment

NASA Astrophysics Data System (ADS)

Gilloteaux, Jacques; Jamison, James M.; Arnold, David; Taper, Henryk S.; von Gruenigen, Vivian E.; Summers, Jack L.

2003-08-01

Human ovarian carcinoma cells (MDAH 2774) were treated with sodium ascorbate (VC), menadione (VK3), or with a VC:VK3 combination for 1 h and then studied using light microscopy (LM) and scanning (SEM) and transmission electron (TEM) microscopy. Plasma membrane damage (blisters and blebs, hairy aspect) results from vitamin C (VC) treatment, while cytoskeletal damage and self-morsellation are caused by vitamin K3 (VK3) treatment. VC:VK3-treated cells exhibit exacerbated injuries characteristic of both VC and VK3 treatment as well as a significant decrease in cell diameters from 20 35 [mu]m for control cells to 7 12 [mu]m for VC:VK3 treatment. Moreover, after a 1-h exposure to the vitamin combination, autoschizis (43%), apoptosis (3%), and oncosis (1.9%) are observed at the percentages indicated. All cellular changes associated with autoschizis observed with SEM were confirmed by LM and TEM observations and are consistent with cell death by autoschizis: decrease in cell size, cytoplasmic self-excisions, degradation of the nucleus and nucleolus without formation of apoptotic bodies and, ultimately, karyorrhexis and karyolysis. These results also suggest that the vitamin combination may find clinical use in the treatment of ovarian cancer.

Effect of Fe(III) on 1,1,2,2-tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the Aberdeen proving ground

USGS Publications Warehouse

Jones, E.J.P.; Voytek, M.A.; Lorah, M.M.

2004-01-01

1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek, MD, where dechlorination occurred. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways led to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The effect of adding Fe(III) to TeCA-amended microcosms of wetland sediment was studied. Differences were identified in the TeCA degradation pathway between microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated microcosms than no AFO microcosms. The microcosm incubations and subsequent experiments with the microcosm materials showed that AFO treatment resulted in lower production of VC by shifting TeCA degradation from dichloroelimination pathways to production of a greater proportion of chlorinated ethane products, and decreasing the microbial capability to produce VC from 1,2-dichloroethylene. VC degradation was not stimulated in the presence of Fe(III). Rather, VC degradation occurred readily under methanogenic conditions and was inhibited under Fe(III)-reducing conditions.

Predictive models and spatial variations of vital capacity in healthy people from 6 to 84 years old in China based on geographical factors.

PubMed

He, Jinwei; Ge, Miao; Wang, Congxia; Jiang, Naigui; Zhang, Mingxin; Yun, Pujun

2014-07-01

The aim of this study was to provide a scientific basic for a unified standard of the reference value of vital capacity (VC) of healthy subjects from 6 and 84 years old in China. The normal reference value of VC was correlated to seven geographical factors, including altitude (X1), annual duration of sunshine (X2), annual mean air temperature (X3), annual mean relative humidity (X4), annual precipitation amount (X5), annual air temperature range (X6) and annual mean wind speed (X7). Predictive models were established by five different linear and nonlinear methods. The best models were selected by t-test. The geographical distribution map of VC in different age groups can be interpolated by Kriging's method using ArcGIS software. It was found that the correlation of VC and geographical factors in China was quite significant, especially for both males and females aged from 6 to 45. The best models were built for different age groups. The geographical distribution map shows the spatial variations of VC in China precisely. The VC of healthy subjects can be simulated by the best model or acquired from the geographical distribution map provided the geographical factors for that city or county of China are known.

High-temperature combustor liner tests in structural component response test facility

NASA Technical Reports Server (NTRS)

Moorhead, Paul E.

1988-01-01

Jet engine combustor liners were tested in the structural component response facility at NASA Lewis. In this facility combustor liners were thermally cycled to simulate a flight envelope of takeoff, cruise, and return to idle. Temperatures were measured with both thermocouples and an infrared thermal imaging system. A conventional stacked-ring louvered combustor liner developed a crack at 1603 cycles. This test was discontinued after 1728 cycles because of distortion of the liner. A segmented or float wall combustor liner tested at the same heat flux showed no significant change after 1600 cycles. Changes are being made in the facility to allow higher temperatures.

Effect of ambient temperature and humidity on emissions of an idling gas turbine

NASA Technical Reports Server (NTRS)

Kauffman, C. W.

1977-01-01

The effects of inlet pressure, temperature, and humidity on the oxides of nitrogen produced by an engine operating at takeoff power setting were investigated and numerous correction factors were formulated. The effect of ambient relative humidity on gas turbine idle emissions was ascertained. Experimentally, a nonvitiating combustor rig was employed to simulate changing combustor inlet conditions as generated by changing ambient conditions. Emissions measurements were made at the combustor exit. For carbon monoxide, a reaction kinetic scheme was applied within each zone of the combustor where initial species concentrations reflected not only local combustor characteristics but also changing ambient conditions.

Preliminary investigation of the performance of a single tubular combustor at pressure up to 12 atmospheres

NASA Technical Reports Server (NTRS)

Wear, Jerrold D; Butze, Helmut F

1954-01-01

The effects of combustor operation at conditions representative of those encountered in high pressure-ratio turbojet engines or at high flight speeds on carbon deposition, exhaust smoke, and combustion efficiency were studied in a single tubular combustor. Carbon deposition and smoke formation tests were conducted over a range of combustor-inlet pressures from 33 to 173 pounds per square inch absolute and combustor reference velocities from 78 to 143 feet per second. Combustion efficiency tests were conducted over a range of pressures from 58 to 117 pounds per square inch absolute and velocities from 89 to 172 feet per second.

A Combustion Research Facility for Testing Advanced Materials for Space Applications

NASA Technical Reports Server (NTRS)

Bur, Michael J.

2003-01-01

The test facility presented herein uses a groundbased rocket combustor to test the durability of new ceramic composite and metallic materials in a rocket engine thermal environment. A gaseous H2/02 rocket combustor (essentially a ground-based rocket engine) is used to generate a high temperature/high heat flux environment to which advanced ceramic and/or metallic materials are exposed. These materials can either be an integral part of the combustor (nozzle, thrust chamber etc) or can be mounted downstream of the combustor in the combustor exhaust plume. The test materials can be uncooled, water cooled or cooled with gaseous hydrogen.

Combustor concepts for aircraft gas turbine low-power emissions reduction

NASA Technical Reports Server (NTRS)

Mularz, E. J.; Gleason, C. C.; Dodds, W. J.

1978-01-01

Several combustor concepts were designed and tested to demonstrate significant reductions in aircraft engine idle pollutant emissions. Each concept used a different approach for pollutant reductions: the hot wall combustor employs a thermal barrier coating and impingement cooled liners; the recuperative cooling combustor preheats the air before entering the combustion chamber; and the catalytic converter combustor is composed of a conventional primary zone followed by a catalytic bed for pollutant cleanup. The designs are discussed in detail and test results are presented for a range of aircraft engine idle conditions. The results indicate that ultralow levels of unburned hydrocarbons and carbon monoxide emissions can be achieved.

Evaluation of agglutination strength by a flow-induced cell movement assay based surface plasmon resonance (SPR) technique.

PubMed

Sudprasert, Krisda; Peungthum, Patjaree; Vongsakulyanon, Apirom; Amarit, Ratthasart; Somboonkaew, Armote; Sutapun, Boonsong; Kitpoka, Pimpun; Kunakorn, Mongkol; Srikhirin, Toemsak

2015-02-07

A flow-induced cell movement assay combined with a surface plasmon resonance (SPR) technique was developed to quantify the agglutination strength, derived from the standard tube-agglutination test. Red blood cells (RBCs), based on the ABO blood group system, were specifically captured by anti-A and/or anti-B antibodies immobilized on a sensor surface. The agglutination strength corresponds to the amount of antigen-antibody interactions or the strength of RBC adhesion. Under a shear flow, the adherent RBCs were forced to move out of the region of interest with different average cell velocities (vc) depending upon the adhesion strength and wall shear stress (WSS). That is, a higher adhesion strength (higher agglutination strength) or lower WSS represents a lower vc or vice versa. In this work, the agglutination strength was derived from the vc that was calculated from the time derivative of the relative SPR signal by using a simple model of cell movement response, whose validity was verified. The vc values of different samples were correlated with their agglutination strengths at a given WSS and antibody surface density. The vc decreased as the agglutination strength increased, which can be considered as a linear regression. The coefficient of variation of the calculated vc decreased to 0.1 as vc increased to 30 μm min(-1). The sensitivity of this assay can be controlled by optimizing the antibody surface density or the WSS. This assay has the capability to resolve the antigen density of A1 and B RBCs from that of A1B RBCs.

True morphology of mitral regurgitant flow assessed by three-dimensional transesophageal echocardiography.

PubMed

Lombardero, Martin; Henquin, Ruth; Perea, Gabriel; Corneli, Mariana; Izurieta, Carlos

2017-01-01

Quantification of mitral regurgitation (MR) by two-dimensional (2D) transthoracic echocardiography (TTE) is based on the analysis of the proximal flow convergence (PFC) and the "vena contracta" (VC). This method assumes geometries and can be misleading. In contrast, three-dimensional (3D) echocardiography directly measures flow volumes and does not assume geometries, which allows for more accurate MR evaluation. To report the 3D transesophageal echocardiography (3DTEE) feasibility for MR quantification and evaluate its concordance with 2D echo. Twenty-seven consecutive patients undergoing 2D and 3DTEE for presurgical MR evaluation were studied prospectively. MR quantification was performed by classical 2D methods based on PFC. Diameters of the VC in orthogonal planes by 3DTEE were estimated, establishing the VC sphericity index as well as VC area (VCA) by direct planimetry. In case of multiple jets, we calculated the sum of the VCA. MR assessment by 3DTEE was feasible. An adequate concordance between VC measurements by 2D methods (TTE and TEE) was observed; however, there was a poor correlation when compared with 3DTEE. The sphericity index of the VC was: 2.08 (±0. 72), reflecting a noncircular VC. 3DTEE is a feasible method for the assessment of the MR true morphology, allowing a better quantification of MR without assuming any geometry. This method revealed the presence of multiple jets, potentially improving MR evaluation and leading to changes in medical decision when compared to 2D echo assessment. © 2016, Wiley Periodicals, Inc.

Systematic review and meta-analysis for the association of bone mineral density and osteoporosis/osteopenia with vascular calcification in women.

PubMed

Zhang, Yiyun; Feng, Bo

2017-02-01

The relationships of osteoporosis/osteopenia and bone mineral density (BMD) with vascular calcification (VC) remain controversial. Thus, we performed this systematic review and meta-analysis to evaluate the association between BMD, osteoporosis/osteopenia risk and VC. PubMed, Embase and Springer databases were searched from inception to March, 2015 for studies involving the association of vascular calcification with BMD and osteopenia/osteoporosis in women. A manual search of the references cited in the publications was also employed for more relevant studies. The heterogeneity was assessed using Cochran's Q statistic and I 2 test. Weighted mean difference (WMD) or odds ratio (OR) and 95% confidence interval (CI) in the VC group and control group were appropriately pooled. Four studies were enrolled in the meta-analysis. The pooled effects indicated that the spine BMD (WMD = -0.08, 95% CI: -0.11 to -0.06) and hip BMD (WMD = -0.06, 95% CI: -0.10 to -0.07) in VC group were significantly lower than those in control group, respectively. Moreover, patients with VC were prone to develop osteoporosis (OR = 4.39, 95% CI: 2.82-6.83) and osteopenia (OR = 1.72, 95% CI: 1.14-2.60). The results suggest that patients with VC have lower lumbar spine and hip BMD levels and increased risk for developing osteoporosis/osteopenia. Thus, VC patients should be evaluated for the presence of osteoporosis/osteopenia, as well as susceptibility to fractures. © 2016 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

NASA Project Develops Next-Generation Low-Emissions Combustor Technologies

NASA Technical Reports Server (NTRS)

Lee, Chi-Ming; Chang, Clarence T.; Herbon, John T.; Kramer, Stephen K.

2013-01-01

NASA's Environmentally Responsible Aviation (ERA) Project is working with industry to develop the fuel flexible combustor technologies for a new generation of low-emissions engine targeted for the 2020 timeframe. These new combustors will reduce nitrogen oxide (NOx) emissions to half of current state-of-the-art (SOA) combustors, while simultaneously reducing noise and fuel burn. The purpose of the low NOx fuel-flexible combustor research is to advance the Technology Readiness Level (TRL) and Integration Readiness Level (IRL) of a low NOx, fuel flexible combustor to the point where it can be integrated in the next generation of aircraft. To reduce project risk and optimize research benefit NASA chose to found two Phase 1 contracts. The first Phase 1 contracts went to engine manufactures and were awarded to: General Electric Company, and Pratt & Whitney Company. The second Phase 1 contracts went to fuel injector manufactures Goodrich Corporation, Parker Hannifin Corporation, and Woodward Fuel System Technology. In 2012, two sector combustors were tested at NASA's ASCR. The results indicated 75% NOx emission reduction below the 2004 CAEP/6 regulation level.

Association between vascular calcification assessed by simple radiography and non-fatal cardiovascular events in hemodialysis patients.

PubMed

Petrauskiene, Vaida; Vaiciuniene, Ruta; Bumblyte, Inga Arune; Kuzminskis, Vytautas; Ziginskiene, Edita; Grazulis, Saulius; Jonaitiene, Egle

2016-12-01

Vascular calcification (VC) is one of the factors associated with cardiovascular mortality in hemodialysis (HD) patients. Recommendations concerning screening for VC differ. Possible ability to prevent and reversibility of VC are major subjects on debate whether screening for VC could improve outcomes of renal patients. The objective of the study was to evaluate the significance of simple vascular calcification score (SVCS) based on plane radiographic films and to test its association with non-fatal cardiovascular events in patients on chronic HD. A study population consisted of 95 prevalent HD patients in the HD unit of Hospital of Lithuanian University of Health sciences Kaunas Clinics. Clinical data and laboratory tests information were collected from medical records. SVCS was evaluated as it is described by Adragao et al. After measurement of VC, HD patients were observed for novel non-fatal cardiovascular events. Patients were divided into two groups: SVCS≥3 (57 patients [60%]) and <3 (38 patients [40%]). The Kaplan-Meier survival curves show a significant difference in non-fatal cardiovascular events in the group with SVCS≥3 vs. <3 group (26.3% vs. 7.8%; log rank 5,49; P=0.018). Multivariate Cox regression analysis confirmed a negative impact of VC, hyperphosphatemia, and lower ejection fraction on cardiovascular events. No statistically significant differences were observed comparing parameters of Ca-P metabolism disorders between groups with different SVCS. On separate analysis, the presence of VC in hands was also associated with higher rate of novel cardiovascular events (score 0 goup-5 events [10.6%] vs. score≥1 group-13 events [27%], log rank P=0.035). VC assessed by simple and inexpensive radiological method was an independent predictor of novel non-fatal cardiovascular events in HD patients. Copyright © 2016 Association Société de néphrologie. Published by Elsevier SAS. All rights reserved.

Transcriptomic changes reveal gene networks responding to the overexpression of a blueberry DWARF AND DELAYED FLOWERING 1 gene in transgenic blueberry plants.

PubMed

Song, Guo-Qing; Gao, Xuan

2017-06-19

Constitutive expression of the CBF/DREB1 for increasing freezing tolerance in woody plants is often associated with other phenotypic changes including dwarf plant and delayed flowering. These phenotypic changes have been observed when Arabidopsis DWARF AND DELAYED FLOWERING 1 (DDF1) was overexpressed in A. thaliana plants. To date, the DDF1 orthologues have not been studied in woody plants. The aim of this study is to investigate transcriptomic responses to the overexpression of blueberry (Vaccinium corymbosum) DDF1 (herein, VcDDF1-OX). The VcDDF1-OX resulted in enhanced freezing tolerance in tetraploid blueberry plants and did not result in significant changes in plant size, chilling requirement, and flowering time. Comparative transcriptome analysis of transgenic 'Legacy-VcDDF1-OX' plants containing an overexpressed VcDDF1 with non-transgenic highbush blueberry 'Legacy' plants revealed the VcDDF1-OX derived differentially expressed (DE) genes and transcripts in the pathways of cold-response, plant flowering, DELLA proteins, and plant phytohormones. The increase in freezing tolerance was associated to the expression of cold-regulated genes (CORs) and the ethylene pathway genes. The unchanged plant size, dormancy and flowering were due to the minimal effect of the VcDDF1-OX on the expression of DELLA proteins, flowering pathway genes, and the other phytohormone genes related to plant growth and development. The DE genes in auxin and cytokinin pathways suggest that the VcDDF1-OX has also altered plant tolerance to drought and high salinity. A DDF1 orthologue in blueberry functioned differently from the DDF1 reported in Arabidopsis. The overexpression of VcDDF1 or its orthologues is a new approach to increase freezing tolerance of deciduous woody plant species with no obvious effect on plant size and plant flowering time.

Organization of hyperactive microglial cells in trigeminal spinal subnucleus caudalis and upper cervical spinal cord associated with orofacial neuropathic pain.

PubMed

Shibuta, Kazuo; Suzuki, Ikuko; Shinoda, Masamichi; Tsuboi, Yoshiyuki; Honda, Kuniya; Shimizu, Noriyoshi; Sessle, Barry J; Iwata, Koichi

2012-04-27

The aim of this study was to evaluate spatial organization of hyperactive microglial cells in trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal cord (C1), and to clarify the involvement in mechanisms underlying orofacial secondary hyperalgesia following infraorbital nerve injury. We found that the head-withdrawal threshold to non-noxious mechanical stimulation of the maxillary whisker pad skin was significantly reduced in chronic constriction injury of the infraorbital nerve (ION-CCI) rats from day 1 to day 14 after ION-CCI. On day 3 after ION-CCI, mechanical allodynia was obvious in the orofacial skin areas innervated by the 1st and 3rd branches of the trigeminal nerve as well as the 2nd branch area. Hyperactive microglial cells in Vc and C1 were observed on days 3 and 7 after ION-CCI. On day 3 after ION-CCI, a large number of phosphorylated extracellular signal-regulated kinase (pERK)-immunoreactive (IR) cells were observed in Vc and C1. Many hyperactive microglial cells were also distributed over a wide area of Vc and C1 innervated by the trigeminal nerve. The intraperitoneal administration of minocycline significantly reduced the activation of microglial cells and the number of pERK-IR cells in Vc and C1, and also significantly attenuated the development of mechanical allodynia. Furthermore, enhanced background activity and mechanical evoked responses of Vc wide dynamic range neurons in ION-CCI rats were significantly reversed following minocycline administration. These findings suggest that activation of microglial cells over a wide area of Vc and C1 is involved in the enhancement of Vc and C1 neuronal excitability in the early period after ION-CCI, resulting in the neuropathic pain in orofacial areas innervated by the injured as well as uninjured nerves. Copyright © 2012 Elsevier B.V. All rights reserved.

Marginal bone-level alterations of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.

PubMed

Thoma, Daniel S; Benic, Goran I; Muñoz, Fernando; Kohal, Ralf; Sanz Martin, Ignacio; Cantalapiedra, Antonio G; Hämmerle, Christoph H F; Jung, Ronald E

2016-04-01

The aim was to test whether or not the marginal bone-level alterations of loaded zirconia implants are similar to the bone-level alterations of a grade 4 titanium one-piece dental implant. In six dogs, all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants (BPI, VC, ZD) and a control titanium one-piece (STM) implant were randomly placed in each hemimandible and left for transmucosal healing (baseline). Six months later, CAD/CAM crowns were cemented. Sacrifice was scheduled at 6-month postloading. Digital X-rays were taken at implant placement, crowns insertion, and sacrifice. Marginal bone-level alterations were calculated, and intra- and intergroup comparisons performed adjusted by confounding factors. Implants were successfully placed. Until crown insertion, two implants were fractured (one VC, one ZD). At sacrifice, 5 more implants were (partly) fractured (one BPI, four ZD), and one lost osseointegration (VC). No decementation of crowns occurred. All implant systems demonstrated a statistically significant (except VC) loss of marginal bone between baseline and crown insertion ranging from 0.29 mm (VC; P = 0.116) to 0.80 mm (ZD; P = 0.013). The estimated marginal bone loss between baseline and 6 months of loading ranged between 0.19 mm (BPI) and 1.11 mm (VC), being statistically significant for STM and VC only (P < 0.05). The changes in marginal bone levels were statistically significantly different between zirconia implants and control implants (STM vs. BPI P = 0.007; vs. VC P = 0.001; vs. ZD P = 0.011). Zirconia implants were more prone to fracture prior to and after loading with implant-supported crowns compared to titanium implants. Individual differences and variability in the extent of the bone-level changes during the 12-month study period were found between the different implant types and materials. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Acetogenic microbial degradation of vinyl chloride

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.

2000-01-01

Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C- acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries, respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and humic acids- reducing conditions.Under methanogenic conditions, microbial degradation of [1,2-14C]vinyl chloride (VC) resulted in significant (14 ?? 3% maximum recovery) but transient recovery of radioactivity as 14C-acetate. Subsequently, 14C-acetate was degraded to 14CH4 and 14CO2 (18 ?? 2% and 54 ?? 3% final recoveries respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, 14C-acetate recovery remained high (27 ?? 1% maximum recovery) throughout the study, no 14CH4 was produced, and the final recovery of 14CO2 was only 35 ?? 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH4 and CO2 may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO2 reported previously under Fe(III)-reducing, SO4-reducing, and humic acids-reducing conditions.

Genomic Characterization of Vulvar (Pre)cancers Identifies Distinct Molecular Subtypes with Prognostic Significance.

PubMed

Nooij, Linda S; Ter Haar, Natalja T; Ruano, Dina; Rakislova, Natalia; van Wezel, Tom; Smit, Vincent T H B M; Trimbos, Baptist J B M Z; Ordi, Jaume; van Poelgeest, Mariette I E; Bosse, Tjalling

2017-11-15

Purpose: Vulvar cancer (VC) can be subclassified by human papillomavirus (HPV) status. HPV-negative VCs frequently harbor TP53 mutations; however, in-depth analysis of other potential molecular genetic alterations is lacking. We comprehensively assessed somatic mutations in a large series of vulvar (pre)cancers. Experimental Design: We performed targeted next-generation sequencing (17 genes), p53 immunohistochemistry and HPV testing on 36 VC and 82 precursors (sequencing cohort). Subsequently, the prognostic significance of the three subtypes identified in the sequencing cohort was assessed in a series of 236 VC patients (follow-up cohort). Results: Frequent recurrent mutations were identified in HPV-negative vulvar (pre)cancers in TP53 (42% and 68%), NOTCH1 (28% and 41%), and HRAS (20% and 31%). Mutation frequency in HPV-positive vulvar (pre)cancers was significantly lower ( P = 0.001). Furthermore, a substantial subset of the HPV-negative precursors (35/60, 58.3%) and VC (10/29, 34.5%) were TP53 wild-type (wt), suggesting a third, not-previously described, molecular subtype. Clinical outcomes in the three different subtypes (HPV + , HPV - /p53wt, HPV - /p53abn) were evaluated in a follow-up cohort consisting of 236 VC patients. Local recurrence rate was 5.3% for HPV + , 16.3% for HPV - /p53wt and 22.6% for HPV - /p53abn tumors ( P = 0.044). HPV positivity remained an independent prognostic factor for favorable outcome in the multivariable analysis ( P = 0.020). Conclusions: HPV - and HPV + vulvar (pre)cancers display striking differences in somatic mutation patterns. HPV - /p53wt VC appear to be a distinct clinicopathologic subgroup with frequent NOTCH1 mutations. HPV + VC have a significantly lower local recurrence rate, independent of clinicopathological variables, opening opportunities for reducing overtreatment in VC. Clin Cancer Res; 23(22); 6781-9. ©2017 AACR . ©2017 American Association for Cancer Research.

Fuel cell system combustor

DOEpatents

Pettit, William Henry

2001-01-01

A fuel cell system including a fuel reformer heated by a catalytic combustor fired by anode and cathode effluents. The combustor includes a turbulator section at its input end for intimately mixing the anode and cathode effluents before they contact the combustors primary catalyst bed. The turbulator comprises at least one porous bed of mixing media that provides a tortuous path therethrough for creating turbulent flow and intimate mixing of the anode and cathode effluents therein.

High-temperature durability considerations for HSCT combustor

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.

1992-01-01

The novel combustor designs for the High Speed Civil Transport will require high temperature materials with long term environmental stability. Higher liner temperatures than in conventional combustors and the need for reduced weight necessitates the use of advanced ceramic matrix composites. The combustor environment is defined at the current state of design, the major degradation routes are discussed for each candidate ceramic material, and where possible, the maximum use temperatures are defined for these candidate ceramics.

Coaxial Dump Ramjet Combustor Combustion Instabilities. Part I. Parametric Test Data.

DTIC Science & Technology

1981-07-01

AD-AIII 355 COAXIAL DUP RA8.? COMBUSTOR COMBUSTION INSTABILITIES I/~ PART I PARAUER1C. 1111 AIR FORCE WRIONT AERONUTICAL LAOS WRIOIII-PATTERSOll...MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANOAROS - 193- A AFWAL-TR-81 -2047 Part 1 COAXIAL DUMP RAMJET COMBUSTOR COMBUSTION INSTABILITIES PART...COMBUSTOR Interim Report for Period COMBUSTION INSTABILITIES February 1979 - March 1980 Part I - Parametric Test Data S. PERFORMING ORG. REPORT NUMBER 7

Flame monitoring of a model swirl injector using 1D tunable diode laser absorption spectroscopy tomography

NASA Astrophysics Data System (ADS)

Liu, Chang; Cao, Zhang; Li, Fangyan; Lin, Yuzhen; Xu, Lijun

2017-05-01

Distributions of temperature and H2O concentration in a swirling flame are critical to evaluate the performance of a gas turbine combustor. In this paper, 1D tunable diode laser absorption spectroscopy tomography (1D-TDLAST) was introduced to monitor swirling flames generated from a model swirl injector by simultaneously reconstructing the rotationally symmetric distributions of temperature and H2O concentration. The optical system was sufficiently simplified by introducing only one fan-beam illumination and a linear detector array of 12 equally-spaced photodetectors. The fan-beam illumination penetrated a cross section of interest in the swirling flame and the transmitted intensities were detected by the detector array. With the transmitted intensities in hand, projections were extracted and employed by a 1D tomographic algorithm to reconstruct the distributions of temperature and H2O concentration. The route of the precessing vortex core generated in the swirling flame can be easily inferred from the reconstructed profiles of temperature and H2O concentration at different heights above the nozzle of the swirl injector.

Turbulence, combustion, pollutant, and stability characterization of a premixed, step combustor

NASA Technical Reports Server (NTRS)

Ganji, A. T.; Sawyer, R. F.

1980-01-01

A two dimensional combustion tunnel was constructed to study a lean premixed turbulent propane/air flame stablized behind a rearward facing step. Studied were: (1) the existence and importance of large coherent structures in turbulent reacting and nonreacting free shear layers behind the steps; (2) the effect of inlet temperature and reference velocity on combustion efficiency; (3) CO, NO2 and NO sub x production in the flame; and (4) the blowout and upstream propagation of the flame. In the ranges studied, the large coherent structures dominated both the reacting and the nonreacting free shear layers behind the step. The growth of the vortices and the propagation of the flamer were intimately linked. Vortex pairing was observed to be one of the mechanisms for introduction of fresh reactants into the shear layer and growth of the shear layer. Probe composition measurements of the flame showed that, in the recirculation zone, the reaction was above 99 percent complete, CO and unburnt hydrocarbons were above the equilibrium level NO sub x concentration was far below the equilibrium level and NO2 comprised a negligible fraction of NO sub x.

Numerical approaches to combustion modeling. Progress in Astronautics and Aeronautics. Vol. 135

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oran, E.S.; Boris, J.P.

1991-01-01

Various papers on numerical approaches to combustion modeling are presented. The topics addressed include; ab initio quantum chemistry for combustion; rate coefficient calculations for combustion modeling; numerical modeling of combustion of complex hydrocarbons; combustion kinetics and sensitivity analysis computations; reduction of chemical reaction models; length scales in laminar and turbulent flames; numerical modeling of laminar diffusion flames; laminar flames in premixed gases; spectral simulations of turbulent reacting flows; vortex simulation of reacting shear flow; combustion modeling using PDF methods. Also considered are: supersonic reacting internal flow fields; studies of detonation initiation, propagation, and quenching; numerical modeling of heterogeneous detonations, deflagration-to-detonationmore » transition to reactive granular materials; toward a microscopic theory of detonations in energetic crystals; overview of spray modeling; liquid drop behavior in dense and dilute clusters; spray combustion in idealized configurations: parallel drop streams; comparisons of deterministic and stochastic computations of drop collisions in dense sprays; ignition and flame spread across solid fuels; numerical study of pulse combustor dynamics; mathematical modeling of enclosure fires; nuclear systems.« less

Computation of losses in a scramjet combustor

NASA Technical Reports Server (NTRS)

Kamath, Pradeep S.; Mcclinton, Charles R.

1992-01-01

The losses in a conceptual scramjet combustor at flight Mach numbers of 8, 10, 12, 16 and 20 are computed. These losses are extracted from three-dimensional parabolized Navier-Stokes solutions of the turbulent, reacting combustor flow field. A combustor performance index was defined based on the rationale that an efficient scramjet combustor should add heat to the fluid in such a manner as to maximize the stream thrust at the combustor exit while minimizing the losses. This index showed a decrease of more than 40 percent as the flight Mach number increased from 8 to 20, indicative of a drop in the thrust-producing potential of the scramjet at the upper end of the speed regime studied. A breakdown of the losses showed that dissipation, nonequilibrium chemistry and heat diffusion contributed roughly 15 percent, 35 percent, and 50 percent to the irreversible increase in entropy at Mach 8 and 22 percent, 13 and 65 percent at Mach 20.

Experimental evaluation of combustor concepts for burning broad property fuels

NASA Technical Reports Server (NTRS)

Kasper, J. M.; Ekstedt, E. E.; Dodds, W. J.; Shayeson, M. W.

1980-01-01

A baseline CF6-50 combustor and three advanced combustor designs were evaluated to determine the effects of combustor design on operational characteristics using broad property fuels. Three fuels were used in each test: Jet A, a broad property 13% hydrogen fuel, and a 12% hydrogen fuel blend. Testing was performed in a sector rig at true cruise and simulated takeoff conditions for the CF6-50 engine cycle. The advanced combustors (all double annular, lean dome designs) generally exhibited lower metal temperatures, exhaust emissions, and carbon buildup than the baseline CF6-50 combustor. The sensitivities of emissions and metal temperatures to fuel hydrogen content were also generally lower for the advanced designs. The most promising advanced design used premixing tubes in the main stage. This design was chosen for additional testing in which fuel/air ratio, reference velocity, and fuel flow split were varied.

Effect of Fuel Injection and Mixing Characteristics on Pulse-Combustor Performance at High-Pressure

NASA Technical Reports Server (NTRS)

Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

2014-01-01

Recent calculations of pulse-combustors operating at high-pressure conditions produced pressure gains significantly lower than those observed experimentally and computationally at atmospheric conditions. The factors limiting the pressure-gain at high-pressure conditions are identified, and the effects of fuel injection and air mixing characteristics on performance are investigated. New pulse-combustor configurations were developed, and the results show that by suitable changes to the combustor geometry, fuel injection scheme and valve dynamics the performance of the pulse-combustor operating at high-pressure conditions can be increased to levels comparable to those observed at atmospheric conditions. In addition, the new configurations can significantly reduce the levels of NOx emissions. One particular configuration resulted in extremely low levels of NO, producing an emission index much less than one, although at a lower pressure-gain. Calculations at representative cruise conditions demonstrated that pulse-combustors can achieve a high level of performance at such conditions.

Parametric Study of Pulse-Combustor-Driven Ejectors at High-Pressure

NASA Technical Reports Server (NTRS)

Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

2015-01-01

Pulse-combustor configurations developed in recent studies have demonstrated performance levels at high-pressure operating conditions comparable to those observed at atmospheric conditions. However, problems related to the way fuel was being distributed within the pulse combustor were still limiting performance. In the first part of this study, new configurations are investigated computationally aimed at improving the fuel distribution and performance of the pulse-combustor. Subsequent sections investigate the performance of various pulse-combustor driven ejector configurations operating at highpressure conditions, focusing on the effects of fuel equivalence ratio and ejector throat area. The goal is to design pulse-combustor-ejector configurations that maximize pressure gain while achieving a thermal environment acceptable to a turbine, and at the same time maintain acceptable levels of NOx emissions and flow non-uniformities. The computations presented here have demonstrated pressure gains of up to 2.8%.

Parametric Study of Pulse-Combustor-Driven Ejectors at High-Pressure

NASA Technical Reports Server (NTRS)

Yungster, Shaye; Paxson, Daniel E.; Perkins, Hugh D.

2015-01-01

Pulse-combustor configurations developed in recent studies have demonstrated performance levels at high-pressure operating conditions comparable to those observed at atmospheric conditions. However, problems related to the way fuel was being distributed within the pulse combustor were still limiting performance. In the first part of this study, new configurations are investigated computationally aimed at improving the fuel distribution and performance of the pulse-combustor. Subsequent sections investigate the performance of various pulse-combustor driven ejector configurations operating at high pressure conditions, focusing on the effects of fuel equivalence ratio and ejector throat area. The goal is to design pulse-combustor-ejector configurations that maximize pressure gain while achieving a thermal environment acceptable to a turbine, and at the same time maintain acceptable levels of NO(x) emissions and flow non-uniformities. The computations presented here have demonstrated pressure gains of up to 2.8.

Study of research and development requirements of small gas-turbine combustors

NASA Technical Reports Server (NTRS)

Demetri, E. P.; Topping, R. F.; Wilson, R. P., Jr.

1980-01-01

A survey is presented of the major small-engine manufacturers and governmental users. A consensus was undertaken regarding small-combustor requirements. The results presented are based on an evaluation of the information obtained in the course of the study. The current status of small-combustor technology is reviewed. The principal problems lie in liner cooling, fuel injection, part-power performance, and ignition. Projections of future engine requirements and their effect on the combustor are discussed. The major changes anticipated are significant increases in operating pressure and temperature levels and greater capability of using heavier alternative fuels. All aspects of combustor design are affected, but the principal impact is on liner durability. An R&D plan which addresses the critical combustor needs is described. The plan consists of 15 recommended programs for achieving necessary advances in the areas of liner thermal design, primary-zone performance, fuel injection, dilution, analytical modeling, and alternative-fuel utilization.

Parametric test results of a swirl-can combustor

NASA Technical Reports Server (NTRS)

Niedzwiecki, R. W.; Jones, R. E.

1973-01-01

Pollutant levels of oxides of nitrogen, unburned hydrocarbons, and carbon monoxide were measured for three models of an experimental, annular swirl can combustor. The combustor was 1.067 meters in outer diameter, incorporated 120 modules, and was specifically designed for elevated exit temperature performance. Test conditions included combustor inlet temperatures of 589, 756 and 839 K, inlet pressures of 3 to 6.4 atmospheres, reference velocities of 21 to 38 meters per second and combustor equivalence ratios, based on total combustor flows of 0.206 to 1.028. Maximum oxides of nitrogen emission index values occurred at an equivalence ratio of 0.7 with lower values measured for both higher and lower equivalence ratios. Oxides of nitrogen concentrations, to the 0.7 level with 756 K inlet air, were correlated for the three models by a combined parameter consisting of measured flow and geometric parameters. Effects of the individual parameters comprising the correlation are also presented.

Advanced technology for reducing aircraft engine pollution

NASA Technical Reports Server (NTRS)

Jones, R. E.

1973-01-01

The proposed EPA regulations covering emissions of gas turbine engines will require extensive combustor development. The NASA is working to develop technology to meet these goals through a wide variety of combustor research programs conducted in-house, by contract, and by university grant. In-house efforts using the swirl-can modular combustor have demonstrated sizable reduction in NO emission levels. Testing to reduce idle pollutants has included the modification of duplex fuel nozzles to air-assisted nozzles and an exploration of the potential improvements possible with combustors using fuel staging and variable geometry. The Experimental Clean Combustor Program, a large contracted effort, is devoted to the testing and development of combustor concepts designed to achieve a large reduction in the levels of all emissions. This effort is planned to be conducted in three phases with the final phase to be an engine demonstration of the best reduced emission concepts.

Energy efficient engine sector combustor rig test program

NASA Technical Reports Server (NTRS)

Dubiel, D. J.; Greene, W.; Sundt, C. V.; Tanrikut, S.; Zeisser, M. H.

1981-01-01

Under the NASA-sponsored Energy Efficient Engine program, Pratt & Whitney Aircraft has successfully completed a comprehensive combustor rig test using a 90-degree sector of an advanced two-stage combustor with a segmented liner. Initial testing utilized a combustor with a conventional louvered liner and demonstrated that the Energy Efficient Engine two-stage combustor configuration is a viable system for controlling exhaust emissions, with the capability to meet all aerothermal performance goals. Goals for both carbon monoxide and unburned hydrocarbons were surpassed and the goal for oxides of nitrogen was closely approached. In another series of tests, an advanced segmented liner configuration with a unique counter-parallel FINWALL cooling system was evaluated at engine sea level takeoff pressure and temperature levels. These tests verified the structural integrity of this liner design. Overall, the results from the program have provided a high level of confidence to proceed with the scheduled Combustor Component Rig Test Program.

Linear aerospike engine study. [for reusable launch vehicles

NASA Technical Reports Server (NTRS)

Diem, H. G.; Kirby, F. M.

1977-01-01

Parametric data on split-combustor linear engine propulsion systems are presented for use in mixed-mode single-stage-to-orbit (SSTO) vehicle studies. Preliminary design data for two selected engine systems are included. The split combustor was investigated for mixed-mode operations with oxygen/hydrogen propellants used in the inner combustor in Mode 2, and in conjunction with either oxygen/RP-1, oxygen/RJ-5, O2/CH4, or O2/H2 propellants in the outer combustor for Mode 1. Both gas generator and staged combustion power cycles were analyzed for providing power to the turbopumps of the inner and outer combustors. Numerous cooling circuits and cooling fluids (propellants) were analyzed and hydrogen was selected as the preferred coolant for both combustors and the linear aerospike nozzle. The maximum operating chamber pressure was determined to be limited by the availability of hydrogen coolant pressure drop in the coolant circuit.

The large-amplitude combustion oscillation in a single-side expansion scramjet combustor

NASA Astrophysics Data System (ADS)

Ouyang, Hao; Liu, Weidong; Sun, Mingbo

2015-12-01

The combustion oscillation in scramjet combustor is believed not existing and ignored for a long time. Compared with the flame pulsation, the large-amplitude combustion oscillation in scramjet combustor is indeed unfamiliar and difficult to be observed. In this study, the specifically designed experiments are carried out to investigate this unusual phenomenon in a single-side expansion scramjet combustor. The entrance parameter of combustor corresponds to scramjet flight Mach number 4.0 with a total temperature of 947 K. The obtained results show that the large-amplitude combustion oscillation can exist in scramjet combustor, which is not occasional and can be reproduced. Under the given conditions of this study, moreover, the large-amplitude combustion oscillation is regular and periodic, whose principal frequency is about 126 Hz. The proceeding of the combustion oscillation is accompanied by the transformation of the flame-holding pattern and combustion mode transition between scramjet mode combustion and ramjet mode combustion.

Engine-Scale Combustor Rig Designed, Fabricated, and Tested for Combustion Instability Control Research

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Breisacher, Kevin J.

2000-01-01

Low-emission combustor designs are prone to combustor instabilities. Because active control of these instabilities may allow future combustors to meet both stringent emissions and performance requirements, an experimental combustor rig was developed for investigating methods of actively suppressing combustion instabilities. The experimental rig has features similar to a real engine combustor and exhibits instabilities representative of those in aircraft gas turbine engines. Experimental testing in the spring of 1999 demonstrated that the rig can be tuned to closely represent an instability observed in engine tests. Future plans are to develop and demonstrate combustion instability control using this experimental combustor rig. The NASA Glenn Research Center at Lewis Field is leading the Combustion Instability Control program to investigate methods for actively suppressing combustion instabilities. Under this program, a single-nozzle, liquid-fueled research combustor rig was designed, fabricated, and tested. The rig has many of the complexities of a real engine combustor, including an actual fuel nozzle and swirler, dilution cooling, and an effusion-cooled liner. Prior to designing the experimental rig, a survey of aircraft engine combustion instability experience identified an instability observed in a prototype engine as a suitable candidate for replication. The frequency of the instability was 525 Hz, with an amplitude of approximately 1.5-psi peak-to-peak at a burner pressure of 200 psia. The single-nozzle experimental combustor rig was designed to preserve subcomponent lengths, cross sectional area distribution, flow distribution, pressure-drop distribution, temperature distribution, and other factors previously found to be determinants of burner acoustic frequencies, mode shapes, gain, and damping. Analytical models were used to predict the acoustic resonances of both the engine combustor and proposed experiment. The analysis confirmed that the test rig configuration and engine configuration had similar longitudinal acoustic characteristics, increasing the likelihood that the engine instability would be replicated in the rig. Parametric analytical studies were performed to understand the influence of geometry and condition variations and to establish a combustion test plan. Cold-flow experiments verified that the design values of area and flow distributions were obtained. Combustion test results established the existence of a longitudinal combustion instability in the 500-Hz range with a measured amplitude approximating that observed in the engine. Modifications to the rig configuration during testing also showed the potential for injector independence. The research combustor rig was developed in partnership with Pratt & Whitney of West Palm Beach, Florida, and United Technologies Research Center of East Hartford, Connecticut. Experimental testing of the combustor rig took place at United Technologies Research Center.

Combustion Dynamics and Control for Ultra Low Emissions in Aircraft Gas-Turbine Engines

NASA Technical Reports Server (NTRS)

DeLaat, John C.

2011-01-01

Future aircraft engines must provide ultra-low emissions and high efficiency at low cost while maintaining the reliability and operability of present day engines. The demands for increased performance and decreased emissions have resulted in advanced combustor designs that are critically dependent on efficient fuel/air mixing and lean operation. However, all combustors, but most notably lean-burning low-emissions combustors, are susceptible to combustion instabilities. These instabilities are typically caused by the interaction of the fluctuating heat release of the combustion process with naturally occurring acoustic resonances. These interactions can produce large pressure oscillations within the combustor and can reduce component life and potentially lead to premature mechanical failures. Active Combustion Control which consists of feedback-based control of the fuel-air mixing process can provide an approach to achieving acceptable combustor dynamic behavior while minimizing emissions, and thus can provide flexibility during the combustor design process. The NASA Glenn Active Combustion Control Technology activity aims to demonstrate active control in a realistic environment relevant to aircraft engines by providing experiments tied to aircraft gas turbine combustors. The intent is to allow the technology maturity of active combustion control to advance to eventual demonstration in an engine environment. Work at NASA Glenn has shown that active combustion control, utilizing advanced algorithms working through high frequency fuel actuation, can effectively suppress instabilities in a combustor which emulates the instabilities found in an aircraft gas turbine engine. Current efforts are aimed at extending these active control technologies to advanced ultra-low-emissions combustors such as those employing multi-point lean direct injection.

Results of the NASP Ames Integrated Mixing Hypersonic Engine (AIMHYE) Scramjet Test Program

NASA Technical Reports Server (NTRS)

Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George S.

1995-01-01

This paper describes the test techniques and results from the National Aerospace Plane Government Work Package 53, the Ames Integrated Mixing Hypersonic Engine (AIMHYE) Scramjet Test program conducted in the NASA Ames 16-Inch Combustion Driven Shock Tunnel. This was a series of near full-scale scramjet combustor tests with the objective to obtain high speed combustor and nozzle data from an engine with injector configurations similar to the NASP E21 and E22a designs. The experimental test approach was to use a large combustor model (80-100% throat height) designed and fabricated for testing in the semi-free jet mode. The conditions tested were similar to the "blue book" conditions at Mach 12, 14, and 16. GWP 53 validated use of large, long test time impulse facilities, specifically the Ames 16-Inch Shock Tunnel, for high Mach number scramjet propulsion testing an integrated test rig (inlet, combustor, and nozzle). Discussion of key features of the test program will include: effects of the 2-D combustor inlet pressure profile; performance of large injectors' fueling system that included nozzlettes, base injection, and film cooling; and heat transfer measurements to the combustor. Significant instrumentation development and application efforts include the following: combustor force balance application for measurement of combustor drag for comparison with integrated point measurements of skin friction; nozzle metric strip for measuring thrust with comparison to integrated pressure measurements; and nonintrusive optical fiber-based diode laser absorption measurements of combustion products for determination of combustor performance. Direct measurements will be reported for specific test article configurations and compared with CFD solutions.

Isolation and Structural Characterization of Two Very Large, and Largely Empty, Endohedral Fullerenes: Tm@C3v-C94 and Ca@C3v-C94

PubMed Central

Che, Yuliang; Yang, Hua; Wang, Zhimin; Jin, Hongxiao; Lu, Chunxin; Zuo, Tianming; Beavers, Christine M.

2009-01-01

The structures of two newly synthesized endohedral fullerenes - Tm@C3v-C94 and Ca@C3v-C94 - have been determined by single crystal X-ray diffraction on samples co-crystallized with NiII(octaethylporphyrin). Both compounds exhibit the same cage geometry and conform to the isolated pentagon rule (IPR). The metal ions within these rather large cages are localized near one end and along the C3 axis. While the calcium ion is situated over a C-C bond at a 6:6 ring junction, the thulium ion is positioned above a six-membered ring of the fullerene. PMID:19507844

Effect of structural heat conduction on the performance of micro-combustors and micro-thrusters

NASA Astrophysics Data System (ADS)

Leach, Timothy Thierry

This thesis investigates the effect of gas-structure interaction on the design and performance of miniaturized combustors with characteristic dimensions less than a few millimeters. These are termed 'micro-combustors' and are intended for use in devices ranging from micro-scale rocket motors for micro, nano, and pico-satellite propulsion, to micro-scale engines for micro-Unmanned Air Vehicle (UAV) propulsion and compact power generation. Analytical models for the propagation of a premixed laminar flame in a micro-channel are developed. The models' predictions are compared to the results of more detailed numerical simulations that incorporate multi-step chemistry, distributed heat transfer between the reacting gas and the combustor structure, heat transfer between the combustor and the environment, and heat transfer within the combustor structure. The results of the modeling and simulation efforts are found to be in good qualitative agreement and demonstrate that the behavior of premixed laminar flames in micro-channels is governed by heat transfer within the combustor structure and heat loss to the environment. The key findings of this work are as follows: First, heat transfer through the micro-combustor's structure tends to increase the flame speed and flame thickness. The increase in flame thickness with decreasing passage height suggests that micro-scale combustors will need to be longer than their conventional-scale counterparts. However, the increase in flame speed more than compensates for this effect and the net effect is that miniaturizing a combustor can increase its power density substantially. Second, miniaturizing chemical rocket thrusters can substantially increase thrust/weight ratio but comes at the price of reduced specific impulse (i.e. overall efficiency). Third, heat transfer through the combustor's structure increases steady-state and transient flame stability. This means that micro-scale combustors will be more stable than their conventional-scale counterparts. Fourth and finally, the extended temperature profile associated with the broadened flame causes a different set of elementary reactions to dominate the operation of the overall reaction mechanism at the micro-scale. This suggests that new chemical mechanisms may need to be developed in order to accurately simulate combustion at small-scales. It also calls into question the efficacy of single-step mechanisms presently used by other researchers.

Interface ring for gas turbine fuel nozzle assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, Timothy A.; Schilp, Reinhard

A gas turbine combustor assembly including a combustor liner and a plurality of fuel nozzle assemblies arranged in an annular array extending within the combustor liner. The fuel nozzle assemblies each include fuel nozzle body integral with a swirler assembly, and the swirler assemblies each include a bellmouth structure to turn air radially inwardly for passage into the swirler assemblies. A radially outer removed portion of each of the bellmouth structures defines a periphery diameter spaced from an inner surface of the combustor liner, and an interface ring is provided extending between the combustor liner and the removed portions ofmore » the bellmouth structures at the periphery diameter.« less

Low NO sub x heavy fuel combustor concept program

NASA Technical Reports Server (NTRS)

Russell, P.; Beal, G.; Hinton, B.

1981-01-01

A gas turbine technology program to improve and optimize the staged rich lean low NOx combustor concept is described. Subscale combustor tests to develop the design information for optimization of the fuel preparation, rich burn, quick air quench, and lean burn steps of the combustion process were run. The program provides information for the design of high pressure full scale gas turbine combustors capable of providing environmentally clean combustion of minimally of minimally processed and synthetic fuels. It is concluded that liquid fuel atomization and mixing, rich zone stoichiometry, rich zone liner cooling, rich zone residence time, and quench zone stoichiometry are important considerations in the design and scale up of the rich lean combustor.

Radiant heat transfer from flames in a single tubular turbojet combustor / Leonard Topper

NASA Technical Reports Server (NTRS)

Topper, Leonard

1952-01-01

An experimental investigation of thermal radiation from the flame of a single tubular turbojet-engine combustor to the combustor liner is presented. The effects of combustor inlet-air pressure, air mass flow, and fuel-air ratio on the radiant intensity and the temperature and emissivity of the flame are reported. The total radiation of the "luminous" flames (containing incandescent soot particles) was much greater (4 to 21 times) than the "nonluminous" molecular radiation. The intensity of radiation from the flame increased rapidly with an increase in combustor inlet-air pressure; it was affected to a lesser degree by variations in fuel-air ratio and air mass flow.

A chemical reactor network for oxides of nitrogen emission prediction in gas turbine combustor

NASA Astrophysics Data System (ADS)

Hao, Nguyen Thanh

2014-06-01

This study presents the use of a new chemical reactor network (CRN) model and non-uniform injectors to predict the NOx emission pollutant in gas turbine combustor. The CRN uses information from Computational Fluid Dynamics (CFD) combustion analysis with two injectors of CH4-air mixture. The injectors of CH4-air mixture have different lean equivalence ratio, and they control fuel flow to stabilize combustion and adjust combustor's equivalence ratio. Non-uniform injector is applied to improve the burning process of the turbine combustor. The results of the new CRN for NOx prediction in the gas turbine combustor show very good agreement with the experimental data from Korea Electric Power Research Institute.

Investigation of soot and carbon formation in small gas turbine combustors

NASA Technical Reports Server (NTRS)

Rosfjord, T. J.

1982-01-01

An investigation of hardware configurations which attempt to minimize carbon and soot-production without sacrificing performance in small gas turbine combustors was conducted. Four fuel injectors, employing either airblast atomization, pressure atomization, or fuel vaporization techniques were combined with nozzle air swirlers and injector sheaths. Eight configurations were screened at sea-level takeoff and idle test conditions. Selected configurations were focused upon in an attempt to quantify the influence of combustor pressure, inlet temperature, primary zone operation, and combustor loading on soot and carbon formation. Cycle tests were also performed. It was found that smoke emission levels depended on the combustor fluid mechanics, the atomization quality of the injector and the fuel hydrogen content.

Method for Making Measurements of the Post-Combustion Residence Time in a Gas Turbine Engine

NASA Technical Reports Server (NTRS)

Miles, Jeffrey H (Inventor)

2015-01-01

A system and method of measuring a residence time in a gas-turbine engine is provided, whereby the method includes placing pressure sensors at a combustor entrance and at a turbine exit of the gas-turbine engine and measuring a combustor pressure at the combustor entrance and a turbine exit pressure at the turbine exit. The method further includes computing cross-spectrum functions between a combustor pressure sensor signal from the measured combustor pressure and a turbine exit pressure sensor signal from the measured turbine exit pressure, applying a linear curve fit to the cross-spectrum functions, and computing a post-combustion residence time from the linear curve fit.

Numerical Prediction of Non-Reacting and Reacting Flow in a Model Gas Turbine Combustor

NASA Technical Reports Server (NTRS)

Davoudzadeh, Farhad; Liu, Nan-Suey

2005-01-01

The three-dimensional, viscous, turbulent, reacting and non-reacting flow characteristics of a model gas turbine combustor operating on air/methane are simulated via an unstructured and massively parallel Reynolds-Averaged Navier-Stokes (RANS) code. This serves to demonstrate the capabilities of the code for design and analysis of real combustor engines. The effects of some design features of combustors are examined. In addition, the computed results are validated against experimental data.

Advanced liner-cooling techniques for gas turbine combustors

NASA Technical Reports Server (NTRS)

Norgren, C. T.; Riddlebaugh, S. M.

1985-01-01

Component research for advanced small gas turbine engines is currently underway at the NASA Lewis Research Center. As part of this program, a basic reverse-flow combustor geometry was being maintained while different advanced liner wall cooling techniques were investigated. Performance and liner cooling effectiveness of the experimental combustor configuration featuring counter-flow film-cooled panels is presented and compared with two previously reported combustors featuring: splash film-cooled liner walls; and transpiration cooled liner walls (Lamilloy).

Flow process in combustors

NASA Technical Reports Server (NTRS)

Gouldin, F. C.

1982-01-01

Fluid mechanical effects on combustion processes in steady flow combustors, especially gas turbine combustors were investigated. Flow features of most interest were vorticity, especially swirl, and turbulence. Theoretical analyses, numerical calculations, and experiments were performed. The theoretical and numerical work focused on noncombusting flows, while the experimental work consisted of both reacting and nonreacting flow studies. An experimental data set, e.g., velocity, temperature and composition, was developed for a swirl flow combustor for use by combustion modelers for development and validation work.

Broad Specification Fuels Combustion Technology Program, Phase 2

NASA Technical Reports Server (NTRS)

Lohmann, R. P.; Jeroszko, R. A.; Kennedy, J. B.

1990-01-01

An experimental evaluation of two advanced technology combustor concepts was conducted to evolve and assess their capability for operation on broadened properties fuels. The concepts were based on the results of Phase 1 of the Broad Specification Fuel Combustor Technology Program which indicated that combustors with variable geometry or staged combustion zones had a flexibility of operation that could facilitate operation on these fuels. Emphasis in defining these concepts included the use of single pipe as opposed to duplex or staged fuels systems to avoid the risk of coking associated with the reduction in thermal stability expected in broadened properties fuels. The first concept was a variable geometry combustor in which the airflow into the primary zone could be altered through valves on the front while the second was an outgrowth of the staged Vorbix combustor, evolved under the NASA/P&W ECCP and EEE programs incorporating simplified fuel and air introduction. The results of the investigation, which involved the use of Experimental Referee Broad Specification (ERBS) fuel, indicated that in the form initially conceived, both of these combustor concepts were deficient in performance relative to many of the program goals for performance emissions. However, variations of both combustors were evaluated that incorporated features to simulate conceptual enhancement to demonstrate the long range potential of the combustor. In both cases, significant improvements relative to the program goals were observed.

Combustor technology for future small gas turbine aircraft

NASA Technical Reports Server (NTRS)

Lyons, Valerie J.; Niedzwiecki, Richard W.

1993-01-01

Future engine cycles proposed for advanced small gas turbine engines will increase the severity of the operating conditions of the combustor. These cycles call for increased overall engine pressure ratios which increase combustor inlet pressure and temperature. Further, the temperature rise through the combustor and the corresponding exit temperature also increase. Future combustor technology needs for small gas turbine engines is described. New fuel injectors with large turndown ratios which produce uniform circumferential and radial temperature patterns will be required. Uniform burning will be of greater importance because hot gas temperatures will approach turbine material limits. The higher combustion temperatures and increased radiation at high pressures will put a greater heat load on the combustor liners. At the same time, less cooling air will be available as more of the air will be used for combustion. Thus, improved cooling concepts and/or materials requiring little or no direct cooling will be required. Although presently there are no requirements for emissions levels from small gas turbine engines, regulation is expected in the near future. This will require the development of low emission combustors. In particular, nitrogen oxides will increase substantially if new technologies limiting their formation are not evolved and implemented. For example, staged combustion employing lean, premixed/prevaporized, lean direct injection, or rich burn-quick quench-lean burn concepts could replace conventional single stage combustors.

Orbit transfer rocket engine technology program enhanced heat transfer combustor technology

NASA Technical Reports Server (NTRS)

Brown, William S.

1991-01-01

In order to increase the performance of a high performance, advanced expander-cycle engine combustor, higher chamber pressures are required. In order to increase chamber pressure, more heat energy is required to be transferred to the combustor coolant circuit fluid which drives the turbomachinery. This requirement was fulfilled by increasing the area exposed to the hot-gas by using combustor ribs. A previous technology task conducted 2-d hot air and cold flow tests to determine an optimum rib height and configuration. In task C.5 a combustor calorimeter was fabricated with the optimum rib configuration, 0.040 in. high ribs, in order to determine their enhancing capability. A secondary objective was to determine the effects of mixture ratio changers on the enhancement during hot-fire testing. The program used the Rocketdyne Integrated Component Evaluator (ICE) reconfigured into a thrust chamber only mode. The test results were extrapolated to give a projected enhancement from the ribs for a 16 in. long cylindrical combustor at 15 Klb nominal thrust level. The hot-gas wall ribs resulted in a 58 percent increase in heat transfer. When projected to a full size 15K combustor, it becomes a 46 percent increase. The results of those tests, a comparison with previous 2-d results, the effects of mixture ratio and combustion gas flow on the ribs and the potential ramifications for expander cycle combustors are detailed.

Multi-Dimensional Measurements of Combustion Species in Flame Tube and Sector Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Hicks, Yolanda Royce

1996-01-01

The higher temperature and pressure cycles of future aviation gas turbine combustors challenge designers to produce combustors that minimize their environmental impact while maintaining high operation efficiency. The development of low emissions combustors includes the reduction of unburned hydrocarbons, smoke, and particulates, as well as the reduction of oxides of nitrogen (NO(x)). In order to better understand and control the mechanisms that produce emissions, tools are needed to aid the development of combustor hardware. Current methods of measuring species within gas turbine combustors use extractive sampling of combustion gases to determine major species concentrations and to infer the bulk flame temperature. These methods cannot be used to measure unstable combustion products and have poor spatial and temporal resolution. The intrusive nature of gas sampling may also disturb the flow structure within a combustor. Planar laser-induced fluorescence (PLIF) is an optical technique for the measurement of combustion species. In addition to its non-intrusive nature, PLIF offers these advantages over gas sampling: high spatial resolution, high temporal resolution, the ability to measure unstable species, and the potential to measure combustion temperature. This thesis considers PLIF for in-situ visualization of combustion species as a tool for the design and evaluation of gas turbine combustor subcomponents. This work constitutes the first application of PLIF to the severe environment found in liquid-fueled, aviation gas turbine combustors. Technical and applied challenges are discussed. PLIF of OH was used to observe the flame structure within the post flame zone of a flame tube combustor, and within the flame zone of a sector combustor, for a variety of fuel injector configurations. OH was selected for measurement because it is a major combustion intermediate, playing a key role in the chemistry of combustion, and because its presence within the flame zone can serve as a qualitative marker of flame temperature. All images were taken in the environment of actual engines during flight, using actual jet fuel. The results of the PLIF study led directly to the modification of a fuel injector.

The virtual continuity in learning programme: results.

PubMed

Wood, Eleanor; Tso, Simon

2012-08-01

The implementation of the European Working Time Directive and specialty-driven care has resulted in the loss of continuity of patient care, and thus a loss of continuity in learning. We proposed a potential solution to this fragmentation of junior doctor workplace learning in the Virtual Continuity in Learning Programme (VCLP). The VCLP enables the doctor to follow the virtual patient journey (of an actual patient who is no longer under their care) using the Virtual Consulting Room (VcR), and to understand the rationale behind clinical decision making prior to completing their case-based discussion (CbD) work-based assessments. Fifty-seven out of 62 (92%) of foundation doctors (Homerton University Hospital, London, UK) consented to participate in the study. Web-tracking software was used. Fifty-three out of 57 (93%) doctors completed an initial questionnaire. Twenty-nine out of 57 (51%) doctors returned a follow-up questionnaire 6 months later. Eleven doctors were interviewed in three focus groups: the VcR user group; the VcR non-user group; and a mixed group. The data was analysed qualitatively. Tracking showed 33.3 per cent (19/57) of doctors used the VcR over a 6-month period. Interestingly doctors used the VcR in a range of situations, not solely as instructed. Results enabled us to understand how doctors learn and their perception of using the VCLP to support their learning and completion of work-based assessments. Foundation doctors use the educational resources available, including the VcR, to help structure their workplace learning. The majority of VcR users found it particularly useful for just-in-time learning. The VCLP offers support to junior doctors learning during their preparation for case-based discussion. © Blackwell Publishing Ltd 2012.

Structural insights into the oligomerization mode of the human receptor for advanced glycation end-products.

PubMed

Yatime, Laure; Andersen, Gregers R

2013-12-01

The receptor for advanced glycation end-products (RAGE) is a pattern recognition receptor sensing endogenous stress signals associated with the development of various diseases, including diabetes, vascular complications, Alzheimer's disease and cancer. RAGE ligands include advanced glycation end-products, S100 proteins, high mobility group box 1 protein and amyloid β-peptides/fibrils. Their signalling through RAGE induces a sustained inflammation that accentuates tissue damage, thereby participating in disease progression. Receptor oligomerization appears to be a crucial parameter for the formation of active signalling complexes, although the precise mode of oligomerization remains unclear in the context of these various ligands. In the present study, we report the first crystal structure of the VC1C2 fragment of the RAGE ectodomain. This structure provides the first description of the C2 domain in the context of the entire ectodomain and supports the observation of its conformational freedom relative to the rigid VC1 domain tandem. In addition, we have obtained a new crystal structure of the RAGE VC1 fragment. The packing in both crystal structures reveals an association of the RAGE molecules through contacts between two V domains and the physiological relevance of this homodimerization mode is discussed. Based on homology with single-pass transmembrane receptors, we also suggest RAGE dimerization through a conserved GxxxG motif within its transmembrane domain. A multimodal homodimerization strategy of RAGE is proposed to form the structural basis for ligand-specific complex formation and signalling functions, as well as for RAGE-mediated cell adhesion. hRAGE_VC1C2 and hRAGE_VC1C2 bind by x-ray crystallography (View interaction) hRAGE_VC1 and hRAGE_VC1 bind by x-ray crystallography (View interaction). © 2013 FEBS.

Exposure of Daphnia magna to trichloroethylene (TCE) and vinyl chloride (VC): evaluation of gene transcription, cellular activity, and life-history parameters.

PubMed

Houde, Magali; Douville, Mélanie; Gagnon, Pierre; Sproull, Jim; Cloutier, François

2015-06-01

Trichloroethylene (TCE) is a ubiquitous contaminant classified as a human carcinogen. Vinyl chloride (VC) is primarily used to manufacture polyvinyl chloride and can also be a degradation product of TCE. Very few data exist on the toxicity of TCE and VC in aquatic organisms particularly at environmentally relevant concentrations. The aim of this study was to evaluate the sub-lethal effects (10 day exposure; 0.1; 1; 10 µg/L) of TCE and VC in Daphnia magna at the gene, cellular, and life-history levels. Results indicated impacts of VC on the regulation of genes related to glutathione-S-transferase (GST), juvenile hormone esterase (JHE), and the vitelline outer layer membrane protein (VMO1). On the cellular level, exposure to 0.1, 1, and 10 µg/L of VC significantly increased the activity of JHE in D. magna and TCE increased the activity of chitinase (at 1 and 10 µg/L). Results for life-history parameters indicated a possible tendency of TCE to affect the number of molts at the individual level in D. magna (p=0.051). Measurement of VG-like proteins using the alkali-labile phosphates (ALP) assay did not show differences between TCE treated organisms and controls. However, semi-quantitative measurement using gradient gel electrophoresis (213-218 kDa) indicated significant decrease in VG-like protein levels following exposure to TCE at all three concentrations. Overall, results indicate effects of TCE and VC on genes and proteins related to metabolism, reproduction, and growth in D. magna. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

A somatostatin analog improves tilt table tolerance by decreasing splanchnic vascular conductance

PubMed Central

Florian, J. P.; Curren, M. J.; Pawelczyk, J. A.

2012-01-01

Splanchnic hemodynamics and tilt table tolerance were assessed after an infusion of placebo or octreotide acetate, a somatostatin analog whose vascular effects are largely confined to the splanchnic circulation. We hypothesized that reductions in splanchnic blood flow (SpBF) and splanchnic vascular conductance (SpVC) would be related to improvements in tilt table tolerance. In randomized, double-blind, crossover trials, hemodynamic variables were collected in 14 women and 16 men during baseline, 70° head-up tilt (HUT), and recovery. A repeated-measures analysis of variance was used to compare changes from baseline with respect to sex and condition. HUT elicited an increase in heart rate and decreases in mean arterial pressure, cardiac index, stroke index, and systemic vascular conductance. Additionally, SpVC and non-SpVC were lower during HUT. Octreotide reduced SpBF and SpVC and increased systemic vascular conductance and non-SpVC. Changes in SpBF and SpVC between supine and HUT were smaller in women (P < 0.05). Tilt table tolerance was increased after administration of octreotide [median tilt time: 15.7 vs. 37.0 min (P < 0.05) and 21.8 vs. 45.0 min (P < 0.05) for women and men, respectively]. A significant relationship existed between change (Δ) in SpBF (placebo-octreotide) and Δtilt time in women (Δtilt time = 2.5–0.0083 ΔSpBF, P < 0.01), but not men (Δtilt time = 3.41–0.0008 ΔSpBF, P = 0.59). In conclusion, administration of octreotide acetate improved tilt table tolerance, which was associated with a decrease in SpVC. In women, but not men, the magnitude of reduction in SpBF was positively associated with improvements in tilt tolerance. PMID:22345429

Molecular characterisation of a calmodulin gene, VcCaM1, that is differentially expressed under aluminium stress in highbush blueberry.

PubMed

Inostroza-Blancheteau, C; Aquea, F; Loyola, R; Slovin, J; Josway, S; Rengel, Z; Reyes-Díaz, M; Alberdi, M; Arce-Johnson, P

2013-11-01

Calmodulin (CaM), a small acidic protein, is one of the best characterised Ca(2+) sensors in eukaryotes. This Ca(2+) -regulated protein plays a critical role in decoding and transducing environmental stress signals by activating specific targets. Many environmental stresses elicit changes in intracellular Ca(2+) activity that could initiate adaptive responses under adverse conditions. We report the first molecular cloning and characterisation of a calmodulin gene, VcCaM1 (Vaccinium corymbosum Calmodulin 1), in the woody shrub, highbush blueberry. VcCaM1 was first identified as VCAL19, a gene induced by aluminium stress in V. corymbosum L. A full-length cDNA of VcCaM1 containing a 766-bp open reading frame (ORF) encoding 149 amino acids was cloned from root RNA. The sequence encodes four Ca(2+) -binding motifs (EF-hands) and shows high similarity (99%) with the isoform CaM 201 of Daucus carota. Expression analyses showed that following Al treatment, VcCaM1 message level decreased in roots of Brigitta, an Al-resistant cultivar, and after 48 h, was lower than in Bluegold, an Al-sensitive cultivar. VcCAM1 message also decreased in leaves of both cultivars within 2 h of treatment. Message levels in leaves then increased by 24 h to control levels in Brigitta, but not in Bluegold, but then decreased again by 48 h. In conclusion, VcCaM1 does not appear to be directly involved in Al resistance, but may be involved in improved plant performance under Al toxicity conditions through regulation of Ca(2+) homeostasis and antioxidant systems in leaves. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Sensitization of trigeminal brainstem pathways in a model for tear deficient dry eye

PubMed Central

Rahman, Mostafeezur; Okamoto, Keiichiro; Thompson, Randall; Katagiri, Ayano; Bereiter, David A.

2015-01-01

Abstract Chronic dry eye disease (DE) is associated with an unstable tear film and symptoms of ocular discomfort. The characteristics of symptoms suggest a key role for central neural processing; however, little is known about central neuroplasticity and DE. We used a model for tear deficient DE and assessed effects on eye blink behavior, orbicularis oculi muscle activity (OOemg), and trigeminal brainstem neural activity in male rats. Ocular-responsive neurons were recorded at the interpolaris/caudalis transition (Vi/Vc) and Vc/upper cervical cord (Vc/C1) regions under isoflurane, whereas OOemg activity was recorded under urethane. Spontaneous tear volume was reduced by ∼50% at 14 days after exorbital gland removal. Hypertonic saline–evoked eye blink behavior in awake rats was enhanced throughout the 14 days after surgery. Saline-evoked neural activity at the Vi/Vc transition and in superficial and deep laminae at the Vc/C1 region was greatly enhanced in DE rats. Neurons from DE rats classified as wide dynamic range displayed enlarged convergent periorbital receptive fields consistent with central sensitization. Saline-evoked OOemg activity was markedly enhanced in DE rats compared with controls. Synaptic blockade at the Vi/Vc transition or the Vc/C1 region greatly reduced hypertonic saline–evoked OOemg activity in DE and sham rats. These results indicated that persistent tear deficiency caused sensitization of ocular-responsive neurons at multiple regions of the caudal trigeminal brainstem and enhanced OOemg activity. Central sensitization of ocular-related brainstem circuits is a significant factor in DE and likely contributes to the apparent weak correlation between peripheral signs of tear dysfunction and symptoms of irritation. PMID:25734990

Experimental investigations on effect of different materials and varying depths of one turn exhaust channel swiss roll combustor on its thermal performance

NASA Astrophysics Data System (ADS)

Mane Deshmukh, Sagar B.; Krishnamoorthy, A.; Bhojwani, V. K.; Pawane, Ashwini

2017-05-01

More energy density of hydrocarbon fuels compared to advanced batteries available in the market demands for development of systems which will use hydrocarbon fuels at small scale to generate power in small quantity (i.e. in few watts) and device efficiency should be reasonably good, but the basic requirement is to generate heat from the fuels like methane, propane, hydrogen, LPG and converting into power. Swiss roll combustor has proved to be best combustor at small scale. Present work is carried out on one turn exhaust channel and half turn of inlet mixture channel Swiss roll combustor. Purpose of keeping exhaust channel length more than the inlet mixture channel to ensure sufficient time for heat exchange between burned and unburned gases, which is not reported in earlier studies. Experimental study mentions effects of different design parameters like materials of combustor, various depths, equivalence ratio, mass flow rates of liquefied petroleum gas (LPG), volume of combustion space and environmental conditions (with insulation and without insulation to combustors) on fuel lean limit and fuel rich limit, temperature profile obtained on all external surfaces, in the main combustion chamber, in the channel carrying unburned gas mixture and burned gas mixture, heat loss to atmosphere from all the walls of combustor, flame location. Different combustor materials tested were stainless steel, Aluminum, copper, brass, bronze, Granite. Depths considered were 22mm, 15mm, 10mm and 5mm. It was observed that flame stability inside the combustion chamber is affected by materials, depths and flow rates. Unburned mixture carrying channel was kept below quenching distance of flame to avoid flash back. Burned gas carrying channel dimension was more than the quenching distance. Considerable temperature rise was observed with insulation to combustors. But combustors with more thermal conductivity showed more heat loss to atmosphere which led to instability of flame.

Unstructured LES of Reacting Multiphase Flows in Realistic Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Ham, Frank; Apte, Sourabh; Iaccarino, Gianluca; Wu, Xiao-Hua; Herrmann, Marcus; Constantinescu, George; Mahesh, Krishnan; Moin, Parviz

2003-01-01

As part of the Accelerated Strategic Computing Initiative (ASCI) program, an accurate and robust simulation tool is being developed to perform high-fidelity LES studies of multiphase, multiscale turbulent reacting flows in aircraft gas turbine combustor configurations using hybrid unstructured grids. In the combustor, pressurized gas from the upstream compressor is reacted with atomized liquid fuel to produce the combustion products that drive the downstream turbine. The Large Eddy Simulation (LES) approach is used to simulate the combustor because of its demonstrated superiority over RANS in predicting turbulent mixing, which is central to combustion. This paper summarizes the accomplishments of the combustor group over the past year, concentrating mainly on the two major milestones achieved this year: 1) Large scale simulation: A major rewrite and redesign of the flagship unstructured LES code has allowed the group to perform large eddy simulations of the complete combustor geometry (all 18 injectors) with over 100 million control volumes; 2) Multi-physics simulation in complex geometry: The first multi-physics simulations including fuel spray breakup, coalescence, evaporation, and combustion are now being performed in a single periodic sector (1/18th) of an actual Pratt & Whitney combustor geometry.

Hypersonic Combustor Model Inlet CFD Simulations and Experimental Comparisons

NASA Technical Reports Server (NTRS)

Venkatapathy, E.; TokarcikPolsky, S.; Deiwert, G. S.; Edwards, Thomas A. (Technical Monitor)

1995-01-01

Numerous two-and three-dimensional computational simulations were performed for the inlet associated with the combustor model for the hypersonic propulsion experiment in the NASA Ames 16-Inch Shock Tunnel. The inlet was designed to produce a combustor-inlet flow that is nearly two-dimensional and of sufficient mass flow rate for large scale combustor testing. The three-dimensional simulations demonstrated that the inlet design met all the design objectives and that the inlet produced a very nearly two-dimensional combustor inflow profile. Numerous two-dimensional simulations were performed with various levels of approximations such as in the choice of chemical and physical models, as well as numerical approximations. Parametric studies were conducted to better understand and to characterize the inlet flow. Results from the two-and three-dimensional simulations were used to predict the mass flux entering the combustor and a mass flux correlation as a function of facility stagnation pressure was developed. Surface heat flux and pressure measurements were compared with the computed results and good agreement was found. The computational simulations helped determine the inlet low characteristics in the high enthalpy environment, the important parameters that affect the combustor-inlet flow, and the sensitivity of the inlet flow to various modeling assumptions.

Biological control of Ascaris suum eggs by Pochonia chlamydosporia fungus.

PubMed

Ferreira, Sebastião Rodrigo; de Araújo, Jackson Victor; Braga, Fábio Ribeiro; Araujo, Juliana Milani; Frassy, Luiza Neme; Ferreira, Aloízio Soares

2011-12-01

Ascaris suum is a gastrointestinal nematode parasite of swines. The aim of this study was to observe Pochonia chlamydosporia fungus on biological control of A. suum eggs after fungus passage through swines gastrointestinal tract. Eighteen pigs, previously dewormed, were randomly divided into three groups: group 1, treated with the fungus isolate VC4; group 2, treated with the fungus isolate VC1 and group 3 did not receive fungus (control). In the treated groups, each animal received a 9 g single dose of mycelium mass containing P. chlamydosporia (VC1 or VC4). Thereafter, animal fecal samples were collected at the following intervals: 8, 12, 24, 36, 48, 72 and 96 h after treatment beginning and these were poured in Petri dishes containing 2% water-agar culture medium. Then, 1,000 A. suum eggs were poured into each dish and kept in an incubator at 26 °C and in the dark for 30 days. After this period, approximately 100 eggs were removed from each Petri dish and morphologically analyzed under light microscopy following the ovicidal activity parameters. The higher percentage observed for isolated VC4 eggs destruction was 57.5% (36 h) after fungus administration and for isolate VC1 this percentage was 45.8% (24 h and 72 h) (p > 0.01). P. chlamydosporia remained viable after passing through the gastrointestinal tract of swines, maintaining its ability of destroying A. suum eggs.

Effect of Fe(III) on 1,1,2,2-Tetrachloroethane degradation and vinyl chloride accumulation in wetland sediments of the Aberdeen Proving Ground

USGS Publications Warehouse

Jones, Elizabeth; Voytek, Mary; Lorah, Michelle

2004-01-01

1,1,2,2-Tetrachloroethane (TeCA) contaminated groundwater at the Aberdeen Proving Ground discharges through an anaerobic wetland in West Branch Canal Creek (MD), where dechlorination occurs. Two microbially mediated pathways, dichloroelimination and hydrogenolysis, account for most of the TeCA degradation at this site. The dichloroelimination pathways lead to the formation of vinyl chloride (VC), a recalcitrant carcinogen of great concern. The goal of this investigation was to determine whether microbially-available Fe(III) in the wetland surface sediment influenced the fate of TeCA and its daughter products. Differences were identified in the TeCA degradation pathway between microcosms treated with amorphous ferric oxyhydroxide (AFO-treated) and untreated (no AFO) microcosms. TeCA degradation was accompanied by a lower accumulation of VC in AFO-treated microcosms than untreated microcosms. The microcosm incubations and subsequent experiments with the microcosm materials showed that AFO treatment resulted in lower production of VC by (1) shifting TeCA degradation from dichloroelimination pathways to production of a greater proportion of chlorinated ethane products, and (2) decreasing the microbial capability to produce VC from 1,2-dichloroethene (DCE). VC degradation was not stimulated in the presence of Fe(III). Rather, VC degradation occurred readily under methanogenic conditions and was inhibited under Fe(III)-reducing conditions.

Combustor with non-circular head end

DOEpatents

Kim, Won -Wook; McMahan, Kevin Weston

2015-09-29

The present application provides a combustor for use with a gas turbine engine. The combustor may include a head end with a non-circular configuration, a number of fuel nozzles positioned about the head end, and a transition piece extending downstream of the head end.

Variable volume combustor with a conical liner support

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Thomas Edward; McConnaughhay, Johnie Franklin; Keener, Chrisophter Paul

The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a conical liner support supporting the liner.

Ignition methods and apparatus using microwave energy

DOEpatents

DeFreitas, Dennis Michael; Migliori, Albert

1997-01-01

An ignition apparatus for a combustor includes a microwave energy source that emits microwave energy into the combustor at a frequency within a resonant response of the combustor, the combustor functioning as a resonant cavity for the microwave energy so that a plasma is produced that ignites a combustible mixture therein. The plasma preferably is a non-contact plasma produced in free space within the resonant cavity spaced away from with the cavity wall structure and spaced from the microwave emitter.

Multifuel evaluation of rich/quench/lean combustor

NASA Technical Reports Server (NTRS)

Notardonato, J. J.; Novick, A. S.; Troth, D. L.

1982-01-01

The fuel flexible combustor technology was developed for application to the Model 570-K industrial gas turbine engine. The technology, to achieve emission goals, emphasizes dry NOx reduction methods. Due to the high levels of fuel-bound nitrogen (FBN), control of NOx can be effected through a staged combustor with a rich initial combustion zone. A rich/quench/lean variable geometry combustor utilizes the technology presented to achieve low NOx from alternate fuels containing FBN. The results focus on emissions and durability for multifuel operation.

Staged cascade fluidized bed combustor

DOEpatents

Cannon, Joseph N.; De Lucia, David E.; Jackson, William M.; Porter, James H.

1984-01-01

A fluid bed combustor comprising a plurality of fluidized bed stages interconnected by downcomers providing controlled solids transfer from stage to stage. Each stage is formed from a number of heat transfer tubes carried by a multiapertured web which passes fluidizing air to upper stages. The combustor cross section is tapered inwardly from the middle towards the top and bottom ends. Sorbent materials, as well as non-volatile solid fuels, are added to the top stages of the combustor, and volatile solid fuels are added at an intermediate stage.

Quiet Clean Short-haul Experimental Engine (QCSEE) clean combustor test report

NASA Technical Reports Server (NTRS)

1975-01-01

A component pressure test was conducted on a F101 PFRT combustor to evaluate the emissions levels of this combustor design at selected under the wing and over the wing operating conditions for the quiet clean short haul experimental engine (QCSEE). Emissions reduction techniques were evaluated which included compressor discharge bleed and sector burning in the combustor. The results of this test were utilized to compare the expected QCSEE emissions levels with the emission goals of the QCSEE engine program.

Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor

DTIC Science & Technology

2014-06-01

Constant mass inflow from a choked orifice Exit Boundary Condition Choked nozzle Diameter of combustor 50.8 mm Diameter of air plenum 25.4 mm A...schematic of the LDI combustor is shown in Fig. 1. It comprises an air inlet section, air plenum, swirler- venturi- injector assembly, combustion chamber...and exit nozzle . Air, heated with an 80 kW electrical heater, enters the combustor through a slotted choked orifice plate, designed to minimize

Dual-Mode Combustor

NASA Technical Reports Server (NTRS)

Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

2013-01-01

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

Properties of Fuels Employed in a Gas Turbine Combustor Program.

DTIC Science & Technology

1983-09-01

potence nateonale PROPERTIES OF FUELS EMPLOYED IN A GAS TURBINE COMBUSTOR PROGRAM by .J.R. Coleman and L.D. Gallop JAN 1O t84’ La.I DEFENCE ROSOARCH...ESTABLISHMENT OTTAWA T~INCAMNTE M4 1-05 - ottwa , National Dibense3 Detence nationale PROPERTIES OF FUELS EMPLOYED IN A GAS TURBINE COMBUSTOR PROGRAM by...made of the physical and chemical properties of sixteen fuels employed in an aircraft gas turbine combustor programme. Several of these are specification

Combustor oscillating pressure stabilization and method

DOEpatents

Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.H.; Cully, S.R.; Addis, R.E.

1998-08-11

High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time. 7 figs.

Effects of vasoactive intestinal peptide on vascular conductance are unaffected by anesthesia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bouder, T.G.; Huffman, L.J.; Hedge, G.A.

1988-12-01

In rats anesthetized with ketamine and pentobarbital (KET/PB), vasoactive intestinal peptide (VIP) increases vascular conductance (VC) in the salivary gland, pancreas, and thyroid gland, whereas no changes in VC are observed in a number of other organs. Because anesthesia may alter the responsiveness of physiological systems, we compared the effects of VIP on organ VC in conscious or anesthetized rats. Chronically catheterized rats were studied in the conscious state or 30 min after induction of anesthesia with KET/PB, isoflurane, or Inactin. Blood flows were measured by the reference sample version of the radioactive microsphere (MS) technique using two MS injectionsmore » ({sup 141}Ce-MS/{sup 85}Sr-MS). Mean arterial blood pressure was monitored and used in the calculation of VC. Organ VCs were similar under basal conditions in conscious and anesthetized rats. VIP infusion caused systemic hypotension and increased VCs in the salivary gland, pancreas, and thyroid gland, and these responses were largely unaffected by anesthesia. These results indicate that the anesthetics used do not alter basal VC or the responsiveness of the vasculature to exogenous VIP.« less

Vapor chamber with hollow condenser tube heat sink

NASA Astrophysics Data System (ADS)

Ong, K. S.; Haw, P. L.; Lai, K. C.; Tan, K. H.

2017-04-01

Heat pipes are heat transfer devices capable of transferring large quantities of heat effectively and efficiently. A vapor chamber (VC) is a flat heat pipe. A novel VC with hollow condenser tubes embedded on the top of it is proposed. This paper reports on the experimental thermal performance of three VC devices embedded with hollow tubes and employed as heat sinks. The first device consisted of a VC with a single hollow tube while the other two VCs had an array of multi-tubes with different tube lengths. All three devices were tested under natural and force air convection cooling. An electrical resistance heater was employed to provide power inputs of 10 and 40 W. Surface temperatures were measured with thermocouple probes at different locations around the devices. The results show that temperatures increased with heater input while total device thermal resistances decreased. Force convection results in lower temperatures and lower resistance. Dry-out occurs at high input power and with too much condensing area. There appears to be an optimum fill ratio which depended upon dimensions of the VC and also heating power.

Estimation of gas and tissue lung volumes by MRI: functional approach of lung imaging.

PubMed

Qanadli, S D; Orvoen-Frija, E; Lacombe, P; Di Paola, R; Bittoun, J; Frija, G

1999-01-01

The purpose of this work was to assess the accuracy of MRI for the determination of lung gas and tissue volumes. Fifteen healthy subjects underwent MRI of the thorax and pulmonary function tests [vital capacity (VC) and total lung capacity (TLC)] in the supine position. MR examinations were performed at inspiration and expiration. Lung volumes were measured by a previously validated technique on phantoms. Both individual and total lung volumes and capacities were calculated. MRI total vital capacity (VC(MRI)) was compared with spirometric vital capacity (VC(SP)). Capacities were correlated to lung volumes. Tissue volume (V(T)) was estimated as the difference between the total lung volume at full inspiration and the TLC. No significant difference was seen between VC(MRI) and VC(SP). Individual capacities were well correlated (r = 0.9) to static volume at full inspiration. The V(T) was estimated to be 836+/-393 ml. This preliminary study demonstrates that MRI can accurately estimate lung gas and tissue volumes. The proposed approach appears well suited for functional imaging of the lung.

Application of jet-shear-layer mixing and effervescent atomization to the development of a low-NO(x) combustor. Ph.D. Thesis - Purdue Univ.

NASA Technical Reports Server (NTRS)

Colantonio, Renato Olaf

1993-01-01

An investigation was conducted to develop appropriate technologies for a low-NO(x), liquid-fueled combustor. The combustor incorporates an effervescent atomizer used to inject fuel into a premixing duct. Only a fraction of the combustion air is used in the premixing process to avoid autoignition and flashback problems. This fuel-rich mixture is introduced into the remaining combustion air by a rapid jet-shear-layer-mixing process involving radial fuel-air jets impinging on axial air jets in the primary combustion zone. Computational analysis was used to provide a better understanding of the fluid dynamics that occur in jet-shear-layer mixing and to facilitate a parametric analysis appropriate to the design of an optimum low-NO(x) combustor. A number of combustor configurations were studied to assess the key combustor technologies and to validate the modeling code. The results from the experimental testing and computational analysis indicate a low-NO(x) potential for the jet-shear-layer combustor. Key parameters found to affect NO(x) emissions are the primary combustion zone fuel-air ratio, the number of axial and radial jets, the aspect ratio and radial location of the axial air jets, and the radial jet inlet hole diameter. Each of these key parameters exhibits a low-NO(x) point from which an optimized combustor was developed. Using the parametric analysis, NO(x) emissions were reduced by a factor of 3 as compared with the emissions from conventional, liquid-fueled combustors operating at cruise conditions. Further development promises even lower NO(x) with high combustion efficiency.

A-E Services to Perform a Cathodic Protection Survey of the Bulk Fuel Terminals at N.S.C. Pearl Harbor, Hawaii. Volume I.

DTIC Science & Technology

1982-06-01

20) From VC-D to VC-E a. 8" Avgas Line - Coated Steel (21) From FC -E to Victor Dock #1 a. 12" Avgas Line - Coated Steel (22) From Air Force Scraper...14. Bldg. S776 3" Ballast Line to VC-2 - 775 3" Ballast Line to Loading Rack - 775 15. 6" Water Line, 10’ N of Bldg. S776 - 745 6" AFFF Line, N of...S776 3" Ballast line to VC-2 - 740 - 775 35 3" Ballast line to Loading Rack - 740 - 775 35 15. 6" Water line 10’ N of Bldg. S776 - 710 - 745 35 6" AFFF

A combined toxicity study of zinc oxide nanoparticles and vitamin C in food additives

NASA Astrophysics Data System (ADS)

Wang, Yanli; Yuan, Lulu; Yao, Chenjie; Ding, Lin; Li, Chenchen; Fang, Jie; Sui, Keke; Liu, Yuanfang; Wu, Minghong

2014-11-01

At present, safety evaluation standards for nanofood additives are made based on the toxic effects of a single additive. Since the size, surface properties and chemical nature influence the toxicity of nanomaterials, the toxicity may have dramatically changed when nanomaterials are used as food additives in a complex system. Herein, we investigated the combined toxicity of zinc oxide nanoparticles (ZnO NPs) and vitamin C (Vc, ascorbic acid). The results showed that Vc increased the cytotoxicity significantly compared with that of the ZnO only NPs. When the cells were exposed to ZnO NPs at a concentration less than 15 mg L-1, or to Vc at a concentration less than 300 mg L-1, there was no significant cytotoxicity, both in the case of gastric epithelial cell line (GES-1) and neural stem cells (NSCs). However, when 15 mg L-1 of ZnO NPs and 300 mg L-1 of Vc were introduced to cells together, the cell viability decreased sharply indicating significant cytotoxicity. Moreover, the significant increase in toxicity was also shown in the in vivo experiments. The dose of the ZnO NPs and Vc used in the in vivo study was calculated according to the state of food and nutrition enhancer standard. After repeated oral exposure to ZnO NPs plus Vc, the injury of the liver and kidneys in mice has been indicated by the change of these indices. These findings demonstrate that the synergistic toxicity presented in a complex system is essential for the toxicological evaluation and safety assessment of nanofood.At present, safety evaluation standards for nanofood additives are made based on the toxic effects of a single additive. Since the size, surface properties and chemical nature influence the toxicity of nanomaterials, the toxicity may have dramatically changed when nanomaterials are used as food additives in a complex system. Herein, we investigated the combined toxicity of zinc oxide nanoparticles (ZnO NPs) and vitamin C (Vc, ascorbic acid). The results showed that Vc increased the cytotoxicity significantly compared with that of the ZnO only NPs. When the cells were exposed to ZnO NPs at a concentration less than 15 mg L-1, or to Vc at a concentration less than 300 mg L-1, there was no significant cytotoxicity, both in the case of gastric epithelial cell line (GES-1) and neural stem cells (NSCs). However, when 15 mg L-1 of ZnO NPs and 300 mg L-1 of Vc were introduced to cells together, the cell viability decreased sharply indicating significant cytotoxicity. Moreover, the significant increase in toxicity was also shown in the in vivo experiments. The dose of the ZnO NPs and Vc used in the in vivo study was calculated according to the state of food and nutrition enhancer standard. After repeated oral exposure to ZnO NPs plus Vc, the injury of the liver and kidneys in mice has been indicated by the change of these indices. These findings demonstrate that the synergistic toxicity presented in a complex system is essential for the toxicological evaluation and safety assessment of nanofood. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05480f

Alternate-Fueled Combustor-Sector Performance: Part A: Combustor Performance Part B: Combustor Emissions

NASA Technical Reports Server (NTRS)

Shouse, D. T.; Neuroth, C.; Henricks, R. C.; Lynch, A.; Frayne, C.; Stutrud, J. S.; Corporan, E.; Hankins, T.

2010-01-01

Alternate aviation fuels for military or commercial use are required to satisfy MIL-DTL-83133F(2008) or ASTM D 7566 (2010) standards, respectively, and are classified as drop-in fuel replacements. To satisfy legacy issues, blends to 50% alternate fuel with petroleum fuels are certified individually on the basis of feedstock. Adherence to alternate fuels and fuel blends requires smart fueling systems or advanced fuel-flexible systems, including combustors and engines without significant sacrifice in performance or emissions requirements. This paper provides preliminary performance (Part A) and emissions and particulates (Part B) combustor sector data for synthetic-parafinic-kerosene- (SPK-) type fuel and blends with JP-8+100 relative to JP-8+100 as baseline fueling.

Design and preliminary results of a semitranspiration cooled (Lamilloy) liner for a high-pressure high-temperature combustor

NASA Technical Reports Server (NTRS)

Wear, J. D.; Trout, A. M.; Smith, J. M.; Jones, R. E.

1978-01-01

A Lamilloy combustor liner was designed, fabricated and tested in a combustor at pressures up to 8 atmospheres. The liner was fabricated of a three layer Lamilloy structure and designed to replace a conventional step louver liner. The liner is to be used in a combustor that provides hot gases to a turbine cooling test facility at pressures up to 40 atmospheres. The Lamilloy liner was tested extensively at lower pressures and demonstrated lower metal temperatures than the conventional liner, while at the same time requiring about 40 percent less cooling air flow. Tests conducted at combustor exit temperatures in excess of 2200 K have not indicated any cooling or durability problems with the Lamilloy linear.

NASA Glenn Research Center UEET (Ultra-Efficient Engine Technology) Program: Agenda and Abstracts

NASA Technical Reports Server (NTRS)

Manthey, Lri

2001-01-01

Topics discussed include: UEET Overview; Technology Benefits; Emissions Overview; P&W Low Emissions Combustor Development; GE Low Emissions Combustor Development; Rolls-Royce Low Emissions Combustor Development; Honeywell Low Emissions Combustor Development; NASA Multipoint LDI Development; Stanford Activities In Concepts for Advanced Gas Turbine Combustors; Large Eddy Simulation (LES) of Gas Turbine Combustion; NASA National Combustion Code Simulations; Materials Overview; Thermal Barrier Coatings for Airfoil Applications; Disk Alloy Development; Turbine Blade Alloy; Ceramic Matrix Composite (CMC) Materials Development; Ceramic Matrix Composite (CMC) Materials Characterization; Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials; Ceramic Matrix Composite Vane Rig Testing and Design; Ultra-High Temperature Ceramic (UHTC) Development; Lightweight Structures; NPARC Alliance; Technology Transfer and Commercialization; and Turbomachinery Overview; etc.

Combustor materials requirements and status of ceramic matrix composites

NASA Technical Reports Server (NTRS)

Hecht, Ralph J.; Johnson, Andrew M.

1992-01-01

The HSCT combustor will be required to operate with either extremely rich or lean fuel/air ratios to reduce NO(x) emission. NASA High Speed Research (HSR) sponsored programs at Pratt & Whitney (P&W) and GE Aircraft Engines (GEAE) have been studying rich and lean burn combustor design approaches which are capable of achieving the aggressive HSCT NO(x) emission goals. In both of the combustor design approaches under study, high temperature (2400-3000 F) materials are necessary to meet the HSCT emission goals of 3-8 gm/kg. Currently available materials will not meet the projected requirements for the HSCT combustor. The development of new materials is an enabling technology for the successful introduction to service of the HSCT.

Composite Matrix Cooling Scheme for Small Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Paskin, Marc D.; Ross, Phillip T.; Mongia, Hukam C.; Acosta, Waldo A.

1990-01-01

The design, manufacture, and testing of a compliant metal/ceramic (CMC) wall cooling concept-implementing combustor for small gas turbine engines has been undertaken by a joint U.S. Army/NASA technology development program. CMC in principle promises greater wall cooling effectiveness than conventional designs and materials, thereby facilitating a substantial reduction in combustor cooling air requirements and furnishing greater airflow for the control of burner outlet temperature patterns as well as improving thermodynamic efficiency and reducing pollutant emissions and smoke levels. Rig test results have confirmed the projected benefits of the CMC concept at combustor outlet temperatures of the order of 2460 F, at which approximately 80 percent less cooling air than conventionally required was being employed by the CMC combustor.

Isolator-combustor interaction in a dual-mode scramjet engine

NASA Technical Reports Server (NTRS)

Pratt, David T.; Heiser, William H.

1993-01-01

A constant-area diffuser, or 'isolator', is required in both the ramjet and scramjet operating regimes of a dual-mode engine configuration in order to prevent unstarts due to pressure feedback from the combustor. Because the nature of the combustor-isolator interaction is different in the two operational modes, however, attention is presently given to the use of thermal vs kinetic energy coordinates for these interaction processes' visualization. The results of the analysis thus conducted indicate that the isolator requires severe flow separation at combustor entry, and that its entropy-generating characteristics are more severe than an equivalent oblique shock. A constant-area diffuser is only marginally able to contain the equivalent normal shock required for subsonic combustor entry.

Investigations on the Influence of the In-Stream Pylon and Strut on the Performance of a Scramjet Combustor

PubMed Central

Liu, Weidong; Sun, Mingbo

2014-01-01

The influence of the in-stream pylon and strut on the performance of scramjet combustor was experimentally and numerically investigated. The experiments were conducted with a direct-connect supersonic model combustor equipped with multiple cavities. The entrance parameter of combustor corresponds to scramjet flight Mach number 4.0 with a total temperature of 947 K. The research results show that, compared with the scramjet combustor without pylon and strut, the wall pressure and the thrust of the scramjet increase due to the improvement of mixing and combustion effect due to the pylon and strut. The total pressure loss caused by the strut is considerable whereas pylon influence is slight. PMID:25254234

Swirling midframe flow for gas turbine engine having advanced transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montgomery, Matthew D.; Charron, Richard C.; Rodriguez, Jose L.

A gas turbine engine can-annular combustion arrangement (10), including: an axial compressor (82) operable to rotate in a rotation direction (60); a diffuser (100, 110) configured to receive compressed air (16) from the axial compressor; a plenum (22) configured to receive the compressed air from the diffuser; a plurality of combustor cans (12) each having a combustor inlet (38) in fluid communication with the plenum, wherein each combustor can is tangentially oriented so that a respective combustor inlet is circumferentially offset from a respective combustor outlet in a direction opposite the rotation direction; and an airflow guiding arrangement (80) configuredmore » to impart circumferential motion to the compressed air in the plenum in the direction opposite the rotation direction.« less

Nonintrusive transceiver and method for characterizing temperature and velocity fields in a gas turbine combustor

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeSilva, Upul P.; Claussen, Heiko

An acoustic transceiver is implemented for measuring acoustic properties of a gas in a turbine engine combustor. The transceiver housing defines a measurement chamber and has an opening adapted for attachment to a turbine engine combustor wall. The opening permits propagation of acoustic signals between the gas in the turbine engine combustor and gas in the measurement chamber. An acoustic sensor mounted to the housing receives acoustic signals propagating in the measurement chamber, and an acoustic transmitter mounted to the housing creates acoustic signals within the measurement chamber. An acoustic measurement system includes at least two such transceivers attached tomore » a turbine engine combustor wall and connected to a controller.« less

40 CFR 60.59b - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994 or for Which... the owner or operator plans to combust in the affected facility. (4) The municipal waste combustor..., municipal waste combustor unit load measurements, and particulate matter control device inlet temperatures...

40 CFR 60.59b - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994 or for Which... the owner or operator plans to combust in the affected facility. (4) The municipal waste combustor..., municipal waste combustor unit load measurements, and particulate matter control device inlet temperatures...

40 CFR 60.59b - Reporting and recordkeeping requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Municipal Waste Combustors for Which Construction is Commenced After September 20, 1994 or for Which... the owner or operator plans to combust in the affected facility. (4) The municipal waste combustor..., municipal waste combustor unit load measurements, and particulate matter control device inlet temperatures...

A CFD Study of Jet Mixing in Reduced Flow Areas for Lower Combustor Emissions

NASA Technical Reports Server (NTRS)

Smith, C. E.; Talpallikar, M. V.; Holdeman, J. D.

1991-01-01

The Rich-burn/Quick-mix/Lean-burn (RQL) combustor has the potential of significantly reducing NO(x) emissions in combustion chambers of High Speed Civil Transport aircraft. Previous work on RQL combustors for industrial applications suggested the benefit of necking down the mixing section. A 3-D numerical investigation was performed to study the effects of neckdown on NO(x) emissions and to develop a correlation for optimum mixing designs in terms of neckdown area ratio. The results of the study showed that jet mixing in reduced flow areas does not enhance mixing, but does decrease residence time at high flame temperatures, thus reducing NO(x) formation. By necking down the mixing flow area by 4, a potential NO(x) reduction of 16:1 is possible for annual combustors. However, there is a penalty that accompanies the mixing neckdown: reduced pressure drop across the combustor swirler. At conventional combustor loading parameters, the pressure drop penalty does not appear to be excessive.

Analytical evaluation of the impact of broad specification fuels on high bypass turbofan engine combustors

NASA Technical Reports Server (NTRS)

Taylor, J. R.

1979-01-01

Six conceptual combustor designs for the CF6-50 high bypass turbofan engine and six conceptual combustor designs for the NASA/GE E3 high bypass turbofan engine were analyzed to provide an assessment of the major problems anticipated in using broad specification fuels in these aircraft engine combustion systems. Each of the conceptual combustor designs, which are representative of both state-of-the-art and advanced state-of-the-art combustion systems, was analyzed to estimate combustor performance, durability, and pollutant emissions when using commercial Jet A aviation fuel and when using experimental referee board specification fuel. Results indicate that lean burning, low emissions double annular combustor concepts can accommodate a wide range of fuel properties without a serious deterioration of performance or durability. However, rich burning, single annular concepts would be less tolerant to a relaxation of fuel properties. As the fuel specifications are relaxed, autoignition delay time becomes much smaller which presents a serious design and development problem for premixing-prevaporizing combustion system concepts.

Development and application of an LC-MS/MS method for the detection of the vinyl chloride-induced DNA adduct N2,3-ethenoguanine in tissues of adult and weanling rats following the exposure to [13C2]-VC

EPA Science Inventory

In the 1970s exposure to vinyl chloride (VC) was shown to cause liver angiosarcoma in VC workers. We have developed a new LC-MS/MS method for analyzing the promutagenic DNA adduct N2,3-ethenoguanine and have applied this to DNA from tissues of both adult and weanling rats expose...

Scale and geometry effects on heat-recirculating combustors

NASA Astrophysics Data System (ADS)

Chen, Chien-Hua; Ronney, Paul D.

2013-10-01

A simple analysis of linear and spiral counterflow heat-recirculating combustors was conducted to identify the dimensionless parameters expected to quantify the performance of such devices. A three-dimensional (3D) numerical model of spiral counterflow 'Swiss roll' combustors was then used to confirm and extend the applicability of the identified parameters. It was found that without property adjustment to maintain constant values of these parameters, at low Reynolds number (Re) smaller-scale combustors actually showed better performance (in terms of having lower lean extinction limits at the same Re) due to lower heat loss and internal wall-to-wall radiation effects, whereas at high Re, larger-scale combustors showed better performance due to longer residence time relative to chemical reaction time. By adjustment of property values, it was confirmed that four dimensionless parameters were sufficient to characterise combustor performance at all scales: Re, a heat loss coefficient (α), a Damköhler number (Da) and a radiative transfer number (R). The effect of diffusive transport effect (i.e. Lewis number) was found to be significant only at low Re. Substantial differences were found between the performance of linear and spiral combustors; these were explained in terms of the effects of the area exposed to heat loss to ambient and the sometimes detrimental effect of increasing heat transfer to adjacent outlet turns of the spiral exchanger. These results provide insight into the optimal design of small-scale combustors and choice of operation conditions.

Variable volume combustor

DOEpatents

Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul

2017-01-17

The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.

Diabetes confers in vitro calcific potential on serum which associates with in vivo vascular calcification.

PubMed

Patidar, Ashish; Singh, Dhruv K; Thakur, Shori; Winocour, Peter; Farrington, Ken; Baydoun, Anwar R

2017-05-01

Although vascular calcification (VC) is prevalent in Type 2 diabetes mellitus (T2DM), underlying mechanisms remain unclear. Neither is it known whether T2DM confers calcific potential (CP) on serum, enabling it to induce VC outside the disease milieu. We, therefore, investigated the CP of serum from controls and subjects with T2DM with and without in vivo VC . Samples from 20 healthy controls and 44 age- and sex-matched patients with T2DM with modification of diet in renal disease estimated glomerular filtration rate (MDRD-4 eGFR) > 60 ml·min -1 were analysed for CP using rat aortic smooth muscle cells in vitro CT scans of femoral arteries identified individuals with in vivo calcification. Serum from subjects with T2DM revealed significantly greater CP than controls. This was further enhanced in the presence of in vivo VC. Addition of β-glycerophosphate (β-GP) plus CaCl 2 increased the CP of T2DM serum but not of controls. Along with age, CP was an independent predictor of the presence of VC. In receiver operator curve (ROC) analysis, CP was a significant predictor of femoral arterial VC (C-statistic 0.70: P =0.009). The distribution of CP was bimodal around a cutoff of 100 nmoles of Ca 2+ protein mg -1 , with a higher proportion of Type 2 diabetes subjects with in vivo calcification (T2DM+) sera above the cutoff value. This group also showed elevated levels of osteoprotegerin (OPG) and matrix Gla protein (MGP). Diabetes confers CP on the serum which is enhanced by the presence of in vivo VC. The CP acquired may be dependent on levels of OPG and MGP. These findings may be clinically relevant for early identification of individuals at risk of VC and for informing therapeutic strategies. © 2017 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

The effects of assisted cycling therapy (ACT) and voluntary cycling on reaction time and measures of executive function in adolescents with Down syndrome.

PubMed

Ringenbach, S D R; Holzapfel, S D; Mulvey, G M; Jimenez, A; Benson, A; Richter, M

2016-11-01

Reports of positive effects of aerobic exercise on cognitive function in persons with Down syndrome are extremely limited. However, a novel exercise intervention, termed assisted cycling therapy (ACT), has resulted in acutely improved cognitive planning ability and reaction times as well as improved cognitive planning after 8 weeks of ACT in adolescents and young adults with Down syndrome. Here, we report the effects of 8 weeks of ACT on reaction time, set-shifting, inhibition and language fluency in adolescents with Down syndrome. Adolescents with Down syndrome (age: ~18 years) were randomly assigned to 8 weeks of ACT (n = 17) or voluntary cycling (VC: n = 16), and a convenience sample (n = 11) was assigned to be an inactive comparison group (NC: n = 11). During ACT, the cycling cadence of the participants was augmented to an average cadence that was 80% faster than the voluntary cadence of the VC group. The increase in cadence was achieved with an electric motor in the stationary bicycle. Reaction time, set-shifting, inhibition and language fluency were assessed before and after 8 weeks of intervention. Power output and heart rates of the ACT and VC groups were almost identical, but the ACT cadence was significantly faster. The ACT group, but not the VC or NC groups, showed significantly improved reactions times (Hedges' g = -0.42) and inhibitory control (g = 0.18). Only the VC group showed improved set-shifting ability (g = 0.57). The ACT and VC groups displayed improved semantic language fluency (g = 0.25, g = 0.22, respectively). These and previous results support the hypothesis of increased neuroplasticity and prefrontal cortex function following ACT and, to a smaller extent, following VC. Both ACT and VC appear to be associated with cortical benefits, but based on current and previous results, ACT seems to maximize the benefits. © 2016 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Characterization of Centrifugally-Loaded Flame Migration for Ultra-Compact Combustors

DTIC Science & Technology

2011-10-01

11 T04 combustor exit temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Q b combustor heat addition...11 Q ab afterburner heat addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11...the mass flow rates, with heat addition, lead to reaching a specific g-load. In addition to varying g-load, a larger scale UCC will require a

Variable volume combustor with pre-nozzle fuel injection system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keener, Christopher Paul; Johnson, Thomas Edward; McConnaughhay, Johnie Franklin

The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of fuel nozzles, a pre-nozzle fuel injection system supporting the fuel nozzles, and a linear actuator to maneuver the fuel nozzles and the pre-nozzle fuel injection system.

Chaos in an imperfectly premixed model combustor.

PubMed

Kabiraj, Lipika; Saurabh, Aditya; Karimi, Nader; Sailor, Anna; Mastorakos, Epaminondas; Dowling, Ann P; Paschereit, Christian O

2015-02-01

This article reports nonlinear bifurcations observed in a laboratory scale, turbulent combustor operating under imperfectly premixed mode with global equivalence ratio as the control parameter. The results indicate that the dynamics of thermoacoustic instability correspond to quasi-periodic bifurcation to low-dimensional, deterministic chaos, a route that is common to a variety of dissipative nonlinear systems. The results support the recent identification of bifurcation scenarios in a laminar premixed flame combustor (Kabiraj et al., Chaos: Interdiscip. J. Nonlinear Sci. 22, 023129 (2012)) and extend the observation to a practically relevant combustor configuration.

Review of jet engine emissions

NASA Technical Reports Server (NTRS)

Grobman, J. S.

1972-01-01

A review of the emission characteristics of jet engines is presented. The sources and concentrations of the various constituents in the engine exhaust and the influence of engine operating conditions on emissions are discussed. Cruise emissions to be expected from supersonic engines are compared with emissions from subsonic engines. The basic operating principles of the gas turbine combustor are reviewed together with the effects of combustor operating conditions on emissions. The performance criteria that determine the design of gas turbine combustors are discussed. Combustor design techniques are considered that may be used to reduce emissions.

Quiet Clean Short-haul Experimental Engine (QCSEE). Double-annular clean combustor technology development report

NASA Technical Reports Server (NTRS)

Bahr, D. W.; Burrus, D. L.; Sabla, P. E.

1979-01-01

A sector combustor technology development program was conducted to define an advanced double annular dome combustor sized for use in the quiet clean short haul experimental engine (QCSEE). A design which meets the emission goals, and combustor performance goals of the QCSEE engine program was developed. Key design features were identified which resulted in substantial reduction in carbon monoxide and unburned hydrocarbon emission levels at ground idle operating conditions, in addition to very low nitric oxide emission levels at high power operating conditions. Their significant results are reported.

Process for Operating a Dual-Mode Combustor

NASA Technical Reports Server (NTRS)

Trefny, Charles J. (Inventor); Dippold, Vance F. (Inventor)

2017-01-01

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

Energy efficient engine

NASA Technical Reports Server (NTRS)

Burrus, D.; Sabla, P. E.; Bahr, D. W.

1980-01-01

The feasibility of meeting or closely approaching the emissions goals established for the Energy Efficient Engine (E3) Project with an advanced design, single annular combustor was determined. A total of nine sector combustor configurations and one full-annular-combustor configuration were evaluated. Acceptable levels of carbon monoxide and hydrocarbon emissions were obtained with several of the sector combustor configurations tested, and several of the configurations tested demonstrated reduced levels of nitrogen oxides compared to conventional, single annular designs. None of the configurations tested demonstrated nitrogen oxide emission levels that meet the goal of the E3 Project.

On the modelling of scalar and mass transport in combustor flows

NASA Technical Reports Server (NTRS)

Nikjooy, M.; So, R. M. C.

1989-01-01

Results are presented of a numerical study of swirling and nonswirling combustor flows with and without density variations. Constant-density arguments are used to justify closure assumptions invoked for the transport equations for turbulent momentum and scalar fluxes, which are written in terms of density-weighted variables. Comparisons are carried out with measurements obtained from three different axisymmetric model combustor experiments covering recirculating flow, swirling flow, and variable-density swirling flow inside the model combustors. Results show that the Reynolds stress/flux models do a credible job of predicting constant-density swirling and nonswirling combustor flows with passive scalar transport. However, their improvements over algebraic stress/flux models are marginal. The extension of the constant-density models to variable-density flow calculations shows that the models are equally valid for such flows.

Phase I Final Scientific Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Xijia; Fetvedt, Jeremy; Dimmig, Walker

This Final Scientific Report addresses the accomplishments achieved during Phase I of DE- FE0023985, Coal Syngas Combustor Development for Supercritical CO 2 Power Cycles. The primary objective of the project was to develop a coal syngas-fueled combustor design for use with high-pressure, high-temperature, oxy-fuel, supercritical CO 2 power cycles, with particular focus given to the conditions required by the Allam Cycle. The primary goals, from the Statement of Project Objectives, were to develop: (1) a conceptual design of a syngas-fueled combustor-turbine block for a 300MWe high-pressure, oxy-fuel, sCO2 power plant; (2) the preliminary design of a 5MWt test combustor; andmore » (3) the definition of a combustor test program. Accomplishments for each of these goals are discussed in this report.« less

Method for operating a combustor in a fuel cell system

DOEpatents

Chalfant, Robert W.; Clingerman, Bruce J.

2002-01-01

A method of operating a combustor to heat a fuel processor in a fuel cell system, in which the fuel processor generates a hydrogen-rich stream a portion of which is consumed in a fuel cell stack and a portion of which is discharged from the fuel cell stack and supplied to the combustor, and wherein first and second streams are supplied to the combustor, the first stream being a hydrocarbon fuel stream and the second stream consisting of said hydrogen-rich stream, the method comprising the steps of monitoring the temperature of the fuel processor; regulating the quantity of the first stream to the combustor according to the temperature of the fuel processor; and comparing said quantity of said first stream to a predetermined value or range of predetermined values.

Advanced Low-Emissions Catalytic-Combustor Program, phase 1. [aircraft gas turbine engines

NASA Technical Reports Server (NTRS)

Sturgess, G. J.

1981-01-01

Six catalytic combustor concepts were defined, analyzed, and evaluated. Major design considerations included low emissions, performance, safety, durability, installations, operations and development. On the basis of these considerations the two most promising concepts were selected. Refined analysis and preliminary design work was conducted on these two concepts. The selected concepts were required to fit within the combustor chamber dimensions of the reference engine. This is achieved by using a dump diffuser discharging into a plenum chamber between the compressor discharge and the turbine inlet, with the combustors overlaying the prediffuser and the rear of the compressor. To enhance maintainability, the outer combustor case for each concept is designed to translate forward for accessibility to the catalytic reactor, liners and high pressure turbine area. The catalytic reactor is self-contained with air-cooled canning on a resilient mounting. Both selected concepts employed integrated engine-starting approaches to raise the catalytic reactor up to operating conditions. Advanced liner schemes are used to minimize required cooling air. The two selected concepts respectively employ fuel-rich initial thermal reaction followed by rapid quench and subsequent fuel-lean catalytic reaction of carbon monoxide, and, fuel-lean thermal reaction of some fuel in a continuously operating pilot combustor with fuel-lean catalytic reaction of remaining fuel in a radially-staged main combustor.

Low NOx, Lean Direct Wall Injection Combustor Concept Developed

NASA Technical Reports Server (NTRS)

Tacina, Robert R.; Wey, Changlie; Choi, Kyung J.

2003-01-01

The low-emissions combustor development at the NASA Glenn Research Center is directed toward advanced high-pressure aircraft gas turbine applications. The emphasis of this research is to reduce nitrogen oxides (NOx) at high-power conditions and to maintain carbon monoxide and unburned hydrocarbons at their current low levels at low-power conditions. Low-NOx combustors can be classified into rich burn and lean burn concepts. Lean burn combustors can be further classified into lean-premixed-prevaporized (LPP) and lean direct injection (LDI) combustors. In both concepts, all the combustor air, except for liner cooling flow, enters through the combustor dome so that the combustion occurs at the lowest possible flame temperature. The LPP concept has been shown to have the lowest NOx emissions, but for advanced high-pressure-ratio engines, the possibly of autoignition or flashback precludes its use. LDI differs from LPP in that the fuel is injected directly into the flame zone and, thus, does not have the potential for autoignition or flashback and should have greater stability. However, since it is not premixed and prevaporized, the key is good atomization and mixing of the fuel quickly and uniformly so that flame temperatures are low and NOx formation levels are comparable to those of LPP.

A Design Methodology for Rapid Implementation of Active Control Systems Across Lean Direct Injection Combustor Platforms

NASA Technical Reports Server (NTRS)

Baumann, William T.; Saunders, William R.; Vandsburger, Uri; Saus, Joseph (Technical Monitor)

2003-01-01

The VACCG team is comprised of engineers at Virginia Tech who specialize in the subject areas of combustion physics, chemical kinetics, dynamics and controls, and signal processing. Currently, the team's work on this NRA research grant is designed to determine key factors that influence combustion control performance through a blend of theoretical and experimental investigations targeting design and demonstration of active control for three different combustors. To validiate the accuracy of conclusions about control effectiveness, a sequence of experimental verifications on increasingly complex lean, direct injection combustors is underway. During the work period January 1, 2002 through October 15, 2002, work has focused on two different laboratory-scale combustors that allow access for a wide variety of measurements. As the grant work proceeds, one key goal will be to obtain certain knowledge about a particular combustor process using a minimum of sophisticated measurements, due to the practical limitations of measurements on full-scale combustors. In the second year, results obtained in the first year will be validated on test combustors to be identified in the first quarter of that year. In the third year, it is proposed to validate the results at more realistic pressure and power levels by utilizing the facilities at the Glenn Research Center.

Control of the Development of Swirling Airflow Dynamics and Its Impact on Biomass Combustion Characteristics

NASA Astrophysics Data System (ADS)

Barmina, I.; Valdmanis, R.; Zaķe, M.

2017-06-01

The development of the swirling flame flow field and gasification/ combustion dynamics at thermo-chemical conversion of biomass pellets has experimentally been studied using a pilot device, which combines a biomass gasifier and combustor by varying the inlet conditions of the fuel-air mixture into the combustor. Experimental modelling of the formation of the cold nonreacting swirling airflow field above the inlet nozzle of the combustor and the upstream flow formation below the inlet nozzle has been carried out to assess the influence of the inlet nozzle diameter, as well primary and secondary air supply rates on the upstream flow formation and air swirl intensity, which is highly responsible for the formation of fuel-air mixture entering the combustor and the development of combustion dynamics downstream of the combustor. The research results demonstrate that at equal primary axial and secondary swirling air supply into the device a decrease in the inlet nozzle diameter enhances the upstream air swirl formation by increasing swirl intensity below the inlet nozzle of the combustor. This leads to the enhanced mixing of the combustible volatiles with the air swirl below the inlet nozzle of the combustor providing a more complete combustion of volatiles and an increase in the heat output of the device.

Ejector-Enhanced, Pulsed, Pressure-Gain Combustor

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Dougherty, Kevin T.

2009-01-01

An experimental combination of an off-the-shelf valved pulsejet combustor and an aerodynamically optimized ejector has shown promise as a prototype of improved combustors for gas turbine engines. Despite their name, the constant pressure combustors heretofore used in gas turbine engines exhibit typical pressure losses ranging from 4 to 8 percent of the total pressures delivered by upstream compressors. In contrast, the present ejector-enhanced pulsejet combustor exhibits a pressure rise of about 3.5 percent at overall enthalpy and temperature ratios compatible with those of modern turbomachines. The modest pressure rise translates to a comparable increase in overall engine efficiency and, consequently, a comparable decrease in specific fuel consumption. The ejector-enhanced pulsejet combustor may also offer potential for reducing the emission of harmful exhaust compounds by making it practical to employ a low-loss rich-burn/quench/lean-burn sequence. Like all prior concepts for pressure-gain combustion, the present concept involves an approximation of constant-volume combustion, which is inherently unsteady (in this case, more specifically, cyclic). The consequent unsteadiness in combustor exit flow is generally regarded as detrimental to the performance of downstream turbomachinery. Among other adverse effects, this unsteadiness tends to detract from the thermodynamic benefits of pressure gain. Therefore, it is desirable in any intermittent combustion process to minimize unsteadiness in the exhaust path.

Flow Coupling Effects in Jet-in-Crossflow Flowfields

NASA Technical Reports Server (NTRS)

Bain, D. B.; Smith, C. E.; Liscinsky, D. S.; Holdeman, J. D.

1996-01-01

The combustor designer is typically required to design liner orifices that effectively mix air jets with crossflow effluent. CFD combustor analysis is typically used in the design process; however the jets are usually assumed to enter the combustor with a uniform velocity and turbulence profile. The jet-mainstream flow coupling is usually neglected because of the computational expense. This CFD study was performed to understand the effect of jet-mainstream flow coupling, and to assess the accuracy of jet boundary conditions that are commonly used in combustor internal calculations. A case representative of a plenum-fed quick-mix section of a Rich Burn/Quick Mix/Lean Burn combustor (i.e. a jet-mainstream mass-flow ratio of about 3 and a jet-mainstream momentum-flux ratio of about 30) was investigated. This case showed that the jet velocity entering the combustor was very non-uniform, with a low normal velocity at the leading edge of the orifice and a high normal velocity at the trailing edge of the orifice. Three different combustor-only cases were analyzed with uniform inlet jet profile. None of the cases matched the plenum-fed calculations. To assess liner thickness effects, a thin-walled case was also analyzed. The CFD analysis showed the thin-walled jets had more penetration than the thick-walled jets.

Challenges to Laser-Based Imaging Techniques in Gas Turbine Combustor Systems for Aerospace Applications

NASA Technical Reports Server (NTRS)

Locke, Randy J.; Anderson, Robert C.; Zaller, Michelle M.; Hicks, Yolanda R.

1998-01-01

Increasingly severe constraints on emissions, noise and fuel efficiency must be met by the next generation of commercial aircraft powerplants. At NASA Lewis Research Center (LeRC) a cooperative research effort with industry is underway to design and test combustors that will meet these requirements. To accomplish these tasks, it is necessary to gain both a detailed understanding of the combustion processes and a precise knowledge of combustor and combustor sub-component performance at close to actual conditions. To that end, researchers at LeRC are engaged in a comprehensive diagnostic investigation of high pressure reacting flowfields that duplicate conditions expected within the actual engine combustors. Unique, optically accessible flame-tubes and sector rig combustors, designed especially for these tests. afford the opportunity to probe these flowfields with the most advanced, laser-based optical diagnostic techniques. However, these same techniques, tested and proven on comparatively simple bench-top gaseous flame burners, encounter numerous restrictions and challenges when applied in these facilities. These include high pressures and temperatures, large flow rates, liquid fuels, remote testing, and carbon or other material deposits on combustor windows. Results are shown that document the success and versatility of these nonintrusive optical diagnostics despite the challenges to their implementation in realistic systems.

Large eddy simulation of combustion characteristics in a kerosene fueled rocket-based combined-cycle engine combustor

NASA Astrophysics Data System (ADS)

Huang, Zhi-wei; He, Guo-qiang; Qin, Fei; Cao, Dong-gang; Wei, Xiang-geng; Shi, Lei

2016-10-01

This study reports combustion characteristics of a rocket-based combined-cycle engine combustor operating at ramjet mode numerically. Compressible large eddy simulation with liquid kerosene sprayed and vaporized is used to study the intrinsic unsteadiness of combustion in such a propulsion system. Results for the pressure oscillation amplitude and frequency in the combustor as well as the wall pressure distribution along the flow-path, are validated using experimental data, and they show acceptable agreement. Coupled with reduced chemical kinetics of kerosene, results are compared with the simultaneously obtained Reynolds-Averaged Navier-Stokes results, and show significant differences. A flow field analysis is also carried out for further study of the turbulent flame structures. Mixture fraction is used to determine the most probable flame location in the combustor at stoichiometric condition. Spatial distributions of the Takeno flame index, scalar dissipation rate, and heat release rate reveal that different combustion modes, such as premixed and non-premixed modes, coexisted at different sections of the combustor. The RBCC combustor is divided into different regions characterized by their non-uniform features. Flame stabilization mechanism, i.e., flame propagation or fuel auto-ignition, and their relative importance, is also determined at different regions in the combustor.

Growth and FIB-SEM analyses of C60 microtubes vertically synthesized on porous alumina membranes

NASA Astrophysics Data System (ADS)

Miyazawa, Kun'ichi; Kuriyama, Ryota; Shimomura, Shuichi; Wakahara, Takatsugu; Tachibana, Masaru

2014-02-01

The vertical growth of C60 microtubes (C60MTs) on anodic aluminum oxide (AAO) membranes was investigated. The C60MT size dependence on isopropyl alcohol (IPA) injection rate, into C60-saturated toluene solutions through AAO membranes, was measured. A longitudinal section of the interface between a vertically grown C60MT (V-C60MT) and a membrane was prepared by focused ion beam processing, and observed with scanning electron microscopy. No cracking was observed along the interface, suggesting good bonding. V-C60MTs exhibited spiral growth. V-C60MT planar density, wall thickness and aspect ratio all decreased with increasing IPA injection rate. The relationships among length, inner and outer diameters of V-C60MTs were also investigated by varying IPA injection rate.

Volumetric capnography curves as lung function test to confirm bronchoconstriction after carbachol challenge in sedated dogs.

PubMed

Scheffzek, S; Mosing, M; Hirt, R; Iff, I; Moens, Y

2012-12-01

This study investigated volumetric capnography (VC) in detecting airway responsiveness following airway challenge using carbachol in seven sedated dogs via face mask. Nebulised saline was administered, followed by increasing concentrations of nebulised carbachol until airflow limitation occurred (EP). Dead space (DS) variables and shape indices of the VC curve were calculated automatically after entering arterial carbon dioxide tension. Airway DS, airway DS to tidal volume (VT) ratio and the intercept of slope 2 of the VC curve decreased significantly at EP by 10%, 13% and 16%, respectively, minute ventilation, VT and alveolar DS increased significantly at EP by 49%, 22% and 200%, respectively. We conclude that VC and derived indices may be used to verify a reaction to airway challenge caused by carbachol in sedated dogs. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of Caffeic Acid Phenethyl Ester and 4-Vinylcatechol on the Stabilities of Oil-in-Water Emulsions of Stripped Soybean Oil.

PubMed

Jia, Cai-Hua; Shin, Jung-Ah; Lee, Ki-Teak

2015-12-02

Caffeic acid phenethyl ester (CAPE) and 4-vinylcatechol (4-VC) were prepared for studying their antioxidative activities in emulsion. Oil-in-water emulsions of stripped soybean oil containing 200 ppm of CAPE, 4-VC, or α-tocopherol were stored at 40 °C in the dark for 50 days, and proton nuclear magnetic resonance ((1)H NMR) was used to identify and quantify the oxidation products. Emulsion droplet sizes, peroxide values, and levels of primary oxidation products (i.e., hydroperoxides) and secondary oxidation products (i.e., aldehydes) were determined. The results showed that CAPE (200 ppm) and 4-VC (200 ppm) had significantly greater antioxidant activities on the oxidation of stripped soybean oil-in-water emulsions than α-tocopherol (200 ppm). The peroxide values of CAPE (8.4 mequiv/L emulsion) and 4-VC (15.0 mequiv/L emulsion) were significantly lower than that of α-tocopherol (33.4 mequiv/L emulsion) (p < 0.05) on 36 days. In addition, the combinations of CAPE + α-tocopherol (100 + 100 ppm) or 4-VC + α-tocopherol (100 + 100 ppm) had better antioxidant activities than α-tocopherol (200 ppm). For CAPE + α-tocopherol, 4-VC + α-tocopherol, and α-tocopherol, the amounts of conjugated diene forms were 16.67, 13.72, and 16.32 mmol/L emulsion, and the concentrations of aldehydes were 2.15, 1.13, and 4.26 mmol/L emulsion, respectively, after 50 days of storage.

BRIC-100VC Biological Research in Canisters (BRIC)-100VC

NASA Technical Reports Server (NTRS)

Richards, Stephanie E.; Levine, Howard G. (Compiler); Romero, Vergel

2016-01-01

The Biological Research in Canisters (BRIC) is an anodized-aluminum cylinder used to provide passive stowage for investigations of the effects of space flight on small specimens. The BRIC 100 mm petri dish vacuum containment unit (BRIC-100VC) has supported Dugesia japonica (flatworm) within spring under normal atmospheric conditions for 29 days in space and Hemerocallis lilioasphodelus L. (daylily) somatic embryo development within a 5% CO2 gaseous environment for 4.5 months in space. BRIC-100VC is a completely sealed, anodized-aluminum cylinder (Fig. 1) providing containment and structural support of the experimental specimens. The top and bottom lids of the canister include rapid disconnect valves for filling the canister with selected gases. These specialized valves allow for specific atmospheric containment within the canister, providing a gaseous environment defined by the investigator. Additionally, the top lid has been designed with a toggle latch and O-ring assembly allowing for prompt sealing and removal of the lid. The outside dimensions of the BRIC-100VC canisters are 16.0 cm (height) x 11.4 cm (outside diameter). The lower portion of the canister has been equipped with sufficient storage space for passive temperature and relative humidity data loggers. The BRIC- 100VC canister has been optimized to accommodate standard 100 mm laboratory petri dishes or 50 mL conical tubes. Depending on storage orientation, up to 6 or 9 canisters have been flown within an International Space Station (ISS) stowage locker.

The Vibrio cholerae Mrp system: cation/proton antiport properties and enhancement of bile salt resistance in a heterologous host.

PubMed

Dzioba-Winogrodzki, Judith; Winogrodzki, Olga; Krulwich, Terry A; Boin, Markus A; Häse, Claudia C; Dibrov, Pavel

2009-01-01

The mrp operon from Vibrio cholerae encoding a putative multisubunit Na(+)/H(+) antiporter was cloned and functionally expressed in the antiporter-deficient strain of Escherichia coli EP432. Cells of EP432 expressing Vc-Mrp exhibited resistance to Na(+) and Li(+) as well as to natural bile salts such as sodium cholate and taurocholate. When assayed in everted membrane vesicles of the E. coli EP432 host, Vc-Mrp had sufficiently high antiport activity to facilitate the first extensive analysis of Mrp system from a Gram-negative bacterium encoded by a group 2 mrp operon. Vc-Mrp was found to exchange protons for Li(+), Na(+), and K(+) ions in pH-dependent manner with maximal activity at pH 9.0-9.5. Exchange was electrogenic (more than one H(+) translocated per cation moved in opposite direction). The apparent K(m) at pH 9.0 was 1.08, 1.30, and 68.5 mM for Li(+), Na(+), and K(+), respectively. Kinetic analyses suggested that Vc-Mrp operates in a binding exchange mode with all cations and protons competing for binding to the antiporter. The robust ion antiport activity of Vc-Mrp in sub-bacterial vesicles and its effect on bile resistance of the heterologous host make Vc-Mrp an attractive experimental model for the further studies of biochemistry and physiology of Mrp systems. Copyright 2008 S. Karger AG, Basel.

Double negatively charged carbon vacancy at the h- and k-sites in 4H-SiC: Combined Laplace-DLTS and DFT study

NASA Astrophysics Data System (ADS)

Capan, Ivana; Brodar, Tomislav; Pastuović, Željko; Siegele, Rainer; Ohshima, Takeshi; Sato, Shin-ichiro; Makino, Takahiro; Snoj, Luka; Radulović, Vladimir; Coutinho, José; Torres, Vitor J. B.; Demmouche, Kamel

2018-04-01

We present results from combined Laplace-Deep Level Transient Spectroscopy (Laplace-DLTS) and density functional theory studies of the carbon vacancy (VC) in n-type 4H-SiC. Using Laplace-DLTS, we were able to distinguish two previously unresolved sub-lattice-inequivalent emissions, causing the broad Z1/2 peak at 290 K that is commonly observed by conventional DLTS in n-type 4H-SiC. This peak has two components with activation energies for electron emission of 0.58 eV and 0.65 eV. We compared these results with the acceptor levels of VC obtained by means of hybrid density functional supercell calculations. The calculations support the assignment of the Z1/2 signal to a superposition of emission peaks from double negatively charged VC defects. Taking into account the measured and calculated energy levels, the calculated relative stability of VC in hexagonal (h) and cubic (k) lattice sites, as well as the observed relative amplitude of the Laplace-DLTS peaks, we assign Z1 and Z2 to VC(h) and VC(k), respectively. We also present the preliminary results of DLTS and Laplace-DLTS measurements on deep level defects (ET1 and ET2) introduced by fast neutron irradiation and He ion implantation in 4H-SiC. The origin of ET1 and ET2 is still unclear.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

NASA Astrophysics Data System (ADS)

Lorah, Michelle M.; Voytek, Mary A.

2004-05-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Potential for Microbial Degradation of cis-Dichloroethene and Vinyl Chloride in Streambed Sediment at the U.S. Department of Energy, Kansas City Plant, Missouri, 2008

USGS Publications Warehouse

Bradley, Paul M.

2009-01-01

A series of carbon-14 (14C) radiotracer-based microcosm experiments was conducted to assess the mechanisms and products of degradation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) in streambed sediments at the U.S. Department of Energy, Kansas City Plant in Kansas City, Missouri. The focus of the investigation was the potential for biotic and abiotic cis-DCE and VC degradation in surficial and underlying hyporheic sediment from the Blue River and its tributaries, Indian Creek and Boone Creek. Substantial degradation of [1,2-14C] cis-DCE and [1,2-14C] VC to 14C-carbon dioxide (14CO2) was observed in all viable surficial sediment microcosms prepared under oxic conditions. No significant accumulation of reductive dechlorination products was observed under these oxic incubation conditions. The results indicate that microbial mineralization processes involving direct oxidation or co-metabolic oxidation are the primary mechanisms of cis-DCE and VC biodegradation in oxic stream sediment at the Kansas City Plant. Substantial mineralization of [1,2-14C] VC also was observed in all viable surficial sediment microcosms incubated in the absence of detectable oxygen (dissolved oxygen concentrations less than 25 micrograms per liter). In general, the accumulation of mineralization products (14CO2 and 14C-methane [14CH4]) predominated with only trace-level detection of the reductive dechlorination product, 14C-ethene. In contrast, microbial degradation of [1,2-14C] cis-DCE by reductive dechlorination or mineralization was not significant in the absence of detectable oxygen. The potential for [1,2-14C] VC biodegradation also was significant in sediments from the deeper hyporheic zones under oxic conditions and in the absence of detectable oxygen. In this study, microbial degradation of [1,2-14C] cis-DCE was not significant in hyporheic sediment treatments under either oxygen condition. Taken together, the results indicate that microbial mineralization processes in streambed sediments at the Kansas City Plant can be an important component of cis-DCE and VC degradation under oxic conditions and of VC degradation even in the absence of detectable oxygen. These results demonstrate that an evaluation of the efficiency of in situ cis-DCE and VC biodegradation in streambed sediments, based solely on observed accumulations of reduced daughter products, may underestimate substantially the total extent of contaminant biodegradation and, thus, the potential importance of the hyporheic zone and streambed sediments as barriers to the discharge of contaminated groundwater.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, Michelle M.; Voytek, Mary A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction.Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Degradation of 1,1,2,2-tetrachloroethane and accumulation of vinyl chloride in wetland sediment microcosms and in situ porewater: Biogeochemical controls and associations with microbial communities

USGS Publications Warehouse

Lorah, M.M.; Voytek, M.A.

2004-01-01

The biodegradation pathways of 1,1,2,2-tetrachloroethane (TeCA) and 1,1,2-trichloroethane (112TCA) and the associated microbial communities in anaerobic wetland sediments were evaluated using concurrent geochemical and genetic analyses over time in laboratory microcosm experiments. Experimental results were compared to in situ porewater data in the wetland to better understand the factors controlling daughter product distributions in a chlorinated solvent plume discharging to a freshwater tidal wetland at Aberdeen Proving Ground, Maryland. Microcosms constructed with wetland sediment from two sites showed little difference in the initial degradation steps of TeCA, which included simultaneous hydrogenolysis to 112TCA and dichloroelimination to 1,2-dichloroethene (12DCE). The microcosms from the two sites showed a substantial difference, however, in the relative dominance of subsequent dichloroelimination of 112TCA. A greater dominance of 112TCA dichloroelimination in microcosms constructed with sediment that was initially iron-reducing and subsequently simultaneously iron-reducing and methanogenic caused approximately twice as much vinyl chloride (VC) production as microcosms constructed with sediment that was methanogenic only throughout the incubation. The microcosms with higher VC production also showed substantially more rapid VC degradation. Field measurements of redox-sensitive constituents, TeCA, and its anaerobic degradation products along flowpaths in the wetland porewater also showed greater production and degradation of VC with concurrent methanogenesis and iron reduction. Molecular fingerprinting indicated that bacterial species [represented by a peak at a fragment size of 198 base pairs (bp) by MnlI digest] are associated with VC production from 112TCA dichloroelimination, whereas methanogens (190 and 307 bp) from the Methanococcales or Methanobacteriales family are associated with VC production from 12DCE hydrogenolysis. Acetate-utilizing methanogens (acetotrophs) appear to be involved in the biodegradation of VC. The relative abundance of Methanosarcinaceae, the only methanogen group with acetotrophic members, doubled in microcosms in which degradation of VC was observed. In addition, molecular analyses using primers specific for known dehalorespiring bacteria in the Dehalococcoides and Desulfuromonas groups showed the presence of these bacteria in microcosm slurry from the site that showed the highest VC production and degradation. Determination of biogeochemical controls and microbial consortia involved in TeCA degradation is leading to a better understanding of the heterogeneity in biodegradation rates and daughter product distribution in the wetland, improving capabilities for developing remediation and monitoring plans.

Fate and Transport Modeling of Selected Chlorinated Organic Compounds at Hangar 1000, U.S. Naval Air Station, Jacksonville, Florida

USGS Publications Warehouse

Davis, J. Hal

2003-01-01

The Jacksonville Naval Air Station occupies 3,800 acres adjacent to the St. Johns River in Jacksonville, Florida. Two underground storage tanks at Hangar 1000 contained solvents from the late 1960s until they were removed in 1994. Ground-water samples at one of the tank sites had levels of trichloroethene (TCE) and total dichloroethene (DCE) of 8,710 micrograms per liter (mg/L) and 4,280 mg/L, respectively. Vinyl chloride (VC) at the site is the result of the biodegradation of DCE. Ground water beneath Hangar 1000 flows toward a storm sewer. TCE and DCE plumes travel with the ground water and presumably have reached the storm sewer, which discharges to the St. Johns River. Simulation of solute transport indicates that the traveltime from the storage tank site to the storm sewer is 16, 14, and 12 years for TCE, DCE, and VC respectively. TCE has the longest traveltime because it has the highest retardation factor at 2.5, DCE takes less time with a retardation factor of 2.0, and VC has the quickest traveltime because it has the lowest retardation factor of 1.7. Based on modeling results, the release of contaminants in the aquifer occurred more than 16 years ago. Model-derived dispersivity values at Hangar 1000 were: longitudinal 1.5 feet (ft), transverse 0.27 ft, and vertical 0.27 ft. The model-derived first order decay rates for biodegradation of TCE, DCE, and VC were 0.0002 per day (d-1), 0.0002 d-1, and 0.06 d-1, respectively. These rates are equivalent to half-lives of 13.7 years for TCE and DCE and 17 days for VC. Source area reductions in contaminant concentrations of 50 and 100 percent were modeled to simulate remediation. As expected, reducing the source concentration by 50 percent resulted in eventual TCE, DCE, and VC concentrations that were half of the original concentrations. About 16 years were needed for new steady-state TCE concentrations to develop, about 14 years for DCE, and about 12 years for VC. Reducing the source area concentrations by 100 percent in the model eventually resulted in zero concentrations of TCE, DCE, and VC. The modeled period of time for the contaminants to be removed from the aquifer once the source was removed was about 17 years for TCE, 15 years for DCE, and 13 years for VC.

Estimating the uncertainty in thermochemical calculations for oxygen-hydrogen combustors

NASA Astrophysics Data System (ADS)

Sims, Joseph David

The thermochemistry program CEA2 was combined with the statistical thermodynamics program PAC99 in a Monte Carlo simulation to determine the uncertainty in several CEA2 output variables due to uncertainty in thermodynamic reference values for the reactant and combustion species. In all, six typical performance parameters were examined, along with the required intermediate calculations (five gas properties and eight stoichiometric coefficients), for three hydrogen-oxygen combustors: a main combustor, an oxidizer preburner and a fuel preburner. The three combustors were analyzed in two different modes: design mode, where, for the first time, the uncertainty in thermodynamic reference values---taken from the literature---was considered (inputs to CEA2 were specified and so had no uncertainty); and data reduction mode, where inputs to CEA2 did have uncertainty. The inputs to CEA2 were contrived experimental measurements that were intended to represent the typical combustor testing facility. In design mode, uncertainties in the performance parameters were on the order of 0.1% for the main combustor, on the order of 0.05% for the oxidizer preburner and on the order of 0.01% for the fuel preburner. Thermodynamic reference values for H2O were the dominant sources of uncertainty, as was the assigned enthalpy for liquid oxygen. In data reduction mode, uncertainties in performance parameters increased significantly as a result of the uncertainties in experimental measurements compared to uncertainties in thermodynamic reference values. Main combustor and fuel preburner theoretical performance values had uncertainties of about 0.5%, while the oxidizer preburner had nearly 2%. Associated experimentally-determined performance values for all three combustors were 3% to 4%. The dominant sources of uncertainty in this mode were the propellant flowrates. These results only apply to hydrogen-oxygen combustors and should not be generalized to every propellant combination. Species for a hydrogen-oxygen system are relatively simple, thereby resulting in low thermodynamic reference value uncertainties. Hydrocarbon combustors, solid rocket motors and hybrid rocket motors have combustion gases containing complex molecules that will likely have thermodynamic reference values with large uncertainties. Thus, every chemical system should be analyzed in a similar manner as that shown in this work.

An experimental study of the stable and unstable operation of an LPP gas turbine combustor

NASA Astrophysics Data System (ADS)

Dhanuka, Sulabh Kumar

A study was performed to better understand the stable operation of an LPP combustor and formulate a mechanism behind the unstable operation. A unique combustor facility was developed at the University of Michigan that incorporates the latest injector developed by GE Aircraft Engines and enables operation at elevated pressures with preheated air at flow-rates reflective of actual conditions. The large optical access has enabled the use of a multitude of state-of-the-art laser diagnostics such as PIV and PLIF, and has shed invaluable light not only into the GE injector specifically but also into gas turbine combustors in general. Results from Particle Imaging Velocimetry (PIV) have illustrated the role of velocity, instantaneous vortices, and key recirculation zones that are all critical to the combustor's operation. It was found that considerable differences exist between the iso-thermal and reacting flows, and between the instantaneous and mean flow fields. To image the flame, Planar Laser Induced Fluorescence (PLIF) of the formaldehyde radical was successfully utilized for the first time in a Jet-A flame. Parameters regarding the flame's location and structure have been obtained that assist in interpreting the velocity results. These results have also shown that some of the fuel injected from the main fuel injectors actually reacts in the diffusion flame of the pilot. The unstable operation of the combustor was studied in depth to obtain the stability limits of the combustor, behavior of the flame dynamics, and frequencies of the oscillations. Results from simultaneous pressure and high speed chemiluminescence images have shown that the low frequency dynamics can be characterized as flashback oscillations. The results have also shown that the stability of the combustor can be explained by simple and well established premixed flame stability mechanisms. This study has allowed the development of a model that describes the instability mechanism and accurately captures the frequencies of the oscillations. By demonstrating how these classical understandings can be applied to the extremely complicated flow within LPP gas turbine combustors, new insight has been provided that will aid in the development of the next generation of cleaner, more stable gas turbine combustors.

A Comparison of Combustor-Noise Models

NASA Technical Reports Server (NTRS)

Hultgren, Lennart S.

2012-01-01

The present status of combustor-noise prediction in the NASA Aircraft Noise Prediction Program (ANOPP)1 for current-generation (N) turbofan engines is summarized. Several semi-empirical models for turbofan combustor noise are discussed, including best methods for near-term updates to ANOPP. An alternate turbine-transmission factor2 will appear as a user selectable option in the combustor-noise module GECOR in the next release. The three-spectrum model proposed by Stone et al.3 for GE turbofan-engine combustor noise is discussed and compared with ANOPP predictions for several relevant cases. Based on the results presented herein and in their report,3 it is recommended that the application of this fully empirical combustor-noise prediction method be limited to situations involving only General-Electric turbofan engines. Long-term needs and challenges for the N+1 through N+3 time frame are discussed. Because the impact of other propulsion-noise sources continues to be reduced due to turbofan design trends, advances in noise-mitigation techniques, and expected aircraft configuration changes, the relative importance of core noise is expected to greatly increase in the future. The noise-source structure in the combustor, including the indirect one, and the effects of the propagation path through the engine and exhaust nozzle need to be better understood. In particular, the acoustic consequences of the expected trends toward smaller, highly efficient gas-generator cores and low-emission fuel-flexible combustors need to be fully investigated since future designs are quite likely to fall outside of the parameter space of existing (semi-empirical) prediction tools.

Characterization and Simulation of the Thermoacoustic Instability Behavior of an Advanced, Low Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Paxson, Daniel E.

2008-01-01

Extensive research is being done toward the development of ultra-low-emissions combustors for aircraft gas turbine engines. However, these combustors have an increased susceptibility to thermoacoustic instabilities. This type of instability was recently observed in an advanced, low emissions combustor prototype installed in a NASA Glenn Research Center test stand. The instability produces pressure oscillations that grow with increasing fuel/air ratio, preventing full power operation. The instability behavior makes the combustor a potentially useful test bed for research into active control methods for combustion instability suppression. The instability behavior was characterized by operating the combustor at various pressures, temperatures, and fuel and air flows representative of operation within an aircraft gas turbine engine. Trends in instability behavior versus operating condition have been identified and documented, and possible explanations for the trends provided. A simulation developed at NASA Glenn captures the observed instability behavior. The physics-based simulation includes the relevant physical features of the combustor and test rig, employs a Sectored 1-D approach, includes simplified reaction equations, and provides time-accurate results. A computationally efficient method is used for area transitions, which decreases run times and allows the simulation to be used for parametric studies, including control method investigations. Simulation results show that the simulation exhibits a self-starting, self-sustained combustion instability and also replicates the experimentally observed instability trends versus operating condition. Future plans are to use the simulation to investigate active control strategies to suppress combustion instabilities and then to experimentally demonstrate active instability suppression with the low emissions combustor prototype, enabling full power, stable operation.

Low-nitrogen oxides combustion of dried sludge using a pilot-scale cyclone combustor with recirculation.

PubMed

Shim, Sung Hoon; Jeong, Sang Hyun; Lee, Sang-Sup

2015-04-01

Recently, numerical and experimental studies have been conducted to develop a moderate or intense low-oxygen dilution (MILD) combustion technology for solid fuels. The study results demonstrated that intense recirculation inside the furnace by high-momentum air is a key parameter to achieve the MILD combustion of solid fuels. However, the high-velocity air requires a significant amount of electricity consumption. A cyclone-type MILD combustor was therefore designed and constructed in the authors' laboratory to improve the recirculation inside the combustor. The laboratory-scale tests yielded promising results for the MILD combustion of dried sewage sludge. To achieve pilot-scale MILD combustion of dried sludge in this study, the effects of geometric parameters such as the venturi tube configuration, the air injection location, and the air nozzle diameter were investigated. With the optimized geometric and operational conditions, the pilot-scale cyclone combustor demonstrated successful MILD combustion of dried sludge at a rate of 75 kg/hr with an excess air ratio of 1.05. A horizontal cyclone combustor with recirculation demonstrated moderate or intense low-oxygen dilution (MILD) combustion of dried sewage sludge at a rate of 75 kg/hr. Optimizing only geometric and operational conditions of the combustor reduced nitrogen oxide (NOx) emissions to less than 75 ppm. Because the operating cost of the MILD combustor is much lower than that of the selective catalytic reduction (SCR) applied to the conventional combustor, MILD combustion technology with the cyclone type furnace is an eligible option for reducing NOx emissions from the combustion of dried sewage sludge.

Flow interaction in the combustor-diffusor system of industrial gas turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agrawal, A.K.; Kapat, J.S.; Yang, T.

1996-05-01

This paper presents an experimental/computational study of cold flow in the combustor-diffuser system of industrial gas turbines to address issues relating to flow interactions and pressure losses in the pre- and dump diffusers. The present configuration with can annular combustors differs substantially from the aircraft engines which typically use a 360 degree annular combustor. Experiments were conducted in a one-third scale, annular 360-degree model using several can combustors equispaced around the turbine axis. A 3-D computational fluid dynamics analysis employing the multidomain procedure was performed to supplement the flow measurements. The measured data correlated well with the computations. The airflowmore » in the dump diffuser adversely affected the prediffuser flow by causing it to accelerate in the outer region at the prediffuser exit. This phenomenon referred to as the sink-effect also caused a large fraction of the flow to bypass much of the dump diffuser and go directly from the prediffuser exit to the bypass air holes on the combustor casing, thereby, rendering the dump diffuser ineffective in diffusing the flow. The dump diffuser was occupied by a large recirculation region which dissipated the flow kinetic energy. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor-diffuser system; much of it in the dump diffuser where the fluid passed through the narrow gaps and pathways. Strong flow interactions in the combustor-diffuser system indicate the need for design modifications which could not be addressed by empirical correlations based on simple flow configurations.« less

Characterization and Simulation of Thermoacoustic Instability in a Low Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Paxson, Daniel E.

2008-01-01

Extensive research is being done toward the development of ultra-low-emissions combustors for aircraft gas turbine engines. However, these combustors have an increased susceptibility to thermoacoustic instabilities. This type of instability was recently observed in an advanced, low emissions combustor prototype installed in a NASA Glenn Research Center test stand. The instability produces pressure oscillations that grow with increasing fuel/air ratio, preventing full power operation. The instability behavior makes the combustor a potentially useful test bed for research into active control methods for combustion instability suppression. The instability behavior was characterized by operating the combustor at various pressures, temperatures, and fuel and air flows representative of operation within an aircraft gas turbine engine. Trends in instability behavior vs. operating condition have been identified and documented. A simulation developed at NASA Glenn captures the observed instability behavior. The physics-based simulation includes the relevant physical features of the combustor and test rig, employs a Sectored 1-D approach, includes simplified reaction equations, and provides time-accurate results. A computationally efficient method is used for area transitions, which decreases run times and allows the simulation to be used for parametric studies, including control method investigations. Simulation results show that the simulation exhibits a self-starting, self-sustained combustion instability and also replicates the experimentally observed instability trends vs. operating condition. Future plans are to use the simulation to investigate active control strategies to suppress combustion instabilities and then to experimentally demonstrate active instability suppression with the low emissions combustor prototype, enabling full power, stable operation.

Vitamin D in Vascular Calcification: A Double-Edged Sword?

PubMed

Wang, Jeffrey; Zhou, Jimmy J; Robertson, Graham R; Lee, Vincent W

2018-05-22

Vascular calcification (VC) as a manifestation of perturbed mineral balance, is associated with aging, diabetes and kidney dysfunction, as well as poorer patient outcomes. Due to the current limited understanding of the pathophysiology of vascular calcification, the development of effective preventative and therapeutic strategies remains a significant clinical challenge. Recent evidence suggests that traditional risk factors for cardiovascular disease, such as left ventricular hypertrophy and dyslipidaemia, fail to account for clinical observations of vascular calcification. Therefore, more complex underlying processes involving physiochemical changes to mineral balance, vascular remodelling and perturbed hormonal responses such as parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) are likely to contribute to VC. In particular, VC resulting from modifications to calcium, phosphate and vitamin D homeostasis has been recently elucidated. Notably, deregulation of vitamin D metabolism, dietary calcium intake and renal mineral handling are associated with imbalances in systemic calcium and phosphate levels and endothelial cell dysfunction, which can modulate both bone and soft tissue calcification. This review addresses the current understanding of VC pathophysiology, with a focus on the pathogenic role of vitamin D that has provided new insights into the mechanisms of VC.

A comparison of intellectual assessments over video conferencing and in-person for individuals with ID: preliminary data.

PubMed

Temple, V; Drummond, C; Valiquette, S; Jozsvai, E

2010-06-01

Video conferencing (VC) technology has great potential to increase accessibility to healthcare services for those living in rural or underserved communities. Previous studies have had some success in validating a small number of psychological tests for VC administration; however, VC has not been investigated for use with persons with intellectual disabilities (ID). A comparison of test results for two well known and widely used assessment instruments was undertaken to establish if scores for VC administration would differ significantly from in-person assessments. Nineteen individuals with ID aged 23-63 were assessed once in-person and once over VC using the Wechsler Abbreviated Scale of Intelligence (WASI) and the Beery-Buktenica Test of Visual-Motor Integration (VMI). Highly similar results were found for test scores. Full-scale IQ on the WASI and standard scores for the VMI were found to be very stable across the two administration conditions, with a mean difference of less than one IQ point/standard score. Video conferencing administration does not appear to alter test results significantly for overall score on a brief intelligence test or a test of visual-motor integration.

75 FR 82370 - Approval and Promulgation of State Plans for Designated Facilities and Pollutants; State of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-30

... Guidelines (EGs) applicable to existing Large Municipal Waste Combustors (LMWCs). These EGs apply to municipal waste combustors with a capacity to combust more than 250 tons per day of municipal solid waste... Municipal Waste Combustor (LMWC) Emissions From Existing Facilities AGENCY: Environmental Protection Agency...

40 CFR 60.34b - Emission guidelines for municipal waste combustor operating practices.

Code of Federal Regulations, 2013 CFR

2013-07-01

... combustor operating practices. 60.34b Section 60.34b Protection of Environment ENVIRONMENTAL PROTECTION... September 20, 1994 § 60.34b Emission guidelines for municipal waste combustor operating practices. (a) For approval, a State plan shall include emission limits for carbon monoxide at least as protective as the...

40 CFR 60.34b - Emission guidelines for municipal waste combustor operating practices.

Code of Federal Regulations, 2011 CFR

2011-07-01

... combustor operating practices. 60.34b Section 60.34b Protection of Environment ENVIRONMENTAL PROTECTION... September 20, 1994 § 60.34b Emission guidelines for municipal waste combustor operating practices. (a) For approval, a State plan shall include emission limits for carbon monoxide at least as protective as the...

40 CFR 60.34b - Emission guidelines for municipal waste combustor operating practices.

Code of Federal Regulations, 2014 CFR

2014-07-01

... combustor operating practices. 60.34b Section 60.34b Protection of Environment ENVIRONMENTAL PROTECTION... September 20, 1994 § 60.34b Emission guidelines for municipal waste combustor operating practices. (a) For approval, a State plan shall include emission limits for carbon monoxide at least as protective as the...

40 CFR 60.34b - Emission guidelines for municipal waste combustor operating practices.

Code of Federal Regulations, 2012 CFR

2012-07-01

... combustor operating practices. 60.34b Section 60.34b Protection of Environment ENVIRONMENTAL PROTECTION... September 20, 1994 § 60.34b Emission guidelines for municipal waste combustor operating practices. (a) For approval, a State plan shall include emission limits for carbon monoxide at least as protective as the...

40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

Code of Federal Regulations, 2010 CFR

2010-07-01

... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emissions... (parts per million by volume) a Mass burn waterwall 205 205. Mass burn rotary waterwall 250 210. Refuse-derived fuel combustor 250 250. Fluidized bed combustor 180 180. Mass burn refractory combustors No limit...

40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

Code of Federal Regulations, 2012 CFR

2012-07-01

... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emissions... (parts per million by volume) a Mass burn waterwall 205 205. Mass burn rotary waterwall 250 210. Refuse-derived fuel combustor 250 250. Fluidized bed combustor 180 180. Mass burn refractory combustors No limit...

40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

Code of Federal Regulations, 2014 CFR

2014-07-01

... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emissions... (parts per million by volume) a Mass burn waterwall 205 205. Mass burn rotary waterwall 250 210. Refuse-derived fuel combustor 250 250. Fluidized bed combustor 180 180. Mass burn refractory combustors No limit...

Spray combustion experiments and numerical predictions

NASA Technical Reports Server (NTRS)

Mularz, Edward J.; Bulzan, Daniel L.; Chen, Kuo-Huey

1993-01-01

The next generation of commercial aircraft will include turbofan engines with performance significantly better than those in the current fleet. Control of particulate and gaseous emissions will also be an integral part of the engine design criteria. These performance and emission requirements present a technical challenge for the combustor: control of the fuel and air mixing and control of the local stoichiometry will have to be maintained much more rigorously than with combustors in current production. A better understanding of the flow physics of liquid fuel spray combustion is necessary. This paper describes recent experiments on spray combustion where detailed measurements of the spray characteristics were made, including local drop-size distributions and velocities. Also, an advanced combustor CFD code has been under development and predictions from this code are compared with experimental results. Studies such as these will provide information to the advanced combustor designer on fuel spray quality and mixing effectiveness. Validation of new fast, robust, and efficient CFD codes will also enable the combustor designer to use them as additional design tools for optimization of combustor concepts for the next generation of aircraft engines.

High Frequency Adaptive Instability Suppression Controls in a Liquid-Fueled Combustor

NASA Technical Reports Server (NTRS)

Kopasakis, George

2003-01-01

This effort extends into high frequency (>500 Hz), an earlier developed adaptive control algorithm for the suppression of thermo-acoustic instabilities in a liquidfueled combustor. The earlier work covered the development of a controls algorithm for the suppression of a low frequency (280 Hz) combustion instability based on simulations, with no hardware testing involved. The work described here includes changes to the simulation and controller design necessary to control the high frequency instability, augmentations to the control algorithm to improve its performance, and finally hardware testing and results with an experimental combustor rig developed for the high frequency case. The Adaptive Sliding Phasor Averaged Control (ASPAC) algorithm modulates the fuel flow in the combustor with a control phase that continuously slides back and forth within the phase region that reduces the amplitude of the instability. The results demonstrate the power of the method - that it can identify and suppress the instability even when the instability amplitude is buried in the noise of the combustor pressure. The successful testing of the ASPAC approach helped complete an important NASA milestone to demonstrate advanced technologies for low-emission combustors.

Testing of felt-ceramic materials for combustor applications

NASA Technical Reports Server (NTRS)

Venkat, R. S.; Roffe, G.

1983-01-01

The feasibility of using composite felt ceramic materials as combustor liners was experimentally studied. The material consists of a porous felt pad sandwiched between a layer of ceramic and one of solid metal. Flat, rectangular test panels, which encompassed several design variations of the basic composite material, were tested, two at a time, in a premixed gas turbine combustor as sections of the combustor wall. Tests were conducted at combustor inlet conditions of 0.5 MPa and 533 K with a reference velocity of 25 m/s. The panels were subjected to a hot gas temperature of 2170 K with 1% of the total airflow used to film cool the ceramic surface of the test panel. In general, thin ceramic layers yield low ceramic stress levels with high felt ceramic interface temperatures. On the other hand, thick ceramic layers result in low felt ceramic interface temperatures but high ceramic stress levels. Extensive thermal cycling appears to cause material degradation, but for a limited number of cycles, the survivability of felt ceramic materials, even under extremely severe combustor operating conditions, was conclusively demonstrated.

Computational Study of Combustor-Turbine Interactions

NASA Technical Reports Server (NTRS)

Miki, Kenji; Liou, Meng-Sing

2017-01-01

The Open National Combustion Code (OpenNCC) is applied to the simulation of a realisticcombustor configuration (Energy Efficient Engine (E3)) in order to investigate the unsteady flow fields inside the combustor and around the first stage stator of a high pressure turbine (HPT). We consider one-twelfth (24 degrees) of the full annular E3 combustor with three different geometries of the combustor exit: one without the vane, and two others with the vane set at different relative positions in relation to the fuel nozzle (clocking). Although it is common to take the exit flow profiles obtained by separately simulating the combustor and then feed it as the inflow profile when modeling the HPT, our studies show that the unsteady flow fields are influenced by the presence of the vane as well as clocking. More importantly, the characteristics (e.g., distribution and strength) of the high temperature spots (i.e., hot-streaks) appearing on the vane significantly alters. This indicates the importance of simultaneously modeling both the combustor and the HPT to understand the mechanics of the unsteady formulation of hot-streaks.

Computational Study of Combustor-Turbine Interactions

NASA Technical Reports Server (NTRS)

Miki, Kenji; Liou, Meng-Sing

2017-01-01

The Open National Combustion Code (OpenNCC) is applied to the simulation of a realisticcombustor configuration [Energy Efficient Engine (E(exp. 3))] in order to investigate the unsteady flow fields inside the combustor and around the first stage stator of a high pressure turbine (HPT). We consider one-twelfth (24 degrees) of the full annular E(exp. 3) combustor with three different geometries of the combustor exit: one without the vane, and two others with the vane set at different relative positions in relation to the fuel nozzle (clocking). Although it is common to take the exit flow profiles obtained by separately simulating the combustor and then feed it as the inflow profile when modeling the HPT, our studies show that the unsteady flow fields are influenced by the presence of the vane as well as clocking. More importantly, the characteristics (e.g., distribution and strength) of the high temperature spots (i.e., hot-streaks) appearing on the vane significantly alters. This indicates the importance of simultaneously modeling both the combustor and the HPT to understand the mechanics of the unsteady formulation of hot-streaks.

Combustor kinetic energy efficiency analysis of the hypersonic research engine data

NASA Astrophysics Data System (ADS)

Hoose, K. V.

1993-11-01

A one-dimensional method for measuring combustor performance is needed to facilitate design and development scramjet engines. A one-dimensional kinetic energy efficiency method is used for measuring inlet and nozzle performance. The objective of this investigation was to assess the use of kinetic energy efficiency as an indicator for scramjet combustor performance. A combustor kinetic energy efficiency analysis was performed on the Hypersonic Research Engine (HRE) data. The HRE data was chosen for this analysis due to its thorough documentation and availability. The combustor, inlet, and nozzle kinetic energy efficiency values were utilized to determine an overall engine kinetic energy efficiency. Finally, a kinetic energy effectiveness method was developed to eliminate thermochemical losses from the combustion of fuel and air. All calculated values exhibit consistency over the flight speed range. Effects from fuel injection, altitude, angle of attack, subsonic-supersonic combustion transition, and inlet spike position are shown and discussed. The results of analyzing the HRE data indicate that the kinetic energy efficiency method is effective as a measure of scramjet combustor performance.

Parametric Modeling Investigation of a Radially-Staged Low-Emission Aviation Combustor

NASA Technical Reports Server (NTRS)

Heath, Christopher M.

2016-01-01

Aviation gas-turbine combustion demands high efficiency, wide operability and minimal trace gas emissions. Performance critical design parameters include injector geometry, combustor layout, fuel-air mixing and engine cycle conditions. The present investigation explores these factors and their impact on a radially staged low-emission aviation combustor sized for a next-generation 24,000-lbf-thrust engine. By coupling multi-fidelity computational tools, a design exploration was performed using a parameterized annular combustor sector at projected 100% takeoff power conditions. Design objectives included nitrogen oxide emission indices and overall combustor pressure loss. From the design space, an optimal configuration was selected and simulated at 7.1, 30 and 85% part-power operation, corresponding to landing-takeoff cycle idle, approach and climb segments. All results were obtained by solution of the steady-state Reynolds-averaged Navier-Stokes equations. Species concentrations were solved directly using a reduced 19-step reaction mechanism for Jet-A. Turbulence closure was obtained using a nonlinear K-epsilon model. This research demonstrates revolutionary combustor design exploration enabled by multi-fidelity physics-based simulation.

Combustor Operability and Performance Verification for HIFiRE Flight 2

NASA Technical Reports Server (NTRS)

Storch, Andrea M.; Bynum, Michael; Liu, Jiwen; Gruber, Mark

2011-01-01

As part of the Hypersonic International Flight Research Experimentation (HIFiRE) Direct-Connect Rig (HDCR) test and analysis activity, three-dimensional computational fluid dynamics (CFD) simulations were performed using two Reynolds-Averaged Navier Stokes solvers. Measurements obtained from ground testing in the NASA Langley Arc-Heated Scramjet Test Facility (AHSTF) were used to specify inflow conditions for the simulations and combustor data from four representative tests were used as benchmarks. Test cases at simulated flight enthalpies of Mach 5.84, 6.5, 7.5, and 8.0 were analyzed. Modeling parameters (e.g., turbulent Schmidt number and compressibility treatment) were tuned such that the CFD results closely matched the experimental results. The tuned modeling parameters were used to establish a standard practice in HIFiRE combustor analysis. Combustor performance and operating mode were examined and were found to meet or exceed the objectives of the HIFiRE Flight 2 experiment. In addition, the calibrated CFD tools were then applied to make predictions of combustor operation and performance for the flight configuration and to aid in understanding the impacts of ground and flight uncertainties on combustor operation.

Dish stirling solar receiver combustor test program

NASA Technical Reports Server (NTRS)

Bankston, C. P.; Back, L. H.

1981-01-01

The operational and energy transfer characteristics of the Dish Stirling Solar Receiver (DSSR) combustor/heat exchanger system was evaluated. The DSSR is designed to operate with fossil fuel augmentation utilizing a swirl combustor and cross flow heat exchanger consisting of a single row of 4 closely spaced tubes that are curved into a conical shape. The performance of the combustor/heat exchanger system without a Stirling engine was studied over a range of operating conditions and output levels using water as the working fluid. Results show that the combustor may be started under cold conditions, controlled safety, and operated at a constant air/fuel ratio (10 percent excess air) over the required range of firing rates. Furthermore, nondimensional heat transfer coefficients based on total heat transfer are plotted versus Reynolds number and compared with literature data taken for single rows of closely spaced tubes perpendicular to cross flow. The data show enhanced heat transfer for the present geometry and test conditions. Analysis of the results shows that the present system meets specified thermal requirements, thus verifying the feasibility of the DSSR combustor design for final prototype fabrication.

Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

NASA Astrophysics Data System (ADS)

Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

2016-05-01

To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

Two and three-dimensional prediffuser combustor studies with air-water mixture

NASA Technical Reports Server (NTRS)

Laing, Peter; Ehresman, C. M.; Murthy, S. N. B.

1993-01-01

Two- and three-dimensional gas turbine prediffuser-combustor sectors were experimentally studied under a number of mixture and flow conditions in a tunnel operating with a two-phase, air-liquid film-droplet mixture. It is concluded that water vaporization in the combustor causes changes in both local gas temperature and state of vitiation and reduces reaction rates. Substantial accumulation of water and water vapor takes place in pocket over the combustor volume, even when the air-water mixture is steady in time. The accuracy of determining combustor performance changes increases with a better knowledge of the state of the air-water mixture in the primary zone. To establish flame-out conditions it is considered to be necessary to combine the prediction of detailed flowfield and chemical activity with that of flame stability and motion characteristics.

Accelerating volumetric cine MRI (VC-MRI) using undersampling for real-time 3D target localization/tracking in radiation therapy: a feasibility study

NASA Astrophysics Data System (ADS)

Harris, Wendy; Yin, Fang-Fang; Wang, Chunhao; Zhang, You; Cai, Jing; Ren, Lei

2018-01-01

Purpose. To accelerate volumetric cine MRI (VC-MRI) using undersampled 2D-cine MRI to provide real-time 3D guidance for gating/target tracking in radiotherapy. Methods. 4D-MRI is acquired during patient simulation. One phase of the prior 4D-MRI is selected as the prior images, designated as MRIprior. The on-board VC-MRI at each time-step is considered a deformation of the MRIprior. The deformation field map is represented as a linear combination of the motion components extracted by principal component analysis from the prior 4D-MRI. The weighting coefficients of the motion components are solved by matching the corresponding 2D-slice of the VC-MRI with the on-board undersampled 2D-cine MRI acquired. Undersampled Cartesian and radial k-space acquisition strategies were investigated. The effects of k-space sampling percentage (SP) and distribution, tumor sizes and noise on the VC-MRI estimation were studied. The VC-MRI estimation was evaluated using XCAT simulation of lung cancer patients and data from liver cancer patients. Volume percent difference (VPD) and Center of Mass Shift (COMS) of the tumor volumes and tumor tracking errors were calculated. Results. For XCAT, VPD/COMS were 11.93  ±  2.37%/0.90  ±  0.27 mm and 11.53  ±  1.47%/0.85  ±  0.20 mm among all scenarios with Cartesian sampling (SP  =  10%) and radial sampling (21 spokes, SP  =  5.2%), respectively. When tumor size decreased, higher sampling rate achieved more accurate VC-MRI than lower sampling rate. VC-MRI was robust against noise levels up to SNR  =  20. For patient data, the tumor tracking errors in superior-inferior, anterior-posterior and lateral (LAT) directions were 0.46  ±  0.20 mm, 0.56  ±  0.17 mm and 0.23  ±  0.16 mm, respectively, for Cartesian-based sampling with SP  =  20% and 0.60  ±  0.19 mm, 0.56  ±  0.22 mm and 0.42  ±  0.15 mm, respectively, for radial-based sampling with SP  =  8% (32 spokes). Conclusions. It is feasible to estimate VC-MRI from a single undersampled on-board 2D cine MRI. Phantom and patient studies showed that the temporal resolution of VC-MRI can potentially be improved by 5-10 times using a 2D cine image acquired with 10-20% k-space sampling.

Improvements in manual dexterity relate to improvements in cognitive planning after assisted cycling therapy (ACT) in adolescents with down syndrome.

PubMed

Holzapfel, Simon D; Ringenbach, Shannon D R; Mulvey, Genna M; Sandoval-Menendez, Amber M; Cook, Megan R; Ganger, Rachel O; Bennett, Kristen

2015-01-01

We have previously reported beneficial effects of acute (i.e., single session) Assisted Cycling Therapy (ACT) on manual dexterity and cognitive planning ability in adolescents with Down syndrome (DS). In the present study, we report the chronic effects of eight weeks of ACT, voluntary cycling (VC), and no cycling (NC), on the same measures in adolescents with DS. Participants completed 8 weeks of ACT, VC, or NC. Those in the ACT and VC groups completed 30min sessions three times per week on a stationary bicycle. During ACT, the mechanical motor of the bicycle augmented the cadence to a rate which was on average 79% faster than the voluntary cadence. During VC, the participants pedaled at a self-selected rate. Unimanual dexterity scores as measured with the Purdue Pegboard test (PPT) improved significantly more for the ACT and VC groups compared to the NC group. ACT lead to greater improvements than VC and NC in the assembly sub-test, which is a task that requires more advanced temporal and spatial processing. The ACT group improved significantly more than the VC group and non-significantly more than the NC group in cognitive planning ability as measured by the Tower of London test (ToL). There were also significant correlations between the assembly subtest of the PPT and all measures of the ToL. These correlations were stronger during post-testing than pre-testing. Pre-post changes in the combined PPT score and ToL number of correct moves correlated positively in the ACT group. These results support the efficacy of the salutary effects of ACT on global fine motor function and executive function in DS. Additionally, the performance on complex bimanual dexterity tasks appears to be related to the capacity of cognitive planning ability. This research has important implications for persons with movement deficits that affect activities of daily living. Copyright © 2015 Elsevier Ltd. All rights reserved.

Assessment of vegetation establishment on tailings dam at an iron ore mining site of suburban Beijing, China, 7 years after reclamation with contrasting site treatment methods.

PubMed

Yan, Demin; Zhao, Fangying; Sun, Osbert Jianxin

2013-09-01

Strip-mining operations greatly disturb soil, vegetation and landscape elements, causing many ecological and environmental problems. Establishment of vegetation is a critical step in achieving the goal of ecosystem restoration in mining areas. At the Shouyun Iron Ore Mine in suburban Beijing, China, we investigated selective vegetation and soil traits on a tailings dam 7 years after site treatments with three contrasting approaches: (1) soil covering (designated as SC), (2) application of a straw mat, known as "vegetation carpet", which contains prescribed plant seed mix and water retaining agent (designated as VC), on top of sand piles, and (3) combination of soil covering and application of vegetation carpet (designated as SC+VC). We found that after 7 years of reclamation, the SC+VC site had twice the number of plant species and greater biomass than the SC and VC sites, and that the VC site had a comparable plant abundance with the SC+VC site but much less biodiversity and plant coverage. The VC site did not differ with the SC site in the vegetation traits, albeit low soil fertility. It is suggested that application of vegetation carpet can be an alternative to introduction of topsoil for treatment of tailings dam with fine-structured substrate of ore sands. However, combination of topsoil treatment and application of vegetation carpet greatly increases vegetation coverage and plant biodiversity, and is therefore a much better approach for assisting vegetation establishment on the tailings dam of strip-mining operations. While application of vegetation carpet helps to stabilize the loose surface of fine-structured mine wastes and to introduce seed bank, introduction of fertile soil is necessary for supplying nutrients to plant growth in the efforts of ecosystem restoration of mining areas.

Vitamin E and vitamin C supplementation improves antioxidant status and immune function in oxidative-stressed breeder roosters by up-regulating expression of GSH-Px gene.

PubMed

Min, Y N; Niu, Z Y; Sun, T T; Wang, Z P; Jiao, P X; Zi, B B; Chen, P P; Tian, D L; Liu, F Z

2018-04-01

This study aimed to evaluate the effects of vitamin C and vitamin E on antioxidant capacity and immune function in oxidative-stressed breeder roosters. One hundred twenty 45-week-old Lveyang black-boned breeder roosters were randomly assigned to 5 dietary treatments, including negative control group (NC), positive control group (PC), and 3 trial groups, which were fed the diets containing 300 mg/kg VC, 200 mg/kg VE, or 300 mg/kg VC and 200 mg/kg VE (VC+VE). At 47 wk of age, the positive control and trial groups were subcutaneously injected 3 times every other d with dexamethasone (DEX) 4 mg/kg of body weight, the negative control group was injected with saline. The experiment lasted for 35 d. The results showed that at 50 wk of age, average daily feed intake of birds challenged with DEX significantly increased (P < 0.05). During post-stress recovery period (52 wk of age), dietary supplemental VE or VC+VE notably increased body weight under oxidative stress (P < 0.01). Oxidative stress induced by DEX could significantly decrease superoxide dismutase (SOD), IgM, antibody titer of ND and mRNA expression of SOD or glutathion peroxidase activity (GSH-Px), increase serous malondialdehyde (MDA) (P < 0.05). Supplementation of VC or VE significantly decreased serous MDA, and increased SOD under oxidative stress (P < 0.05). Supplementation of VC or VE, or their combination significantly increased the relative expression of GSH-Px mRNA when compared to the oxidative-stressed control treatment (P < 0.05), whereas did not alleviate the relative expression of SOD mRNA (P > 0.05). Therefore, the results suggest that addition of 300 mg/kg VC, 200 mg/kg VE or their combination could improve antioxidant ability and immune performance in oxidative-stressed breeder roosters through up-regulating the expression of GSH-Px gene.

Les accidents de la vie courante chez l’enfant à Dakar: à propos de 201 cas

PubMed Central

Mohamed, Azhar Salim; Sagna, Aloïse; Fall, Mbaye; Ndoye, Ndeye Aby; Mbaye, Papa Alassane; Fall, Aimé Lakh; Diaby, Alou; Ndour, Oumar; Ngom, Gabriel

2017-01-01

Les accidents de la vie courante (AcVC) sont fréquents chez l’enfant et peuvent être à l’origine de lésions handicapantes et de décès. L’objectif de notre travail était d’étudier les aspects épidémiologiques et lésionnels des AcVC à Dakar. C’est une étude transversale descriptive menée du 1er Janvier 2013 au 30 juin 2013. Les enfants victimes d’accidents domestiques, d’accidents de sport et de loisirs ou d’accidents scolaires ont été inclus. Nous avons étudié des paramètres généraux et des paramètres ayant trait à chaque type d’AcVC. Deux cent et un enfants ont été inclus, ce qui représentait 27% des consultations aux urgences. Il y avait 148 garçons et 53 filles. Les enfants de moins de 5 ans étaient les plus touchés (37,8%). Le football et le jeu de lutte étaient les grands pourvoyeurs d’AcVC. Les AcVC survenaient principalement à domicile (58,2%) et dans les aires de sport et de loisirs (31,8%). Les fractures prédominaient dans les différents types d’AcVC: 54,9% des accidents domestiques, 68,8% des accidents de sport et de loisirs et 40% des accidents scolaires. Au plan épidémiologique, nos résultats sont superposables à la littérature. Les fractures prédominent à l’opposé de la littérature où les contusions sont prépondérantes. Le jeu de lutte est le plus grand pourvoyeur de ces fractures après le football. La connaissance des aspects épidémiologiques et lésionnels permet de mener des campagnes de prévention des AcVC à Dakar. PMID:29187941

A capture method based on the VC1 domain reveals new binding properties of the human receptor for advanced glycation end products (RAGE).

PubMed

Degani, Genny; Altomare, Alessandra A; Colzani, Mara; Martino, Caterina; Mazzolari, Angelica; Fritz, Guenter; Vistoli, Giulio; Popolo, Laura; Aldini, Giancarlo

2017-04-01

The Advanced Glycation and Lipoxidation End products (AGEs and ALEs) are a heterogeneous class of compounds derived from the non-enzymatic glycation or protein adduction by lipoxidation break-down products. The receptor for AGEs (RAGE) is involved in the progression of chronic diseases based on persistent inflammatory state and oxidative stress. RAGE is a pattern recognition receptor (PRR) and the inhibition of the interaction with its ligands or of the ligand accumulation have a potential therapeutic effect. The N-terminal domain of RAGE, the V domain, is the major site of AGEs binding and is stabilized by the adjacent C1 domain. In this study, we set up an affinity assay relying on the extremely specific biological interaction AGEs ligands have for the VC1 domain. A glycosylated form of VC1, produced in the yeast Pichia pastoris, was attached to magnetic beads and used as insoluble affinity matrix (VC1-resin). The VC1 interaction assay was employed to isolate specific VC1 binding partners from in vitro generated AGE-albumins and modifications were identified/localized by mass spectrometry analysis. Interestingly, this method also led to the isolation of ALEs produced by malondialdehyde treatment of albumins. Computational studies provided a rational-based interpretation of the contacts established by specific modified residues and amino acids of the V domain. The validation of VC1-resin in capturing AGE-albumins from complex biological mixtures such as plasma and milk, may lead to the identification of new RAGE ligands potentially involved in pro-inflammatory and pro-fibrotic responses, independently of their structures or physical properties, and without the use of any covalent derivatization process. In addition, the method can be applied to the identification of antagonists of RAGE-ligand interaction. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity.

PubMed

Oppenheimer, Beno W; Berger, Kenneth I; Ali, Saleem; Segal, Leopoldo N; Donnino, Robert; Katz, Stuart; Parikh, Manish; Goldring, Roberta M

2016-01-01

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity. Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Interleukin-18 Enhances Vascular Calcification and Osteogenic Differentiation of Vascular Smooth Muscle Cells Through TRPM7 Activation.

PubMed

Zhang, Kun; Zhang, Yinyin; Feng, Weijing; Chen, Renhua; Chen, Jie; Touyz, Rhian M; Wang, Jingfeng; Huang, Hui

2017-10-01

Vascular calcification (VC) is an important predictor of cardiovascular morbidity and mortality. Osteogenic differentiation of vascular smooth muscle cells (VSMCs) is a key mechanism of VC. Recent studies show that IL-18 (interleukin-18) favors VC while TRPM7 (transient receptor potential melastatin 7) channel upregulation inhibits VC. However, the relationship between IL-18 and TRPM7 is unclear. We questioned whether IL-18 enhances VC and osteogenic differentiation of VSMCs through TRPM7 channel activation. Coronary artery calcification and serum IL-18 were measured in patients by computed tomographic scanning and enzyme-linked immunosorbent assay, respectively. Primary rat VSMCs calcification were induced by high inorganic phosphate and exposed to IL-18. VSMCs were also treated with TRPM7 antagonist 2-aminoethoxy-diphenylborate or TRPM7 small interfering RNA to block TRPM7 channel activity and expression. TRPM7 currents were recorded by patch-clamp. Human studies showed that serum IL-18 levels were positively associated with coronary artery calcium scores ( r =0.91; P <0.001). In VSMCs, IL-18 significantly decreased expression of contractile markers α-smooth muscle actin, smooth muscle 22 α, and increased calcium deposition, alkaline phosphatase activity, and expression of osteogenic differentiation markers bone morphogenetic protein-2, Runx2 (runt-related transcription factor 2), and osteocalcin ( P <0.05). IL-18 increased TRPM7 expression through ERK1/2 (extracellular signal-regulated kinase 1/2) signaling activation, and TRPM7 currents were augmented by IL-18 treatment. Inhibition of TRPM7 channel by 2-aminoethoxy-diphenylborate or TRPM7 small interfering RNA prevented IL-18-enhanced osteogenic differentiation and VSMCs calcification. These findings suggest that coronary artery calcification is associated with increased IL-18 levels. IL-18 enhances VSMCs osteogenic differentiation and subsequent VC induced by β-glycerophosphate via TRPM7 channel activation. Accordingly, IL-18 may contribute to VC in proinflammatory conditions. © 2017 American Heart Association, Inc.

Recovery of function, peripheral sensitization and sensory neurone activation by novel pathways following axonal injury in Aplysia californica.

PubMed

Dulin, M F; Steffensen, I; Morris, C E; Walters, E T

1995-10-01

Recovery of behavioural and sensory function was examined following unilateral pedal nerve crush in Aplysia californica. Nerve crush that transected all axons connecting the tail to the central nervous system (CNS) eliminated the ipsilateral tail-evoked siphon reflex, whose sensory input travels in the crushed tail nerve (p9). The first reliable signs of recovery of this reflex were observed within 1 week, and most animals displayed tail-evoked siphon responses within 2 weeks. Wide-dynamic-range mechanosensory neurons with somata in the ventrocaudal (VC) cluster of the ipsilateral pleural ganglion exhibited a few receptive fields (RFs) on the tail 3 weeks after unilateral pedal nerve crush, indicating that the RFs had either regenerated or been reconnected to the central somata. These RFs were smaller and sensitized compared with corresponding RFs on the contralateral, uncrushed side. Centrally conducted axon responses of VC sensory neurones to electrical stimulation distal to the nerve crush site did not reappear until at least 10 days after the crush. Because the crush site was much closer to the CNS than to the tail, the failure of axon responses to be restored earlier than the behavioural responses indicates that early stages of reflex recovery are not due to regeneration of VC sensory neurone axons into the tail. Following nerve crush, VC sensory neurones often could be activated by stimulating central connectives or peripheral nerves that do not normally contain the sensory neurone's axons. These results suggest that recovery of behavioral function after nerve injury involves complex mechanisms, including regenerative growth of axotomized VC sensory neurones, sensitization of regenerating RFs and sprouting of VC sensory neurone fibres within the CNS. Furthermore, the rapidity of behavioural recovery indicates that its initial phases are mediated by additional mechanisms, perhaps centripetal regeneration of unidentified sensory neurones having peripheral somata, or transient reconnection of proximal and distal stumps of axotomized VC cells.

Attenuated noradrenergic sensitivity during local cooling in aged human skin

PubMed Central

Thompson, Caitlin S; Holowatz, Lacy A; Kenney, W. Larry

2005-01-01

Reflex-mediated cutaneous vasoconstriction (VC) is impaired in older humans; however, it is unclear whether this blunted VC also occurs during local cooling, which mediates VC through different mechanisms. We tested the hypothesis that the sensitization of cutaneous vessels to noradrenaline (NA) during direct skin cooling seen in young skin is blunted in aged skin. In 11 young (18–30 years) and 11 older (62–76 years) men and women, skin blood flow was monitored at two forearm sites with laser Doppler (LD) flowmetry while local skin temperature was cooled and clamped at 24°C. Cutaneous vascular conductance (CVC; LD flux/mean arterial pressure) was expressed as percentage change from baseline (%ΔCVCbase). At one site, five doses of NA (10−10–10−2m) were sequentially infused via intradermal microdialysis during cooling while the other 24°C site served as control (Ringer solution + cooling). At control sites, VC due to cooling alone was similar in young versus older (−54 ± 5 versus −56 ± 3%ΔCVCbase, P= 0.46). In young, NA infusions induced additional dose-dependent VC (10−8, 10−6, 10−4 and 10−2m: −70 ± 2, −72 ± 3, −78 ± 3 and −79 ± 4%ΔCVCbase; P < 0.05 versus control). In older subjects, further VC did not occur until the highest infused dose of NA (10−2m: −70 ± 5%ΔCVCbase; P < 0.05 versus control). When cutaneous arterioles are sensitized to NA by direct cooling, young skin exhibits the capacity to further constrict to NA in a dose-dependent manner. However, older skin does not display enhanced VC capacity until treated with saturating doses of NA, possibly due to age-associated decrements in Ca2+ availability or α2C-adrenoceptor function. PMID:15705648

Reflex vasoconstriction in aged human skin increasingly relies on Rho kinase-dependent mechanisms during whole body cooling

PubMed Central

Jennings, John D.; Holowatz, Lacy A.; Kenney, W. Larry

2009-01-01

Primary human aging may be associated with augmented Rho kinase (ROCK)-mediated contraction of vascular smooth muscle and ROCK-mediated inhibition of nitric oxide synthase (NOS). We hypothesized that the contribution of ROCK to reflex vasoconstriction (VC) is greater in aged skin. Cutaneous VC was elicited by 1) whole body cooling [mean skin temperature (Tsk) = 30.5°C] and 2) local norepinephrine (NE) infusion (1 × 10−6 M). Four microdialysis fibers were placed in the forearm skin of eight young (Y) and eight older (O) subjects for infusion of 1) Ringer solution (control), 2) 3 mM fasudil (ROCK inhibition), 3) 20 mM NG-nitro-l-arginine methyl ester (NOS inhibition), and 4) both ROCK + NOS inhibitors. Red cell flux was measured by laser-Doppler flowmetry over each site. Cutaneous vascular conductance (CVC) was calculated as flux/mean arterial pressure and normalized to baseline CVC (%ΔCVCbaseline). VC was reduced at the control site in O during cooling (Y, −34 ± 3; and O, −18 ± 3%ΔCVCbaseline; P < 0.001) and NE infusion (Y, −53 ± 4, and O, −41 ± 9%ΔCVCbaseline; P = 0.006). Fasudil attenuated VC in both age groups during mild cooling; however, this reduction remained only in O but not in Y skin during moderate cooling (Y, −30 ± 5; and O, −7 ± 1%ΔCVCbaseline; P = 0.016) and was not altered by NOS inhibition. Fasudil blunted NE-mediated VC in both age groups (Y, −23 ± 4; and O, −7 ± 3%ΔCVCbaseline; P < 0.01). Cumulatively, these data indicate that reflex VC is more reliant on ROCK in aged skin such that approximately half of the total VC response to whole body cooling is ROCK dependent. PMID:19717729

Effects of fuel nozzle design on performance of an experimental annular combustor using natural gas fuel

NASA Technical Reports Server (NTRS)

Wear, J. D.; Schultz, D. F.

1972-01-01

Tests of various fuel nozzles were conducted with natural gas fuel in a full-annulus combustor. The nozzles were designed to provide either axial, angled, or radial fuel injection. Each fuel nozzle was evaluated by measuring combustion efficiency at relatively severe combustor operating conditions. Combustor blowout and altitude ignition tests were also used to evaluate nozzle designs. Results indicate that angled injection gave higher combustion efficiency, less tendency toward combustion instability, and altitude relight characteristics equal to or superior to those of the other fuel nozzles that were tested.