WorldWideScience

Sample records for rapid low-pressure proteolysis

  1. Modeling the Rapid Boil-Off of a Cryogenic Liquid When Injected into a Low Pressure Cavity

    Science.gov (United States)

    Lira, Eric

    2016-01-01

    Many launch vehicle cryogenic applications require the modeling of injecting a cryogenic liquid into a low pressure cavity. The difficulty of such analyses lies in accurately predicting the heat transfer coefficient between the cold liquid and a warm wall in a low pressure environment. The heat transfer coefficient and the behavior of the liquid is highly dependent on the mass flow rate into the cavity, the cavity wall temperature and the cavity volume. Testing was performed to correlate the modeling performed using Thermal Desktop and Sinda Fluint Thermal and Fluids Analysis Software. This presentation shall describe a methodology to model the cryogenic process using Sinda Fluint, a description of the cryogenic test set up, a description of the test procedure and how the model was correlated to match the test results.

  2. Low-pressure

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Richard [Membrane Technology And Research, Inc., Newark, CA (United States); Kniep, Jay [Membrane Technology And Research, Inc., Newark, CA (United States); Hao, Pingjiao [Membrane Technology And Research, Inc., Newark, CA (United States); Chan, Chi Cheng [Membrane Technology And Research, Inc., Newark, CA (United States); Nguyen, Vincent [Membrane Technology And Research, Inc., Newark, CA (United States); Huang, Ivy [Membrane Technology And Research, Inc., Newark, CA (United States); Amo, Karl [Membrane Technology And Research, Inc., Newark, CA (United States); Freeman, Brice [Membrane Technology And Research, Inc., Newark, CA (United States); Fulton, Don [Membrane Technology And Research, Inc., Newark, CA (United States); Ly, Jennifer [Membrane Technology And Research, Inc., Newark, CA (United States); Lipscomb, Glenn [Membrane Technology And Research, Inc., Newark, CA (United States); Lou, Yuecun [Membrane Technology And Research, Inc., Newark, CA (United States); Gogar, Ravikumar [Membrane Technology And Research, Inc., Newark, CA (United States)

    2015-01-29

    This final technical progress report describes work conducted by Membrane Technology and Research, Inc. (MTR) for the Department of Energy (DOE NETL) on development of low-pressure membrane contactors for carbon dioxide (CO2) capture from power plant flue gas (award number DE-FE0007553). The work was conducted from October 1, 2011 through September 30, 2014. The overall goal of this three-year project was to build and operate a prototype 500 m2 low-pressure sweep membrane module specifically designed to separate CO2 from coal-fired power plant flue gas. MTR was assisted in this project by a research group at the University of Toledo, which contributed to the computational fluid dynamics (CFD) analysis of module design and process simulation. This report details the work conducted to develop a new type of membrane contactor specifically designed for the high-gas-flow, low-pressure, countercurrent sweep operation required for affordable membrane-based CO2 capture at coal power plants. Work for this project included module development and testing, design and assembly of a large membrane module test unit at MTR, CFD comparative analysis of cross-flow, countercurrent, and novel partial-countercurrent sweep membrane module designs, CFD analysis of membrane spacers, design and fabrication of a 500 m2 membrane module skid for field tests, a detailed performance and cost analysis of the MTR CO2 capture process with low-pressure sweep modules, and a process design analysis of a membrane-hybrid separation process for CO2 removal from coal-fired flue gas. Key results for each major task are discussed in the report.

  3. Ammonia Synthesis at Low Pressure.

    Science.gov (United States)

    Cussler, Edward; McCormick, Alon; Reese, Michael; Malmali, Mahdi

    2017-08-23

    Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in areas requiring ammonia for synthetic fertilizer. Such wind energy is often called "stranded," because it is only available far from population centers where it can be directly used. In the proposed low pressure process, nitrogen is made from air using pressure swing absorption, and hydrogen is produced by electrolysis of water. While these gases can react at approximately 400 °C in the presence of a promoted conventional catalyst, the conversion is often limited by the reverse reaction, which makes this reaction only feasible at high pressures. This limitation can be removed by absorption on an ammine-like calcium or magnesium chloride. Such alkaline metal halides can effectively remove ammonia, thus suppressing the equilibrium constraints of the reaction. In the proposed absorption-enhanced ammonia synthesis process, the rate of reaction may then be controlled not by the chemical kinetics nor the absorption rates, but by the rate of the recycle of unreacted gases. The results compare favorably with ammonia made from a conventional small scale Haber-Bosch process.

  4. The Effects of Low-Pressure Rapid Thermal Post-Annealing on the Properties of (Ba, Sr)TiO3 Thin Films Deposited by Liquid Source Misted Chemical Deposition

    Science.gov (United States)

    Yang, Ming-Jui; Chien, Chao-Hsin; Leu, Ching-Chich; Zhang, Ren-Jian; Wu, Shich-Chuan; Huang, Tiao-Yuan; Tseng, Tseung-Yuen

    2001-12-01

    The technique of low-pressure post-annealing process with additional second-step annealing for preparation of the Ba0.7Sr0.3TiO3 thin films deposited by liquid source misted chemical deposition (LSMCD) has been proposed. With employing this annealing procedure, the leakage current density can be significantly eliminated by approximately one order of magnitude at 2 V@. In particular, process temperature can be reduced from 650°C to 600°C without suffering deteriorated crystallinity issue, which is identified by both C-V measurement and X-ray diffraction spectrum. The extracted dielectric constant is 310 with extreamly low loss tangent of 0.005. The spectrum of atomic force microscopy (AFM) shows that this low-pressure process results in smoother surface topography. Moreover, thermal desorption spectrums assure that less residual organics and contaminations were left after low pressure post-annealing. This may be one of the reasons for lowering crystallization temperature and the improved electrical properties.

  5. Low pressure microfluidic-based DNA fragmentation

    NARCIS (Netherlands)

    Shui, Lingling; Sparreboom, Wouter; Bomer, Johan G.; Jin, Mingliang; Carlen, Edwin; van den Berg, Albert

    2011-01-01

    We report a low-pressure microfluidic deoxyribonucleic acid (DNA) fragmentation device based on a combination of me-chanical hydrodynamic shearing and low temperature sample heating. Conventional DNA fragmentation based on hydrody-namic shearing is capable of achieving fragment lengths (FL) < 10k bp

  6. Low Pressure Nuclear Thermal Rocket (LPNTR) concept

    Science.gov (United States)

    Ramsthaler, J. H.

    1991-01-01

    A background and a description of the low pressure nuclear thermal system are presented. Performance, mission analysis, development, critical issues, and some conclusions are discussed. The following subject areas are covered: LPNTR's inherent advantages in critical NTR requirement; reactor trade studies; reference LPNTR; internal configuration and flow of preliminary LPNTR; particle bed fuel assembly; preliminary LPNTR neutronic study results; multiple LPNTR engine concept; tank and engine configuration for mission analysis; LPNTR reliability potential; LPNTR development program; and LPNTR program costs.

  7. Low-Pressure-Drop Shutoff Valve

    Science.gov (United States)

    Thornborrow, John

    1994-01-01

    Flapper valve remains open under normal flow conditions but closes upon sudden increases to high rate of flow and remains closed until reset. Valve is fluid/mechanical analog of electrical fuse or circuit breaker. Low-pressure-drop shutoff valve contains flapper machined from cylindrical surface. During normal flow conditions, flapper presents small cross section to flow. (Useful in stopping loss of fluid through leaks in cooling systems.)

  8. Investigations into low pressure methanol synthesis

    DEFF Research Database (Denmark)

    Sharafutdinov, Irek

    The central topic of this work has been synthesis, characterization and optimization of novel Ni-Ga based catalysts for hydrogenation of CO2 to methanol. The overall goal was to search for materials that could be used as a low temperature (and low pressure) methanol synthesis catalyst....... Among them, Ni-Ga has been chosen, primarily due to low price of constituent metals. After the preliminary optimization work, an optimal catalyst composition and preparation method has been suggested. Indeed, for an optimal catalyst, which is a SiO2 supported Ni-Ga prepared from a solution of nitrates...... due to carbon formation) and under accelerated ageing conditions (due to dealloying). However, the initial activity could always be restored after treatment in hydrogen flow at elevated temperatures. The work in the direction of suppression of deactivation and by-product formation is still in progress....

  9. Mechanical behavior of PDMS at low pressure

    Science.gov (United States)

    Bunyan, J.; Tawfick, S.

    2017-07-01

    Polydimethylsiloxanes (PDMS) are used in a wide range of soft devices including lab-on-chip, soft robots and flexible electronics. These technologies are currently considered for space exploration applications. We experimentally study the effects of vacuum pressure on the dynamics of PDMS resonator and demonstrate that, unlike hard materials, it exhibits an appreciable change in modulus manifested as a shift in resonance frequency with varying pressure. To reveal this dependence, we carefully probe the dissipation due to air pressure damping acting on the surface of the membrane. For a 1 µm thick membrane, the modulus of the PDMS decreases when the pressure is below P t  =  3.175 Torr, whereas at pressures above {{P}\\text{t}} the dynamics are dominated by gas damping in the free molecular flow and viscous regimes. We conjecture that the observed effect is a consequence of a change in shear modulus resulting in a logarithmic linear relationship between pressure and stiffness for a circular PDMS membrane. These results are important for the application of PDMS microdevices at low pressure.

  10. Perlecan and the Blood-Brain Barrier: Beneficial Proteolysis?

    Directory of Open Access Journals (Sweden)

    Jill eRoberts

    2012-08-01

    Full Text Available The cerebral microvasculature is important for maintaining brain homeostasis. This is achieved via the blood-brain barrier (BBB, composed of endothelial cells with specialized tight junctions, astrocytes and a basement membrane. Prominent components of the basement membrane extracellular matrix (ECM include fibronectin, laminin, collagen IV and perlecan, all of which regulate cellular processes via signal transduction through various cell membrane bound ECM receptors. Expression and proteolysis of these ECM components can be rapidly altered during pathological states of the central nervous system. In particular, proteolysis of perlecan, a heparan sulfate proteoglycan, occurs within hours following ischemia induced by experimental stroke. Proteolysis of ECM components following stroke results in the degradation of the basement membrane and further disruption of the BBB. While it is clear that such proteolysis has negative consequences for the BBB, we propose that it also may lead to generation of ECM protein fragments, including the C-terminal domain V (DV of perlecan, that potentially have a positive influence on other aspects of CNS health. Indeed, perlecan DV has been shown to be persistently generated after stroke and beneficial as a neuroprotective molecule and promoter of post-stroke brain repair. This mini-review will discuss beneficial roles of perlecan protein fragment generation within the brain during stroke.

  11. Alternating current-assisted on-plate proteolysis for MALDI-TOF MS peptide mapping.

    Science.gov (United States)

    Wang, Sheng; Wei, Bangguo; Yang, Pengyuan; Chen, Gang

    2008-11-01

    In this report, alternating current-assisted on-plate proteolysis has been developed for rapid peptide mapping. Protein solutions containing trypsin were allowed to digest directly on the spots of a stainless steel MALDI plate with the assistance of low-voltage alternating current electricity. Alternating current (AC) was allowed to pass through the protein solutions via the MALDI plate and a platinum disc electrode. The feasibility and performance of the novel proteolysis approach were investigated by the digestion of BSA and cytochrome c (Cyt-c). It was demonstrated that AC substantially enhanced the efficiency of proteolysis and the digestion time was significantly reduced to 5 min. The digests were identified by MALDI-TOF MS with sequence coverages of 42% (BSA) and 77% (Cyt-c) that were comparable to those obtained by using conventional in-solution tryptic digestion. The present proteolysis strategy is simple and efficient, offering great promise for MALDI-TOF MS peptide mapping.

  12. Low pressure cooling seal system for a gas turbine engine

    Science.gov (United States)

    Marra, John J

    2014-04-01

    A low pressure cooling system for a turbine engine for directing cooling fluids at low pressure, such as at ambient pressure, through at least one cooling fluid supply channel and into a cooling fluid mixing chamber positioned immediately downstream from a row of turbine blades extending radially outward from a rotor assembly to prevent ingestion of hot gases into internal aspects of the rotor assembly. The low pressure cooling system may also include at least one bleed channel that may extend through the rotor assembly and exhaust cooling fluids into the cooling fluid mixing chamber to seal a gap between rotational turbine blades and a downstream, stationary turbine component. Use of ambient pressure cooling fluids by the low pressure cooling system results in tremendous efficiencies by eliminating the need for pressurized cooling fluids for sealing this gap.

  13. An improved process for high nutrition of germinated brown rice production: Low-pressure plasma.

    Science.gov (United States)

    Chen, Hua Han; Chang, Hung Chia; Chen, Yu Kuo; Hung, Chien Lun; Lin, Su Yi; Chen, Yi Sheng

    2016-01-15

    Brown rice was exposed to low-pressure plasma ranging from 1 to 3kV for 10min. Treatment of brown rice in low-pressure plasma increases the germination percentage, seedling length, and water uptake in laboratory germination tests. Of the various treatments, 3-kV plasma exposure for 10min yielded the best results. In germinating brown rice, α-amylase activity was significantly higher in treated groups than in controls. The higher enzyme activity in plasma-treated brown rice likely triggers the rapid germination and earlier vigor of the seedlings. Low-pressure plasma also increased gamma-aminobutyric acid (GABA) levels from ∼19 to ∼28mg/100g. In addition, a marked increase in the antioxidant activity of brown rice was observed with plasma treatments compared to controls. The main finding of this study indicates that low-pressure plasma is effective at enhancing the growth and GABA accumulation of germinated brown rice, which can supply high nutrition to consumer.

  14. Bulk characterization of pharmaceutical powders by low-pressure compression

    DEFF Research Database (Denmark)

    Sørensen, A.H.; Sonnergaard, Jørn; Hovgaard, L.

    2005-01-01

    for characterization purposes. Significant correlation was demonstrated between several of the compression and tapping-derived parameters. The discriminative power of the low-pressure compression test was discussed using the compressed density at 0.2 MPa, correlated with the tapped density, and the relative Walker...... coefficient, correlated with the Compressibility Index, as examples. The compressed density at 0.2 MPa and the relative Walker coefficient demonstrated excellent discriminative power, superior to the discriminative power of the correlated tapping derived parameters. The low-pressure compression test......Low-pressure compression of pharmaceutical powders using small amounts of sample (50 mg) was evaluated as an alternative to traditional bulk powder characterization by tapping volumetry. Material parameters were extrapolated directly from the compression data and by fitting with the Walker...

  15. A low pressure filter system for new containment concepts

    Energy Technology Data Exchange (ETDEWEB)

    Dillmann, H.G.; Pasler, H. [Kernforschungszentrum Karlsruhe GmbH Laboratorium fuer Isotopentechnik, Karlsruhe (Germany)

    1995-02-01

    It is demonstrated that after severe accidents the decay heat can be removed in a passive mode in a convective flow, i.e. without needing a fan. The filter components with sufficiently low pressure drop values which are required for this purpose will be described and the results indicated.

  16. Spontaneous low-pressure headache complicating bag-piping.

    Science.gov (United States)

    Patrick, Alasdair; McAuley, David; Roxburgh, Richard

    2007-04-01

    We describe an interesting case of a 40-year-old lady who developed a spontaneous low-pressure headache whilst playing the bag-pipes. Playing wind instruments requires the generation of significant intra-thoracic pressure, which may have contributed to this musician's condition.

  17. LOW PRESSURE ULTRAVIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS

    Science.gov (United States)

    Cysts of Giardia muris were inactivated using a low pressure ultravolet (UV) light source. Cyst viability was detemined by both in vitro excystation and animal infectivity. Cyst doeses were counted using a flow cytometer for the animal infectivity experiments. Using in vitro excy...

  18. LOW PRESSURE ULTRAVEIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS

    Science.gov (United States)

    Cysts of Giardia muris were inactivated using a low pressure ultravolet (UV) light source. Cyst viability was detemined by both in vitro excystation and animal infectivity. Cyst doeses were counted using a flow cytometer for the animal infectivity experiments. Using in vitro excy...

  19. Low-pressure valves in hydrocephalic children : a retrospective analysis

    NARCIS (Netherlands)

    Breimer, G. E.; Sival, Deborah; Hoving, E. W.

    2012-01-01

    A series of 100 children under 2 years of age treated for hydrocephalus is described. All patients received a standard differential low-pressure (SD low) valve as the first cerebrospinal fluid (CSF) shunt treatment. The performance of this group during follow-up is analysed. A retrospective cohort s

  20. Low-pressure valves in hydrocephalic children : a retrospective analysis

    NARCIS (Netherlands)

    Breimer, G. E.; Sival, Deborah; Hoving, E. W.

    2012-01-01

    A series of 100 children under 2 years of age treated for hydrocephalus is described. All patients received a standard differential low-pressure (SD low) valve as the first cerebrospinal fluid (CSF) shunt treatment. The performance of this group during follow-up is analysed. A retrospective cohort s

  1. Infrared-assisted on-plate proteolysis for MALDI-TOF-MS peptide mapping.

    Science.gov (United States)

    Wang, Sheng; Bao, Huimin; Zhang, Luyan; Yang, Pengyuan; Chen, Gang

    2008-07-15

    In this report, infrared (IR)-assisted on-plate proteolysis has been developed for rapid peptide mapping. Protein solutions containing trypsin were allowed to digest directly on the spots of matrix-assisted laser desorption/ionization (MALDI) plates under IR radiation. The feasibility and performance of the novel proteolysis approach were investigated by the digestion of bovine serum albumin (BSA) and cytochrome c (Cyt-c). It was demonstrated that IR radiation substantially enhanced the efficiency of proteolysis and the digestion time was significantly reduced to 5 min. The digests were identified by MALDI time-of-flight mass spectrometry with sequence coverages of 55 (BSA) and 75% (Cyt-c) that were comparable to those obtained by using conventional in-solution tryptic digestion. The suitability of IR-assisted on-plate proteolysis to complex proteins was demonstrated by digesting human serum and casein extracted from commercially available milk sample. The present proteolysis strategy is simple and efficient, offering great promise for high-throughput protein identification.

  2. Proteolysis and consistency of Meshanger cheese

    NARCIS (Netherlands)

    Jong, de L.

    1978-01-01

    Proteolysis in Meshanger cheese, estimated by quantitative polyacrylamide gel electrophoresis is discussed. The conversion of α s1 -casein was proportional to rennet concentration in the cheese. Changes in consistency, after a maximum, were correlated to breakdown of

  3. Regulatory Proteolysis in Arabidopsis-Pathogen Interactions

    OpenAIRE

    Miklós Pogány; Tamás Dankó; Evelin Kámán-Tóth; Ildikó Schwarczinger; Zoltán Bozsó

    2015-01-01

    Approximately two and a half percent of protein coding genes in Arabidopsis encode enzymes with known or putative proteolytic activity. Proteases possess not only common housekeeping functions by recycling nonfunctional proteins. By irreversibly cleaving other proteins, they regulate crucial developmental processes and control responses to environmental changes. Regulatory proteolysis is also indispensable in interactions between plants and their microbial pathogens. Proteolytic cleavage is s...

  4. Kinetic analysis of negative power deposition in low pressure plasmas

    CERN Document Server

    Trieschmann, Jan

    2016-01-01

    The negative power absorption in low pressure plasmas is investigated by means of an analyical model which couples Boltzmann's equation and the quasi-stationary Maxwell's equation. Exploiting standard Hilbert space methods an explicit solution for both, the electric field and the distribution function of the electrons for a bounded discharge configuration subject to an unsymmetrical excitation has been found for the first time. The model is applied to a low pressure inductively coupled plasma discharge. In this context particularly the anomalous skin effect and the effect of phase mixing is discussed. The analytical solution is compared with results from electromagnetic full wave particle in cell simulations. Excellent agreement between the analytical and the numerical results is found.

  5. Heat transfer by condensation of low pressure metal vapors.

    Science.gov (United States)

    Huang, Y. S.; Lyman, F. A.; Lick, W. J.

    1972-01-01

    The film condensation of low pressure metal vapors on isothermal vertical flat plates or tubes is considered. The liquid film is treated as a thin layer in which the acceleration and pressure forces are negligible and across which the temperature distribution is linear. The average behavior of the vapor is found from the linearized one-dimensional vapor flow equations. In order to calculate the rate of condensation, a consistent distribution function for the vapor particles at the liquid-vapor interface is necessary and is determined. The result of the analysis is a set of algebraic equations from which one can predict the condensation rate of low pressure metal vapors. A large but continuous temperature decrease in the vapor is predicted and calculated.

  6. LOW-PRESSURE MEMBRANE CONTACTORS FOR CARBON DIOXIDE CAPTURE

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Richard; Kniep, Jay; Hao, Pingjiao; Chan, Chi Cheng; Nguyen, Vincent; Huang, Ivy; Amo, Karl; Freeman, Brice; Fulton, Don; Ly, Jennifer; Lipscomb, Glenn; Lou, Yuecun; Gogar, Ravikumar

    2014-09-30

    This final technical progress report describes work conducted by Membrane Technology and Research, Inc. (MTR) for the Department of Energy (DOE NETL) on development of low-pressure membrane contactors for carbon dioxide (CO2) capture from power plant flue gas (award number DE-FE0007553). The work was conducted from October 1, 2011 through September 30, 2014. The overall goal of this three-year project was to build and operate a prototype 500 m2 low-pressure sweep membrane module specifically designed to separate CO2 from coal-fired power plant flue gas. MTR was assisted in this project by a research group at the University of Toledo, which contributed to the computational fluid dynamics (CFD) analysis of module design and process simulation. This report details the work conducted to develop a new type of membrane contactor specifically designed for the high-gas-flow, low-pressure, countercurrent sweep operation required for affordable membrane-based CO2 capture at coal power plants. Work for this project included module development and testing, design and assembly of a large membrane module test unit at MTR, CFD comparative analysis of cross-flow, countercurrent, and novel partial-countercurrent sweep membrane module designs, CFD analysis of membrane spacers, design and fabrication of a 500 m2 membrane module skid for field tests, a detailed performance and cost analysis of the MTR CO2 capture process with low-pressure sweep modules, and a process design analysis of a membrane-hybrid separation process for CO2 removal from coal-fired flue gas. Key results for each major task are discussed in the report.

  7. APHRON-BASED DRILLING FLUIDS: SOLUTION FOR LOW PRESSURE RESERVOIRS

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2009-12-01

    Full Text Available Drilling wells throughout depleted or low pressure reservoirs requires low density drilling fluids, often with density less than water. Methods to reduce the density of drilling fluids have included mixing-in air or nitrogen. However, problems with these approaches include instability of gas bubbles (bubbles collapse or expand and increased costs. Recently, the use of micro bubbles named aphrons in drilling, completion and workover fluids has proven success in solving many problems related to low pressure reservoirs such as fluid loss control, formation damage, stabilization of multipressure sequences with one fluid and possible differential sticking. Aphrons represent bubble with uniquely structure stabilized with surfactant. Against conventional micro bubbles, aphrons are more stable in downhole conditions and they are generated using standard mixing equipment. Owing to their properties and overpressure in wellbore aphrons penetrate into low pressure layers and set up inner bridging. Depleted wells which are very expensive to drill underbalanced or with other remediation techniques can now be drilled overbalanced. This paper presents description of aphron structure and stability, aphron bridging mechanism, aphron-based fluid composition and properties, and field experiences in applying aphron-based fluids.

  8. Bulk characterization of pharmaceutical powders by low-pressure compression.

    Science.gov (United States)

    Sørensen, Arne Hagsten; Sonnergaard, Jørn Møller; Hovgaard, Lars

    2005-01-01

    Low-pressure compression of pharmaceutical powders using small amounts of sample (50 mg) was evaluated as an alternative to traditional bulk powder characterization by tapping volumetry. Material parameters were extrapolated directly from the compression data and by fitting with the Walker, the Kawakita, and the Log-Exp compression models. The compression-derived material parameters were compared to the poured and tapped density and the Compressibility Index determined by tapping. The repeatability of the compression-derived parameters was generally high, supporting their potential for characterization purposes. Significant correlation was demonstrated between several of the compression and tapping-derived parameters. The discriminative power of the low-pressure compression test was discussed using the compressed density at 0.2 MPa, correlated with the tapped density, and the relative Walker coefficient, correlated with the Compressibility Index, as examples. The compressed density at 0.2 MPa and the relative Walker coefficient demonstrated excellent discriminative power, superior to the discriminative power of the correlated tapping derived parameters. The low-pressure compression test was concluded to provide a cost-effective and sensitive alternative to traditional tapping volumetry.

  9. Low pressure gas collection system : solving environmental problems

    Energy Technology Data Exchange (ETDEWEB)

    Saputelli, L.A. [PDVSA Exploracion and Produccion (Venezuela)

    1998-09-01

    Alternative solutions to flaring for collecting low pressure gases in oil fields, were discussed. Many different solutions for boosting or collecting low pressure gases and mixing them into the oil stream were examined. A solution for collecting low pressure gases using existing field facilities was proposed. Main factors considered in designing this solution included: (1) the use of existing power facilities, (2) low up-scaling cost, (3) keeping harmony with the environment, and (4) maintaining well efficiencies. Field trials (conducted in 1982) consisted of the testing of 10 `Ecopres` compressors in the Bolivar coastal field, Lake Maracaibo, Venezuela, in order to maximize gas utilization. The tests showed that it was possible to recover up to 99 per cent of annular gas with no reduction in oil well productivity but there was a 21 per cent reduction in oil production when the annular flow was connected directly to the flow line. In the proposed alternative solution, annular spaces are open to atmospheric pressure. The proposed system consists of a single stage gas compressor attached to a heat exchanger and a single stage gas turbine. 4 refs., 9 figs.

  10. Extracellular proteolysis in the adult murine brain.

    Science.gov (United States)

    Sappino, A P; Madani, R; Huarte, J; Belin, D; Kiss, J Z; Wohlwend, A; Vassalli, J D

    1993-08-01

    Plasminogen activators are important mediators of extracellular metabolism. In the nervous system, plasminogen activators are thought to be involved in the remodeling events required for cell migration during development and regeneration. We have now explored the expression of the plasminogen activator/plasmin system in the adult murine central nervous system. Tissue-type plasminogen activator is synthesized by neurons of most brain regions, while prominent tissue-type plasminogen activator-catalyzed proteolysis is restricted to discrete areas, in particular within the hippocampus and hypothalamus. Our observations indicate that tissue-type plasminogen activator-catalyzed proteolysis in neural tissues is not limited to ontogeny, but may also contribute to adult central nervous system physiology, for instance by influencing neuronal plasticity and synaptic reorganization. The identification of an extracellular proteolytic system active in the adult central nervous system may also help gain insights into the pathogeny of neurodegenerative disorders associated with extracellular protein deposition.

  11. DNA-Protein Crosslink Proteolysis Repair.

    Science.gov (United States)

    Vaz, Bruno; Popovic, Marta; Ramadan, Kristijan

    2017-06-01

    Proteins that are covalently bound to DNA constitute a specific type of DNA lesion known as DNA-protein crosslinks (DPCs). DPCs represent physical obstacles to the progression of DNA replication. If not repaired, DPCs cause stalling of DNA replication forks that consequently leads to DNA double-strand breaks, the most cytotoxic DNA lesion. Although DPCs are common DNA lesions, the mechanism of DPC repair was unclear until now. Recent work unveiled that DPC repair is orchestrated by proteolysis performed by two distinct metalloproteases, SPARTAN in metazoans and Wss1 in yeast. This review summarizes recent discoveries on two proteases in DNA replication-coupled DPC repair and establishes DPC proteolysis repair as a separate DNA repair pathway for genome stability and protection from accelerated aging and cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. A wireless and passive low-pressure sensor.

    Science.gov (United States)

    Nicolay, Pascal; Lenzhofer, Martin

    2014-02-17

    This paper will discuss the results obtained with a first prototype of a completely passive and wireless low pressure sensor. The device is a heat conductivity gauge, based on a wireless and passive SAW temperature sensor. The required heating energy is applied to the sensor using inductive coupling. The prototype was successfully tested in a vacuum chamber. Its equilibrium temperature changed drastically and in a reproducible way when pressure steps were applied. However, the response time was very long. A model is provided to account for the sensor's behavior. It is then used to show that the response time could be strongly improved using basic design improvements. Further possible improvements are discussed.

  13. Global Instability and Control of Low-Pressure Turbine Flows

    Science.gov (United States)

    2006-03-31

    Methodos Numericos in Ingenieria 2005, Granada Y 3 rd Symposium on Global Flow Instability and Control September 2005 Crete, Greece. * AIAA San...valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To...31-03-2006 Final 01-02-2003 To 31-12-2005 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Global Instability and Control of Low Pressure Turbine Flows 5b

  14. Device for calibration of low pressure gauges development

    OpenAIRE

    Nikitović Ž.D.

    2002-01-01

    Vacuum system set-up is presented and used for calibration of pressure gauges in the region of rough vacuum, from 103 mbar to 10-1 mbar, with dry air. The capacitance manometer is used for the calibration of piezoresistant manometer, oil, mercury and mercury micrometers U manometers. The applicability of the experimental set-up and obtained results for the low pressure gauges calibration in the medium and high vacuum region is approved. It was shown how calibration of some cheaper pressure ga...

  15. Low pressure growth of cubic boron nitride films

    Science.gov (United States)

    Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

    1997-01-01

    A method for forming thin films of cubic boron nitride on substrates at low pressures and temperatures. A substrate is first coated with polycrystalline diamond to provide a uniform surface upon which cubic boron nitride can be deposited by chemical vapor deposition. The cubic boron nitride film is useful as a substitute for diamond coatings for a variety of applications in which diamond is not suitable. any tetragonal or hexagonal boron nitride. The cubic boron nitride produced in accordance with the preceding example is particularly well-suited for use as a coating for ultra hard tool bits and abrasives, especially those intended to use in cutting or otherwise fabricating iron.

  16. Predicted thermal superluminescence in low-pressure air

    CERN Document Server

    Aramyan, A R; Galechyan, G A; Mangasaryan, N R; Nersisyan, H B

    2009-01-01

    It is shown that due to the dissociation of the molecular oxygen it is possible to obtain inverted population in low pressure air by heating. As a result of the quenching of the corresponding levels of the atomic oxygen the thermal superluminescent radiation is generated. It has been found that the threshold of the overpopulation is exceeded at the air temperature 2300-3000 K. Using this effect a possible mechanism for the generation of the flashes of the radiation in air observed on the airframe of the space shuttle during its descent and reentry in the atmosphere is suggested.

  17. Cellular contractility requires ubiquitin mediated proteolysis.

    Directory of Open Access Journals (Sweden)

    Yuval Cinnamon

    Full Text Available BACKGROUND: Cellular contractility, essential for cell movement and proliferation, is regulated by microtubules, RhoA and actomyosin. The RhoA dependent kinase ROCK ensures the phosphorylation of the regulatory Myosin II Light Chain (MLC Ser19, thereby activating actomyosin contractions. Microtubules are upstream inhibitors of contractility and their depolymerization or depletion cause cells to contract by activating RhoA. How microtubule dynamics regulates RhoA remains, a major missing link in understanding contractility. PRINCIPAL FINDINGS: We observed that contractility is inhibited by microtubules not only, as previously reported, in adherent cells, but also in non-adhering interphase and mitotic cells. Strikingly we observed that contractility requires ubiquitin mediated proteolysis by a Cullin-RING ubiquitin ligase. Inhibition of proteolysis, ubiquitination and neddylation all led to complete cessation of contractility and considerably reduced MLC Ser19 phosphorylation. CONCLUSIONS: Our results imply that cells express a contractility inhibitor that is degraded by ubiquitin mediated proteolysis, either constitutively or in response to microtubule depolymerization. This degradation seems to depend on a Cullin-RING ubiquitin ligase and is required for cellular contractions.

  18. Protonation enhancement by dichloromethane doping in low-pressure photoionization

    Science.gov (United States)

    Shu, Jinian; Zou, Yao; Xu, Ce; Li, Zhen; Sun, Wanqi; Yang, Bo; Zhang, Haixu; Zhang, Peng; Ma, Pengkun

    2016-12-01

    Doping has been used to enhance the ionization efficiency of analytes in atmospheric pressure photoionization, which is based on charge exchange. Compounds with excellent ionization efficiencies are usually chosen as dopants. In this paper, we report a new phenomenon observed in low-pressure photoionization: Protonation enhancement by dichloromethane (CH2Cl2) doping. CH2Cl2 is not a common dopant due to its high ionization energy (11.33 eV). The low-pressure photoionization source was built using a krypton VUV lamp that emits photons with energies of 10.0 and 10.6 eV and was operated at ~500–1000 Pa. Protonation of water, methanol, ethanol, and acetaldehyde was respectively enhanced by 481.7 ± 122.4, 197.8 ± 18.8, 87.3 ± 7.8, and 93.5 ± 35.5 times after doping 291 ppmv CH2Cl2, meanwhile CH2Cl2 almost does not generate noticeable ions itself. This phenomenon has not been documented in the literature. A new protonation process involving in ion-pair and H-bond formations was proposed to expound the phenomenon. The observed phenomenon opens a new prospect for the improvement of the detection efficiency of VUV photoionization.

  19. Low pressure storage of natural gas on activated carbon

    Science.gov (United States)

    Wegrzyn, J.; Wiesmann, H.; Lee, T.

    The introduction of natural gas to the transportation energy sector offers the possibility of displacing imported oil with an indigenous fuel. The barrier to the acceptance of natural gas vehicles (NGV) is the limited driving range due to the technical difficulties of on-board storage of a gaseous fuel. In spite of this barrier, compressed natural gas (CNG) vehicles are today being successfully introduced into the market place. The purpose of this work is to demonstrate an adsorbent natural gas (ANG) storage system as a viable alternative to CNG storage. It can be argued that low pressure ANG has reached near parity with CNG, since the storage capacity of CNG (2400 psi) is rated at 190 V/V, while low pressure ANG (500 psi) has reached storage capacities of 180 V/V in the laboratory. A program, which extends laboratory results to a full-scale vehicle test, is necessary before ANG technology will receive widespread acceptance. The objective of this program is to field test a 150 V/V ANG vehicle in FY 1994. As a start towards this goal, carbon adsorbents have been screened by Brookhaven for their potential use in a natural gas storage system. This paper reports on one such carbon, trade name Maxsorb, manufactured by Kansai Coke under an Amoco license.

  20. Protonation enhancement by dichloromethane doping in low-pressure photoionization

    CERN Document Server

    Shu, Jinian; Xu, Ce; Li, Zhen; Sun, Wanqi; Yang, Bo; Zhang, Haixu; Zhang, Peng; Ma, Pengkun

    2016-01-01

    Doping has been used to enhance the ionization efficiency of analytes in atmospheric pressure photoionization, which is based on charge exchange. Compounds with excellent ionization efficiencies are usually chosen as dopants. In this paper, we report a new phenomenon observed in low-pressure photoionization: Protonation enhancement by dichloromethane (CH2Cl2) doping. CH2Cl2 is not a common dopant due to its high ionization energy (11.33 eV). The low-pressure photoionization source was built using a krypton VUV lamp that emits photons with energies of 10.0 and 10.6 eV and was operated at 500-1000 Pa. Protonation of water, methanol, ethanol, and acetaldehyde was respectively enhanced by 481.7 +/- 122.4, 197.8 +/- 18.8, 87.3 +/- 7.8, and 93.5 +/- 35.5 times after doping 291 ppmv CH2Cl2, meanwhile CH2Cl2 almost does not generate noticeable ions itself. This phenomenon has not been documented in the literature. A new protonation process involving in ion-pair and H-bond formations was proposed to expound the phenom...

  1. Performance assessment of low pressure nuclear thermal propulsion

    Science.gov (United States)

    Gerrish, Harrold P., Jr.; Doughty, Glen E.

    1993-01-01

    An increase in Isp for nuclear thermal propulsion systems is desirable for reducing the propellant requirements and cost of future applications, such as the Mars Transfer Vehicle. Several previous design studies have suggested that the Isp could be increased substantially with hydrogen dissociation/recombination. Hydrogen molecules (H2), at high temperatures and low pressures, will dissociate to monatomic hydrogen (H). The reverse process (i.e., formation of H2 from H) is exothermic. The exothermic energy in a nozzle increases the kinetic energy and therefore, increases the Isp. The low pressure nuclear thermal propulsion system (LPNTP) system is expected to maximize the hydrogen dissociation/recombination and Isp by operating at high chamber temperatures and low chamber pressures. The process involves hydrogen flow through a high temperature, low pressure fission reactor, and out a nozzle. The high temperature (approximately 3000 K) of the hydrogen in the reactor is limited by the temperature limits of the reactor material. The minimum chamber pressure is about 1 atm because lower pressures decrease the engines thrust to weight ratio below acceptable limits. This study assumes that hydrogen leaves the reactor and enters the nozzle at the 3000 K equilibrium dissociation level. Hydrogen dissociation in the reactor does not affect LPNTP performance like dissociation in traditional chemical propulsion systems, because energy from the reactor resupplies energy lost due to hydrogen dissociation. Recombination takes place in the nozzle due primarily to a drop in temperature as the Mach number increases. However, as the Mach number increases beyond the nozzle throat, the static pressure and density of the flow decreases and minimizes the recombination. The ideal LPNTP Isp at 3000 K and 10 psia is 1160 seconds due to the added energy from fast recombination rates. The actual Isp depends on the finite kinetic reaction rates which affect the amount of monatomic hydrogen

  2. Electron heating in low pressure capacitive discharges revisited

    Science.gov (United States)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2014-12-01

    The electrons in capacitively coupled plasmas (CCPs) absorb energy via ohmic heating due to electron-neutral collisions and stochastic heating due to momentum transfer from high voltage moving sheaths. We use Particle-in-Cell (PIC) simulations to explore these heating mechanisms and to compare the PIC results with available theories on ohmic and stochastic heating. The PIC results for ohmic heating show good agreement with the ohmic heating calculation of Lafleur et al. [Phys. Plasmas 20, 124503 (2013)]. The PIC results for stochastic heating in low pressure CCPs with collisionless sheaths show good agreement with the stochastic heating model of Kaganovich et al. [IEEE Trans. Plasma Sci. 34, 696 (2006)], which revises the hard wall asymptotic model of Lieberman [IEEE Trans. Plasma Sci. 16, 638 (1988)] by taking current continuity and bulk oscillation into account.

  3. Low pressure powder injection moulding of stainless steel powders

    Energy Technology Data Exchange (ETDEWEB)

    Zampieron, J.V.; Soares, J.P.; Mathias, F.; Rossi, J.L. [Powder Processing Center CCP, Inst. de Pesquisas Energeticas e Nucleares, Sao Paulo, SP (Brazil); Filho, F.A. [IPEN, Inst. de Pesquisas Energeticas e Nucleares, Cidade Univ., Sao Paulo, SP (Brazil)

    2001-07-01

    Low-pressure powder injection moulding was used to obtain AISI 316L stainless steel parts. A rheological study was undertaken using gas-atomised powders and binders. The binders used were based on carnauba wax, paraffin, low density polyethylene and microcrystalline wax. The metal powders were characterised in terms of morphology, particle size distribution and specific surface area. These results were correlated to the rheological behaviour. The mixture was injected in the shape of square bar specimens to evaluate the performance of the injection process in the green state, and after sintering. The parameters such as injection pressure, viscosity and temperature were analysed for process optimisation. The binders were thermally removed in low vacuum with the assistance of alumina powders. Debinding and sintering were performed in a single step. This procedure shortened considerably the debinding and sintering time. (orig.)

  4. Numerical simulation of low pressure die-casting aluminum wheel

    Institute of Scientific and Technical Information of China (English)

    Mi Guofa; Liu Xiangyu; Wang Kuangfei; Fu Hengzhi

    2009-01-01

    The FDM numerical simulation software, ViewCast system, was employed to simulate the low pressure die casting (LPDC) of an aluminum wheel. By analyzing the mold-filling and solidification stage of the LPDC process, the distribution of liquid fraction, temperature field and solidification pattern of castings were studied. The potential shrinkage defects were predicted to be formed at the rim/spoke junctions, which is in consistence with the X-ray detection result. The distribution pattern of the defects has also been studied. A solution towards reducing such defects has been presented. The cooling capacity of the mold was improved by installing water pipes both in the side mold and the top mold. Analysis on the shrinkage defects under forced cooling mode proved that adding the cooling system in the mold is an effective method for reduction of shrinkage defects.

  5. Low-Pressure Turbine Separation Control: Comparison With Experimental Data

    Science.gov (United States)

    Garg, Vijay K.

    2002-01-01

    The present work details a computational study, using the Glenn HT code, that analyzes the use of vortex generator jets (VGJs) to control separation on a low-pressure turbine (LPT) blade at low Reynolds numbers. The computational results are also compared with the experimental data for steady VGJs. It is found that the code determines the proper location of the separation point on the suction surface of the baseline blade (without any VGJ) for Reynolds numbers of 50,000 or less. Also, the code finds that the separated region on the suction surface of the blade vanishes with the use of VGJs. However, the separated region and the wake characteristics are not well predicted. The wake width is generally over-predicted while the wake depth is under-predicted.

  6. A Wireless and Passive Low-Pressure Sensor

    Directory of Open Access Journals (Sweden)

    Pascal Nicolay

    2014-02-01

    Full Text Available This paper will discuss the results obtained with a first prototype of a completely passive and wireless low pressure sensor. The device is a heat conductivity gauge, based on a wireless and passive SAW temperature sensor. The required heating energy is applied to the sensor using inductive coupling. The prototype was successfully tested in a vacuum chamber. Its equilibrium temperature changed drastically and in a reproducible way when pressure steps were applied. However, the response time was very long. A model is provided to account for the sensor’s behavior. It is then used to show that the response time could be strongly improved using basic design improvements. Further possible improvements are discussed.

  7. Very low pressure high power impulse triggered magnetron sputtering

    Science.gov (United States)

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  8. Low-pressure hydrogen plasmas explored using a global model

    Science.gov (United States)

    Samuell, Cameron M.; Corr, Cormac S.

    2016-02-01

    Low-pressure hydrogen plasmas have found applications in a variety of technology areas including fusion, neutral beam injection and material processing applications. To better understand these discharges, a global model is developed to predict the behaviour of electrons, ground-state atomic and molecular hydrogen, three positive ion species (H+, \\text{H}2+ , and \\text{H}3+ ), a single negative ion species (H-), and fourteen vibrationally excited states of molecular hydrogen ({{\\text{H}}2}≤ft(\\upsilon =1\\right. -14)). The model is validated by comparison with experimental results from a planar inductively coupled GEC reference cell and subsequently applied to the MAGPIE linear helicon reactor. The MAGPIE reactor is investigated for a range of pressures from 1 to 100 mTorr and powers up to 5 kW. With increasing power between 50 W and 5 kW at 10 mTorr the density of all charged species increases as well as the dissociative fraction while the electron temperature remains almost constant at around 3 eV. For gas pressures from 1-100 mTorr at an input power of 1 kW, the electron density remains almost constant, the electron temperature and dissociative fraction decreases, while \\text{H}3+ density increases in density and also dominates amongst ion species. Across these power and pressure scans, electronegativity remains approximately constant at around 2.5%. The power and pressure determines the dominant ion species in the plasma with \\text{H}3+ observed to dominate at high pressures and low powers whereas H+ tends to be dominant at low pressures and high powers. A sensitivity analysis is used to demonstrate how experimental parameters (power, pressure, reactor wall material, geometry etc) influence individual species’ density as well as the electron temperature. Physical reactor changes including the length, radius and wall recombination coefficient are found to have the largest influence on outputs obtained from the model.

  9. Proteolysis in microfluidic droplets: an approach to interface protein separation and peptide mass spectrometry

    OpenAIRE

    Ji, Ji; Nie, Lei; Qiao, Liang; Li, Yixin; Guo, Liping; Liu, Baohong; Yang, Pengyuan; Girault, Hubert H.

    2012-01-01

    A versatile microreactor protocol based on microfluidic droplets has been developed for on-line protein digestion. Proteins separated by liquid chromatography are fractionated in water-in-oil droplets and digested in sequence. The microfluidic reactor acts also as an electrospray ionization emitter for mass spectrometry analysis of the peptides produced in the individual droplets. Each droplet is an enzymatic micro-reaction unit with efficient proteolysis due to rapid mixing, enhanced mass tr...

  10. Optimization of process parameter for synthesis of silicon quantum dots using low pressure chemical vapour deposition

    Indian Academy of Sciences (India)

    Dipika Barbadikar; Rashmi Gautam; Sanjay Sahare; Rajendra Patrikar; Jatin Bhatt

    2013-06-01

    Si quantum dots-based structures are studied recently for performance enhancement in electronic devices. This paper presents an attempt to get high density quantum dots (QDs) by low pressure chemical vapour deposition (LPCVD) on SiO2 substrate. Surface treatment, annealing and rapid thermal processing (RTP) are performed to study their effect on size and density of QDs. The samples are also studied using Fourier transformation infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM) and photoluminescence study (PL). The influence of Si–OH bonds formed due to surface treatment on the density of QDs is discussed. Present study also discusses the influence of surface treatment and annealing on QD formation.

  11. Thermodynamic analysis of cascade microcryocoolers with low pressure ratios

    Energy Technology Data Exchange (ETDEWEB)

    Radebaugh, Ray [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2014-01-29

    The vapor-compression cycle for refrigeration near ambient temperature achieves high efficiency because the isenthalpic expansion of the condensed liquid is a rather efficient process. However, temperatures are limited to about 200 K with a single-stage system. Temperatures down to 77 K are possible with many stages. In the case of microcryocoolers using microcompressors, pressure ratios are usually limited to about 6 or less. As a result, even more stages are required to reach 77 K. If the microcompressors can be fabricated with low-cost wafer-level techniques, then the use of many stages with separate compressors may become a viable option for achieving temperatures of 77 K with high efficiency. We analyze the ideal thermodynamic efficiency of a cascade Joule-Thomson system for various temperatures down to 77 K and with low pressure ratios. About nine stages are required for 77 K, but fewer stages are also analyzed for operation at higher temperatures. For 77 K, an ideal second-law efficiency of 83 % of Carnot is possible with perfect recuperative heat exchangers and 65 % of Carnot is possible with no recuperative heat exchangers. The results are compared with calculated efficiencies in mixed-refrigerant cryocoolers over the range of 77 K to 200 K. Refrigeration at intermediate temperatures is also available. The use of single-component fluids in each of the stages is expected to eliminate the problem of pulsating flow and temperature oscillations experienced in microcryocoolers using mixed refrigerants.

  12. Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

    Science.gov (United States)

    Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

    2016-09-01

    Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

  13. "Politically-Incorrect" Electron Behavior in Low Pressure RF Discharges

    Science.gov (United States)

    Godyak, Valery; Kolobov, Vladimir

    1996-10-01

    The main interaction of plasma electrons with electromagnetic fields for bounded plasma of an rf discharge occurs in the vicinity of its boundaries (in the rf sheath of a capacitive rf discharge and in the skin layer of an inductive one). On the other hand, due to plasma inhomogeneity, a dc ambipolar field is always present in the bounded plasma. in low pressure discharges the ambipolar potential well captures low energy electrons within the discharge center while high energy electrons freely overcome the ambipolar potential and reach the plasma boundaries where heating takes place. Being segregated in space, low energy electrons are discriminated from participation in the heating process. When Coulomb interaction between low and high energy electron groups is weak, their temperatures appear to be essentially different ( a low energy peak on the EEDF). In this presentation we present theoretical and experimental evidence of such an apartheid in the low and high energy electron populations of the EEDF in rf discharge and we outline discharge conditions where such abnormal EEDF behavior is possible.

  14. Absorption spectrum of very low pressure atomic hydrogen

    CERN Document Server

    Moret-Bailly, Jacques

    2015-01-01

    Spectra of quasars result primarily from interactions of natural light with atomic hydrogen. A visible absorption of a sharp and saturated spectral line in a gas requires a low pressure, so a long path without blushing as a cosmological redshift. Burbidge and Karlsson observed that redshifts of quasars result from fundamental redshifts, written 3K and 4K, that cause a shift of absorbed beta and gamma lines of H to alpha gas line. Thus absorbed spectrum is shifted until an absorbed line overlaps with Lyman alpha line of gas: redshift only occurs if an alpha absorption pumps atoms to 2P state. Thus, space is divided into spherical shells centered on the quasar, containing or not 2P atoms. Neglecting collisional de-excitations in absorbing shells, more and more atoms are excited until amplification of a beam having a long path in a shell, thus perpendicular to the observed ray, is large enough for a superradiant flash at alpha frequency. Energy is provided by atoms and observed ray, absorbing a line at local Lym...

  15. Endoscopic PIV measurements in a low pressure turbine rig

    Energy Technology Data Exchange (ETDEWEB)

    Kegalj, Martin; Schiffer, Heinz-Peter [Technische Universitaet Darmstadt (Germany). Department of Gas Turbines and Aerospace Propulsion

    2009-10-15

    Particle-Image-Velocimetry (PIV) is a useful way to acquire information about the flow in turbomachinery. Several premises have to be fulfilled to achieve high-quality data, for example, optical access, low vibrations and low reflections. However, not all test facilities comply with these requirements. If there is no optical access to the test area, measurements cannot be performed. The use of borescopic optics is a possible solution to this issue, as the access required is very small. Several different techniques can be used to measure the three components of the velocity vector, one of which is Stereo-PIV. These techniques require either large optical access from several viewing angles or highly complex setups. Orthogonal light sheet orientations in combination with borescopic optics using Planar-PIV can deliver sufficient information about the flow. This study will show the feasibility of such an approach in an enclosed test area, such as the interblade space in a Low-Pressure-Turbine-Rig. The results from PIV will be compared with data collected with conventional techniques, such as the Five-Hole-Probe and the 2-component Hot-Wire-Anemometry. An analysis of time- and phase-averaged data will be performed. (orig.)

  16. Characteristics of Cylindrical Microwave Plasma Source at Low Pressure

    Science.gov (United States)

    Park, Seungil; Youn, S.; Kim, S. B.; Yoo, S. J.

    2016-10-01

    A microwave plasma source with a cylindrical resonance cavity has been proposed to generate the plasma at low pressure. This plasma source consists of magnetron, waveguide, antenna, and cavity. The microwave generating device is a commercial magnetron with 1 kW output power at the frequency of 2.45 GHz. The microwave is transmitted through the rectangular waveguide with the whistle shape, and coupled to the cavity by the slot antenna. The resonant mode of the cylindrical cavity is the TE111 mode. The operating pressure is between 0.1 Torr and 0.3 Torr with the Argon and nitrogen gas. The electron temperature and electron number density of argon plasma were measured with the optical emission spectroscopy measurement. And Ar1s5 metastable density was measured using tunable diode laser absorption spectroscopy (TDLAS). The plasma diagnostic results of a cylindrical microwave plasma source would be described in this study. This work was supported by R&D Program of ``Plasma Advanced Technology for Agriculture and Food (Plasma Farming)'' through the National Fusion Research Institute of Korea (NFRI) funded by the Government funds.

  17. Longitudinal discharge pumped low-pressure XeCl laser

    Science.gov (United States)

    Fedorov, A. I.

    2013-10-01

    We have studied output parameters of a XeCl and a N2 laser pumped by a longitudinal discharge with automatic spark UV preionisation. The output parameters of a low-pressure (30 Torr) XeCl laser operating with Ar, Ne and He as buffer gases or with no buffer gas have been optimised for the first time. The laser generated 5-ns FWHM pulses with an average power of 0.5 mW and output energy of 0.15 mJ. Under longitudinal discharge pumping, an output energy per unit volume of 1.8 J L-1 atm-1 was reached using helium as a buffer gas. With argon-containing and buffer-free mixtures, it was 1.5 J L-1 atm-1. The N2 laser generated 2.5-ns FWHM pulses with an average power of 0.35 mW and output energy of 0.05 mJ.

  18. Onset of Nucleate Boiling in Rectangular Channels under Low Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jung Hyun; Lee, Juhyung; Jeong, Yong Hoon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Chang, Soon Heung [Handong University, Pohang (Korea, Republic of)

    2015-10-15

    In this study, new methodology to define ONB point based on the heat transfer coefficient difference between single phase heat transfer and two phase heat transfer using single phase heat transfer correlation. In addition, several existing ONB prediction correlations based on the Hsu's model showed large error with experimental data. It can support that not only heat flux and wall superheat, but also the local parameters should be figured into ONB prediction. Nuclear reactors can be divided into two types; commercial reactor and research reactor. Radiation from research reactors is used for many industries. Due to that characteristic of research reactors, as many people work around research reactor, the design with conservative safety margin for research reactor is more sensitive issue. Some research reactors such as the Jordan Research and Training Reactor (JRTR) have three characteristics. First, they operate under atmospheric pressure. Second, they use the nuclear fuel plate. Third, they use downward flow to remove the heat of the fuel plate. However, one of the precautions of using downward flow under low pressure is that fluid behavior can change much faster than under high pressure. Bubble nucleation itself is not important for nuclear reactor safety at all, but it can be lead to critical thermal-hydraulic events such as onset of fluid instability (OFI) or critical heat flux (CHF) easily. Also, bubble nucleation would be avoided to maintain the steady normal operation. The IAEA also recommends for research reactors to have enough ONB margin to maintain a normal operation state in 'IAEA-TECDOC-233' (1980). It can support that the existing ONB prediction correlations are not suitable for predict ONB in rectangular channel and new correlation is needed to this condition.

  19. Studies of Methane Counterflow Flames at Low Pressures

    Science.gov (United States)

    Burrell, Robert Roe

    Methane is the smallest hydrocarbon molecule, the fuel most widely studied in fundamental flame structure studies, and a major component of natural gas. Despite many decades of research into the fundamental chemical kinetics involved in methane oxidation, ongoing advancements in research suggest that more progress can be made. Though practical combustors of industrial and commercial significance operate at high pressures and turbulent flow conditions, fundamental understanding of combustion chemistry in flames is more readily obtained for low pressure and laminar flow conditions. Measurements were performed from 1 to 0.1 atmospheres for premixed methane/air and non-premixed methane-nitrogen/oxygen flames in a counterflow. Comparative modeling with quasi-one-dimensional strained flame codes revealed bias-induced errors in measured velocities up to 8% at 0.1 atmospheres due to tracer particle phase velocity slip in the low density gas reacting flow. To address this, a numerically-assisted correction scheme consisting of direct simulation of the particle phase dynamics in counterflow was implemented. Addition of reactions describing the prompt dissociation of formyl radicals to an otherwise unmodified USC Mech II kinetic model was found to enhance computed flame reactivity and substantially improve the predictive capability of computed results for measurements at the lowest pressures studied. Yet, the same modifications lead to overprediction of flame data at 1 atmosphere where results from the unmodified USC Mech II kinetic mechanism agreed well with ambient pressure flame data. The apparent failure of a single kinetic model to capture pressure dependence in methane flames motivates continued skepticism regarding the current understanding of pressure dependence in kinetic models, even for the simplest fuels.

  20. Functional Imaging of Proteolysis: Stromal and Inflammatory Cells Increase Tumor Proteolysis

    Directory of Open Access Journals (Sweden)

    Mansoureh Sameni

    2003-07-01

    Full Text Available The underlying basement membrane is degraded during progression of breast and colon carcinoma. Thus, we imaged degradation of a quenched fluorescent derivative of basement membrane type IV collagen (DQ-collagen IV by living human breast and colon tumor spheroids. Proteolysis of DQ-collagen IV by HCT 116 and HKh-2 human colon tumor spheroids was both intracellular and pericellular. In contrast, proteolysis of DQ-collagen IV by BT20 human breast tumor spheroids was pericellular. As stromal elements can contribute to proteolytic activities associated with tumors, we also examined degradation of DQ-collagen IV by human monocytes/macrophages and colon and breast fibroblasts. Fibroblasts themselves exhibited a modest amount of pericellular degradation. Degradation was increased 4–17-fold in cocultures of fibroblasts and tumor cells as compared to either cell type alone. Inhibitors of matrix metalloproteinases, plasmin, and the cysteine protease, cathepsin B, all reduced degradation in the cocultures. Monocytes did not degrade DQ-collagen IV; however, macrophages degraded DQ-collagen IV intracellularly. In coculture of tumor cells, fibroblasts, and macrophages, degradation of DQ-collagen IV was further increased. Imaging of living tumor and stromal cells has, thus, allowed us to establish that tumor proteolysis occurs pericellularly and intracellularly and that tumor, stromal, and inflammatory cells all contribute to degradative processes.

  1. An affinity-directed protein missile system for targeted proteolysis

    Science.gov (United States)

    Fulcher, Luke J.; Macartney, Thomas; Bozatzi, Polyxeni; Hornberger, Annika; Rojas-Fernandez, Alejandro

    2016-01-01

    The von Hippel–Lindau (VHL) protein serves to recruit the hypoxia-inducible factor alpha (HIF1α) protein under normoxia to the CUL2 E3 ubiquitin ligase for its ubiquitylation and degradation through the proteasome. In this report, we modify VHL to engineer an affinity-directed protein missile (AdPROM) system to direct specific endogenous target proteins for proteolysis in mammalian cells. The proteolytic AdPROM construct harbours a cameloid anti-green fluorescence protein (aGFP) nanobody that is fused to VHL for either constitutive or tetracycline-inducible expression. For target proteins, we exploit CRISPR/Cas9 to rapidly generate human kidney HEK293 and U2OS osteosarcoma homozygous knock-in cells harbouring GFP tags at the VPS34 (vacuolar protein sorting 34) and protein associated with SMAD1 (PAWS1, aka FAM83G) loci, respectively. Using these cells, we demonstrate that the expression of the VHL-aGFP AdPROM system results in near-complete degradation of the endogenous GFP-VPS34 and PAWS1-GFP proteins through the proteasome. Additionally, we show that Tet-inducible destruction of GFP-VPS34 results in the degradation of its associated partner, UVRAG, and reduction in levels of cellular phosphatidylinositol 3-phosphate. PMID:27784791

  2. TOPICAL REVIEW: Formation and behaviour of nano/micro-particles in low pressure plasmas

    Science.gov (United States)

    Watanabe, Y.

    2006-10-01

    Systematic studies on formation and behaviour of particles in low-pressure plasmas have been carried out in silane capacitive high-frequency-discharges developing various in situ particle growth observation methods in the range of their size above sub-nanometres. Studies on charging characteristics of the particles and forces acting on them in the plasmas have greatly contributed to progress in particle growth. All the time evolutions of particle size and density observed until now have a common feature that the particles grow to large ones of micrometres in size through three phases: the initial growth phase up to a nanometre size, the rapid growth phase and the growth saturation phase. The growth in the rapid growth and growth saturation phases can be explained fairly well by the model of coagulation between the negatively charged particles and the positively charged ones of nanometre size. While some issues are still left to be solved, the growth processes in the initial growth phase can be understood by taking into account the relationship between the gas residence time and the growth time for the particles to grow up to nanometre size.

  3. Proteolysis of prato type cheese produced using ultrafiltration

    OpenAIRE

    Spadoti Leila Maria; Dornellas José Raimundo Ferreira; Roig Salvador Massaguer

    2005-01-01

    The application of milk ultrafiltration technology for cheese manufacture presents several advantages. However, it also influences proteolysis and, consequently, cheese ripening. The effects of five different processing methods for Prato cheese were evaluated with respect to the time evolution of the extent and depth of proteolysis indexes (EPI and DPI). The following treatments (T) for cheese production were studied: T1 - without ultrafiltration (standard); T2, T3, T4 and T5 - using milk con...

  4. Protein dynamics and proteolysis in plant vacuoles.

    Science.gov (United States)

    Müntz, Klaus

    2007-01-01

    Plant cells cannot live without their vacuoles. The tissues and organs of a plant contain a wide variety of differentiated and specialized vacuoles -- even a single plant cell can possess two or more types of vacuoles. Vacuolar proteins are encoded by nuclear genes and synthesized in the cytoplasm. Their transport into the vacuolar compartment is under cytoplasmic control. Transcription seems to be a major control level for differential protein supply to the vacuoles. It is at this level that vacuole differentiation and functions are mainly integrated into cellular processes. Recycling amino acids generated by protein degradation is a major function of the vacuole. This is most evident when storage proteins are mobilized in storage tissues of generative or vegetative organs in order to nourish the embryo of germinating seeds or sprouting buds. When specific proteins are transferred to the vacuole for immediate degradation this compartment contributes to the adaptation of protein complexes in response to changes in developmental or environmental conditions. Vacuolar proteases are involved in protein degradation during reversible senescence and programmed cell death, which is also called irreversible senescence. Vacuoles contribute to defence against pathogens and herbivores by limited and unlimited proteolysis. Our present knowledge on functions and processes of vacuolar protein dynamics in plants is reviewed. Research perspectives are deduced.

  5. Surgical Space Conditions During Low-Pressure Laparoscopic Cholecystectomy with Deep Versus Moderate Neuromuscular Blockade

    DEFF Research Database (Denmark)

    Staehr-Rye, Anne K; Rasmussen, Lars S.; Rosenberg, Jacob;

    2014-01-01

    described, but deep neuromuscular blockade may be beneficial. We investigated if deep muscle relaxation would be associated with a higher proportion of procedures with "optimal" surgical space conditions compared with moderate relaxation during low-pressure (8 mm Hg) laparoscopic cholecystectomy. METHODS...... with surgical space conditions that were marginally better than with moderate muscle relaxation during low-pressure laparoscopic cholecystectomy....

  6. Internal ballistics of recoilless high-low pressure guns using hepta-tubular powders

    Directory of Open Access Journals (Sweden)

    M. C. Gupta

    1960-04-01

    Full Text Available In this paper, the theory of recoilless high-low pressure guns has been discussed by taking the form function and the results have been applied to the case of hepta-tubular powders. The results for high-low pressure guns follow as a particular case.

  7. 49 CFR 192.623 - Maximum and minimum allowable operating pressure; Low-pressure distribution systems.

    Science.gov (United States)

    2010-10-01

    ... distribution systems. (a) No person may operate a low-pressure distribution system at a pressure high enough to...) No person may operate a low pressure distribution system at a pressure lower than the minimum... 49 Transportation 3 2010-10-01 2010-10-01 false Maximum and minimum allowable operating...

  8. Seed disinfection effect of atmospheric pressure plasma and low pressure plasma on Rhizoctonia solani.

    Science.gov (United States)

    Nishioka, Terumi; Takai, Yuichiro; Kawaradani, Mitsuo; Okada, Kiyotsugu; Tanimoto, Hideo; Misawa, Tatsuya; Kusakari, Shinichi

    2014-01-01

    Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them.

  9. Development of Experiment Chambers of Complex Low-pressure Environment%低压复合环境试验舱群研制

    Institute of Scientific and Technical Information of China (English)

    殷东辰; 肖华军; 臧斌; 文湘阳; 任兆生; 顾昭; 石立勇; 王桂友

    2011-01-01

    Objective To develop a set of experiment chambers of complex low-pressure environment, in which the conditions of high altitude & low pressure, low pressure & low temperature, low pressure & high temperature, rapid decompression can be simulated. Methods With the multi-chamber structure and four high-power vacuum pumps applied, the air flow was controlled by the electromagnetic valves over the pipeline. The flow of fresh air into the chambers and the drawing out of the vacuum achieved dynamic balance by the control software. The system for communication, oxygen supply, physiological monitoring and environment detection was equipped. ReeultB The simulated altitude was up to 40000m, with the rapid decompression time being 0.01s. In the meantime, the chambers were of the function of simulating the complex circumstances of high altitude & low pressure, low pressure & low temperature, low pressure & high temperature, rapid decompression. The function met the design requirements and reached the national leading research level. Conclusion The set of experiment chambers can decrease the load of operation by preprogrammed automatic control without adding persons. The simulation of high altitude & low pressure circumstance is improved, and the requirements for the simulation of the conditions of high altitude & low pressure, low pressure & low temperature, low pressure & high temperature, rapid decompression are satisfied.[Chinese Medical Equipment Journal,2011,32(12) :6-8,12]%目的:研制一组具备高空低气压环境、低压低温复合环境、低压高温复合环境及迅速减压功能的低压复合环境试验舱群,满足航空装备试验鉴定、航空医学科研训练工作要求.方法:采用多舱室结构分别实现高空低压环境、高空低压低温环境、高空低压高温环境和迅速减压功能,使用4套大功率真空泵实现抽真空功能,全管路电磁控制阀门控制抽真空流量,通过程序控制入舱新风量和抽真空流

  10. Ignition and combustion of pyrotechnics at low pressures and at temperature extremes

    Directory of Open Access Journals (Sweden)

    Clive Woodley

    2017-06-01

    Full Text Available Rapid and effective ignition of pyrotechnic countermeasure decoy flares is vitally important to the safety of expensive military platforms such as aircraft. QinetiQ is conducting experimental and theoretical research into pyrotechnic countermeasure decoy flares. A key part of this work is the development and application of improved models to increase the understanding of the ignition processes occurring for these flares. These models have been implemented in a two-dimensional computational model and details are described in this paper. Previous work has conducted experiments and validated the computational model at ambient temperature and pressure. More recently the computational model has been validated at pressures down to that equivalent to 40,000 feet but at ambient temperature (∼290 K. This paper describes further experimental work in which the ignition delays of the priming material in inert countermeasure decoy flares were determined for pressures down to 40,000 feet and at temperature extremes of −40 °C and 100 °C. Also included in this paper is a comparison of the measured and predicted ignition delays at low pressures and temperature extremes. The agreement between the predicted and measured ignition delays is acceptable.

  11. Simulations of dissociation constants in low pressure supercritical water

    Science.gov (United States)

    Halstead, S. J.; An, P.; Zhang, S.

    2014-09-01

    This article reports molecular dynamics simulations of the dissociation of hydrochloric acid and sodium hydroxide in water from ambient to supercritical temperatures at a fixed pressure of 250 atm. Corrosion of reaction vessels is known to be a serious problem of supercritical water, and acid/base dissociation can be a significant contributing factor to this. The SPC/e model was used in conjunction with solute models determined from density functional calculations and OPLSAA Lennard-Jones parameters. Radial distribution functions were calculated, and these show a significant increase in solute-solvent ordering upon forming the product ions at all temperatures. For both dissociations, rapidly decreasing entropy of reaction was found to be the controlling thermodynamic factor, and this is thought to arise due to the ions produced from dissociation maintaining a relatively high density and ordered solvation shell compared to the reactants. The change in entropy of reaction reaches a minimum at the critical temperature. The values of pKa and pKb were calculated and both increased with temperature, in qualitative agreement with other work, until a maximum value at 748 K, after which there was a slight decrease.

  12. Self-consistent Kinetic Description of the Low-Pressure Solenoidal Inductively Coupled Argon Discharge

    Institute of Scientific and Technical Information of China (English)

    毛明; 王友年

    2005-01-01

    Using an one-dimensional slab model, we have studied the electron energy distribution, the anomalous skin effect, and power absorption in the solenoidal-inductively-coupled argon discharge under low pressures (≤1.33 Pa). The electron energy distribution function and rf electromagnetic field in the plasma are determined self-consistently by the linearized Bolztmann equation incorporating with the Maxwell equations. The numerical results show that, at low pressures, the electron energy distribution function exhibits a non-Maxwellian distribution with a long high-energy tail. The anomalous skin effect is greatly enhanced under low pressures and the negative power absorption is also obtained.

  13. Suppression of interleukin-33 bioactivity through proteolysis by apoptotic caspases.

    Science.gov (United States)

    Lüthi, Alexander U; Cullen, Sean P; McNeela, Edel A; Duriez, Patrick J; Afonina, Inna S; Sheridan, Clare; Brumatti, Gabriela; Taylor, Rebecca C; Kersse, Kristof; Vandenabeele, Peter; Lavelle, Ed C; Martin, Seamus J

    2009-07-17

    Interleukin-33 (IL-33) is a member of the IL-1 family and is involved in polarization of T cells toward a T helper 2 (Th2) cell phenotype. IL-33 is thought to be activated via caspase-1-dependent proteolysis, similar to the proinflammatory cytokines IL-1 beta and IL-18, but this remains unproven. Here we showed that IL-33 was processed by caspases activated during apoptosis (caspase-3 and -7) but was not a physiological substrate for caspases associated with inflammation (caspase-1, -4, and -5). Furthermore, caspase-dependent processing of IL-33 was not required for ST2 receptor binding or ST2-dependent activation of the NF-kappaB transcription factor. Indeed, caspase-dependent proteolysis of IL-33 dramatically attenuated IL-33 bioactivity in vitro and in vivo. These data suggest that IL-33 does not require proteolysis for activation, but rather, that IL-33 bioactivity is diminished through caspase-dependent proteolysis within apoptotic cells. Thus, caspase-mediated proteolysis acts as a switch to dampen the proinflammatory properties of IL-33.

  14. Low pressure corium dispersion experiments in the DISCO test facility with cold simulant fluids

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, L.; Gargallo, M.; Kirstahler, M.; Schwall, M.; Wachter, E.; Woerner, G.

    2006-08-15

    In a severe accident special pressure relief valves in the primary circuit of German Pressurized Water Reactors (PWR) will transfer a high pressure accident into a low pressure scenario. However, there may be a time window during late in-vessel reflooding scenarios where the pressure is in the order of 1 or 2 MPa at the moment of the reactor vessel rupture. A failure in the bottom head of the reactor pressure vessel, followed by melt expulsion and blowdown of the reactor cooling system, might disperse molten core debris out of the reactor pit, even at such low pressures. The mechanisms of efficient debris-to-gas heat transfer, exothermic metal/oxygen reactions, and hydrogen combustion may cause a rapid increase in pressure and temperature in the reactor containment. Integral experiments are necessary to furnish data for modeling these processes in computer codes, that will be used to apply these result to the reactor case. The acquired knowledge can lead to realize additional safety margins for existing or future plants. The test facility DISCO-C (DIspersion of Simulant COrium - Cold) models the annular reactor cavity and the subcompartments of a large European reactor in a scale 1:18. The fluid dynamics of the dispersion process was studied using model fluids, water or bismuth alloy instead of corium, and nitrogen or helium instead of steam. The effects of different breach sizes and locations, and different failure pressures on the dispersion were studied, specifically by testing central holes, lateral holes, horizontal rips, and complete ripping of the bottom head. 22 experiments were performed in a basic cavity geometry with holes at the bottom of the lower head to study the similarity relations. Variables were the hole diameter, the initial pressure in the RPV and the fluids used. The only flow path out of the reactor pit was the annular gap between the inner wall of the reactor pit and the RPV, and then along the main coolant lines into the subcompartments

  15. Proteolysis of Livanjski cheese during ripening

    Directory of Open Access Journals (Sweden)

    Samir KALIT

    2016-12-01

    Full Text Available Livanjski cheese belongs to the group of hard cheeses which is traditionally produced in Livno (Bosnia and Herzegovina. Proteolytic changes during the ripening of Livanjski cheese have not been investigated extensively. The aim of this paper was to determine its proteolytic changes during the different stages of ripening. Five Livanjski cheeses (from raw cow’s or a mixture of sheep’s and cow’s milk were observed during the ripening to evaluate its typical proteolytic profile. An electophoretic profile of Livanjski cheese was determined by Urea-polyacrylamide gel electrophoresis (urea-PAGE and a densitometric evaluation of the urea-PAGE gels was performed using a densitometer. The water-soluble nitrogen fraction in the total nitrogen (WSN %TN and the 12%-TCA-soluble nitrogen fraction in the total nitrogen (TCA-SN %TN of the cheese were determined using the Kjeldahl method. Degradation of αs1-casein by chymosin caused a significant decrease (P < 0.05 of relative content of this protein in Livanjski cheese at the sixth week point of ripening. Due to the activity of chymosin on αs1-casein, αs1-I-casein and αs1-II-casein developed, which caused a significant increase (P < 0.05 of Index alpha. The relative ratio of β-casein significantly decreased (P < 0.05 during ripening leading to a significant accumulation (P < 0.05 of degraded product (sum γ1-casein, γ2-casein and γ3-casein. These proteolytic changes caused a significant increase (P < 0.05 of Index betta. Accumulation of medium, small peptides and amino acids caused a significant (P < 0.05 increase of the relative content of WSN %TN and TCA-SN %TN. In general, proteolysis of Livanjski cheese during ripening was moderate probably due to the low moisture content and low water activity, although it was produced from raw milk. Taking into account that the ratio β-casein : αs1-casein at the end of ripening was 1.46, it could be concluded that degradation of αs1-casein could be the

  16. Performance of the low pressure MWPCs for fission fragments under a high background%Performance of the low pressure MWPCs for fission fragments under a high background

    Institute of Scientific and Technical Information of China (English)

    宋玉收; Margaryan A.; 胡碧涛; 唐力光

    2011-01-01

    Two couples of low pressure multi-wire proportional chambers (MWPC) were located in the target chamber to detect fission fragments in a hypernuclei producing experiment at Thomas Jefferson National Laboratory (Jlab). In the experiment, a continuous wave (

  17. Isolated calcification of tricuspid valve with severe low pressure tricuspid regurgitation in an infant

    OpenAIRE

    Mittal, S.R.

    2013-01-01

    A three-month-old asymptomatic male infant was evaluated for a systolic murmur. Echocardiography revealed calcification of tricuspid leaflets with severe low pressure tricuspid regurgitation. Pulmonary artery flow was normal. There was no other congenital anomaly.

  18. Isolated calcification of tricuspid valve with severe low pressure tricuspid regurgitation in an infant.

    Science.gov (United States)

    Mittal, S R

    2013-12-01

    A three-month-old asymptomatic male infant was evaluated for a systolic murmur. Echocardiography revealed calcification of tricuspid leaflets with severe low pressure tricuspid regurgitation. Pulmonary artery flow was normal. There was no other congenital anomaly.

  19. Proteolysis of prato type cheese produced using ultrafiltration

    Directory of Open Access Journals (Sweden)

    Spadoti Leila Maria

    2005-01-01

    Full Text Available The application of milk ultrafiltration technology for cheese manufacture presents several advantages. However, it also influences proteolysis and, consequently, cheese ripening. The effects of five different processing methods for Prato cheese were evaluated with respect to the time evolution of the extent and depth of proteolysis indexes (EPI and DPI. The following treatments (T for cheese production were studied: T1 - without ultrafiltration (standard; T2, T3, T4 and T5 - using milk concentrated by ultrafiltration (UFCM and respectively: T2 - without pre-fermentation of the UFCM; T3 - pre-fermentation of 10% of the UFCM; T4 - pre-fermentation of 20% of the UFCM, and T5 - pre-fermentation of 20% of the UFCM plus indirect heating. Treatments affected the EPI and DPI of the cheeses (T1 lower values for EPI and DPI and T4 higher values for EPI and DPI. The time influenced the extent and depth of proteolysis indexes.

  20. Stochastic Theory of Dust-Grain Charging in Low-Pressure Plasmas

    CERN Document Server

    Abolmasov, S N; Cabarrocas, P Roca i

    2013-01-01

    Charging of dust grains in low-pressure plasmas is reviewed critically. A theory based on the Fokker-Planck equation and orbital motion limited approximation is proposed. The theory predicts that dust grains can acquire a positive charge in low-pressure electropositive plasmas having a sufficiently high plasma potential, in agreement with experimental observations. It is also shown that variations in the plasma potential (electron temperature) can lead to spatial regions in which grains have opposite charges.

  1. Spectroscopic Investigation of Indium Halides as Substitutes of Mercury in Low Pressure Discharges for Lighting Applications

    OpenAIRE

    Briefi, Stefan

    2012-01-01

    Low pressure discharges with indium halides as radiator are discussed as substitutes for hazardous mercury in conventional fluorescent lamps. In this work, the applicability of InBr and InCl in a low pressure discharge light source is investigated. The aim is to identify and understand the physical processes which determine the discharge characteristics and the efficiency of the generated near-UV emission of the indium halide molecule and of the indium atom which is created due to dissociatio...

  2. Simultaneous removal of phosphorus and EfOM using MIEX, coagulation, and low-pressure membrane filtration.

    Science.gov (United States)

    Kim, Hyun-Chul; Timmes, Thomas C; Dempsey, Brian A

    2015-01-01

    The feasibility of using magnetic ion exchange (MIEX) treatment, in-line alum coagulation, and low-pressure membrane filtration was investigated for the simultaneous removal of total phosphorus (TP) and effluent organic matter (EfOM) from biologically treated wastewater. The focus was also placed on minimizing fouling of polyvinylidene fluoride and polyethersulfone membranes, which are the most commonly used low-pressure membranes in new and retrofit wastewater treatment plants. MIEX alone was effective for the removal of EfOM, and MIEX plus a small alum dose was very effective in removing both EfOM and TP. MIEX removed phosphorus, but organic acids in EfOM were preferentially removed, and the effects of competing anions on the removal of EfOM were insignificant. All the pretreatment strategies decreased the resistance to filtration. The greatest decrease in fouling was achieved by using MIEX (15 mL L⁻¹) plus a very low dose of alum (∼0.5 mg Al L⁻¹). Sweep floc coagulation using alum and without MIEX also significantly decreased fouling but did not effectively remove EfOM and produced high floc volume that could be problematic for inside-out hollow-fibre modules. The addition of these reagents into rapid mix followed by membrane filtration would provide operational simplicity and could be easily retrofitted at existing membrane filtration facilities.

  3. Structural organization of mammalian prions as probed by limited proteolysis

    Science.gov (United States)

    The GPI- transgenic mouse model was used to study the structure of GPI- prions. We obtained valuable information about the structure of prions by performing limited proteolysis of the GPI- prions and analyzing the results by mass spectrometry and Western blot. This information coupled with previous ...

  4. Effects of reduction and proteolysis on cashew allergens

    Science.gov (United States)

    Allergic reaction to cashew ingestion is frequently more severe than reaction to peanut ingestion, and food allergens are commonly resistant to digestive proteases. The purpose of this study was to characterize the sensitivity of cashew proteins to proteolysis. Cashew protein extracts and purified c...

  5. Biofilm recruitment of Vibrio cholerae by matrix proteolysis.

    Science.gov (United States)

    Duperthuy, Marylise; Uhlin, Bernt Eric; Wai, Sun Nyunt

    2015-11-01

    The appearance of bacterial biofilms involves secretion of polysaccharides and proteins that form an extracellular matrix embedding the bacteria. Proteases have also been observed, but their role has remained unclear. Smith and co-workers have now found that proteolysis can contribute to further recruitment of bacteria to Vibrio cholerae biofilms.

  6. Sarcomere Length Influences u-calpain Mediated Proteolysis

    Science.gov (United States)

    Muscle shortening and postmortem proteolysis both influence beef tenderness, but their interacting effects on tenderness are relatively unknown. Inherent myofibril structure and the extent of overlap between myosin and actin filaments are hypothesized to affect the availability of substrates for deg...

  7. Amelogenin "nanorods" formation during proteolysis by Mmp-20.

    Science.gov (United States)

    Yang, Xiudong; Sun, Zhi; Ma, Ruiwen; Fan, Daming; Moradian-Oldak, Janet

    2011-11-01

    Amelogenin is cleaved by enamelysin (Mmp-20) soon after its secretion, and the cleavage products accumulate in specific locations during enamel formation, suggesting that parent amelogenin proteolysis is necessary for activating its functions. To investigate the precise roles of Mmp-20 and its influence on the assembly of amelogenin, an in vitro enzymatic digestion process mimicking the initial stages of amelogenin proteolysis was investigated at near-physiological conditions using recombinant porcine amelogenin (rP172) and enamelysin. Hierarchically organized nanorod structures formed during different digestion stages were detected by TEM. At the earliest stage, uniformly dispersed parent amelogenin spherical particles, mixed with some darker stained smaller spheres, and accompanying elongated chain-like nanostructures were observed. Cylindrical nanorods, which appeared to be the result of tight assembly of thin subunit cylindrical discs with thicknesses ranging from ∼2.5 to ∼6.0nm, were formed after an hour of proteolysis. These subunit building blocks stacked to form nanorods with maximum length of ∼100nm. With the production of more cleavage products, additional morphologies spontaneously evolved from the cylindrical nanorods. Larger ball-like aggregates ultimately formed at the end of proteolysis. The uniform spherical particles, nanorods, morphological patterns evolved from nanorods, and globular aggregated microstructures were successively formed by means of co-assembly of amelogenin and its cleavage products during a comparatively slow proteolysis process. We propose that, following the C-terminal cleavage of amelogenin, co-assembly with its fragments leads to formation of nanorod structures whose properties eventually dictate the super-structural organization of enamel matrix, controlling the elongated growth of enamel apatite crystals.

  8. Low Pressure Tolerance by Methanogens in an Aqueous Environment: Implications for Subsurface Life on Mars

    Science.gov (United States)

    Mickol, R. L.; Kral, T. A.

    2016-09-01

    The low pressure at the surface of Mars (average: 6 mbar) is one potentially biocidal factor that any extant life on the planet would need to endure. Near subsurface life, while shielded from ultraviolet radiation, would also be exposed to this low pressure environment, as the atmospheric gas-phase pressure increases very gradually with depth. Few studies have focused on low pressure as inhibitory to the growth or survival of organisms. However, recent work has uncovered a potential constraint to bacterial growth below 25 mbar. The study reported here tested the survivability of four methanogen species (Methanothermobacter wolfeii, Methanosarcina barkeri, Methanobacterium formicicum, Methanococcus maripaludis) under low pressure conditions approaching average martian surface pressure (6 mbar - 143 mbar) in an aqueous environment. Each of the four species survived exposure of varying length (3 days - 21 days) at pressures down to 6 mbar. This research is an important stepping-stone to determining if methanogens can actively metabolize/grow under these low pressures. Additionally, the recently discovered recurring slope lineae suggest that liquid water columns may connect the surface to deeper levels in the subsurface. If that is the case, any organism being transported in the water column would encounter the changing pressures during the transport.

  9. Growth and mitochondrial respiration of mungbeans (Phaseolus aureus Roxb.) germinated at low pressure

    Science.gov (United States)

    Musgrave, M. E.; Gerth, W. A.; Scheld, H. W.; Strain, B. R.

    1988-01-01

    Mungbean (Phaseolus aureus Roxb.) seedlings were grown hypobarically to assess the effects of low pressure (21-24 kilopascals) on growth and mitochondrial respiration. Control seedlings grown at ambient pressure (101 kilopascals) were provided amounts of O2 equivalent to those provided experimental seedlings at reduced pressure to factor out responses to O2 concentration and to total pressure. Respiration was assayed using washed mitochondria, and was found to respond only to O2 concentration. Regardless of total pressure, seedlings grown at 2 millimoles O2 per liter had higher state 3 respiration rates and decreased percentages of alternative respiration compared to ambient (8.4 millimoles O2 per liter) controls. In contrast, seedling growth responded to total pressure but not to O2 concentration. Seedlings were significantly larger when grown under low pressure. While low O2 (2 millimoles O2 per liter) diminished growth at ambient pressure, growth at low pressure in the same oxygen concentration was enhanced. Respiratory development and growth of mungbean seedlings under low pressure is unimpaired whether oxygen or air is used as the chamber gas, and further, low pressure can improve growth under conditions of poor aeration.

  10. Monitoring of low pressure plasma systems; Ueberwachung von Niederdruck-Plasmaanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Michaeli, W.; Hegenbart, A.; Binkowski, D.; Fragstein, F. v. [Inst. fuer Kunststoffverarbeitung (IKV) an der RWTH Aachen (Germany)

    2007-02-15

    The optical emission spectroscopy (OES) is a very flexible and easy to use method to monitor industrial plasma processes. By directly monitoring the plasma itself many additional factors influencing low pressure plasma processes can be observed. First of all factors that can not be controlled directly play an important role in this context. Examples are contaminations and leaks in the plasma system. These can negatively influence the reproducibility of production processes. In this paper the effect of a leak on the coating and the plasma process is being shown. Additionally the detection of contaminations and sealing problems in a microwave plasma source is being demonstrated. By using the correlations being presented the OES can be used to continually monitor low pressure plasma systems and thus enhance reproducibility of industrial low pressure plasma processes. (orig.)

  11. Bulk characterization of pharmaceutical powders by low-pressure compression II

    DEFF Research Database (Denmark)

    Hagsten Sørensen, A.; Sonnergaard, Jørn; Hovgaard, L.

    2006-01-01

    The aim of the present study was to investigate the effect of punch and die diameter, sample size, compression speed, and particle size on two low-pressure compression-derived parameters; the compressed density and the Walker w parameter. The excellent repeatability of the low-pressure compression...... method allowed small effects of variations in punch and die diameter and sample size to be demonstrated on a high significance level. Changing the compression speed, however, did not cause a significant effect in the compressed density, whereas a decrease in w was seen. The effect of particle size...... was studied by compressing and tapping different grades of calcium carbonate, lactose, and microcrystalline cellulose. The low-pressure compression-derived parameters were compared to tapped densities and to Compressibility Indexes obtained by tapping volumetry. Even though the relationship between particle...

  12. Treatment of refractory low-pressure hydrocephalus with an active pumping negative-pressure shunt system.

    Science.gov (United States)

    Kalani, M Yashar S; Turner, Jay D; Nakaji, Peter

    2013-03-01

    Low-pressure hydrocephalus is a rare type of hydrocephalus characterized by negative intracranial pressure (ICP) and ventriculomegaly. Given the shortcomings of available methods to treat refractory low-pressure hydrocephalus, we set out to develop a new system for evacuation of cerebrospinal fluid (CSF) from the ventricular system where existing shunt systems do not produce the necessary gradient for CSF drainage. We retrospectively reviewed the charts of two patients with the diagnosis of negative-pressure hydrocephalus refractory to traditional treatments. We combined a traditional low-pressure, non-siphoning valve with a pumping chamber placed distal to the valve to create a system that could be actively pumped to remove excess CSF. Treatment of negative-pressure hydrocephalus requires the establishment of a lower ventricular drainage pressure than the drainage pressure in the subarachnoid space. In refractory cases, we propose the use of this active negative-pressure pumping system.

  13. Low-pressure airlift fermenter for single cell protein production: II. Continuous culture of Pichia yeast

    Energy Technology Data Exchange (ETDEWEB)

    Chen, N.Y.; Srinivasan, S.; Leavitt, R.I.; Coty, V.F.; Kondis, E.F.

    1987-03-01

    Experiments using Pichia yeast grown on n-paraffins have been conducted in laboratory 10-l airlift fermenters and in a 640-l module of commercial scale. Results confirmed the design concept with low-pressure air. However, in the absence of mass transport constraints, the build up of toxic factors in the fermenter appeared to a major variable limiting cell productivity. Foaming in the large fermenter also presented a serious problem, which must be solved before low-pressure airlift fermenters become practical. 14 references.

  14. Over recovery in low pressure sparkgaps - confirmation of pressure reduction in over recovery

    OpenAIRE

    Nagesh, KV; Ron, PH; Nagabhushana, GR; Nema, RS

    1999-01-01

    The over recovery in sparkgaps [1], [2] operating along the left-hand side of Paschens characteristics is due to pressure reduction in the gap after the first pulse discharge. This pressure reduction leading to over recovery in low pressure sparkgaps has been verified using a low pressure sparkgap with two sparkgaps placed one above the other in the same chamber. The breakdown voltage strength characteristics of the second gap has been determined for gap spacings of 3.5 mm to 10 mm, diffusion...

  15. Germination of white radish, buckwheat and qing-geng-cai under low pressure in closed environment.

    Science.gov (United States)

    Hinokuchi, Tsutomu; Oshima, Satoshi; Hashimoto, Hirofumi

    2004-11-01

    In order to cultivate plants under low pressure in closed environment, the germination rate of seeds of white radish was investigated under low pressure, low oxygen partial pressure and condition of pure oxygen. The result of these experiments showed that the germination rate was affected by the oxygen partial pressure. From this fact, it is possible to lower the total pressure by using only the pure oxygen in germination. Furthermore, the germination rates of seeds of buckwheat and qing-geng-cai were also investigated in pure oxygen for the comparison. Consequently, though tendency in germination rate of white radish was similar to qing-geng-cai, it was different from buckwheat.

  16. On the mechanism of low-pressure imprint lithography: capillarity vs viscous flow.

    Science.gov (United States)

    Khang, Dahl-Young; Lee, Hong H

    2008-05-20

    Dominant mechanisms in low-pressure imprint lithography processes have been identified for the regimes that are definable in terms of applied pressure, temperature, and mold material characteristics. Capillarity is found to be the dominant mechanism at high temperature and low pressure when stiff, hard molds are used. In the case of flexible thin-film ( approximately 20 microm) molds, both the capillarity and the viscous flow are involved. Both mechanisms are operative in the initial stage of the imprinting, but the capillarity takes over as time progresses.

  17. The beauty of frost: nano-sulfur assembly via low pressure vapour deposition.

    Science.gov (United States)

    Wang, Yu; Chen, Lu; Scudiero, Louis; Zhong, Wei-Hong

    2015-11-14

    A low pressure vapour deposition (LPVD) technique is proposed as an environmentally friendly, cost-effective and versatile strategy for fabrication of sulfur nanomaterials. By controlling the characteristics of the deposit substrate for the LPVD, various sulfur-based nanomaterials have been obtained through a substrate-induced self-assembly process.

  18. Numerical Study of Active Flow Control for a Transitional Highly-Loaded Low-Pressure Turbine

    Science.gov (United States)

    2008-02-01

    Count Using Vortex Generator Jet Separation Control,” ASME Paper GT-2002-30602, Jun. 2002. [16] Eulitz, F. and Engel , K., “Numerical Investigation of...Around a Low Pressure Turbine Blade,” Direct and Large-Eddy Simulation IV, ERCOFTAC Series Vol. 8 , edited by B. J. Guerts, R. Friedrich , and O

  19. Low-pressure pulmonary artery aneurysm presenting with pulmonary embolism: a case series

    Directory of Open Access Journals (Sweden)

    Papoulidis Pavlos

    2011-04-01

    Full Text Available Abstract Introduction Pulmonary artery aneurysm is an uncommon disorder with severe complications. The diagnosis is often difficult, since the clinical manifestations are non-specific and the treatment is controversial, as the natural history of the disease is not completely understood. Case presentation We describe the cases of two patients with pulmonary artery aneurysms. The first patient was a 68-year-old Caucasian man with an idiopathic low-pressure pulmonary artery aneurysm together with a pulmonary embolism. The patient preferred a conservative approach and was stable at the 10-month follow-up visit after being placed on anti-coagulant treatment. The second patient was a 66-year-old Caucasian woman with a low-pressure pulmonary artery aneurysm also presented together with a pulmonary embolism. The aneurysm was secondary to pulmonary valve stenosis. She received anti-coagulants and, after stabilization, underwent percutaneous balloon valvuloplasty. Conclusion Pulmonary embolism may be the initial presentation of a low-pressure pulmonary artery aneurysm. No underlying cause for pulmonary embolism was found in either of our patients, suggesting a causal association with low-pressure pulmonary artery aneurysm.

  20. Gray water recycle: Effect of pretreatment technologies on low pressure reverse osmosis treatment

    Science.gov (United States)

    Gray water can be a valuable source of water when properly treated to reduce the risks associated with chemical and microbial contamination to acceptable levels for the intended reuse application. In this study, the treatment of gray water using low pressure reverse osmosis (RO) filtration after pre...

  1. An Engine Research Program Focused on Low Pressure Turbine Aerodynamic Performance

    Science.gov (United States)

    Castner, Raymond; Wyzykowski, John; Chiapetta, Santo; Adamczyk, John

    2002-01-01

    A comprehensive test program was performed in the Propulsion Systems Laboratory at the NASA Glenn Research Center, Cleveland Ohio using a highly instrumented Pratt and Whitney Canada PW 545 turbofan engine. A key objective of this program was the development of a high-altitude database on small, high-bypass ratio engine performance and operability. In particular, the program documents the impact of altitude (Reynolds Number) on the aero-performance of the low-pressure turbine (fan turbine). A second objective was to assess the ability of a state-of-the-art CFD code to predict the effect of Reynolds number on the efficiency of the low-pressure turbine. CFD simulation performed prior and after the engine tests will be presented and discussed. Key findings are the ability of a state-of-the art CFD code to accurately predict the impact of Reynolds Number on the efficiency and flow capacity of the low-pressure turbine. In addition the CFD simulations showed the turbulent intensity exiting the low-pressure turbine to be high (9%). The level is consistent with measurements taken within an engine.

  2. Low-pressure pneumoperitoneum during laparoscopic donor nephrectomy to optimize live donors' comfort

    NARCIS (Netherlands)

    Warle, M.C.; Berkers, A.W.; Langenhuijsen, J.F.; Jagt, M.F.P. van der; Dooper, P.M.M.; Kloke, H.J.; Pilzecker, D.; Renes, S.H.; Wever, K.E.; Hoitsma, A.J.; Vliet, J.A. van der; D'Ancona, F.C.H.

    2013-01-01

    Nowadays, laparoscopic donor nephrectomy (LDN) has become the gold standard to procure live donor kidneys. As the relationship between donor and recipient loosens, it becomes of even greater importance to optimize safety and comfort of the surgical procedure. Low-pressure pneumoperitoneum has been s

  3. ASSESSING THE EFFECTIVENESS OF LOW PRESSURE ULTRAVIOLET LIGHT FOR INACTIVATING HELICOBACTER PYLORI

    Science.gov (United States)

    Three strains of Helicobacter pylori were exposed to ultraviolet (UV) light from a low-pressure source to determine log inactivation versus applied fluence. Results indicate that H. pylori is readily inactivated at UV fluences typically used in water treatment r...

  4. ASSESSING THE EFFECTIVENESS OF LOW PRESSURE ULTRAVIOLET LIGHT FOR INACTIVATING HELICOBACTER PYLORI

    Science.gov (United States)

    Three strains of Helicobacter pylori were exposed to ultraviolet (UV) light from a low-pressure source to determine log inactivation versus applied fluence. Results indicate that H. pylori is readily inactivated at UV fluences typically used in water treatment r...

  5. Heat transport in cold-wall single-wafer low pressure chemical-vapor-deposition reactors

    NARCIS (Netherlands)

    Hasper, A.; Schmitz, J.E.J.; Holleman, J.; Verweij, J.F.

    1992-01-01

    A model is formulated to understand and predict wafer temperatures in a tungsten low pressure chemical‐vapor‐deposition (LPCVD) single‐wafer cold‐wall reactor equipped with hot plate heating. The temperature control is usually carried out on the hot plate temperature. Large differences can occur

  6. Using the EMD method to determine fault criterion for medium-low pressure gas regulators

    Science.gov (United States)

    Hao, Xuejun; Liu, Qiang; Yang, Guobin; Du, Yi

    2015-11-01

    By extracting the outlet pressure data of gas regulators, this paper uses the EMD toolbox of the MATLAB software, which can perform data decomposition and the Hilbert-Huang Transform to find the rules with fault data. Eventually, the medium-low pressure gas regulator fault criterion can be established.

  7. Numerical approach to a low pressure gas-injection scroll compressor

    OpenAIRE

    Zhou Guang-Hui; Li Hai-Jun; Liu Lei; Zhao Deng-Ke; Wei Pan-Pan; Chen Tong

    2015-01-01

    In order to solve problems arising in ordinary heat pump system for pure electric vehicles at ultra-low temperature, a low pressure gas-injection scroll compressor is designed, and a mathematical model is established. Comparison with the experimental results shows good accuracy of the theoretical prediction.

  8. Optimized surgical space during low-pressure laparoscopy with deep neuromuscular blockade

    DEFF Research Database (Denmark)

    Staehr-Rye, Anne K; Rasmussen, Lars S; Rosenberg, Jacob;

    2013-01-01

    Laparoscopic cholecystectomy (LC) can be performed using low intra-abdominal pressure (space conditions using either deep, continuous muscle relaxation or moderate blockade during low-pressure (8 mm......Hg) LC. We hypothesized that a deep neuromuscular block would be associated with a higher proportion of optimal surgical space conditions....

  9. Highly Loaded Low-Pressure Turbine: Design, Numerical and Experimental Analysis (Preprint)

    Science.gov (United States)

    2010-06-01

    the transition models of Praisner and Clark [19] to determine airfoil performance. Graphical User In- terfaces (GUI) were employed to alter the...Turbomachinery Flows, NASA/CP- 2001-210888, NASA. [5] Hourmouziadis, J., 1984. “Aerodynamic design of low pressure turbines”. In AGARD-LS-167 Blading Desing

  10. Proteolysis in microfluidic droplets: an approach to interface protein separation and peptide mass spectrometry.

    Science.gov (United States)

    Ji, Ji; Nie, Lei; Qiao, Liang; Li, Yixin; Guo, Liping; Liu, Baohong; Yang, Pengyuan; Girault, Hubert H

    2012-08-07

    A versatile microreactor protocol based on microfluidic droplets has been developed for on-line protein digestion. Proteins separated by liquid chromatography are fractionated in water-in-oil droplets and digested in sequence. The microfluidic reactor acts also as an electrospray ionization emitter for mass spectrometry analysis of the peptides produced in the individual droplets. Each droplet is an enzymatic micro-reaction unit with efficient proteolysis due to rapid mixing, enhanced mass transfer and automated handling. This droplet approach eliminates sample loss, cross-contamination, non-specific absorption and memory effect. A protein mixture was successfully identified using the droplet-based micro-reactor as interface between reverse phase liquid chromatography and mass spectrometry.

  11. Use of high-gradient magnetic fishing for reducing proteolysis during fermentation.

    Science.gov (United States)

    Maury, Trine L; Ottow, Kim E; Brask, Jesper; Villadsen, John; Hobley, Timothy J

    2012-07-01

    Proteolysis during fermentation may have a severe impact on the yield and quality of a secreted product. In the current study, we demonstrate the use of high-gradient magnetic fishing (HGMF) as an efficient alternative to the more conventional methods of preventing proteolytic degradation. Bacitracin-linked magnetic affinity adsorbents were employed directly in a fermenter during Bacillus licheniformis cultivation to remove trace amounts of unwanted proteases. The constructed magnetic adsorbents had excellent, highly specific binding characteristics in the fermentation broth (K(d) = 1.94 micromolar; Q(max) = 222.8 mg/g), which obeyed the Langmuir isotherm and had rapid binding kinetics (equilibrium in HGMF, the degradation of the model protein bovine serum albumin was stopped. The adsorbents could be recycled and reused during the same fermentation to remove freshly produced proteases, extending the life of the model protein in the fermenter. HGMF may provide an efficient method of stabilizing heterologous proteins produced in cultivation processes.

  12. Automated mini-column solid-phase extraction cleanup for high-throughput analysis of chemical contaminants in foods by low-pressure gas chromatography – tandem mass spectrometry

    Science.gov (United States)

    This study demonstrated the application of an automated high-throughput mini-cartridge solid-phase extraction (mini-SPE) cleanup for the rapid low-pressure gas chromatography – tandem mass spectrometry (LPGC-MS/MS) analysis of pesticides and environmental contaminants in QuEChERS extracts of foods. ...

  13. H2O temperature sensor for low-pressure flames using tunable diode laser absorption near 2.9 νm

    KAUST Repository

    Li, Sijie

    2011-10-19

    Making use of a newly available rapid-tuning diode laser operating at wavelengths up to 2.9 νm, an absorption-based temperature sensor was developed for in situ measurements in low-pressure flames. Based on the systematic analysis of H2O vapor transitions in the fundamental vibrational bands (ν1 and ν3) of H2O in the range of 2.5-3.0 νm, an optimal closely-spaced spectral line pair near 2.9 νm was selected for its temperature sensitivity in the range of 1000-2500 K. The narrow-linewidth room-temperature laser was scanned repetitively across these spectral features at 5 kHz, enabling fast, accurate temperature sensing. Use of the temperature sensor was investigated in low-pressure flames supported on a McKenna burner at 15, 25 and 60 Torr. To avoid absorption by the cold gases in the flame edges and the recirculation region between the burner and the vacuum chamber wall, a variable-path in situ probe was designed and an optimal path length was determined to accurately measure the flame centerline temperature. Different flame conditions were investigated to illustrate the potential of this sensor system for sensitive measurements of combustion temperature in low-pressure flames. © 2011 IOP Publishing Ltd.

  14. Low-pressure cardiac tamponade masquerading as severe sepsis diagnosed with a bedside ultrasound and as the initial presentation of malignancy.

    Science.gov (United States)

    Conti, Ricardo Augusto Slaibi; Oppenheim, Ian Mandeville

    2014-01-01

    We report a patient with low-pressure cardiac tamponade masquerading as sepsis and as the initial presentation of malignancy. A quick diagnosis was done by the intensivist performing a bedside ultrasound. The diagnosis of low-pressure cardiac tamponade is a challenge because the classic physical signs of cardiac tamponade can be absent. It is made even more challenging when the vital sign changes and physical examination findings mimic severe sepsis. One of the benefits of a bedside ultrasound in the assessment of a patient with an initial diagnosis of severe sepsis or septic shock is the rapid diagnosis of cardiac tamponade if it is present. A 55-year-old male presented to the emergency department with weakness, cough, and syncope. His examination was notable only for dusky mottling of his cheeks, chest, and neck. Specifically, there was no jugular venous distension or pulsus paradoxus. A chest radiograph showed a right upper lobe infiltrate, whereas his electrocardiogram showed only sinus tachycardia. His white blood cell count and lactic acid were elevated. The sepsis protocol was started and a bedside ultrasound revealed signs of cardiac tamponade. The patient immediately improved after a pericardiocentesis. Analysis of the pericardial biopsy revealed adenocarcinoma, later determined to be from a pulmonary primary source. Because low-pressure cardiac tamponade is life-threatening and difficult to diagnose, evaluation of the pericardium with a bedside ultrasound should be considered in patients with syncope, severe sepsis, or shock.

  15. An experimental and kinetic modeling study of premixed nitroethane flames at low pressure

    DEFF Research Database (Denmark)

    Zhang, Kuiwen; Zhang, Lidong; Xie, Mingfeng

    2013-01-01

    An experimental and kinetic modeling study is reported on three premixed nitroethane/oxygen/argon flames at low pressure (4.655kPa) with the equivalence ratios (Φ) of 1.0, 1.5 and 2.0. Over 30 flame species were identified with tunable synchrotron vacuum ultraviolet photoionization mass spectrome......An experimental and kinetic modeling study is reported on three premixed nitroethane/oxygen/argon flames at low pressure (4.655kPa) with the equivalence ratios (Φ) of 1.0, 1.5 and 2.0. Over 30 flame species were identified with tunable synchrotron vacuum ultraviolet photoionization mass...... predictions have shown satisfactory agreement with the experimental results. Basing on the rate-of-production analysis, the reaction pathways that feature the combustion of nitroethane were revealed, including the primary decomposition of C–N bond fission, the oxidation of C2 and C1 hydrocarbons...

  16. A comparison among optical emission spectroscopic methods of determining electron temperature in low pressure argon plasmas

    Institute of Scientific and Technical Information of China (English)

    Niu Tian-Ye; Cao Jin-Xiang; Liu Lei; Liu Jin-Ying; Wang Yan; Wang Liang

    2007-01-01

    In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas of dc glow discharges at low pressures in laboratory by measuring the relative intensities of ArI lines at various pressures. These methods are developed respectively on the basis of the Fermi-Dirac model, corona model, and two kinds of electron collision cross section models according to the kinetic analysis. Their theoretical bases and the conditions to which they are applicable are reviewed, and their calculation results and fitting errors are compared with each other. The investigation has indicated that the electron temperatures obtained by the four methods become consistent with each other when the pressure increases in the low pressure argon plasmas.

  17. Finite Element Modeling and Analysis of Powder Stream in Low Pressure Cold Spray Process

    Science.gov (United States)

    Goyal, Tarun; Walia, Ravinderjit Singh; Sharma, Prince; Sidhu, Tejinder Singh

    2016-07-01

    Low pressure cold gas dynamic spray (LPCGDS) is a coating process that utilize low pressure gas (5-10 bars instead of 25-30 bars) and the radial injection of powder instead of axial injection with the particle range (1-50 μm). In the LPCGDS process, pressurized compressed gas is accelerated to the critical velocity, which depends on length of the divergent section of nozzle, the propellant gas and particle characteristics, and the diameters ratio of the inlet and outer diameters. This paper presents finite element modeling (FEM) of powder stream in supersonic nozzle wherein adiabatic gas flow and expansion of gas occurs in uniform manner and the same is used to evaluate the resultant temperature and velocity contours during coating process. FEM analyses were performed using commercial finite volume package, ANSYS CFD FLUENT. The results are helpful to predict the characteristics of powder stream at the exit of the supersonic nozzle.

  18. Shock tube study of n-decane ignition at low pressures

    Institute of Scientific and Technical Information of China (English)

    Xiao-Fei Nie; Ping Li; Chang-Hua Zhang; Wei Xie; Cong-Shan Li; Xiang-Yuan Li

    2012-01-01

    Ignition delay times for n-decane/O2/Ar mixtures were measured behind reflected shock waves using endwall pressure and CH* emission measurements in a heated shock tube.The initial postshock conditions cover pressures of 0.09-0.26 MPa,temperatures of 1 227-1 536 K,and oxygen mole fractions of 3.9%-20.7% with an equivalence ratio of 1.0.The correlation formula of ignition delay dependence on pressure,temperature,and oxygen mole fraction was obtained.The current data are in good agreement with available low-pressure experimental data,and they are then compared with the prediction of a kinetic mechanism.The current measurements extend the kinetic modeling targets for the n-decane combustion at low pressures.

  19. Kinetic analysis of negative power deposition in inductive low pressure plasmas

    Science.gov (United States)

    Trieschmann, Jan; Mussenbrock, Thomas

    2017-02-01

    Negative power deposition in low pressure inductively coupled plasmas (ICPs) is investigated by means of an analytical model which couples Boltzmann’s equation and the quasi-stationary Maxwell’s equations. Exploiting standard Hilbert space methods an explicit solution for both, the electric field and the distribution function of the electrons for a bounded discharge configuration subject to an unsymmetrical excitation is found for the first time. The model is applied to a low pressure ICP discharge. In this context particularly the anomalous skin effect and the effect of phase mixing is discussed. The analytical solution is compared with results from electromagnetic full wave particle in cell simulations. Excellent agreement between the analytical and the numerical results is found.

  20. Surface energy-tunable iso decyl acrylate based molds for low pressure-nanoimprint lithography

    Science.gov (United States)

    Tak, Hyowon; Tahk, Dongha; Jeong, Chanho; Lee, Sori; Kim, Tae-il

    2017-10-01

    We presented surface energy-tunable nanoscale molds for unconventional lithography. The mold is highly robust, transparent, has a minimized haze, does not contain additives, and is a non-fluorinated isodecyl acrylate and trimethylolpropane triacrylate based polymer. By changing the mixing ratio of the polymer components, the cross-linking density, mechanical modulus, and surface energy (crucial factors in low pressure ((1–2) × 105 N m‑2) low pressure-nanoimprint lithography (LP-NIL)), can be controlled. To verify these properties of the molds, we also characterized the surface energy by measuring the contact angles and calculating the work of adhesion among the wafer, polymer film, and mold for successful demolding in nanoscale structures. Moreover, the molds showed high optical clarity and precisely tunable mechanical and surface properties, capable of replicating sub-100 nm patterns by thermal LP-NIL and UV-NIL.

  1. Interplay between lattice dynamics and the low-pressure phase of simple cubic polonium

    Science.gov (United States)

    Zaoui, A.; Belabbes, A.; Ahuja, R.; Ferhat, M.

    2011-04-01

    Low-pressure structural properties of simple cubic polonium are explored through first-principles density-functional theory based relativistic total energy calculations using pseudopotentials and plane-wave basis set, as well as linear-response theory. We have found that Po undergoes structural phase transition at low pressure near 2 GPa, where the element transforms from simple cubic to a mixture of two trigonal phases namely, hR1 (α=86°) and hR2 (α=97.9°) structures. The lattice dynamics calculations provide strong support for the observed phase transition, and show the dynamical stability (instability) of the hR2 (hR1) phase.

  2. Mesoscopic simulation of diffusive contaminant spreading in gas flows at low pressure

    CERN Document Server

    Schmieschek, S; Keller, F; Nieken, U; Harting, J

    2015-01-01

    Many modern production and measurement facilities incorporate multiphase systems at low pressures. In this region of flows at small, non-zero Knudsen- and low Mach numbers the classical mesoscopic Monte Carlo methods become increasingly numerically costly. To increase the numerical efficiency of simulations hybrid models are promising. In this contribution, we propose a novel efficient simulation approach for the simulation of two phase flows with a large concentration imbalance in a low pressure environment in the low intermediate Knudsen regime. Our hybrid model comprises a lattice-Boltzmann method corrected for the lower intermediate Kn regime proposed by Zhang et al. for the simulation of an ambient flow field. A coupled event-driven Monte-Carlo-style Boltzmann solver is employed to describe particles of a second species of low concentration. In order to evaluate the model, standard diffusivity and diffusion advection systems are considered.

  3. Development of a low pressure chromatographic flow system for monitoring the biodegradation of ofloxacin and ciprofloxacin

    OpenAIRE

    Santos, Inês C.; Mesquita, Raquel R. B.; Amorim, Catarina L.; Castro, Paula M. L.; Rangel,António O. S. S.

    2016-01-01

    In this work, we propose a simple low pressure chromatography method with a high throughput for monitoring the biodegradation of fluoroquinolones. Fluoroquinolones are a class of antibiotics that have been accumulating in the environment as a consequence of their release from different sources, namely hospital waste. It has been found that wastewater treatment plants are not able to completely remove this type of micro-pollutants and so, alternative solutions are necessary. Some biodegradatio...

  4. Experimental Studies of Low-Pressure Plasma Jet by Means of Langmuir Probes and Emission Spectra

    Institute of Scientific and Technical Information of China (English)

    LIU Lei; CAO Jinxiang; NIU Tianye; WANG Liang; MENG Gang; LIU Xin; YUAN Lei; WU Runhui; ZHANG Shengjun; REN Aimin

    2009-01-01

    An investigation was made into the argon plasma jet that expanded in a low-pressure vacuum chamber. The spatial distributions of the parameters of the plasma jet with different supplied powers were measured using a ten-channel Langmuir probe array. The chemical species in the plasma jet were identified by emission spectroscopy. The electron excitation temperatures at two positions, 10 cm and 50 cm downstream from the nozzle exit were calculated, respectively, by the Boltzmann plot method.

  5. Low-pressure glow discharge in a Xenon/Chlorine mixture

    Science.gov (United States)

    Shuaibov, A. K.; Shimon, L. L.; Shevera, I. V.; Dashchenko, A. I.

    2002-12-01

    The spatial, electrical, and optical characteristics of a transverse glow discharge and a volume discharge with a spherical anode and plane cathode in low-pressure Xe/Cl2 mixtures are studied. It is shown that the transverse glow discharge in mixtures with a low chlorine content occupies most of the interelectrode gap and exists in the form of strata. As the total pressure ( P≥300 Pa) and the partial chlorine pressure ( P(Cl2)≥80 Pa) increase, a solitary plasma domain with a volume of 1-2 cm3 forms in the discharge gap. It acts as a selective source of UV radiation in the XeCl(D-X) 236-nm, Cl2 (D'-A') 257-nm, and XeCl(B-X) 308-nm bands. In certain Xe/Cl2 mixtures, plasma self-oscillations in the frequency range 1-100 kHz are observed. The current of a low-pressure volume discharge with a spherical anode and plane cathode and the emission from it have both a dc and an ac component. The pressure and composition of the working mixture, as well as the average current of the volume discharge are optimized to attain the maximum emission intensity of the XeCl(D,B-X) bands. Low-pressure volume discharges in xenon/chlorine mixtures can be used as active media in low-pressure large-aperture planar or cylindrical excimer-halogen lamps emitting modulated or repetitive pulsed UV radiation.

  6. Observation of Quartz Cathode-Luminescence in a Low Pressure Plasma Discharge

    Science.gov (United States)

    Foster, John E.

    2004-01-01

    Intense, steady-state cathode-luminescence has been observed from exposure of quartz powder to a low pressure rf-excited argon plasma discharge. The emission spectra (400 to 850 nm) associated with the powder luminescence were documented as a function of bias voltage using a spectrometer. The emission was broad-band, essentially washing out the line spectra features of the argon plasma discharge.

  7. Low-pressure pneumoperitoneum during laparoscopic donor nephrectomy to optimize live donors' comfort.

    Science.gov (United States)

    Warlé, M C; Berkers, A W; Langenhuijsen, J F; van der Jagt, M F; Dooper, Ph M; Kloke, H J; Pilzecker, D; Renes, S H; Wever, K E; Hoitsma, A J; van der Vliet, J A; D'Ancona, F C H

    2013-01-01

    Nowadays, laparoscopic donor nephrectomy (LDN) has become the gold standard to procure live donor kidneys. As the relationship between donor and recipient loosens, it becomes of even greater importance to optimize safety and comfort of the surgical procedure. Low-pressure pneumoperitoneum has been shown to reduce pain scores after laparoscopic cholecystectomy. Live kidney donors may also benefit from the use of low pressure during LDN. To evaluate feasibility and efficacy to reduce post-operative pain, we performed a randomized blinded study. Twenty donors were randomly assigned to standard (14 mmHg) or low (7 mmHg) pressure during LDN. One conversion from low to standard pressure was indicated by protocol due to lack of progression. Intention-to-treat analysis showed that low pressure resulted in a significantly longer skin-to-skin time (149 ± 86 vs. 111 ± 19 min), higher urine output during pneumoperitoneum (23 ± 35 vs. 11 ± 20 mL/h), lower cumulative overall pain score after 72 h (9.4 ± 3.2 vs. 13.5 ± 4.5), lower deep intra-abdominal pain score (11 ± 3.3 vs. 7.5 ± 3.1), and a lower cumulative overall referred pain score (1.8 ± 1.9 vs. 4.2 ± 3). Donor serum creatinine levels, complications, and quality of life dimensions were not significantly different. Our data show that low-pressure pneumoperitoneum during LDN is feasible and may contribute to increase live donors' comfort during the early post-operative phase.

  8. Low pressure arc discharge lamp apparatus with magnetic field generating means

    Science.gov (United States)

    Grossman, M.W.; George, W.A.; Maya, J.

    1987-10-06

    A low-pressure arc discharge apparatus having a magnetic field generating means for increasing the output of a discharge lamp is disclosed. The magnetic field generating means, which in one embodiment includes a plurality of permanent magnets, is disposed along the lamp for applying a constant transverse magnetic field over at least a portion of the positive discharge column produced in the arc discharge lamp operating at an ambient temperature greater than about 25 C. 3 figs.

  9. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    OpenAIRE

    Fleetwood, James D

    2014-01-01

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these proc...

  10. Growth Enhancement of Radish Sprouts Induced by Low Pressure O2 Radio Frequency Discharge Plasma Irradiation

    Science.gov (United States)

    Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu; Hayashi, Nobuya

    2012-01-01

    We studied growth enhancement of radish sprouts (Raphanus sativus L.) induced by low pressure O2 radio frequency (RF) discharge plasma irradiation. The average length of radish sprouts cultivated for 7 days after O2 plasma irradiation is 30-60% greater than that without irradiation. O2 plasma irradiation does not affect seed germination. The experimental results reveal that oxygen related radicals strongly enhance growth, whereas ions and photons do not.

  11. Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades

    OpenAIRE

    2007-01-01

    This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP) neural network and genetic algorithm (GA), the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pres...

  12. Study of the low-pressure plasma effect on polypropylene nonwovens

    Science.gov (United States)

    López, R.; Boronat, T.; Pascual, M.; Calvo, O.; Balart, R.

    2010-06-01

    In this work we have used low-pressure plasma with a gas based on methane and oxygen mixture to improve wettability and durability of a PP nonwoven fabrics. The obtained results show good durability with the use of methane-oxygen plasma mixture gas. The effects of the plasma are similar to a plasmapolymerization process but in this case we obtain hydrophilic properties with high durability. The surface does not suffer important changes and the roughness of the material remains constant.

  13. Effect of balanced low pressure drying of curcuma longa leaf on skin immune activation activities.

    Science.gov (United States)

    Choi, Wooseok; Lim, Hye Won; Lee, Hyeon Yong

    2014-01-01

    The effect of balanced low pressure drying pretreatment associated with ultrasonication extraction (BU) on the enhancement of skin immune modulatory activities of Curcuma longa leaf was studied by comparing with conventional hot air drying (HE), freeze drying (FE) and balanced low pressure drying (BE) pretreatment processes. In considering skin immune activation activities such as the inhibition of hyaluronidase activity, the BU extract showed ca. 10% higher than those of HE, and even higher than that of the FE extract. Nitric oxide production from macrophage of the BU extract in adding 1.0 mg/mL was increased up to 16.5 μM. When measuring inhibition of IL-6 and TNF-a production from the human T lymphocytes (T cell), the BU extract also showed 53% and 78% of inhibition effect, respectively. It is found that the BU extract could effectively suppress the expression levels of skin inflammation related genes such as Cox-2 and iNOS, down to 80% and 85% compared to the control, respectively. Balanced low pressure drying process was especially active on dehydration of the leaves with minimizing the destruction and making easier elution of the bioactive substances, which resulted in higher extraction yield and better biological activities.

  14. Characteristics of long-gap AC streamer discharges under low pressure conditions

    Science.gov (United States)

    Yang, Yaqi; Li, Weiguo; Xia, Yu; Yuan, Chuangye

    2017-10-01

    The generation and propagation of a streamer is a significant physical process of air gap discharge. Research on the mechanism of streamers under low-pressure conditions is helpful for understanding the process of long-gap discharge in a high-altitude area. This paper describes laboratory investigations of streamer discharge under alternating current (AC) voltage in a low pressure test platform for a 60 cm rod-plane gap at 30 kPa, and analyzes the characteristics of streamer generation and propagation. The results show that the partial streamer and breakdown streamer all occur in the positive half-cycle of AC voltage near the peak voltage at 30 kPa. The partial streamer could cause the distortion of current and voltage waveform, and it appears as the branching characteristic at the initial stage. With the extension of the streamer, the branching and tortuosity phenomena become gradually obvious, but the branching is suppressed when the streamer crosses the gap. The low-pressure condition has little influence on the tortuosity length and the tortuosity number of the streamer, but affect the diameter of streamer obviously.

  15. Efficacy of epidural blood patches for spontaneous low-pressure headaches: a case series.

    Science.gov (United States)

    Ansel, S; Rae, A; Tyagi, A

    2016-12-01

    Patients with a spontaneous cerebrospinal fluid leak, normally at a spinal level, typically present with low-pressure headache. In refractory cases, an epidural blood patch may be attempted. We aimed to assess the efficacy of lumbar epidural blood patching in spontaneous, low-pressure headaches. Methods We retrospectively analysed notes of patients who had an epidural blood patch performed for spontaneous low-pressure headaches in a single centre. Information regarding demographics, radiology and clinic follow-up was extracted from an electronic patient record system. Questionnaires regarding outcome were sent to patients a minimum of 6 months post-procedure. All patients received an epidural blood patch in the lumbar region irrespective of the site of cerebrospinal fluid leak. Results Sixteen patients who underwent lumbar epidural blood patching were analysed (11 female; mean age 43 years). The site of cerebrospinal fluid leak was evident in only 3/16 patients. Thirteen patients attended clinic follow-up; three reported complete headache resolution, four reported improvement in intensity or frequency and six described no change. Five of eight questionnaire respondents reported reduction in pain, and in these responders, mean headache severity improved from 9/10 to 3/10. Five of eight patients returning follow-up questionnaires reported sustained improvement in headache symptoms. Conclusion Epidural blood patch procedures can provide sustained improvement in headache symptoms in selected patients with spontaneous intracranial hypotension, but an untargeted approach has a lower success rate than reported in other case series.

  16. Molecular-level Insight into Unusual Low Pressure CO2 Affinity in Pillared Metal-Organic Frameworks

    NARCIS (Netherlands)

    Burtch, N.C.; Jasuja, H.; Dubbeldam, D.; Walton, K.S.

    2013-01-01

    Fundamental insight into how low pressure adsorption properties are affected by chemical functionalization is critical to the development of next-generation porous materials for postcombustion CO2 capture. In this work, we present a systematic approach to understanding low pressure CO2 affinity in i

  17. Molecular-level Insight into Unusual Low Pressure CO2 Affinity in Pillared Metal-Organic Frameworks

    NARCIS (Netherlands)

    Burtch, N.C.; Jasuja, H.; Dubbeldam, D.; Walton, K.S.

    2013-01-01

    Fundamental insight into how low pressure adsorption properties are affected by chemical functionalization is critical to the development of next-generation porous materials for postcombustion CO2 capture. In this work, we present a systematic approach to understanding low pressure CO2 affinity in i

  18. Temperature limited fed-batch technique for control of proteolysis in Pichia pastoris bioreactor cultures

    Directory of Open Access Journals (Sweden)

    Garcia Percival

    2003-06-01

    Full Text Available Abstract Background A temperature limited fed-batch (TLFB technique is described and used for Pichia pastoris Mut+ strain cultures and compared with the traditional methanol limited fed-batch (MLFB technique. A recombinant fusion protein composed of a cellulose-binding module (CBM from Neocallimastix patriciarum cellulase 6A and lipase B from Candida antarctica (CALB, was produced and secreted by this strain. Results A protein concentration of about 1 g L-1 was produced in the MLFB process. However, this product was considerably degraded by protease(s. By applying the TLFB process, the yield was increased to 2 g L-1 full-length product and no proteolytic degradation was observed. Flow cytometry analysis showed that the percentage of dead cells increased rapidly during the initial methanol feed phase in the MLFB process and reached a maximum of about 12% after about 40–70 hours of methanol feeding. In the TLFB process, cell death rate was low and constant and reached 4% dead cells at the end of cultivation (about 150 hours methanol feeding time. The lower cell death rate in the TLFB correlated with a lower protease activity in the culture supernatant. The specific alcohol oxidase (AOX activity in the TLFB process was 3.5 times higher than in the MLFB process. Conclusion Three mechanisms that may contribute to the much higher accumulation of product in the TLFB process are: 1 reduced proteolysis due to lower temperature, 2 reduced proteolysis due to lower cell death and protease release to the medium, 3 increased synthesis rate due to higher AOX activity.

  19. Peptidomic Analysis of Rat Plasma: Proteolysis in Hemorrhagic Shock.

    Science.gov (United States)

    Aletti, Federico; Maffioli, Elisa; Negri, Armando; Santamaria, Marco H; DeLano, Frank A; Kistler, Erik B; Schmid-Schönbein, Geert W; Tedeschi, Gabriella

    2016-05-01

    It has been previously shown that intestinal proteases translocate into the circulation during hemorrhagic shock and contribute to proteolysis in distal organs. However, consequences of this phenomenon have not previously been investigated using high-throughput approaches. Here, a shotgun label-free quantitative proteomic approach was utilized to compare the peptidome of plasma samples from healthy and hemorrhagic shock rats to verify the possible role of uncontrolled proteolytic activity in shock. Plasma was collected from rats after hemorrhagic shock (HS) consisting of 2-h hypovolemia followed by 2-h reperfusion, and from healthy control (CTRL) rats. A new two-step enrichment method was applied to selectively extract peptides and low molecular weight proteins from plasma, and directly analyze these samples by tandem mass spectrometry. One hundred twenty-six circulating peptides were identified in CTRL and 295 in HS animals. Ninety-six peptides were present in both conditions; of these, 57 increased and 30 decreased in shock. In total, 256 peptides were increased or present only in HS confirming a general increase in proteolytic activity in shock. Analysis of the proteases that potentially generated the identified peptides suggests that the larger relative contribution to the proteolytic activity in shock is due to chymotryptic-like proteases. These results provide quantitative confirmation that extensive, system-wide proteolysis is part of the complex pathologic phenomena occurring in hemorrhagic shock.

  20. Regulated specific proteolysis of the Cajal body marker protein coilin.

    Science.gov (United States)

    Velma, Venkatramreddy; Broome, Hanna J; Hebert, Michael D

    2012-12-01

    Cajal bodies (CB) are subnuclear domains that contain various proteins with diverse functions including the CB marker protein coilin. In this study, we investigate the proteolytic activity of calpain on coilin. Here, we report a 28-kDa cleaved coilin fragment detected by two coilin antibodies that is cell cycle regulated, with levels that are consistently reduced during mitosis. We further show that an in vitro calpain assay with full-length or C-terminal coilin recombinant protein releases the same size cleaved fragment. Furthermore, addition of exogenous RNA to purified coilin induces proteolysis by calpain. We also report that the relative levels of this cleaved coilin fragment are susceptible to changes induced by various cell stressors, and that coilin localization is affected by inhibition or knockdown of calpain both under normal and stressed conditions. Collectively, our data suggest that coilin is subjected to regulated specific proteolysis by calpain, and this processing may play a role in the regulation of coilin activity and CB formation.

  1. Plant senescence and proteolysis: two processes with one destiny

    Directory of Open Access Journals (Sweden)

    Mercedes Diaz-Mendoza

    Full Text Available Abstract Senescence-associated proteolysis in plants is a complex and controlled process, essential for mobilization of nutrients from old or stressed tissues, mainly leaves, to growing or sink organs. Protein breakdown in senescing leaves involves many plastidial and nuclear proteases, regulators, different subcellular locations and dynamic protein traffic to ensure the complete transformation of proteins of high molecular weight into transportable and useful hydrolysed products. Protease activities are strictly regulated by specific inhibitors and through the activation of zymogens to develop their proteolytic activity at the right place and at the proper time. All these events associated with senescence have deep effects on the relocation of nutrients and as a consequence, on grain quality and crop yield. Thus, it can be considered that nutrient recycling is the common destiny of two processes, plant senescence and, proteolysis. This review article covers the most recent findings about leaf senescence features mediated by abiotic and biotic stresses as well as the participants and steps required in this physiological process, paying special attention to C1A cysteine proteases, their specific inhibitors, known as cystatins, and their potential targets, particularly the chloroplastic proteins as source for nitrogen recycling.

  2. Study of low-pressure premixed laminar n-heptane+ propane/oxygen/nitrogen flames

    Institute of Scientific and Technical Information of China (English)

    YU Wu; WEI LiXia; MA ZhiHao; HUANG ZuoHua; YUAN Tao; TIAN ZhenYu; LI YuYang

    2009-01-01

    Low-pressure premixed laminar n-heptane+propane/oxygen/nitrogen flames were investigated with tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam sampling mass spectrometry. Three flames with different mass percentage of propane in the fuel blends of 0%, 10%, and 20% were studied. The combustion intermediates were identified by comparing the measured IEs with those values in literatures. Mole fraction profiles of the main species were compared among the three flames. The experimental results provide detailed data in understanding the combustion of n-heptane and n-heptane/propane blends in engine. They are also helpful in establishing and verifying the kinetic models.

  3. An experimental and kinetic modeling study of premixed nitromethane flames at low pressure

    DEFF Research Database (Denmark)

    Zhang, Kuiwen; Li, Yuyang; Yuan, Tao

    2011-01-01

    An experimental and modeling study is reported on three premixed nitromethane/oxygen/argon flames at low pressure (4.655kPa) with equivalence ratios (ϕ) of 1.0, 1.5 and 2.0. Flame species were identified with tunable synchrotron vacuum ultraviolet photoionization. The mole fraction profiles of more...... against experimental results of all three flames. The computed predictions showed satisfactory agreement with the experimental results. Based on a rate-of-production analysis, reaction pathway diagrams were obtained to describe the hydrocarbon oxidation process and nitrogenous species chemistry...

  4. Unsteady effects at the interface between impeller-vaned diffuser in a low pressure centrifugal compressor

    Directory of Open Access Journals (Sweden)

    Mihai Leonida NICULESCU

    2013-03-01

    Full Text Available In this paper, Proper Orthogonal Decomposition (POD is applied to the analysis of the unsteady rotor-stator interaction in a low-pressure centrifugal compressor. Numerical simulations are carried out through finite volumes method using the Unsteady Reynolds-Averaged Navier-Stokes Equations (URANS model. Proper Orthogonal Decomposition allows an accurate reconstruction of flow field using only a small number of modes; therefore, this method is one of the best tools for data storage. The POD results and the data obtained by the Adamczyk decomposition are compared. Both decompositions show the behavior of unsteady rotor-stator interaction, but the POD modes allow quantifying better the numerical errors.

  5. Investigation of Low-Pressure Turbine Endwall Flows: Simulations and Experiments (Postprint)

    Science.gov (United States)

    2015-01-01

    Endwall Losses of High Lift Low Pressure Turbine Vanes ,” Ph.D. Dissertation, Air Force Institute of Technology, 2012 13Sauer, H., Muller, R., and...2001, pp. 207-213 14Zess, G., and Thole, K., “Computational Design and Experimental Evaluation of Using a Leading Edge Fillet on a Gas Turbine Vane ,” J...Turbine,” ASME Paper 94-GT-249, 1994 19Harvey, N., Rose, M., Taylor, M., Shahpar, S., Hartland, J., and Gregory- Smith , D., “Nonaxisymmetric turbine

  6. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination.

    OpenAIRE

    Fumagalli, F; Kylian, O; Amato, Letizia; Hanus, J; Rossi, F.

    2012-01-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can be achieved using pure H2O or Ar/H2O mixtures at low temperatures with removal rates comparable to oxygen-based mixtures. Particle fluxes (Ar+ ions, O and H atomic radicals and OH molecular radicals) fro...

  7. Cure Reaction Kinetics of Low Pressure Sheet Molding Compound System Thickened by Crystalline Polymer

    Institute of Scientific and Technical Information of China (English)

    QIN Yan; LIU Haihua; HUANG Zhixiong; MEI Qilin

    2007-01-01

    Several kinetic models for unsaturated polyester cure reaction and some existing parameter estimation techniques of these models were introduced. Correlated kinetic parameters and kinetic equations of the autocatalytic empirical kinetic model of LPSMC system were determined by using isothermal DSC to scan the system which was thickened by crystalline polymer (PEG-MAH). Through using a serial curing degree of the system to validate the model, the experimental results were basically identical with the predictions of the autocatalytic empirical kinetic model. This model could provide a theoretical reference to the determination of molding techniques of low pressure SMC.

  8. Cavity ringdown laser absorption spectroscopy detection of formyl (HCO) radical in a low pressure flame

    Science.gov (United States)

    Scherer, J. J.; Rakestraw, D. J.

    1997-01-01

    The formyl radical has been detected via the ÖX˜ system in a low pressure CH 4/N 2/O 2 flame using cavity ringdown laser absorption spectroscopy. The direct absorption data obtained in these initial studies allows determination of the absolute HCO concentration in the flame of ca. 2.1(±0.9) × 10 13 mol cm -3, which is in excellent agreement with flame chemistry simulations. The extrapolated detection limit at 300 K of ≈ 1.4(±0.6) × 10 11 mol cm -3 is comparable to that of other methods, including intracavity laser absorption spectroscopy.

  9. Remote sensing of a low pressure plasma in the radio near field

    Science.gov (United States)

    Kelly, Seán; McNally, Patrick J.

    2017-09-01

    A novel approach to remotely monitor low pressure non-equilibrium plasmas is reported. A magnetic field antenna is positioned in the near field of a capacitively coupled plasma. Magnetic flux from plasma currents, present near the viewport, is intercepted by a calibrated loop antenna placed outside the chamber. The induced signal current is correlated to bulk plasma currents. The comparison of relative harmonic amplitudes shows resonance features for lower operating pressures. The geometric resonance and electron-neutral collision frequencies are evaluated from resonant harmonic features. This approach advances remote, noninvasive, and installation-free plasma monitoring, which is of particular interest to industrial scenarios.

  10. Ion time-of-flight study of laser ablation of silver in low pressure gases

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    The dynamics of ions from a laser-ablated silver target in low pressure background atmospheres have been investigated in a simple geometry using an electrical probe. A simple scattering picture for the first transmitted peak of the observed plume splitting has been used to calculate cross section...... of the ablated silver ions in oxygen (sigma{O(2)} = 4.8 x 10(-16) cm(2)) and in argon (sigma{Ar} = 6.7 x 10(-16) cm(2)). The dynamics of the blast wave is well described by blast wave theory. (C) 1999 Elsevier Science B.V. All rights reserved....

  11. Low pressure water vapour discharge as a light source: I. Spectroscopic characteristics and efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Artamonova, E; Artamonova, T; Beliaeva, A; Gorbov, D; Khodorkovskii, M; Melnikov, A; Milenin, V; Murashov, S; Rakcheeva, L; Timofeev, N [Saint-Petersburg State University, Ulyanovskaya 3, 198504 (Russian Federation); Michael, D [General Electric Global Research Center, One Research Circle (Bldg K1 Rm 4B31), Niskayuna, NY, 12309 (United States)], E-mail: timofeev@pobox.spbu.ru, E-mail: michael@crd.ge.com

    2008-08-07

    Spectral and electrical characteristics of a low pressure dc discharge formed from a mixture of one of the rare gases Ne, Ar or Kr plus water vapour are studied. Water vapour is only a minor additive to the rare gas. It has been shown that enhanced emission of the OH 306.4 nm band is registered from the discharge of Ar mixed with water vapour. Plasmas from the other investigated rare gases yielded considerably less OH 306.4 nm emission. Data about consumed electric power, spectra and relative efficiencies are presente000.

  12. Electron energy probability function and L-p similarity in low pressure inductively coupled bounded plasma

    OpenAIRE

    Chatterjee, Sanghamitro; Bhattacharjee, Sudeep; Charles, Christine; Boswell, Rod

    2015-01-01

    Particle-In-Cell (PIC) simulations are carried out to investigate the effect of discharge length (L) and pressure (p) on Electron Energy Probability Function (EEPF) in a low pressure radio frequency (rf) inductively coupled plasma (ICP) at 13.56 MHz. It is found that for both cases of varying L (0.1–0.5 m) and p (1–10 mTorr), the EEPF is a bi-Maxwellian with a step in the bounded direction (x) and non-Maxwellian with a hot tail in the symmetric unbounded directions (y, z). The plasma space po...

  13. Low pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    DEFF Research Database (Denmark)

    Fumagalli, F; Kylian, O; Amato, Letizia

    2012-01-01

    be achieved using pure H2O or Ar/H2O mixtures at low temperatures with removal rates comparable to oxygen-based mixtures. Particle fluxes (Ar+ ions, O and H atomic radicals and OH molecular radicals) from water vapour discharge are measured by optical emission spectroscopy and Langmuir probe under several......Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can...

  14. Experimental measurement of the thermal stability criteria for low pressure methanol synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Berty, J.M.; Lenczyk, J.P.; Shah, S.M.

    1982-11-01

    The mathematical basis was derived for the experimental measurement of the ''Slope Condition'' and of the ''Dynamic Condition'' of the thermal stability criteria in a laboratory-scale internal recycle reactor. This work also resulted in clearer interpretations and simpler expressions for the two stability criteria. The method was experimentally demonstrated on the example of the low pressure methanol synthesis. Only seven experiments were needed to evaluate the stability criteria of this reaction for which the kinetics is unknown.

  15. Is the use of low-pressure pulsatile lavage for pressure ulcer management associated with environmental contamination with Acinetobacter baumannii?

    Science.gov (United States)

    Ho, Chester H; Johnson, Tova; Miklacic, Joan; Donskey, Curtis J

    2009-10-01

    Ho CH, Johnson T, Miklacic J, Donskey CJ. Is the use of low-pressure pulsatile lavage for pressure ulcer management associated with environmental contamination with Acinetobacter baumannii? To determine the extent of environmental contamination associated with low-pressure pulsatile lavage of stage III or IV pressure ulcers in patients with spinal cord injury (SCI) when routine infection control precautions are used for wounds colonized or infected with Acinetobacter baumannii. Prospective investigation in which pressure ulcer cultures and environmental cultures were obtained before and after low-pressure pulsatile lavage treatment, and before and after regular dressing changes. Environmental cultures included the patient's bedrail and settle plates placed 0.6, 1.5, and 2.4m from the wound to assess airborne spread of A. baumannii. SCI inpatient unit in a Department of Veterans Affairs Medical Center. Inpatients (N=15) with SCI receiving daily low-pressure pulsatile lavage treatment for stage III or IV pressure ulcers with standard dressing change, as well as regular dressing changes without low-pressure pulsatile lavage at other times of the day. Standard, regular dressing changes and dressing changes with low-pressure pulsatile lavage. Comparison of frequency of environmental contamination with A. baumannii associated with low-pressure pulsatile lavage versus regular dressing changes. Of the 15 SCI inpatients meeting inclusion criteria, 9 (60%) grew A. baumannii from their wounds. Of the 9 patients with wound cultures positive for A. baumannii, only 1 (11%) had environmental contamination with this organism after performance of low-pressure pulsatile lavage, and the same patient had environmental contamination after a standard dressing change. The antibiotic susceptibility patterns of the wound and environmental A. baumannii isolates were identical. Low-pressure pulsatile lavage using the infection control methods described is not associated with an increased

  16. Nutritional Control of DNA Replication Initiation through the Proteolysis and Regulated Translation of DnaA.

    Directory of Open Access Journals (Sweden)

    David J Leslie

    2015-07-01

    Full Text Available Bacteria can arrest their own growth and proliferation upon nutrient depletion and under various stressful conditions to ensure their survival. However, the molecular mechanisms responsible for suppressing growth and arresting the cell cycle under such conditions remain incompletely understood. Here, we identify post-transcriptional mechanisms that help enforce a cell-cycle arrest in Caulobacter crescentus following nutrient limitation and during entry into stationary phase by limiting the accumulation of DnaA, the conserved replication initiator protein. DnaA is rapidly degraded by the Lon protease following nutrient limitation. However, the rate of DnaA degradation is not significantly altered by changes in nutrient availability. Instead, we demonstrate that decreased nutrient availability downregulates dnaA translation by a mechanism involving the 5' untranslated leader region of the dnaA transcript; Lon-dependent proteolysis of DnaA then outpaces synthesis, leading to the elimination of DnaA and the arrest of DNA replication. Our results demonstrate how regulated translation and constitutive degradation provide cells a means of precisely and rapidly modulating the concentration of key regulatory proteins in response to environmental inputs.

  17. Effect of Low Pressure End Conditions on Steam Power Plant Performance

    Directory of Open Access Journals (Sweden)

    Ali Syed Haider

    2014-07-01

    Full Text Available Most of the electricity produced throughout the world today is from steam power plants and improving the performance of power plants is crucial to minimize the greenhouse gas emissions and fuel consumption. Energy efficiency of a thermal power plant strongly depends on its boiler-condenser operating conditions. The low pressure end conditions of a condenser have influence on the power output, steam consumption and efficiency of a plant. Hence, the objective this paper is to study the effect of the low pressure end conditions on a steam power plant performance. For the study each component was modelled thermodynamically. Simulation was done and the results showed that performance of the condenser is highly a function of its pressure which in turn depends on the flow rate and temperature of the cooling water. Furthermore, when the condenser pressure increases both net power output and plant efficiency decrease whereas the steam consumption increases. The results can be used to run a steam power cycle at optimum conditions.

  18. Laparoscopic Cholecystectomy Under Spinal Anesthesia with Low-Pressure Pneumoperitoneum - Prospective Study of 150 Cases

    Directory of Open Access Journals (Sweden)

    Sunder Goyal

    2012-08-01

    Materials and Methods: In a private rural medical college, 150 patients were selected prospectively for laparoscopic cholecystectomy, under low-pressure (8mmHg pneumoperitoneum and under spinal anesthesia over a span of one and a half years. Injection bupivacaine (0.5% was used for spinal anesthesia. All ports were made in a head-down position to avoid hypotension. Shoulder pain was managed by reassurance as well as by diverting the attention and sedation in a few cases. Results: We successfully performed the operations in 145 patients without major complications. Spinal anesthesia was converted to general anesthesia in five patients due to severe shoulder pain. Age varied between 21 and 75 years. Duration of operation time (skin to skin was between 40 and 80 minutes. Twenty-nine patients complained of right shoulder pain. Most of them were managed by reassurance from the anesthetist and a few needed an injection of fentanyl along with midazolam. Conclusion: Laparoscopic cholecystectomy with low-pressure CO2 pneumoperitoneum is feasible and safe under spinal anesthesia. Incidence of postoperative shoulder pain and complications are comparable with laparoscopic cholecystectomy under general anesthesia. [Arch Clin Exp Surg 2012; 1(4.000: 224-228

  19. Kinetic mechanism for low-pressure oxygen/methane ignition and combustion

    Science.gov (United States)

    Slavinskaya, N. A.; Wiegand, M.; Starcke, J. H.; Riedel, U.; Haidn, O. J.; Suslov, D.

    2013-03-01

    It is known that during a launch of a rocket, the interaction of the exhaust gases of rocket engines with the atmosphere causes a local depletion of the ozone layer. In order to study these chemical processes in detail, a chemical reaction mechanism of the methane oxidation appropriate for high- and low-pressure conditions and a chemical reactor network to reproduce operating conditions in rocket engines and in the environment have been developed. An earlier developed detailed chemical kinetic model for the high-pressure CH4/O2 combustion has been improved for the low pressure and low temperature methane combustion and augmented with a submodel for NOx formation. The main model improvements are related to the pressure depending reactions. The model has been validated for operating conditions of 0.02 jet. Simulations performed have shown that the exhaust gases of a methane/oxygen propelled liquid rocket engine contain high amounts of active radicals, which can influence the formation of nitrogen compounds and consume ozone in the atmosphere.

  20. An expression for the h l factor in low-pressure electronegative plasma discharges

    Science.gov (United States)

    Chabert, P.

    2016-04-01

    The positive ion flux exiting a low-pressure plasma discharge is a crucial quantity in global (volume-averaged) models. In discharges containing only electrons and positive ions (electropositive discharges), it is common to write this flux {Γ\\text{wall}}={{h}\\text{l}}{{n}\\text{i0}}{{u}\\text{B}} , where {{n}\\text{i0}} is the central positive ion density, {{u}\\text{B}} is the positive ion fluid speed at the sheath edge (the Bohm speed), and {{h}\\text{l}} is the positive ion edge-to-centre density ratio. There are well established formulae for {{h}\\text{l}} in electropositive discharges, but for discharges containing negative ions (electronegative discharges), the analysis is more complicated. The purpose of this paper is to propose a formula for the {{h}\\text{l}} factor in low-pressure electronegative discharges. We use the numerical solution of fluid equations with Boltzmann negative ions, including Poisson’s equation, as a guide to derive an analytical expression that can easily be incorporated in global models. The parameter space in which the derived expression is valid is discussed at the end of the paper.

  1. Evacuation of coal from hoppers/silos with low pressure pneumatic blasting systems

    Science.gov (United States)

    Fischer, J. S.

    1977-01-01

    The need for an efficient, economical, effective and quiet device for moving coal and other difficult bulk solids was recognized. Thus came the advent of the low pressure pneumatic blasting system - a very efficient means of using a small amount of plant air (up to 125 PSI) to eliminate the most troublesome material hang-ups in storage containers. This simple device has one moving part and uses approximately 3% of the air consumed by a pneumatic vibrator on the same job. The principle of operation is very simple: air stored in the unit's reservoir is expelled directly into the material via a patented quick release valve. The number, size, and placement of the blaster units on the storage vessel is determined by a series of tests to ascertain flowability of the problem material. These tests in conjunction with the hopper or silo configuration determine specification of a low pressure pneumatic blasting system. This concept has often proven effective in solving flow problems when all other means have failed.

  2. Weak interactions between water and clathrate-forming gases at low pressures

    Energy Technology Data Exchange (ETDEWEB)

    Thurmer, Konrad; Yuan, Chunqing; Kimmel, Gregory A.; Kay, Bruce D.; Smith, R. Scott

    2015-11-01

    Using scanning probe microscopy and temperature programed desorption we examined the interaction between water and two common clathrate-forming gases, methane and isobutane, at low temperature and low pressure. Water co-deposited with up to 10-1 mbar methane or 10-5 mbar isobutane at 140 K onto a Pt(111) substrate yielded pure crystalline ice, i.e., the exposure to up to ~107 gas molecules for each deposited water molecule did not have any detectable effect on the growing films. Exposing metastable, less than 2 molecular layers thick, water films to 10-5 mbar methane does not alter their morphology, suggesting that the presence of the Pt(111) surface is not a strong driver for hydrate formation. This weak water-gas interaction at low pressures is supported by our thermal desorption measurements from amorphous solid water and crystalline ice where 1 ML of methane desorbs near ~43 K and isobutane desorbs near ~100 K. Similar desorption temperatures were observed for desorption from amorphous solid water.

  3. Phosphorus recovery from sewage sludge with a hybrid process of low pressure wet oxidation and nanofiltration.

    Science.gov (United States)

    Blöcher, Christoph; Niewersch, Claudia; Melin, Thomas

    2012-04-15

    Phosphorus recovery from sewage sludge will become increasingly important within the next decades due to depletion of mineral phosphorus resources. In this work a new process concept was investigated, which aims at realising phosphorus recovery in a synergistic way with the overall sewage sludge treatment scheme. This process combines a low pressure wet oxidation for sewage sludge decomposition as well as phosphorus dissolution and a nanofiltration process to separate phosphorus from heavy metals and obtain a clean diluted phosphoric acid, from which phosphorus can be recovered as clean fertiliser. It was shown that this process concept is feasible for sewage sludge for wastewater treatment plants that apply enhanced biological removal or precipitation with alumina salts for phosphorus removal. The critical parameter for phosphorus dissolution in the low pressure wet oxidation process is the iron concentration, while in the nanofiltration multi-valent cations play a predominant role. In total, a phosphorus recovery of 54% was obtained for an exemplary wastewater treatment plant. Costs of the entire process are in the same range as conventional sewage sludge disposal, with the benefit being phosphorus recovery and reduced emission of greenhouse gases due to avoidance of sludge incineration.

  4. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications.

    Science.gov (United States)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R(2) and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  5. Annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure applications

    Science.gov (United States)

    Li, Chuang; Cordovilla, Francisco; Ocaña, José L.

    2017-03-01

    A novel structural piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been proposed for low pressure measurements based on silicon substrate. In this study, a design method, including the model design, dimensions optimization, and performance prediction of the novel structure sensor, is presented. The finite element method has been used to analyze the stress distribution of sensitive elements and the deflection of membrane. On the basis of simulation results, the relationships between structural dimension variables and mechanical performance are deduced, which make the fabrication processes more efficient. According to statistics theory, the coefficient of determination R2 and residual sum of squares are introduced to indicate whether the fitting equations and curves match well with the simulation results. After that, a series of the optimal membrane dimensions are determined. Compared with other structural sensors, the optimized sensor achieves the best overall properties as it mitigates the contradiction between sensitivity and linearity. The reasons why the proposed sensor can maximize sensitivity and minimize nonlinearity are also discussed. By localizing more strain energy in the high concentrated stress profile and creating partially stiffened membrane, the proposed sensor has achieved a high sensitivity of 34.5 (mV/V)/psi and a low nonlinearity of 0.25% FSS. Thus, the proposed structure sensor will be a proper choice for low pressure applications less than 1 psi.

  6. Quantitative and sensitive analysis of CN molecules using laser induced low pressure He plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Idris, Nasrullah; Ramli, Muliadi [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, 10 Rawamangun, Jakarta 13220 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan Puspiptek, Serpong, Tangerang Selatan, 15314 Banten (Indonesia); Tjia, May On [Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia); Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Lie, Tjung Jie; Lie, Zener Sukra; Kurniawan, Davy Putra; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Kagawa, Kiichiro [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Fukui Science Education Academy, Takagi Chuou 2 choume, Fukui 910-0804 (Japan)

    2015-03-21

    We report the results of experimental study on CN 388.3 nm and C I 247.8 nm emission characteristics using 40 mJ laser irradiation with He and N{sub 2} ambient gases. The results obtained with N{sub 2} ambient gas show undesirable interference effect between the native CN emission and the emission of CN molecules arising from the recombination of native C ablated from the sample with the N dissociated from the ambient gas. This problem is overcome by the use of He ambient gas at low pressure of 2 kPa, which also offers the additional advantages of cleaner and stronger emission lines. The result of applying this favorable experimental condition to emission spectrochemical measurement of milk sample having various protein concentrations is shown to yield a close to linear calibration curve with near zero extrapolated intercept. Additionally, a low detection limit of 5 μg/g is found in this experiment, making it potentially applicable for quantitative and sensitive CN analysis. The visibility of laser induced breakdown spectroscopy with low pressure He gas is also demonstrated by the result of its application to spectrochemical analysis of fossil samples. Furthermore, with the use of CO{sub 2} ambient gas at 600 Pa mimicking the Mars atmosphere, this technique also shows promising applications to exploration in Mars.

  7. A 10-GHz Bandwidth Electroabsorption Modulated Laser by Ultra-Low-Pressure Selective Area Growth

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qian; PAN Jiao-Qing; ZHOU Fan; WANG Bao-Jun; WANG Lu-Feng; WANG Wei

    2005-01-01

    @@ A novel integration technique has been developed using band-gap energy control of InGaAsP/InGaAsP multi quantum-well (MQW) structures during simultaneous ultra-low-pressure (22 mbar) selective-area-growth (SAG)process in metal-organic chemical vapour deposition. A fundamental study of the controllability of band gap energy by the SAG method is performed. A large band-gap photoluminescence wavelength shift of 83nm is obtained with a small mask width variation (0-30μm). The method is then applied to fabricate an MQW distributed-feedback laser monolithically integrated with an electroabsorption modulator. The experimental results exhibit superior device characteristics with low threshold of 19 mA, over 24 dB extinction ratio when coupled into a single mode fibre. More than 10 GHz modulation bandwidth is also achieved, which demonstrates that the ultra-low-pressure SAG technique is a promising approach for high-speed transmission photonic integrated circuits.

  8. The role of thermal energy accommodation and atomic recombination probabilities in low pressure oxygen plasmas

    Science.gov (United States)

    Gibson, Andrew Robert; Foucher, Mickaël; Marinov, Daniil; Chabert, Pascal; Gans, Timo; Kushner, Mark J.; Booth, Jean-Paul

    2017-02-01

    Surface interaction probabilities are critical parameters that determine the behaviour of low pressure plasmas and so are crucial input parameters for plasma simulations that play a key role in determining their accuracy. However, these parameters are difficult to estimate without in situ measurements. In this work, the role of two prominent surface interaction probabilities, the atomic oxygen recombination coefficient γ O and the thermal energy accommodation coefficient α E in determining the plasma properties of low pressure inductively coupled oxygen plasmas are investigated using two-dimensional fluid-kinetic simulations. These plasmas are the type used for semiconductor processing. It was found that α E plays a crucial role in determining the neutral gas temperature and neutral gas density. Through this dependency, the value of α E also determines a range of other plasma properties such as the atomic oxygen density, the plasma potential, the electron temperature, and ion bombardment energy and neutral-to-ion flux ratio at the wafer holder. The main role of γ O is in determining the atomic oxygen density and flux to the wafer holder along with the neutral-to-ion flux ratio. It was found that the plasma properties are most sensitive to each coefficient when the value of the coefficient is small causing the losses of atomic oxygen and thermal energy to be surface interaction limited rather than transport limited.

  9. Combination of Low-pressure Steam Explosion and Alkaline Peroxide Pretreatment for Separation of Hemicellulose

    Directory of Open Access Journals (Sweden)

    Yang Xing

    2014-04-01

    Full Text Available Low-pressure steam explosion (LPSE combined with alkaline peroxide (AP pretreatment was first employed to separate hemicellulose from Lespedeza stalks. The monosaccharide composition and molecular weight distribution of the obtained hemicellulose fractions were characterized in this study. The results show that the hemicellulose extracted from Lespedeza stalks consisted of xylose, glucose, galactose, and mannose, which was a mixture of arabinoxylans and xyloglucans or β-glucans. The yield of hemicellulose fractions after AP pretreatment ranged from 11.2% (2.5% hydrogen peroxide (H2O2, w/v for 12 h to 12.2% (3.3% H2O2, w/v for 72 h. The molecular weight of hemicellulose decreased from 2,458 g/mol to 1,984 g/mol after AP pretreatment, indicating its degradation reaction. The structure of hemicellulose was analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and heteronuclear single quantum coherence. The AP pretreatment partially cleaved the backbone and the ether linkage between lignin and hemicelluloses. Also, branched-chain α-D-arabinofuranosyl in which β-D-xylose substituted at the C-3 position (monosubstituted was removed, illustrating a partial debranching reaction. Therefore, the combination of low-pressure steam explosion and alkaline peroxide pretreatment (LPSE-AP is an effective pretreatment method to separate hemicellulose from Lespedeza stalk.

  10. Electrical Properties for Capacitively Coupled Radio Frequency Discharges of Helium and Neon at Low Pressure

    Science.gov (United States)

    Tanisli, Murat; Sahin, Neslihan; Demir, Suleyman

    2016-10-01

    In this study, the symmetric radio frequency (RF) electrode discharge is formed between the two electrodes placing symmetric parallel. The electrical properties of symmetric capacitive RF discharge of pure neon and pure helium have been obtained from current and voltage waveforms. Calculations are done according to the homogeneous discharge model of capacitively coupled radio frequency (CCRF) using with the data in detail. Electrical properties of bulk plasma and sheath capacitance are also investigated at low pressure with this model. This study compares the electrical characteristics and sheath capacitance changes with RF power and pressure for helium and neon discharges. Also, the aim of the study is to see the differences between helium and neon discharges' current and voltage values. Their root-mean-square voltages and currents are obtained from Tektronix 3052C oscilloscope. Modified homogeneous discharge model of CCRF is used for low pressure discharges and the calculations are done using experimental results. It is seen that homogeneous discharge model of CCRF is usable with modification and then helium and neon discharge's electrical properties are investigated and presented with a comparison. Helium discharge's voltage and current characteristic have smaller values than neon's. It may be said that neon discharge is a better conductor than helium discharge. It is seen that the sheath capacitance is inversely correlation with sheath resistance.

  11. Determination of the cathode and anode voltage drops in high power low-pressure amalgam lamps

    Energy Technology Data Exchange (ETDEWEB)

    Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Vasiliev, A. I., E-mail: vasiliev@npo.lit.ru; Kostyuchenko, S. V.; Sokolov, D. V.; Startsev, A. Yu. [Joint Stock Company NPO LIT (Russian Federation); Kudryavtsev, N. N. [Moscow Institute of Physics and Technology (State University) (Russian Federation)

    2011-12-15

    For the first time, cathode and anode drops of powerful low-pressure amalgam lamps were measured. The lamp discharge current is 3.2 A, discharge current frequency is 43 kHz, linear electric power is 2.4 W/cm. The method of determination of a cathode drop is based on the change of a lamp operating voltage at variation of the electrode filament current at constant discharge current. The total (cathode plus anode) drop of voltage was measured by other, independent ways. The maximum cathode fall is 10.8 V; the anode fall corresponding to the maximal cathode fall is 2.4 V. It is shown that in powerful low pressure amalgam lamps the anode fall makes a considerable contribution (in certain cases, the basic one) to heating of electrodes. Therefore, the anode fall cannot be neglected, at design an electrode and ballast of amalgam lamps with operating discharge current frequency of tens of kHz.

  12. A 10-GHz Bandwidth Electroabsorption Modulated Laser by Ultra-Low-Pressure Selective Area Growth

    Science.gov (United States)

    Zhao, Qian; Pan, Jiao-Qing; Zhou, Fan; Wang, Bao-Jun; Wang, Lu-Feng; Wang, Wei

    2005-08-01

    A novel integration technique has been developed using band-gap energy control of InGaAsP/InGaAsP multi-quantum-well (MQW) structures during simultaneous ultra-low-pressure (22 mbar) selective-area-growth (SAG) process in metal-organic chemical vapour deposition. A fundamental study of the controllability of band gap energy by the SAG method is performed. A large band-gap photoluminescence wavelength shift of 83 nm is obtained with a small mask width variation (0-30 μm). The method is then applied to fabricate an MQW distributed-feedback laser monolithically integrated with an electroabsorption modulator. The experimental results exhibit superior device characteristics with low threshold of 19 mA, over 24 dB extinction ratio when coupled into a single mode fibre. More than 10 GHz modulation bandwidth is also achieved, which demonstrates that the ultra-low-pressure SAG technique is a promising approach for high-speed transmission photonic integrated circuits.

  13. Analisis Numerikal Frekuensi Natural Pada Poros Low Pressure Boiler Feed Pump PT.PJB UP Gresik

    Directory of Open Access Journals (Sweden)

    Muhammad Taufik Akbar Ofrial

    2017-03-01

    Full Text Available Low pressure boiler feed pump (LPBFP merupakan salah satu komponen penting dalam sistem Heat Recovery Steam Generator (HRSG, pada pengoperasiannya sering terjadi permasalahan yaitu patahnya poros yang dapat terjadi 8-10 kali dalam setahun yang mungkin disebabkan oleh faktor getaran. Untuk itu pada penelitian ini dilakukan perhitungan dengan pemodelan metode elemen hingga menggunakan software ANSYS untuk menghitung frekuensi natural dan modus getaran untuk 10 frekuensi natural pertama pada komponen LPBFP. Dari hasil simulasi didapatkan nilai yaitu untuk orde pertama sebesar 583,03 Hz, orde kedua sebesar 583,39 Hz, orde ketiga sebesar 2820,8 Hz, orde keempat sebesar 2849 Hz, orde kelima sebesar 3943,9 Hz, orde keenam sebesar 4079,6 Hz, orde ketujuh sebesar 5428,3 Hz, orde kedelapan sebesar 6111 Hz, orde kesembilan sebesar 6594 Hz, orde kesepuluh sebesar 6715 Hz. Sepuluh frekuensi natural menghasilkan lima jenis modus getaran yaitu lateral bending vibration, shear bending vibration, torsional bending vibration, axial bending vibration, torsional shear bending vibration. Dari kesepuluh frekuensi natural yang diperoleh semuanya menyebabkan kegagalan poros low pressure boiler feed pump.

  14. Development of a low-pressure materials pre-treatment process for improved energy efficiency

    Science.gov (United States)

    Lee, Kwanghee; You, Byung Don

    2017-09-01

    Low pressure materials pre-treatment process has been developed as an alternative to the existing high-temperature sludge drying, limestone calcination, and limonite dehydroxylation. Using the thermodynamic equilibrium relationship between temperature and pressure represented by the Clausius-Clapeyron equation, the operational temperature of these reactions could be lowered at reduced pressure for increased energy efficiency. For industrial sludge drying, the evaporation rate was controlled by interfacial kinetics showing a constant rate with time and significant acceleration in the reaction could be observed with reduced pressure. At this modified reaction rate under low pressure, the rate was also partially controlled by mass transfer. Temperature of limestone calcination was lowered, but the reaction was limited at the calculated equilibrium temperature of the Clausius-Clapeyron equation and slightly higher temperatures were required. The energy consumption during limestone calcination and limonite dehydroxylation were evaluated, where lower processing pressures could enhance the energy efficiency for limestone calcination, but limonite dehydroxylation could not achieve energy-savings due to the greater power consumption of the vacuum pump under lower pressure and reduced temperatures.

  15. Low-Pressure Pericardial Tamponade: Case Report and Review of the Literature.

    Science.gov (United States)

    Walsh, Brooks M; Tobias, Lauren A

    2017-04-01

    Focused cardiac ultrasound (FoCUS) is accurate for determining the presence of a pericardial effusion. Using FoCUS to evaluate for pericardial tamponade, however, is more involved. Many experts teach that tamponade is unlikely if the inferior vena cava (IVC) shows respiratory variation and is not distended. A 53-year-old woman presented to the emergency department (ED) with severe orthostatic hypotension, exertional dyspnea, and hypoxia. The evaluation did not reveal an acute cardiopulmonary etiology, but FoCUS demonstrated a pericardial effusion, with several signs consistent with tamponade. The IVC, however, was not distended. She was believed to be hypovolemic, but fluid therapy provided minimal benefit. The patient's condition improved only after aspiration of the effusion. The patient's presentation was likely a "low-pressure" pericardial tamponade. Patients with this subset of tamponade often do not have significant venous congestion, but urgent pericardial aspiration is still indicated. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Pericardial tamponade may not manifest with IVC plethora on ultrasound. Patients with low-pressure tamponade do not present with the most florid signs of tamponade, but they nonetheless fulfill diagnostic criteria for tamponade. If a non-plethoric IVC is used to rule out tamponade, the clinician risks delaying comprehensive echocardiography or other tests. Furthermore, the potential for deterioration to frank shock could be discounted, with inappropriate disposition and monitoring. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Inactivation differences of microorganisms by low pressure UV and pulsed xenon lamps.

    Science.gov (United States)

    Otaki, M; Okuda, A; Tajima, K; Iwasaki, T; Kinoshita, S; Ohgaki, S

    2003-01-01

    UV disinfection has been applied to water treatment in recent years with low-pressure and medium-pressure UV lamps mainly used as the light source. In general, UV disinfection is considered to be inefficient with water of high turbidity because of inhibition of light penetration. Additionally, photoreactivation may be a problem that should be considered in case a disinfected water is discharged to the environment where sunlight causes reactivation. Recently, other types of lamps have been proposed including a flush-type lamp (such as a pulsed-xenon lamp) that emits high energy and wide wavelength intermittently. In this study, the difference between inactivation efficiencies by low-pressure UV (LPUV) and pulsed-xenon (PXe) lamps was investigated using two coliphage types and three strains of Escherichia coli. PXe had a suppressive effect on photoreactivation rate of the E. coli strains even though there was no significant effect on inactivation rate and maximum survival ratio after photoreactivation. PXe also had a benefit when applied to high turbidity waters as no tailing phenomena were observed in the low survival ratio area although it was observed in LPUV inactivation. This efficiency difference was considered to be due to the difference in irradiated wavelength of both lamps.

  17. Physiological regulation of epithelial sodium channel by proteolysis

    DEFF Research Database (Denmark)

    Svenningsen, Per; Friis, Ulla G; Bistrup, Claus

    2011-01-01

    PURPOSE OF REVIEW: Activation of epithelial sodium channel (ENaC) by proteolysis appears to be relevant for day-to-day physiological regulation of channel activity in kidney and other epithelial tissues. Pathophysiogical, proteolytic activation of ENaC in kidney has been demonstrated in proteinuric...... disease. RECENT FINDINGS: A variation in sodium and potassium intake or plasma aldosterone changes the number of cleaved α and γ-ENaC subunits and is associated with changes in ENaC currents. The protease furin mediates intracellular cleavage, whereas the channel-activating protease prostasin (CAP-1...... opens the way for new understanding of the pathogenesis of proteinuric sodium retention, which may involve plasmin and present several potential new drug targets....

  18. Pressure estimation for diamond anvils cell under very-low pressures, hydrostatic conditions -evaluation for quartz Raman peak shifts-

    Science.gov (United States)

    Kubo, K.; Okamoto, K.

    2016-12-01

    Pressure shift of the ruby R1 luminescent shift has been used as primary pressure gauge in diamond-anvils experiments. However, the pressure calibration under low-pressure conditions (Ruby pressure gauge at 1 GPa.

  19. Gating system optimization of low pressure casting A356 aluminum alloy intake manifold based on numerical simulation

    National Research Council Canada - National Science Library

    Jiang Wenming Fan Zitian

    2014-01-01

    To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on filling and solidification processes of the casting was carried...

  20. Development and Commercial Application of Ultra-Low Pressure Naphtha Reforming Technology with Continuous Catalyst Regeneration

    Institute of Scientific and Technical Information of China (English)

    Ma Aizeng; Xu Youchun; Yang Dong; Zhang Xinkuan; Wang Jieguang

    2013-01-01

    The development history and major technological innovations of the ultra-low pressure naphtha reforming tech-nology with continuous catalyst regeneration in China were introduced. This technology had been adopted by the 1.0 Mt/a CCR unit at the Guangzhou Company. The appropriate catalyst was selected to meet the demand of the unit capacity, the feedstock, and the product slate. The design parameters, including the reaction pressure, the octane number of C5+ liquid product, the reaction temperature, the space velocity, the hydrogen/oil molar ratio, and the catalyst circulating rate, were chosen based on the study of process conditions and parameters. The commercial test results showed that the research oc-tane number of C5+ product reached 104 when the capacity of the CCR unit was 100% and 115% of the design value. The other technical targets attained or exceeded the expected value.

  1. Calibration of Relative Humidity Devices in Low-pressure, Low-temperature CO2 Environment

    Science.gov (United States)

    Genzer, Maria; Polkko, Jouni; Nikkanen, Timo; Hieta, Maria; Harri, Ari-Matti

    2017-04-01

    Calibration of relative humidity devices requires in minimum two humidity points - dry (0%RH) and (near)saturation (95-100%RH) - over the expected operational temperature and pressure range of the device. In terrestrial applications these are relatively easy to achieve using for example N2 gas as dry medium, and water vapor saturation chambers for producing saturation and intermediate humidity points. But for example in applications intended for meteorological measurements on Mars there is a need to achieve at least dry and saturation points in low-temperature, low-pressure CO2 environment. We have developed a custom-made, small, relatively low-cost calibration chamber able to produce both dry points and saturation points in Martian range pressure CO2, in temperatures down to -70°C. The system utilizes a commercially available temperature chamber for temperature control, vacuum vessels and pumps. The main pressure vessel with the devices under test inside is placed inside the temperature chamber, and the pressure inside is controlled by pumps and manual valves and monitored with a commercial pressure reference with calibration traceable to national standards. Air, CO2, or if needed another gas like N2, is used for filling the vessel until the desired pressure is achieved. Another pressure vessel with a dedicated pressure pump is used as the saturation chamber. This vessel is placed in the room outside the temperature chamber, partly filled with water and used for achieving saturated water vapor in room-temperature low-pressure environment. The saturation chamber is connected to the main pressure vessel via valves. In this system dry point, low-pressure CO2 environment is achieved by filling the main pressure vessel with dry CO2 gas until the desired pressure is achieved. A constant flow of gas is maintained with the pump and valves and monitored with the pressure reference. The saturation point is then achieved by adding some water vapor from the saturation

  2. Discrete element simulation of powder compaction in cold uniaxial pressing with low pressure

    Science.gov (United States)

    Rojek, Jerzy; Nosewicz, Szymon; Jurczak, Kamila; Chmielewski, Marcin; Bochenek, Kamil; Pietrzak, Katarzyna

    2016-11-01

    This paper presents numerical studies of powder compaction in cold uniaxial pressing. The powder compaction in this work is considered as an initial stage of a hot pressing process so it is realized with relatively low pressure (up to 50 MPa). Hence the attention has been focused on the densification mechanisms at this range of pressure and models suitable for these conditions. The discrete element method employing spherical particles has been used in the numerical studies. Numerical simulations have been performed for two different contact models—the elastic Hertz-Mindlin-Deresiewicz model and the plastic Storåkers model. Numerical results have been compared with the results of laboratory tests of the die compaction of the NiAl powder. Comparisons have shown that the discrete element method is capable to represent properly the densification mechanisms by the particle rearrangement and particle deformation.

  3. Transient evolution of solitary electron holes in low pressure laboratory plasma

    CERN Document Server

    Choudhary, Mangilal; Mukherjee, Subroto

    2015-01-01

    Solitary electrons holes (SEHs) are localized electrostatic positive potential structures in collisionless plasmas. These are vortex-like structures in the electron phase space. Its existence is cause of distortion of the electron distribution in the resonant region. These are explained theoretically first time by Schamel et.al [Phys. Scr. 20, 336 (1979) and Phys. Plasmas 19, 020501 (2012)]. Propagating solitary electron holes can also be formed in a laboratory plasma when a fast rising high positive voltage pulse is applied to a metallic electrode [Kar et. al., Phys. Plasmas 17, 102113 (2010)] immersed in a low pressure plasma. The temporal evolution of these structures can be studied by measuring the transient electron distribution function (EDF). In the present work, transient EDF is measured after formation of a solitary electron hole in nearly uniform, unmagnetized, and collisionless plasma for applied pulse width and, where and are applied pulse width and inverse of ion plasma frequency respectively. Fo...

  4. Fabrication of Planar Heterojunction Perovskite Solar Cells by Controlled Low-Pressure Vapor Annealing.

    Science.gov (United States)

    Li, Yanbo; Cooper, Jason K; Buonsanti, Raffaella; Giannini, Cinzia; Liu, Yi; Toma, Francesca M; Sharp, Ian D

    2015-02-05

    A new method for achieving high efficiency planar CH3NH3I3-xClx perovskite photovoltaics, based on a low pressure, reduced temperature vapor annealing is demonstrated. Heterojunction devices based on this hybrid halide perovskite exhibit a top PCE of 16.8%, reduced J-V hysteresis, and highly repeatable performance without need for a mesoporous or nanocrystalline metal oxide layer. Our findings demonstrate that large hysteresis is not an inherent feature of planar heterojunctions, and that efficient charge extraction can be achieved with uniform halide perovskite materials with desired composition. X-ray diffraction, valence band spectroscopy, and transient absorption measurements of these thin films reveal that structural modifications induced by chlorine clearly dominate over chemical and electronic doping effects, without affecting the Fermi level or photocarrier lifetime in the material.

  5. Natural Circulation Characteristics at Low-Pressure Conditions through PANDA Experiments and ATHLET Simulations

    Directory of Open Access Journals (Sweden)

    Domenico Paladino

    2008-01-01

    Full Text Available Natural circulation characteristics at low pressure/low power have been studied by performing experimental investigations and numerical simulations. The PANDA large-scale facility was used to provide valuable, high quality data on natural circulation characteristics as a function of several parameters and for a wide range of operating conditions. The new experimental data allow for testing and improving the capabilities of the thermal-hydraulic computer codes to be used for treating natural circulation loops in a range with increased attention. This paper presents a synthesis of a part of the results obtained within the EU-Project NACUSP “natural circulation and stability performance of boiling water reactors.” It does so by using the experimental results produced in PANDA and by showing some examples of numerical simulations performed with the thermal-hydraulic code ATHLET.

  6. Experimental testing of cooling by low pressure adsorption in a zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Redman, C.M.

    1985-01-01

    A small scale facility was designed, constructed, and utilized to test the use of zeolite adsorption of water vapor to augment chill storage in ice for conventional space cooling. The facility uses solar-derived energy, for the heat source and evaporatively chilled water for the heat sump. The product cooling uses sublimation of ice instead of melting. The ZCAT facility utilizes a heat pumping technique in which a water vapor adsorbent functions as the compressor and condenser. The design was based on use of 13X zeolite as the adsorber because of its high adsorbence at low pressures. However, it has been determined that other materials such as silica gel should give superior performance. While zeolite 13X holds more water in the pressure and temperature ranges of interest, silica gel cycles more water and has less residue water. Both points are very important in the design of an efficient and cost effective system.

  7. Numerical simulation and optimization of Al alloy cylinder body by low pressure die casting

    Directory of Open Access Journals (Sweden)

    Mi Guofa

    2008-05-01

    Full Text Available Shrinkage defects can be formed easily at Critical location during low pressure die casting (LPDC of aluminum alloy cylinder body. It has harmful effect on the products. Mold fi lling and solidifi cation process of a cylinder body was simulated by using of Z-CAST software. The casting method was improved based on the simulation results. In order to create effective feeding passage, the structure of casting was modifi ed by changing the location of strengthening ribs at the bottom, without causing any adverse effect on the part’s performance. Inserting copper billet at suitable location of the die is a valid way to create suitable solidifi cation sequence that is benefi cial to the feeding. Using these methods, the shrinkage defect was completely eliminated at the critical location.

  8. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

    Science.gov (United States)

    Azadi, Sam; Cohen, R. E.

    2016-08-01

    We studied the low-pressure (0-10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo and density functional theory (DFT) methods. We performed diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. Using density functional perturbation theory, we computed the phonon contributions to the free energies. Our DFT enthalpy-pressure phase diagrams indicate that the Pbca and P21/c structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature Pbca to P21/c phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations give 50.6 ± 0.5 kJ/mol for crystalline benzene lattice energy.

  9. Low pressure mediated enhancement of nanoparticle and macromolecule loading into porous silicon structures.

    Science.gov (United States)

    Leonard, Fransisca; Margulis-Goshen, Katrin; Liu, Xuewu; Srinivasan, Srimeenakshi; Magdassi, Shlomo; Godin, Biana

    2014-01-01

    Ensuring drug loading efficiency and consistency is one of the most critical stages in engineering drug delivery vectors based on porous materials. Here we propose a technique to significantly enhance the efficiency of loading by employing simple and widely available methods: applying low pressure with and without centrifugation. Our results point toward the advantages the proposed method over the passive loading, especially where the size difference of loaded materials and the pore size of the porous silicon particles is smaller, an increase up to 20-fold can be observed. The technique described in the study can be used for efficient and reproducible loading of porous materials with therapeutic molecules, nanoparticles and contrast imaging agents for biomedical application.

  10. Qualitative model of the operating mechanism of the protective coating for low pressure Hg lamps

    Energy Technology Data Exchange (ETDEWEB)

    Krasnochub, A V [DECO Ltd, PO Box 40, 141701 Dolgoprudnyi (Russian Federation); Vasiliev, A I [LIT Technology Ltd, Krasnobogatyrskaya 44, 107076 Moscow (Russian Federation)

    2006-04-07

    Interaction between the plasma and protective coating on the inner side of low pressure mercury lamp bulbs is considered. Under the assumption that the main way of decreasing the transmission of the bulb wall is the implantation of Hg ions within the fused quartz and formation of complexes [HgO] therein, a qualitative model of the attenuation mechanism is offered. The influence of the characteristics of a coating (thickness, close-packed structures, the lattice parameter, mass of atoms) on the transmission of the bulb walls is analysed. On the basis of the suggested model, estimates of the change in minimum transmission of bulb walls were made for lamps with and without protective coating. It is shown that in spite of approximations, the proposed model is in good agreement with experimental data.

  11. CATS, a low pressure multiwire proportional chamber for secondary beam tracking at GANIL

    CERN Document Server

    Ottini-Hustache, S; Auger, F; Musumarra, A; Alamanos, N; Cahan, B; Gillibert, A; Lagoyannis, A; Maillard, O; Pollacco, E; Sida, J L; Riallot, M

    1999-01-01

    A beam detector system, CATS (Chambre A Trajectoires de Saclay), was designed to provide event-by-event particle tracking in experiments with radioactive beams at GANIL. It consists of two low pressure multiwire proportional chambers with one plane of anode wires placed between two cathode planes (active area: 70x70 mm sup 2), respectively segmented into 28 vertical or horizontal strips (2.54 mm wide). The anode wires deliver a time signal allowing a time of flight measurement with an accuracy between 440 ps and 1.2 ns, depending on the energy loss of incident particles in the detector. The cathode strips are individually read out and the position of incoming particles is reconstructed using a charge centroid finding algorithm. A spatial resolution of 400 mu m (700 mu m) was achieved during in beam experiment, with a counting rate of 1.5x10 sup 5 (10 sup 6) particles per second. (author)

  12. Wastewater disinfection by low-pressure UV and ozone: a design approach based on water quality.

    Science.gov (United States)

    Savoye, P; Janex, M L; Lazarova, V

    2001-01-01

    Disinfection processes are known to be very sensitive to wastewater quality. This paper discusses the parameters that impact the UV light (UV) and ozone disinfection processes and the related mechanisms based on literature review. Low-pressure UV and ozone technologies were investigated on effluents that covered a wide range of water quality. The results are given in terms of design doses required to meet three major disinfection standards. Both processes were found eligible for the majority of effluents tested. Although cost-effectiveness is usually considered more favourable to UV, the ozone alternative should be examined in cases such as the disinfection of low-quality effluents or large treatment plants. Ozonation was also found capable of meeting the stringent Title 22 standard with no coagulation at a dose of 10 mg/l.

  13. Stress corrosion cracking in low-pressure turbine discs in an NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Itoh [Mitsubishi Heavy Industries, Ltd., Takasago Research and Development Center (Japan); Takashi, Momoo [Mitsubishi Heavy Industries, Ltd., Takasago Machinery Works (Japan)

    2001-07-01

    From past research, it is known that stress corrosion cracking in low-pressure turbine discs occurs in an environment near that of deaerated pure water. Nevertheless, in units with molar ratio control, there is a possibility of NaCl concentrating as an impurity in the dry/wet boundary region. Long-term immersion tests were conducted at 373 K to 473 K with the NaCl concentration predicted to become 5%. It was found that, when FeCl{sub 3} or other oxidizer was added, corrosion increased remarkably and SCC was initiated. When cracks were initiated, they were primarily transgranular; as the test temperature was decreased, initiation was accelerated but conversely crack propagation was reduced. (author)

  14. On designing low pressure loss working spaces for a planar Stirling micromachine

    Science.gov (United States)

    Hachey, M.-A.; Léveillé, É.; Fréchette, L. G.; Formosa, F.

    2015-12-01

    In this paper, research was undertaken with the objective to design low pressure loss working spaces for a Stirling cycle micro heat engine operating from low temperature waste heat. This planar free-piston heat engine is anticipated to operate at the kHz level with mm3 displacement. Given the resonant nature of the free-piston configuration, the complexity of its working gas’ flow geometry and its projected high operating frequency, flow analysis is relatively complex. Design considerations were thus based on fast prototyping and experimentation. Results show that geometrical features, such as a sharp 90° corner between the regenerator and working spaces, are strong contributors to pressure losses. This research culminated into a promising revised working space configuration for engine start-up, as it considerably reduced total pressure losses, more than 80% at Re = 700, from the original design.

  15. Plasma-photocatalyst interaction: Production of oxygen atoms in a low pressure discharge

    Science.gov (United States)

    Guaitella, O.; Gatilova, L.; Rousseau, A.

    2005-04-01

    A pulsed dc low pressure discharge in air (210 Pa) is used to study the mechanisms of activation of a photocatalytic material (TiO2) under plasma exposure. It is first shown that the presence of TiO2 inside the plasma region leads to a strong increase of the reduced electric field. Time resolved measurement of the atomic oxygen density is performed by actinometry during a 10 ms pulse at a low repetition rate (1 Hz) with and without TiO2 pellets inside the plasma region. The presence of TiO2 pellets strongly increases the O atom density during the first millisecond, but this effect saturates for longer exposure times.

  16. Dynamics of cathode spots in low-pressure arc plasma removing oxide layer on steel surfaces

    Science.gov (United States)

    Tang, Z. L.; Yang, K.; Liu, H. X.; Zhang, Y. C.; Li, H.; Zhu, X. D.

    2016-03-01

    The dynamics of cathode spots has been investigated in low-pressure arc plasma for removing oxide layer on low carbon steel surfaces. The motion of cathode spots was observed with a high speed camera, and the arc voltage was analyzed by fast Fourier transform. The spots move on clean steel surface as a random walk, and the low-frequency components dominated the voltage waveform. However, the spots on steel surfaces with oxide layer tend to burn on the rim of the eroded area formed in the previous arcing, and the low-frequency components decrease correspondingly. The "color" of the colored random noise for arc voltage varies from the approximate brown noise for clean steel surface to pink noise for thick oxide layer, where the edge effect of boundary is considered to play a significant role.

  17. Comparison measurements of low-pressure between a laser refractometer and ultrasonic manometer

    Science.gov (United States)

    Egan, Patrick F.; Stone, Jack A.; Ricker, Jacob E.; Hendricks, Jay H.

    2016-05-01

    We have developed a new low-pressure sensor which is based on the measurement of (nitrogen) gas refractivity inside a Fabry-Perot cavity. We compare pressure determinations via this laser refractometer to that of well-established ultrasonic manometers throughout the range 100 Pa to 180 000 Pa. The refractometer demonstrates 10-6 ṡ p reproducibility for p > 100 Pa, and this precision outperforms a manometer. We also claim the refractometer has an expanded uncertainty of U(pFP) = [(2.0 mPa)2 + (8.8 × 10-6 ṡ p)2]1/2, as realized through the properties of nitrogen gas; we argue that a transfer of the pascal to p < 1 kPa using a laser refractometer is more accurate than the current primary realization.

  18. Carbon foam derived from pitches modified with mineral acids by a low pressure foaming process

    Energy Technology Data Exchange (ETDEWEB)

    Tsyntsarski, B.; Petrova, B.; Budinova, T.; Petrov, N.; Krzesinska, M.; Pusz, S.; Majewska, J.; Tzvetkov, P. [Bulgarian Academy of Science, Sofia (Bulgaria). Inst. of Organic Chemistry

    2010-10-15

    Carbon foams with an anisotropic texture and high mechanical strength were produced using precursors obtained after thermo-oxidation treatment of commercial coal-tar pitch with H{sub 2}SO{sub 4} and HNO{sub 3}. The investigations of the relation between the properties of the precursor and the structure of obtained foam indicate, that the composition and softening point of the pitch precursor significantly affect the foaming process, foam structure and foam mechanical strength. The composition and properties of the modified pitches allow foam formation at relatively low pressure and fast heating rate during the foaming process without a stabilization treatment. The foaming process of pitch-based carbon foams, pretreatment of the precursors, and the properties of resultant foams are discussed in this paper.

  19. Time-zero fission-fragment detector based on low-pressure multiwire proportional chambers

    CERN Document Server

    Assamagan, Ketevi A; Bayatyan, G L; Carlini, R; Danagulyan, S; Eden, T; Egiyan, K; Ent, R; Fenker, H; Gan, L; Gasparian, A; Grigoryan, N K; Greenwood, Z; Gueye, P; Hashimoto, O; Johnston, K; Keppel, C; Knyazyan, S; Majewski, S; Margaryan, A; Margaryan, Yu L; Marikian, G G; Martoff, J; Mkrtchyan, H G; Parlakyan, L; Sato, Y; Sawafta, R; Simicevic, N; Tadevosyan, V; Takahashi, T; Tang, L; Vartanian, G S; Vulcan, W; Wells, S; Wood, S

    1999-01-01

    A time-zero fission fragment (FF) detector, based on the technique of low-pressure multiwire proportional chambers (LPMWPC), has been designed and constructed for the heavy hypernuclear lifetime experiment (E95-002) at Thomas Jefferson National Accelerator Facility. Its characteristics and the method of time-zero reconstruction were investigated using fission fragments from a sup 2 sup 5 sup 2 Cf spontaneous fission source. The influence of the ionization energy loss was also studied. It is shown that Heptane, Hexane, and Isobutane gases at a pressure of 1-2 Torr are all suitable for such a FF detector. As desired by experiment, a timing resolution of about 200 ps (FWHM) for a chamber size of 21x21 cm sup 2 was achieved.

  20. Low-pressure water vapour plasma treatment of surfaces for biomolecules decontamination

    Science.gov (United States)

    Fumagalli, F.; Kylián, O.; Amato, L.; Hanuš, J.; Rossi, F.

    2012-04-01

    Decontamination treatments of surfaces are performed on bacterial spores, albumin and brain homogenate used as models of biological contaminations in a low-pressure, inductively coupled plasma reactor operated with water-vapour-based gas mixtures. It is shown that removal of contamination can be achieved using pure H2O or Ar/H2O mixtures at low temperatures with removal rates comparable to oxygen-based mixtures. Particle fluxes (Ar+ ions, O and H atomic radicals and OH molecular radicals) from water vapour discharge are measured by optical emission spectroscopy and Langmuir probe under several operating conditions. Analysis of particle fluxes and removal rates measurements illustrates the role of ion bombardment associated with O radicals, governing the removal rates of organic matter. Auxiliary role of hydroxyl radicals is discussed on the basis of experimental data. The advantages of a water vapour plasma process are discussed for practical applications in medical devices decontamination.

  1. Monte Carlo Simulation of Laser-Ablated Particle Splitting Dynamic in a Low Pressure Inert Gas

    Science.gov (United States)

    Ding, Xuecheng; Zhang, Zicai; Liang, Weihua; Chu, Lizhi; Deng, Zechao; Wang, Yinglong

    2016-06-01

    A Monte Carlo simulation method with an instantaneous density dependent mean-free-path of the ablated particles and the Ar gas is developed for investigating the transport dynamics of the laser-ablated particles in a low pressure inert gas. The ablated-particle density and velocity distributions are analyzed. The force distributions acting on the ablated particles are investigated. The influence of the substrate on the ablated-particle velocity distribution and the force distribution acting on the ablated particles are discussed. The Monte Carlo simulation results approximately agree with the experimental data at the pressure of 8 Pa to 17 Pa. This is helpful to investigate the gas phase nucleation and growth mechanism of nanoparticles. supported by the Natural Science Foundation of Hebei Province, China (No. A2015201166) and the Natural Science Foundation of Hebei University, China (No. 2013-252)

  2. Pyrene measurements in sooting low pressure methane flames by jet-cooled laser-induced fluorescence.

    Science.gov (United States)

    Wartel, M; Pauwels, J-F; Desgroux, P; Mercier, X

    2011-12-15

    This paper presents in detail the study we carried out concerning the pyrene measurement by jet-cooled laser-induced fluorescence (JCLIF) in different sooting low pressure methane flames. The aim of this paper is both to demonstrate the potentialities of this technique for the measurement of such moderately sized polycyclic aromatic hydrocarbons under sooting flame conditions and to provide new experimental data for the understanding and the development of chemical models of the soot formation processes. Several concentration profiles of pyrene measured in different sooting flame (various pressure and equivalence ratio) are presented. The validation of the JCLIF method for pyrene measurements is explained in detail as well as the calibration procedure, based on the standard addition method, which has been implemented for the quantification of the concentration profiles. Sensitivity lower than 1 ppb was obtained for the measurement of this species under sooting flame conditions.

  3. Erosion study of final stage blading of low pressure steam turbines

    Science.gov (United States)

    Dehouve, J.; Nardin, P.; Zeghmati, M.

    1999-04-01

    In order to increase our knowledge of erosion phenomena, the Steam Turbine Groupe (STG) of ALSTOM has been using an erosion test facility in the C.R.T.V. (Centre de Recherche Turbines à Vapeur). This test facility simulates erosion in low pressure steam turbine cylinders in order to compare the erosion resistance of various blade materials (12% chromium steel, titanium alloys, etc.) and their protection (superficial hardening, coatings, etc.). This test facility also allows us to understand the mechanism causing damage at a macroscopic level (impact energy of the droplets and the loss of eroded volume) and at a microscopic level (residual stress and metallurgic analysis) and therefore to determine an evolution law of material surface damage. In this paper, the behaviour of the materials (12% chromium steel and titanium alloys), which has been analysed by image production measurement methods, will be presented according to different impact velocities.

  4. Performance and control study of a low-pressure-ratio turbojet engine for a drone aircraft

    Science.gov (United States)

    Seldner, K.; Geyser, L. C.; Gold, H.; Walker, D.; Burgner, G.

    1972-01-01

    The results of analog and digital computer studies of a low-pressure-ratio turbojet engine system for use in a drone vehicle are presented. The turbojet engine consists of a four-stage axial compressor, single-stage turbine, and a fixed area exhaust nozzle. Three simplified fuel schedules and a generalized parameter fuel control for the engine system are presented and evaluated. The evaluation is based on the performance of each schedule or control during engine acceleration from a windmill start at Mach 0.8 and 6100 meters to 100 percent corrected speed. It was found that, because of the higher acceleration margin permitted by the control, the generalized parameter control exhibited the best dynamic performance.

  5. Oxygen transport membrane based advanced power cycle with low pressure synthesis gas slip stream

    Energy Technology Data Exchange (ETDEWEB)

    Kromer, Brian R.; Litwin, Michael M.; Kelly, Sean M.

    2016-09-27

    A method and system for generating electrical power in which a high pressure synthesis gas stream generated in a gasifier is partially oxidized in an oxygen transport membrane based reactor, expanded and thereafter, is combusted in an oxygen transport membrane based boiler. A low pressure synthesis gas slip stream is split off downstream of the expanders and used as the source of fuel in the oxygen transport membrane based partial oxidation reactors to allow the oxygen transport membrane to operate at low fuel pressures with high fuel utilization. The combustion within the boiler generates heat to raise steam to in turn generate electricity by a generator coupled to a steam turbine. The resultant flue gas can be purified to produce a carbon dioxide product.

  6. The advantages of Low Pressure Carburizing in the Heat Treatment Subcontracting Business

    Institute of Scientific and Technical Information of China (English)

    Guy PRUNEL; Bruno STAUDER

    2004-01-01

    Low Pressure Carburizing (LPC) was introduced in the 90's in the western Europe Heat Treatment business,mainly for in-house applications where it was especially appreciated for carburizing of transmission parts. However the success of the LPC units installed for gears carburizing in the automotive industry has hindered the development of the process in other fields - like subcontracting business -, where its advantages deserve to be enlightened.After a brief review of the principle of the process, the interest of its classical application to transmission parts is described,underlining peculiarly the reduction of the distortion observed when LPC is associated with high pressure gas quenching.Then the less-known advantages of the LPC process, like the high accuracy and reproducibility of the results, the modeling possibility and the simulation easiness, the case-depth uniformity and the full flexibility of the units are considered,showing how they can be beneficial to subcontracting business.

  7. Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades

    Directory of Open Access Journals (Sweden)

    Li Yang

    2007-01-01

    Full Text Available This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP neural network and genetic algorithm (GA, the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.

  8. INTERNAL FLOW MECHANISM AND EXPERIMENTAL RESEARCH OF LOW PRESSURE AXIAL FAN WITH FORWARD-SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    LI Yang; LIU Jie; OUYANG Hua; DU Zhao-Hui

    2008-01-01

    This article presents the flow mechanism analysis and experimental study of a forward-skewed impeller and a radial impeller in low pressure axial fan. The forward-skewed blade was obtained by the optimization design of the radial blade and CFD technique. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the forward-skewed blade has demonstrated the improvements in efficiency, total pressure ratio, Stable Operating Range (SOR) and less aerodynamic noise. Detailed flow measurement and computation were performed for outlet flow field for investigating the responsible flow mechanisms. The results show the forward-skewed blade can cause a spanwise redistribution of flow toward the blade mid-span and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at mid-span.

  9. Low pressure phase diagram of CeCoGe{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mizoo, Masakazu; Nishioka, Takashi; Kato, Harukazu; Matsumura, Masahiro, E-mail: nisioka@kochi-u.ac.jp [Graduate School of Integrated Arts and Sciences, Kochi University, Kochi 780-8520 (Japan)

    2011-01-01

    We have performed measurements of the Hall magnetization and electrical resistivity on a pressure-induced antiferromagnetic heavy fermion superconductor CeCoGe{sub 3} at pressures up to {approx}1.7 GPa, which crystallizes in the tetragonal BaNiSn{sub 3}-type structure without inversion symmetry. We have clarified that five successive phase transitions appear at ambient pressure. As pressure is applied, these transitions approach one another until {approx}1.2 GPa, and then separate again. We have also found another phase transition emerges above {approx}0.5 GPa, which is consistent with a recent Co-NQR study. From these results, we propose a low pressure P-T phase diagram, which contains at least eight ordered phases below {approx}2 GPa. This phase diagram is consistent with a recent reported high pressure phase diagram.

  10. Turbulent kinetic energy balance measurements in the wake of a low-pressure turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Sideridis, A. [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Yakinthos, K., E-mail: kyros@eng.auth.g [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Goulas, A. [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2011-02-15

    The turbulent kinetic energy budget in the wake generated by a high lift, low-pressure two-dimensional blade cascade of the T106 profile was investigated experimentally using hot-wire anemometry. The purpose of this study is to examine the transport mechanism of the turbulent kinetic energy and provide validation data for turbulence modeling. Point measurements were conducted on a high spatial resolution, two-dimensional grid that allowed precise derivative calculations. Positioning of the probe was achieved using a high accuracy traversing mechanism. The turbulent kinetic energy (TKE) convection, production, viscous diffusion and turbulent diffusion were all obtained directly from experimental measurements. Dissipation and pressure diffusion were calculated indirectly using techniques presented and validated by previous investigators. Results for all terms of the turbulent kinetic energy budget are presented and discussed in detail in the present work.

  11. Propagation of light in low pressure ionised and atomic hydrogen. Application to astrophysics

    CERN Document Server

    Moret-Bailly, J

    2003-01-01

    The "Impulsive Stimulated Raman Scattering" (ISRS) performed using ultrashort laser pulses shifts the light frequencies. Tried using ordinary incoherent light, it keeps its qualitative properties except the nonlinearity due to the power of the laser pulses. The relative frequency shifts of the "Coherent Raman Effect on Incoherent Light" (CREIL) which is obtained do not depend on the intensity and, in a first approximation, on the frequency of the light. As CREIL does not blur the images and the spectra, its shifts may be confused with Doppler shifts. ISRS and CREIL are parametric effects which do not excite the matter, transferring energy from hot beams to cold beams; for CREIL, the cold light is thermal radiation which is heated. CREIL requires low pressure gases acting as catalysts. These gases must have Raman transitions in the radiofrequencies range: for instance H2+ or excited atomic hydrogen in a magnetic field. The spectral lines resulting from a simultaneous absorption (or emission) and CREIL have a w...

  12. Research and Evaluation for Passive Safety System in Low Pressure Reactor

    Directory of Open Access Journals (Sweden)

    Peng Chuanxin

    2015-01-01

    Full Text Available Low pressure reactor is a small size advanced reactor with power of 180 MWt, which is under development at Nuclear Power Institute of China. In order to assess the ability and feasibility of passive safety system, several tests have been implemented on the passive safety system (PSS test facility. During the LOCA and SBO accident, the adequate core cooling is provided by the performance of passive safety system. In addition the best-estimate thermal hydraulic code, CATHARE V2.1, has been assessed against cold leg LOCA test. The calculation results show that CATHARE is in a satisfactory agreement with the test for the steady state and transient test.

  13. Research program: The investigation of heat transfer and fluid flow at low pressure

    Science.gov (United States)

    El-Genk, M. S.; Philbin, J. S.; Foushee, F. C.

    1986-04-01

    This paper gives an overview of a multiyear joint research program being conducted at the University of New Mexico (UNM) with support from Sandia National Laboratories and GA Technologies. This research focuses on heat removal and fluid dynamics in flow regimes characterized by low pressure and low Reynolds number. The program was motivated by a desire to characterize and analyze cooling in a broad class of TRIGA-type reactors under: (1) typical operating conditions, (2) anticipated, new operating regimes, and (3) postulated accident conditions. It has also provided experimental verification of analytical tools used in design analysis. The paper includes descriptions of the UNM thermal-hydraulics test facility and the experimental test sections. During the first two years experiments were conducted using single, electrically heated rod in water and air annuli. This configuration provides an observable and serviceable simulation of a fuel rod and its coolant channel.

  14. Principles and practice of low pressure-expendable pattern casting process for magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    LI Ji-qiang; FAN Zi-tian; WU He-bao; DONG Xuan-pu; ZHANG Da-fu; HUANG Nai-yu

    2006-01-01

    A newly developed low-pressure expendable pattern casting (LP-EPC) process was introduced and its basic pnnciples or effect factors were further analyzed. According to theoretical calculation and experimental results, the major casting parameters that are of great and critical importance on the process include pressure and flux of filling gas, decomposition characteristic and density of foam pattern,thickness and permeability of coating, pouring temperature, vacuum degree and their combination. Most of casting defects can be effectively avoided by choosing the suitable parameters. The success achieved in pouring motor housing and exhaust manifold castings demonstrates the advantages of LP-EPC process in the production of high-complicated castings with high dimension accuracy.

  15. Numerical simulation and optimization of Al alloy cylinder body by low pressure die casting

    Institute of Scientific and Technical Information of China (English)

    Mi Guofa; Liu Yanlei; Zhao Hengtao; Fu Hengzhi

    2008-01-01

    Shrinkage defects can be formed easily at critical location during low pressure die casting(LPDC)of aluminum alloy cylinder body.It has harmful effect on the products.Mold filling and solidification process of a cylinder body was simulated by using of Z-CAST software.The casting method was Improved based on the simulation results.In order to create eriective feeding passage,the structure of casting was modified by changing the location of strengthening ribs at the bottom,without causing any adverse effect on the part's performance.Inserting copper billet at suitable Iocation of the die is a valid way to create suitable solidification sequence that is beneficial to the feeding.Using these methods.the shrinkage defect was completely eliminated at the critical location.

  16. Oxygen transport membrane based advanced power cycle with low pressure synthesis gas slip stream

    Science.gov (United States)

    Kromer, Brian R.; Litwin, Michael M.; Kelly, Sean M.

    2016-09-27

    A method and system for generating electrical power in which a high pressure synthesis gas stream generated in a gasifier is partially oxidized in an oxygen transport membrane based reactor, expanded and thereafter, is combusted in an oxygen transport membrane based boiler. A low pressure synthesis gas slip stream is split off downstream of the expanders and used as the source of fuel in the oxygen transport membrane based partial oxidation reactors to allow the oxygen transport membrane to operate at low fuel pressures with high fuel utilization. The combustion within the boiler generates heat to raise steam to in turn generate electricity by a generator coupled to a steam turbine. The resultant flue gas can be purified to produce a carbon dioxide product.

  17. The effects of plasma inhomogeneity on the nanoparticle coating in a low pressure plasma reactor

    Science.gov (United States)

    Pourali, N.; Foroutan, G.

    2015-10-01

    A self-consistent model is used to study the surface coating of a collection of charged nanoparticles trapped in the sheath region of a low pressure plasma reactor. The model consists of multi-fluid plasma sheath module, including nanoparticle dynamics, as well as the surface deposition and particle heating modules. The simulation results show that the mean particle radius increases with time and the nanoparticle size distribution is broadened. The mean radius is a linear function of time, while the variance exhibits a quadratic dependence. The broadening in size distribution is attributed to the spatial inhomogeneity of the deposition rate which in turn depends on the plasma inhomogeneity. The spatial inhomogeneity of the ions has strong impact on the broadening of the size distribution, as the ions contribute both in the nanoparticle charging and in direct film deposition. The distribution width also increases with increasing of the pressure, gas temperature, and the ambient temperature gradient.

  18. Development of water soluble binder systems for low pressure injection molding of alumina

    Energy Technology Data Exchange (ETDEWEB)

    Bakan, H.I.; Gunes, M. [TUBITAK-MRC Materials and Chemical Technologies Research Inst., Kocaeli (Turkey)

    2004-07-01

    Low pressure injection molding of alumina powder using a water-soluble binder system has been carried out successfully. The water-soluble based binder system consisted of poly (2-ethyl-2-oxaline), low density polyethylene and stearic acid. The critical powder loading of the binder-powder mixture was determined based on torque rheometry experiments. The rheological properties of the powder-binder mixture were investigated systematically. The binder system used provides satisfactory mixture stability, excellent mouldability and reasonably fast water leaching and thermal debinding rates. The water-soluble constituent, poly (2-ethyl-2-oxaline), was removed by leaching in convecting water at 60 C within 6 hour. The remaining binder constituents were thermally removed during heating to 450 C. Sintering of the parts was conducted at 1550 C for an hour in air. (orig.)

  19. Characterization of the large area plane-symmetric low-pressure DC glow discharge

    Science.gov (United States)

    Avtaeva, S.; Gorokhovsky, V.; Myers, S.; Robertson, S.; Shunko, E.; Zembower, Z.

    2016-10-01

    Electron density and temperature as well as nitrogen dissociation degree in the low-pressure (10-50 mTorr) large area plane-symmetric DC glow discharge in Ar-N2 mixtures are studied by probes and spectral methods. Electron density measured by a hairpin probe is in good agreement with that derived from the intensity ratio of the N2 2nd positive system bands IC , 1 - 3/IC , 0 - 2 and from the intensity ratio of argon ions and atom lines IArII/IArI, while Langmuir probe data provides slightly higher values of electron density. Electron density in the low-pressure DC glow discharge varies with the discharge conditions in the limits of 108-1010 cm- 3. The concept of electron temperature can be used in low-pressure glow discharges with reservations. The intensity ratio of (0-0) vibrational bands of N2 1st negative and 2nd positive systems I391.4/I337.1 exhibits the electron temperature of 1.5-2.5 eV when argon fraction in the mixture is higher than nitrogen fraction and this ratio quickly increases with nitrogen fraction up to 10 eV in pure nitrogen. The electron temperature calculated from Langmuir probe I-V characteristics assuming a Maxwellian EEDF, gives Te 0.3-0.4 eV. In-depth analysis of the EEDF using the second derivative of Langmuir probe I-V characteristics shows that in a low-pressure glow discharge the EEDF is non-Maxwellian. The EEDF has two populations of electrons: the main background non-Maxwellian population of ;cold; electrons with the mean electron energy of 0.3-0.4 eV and the small Maxwellian population of ;hot; electrons with the mean electron energy of 1.0-2.5 eV. Estimations show that with electron temperature lower than 1 eV the rate of the direct electron impact ionization of N2 is low and the main mechanism of N2 ionization becomes most likely Penning and associative ionization. In this case, assumptions of the intensity ratio IN2+ , 391/IN2 , 337 method are violated. In the glow discharge, N2 dissociation degree reaches about 7% with the argon

  20. Simulation of rarefied low pressure RF plasma flow around the sample

    Science.gov (United States)

    Zheltukhin, V. S.; Shemakhin, A. Yu

    2017-01-01

    The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 103 K, in the plasma jet is (3.2-10) • 102 K, the degree of ionization is 10-7-10-5, electron density is 1015-1019 m-3. For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out.

  1. Effects of feed solution chemistry on low pressure reverse osmosis filtration of cesium and strontium

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shiyuan, E-mail: dingshiyuan@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Yang, Yu, E-mail: yangyu@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Huang, Haiou, E-mail: huanghaiou@bnu.edu.cn [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Liu, Hengchen, E-mail: 799599501@qq.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Hou, Li-an, E-mail: houlian678@hotmail.com [State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, No. 19, Xinjiekouwai Street, Haidian District, Beijing 100875 (China); Xi’an High-Tech Institute, No. 2, Tongxin Street, Baqiao District, Xi’an 710025 (China)

    2015-08-30

    Highlights: • A low pressure spiral wound RO membrane can reject Cs and Sr efficiently. • The rejection of Cs and Sr is dependent on feed pH and co-existing ions. • Donnan exclusion and electrostatic interaction govern the rejection of Cs and Sr. • The differences of filtration mechanism were influenced by the size of ions. • Sr could strengthen the irreversible membrane fouling resistance with HA. - Abstract: The objective of this study was to identify the removal mechanisms of radionuclides by reverse osmosis (RO) membranes under conditions relevant to full-scale water treatment. For this purpose, the effects of feed solution chemistry on the removal of Cs and Sr by a low pressure RO system was investigated by systematically varying membrane surface charge, ionic composition, and organic matter concentrations. The results showed that the effects of solution chemistry on the filtration of Cs and Sr were related to their hydrated ionic radius, resulting in the predominance of the Donnan’s effect and electrostatic interactions, respectively. Consequently, the rejection of Cs increased more pronouncedly than Sr with the increases of feed concentration. Due to the Donnan’s effect, different anions decreased the rejection of Cs to different extents in accordance to the order of anions’ radii as SO{sub 4}{sup 2−} > Cl{sup −} > NO{sub 3}{sup −} > F{sup −}. The variations in Sr rejection were influenced by the electrostatic interactions between Sr{sup 2+} and the membrane. In addition, humic acid (HA) lowered the rejection of Cs and caused significant membrane flux decline, but did not change the rejection of Sr. Sr also aggravated HA fouling of the membrane.

  2. Effects of Alternate Leading Edge Cutback on the Space Shuttle Main Engine Low Pressure Fuel Pump

    Science.gov (United States)

    Mulder, Andrew; Skelley, Stephen

    2016-01-01

    A higher order cavitation oscillation observed in the SSME low pressure fuel pump has been eliminated in water flow testing of a modified subscale replica of the inducer. The low pressure pump was modified by removing the outboard sections of two opposing blades of the four-bladed inducer, blending the "cutback" regions into the blades at the leading edge and tip, and removing material on the suction sides to decrease the exposed leading edge thickness. The leading edge tips of the cutback blades were moved approximately 25 degrees from their previous locations, thereby increasing one blade to blade spacing, decreasing the second, while simultaneously moving the cutback tips downstream. The test was conducted in MSFC's inducer test loop at scaled operating conditions in degassed and filtered water. In addition to eliminating HOC across the entire scaled operating regime, rotating cavitation was suppressed while the range of both alternate blade and asymmetric cavitation were increased. These latter phenomena, and more significantly, the shifts between these cavitation modes also resulted in significant changes to the head coefficient at low cavitation numbers. Reverse flow was detected at a slightly larger flow coefficient with the cutback inducer and suction capability was reduced by approximately 1 velocity head at and above approximately 90% of the reference flow coefficient. These performance changes along with more intense reverse flow are consistent with poor flow area management and increased incidence in the cutback region. Although the test demonstrated that the inducer modification was successful at eliminating the higher order cavitation across the entire scaled operating regime, different, previously unobserved, cavitation oscillations were introduced and significant performance penalties were imposed.

  3. The inhibitory role of sympathetic nervous system in the Ca2+-dependent proteolysis of skeletal muscle

    Directory of Open Access Journals (Sweden)

    L.C.C. Navegantes

    2009-01-01

    Full Text Available Mammalian cells contain several proteolytic systems to carry out the degradative processes and complex regulatory mechanisms to prevent excessive protein breakdown. Among these systems, the Ca2+-activated proteolytic system involves the cysteine proteases denoted calpains, and their inhibitor, calpastatin. Despite the rapid progress in molecular research on calpains and calpastatin, the physiological role and regulatory mechanisms of these proteins remain obscure. Interest in the adrenergic effect on Ca2+-dependent proteolysis has been stimulated by the finding that the administration of β2-agonists induces muscle hypertrophy and prevents the loss of muscle mass in a variety of pathologic conditions in which calpains are activated. This review summarizes evidence indicating that the sympathetic nervous system produces anabolic, protein-sparing effects on skeletal muscle protein metabolism. Studies are reviewed, which indicate that epinephrine secreted by the adrenal medulla and norepinephrine released from adrenergic terminals have inhibitory effects on Ca2+-dependent protein degradation, mainly in oxidative muscles, by increasing calpastatin levels. Evidence is also presented that this antiproteolytic effect, which occurs under both basal conditions and in stress situations, seems to be mediated by β2- and β3-adrenoceptors and cAMP-dependent pathways. The understanding of the precise mechanisms by which catecholamines promote muscle anabolic effects may have therapeutic value for the treatment of muscle-wasting conditions and may enhance muscle growth in farm species for economic and nutritional purposes.

  4. Continuous fast Fourier transforms cyclic voltammetry as a new approach for investigation of skim milk k-casein proteolysis, a comparative study.

    Science.gov (United States)

    Shayeh, Javad Shabani; Sefidbakht, Yahya; Siadat, Seyed Omid Ranaei; Niknam, Kaveh

    2017-10-01

    Cheese production is relied upon the action of Rennet on the casein micelles of milk. Chymosin assay methods are usually time consuming and offline. Herein, we report a new electrochemical technique for studying the proteolysis of K-casein. The interaction of rennet and its substrate was studied by fast Fourier transform continuous cyclic voltammetry (FFTCCV) based on a determination of k-casein in aqueous solution. FFTCCV technique is a very useful method for studying the enzymatic procedures. Fast response, no need of modified electrodes or complex equipment is some of FFTCCV advantages. Various concentrations of enzyme and substrate were selected and the increase in the appearance of charged species in solution as a result of the addition of rennet was studied. Data obtained using FFTCCV technique were also confirmed by turbidity analysis. The results show that rennet proteolysis activity occurs in much shorter time scales compare with its aggregation. Hence, following the appearance of charged segments as a result of proteolysis could be under consideration as a rapid and online method. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Primary proteolysis of white brined goat cheese monitored by high molarity Tris buffer SDS- PAGE system

    National Research Council Canada - National Science Library

    Milenko Smiljanić; Mirjana B. Pešić; Miroljub B. Barać; Sladjana P. Stanojević; Snežana T. Jovanović; Ognjen D. Maćej

    2013-01-01

    The aim of this work was to investigate primary proteolysis of white brined goat cheese prepared from raw milk and to correlate with the results obtained with high-molarity Tris buffer electrophoretic system...

  6. Sarcomere length influences u-calpain mediated proteolysis of troponin-T

    Science.gov (United States)

    Muscle shortening and postmortem proteolysis are well established as mechanisms controlling beef tenderness. Inherent myofibril structure and the extent of overlap between myosin and actin filaments are hypothesized to affect the availability of substrates for degradation by calpains. The objective ...

  7. Effect of Surface Treatment by Cathode Spot of Low Pressure Arc on Bonding Strength of Spraying Film by APPS

    Science.gov (United States)

    Hara, Masayuki; Ogura, Hirosi; Maezono, Satoru; Kubo, Yuya; Iwao, Toru; Tobe, Shogo; Inaba, Tsuginori

    Cathode spots of a low pressure arc can remove the oxide layer and evaporate impurities on the metal surface. The removal of the oxide layer by using the cathode spots in the low pressure is expected to solve the serious problems of the chemical and mechanical cleaning methods. The phenomena of the cathode spots in the low pressure for pre-treatment of Atmospheric Pressure Plasma Spray (APPS) have been investigated. In this paper, the surface shape of oxide work pieces was treated by using the cathode spots in the low pressure arc then compared with the grit-blasted surface. As a result, it is possible to improve the bonding strength of the spray deposit by making arithmetical mean height Ra large and average length of outline curve element Rsm small. Cathode spots of a low-pressure arc can be used for pre-treatment of APPS as the alternative technology of the blast. it is possible to obtain Ra larger an Rsm smaller than the blast only by cathode spots after the blast. But the treatment must be restricted not to destroy projection ones which were formed with melting.

  8. Effects of temperature and exposure time on mortality of stored-product insects exposed to low pressure.

    Science.gov (United States)

    Mbata, G N; Phillips, T W

    2001-10-01

    The prospects of using low pressure that creates a low-oxygen atmosphere to control stored-product insects were investigated in the laboratory. Eggs, larvae, and pupae of Tribolium castaneum (Herbst), Plodia interpunctella (Hübner), and Rhyzopertha dominica (F.) were exposed to 32.5 mmHg in glass chambers at 25, 33, 37, and 40 degrees C for times ranging from 30 min to 144 h. Time-mortality data were subjected to probit analyses and lethal dose ratios were computed to determine differences in lethal time (LT) values among all species-life stage combinations across the four temperatures. Eggs of each species were the life stage most tolerant to low pressure. Pupae of T. castaneum and R. dominica were more tolerant to low pressure than larvae. In all life stages, mortality increased with increasing exposure time to low pressure and also with increasing temperature. Immature stages of R. dominica were more tolerant to low pressure than immature stages of the other two species. The LT99 for R. dominica eggs was 176.32 h at 25 degrees C and that for P. interpunctella eggs was 28.35 h at the same temperature. An increase in temperature to 33 degrees C resulted in a LT99 phosphine for controlling pests of stored-products or other commodities.

  9. Bulk characterization of pharmaceutical powders by low-pressure compression II: effect of method settings and particle size.

    Science.gov (United States)

    Sørensen, Arne Hagsten; Sonnergaard, Jørn Møller; Hovgaard, Lars

    2006-01-01

    The aim of the present study was to investigate the effect of punch and die diameter, sample size, compression speed, and particle size on two low-pressure compression-derived parameters; the compressed density and the Walker w parameter. The excellent repeatability of the low-pressure compression method allowed small effects of variations in punch and die diameter and sample size to be demonstrated on a high significance level. Changing the compression speed, however, did not cause a significant effect in the compressed density, whereas a decrease in w was seen. The effect of particle size was studied by compressing and tapping different grades of calcium carbonate, lactose, and microcrystalline cellulose. The low-pressure compression-derived parameters were compared to tapped densities and to Compressibility Indexes obtained by tapping volumetry. Even though the relationship between particle size and the low-pressure compression-derived parameters appeared to be more complicated, a similar trend was observed. It was concluded that the low-pressure compression method provides a useful alternative to the more sample-consuming methods providing flow-related information.

  10. A comparison of low-pressure and supercharged operation of polymer electrolyte membrane fuel cell systems for aircraft applications

    Science.gov (United States)

    Werner, C.; Preiß, G.; Gores, F.; Griebenow, M.; Heitmann, S.

    2016-08-01

    Multifunctional fuel cell systems are competitive solutions aboard future generations of civil aircraft concerning energy consumption, environmental issues, and safety reasons. The present study compares low-pressure and supercharged operation of polymer electrolyte membrane fuel cells with respect to performance and efficiency criteria. This is motivated by the challenge of pressure-dependent fuel cell operation aboard aircraft with cabin pressure varying with operating altitude. Experimental investigations of low-pressure fuel cell operation use model-based design of experiments and are complemented by numerical investigations concerning supercharged fuel cell operation. It is demonstrated that a low-pressure operation is feasible with the fuel cell device under test, but that its range of stable operation changes between both operating modes. Including an external compressor, it can be shown that the power demand for supercharging the fuel cell is about the same as the loss in power output of the fuel cell due to low-pressure operation. Furthermore, the supercharged fuel cell operation appears to be more sensitive with respect to variations in the considered independent operating parameters load requirement, cathode stoichiometric ratio, and cooling temperature. The results indicate that a pressure-dependent self-humidification control might be able to exploit the potential of low-pressure fuel cell operation for aircraft applications to the best advantage.

  11. Imaging Proteolysis by Living Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Mansoureh Sameni

    2000-01-01

    Full Text Available Malignant progression is accompanied by degradation of extracellular matrix proteins. Here we describe a novel confocal assay in which we can observe proteolysis by living human breast cancer cells (BT20 and BT549 through the use of quenchedfluorescent protein substrates. Degradation thus was imaged, by confocal optical sectioning, as an accumulation of fluorescent products. With the BT20 cells, fluorescence was localized to pericellular focal areas that coincide with pits in the underlying matrix. In contrast, fluorescence was localized to intracellular vesicles in the BT549 cells, vesicles that also label for lysosomal markers. Neither intracellular nor pericellular fluorescence was observed in the BT549 cells in the presence of cytochalasin B, suggesting that degradation occurred intracellularly and was dependent on endocytic uptake of substrate. In the presence of a cathepsin 13-selective cysteine protease inhibitor, intracellular fluorescence was decreased ~90% and pericellular fluorescence decreased 67% to 96%, depending on the protein substrate. Matrix metallo protease inhibitors reduced pericellular fluorescence ~50%, i.e., comparably to a serine and a broad spectrum cysteine protease inhibitor. Our results suggest that: 1 a proteolytic cascade participates in pericellular digestion of matrix proteins by living human breast cancer cells, and 2 the cysteine protease cathepsin B participates in both pericellular and intracellular digestion of matrix proteins by living human breast cancer cells.

  12. Proteolysis of specific porcine zona pellucida glycoproteins by boar acrosin.

    Science.gov (United States)

    Dunbar, B S; Dudkiewicz, A B; Bundman, D S

    1985-04-01

    The morphologic and biochemical effects on the structure and constituent glycoproteins of the zona pellucida (ZP) by a specific sperm enzyme, acrosin, and a nonsperm enzyme, trypsin, have been evaluated. Intact porcine ZP matricies, exposed to either acrosin or trypsin, were analyzed microscopically. Changes in specific glycoproteins were monitored by high-resolution two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and the silver-based color stain, GELCODE. Although these enzymes did not alter the macroscopic properties of the ZP matrix, the 2D-PAGE ZP protein patterns were markedly altered. The high molecular weight glycoprotein families (II and III) were sensitive to proteolytic digestion, whereas the major glycoprotein family (I) of the porcine zona was only partially proteolyzed by acrosin and trypsin. Furthermore, it was demonstrated that acrosin had unique substrate specificity compared to that of trypsin, since the ZP peptide patterns were found to be different. These studies are the first to demonstrate which integral glycoproteins of the native porcine ZP matrix are specifically proteolyzed by acrosin from the homologous species and that this proteolysis occurs without the dissolution of the native porcine matrix.

  13. Altered balance between proteolysis and antiproteolysis in oncohematologic diseases

    Directory of Open Access Journals (Sweden)

    O. E. Shaul’ska

    2015-03-01

    Full Text Available Destruction of malignant cell clones and search for markers of the effectiveness of chemotherapy in patients with hematologic malignancies is an urgent direction of research. The purpose of this paper was to study plasma of patients with various forms of blood tumor, the activity of trypsin-like enzymes, matrix metalloproteinases MMP2 and MMP9, content of α1-proteinase inhibitor and α2-macroglobulin before and after the cytotoxic therapy by anthracycline antibiotics, doxorubicin and daunorubicin. It was established that concentration of inhibitors and activity of trypsin-like enzymes increased in patients with acute myeloid leukemia and multiple myeloma against the backdrop of multidirectional changes of proMMP9. Activity of the latter enzyme was reduced to 0,03±0,01 rel. u. in acute myeloid leukemia, and after chemotherapy it increased 7 times. Reducing level of inhibitors and increasing activity of MMP9 were found in chronic lymphocytic leukemia. The presence of the correlation between the α2-macroglobulin and gelatinase activity in the treatment indicates that the inhibitor is an important mechanism for storing of gelatinоlytic potential. Balance between proteolysis and antiproteolysis depends on the type of proliferating cells and the course of the disease. Indicators of tissue destruction may be an additional criterion for monitoring the stage of blood tumors and efficacy of treatment.

  14. Proteolysis of truncated hemolysin A yields a stable dimerization interface

    Energy Technology Data Exchange (ETDEWEB)

    Novak, Walter R.P.; Bhattacharyya, Basudeb; Grilley, Daniel P.; Weaver, Todd M. (Wabash); (UW)

    2017-02-21

    Wild-type and variant forms of HpmA265 (truncated hemolysin A) fromProteus mirabilisreveal a right-handed, parallel β-helix capped and flanked by segments of antiparallel β-strands. The low-salt crystal structures form a dimeric structureviathe implementation of on-edge main-chain hydrogen bonds donated by residues 243–263 of adjacent monomers. Surprisingly, in the high-salt structures of two variants, Y134A and Q125A-Y134A, a new dimeric interface is formedviamain-chain hydrogen bonds donated by residues 203–215 of adjacent monomers, and a previously unobserved tetramer is formed. In addition, an eight-stranded antiparallel β-sheet is formed from the flap regions of crystallographically related monomers in the high-salt structures. This new interface is possible owing to additional proteolysis of these variants after Tyr240. The interface formed in the high-salt crystal forms of hemolysin A variants may mimic the on-edge β-strand positioning used in template-assisted hemolytic activity.

  15. Global Identification of Biofilm-Specific Proteolysis in Candida albicans

    Directory of Open Access Journals (Sweden)

    Michael B. Winter

    2016-09-01

    Full Text Available Candida albicans is a fungal species that is part of the normal human microbiota and also an opportunistic pathogen capable of causing mucosal and systemic infections. C. albicans cells proliferate in a planktonic (suspension state, but they also form biofilms, organized and tightly packed communities of cells attached to a solid surface. Biofilms colonize many niches of the human body and persist on implanted medical devices, where they are a major source of new C. albicans infections. Here, we used an unbiased and global substrate-profiling approach to discover proteolytic activities produced specifically by C. albicans biofilms, compared to planktonic cells, with the goal of identifying potential biofilm-specific diagnostic markers and targets for therapeutic intervention. This activity-based profiling approach, coupled with proteomics, identified Sap5 (Candidapepsin-5 and Sap6 (Candidapepsin-6 as major biofilm-specific proteases secreted by C. albicans. Fluorogenic peptide substrates with selectivity for Sap5 or Sap6 confirmed that their activities are highly upregulated in C. albicans biofilms; we also show that these activities are upregulated in other Candida clade pathogens. Deletion of the SAP5 and SAP6 genes in C. albicans compromised biofilm development in vitro in standard biofilm assays and in vivo in a rat central venous catheter biofilm model. This work establishes secreted proteolysis as a promising enzymatic marker and potential therapeutic target for Candida biofilm formation.

  16. 低压洗涤塔在尿素装置低压尾气回收中的应用%Application of low-pressure scrubber in low-pressure exhaust gas recycling of urea plant

    Institute of Scientific and Technical Information of China (English)

    侯立志

    2014-01-01

    简要介绍二氧化碳汽提尿素装置低压回收工序采用低压洗涤塔工艺,有效降低了尾气中氨、二氧化碳的排放,大大降低了生产成本。%The paper briefly introduces low-pressure scrubber process in low-pressure exhaust gas recycling of CO2 stripping urea plant,reducing ammonia and carbon dioxide emissions effectively in tail gas,and reducing the cost of production greatly.

  17. Microwave air plasmas in capillaries at low pressure II. Experimental investigation

    Science.gov (United States)

    Stancu, G. D.; Leroy, O.; Coche, P.; Gadonna, K.; Guerra, V.; Minea, T.; Alves, L. L.

    2016-11-01

    This work presents an experimental study of microwave (2.45 GHz excitation frequency) micro-plasmas, generated in dry air (N2 80%: O2 20%) within a small radius silica capillary (345 µm inner radius) at low pressure (300 Pa) and low powers (80-130 W). Experimental diagnostics are performed using optical emission spectroscopy calibrated in absolute intensity. Axial-resolved measurements (50 µm spatial resolution) of atomic transitions N(3p4S)  →  N(3s4P) O(3p5P)  →  O(3s5S) and molecular transitions N2(C,v‧)  →  N2(B,v″) \\text{N}2+ (B,v‧)  →  \\text{N}2+ (X,v″) allow us to obtain, as a function of the coupled power, the absolute densities of N(3p4S), O(3p5P), N2(C), N2(B) and \\text{N}2+ (B), as well as the gas (rotational) temperature (700-1000 K), the vibrational temperature of N2(C,v) (7000-10 000 K) and the excitation temperatures of N2(C) and N2(B) (11 000 K). The analysis of the H β line-width gives an upper limiting value of 1013 cm-3 for the electron density; its axial variation (4  ×  1011-6  ×  1012 cm-3) being estimated by solving the wave electrodynamics equations for the present geometry, plasma length and electron-neutral collision frequency. The experimental results were compared with the results from a 0D model, presented in companion paper I [1], which couples the system of rate balance equations for the dominant neutral and charged plasma species to the homogeneous two-term electron Boltzmann equation, taking the measured gas temperature and the estimated electron density as input parameters. Good qualitative agreement is found between the measurements and calculations of the local species densities for various powers and axial positions. The dissociation degree of oxygen is found above 10%. Moreover, both the measurements and calculations show evidence of the non-equilibrium behavior of low-temperature plasmas, with vibrational and excitation temperatures at least

  18. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    Science.gov (United States)

    Fleetwood, James D.

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these processes, while compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during deposition. In the work reported, sub-micron 8 mole % Y2O3-ZrO2 (YSZ) and gadolinia-doped ceria (GDC), powders, including those in suspension with scandium-nitrate dopants, were deposited on NiO-YSZ anodes, via very low pressure suspension plasma spray (VLPSPS) at Sandia National Laboratories' Thermal Spray Research Laboratory and electrophoretic deposition (EPD) at Purdue University. Plasma spray was carried out in a chamber held at 320 - 1300 Pa, with the plasma composed of argon, hydrogen, and helium. EPD was characterized utilizing constant current deposition at 10 mm electrode separation, with deposits sintered from 1300 -- 1500 °C for 2 hours. The role of suspension constituents in EPD was analyzed based on a parametric study of powder loading, powder specific surface area, polyvinyl butyral (PVB) content, polyethyleneimine (PEI) content, and acetic acid content. Increasing PVB content and reduction of particle specific surface area were found to eliminate the formation of cracks when drying. PEI and acetic acid content were used to control suspension stability and the adhesion of deposits. Additionally, EPD was used to fabricate YSZ/GDC bilayer electrolyte systems. The resultant YSZ electrolytes were 2-27 microns thick and up to 97% dense. Electrolyte performance as part of a SOFC system with screen printed LSCF cathodes was evaluated with peak

  19. Physical Insights, Steady Aerodynamic Effects, and a Design Tool for Low-Pressure Turbine Flutter

    Science.gov (United States)

    Waite, Joshua Joseph

    The successful, efficient, and safe turbine design requires a thorough understanding of the underlying physical phenomena. This research investigates the physical understanding and parameters highly correlated to flutter, an aeroelastic instability prevalent among low pressure turbine (LPT) blades in both aircraft engines and power turbines. The modern way of determining whether a certain cascade of LPT blades is susceptible to flutter is through time-expensive computational fluid dynamics (CFD) codes. These codes converge to solution satisfying the Eulerian conservation equations subject to the boundary conditions of a nodal domain consisting fluid and solid wall particles. Most detailed CFD codes are accompanied by cryptic turbulence models, meticulous grid constructions, and elegant boundary condition enforcements all with one goal in mind: determine the sign (and therefore stability) of the aerodynamic damping. The main question being asked by the aeroelastician, "is it positive or negative?'' This type of thought-process eventually gives rise to a black-box effect, leaving physical understanding behind. Therefore, the first part of this research aims to understand and reveal the physics behind LPT flutter in addition to several related topics including acoustic resonance effects. A percentage of this initial numerical investigation is completed using an influence coefficient approach to study the variation the work-per-cycle contributions of neighboring cascade blades to a reference airfoil. The second part of this research introduces new discoveries regarding the relationship between steady aerodynamic loading and negative aerodynamic damping. Using validated CFD codes as computational wind tunnels, a multitude of low-pressure turbine flutter parameters, such as reduced frequency, mode shape, and interblade phase angle, will be scrutinized across various airfoil geometries and steady operating conditions to reach new design guidelines regarding the influence

  20. Primary proteolysis of white brined goat cheese monitored by high molarity Tris buffer SDS- PAGE system

    Directory of Open Access Journals (Sweden)

    Milenko Smiljanić

    2013-08-01

    Full Text Available The aim of this work was to investigate primary proteolysis of white brined goat cheese prepared from raw milk and to correlate with the results obtained with high-molarity Tris buffer electrophoretic system. Proteolytic changes of white brined cheese were monitored by three parameters, the total protein, the water soluble proteins and the degree of proteolysis, whereas the change of major casein fractions was followed by electrophoresis in reducing conditions. Ripening caused a decrease of the total protein content, whereas in the first forty days the water soluble protein and the degree of proteolysis increased. Both casein fractions (αs- and β-casein of goat cheese were susceptible to primary proteolysis but to the different extent. αs1- casein disappeared during processing, whereas during 60-days of ripening the content of αs2 and β-casein was reduced by 38.90 %, and 30.72 %, respectively. Such trends of major casein fractions were strongly correlated with the degree of proteolysis and the moisture content, whereas no correlation was found between them and the water soluble protein content. The results of our investigation clearly suggested that SDS-PAGE method based on high-molarity Tris-buffer system could be a very useful for purposes of monitoring the white goat cheese proteolysis.

  1. Microstructures of GaN Buffer Layers Grown on Si(111) Using Rapic Thermal Process Low-Pressure Metalorganic Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    CHEN Peng; ZHENG You-Dou; JIANG Shu-Sheng; FENG Duan; Z. C. Huang; SHEN Bo; ZHU Jian-Min; CHEN Zhi-Zhong; ZHOU Yu-Gang; XIE Shi-Yong; ZHANG Rong; HAN Ping; GU Shu-Lin

    2000-01-01

    Microstructures of GaN buffer layers grown on Si (111) substrates using rapid thermal process low-pressure metalorganic chemical vapor deposition are investigated by an atomic force microscope (AFM) and a high resolution transmission electron microscope (HRTEM). AFM images show that the islands appear in the GaN buffer layer after annealing at high temperature. Cross-sectional HRTEM micrographs of the buffer region of these samples indicate that there are bunched steps on the surface of the Si substrate and a lot of domains in GaN misorienting each other with small angles. The boundaries of those dowains locate near the bunched steps,and the regions of the film on a terrace between steps have the same crystal orientation. An amorphous-like layer, about 3 nm thick, can also be observed between the GaN buffer layer and the Si substrate.

  2. Influence of Laser Power on the Hardening of Ti6Al4V Low-Pressure Steam Turbine Blade Material for Enhancing Water Droplet Erosion Resistance

    Science.gov (United States)

    Mann, B. S.; Arya, Vivek; Pant, B. K.

    2011-03-01

    To overcome water droplet erosion of Ti6Al4V alloy blade material used in low-pressure steam turbine (LPST) of high-rating nuclear and super critical thermal power plants, high-power diode laser (HPDL) surface treatment at two temperatures corresponding to two different power levels was carried out. During incubation as well as under prolonged erosion testing, the HPDL surface treatment of this alloy has enhanced its resistance significantly. This is due to the formation of fine-grained martensitic (ά) phase due to rapid heating and cooling associated with laser treatment. The droplet erosion test results after HPDL surface treatment on this alloy, SEM, XRD analysis, and residual stresses developed due to HPDL surface treatment are given in this paper.

  3. Improving the conversion efficiency of Cu2ZnSnS4 solar cell by low pressure sulfurization

    Science.gov (United States)

    Zhang, Kun; Su, Zhenghua; Zhao, Lianbo; Yan, Chang; Liu, Fangyang; Cui, Hongtao; Hao, Xiaojing; Liu, Yexiang

    2014-04-01

    Cu2ZnSnS4 thin films have been prepared by the sol-gel sulfurization method on Mo-coated substrates, and the comparative studies between the atmospheric pressure sulfurization and low pressure sulfurization was carried out. The Cu2ZnSnS4 film sulfurized at low pressure exhibits larger grain size, thinner MoS2 layer, and free of SnS secondary phase, but more ZnS on surface. The device efficiency of 4.1% using Cu2ZnSnS4 absorber from atmospheric pressure sulfurization is improved to 5.7% using that from low pressure sulfurization via the boost of open-circuit and fill factor.

  4. Numerical simulation of turbulent flow in the throttle of the MBIR reactor's low-pressure chamber

    Science.gov (United States)

    Yarunichev, V. A.; Orlova, E. E.; Lemekhov, Yu. V.; Shpanskii, V. A.

    2015-08-01

    This work in devoted to numerical calculation of turbulent flow in a labyrinth-type throttle. A system of such throttles is installed at the inlet to the MBIR reactor's low-pressure chamber and serves for setting up the required pressure difference and coolant flow rate. MBIR is a multipurpose fourthgeneration fast-neutron research reactor intended for investigating new kinds of nuclear fuel, structural materials, and coolants. The aim of this work is to develop a verified procedure for carrying out 3D calculation of the throttle using CFD modeling techniques. The investigations on determining the throttle hydraulic friction coefficient were carried out in the range of Reynolds numbers Re = 52000-136000. The reactor coolant (liquid sodium) was modeled by tap water. The calculations were carried out using high-Reynolds-number turbulence models with the near-wall functions k-ɛ and RNG k-ɛ, where k is the turbulent pulsation kinetic energy and ɛ is the turbulence kinetic energy dissipation rate. The obtained results have shown that the calculated value of hydraulic friction coefficient differs from its experimental value by no more than 10%. The developed procedure can be applied in determining the hydraulic friction coefficient of a modified labyrinth throttle design. The use of such calculation will make it possible to predict an experiment with the preset accuracy.

  5. Impurity incorporation in orientation patterned GaAs grown by low pressure HVPE

    Science.gov (United States)

    Snure, M.; Jiménez, J.; Hortelano, V.; Swider, S.; Mann, M.; Tassev, V.; Lynch, C.; Bliss, D.

    2012-08-01

    Orientation-patterned GaAs (OP-GaAs) has shown promise as an efficient frequency-shifted laser source over the range of 2-12 μm. In order to make OP-GaAs a viable source, efficiency and output power must be significantly increased, which requires minimizing major sources of loss. Low pressure HVPE has been adopted as the most suitable technique for regrowth of thick high quality GaAs layers on OP templates. We have explored process parameters in bulk and OP material to identify and control the sources of point defects, a key contributor to optical losses. Growth on OP templates with periodic [001] and [00-1] domains results in domain specific surface orientation, which should have inhomogeneous defect incorporation. Hall measurements, SIMS depth profiling, and cathodoluminescence (CL) were used to identify point defects in bulk and OP-GaAs. It was found that Si impurities are the primary source of donors, while VGa were identified as the primary source of acceptors. In order to study the incorporation of impurities in OP-GaAs samples, we intentionally doped samples with Si to increase CL and SIMS detectability. Spatially resolved CL and SIMS revealed regions with significant differences in the defect concentration, which can affect device output.

  6. Review of recent developments and applications in low-pressure (vacuum outlet) gas chromatography.

    Science.gov (United States)

    Sapozhnikova, Yelena; Lehotay, Steven J

    2015-10-29

    The concept of low pressure (LP) vacuum outlet gas chromatography (GC) was introduced more than 50 years ago, but it was not until the 2000s that its theoretical applicability to fast analysis of GC-amenable chemicals was realized. In practice, LPGC is implemented by placing the outlet of a short, wide (typically 10-15 m, 0.53 mm inner diameter) analytical column under vacuum conditions, which speeds the separation by reducing viscosity of the carrier gas, thereby leading to a higher optimal flow rate for the most separation efficiency. To keep the inlet at normal operating pressures, the analytical column is commonly coupled to a short, narrow uncoated restriction capillary that also acts as a guard column. The faster separations in LPGC usually result in worse separation efficiency relative to conventional GC, but selective detection usually overcomes this drawback. Mass spectrometry (MS) provides highly selective and sensitive universal detection, and nearly all GC-MS instruments provide vacuum outlet conditions for implementation of LPGC-MS(/MS) without need for adaptations. In addition to higher sample throughput, LPGC provides other benefits, including lower detection limits, less chance of analyte degradation, reduced peak tailing, increased sample loadability, and more ruggedness without overly narrow peaks that would necessitate excessively fast data acquisition rates. This critical review summarizes recent developments in the application of LPGC with MS and other detectors in the analysis of pesticides, environmental contaminants, explosives, phytosterols, and other semi-volatile compounds.

  7. NMR Study of Laser-polarized 129Xe in Low Pressure Natural Xenon Gas

    Institute of Scientific and Technical Information of China (English)

    SUN Xianping; WANG Shenglie; ZENG Xizhi

    2001-01-01

    The NMR signal from the laser-polarized t29 Xe in low-pressure natural xenon gas has been observed with a Bruker WP-80SY NMR spectrometer. The laser-polarized 129 Xe was produced by the method of laser pumping and spin exchange in a magnetic field of 1.87 Tesla. It is obtained experimentally that the nuclear spin relaxation rate 1/T1 of laser-polarized 129Xe are (4.03±1.97)×10-3/see~(2.21±0.78)×10-3/see in the range of the 3.33×103 Pa~8.29×104 Pa Xe gas pressures, the apparent wall relaxation rate 1/Tw* =(1.98±0.18)×10-3/see, and the relaxation rate coefficient C of 133Cs-129Xe spin exchange is (2.81±0.74)×10-16 em3/sec.

  8. Low-pressure phase diagram of crystalline benzene from quantum Monte Carlo

    CERN Document Server

    Azadi, Sam

    2016-01-01

    We study the low-pressure (0 to 10 GPa) phase diagram of crystalline benzene using quantum Monte Carlo (QMC) and density functional theory (DFT) methods. We consider the $Pbca$, $P4_32_12$, and $P2_1/c$ structures as the best candidates for phase I and phase II. We perform diffusion quantum Monte Carlo (DMC) calculations to obtain accurate static phase diagrams as benchmarks for modern van der Waals density functionals. We use density functional perturbation theory to compute phonon contribution in the free-energy calculations. Our DFT enthalpy-pressure phase diagram indicates that the $Pbca$ and $P2_1/c$ structures are the most stable phases within the studied pressure range. The DMC Gibbs free-energy calculations predict that the room temperature $Pbca$ to $P2_1/c$ phase transition occurs at 2.1(1) GPa. This prediction is consistent with available experimental results at room temperature. Our DMC calculations show an estimate of 50.6$\\pm$0.5 kJ/mol for crystalline benzene lattice energy.

  9. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    Science.gov (United States)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2016-07-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  10. High-voltage nanosecond pulses in a low-pressure radiofrequency discharge

    CERN Document Server

    Pustylnik, Mikhail; Ivlev, Alexei; Vasilyak, Leonid; Couëdel, Lenaic; Thomas, Hubertus; Morfill, Gregor; Fortov, Vladimir

    2013-01-01

    An influence of a high-voltage (3-17 kV) 20 ns pulse on a weakly-ionized low-pressure (0.1-10 Pa) capacitively-coupled radiofrequency (RF) argon plasma is studied experimentally. The plasma evolution after pulse exhibits two characteristic regimes: a bright flash, occurring within 100 ns after the pulse (when the discharge emission increases by 2-3 orders of magnitude over the steady-state level), and a dark phase, lasting a few hundreds \\mu s (when the intensity of the discharge emission drops significantly below the steady-state level). The electron density increases during the flash and remains very large at the dark phase. 1D3V particle-in-cell simulations qualitatively reproduce both regimes and allow for detailed analysis of the underlying mechanisms. It is found that the high-voltage nanosecond pulse is capable of removing a significant fraction of plasma electrons out of the discharge gap, and that the flash is the result of the excitation of gas atoms, triggered by residual electrons accelerated in t...

  11. Evaluation of Low-Pressure Cold Plasma for Disinfection of ISS Grown Produce and Metallic Instrumentation

    Science.gov (United States)

    Hintze, Paul E.; Franco, Carolina; Hummerick, Mary E.; Maloney, Phil R.; Spencer, Lashelle E.

    2017-01-01

    Cold plasma (CP) cleaning is a dry, non-thermal process, which can provide broad-spectrum antimicrobial activity yet reportedly causes little to no damage to the object being sanitized. Since cold plasma uses no liquids, it has the distinct advantage when used in microgravity of not having to separate liquids from the item being cleaned. This paper will present results on an effort to use low pressure CP to disinfect or sterilize materials for in space applications. Exposure times from 0 to 60 minutes and pressures ranging from 0.10 to 1.0 mbar were used to optimize plasma parameters. Tests were done on produce and metal coupons to simulate medical equipment. Escherichia coli was used as the challenge organism on produce and Bacillus pumilus SAFR-32 was used on metal surfaces. Produce testing was not successful, with unacceptable kill rates and the produce being negatively impacted by exposure to the plasma. The plasma caused a 5 log reduction in the number of viable bacteria on metal coupon tests, which placed the number of viable bacteria below the detection limit. This is a very promising result showing that sterilization of medical equipment with cold plasma is feasible. Scanning Electron Microscope images were taken before and after exposure. The images after plasma exposure show that the bacteria spores have been physically affected, as their size has gotten smaller and their appearance has changed.

  12. Evaluation of Low-Pressure Cold Plasma for Disinfection for ISS Grown Produce and Metallic Instrumentation

    Science.gov (United States)

    Hintze, Paul E.; Franco, Carolina; Hummerick, Mary E.; Maloney, Phillip R.; Spencer, Lashelle E.

    2017-01-01

    Cold plasma (CP) cleaning is a dry, non-thermal process, which can provide broad-spectrum antimicrobial activity yet reportedly causes little to no damage to the object being sanitized. Since cold plasma uses no liquids, it has the distinct advantage when used in microgravity of not having to separate liquids from the item being cleaned. This paper will present results on an effort to use low pressure CP to disinfect or sterilize materials for in space applications. Exposure times from 0 to 60 minutes and pressures ranging from 10 to 100 Pa were used to optimize plasma parameters to achieve acceptable kill rates for 3 bacteria, Bacillus cereus, E. coli and Bacillus pumulis SAFR-32 and one fungi, Aspergillus niger. These tests were done on produce and metal coupons to simulate medical equipment. Produce testing was not successful, with unacceptable kill rates and the produce being negatively impacted by exposure to the plasma. The plasma caused a 5 log reduction in the number of viable bacteria on metal coupon tests, which placed the number of viable bacteria below the detection limit. This is a very promising result showing that sterilization of medical equipment with cold plasma is feasible. Scanning Electron Microscope images were taken before and after exposure. The images after plasma exposure shows that the bacteria spores have been physically affected, as their size has gotten smaller and the appearance has changed.

  13. A collisional-radiative model for low-pressure weakly magnetized Ar plasmas

    Science.gov (United States)

    Zhu, Xi-Ming; Tsankov, Tsanko; Czarnetzki, Uwe; Marchuk, Oleksandr

    2016-09-01

    Collisional-radiative (CR) models are widely investigated in plasma physics for describing the kinetics of reactive species and for optical emission spectroscopy. This work reports a new Ar CR model used in low-pressure (0.01-10 Pa) weakly magnetized (<0.1 Tesla) plasmas, including ECR, helicon, and NLD discharges. In this model 108 realistic levels are individually studied, i.e. 51 lowest levels of the Ar atom and 57 lowest levels of the Ar ion. We abandon the concept of an ``effective level'' usually adopted in previous models for glow discharges. Only in this way the model can correctly predict the non-equilibrium population distribution of close energy levels. In addition to studying atomic metastable and radiative levels, this model describes the kinetic processes of ionic metastable and radiative levels in detail for the first time. This is important for investigation of plasma-surface interaction and for optical diagnostics using atomic and ionic line-ratios. This model could also be used for studying Ar impurities in tokamaks and astrophysical plasmas.

  14. Aluminum oxide films deposited in low pressure conditions by reactive pulsed dc magnetron sputtering

    CERN Document Server

    Seino, T

    2002-01-01

    The reactive pulsed dc sputtering technique is widely used for the deposition of oxide films. The operating pressure for sputtering is commonly above 0.13 Pa. In this study, however, aluminum oxide (alumina) films were deposited at operating pressures from 0.06 to 0.4 Pa using a sputtering system equipped with a scanning magnetron cathode and a pulsed dc power supply. The pulsed dc power was found to be useful not only to reduce arcing, but also to sustain the discharge at low pressure. The electrical breakdown field, intrinsic stress, O/Al ratio, refractive index, and surface roughness were investigated. Both a low intrinsic stress and an O/Al ratio around the stoichiometry were required to get the film having a high breakdown field. A low operating pressure of 0.1 Pa was found to provide the necessary stress and O/Al ratio targets. A 50-nm-thick alumina film having a maximum breakdown field of 7.4 MV/cm was obtained.

  15. Two-Phase Instability Characteristics of Printed Circuit Steam Generator for the Low Pressure Condition

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Han-Ok; Han, Hun Sik; Kim, Young-In; Kim, Keung Koo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall manufacturing cost for the components. A PCHE(Printed Circuit Heat Exchanger) is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. PCSG(Printed Circuit Steam Generator) is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. For the introduction of new steam generator, design requirement for the two-phase flow instability should be considered. This paper describes two-phase flow instability characteristics of PCSG for the low pressure condition. PCSG is a potential candidate to be applied to the integral reactor with its compactness and mechanical robustness. Interconnecting flow path was developed to mitigate the two-phase flow instability in the cold side. The flow characteristics of two-phase flow instability at the PCSG is examined experimentally in this study.

  16. Reconsideration of basic concepts for the low-pressure discharge maintenance

    Science.gov (United States)

    Shivarova, Antonia

    2016-09-01

    The Schottky condition and the concept for the ambipolar field known as bases of the low-pressure discharge maintenance are reconsidered. Whereas the Schottky condition results in a value of the electron temperature independent of the plasma density, the discussed generalized form of the Schottky condition relates - due to the nonlinear processes in the charged particle balance - the electron temperature to the plasma density, thus, ensuring self-consistency of the plasma description. The concept for equality of the electron and ion fluxes resulting into the ambipolar field is the second issue discussed. Localization of the power input outside the high plasma-density region, a common case in many rf plasma sources, breaks it down by transforming the ambipolar field into a vortex, non-conservative, field. Since the dc field in the discharge should be a potential (conservative) field, it appears to be composed by two vortex field: the ambipolar field and a field related to a vortex dc current, the latter driven by a deviation from the Boltzmann distribution of the electron density. In addition, due to the steady-state magnetic field self-induced by the vortex current in the discharge, the plasma appears magnetized without having an external magnetic field applied.

  17. Performances of nanofiltration and low pressure reverse osmosis membranes for desalination: characterization and modelling

    Science.gov (United States)

    Boussouga, Y. A.; Lhassani, A.

    2017-03-01

    The nanofiltration and the reverse osmosis processes are the most common techniques for the desalination of water contaminated by an excess of salts. In this present study, we were interested in the characterization of commercial, composite and asymmetric membranes of nanofiltration (NF90, NF270) and low pressure reverse osmosis (BW30LE). The two types of characterization that we opted for our study: (i) characterization of electrical proprieties, in terms of the surface charge of various membranes studied by the measurement of the streaming potential, (ii) hydrodynamic characterization in terms of hydraulic permeability with pure water, mass transfer and phenomenological parameters for each system membrane/salt using hydrodynamic approaches. The irreversible thermodynamics allowed us to model the observed retention Robs of salts (NaCl and Na2SO4) for the different membranes studied, to understand and to predict a good filtration with a membrane. A study was conducted on the type of mass transfer for each system membrane/salt: convection and diffusion. The results showed that all tested membranes are negatively charged for the solutions at neutral pH, this is explained by their material composition. The results also showed competitiveness between the different types of membranes. In view of that the NF remains effective in terms of selective retention with less energy consumption than LPRO.

  18. Effects of feed solution chemistry on low pressure reverse osmosis filtration of cesium and strontium.

    Science.gov (United States)

    Ding, Shiyuan; Yang, Yu; Huang, Haiou; Liu, Hengchen; Hou, Li-an

    2015-08-30

    The objective of this study was to identify the removal mechanisms of radionuclides by reverse osmosis (RO) membranes under conditions relevant to full-scale water treatment. For this purpose, the effects of feed solution chemistry on the removal of Cs and Sr by a low pressure RO system was investigated by systematically varying membrane surface charge, ionic composition, and organic matter concentrations. The results showed that the effects of solution chemistry on the filtration of Cs and Sr were related to their hydrated ionic radius, resulting in the predominance of the Donnan's effect and electrostatic interactions, respectively. Consequently, the rejection of Cs increased more pronouncedly than Sr with the increases of feed concentration. Due to the Donnan's effect, different anions decreased the rejection of Cs to different extents in accordance to the order of anions' radii as SO4(2-)>Cl(-)>NO3(-)>F(-). The variations in Sr rejection were influenced by the electrostatic interactions between Sr(2+) and the membrane. In addition, humic acid (HA) lowered the rejection of Cs and caused significant membrane flux decline, but did not change the rejection of Sr. Sr also aggravated HA fouling of the membrane. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Microwave air plasmas in capillaries at low pressure I. Self-consistent modeling

    Science.gov (United States)

    Coche, P.; Guerra, V.; Alves, L. L.

    2016-06-01

    This work presents the self-consistent modeling of micro-plasmas generated in dry air using microwaves (2.45 GHz excitation frequency), within capillaries (model couples the system of rate balance equations for the most relevant neutral and charged species of the plasma to the homogeneous electron Boltzmann equation. The maintenance electric field is self-consistently calculated adopting a transport theory for low to intermediate pressures, taking into account the presence of O- ions in addition to several positive ions, the dominant species being O{}2+ , NO+ and O+ . The low-pressure small-radius conditions considered yield very-intense reduced electric fields (˜600-1500 Td), coherent with species losses controlled by transport and wall recombination, and kinetic mechanisms strongly dependent on electron-impact collisions. The charged-particle transport losses are strongly influenced by the presence of the negative ion, despite its low-density (˜10% of the electron density). For electron densities in the range (1-≤ft. 4\\right)× {{10}12} cm-3, the system exhibits high dissociation degrees for O2 (˜20-70%, depending on the working conditions, in contrast with the  ˜0.1% dissociation obtained for N2), a high concentration of O2(a) (˜1014 cm-3) and NO(X) (5× {{10}14} cm-3) and low ozone production (<{{10}-3}% ).

  20. Pulsed Discharge Effects on Bacteria Inactivation in Low-Pressure Radio-Frequency Oxygen Plasma

    Science.gov (United States)

    Vicoveanu, Dragos; Ohtsu, Yasunori; Fujita, Hiroharu

    2008-02-01

    The sporicidal effects of low-pressure radio frequency (RF) discharges in oxygen, produced by the application of continuous and pulsed RF power, were evaluated. For all cases, the survival curves showed a biphasic evolution. The maximum efficiency for bacteria sterilization was obtained when the RF power was injected in the continuous wave mode, while in the pulsed mode the lowest treatment temperature was ensured. The inactivation rates were calculated from the microorganism survival curves and their dependencies on the pulse characteristics (i.e., pulse frequency and duty cycle) were compared with those of the plasma parameters. The results indicated that the inactivation rate corresponding to the first phase of the survival curves is related to the time-averaged intensity of the light emission by the excited neutral atoms in the pulsed plasma, whereas the inactivation rate calculated from the second slope of the survival curves and the time-averaged plasma density have similar behaviors, when the pulse parameters were modified.

  1. Impact of effluent organic matter on low-pressure membrane fouling in tertiary treatment

    KAUST Repository

    Ayache, C.

    2013-05-01

    This study aims at comparing low-pressure membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r2 = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r2 = 0.95 and r2 = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the membrane was attributed to hydraulically irreversible fouling (r2 = 0.67). © 2013 Elsevier Ltd.

  2. Reactivation of Giardia lamblia cysts after exposure to low-pressure UV irradiation.

    Science.gov (United States)

    Shin, Gwy-Am; Linden, Karl G

    2015-07-01

    In this study, we determined the repair capabilities of Giardia lamblia cysts when they were exposed to low-pressure (LP) UV and then 4 different repair conditions. A UV collimated beam apparatus was used to expose shallow suspensions of G. lamblia cysts in buffered reagent water (PBS, pH 7.2) to various doses of LP UV irradiation. After UV irradiation, samples were exposed to 4 repair conditions (light and dark repair conditions with 2 temperatures (25 °C and 37 °C) for each condition). The inactivation of G. lamblia cysts by LP UV was very extensive (∼ 5 log10) even with a low dose of LP UV (1 mJ/cm(2)). More importantly, there was significant restoration of infectivity in G. lamblia cysts when they were exposed to a low dose of LP UV and then to all the repair conditions tested. Overall, the results of this study indicate that G. lamblia cysts do have the ability to repair their UV-damaged DNA when they are exposed to low doses of LP UV irradiation. This is the first study to report the presence of repair in UV-irradiated G. lamblia cysts.

  3. Low-Pressure Vapor-Assisted Solution Process for Thiocyanate-Based Pseudohalide Perovskite Solar Cells.

    Science.gov (United States)

    Chiang, Yu-Hsien; Cheng, Hsin-Min; Li, Ming-Hsien; Guo, Tzung-Fang; Chen, Peter

    2016-09-22

    In this report, we fabricated thiocyanate-based perovskite solar cells with low-pressure vapor-assisted solution process (LP-VASP) method. Photovoltaic performances are evaluated with detailed materials characterizations. Scanning electron microscopy images show that SCN-based perovskite films fabricated using LP-VASP have long-range uniform morphology and large grain sizes up to 1 μm. The XRD and Raman spectra were employed to observe the characteristic peaks for both SCN-based and pure CH3 NH3 PbI3 perovskite. We observed that the Pb(SCN)2 film transformed to PbI2 before the formation of perovskite film. X-ray photoemission spectra (XPS) show that only a small amount of S remained in the film. Using LP-VASP method, we fabricated SCN-based perovskite solar cells and achieved a power conversion efficiency of 12.72 %. It is worth noting that the price of Pb(SCN)2 is only 4 % of PbI2 . These results demonstrate that pseudo-halide perovskites are promising materials for fabricating low-cost perovskite solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Spectrochemical analysis of Cs in water and soil using low pressure laser induced breakdown spectroscopy

    Science.gov (United States)

    Ramli, Muliadi; Khumaeni, Ali; Kurniawan, Koo Hendrik; Tjia, May On; Kagawa, Kiichiro

    2017-06-01

    An experimental study has been conducted for the practical and in situ application of laser-induced breakdown spectroscopy (LIBS) for the detection of Cs pollutant in water and soil in the nearby area of Fukushima Nuclear Power Station. The spectrochemical measurements were carried out by means of 355 nm Nd-YAG laser with N2 and He ambient gases at atmospheric and low pressures. The soil samples were prepared by pelletizing the mixtures of 80% soil and 20% KBr while the aqueous samples were prepared as thin films electro deposited on indium tin oxide (ITO) glass. The resulted emission spectra using 0.5 kPa N2 ambient gas shows the minimum detectable Cs concentration of 0.2 ppm and 0.3 ppm in the water and soil samples, respectively. The result of this experiment has thus demonstrated the viability of the LIBS equipment employed here as a more practical, in-situ and even mobile alternative to the standard use of gamma-ray spectroscopy using germanium detector.

  5. A modified setup for measuring the first ionization coefficient of tissue equivalent gases at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Petri, Anna R.; Goncalves, Josemary A.C.; Bueno, Carmen C., E-mail: arpetri@ipen.br, E-mail: josemary@ipen.br, E-mail: ccbueno@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Mangiarotti, Alessio, E-mail: alessio@if.usp.br [Universidade de Sao Paulo (IF/USP), Sao Paulo, SP (Brazil). Instituto de Fisica

    2015-07-01

    In our previous works, measurements of the first Townsend ionization coefficient, α, for pure nitrogen and isobutane at atmospheric pressure as a function of the reduced electric field were carried out in the range of 145 to 194 Td to prevent the chamber from electrical discharges. In order to increase this upper limit, the setup was modified for operating at low pressure. The detector has a Resistive Plate Chamber-like configuration where the primary ionization is produced by the incidence of nitrogen pulsed laser beam on an aluminum electrode. To validate the technique, measurements of the first Townsend ionization coefficient in nitrogen as a function of the reduced electric field were carried out at atmospheric pressure and at 100hPa, as this is an extensively studied gas with well-established data. Good agreement among our results, data from the literature and Magboltz simulations, leading to extend our method to Tissue Equivalent (TE) gases whose α is unknown. Preliminary measurements of α in a methane-based TE gas (CH{sub 4} - 64.4%, CO{sub 2} - 32.4% and N{sub 2} - 3.2%) are also presented. (author)

  6. Production of metallic nanopowders (Mg, Al by solar carbothermal reduction of their oxides at low pressure

    Directory of Open Access Journals (Sweden)

    J. Puig

    2016-06-01

    Full Text Available The carbothermal reduction of MgO and Al2O3 in argon flow at low pressure allows to lower the onset temperature of metal vapor formation. Thermodynamic calculations indicate that metal formation begins at 1400 and 1700 K for a primary vacuum (1000 Pa, respectively, for Mg and Al. In the experimental section, concentrated solar energy was used for the process heating in order to favor energy savings. The products of the reaction between MgO or Al2O3 and 2 varieties of carbon (graphite, carbon black in flowing argon atmosphere at a total pressure of around 1000 to 1600 Pa were studied using X-ray diffraction, and microstructure observations revealed the formation of metallic nanopowders with some by-products. Metallic conversions close to 45 wt% and 52 wt%, respectively, for Mg and Al, were obtained. The low conversion yield of the carbothermal reduction of MgO can be attributed to a backward reaction reforming MgO powder and to a sintering process between oxide particles at high temperature. Aluminum production challenge is to avoid formation of undesired by-products: Al2O, Al4C3 and Al-oxycarbides. Advantages and weaknesses of the used process are described and some improvements are proposed to increase metallic yields.

  7. Uniformly Distributed Graphene Domain Grows on Standing Copper via Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Shih-Hao Chan

    2013-01-01

    Full Text Available Uniformly distributed graphene domains were synthesized on standing copper foil by a low-pressure chemical vapor deposition system. This method improved the distribution of the graphene domains at different positions on the same piece of copper foil along the forward direction of the gas flow. Scanning electron microscopy (SEM showed the average size of the graphene domains to be about ~20 m. This results show that the sheet resistance of monolayer graphene on a polyethylene terephthalate (PET substrate is about ~359 /□ whereas that of the four-layer graphene films is about ~178 /□, with a transmittance value of 88.86% at the 550 nm wavelength. Furthermore, the sheet resistance can be reduced with the addition of HNO3 resulting in a value of 84 /□. These values meet the absolute standard for touch sensor applications, so we believe that this method can be a candidate for some transparent conductive electrode applications.

  8. Corrosion fatigue of bladed disk attachments of low-pressure turbine

    Energy Technology Data Exchange (ETDEWEB)

    Asai, K. [Material Research Lab., Hitachi, Ltd., Hitachi (Japan); Sakurai, S.; Nomura, K. [Thermal Power and Hydroelectric Systems Div., Hitachi, Ltd., Hitachi (Japan); Saito, E.; Namura, K. [Power and Industrial Systems R and D Lab., Hitachi, Ltd., Hitachi (Japan)

    2004-07-01

    The mechanism of a disk cracking in a low-pressure steam turbine was investigated by finite-element and fracture mechanics analysis and, based on the results of the investigation, a life assessment method was derived. The disk cracking was found to be caused by growth of corrosion pits, superposition of multiple vibration modes, and an increase in the standard deviation of the natural frequency of grouped blades after long-term operation. Taking these findings into consideration, the authors then developed a life-assessment method for disk cracking composed of evaluations (1) maximum corrosion pit size at the current situation, (2) corrosion pit growth after a certain term, and (3) failure-occurrence ratio for the estimated corrosion pit depth. Maximum corrosion-pit size is evaluated by extreme value statistical analysis using the data obtained by replica inspection. The failure-occurrence ratio is evaluated by Monte Carlo simulation considering two uncertainties, namely, the standard deviation of the natural frequency of grouped blades and the stimulus ratio. The values of both uncertainties were determined by the inverse problem analysis of the disk cracking. In light of these results, the authors found that replacing conventional tenon-shroud grouped blades with continuous-cover blades is effective from the view point of vibratory behavior. (orig.)

  9. Two dimensional analysis of low pressure flows in the annulus region between two concentric cylinders.

    Science.gov (United States)

    Al-Kouz, Wael; Alshare, Aiman; Alkhalidi, Ammar; Kiwan, Suhil

    2016-01-01

    A numerical simulation of the steady two-dimensional laminar natural convection heat transfer for the gaseous low-pressure flows in the annulus region between two concentric horizontal cylinders is carried out. This type of flow occurs in "evacuated" solar collectors and in the receivers of the solar parabolic trough collectors. A finite volume code is used to solve the coupled set of governing equations. Boussinesq approximation is utilized to model the buoyancy effect. A correlation for the thermal conductivity ratio (k r = k eff/k) in terms of Knudsen number and the modified Rayleigh number is proposed for Prandtl number (Pr = 0.701). It is found that as Knudsen number increases then the thermal conductivity ratio decreases for a given Rayleigh number. Also, it is shown that the thermal conductivity ratio k r increases as Rayleigh number increases. It appears that there is no consistent trend for varying the dimensionless gap spacing between the inner and the outer cylinder ([Formula: see text]) on the thermal conductivity ratio (k r) for the considered spacing range.

  10. The isolation of soyasaponins by fractional precipitation, solid phase extraction, and low pressure liquid chromatography.

    Science.gov (United States)

    Gurfinkel, D M; Reynolds, W F; Rao, A V

    2005-11-01

    Bioactive soyasaponins are present in soybean (Glycine max). In this study, the isolation of soyasaponins in relatively pure form (>80%) using precipitation, solid phase extraction and reverse phase low pressure liquid chromatography (RP-LPLC) is described. Soy flour soyasaponins were separated from non-saponins by methanol extraction and precipitation with ammonium sulphate. Acetylated group A soyasaponins were isolated first by solid phase extraction followed by RP-LPLC (solvent: ethanol-water). Soyasaponins, from a commercial preparation, were saponified and fractionated into deacetylated group A and group B soyasaponins by solid phase extraction (methanol-water). Partial hydrolysis of group B soyasaponins produced a mixture of soyasaponin III and soyasapogenol B monoglucuronide. RP-LPLC of deacetylated group A soyasaponins separated soyasaponin A1 and A2 (38% methanol); of group B soyasaponins isolated soyasaponin I (50% ethanol); and of the partial hydrolysate separated soyasaponin III from soyasapogenol B monoglucuronide (50% ethanol). This methodology provides soyasaponin fractions that are suitable for biological evaluation.

  11. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

    Science.gov (United States)

    Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

    2015-07-15

    Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

  12. Glow discharge in low pressure plasma PVD: mathematical model and numerical simulations

    CERN Document Server

    Speranza, A; Meacci, L; Fanfani, S; Borsi, I; Monti, A; 10.1007/s11012-010-9330-z

    2010-01-01

    In this paper we analyze the problem of glow discharge in low pressure plasma in industrial plant, for chambers of different shapes and various working parameters, like pressure and electric potential. The model described is based upon a static approximation of the AC configuration with two electrodes and a drift diffusion approximation for the current density of positive ions and electrons. A detailed discussion of the boundary conditions imposed is given, as well as the full description of the mathematical model. Numerical simulations were performed for a simple 1D model and two different 2D models, corresponding to two different settings of the industrial plant. The simpler case consists of a radially symmetric chamber, with one central electrode (cathode), based upon a DC generator. In this case, the steel chamber acts as the anode. The second model concerns a two dimensional horizontal cut of the most common plant configuration, with two electrodes connected to an AC generator. The case is treated in a "...

  13. Recycling of plastics from stockpiles performed by means of low-pressure injection

    Directory of Open Access Journals (Sweden)

    J. Gintowt

    2010-07-01

    Full Text Available A viability analysis of manufacturing goods out of plastics, from stockpiles and municipal residues, has been carried out. The analysispertains goods in the form of inserts manufactured in light molds of big-sizes, by means of low-pressure injection. The cost analysis of the investment and manufacturing suggests that those goods are not price-competitive, as compared to other ones used in similar situations. Exploitation analysis proves that the goods, used outdoors are easily damaged on the surface by UV exposure, temperature differences of 24-hour cycle, as well as by water and plants. Re-recycling, and especially, the grinding of the product poses another challenge in the future. An analysis of the environmental impact of energy acquisition during the manufacturing of those goods was also carried out. The analysis also pertains the method of identifying the type of raw-material, in the process of segregation that stems from the necessity of a complex content training of staff running waste segregation posts.

  14. Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions.

    Science.gov (United States)

    Yu, Huiyang; Huang, Jianqiu

    2015-09-08

    In this paper, a pressure sensor for low pressure detection (0.5 kPa-40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance.

  15. Investigation of Low-Pressure Ultraviolet Radiation on Inactivation of Rhabitidae Nematode from Water

    Directory of Open Access Journals (Sweden)

    Mohammad Hadi Dehghani

    2013-03-01

    Full Text Available Background: Rhabditidae is a family of free-living nematodes. Free living nematodes due to their active movement and resistance to chlorination, do not remove in conventional water treatment processes thus can be entered to distribution systems and cause adverse health effects. Ultraviolet radiation (UV can be used as a method of inactivating for these organisms. This cross sectional study was done to investigate the efficiency of ultraviolet lamp in the inactivation of free living nematode in water.Methods: The effects of radation time, turbidity, pH and temperature were invistigated in this study. Ultraviolet lamp used in this study was a 11 W lamp and intensity of this lamp was 24 µw / cm2.Results: Radiation time required to achieve 100% efficiency for larvae nematode and adults was 9 and 10 minutes respectively. There was a significant correlation between the increase in radiation time, temperature rise and turbidity reduction with inactivation efficiency of lamp (P<0.001. Increase of turbidity up 25 NTU decreased inactivation efficiency of larvae and adult nematodes from 100% to 66% and 100% to 64% respectively. Change in pH range from 6 to 9 did not affect the efficiency of inactivation. With increasing temperature inactivation rate increased. Also the effect of the lamp on inactivation of larvae nematod was mor than adults.Conclusions: It seems that with requiring the favorable conditions low-pressure ultraviolet radiation systems can be used for disinfection of water containing Rhabitidae nematode.

  16. Determination of Stress Intensity Factors in Low Pressure Turbine Rotor Discs

    Directory of Open Access Journals (Sweden)

    Ivana Vasovic

    2014-01-01

    Full Text Available An attention in this paper is focused on the stress analysis and the determination of fracture mechanics parameters in low pressure (LP turbine rotor discs and on developing analytic expressions for stress intensity factors at the critical location of LP steam turbine disc. Critical locations such as keyway and dovetail area experienced stress concentration leading to crack initiation. Major concerns for the power industry are determining the critical locations with one side and fracture mechanics parameters with the other side. For determination of the critical locations in LP turbine rotor disc conventional finite elements are used here. For this initial crack length and during crack growth it is necessary to determine SIFs. In fatigue crack growth process it is necessary to have analytic formulas for the stress intensity factor. To determine analytic formula for stress intensity factor (SIF of cracked turbine rotor disc special singular finite elements are used. Using discrete values of SIFs which correspond to various crack lengths analytic formula of SIF in polynomial forms is derived here. For determination of SIF in this paper, combined J-integral approach and singular finite elements are used. The interaction of mechanical and thermal effects was correlated in terms of the fracture toughness.

  17. Thermodynamics of Methane Adsorption on Copper HKUST-1 at Low Pressure.

    Science.gov (United States)

    Wu, Di; Guo, Xiaofeng; Sun, Hui; Navrotsky, Alexandra

    2015-07-02

    Metal-organic frameworks (MOFs) can be engineered as natural gas storage materials by tuning the pore structures and surface properties. Here we report the direct measurement of CH4 adsorption enthalpy on a paddlewheel MOF (Cu HKUST-1) using gas adsorption calorimetry at 25 °C at low pressures (below 1 bar). In this pressure region, the CH4-CH4 intermolecular interactions are minimized and the energetics solely reflects the CH4-MOF interactions. Our results suggest moderately exothermic physisorption with an enthalpy of -21.1 ± 1.1 kJ/mol CH4 independent of coverage. This calorimetric investigation complements previous computational and crystallographic studies by providing zero coverage enthalpies of CH4 adsorption. The analysis of the new and literature data suggests that in initial stages of adsorption the CH4-HKUST-1 interaction tends to be more sensitive to the pore dimension than to the guest polarizability, suggesting a less specific chemical binding role for the open Cu site.

  18. Unilateral bicep curl hemodynamics: Low-pressure continuous vs high-pressure intermittent blood flow restriction.

    Science.gov (United States)

    Brandner, C R; Kidgell, D J; Warmington, S A

    2015-12-01

    Light-load exercise training with blood flow restriction (BFR) increases muscle strength and size. However, the hemodynamics of BFR exercise appear elevated compared with non-BFR exercise. This questions the suitability of BFR in special/clinical populations. Nevertheless, hemodynamics of standard prescription protocols for BFR and traditional heavy-load exercise have not been compared. We investigated the hemodynamics of two common BFR exercise methods and two traditional resistance exercises. Twelve young males completed four unilateral elbow flexion exercise trials in a balanced, randomized crossover design: (a) heavy load [HL; 80% one-repetition maximum (1-RM)]; (b) light load (LL; 20% 1-RM); and two other light-load trials with BFR applied (c) continuously at 80% resting systolic blood pressure (BFR-C) or (d) intermittently at 130% resting systolic blood pressure (BFR-I). Hemodynamics were measured at baseline, during exercise, and for 60-min post-exercise. Exercising heart rate, blood pressure, cardiac output, and rate-pressure product were significantly greater for HL and BFR-I compared with LL. The magnitude of hemodynamic stress for BFR-C was between that of HL and LL. These data show reduced hemodynamics for continuous low-pressure BFR exercise compared with intermittent high-pressure BFR in young healthy populations. BFR remains a potentially viable method to improve muscle mass and strength in special/clinical populations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Molding Properties of Inconel 718 Feedstocks Used in Low-Pressure Powder Injection Molding

    Directory of Open Access Journals (Sweden)

    Fouad Fareh

    2016-01-01

    Full Text Available The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to study the degree of dependence of shear rate and temperature on the viscosity of the feedstocks. The injection performance of feedstocks was then evaluated using an analytical moldability model. The results indicated that the viscosity profiles of feedstocks depend significantly on the binder constituents, and the secondary binder constituents play an important role in the rheological behavior (pseudoplastic or near-Newtonian exhibited by the feedstock formulations. Viscosity values as low as 0.06 to 2.9 Pa·s were measured at high shear rates and high temperatures. The results indicate that a feedstock containing a surfactant agent exhibits the best moldability characteristics.

  20. Numerical Simulations of Low Pressure Inductively Coupled Plasmas in Geometrically Complex Reactors

    Science.gov (United States)

    Yu, Ben; Wu, Hanming; Krishnan, Anantha

    1996-10-01

    A two-dimensional fluid model has been developed for simulation of low pressure inductively coupled plasma (ICP) reactors. The model obtains solutions for the plasma density, electron temperature, and electric field for the given operating conditions. The physical phenomena and processes such as ambipolar diffusion, thermal diffusion, quasi-neutrality, ionization, inductive Joule heating, and excitations are considered in the model. A significant feature of the model is its capability of handling complex geometries that are often encountered in industrial reactors. Complex reactor geometries are modeled by a body-fitted-coordinate (BFC) formulation. A series of numerical experiments have been conducted using the model to study effects of various parameters such as chamber pressure, size of the wafer, position of the inductive coil, and the power input into the plasma. Different reactor geometries such as the GEC ICP reference cell and the belljar reactor have been simulated. The results of the parametric experiments are presented to show certain systematic trends in performance parameters such as uniformity and processing rates. The ICP model has been coupled to a computational fluid dynamics (CFD) code (capable of 3D simulations) that obtains the flow and pressure distribution inside the chamber. The ICP model will use pressure predictions (from the CFD model) to compute the local ionization rates. Chemical source/sink terms from the plasma dissociation model will be used by the CFD code to account for local reactant depletion effects.

  1. Epitaxial film growth of chromium dioxide by low pressure chemical vapor deposition using chromium carbonyl

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jinwen [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Pathak, Manjit [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Zhong Xing [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Electrical and Computer Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); LeClair, Patrick [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Klein, Tonya M. [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States); Gupta, Arunava, E-mail: agupta@mint.ua.ed [MINT Center, University of Alabama, Tuscaloosa, AL 35487 (United States); Department of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, AL 35487 (United States)

    2010-09-30

    Epitaxial chromium dioxide (CrO{sub 2}) thin films have been deposited by low pressure chemical vapor deposition (LPCVD) on (100) TiO{sub 2} substrates using the precursor chromium hexacarbonyl (Cr(CO){sub 6}) within a narrow temperature window of 380-400 {sup o}C. Normal {theta}-2{theta} Bragg x-ray diffraction results show that the predominant phase is CrO{sub 2} with only a small amount of Cr{sub 2}O{sub 3} present, mostly at the film surface. The LPCVD films have a reasonably smooth surface morphology with a root mean square roughness of 4 nm on a scale of 5 {mu}m. Raman spectroscopy confirms the existence of rutile CrO{sub 2} in the deposited films, while transmission electron microscopy confirms the single-crystalline nature of the films. The LPCVD films showing a dominant CrO{sub 2} phase exhibit clear uniaxial magnetic anisotropy with the easy axis oriented along the c direction.

  2. The deterministic prediction of damage functions to low pressure steam turbines

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chun; Macdonald, D.D.

    1993-01-01

    Localized corrosion phenomena, including pitting corrosion, stress corrosion cracking, and corrosion fatigue, are the principal causes of corrosion-induced damage in electric power generating facilities and typically result in more than 50% of the unscheduled outages. Prediction of damage, so that repairs and inspections can be made during scheduled outages, could have an enormous impact on the economics of electric power generation. To date, prediction of corrosion damage has been made on the basis of empirical/statistical methods that have proven to be insufficiently robust and accurate to form the basis for the desired inspection/repair protocol. In this paper, we describe a deterministic method for predicting localized corrosion damage. We have used the method to illustrate how pitting corrosion initiates stress corrosion cracking (SCC) for low pressure steam turbine disks downstream of the Wilson line, where a thin condensed liquid layer exists on the steel disk surfaces. Our calculations show that the SCC initiation and propagation are sensitive to the oxygen content of the steam, the environment in the thin liquid condensed layer, and the stresses that the disk experiences in service.

  3. The deterministic prediction of damage functions to low pressure steam turbines

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chun; Macdonald, D.D.

    1993-06-01

    Localized corrosion phenomena, including pitting corrosion, stress corrosion cracking, and corrosion fatigue, are the principal causes of corrosion-induced damage in electric power generating facilities and typically result in more than 50% of the unscheduled outages. Prediction of damage, so that repairs and inspections can be made during scheduled outages, could have an enormous impact on the economics of electric power generation. To date, prediction of corrosion damage has been made on the basis of empirical/statistical methods that have proven to be insufficiently robust and accurate to form the basis for the desired inspection/repair protocol. In this paper, we describe a deterministic method for predicting localized corrosion damage. We have used the method to illustrate how pitting corrosion initiates stress corrosion cracking (SCC) for low pressure steam turbine disks downstream of the Wilson line, where a thin condensed liquid layer exists on the steel disk surfaces. Our calculations show that the SCC initiation and propagation are sensitive to the oxygen content of the steam, the environment in the thin liquid condensed layer, and the stresses that the disk experiences in service.

  4. The deterministic prediction of failure of low pressure steam turbine disks

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chun; Macdonald, D.D.

    1993-05-01

    Localized corrosion phenomena, including pitting corrosion, stress corrosion cracking, and corrosion fatigue, are the principal causes of corrosion-induced damage in electric power generating facilities and typically result in more than 50% of the unscheduled outages. Prediction of damage, so that repairs and inspections can be made during scheduled outages, could have an enormous impact on the economics of electric power generation. To date, prediction of corrosion damage has been made on the basis of empirical/statistical methods that have proven to be insufficiently robust and accurate to form the basis for the desired inspection/repair protocol. In this paper, we describe a deterministic method for predicting localized corrosion damage. We have used the method to illustrate how pitting corrosion initiates stress corrosion cracking (SCC) for low pressure steam turbine disks downstream of the Wilson line, where a thin condensed liquid layer exists on the steel disk surfaces. Our calculations show that the SCC initiation and propagation are sensitive to the oxygen content of the steam, the environment in the thin liquid condensed layer, and the stresses that the disk experiences in service.

  5. Little pump that could : hydraulic submersible pump tackles low pressure, low fluid volume gas wells

    Energy Technology Data Exchange (ETDEWEB)

    Ross, E.

    2008-03-15

    A new pump designed by Global Energy Services was described. The pump was designed to address problems associated with downhole pumps in coalbed methane (CBM) wells. The hydraulic submersible pump (HSP) was designed to address issues related to artificial lift gas lock and solids. The pump has been installed at 35 CBM wells in western Canada as well as at natural gas wells with low pressures and low rates of water. The HSP technology was designed for use with wells between 0.01 cubic metres and 24 cubic metres per day of water. A single joystick in the surface unit is used to determine the amount of hydraulic oil delivered to the bottomhole pump when then determines the amounts of fluid produced. A 10-slot self-flushing sand screen is used to filter out particles of sand, coal, and cement. The pump also includes a hydraulic flow control valve to control water volumes. The HSP's positive displacement design makes it suitable for use in horizontal and deviated wells. The pump technology is currently being re-designed to handle larger volumes at deeper depths. 2 figs.

  6. Microwave techniques for electron density measurements in low pressure RF plasmas

    Science.gov (United States)

    Zheltukhin, Viktor; Gafarov, Ildar; Shemakhin, Alexander

    2016-09-01

    Results of the experimental studying of RF plasma jet at low pressure in the range of 10 - 300 Pa is presented. The electron density distribution both in inductive and in capacitive coupled RF discharges was measured at 1.76 MHz and 13.56 MHz consequently. We used three independent microwave diagnostic techniques such as free space (the ``two-frequency'' and ``on the cut-off signal'') and a resonator. It is found that the electron density in the RF plasma jets is by 1-2 orders of magnitude greater than in the decaying plasma jet, and by 1-2 orders of magnitude less than in the RF plasma torch. Thus the RF plasma jet is similar to the additional discharge between the electrodes or the coil and the vacuum chamber walls. As a consequence, the formation of the positive charge sheath near the specimen placed in plasma stream is observed. It is found that the maximum of ionization degree as well as more uniform electron density distribution across the stream is observed in the range of the gas flow rate Gg = 0 . 06 - 0 . 12 g/s and the discharge power Pd = 0 . 5 - 2 . 5 kW. The work was funded by RFBR, according to the research projects No. 16-31-60081 mol_a_dk.

  7. Experimental Investigation on Electromagnetic Attenuation by Low Pressure Radio-Frequency Plasma for Cavity Structure

    Science.gov (United States)

    He, Xiang; Zhang, Yachun; Chen, Jianping; Chen, Yudong; Zeng, Xiaojun; Yao, Hong; Tang, Chunmei

    2016-01-01

    This paper reports on an experiment designed to test electromagnetic (EM) attenuation by radio-frequency (RF) plasma for cavity structures. A plasma reactor, in the shape of a hollow cylinder, filled with argon gas at low pressure, driven by a RF power source, was produced by wave-transmitting material. The detailed attenuations of EM waves were investigated under different conditions: the incident frequency is 1-4 GHz, the RF power supply is 13.56 MHz and 1.6-3 kW, and the argon pressure is 75-200 Pa. The experimental results indicate that 5-15 dB return loss can be obtained. From a first estimation, the electron density in the experiment is approximately (1.5-2.2) × 1016 m-3 and the collision frequency is about 11-30 GHz. The return loss of EM waves was calculated using a finite-difference time-domain (FDTD) method and it was found that it has a similar development with measurement. It can be confirmed that RF plasma is useful in the stealth of cavity structures such as jet-engine inlet. supported by National Natural Science Foundation of China (No. 51107033) and the Fundamental Research Funds for the Central Universities of China (No. 2013B33614)

  8. Experimental Verification of Statistically Optimized Parameters for Low-Pressure Cold Spray Coating of Titanium

    Directory of Open Access Journals (Sweden)

    Damilola Isaac Adebiyi

    2016-06-01

    Full Text Available The cold spray coating process involves many process parameters which make the process very complex, and highly dependent and sensitive to small changes in these parameters. This results in a small operational window of the parameters. Consequently, mathematical optimization of the process parameters is key, not only to achieving deposition but also improving the coating quality. This study focuses on the mathematical identification and experimental justification of the optimum process parameters for cold spray coating of titanium alloy with silicon carbide (SiC. The continuity, momentum and the energy equations governing the flow through the low-pressure cold spray nozzle were solved by introducing a constitutive equation to close the system. This was used to calculate the critical velocity for the deposition of SiC. In order to determine the input temperature that yields the calculated velocity, the distribution of velocity, temperature, and pressure in the cold spray nozzle were analyzed, and the exit values were predicted using the meshing tool of Solidworks. Coatings fabricated using the optimized parameters and some non-optimized parameters are compared. The coating of the CFD-optimized parameters yielded lower porosity and higher hardness.

  9. Ubiquitin, a central component of selective cytoplasmic proteolysis, is linked to proteins residing at the locus of non-selective proteolysis, the vacuole

    NARCIS (Netherlands)

    Simeon, Angela; Klei, Ida J. van der; Veenhuis, Marten; Wolf, Dieter H.

    1992-01-01

    Ubiquitin, an evolutionary highly conserved protein, is known to be involved in selective proteolysis in the cytoplasm. Here we show that ubiquitin-protein conjugates are also found in the yeast vacuole. Mutants defective in the major vacuolar endopeptidases, proteinase yscA and yscB, lead to accumu

  10. Proteolysis and Flavor Characteristics of Serrano Ham Processed under Different Ripening Temperature Conditions.

    Science.gov (United States)

    del Olmo, Ana; Calzada, Javier; Gaya, Pilar; Nuñez, Manuel

    2015-11-01

    Physicochemical, proteolysis and sensory characteristics of Serrano hams processed under low, medium and high ripening temperature conditions (RTC), with respective average temperatures of 9.3, 14.3, and 19.1 °C, were determined throughout a 15-mo period. In addition, quantitative relationships among variables were calculated. Medium and high RTC hams showed lower moisture contents and lower levels of low- and high-ionic-strength soluble proteins than low RTC hams. At 15 mo, aldolase was the most abundant low-ionic-strength soluble protein and actin the most abundant high-ionic-strength soluble protein in all hams while creatine kinase was no longer detected and H-meromyosin was detected only in low and medium RTC hams. Levels of all the molecular-weight peptide fractions increased during ripening, with higher factors of increase for the fractions of lower molecular weight. Total free amino acids were at significantly higher concentrations in medium and high RTC hams than in low RTC hams from month 7 onwards. The correlations of flavor preference and flavor intensity with ripening time, thermal integral, total free amino acids and most individual free amino acids were highly significant, while raw-meat taste was negatively correlated with all those variables. From month 5 to month 9 of ripening, development of a high quality flavor evolved more rapidly in medium RTC hams, flavor intensity increased at a faster rate in high RTC hams and raw-meat taste declined more rapidly in medium and high RTC hams. Medium and high RTC may be applied to accelerate the ripening process of Serrano ham without impairing flavor preference. Medium and high ripening temperature conditions (RTC) may be applied to Serrano ham in order to enhance the phenomena associated with ripening, without loss of product quality. Moisture loss, degradation of proteins and formation of free amino acids were accelerated in medium and high RTC hams. From month 5 to month 9 of ripening, development of a

  11. Study of dust re-suspension at low pressure in a dedicated wind-tunnel

    Science.gov (United States)

    Rondeau, Anthony; Sabroux, Jean-Christophe; Chassefière, Eric

    2015-04-01

    The atmosphere of several telluric planets or satellites are dusty. Such is the case of Earth, Venus, Mars and Titan, each bearing different aeolian processes linked principally to the kinematic viscosity of the near-surface atmosphere. Studies of the Martian atmosphere are particularly relevant for the understanding of the dust re-suspension phenomena at low pressure (7 mbar). It turns out that operation of fusion reactors of the tokamak design produces significant amount of dust through the erosion of plasma-facing components. Such dust is a key issue, both regarding the performance and the safety of a fusion reactor such as ITER, under construction in Cadarache, France. Indeed, to evaluate the explosion risk in the ITER fusion reactor, it is essential to quantify the re-suspended dust fraction as a function of the dust inventory that can be potentially mobilized during a loss of vacuum accident (LOVA), with air or water vapour ingress. A complete accident sequence will encompass dust re-suspension from near-vacuum up to atmospheric pressure. Here, we present experimental results of particles re-suspension fractions measured at 1000, 600 and 300 mbar in the IRSN BISE (BlowIng facility for airborne releaSE) wind tunnel. Both dust monolayer deposits and multilayer deposits were investigated. In order to obtain experimental re-suspension data of dust monolayer deposits, we used an optical microscope allowing to measure the re-suspended particles fraction by size intervals of 1 µm. The deposits were made up of tungsten particles on a tungsten surface (an ubiquitous plasma facing component) and alumina particles on a glass plate, as a surrogate. A comparison of the results with the so-called Rock'nRoll dust re-suspension model (Reeks and Hall, 2001) is presented and discussed. The multilayer deposits were made in a vacuum sedimentation chamber allowing to obtain uniform deposits in terms of thickness. The re-suspension experimental data of such deposits were obtained

  12. RF power transfer efficiency of inductively coupled low pressure H2 and D2 discharges

    Science.gov (United States)

    Rauner, D.; Briefi, S.; Fantz, U.

    2017-09-01

    The RF power transfer efficiency and the relevant power absorption mechanisms of inductively heated hydrogen and deuterium plasmas are investigated in the low-pressure region between 0.25 and 10 Pa. The discharges are generated in a cylindrical vessel via a helical coil applying a frequency of 1 MHz and delivered RF powers up to 800 W. The power transfer efficiency η is quantified by a subtractive method that relies on the measurement of the delivered RF power and of the RF current through the plasma coil both with and without discharge operation. By means of optical emission spectroscopy and electrical probe measurements, the key plasma parameters are obtained. For both H2 and D2, the relative behavior of the power transfer efficiency is well comparable, which increases with increasing delivered RF power and describes a maximum at pressures between 1 and 3 Pa where more than 90 % of the provided power are absorbed by the plasma. The observed relative dependencies of η on the operational parameters are found to be well explained by an analytical approach that considers the power absorption by the plasma via evaluating the RF plasma conductivity based on the measured plasma parameters. At the parameters present, non-collisional stochastic heating of electrons has to be considered for pressures p≤slant 1 {Pa}, while collisional heating dominates at higher pressure. Molecular dissociation is found to have a significant influence on the power transfer efficiency of light molecular discharges. The direct comparison of H2 and D2 identifies the higher atomic density in deuterium to cause a systematically increased power transfer efficiency due to an increased ionization rate in the present electron temperature region.

  13. Identification of effluent organic matter fractions responsible for low-pressure membrane fouling

    KAUST Repository

    Filloux, Emmanuelle

    2012-11-01

    Anion exchange resin (AER), powder activated carbon (PAC) adsorption and ozonation treatments were applied on biologically treated wastewater effluent with the objective to modify the effluent organic matter (EfOM) matrix. Both AER and PAC led to significant total organic carbon (TOC) removal, while the TOC remained nearly constant after ozonation. Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis showed that the AER treatment preferentially removed high and intermediate molecular weight (MW) humic-like structures while PAC removed low MW compounds. Only a small reduction of the high MW colloids (i.e. biopolymers) was observed for AER and PAC treatments. Ozonation induced a large reduction of the biopolymers and an important increase of the low MW humic substances (i.e. building blocks).Single-cycle microfiltration (MF) and ultrafiltration (UF) tests were conducted using commercially available hollow fibres at a constant flux. After reconcentration to their original organic carbon content, the EfOM matrix modified by AER and PAC treatments exhibited higher UF membrane fouling compared to untreated effluent; result that correlated with the higher concentration of biopolymers. On the contrary, ozonation which induced a significant degradation of the biopolymers led to a minor flux reduction for both UF and MF filtration tests. Based on a single filtration, results indicate that biopolymers play a major role in low pressure membrane fouling and that intermediate and low MW compounds have minor impact. Thus, this approach has shown to be a valid methodology to identify the foulant fractions of EfOM. © 2012 Elsevier Ltd.

  14. Final Report: Comparison of the primary (national) standards of low-pressure gas flow

    Science.gov (United States)

    Benková, Miroslava; Makovnik, Stefan; Mickan, Bodo

    2015-01-01

    The EURAMET.M.FF-K6 comparison was organized for the purpose of determination of the degree of equivalence of the primary (national) standards for low-pressure gas flow measurement over the range (2 to 100) m3/h and was performed simultaneously with CCM.FF-K6.2011 with the same transfer standard. A rotary gas meter G65 was used as a transfer standard. The measurements were provided by prescribed reference conditions. Fifteen laboratories from EURAMET participated in this key comparison - SMU, Slovakia; PTB, Germany; CEM, Spain; LNE-LADG, France; VSL, Netherlands; CMI, Czech Republic; BEV, Austria; MKEH, Hungary; GUM Poland; SP, Sweden; METAS, Switzerland; DMDM, Serbia; TUBITAK-UME, Turkey; EIM, Greece; IMBiH, Bosnia-Herzegovina. The EURAMET.M.FF-K6 is linked to the CCM.FF-K6.2011 by correcting the results of three linking laboratories (Slovakia SMU, Germany PTB and France LNE LADG). This correction provides an estimate of what would have been the result from the EURAMET.M-FF-K6 participants, if they had actually participated in CCM.FF-K6.2011. According to the evaluation 93.7 % of the results were consistent with KCRV, 3.4 % of the results were in the warning level and 2.9 % of the results were inconsistent. The results of this comparison can be used for review of the CMC tables. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  15. Ice-melt rates during volcanic eruptions within water-drained, low-pressure subglacial cavities

    Science.gov (United States)

    Woodcock, D. C.; Lane, S. J.; Gilbert, J. S.

    2016-02-01

    Subglacial volcanism generates proximal and distal hazards including large-scale flooding and increased levels of explosivity. Direct observation of subglacial volcanic processes is infeasible; therefore, we model heat transfer mechanisms during subglacial eruptions under conditions where cavities have become depressurized by connection to the atmosphere. We consider basaltic eruptions in a water-drained, low-pressure subglacial cavity, including the case when an eruption jet develops. Such drained cavities may develop on sloping terrain, where ice may be relatively shallow and where gravity drainage of meltwater will be promoted. We quantify, for the first time, the heat fluxes to the ice cavity surface that result from steam condensation during free convection at atmospheric pressure and from direct and indirect radiative heat transfer from an eruption jet. Our calculations indicate that the direct radiative heat flux from a lava fountain (a "dry" end-member eruption jet) to ice is c. 25 kW m-2 and is a minor component. The dominant heat transfer mechanism involves free convection of steam within the cavity; we estimate the resulting condensation heat flux to be c. 250 kW m-2. Absorption of radiation from a lava fountain by steam enhances convection, but the increase in condensing heat flux is modest at c. 25 kW m-2. Overall, heat fluxes to the ice cavity surface are likely to be no greater than c. 300 kW m-2. These are comparable with heat fluxes obtained by single phase convection of water in a subglacial cavity but much less than those obtained by two-phase convection.

  16. Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

    Science.gov (United States)

    Floris, R; Nijmeijer, K; Cornelissen, E R

    2016-03-15

    The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment.

  17. A Shock Tube Study of the CO + OH Reaction Near the Low-Pressure Limit

    KAUST Repository

    Nasir, Ehson Fawad

    2016-05-16

    Rate coefficients for the reaction between carbon monoxide and hydroxyl radical were measured behind reflected shock waves over 700 – 1230 K and 1.2 – 9.8 bar. The temperature/pressure conditions correspond to the predicted low-pressure limit of this reaction, where the channel leading to carbon dioxide formation is dominant. The reaction rate coefficients were inferred by measuring the formation of carbon dioxide using quantum cascade laser absorption near 4.2 µm. Experiments were performed under pseudo-first order conditions with tert-butyl hydroperoxide (TBHP) as the OH precursor. Using ultraviolet laser absorption by OH radicals, the TBHP decomposition rate was measured to quantify potential facility effects under extremely dilute conditions used here. The measured CO + OH rate coefficients are provided in Arrhenius form for three different pressure ranges: kCO+OH (1.2 – 1.6 bar) = 9.14 x 10-13 exp(-1265/T) cm3 molecule-1 s-1 kCO+OH (4.3 – 5.1 bar) = 8.70 x 10-13 exp(-1156/T) cm3 molecule-1 s-1 kCO+OH (9.6 – 9.8 bar) = 7.48 x 10-13 exp(-929/T) cm3 molecule-1 s-1 The measured rate coefficients are found to be lower than the master equation modeling results by Weston et al. [J. Phys. Chem. A, 117 (2013) 821] at 819 K and in closer agreement with the expression provided by Joshi and Wang [Int. J. Chem. Kinet., 38 (2006) 57].

  18. A Shock-Tube Study of the CO + OH Reaction Near the Low-Pressure Limit.

    Science.gov (United States)

    Nasir, Ehson F; Farooq, Aamir

    2016-06-09

    Rate coefficients for the reaction between carbon monoxide and hydroxyl radical were measured behind reflected shock waves over 700-1230 K and 1.2-9.8 bar. The temperature/pressure conditions correspond to the predicted low-pressure limit of this reaction, where the channel leading to carbon dioxide formation is dominant. The reaction rate coefficients were inferred by measuring the formation of carbon dioxide using quantum cascade laser absorption near 4.2 μm. Experiments were performed under pseudo-first-order conditions with tert-butyl hydroperoxide (TBHP) as the OH precursor. Using ultraviolet laser absorption by OH radicals, the TBHP decomposition rate was measured to quantify potential facility effects under extremely dilute conditions used here. The measured CO + OH rate coefficients are provided in Arrhenius form for three different pressure ranges: kCO+OH(1.2-1.6 bar) = (9.14 ± 2.17) × 10(-13) exp(-(1265 ± 190)/T) cm(3) molecule(-1) s(-1); kCO+OH(4.3-5.1 bar) = (8.70 ± 0.84) × 10(-13) exp(-(1156 ± 83)/T) cm(3) molecule(-1) s(-1); and kCO+OH(9.6-9.8 bar) = (7.48 ± 1.92) × 10(-13) exp(-(929 ± 192)/T) cm(3) molecule(-1) s(-1). The measured rate coefficients are found to be lower than the master equation modeling results by Weston et al. [J. Phys. Chem. A, 2013, 117, 821] at 819 K and in closer agreement with the expression provided by Joshi and Wang [Int. J. Chem. Kinet., 2006, 38, 57].

  19. Compressible DNS of transitional and turbulent flow in a low pressure turbine cascade

    Science.gov (United States)

    Ranjan, Rajesh; Deshpande, Suresh; Narasimha, Roddam

    2015-11-01

    Direct numerical simulation (DNS) of flow in a low pressure turbine cascade at high incidence is performed using a new in-house code ANUROOP. This code solves compressible Navier-Stokes equations in conservative form using finite volume technique and uses kinetic-energy consistent scheme for the flux calculations. ANUROOP is capable of handling flow past complex geometries using hybrid grid approach (separate grid topologies for the boundary layer and rest of the blade passage). This approach offers much more control in mesh spacing and distribution compared to elliptic grid technique, which is used in many previous studies. Also, in contrast to previous studies, focus of the current work is mainly on the boundary layer flow. The flow remains laminar on the pressure side of the blade, but separates in the aft region of the suction side leading to transition. Separation bubbles formed at this region are transient in nature and we notice multiple bubbles merging and breaking in time. In the mean flow however, only one bubble is seen. Velocity profiles very near to the leading edge of the suction side suggest strong curvature effect. Higher-order boundary layer theory that includes effect of curvature is found to be necessary to characterize the flow in this region. Also, the grid convergence study reveals interesting aspects of numerics vital for accurate simulation of this kind of complex flows. We would like to thank the Gas Turbine Enabling Technology (GATET) Program for funding this project. We also thank C-DAC, Pune and CSIR-4PI, Bangalore for providing computational resources.

  20. Consideraciones sobre el hidrocefalo de baja presion Considerations on low pressure hydrocephalus

    Directory of Open Access Journals (Sweden)

    E. Herskovits

    1976-12-01

    Full Text Available Se analizan las condiciones fisiopatológicas del sindrome de hidrocéfalo de presión normal. De un grupo de 21 pacientes con sintomatologia clínica correspondiente a esta entidad, se seleccionan 10 que presentan un diagnóstico clínico, radiológico y cisternográfico indudable de la entidad en estudio. Se observó que, a pesar de esta selección solamente un 50% de ellos se vió beneficiado con la colocación de una válvula de baja presión. Surge entonces la hipotésis de que este cuadro es un sindrome multicausal; que por un proceso fisiopatogenico común produce un cuadro clínico, radiológico y cisternográfico similar y que serían beneficiados únicamente aquellos enfermos en los que se soluciona el problema mecánico.The physiopathological conditions of the normal pressure hydrocephalus syndrome are analysed. Within a group of 21 patients with clinical sinto- mathology pertaining this entity, only were 10 selected with a clinical, radiological and cisternografic indubitable diagnosis. It has been noticed that in spite of the stricked selection only a 50% of them have been beneficed by the application of a low pressure valve. Then, the hypothesis that the disease is a multicausal syndrome appears, which by an identical physiopathologic process produces or exhibits a similar clinical, radiological and cisternographic picture. Only those patients on whom the mechanical problem is solved would be beneficed by neurosurgery.

  1. Inactivation of single-celled Ascaris suum eggs by low-pressure UV radiation.

    Science.gov (United States)

    Brownell, Sarah A; Nelson, Kara L

    2006-03-01

    Intact and decorticated single-celled Ascaris suum eggs were exposed to UV radiation from low-pressure, germicidal lamps at fluences (doses) ranging from 0 to 8,000 J/m2 for intact eggs and from 0 to 500 J/m2 for decorticated eggs. With a UV fluence of 500 J/m2, 0.44-+/-0.20-log inactivation (mean+/-95% confidence interval) (63.7%) of intact eggs was observed, while a fluence of 4,000 J/m2 resulted in 2.23-+/-0.49-log inactivation (99.4%). (The maximum quantifiable inactivation was 2.5 log units.) Thus, according to the methods used here, Ascaris eggs are the most UV-resistant water-related pathogen identified to date. For the range of fluences recommended for disinfecting drinking water and wastewater (200 to 2,000 J/m2), from 0- to 1.5-log inactivation can be expected, although at typical fluences (less than 1,000 J/m2), the inactivation may be less than 1 log. When the eggs were decorticated (the outer egg shell layers were removed with sodium hypochlorite, leaving only the lipoprotein ascaroside layer) before exposure to UV, 1.80-+/-0.32-log reduction (98.4%) was achieved with a fluence of 500 J/m2, suggesting that the outer eggshell layers protected A. suum eggs from inactivation by UV radiation. This protection may have been due to UV absorption by proteins in the outer layers of the 3- to 4-microm-thick eggshell. Stirring alone (without UV exposure) also inactivated some of the Ascaris eggs (approximately 20% after 75 min), which complicated determination of the inactivation caused by UV radiation alone.

  2. The effect of thermal annealing on the properties of thin alumina films prepared by low pressure MOCVD

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Vendel, van de D.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin amorphous alumina films were prepared on stainless steel, type AISI 304, by low pressure metal-organic chemical vapour deposition. The effect of thermal annealing in nitrogen (for 2, 4 and 17 h at 600, 700 and 800 °C) on the film properties, including the protection of the underlying substrate

  3. Test beam results of a low-pressure micro-strip gas chamber with a secondary-electron emitter

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, S.; Anderson, D.F.; Zimmerman, J. [Fermi National Accelerator Lab., Batavia, IL (United States); Sbarra, C. [Istituto Nazionale di Fisica Nucleare, Pisa (Italy); Salomon, M. [TRIUMF, Vancouver, BC (Canada)

    1994-10-01

    We present recent results, from a beam test, on the angular dependence of the efficiency and the distribution of the signals on the anode strips of a low-pressure microstrip gas chamber with a thick CsI layer as a secondary-electron emitter. New results of CVD diamond films as secondary-electron emitters are discussed.

  4. Plasma-chemical reactor based on a low-pressure pulsed arc discharge for synthesis of nanopowders

    Science.gov (United States)

    Karpov, I. V.; Ushakov, A. V.; Lepeshev, A. A.; Fedorov, L. Yu.

    2017-01-01

    A reactor for producing nanopowders in the plasma of a low-pressure arc discharge has been developed. As a plasma source, a pulsed cold-cathode arc evaporator has been applied. The design and operating principle of the reactor have been described. Experimental data on how the movement of a gaseous mixture in the reactor influences the properties of nanopowders have been presented.

  5. Randomized Trial of Low-pressure Carbon Dioxide-elicited Pneumoperitoneum Versus Abdominal Wall Lifting for Laparoscopic Cholecystectomy

    Directory of Open Access Journals (Sweden)

    Yih-Huei Uen

    2007-08-01

    Conclusion: Both alternative methods for this type of surgery appeared feasible and safe for LC. Low-pressure CO2 pneumoperitoneum had a shorter surgical duration and less postoperative shoulder pain compared to the GLC technique, but did not feature any other advantage over the AWL technique with regard to impact on cardiopulmonary function.

  6. Assessing the effectiveness of low-pressure ultraviolet light for inactivating Mycobacterium avium complex (MAC) micro-organisms

    Science.gov (United States)

    Aims: To assess low-pressure ultraviolet light (LP-UV) inactivation kinetics of Mycobacterium avium complex (MAC) strains in a water matrix using collimated beam apparatus. Methods and Results: Strains of M. avium (n = 3) and Mycobacterium intracellulare (n = 2) were exposed t...

  7. Characteristics of mold filling and entrainment of oxide film in low pressure casting of A356 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shan-Guang; Cao, Fu-Yang; Zhao, Xin-Yi; Jia, Yan-Dong; Ning, Zhi-Liang; Sun, Jian-Fei, E-mail: jfsun_hit@263.net

    2015-02-25

    The effect of pressurizing speed of low pressure casting on mold filling and mechanical properties of A356 alloy was studied. The mold filling behavior was calculated by two phase flow model using VOF (Volume of Fluid) method. In order to evaluate the accuracy of simulated results, the real mold filling process observed by X-ray radiography was compared. The results show that during mold filling the gate velocity first increased dramatically, then kept unchanged under relatively low pressurizing speed, or increased slowly under relatively high pressurizing speed. High gate velocity causes melt falling back under gravity with high speed. The falling velocity and the resultant relative rotating vortex are the main causes of oxide film entrainment in low pressure casting. The mechanical properties of the as-cast A356 alloy were measured by four-point bend test. Weibull probability plots were used to assess the fracture mechanisms under different pressurizing speeds. The results obtained in this paper illuminate on designing suitable pressurizing speed for mold filling in low pressure casting.

  8. The effect of thermal annealing on the properties of thin alumina films prepared by low pressure MOCVD

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Haanappel, V.A.C.; van de Vendel, D.; van Corbach, H.D.; Fransen, T.; Gellings, P.J.

    1995-01-01

    Thin amorphous alumina films were prepared on stainless steel, type AISI 304, by low pressure metal-organic chemical vapour deposition. The effect of thermal annealing in nitrogen (for 2, 4 and 17 h at 600, 700 and 800 °C) on the film properties, including the protection of the underlying substrate

  9. Assessing the effectiveness of low-pressure ultraviolet light for inactivating Mycobacterium avium complex (MAC) micro-organisms

    Science.gov (United States)

    Aims: To assess low-pressure ultraviolet light (LP-UV) inactivation kinetics of Mycobacterium avium complex (MAC) strains in a water matrix using collimated beam apparatus. Methods and Results: Strains of M. avium (n = 3) and Mycobacterium intracellulare (n = 2) were exposed t...

  10. Experimental and Kinetic Modeling Study of Nitroethane Pyrolysis at a Low Pressure: Competition Reactions in the Primary Decomposition

    DEFF Research Database (Denmark)

    Zhang, Kuiwen; Glarborg, Peter; Zhou, Xueyao

    2016-01-01

    The pyrolysis of nitroethane has been investigated over the temperature range of 682-1423 K in a plug flow reactor at a low pressure. The major species in the pyrolysis process have been identified and quantified using tunable synchrotron vacuum ultraviolet photoionization mass spectrometry and m...

  11. Matriptase activation connects tissue factor-dependent coagulation initiation to epithelial proteolysis and signaling.

    Science.gov (United States)

    Le Gall, Sylvain M; Szabo, Roman; Lee, Melody; Kirchhofer, Daniel; Craik, Charles S; Bugge, Thomas H; Camerer, Eric

    2016-06-23

    The coagulation cascade is designed to sense tissue injury by physical separation of the membrane-anchored cofactor tissue factor (TF) from inactive precursors of coagulation proteases circulating in plasma. Once TF on epithelial and other extravascular cells is exposed to plasma, sequential activation of coagulation proteases coordinates hemostasis and contributes to host defense and tissue repair. Membrane-anchored serine proteases (MASPs) play critical roles in the development and homeostasis of epithelial barrier tissues; how MASPs are activated in mature epithelia is unknown. We here report that proteases of the extrinsic pathway of blood coagulation transactivate the MASP matriptase, thus connecting coagulation initiation to epithelial proteolysis and signaling. Exposure of TF-expressing cells to factors (F) VIIa and Xa triggered the conversion of latent pro-matriptase to an active protease, which in turn cleaved the pericellular substrates protease-activated receptor-2 (PAR2) and pro-urokinase. An activation pathway-selective PAR2 mutant resistant to direct cleavage by TF:FVIIa and FXa was activated by these proteases when cells co-expressed pro-matriptase, and matriptase transactivation was necessary for efficient cleavage and activation of wild-type PAR2 by physiological concentrations of TF:FVIIa and FXa. The coagulation initiation complex induced rapid and prolonged enhancement of the barrier function of epithelial monolayers that was dependent on matriptase transactivation and PAR2 signaling. These observations suggest that the coagulation cascade engages matriptase to help coordinate epithelial defense and repair programs after injury or infection, and that matriptase may contribute to TF-driven pathogenesis in cancer and inflammation.

  12. Simulation of polyatomic discharges for thin film deposition processes in low-pressure plasma reactors

    Science.gov (United States)

    Bera, Kallol

    Comprehensive multi-dimensional self-consistent numerical fluid models for radio-frequency capacitively and inductively coupled methane discharges were developed to predict diamond-like-carbon thin film deposition/etching rate on the wafer. A numerical model of glow discharge provides insight on the physical phenomena in the discharge leading to better understanding and design of the reactor. The developed discharge models included detailed discharge physics, gas-phase chemistry and surface chemistry modeling. To understand the basic discharge phenomena, one- dimensional radio frequency capacitively coupled Ar plasma was simulated using a fluid model. The model was modified for methane plasma to predict the profiles of the plasma variables. The model was then extended to two- dimensional cylindrical coordinates to capture the effects of asymmetry of the reactor on the plasma variables. The necessary dc bias for the discharge was predicted such that the cycle-averaged current to the powered electrode was zero. A discharge chemistry model was also developed to predict various radical and neutral densities in the plasma, and their fluxes to the cathode. The species fluxes are used to predict film deposition rate and the properties of the deposited film. The model predictions of plasma density, self-generated de bias, cathode current and plasma potential compared well with the experimental results. A high density plasma with inductive coupling at low pressure was also considered. Separate rf bias and dc bias are applied to the substrate holder to modulate the ion energy. The present model simulates electron, ion and neutral transport, including detailed discharge and surface chemistry. The model has been implemented for methane discharge to obtain deposition/etching of thin carbon film on the wafer. To the author's knowledge, this is the first attempt to simulate capacitively and inductively coupled plasmas self-consistently for a depositing gas under the operating

  13. "Virtual IED sensor" at an rf-biased electrode in low-pressure plasma

    Science.gov (United States)

    Bogdanova, M. A.; Lopaev, D. V.; Zyryanov, S. M.; Rakhimov, A. T.

    2016-07-01

    Energy distribution and the flux of the ions coming on a surface are considered as the key-parameters in anisotropic plasma etching. Since direct ion energy distribution (IED) measurements at the treated surface during plasma processing are often hardly possible, there is an opportunity for virtual ones. This work is devoted to the possibility of such indirect IED and ion flux measurements at an rf-biased electrode in low-pressure rf plasma by using a "virtual IED sensor" which represents "in-situ" IED calculations on the absolute scale in accordance with a plasma sheath model containing a set of measurable external parameters. The "virtual IED sensor" should also involve some external calibration procedure. Applicability and accuracy of the "virtual IED sensor" are validated for a dual-frequency reactive ion etching (RIE) inductively coupled plasma (ICP) reactor with a capacitively coupled rf-biased electrode. The validation is carried out for heavy (Ar) and light (H2) gases under different discharge conditions (different ICP powers, rf-bias frequencies, and voltages). An EQP mass-spectrometer and an rf-compensated Langmuir probe (LP) are used to characterize plasma, while an rf-compensated retarded field energy analyzer (RFEA) is applied to measure IED and ion flux at the rf-biased electrode. Besides, the pulsed selfbias method is used as an external calibration procedure for ion flux estimating at the rf-biased electrode. It is shown that pulsed selfbias method allows calibrating the IED absolute scale quite accurately. It is also shown that the "virtual IED sensor" based on the simplest collisionless sheath model allows reproducing well enough the experimental IEDs at the pressures when the sheath thickness s is less than the ion mean free path λi (s λi), the difference between calculated and experimental IEDs due to ion collisions in the sheath is observed in the low energy range. The effect of electron impact ionization in the sheath on the origin and

  14. Spatio-temporal variability of summer monsoon rainfall over Orissa in relation to low pressure systems

    Indian Academy of Sciences (India)

    M Mohapatra; U C Mohanty

    2006-04-01

    The summer monsoon rainfall over Orissa occurs mostly due to low pressure systems (LPS)developing over the Bay of Bengal and moving along the monsoon trough.A study is hence undertaken to find out characteristic features of the relationship between LPS over different regions and rainfall over Orissa during the summer monsoon season (June-September).For this purpose,rainfall and rainy days over 31 selected stations in Orissa and LPS days over Orissa and adjoining land and sea regions during different monsoon months and the season as a whole over a period of 20 years (1980-1999)are analysed.The principal objective of this study is to find out the role of LPS on spatial and temporal variability of summer monsoon rainfall over Orissa. The rainfall has been significantly less than normal over most parts of Orissa except the eastern side of Eastern Ghats during July and hence during the season as a whole due to a significantly less number of LPS days over northwest Bay in July over the period of 1980-1999.The seasonal rainfall shows higher interannual variation (increase in coefficient of variation by about 5%)during 1980-1999 than that during 1901-1990 over most parts of Orissa except northeast Orissa.Most parts of Orissa,especially the region extending from central part of coastal Orissa to western Orissa (central zone)and western side of the Eastern Ghats get more seasonal monsoon rainfall with the development and persistence of LPS over northwest Bay and their subsequent movement and persistence over Orissa.The north Orissa adjoining central zone also gets more seasonal rainfall with development and persistence of LPS over northwest Bay.While the seasonal rainfall over the western side of the Eastern Ghats is adversely affected due to increase in LPS days over west central Bay,Jharkhand and Bangladesh,that over the eastern side of the Eastern Ghats is adversely affected due to increase in LPS days over all the regions to the north of Orissa.There are signi

  15. Ultra high efficiency/low pressure supercritical fluid chromatography with superficially porous particles for triglyceride separation.

    Science.gov (United States)

    Lesellier, E; Latos, A; de Oliveira, A Lopes

    2014-01-31

    This paper reports the development of the separation of vegetable oil triglycerides (TG) in supercritical chromatography (SFC), using superficially porous particles (SPPs). The SPP, having a small diameter (2-3μm), provide a higher theoretical plate number (N), which allows to improve separation of critical pairs of compounds. However, compared to fully porous particles of larger diameter (5μm), the pressure drop is also increased. Fortunately, supercritical fluids have a low viscosity, which allows coupling several columns to achieve high N values, while maintaining flow rate above 1ml/min, ensuring a ultra high efficiency (UHE) at low pressure (LP) (below 40MPa), with regards to the one reached with liquid and sub-two micron particles (around 100MPa). The use of two detector systems (UV and ELSD) connected in series to the UHE-LP-SFC system provides complementary responses, due to their specific detection principles. Working in a first part with three coupled Kinetex C18 columns (45cm total length), the effect of modifier nature and percentage were studied with two reference oils, argan and rapeseed, chosen for their different and well-known TG composition. The analytical method was developed from previous studies performed with fully porous particles (FPP). Optimized conditions with three Kinetex were as follows: 17°C, 12% of ACN/MeOH (90/10; v/v). With these conditions, and by using an increased length of Kinetex C18 column (60cm), another additional column was selected from ten different commercial SPP C18 bonded phases, by applying a Derringer function on varied parameters: theoretical plate number (TPN), separation index (SI) for critical pairs of peaks (the peaks of compounds difficult to separate due to subtle structural differences), the analysis duration, and the total peak number. This function normalizes the values of any parameters, between 0 and 1, from the worst value to the better, allowing to take account of various parameters in the final

  16. Separation control in low pressure turbines using plasma actuators with passing wakes

    Science.gov (United States)

    Burman, Debashish

    A Dielectric Barrier Discharge (DBD) plasma actuator is operated in flow over the suction surface of a Pack-B Low Pressure Turbine (LPT) airfoil at a Reynolds number of 50,000 (based on exit velocity and suction surface length) and inlet free-stream turbulence intensity of 2.5%. Preliminary characterization studies were made of the effect of varying actuator pulsing frequency and duty cycle, actuator edge effects, and orientation of the actuator with the flow. Flow control was demonstrated with the actuator imparting momentum opposite to the stream-wise flow direction, showing that it is possible to use disturbances alone to destabilize the flow and effect transition. No frequencies of strong influence were found over the range tested, indicating that a broad band of effective frequencies exists. Edge effects were found to considerably enhance separation control. Total pressure measurements of the flow without passing wakes were taken using a glass total-pressure tube. Corrections for streamline displacement due to shear and wall effects were made, and comparisons with previous hot-wire measurements were used to validate data. Performance features of conventional two-electrode and a novel three-electrode actuator configuration were compared. Hot-wire anemometry was used to take time-varying ensemble-averaged near-wall velocity measurements of the flow with periodic passing wakes. Corrections were made for near-wall effects, temperature effects, and interference of the electric field. The wakes were generated by a wake generator mechanism located upstream of the airfoil passage. The near-suction-surface total pressure field (flow without wakes) and velocity field (flow with wakes) in the trailing part of the airfoil passage, and the wall-normal gradient of these quantities, were used to demonstrate effective prevention of flow separation using the plasma actuator. Both flows (with and without passing wakes) showed fully attached flow (or very thin separation zones

  17. Low-pressure foaming: a novel method for the fabrication of porous scaffolds for tissue engineering.

    Science.gov (United States)

    Chung, Eun Ji; Sugimoto, Matthew; Koh, Jason L; Ameer, Guillermo A

    2012-02-01

    Scaffolds for tissue engineering applications must incorporate porosity for optimal cell seeding, tissue ingrowth, and vascularization, but common fabrication methods for achieving porosity are incompatible with a variety of polymers, limiting widespread use. In this study, porous scaffolds consisting of poly(1,8-octanediol-co-citrate) (POC) containing hydroxyapatite nanocrystals (HA) were fabricated using low-pressure foaming (LPF). LPF is a novel method of fabricating an interconnected, porous scaffold with relative ease. LPF takes advantage of air bubbles that act as pore nucleation sites during a polymer mixing step. Vacuum is applied to expand the nucleation sites into interconnected pores that are stabilized through cross-linking. POC was combined with 20%, 40%, and 60% by weight HA, and the effect of increasing HA particle content on porosity, mechanical properties, and alkaline phosphatase (ALP) activity of human mesenchymal stem cells (hMSC) was evaluated. The effect of the prepolymer viscosity on porosity and the mechanical properties of POC with 40% by weight HA (POC-40HA) were also assessed. POC-40HA scaffolds were also implanted in an osteochondral defect of a rabbit model, and the explants were assessed at 6 weeks using histology. With increasing HA content, the pore size of POC-HA scaffolds can be varied (85 to 1,003 μm) and controlled to mimic the pore size of native trabecular bone. The compression modulus increased with greater HA content under dry conditions and were retained to a greater extent than with porous scaffolds fabricated using salt-leaching under wet conditions. Furthermore, all POC-HA scaffolds prepared using LPF supported hMSC attachment, and an increase in ALP activity correlated with an increase in HA content. An increase in the prepolymer viscosity resulted in increased compression modulus, greater distance between pores, and less porosity. After 6 weeks in vivo, cell and tissue infiltration was present throughout the scaffold

  18. Laser-light backscattering response to water content and proteolysis in dry-cured ham

    DEFF Research Database (Denmark)

    Fulladosa, E.; Rubio-Celorio, M.; Skytte, Jacob Lercke

    2017-01-01

    Laser backscattering imaging (LBI) is a low-cost technology proposed to determine non-invasively composition and microstructural characteristics of agro food and dairy products. The aim of this work was to define the effect of different acquisition conditions (wavelength, object distance and angle...... of laser incidence) and to analyse the laser-light backscattering changes caused by additional hot air drying and proteolysis of dry-cured ham slices. The feasibility of the technology to determine water content and proteolysis (which is related to textural characteristics) of commercial sliced dry......-cured ham was also evaluated. Results showed that a red laser (635 nm) is more convenient than a green laser (532 nm) to analyse dry-cured ham but no preferable angle or object distance to evaluate dryness or proteolysis was found. Nevertheless, light scattering parameters were modified depending...

  19. Molecular characterization of a proteolysis-resistant lipase from Bacillus pumilus SG2

    Directory of Open Access Journals (Sweden)

    R. Sangeetha

    2014-06-01

    Full Text Available Proteolysis-resistant lipases can be well exploited by industrial processes which employ both lipase and protease as biocatalysts. A proteolysis resistant lipase from Bacillus pumilus SG2 was isolated, purified and characterized earlier. The lipase was resistant to native and commercial proteases. In the present work, we have characterized the lip gene which encodes the proteolysis-resistant lipase from Bacillus pumilus SG2. The parameters and structural details of lipase were analysed. The lip gene consisted of 650 bp. The experimental molecular weight of SG2 lipase was nearly double that of its theoretical molecular weight, thus suggesting the existence of the functional lipase as a covalent dimer. The proteolytic cleavage sites of the lipase would have been made inaccessible by dimerisation, thus rendering the lipase resistant to protease.

  20. The beneficial role of proteolysis in skeletal muscle growth and stress adaptation.

    Science.gov (United States)

    Bell, Ryan A V; Al-Khalaf, Mohammad; Megeney, Lynn A

    2016-01-01

    Muscle atrophy derived from excessive proteolysis is a hallmark of numerous disease conditions. Accordingly, the negative consequences of skeletal muscle protein breakdown often overshadow the critical nature of proteolytic systems in maintaining normal cellular function. Here, we discuss the major cellular proteolysis machinery-the ubiquitin/proteosome system, the autophagy/lysosomal system, and caspase-mediated protein cleavage-and the critical role of these protein machines in establishing and preserving muscle health. We examine how ordered degradation modifies (1) the spatiotemporal expression of myogenic regulatory factors during myoblast differentiation, (2) membrane fusion during myotube formation, (3) sarcomere remodeling and muscle growth following physical stress, and (4) energy homeostasis during nutrient deprivation. Finally, we review the origin and etiology of a number of myopathies and how these devastating conditions arise from inborn errors in proteolysis.

  1. Mass Spectrometry Guided In Situ Proteolysis to Obtain Crystals for X-ray Structure Determination

    Energy Technology Data Exchange (ETDEWEB)

    Gheyi, Tarun; Rodgers, Logan; Romero, Richard; Sauder, J. Michael; Burley, Stephen K. (Lilly)

    2012-04-30

    A strategy for increasing the efficiency of protein crystallization/structure determination with mass spectrometry has been developed. This approach combines insights from limited proteolysis/mass spectrometry and crystallization via in situ proteolysis. The procedure seeks to identify protease-resistant polypeptide chain segments from purified proteins on the time-scale of crystal formation, and subsequently crystallizing the target protein in the presence of the optimal protease at the right relative concentration. We report our experience with 10 proteins of unknown structure, two of which yielded high-resolution X-ray structures. The advantage of this approach comes from its ability to select only those structure determination candidates that are likely to benefit from application of in situ proteolysis, using conditions most likely to result in formation of a stable proteolytic digestion product suitable for crystallization.

  2. Far infrared-assisted encapsulation of filter paper strips in poly(methyl methacrylate) for proteolysis.

    Science.gov (United States)

    Chen, Qiwen; Bao, Huimin; Zhang, Luyan; Chen, Gang

    2016-02-01

    Filter paper strips were enclosed between two poly(methyl methacrylate) plates to fabricate paper-packed channel microchips under pressure in the presence of far infrared irradiation. After the enclosed paper strip was oxidized by periodate, trypsin was covalently immobilized in them to fabricate microfluidic proteolysis bioreactor. The feasibility and performance of the unique bioreactor were demonstrated by digesting BSA and lysozyme. The results were comparable to those of conventional in-solution proteolysis while the digestion time was significantly reduced to ∼18 s. The suitability of the microfluidic paper-based bioreactors to complex proteins was demonstrated by digesting human serum.

  3. Studies of THGEM-based detector at low-pressure Hydrogen/Deuterium, for AT-TPC applications

    CERN Document Server

    Cortesi, Marco; Mittig, Wolfgang; Bazin, Daniel; Beceiro-Novo, Saul; Stolz, Andreas

    2015-01-01

    We study the performance of single- and double- THick Gas Electron Multiplier (THGEM) detectors in pure Hydrogen and Deuterium at low pressures, in the range of 100-450 Torr. The effect of the pressure on the maximum achievable gain, ion-back flow and long-term gain stability are investigated for single and double cascade detectors. In particular, it was found that maximum achievable gains above 10^4, from single-photoelectrons avalanche, can be achieved for pressures of 200 Torr and above; for lower pressure the gains are limited by avalanche-induced secondary effects to a values of around 103. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particular for applications of THGEM end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics.

  4. Development and field application of a novel emulsion system O/W for well drilling of low pressure reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Arellano, J.; Ojeda, A.; Blanco, J.; Medina, N.; Gutierrez, X.; Carrasquero, M.; Briceno, H. [PDVSA (Venezuela)

    2011-07-01

    In Venezuela, there are important reserves of hydrocarbons in low pressure reservoirs but accessing to these reserves is a major challenge. This paper presents a new oil in water emulsion (O/W) system, using fatty acids and their salts as surfactant additives for use in such reservoirs, and the results obtained in field applications. Emulsions were prepared using two oil types and multiple salt (KCl) concentrations. Tests were then conducted to determine their thermal stability and return permeability percentage. Results showed good tolerance of high concentrations of KCl, as well as good stability under high temperatures and a good rheological behavior. The field test showed that the O/W emulsion system presents technological and cost advantages over other commercial technologies. This paper presented a new oil in water emulsion system which is a good alternative to water based fluids for well drilling in low pressure reservoirs.

  5. [Change in the properties of titanium alloys exposed to a stream of high-frequency, low-pressure radiating plasma].

    Science.gov (United States)

    Matukhnov, V M; Abdullin, I Sh; Altareva, G I; Zheltukhin, V S; Gerasev, G P

    1985-01-01

    The Nitrogen-Argon plasma of a high-frequency low-pressure discharge is proven to be very effective in machining pieces made of titanium alloys. The optimum operating modes are found that improve surface microhardness, reduce surface roughness, increase durability and endurance limits, and do not produce the effect on the residual stress. The operating modes have been tested with great success in machining microsurgical and ultrasonic surgical instruments.

  6. Evaluation of shallow-placed low pressure distribution systems in soils marginally suited for on-site waste treatment

    OpenAIRE

    Ijzerman, M. Marian

    1990-01-01

    Two shallow-placed low pressure distribution (LPD) systems were evaluated in soils that were marginally suited for a conventional on-site wastewater disposal system (OSWDS) because of low hydraulic conductivity and shallow depth of soil to bedrock. The soils used for this study were Edom (fine, illitic, mesic, Typic Hapludult) and Penn-Bucks soil (fine-loamy, mixed, mesic, ultic Hapludult). In the Edam soil, the LPD system was installed with four subsystem designs operating: a ...

  7. An experimental study of amphibole stability in low-pressure granitic magmas and a revised Al-in-hornblende geobarometer

    Science.gov (United States)

    Mutch, E. J. F.; Blundy, J. D.; Tattitch, B. C.; Cooper, F. J.; Brooker, R. A.

    2016-10-01

    We report new experimental data on the composition of magmatic amphiboles synthesised from a variety of granite (sensu lato) bulk compositions at near-solidus temperatures and pressures of 0.8-10 kbar. The total aluminium content (Altot) of the synthetic calcic amphiboles varies systematically with pressure ( P), although the relationship is nonlinear at low pressures (barometer expression is comparable to the precision with which near-solidus amphibole rim composition can be characterised.

  8. The efficacy of low-pressure lavage with different irrigating solutions to remove adherent bacteria from bone.

    Science.gov (United States)

    Bhandari, M; Adili, A; Schemitsch, E H

    2001-03-01

    Recent studies have suggested that high-pressure irrigation may have adverse effects on bone. However, the use of low-pressure irrigation may not remove all adherent bacteria from bone. The type of irrigating solution may be an important factor in the removal of adherent bacteria with pulsatile lavage. In this study, we compared the effects of various irrigating solutions on the number and function of osteoblasts and osteoclasts and we examined the effectiveness of these solutions in removing adherent bacteria from bone. To examine the effect of irrigating solutions on the number and activity of osteoblasts, we isolated calvarial cells from newborn C57BI/6 mice and exposed the cells to equivalent concentrations of ethanol, povidoneiodine, liquid soap, antimicrobial wash (50 U/L of bacitracin), or chlorhexidine gluconate, for two, ten, or twenty minutes. The cells were then cultured in the presence of bone-nodule-enhancing medium (beta-glycerophosphate and ascorbic acid) for twenty-one days. The medium was changed every three or four days. Mineralized nodules were stained with alizarin red S, and osteoblasts were stained with a histochemical stain for alkaline phosphatase. Osteoclasts were identified with tartrate-resistant acid-phosphatase staining. In a second experiment, canine cortical tibiae were contaminated with Staphylococcus aureus for six hours and subjected to different irrigating solutions with or without low-pressure lavage. Bacterial colony-forming units were quantitated under each set of conditions. Each solution resulted in a time-dependent decrease in the number of calvarial osteoblasts and osteoclasts compared with that in the controls. The 1% soap solution resulted in greater preservation of both alkaline-phosphatase activity and bone-nodule formation than did the other solutions. Moreover, the soap solution preserved the number of osteoclasts to the greatest extent. The povidone-iodine and chlorhexidine-gluconate solutions resulted in the largest

  9. Immobilization of trypsin on miniature incandescent bulbs for infrared-assisted proteolysis

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Huimin; Bao, Huimin; Zhang, Luyan; Chen, Gang, E-mail: gangchen@fudan.edu.cn

    2014-10-03

    Highlights: • Trypsin was immobilized on miniature incandescent bulbs via chitosan coating. • The bulbs acted as enzymatic reactors and the generators of infrared radiation. • The bulb bioreactors were successfully employed in infrared-assisted proteolysis. • The proteolysis could accomplish within 5 min with high sequence coverages. - Abstract: A novel efficient proteolysis approach was developed based on trypsin-immobilized miniature incandescent bulbs and infrared (IR) radiation. Trypsin was covalently immobilized in the chitosan coating on the outer surface of miniature incandescent bulbs with the aid of glutaraldehyde. When an illuminated enzyme-immobilized bulb was immersed in protein solution, the emitted IR radiation could trigger and accelerate heterogeneous protein digestion. The feasibility and performance of the novel proteolysis approach were demonstrated by the digestion of hemoglobin (HEM), cytochrome c (Cyt-c), lysozyme (LYS), and ovalbumin (OVA) and the digestion time was significantly reduced to 5 min. The obtained digests were identified by MALDI-TOF-MS with the sequence coverages of 91%, 77%, 80%, and 52% for HEM, Cyt-c, LYS, and OVA (200 ng μL{sup −1} each), respectively. The suitability of the prepared bulb bioreactors to complex proteins was demonstrated by digesting human serum.

  10. Calpain-catalyzed proteolysis of human dUTPase specifically removes the nuclear localization signal peptide.

    Directory of Open Access Journals (Sweden)

    Zoltán Bozóky

    Full Text Available BACKGROUND: Calpain proteases drive intracellular signal transduction via specific proteolysis of multiple substrates upon Ca(2+-induced activation. Recently, dUTPase, an enzyme essential to maintain genomic integrity, was identified as a physiological calpain substrate in Drosophila cells. Here we investigate the potential structural/functional significance of calpain-activated proteolysis of human dUTPase. METHODOLOGY/PRINCIPAL FINDINGS: Limited proteolysis of human dUTPase by mammalian m-calpain was investigated in the presence and absence of cognate ligands of either calpain or dUTPase. Significant proteolysis was observed only in the presence of Ca(II ions, inducing calpain action. The presence or absence of the dUTP-analogue α,β-imido-dUTP did not show any effect on Ca(2+-calpain-induced cleavage of human dUTPase. The catalytic rate constant of dUTPase was unaffected by calpain cleavage. Gel electrophoretic analysis showed that Ca(2+-calpain-induced cleavage of human dUTPase resulted in several distinctly observable dUTPase fragments. Mass spectrometric identification of the calpain-cleaved fragments identified three calpain cleavage sites (between residues (4SE(5; (7TP(8; and (31LS(32. The cleavage between the (31LS(32 peptide bond specifically removes the flexible N-terminal nuclear localization signal, indispensable for cognate localization. CONCLUSIONS/SIGNIFICANCE: Results argue for a mechanism where Ca(2+-calpain may regulate nuclear availability and degradation of dUTPase.

  11. Characterization of linear forms of the circular enterocin AS-48 obtained by limited proteolysis

    NARCIS (Netherlands)

    Montalbán-López, Manuel; Spolaore, Barbara; Pinato, Odra; Martínez-Bueno, Manuel; Valdivia, Eva; Maqueda, Mercedes; Fontana, Angelo

    2008-01-01

    AS-48 is a 70-residue circular peptide from Enterococcus faecalis with a broad antibacterial activity. Here, we produced by limited proteolysis a protein species carrying a single nicking and fragments of 55 and 38 residues. Nicked AS-48 showed a lower helicity by far-ultraviolet circular dichroism

  12. Muscle type influences u-calpain mediated troponin-T proteolysis in bovine myofibrils in vitro

    Science.gov (United States)

    The influence of muscle type on postmortem proteolysis remains largely unexplored. Previous attempts to classify muscle tenderness based on ‘muscle type’ indicated differences in tenderness were due to variations in proteolytic enzyme levels, but failed to account for the influence of sarcomere leng...

  13. Variation in proteolysis, sarcomere length, collagen content, and tenderness among major pork muscles.

    Science.gov (United States)

    Wheeler, T L; Shackelford, S D; Koohmaraie, M

    2000-04-01

    The objectives of this experiment were to determine the extent of variation in proteolysis, sarcomere length, and collagen content among pork muscles and the association of those factors with tenderness variation among muscles at 1 d postmortem. Twenty-three white composite barrows were slaughtered and carcasses (66 kg) were chilled at 0 degrees C for 24 h. At 1 d postmortem, the longissimus lumborum, biceps femoris, semimembranosus, semitendinosus, and triceps brachii, long head were dissected from one side of each carcass and frozen. Trained sensory panelists evaluated tenderness, amount of connective tissue, juiciness, and pork flavor intensity of grilled (70 degrees C) chops on 8-point scales. Raw chops were used for total collagen content, sarcomere length, and the extent of desmin proteolysis. Tenderness ratings were highest (P muscles were .54 (semimembranosus), .34 (semitendinosus), .36 (triceps branchii), and .17 (biceps femorus). Total collagen was highest (P muscle), followed by triceps branchii (6.0 mg/g) and semitendinosus (5.3 mg/g), and lowest for semimembranosus (4.5 mg/g) and longissimus lumborum (4.1 mg/g). Sarcomere length was longest (P variation in tenderness rating among all samples. Piecewise linear regression was used to account for the interaction of sarcomere length with proteolysis and collagen. This analysis accounted for 72% of the variation in tenderness rating. Variation in collagen, proteolysis, and sarcomere length and the degree of their interaction with one another determine the tenderness of individual muscles.

  14. Use of high-gradient magnetic fishing for reducing proteolysis during fermentation

    DEFF Research Database (Denmark)

    Maury, Trine Lütken; Ottow, Kim Ekelund; Brask, Jesper

    2012-01-01

    Proteolysis during fermentation may have a severe impact on the yield and quality of a secreted product. In the current study, we demonstrate the use of high-gradient magnetic fishing (HGMF) as an efficient alternative to the more conventional methods of preventing proteolytic degradation...

  15. Hyperosmotic Stress Induces Tau Proteolysis by Caspase-3 Activation in SH-SY5Y Cells.

    Science.gov (United States)

    Olivera-Santa Catalina, Marta; Caballero-Bermejo, Montaña; Argent, Ricardo; Alonso, Juan C; Cuenda, Ana; Lorenzo, María J; Centeno, Francisco

    2016-12-01

    Tau is a microtubule-associated protein implicated in the pathogenesis of Alzheimer's disease and other related tauopathies. In this subset of neurodegenerative disorders, Tau auto-assembles into insoluble fibrils that accumulate in neurons as paired helical filaments (PHFs), promoting cellular dysfunction and cytotoxic effects. Growing evidence suggests that abnormal post-translational regulation, mainly hyperphosphorylation and aberrant cleavage, drives Tau to this pathological state. In this work we show that sorbitol-induced hyperosmotic stress promotes Tau proteolysis in SH-SY5Y neuroblastoma cells. The appearance of cleaved Tau was preceded by the activation of μ-calpain, the proteasome system and caspase-3. Tau proteolysis was completely prevented by caspase-3 inhibition but unaffected by neither the proteasome system nor μ-calpain activity blockade. Concomitantly, hyperosmotic stress induced apoptosis in SH-SY5Y cells, which was efficiently avoided by the inhibition of caspase-3 activity. Altogether, our results provide the first evidence that Tau protein is susceptible to caspase-3 proteolysis under hyperosmotic stress and suggest a positive relationship between Tau proteolysis and apoptosis in SH-SY5Y cells. J. Cell. Biochem. 117: 2781-2790, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Proteolysis produced within biofilms of bacterial isolates from raw milk tankers.

    Science.gov (United States)

    Teh, Koon Hoong; Flint, Steve; Palmer, Jon; Andrewes, Paul; Bremer, Phil; Lindsay, Denise

    2012-06-15

    In this study, six bacterial isolates that produced thermo-resistant enzymes isolated from the internal surfaces of raw milk tankers were evaluated for their ability to produce proteolysis within either single culture biofilms or co-culture biofilms. Biofilms were formed in an in vitro model system that simulated the upper internal surface of a raw milk tanker during a typical summer's day of milk collection in New Zealand. The bacterial isolates were further evaluated for their ability to form biofilms at 25, 30 and 37°C. Mutual and competitive effects were observed in some of the co-culture biofilms, with all isolates being able to form biofilms in either single culture or co-culture at the three temperatures. The proteolysis was also evaluated in both biofilms and corresponding planktonic cultures. The proteolysis per cell decreased as the temperature of incubation (20-37°C) increased. Furthermore, mutualistic interactions in terms of proteolysis were observed when cultures were grown as co-culture biofilms. This is the first study to show that proteolytic enzymes can be produced in biofilms on the internal surfaces of raw milk tankers. This has important implications for the cleaning and the temperature control of raw milk transport tankers.

  17. Activation of proteolysis by calpains and structural changes in human paroxysmal and persistent atrial fibrillation

    NARCIS (Netherlands)

    Brundel, BJJM; Ausma, J; van Gelder, IC; Van Der Want, JJL; van Gilst, WH; Crijns, HJGM; Henning, RH

    2002-01-01

    Objective: Atrial fibrillation (AF) is accompanied by electrical. structural and ion-channel protein remodeling. We tested if proteolysis by calpain and proteasome is activated during AF. and studied the relation with the remodeling processes. Methods: Right atrial appendages were obtained from pati

  18. Hybrid simulations of solenoidal radio-frequency inductively coupled hydrogen discharges at low pressures

    Science.gov (United States)

    Yang, Wei; Li, Hong; Gao, Fei; Wang, You-Nian

    2016-12-01

    In this article, we have described a radio-frequency (RF) inductively coupled H2 plasma using a hybrid computational model, incorporating the Maxwell equations and the linear part of the electron Boltzmann equation into global model equations. This report focuses on the effects of RF frequency, gas pressure, and coil current on the spatial profiles of the induced electric field and plasma absorption power density. The plasma parameters, i.e., plasma density, electron temperature, density of negative ion, electronegativity, densities of neutral species, and dissociation degree of H2, as a function of absorption power, are evaluated at different gas pressures. The simulation results show that the utilization efficiency of the RF source characterized by the coupling efficiency of the RF electric field and power to the plasma can be significantly improved at the low RF frequency, gas pressure, and coil current, due to a low plasma density in these cases. The densities of vibrational states of H2 first rapidly increase with increasing absorption power and then tend to saturate. This is because the rapidly increased dissociation degree of H2 with increasing absorption power somewhat suppresses the increase of the vibrational states of H2, thus inhibiting the increase of the H-. The effects of absorption power on the utilization efficiency of the RF source and the production of the vibrational states of H2 should be considered when setting a value of the coil current. To validate the model simulations, the calculated electron density and temperature are compared with experimental measurements, and a reasonable agreement is achieved.

  19. Effect of driving frequency on the electron-sheath interaction and electron energy distribution function in a low pressure capacitively coupled plasmas

    Science.gov (United States)

    Sharma, Sarveshwar; Sirse, Nishant; Kaw, Predhiman; Turner, Miles; Ellingboe, Albert R.; InstitutePlasma Research, Gandhinagar, Gujarat Team; School Of Physical Sciences; Ncpst, Dublin City University, Dublin 9, Ireland Collaboration

    2016-09-01

    The effect of driving frequency (27.12-70 MHz) on the electron-sheath interaction and electron energy distribution function (EEDF) is investigated in a low pressure capacitive discharges using a self-consistent particle-in-cell simulation. At a fixed discharge voltage the EEDF evolves from a strongly bi-Maxwellian at low frequency, 27.12 MHz, to a convex type distribution at an intermediate frequency, 50 MHz, and finally becomes a weak biMaxwellian above 50 MHz. The EEDF evolution leads to a two-fold increase in the effective electron temperature up to 50 MHz, whereas the electron density remains constant in this range. After 50MHz, the electron density increases rapidly and the electron temperature decreases. The transition is caused by the transient electric field excited by bursts of high energy electrons interacting strongly with the sheath edge. Above the transition frequency, high energy electrons are confined between two sheaths which increase the ionization probability and thus the plasma density increases.

  20. Start-up phase of the HELOKA-LP low pressure helium test facility for IFMIF irradiation modules

    Energy Technology Data Exchange (ETDEWEB)

    Schlindwein, Georg, E-mail: georg.schlindwein@kit.edu [Institute for Neutron Physics and Reactor Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Arbeiter, Frederik; Freund, Jana [Institute for Neutron Physics and Reactor Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) succesfully taken to operation at the end of 2009. Black-Right-Pointing-Pointer Verified that HELOKA-LP fulfils all requirements to test the High Flux Test Module (HFTM). Black-Right-Pointing-Pointer Some improvements could be done (e.g. reduction of power consumption, enhancement of control path parameters). Black-Right-Pointing-Pointer We obtained a chronological sequence of the helium gas impurity which is important for the International Fusion Irradiation Facility (IFMIF). - Abstract: As part of the Engineering Validation and Engineering Design Activities (EVEDA) for the International Fusion Materials Irradiation Facility (IFMIF) , it is foreseen to design and test a 1:1 scale prototype of the IFMIF High Flux Test Module (HFTM) . The module has been designed to be cooled by a low pressure helium gas flowing through minichannels to remove the nuclear heat. The Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) has been designed to provide coolant at 1:1 HFTM operational conditions: massflow 12-120 g/s, inlet pressure 0.3-0.6 MPa, inlet temperature RT - 250 Degree-Sign C. A secondary objective is to use the experience gained with HELOKA-LP for the planning of the IFMIF helium cooling system. The facility has been put into operation in 2009, and has since then been in a test and optimization phase. It was proven, that the above mentioned requirements for the facility are achieved. The paper describes the process layout and components of the facility. The performance is characterized by the results of several steady state and transient benchmark tests. Typical start-up and transition times relevant for the operation mode in the IFMIF irradiation campaigns are obtained. Additionally first results on the impurity ingress and the cooling gas chemistry are described.

  1. Standard values of fugacity for sulfur which are self-consistent with the low-pressure phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, Robert A., E-mail: rob.marriott@ucalgary.ca [Alberta Sulphur Research Ltd., University of Calgary, Alberta (Canada); Wan, Herman H. [Alberta Sulphur Research Ltd., University of Calgary, Alberta (Canada)

    2011-08-15

    Highlights: > We have provided a method for calculating the fugacity for elemental sulfur. > Calculated sulfur fugacities can be used in sulfur equilibrium models. > The sulfur fugacities also can be used to locate the phase changes in the low-pressure phase diagram. > We have measured the 'natural' melting point of sulfur, and found it to be T = 388.5 {+-} 0.2 K. - Abstract: A method for calculating the fugacity of pure sulfur in the {alpha}-solid, {beta}-solid and liquid phase regions has been reported for application to industrial equilibrium conditions, e.g., high-pressure solubility of sulfur in sour gas. The fugacity calculations are self-consistent with the low-pressure phase diagram. As recently discussed by Ferreira and Lobo , empirical fitting of the experimental data does not yield consistent behaviour for the low-pressure phase diagram of elemental sulfur. In particular, there is a discrepancy between the vapour pressure of {beta}-solid (monoclinic) and liquid sulfur at the fusion temperature. We have provided an alternative semi-empirical approach which allows one to calculate values of the fugacity at conditions removed from the conditions of the pure sulfur phase transitions. For our approach, we have forced the liquid vapour pressure to equal the {beta}-solid vapour pressure at the {beta}-l-g triple point corresponding to the 'natural' fusion temperature for {beta}-solid. Many studies show a higher 'observed' fusion temperature for elemental sulfur. The non-reversible conditions for 'observed' fusion conditions for elemental sulfur result from a kinetically hindered melt which causes some thermodynamic measurements to be related to a metastable S{sub 8} liquid. We have measured the 'natural' fusion temperature, T{sub fus}{sup {beta}}(exp.)=(388.5{+-}0.2)K at p = 89.9 kPa, which is consistent with literature fusion data at higher-pressures. Using our semi-empirical approach, we have used or found the

  2. Combustion processes for a low pressure gasoline direct injection; Brennverfahrenskonzepte fuer eine Niederdruck-Direkteinspritzung bei Ottomotoren

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Stephan; Trattner, Alexander; Eichlseder, Helmut; Kirchberger, Roland [Technische Univ., Graz (Austria). Inst. fuer Verbrennungskraftmaschinen und Thermodynamik

    2011-07-15

    The gasoline direct injection becomes more and more important for small engines used in passenger cars. Lowering injection pressure and thus costs could enable the introduction of this technology in the small engine segment offering an alternative to today's MPFI engines. The results of these investigations made at TU Graz show the potential of low pressure direct injection in terms of improvement over standard MPFI engines (fuel economy, emissions, and engine operation stability) and reduced costs compared to high pressure GDI systems. (orig.)

  3. Low Pressure Radio-Frequency Oxygen Plasma Induced Oxidation of Titanium – Surface Characteristics and Biological Effects

    OpenAIRE

    Wan-Yu Tseng; Sheng-Hao Hsu; Chieh-Hsiun Huang; Yu-Chieh Tu; Shao-Chin Tseng; Hsuen-Li Chen; Min-Huey Chen; Wei-Fang Su; Li-Deh Lin

    2013-01-01

    OBJECTIVE: This research was designed to investigate the effects of low pressure radio-frequency (RF) oxygen plasma treatment (OPT) on the surface of commercially pure titanium (CP-Ti) and Ti6Al4V. Surface topography, elemental composition, water contact angle, cell viability, and cell morphology were surveyed to evaluate the biocompatibility of titanium samples with different lengths of OP treating time. MATERIALS AND METHODS: CP-Ti and Ti6Al4V discs were both classified into 4 groups: untre...

  4. Kinetics of low pressure CVD growth of SiO2 on InP and Si

    Science.gov (United States)

    Iyer, R.; Lile, D. L.

    1988-01-01

    The kinetics of low pressure CVD growth of SiO2 from SiH4 and O2 has been investigated for the case of an indirect (remote) plasma process. Homogeneous (gas phase) and heterogeneous operating ranges have been experimentally identified. The process was shown to be consistent within the heterogeneous surface-reaction dominated range of operation. A kinetic rate equation is given for growth at 14 W RF power input and 400 mtorr total pressure on both InP and Si substrates. The process exhibits an activation energy of 8.4 + or - 0.6 kcal/mol.

  5. Inactivation of Cryptosporidium parvum oocysts using medium- and low-pressure ultraviolet radiation.

    Science.gov (United States)

    Craik, S A; Weldon, D; Finch, G R; Bolton, J R; Belosevic, M

    2001-04-01

    The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts was studied using a collimated beam apparatus. Experiments were conducted using parasites suspended in both filtered surface water and phosphate buffered laboratory water. Inactivation of oocysts was measured as reduction in infectivity using a CD-1 neonatal mouse model and was found to be a non-linear function of UV dose over the range of germicidal doses tested (0.8-119 mJ/cm2). Oocyst inactivation increased rapidly with UV dose at doses less than 25 mJ/cm2 with two and three log-units inactivation at approximately 10 and 25 mJ/cm2, respectively. The cause of significant leveling-off and tailing in the UV inactivation curve at higher doses was not determined. Maximum measured oocyst inactivation ranged from 3.4 to greater than 4.9 log-units and was dependent on different batches of parasites. Water type and temperature, the concentration of oocysts in the suspension, and the UV irradiance did not have significant impacts on oocyst inactivation. When compared on the basis of germicidal UV dose, the oocysts were equally sensitive to low- and medium-pressure UV radiation. With respect to Cryptosporidium, both low- and medium-pressure ultraviolet radiation are attractive alternatives to conventional chemical disinfection methods in drinking water treatment.

  6. Protein aggregation and amyloid fibril formation by an SH3 domain probed by limited proteolysis.

    Science.gov (United States)

    Polverino de Laureto, Patrizia; Taddei, Niccolò; Frare, Erica; Capanni, Cristina; Costantini, Silvia; Zurdo, Jesús; Chiti, Fabrizio; Dobson, Christopher M; Fontana, Angelo

    2003-11-14

    The SH3 domains are small protein modules of 60-85 amino acid residues that are found in many proteins involved in intracellular signal transduction. The SH3 domain of the p85alpha subunit of bovine phosphatidylinositol 3'-kinase (PI3-SH3) under acidic solution adopts a compact denatured state from which amyloid fibrils are readily formed. This aggregation process has been found to be modulated substantially by solution conditions. Here, we have analyzed the conformational features of the native and acid denatured states of PI3-SH3 by limited proteolysis experiments using proteinase K and pepsin, respectively. Moreover, we have analyzed the propensity of PI3-SH3 to be hydrolyzed by pepsin at different stages in the process of aggregation and amyloid formation at pH 1.2 and 2.0 and compared the sites of proteolysis under these conditions with the conformational features of both native and aggregated PI3-SH3. The results demonstrate that the denatured state of PI3-SH3 formed at low pH is relatively resistant to proteolysis, indicating that it is partially folded. The long loop connecting beta-strands b and c in the native protein is the region in this structure most susceptible to proteolysis. Remarkably, aggregates of PI3-SH3 that are formed initially from this denatured state in acid solution display enhanced susceptibility to proteolysis of the long loop, suggesting that the protein becomes more unfolded in the early stages of aggregation. By contrast, the more defined amyloid fibrils that are formed over longer periods of time are completely resistant to proteolysis. We suggest that the protein aggregates formed initially are relatively dynamic species that are able readily to reorganize their interactions to enable formation of very well ordered fibrillar structures. In addition, the disordered and non-native character of the polypeptide chains in the early aggregates could be important in determining the high cytotoxicity that has been revealed in previous

  7. A comparative study on the pulsed UV and the low-pressure UV inactivation of a range of microbial species in water.

    Science.gov (United States)

    Garvey, Mary; Thokala, Nikhil; Rowan, Neil

    2014-12-01

    Research into alternative methods of disinfecting water and wastewater has proven necessary due to the emergence of chlorine-resistant organisms and the disinfection byproducts associated with chlorine use. The use of UV light to inactivate microbial species has proven effective, however; standard UV lamps have proven to be less effective in their ability to inactivate parasites and bacterial endospores in water treatment settings. Pulsed UV (PUV) light may potentially provide a novel alternative to water and wastewater disinfection. Research outlined in this study assesses the potential of a novel PUV system for the rapid and reproducible inactivation of a range of test species including Bacillus endospores. In comparison to standard low-pressure (LP) UV lamps, this PUV system provided significantly higher levels of inactivation for all test species. Furthermore, there was a remarkable decrease in time needed to obtain significant inactivation rates following treatment with PUV compared to LP-UV. With the PUV system, a 70-second treatment time (7.65 μJ/cm2) resulted in similar inactivation rates of Bacillus endospores to that of the LP-UV inactivation of their vegetative counterpart. Also, at PUV doses exceeding 4.32 J/cm2, there was not a significant difference in the PUV inactivation of Bacillus endospores in the absence or presence of 10 ppm organic matter. However, the presence of organic matter resulted in a significant reduction in microbial inactivation for all treatment doses using the LP-UV system. The findings of this study suggest that PUV technology may provide a rapid effective method for the disinfection of water and wastewater.

  8. Design and development of low pressure evaporator/condenser unit for water-based adsorption type climate control systems

    Science.gov (United States)

    Venkataramanan, Arjun; Rios Perez, Carlos A.; Hidrovo, Carlos H.

    2016-11-01

    Electric vehicles (EVs) are the future of clean transportation and driving range is one of the important parameters which dictates its marketability. In order to increase driving range, electrical battery energy consumption should be minimized. Vapor-compression refrigeration systems currently employed in EVs for climate control consume a significant fraction of the battery charge. Thus, by replacing this traditional heating ventilation and air-conditioning system with an adsorption based climate control system one can have the capability of increasing the drive range of EVs.The Advanced Thermo-adsorptive Battery (ATB) for climate control is a water-based adsorption type refrigeration cycle. An essential component of the ATB is a low pressure evaporator/condenser unit (ECU) which facilitates both the evaporation and condensation processes. The thermal design of the ECU relies predominantly on the accurate prediction of evaporation/boiling heat transfer coefficients since the standard correlations for predicting boiling heat transfer coefficients have large uncertainty at the low operating pressures of the ATB. This work describes the design and development of a low pressure ECU as well as the thermal performance of the actual ECU prototype.

  9. Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography

    Science.gov (United States)

    Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

    2015-03-01

    A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515 nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0 mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55 μg/L, the relative standard deviation (n = 10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5 mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1 h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples.

  10. Low-pressure plasma enhanced immobilization of chitosan on low-density polyethylene for bio-medical applications

    Science.gov (United States)

    Pandiyaraj, K. Navaneetha; Ferraria, Ana Maria; Rego, Ana Maria Botelho do; Deshmukh, Rajendra. R.; Su, Pi-Guey; Halleluyah Mercy, Jr.; Halim, Ahmad Sukari

    2015-02-01

    With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents, among others.

  11. Deactivation of lipopolysaccharide by Ar and H2 inductively coupled low-pressure plasma

    Science.gov (United States)

    Bartis, E. A. J.; Barrett, C.; Chung, T.-Y.; Ning, N.; Chu, J.-W.; Graves, D. B.; Seog, J.; Oehrlein, G. S.

    2014-01-01

    Using an inductively coupled plasma system, we study the effects of direct plasma, plasma-generated high-energy photons in the ultraviolet and vacuum ultraviolet (UV/VUV), and radical treatments on lipopolysaccharide (LPS). LPS is a biomolecule found in the outer membrane of Gram-negative bacteria and a potent stimulator of the immune system composed of polysaccharide and lipid A, which contains six aliphatic chains. LPS film thickness spun on silicon was monitored by ellipsometry while the surface chemistry was characterized before and after treatments by x-ray photoelectron spectroscopy (XPS). Additionally, biological activity was measured using an enzyme-linked immunosorbent assay under (a) a sensitive regime (sub-µM concentrations of LPS) and (b) a bulk regime (above µM concentrations of LPS) after plasma treatments. Direct plasma treatment causes rapid etching and deactivation of LPS in both Ar and H2 feed gases. To examine the effect of UV/VUV photons, a long-pass filter with a cut-off wavelength of 112 nm was placed over the sample. H2 UV/VUV treatment causes material removal and deactivation due to atomic and molecular UV/VUV emission while Ar UV/VUV treatment shows minimal effects as Ar plasma does not emit UV/VUV photons in the transmitted wavelength range explored. Interestingly, radical treatments remove negligible material but cause deactivation. Based on the amphiphilic structure of LPS, we expect a lipid A rich surface layer to form at the air-water interface during sample preparation with polysaccharide layers underneath. XPS shows that H2 plasma treatment under direct and UV/VUV conditions causes oxygen depletion through removal of C-O and O-C = O bonds in the films, which does not occur in Ar treatments. Damage to these groups can remove aliphatic chains that contribute to the pyrogenicity of LPS. Radical treatments from both Ar and H2 plasmas remove aliphatic carbon from the near-surface, demonstrating the important role of neutral species.

  12. Deposition of stable amine coating onto polycaprolactone nanofibers by low pressure cyclopropylamine plasma polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Manakhov, Anton [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Nečas, David [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Čechal, Jan [CEITEC — Central European Institute of Technology, Brno University of Technology, Technická 3058/10, 616 00 Brno (Czech Republic); Pavliňák, David [Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Eliáš, Marek [Plasma Technologies, CEITEC — Central European Institute of Technology, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); and others

    2015-04-30

    Amine-rich films are of high interest for the bio-applications including drug delivery and tissue engineering thanks to their high reactivity allowing the formation of the covalent linkages between biomolecules and a surface. However, the bio-applications of amine-rich films require their good stability in water which is often achieved at large expenses of the amine concentration. Recently, non-toxic cyclopropylamine (CPA) has been applied for the plasma polymerization of films bearing high NH{sub x} environment combined with the moderate thickness loss (20%) after water immersion for 48 h. In this work, the amine-rich film with the NH{sub x} concentration over 7 at.% was deposited on Si substrates and polycaprolactone nanofiber meshes by using CPA plasma polymerization (pulsed mode) in a vertically oriented stainless steel reactor. The substrates were placed at the radio frequency electrode and the ion bombardment caused by direct-current self-bias was suppressed by using high pressure of 50 Pa. Analysis of samples by scanning electron microscopy did not reveal any cracks in the deposited layer formed during a sample immersion in water. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed a slight oxidation of amine groups in water but the film still contained 5 at.% of NH{sub x} (according to the N1s XPS fitting) after the immersion. The rapid oxidation of amine groups was observed during the aging experiment carried out in air at room temperature because FTIR revealed an increase of amide peaks that increased progressively with aging time. However, this oxidation was significantly reduced if the plasma polymer was stored at − 20 °C. Since the films exhibit high amine concentration and very good water stability they have great potential for applications as biocompatible functional coatings. - Highlights: • Cyclopropylamine plasma polymers deposited on polycaprolactone nanofibers • Amine-rich films with high

  13. Actin proteolysis during ripening of dry fermented sausages at different pH values.

    Science.gov (United States)

    Berardo, A; Devreese, B; De Maere, H; Stavropoulou, D A; Van Royen, G; Leroy, F; De Smet, S

    2017-04-15

    In dry fermented sausages, myofibrillar proteins undergo intense proteolysis generating small peptides and free amino acids that play a role in flavour generation. This study aimed to identify small peptides arising from actin proteolysis, as influenced by the type of processing. Two acidification profiles were imposed, in order to mimic the pH normally obtained in southern-type and northern-type dry fermented sausages. The identification of peptides was done by liquid chromatography coupled to mass spectrometry in a data-independent positive mode of acquisition (LC-MS(E)). During manufacturing of the dry fermented sausages, actin was highly proteolysed, especially in nine regions of the sequence. After fermentation, 52 and 42 actin-derived peptides were identified at high and low pH, respectively, which further increased to 66 and 144 peptides, respectively, at the end of ripening. Most peptides were released at the cleavage sites of cathepsins B and D, which thus play an important role.

  14. Monitoring of Enzymatic Proteolysis Using Self-Assembled Quantum Dot-Protein Substrate Sensors

    Directory of Open Access Journals (Sweden)

    Aaron R. Clapp

    2008-01-01

    Full Text Available We have previously utilized hybrid semiconductor quantum dot- (QD- peptide substrates for monitoring of enzymatic proteolysis. In this report, we expand on this sensing strategy to further monitor protein-protease interactions. We utilize QDs self-assembled with multiple copies of dye-labeled proteins as substrates for the sensing of protease activity. Detection of proteolysis is based on changes in the rate of fluorescence resonance energy transfer (FRET between the QDs and the proximal dye-labeled proteins following protein digestion by added enzyme. Our study focused on two representative proteolytic enzymes: the cysteine protease papain and the serine protease endoproteinase K. Analysis of the enzymatic digestion allowed us to estimate minimal values for the enzymatic activities of each enzyme used. Mechanisms of enzymatic inhibition were also inferred from the FRET data collected in the presence of inhibitors. Potential applications of this technology include drug discovery assays and in vivo cellular monitoring of enzymatic activity.

  15. Direct imaging of APP proteolysis in living cells.

    Science.gov (United States)

    Parenti, Niccoló; Del Grosso, Ambra; Antoni, Claudia; Cecchini, Marco; Corradetti, Renato; Pavone, Francesco S; Calamai, Martino

    2017-01-01

    Alzheimer's disease is a multifactorial disorder caused by the interaction of genetic, epigenetic and environmental factors. The formation of cytotoxic oligomers consisting of Aβ peptide is widely accepted as being one of the main key events triggering the development of Alzheimer's disease. Aβ peptide production results from the specific proteolytic processing of the amyloid precursor protein (APP). Deciphering the factors governing the activity of the secretases responsible for the cleavage of APP is still a critical issue. Kits available commercially measure the enzymatic activity of the secretases from cells lysates, in vitro. By contrast, we have developed a prototypal rapid bioassay that provides visible information on the proteolytic processing of APP directly in living cells. APP was fused to a monomeric variant of the green fluorescent protein and a monomeric variant of the red fluorescent protein at the C-terminal and N-terminal (mChAPPmGFP), respectively. Changes in the proteolytic processing rate in transfected human neuroblastoma and rat neuronal cells were imaged with confocal microscopy as changes in the red/green fluorescence intensity ratio. The significant decrease in the mean red/green ratio observed in cells over-expressing the β-secretase BACE1, or the α-secretase ADAM10, fused to a monomeric blue fluorescent protein confirms that the proteolytic site is still accessible. Specific siRNA was used to evaluate the contribution of endogenous BACE1. Interestingly, we found that the degree of proteolytic processing of APP is not completely homogeneous within the same single cell, and that there is a high degree of variability between cells of the same type. We were also able to follow with a fluorescence spectrometer the changes in the red emission intensity of the extracellular medium when BACE1 was overexpressed. This represents a complementary approach to fluorescence microscopy for rapidly detecting changes in the proteolytic processing of

  16. The Golgi apparatus regulates cGMP-dependent protein kinase I compartmentation and proteolysis.

    Science.gov (United States)

    Kato, Shin; Chen, Jingsi; Cornog, Katherine H; Zhang, Huili; Roberts, Jesse D

    2015-06-01

    cGMP-dependent protein kinase I (PKGI) is an important effector of cGMP signaling that regulates vascular smooth muscle cell (SMC) phenotype and proliferation. PKGI has been detected in the perinuclear region of cells, and recent data indicate that proprotein convertases (PCs) typically resident in the Golgi apparatus (GA) can stimulate PKGI proteolysis and generate a kinase fragment that localizes to the nucleus and regulates gene expression. However, the role of the endomembrane system in PKGI compartmentation and processing is unknown. Here, we demonstrate that PKGI colocalizes with endoplasmic reticulum (ER), ER-Golgi intermediate compartment, GA cisterna, and trans-Golgi network proteins in pulmonary artery SMC and cell lines. Moreover, PKGI localizes with furin, a trans-Golgi network-resident PC known to cleave PKGI. ER protein transport influences PKGI localization because overexpression of a constitutively inactive Sar1 transgene caused PKGI retention in the ER. Additionally, PKGI appears to reside within the GA because PKGI immunoreactivity was determined to be resistant to cytosolic proteinase K treatment in live cells. The GA appears to play a role in PKGI proteolysis because overexpression of inositol 1,4,5-trisphosphate receptor-associated cGMP kinase substrate, not only tethered heterologous PKGI-β to the ER and decreased its localization to the GA, but also diminished PKGI proteolysis and nuclear translocation. Also, inhibiting intra-GA protein transport with monensin was observed to decrease PKGI cleavage. These studies detail a role for the endomembrane system in regulating PKGI compartmentation and proteolysis. Moreover, they support the investigation of mechanisms regulating PKGI-dependent nuclear cGMP signaling in the pulmonary vasculature with Golgi dysfunction.

  17. Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus.

    Science.gov (United States)

    Wiera, Grzegorz; Mozrzymas, Jerzy W

    2015-01-01

    Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed long-term potentiation (LTP) that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tissue plasminogen activator (tPA)/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.

  18. In situ proteolysis to generate crystals for structure determination: an update.

    Directory of Open Access Journals (Sweden)

    Amy Wernimont

    Full Text Available For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13-15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trials--in situ proteolysis--significantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate. Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 A resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects.

  19. CLIC1 regulates dendritic cell antigen processing and presentation by modulating phagosome acidification and proteolysis

    Directory of Open Access Journals (Sweden)

    Kanin Salao

    2016-05-01

    Full Text Available Intracellular chloride channel protein 1 (CLIC1 participates in inflammatory processes by regulating macrophage phagosomal functions such as pH and proteolysis. Here, we sought to determine if CLIC1 can regulate adaptive immunity by actions on dendritic cells (DCs, the key professional antigen presenting cells. To do this, we first generated bone marrow-derived DCs (BMDCs from germline CLIC1 gene-deleted (CLIC1−/− and wild-type (CLIC1+/+ mice, then studied them in vitro and in vivo. We found phagocytosis triggered cytoplasmic CLIC1 translocation to the phagosomal membrane where it regulated phagosomal pH and proteolysis. Phagosomes from CLIC1−/− BMDCs displayed impaired acidification and proteolysis, which could be reproduced if CLIC1+/+, but not CLIC1−/− cells, were treated with IAA94, a CLIC family ion channel blocker. CLIC1−/− BMDC displayed reduced in vitro antigen processing and presentation of full-length myelin oligodendrocyte glycoprotein (MOG and reduced MOG-induced experimental autoimmune encephalomyelitis. These data suggest that CLIC1 regulates DC phagosomal pH to ensure optimal processing of antigen for presentation to antigen-specific T-cells. Further, they indicate that CLIC1 is a novel therapeutic target to help reduce the adaptive immune response in autoimmune diseases.

  20. Extracellular proteolysis in structural and functional plasticity of mossy fiber synapses in hippocampus

    Directory of Open Access Journals (Sweden)

    Grzegorz eWiera

    2015-11-01

    Full Text Available Brain is continuously altered in response to experience and environmental changes. One of the underlying mechanisms is synaptic plasticity, which is manifested by modification of synapse structure and function. It is becoming clear that regulated extracellular proteolysis plays a pivotal role in the structural and functional remodeling of synapses during brain development, learning and memory formation. Clearly, plasticity mechanisms may substantially differ between projections. Mossy fiber synapses onto CA3 pyramidal cells display several unique functional features, including pronounced short-term facilitation, a presynaptically expressed LTP that is independent of NMDAR activation, and NMDA-dependent metaplasticity. Moreover, structural plasticity at mossy fiber synapses ranges from the reorganization of projection topology after hippocampus-dependent learning, through intrinsically different dynamic properties of synaptic boutons to pre- and postsynaptic structural changes accompanying LTP induction. Although concomitant functional and structural plasticity in this pathway strongly suggests a role of extracellular proteolysis, its impact only starts to be investigated in this projection. In the present report, we review the role of extracellular proteolysis in various aspects of synaptic plasticity in hippocampal mossy fiber synapses. A growing body of evidence demonstrates that among perisynaptic proteases, tPA/plasmin system, β-site amyloid precursor protein-cleaving enzyme 1 (BACE1 and metalloproteinases play a crucial role in shaping plastic changes in this projection. We discuss recent advances and emerging hypotheses on the roles of proteases in mechanisms underlying mossy fiber target specific synaptic plasticity and memory formation.

  1. A study of interfacial heat transfer and process parameters in squeeze casting and low pressure permanent mold casting

    Science.gov (United States)

    Krishna, Prasad

    2001-08-01

    With the emerging demand for energy efficient and environment-friendly automobiles, cast aluminum alloys are increasingly being used in their manufacture. In this context, two permanent mold casting processes, namely, Squeeze Cast Permanent Mold and Low Pressure Permanent Mold (LPPM) have become very popular in the production of high integrity shape-cast aluminum components. However, many industries are yet to benefit from the full potential of these processes due to limited understanding of the effect of process parameters on casting quality and the necessary boundary conditions for computer modeling and simulation so as to minimize costly field trials. This dissertation attempts to address some of these concerns facing today's foundry industry. An experimental investigation of the Indirect Squeeze Casting Process was conducted by pouring molten Al-7Si-0.3Mg (A356) alloy into a specially designed and instrumented mold, mounted on a horizontal clamped-vertical shot squeeze caster (HVSC). Temperature measurements close to the metal/mold interface were made and compared with the results of the numerical simulation of heat flow during solidification and cooling of castings. The Heat Transfer Coefficient (HTC), a critical parameter essential for any solidification simulation, was estimated based on the simulation that gave the best fit to the experimental temperature data. During the solidification process, the HTC is relatively uniform over the entire casting and on reaching a critical solidification pressure, the HTC is close to 4500 W/m2 K. The work has also provided a correlation of Secondary Dendrite Arm Spacing (SDAS) with cooling rate for a modified A356 alloy. Low Pressure Permanent Mold Casting experiments were conducted by pouring a nearly identical aluminum alloy into an instrumented, coated mold mounted on a low pressure casting machine. The pressure levels, along with the time required to achieve complete filling, were microprocessor controlled in the

  2. New concepts in molecular imaging: non-invasive MRI spotting of proteolysis using an Overhauser effect switch.

    Directory of Open Access Journals (Sweden)

    Philippe Mellet

    Full Text Available BACKGROUND: Proteolysis, involved in many processes in living organisms, is tightly regulated in space and time under physiological conditions. However deregulation can occur with local persistent proteolytic activities, e.g. in inflammation, cystic fibrosis, tumors, or pancreatitis. Furthermore, little is known about the role of many proteases, hence there is a need of new imaging methods to visualize specifically normal or disease-related proteolysis in intact bodies. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, a new concept for non invasive proteolysis imaging is proposed. Overhauser-enhanced Magnetic Resonance Imaging (OMRI at 0.2 Tesla was used to monitor the enzymatic hydrolysis of a nitroxide-labeled protein. In vitro, image intensity switched from 1 to 25 upon proteolysis due to the associated decrease in the motional correlation time of the substrate. The OMRI experimental device used in this study is consistent with protease imaging in mice at 0.2 T without significant heating. Simulations show that this enzymatic-driven OMRI signal switch can be obtained at lower frequencies suitable for larger animals or humans. CONCLUSIONS/SIGNIFICANCE: The method is highly sensitive and makes possible proteolysis imaging in three dimensions with a good spatial resolution. Any protease could be targeted specifically through the use of taylor-made cleavable macromolecules. At short term OMRI of proteolysis may be applied to basic research as well as to evaluate therapeutic treatments in small animal models of experimental diseases.

  3. Pressure dependence of X-rays produced by an LiTaO{sub 3} single crystal at low pressures

    Energy Technology Data Exchange (ETDEWEB)

    Hanamoto, Katsumi, E-mail: hana@md.okayama-u.ac.jp [Graduate School of Health Sciences, Okayama University, 5-1 Shikata-cho, 2-chome, Kita-ku, Okayama 700-8558 (Japan); Kawabe, Atsushi; Sakoda, Akihiro; Kataoka, Takahiro; Okada, Mari; Yamaoka, Kiyonori [Graduate School of Health Sciences, Okayama University, 5-1 Shikata-cho, 2-chome, Kita-ku, Okayama 700-8558 (Japan)

    2012-03-21

    The energy spectra of X-rays produced by an LiTaO{sub 3} single crystal have been measured at pressures of 5-50 Pa. The energy spectra showed that the amount of X-rays increased exponentially and the endpoint energy of the spectra increased linearly with the decrease of pressure at pressures of 10-25 Pa. A maximum endpoint energy of about 22 keV was obtained using an LiTaO{sub 3} single crystal with 0.5 mm thickness at the pressure of 10 Pa. The maximum energy produced by the present experimental setup was estimated assuming that the LiTaO{sub 3} single crystal forms a parallel-plate capacitor. The estimated energy reasonably agreed with the energy obtained. The pressure dependence of the endpoint energy was discussed in relation to the breakdown potential at low pressures.

  4. Effects of Solvent and Ion Source Pressure on the Analysis of Anabolic Steroids by Low Pressure Photoionization Mass Spectrometry

    Science.gov (United States)

    Liu, Chengyuan; Zhu, Yanan; Yang, Jiuzhong; Zhao, Wan; Lu, Deen; Pan, Yang

    2017-01-01

    Solvent and ion source pressure were two important factors relating to the photon induced ion-molecule reactions in low pressure photoionization (LPPI). In this work, four anabolic steroids were analyzed by LPPI mass spectrometry. Both the ion species present and their relative abundances could be controlled by switching the solvent and adjusting the ion source pressure. Whereas M•+, MH+, [M - H2O]+, and solvent adducts were observed in positive LPPI, [M - H]- and various oxidation products were abundant in negative LPPI. Changing the solvent greatly affected formation of the ion species in both positive and negative ion modes. The ion intensities of the solvent adduct and oxygen adduct were selectively enhanced when the ion source pressure was elevated from 68 to 800 Pa. The limit of detection could be decreased by increasing the ion source pressure.

  5. An Assessment of the Residual Stresses in Low Pressure Plasma Sprayed Coatings on an Advanced Copper Alloy

    Science.gov (United States)

    Raj, S. V.; Ghosn, L. J.; Agarwal, A.; Lachtrupp, T. P.

    2002-01-01

    Modeling studies were conducted on low pressure plasma sprayed (LPPS) NiAl top coat applied to an advanced Cu-8(at.%)Cr-4%Nb alloy (GRCop-84) substrate using Ni as a bond coat. A thermal analysis suggested that the NiAl and Ni top and bond coats, respectively, would provide adequate thermal protection to the GRCop-84 substrate in a rocket engine operating under high heat flux conditions. Residual stress measurements were conducted at different depths from the free surface on coated and uncoated GRCop-84 specimens by x-ray diffraction. These data are compared with theoretically estimated values assessed by a finite element analysis simulating the development of these stresses as the coated substrate cools down from the plasma spraying temperature to room temperature.

  6. On the Origin of Light Emission in Silicon Rich Oxide Obtained by Low-Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. Aceves-Mijares

    2012-01-01

    Full Text Available Silicon Rich Oxide (SRO has been considered as a material to overcome the drawbacks of silicon to achieve optical functions. Various techniques can be used to produce it, including Low-Pressure Chemical Vapor Deposition (LPCVD. In this paper, a brief description of the studies carried out and discussions of the results obtained on electro-, cathode-, and photoluminescence properties of SRO prepared by LPCVD and annealed at 1,100°C are presented. The experimental results lead us to accept that SRO emission properties are due to oxidation state nanoagglomerates rather than to nanocrystals. The emission mechanism is similar to Donor-Acceptor decay in semiconductors, and a wide emission spectrum, from 450 to 850 nm, has been observed. The results show that emission is a function of both silicon excess in the film and excitation energy. As a result different color emissions can be obtained by selecting the suitable excitation energy.

  7. Ion energy distributions for the identification of active species and processes in low pressure hollow cathode discharges

    Energy Technology Data Exchange (ETDEWEB)

    Tanarro, I; Herrero, V J [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)], E-mail: itanarro@iem.cfmac.csic.es

    2009-08-15

    Energy distributions of ions generated in hollow cathode low pressures dc discharges of different gases and gas mixtures containing Ar, H{sub 2}, N{sub 2}, O{sub 2} or CH{sub 4} are studied by quadrupole mass spectrometry. The ions are sampled through a small diaphragm in the grounded cathode. The measured distributions are mostly determined by the acceleration of ions in the sheath region between the negative glow and the cathode, displaying in general a narrow peak centred at energies close to the anode potential, but with specific features for the distinct ions. It is shown that information about ion production and sheath collision processes can be derived from the shapes of the different energy distributions. In some cases these distributions are used for the estimation of the relative abundance of ions with the same mass/charge ratio but different compositions in complex gas mixtures.

  8. Development of a chromatographic low pressure flow injection system using amperometric detection: Application to the analysis of niacin in coffee.

    Science.gov (United States)

    Santos, João Rodrigo; Rangel, António O S S

    2015-11-15

    In this work, an analytical flow system able to perform low pressure chromatography with amperometric detection is presented. As case study, the determination of niacin (vitamin B3) in coffee brewed samples was selected. The manifold comprised a 1.0 cm length monolithic column coated with didecyldimethylammonium bromide, a laboratory-made boron doped diamond electrode, and featured in-line ionic strength adjustment of the mobile phase. The figures of merit concerning the selected case study namely, detection limit, 7.90 × 10(-7) M, determination rate, ca. 10 samplesh(-1), mobile phase and ISA solution consumption, ca. 2.6 mL per analysis, and CV, below 5% for retention time and peak height, showed the competitiveness of this analytical strategy comparing to the described HPLC methods for niacin determination. The strategy displays a simple configuration, low cost, fast and easy assembling, foreseeing its use to general purpose applications.

  9. Hot-wall low pressure chemical vapor deposition growth and characterization of AlN thin films

    Science.gov (United States)

    Heinselman, Karen N.; Brown, Richard J.; Shealy, James R.

    2017-10-01

    Hot-wall low pressure chemical vapor deposition (LPCVD) of highly crystalline epitaxial thin-film AlN grown on silicon (1 1 1) substrates is reported for the first time. Deposition was carried out in a modified commercial LPCVD at 1000 °C and 2 torr. Preflow time for the aluminum precursor, trimethylaluminum, was varied to nucleate Al, and the resulting variation in X-ray diffraction (XRD) crystalline AlN peaks is presented. With a 30 s dichlorosilane (SiH2Cl2) pretreatment at 700 °C and the optimal TMAl preflow time, the FWHM of the resulting film was 1116 arcsec for the AlN (0 0 2) 2 θ - ω peak, and the AlN (0 0 2) peak had an omega rocking curve FWHM of 1.6°. This AlN film was shown to be epitaxially aligned to the Si (1 1 1) substrate.

  10. A static pressure reset control system with a new type of flow damper for use in low pressure ventilation systems

    DEFF Research Database (Denmark)

    Terkildsen, Søren; Svendsen, Svend

    2012-01-01

    The control strategy for mechanical ventilation systems has significant impact on the performance of the system, in terms of energy consumption and correct air distribution. This paper presents a static pressure reset control system employing a new type of flow damper with lower pressure loss...... for use in low pressure ventilation systems. The flow damper has a droplet shape that minimizes turbulence generation and the resulting pressure loss. The performance of the damper was examined by making measurements of pressure loss and airflow. These were used to determine the required pressure loss...... for operation and the airflow accuracy. Results were compared to similar tests carried out with conventional flat plate dampers. A static pressure reset control algorithm was programmed and analyzed on a test system consisting of three dampers, representing three office rooms. The comparison of the dampers...

  11. Room-Temperature Ferromagnetism of Ga1-xMnxN Grown by Low-Pressure Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhi-Tao; ZHANG Guo-Yi; SU Yue-Yong; YANG Zhi-Jian; ZHANG Yan; ZHANG Bin; GUO Li-Ping; XU Ke; PAN Yao-Bao; ZHANG Han

    2006-01-01

    @@ Epitaxial films of Ga1-xMnxN have been grown on c-sapphire substrates by low-pressure metal-organic vapour phase epitaxy. The samples show ferromagnetic behaviour up to a temperature of T = 380 K with hysteresis curves showing a coercivity of 50-100Oe. No ferromagnetic second phases and no significant deterioration in crystal quality with the incorporation of Mn can be detected by high-resolution x-ray diffraction. The result of x-ray absorption near-edge structures indicates that Mn atoms substitute for Ga atoms. The Mn concentrations of the layers are determined to reach x = 0.038 by proton-induced x-ray emission.

  12. Active metasomatism in the Cerro Prieto geothermal system, Baja California, Mexico: a telescoped low pressure/temperature metamorphic facies series

    Energy Technology Data Exchange (ETDEWEB)

    Schiffman, P.; Elders, W.A.; Williams, A.E.; McDowell, S.D.; Bird, D.K.

    1983-01-01

    In the Cerro Prieto geothermal field, carbonate-cemented, quartzofeldspathic sediments of the Colorado River delta are being actively metasomatized into calc-silicate metamorphic rocks by reaction with alkali chloride brines between 200/sup 0/ and 370/sup 0/C, low fluid and lithostatic pressures, and low oxygen fugacities. Petrologic investigations of drill cores and cutting from over 50 wells in this field identified a prograde series of calc-silicate mineral zones which include as index minerals: wairakite, epidote, prehnite, and clinopyroxene. Associated divariant mineral assemblages are indicative of a very low pressure/temperature metamorphic facies series which encompasses the clay-carbonate, zeolite, greenschist, and amphibolite facies. This hydrothermal metamorphic facies series, which is becoming increasingly recognized in other active geothermal systems, is characterized by temperature-telescoped dehydration and decarbonation mineral equilibria. Its equivalent should now be sought in fossil hydrothermal systems.

  13. Design criteria for semi-central sanitation with low pressure network and membrane bioreactor-the ENREM project.

    Science.gov (United States)

    Gnirss, Regina; Luedicke, Carsten; Vocks, Martin; Lesjean, Boris

    2008-01-01

    MBR-technology is able to fulfil similar or even higher standard for nutrients removal than conventional activated sludge processes. This paper presents the optimisation of the membrane bioreactor technology, together with a low pressure sewer, to equip a remote and yet unsewered area of Berlin requiring high quality wastewater treatment. The hydraulic flow pattern of the entire system has to be studied carefully due to the small collection system (no time delay between wastewater discharge and treatment to minimise the daily profile). The pollutant concentrations in the wastewater exhibit also stronger variations. In order to flatten out the hydraulic and load profile, and therefore to reduce the size of the biological reactor and the membrane surface, a buffer tank was installed before the MBR-plant. A full analysis of the influent hydraulic flow and wastewater characterisation is provided for the demonstration MBR-plant.

  14. Growth of a Novel Periodic Structure of SiC/AlN Multilayers by Low Pressure Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yong-Mei; SUN Guo-Sheng; LI Jia-Ye; LIU Xing-Fang; WANG Lei; ZHAO Wan-Shun; LI Jin-Min

    2007-01-01

    A novel 10-period SiC/AlN multilayered structure with a SiC cap layer is prepared by low pressure chemical vapour deposition (LPCVD). The structure with total Sim thickness of about 1.45μm is deposited on a Si (111) substrate and shows good surface morphology with a smaller rms surface roughness of 5.3 nm. According to the secondary ion mass spectroscopy results, good interface of the 10 period SiC/AlN structure and periodic changes of depth profiles of C, Si, Al, N components are obtained by controlling the growth procedure. The structure exhibits the peak reflectivity close to 30% near the wavelength of 322 nm. To the best of our knowledge, this is the first report of growth of the SiC/AlN periodic structure using the home-made LPCVD system.

  15. Growth of selective tungsten films on self-aligned CoSi/sub 2/ by low pressure chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    van der Putte, P.; Sadana, D.K.; Broadbent, E.K.; Morgan, A.E.

    1986-12-22

    The selective deposition of tungsten films onto CoSi/sub 2/ and onto Co by low pressure chemical vapor deposition and their material properties have been investigated with Auger electron spectroscopy, transmission electron microscopy, and Rutherford backscattering. When using WF/sub 6/ and H/sub 2/, uniformly thick tungsten films can be deposited onto CoSi/sub 2/ without substrate alteration. In patterned structures, however, void formation was found at the perimeters of CoSi/sub 2/ contacts to silicon, indicating encroachment of WF/sub 6/ down the edge of the silicide-Si interface. In WF/sub 6/ and Ar, the film thickness was limited to 10 nm and some Si was locally consumed from the upper part of the CoSi/sub 2/ film. Transmission electron diffraction showed evidence of Co/sub 2/Si formation in these areas.

  16. High versus low-pressure balloon inflation during multilinktrade mark stent implantation: acute and long-term angiographic results.

    Science.gov (United States)

    Caixeta, A M; Brito, F S; Rati, M; Perin, M A; da Luz, P L; Ramires, J A; Ambrose, J A; Martinez, E E

    2000-08-01

    We compared the impact of low and high-pressure balloon inflation on acute and late angiographic results of Multilink stent. Low-pressure balloon inflation (9.5 +/- 1.9 atm) was used in 43 stents and high pressure (17.1 +/- 1.5 atm) in 44. A larger immediate luminal gain was achieved in stents with high-pressure balloon inflation (1.80 +/- 0.26 vs. 1.47 +/- 0.62; P = 0.002), resulting in a larger mean diameter in this group (2.71 +/- 0.37 vs. 2.48 +/- 0.47; P = 0.017). At follow-up, a larger luminal diameter was achieved in the high pressure group (1.93 +/- 0.72 vs. 1.45 +/- 0.66; P = 0.002) and a trend to a lower rate of angiographic restenosis (15% vs. 38%, P = 0.08).

  17. Physisorption of Ar, Kr, CH4, and N2 on 304 stainless steel at very low pressures.

    Science.gov (United States)

    Troy, M.; Wightman, J. P.

    1971-01-01

    Determination of physisorption isotherms of these gases on stainless steel by pressure change measurements in very low pressure cryogenic baths where a steel nipple was brought in contact with the test gas at 77 to 90 K in a sealed constant-volume system. The position of the nipple in the gas was changed in such a manner that gas adsorption on a 47.5 sq cm area of the steel surface could be measured. The Dubinin-Radushkevich (DR) equation (1947) was used for an empirical description of isotherms at different temperatures. The mean adsorption energies calculated from the DR plots were 1290, 1545, 1490 and 1903 cal/mol for Ar, Kr, CH4 and N2, respectively, being about 10% higher than the corresponding values on Pyrex.

  18. Operation of gas electron multiplier (GEM) with propane gas at low pressure and comparison with tissue-equivalent gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    De Nardo, L., E-mail: laura.denardo@unipd.it [University of Padova, Physics and Astronomy Department and PD-INFN, via Marzolo 8, I-35131 Padova (Italy); Farahmand, M., E-mail: majid.farahmand@rivm.nl [Centre for Environmental Safety and Security, National Institute for Public Health and the Environment (RIVM), PO Box 1, NL-3720 BA Bilthoven (Netherlands)

    2016-05-21

    A Tissue-Equivalent Proportional Counter (TEPC), based on a single GEM foil of standard geometry, has been tested with pure propane gas at low pressure, in order to simulate a tissue site of about 1 µm equivalent size. In this work, the performance of GEM with propane gas at a pressure of 21 and 28 kPa will be presented. The effective gas gain was measured in various conditions using a {sup 244}Cm alpha source. The dependence of effective gain on the electric field strength along the GEM channel and in the drift and induction region was investigated. A maximum effective gain of about 5×10{sup 3} has been reached. Results obtained in pure propane gas are compared with gas gain measurements in gas mixtures commonly employed in microdosimetry, that is propane and methane based Tissue-Equivalent gas mixtures.

  19. In situ observation of UF5 nanoparticle growth in a low-pressure mixed-flow reactor

    Science.gov (United States)

    Kuga, Y.; Hirasawa, M.; Seto, T.; Okuyama, K.; Takeuchi, K.

    A mixed-flow reactor for the generation of UF5 nanoparticles equipped with an in situ size-monitoring system, a LPDMA (low-pressure differential mobility analyzer), was developed to experimentally investigate the nanoparticle growth mechanism. The concentration of photoproduced UF5 molecules was controlled by changing three factors: (I) the concentration of the feed UF6 gas, (II) the laser pulse energy of the irradiation, and (III) the repetition rate of the laser pulses. The dependence of the volumetric average diameter of the photoproduced particles on the UF5 nascent concentration in all three cases was found to be very similar. The result strongly suggests that the reactor functions as a mixed-flow reactor under a complete mixing condition. The particle size measured by the LPDMA was found to be in the range of 6 to 11 nm, and it was approximately proportional to the power 0.3 of the initial concentration of photoproduced UF5 molecules.

  20. A Concept for a Low Pressure Noble Gas Fill Intervention in the IFE Fusion Test Facility (FTF) Target Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Gentile, C. A.; Blanchard, W. R.; Kozub, T. A.; Aristova, M.; McGahan, C.; Natta, S.; Pagdon, K.; Zelenty, J.

    2010-01-14

    An engineering evaluation has been initiated to investigate conceptual engineering methods for implementing a viable gas shield strategy in the Fusion Test Facility (FTF) target chamber. The employment of a low pressure noble gas in the target chamber to thermalize energetic helium ions prior to interaction with the wall could dramatically increase the useful life of the first wall in the FTF reactor1. For the purpose of providing flexibility, two target chamber configurations are addressed: a five meter radius sphere and a ten meter radius sphere. Experimental studies at Nike have indicated that a low pressure, ambient gas resident in the target chamber during laser pulsing does not appear to impair the ability of laser light from illuminating targets2. In addition, current investigations into delivering, maintaining, and processing low pressure gas appear to be viable with slight modification to current pumping and plasma exhaust processing technologies3,4. Employment of a gas fill solution for protecting the dry wall target chamber in the FTF may reduce, or possibly eliminate the need for other attenuating technologies designed for keeping He ions from implanting in first wall structures and components. The gas fill concept appears to provide an effective means of extending the life of the first wall while employing mostly commercial off the shelf (COTS) technologies. Although a gas fill configuration may provide a methodology for attenuating damage inflicted on chamber surfaces, issues associated with target injection need to be further analyzed to ensure that the gas fill concept is viable in the integrated FTF design5. In the proposed system, the ambient noble gas is heated via the energetic helium ions produced by target detonation. The gas is subsequently cooled by the chamber wall to approximately 800oC, removed from the chamber, and processed by the chamber gas processing system (CGPS). In an optimized scenario of the above stated concept, the chamber

  1. Characterization of magnetically confined low-pressure plasmas produced by an electromagnetic field in argon-acetylene mixtures

    Science.gov (United States)

    Makdessi, G. Al; Margot, J.; Clergereaux, R.

    2016-10-01

    Dust particles formation was investigated in magnetically confined low-pressure plasma produced in argon-acetylene mixtures. The plasma characteristics were measured in order to identify the species involved in the dust particles formation. Their dependence on the operating conditions including magnetic field intensity, acetylene fraction in the gas mixture and operating pressure was examined. In contrast with noble gases, in the presence of acetylene, the electron temperature increases with the magnetic field intensity, indicating additional charged particles losses in the plasma. Indeed, in these conditions, larger hydrocarbon ions are produced leading to the formation of dust particles in the plasma volume. The observed dependence of positive ion mass distribution and density and relative negative ion density on the operating parameters suggests that the dust particles are formed through different pathways, where negative and positive ions are both involved in the nucleation.

  2. DNS of Flow in a Low-Pressure Turbine Cascade Using a Discontinuous-Galerkin Spectral-Element Method

    Science.gov (United States)

    Garai, Anirban; Diosady, Laslo Tibor; Murman, Scott; Madavan, Nateri

    2015-01-01

    A new computational capability under development for accurate and efficient high-fidelity direct numerical simulation (DNS) and large eddy simulation (LES) of turbomachinery is described. This capability is based on an entropy-stable Discontinuous-Galerkin spectral-element approach that extends to arbitrarily high orders of spatial and temporal accuracy and is implemented in a computationally efficient manner on a modern high performance computer architecture. A validation study using this method to perform DNS of flow in a low-pressure turbine airfoil cascade are presented. Preliminary results indicate that the method captures the main features of the flow. Discrepancies between the predicted results and the experiments are likely due to the effects of freestream turbulence not being included in the simulation and will be addressed in the final paper.

  3. CFD Study of the Hydrocarbon Boost Low-Pressure Inducer and Kicker in the Presence of a Circumferential Groove

    Science.gov (United States)

    Coker, Robert

    2011-01-01

    Results are presented of a computational fluid dynamics (CFD) study done in support of Marshall Space Flight Center's (MSFC) sub-scale water flow experiments of the Hydrocarbon Boost (HCB) Oxidizer Turbopump (OTP) being developed by the Air Force Research Laboratory (AFRL) and Aerojet. A circumferential groove may be added to the pump to reduce synchronous cavitation and subsequent bearing loads at a minimal performance cost. However, the energy may reappear as high order cavitation (HOC) that spans a relatively large frequency range. Thus, HOC may have implications for the full-scale OTP inducer in terms of reduced structural margin at higher mode frequencies. Simulations using the LOCI/Stream CFD program were conducted in order to explore the fluid dynamical impact of the groove on the low-pressure inducer and kicker. It was found that the circumferential groove has minimal head performance impact, but causes back-flowing high-swirl fluid to interact with the nearly-axial incoming fluid just above the inducer blades. The high-shear interface between the fluids is Kelvin-Helmholtz unstable, resulting in trains of low pressure regions or 'pearls' forming near the upstream edge of the groove. When the static pressure in these regions becomes low enough and they get cut by the blade leading edge, HOC is thought to occur. Although further work is required, the numerical models indicate that HOC will occur in the runbox of the AFRL/Aerojet HCB OTP. Comparisons to the ongoing water flow experiments will be discussed, as well as possible designs that may mitigate HOC while continuing to reduce synchronous cavitation. December 2011 MSS/LPS/SPS Joint Subcommittee Meeting ABSTRACT SUBMITTAL FORM

  4. Numerical Investigation of the Interaction between Mainstream and Tip Shroud Leakage Flow in a 2-Stage Low Pressure Turbine

    Science.gov (United States)

    Jia, Wei; Liu, Huoxing

    2014-06-01

    The pressing demand for future advanced gas turbine requires to identify the losses in a turbine and to understand the physical mechanisms producing them. In low pressure turbines with shrouded blades, a large portion of these losses is generated by tip shroud leakage flow and associated interaction. For this reason, shroud leakage losses are generally grouped into the losses of leakage flow itself and the losses caused by the interaction between leakage flow and mainstream. In order to evaluate the influence of shroud leakage flow and related losses on turbine performance, computational investigations for a 2-stage low pressure turbine is presented and discussed in this paper. Three dimensional steady multistage calculations using mixing plane approach were performed including detailed tip shroud geometry. Results showed that turbines with shrouded blades have an obvious advantage over unshrouded ones in terms of aerodynamic performance. A loss mechanism breakdown analysis demonstrated that the leakage loss is the main contributor in the first stage while mixing loss dominates in the second stage. Due to the blade-to-blade pressure gradient, both inlet and exit cavity present non-uniform leakage injection and extraction. The flow in the exit cavity is filled with cavity vortex, leakage jet attached to the cavity wall and recirculation zone induced by main flow ingestion. Furthermore, radial gap and exit cavity size of tip shroud have a major effect on the yaw angle near the tip region in the main flow. Therefore, a full calculation of shroud leakage flow is necessary in turbine performance analysis and the shroud geometric features need to be considered during turbine design process.

  5. Addressing reverse osmosis fouling within water reclamation--a side-by-side comparison of low-pressure membrane pretreatments.

    Science.gov (United States)

    Kent, Fraser C; Farahbakhsh, Khosrow

    2011-06-01

    A tertiary membrane filtration (TMF) pilot operating on secondary effluent and a membrane bioreactor (MBR) were setup in a side-by-side study as pretreatments for two identical reverse osmosis pilot systems. The water quality of the permeate from both low-pressure membrane pretreatment systems and the fouling rate of the reverse osmosis systems were compared to assess the capabilities of the two low-pressure membrane pretreatments to prevent organic fouling of the reverse osmosis systems. Both pretreatment pilots were setup using typical operating conditions (i.e., solids retention time and mixed-liquor suspended solids). A consistent difference in water quality and reverse osmosis performance was demonstrated during the 12-month study. The MBR permeate consistently had significantly lower total organic carbon (TOC) and chemical oxygen demand concentrations, but higher color and specific UV absorbance compared with the permeate from the TMF pretreatment. The pretreatment with the MBR gave an average reverse osmosis fouling rate over the entire study (0.27 Lmh/bar.month) that was less than half of the value found for the reverse osmosis with TMF pretreatment (0.60 Lmh/bar.month). A correlation of reverse osmosis feed TOC concentration with average reverse osmosis fouling rate also was established, independent of the pretreatment method used. Results from a cleaning analysis, energy dispersive spectroscopy, and fourier transformed infrared reflectometry confirmed that the foulants were primarily organic in nature. It is concluded that, for this type of application and setup, MBR systems present an advantage over tertiary membrane polishing of secondary effluent for reverse osmosis pretreatment.

  6. Corrosion Analysis of Low Pressure Steam Turbine%某汽轮机低压缸腐蚀分析

    Institute of Scientific and Technical Information of China (English)

    徐洪; 张建国; 杨贤彪

    2011-01-01

    The case of erosion/corrosion damage occurring in a low pressure steam turbine was evaluated. This fossil power unit had been put into operation for nearly twenty years, and the used ion exchange resins for water treatment had never been scrapped. The leaked organism of aged ion exchange resins was decomposed into corrosive irons in the water-steam cycle. The action of enriched corrosion irons in the primary condensate water with the water steam made a severe erosion/corrosion of the low pressure turbine. It is important to detect the contents of corrosion irons and displace aged ion exchange resins in time.%对某汽轮机低压缸的腐蚀一磨蚀案例进行了研究.该火电机组投运近20年,从未对补给水处理系统的离子交换树脂进行过报废处理.老化的树脂产生大量有机溶出物,随补给水进入热力系统,受热分解为乙酸根、硫酸根等腐蚀性离子.这些腐蚀性离子在初凝水中富集使其呈酸性,与湿蒸汽共同冲刷腐蚀低压缸内壁,导致严重腐蚀.采用离子色谱仪监测水汽中腐蚀性离子含量,及时报废老化的离子交换树脂,对预防低压缸腐蚀十分必要.

  7. 碳氢燃料低压裂解特性%Pyrolysis Characteristics of Hydrocarbon Fuel Under Low Pressure

    Institute of Scientific and Technical Information of China (English)

    张其翼; 魏微; 周灏; 文旭; 李象远

    2015-01-01

    针对主动冷却中利用碳氢燃料裂解吸热释放热沉的特性,研究分析了碳氢燃料在低压条件下的裂解反应特征,从产气率、气相组分与结焦等方面进行了对比研究.结果表明,在相同停留时间,压力降低,裂解的产气率更高,裂解气组分中烯烃含量大幅提升,表明低压裂解具有一定的反应定向性.通过吸光光度法半定量分析高温裂解残液,发现裂解压力降低,吸光度值降低,表明低压裂解可以明显抑制结焦反应发生.%This study focuses on the cracking reaction of hydrocarbon fuel under low pressure.The rate of pyrolysis gas yielding,pyrolysis gas composition and coke formation are studied and compared.The results demonstrate that during the same residence time,the rate of gas yielding increases while the pressure is reduced.A substantial rise of the olefin content in the pyrolysis gas indicates that the cracking reaction is directed.The semi-quantitative analysis of pyrolysis residue absorbance shows that absorbance values are reduced with the decrease of cracking pressure,and low pressure pyrolysis can significantly inhibit coking reaction.

  8. Low-pressure balloon angioplasty with adjuvant pharmacological therapy in patients with acute ischemic stroke caused by intracranial arterial occlusions

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Raul G. [Massachusetts General Hospital, Harvard Medical School, Department of Radiology, Endovascular Neurosurgery/Interventional Neuroradiology Section, Boston, MA (United States); Massachusetts General Hospital, Harvard Medical School, Department of Neurosurgery, Endovascular Neurosurgery/Interventional Neuroradiology Section, Boston, MA (United States); Massachusetts General Hospital, Harvard Medical School, Department of Neurology, Neurocritical Care and Vascular Neurology Section, Boston, MA (United States); Massachusetts General Hospital, Boston, MA (United States); Schwamm, Lee H.; Buonanno, Ferdinando S.; Koroshetz, Walter J. [Massachusetts General Hospital, Harvard Medical School, Department of Neurology, Neurocritical Care and Vascular Neurology Section, Boston, MA (United States); Yoo, Albert J.; Rabinov, James D.; Pryor, Johnny C.; Hirsch, Joshua A. [Massachusetts General Hospital, Harvard Medical School, Department of Radiology, Endovascular Neurosurgery/Interventional Neuroradiology Section, Boston, MA (United States); Massachusetts General Hospital, Harvard Medical School, Department of Neurosurgery, Endovascular Neurosurgery/Interventional Neuroradiology Section, Boston, MA (United States)

    2008-04-15

    The use of coronary balloons in the cerebral vasculature is limited due to their poor trackability and increased risk of vessel injury. We report our experience using more compliant elastomer balloons for thrombus resistant to intraarterial (IA) pharmacological and mechanical thrombolysis in acute stroke. We retrospectively analyzed 12 consecutive patients with an occluded intracranial artery treated with angioplasty using a low-pressure elastomer balloon. Angiograms were graded according to the Thrombolysis in Cerebral Infarction (TICI) and Qureshi grading systems. Outcomes were categorized as independent (modified Rankin scale, mRS, score {<=}2), dependent (mRS score 3-5), or dead (mRS score 6). Included in the study were 12 patients (mean age 66{+-}17 years, range 31-88 years; mean baseline National Institutes of Health stroke scale score 17{+-}3, range 12-23). The occlusion sites were: internal carotid artery (ICA) terminus (five patients, including two concomitant cervical ICA occlusions), M1 segment (two patients), and basilar artery (two patients). Pharmacological treatment included intravenous (IV) t-PA only (two patients), IA urokinase only (nine patients), both IV t-PA and IA urokinase (one patient), and IV and/or IA eptifibatide (eight patients). Mean time to treatment was 5.9{+-}3.9 h (anterior circulation) and 11.0{+-}7.2 h (posterior circulation). Overall recanalization rate (TICI grade 2/3) was 91.6%. Procedure-related morbidity occurred in one patient (distal posterior inferior cerebellar artery embolus). There were no symptomatic hemorrhages. Outcomes at 90 days were independent (five patients), dependent (three patients) and dead (four patients, all due to progression of stroke with withdrawal of care). Angioplasty of acutely occluded intracranial arteries with low-pressure elastomer balloons results in high recanalization rates with an acceptable degree of safety. Prior use of thrombolytics may increase the chances of recanalization, and

  9. Buoyancy induced limits for nanoparticle synthesis experiments in horizontal premixed low-pressure flat-flame reactors

    Science.gov (United States)

    Weise, C.; Faccinetto, A.; Kluge, S.; Kasper, T.; Wiggers, H.; Schulz, C.; Wlokas, I.; Kempf, A.

    2013-06-01

    Premixed low-pressure flat-flame reactors can be used to investigate the synthesis of nanoparticles. The present work examines the flow field inside such a reactor during the formation of carbon (soot) and iron oxide (from Fe(CO)5) nanoparticles, and how it affects the measurements of nanoparticle size distribution. The symmetry of the flow and the impact of buoyancy were analysed by three-dimensional simulations and the nanoparticle size distribution was obtained by particle mass spectrometry (PMS) via molecular beam sampling at different distances from the burner. The PMS measurements showed a striking, sudden increase in particle size at a critical distance from the burner, which could be explained by the flow field predicted in the simulations. The simulation results illustrate different fluid mechanical phenomena which have caused this sudden rise in the measured particle growth. Up to the critical distance, buoyancy does not affect the flow, and an (almost) linear growth is observed in the PMS experiments. Downstream of this critical distance, buoyancy deflects the hot gas stream and leads to an asymmetric flow field with strong recirculation. These recirculation zones increase the particle residence time, inducing very large particle sizes as measured by PMS. This deviation from the assumed symmetric, one-dimensional flow field prevents the correct interpretation of the PMS results. To overcome this problem, modifications to the reactor were investigated; their suitability to reduce the flow asymmetry was analysed. Furthermore, 'safe' operating conditions were identified for which accurate measurements are feasible in premixed low-pressure flat-flame reactors that are transferrable to other experiments in this type of reactor. The present work supports experimentalists to find the best setup and operating conditions for their purpose.

  10. Low-pressure plasma enhanced immobilization of chitosan on low-density polyethylene for bio-medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Pandiyaraj, K. Navaneetha, E-mail: dr.knpr@gmail.com [Surface Engineering Laboratory, Department of Physics, Sri Shakthi Institute of Engineering and Technology, L& T by pass, Chinniyam Palayam (post), Coimbatore, 641062 (India); Ferraria, Ana Maria; Rego, Ana Maria Botelho do [Centro de Química- Física Molecular and Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, University of Lisbon (Portugal); Deshmukh, Rajendra R. [Department of Physics, Institute of Chemical Technology, Matunga, Mumbai 400 019 (India); Su, Pi-Guey [Department of Chemistry, Chinese Culture University, Taipei 111, Taiwan (China); Halleluyah, Jr. Mercy; Halim, Ahmad Sukari [Reconstructive Science Unit, School of Medical Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

    2015-02-15

    Highlights: • Acrylic acid (AAc) was grafted on LDPE film by in situ plasma polymerization. • Molecules of PEG and chitosan were immobilized on AAc grafted LDPE films. • Surface modified LDPE exhibits excellent hydrophilic property. • Surface modified LDPE resist the adsorption of protein and adhesion of platelets. - Abstract: With the aim of improving blood compatibility of low density polyethylene (LDPE) films, an effective low-pressure plasma technology was employed to functionalize the LDPE film surfaces through in-situ grafting of acrylic acid (AAc). Subsequently, the molecules of poly(ethylene glycol) (PEG) and chitosan (CHI) were immobilized on the surface of grafted LDPE films. The unmodified and modified LDPE films were analyzed using various characterization techniques such as contact angle, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photo electron spectroscopy (XPS) to understand the changes in surface properties such as hydrophilicity, surface topography and chemical composition, respectively. Furthermore, LDPE films have been subjected to an ageing process to determine the durability of the plasma assisted surface modification. The blood compatibility of the surface modified LDPE films was confirmed by in vitro tests. It was found that surface modified LDPE films show better hydrophilic behavior compared with the unmodified one. FTIR and XPS results confirm the successful immobilization of CHI on the surface of LDPE films. LDPE films showed marked morphological changes after grafting of AAc, PEG and CHI which were confirmed through AFM imaging. The in vitro blood compatibility tests have clearly demonstrated that CHI immobilized LDPE films exhibit remarkable anti thrombogenic nature compared with other modified films. Surface modified LDPE films through low-pressure plasma technique could be adequate for biomedical implants such as artificial skin substrates, urethral catheters or cardiac stents

  11. Tubulin secondary structure analysis, limited proteolysis sites, and homology to FtsZ.

    Science.gov (United States)

    de Pereda, J M; Leynadier, D; Evangelio, J A; Chacón, P; Andreu, J M

    1996-11-12

    The far-ultraviolet circular dichroism spectrum of the alpha beta-tubulin dimer analyzed by six different methods indicates an average content of approximately 33% alpha helix, 21% beta sheet, and 45% other secondary structure. Deconvolution of Fourier transform infrared spectra indicates 24% sheet, 37% (maximum) helix, and 38% (minimum) other structure. Separate alignments of 75 alpha-tubulin, 106 beta-tubulin, and 14 gamma-tubulin sequences and 12 sequences of the bacterial cell division protein FtsZ have been employed to predict their secondary structures with the multiple-sequence method PHD [Rost, B., & Sander, C. (1993a) J. Mol. Biol. 232, 584-599]. The predicted secondary structures average of 33% alpha helix, 24% beta sheet, and 43% loop for the alpha beta dimer. The predictions have been compared with sites of limited proteolysis by 12 proteases at the surfaces of the heterodimer and taxol-induced microtubules [de Pereda, J. M., & Andreu, J. M. (1996) Biochemistry 35, 14184-14202]. From 24 experimentally determined nicking sites, 18 are at predicted loops or at the extremes of secondary structure elements. Proteolysis zone A (including acetylable Lys40 and probably Lys60 in alpha-tubulin and Gly93 in beta-tubulin) and proteolysis zone B (extending between residues 167 and 183 in both chains) are accessible in microtubules. Proteolysis zone C, between residues 278 and 295, becomes partially occluded in microtubules. The alpha-tubulin nicking site Arg339-Ser340 is at a loop following a predicted alpha helix in proteolysis zone D. This site is protected in taxol microtubules; however, a new tryptic site appears which is probably located at the N-terminal end of the same helix. Zone D also contains beta-tubulin Cys354, which is accessible in microtubules. Proteolysis zone E includes the C-terminal hypervariable loops (10-20 residues) of each tubulin chain. These follow the two larger predicted helical zones (residues 372-395 and 405-432 in beta-tubulin), which

  12. Understanding of the importance of the spore coat structure and pigmentation in the Bacillus subtilis spore resistance to low-pressure plasma sterilization

    Science.gov (United States)

    Raguse, Marina; Fiebrandt, Marcel; Denis, Benjamin; Stapelmann, Katharina; Eichenberger, Patrick; Driks, Adam; Eaton, Peter; Awakowicz, Peter; Moeller, Ralf

    2016-07-01

    Low-pressure plasmas have been evaluated for their potential in biomedical and defense purposes. The sterilizing effect of plasma can be attributed to several active agents, including (V)UV radiation, charged particles, radical species, neutral and excited atoms and molecules, and the electric field. Spores of Bacillus subtilis were used as a bioindicator and a genetic model system to study the sporicidal effects of low-pressure plasma decontamination. Wild-type spores, spores lacking the major protective coat layers (inner, outer, and crust), pigmentation-deficient spores or spore impaired in encasement (a late step in coat assembly) were systematically tested for their resistance to low-pressure argon, hydrogen, and oxygen plasmas with and without admixtures. We demonstrate that low-pressure plasma discharges of argon and oxygen discharges cause significant physical damage to spore surface structures as visualized by atomic force microscopy. Spore resistance to low-pressure plasma was primarily dependent on the presence of the inner, and outer spore coat layers as well as spore encasement, with minor or less importance of the crust and spore pigmentation, whereas spore inactivation itself was strongly influenced by the gas composition and operational settings.

  13. Forward Osmosis/Low Pressure Reverse Osmosis for Water Reuse: Removal of Organic Micropollutants, Fouling and Cleaning

    KAUST Repository

    Linares, Rodrigo

    2011-07-01

    Forward osmosis (FO) is a natural process in which a solution with high concentration of solutes is diluted when being in contact, through a semipermeable membrane, with a low concentration solution. This osmotic process has been demonstrated to be efficient to recover wastewater effluents while diluting a saline draw solution. Nevertheless, the study of the removal of micropollutants by FO is barely described in the literature. This research focuses on the removal of these substances spiked in a secondary wastewater effluent, while diluting water from the Red Sea, generating feed water that can be desalinated with a low pressure reverse osmosis (LPRO) system. Another goal of this work is to characterize the fouling of the FO membrane, and its effect on micropollutants rejection, as well as the membrane cleaning efficiency of different methods. When considering only FO with a clean membrane, the rejection of the hydrophilic neutral compounds was between 48.6% and 84.7%, for the hydrophobic neutrals the rejection ranged from 40.0% to 87.5%, and for the ionic compounds the rejections were between 92.9% and 96.5%. With a fouled membrane, the rejections were between 44.6% to 95.2%, 48.7% to 91.5% and 96.9% to 98.6%, respectively. These results suggest that, except for the hydrophilic neutral compounds, the rejection of the micropollutants is increased by the fouling layer, possibly due to the higher hydrophilicity of the FO fouled membrane compared to the clean one, the increased adsorption capacity and reduced mass transport capacity, membrane swelling, and the higher negative charge of the surface, related to the foulants. However, when coupled with low pressure reverse osmosis, the rejections for both, the clean and fouled membrane, increased above 98%. The fouling layer, after characterizing the wastewater effluent and the concentrated wastewater after the FO process, proved to be composed of biopolymers, which can be removed with air scouring during short periods

  14. Low pressure radio-frequency oxygen plasma induced oxidation of titanium--surface characteristics and biological effects.

    Directory of Open Access Journals (Sweden)

    Wan-Yu Tseng

    Full Text Available OBJECTIVE: This research was designed to investigate the effects of low pressure radio-frequency (RF oxygen plasma treatment (OPT on the surface of commercially pure titanium (CP-Ti and Ti6Al4V. Surface topography, elemental composition, water contact angle, cell viability, and cell morphology were surveyed to evaluate the biocompatibility of titanium samples with different lengths of OP treating time. MATERIALS AND METHODS: CP-Ti and Ti6Al4V discs were both classified into 4 groups: untreated, treated with OP generated by using oxygen (99.98% for 5, 10, and 30 min, respectively. After OPT on CP-Ti and Ti6Al4V samples, scanning probe microscopy, X-ray photoelectron spectrometry (XPS, and contact angle tests were conducted to determine the surface topography, elemental composition and hydrophilicity, respectively. The change of surface morphology was further studied using sputtered titanium on silicon wafers. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT assay and F-actin immunofluorescence stain were performed to investigate the viability and spreading behavior of cultivated MG-63 cells on the samples. RESULTS: The surface roughness was most prominent after 5 min OPT in both CP-Ti and Ti6Al4V, and the surface morphology of sputtered Ti sharpened after the 5 min treatment. From the XPS results, the intensity of Ti(°, Ti(2+, and Ti(3+ of the samples' surface decreased indicating the oxidation of titanium after OPT. The water contact angles of both CP-Ti and Ti6Al4V were increased after 5 min OPT. The results of MTT assay demonstrated MG-63 cells proliferated best on the 5 min OP treated titanium sample. The F-actin immunofluorescence stain revealed the cultivated cell number of 5 min treated CP-Ti/Ti6Al4V was greater than other groups and most of the cultivated cells were spindle-shaped. CONCLUSIONS: Low pressure RF oxygen plasma modified both the composition and the morphology of titanium samples' surface. The CP-Ti/Ti6Al4V

  15. Performance of a CdZnTe Radiation Detector Grown by a Low-pressure Bridgman Method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Han Soo; Ha, Jang Ho; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-11-15

    CdZnTe (CZT) has been studied for many years as a material for room-temperature, high energy resolution gamma-ray detectors. Currently, prototypical detectors are now available for medical imaging, industrial tomograph and astrophysics in the world-wide. For this reason and next-generation gamma-ray detector, core-technology of CZT crystal growth and detector fabrication is much more crucial. CZT crystal was grown by Low-pressure Bridgman Method at Korea Atomic Energy Research Institute (KAERI) for room-temperature gamma-ray detector. In this study, performance of a CZT radiation detector such as I-V curve and energy resolution for gamma-ray was presented. We measured the I-V curve to define the resistivity of the grown CZT crystal. The electrometer, Keithley 6517A, was used to biasthe high voltage on the detector and read the leakage current. The measured I-V curve is shown in Fig. 3. Resistivity of the planar-type CZT detector, which didn't apply any passivation, was 7.8 x 10{sup 9} Ω·cm. The pulse height spectra was obtained with a CREMAT® CR-110 preamplifier, ORTEC® 572 amplifier, and 919 MCA. Figure 4 and 5 shows the pulse height spectra for 511 keV and 660 keV gamma-ray. The 10.0 % and 9.7 % energy resolutions for 511 keV and 662 keV gamma-ray, respectively, were obtained with the fabricated CZT detector. CZT single crystal was grown by low-pressure Bridgman method. Large domain of (1,1,1) crystalline face was obtained. Resistivity of 7.8 x 10{sup 9} Ω·cm of the grown CZT crystal, can be fabricated gamma-ray detector from the results. 10.0 % and 9.7 % of enrgy resolution for 511 keV and 662 keV gamma-ray, respectively, was also obtained. In the future work, passivation and types of detector, such as a Schottky-type, a Frisch Collor, and a coplanar electrode, will be studied to improve energy resolution.

  16. Ethylene Decomposition Initiated by Ultraviolet Radiation from Low Pressure Mercury Lamps: Kinetics Model Prediction and Experimental Verification.

    Science.gov (United States)

    Jozwiak, Zbigniew Boguslaw

    1995-01-01

    Ethylene is an important auto-catalytic plant growth hormone. Removal of ethylene from the atmosphere surrounding ethylene-sensitive horticultural products may be very beneficial, allowing an extended period of storage and preventing or delaying the induction of disorders. Various ethylene removal techniques have been studied and put into practice. One technique is based on using low pressure mercury ultraviolet lamps as a source of photochemical energy to initiate chemical reactions that destroy ethylene. Although previous research showed that ethylene disappeared in experiments with mercury ultraviolet lamps, the reactions were not described and the actual cause of ethylene disappearance remained unknown. Proposed causes for this disappearance were the direct action of ultraviolet rays on ethylene, reaction of ethylene with ozone (which is formed when air or gas containing molecular oxygen is exposed to radiation emitted by this type of lamp), or reactions with atomic oxygen leading to formation of ozone. The objective of the present study was to determine the set of physical and chemical actions leading to the disappearance of ethylene from artificial storage atmosphere under conditions of ultraviolet irradiation. The goal was achieved by developing a static chemical model based on the physical properties of a commercially available ultraviolet lamp, the photochemistry of gases, and the kinetics of chemical reactions. The model was used to perform computer simulations predicting time dependent concentrations of chemical species included in the model. Development of the model was accompanied by the design of a reaction chamber used for experimental verification. The model provided a good prediction of the general behavior of the species involved in the chemistry under consideration; however the model predicted lower than measured rate of ethylene disappearance. Some reasons for the model -experiment disagreement are radiation intensity averaging, the experimental

  17. Effects of energy deficit, dietary protein, and feeding on intracellular regulators of skeletal muscle proteolysis.

    Science.gov (United States)

    Carbone, John W; Margolis, Lee M; McClung, James P; Cao, Jay J; Murphy, Nancy E; Sauter, Edward R; Combs, Gerald F; Young, Andrew J; Pasiakos, Stefan M

    2013-12-01

    This study was undertaken to characterize the ubiquitin proteasome system (UPS) response to varied dietary protein intake, energy deficit (ED), and consumption of a mixed meal. A randomized, controlled trial of 39 adults consuming protein at 0.8 (recommended dietary allowance [RDA]), 1.6 (2×-RDA), or 2.4 (3×-RDA) g · kg(-1) · d(-1) for 31 d. A 10-d weight maintenance (WM) period was followed by 21 d of 40% ED. Ubiquitin (Ub)-mediated proteolysis and associated gene expression were assessed in the postabsorptive (fasted) and postprandial (fed; 480 kcal, 20 g protein) states after WM and ED by using muscle biopsies, fluorescence-based assays, immunoblot analysis, and real-time qRT-PCR. In the assessment of UPS responses to varied protein intakes, ED, and feeding, the RDA, WM, and fasted measures served as appropriate controls. ED resulted in the up-regulation of UPS-associated gene expression, as mRNA expression of the atrogenes muscle RING finger-1 (MuRF1) and atrogin-1 were 1.2- and 1.3-fold higher (P<0.05) for ED than for WM. However, mixed-meal consumption attenuated UPS-mediated proteolysis, independent of energy status or dietary protein, as the activities of the 26S proteasome subunits β1, β2, and β5 were lower (P<0.05) for fed than for fasted. Muscle protein ubiquitylation was also 45% lower (P<0.05) for fed than for fasted, regardless of dietary protein and energy manipulations. Independent of habitual protein intake and despite increased MuRF1 and atrogin-1 mRNA expression during ED, consuming a protein-containing mixed meal attenuates Ub-mediated proteolysis.

  18. Off-target effects of thrombolytic drugs: apolipoprotein A-I proteolysis by alteplase and tenecteplase.

    Science.gov (United States)

    Gomaraschi, Monica; Ossoli, Alice; Vitali, Cecilia; Pozzi, Silvia; Vitali Serdoz, Laura; Pitzorno, Cristina; Sinagra, Gianfranco; Franceschini, Guido; Calabresi, Laura

    2013-02-15

    The administration of thrombolytic drugs is of proven benefit in a variety of clinical conditions requiring acute revascularization, including acute myocardial infarction (AMI), ischemic stroke, pulmonary embolism, and venous thrombosis. Generated plasmin can degrade non-target proteins, including apolipoprotein A-I (apoA-I), the major protein constituent of high-density lipoproteins (HDL). Aim of the present study was to compare the extent of apoA-I proteolytic degradation in AMI patients treated with two thrombolytic drugs, alteplase and the genetically engineered t-PA variant tenecteplase. ApoA-I degradation was evaluated in sera from 38 AMI patients treated with alteplase or tenecteplase. In vitro, apoA-I degradation was tested by incubating control sera or purified HDL with alteplase or tenecteplase at different concentrations (5-100 μg/ml). Treatment with alteplase and tenecteplase results in apoA-I proteolysis; the extent of apoA-I degradation was more pronounced in alteplase-treated patients than in tenecteplase-treated patients. In vitro, the extent of apoA-I proteolysis was higher in alteplase-treated sera than in tenecteplase-treated sera, in the whole drug concentration range. No direct effect of the two thrombolytic agents on apoA-I degradation was observed. In addition to apoA-I, apoA-IV was also degraded by the two thrombolytic agents and again proteolytic degradation was higher with alteplase than tenecteplase. In conclusion, this study indicates that both alteplase and tenecteplase cause plasmin-mediated proteolysis of apoA-I, with alteplase resulting in a greater apoA-I degradation than tenecteplase, potentially causing a transient impairment of HDL atheroprotective functions.

  19. Collagen fibril architecture, domain organization, and triple-helical conformation govern its proteolysis

    Energy Technology Data Exchange (ETDEWEB)

    Perumal, Shiamalee; Antipova, Olga; Orgel, Joseph P.R.O. (IIT)

    2008-06-24

    We describe the molecular structure of the collagen fibril and how it affects collagen proteolysis or 'collagenolysis.' The fibril-forming collagens are major components of all mammalian connective tissues, providing the structural and organizational framework for skin, blood vessels, bone, tendon, and other tissues. The triple helix of the collagen molecule is resistant to most proteinases, and the matrix metalloproteinases that do proteolyze collagen are affected by the architecture of collagen fibrils, which are notably more resistant to collagenolysis than lone collagen monomers. Until now, there has been no molecular explanation for this. Full or limited proteolysis of the collagen fibril is known to be a key process in normal growth, development, repair, and cell differentiation, and in cancerous tumor progression and heart disease. Peptide fragments generated by collagenolysis, and the conformation of exposed sites on the fibril as a result of limited proteolysis, regulate these processes and that of cellular attachment, but it is not known how or why. Using computational and molecular visualization methods, we found that the arrangement of collagen monomers in the fibril (its architecture) protects areas vulnerable to collagenolysis and strictly governs the process. This in turn affects the accessibility of a cell interaction site located near the cleavage region. Our observations suggest that the C-terminal telopeptide must be proteolyzed before collagenase can gain access to the cleavage site. Collagenase then binds to the substrate's 'interaction domain,' which facilitates the triple-helix unwinding/dissociation function of the enzyme before collagenolysis.

  20. cAMP-dependent proteolysis of GATA-6 is linked to JNK-signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Ushijima, Hironori [Department of Molecular Biology, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Shiwagun, Iwate 028-3694 (Japan); Maeda, Masatomo, E-mail: mmaeda@iwate-med.ac.jp [Department of Molecular Biology, School of Pharmacy, Iwate Medical University, 2-1-1, Nishitokuta, Yahaba, Shiwagun, Iwate 028-3694 (Japan)

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer A JNK inhibitor SP600125 inhibited cAMP-dependent proteolysis of GATA-6. Black-Right-Pointing-Pointer Effect of a JNK activator anisomycin on the proteolysis was examined. Black-Right-Pointing-Pointer Anisomycin stimulated the export of nuclear GATA-6 into the cytoplasm. Black-Right-Pointing-Pointer JNK activated the CRM1 mediated nuclear export of GATA-6. Black-Right-Pointing-Pointer JNK further stimulated slowly the degradation of GATA-6 by cytoplasmic proteasomes. -- Abstract: A JNK inhibitor SP600125 inhibited cAMP-dependent proteolysis of GATA-6 by proteasomes around its IC50. We further examined the effects of SP600125 on the degradation of GATA-6 in detail, since an activator of JNK (anisomycin) is available. Interestingly, anisomycin immediately stimulated the export of nuclear GATA-6 into the cytoplasm, and then the cytoplasmic content of GATA-6 decreased slowly through degradation by proteasomes. Such an effect of anisomycin was inhibited by SP600125, indicating that the observed phenomenon might be linked to the JNK signaling pathway. The inhibitory effect of SP600125 could not be ascribed to the inhibition of PKA, since phosphorylation of CREB occurred in the presence of dbcAMP and SP600125. The nuclear export of GATA-6 was inhibited by leptomycin B, suggesting that CRM1-mediated export could be activated by anisomycin. Furthermore, it seems likely that the JNK activated by anisomycin may stimulate not only the nuclear export of GATA-6 through CRM1 but also the degradation of GATA-6 by cytoplasmic proteasomes. In contrast, A-kinase might activate only the latter process through JNK.

  1. Use of high-gradient magnetic fishing for reducing proteolysis during fermentation

    DEFF Research Database (Denmark)

    Maury, Trine Lütken; Ottow, Kim Ekelund; Brask, Jesper

    2012-01-01

    Proteolysis during fermentation may have a severe impact on the yield and quality of a secreted product. In the current study, we demonstrate the use of high-gradient magnetic fishing (HGMF) as an efficient alternative to the more conventional methods of preventing proteolytic degradation....... Bacitracin-linked magnetic affinity adsorbents were employed directly in a fermenter during Bacillus licheniformis cultivation to remove trace amounts of unwanted proteases. The constructed magnetic adsorbents had excellent, highly specific binding characteristics in the fermentation broth (K(d) = 1...

  2. Determinants of Proteolysis and Cell-Binding for the Shigella flexneri Cytotoxin, SigA.

    Science.gov (United States)

    Chua, Eng Guan; Al-Hasani, Keith; Scanlon, Martin; Adler, Ben; Sakellaris, Harry

    2015-11-01

    Shigella flexneri secretes an enterotoxic, SPATE family autotransporter (AT), SigA, which has cytopathic activity towards cultured epithelial cells. Its cytopathic activity is due to its ability to degrade the cytoskeletal protein, α-fodrin. The mechanisms by which AT toxins target cells and tissues differ and the details of how SigA acts are not known. In the current study, the determinants of proteolysis and cell-targeting for SigA were determined. We demonstrate that the SigA passenger or α-domain consists of two functionally distinct domains, designated α1 and α2, which are sufficient to specify proteolytic and cell-binding activities, respectively.

  3. Modification of carbon fabrics by radio-frequency capacitive discharge at low pressure to regulate mechanical properties of carbon fiber reinforced plastics based on it

    Science.gov (United States)

    Garifullin, A. R.; Krasina, I. V.; Skidchenko, E. A.; Shaekhov, M. F.; Tikhonova, N. V.

    2017-01-01

    To increase the values of mechanical properties of carbon fiber (CF) composite materials used in sports equipment production the method of radio-frequency capacitive (RFC) low-pressure plasma treatment in air was proposed. Previously it was found that this type of modification allows to effectively regulate the surface properties of fibers of different nature. This treatment method differs from the traditional ones by efficiency and environmental friendliness as it does not require the use of aggressive, environmentally hazardous chemicals. In this paper it was established that RFC low-pressure air plasma treatment of carbon fabrics enhances the interlaminar shear strength (ILSS) of carbon fiber reinforced plastic (CFRP). As a result of experimental studies of CF by Fourier Transform Infrared (FTIR) spectroscopy method it was proved that after radio-frequency capacitive plasma treatment at low pressure in air the oxygen-containing functional groups is grafted on the surface. These groups improve adhesion at the interface “matrix-fiber”.

  4. Self-consistent system of equations for a kinetic description of the low-pressure discharges accounting for the nonlocal and collisionless electron dynamics.

    Science.gov (United States)

    Kaganovich, Igor D; Polomarov, Oleg

    2003-08-01

    In low-pressure discharges, where the electron mean free path is larger or comparable with the discharge length, the electron dynamics is essentially nonlocal. Moreover, the electron energy distribution function (EEDF) deviates considerably from a Maxwellian. Therefore, an accurate kinetic description of the low-pressure discharges requires knowledge of the nonlocal conductivity operator and calculation of the non-Maxwellian EEDF. The previous treatments made use of simplifying assumptions: a uniform density profile and a Maxwellian EEDF. In the present study, a self-consistent system of equations for the kinetic description of nonlocal, nonuniform, nearly collisionless plasmas of low-pressure discharges is derived. It consists of the nonlocal conductivity operator and the averaged kinetic equation for calculation of the non-Maxwellian EEDF. The importance of accounting for the nonuniform plasma density profile on both the current density profile and the EEDF is demonstrated.

  5. The Recovery and Power Generation Technology for Low Pressure Exhaust Steam%低压放散蒸汽回收发电技术

    Institute of Scientific and Technical Information of China (English)

    戴海波

    2015-01-01

    对钢铁企业低压饱和蒸汽管网运行情况进行研究,分析总结低压低温饱和的间断性放散蒸汽放散规律,通过放散蒸汽的有效回收,并利用螺杆膨胀机发电技术,形成低压饱和蒸汽资源化和再利用的项目方案。%The operation state of low pressure saturated steam pipeline networks of steel enterprises was investigated and the pattern of intermittent exhausting of low-pressure low-temperature saturated steam was analyzed. Through effective recovery of the exhaust steam and adopting of the power generation technology of screw expander, a project plan for recy-cling and utilization of low pressure saturated steam was drawn up.

  6. 300 kt/a低压氨合成技术应用总结%Sum-Up of Use of 300 kt/a Low Pressure Ammonia Synthesis Technology

    Institute of Scientific and Technical Information of China (English)

    位洪朋; 左玉香; 李守军

    2014-01-01

    A detailed description is given of system configuration , catalyst loading , reduction by heating of catalyst and production operation of 300 kt/a low pressure ammonia synthesis plant .From the commissioning of low pressure ammonia synthesis plant , each technique index is ideal , indicating that GC type low pressure ammonia synthesis technology is relatively mature , stable , reliable and advanced .%详细介绍了300 kt/a低压氨合成装置的系统配置、催化剂装填、催化剂升温还原、生产运行等情况。低压氨合成装置投运后,各项工艺指标均较为理想,表明GC型低压氨合成技术较为成熟、稳定、可靠、先进。

  7. Pathogen-mediated proteolysis of the cell death regulator RIPK1 and the host defense modulator RIPK2 in human aortic endothelial cells.

    Directory of Open Access Journals (Sweden)

    Andrés G Madrigal

    Full Text Available Porphyromonas gingivalis is the primary etiologic agent of periodontal disease that is associated with other human chronic inflammatory diseases, including atherosclerosis. The ability of P. gingivalis to invade and persist within human aortic endothelial cells (HAEC has been postulated to contribute to a low to moderate chronic state of inflammation, although how this is specifically achieved has not been well defined. In this study, we demonstrate that P. gingivalis infection of HAEC resulted in the rapid cleavage of receptor interacting protein 1 (RIPK1, a mediator of tumor necrosis factor (TNF receptor-1 (TNF-R1-induced cell activation or death, and RIPK2, a key mediator of both innate immune signaling and adaptive immunity. The cleavage of RIPK1 or RIPK2 was not observed in cells treated with apoptotic stimuli, or cells stimulated with agonists to TNF-R1, nucleotide oligomerization domain receptor 1(NOD1, NOD2, Toll-like receptor 2 (TLR2 or TLR4. P. gingivalis-induced cleavage of RIPK1 and RIPK2 was inhibited in the presence of a lysine-specific gingipain (Kgp inhibitor. RIPK1 and RIPK2 cleavage was not observed in HAEC treated with an isogenic mutant deficient in the lysine-specific gingipain, confirming a role for Kgp in the cleavage of RIPK1 and RIPK2. Similar proteolysis of poly (ADP-ribose polymerase (PARP was observed. We also demonstrated direct proteolysis of RIPK2 by P. gingivalis in a cell-free system which was abrogated in the presence of a Kgp-specific protease inhibitor. Our studies thus reveal an important role for pathogen-mediated modification of cellular kinases as a potential strategy for bacterial persistence within target host cells, which is associated with low-grade chronic inflammation, a hallmark of pathogen-mediated chronic inflammatory disorders.

  8. Pathogen-mediated proteolysis of the cell death regulator RIPK1 and the host defense modulator RIPK2 in human aortic endothelial cells.

    Science.gov (United States)

    Madrigal, Andrés G; Barth, Kenneth; Papadopoulos, George; Genco, Caroline Attardo

    2012-01-01

    Porphyromonas gingivalis is the primary etiologic agent of periodontal disease that is associated with other human chronic inflammatory diseases, including atherosclerosis. The ability of P. gingivalis to invade and persist within human aortic endothelial cells (HAEC) has been postulated to contribute to a low to moderate chronic state of inflammation, although how this is specifically achieved has not been well defined. In this study, we demonstrate that P. gingivalis infection of HAEC resulted in the rapid cleavage of receptor interacting protein 1 (RIPK1), a mediator of tumor necrosis factor (TNF) receptor-1 (TNF-R1)-induced cell activation or death, and RIPK2, a key mediator of both innate immune signaling and adaptive immunity. The cleavage of RIPK1 or RIPK2 was not observed in cells treated with apoptotic stimuli, or cells stimulated with agonists to TNF-R1, nucleotide oligomerization domain receptor 1(NOD1), NOD2, Toll-like receptor 2 (TLR2) or TLR4. P. gingivalis-induced cleavage of RIPK1 and RIPK2 was inhibited in the presence of a lysine-specific gingipain (Kgp) inhibitor. RIPK1 and RIPK2 cleavage was not observed in HAEC treated with an isogenic mutant deficient in the lysine-specific gingipain, confirming a role for Kgp in the cleavage of RIPK1 and RIPK2. Similar proteolysis of poly (ADP-ribose) polymerase (PARP) was observed. We also demonstrated direct proteolysis of RIPK2 by P. gingivalis in a cell-free system which was abrogated in the presence of a Kgp-specific protease inhibitor. Our studies thus reveal an important role for pathogen-mediated modification of cellular kinases as a potential strategy for bacterial persistence within target host cells, which is associated with low-grade chronic inflammation, a hallmark of pathogen-mediated chronic inflammatory disorders.

  9. Increase in ubiquitin-protein conjugates concomitant with the increase in proteolysis in rat skeletal muscle during starvation and atrophy denervation

    Science.gov (United States)

    Wing, S. S.; Haas, A. L.; Goldberg, A. L.

    1995-01-01

    The rapid loss of skeletal-muscle protein during starvation and after denervation occurs primarily through increased rates of protein breakdown and activation of a non-lysosomal ATP-dependent proteolytic process. To investigate whether protein flux through the ubiquitin (Ub)-proteasome pathway is enhanced, as was suggested by related studies, we measured, using specific polyclonal antibodies, the levels of Ub-conjugated proteins in normal and atrophying muscles. The content of these critical intermediates had increased 50-250% after food deprivation in the extensor digitorum longus and soleus muscles 2 days after denervation. Like rates of proteolysis, the amount of Ub-protein conjugates and the fraction of Ub conjugated to proteins increased progressively during food deprivation and returned to normal within 1 day of refeeding. During starvation, muscles of adrenalectomized rats failed to increase protein breakdown, and they showed 50% lower levels of Ub-protein conjugates than those of starved control animals. The changes in the pools of Ub-conjugated proteins (the substrates for the 26S proteasome) thus coincided with and can account for the alterations in overall proteolysis. In this pathway, large multiubiquitinated proteins are preferentially degraded, and the Ub-protein conjugates that accumulated in atrophying muscles were of high molecular mass (> 100 kDa). When innervated and denervated gastrocnemius muscles were fractionated, a significant increase in ubiquitinated proteins was found in the myofibrillar fraction, the proteins of which are preferentially degraded on denervation, but not in the soluble fraction. Thus activation of this proteolytic pathway in atrophying muscles probably occurs initially by increasing Ub conjugation to cell proteins. The resulting accumulation of Ub-protein conjugates suggests that their degradation by the 26S proteasome complex subsequently becomes rate-limiting in these catabolic states.

  10. Free-stream Turbulence Effects on the Boundary Layer of a High-lift Low-Pressure-Turbine Blade

    Institute of Scientific and Technical Information of China (English)

    Simoni D.; Ubaldi M.; Zunino P.; Ampellio E.

    2016-01-01

    The suction side boundary layer evolution of a high-lift low-pressure turbine cascade has been experimentally investigated at low and high free-stream turbulence intensity conditions.Measurements have been carried out in order to analyze the boundary layer transition and separation processes at a low Reynolds number,under both steady and unsteady inflows.Static pressure distributions along the blade surfaces as well as total pressure distributions in a downstream tangential plane have been measured to evaluate the overall aerodynamic efficiency of the blade for the different conditions.Particle Image Velocimetry has been adopted to analyze the time-mean and time-varying velocity fields.The flow field has been surveyed in two orthogonal planes (a blade-to-blade plane and a wall-parallel one).These measurements allow the identification of the Kelvin-Helmholtz large scale coherent structures shed as a consequence of the boundary layer laminar separation under steady inflow,as well as the investigation of the three-dimensional effects induced by the intermittent passage of low and high speed streaks.A close inspection of the time-mean velocity profiles as well as of the boundary layer integral parameters helps to characterize the suction side boundary layer state,thus justifying the influence of free-stream turbulence intensity on the blade aerodynamic losses measured under steady and unsteady inflows.

  11. Free-stream turbulence effects on the boundary layer of a high-lift low-pressure-turbine blade

    Science.gov (United States)

    Simoni, D.; Ubaldi, M.; Zunino, P.; Ampellio, E.

    2016-06-01

    The suction side boundary layer evolution of a high-lift low-pressure turbine cascade has been experimentally investigated at low and high free-stream turbulence intensity conditions. Measurements have been carried out in order to analyze the boundary layer transition and separation processes at a low Reynolds number, under both steady and unsteady inflows. Static pressure distributions along the blade surfaces as well as total pressure distributions in a downstream tangential plane have been measured to evaluate the overall aerodynamic efficiency of the blade for the different conditions. Particle Image Velocimetry has been adopted to analyze the time-mean and time-varying velocity fields. The flow field has been surveyed in two orthogonal planes (a blade-to-blade plane and a wall-parallel one). These measurements allow the identification of the Kelvin-Helmholtz large scale coherent structures shed as a consequence of the boundary layer laminar separation under steady inflow, as well as the investigation of the three-dimensional effects induced by the intermittent passage of low and high speed streaks. A close inspection of the time-mean velocity profiles as well as of the boundary layer integral parameters helps to characterize the suction side boundary layer state, thus justifying the influence of free-stream turbulence intensity on the blade aerodynamic losses measured under steady and unsteady inflows.

  12. The Switch from Low-Pressure Sodium to Light Emitting Diodes Does Not Affect Bat Activity at Street Lights.

    Directory of Open Access Journals (Sweden)

    Elizabeth G Rowse

    Full Text Available We used a before-after-control-impact paired design to examine the effects of a switch from low-pressure sodium (LPS to light emitting diode (LED street lights on bat activity at twelve sites across southern England. LED lights produce broad spectrum 'white' light compared to LPS street lights that emit narrow spectrum, orange light. These spectral differences could influence the abundance of insects at street lights and thereby the activity of the bats that prey on them. Most of the bats flying around the LPS lights were aerial-hawking species, and the species composition of bats remained the same after the switch-over to LED. We found that the switch-over from LPS to LED street lights did not affect the activity (number of bat passes, or the proportion of passes containing feeding buzzes, of those bat species typically found in close proximity to street lights in suburban environments in Britain. This is encouraging from a conservation perspective as many existing street lights are being, or have been, switched to LED before the ecological consequences have been assessed. However, lighting of all spectra studied to date generally has a negative impact on several slow-flying bat species, and LED lights are rarely frequented by these 'light-intolerant' bat species.

  13. The effect of the driving frequency on the confinement of beam electrons and plasma density in low pressure capacitive discharges

    CERN Document Server

    Wilczek, S; Schulze, J; Schuengel, E; Brinkmann, R P; Derzsi, A; Korolov, I; Donkó, Z; Mussenbrock, T

    2014-01-01

    The effect of changing the driving frequency on the plasma density and the electron dynamics in a capacitive radio-frequency argon plasma operated at low pressures of a few Pa is investigated by Particle in Cell/Monte Carlo Collisions simulations and analytical modeling. In contrast to previous assumptions the plasma density does not follow a quadratic dependence on the driving frequency in this non-local collisionless regime. Instead, a step-like increase at a distinct driving frequency is observed. Based on the analytical power balance model, in combination with a detailed analysis of the electron kinetics, the density jump is found to be caused by an electron heating mode transition from the classical $\\alpha$-mode into a low density resonant heating mode characterized by the generation of two energetic electron beams at each electrode per sheath expansion phase. These electron beams propagate through the bulk without collisions and interact with the opposing sheath. In the low density mode, the second bea...

  14. Rejection of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) by low pressure reverse osmosis membranes.

    Science.gov (United States)

    Ozaki, H; Ikejima, N; Shimizu, Y; Fukami, K; Taniguchi, S; Takanami, R; Giri, R R; Matsui, S

    2008-01-01

    This paper aims to elucidate retention characteristics of some pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals (EDCs), by two polyamide low pressure reverse osmosis (LPRO) membranes. Feed solution pH did not have an influence on rejections of undissociated solutes, which was most likely governed by adsorption, size exclusion and diffusion simultaneously. Size exclusion was presumably dominant, especially with tight membranes (UTC-70U). Rejections of the solutes with low dipole moment (diffusion coefficient (D(p)). The rejections decreased with increasing D(p) values irrespective of their dipole moments. Rejections of solutes with comparatively larger dipole moments might be dominated by diffusion and/or convection rather than their hydrophobicity. However, rejections of solutes with hydroxyl and carboxyl functional groups by UTC-60 increased with solution pH. More than 80% rejections were obtained for degree of dissociation (alpha)>0.5. Electrostatic repulsion played a key role for rejection of dissociated solutes, especially by loose LPRO membranes. Therefore, assessing the dissociation degree at desired pH values can be a key step to obtain an insight of rejection mechanisms by polyamide membranes.

  15. Indirect desalination of Red Sea water with forward osmosis and low pressure reverse osmosis for water reuse

    KAUST Repository

    Yangali-Quintanilla, Victor

    2011-10-01

    The use of energy still remains the main component of the costs of desalting water. Forward osmosis (FO) can help to reduce the costs of desalination, and extracting water from impaired sources can be beneficial in this regard. Experiments with FO membranes using a secondary wastewater effluent as a feed water and Red Sea water as a draw solution demonstrated that the technology is promising. FO coupled with low pressure reverse osmosis (LPRO) was implemented for indirect desalination. The system consumes only 50% (~1.5 kWh/m3) of the energy used for high pressure seawater RO (SWRO) desalination (2.5-4 kWh/m3), and produces a good quality water extracted from the impaired feed water. Fouling of the FO membranes was not a major issue during long-term experiments over 14 days. After 10 days of continuous FO operation, the initial flux declined by 28%. Cleaning the FO membranes with air scouring and clean water recovered the initial flux by 98.8%. A cost analysis revealed FO per se as viable technology. However, a minimum average FO flux of 10.5 L/m2-h is needed to compete with water reuse using UF-LPRO, and 5.5 L/m2-h is needed to recover and desalinate water at less cost than SWRO. © 2011 Elsevier B.V.

  16. Film analysis employing subtarget effect using 355 nm Nd-YAG laser-induced plasma at low pressure

    Energy Technology Data Exchange (ETDEWEB)

    Hedwig, Rinda [Department of Computer Engineering, Faculty of Computer Studies, Bina Nusantara University, 9 K.H. Syahdan, Jakarta Barat 11480 (Indonesia); Budi, Wahyu Setia [Department of Physics, Faculty of Mathematics and Natural Sciences, Diponegoro University, Tembalang Campus, Semarang, Central Java (Indonesia); Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh, Nanggroe Aceh Darussalam (Indonesia); Pardede, Marincan [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Suliyanti, Maria Margaretha [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Lie, Tjung Jie [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Kurniawan, Davy Putra [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia); Kurniawan, Koo Hendrik [Research Center of Maju Makmur Mandiri Foundation, 40 Srengseng Raya, Kembangan, Jakarta Barat 11630 (Indonesia)]. E-mail: kurnia18@cbn.net.id; Kagawa, Kiichiro [Department of Physics, Faculty of Education and Regional Studies, 9-1 bunkyo 3-chome, Fukui 910-8507 (Japan); Tjia, May On [Department of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)

    2006-12-15

    The applicability of spectrochemical analysis for liquid and powder samples of minute amount in the form of thin film was investigated using ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A variety of organic samples such as commercial black ink usually used for stamp pad, ginseng extract, human blood, liquid milk and ginseng powder was prepared as film deposited on the surface of an appropriate hard substrate such as copper plate or glass slide. It was demonstrated that in all cases studied, good quality spectra were obtained with very low background and free from undesirable contamination by the substrate elements, featuring ppm or even sub-ppm sensitivity and worthy of application for quantitative analysis of organic samples. The proper preparation of the films was found to be crucial in achieving the high quality spectra. It was further shown that much inferior results were obtained when the atmospheric-pressure (101 kPa) operating condition of laser-induced breakdown spectroscopy or the fundamental wavelength of the Nd-YAG laser was employed due to the excessive or improper laser ablation process.

  17. Controllable Generation of a Submillimeter Single Bubble in Molten Metal Using a Low-Pressure Macrosized Cavity

    Science.gov (United States)

    Konovalenko, Alexander; Sköld, Per; Kudinov, Pavel; Bechta, Sevostian; Grishchenko, Dmitry

    2017-04-01

    We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies where a controllable generation of a single submillimeter bubble in opaque hot liquid is required. The method resolves difficulties with bubble detachment from the orifice, wettability issues, capillary channel and orifice surfaces degradation due to contact with corrosive hot liquid, etc. The macrosized, 5- to 50-mm3 cavity is drilled in the solid part of the pool. Flushing the cavity with gas, vacuuming it to low pressure, as well as sealing and consequent remelting cause cavity implosion due to a few orders in magnitude pressure difference between the cavity and the molten pool. We experimentally demonstrate a controllable production of single bubbles ranging from a few milliliters down to submillimeter size. The uncertainties in size and bubble release timing are estimated and compared with experimental observations for bubbles ranging within 0.16 to 4 mm in equivalent-volume sphere diameter. Our results are obtained in heavy liquid metals such as Wood's and Lead-Bismuth eutectics at 353 K to 423 K (80 °C to 150 °C).

  18. Feasibility study of a dedicated nuclear desalination system: Low-pressure Inherent heat sink Nuclear Desalination plant (LIND

    Directory of Open Access Journals (Sweden)

    Ho Sik Kim

    2015-04-01

    Full Text Available In this paper, we suggest the conceptual design of a water-cooled reactor system for a low-pressure inherent heat sink nuclear desalination plant (LIND that applies the safety-related design concepts of high temperature gas-cooled reactors to a water-cooled reactor for inherent and passive safety features. Through a scoping analysis, we found that the current LIND design satisfied several essential thermal–hydraulic and neutronic design requirements. In a thermal–hydraulic analysis using an analytical method based on the Wooton–Epstein correlation, we checked the possibility of safely removing decay heat through the steel containment even if all the active safety systems failed. In a neutronic analysis using the Monte Carlo N-particle transport code, we estimated a cycle length of approximately 6 years under 200 MWth and 4.5% enrichment. The very long cycle length and simple safety features minimize the burdens from the operation, maintenance, and spent-fuel management, with a positive impact on the economic feasibility. Finally, because a nuclear reactor should not be directly coupled to a desalination system to prevent the leakage of radioactive material into the desalinated water, three types of intermediate systems were studied: a steam producing system, a hot water system, and an organic Rankine cycle system.

  19. Numerical investigation of the film uniformity during the surface coating of charged nanoparticles in a low pressure plasma reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pourali, N.; Foroutan, G., E-mail: foroutan@sut.ac.ir

    2016-07-15

    The uniformity of film deposition on charged nanoparticles, trapped near the sheath of a capacitively coupled plasma reactor, is studied by numerical simulation of the multi-fluid plasma equations, surface deposition processes, and nanoparticle heating effects. It is found that the anisotropy in the ion flux onto the powered electrode may be hold responsible for the film nonuniformity. The nonuniformity increases with increasing of the particle radius, although small particles lose sphericity faster than the large particles. Because of the electron temperature dependence of the deposition rate and the incident ion flux, higher electron temperatures lead to more nonuniform film deposition. However, the uniformity is improved and the sphericity is restored by the increase in the background gas pressure and/or temperature. - Highlights: • The surface coating of charged nanoparticles in a low pressure plasma is investigated by numerical simulation of the multi-fluid plasma equations. • The deposition rate on the particle surface is not spatially uniform. • The nonuniformity in the film deposition is attributed to the anisotropy of the ion flux. • The nonuniformity increases with distance from the sheath edge.

  20. Kinetics of low-pressure, low-temperature graphene growth: toward single-layer, single-crystalline structure.

    Science.gov (United States)

    Mehdipour, Hamid; Ostrikov, Kostya Ken

    2012-11-27

    Graphene grown on metal catalysts with low carbon solubility is a highly competitive alternative to exfoliated and other forms of graphene, yet a single-layer, single-crystal structure remains a challenge because of the large number of randomly oriented nuclei that form grain boundaries when stitched together. A kinetic model of graphene nucleation and growth is developed to elucidate the effective controls of the graphene island density and surface coverage from the onset of nucleation to the full monolayer formation in low-pressure, low-temperature CVD. The model unprecedentedly involves the complete cycle of the elementary gas-phase and surface processes and shows a precise quantitative agreement with the recent low-energy electron diffraction measurements and also explains numerous parameter trends from a host of experimental reports. These agreements are demonstrated for a broad pressure range as well as different combinations of precursor gases and supporting catalysts. The critical role of hydrogen in controlling the graphene nucleation and monolayer formation is revealed and quantified. The model is generic and can be extended to even broader ranges of catalysts and precursor gases/pressures to enable the as yet elusive effective control of the crystalline structure and number of layers of graphene using the minimum amounts of matter and energy.

  1. Evidence for skill level differences in the thought processes of golfers during high and low pressure situations.

    Directory of Open Access Journals (Sweden)

    Amy Elizabeth Whitehead

    2016-01-01

    Full Text Available Two studies examined differences in the cognition of golfers with differing levels of expertise in high and low pressure situations. In study 1, six high skill and six low skill golfers performed six holes of golf, while verbalizing their thoughts using Think Aloud (TA protocol. Higher skilled golfers’ cognitive processes centered more on planning in comparison to lower skilled golfers. Study 2 investigated whether thought processes of golfers changed in response to competitive pressure. Eight high skill and eight moderate skilled golfers, completed a practice round and a competition round whilst verbalizing thoughts using TA. To create pressure in the competition condition, participants were instructed that monetary prizes would be awarded to the top three performers and scores of all golfers would be published in a league table in the club house. When performing under competitive pressure, it was found that higher skilled golfers were more likely to verbalize technical rules compared to practice conditions, especially during putting performance. This shift in cognition toward more technical aspects of motor performance was strongly related to scores on the Decision Specific Reinvestment Scale, suggesting individuals with a higher propensity for reinvestment show the largest changes in cognition under pressure. From a practical perspective, TA can aid a player, coach or sport psychologist by allowing thought processes to be identified and investigate a performer’s thoughts when faced with the pressure of a competition.

  2. Gating system optimization of low pressure casting A356 aluminum alloy intake manifold based on numerical simulation

    Directory of Open Access Journals (Sweden)

    Jiang Wenming

    2014-03-01

    Full Text Available To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on filling and solidification processes of the casting was carried out using the ProCAST software. The gating system of the casting is optimized according to the simulation results. Results show that when the gating system consists of only one sprue, the filling of the molten metal is not stable; and the casting does not follow the sequence solidification, and many shrinkage porosities are observed through the casting. After the gating system is improved by adding one runner and two in-gates, the filling time is prolonged from 4.0 s to 4.5 s, the filling of molten metal becomes stable, but this casting does not follow the sequence solidification either. Some shrinkage porosity is also observed in the hot spots of the casting. When the gating system was further improved by adding risers and chill to the hot spots of the casting, the shrinkage porosity defects were eliminated completely. Finally, by using the optimized gating system the A356 aluminum alloy intake manifold casting with integrated shape and smooth surface as well as dense microstructure was successfully produced.

  3. The effects of process parameters on yield and properties of iron nanoparticles from ferrocene in a low-pressure plasma

    Science.gov (United States)

    Panchal, V.; Lahoti, G.; Bhandarkar, U.; Neergat, M.

    2011-08-01

    The effects of process parameters on iron nanoparticle formation and properties while using ferrocene as a precursor in a low-pressure capacitively coupled plasma are investigated. The L18 array of the Taguchi method, followed by the L4 array, is used with the notional objective of increasing the yield of nanoparticles. A study of the size, shape and composition of the particles (using transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, x-ray diffraction, CHON and inductively coupled plasma-atomic emission spectroscopy analysis) gives an insight into the role played by various process parameters. Pressure is the most critical parameter in increasing nanoparticle yield, whereas hydrogen flow plays a key role in determining the nanoparticle size and composition. Atomic hydrogen helps in removing amorphous carbon and reducing the nanoparticle size. RF power plays an important role in the dissociation of ferrocene thus also affecting the composition. Nanoparticles obtained using optimized conditions are a mixture of Fe3O4 and Fe2O3 with cluster size 25-40 nm in diameter that are further made up of 2-4 nm crystallites. Magnetic property measurements indicate that the nanoparticles are super-paramagnetic in nature.

  4. Parametric study of low-pressure electron beam generated Ar–SF6 plasma and implications for processing

    Science.gov (United States)

    Petrov, G. M.; Petrova, Tz B.; Boris, D. R.; Walton, S. G.

    2017-09-01

    The dissociation products and fluxes of sulfur hexafluoride are theoretically studied in electron beam generated plasmas produced in Ar–SF6 mixtures at low pressure (10–100 mTorr). Parameter variation is used to determine scaling laws, which are otherwise difficult to derive analytically and time consuming to determine empirically. Volume-averaged densities of SF6 dissociation products such as SF x , x = 1…5, F2 and F, as well as electron and ion fluxes on reactor wall are calculated using a one-dimensional steady-state hydrodynamic model. It is established that SF x and F2 have similar trends with the variation of pressure, electron beam current and SF6 concentration, while the scaling of F atoms is markedly different. Attention is paid to the ratio of absorbed neutral-to-ion flux on the reactor wall due to its importance for ion-assisted etching in reactive plasmas. At typical operating conditions, this ratio is between 10 and 103. At very low SF6 concentrations (<1%), F atoms dominate the radical flux to the reactor walls. In contrast, at concentrations above 1%, SF x radicals deliver the most F to the walls.

  5. Tailoring surface properties of polyethylene separator by low pressure 13.56 MHz RF oxygen plasma glow discharge

    Science.gov (United States)

    Li, Chun; Liang, Chia-Han; Huang, Chun

    2016-01-01

    Low-pressure plasma surface modification in a radio-frequency capacitively coupled glow discharge of oxygen gas was carried out to induce polar functional groups onto polyethylene membrane separator surfaces to enhance its hydrophilicity. The surface changes in surface free energy were monitored by static contact angle measurement. A significant increase in the surface energy of polyethylene membrane separators caused by the oxygen gas plasma modifications was observed. The static water contact angle of the plasma-modified membrane separator significantly decreased with the increase in treatment duration and plasma power. An obvious increase in the surface energy of the membrane separators owing to the oxidative effect of oxygen-gas-plasma modifications was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated by oxygen gas plasma surface modification. The variations in the surface morphology and chemical structure of the separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS showed significantly higher surface concentrations of oxygen functional groups in the oxygen-gas-plasma-modified polymeric separator surfaces than in the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between oxygen gas plasmas and the separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the separator.

  6. One-dimensional Ar-SF{sub 6} hydromodel at low-pressure in e-beam generated plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, George M., E-mail: george.petrov@nrl.navy.mil; Boris, David R.; Petrova, Tzvetelina B.; Walton, Scott G. [Plasma Physics Division, Naval Research Laboratory, 4555 Overlook Ave. SW, Washington DC 20375-5346 (United States)

    2016-03-15

    A one-dimensional steady-state hydrodynamic model of electron beam generated plasmas produced in Ar-SF{sub 6} mixtures at low pressure in a constant magnetic field was developed. Simulations were performed for a range of SF{sub 6} partial pressures at constant 30 mTorr total gas pressure to determine the spatial distribution of species densities and fluxes. With the addition of small amount of SF{sub 6} (∼1%), the confining electrostatic field sharply decreases with respect to the pure argon case. This effect is due to the applied magnetic field inhibiting electron diffusion. The hallmark of electronegative discharge plasmas, positive ion—negative ion core and positive ion—electron edge, was not observed. Instead, a plasma with large electronegativity (∼100) is formed throughout the volume, and only a small fraction (≈30%) of the parent SF{sub 6} molecules were dissociated to F{sub 2}, SF{sub 2}, and SF{sub 4}. Importantly, F radical densities were found to be very low, on the order of the ion density. Model predictions for the electron density, ion density, and plasma electronegativity are in good agreement with experimental data over the entire range of SF{sub 6} concentrations investigated.

  7. Microstructural Characteristics and Oxidation Behavior of Low-Pressure Cold-Sprayed CoNiCrAlY Coatings

    Science.gov (United States)

    Zhang, Lin-wei; Lu, Lei; Wang, Lu; Ning, Xian-jin; Wang, Quan-sheng; Wang, Ri-xin

    2017-09-01

    CoNiCrAlY coatings were deposited by low-pressure cold spraying and subsequently heat-treated at 1050 °C for 4 h in a vacuum environment. The microstructural characteristics and oxidation behavior of CoNiCrAlY coatings were investigated. The as-sprayed coating exhibited low porosity and oxygen content. The high plastic deformation of the sprayed particles led to significant refinement of γ-matrix and dissolution of β-(Ni,Co)Al phase in the as-sprayed coating. After heat treatment, the single phase (γ) in the as-sprayed coating was converted into a γ/β microstructure, and a continuous single α-Al2O3 scale was formed on the coating surface. Vacuum heat treatment can postpone the formation of spinel oxides within 100 h. After being oxidized at 1050 °C for 400 h, the heat-treated coating exhibited better oxidation resistance than the as-sprayed coating. The reduced growth rate of the oxide scale and the suppression of the formation of spinel oxides can be attributed to the vacuum heat treatment, as well as the intrinsic microstructure of the cold-sprayed coating. Finally, the effects of the microstructural changes induced during the cold spraying process on the growth of the thermally grown oxide and the oxidation mechanisms of the CoNiCrAlY coatings were discussed.

  8. Mass spectrometry of positive ions in capacitively coupled low pressure RF discharges in oxygen with water impurities

    Science.gov (United States)

    Stefanović, Ilija; Stojanović, Vladimir; Boulmer-Leborgne, Chantal; Lecas, Thomas; Kovacevic, Eva; Berndt, Johannes

    2016-07-01

    A capacitively coupled RF oxygen discharge is studied by means of mass spectroscopy. Mass spectra of neutral and positive species are measured in the mid plane between the electrodes at different distances between plasma and mass-spectrometer orifice. In the case of positive ions, as expected, the largest flux originates from \\text{O}2+ . However, a significant number of impurities are detected, especially for low input powers and larger distances. The most abundant positive ions (besides \\text{O}2+ ) are \\text{N}{{\\text{O}}+}, \\text{NO}2+ , {{\\text{H}}+}≤ft({{\\text{H}}2}\\text{O}\\right) , and {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}2} . In particular, for the case of hydrated hydronium ions {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}n} (n  =  1, 2) a surprisingly large flux (for low pressure plasma conditions) is detected. Another interesting fact concerns the {{\\text{H}}2}{{\\text{O}}+} ions. Despite the relatively high ammount of water impurities {{\\text{H}}2}{{\\text{O}}+} ions are present only in traces. The reaction mechanisms leading to the production of the observed ions, especially the hydrated hydronium ions are discussed.

  9. Comparison of ultraviolet light-emitting diodes and low-pressure mercury-arc lamps for disinfection of water.

    Science.gov (United States)

    Sholtes, Kari A; Lowe, Kincaid; Walters, Glenn W; Sobsey, Mark D; Linden, Karl G; Casanova, Lisa M

    2016-09-01

    Ultraviolet (UV) light-emitting diodes (LEDs) emitting at 260 nm were evaluated to determine the inactivation kinetics of bacteria, viruses, and spores compared to low-pressure (LP) UV irradiation. Test microbes were Escherichia coli B, a non-enveloped virus (MS-2), and a bacterial spore (Bacillus atrophaeus). For LP UV, 4-log10 reduction doses were: E. coli B, 6.5 mJ/cm(2); MS-2, 59.3 mJ/cm(2); and B. atrophaeus, 30.0 mJ/cm(2). For UV LEDs, the 4-log10 reduction doses were E. coli B, 6.2 mJ/cm(2); MS-2, 58 mJ/cm(2); and B. atrophaeus, 18.7 mJ/cm(2). Microbial inactivation kinetics of the two UV technologies were not significantly different for E. coli B and MS-2, but were different for B. atrophaeus spores. UV LEDs at 260 nm are at least as effective for inactivating microbes in water as conventional LP UV sources and should undergo further development in treatment systems to disinfect drinking water.

  10. Impact of low-pressure glow-discharge-pulsed plasma polymerization on properties of polyaniline thin films

    Science.gov (United States)

    Jatratkar, Aviraj A.; Yadav, Jyotiprakash B.; Deshmukh, R. R.; Barshilia, Harish C.; Puri, Vijaya; Puri, R. K.

    2016-12-01

    This study reports on polyaniline thin films deposited on a glass substrate using a low-pressure glow-discharge-pulsed plasma polymerization method. The polyaniline thin film obtained by pulsed plasma polymerization has been successfully demonstrated as an optical waveguide with a transmission loss of 3.93 dB cm-1, and has the potential to be employed in integrated optics. An attempt has been made to investigate the effect of plasma OFF-time on the structural, optical as well as surface properties of polyaniline thin film. The plasma ON-time has been kept constant and the plasma OFF-time has been varied throughout the work. The plasma OFF-time strongly influenced the properties of the polyaniline thin film, and a nanostructured and compact surface was revealed in the morphological studies. The plasma OFF-time was found to enhance film thickness, roughness, refractive index and optical transmission loss, whereas it reduced the optical band gap of the polyaniline thin films. Retention in the aromatic structure was confirmed by FTIR results. Optical studies revealed a π-π* electronic transition at about 317 nm as well as the formation of a branched structure. As compared with continuous wave plasma, pulsed plasma polymerization shows better properties. Pulsed plasma polymerization reduced the roughness of the film from 1.2 nm to 0.42 nm and the optical transmission loss from 6.56 dB cm-1 to 3.39 dB cm-1.

  11. Exploring the Utilization of Low-Pressure, Piston-Cylinder Experiments to Determine the Bulk Compositions of Finite, Precious Materials

    Science.gov (United States)

    Vander Kaaden, K. E.; McCubbin, F. M.; Harrington, A. D.

    2017-01-01

    Determining the bulk composition of precious materials with a finite mass (e.g., meteorite samples) is extremely important in the fields of Earth and Planetary Science. From meteorite studies we are able to place constraints on large scale planetary processes like global differentiation and subsequent volcanism, as well as smaller scale processes like crystallization in a magma chamber or sedimentary compaction at the surface. However, with meteorite samples in particular, far too often we are limited by how precious the sample is as well as its limited mass. In this study, we have utilized aliquots of samples previously studied for toxicological hazards, including both the fresh samples (lunar mare basalt NWA 4734, lunar regolith breccia NWA 7611, martian basalt Tissint, martian regolith breccia NWA 7034, a vestian basalt Berthoud, a vestian regolith breccia NWA 2060, and a terrestrial mid-ocean ridge basalt (MORB)), and those that underwent iron leaching (Tissint, NWA 7034, NWA 4734, MORB). With these small masses of material, we performed low pressure (approx. 0.75 GPa), high temperature (greater than 1600 degrees Celsius) melting experiments. Each sample was analyzed using a JEOL 8530F electron microprobe to determine the bulk composition of the materials that were previously examined. When available, the results of our microprobe data were compared with bulk rock compositions in the literature. The results of this study show that with this technique, only approx. 50 mg of sample is required to accurately determine the bulk composition of the materials of interest.

  12. Feasibility study of a dedicate nuclear desalination system: Low-pressure inherent heat sink nuclear desalination plant (LIND)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ho Sik; No, Hee Cheon; Jo, Yu Gwan; Wivisono, Andhika Feri; Park, Byung Ha; Choi, Jin Young; Lee, Jeong Ik; Jeong, Yong Hoon; Cho, Nam Zin [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2015-04-15

    In this paper, we suggest the conceptual design of a water-cooled reactor system for a low-pressure inherent heat sink nuclear desalination plant (LIND) that applies the safety-related design concepts of high temperature gas-cooled reactors to a water-cooled reactor for inherent and passive safety features. Through a scoping analysis, we found that the current LIND design satisfied several essential thermal-hydraulic and neutronic design requirements. In a thermal-hydraulic analysis using an analytical method based on the Wooton-Epstein correlation, we checked the possibility of safely removing decay heat through the steel containment even if all the active safety systems failed. In a neutronic analysis using the Monte Carlo N-particle transport code, we estimated a cycle length of approximately 6 years under 200 MW{sub th} and 4.5% enrichment. The very long cycle length and simple safety features minimize the burdens from the operation, maintenance, and spent-fuel management, with a positive impact on the economic feasibility. Finally, because a nuclear reactor should not be directly coupled to a desalination system to prevent the leakage of radioactive material into the desalinated water, three types of intermediate systems were studied: a steam producing system, a hot water system, and an organic Rankine cycle system.

  13. 2D fluid-analytical simulation of electromagnetic effects in low pressure, high frequency electronegative capacitive discharges

    Science.gov (United States)

    Kawamura, E.; Lichtenberg, A. J.; Lieberman, M. A.; Marakhtanov, A. M.

    2016-06-01

    A fast 2D axisymmetric fluid-analytical multifrequency capacitively coupled plasma (CCP) reactor code is used to study center high nonuniformity in a low pressure electronegative chlorine discharge. In the code, a time-independent Helmholtz wave equation is used to solve for the capacitive fields in the linearized frequency domain. This eliminates the time dependence from the electromagnetic (EM) solve, greatly speeding up the simulations at the cost of neglecting higher harmonics. However, since the code allows up to three driving frequencies, we can add the two most important harmonics to the CCP simulations as the second and third input frequencies. The amplitude and phase of these harmonics are estimated by using a recently developed 1D radial nonlinear transmission line (TL) model of a highly asymmetric cylindrical discharge (Lieberman et al 2015 Plasma Sources Sci. Technol. 24 055011). We find that at higher applied frequencies, the higher harmonics contribute significantly to the center high nonuniformity due to their shorter plasma wavelengths.

  14. The effects of process parameters on yield and properties of iron nanoparticles from ferrocene in a low-pressure plasma

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, V; Neergat, M [Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Lahoti, G; Bhandarkar, U, E-mail: bhandarkar@iitb.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2011-08-31

    The effects of process parameters on iron nanoparticle formation and properties while using ferrocene as a precursor in a low-pressure capacitively coupled plasma are investigated. The L{sub 18} array of the Taguchi method, followed by the L{sub 4} array, is used with the notional objective of increasing the yield of nanoparticles. A study of the size, shape and composition of the particles (using transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, x-ray diffraction, CHON and inductively coupled plasma-atomic emission spectroscopy analysis) gives an insight into the role played by various process parameters. Pressure is the most critical parameter in increasing nanoparticle yield, whereas hydrogen flow plays a key role in determining the nanoparticle size and composition. Atomic hydrogen helps in removing amorphous carbon and reducing the nanoparticle size. RF power plays an important role in the dissociation of ferrocene thus also affecting the composition. Nanoparticles obtained using optimized conditions are a mixture of Fe{sub 3}O{sub 4} and Fe{sub 2}O{sub 3} with cluster size 25-40 nm in diameter that are further made up of 2-4 nm crystallites. Magnetic property measurements indicate that the nanoparticles are super-paramagnetic in nature.

  15. The surface chemistry resulting from low-pressure plasma treatment of polystyrene: The effect of residual vessel bound oxygen

    Science.gov (United States)

    Dhayal, Marshal; Alexander, Morgan R.; Bradley, James W.

    2006-09-01

    The surface chemistry of plasma treated polystyrene samples has been studied in a specially designed low-pressure argon discharge system incorporating in situ XPS analysis. By using an electrostatic grid biasing technique, the plasma source can also be used in a mode preventing ion interactions with the sample. The system, which utilizes a vacuum transfer chamber between plasma and XPS analysis has allowed us to differentiate between the level of oxygen incorporated at the polystyrene surface from residual gas during treatment and that from the exposure of the treated sample to the laboratory atmosphere. Using typical base pressures of about 5 × 10 -3 Pa (4 × 10 -5 Torr) the XPS results show that significant oxygen surface incorporation resulted from oxygen containing species in the plasma itself (i.e. water vapour with 2 × 10 -3 Pa partial pressure). The surface concentration of O was measured at 7.6 at.%. Subsequent atmospheric exposure of the treated samples resulted in only a small increase (of 0.6 at.%) in oxygen incorporation in the form of acid anhydride functionalities. XPS measurements of PS samples exposed to plasmas with no ion-surface component (i.e. exposure from VUV, UV and excited neutral species only) showed no appreciable change in oxygen incorporation compared to those with low-energy ion bombardment from the plasma (free radical sites in this discharge regime.

  16. Acoustic performance of low pressure axial fan rotors with different blade chord length and radial load distribution

    Science.gov (United States)

    Carolus, Thomas

    The paper examines the acoustic and aerodynamic performance of low-pressure axial fan rotors with a hub/tip ratio of 0.45. Six rotors were designed for the same working point by means of the well-known airfoil theory. The condition of an equilibrium between the static pressure gradient and the centrifugal forces is maintained. All rotors have unequally spaced blades to diminish tonal noise. The rotors are tested in a short cylindrical housing without guide vanes. All rotors show very similar flux-pressure difference characteristics. The peak efficiency and the noise performance is considerably influenced by the chosen blade design. The aerodynamically and acoustically optimal rotor is the one with the reduced load at the hub and increased load in the tip region under satisfied equilibrium conditions. It runs at the highest aerodynamic efficiency, and its noise spectrum is fairly smooth. The overall sound pressure level of this rotor is up to 8 dB (A) lower compared to the other rotors under consideration.

  17. Exploring the low-pressure growth limit: evolution of Bacillus subtilis in the laboratory to enhanced growth at 5 kilopascals.

    Science.gov (United States)

    Nicholson, Wayne L; Fajardo-Cavazos, Patricia; Fedenko, Jeffrey; Ortíz-Lugo, José L; Rivas-Castillo, Andrea; Waters, Samantha M; Schuerger, Andrew C

    2010-11-01

    Growth of Bacillus subtilis cells, normally adapted at Earth-normal atmospheric pressure (∼101.3 kPa), was progressively inhibited by lowering of pressure in liquid LB medium until growth essentially ceased at 2.5 kPa. Growth inhibition was immediately reversible upon return to 101.3 kPa, albeit at a slower rate. A population of B. subtilis cells was cultivated at the near-inhibitory pressure of 5 kPa for 1,000 generations, where a stepwise increase in growth was observed, as measured by the turbidity of 24-h cultures. An isolate from the 1,000-generation population was obtained that showed an increase in fitness at 5 kPa when compared to the ancestral strain or a strain obtained from a parallel population that evolved for 1,000 generations at 101.3 kPa. The results from this preliminary study have implications for understanding the ability of terrestrial microbes to grow in low-pressure environments such as Mars.

  18. EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.

  19. Spectrochemical analysis of powder using 355 nm Nd-YAG laser-induced low-pressure plasma.

    Science.gov (United States)

    Lie, Zener S; Pardede, M; Hedwig, R; Suliyanti, M M; Kurniawan, Koo Hendrik; Munadi; Lee, Yong-Inn; Kagawa, Kiichiro; Hattori, Isamu; Tjia, May On

    2008-04-01

    The applicability of spectrochemical analysis of minute amounts of powder samples was investigated using an ultraviolet Nd-YAG laser (355 nm) and low-pressure ambient air. A large variety of chemical powder samples of different composition were employed in the experiment. These included a mixture of copper(II) sulfate pentahydrate, zinc sulfide, and chromium(III) sulfate n-hydrate powders, baby powder, cosmetic powders, gold films, zinc supplement tablet, and muds and soils from different areas. The powder samples were prepared by pulverizing the original samples to an average size of around 30 microm in order to trap them in the tiny micro holes created on the surface of the quartz subtarget. It was demonstrated that in all cases studied, good quality spectra were obtained with low background, free from undesirable contamination by the subtarget elements and featuring ppm sensitivity. A further measurement revealed a linear calibration curve with zero intercept. These results clearly show the potential application of this technique for practical qualitative and quantitative spectrochemical analysis of powder samples in various fields of study and investigation.

  20. Chemically blockable transformation and ultraselective low-pressure gas adsorption in a non-porous metal organic framework.

    Science.gov (United States)

    Xiao, Bo; Byrne, Peter J; Wheatley, Paul S; Wragg, David S; Zhao, Xuebo; Fletcher, Ashleigh J; Thomas, K Mark; Peters, Lars; Evans, John S O; Warren, John E; Zhou, Wuzong; Morris, Russell E

    2009-07-01

    Metal organic frameworks (MOFs) are among the most exciting materials discovered recently, attracting particular attention for their gas-adsorption and -storage properties. Certain MOFs show considerable structural flexibility in response to various stimuli. Although there are several examples of 'breathing' MOFs, in which structural changes occur without any bond breaking, examples of transformations in which several bonds are broken and made are much rarer. In this paper we demonstrate how a flexible MOF, Cu2(OH)(C8H3O7S)(H2O)2H2O, can be synthesized by careful choice of the organic linker ligand. The flexibility can be controlled by addition of a supplementary coordinating molecule, which increases the thermal stability of the solid sufficiently for direct imaging with electron microscopy to be possible. We also demonstrate that the MOF shows unprecedented low-pressure selectivity towards nitric oxide through a coordination-driven gating mechanism. The chemical control over these behaviours offers new possibilities for the synthesis of MOFs with unusual and potentially exploitable properties.

  1. Field-Emission Study of Multi-Walled Carbon Nanotubes Grown On Si Substrate by Low Pressure Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    J. Ali

    2011-01-01

    Full Text Available CNTs are synthesized by Low Pressure Chemical Vapor Deposition (LPCVD method at 600 °C. The Si substrate is coated with Fe, used as a catalyst, by RF- sputtering. The thickness of the catalyst film is measured to be approximately 15 nm. Three precursor gases Acetylene (C2H2, Ammonia (NH3 and Hydrogen (H2 with flow rates 15 sccm, 100 sccm and 100 sccm respectively are allowed to flow through the tube reactor for 20 minutes. The as grown CNTs sample was characterized by Scanning Electron Microscope (SEM. SEM images show that the diameter of as grown CNTs is in the range of 20-50 nm. Field emission properties of as grown sample have also been studied. The CNTs film shows good field emission with turn on field Eα = 2.10 V/μm at the current density of 4.59 mA/cm2 with enhancement factor β = 1.37 × 102.

  2. An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve

    Directory of Open Access Journals (Sweden)

    Christophe Gutfrind

    2016-05-01

    Full Text Available The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP Exhaust Gas Recirculation (EGR valve for use in Internal Combustion Engines (ICEs. The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM using the FLUX-3D® software (CEDRAT, Meylan, France will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink® in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system.

  3. An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve.

    Science.gov (United States)

    Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

    2016-05-20

    The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D(®) software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink(®) in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system.

  4. Controllable Generation of a Submillimeter Single Bubble in Molten Metal Using a Low-Pressure Macrosized Cavity

    Science.gov (United States)

    Konovalenko, Alexander; Sköld, Per; Kudinov, Pavel; Bechta, Sevostian; Grishchenko, Dmitry

    2017-01-01

    We develop a method for generation of a single gas bubble in a pool of molten metal. The method can be useful for applications and research studies where a controllable generation of a single submillimeter bubble in opaque hot liquid is required. The method resolves difficulties with bubble detachment from the orifice, wettability issues, capillary channel and orifice surfaces degradation due to contact with corrosive hot liquid, etc. The macrosized, 5- to 50-mm3 cavity is drilled in the solid part of the pool. Flushing the cavity with gas, vacuuming it to low pressure, as well as sealing and consequent remelting cause cavity implosion due to a few orders in magnitude pressure difference between the cavity and the molten pool. We experimentally demonstrate a controllable production of single bubbles ranging from a few milliliters down to submillimeter size. The uncertainties in size and bubble release timing are estimated and compared with experimental observations for bubbles ranging within 0.16 to 4 mm in equivalent-volume sphere diameter. Our results are obtained in heavy liquid metals such as Wood's and Lead-Bismuth eutectics at 353 K to 423 K (80 °C to 150 °C).

  5. Increasing the efficiency of the axial low pressure compressor in three operation modes by optimizing the shape of its blades

    Science.gov (United States)

    Popov, G. M.; Baturin, O. V.; Goriachkin, E. S.; Novikova, Yu D.; Kolmakova, D. A.

    2017-01-01

    The paper proposes a method for multicriteria optimization of the low pressure compressor working process. The optimization was conducted in three engine modes, corresponding to the temperature of the air at engine inlet --15, +15, +45 °C. Parameters of the compressor were calculated in operational and stall points. The LPC modernization was performed with usage of optimization methods that implemented in the software package IOSO. To perform optimization, the LPC numerical model was created using the NUMECA FineTurbo software. Numerical models of the LPC workflow were created based on the design documentation. The coordinates of three points of a spline in a circumferential direction and a stagger angle were changed for the rotor blades. The coordinates of a mid-point and a point of the trailing edge, stagger angles, and also the position of sections in circumferential and axial directions were changed for the guide vanes. To prevent a shift of the LPC characteristics, we set restrictions for the LPC specific massflow, a minimal pressure raise and astall margin. As a result of this work, a variant of the compressor, ensuring the increase in its efficiency by 1.1% (abs.) and stall margins by 7.5% (abs.) in the primary operation mode has been found.

  6. Low-pressure catalytic wet-air oxidation of a high-strength industrial wastewater using Fenton's reagent.

    Science.gov (United States)

    Biçaksiz, Zeliha; Aytimur, Gülin; Atalay, Süheyda

    2008-06-01

    Wastewater from the Afyon Alkaloids Factory (Afyon, Turkey) was subjected to low-pressure catalytic wet-air oxidation (CWAO) using Fenton's reagent, and the optimal reaction conditions were investigated. The CWAO using Fenton's reagent was applied to the factory effluent, diluted factory effluent, and aerobically pretreated wastewater. To find the optimum quantities of reagents, ferrous iron (Fe(+2))-to-substrate ratios of 1:10, 1:25, and 1:50 and hydrogen peroxide (H2O2)-to-Fe(+2) ratios of 1, 5, and 10 were investigated, and the treatment was carried out at different temperatures. High chemical oxygen demand (COD) removals were obtained at 50 degrees C, with the Fe(+2)-to-substrate ratio range between 1:10 and 1:25. The change in H2O2-to-Fe(+2) ratios did not cause any considerable effect. Also, the percentages of COD removals were nearly the same, so the ratio H2O2:Fe(+2):1 is recommended. Aerobic pretreatment seems to be effective. On the other hand, no enhancement was observed in the case of the diluted wastewater.

  7. Synthesis and characterization of graphene layers prepared by low-pressure chemical vapor deposition using triphenylphosphine as precursor

    Energy Technology Data Exchange (ETDEWEB)

    Mastrapa, G.C.; Maia da Costa, M.E.H. Maia [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ (Brazil); Larrude, D.G., E-mail: dunigl@vdg.fis.puc-rio.br [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ (Brazil); Freire, F.L. [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22451-900, Rio de Janeiro, RJ (Brazil); Brazilian Center for Physical Research, 22290-180, Rio de Janeiro, RJ (Brazil)

    2015-09-15

    The synthesis of a single-layer graphene using a low-pressure Chemical Vapor Deposition (CVD) system with triphenylphosphine as precursor is reported. The amount of triphenylphosphine used as precursor was in the range of 10–40 mg. Raman spectroscopy was employed to analyze samples prepared with 10 mg of the precursor, and these spectra were found typical of graphene. The Raman measurements indicate that the progressive degradation of graphene occurs as the amount of triphenylphosphine increases. X-ray photoelectron spectroscopy measurements were performed to investigate the different chemical environments involving carbon and phosphorous atoms. Scanning electron microscopy and transmission electron microscopy were also employed and the results reveal the formation of dispersed nanostructures on top of the graphene layer, In addition, the number of these nanostructures is directly related to the amount of precursor used for sample growth. - Highlights: • We grow graphene using the solid precursor triphenylphosphine. • Raman analysis confirms the presence of monolayer graphene. • SEM images show the presence of small dark areas dispersed on the graphene surface. • Raman I{sub D}/I{sub G} ratio increases in the dark region of the graphene surface.

  8. Luminance and efficacy improvement of low-pressure xenon pulsed fluorescent lamps by using an auxiliary external electrode

    Science.gov (United States)

    Jinno, Masafumi; Okamoto, Masahiro; Takeda, Masashi; Motomura, Hideki

    2007-07-01

    As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been keeping their interest in developing mercury-free discharge lamps, especially in low-pressure xenon as the most promising UV sources to substitute mercury. In this paper the authors report the effect of auxiliary external electrode (AEE) on the pulsed xenon fluorescent lamps. In this research two types of structures are used. One is the standard type, which has one anode and one cathode inside the lamp. The other is the double anode type, which has two anodes and one cathode inside the lamp. By using the AEE the luminance and the efficacy are improved simultaneously. The luminance is improved by about 129% for the standard structure type and 20% for the double anode type. The efficacy is improved by 60% for the standard type and by 63% for the double anode type. We call this effect/method the Jinno Motomura effect/method (JM-effect/method). Regarding the result of the xenon metastable atom distribution, measured by LIF, this effect is attributed to the plasma potential control and enlargement of the positive column by AEE.

  9. Evaluation of Low Pressure Fogging System for Improving Crop Yield of Tomato (Lycopersicon esculentum Mill.: Grown under Heat Stress Conditions

    Directory of Open Access Journals (Sweden)

    Kobi Shilo

    2013-06-01

    Full Text Available In Mediterranean regions, many tomato plants are grown throughout the hot summer period (May–September in sheltered cultivation, mainly for plant protection reasons. Most of the shelters that are used are low cost net houses covered with 50 mesh insect proof net. In most cases these net houses have a flat roof and no ventilation or climate control measures. This insufficient ventilation during the hot summer leads to above optimal air temperatures and causes moderate heat stress inside the shelters, which leads to yield reduction. The aim of this study was to evaluate the ability of a simple and inexpensive low pressure fogging system installed in a naturally ventilated net house to lower temperatures and improve the yield during the summer. The study showed that in areas where relative air humidity (RH during the daytime is less than 60%, tomato plants improved their performance when grown through the summer in net houses under moderate heat stress. Under fogging conditions pollen grain viability and fruit set were significantly improved. This improvement influenced the yield picked during September (104–136 DAP. However, total seasonal yield was not affected by the fogging treatment.

  10. Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels

    Science.gov (United States)

    Duan, Jianglan; Maijer, Daan; Cockcroft, Steve; Reilly, Carl

    2013-12-01

    A two-phase computational fluid dynamics model of the low-pressure die-cast process for the production of A356 aluminum alloy wheels has been developed to predict the flow conditions during die filling. The filling model represents a 36-deg section of a production wheel, and was developed within the commercial finite-volume package, ANSYS CFX, assuming isothermal conditions. To fully understand the behavior of the free surface, a novel technique was developed to approximate the vent resistances as they impact on the development of a backpressure within the die cavity. The filling model was first validated against experimental data, and then was used to investigate the effects of venting conditions and pressure curves during die filling. It was found that vent resistance and vent location strongly affected die filling time, free surface topography, and air entrainment for a given pressure fill-curve. With regard to the pressure curve, the model revealed a strong relation between the pressure curve and the flow behavior in the hub, which is an area prone to defect formation.

  11. Low-pressure effective fluorescence lifetimes and photo-physical rate constants of one- and two-ring aromatics

    Science.gov (United States)

    Benzler, Thorsten; Faust, Stephan; Dreier, Thomas; Schulz, Christof

    2015-12-01

    One- and two-ring aromatics such as toluene and naphthalene are frequently used molecular tracer species in laser-induced fluorescence (LIF) imaging diagnostics. Quantifying LIF signal intensities requires knowledge of the photo-physical processes that determine the fluorescence quantum yield. Collision-induced and intramolecular energy transfer processes in the excited electronic state closely interact under practical conditions. They can be separated through experiments at variable low pressures. Effective fluorescence lifetimes of gaseous toluene, 1,2,4-trimethylbenzene, anisole, naphthalene, and 1-methylnaphthalene diluted in CO2 were measured after picosecond laser excitation at 266 nm and time-resolved detection of fluorescence intensities. Measurements in an optically accessible externally heated cell between 296 and 475 K and 0.010-1 bar showed that effective fluorescence lifetimes generally decrease with temperature, while the influence of the bath-gas pressure depends on the respective target species and temperature. The results provide non-radiative and fluorescence rate constants and experimentally validate the effect of photo-induced cooling.

  12. LOW PRESSURE CARBURIZING IN A LARGE-CHAMBER DEVICE FOR HIGH-PERFORMANCE AND PRECISION THERMAL TREATMENT OF PARTS OF MECHANICAL GEAR

    Directory of Open Access Journals (Sweden)

    Emilia Wołowiec-Korecka

    2017-03-01

    Full Text Available This paper presents the findings of research of a short-pulse low pressure carburizing technology developed for a new large-chamber furnace for high-performance and precision thermal treatment of parts of mechanical gear. Sections of the article discuss the novel constructions of the device in which parts being carburized flow in a stream, as well as the low-pressure carburizing experiment. The method has been found to yield uniform, even and repeatable carburized layers on typical gear used in automotive industry.

  13. Polymer Surface Treatment by Atmospheric Pressure Low Temperature Surface Discharge Plasma:Its Characteristics and Comparison with Low Pressure Oxygen Plasma Treatment

    Institute of Scientific and Technical Information of China (English)

    Atsushi KUWABARA; Shin-ichi KURODA; Hitoshi KUBOTA

    2007-01-01

    The polymer treatment with a low-temperature plasma jet generated on the atmospheric pressure surface discharge (SD) plasma is performed.The change of the surface property over time,in comparison with low pressure oxygen (O2) plasma treatment,is examined.As one compares the treatment by atmospheric pressure plasma to that by the low pressure O2 plasma of PS (polystyrene) the treatment effects were almost in complete agreement.However,when the atmospheric pressure plasma was used for PP(polypropylene),it produced remarkable hydrophilic effects.

  14. High-frequency data observations from space shuttle main engine low pressure fuel turbopump discharge duct flex joint tripod failure investigation

    Science.gov (United States)

    Zoladz, T. F.; Farr, R. A.

    1991-01-01

    Observations made by Marshall Space Flight Center (MSFC) engineers during their participation in the Space Shuttle Main Engine (SSME) low pressure fuel turbopump discharge duct flex joint tripod failure investigation are summarized. New signal processing techniques used by the Component Assessment Branch and the Induced Environments Branch during the failure investigation are described in detail. Moreover, nonlinear correlations between frequently encountered anomalous frequencies found in SSME dynamic data are discussed. A recommendation is made to continue low pressure fuel (LPF) duct testing through laboratory flow simulations and MSFC-managed technology test bed SSME testing.

  15. Much to know about proteolysis: intricate proteolytic machineries compromise essential cellular functions.

    Science.gov (United States)

    Marfany, Gemma; Farràs, Rosa; Salido, Eduardo; Xirodimas, Dimitris P; Rodríguez, Manuel S

    2008-10-01

    Proteolysis has traditionally been considered as a radical way to terminate the function of a protein. However, protein destruction also is the starting point for many processes as they can only occur when the way has been cleared for the action of other proteins. Protein destruction can occur virtually in all compartments and organelles of the cell, associated with cell membranes or large protein complexes, it determines subcellular partitioning, association with positive or negative regulators which conditions the action of many critical cellular factors. The third intracellular proteolysis meeting held by the University La Laguna, Canary Islands, Spain, included speakers working with some of the most important proteolytic systems present in higher eukaryotes, such as the UPS (ubiquitin-proteasome system) and autophagy. Owing to the fact that these pathways directly or indirectly regulate many cell functions, this meeting brought together an audience with a wide range of research interests, including genetic, cell biological, biochemical and structural aspects of protein degradation. Some of these topics inspired interesting discussions and a significant number of these are developed in the issues reviewed herein.

  16. Proteolysis of proBDNF is a key regulator in the formation of memory.

    Directory of Open Access Journals (Sweden)

    Philip Barnes

    Full Text Available It is essential to understand the molecular processes underlying long-term memory to provide therapeutic targets of aberrant memory that produce pathological behaviour in humans. Under conditions of recall, fully-consolidated memories can undergo reconsolidation or extinction. These retrieval-mediated memory processes may rely on distinct molecular processes. The cellular mechanisms initiating the signature molecular events are not known. Using infusions of protein synthesis inhibitors, antisense oligonucleotide targeting brain-derived neurotrophic factor (BDNF mRNA or tPA-STOP (an inhibitor of the proteolysis of BDNF protein into the hippocampus of the awake rat, we show that acquisition and extinction of contextual fear memory depended on the increased and decreased proteolysis of proBDNF (precursor BDNF in the hippocampus, respectively. Conditions of retrieval that are known to initiate the reconsolidation of contextual fear memory, a BDNF-independent memory process, were not correlated with altered proBDNF cleavage. Thus, the processing of BDNF was associated with the acquisition of new information and the updating of information about a salient stimulus. Furthermore, the differential requirement for the processing of proBDNF by tPA in distinct memory processes suggest that the molecular events actively engaged to support the storage and/or the successful retrieval of memory depends on the integration of ongoing experience with past learning.

  17. Mcm10 proteolysis initiates before the onset of M-phase

    Directory of Open Access Journals (Sweden)

    Khan Muntaz

    2010-10-01

    Full Text Available Abstract Background Mcm10 protein is essential for initiation and elongation phases of replication. Human cells proteolyze Mcm10 during mitosis, presumably to ensure a single round of replication. It has been proposed that anaphase promoting complex ubiquitinates Mcm10 in late M and early G1 phases. Results In contrast to the previous work, we report that the degradation of Mcm10 is initiated at the onset of mitosis. Immunoblotting and immunofluorescence assays display that Mcm10 levels are low in all phases of mitosis. We report that Mcm10 degradation is not dependent on anaphase promoting complex. Further, the proteolysis in M-phase can be independently mediated by non-overlapping regions of Mcm10, apparently employing a redundant mechanism to ensure downregulation. Conclusions It is believed that the proteolysis of Mcm10 during mitosis is a vital mechanism to prevent aberrant initiation of replication and the present study describes the regulation of Mcm10 during this phase of the cell-cycle.

  18. Proteolysis at the plasma membrane of tobacco roots: biochemical evidence and possible roles.

    Science.gov (United States)

    Eick, Manuela; Stöhr, Christine

    2009-01-01

    Plasma membrane-associated proteases (pm-proteases) exist principally in roots of Nicotiana tabacum cv. Samsun, whereas in plasma membrane (pm) vesicles prepared from leaves, protease activity was at the detection limit. Biochemical characterisation revealed a high diversity of particular hydrophobic pm-proteases indicating multiple functions in root tissue. One proportion of chromatographically separated proteases was split up by non-reducing SDS-PAGE in 8-12 single polypeptides, dependent on plant nitrogen nutrition. The active polypeptides could be grouped in those that were (i) inhibited, (ii) stimulated and (iii) independent of bivalent cations. Although, the total specific protease activity of various pm vesicles was almost identical, the composition and activity of individual polypeptides was dependent on nitrogen supply of the plants. Particularly, nitrogen deficiency stimulated the activity of high molecular mass proteases (125 kDa-97 kDa), whereas sufficient nitrate supply enhanced proteolytic activity of 90 kDa, 83 kDa and 65 kDa polypeptides. Endogenous proteolysis within pm vesicles suggested that at least partly protease substrates are localised within the same membrane. A comparison of polypeptides originated from proteolysis of pm vesicles and those exudated by roots into the external medium points to a role of root pm-proteases in the specific release of polypeptides into the rhizosphere.

  19. The role of extracellular proteolysis in synaptic plasticity of the central nervous system 

    Directory of Open Access Journals (Sweden)

    Anna Konopka

    2012-11-01

    Full Text Available The extracellular matrix (ECM of the central nervous system has a specific structure and protein composition that are different from those in other organs. Today we know that the ECM not only provides physical scaffolding for the neurons and glia, but also actively modifies their functions. Over the last two decades, a growing body of research evidence has been collected, suggesting an important role of ECM proteolysis in synaptic plasticity of the brain. So far the majority of data concern two large families of proteases: the serine proteases and the matrix metalloproteinases. The members of these families are localized at the synapses, and are secreted into the extracellular space in an activity-dependent manner. The proteases remodel the local environment as well as influencing synapse structure and function. The structural modifications induced by proteases include shape and size changes, as well as synapse elimination, and synaptogenesis. The functional changes include modifications of receptor function in the postsynaptic part of the synapse, as well as the potentiation or depression of neurotransmitter secretion by the presynaptic site. The present review summarizes the current view on the role of extracellular proteolysis in the physiological synaptic plasticity underlying the phenomena of learning and memory, as well as in the pathological plasticity occurring during epileptogenesis or development of drug addiction. 

  20. Buffering and proteolysis are induced by segmental monosomy in Drosophila melanogaster

    Science.gov (United States)

    Lundberg, Lina E.; Figueiredo, Margarida L. A.; Stenberg, Per; Larsson, Jan

    2012-01-01

    Variation in the number of individual chromosomes (chromosomal aneuploidy) or chromosome segments (segmental aneuploidy) is associated with developmental abnormalities and reduced fitness in all species examined; it is the leading cause of miscarriages and mental retardation and a hallmark of cancer. However, despite their documented importance in disease, the effects of aneuploidies on the transcriptome remain largely unknown. We have examined the expression effects of seven heterozygous chromosomal deficiencies, both singly and in all pairwise combinations, in Drosophila melanogaster. The results show that genes in one copy are buffered, i.e. expressed more strongly than the expected 50% of wild-type level, the buffering is general and not influenced by other monosomic regions. Furthermore, long genes are significantly more highly buffered than short genes and gene length appears to be the primary determinant of the buffering degree. For short genes the degree of buffering depends on expression level and expression pattern. Furthermore, the results show that in deficiency heterozygotes the expression of genes involved in proteolysis is enhanced and negatively correlates with the degree of buffering. Thus, enhanced proteolysis appears to be a general response to aneuploidy. PMID:22434883

  1. Mapping the consequence of Notch1 proteolysis in vivo with NIP-CRE.

    Science.gov (United States)

    Vooijs, Marc; Ong, Chin-Tong; Hadland, Brandon; Huppert, Stacey; Liu, Zhenyi; Korving, Jeroen; van den Born, Maaike; Stappenbeck, Thaddeus; Wu, Yumei; Clevers, Hans; Kopan, Raphael

    2007-02-01

    The four highly conserved Notch receptors receive short-range signals that control many biological processes during development and in adult vertebrate tissues. The involvement of Notch1 signaling in tissue self-renewal is less clear, however. We developed a novel genetic approach N(1)IP-CRE (Notch1 Intramembrane Proteolysis) to follow, at high resolution, the descendents of cells experiencing Notch1 activation in the mouse. By combining N(1)IP-CRE with loss-of-function analysis, Notch activation patterns were correlated with function during development, self-renewal and malignancy in selected tissues. Identification of many known functions of Notch1 throughout development validated the utility of this approach. Importantly, novel roles for Notch1 signaling were identified in heart, vasculature, retina and in the stem cell compartments of self-renewing epithelia. We find that the probability of Notch1 activation in different tissues does not always indicate a requirement for this receptor and that gradients of Notch1 activation are evident within one organ. These findings highlight an underappreciated layer of complexity of Notch signaling in vivo. Moreover, NIP-CRE represents a general strategy applicable for monitoring proteolysis-dependent signaling in vivo.

  2. Natural mitochondrial proteolysis confirms transcription systematically exchanging/deleting nucleotides, peptides coded by expanded codons.

    Science.gov (United States)

    Seligmann, Hervé

    2017-02-07

    Protein sequences have higher linguistic complexities than human languages. This indicates undeciphered multilayered, overprinted information/genetic codes. Some superimposed genetic information is revealed by detections of transcripts systematically (a) exchanging nucleotides (nine symmetric, e.g. AC, fourteen asymmetric, e.g. A->C->G->A, swinger RNAs) translated according to tri-, tetra- and pentacodons, and (b) deleting mono-, dinucleotides after each trinucleotide (delRNAs). Here analyses of two independent proteomic datasets considering natural proteolysis confirm independently translation of these non-canonical RNAs, also along tetra- and pentacodons, increasing coverage of putative, cryptically encoded proteins. Analyses assuming endoproteinase GluC and elastase digestions (cleavages after residues D, E, and A, L, I, V, respectively) detect additional peptides colocalizing with detected non-canonical RNAs. Analyses detect fewer peptides matching GluC-, elastase- than trypsin-digestions: artificial trypsin-digestion outweighs natural proteolysis. Results suggest occurrences of complete proteins entirely matching non-canonical, superimposed encoding(s). Protein-coding after bijective transformations could explain genetic code symmetries, such as along Rumer's transformation.

  3. Hepatic steatosis inhibits autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression

    Energy Technology Data Exchange (ETDEWEB)

    Inami, Yoshihiro [Department of Gastroenterology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Yamashina, Shunhei, E-mail: syamashi@juntendo.ac.jp [Department of Gastroenterology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Izumi, Kousuke [Department of Gastroenterology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Ueno, Takashi [Department of Biochemistry, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan); Tanida, Isei [Department of Biochemistry and Cell Biology, Laboratory of Biomembranes, National Institute of Infectious Disease, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640 (Japan); Ikejima, Kenichi; Watanabe, Sumio [Department of Gastroenterology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421 (Japan)

    2011-09-09

    Highlights: {yields} Acidification of autophagosome was blunted in steatotic hepatocytes. {yields} Hepatic steatosis did not disturb fusion of isolated autophagosome and lysosome. {yields} Proteinase activity of cathepsin B and L in autolysosomes was inhibited by steatosis. {yields} Hepatic expression of cathepsin B and L was suppressed by steatosis. -- Abstract: Autophagy, one of protein degradation system, contributes to maintain cellular homeostasis and cell defense. Recently, some evidences indicated that autophagy and lipid metabolism are interrelated. Here, we demonstrate that hepatic steatosis impairs autophagic proteolysis. Though accumulation of autophagosome is observed in hepatocytes from ob/ob mice, expression of p62 was augmented in liver from ob/ob mice more than control mice. Moreover, degradation of the long-lived protein leucine was significantly suppressed in hepatocytes isolated from ob/ob mice. More than 80% of autophagosomes were stained by LysoTracker Red (LTR) in hepatocytes from control mice; however, rate of LTR-stained autophagosomes in hepatocytes were suppressed in ob/ob mice. On the other hand, clearance of autolysosomes loaded with LTR was blunted in hepatocytes from ob/ob mice. Although fusion of isolated autophagosome and lysosome was not disturbed, proteinase activity of cathepsin B and L in autolysosomes and cathepsin B and L expression of liver were suppressed in ob/ob mice. These results indicate that lipid accumulation blunts autophagic proteolysis via impairment of autophagosomal acidification and cathepsin expression.

  4. Overexpression of the essential Sis1 chaperone reduces TDP-43 effects on toxicity and proteolysis.

    Science.gov (United States)

    Park, Sei-Kyoung; Hong, Joo Y; Arslan, Fatih; Kanneganti, Vydehi; Patel, Basant; Tietsort, Alex; Tank, Elizabeth M H; Li, Xingli; Barmada, Sami J; Liebman, Susan W

    2017-05-01

    Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by selective loss of motor neurons with inclusions frequently containing the RNA/DNA binding protein TDP-43. Using a yeast model of ALS exhibiting TDP-43 dependent toxicity, we now show that TDP-43 overexpression dramatically alters cell shape and reduces ubiquitin dependent proteolysis of a reporter construct. Furthermore, we show that an excess of the Hsp40 chaperone, Sis1, reduced TDP-43's effect on toxicity, cell shape and proteolysis. The strength of these effects was influenced by the presence of the endogenous yeast prion, [PIN+]. Although overexpression of Sis1 altered the TDP-43 aggregation pattern, we did not detect physical association of Sis1 with TDP-43, suggesting the possibility of indirect effects on TDP-43 aggregation. Furthermore, overexpression of the mammalian Sis1 homologue, DNAJB1, relieves TDP-43 mediated toxicity in primary rodent cortical neurons, suggesting that Sis1 and its homologues may have neuroprotective effects in ALS.

  5. Inhibition of proliferation, migration and proteolysis contribute to corticosterone-mediated inhibition of angiogenesis.

    Directory of Open Access Journals (Sweden)

    Eric A Shikatani

    Full Text Available The angiostatic nature of pharmacological doses of glucocorticoid steroids is well known. However, the consequences of pathophysiological elevation of endogenous glucocorticoids are not well established. In the current study, we hypothesized that the angiostatic effect of corticosterone, an endogenous glucocorticoid in rodents, occurs through multi-faceted alterations in skeletal muscle microvascular endothelial cell proliferation, migration, and proteolysis. Chronic corticosterone treatment significantly reduced the capillary to fiber ratio in the tibialis anterior muscle compared to that of placebo-treated rats. Corticosterone inhibited endothelial cell sprouting from capillary segments ex vivo. Similarly, 3-dimensional endothelial cell spheroids treated with corticosterone for 48 hours showed evidence of sprout regression and reduced sprout length. Endothelial cell proliferation was reduced in corticosterone treated cells, coinciding with elevated FoxO1 and reduced VEGF production. Corticosterone treated endothelial cells exhibited reduced migration, which correlated with a reduction in RhoA activity. Furthermore, corticosterone treated endothelial cells in both 3-dimensional and monolayer cultures had decreased MMP-2 production and activation resulting in decreased proteolysis by endothelial cells, limiting their angiogenic potential. Promoter assays revealed that corticosterone treatment transcriptionally repressed MMP-2, which may map to a predicted GRE between -1510 and -1386 bp of the MMP-2 promoter. Additionally, Sp1, a known transcriptional activator of MMP-2 was decreased following corticosterone treatment. This study provides new insights into the mechanisms by which pathophysiological levels of endogenous glucocorticoids may exert angiostatic effects.

  6. Extracellular proteolysis of apolipoprotein E (apoE by secreted serine neuronal protease.

    Directory of Open Access Journals (Sweden)

    Irfan Y Tamboli

    Full Text Available Under normal conditions, brain apolipoprotein E (apoE is secreted and lipidated by astrocytes, then taken up by neurons via receptor mediated endocytosis. Free apoE is either degraded in intraneuronal lysosomal compartments or released. Here we identified a novel way by which apoE undergoes proteolysis in the extracellular space via a secreted neuronal protease. We show that apoE is cleaved in neuronal conditioned media by a secreted serine protease. This apoE cleavage was inhibited by PMSF and α1-antichymotrypsin, but not neuroserpin-1 or inhibitors of thrombin and cathepsin G, supporting its identity as a chymotrypsin like protease. In addition, apoE incubation with purified chymotrypsin produced a similar pattern of apoE fragments. Analysis of apoE fragments by mass spectrometry showed cleavages occurring at the C-terminal side of apoE tryptophan residues, further supporting our identification of cleavage by chymotrypsin like protease. Hippocampal neurons were more efficient in mediating this apoE cleavage than cortical neurons. Proteolysis of apoE4 generated higher levels of low molecular weight fragments compared to apoE3. Primary glial cultures released an inhibitor of this proteolytic activity. Together, these studies reveal novel mechanism by which apoE can be regulated and therefore could be useful in designing apoE directed AD therapeutic approaches.

  7. A comparative study on continuous and pulsed RF argon capacitive glow discharges at low pressure by fluid modeling

    Science.gov (United States)

    Liu, Ruiqiang; Liu, Yue; Jia, Wenzhu; Zhou, Yanwen

    2017-01-01

    Based on the plasma fluid theory and using the drift-diffusion approximation, a mathematical model for continuous and pulsed radial frequency (RF) argon capacitive glow discharges at low pressure is established. The model is solved by a finite difference method and the numerical results are reported. Based on the systematic analysis of the results, plasma characteristics of the continuous and pulsed RF discharges are comparatively investigated. It is shown that, under the same condition for the peak value of the driving potential, the cycle-averaged electron density, the current density, and other essential physical quantities in the continuous RF discharge are higher than those from the pulsed RF discharge. On the other hand, similar plasma characteristics are obtained with two types of discharges, by assuming the same deposited power. Consequently, higher driving potential is needed in pulsed discharges in order to maintain the same effective plasma current. Furthermore, it is shown that, in the bulk plasma region, the peak value of the bipolar electric field from the continuous RF discharge is greater than that from the pulsed RF discharge. In the sheath region, the ionization rate has the shape of double-peaking and the explanation is given. Because the plasma input power depends on the driving potential and the plasma current phase, the phase differences between the driving potential and the plasma current are compared between the continuous and the pulsed RF discharges. It is found that this phase difference is smaller in the pulsed RF discharge compared to that of the continuous RF discharge. This means that the input energy coupling in the pulsed RF discharge is less efficient than the continuous counterpart. This comparative study, carried out also under other conditions, thus can provide instructive ideas in applications using the continuous and pulsed RF capacitive glow discharges.

  8. Life cycle cost of a hybrid forward osmosis – low pressure reverse osmosis system for seawater desalination and wastewater recovery

    KAUST Repository

    Valladares Linares, Rodrigo

    2015-10-19

    In recent years, forward osmosis (FO) hybrid membrane systems have been investigated as an alternative to conventional high-pressure membrane processes (i.e. reverse osmosis (RO)) for seawater desalination and wastewater treatment and recovery. Nevertheless, their economic advantage in comparison to conventional processes for seawater desalination and municipal wastewater treatment has not been clearly addressed. This work presents a detailed economic analysis on capital and operational expenses (CAPEX and OPEX) for: i) a hybrid forward osmosis – low-pressure reverse osmosis (FO-LPRO) process, ii) a conventional seawater reverse osmosis (SWRO) desalination process, and iii) a membrane bioreactor – reverse osmosis – advanced oxidation process (MBR-RO-AOP) for wastewater treatment and reuse. The most important variables affecting economic feasibility are obtained through a sensitivity analysis of a hybrid FO-LPRO system. The main parameters taken into account for the life cycle costs are the water quality characteristics (similar feed water and similar water produced), production capacity of 100,000 m3 d−1 of potable water, energy consumption, materials, maintenance, operation, RO and FO module costs, and chemicals. Compared to SWRO, the FO-LPRO systems have a 21% higher CAPEX and a 56% lower OPEX due to savings in energy consumption and fouling control. In terms of the total water cost per cubic meter of water produced, the hybrid FO-LPRO desalination system has a 16% cost reduction compared to the benchmark for desalination, mainly SWRO. Compared to the MBR-RO-AOP, the FO-LPRO systems have a 7% lower CAPEX and 9% higher OPEX, resulting in no significant cost reduction per m3 produced by FO-LPRO. Hybrid FO-LPRO membrane systems are shown to have an economic advantage compared to current available technology for desalination, and comparable costs with a wastewater treatment and recovery system. Based on development on FO membrane modules, packing density, and

  9. 在线低压等离子清洗研究%Research of Low Pressure Plasma Cleaning Inline

    Institute of Scientific and Technical Information of China (English)

    杨文伟; 杜海文; 王大伟; 续艳鑫

    2011-01-01

    Introduce an efficient and environmental plasma cleaning inline technique. Study the cleaning principle and inline mechanism under low-pressure plasma, and propose the match principle of dielectric gas, finally analyze the examination of surface free energy and the test method of contact angle for cleanliness conditions. The experiment used contact angle tester to test the work change of adhesion on solid surface before and after cleaning. It is found that the adhesion work was improved about 54.7% after cleaning of Ar plasma, and the efficiency was improved about 75% over the common plasma cleaning.%介绍了一种高效环保的在线等离子清洗方法,深入研究了低压下等离子的清洗原理和在线式的清洗机制,提出了介质气体的选配原则,分析了榆测表面自由能和洁净程度的接触角测试方法.通过实验,在氩等离子在线清洗中,用接触角测试仪测定固体表面清洗前后粘附功的变化,发现在氩等离子清洗后固体表面粘附功提高了54.7%,相对于普通的射频等离子清洗其效率提升了约75%.

  10. InP/InGaAlAs distributed Bragg reflectors grown by low-pressure metal organic chemical vapor deposition

    Science.gov (United States)

    Lu, T. C.; Tsai, J. Y.; Chu, J. T.; Chang, Y. S.; Wang, S. C.

    2003-04-01

    Long-wavelength vertical cavity surface emitting lasers (VCSELs) are considered the best candidate for the future low-cost reliable light sources in fiber communications. However, the absence of high refractive index contrast in InP-lattice-matched materials impeded the development of 1.3-1.5 μm VCSELs. Although wafer fusions provided the alternative approaches to integrate the InP-based gain materials with the GaAs/AlAs materials for their inherent high refractive index contrast, the monolithic InP-based lattice-matched distributed Bragg reflectors (DBRs) are still highly attractive and desirable. In this report, we demonstrate InP/InGaAlAs DBRs with larger refractive index contrast than InP/InGaAsP and InAlAs/InGaAlAs DBRs. The switching between InP and InGaAlAs layers and growth rate control have been done by careful growth interruption technique and accurate in situ optical monitoring in low-pressure metal organic chemical vapor deposition. A 35 pairs 1.55 μm centered InP/InGaAlAs DBRs has the stopband of more than 100 nm and the highest reflectivity of more than 99%. A VCSEL structure incorporating 35 pairs InP/InGaAlAs DBR as the bottom mirror combined with a 2 λ thick periodic gain cavity and 10 pairs SiO 2/TiO 2 top dielectric mirrors was fabricated. The VCSELs lased at 1.56 μm by optical pumping at room temperature with the threshold pumping power of 30 mW.

  11. Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures.

    Science.gov (United States)

    Gu, Shuai; He, Jianqiao; Zhu, Yunlong; Wang, Zhiqiang; Chen, Dongyang; Yu, Guipeng; Pan, Chunyue; Guan, Jianguo; Tao, Kai

    2016-07-20

    The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation.

  12. On the spectroscopic detection of neutral species in a low-pressure plasma containing boron and hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Lavrov, B P [Faculty of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Osiac, M [Institut fuer Niedertemperatur-Plasmaphysik, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19 (Germany); Pipa, A V [Faculty of Physics, St. Petersburg State University, St. Petersburg, 198504 (Russian Federation); Roepcke, J [Institut fuer Niedertemperatur-Plasmaphysik, 17489 Greifswald, Friedrich-Ludwig-Jahn-Str. 19 (Germany)

    2003-11-01

    Spectroscopic studies of microwave discharges in H{sub 2}-Ar-B{sub 2}H{sub 6} gas mixtures (f = 2.45 GHz, P = 1.2-3.5 kW, p = 1-8 mbar) have been performed to improve the possibilities of diagnostics of non-equilibrium, low-pressure plasmas containing boron and hydrogen. For this purpose, UV-VIS optical emission spectroscopy and infrared absorption spectroscopy with tunable diode lasers (TDLAS) have been applied. It is shown that information about neutral species and the gas temperature may be obtained by means of new and modified spectroscopic methods. A method for the determination of the absolute number density of boron atoms from measured relative intensities of the components of the boron resonance doublet (distorted by reabsorption) is proposed and tested for validity. The maximum of the density was found to be 3.8x10{sup 11} atoms cm{sup -3} at an admixture of diborane of about 2%. The gas temperature was determined from the intensity distributions in the rotational structure of the emission bands of BH and H{sub 2} and from Doppler broadening of the absorption line profiles of the BH molecule. It was observed that values of the gas temperature obtained from the rotational intensity distributions are in good agreement with those obtained from Doppler widths (T{sub g} = 700-1070 K). Based on measurements of the relative line intensities of atomic and molecular hydrogen and the gas temperature, and using a simple excitation-deactivation model, the density of molecular hydrogen was found to be about 40 times higher than the density of atomic hydrogen. It is shown that some absorption lines of boron hydrides (B{sub 2}H{sub 6}, BH{sub 3} and BH) detected by TDLAS may be used for plasma diagnostics.

  13. Aerosol size distributions measured in urban, rural and high-alpine air with an electrical low pressure impactor (ELPI)

    Science.gov (United States)

    Held, A.; Zerrath, A.; McKeon, U.; Fehrenbach, T.; Niessner, R.; Plass-Dülmer, C.; Kaminski, U.; Berresheim, H.; Pöschl, U.

    An electrical low pressure impactor (ELPI) was used to study atmospheric aerosol particle number, surface, and mass concentrations and size distributions over a diameter range of 7 nm-10 μm at urban, rural and high-alpine locations along an alpine altitude transect across Southern Germany. The measurements were performed in the city of Munich and at the global atmosphere watch (GAW) stations Hohenpeißenberg and Zugspitze in the years 2001-2004. To minimize particle bounce effects and enable chemical analysis of the collected particles without disturbance by grease on the impaction substrates, the sample flow was conditioned to about 75% relative humidity. The performance of the ELPI instrument was evaluated by comparison with well-established aerosol measurement techniques including condensation particle counters, scanning and differential mobility particle sizers, filter sampling, and gravimetric determination of particulate mass. In general, particle number concentrations, size distributions, and PM2.5 concentrations determined with the ELPI were in good agreement with alternative techniques (rank correlation coefficients ρ = 0.70-0.95). The ELPI filter stage data for the particle diameter range of 7-30 nm, however, appeared to be strongly biased towards high values. Long-term measurements at the rural site (Hohenpeißenberg) revealed distinct seasonal patterns with the highest number concentrations in summer (median daily average: 3100 cm -3) and the highest mass concentrations in spring and fall (median daily average PM2.5 and PM10: 21-25 and 27-35 μg m -3, respectively). In spring and fall we also observed pronounced maxima of particle surface and mass concentration in the coarse mode (peak at ˜3 μm), which are most likely due to primary biological material. Relatively clean air (PM10 urban air from Munich (NE) clearly contributed to elevated particle mass loadings (PM10 > = 10 μg m -3).

  14. Study on typical hole defects in AZ91D magnesium alloy prepared by low pressure lost foam casting

    Directory of Open Access Journals (Sweden)

    Li Jiqiang

    2013-07-01

    Full Text Available The hole defects can easily occur in magnesium alloy castings that are prepared by low pressure lost foam casting (LP-LFC process when the process parameters such as vacuum, pouring temperature and filling velocity are not properly selected. In this study, the forming mechanism of the hole defects in AZ91D magnesium castings by LP-LFC process was investigated. The shape, location and surface appearance of the hole defects were observed using optical microscopy and scanning electron microscopy, and the chemical composition on the surface of the holes was analyzed using energy spectrometer. The result indicates that there are two types of hole defects, i.e., the pyrolysis products related hole defects, including concentrative hole and blow hole defects, and slag related hole defects. The concentrative hole and the blow-hole defects were formed either by the liquid-EPS degradation products entrapped in the molten metal under the condition that the pouring temperature is equal to or lower than 730 ℃, or by the hindered transport of EPS pyrolysis products. Some irregular shape hole defects were caused by slag or by coating slough entrapment when the pouring temperature is equal to 750 ℃ and the filling velocity is equal to or greater than 100 mm·s-1. To reduce or eliminate the hole defects, the vacuum and filling velocity must be properly chosen to ensure that the metal front profile exhibits convex shape and in laminar current state, and the pouring temperature should be just high enough to ensure that the molten melt has adequate heat energy to complete the foam pyrolysis and to fully occupy the mould. For AZ91D magnesium castings in this study, the parameters should be 730 ℃ pouring temperature, 0.02-0.03 MPa vacuum and 80 mm·s-1 filling velocity.

  15. Control of the nucleation and quality of graphene grown by low-pressure chemical vapor deposition with acetylene

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Meng, E-mail: youmou@rift.mech.tohoku.ac.jp [Department of Nanomechanics, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Sasaki, Shinichirou [Department of Nanomechanics, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Suzuki, Ken; Miura, Hideo [Fracture and Reliability Research Institute, Tohoku University, Sendai 980-8579 (Japan)

    2016-03-15

    Graphical abstract: - Highlights: • For the first time, we succeeded in the LPCVD growth of monolayer graphene using acetylene as the precursor gas. • The growth rate is very high when acetylene is used as the source gas. Our process has exhibited the potential to shorten the growth time of CVD graphene. • We found that the domain size, defects density, layer number and the sheet resistance of graphene can be changed by changing the acetylene flow rates. • We found that it is also possible to form bilayer graphene using acetylene. However, further study are necessary to reduce the defects density. - Abstract: Although many studies have reported the chemical vapor deposition (CVD) growth of large-area monolayer graphene from methane, synthesis of graphene using acetylene as the source gas has not been fully explored. In this study, the low-pressure CVD (LPCVD) growth of graphene from acetylene was systematically investigated. We succeeded in regulating the domain size, defects density, layer number and the sheet resistance of graphene by changing the acetylene flow rates. Scanning electron microscopy and Raman spectroscopy were employed to confirm the layer number, uniformity and quality of the graphene films. It is found that a low flow rate of acetylene (0.28 sccm) is required to form high-quality monolayer graphene in our system. On the other hand, the high acetylene flow rate (7 sccm) will induce the growth of the bilayer graphene domains with high defects density. On the basis of selected area electron diffraction (SAED) pattern, the as-grown monolayer graphene domains were analyzed to be polycrystal. We also discussed the relation between the sheet resistacne and defects density in graphene. Our results provide great insights into the understanding of the CVD growth of monolayer and bilayer graphene from acetylene.

  16. 低压蒸汽节能回收改造总结%Sum-Up of Renovation of Energy Saving and Recovery of Low-Pressure Steam

    Institute of Scientific and Technical Information of China (English)

    马飞跃; 陈隆

    2015-01-01

    Due to design flaws,there is an unbalanced byproduct low-pressure steam from waste heat boiler,and the surplus low-pressure steam has to vent directly.In order to reduce energy consumption and save production cost,the surplus low-pressure steam is used to drive steam turbine, and steam turbine drives circulating water pump,and the excess energy is used to generate electricity. The implementation of technological renovation measures,not only has recovered and utilized surplus low-pressure steam,but also has significant economic benefit.%由于设计上的缺陷,导致废热锅炉副产的低压蒸汽不平衡,富余的低压蒸汽只能直接放空。为了降低能耗、节约生产成本,采用富余的低压蒸汽作为汽轮机的动能,由汽轮机拖动循环水泵,多余的能量用于发电。改造措施实施后,不仅回收利用了富余的低压蒸汽,而且具有明显的经济效益。

  17. Gasoline from coal in the state of Illinois: feasibility study. Volume I. Design. [KBW gasification process, ICI low-pressure methanol process and Mobil M-gasoline process

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    Volume 1 describes the proposed plant: KBW gasification process, ICI low-pressure methanol process and Mobil M-gasoline process, and also with ancillary processes, such as oxygen plant, shift process, RECTISOL purification process, sulfur recovery equipment and pollution control equipment. Numerous engineering diagrams are included. (LTN)

  18. Gasoline from coal in the state of Illinois: feasibility study. Volume I. Design. [KBW gasification process, ICI low-pressure methanol process and Mobil M-gasoline process

    Energy Technology Data Exchange (ETDEWEB)

    1980-01-01

    Volume 1 describes the proposed plant: KBW gasification process, ICI low-pressure methanol process and Mobil M-gasoline process, and also with ancillary processes, such as oxygen plant, shift process, RECTISOL purification process, sulfur recovery equipment and pollution control equipment. Numerous engineering diagrams are included. (LTN)

  19. Effects of low pressure radio frequency discharge on the physical and mechanical characteristics and chemical composition of diffusion coating on a surface of complex configuration details

    Science.gov (United States)

    Ladianov, V. I.; Gilmutdinov, F. Z.; Nikonova, R. M.; Kashapov, N. F.; Shaekhov, M. F.; Khristoliubova, V. I.

    2017-01-01

    The work deals with the influence of low-pressure radio frequency (RF) discharge on the surface properties of metals and their alloys. As objects of research to study the interaction of the jet low pressure RF discharge into the surface of the material the following materials were chosen: tungsten cobalt alloy, high speed steel, structural steel. In the presence of the materials energy parameters of low pressure RF discharge flows in the discharge chamber and the electrode gap were studied. A quantitative assessment of the gas composition inside the chamber to determine the characteristics of the plasma flow, making the major contribution to the modification of the surface was carried out. The influence of the input parameters of the plasma unit on the discharge characteristics was held. Identification of the main processes responsible for the modification of the surface of metals and alloys with the metal sample in the plasma jet and the effect of samples of products complex configuration on its properties is determined. The results of studies of physical and mechanical characteristics and chemical composition of the surface layers of high-speed steels, alloys and steel before and after treatment by low pressure radio frequency discharges with the instrumental indentation methods and X-ray photo-electron spectroscopy. With the help of the quality control system of the inner surfaces tubular products were studied.

  20. Complications corner: Anterior thoracic disc surgery with dural tear/CSF fistula and low-pressure pleural drain led to severe intracranial hypotension

    Directory of Open Access Journals (Sweden)

    Eline A Oudeman

    2015-01-01

    Conclusion: Severe neurological deterioration occurring after thoracic decompressive surgery may rarely be attributed to intracranial hypotension due to a subarachnoid-pleural fistula. Patients should be treated with external lumbar drainage of cerebrospinal fluid for 3-5 days rather than a low-pressure pleural drain to avoid the onset of intracranial hypotension leading to symptomatic subdural hematomas.

  1. Dewetting-induced globule-coil transitions of model polymers and possible implications high-temperature and low-pressure unfolding of proteins.

    Science.gov (United States)

    Sumi, Tomonari; Imazaki, Nobuyuki; Sekino, Hideo

    2010-04-28

    A thermodynamic analysis of high-temperature and low-pressure unfolding of proteins using a coarse-grained multiscale simulation combined with a liquid-state density-functional theory is presented. In this study, a hydrophobic polymer chain is employed as a probe molecule for investigating qualitative changes in a hydration free energy surface acting on proteins with changes in temperature and pressure. When water is heated so that its vapor pressure is equal to the atmospheric pressure, it boils. Long-ranged dewetting or drying caused by a hydrophobic planar wall and a large hydrophobic solute surface is significantly enhanced as it approaches the liquid-vapor coexistence curve of water. In this study, we demonstrate that high-temperature and low-pressure unfolding of the polymer chain is interpreted as dewetting-induced unfolding that occurs as it approaches the liquid-vapor coexistence. The unfolding of proteins due to high-temperature and low-pressure denaturation enhances the long-ranged dewetting or drying around them. The long-ranged dewetting phenomenon is considered to be originating from positive changes in both volume and entropy due to the high-temperature and low-pressure denaturation of the proteins.

  2. The effects of burner stabilization on Fenimore NO formation in low-pressure, fuel-rich premixed CH4/O2/N2 flames

    NARCIS (Netherlands)

    van Essen, Vincent; Sepman, Alexey; Mokhov, A. V.; Levinsky, H. B.

    We investigate the effects of varying the degree of burner stabilization on Fenimore NO formation in fuel-rich low-pressure flat CH4/O-2/N-2 flames. Towards this end, axial profiles of flame temperature and OH, NO and CH mole fractions are measured using laser-induced fluorescence (LIF). The

  3. The challenge of measuring sulfuric acid aerosols: number concentration and size evaluation using a condensation particle counter (CPC) and an electrical low pressure impactor (ELPI+)

    NARCIS (Netherlands)

    Brachert, L.; Mertens, J.; Khakharia, P.M.; Schaber, K.

    2014-01-01

    In this study, two different methods for the measurement of the sulfuric acid aerosol which is formed in wet flue gas cleaning processes have been investigated. The condensation particle counter (UFCPC, PALAS GmbH) provides information about the number concentration. With the electrical low pressure

  4. Effect of the Content of Retained Austenite and Grain Size on the Fatigue Bending Strength of Steels Carburized in a Low-Pressure Atmosphere

    Science.gov (United States)

    Kula, P.; Dybowski, K.; Lipa, S.; Januszewicz, B.; Pietrasik, R.; Atraszkiewicz, R.; Wołowiec, E.

    2014-11-01

    The effect of the content of retained austenite and of the initial austenite grain size on high-cycle fatigue of two low-alloy steels 16MnCr5 and 17CrNi6-6 after carburizing in a low-pressure atmosphere (acetylene, ethylene and hydrogen) and subsequent high-pressure gas quenching is investigated.

  5. Analysis and control of proteolysis of a fusion protein in Pichia pastoris fed-batch processes.

    Science.gov (United States)

    Jahic, Mehmedalija; Gustavsson, Malin; Jansen, Ann-Katrin; Martinelle, Mats; Enfors, Sven-Olof

    2003-04-10

    A fusion protein composed of a cellulose-binding module (CBM) from Neocallimastix patriciarum cellulase 6A and lipase B from Candida antarctica (CALB), was produced by Pichia pastoris Mut(+) in high-cell density bioreactor cultures. The production was induced by switching from growth on glycerol to growth on methanol. The lipase activity in the culture supernatant increased at an almost constant rate up to a value corresponding to 1.3 g x l(-1) of CBM-CALB. However, only about 40% of the product was of full-length according to Western blot analysis. This loss was due to a cleavage of the protein in the linker between the CBM and the CALB moieties. The cleavage was catalyzed by serine proteases in the culture supernatant. The CALB-moiety was subjected to further slow degradation by cell-associated proteolysis. Different strategies were used to reduce the proteolysis. Previous efforts to shorten the linker region resulted in a stable protein but with ten times reduced product concentration in bioreactor cultures (Gustavsson et al. 2001, Protein Eng. 14, 711-715). Addition of rich medium for protease substrate competition had no effect on the proteolysis of CBM-CALB. The kinetics for the proteolytic reactions, with and without presence of cells were shown to be influenced by pH. The fastest reaction, cleavage in the linker, was substantially reduced at pH values below 5.0. Decreasing the pH from 5.0 to 4.0 in bioreactor cultures resulted in an increase of the fraction of full-length product from 40 to 90%. Further improvement was achieved by decreasing the temperature from 30 to 22 degrees C during the methanol feed phase. By combining the optimal pH and the low temperature almost all product (1.5 g x l(-1)) was obtained as full-length protein with a considerably higher purity in the culture supernatant compared with the original cultivation.

  6. Life cycle cost of a hybrid forward osmosis - low pressure reverse osmosis system for seawater desalination and wastewater recovery.

    Science.gov (United States)

    Valladares Linares, R; Li, Z; Yangali-Quintanilla, V; Ghaffour, N; Amy, G; Leiknes, T; Vrouwenvelder, J S

    2016-01-01

    In recent years, forward osmosis (FO) hybrid membrane systems have been investigated as an alternative to conventional high-pressure membrane processes (i.e. reverse osmosis (RO)) for seawater desalination and wastewater treatment and recovery. Nevertheless, their economic advantage in comparison to conventional processes for seawater desalination and municipal wastewater treatment has not been clearly addressed. This work presents a detailed economic analysis on capital and operational expenses (CAPEX and OPEX) for: i) a hybrid forward osmosis - low-pressure reverse osmosis (FO-LPRO) process, ii) a conventional seawater reverse osmosis (SWRO) desalination process, and iii) a membrane bioreactor - reverse osmosis - advanced oxidation process (MBR-RO-AOP) for wastewater treatment and reuse. The most important variables affecting economic feasibility are obtained through a sensitivity analysis of a hybrid FO-LPRO system. The main parameters taken into account for the life cycle costs are the water quality characteristics (similar feed water and similar water produced), production capacity of 100,000 m(3) d(-1) of potable water, energy consumption, materials, maintenance, operation, RO and FO module costs, and chemicals. Compared to SWRO, the FO-LPRO systems have a 21% higher CAPEX and a 56% lower OPEX due to savings in energy consumption and fouling control. In terms of the total water cost per cubic meter of water produced, the hybrid FO-LPRO desalination system has a 16% cost reduction compared to the benchmark for desalination, mainly SWRO. Compared to the MBR-RO-AOP, the FO-LPRO systems have a 7% lower CAPEX and 9% higher OPEX, resulting in no significant cost reduction per m(3) produced by FO-LPRO. Hybrid FO-LPRO membrane systems are shown to have an economic advantage compared to current available technology for desalination, and comparable costs with a wastewater treatment and recovery system. Based on development on FO membrane modules, packing density, and

  7. Development of a feed-and-bleed operation strategy with hybrid-SIT under low pressure condition of PWR

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, In Seop, E-mail: jeoni@rpi.edu [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States); Han, Sang Hoon, E-mail: shhan2@kaeri.re.kr [Advanced Research Group, Korea Atomic Energy Research Institute, 70 Daedeok-daero 989 Beon-gil, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Kang, Sang Hee, E-mail: sanghee.kang@khnp.co.kr [NSSS Design Group, Korea Hydro & Nuclear Power Co., Ltd., Central Research Institute, 70, 1312-beongil, Yuseongdaero, Yuseong-gu, Daejeon (Korea, Republic of); Kang, Hyun Gook, E-mail: hyungook@kaist.ac.kr [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY (United States)

    2017-04-01

    Highlights: • The novel F&B operation strategy with H-SIT and LPSI is developed. • The effectiveness of the H-SITs is verified using thermo-hydraulic simulations. • Success criteria considered for the new F&B operation strategy is identified. • A PSA model of APR+ reflecting the new F&B strategy with H-SIT is developed. • A risk analysis of the proposed F&B operation strategy is performed. - Abstract: While safety functions in current nuclear power plants are mainly provided by active safety systems, recently passive safety systems are being combined with the active systems to strengthen accident mitigation capability and therefore enhance overall plant safety. To this end, securing long-term cooling of the core is of particular importance. This study considers the hybrid safety injection tank (H-SIT), a passive injection system, as a target component to develop a long-term cooling strategy using active and passive systems concurrently. In the feed-and-bleed (F&B) operation, one of the important long-term cooling strategies to maintain core safety in pressurized water reactors, low pressure safety injection (LPSI) pumps are typically considered inoperable as depressurization is first required, which leads to core dry-out before reaching LPSI operable pressure. This study investigates whether H-SITs, with the important design feature of passive coolant injection under any pressure condition of the primary coolant system, can make up the core during depressurization thereby allowing LPSI pumps to be used in F&B operation as an additional means of long-term cooling. The effectiveness of the H-SITs is verified using thermal-hydraulic simulations, and based on the results a novel F&B operation strategy with H-SITs and LPSI pumps is developed. A probabilistic safety assessment (PSA) model is then developed in order to assess the risk effect of the suggested strategy. PSA results demonstrate that the proposed strategy lowers core damage frequency in the target

  8. Chemical and proteolysis-derived changes during long-term storage of lactose-hydrolyzed ultrahigh-temperature (UHT) milk.

    Science.gov (United States)

    Jansson, Therese; Jensen, Hanne B; Sundekilde, Ulrik K; Clausen, Morten R; Eggers, Nina; Larsen, Lotte B; Ray, Colin; Andersen, Henrik J; Bertram, Hanne C

    2014-11-19

    Proteolytic activity in milk may release bitter-tasting peptides and generate free amino terminals that react with carbohydrates, which initiate Maillard reaction. Ultrahigh temperature (UHT) heat treatment inactivates the majority of proteolytic enzymes in milk. In lactose-hydrolyzed milk a β-galactosidase preparation is applied to the milk after heat treatment, which has proteolytic side activities that may induce quality deterioration of long-term-stored milk. In the present study proteolysis, glycation, and volatile compound formation were investigated in conventional (100% lactose), filtered (60% lactose), and lactose-hydrolyzed (lactose) UHT milk using reverse phase high-pressure liquid chromatography-mass spectrometry, proton nuclear magnetic resonance, and gas chromatography-mass spectrometry. Proteolysis was observed in all milk types. However, the degree of proteolysis was significantly higher in the lactose-hydrolyzed milk compared to the conventional and filtered milk. The proteins most prone to proteolysis were β-CN and αs1-CN, which were clearly hydrolyzed after approximately 90 days of storage in the lactose-hydrolyzed milk.

  9. The Putative O-Linked N-Acetylglucosamine Transferase SPINDLY Inhibits Class I TCP Proteolysis to Promote Sensitivity to Cytokinin.

    Science.gov (United States)

    Steiner, Evyatar; Livne, Sivan; Kobinson-Katz, Tammy; Tal, Lior; Pri-Tal, Oded; Mosquna, Assaf; Tarkowská, Danuše; Mueller, Bruno; Tarkowski, Petr; Weiss, David

    2016-06-01

    Arabidopsis (Arabidopsis thaliana) SPINDLY (SPY) is a putative serine and threonine O-linked N-acetylglucosamine transferase (OGT). While SPY has been shown to suppress gibberellin signaling and to promote cytokinin (CK) responses, its catalytic OGT activity was never demonstrated and its effect on protein fate is not known. We previously showed that SPY interacts physically and functionally with TCP14 and TCP15 to promote CK responses. Here, we aimed to identify how SPY regulates TCP14/15 activities and how these TCPs promote CK responses. We show that SPY activity is required for TCP14 stability. Mutation in the putative OGT domain of SPY (spy-3) stimulated TCP14 proteolysis by the 26S proteasome, which was reversed by mutation in CULLIN1 (CUL1), suggesting a role for SKP, CUL1, F-box E3 ubiquitin ligase in TCP14 proteolysis. TCP14 proteolysis in spy-3 suppressed all TCP14 misexpression phenotypes, including the enhanced CK responses. The increased CK activity in TCP14/15-overexpressing flowers resulted from increased sensitivity to the hormone and not from higher CK levels. TCP15 overexpression enhanced the response of the CK-induced synthetic promoter pTCS to CK, suggesting that TCP14/15 affect early steps in CK signaling. We propose that posttranslational modification of TCP14/15 by SPY inhibits their proteolysis and that the accumulated proteins promote the activity of the CK phosphorelay cascade in developing Arabidopsis leaves and flowers.

  10. Ligand binding to an Allergenic Lipid Transfer Protein Enhances Conformational Flexibility resulting in an Increase in Susceptibility to Gastroduodenal Proteolysis

    Science.gov (United States)

    Abdullah, Syed Umer; Alexeev, Yuri; Johnson, Philip E.; Rigby, Neil M.; Mackie, Alan R.; Dhaliwal, Balvinder; Mills, E. N. Clare

    2016-07-01

    Non-specific lipid transfer proteins (LTPs) are a family of lipid-binding molecules that are widely distributed across flowering plant species, many of which have been identified as allergens. They are highly resistant to simulated gastroduodenal proteolysis, a property that may play a role in determining their allergenicity and it has been suggested that lipid binding may further increase stability to proteolysis. It is demonstrated that LTPs from wheat and peach bind a range of lipids in a variety of conditions, including those found in the gastroduodenal tract. Both LTPs are initially cleaved during gastroduodenal proteolysis at three major sites between residues 39–40, 56–57 and 79–80, with wheat LTP being more resistant to cleavage than its peach ortholog. The susceptibility of wheat LTP to proteolyic cleavage increases significantly upon lipid binding. This enhanced digestibility is likely to be due to the displacement of Tyr79 and surrounding residues from the internal hydrophobic cavity upon ligand binding to the solvent exposed exterior of the LTP, facilitating proteolysis. Such knowledge contributes to our understanding as to how resistance to digestion can be used in allergenicity risk assessment of novel food proteins, including GMOs.

  11. Proteolysis, Fermentation Efficiency, and In Vitro Ruminal Digestion of Peanut Stover Ensiled with Raw or Heated Corn

    National Research Council Canada - National Science Library

    Yang, C.-M. J

    2005-01-01

    .... Legume forages often undergo extensive proteolysis during silage fermentation, with the production of various NPN components ( Ohshima and McDonald, 1978 ). Muck (1987) indicated that up to 70% of the N in alfalfa silage could be in the form of NPN. The conversion of protein N to NPN may have negative impacts on forage N use by ruminants. N...

  12. Granzyme B-dependent proteolysis acts as a switch to enhance the proinflammatory activity of IL-1α

    NARCIS (Netherlands)

    I.S. Afonina; G.A. Tynan; S.E. Logue; S.P. Cullen; M. Bots; A.U. Lüthi; E.P. Reeves; N.G. McElvaney; J.P. Medema; E.C. Lavelle; S.J. Martin

    2011-01-01

    Granzyme B is a cytotoxic lymphocyte-derived protease that plays a central role in promoting apoptosis of virus-infected target cells, through direct proteolysis and activation of constituents of the cell death machinery. However, previous studies have also implicated granzymes A and B in the produc

  13. The effect of proteolysis on the induction of cell death by monomeric alpha-lactalbumin.

    Science.gov (United States)

    Brück, Wolfram M; Gibson, Glenn R; Brück, Thomas B

    2014-02-01

    α-Lactalbumin (α-la) is a major whey protein found in milk. Previous data suggested that α-la has antiproliferative effects in human adenocarcinoma cell lines such as Caco-2 and HT-29. However, the cell death inducing α-la was not a naturally occurring monomer but either a multimeric variant or an α-la:oleic acid complex (HAMLET/BAMLET). Proteolysis showed that both human and bovine α-la are susceptible to digestion. ELISA assays assessing cell death with the native undigested α-la fractions showed that undigested protein fractions did have a significant cell death effect on CaCo-2 cells. Bovine α-la was also more effective than human α-la. A reduction in activity corresponded with lower concentrations of the protein and partial digestion and fragmentation of the protein using trypsin and pepsin. This suggests that the tertiary structure is vital for the apoptotic effect.

  14. Insulinlike growth factor-binding protein proteolysis an emerging paradigm in insulinlike growth factor physiology.

    Science.gov (United States)

    Fowlkes, J L

    1997-10-01

    In biologic fluids, insulinlike growth factors (IGF-I and IGF-II) are bound to high-affinity insulinlike growth factor binding proteins (IGFBPs) of which seven have now been identified (IGFBPs 1-7). In a variety of biologic fluids, several IGFBPs undergo proteolytic degradation. Such degradation can lead to increased IGF bioavailability at the cell surface, facilitating receptor interactions. Herein, recent data identifying several IGFBP-degrading proteinases and their effects on IGF bioactivity is reviewed, and how IGFBP proteolysis is regulated by IGFs and IGFBPs, as well as how IGFBP cleavage analysis provides insights into the structure and function of IGFBPs, is explored. (Trends Endocrinol Metab 1997;8:299-306). (c) 1997, Elsevier Science Inc.

  15. Mechanisms of accelerated proteolysis in rat soleus muscle atrophy induced by unweighting or denervation

    Science.gov (United States)

    Tischler, Marc E.; Kirby, Christopher; Rosenberg, Sara; Tome, Margaret; Chase, Peter

    1991-01-01

    A hypothesis proposed by Tischler and coworkers (Henriksen et al., 1986; Tischler et al., 1990) concerning the mechanisms of atrophy induced by unweighting or denervation was tested using rat soleus muscle from animals subjected to hindlimb suspension and denervation of muscles. The procedure included (1) measuring protein degradation in isolated muscles and testing the effects of lysosome inhibitors, (2) analyzing the lysosome permeability and autophagocytosis, (3) testing the effects of altering calcium-dependent proteolysis, and (4) evaluating in vivo the effects of various agents to determine the physiological significance of the hypothesis. The results obtained suggest that there are major differences between the mechanisms of atrophies caused by unweighting and denervation, though slower protein synthesis is an important feature common for both.

  16. Improvement of the antimicrobial and antioxidant activities of camel and bovine whey proteins by limited proteolysis.

    Science.gov (United States)

    Salami, Maryam; Moosavi-Movahedi, Ali Akbar; Ehsani, Mohammad Reza; Yousefi, Reza; Haertlé, Thomas; Chobert, Jean-Marc; Razavi, Seyed Hadi; Henrich, Robert; Balalaie, Saeed; Ebadi, Seyed Ahmad; Pourtakdoost, Samineh; Niasari-Naslaji, Amir

    2010-03-24

    The compositions and structures of bovine and camel milk proteins are different, which define their functional and biological properties. The aim of this study was to investigate the effects of enzymatic hydrolysis of camel and bovine whey proteins (WPs) on their antioxidant and antimicrobial properties. After enzymatic treatment, both the antioxidant and the antimicrobial activities of bovine and camel WPs were improved. The significantly higher antioxidant activity of camel WPs and their hydrolysates as compared with that of bovine WPs and their hydrolysates may result from the differences in amounts and/or in accessibilities of antioxidant amino acid residues present in their primary structures and from the prevalence of alpha-lactalbumin and beta-lactoglobulin as proteolytic substrates in camel and bovine whey, respectively. The results of this study reveal differences in antimicrobial and antioxidant activities between WP hydrolysates of bovine and camel milk and the effects of limited proteolysis on these activities.

  17. Proteolysis of synaptobrevin, syntaxin, and SNAP-25 in alveolar epithelial type II cells.

    Science.gov (United States)

    Zimmerman, U J; Malek, S K; Liu, L; Li, H L

    1999-10-01

    Synaptobrevin-2, syntaxin-1, and SNAP-25 were identified in rat alveolar epithelial type II cells by Western blot analysis. Synaptobrevin-2 was localized in the lamellar bodies, and syntaxin-1 and SNAP-25 were found in 0.4% Nonidet P40-soluble and -insoluble fractions, respectively, of the type II cells. When the isolated type II cells were stimulated for secretion with calcium ionophore A23187 or with phorbol 12-myristate 13-acetate, these proteins were found to have been proteolyzed. Preincubation of cells with calpain inhibitor II (N-acetylleucylleucylmethionine), however, prevented the proteolysis. Treatment of the cell lysate with exogenous calpain resulted in a time-dependent decrease of these proteins. The data suggest that synaptobrevin, syntaxin, and SNAP-25 are subject to proteolytic modification by activated calpain in intact type II cells stimulated for secretion.

  18. Effect of Flavourzyme on proteolysis, antioxidant capacity and sensory attributes of Chinese sausage.

    Science.gov (United States)

    Feng, Li; Qiao, Yan; Zou, Yufeng; Huang, Ming; Kang, Zhuangli; Zhou, Guanghong

    2014-09-01

    The objective of this study was to investigate the effect of Flavourzyme, at levels of 0 (control) 4, 8, 12, 16 and 20 LAPU/kg raw meat, on the proteolysis, antioxidant capacity and sensory attributes of Chinese sausage made at 50 °C for 48 h. Results showed that Flavourzyme addition in Chinese sausage accelerated protein degradation, which was reflected by the increase of non-protein nitrogen and appearance of new protein bands in both water-soluble and salt-soluble proteins. By adding Flavourzyme, texture profile analysis (TPA) parameters decreased significantly, and aroma, taste and texture scores were enhanced, respectively. The best sensory attributes were obtained at 8 and 12 LAPU/kg Flavourzyme dose. Besides, Flavourzyme addition enhanced antioxidant capacity, lowered water activity and TBARS values of Chinese sausage. Therefore, moderate Flavourzyme addition is a novel method with great potential to improve eating properties and storage stability of Chinese sausage.

  19. MBTPS2 mutations cause defective regulated intramembrane proteolysis in X-linked osteogenesis imperfecta

    Science.gov (United States)

    Lindert, Uschi; Cabral, Wayne A.; Ausavarat, Surasawadee; Tongkobpetch, Siraprapa; Ludin, Katja; Barnes, Aileen M.; Yeetong, Patra; Weis, Maryann; Krabichler, Birgit; Srichomthong, Chalurmpon; Makareeva, Elena N.; Janecke, Andreas R.; Leikin, Sergey; Röthlisberger, Benno; Rohrbach, Marianne; Kennerknecht, Ingo; Eyre, David R.; Suphapeetiporn, Kanya; Giunta, Cecilia; Marini, Joan C.; Shotelersuk, Vorasuk

    2016-01-01

    Osteogenesis imperfecta (OI) is a collagen-related bone dysplasia. We identified an X-linked recessive form of OI caused by defects in MBTPS2, which encodes site-2 metalloprotease (S2P). MBTPS2 missense mutations in two independent kindreds with moderate/severe OI cause substitutions at highly conserved S2P residues. Mutant S2P has normal stability, but impaired functioning in regulated intramembrane proteolysis (RIP) of OASIS, ATF6 and SREBP transcription factors, consistent with decreased proband secretion of type I collagen. Further, hydroxylation of the collagen lysine residue (K87) critical for crosslinking is reduced in proband bone tissue, consistent with decreased lysyl hydroxylase 1 in proband osteoblasts. Reduced collagen crosslinks presumptively undermine bone strength. Also, proband osteoblasts have broadly defective differentiation. These mutations provide evidence that RIP plays a fundamental role in normal bone development. PMID:27380894

  20. Effect and proposed mechanism of vitamin C modulating amino acid regulation of autophagic proteolysis.

    Science.gov (United States)

    Karim, Md Razaul; Kadowaki, Motoni

    2017-08-10

    Autophagy is an intracellular bulk degradation process, induced under nutrient starvation. Failure of autophagy has been recognized as a contributor to aging and multiple age related neurodegenerative diseases. Improving autophagy is a beneficial anti-aging strategy, however very few physiological regulators have been identified. Here, we demonstrate that vitamin C is a nutritional stimulator of autophagy. Supplementation of fresh hepatocytes with vitamin C increased autophagic proteolysis significantly in the presence of amino acids in a dose- and time-dependent manner, although no effect was observed in the absence of amino acids. In addition, inhibitor studies with 3-methyladenine, chloroquine, leupeptin and β-lactone confirmed that vitamin C is active through the lysosomal autophagy and not the proteasome pathway. Furthermore, the autophagy marker LC3 protein was significantly increased by vitamin C, suggesting its possible site of action is at the formation step. Both the reduced (ascorbic acid, AsA) and oxidized form (dehydroascorbic acid, DHA) of vitamin C exhibited equal enhancing effect, indicating that the effect does not depend on the anti-oxidation functionality of vitamin C. To understand the mechanism, we established that the effective dose (50 μM) was 15× lower than the intracellular content suggesting these would be only a minor influx from the extracellular pool. Moreover, transporter inhibitor studies in an AsA deficient ODS model rat revealed more accurately that the enhancing effect on autophagic proteolysis still existed, even though the intracellular influx of AsA was blocked. Taken together, these results provide evidence that vitamin C can potentially act through extracellular signaling. Copyright © 2017. Published by Elsevier B.V.