Assessment of the advantages and feasibility of a nuclear rocket for a manned Mars mission

International Nuclear Information System (INIS)

Howe, S.D.

1986-01-01

The feasibility of rebuilding and testing a nuclear thermal rocket (NTR) for the Mars mission was investigted. Calculations indicate that an NTR would substantially reduce the Earth-orbit assemble mass compared to LOX/LH 2 systems. The mass savings were 36 and 65% for the cases of total aerobraking and of total propulsive braking respectively. Consequently, the cost savings for a single mission of using an NTR, if aerobraking is feasible, are probably insufficient to warrant the NTR development. If multiple missions are planned or if propulsive braking is desired at Mars and/or at Earth, then the savings of about $7 billion will easily pay for the NTR. Estimates of the cost of rebuilding a NTR were based on the previous NERVA program's budget plus additional costs to develop a flight ready engine. The total cost to build the engine would be between $4 to 5 billion. The concept of developing a full-power test stand at Johnston Atoll in the Pacific appears very feasible. The added expense of building facilities on the island should be less than $1.4 billion

Co-induction of p75NTR and p75NTR-associated death executor in neurons after zinc exposure in cortical culture or transient ischemia in the rat.

Science.gov (United States)

Park, J A; Lee, J Y; Sato, T A; Koh, J Y

2000-12-15

Recently, a 22 kDa protein termed p75(NTR)-associated death executor (NADE) was discovered to be a necessary factor for p75(NTR)-mediated apoptosis in certain cells. However, the possible role for p75(NTR)/NADE in pathological neuronal death has yet been undetermined. In the present study, we have examined this possibility in vivo and in vitro. Exposure of cortical cultures to zinc induced both p75(NTR) and NADE in neurons, whereas exposure to NMDA, ionomycin, iron, or H(2)O(2) induced neither. In addition, zinc exposure increased neuronal NGF expression and its release into the medium. A function-blocking antibody of p75(NTR) (REX) inhibited association between p75(NTR) and NADE as well as neuronal death induced by zinc. Conversely, NGF augmented zinc-induced neuronal death. Caspase inhibitors reduced zinc-induced neuronal death, indicating that caspases were involved. Because reduction of NADE expression with cycloheximide or NADE antisense oligonucleotides attenuated zinc-induced neuronal death, NADE appears to contribute to p75(NTR)-induced cortical neuronal death as shown in other cells. Because zinc neurotoxicity may be a key mechanism of neuronal death after transient forebrain ischemia, we next examined this model. After ischemia, p75(NTR) and NADE were induced in degenerating rat hippocampal CA1 neurons. There was a close correlation between zinc accumulation and p75(NTR)/NADE induction. Suggesting the role of zinc here, injection of a metal chelator, CaEDTA, into the lateral ventricle completely blocked the induction of p75(NTR) and NADE. Our results suggest that co-induction of p75(NTR) and NADE plays a role in zinc-triggered neuronal death in vitro and in vivo.

Lunar Robotic Precursor Missions Using Electric Propulsion

OpenAIRE

Winski, Richard G.

2006-01-01

A trade study is carried out for the design of electric propulsion based lunar robotic precursor missions. The focus is to understand the relationships between payload mass delivered, electric propulsion power, and trip time. The results are compared against a baseline system using chemical propulsion with LOX/H2. The major differences between the chemical propulsion based and electric propulsion based systems are presented in terms of the payload mass and trip time. It is shown that solar e...

Assessment of the advantages and feasibility of a nuclear rocket

International Nuclear Information System (INIS)

Howe, S.D.

1985-01-01

The feasibility of rebuilding and testing a nuclear thermal rocket (NTR) for the Mars mission has been investigated. Calculations indicate that an NTR would substantially reduce the earth-orbit assembled mass compared to LOX/LH 2 systems. The mass savings were 36% and 65% for the cases of total aerobraking and of total propulsive braking respectively. Consequently, the cost savings for a single mission of using an NTR, if aerobraking is feasible, are probably insufficient to warrant the NTR development. If multiple missions are planned or if propulsive braking is desired at Mars and/or at Earth, then the savings of about $7B will easily pay for the NTR development. Estimates of the cost of rebuilding a NTR were based on the previous NERVA program's budget plus additional costs to develop a flight ready engine. The total cost to build the engine would be between $4 to 5B. The concept of developing a full-power test stand at Johnston Atoll in the Pacific appears very feasible. The added expense of building facilities on the island should be less than $1.4B

Evaluation of advanced propulsion options for the next manned transportation system: Propulsion evolution study

Science.gov (United States)

Spears, L. T.; Kramer, R. D.

1990-01-01

The objectives were to examine launch vehicle applications and propulsion requirements for potential future manned space transportation systems and to support planning toward the evolution of Space Shuttle Main Engine (SSME) and Space Transportation Main Engine (STME) engines beyond their current or initial launch vehicle applications. As a basis for examinations of potential future manned launch vehicle applications, we used three classes of manned space transportation concepts currently under study: Space Transportation System Evolution, Personal Launch System (PLS), and Advanced Manned Launch System (AMLS). Tasks included studies of launch vehicle applications and requirements for hydrogen-oxygen rocket engines; the development of suggestions for STME engine evolution beyond the mid-1990's; the development of suggestions for STME evolution beyond the Advanced Launch System (ALS) application; the study of booster propulsion options, including LOX-Hydrocarbon options; the analysis of the prospects and requirements for utilization of a single engine configuration over the full range of vehicle applications, including manned vehicles plus ALS and Shuttle C; and a brief review of on-going and planned LOX-Hydrogen propulsion technology activities.

Coil-On-Plug Ignition for LOX/Methane Liquid Rocket Engines in Thermal Vacuum Environments

Science.gov (United States)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX) / liquid methane rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/methane propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. In order to successfully demonstrate ignition reliability in the vacuum conditions and eliminate corona discharge issues, a coil-on-plug ignition system has been developed. The ICPTA uses spark-plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark-plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp.-2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, Plum Brook testing demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/methane propulsion systems in future spacecraft.

NTR-Enhanced Lunar-Base Supply using Existing Launch Fleet Capabilities

Energy Technology Data Exchange (ETDEWEB)

John D. Bess; Emily Colvin; Paul G. Cummings

2009-06-01

During the summer of 2006, students at the Center for Space Nuclear Research sought to augment the current NASA lunar exploration architecture with a nuclear thermal rocket (NTR). An additional study investigated the possible use of an NTR with existing launch vehicles to provide 21 metric tons of supplies to the lunar surface in support of a lunar outpost. Current cost estimates show that the complete mission cost for an NTR-enhanced assembly of Delta-IV and Atlas V vehicles may cost 47-86% more than the estimated Ares V launch cost of $1.5B; however, development costs for the current NASA architecture have not been assessed. The additional cost of coordinating the rendezvous of four to six launch vehicles with an in-orbit assembly facility also needs more thorough analysis and review. Future trends in launch vehicle use will also significantly impact the results from this comparison. The utility of multiple launch vehicles allows for the development of a more robust and lower risk exploration architecture.

NTR-Enhanced Lunar-Base Supply using Existing Launch Fleet Capabilities

International Nuclear Information System (INIS)

Bess, John D.; Colvin, Emily; Cummings, Paul G.

2009-01-01

During the summer of 2006, students at the Center for Space Nuclear Research sought to augment the current NASA lunar exploration architecture with a nuclear thermal rocket (NTR). An additional study investigated the possible use of an NTR with existing launch vehicles to provide 21 metric tons of supplies to the lunar surface in support of a lunar outpost. Current cost estimates show that the complete mission cost for an NTR-enhanced assembly of Delta-IV and Atlas V vehicles may cost 47-86% more than the estimated Ares V launch cost of $1.5B; however, development costs for the current NASA architecture have not been assessed. The additional cost of coordinating the rendezvous of four to six launch vehicles with an in-orbit assembly facility also needs more thorough analysis and review. Future trends in launch vehicle use will also significantly impact the results from this comparison. The utility of multiple launch vehicles allows for the development of a more robust and lower risk exploration architecture

Computational Analysis of Powered Lift Augmentation for the LEAPTech Distributed Electric Propulsion Wing

Science.gov (United States)

Deere, Karen A.; Viken, Sally A.; Carter, Melissa B.; Viken, Jeffrey K.; Wiese, Michael R.; Farr, Norma L.

2017-01-01

A computational study of a distributed electric propulsion wing with a 40deg flap deflection has been completed using FUN3D. Two lift-augmentation power conditions were compared with the power-off configuration on the high-lift wing (40deg flap) at a 73 mph freestream flow and for a range of angles of attack from -5 degrees to 14 degrees. The computational study also included investigating the benefit of corotating versus counter-rotating propeller spin direction to powered-lift performance. The results indicate a large benefit in lift coefficient, over the entire range of angle of attack studied, by using corotating propellers that all spin counter to the wingtip vortex. For the landing condition, 73 mph, the unpowered 40deg flap configuration achieved a maximum lift coefficient of 2.3. With high-lift blowing the maximum lift coefficient increased to 5.61. Therefore, the lift augmentation is a factor of 2.4. Taking advantage of the fullspan lift augmentation at similar performance means that a wing powered with the distributed electric propulsion system requires only 42 percent of the wing area of the unpowered wing. This technology will allow wings to be 'cruise optimized', meaning that they will be able to fly closer to maximum lift over drag conditions at the design cruise speed of the aircraft.

Robust Exploration and Commercial Missions to the Moon Using LANTR Propulsion and Lunar Liquid Oxygen Derived from FeO-Rich Pyroclastic Deposits

Science.gov (United States)

Borowski, Stanley K.; Ryan, Stephen W.; Burke, Laura M.; McCurdy, David R.; Fittje, James E.; Joyner, Claude R.

2017-01-01

The nuclear thermal rocket (NTR) has frequently been identified as a key space asset required for the human exploration of Mars. This proven technology can also provide the affordable access through cislunar space necessary for commercial development and sustained human presence on the Moon. It is a demonstrated technology capable of generating both high thrust and high specific impulse (Isp approx.900 s) twice that of todays best chemical rockets. Nuclear lunar transfer vehicles consisting of a propulsion stage using three approx.16.5 klbf Small Nuclear Rocket Engines (SNREs), an in-line propellant tank, plus the payload can enable a variety of reusable lunar missions. These include cargo delivery and crewed lunar landing missions. Even weeklong tourism missions carrying passengers into lunar orbit for a day of sightseeing and picture taking are possible. The NTR can play an important role in the next phase of lunar exploration and development by providing a robust in-space lunar transportation system (LTS) that can allow initial outposts to evolve into settlements supported by a variety of commercial activities such as in-situ propellant production used to supply strategically located propellant depots and transportation nodes. The use of lunar liquid oxygen (LLO2) derived from iron oxide (FeO)-rich volcanic glass beads, found in numerous pyroclastic deposits on the Moon, can significantly reduce the launch mass requirements from Earth by enabling reusable, surface-based lunar landing vehicles (LLVs) using liquid oxygen/hydrogen (LO2/H2) chemical rocket engines. Afterwards, a LO2/H2 propellant depot can be established in lunar equatorial orbit to supply the LTS. At this point a modified version of the conventional NTR called the LOX-augmented NTR, or LANTR is introduced into the LTS allowing bipropellant operation and leveraging the mission benefits of refueling with lunar-derived propellants for Earth return. The bipropellant LANTR engine utilizes the large

The rationale/benefits of nuclear thermal rocket propulsion for NASA's lunar space transportation system

Science.gov (United States)

Borowski, Stanley K.

1994-09-01

The solid core nuclear thermal rocket (NTR) represents the next major evolutionary step in propulsion technology. With its attractive operating characteristics, which include high specific impulse (approximately 850-1000 s) and engine thrust-to-weight (approximately 4-20), the NTR can form the basis for an efficient lunar space transportation system (LTS) capable of supporting both piloted and cargo missions. Studies conducted at the NASA Lewis Research Center indicate that an NTR-based LTS could transport a fully-fueled, cargo-laden, lunar excursion vehicle to the Moon, and return it to low Earth orbit (LEO) after mission completion, for less initial mass in LEO than an aerobraked chemical system of the type studied by NASA during its '90-Day Study.' The all-propulsive NTR-powered LTS would also be 'fully reusable' and would have a 'return payload' mass fraction of approximately 23 percent--twice that of the 'partially reusable' aerobraked chemical system. Two NTR technology options are examined--one derived from the graphite-moderated reactor concept developed by NASA and the AEC under the Rover/NERVA (Nuclear Engine for Rocket Vehicle Application) programs, and a second concept, the Particle Bed Reactor (PBR). The paper also summarizes NASA's lunar outpost scenario, compares relative performance provided by different LTS concepts, and discusses important operational issues (e.g., reusability, engine 'end-of life' disposal, etc.) associated with using this important propulsion technology.

Mars mission opportunity and transit time sensitivity for a nuclear thermal rocket propulsion application

International Nuclear Information System (INIS)

Young, A.C.; Mulqueen, J.A.; Nishimuta, E.L.; Emrich, W.J.

1993-01-01

President George Bush's 1989 challenge to America to support the Space Exploration Initiative (SEI) of ''Back to the Moon and Human Mission to Mars'' gives the space industry an opportunity to develop effective and efficient space transportation systems. This paper presents stage performance and requirements for a nuclear thermal rocket (NTR) Mars transportation system to support the human Mars mission of the SEI. Two classes of Mars mission profiles are considered in developing the NTR propulsion vehicle performance and requirements. The two Mars mission classes include the opposition class and conjunction class. The opposition class mission is associated with relatively short Mars stay times ranging from 30 to 90 days and total mission duration of 350 to 600 days. The conjunction class mission is associated with much longer Mars stay times ranging from 500 to 600 days and total mission durations of 875 to 1,000 days. Vehicle mass scaling equations are used to determine the NTR stage mass, size, and performance range required for different Mars mission opportunities and for different Mars mission durations. Mission opportunities considered include launch years 2010 to 2018. The 2010 opportunity is the most demanding launch opportunity and the 2018 opportunity is the least demanding opportunity. NTR vehicle mass and size sensitivity to NTR engine thrust level, engine specific impulse, NTR engine thrust-to-weight ratio, and Mars surface payload are presented. NTR propulsion parameter ranges include those associated with NERVA, particle bed reactor (PBR), low-pressure, and ceramic-metal-type engine design

Mars mission opportunity and transit time sensitivity for a nuclear thermal rocket propulsion application

Science.gov (United States)

Young, Archie C.; Mulqueen, John A.; Nishimuta, Ena L.; Emrich, William J.

1993-01-01

President George Bush's 1989 challenge to America to support the Space Exploration Initiative (SEI) of ``Back to the Moon and Human Mission to Mars'' gives the space industry an opportunity to develop effective and efficient space transportation systems. This paper presents stage performance and requirements for a nuclear thermal rocket (NTR) Mars transportation system to support the human Mars mission of the SEI. Two classes of Mars mission profiles are considered in developing the NTR propulsion vehicle performance and requirements. The two Mars mission classes include the opposition class and conjunction class. The opposition class mission is associated with relatively short Mars stay times ranging from 30 to 90 days and total mission duration of 350 to 600 days. The conjunction class mission is associated with much longer Mars stay times ranging from 500 to 600 days and total mission durations of 875 to 1,000 days. Vehicle mass scaling equations are used to determine the NTR stage mass, size, and performance range required for different Mars mission opportunities and for different Mars mission durations. Mission opportunities considered include launch years 2010 to 2018. The 2010 opportunity is the most demanding launch opportunity and the 2018 opportunity is the least demanding opportunity. NTR vehicle mass and size sensitivity to NTR engine thrust level, engine specific impulse, NTR engine thrust-to-weight ratio, and Mars surface payload are presented. NTR propulsion parameter ranges include those associated with NERVA, particle bed reactor (PBR), low-pressure, and ceramic-metal-type engine design.

Advanced Chemical Propulsion Study

Science.gov (United States)

Woodcock, Gordon; Byers, Dave; Alexander, Leslie A.; Krebsbach, Al

2004-01-01

A study was performed of advanced chemical propulsion technology application to space science (Code S) missions. The purpose was to begin the process of selecting chemical propulsion technology advancement activities that would provide greatest benefits to Code S missions. Several missions were selected from Code S planning data, and a range of advanced chemical propulsion options was analyzed to assess capabilities and benefits re these missions. Selected beneficial applications were found for higher-performing bipropellants, gelled propellants, and cryogenic propellants. Technology advancement recommendations included cryocoolers and small turbopump engines for cryogenic propellants; space storable propellants such as LOX-hydrazine; and advanced monopropellants. It was noted that fluorine-bearing oxidizers offer performance gains over more benign oxidizers. Potential benefits were observed for gelled propellants that could be allowed to freeze, then thawed for use.

Nuclear thermal rocket propulsion application to Mars missions

International Nuclear Information System (INIS)

Emrich, W.J. Jr.; Young, A.C.; Mulqueen, J.A.

1991-01-01

Options for vehicle configurations are reviewed in which nuclear thermal rocket (NTR) propulsion is used for a reference mission to Mars. The scenario assumes an opposition-class Mars transfer trajectory, a 435-day mission, and the use of a single nuclear engine with 75,000 lbs of thrust. Engine parameters are examined by calculating mission variables for a range of specific impulses and thrust/weight ratios. The reference mission is found to have optimal values of 925 s for the specific impulse and thrust/weight ratios of 4.0 and 0.06 for the engine and total stage ratios respectively. When the engine thrust/weight ratio is at least 4/1 the most critical engine parameter is engine specific impulse for reducing overall stage weight. In the context of this trans-Mars three-burn maneuver the NTR engine with an expander engine cycle is considered a more effective alternative than chemical/aerobrake and other propulsion options

The NtrY-NtrX two-component system is involved in controlling nitrate assimilation in Herbaspirillum seropedicae strain SmR1.

Science.gov (United States)

Bonato, Paloma; Alves, Lysangela R; Osaki, Juliana H; Rigo, Liu U; Pedrosa, Fabio O; Souza, Emanuel M; Zhang, Nan; Schumacher, Jörg; Buck, Martin; Wassem, Roseli; Chubatsu, Leda S

2016-11-01

Herbaspirillum seropedicae is a diazotrophic β-Proteobacterium found endophytically associated with gramineae (Poaceae or graminaceous plants) such as rice, sorghum and sugar cane. In this work we show that nitrate-dependent growth in this organism is regulated by the master nitrogen regulatory two-component system NtrB-NtrC, and by NtrY-NtrX, which functions to specifically regulate nitrate metabolism. NtrY is a histidine kinase sensor protein predicted to be associated with the membrane and NtrX is the response regulator partner. The ntrYntrX genes are widely distributed in Proteobacteria. In α-Proteobacteria they are frequently located downstream from ntrBC, whereas in β-Proteobacteria these genes are located downstream from genes encoding an RNA methyltransferase and a proline-rich protein with unknown function. The NtrX protein of α-Proteobacteria has an AAA+ domain, absent in those from β-Proteobacteria. An ntrY mutant of H. seropedicae showed the wild-type nitrogen fixation phenotype, but the nitrate-dependent growth was abolished. Gene fusion assays indicated that NtrY is involved in the expression of genes coding for the assimilatory nitrate reductase as well as the nitrate-responsive two-component system NarX-NarL (narK and narX promoters, respectively). The purified NtrX protein was capable of binding the narK and narX promoters, and the binding site at the narX promoter for the NtrX protein was determined by DNA footprinting. In silico analyses revealed similar sequences in other promoter regions of H. seropedicae that are related to nitrate assimilation, supporting the role of the NtrY-NtrX system in regulating nitrate metabolism in H. seropedicae. © 2016 Federation of European Biochemical Societies.

Characterization of genetic diversity and linkage disequilibrium of ZmLOX4 and ZmLOX5 loci in maize.

Directory of Open Access Journals (Sweden)

Gerald N De La Fuente

Full Text Available Maize (Zea mays L. lipoxygenases (ZmLOXs are well recognized as important players in plant defense against pathogens, especially in cross kingdom lipid communication with pathogenic fungi. This study is among the first to investigate genetic diversity at important gene paralogs ZmLOX4 and ZmLOX5. Sequencing of these genes in 400 diverse maize lines showed little genetic diversity and low linkage disequilibrium in the two genes. Importantly, we identified one inbred line in which ZmLOX5 has a disrupted open reading frame, a line missing ZmLOX5, and five lines with a duplication of ZmLOX5. Tajima's D test suggests that both ZmLOX4 and ZmLOX5 have been under neutral selection. Further investigation of haplotype data revealed that within the ZmLOX family members only ZmLOX12, a monocot specific ZmLOX, showed strong linkage disequilibrium that extends further than expected in maize. Linkage disequilibrium patterns at these loci of interest are crucial for future candidate gene association mapping studies. ZmLOX4 and ZmLOX5 mutations and copy number variants are under further investigation for crop improvement.

Adenovirus-mediated truncated Bid overexpression induced by the Cre/LoxP system promotes the cell apoptosis of CD133+ ovarian cancer stem cells.

Science.gov (United States)

Long, Qifang; Yang, Ru; Lu, Weixian; Zhu, Weipei; Zhou, Jundong; Zheng, Cui; Zhou, Dongmei; Yu, Ling; Wu, Jinchang

2017-01-01

Cancer stem cells are a small subset of cancer cells that contribute to cancer progression, metastasis, chemoresistance and recurrence. CD133-positive (CD133+) ovarian cancer cells have been identified as ovarian cancer stem cells. Adenovirus-mediated gene therapy is an innovative therapeutic method for cancer treatment. In the present study, we aimed to develop a new gene therapy to specifically eliminate CD133+ ovarian cancer stem cells by targeting CD133. We used the Cre/LoxP system to augment the selective expression of the truncated Bid (tBid) gene as suicide gene therapy in CD133+ ovarian cancer stem cells. The adenovirus (Ad)-CD133-Cre expressing Cre recombinase under the control of the CD133 promoter and Ad-CMV-LoxP-Neo-LoxP-tBid expressing tBid under the control of the CMV promoter were successfully constructed using the Cre/LoxP switching system. The co-infection of Ad-CMV-LoxP-Neo-LoxP-tBid and Ad-CD133-Cre selectively induced tBid overexpression, which inhibited cell growth and triggered the cell apoptosis of CD133+ ovarian cancer stem cells. The Cre/LoxP system-mediated tBid overexpression activated the pro-apoptotic signaling pathway and augmented the cytotoxic effect of cisplatin in CD133+ ovarian cancer stem cells. Furthermore, in xenograft experiments, co-infection with the two recombinant adenoviruses markedly suppressed tumor growth in vivo and promoted cell apoptosis in tumor tissues. Taken together, the present study provides evidence that the adenovirus-mediated tBid overexpression induced by the Cre/LoxP system can effectively eliminate CD133+ ovarian cancer stem cells, representing a novel therapeutic strategy for the treatment of ovarian cancer.

The ntrB and ntrC Genes Are Involved in the Regulation of Poly-3-Hydroxybutyrate Biosynthesis by Ammonia in Azospirillum brasilense Sp7

Science.gov (United States)

Sun, Jun; Peng, Xuan; Van Impe, Jan; Vanderleyden, Jos

2000-01-01

Azospirillum brasilense Sp7 and its ntrA (rpoN), ntrBC, and ntrC mutants have been evaluated for their capabilities of poly-3-hydroxybutyrate (PHB) accumulation in media with high and low ammonia concentrations. It was observed that the ntrBC and ntrC mutants can produce PHB in both low- and high-C/N-ratio media, while no significant PHB production was observed for the wild type or the ntrA mutant in low-C/N-ratio media. Further investigation by fermentation analysis indicated that the ntrBC and ntrC mutants were able to grow and accumulate PHB simultaneously in the presence of a high concentration of ammonia in the medium, while little PHB was produced in the wild type and ntrA (rpoN) mutant during active growth phase. These results provide the first genetic evidence that the ntrB and ntrC genes are involved in the regulation of PHB synthesis by ammonia in A. brasilense Sp7. PMID:10618211

Nuclear thermal propulsion transportation systems for lunar/Mars exploration

International Nuclear Information System (INIS)

Clark, J.S.; Borowski, S.K.; Mcilwain, M.C.; Pellaccio, D.G.

1992-09-01

Nuclear thermal propulsion technology development is underway at NASA and DoE for Space Exploration Initiative (SEI) missions to Mars, with initial near-earth flights to validate flight readiness. Several reactor concepts are being considered for these missions, and important selection criteria will be evaluated before final selection of a system. These criteria include: safety and reliability, technical risk, cost, and performance, in that order. Of the concepts evaluated to date, the Nuclear Engine for Rocket Vehicle Applications (NERVA) derivative (NDR) is the only concept that has demonstrated full power, life, and performance in actual reactor tests. Other concepts will require significant design work and must demonstrate proof-of-concept. Technical risk, and hence, development cost should therefore be lowest for the concept, and the NDR concept is currently being considered for the initial SEI missions. As lighter weight, higher performance systems are developed and validated, including appropriate safety and astronaut-rating requirements, they will be considered to support future SEI application. A space transportation system using a modular nuclear thermal rocket (NTR) system for lunar and Mars missions is expected to result in significant life cycle cost savings. Finally, several key issues remain for NTR's, including public acceptance and operational issues. Nonetheless, NTR's are believed to be the next generation of space propulsion systems - the key to space exploration

NADE, a p75NTR-associated cell death executor, is involved in signal transduction mediated by the common neurotrophin receptor p75NTR.

Science.gov (United States)

Mukai, J; Hachiya, T; Shoji-Hoshino, S; Kimura, M T; Nadano, D; Suvanto, P; Hanaoka, T; Li, Y; Irie, S; Greene, L A; Sato, T A

2000-06-09

The low affinity neurotrophin receptor p75NTR can mediate cell survival as well as cell death of neural cells by NGF and other neurotrophins. To elucidate p75NTR-mediated signal transduction, we screened p75NTR-associated proteins by a yeast two-hybrid system. We identified one positive clone and named NADE (p75NTR-associated cell death executor). Mouse NADE has marked homology to the human HGR74 protein. NADE specifically binds to the cell-death domain of p75NTR. Co-expression of NADE and p75NTR induced caspase-2 and caspase-3 activities and the fragmentation of nuclear DNA in 293T cells. However, in the absence of p75NTR, NADE failed to induce apoptosis, suggesting that NADE expression is necessary but insufficient for p75NTR-mediated apoptosis. Furthermore, p75NTR/NADE-induced cell death was dependent on NGF but not BDNF, NT-3, or NT-4/5, and the recruitment of NADE to p75NTR (intracellular domain) was dose-dependent. We obtained similar results from PC12 cells, nnr5 cells, and oligodendrocytes. Taken together, NADE is the first signaling adaptor molecule identified in the involvement of p75NTR-mediated apoptosis induced by NGF, and it may play an important role in the pathogenesis of neurogenetic diseases.

Arsenic augments the uptake of oxidized LDL by upregulating the expression of lectin-like oxidized LDL receptor in mouse aortic endothelial cells

Energy Technology Data Exchange (ETDEWEB)

Hossain, Ekhtear [Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan); Ota, Akinobu, E-mail: aota@aichi-med-u.ac.jp [Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan); Karnan, Sivasundaram; Damdindorj, Lkhagvasuren [Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan); Takahashi, Miyuki [Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan); Division of Hematology, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan); Konishi, Yuko; Konishi, Hiroyuki; Hosokawa, Yoshitaka [Department of Biochemistry, Aichi Medical University School of Medicine, Nagakute, Aichi (Japan)

2013-12-15

Although chronic arsenic exposure is a well-known risk factor for cardiovascular diseases, including atherosclerosis, the molecular mechanism underlying arsenic-induced atherosclerosis remains obscure. Therefore, this study aimed to elucidate this molecular mechanism. We examined changes in the mRNA level of the lectin-like oxidized LDL (oxLDL) receptor (LOX-1) in a mouse aortic endothelial cell line, END-D, after sodium arsenite (SA) treatment. SA treatment significantly upregulated LOX-1 mRNA expression; this finding was also verified at the protein expression level. Flow cytometry and fluorescence microscopy analyses showed that the cellular uptake of fluorescence (Dil)-labeled oxLDL was significantly augmented with SA treatment. In addition, an anti-LOX-1 antibody completely abrogated the augmented uptake of Dil-oxLDL. We observed that SA increased the levels of the phosphorylated forms of nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB)/p65. SA-induced upregulation of LOX-1 protein expression was clearly prevented by treatment with an antioxidant, N-acetylcysteine (NAC), or an NF-κB inhibitor, caffeic acid phenethylester (CAPE). Furthermore, SA-augmented uptake of Dil-oxLDL was also prevented by treatment with NAC or CAPE. Taken together, our results indicate that arsenic upregulates LOX-1 expression through the reactive oxygen species-mediated NF-κB signaling pathway, followed by augmented cellular oxLDL uptake, thus highlighting a critical role of the aberrant LOX-1 signaling pathway in the pathogenesis of arsenic-induced atherosclerosis. - Highlights: • Sodium arsenite (SA) increases LOX-1 expression in mouse aortic endothelial cells. • SA enhances cellular uptake of oxidized LDL in dose-dependent manner. • SA-induced ROS generation enhances phosphorylation of NF-κB. • SA upregulates LOX-1 expression through ROS-activated NF-κB signaling pathway.

Nuclear Thermal Rocket (NTR) Development Risk Communication

Science.gov (United States)

Kim, Tony

2014-01-01

There are clear advantages of development of a Nuclear Thermal Rocket (NTR) for a crewed mission to Mars. NTR for in-space propulsion enables more ambitious space missions by providing high thrust at high specific impulse (approximately 900 sec) that is 2 times the best theoretical performance possible for chemical rockets. Missions can be optimized for maximum payload capability to take more payload with reduced total mass to orbit; saving cost on reduction of the number of launch vehicles needed. Or missions can be optimized to minimize trip time significantly to reduce the deep space radiation exposure to the crew. NTR propulsion technology is a game changer for space exploration. However, "NUCLEAR" is a word that is feared and vilified by some groups and the hostility towards development of any nuclear systems can meet great opposition by the public as well as from national leaders and people in authority. Communication of nuclear safety will be critical to the success of the development of the NTR. Why is there a fear of nuclear? A bomb that can level a city is a scary weapon. The first and only times the Nuclear Bomb was used in a war was on Hiroshima and Nagasaki during World War 2. The "Little Boy" atomic bomb was dropped on Hiroshima on August 6, 1945 and the "Fat Man" on Nagasaki 3 days later on August 9th. Within the first 4 months of bombings, 90- 166 thousand people died in Hiroshima and 60-80 thousand died in Nagasaki. It is important to note for comparison that over 500 thousand people died and 5 million made homeless due to strategic bombing (approximately 150 thousand tons) of Japanese cities and war assets with conventional non-nuclear weapons between 1942- 1945. A major bombing campaign of "firebombing" of Tokyo called "Operation Meetinghouse" on March 9 and 10 consisting of 334 B-29's dropped approximately1,700 tons of bombs around 16 square mile area and over 100 thousand people have been estimated to have died. The declaration of death is very

Advanced Development of a Compact 5-15 lbf Lox/Methane Thruster for an Integrated Reaction Control and Main Engine Propulsion System

Science.gov (United States)

Hurlbert, Eric A.; McManamen, John Patrick; Sooknanen, Josh; Studak, Joseph W.

2011-01-01

This paper describes the advanced development and testing of a compact 5 to 15 lbf LOX/LCH4 thruster for a pressure-fed integrated main engine and RCS propulsion system to be used on a spacecraft "vertical" test bed (VTB). The ability of the RCS thruster and the main engine to operate off the same propellant supply in zero-g reduces mass and improves mission flexibility. This compact RCS engine incorporates several features to dramatically reduce mass and parts count, to ease manufacturing, and to maintain acceptable performance given that specific impulse (Isp) is not the driver. For example, radial injection holes placed on the chamber body for easier drilling, and high temperature Haynes 230 were selected for the chamber over other more expensive options. The valve inlets are rotatable before welding allowing different orientations for vehicle integration. In addition, the engine design effort selected a coil-on-plug ignition system which integrates a relay and coil with the plug electrode, and moves some exciter electronics to avionics driver board. The engine injector design has small dribble volumes to target minimum pulse widths of 20 msec. and an efficient minimum impulse bit of less than 0.05 lbf-sec. The propellants, oxygen and methane, were chosen because together they are a non-toxic, Mars-forward, high density, space storable, and high performance propellant combination that is capable of pressure-fed and pump-fed configurations and integration with life support and power subsystems. This paper will present the results of the advanced development testing to date of the RCS thruster and the integration with a vehicle propulsion system.

Study and Design of a Compact Fuel Carrying (Holding) System of a Nuclear-Thermal Propulsion Device

International Nuclear Information System (INIS)

Sultan, R.

2012-01-01

Humankind is exploratory by nature and stepping on Mars and beyond is the next frontier of space explorations. In order to achieve these ambitions, novel techniques for propulsion are needed because existing chemical rockets fail to fulfill such missions. Many efforts are underway to find the best alternative. All these efforts justify that nuclear thermal propulsion (NTR) is an ideal option for acquiring this goal. To study the feasibility and develop a conceptual model for indigenous development of this technology has been the objectives of this work. In this work, detailed study pertaining to nuclear thermal propulsion has been done by considering hardware issues, operational aspects and safety issues. Proposed long stay manned Mars mission by NASA has been considered for design specification than a simplified NTR is designed to find various essential parameters like vehicle differential velocity, mass flow rates and exhaust propellant velocity. Next, temperature contours for its geometry (with simplified assumptions) involving reactor core and converging-diverging nozzle is modeled and analyzed using Gambit 2.0 and Fluent 6.1. Then some detail is provided for its future proposed development phases as planned by NASA. Analysis from our design show feasibility of the proposed development of NTR, however, further research on material technology is needed to withhold such high temperatures around 2500 degree C. It is also recommended that neutronic design for mission specific systems may be performed. (author)

Regulation of COX and LOX by curcumin.

Science.gov (United States)

Rao, Chinthalapally V

2007-01-01

Turmeric (Curcuma longa) is extensively used as a household remedy for various diseases. For the last few decades, work has been done to establish the biological activities and pharmacological actions of curcumin, the principle constituent of turmeric. Curcumin has proven to be beneficial in the prevention and treatment of a number of inflammatory diseases due to its anti-inflammatory activity. Arachidonic acid-derived lipid mediators that are intimately involved in inflammation are biosynthesized by pathways dependent on cyclooxygenase (COX) and lipoxygenase (LOX) enzymes. The role of LOX and COX isoforms, particularly COX-2, in the inflammation has been well established. At cellular and molecular levels, curcumin has been shown to regulate a number of signaling pathways, including the eicosanoid pathway involving COX and LOX. A number of studies have been conducted that support curcumin-mediated regulation of COX and LOX pathways, which is an important mechanism by which curcumin prevents a number of disease processes, including the cancer. The specific regulation of 5-LOX and COX-2 by curcumin is not fully established; however, existing evidence indicates that curcumin regulates LOX and COX-2 predominately at the transcriptional level and, to a certain extent, the posttranslational level. Thus, the curcumin-selective transcriptional regulatory action of COX-2, and dual COX/LOX inhibitory potential of this naturally occurring agent provides distinctive advantages over synthetic COX/LOX inhibitors, such as nonsteroidal anti-inflammatory drugs. In this review, we discuss evidence that supports the regulation of COX and LOX enzymes by curcumin as the key mechanism for its beneficial effects in preventing various inflammatory diseases.

Nuclear propulsion: to go to the moon in 24 hours; Propulsion nucleaire: aller sur la lune en 24 heures

Energy Technology Data Exchange (ETDEWEB)

Freeman, M

1999-10-01

Nuclear propulsion is a necessary step to give to man the opportunity of developing activities in space. This technique enables rockets to go farther, more quickly and to transport more load than the classical chemical propulsion. Space travel requires huge quantities of energy. An equivalent quantity of energy can be extracted from 13 tons of liquid hydrogen-oxygen, from 20 g of uranium (fission), from 0.5 g of deuterium (fusion) and from 0.02 g of anti-hydrogen-hydrogen (annihilation). The concept of nuclear thermal rocket (NTR) is based on an embarked nuclear reactor whose purpose is to heat hydrogen to 3000 K temperature. The thrust can be increased by injecting liquid oxygen in the nozzle to react with supersonic hydrogen. (A.C.)

Cycle O(CY1991) NLS trade studies and analyses report. Book 2, part 2: Propulsion

Science.gov (United States)

Cronin, R.; Werner, M.; Bonson, S.; Spring, R.; Houston, R.

1992-01-01

This report documents the propulsion system tasks performed in support of the National Launch System (NLS) Cycle O preliminary design activities. The report includes trades and analyses covering the following subjects: (1) Maximum Tank Stretch Study; (2) No LOX Bleed Performance Analysis; (3) LOX Bleed Trade Study; (4) LO2 Tank Pressure Limits; (5) LOX Tank Pressurization System Using Helium; (6) Space Transportation Main Engine (STME) Heat Exchanger Performance; (7) LH2 Passive Recirculation Performance Analysis; (8) LH2 Bleed/Recirculation Study; (9) LH2 Tank Pressure Limits; and (10) LH2 Pressurization System. For each trade study an executive summary and a detailed trade study are provided. For the convenience of the reader, a separate section containing a compilation of only the executive summaries is also provided.

Swirl Coaxial Injector Testing with LOX/RP-J

Science.gov (United States)

Greene, Sandra Elam; Casiano, Matt

2013-01-01

Testing was conducted at NASA fs Marshall Space Flight Center (MSFC) in the fall of 2012 to evaluate the operation and performance of liquid oxygen (LOX) and kerosene (RP ]1) in an existing swirl coaxial injector. While selected Russian engines use variations of swirl coaxial injectors, component level performance data has not been readily available, and all previously documented component testing at MSFC with LOX/RP ]1 had been performed using a variety of impinging injector designs. Impinging injectors have been adequate for specific LOX/RP ]1 engine applications, yet swirl coaxial injectors offer easier fabrication efforts, providing cost and schedule savings for hardware development. Swirl coaxial elements also offer more flexibility for design changes. Furthermore, testing with LOX and liquid methane propellants at MSFC showed that a swirl coaxial injector offered improved performance compared to an impinging injector. So, technical interest was generated to see if similar performance gains could be achieved with LOX/RP ]1 using a swirl coaxial injector. Results would allow such injectors to be considered for future engine concepts that require LOX/RP ]1 propellants. Existing injector and chamber hardware was used in the test assemblies. The injector had been tested in previous programs at MSFC using LOX/methane and LOX/hydrogen propellants. Minor modifications were made to the injector to accommodate the required LOX/RP ]1 flows. Mainstage tests were performed over a range of chamber pressures and mixture ratios. Additional testing included detonated gbombs h for stability data. Test results suggested characteristic velocity, C*, efficiencies for the injector were 95 ]97%. The injector also appeared dynamically stable with quick recovery from the pressure perturbations generated in the bomb tests.

LOX is a novel mitotic spindle-associated protein essential for mitosis.

Science.gov (United States)

Boufraqech, Myriem; Wei, Darmood; Weyemi, Urbain; Zhang, Lisa; Quezado, Martha; Kalab, Petr; Kebebew, Electron

2016-05-17

LOX regulates cancer progression in a variety of human malignancies. It is overexpressed in aggressive cancers and higher expression of LOX is associated with higher cancer mortality. Here, we report a new function of LOX in mitosis. We show that LOX co-localizes to mitotic spindles from metaphase to telophase, and p-H3(Ser10)-positive cells harbor strong LOX staining. Further, purification of mitotic spindles from synchronized cells show that LOX fails to bind to microtubules in the presence of nocodazole, whereas paclitaxel treated samples showed enrichment in LOX expression, suggesting that LOX binds to stabilized microtubules. LOX knockdown leads to G2/M phase arrest; reduced p-H3(Ser10), cyclin B1, CDK1, and Aurora B. Moreover, LOX knockdown significantly increased sensitivity of cancer cells to chemotherapeutic agents that target microtubules. Our findings suggest that LOX has a role in cancer cell mitosis and may be targeted to enhance the activity of microtubule inhibitors for cancer therapy.

Vehicle configuration options using nuclear propulsion for Mars missions

Science.gov (United States)

Emrich, William J.

1993-01-01

The solid core nuclear thermal rocket (NTR) provides an attractive means of providing the propulsive force needed to accomplish a wide array of space missions. With its factor of two or more advantage in Isp over chemical engines, nuclear propulsion provides the opportunity to accomplish space missions which are impractical by other means. This paper focuses on the use of a nuclear thermal rocket to accomplish a variety of space missions with emphasis on the manned Mars mission. The particle bed reactor (PBR) type nuclear engine was chosen as the baseline engine used to conduct the present study because of its perceived versatility over other nuclear propulsion systems in conducting a wide variety of tasks. This study baselines a particle bed reactor engine with an engine thrust-to-weight ratio (~11.5) and a specific impulse of ~950 s. It is shown that a PBR engine of this type will offer distinct advantages over the larger and heavier NERVA type nuclear engines.

Vehicle configuration options using nuclear propulsion for Mars missions

International Nuclear Information System (INIS)

Emrich, W.J. Jr.

1993-01-01

The solid core nuclear thermal rocket (NTR) provides an attractive means of providing the propulsive force needed to accomplish a wide array of space missions. With its factor of two or more advantage in Isp over chemical engines, nuclear propulsion provides the opportunity to accomplish space missions which are impractical by other means. This paper focuses on the use of a nuclear thermal rocket to accomplish a variety of space missions with emphasis on the manned Mars mission. The particle bed reactor (PBR) type nuclear engine was chosen as the baseline engine used to conduct the present study because of its perceived versatility over other nuclear propulsion systems in conducting a wide variety of tasks. This study baselines a particle bed reactor engine with an engine thrust-to-weight ratio (∼11.5) and a specific impulse of ∼950 s. It is shown that a PBR engine of this type will offer distinct advantages over the larger and heavier NERVA type nuclear engines

On the use of a pulsed nuclear thermal rocket for interplanetary travel

OpenAIRE

Arias Montenegro, Francisco Javier

2016-01-01

The object of this work is a first assessment of the use of a pulsed nuclear thermal rocket for thrust and specific impulse (Isp) augmentation with particular reference to interplanetary travel. The basis of the novel space propulsion idea is the possibility of working in a bimodal fashion where the classical stationary nuclear thermal rocket (NTR) could be switch on or switch off as a pulsed reactor as desired by the mission planners. It was found that the key factor for Isp augmentation ...

A Crewed Mission to Apophis Using a Hybrid Bimodal Nuclear Thermal Electric Propulsion (BNTEP) System

Science.gov (United States)

Mccurdy, David R.; Borowski, Stanley K.; Burke, Laura M.; Packard, Thomas W.

2014-01-01

A BNTEP system is a dual propellant, hybrid propulsion concept that utilizes Bimodal Nuclear Thermal Rocket (BNTR) propulsion during high thrust operations, providing 10's of kilo-Newtons of thrust per engine at a high specific impulse (Isp) of 900 s, and an Electric Propulsion (EP) system during low thrust operations at even higher Isp of around 3000 s. Electrical power for the EP system is provided by the BNTR engines in combination with a Brayton Power Conversion (BPC) closed loop system, which can provide electrical power on the order of 100's of kWe. High thrust BNTR operation uses liquid hydrogen (LH2) as reactor coolant propellant expelled out a nozzle, while low thrust EP uses high pressure xenon expelled by an electric grid. By utilizing an optimized combination of low and high thrust propulsion, significant mass savings over a conventional NTR vehicle can be realized. Low thrust mission events, such as midcourse corrections (MCC), tank settling burns, some reaction control system (RCS) burns, and even a small portion at the end of the departure burn can be performed with EP. Crewed and robotic deep space missions to a near Earth asteroid (NEA) are best suited for this hybrid propulsion approach. For these mission scenarios, the Earth return V is typically small enough that EP alone is sufficient. A crewed mission to the NEA Apophis in the year 2028 with an expendable BNTEP transfer vehicle is presented. Assembly operations, launch element masses, and other key characteristics of the vehicle are described. A comparison with a conventional NTR vehicle performing the same mission is also provided. Finally, reusability of the BNTEP transfer vehicle is explored.

Self-renewal and chemotherapy resistance of p75NTR positive cells in esophageal squamous cell carcinomas

International Nuclear Information System (INIS)

Huang, Sheng-Dong; Yuan, Yang; Liu, Xiao-Hong; Gong, De-Jun; Bai, Chen-Guang; Wang, Feng; Luo, Jun-Hui; Xu, Zhi-Yun

2009-01-01

p75 NTR has been used to isolate esophageal and corneal epithelial stem cells. In the present study, we investigated the expression of p75 NTR in esophageal squamous cell carcinoma (ESCC) and explored the biological properties of p75 NTR+ cells. p75 NTR expression in ESCC was assessed by immunohistochemistry. p75 NTR+ and p75 NTR- cells of 4 ESCC cell lines were separated by fluorescence-activated cell sorting. Differentially expressed genes between p75 NTR+ and p75 NTR- cells were determined by real-time quantitative reverse transcription-PCR. Sphere formation assay, DDP sensitivity assay, 64 copper accumulation assay and tumorigenicity analysis were performed to determine the capacity of self-renewal, chemotherapy resistance and tumorigenicity of p75 NTR+ cells. In ESCC specimens, p75 NTR was found mainly confined to immature cells and absent in cells undergoing terminal differentiation. The percentage of p75 NTR+ cells was 1.6%–3.7% in Eca109 and 3 newly established ESCC cell lines. The expression of Bmi-1, which is associated with self-renewal of stem cells, was significantly higher in p75 NTR+ cells. p63, a marker identified in keratinocyte stem cells, was confined mainly to p75 NTR+ cells. The expression of CTR1, which is associated with cisplatin (DDP)-resistance, was significantly decreased in p75 NTR+ cells. Expression levels of differentiation markers, such as involucrin, cytokeratin 13, β1-integrin and β4-integrin, were lower in p75 NTR+ cells. In addition, p75 NTR+ cells generated both p75 NTR+ and p75 NTR- cells, and formed nonadherent spherical clusters in serum-free medium supplemented with growth factors. Furthermore, p75 NTR+ cells were found to be more resistant to DDP and exhibited lower 64 copper accumulation than p75 NTR- cells. Our results demonstrated that p75 NTR+ cells possess some characteristics of CSCs, namely, self-renewal and chemotherapy resistance. Chemotherapy resistance of p75 NTR+ cells may probably be attributable to

Nuclear propulsion: to go to the moon in 24 hours

International Nuclear Information System (INIS)

Freeman, M.

1999-01-01

Nuclear propulsion is a necessary step to give to man the opportunity of developing activities in space. This technique enables rockets to go farther, more quickly and to transport more load than the classical chemical propulsion. Space travel requires huge quantities of energy. An equivalent quantity of energy can be extracted from 13 tons of liquid hydrogen-oxygen, from 20 g of uranium (fission), from 0.5 g of deuterium (fusion) and from 0.02 g of anti-hydrogen-hydrogen (annihilation). The concept of nuclear thermal rocket (NTR) is based on an embarked nuclear reactor whose purpose is to heat hydrogen to 3000 K temperature. The thrust can be increased by injecting liquid oxygen in the nozzle to react with supersonic hydrogen. (A.C.)

Dermal Delivery of Constructs Encoding Cre Recombinase to Induce Skin Tumors in PtenLoxP/LoxP;BrafCA/+ Mice

Directory of Open Access Journals (Sweden)

Marcel A. Deken

2016-12-01

Full Text Available Current genetically-engineered mouse melanoma models are often based on Tyr::CreERT2-controlled MAPK pathway activation by the BRAFV600E mutation and PI3K pathway activation by loss of PTEN. The major drawback of these models is the occurrence of spontaneous tumors caused by leakiness of the Tyr::CreERT2 system, hampering long-term experiments. To address this problem, we investigated several approaches to optimally provide local delivery of Cre recombinase, including injection of lentiviral particles, DNA tattoo administration and particle-mediated gene transfer, to induce melanomas in PtenLoxP/LoxP;BrafCA/+ mice lacking the Tyr::CreERT2 allele. We found that dermal delivery of the Cre recombinase gene under the control of a non-specific CAG promoter induced the formation of melanomas, but also keratoacanthoma and squamous cell carcinomas. Delivery of Cre recombinase DNA under the control of melanocyte-specific promoters in PtenLoxP/LoxP;BrafCA/+ mice resulted in sole melanoma induction. The growth rate and histological features of the induced tumors were similar to 4-hydroxytamoxifen-induced tumors in Tyr::CreERT2;PtenLoxP/LoxP;BrafCA/+ mice, while the onset of spontaneous tumors was prevented completely. These novel induction methods will allow long-term experiments in mouse models of skin malignancies.

The transcriptional activator NtrC controls the expression and activity of glutamine synthetase in Herbaspirillum seropedicae.

Science.gov (United States)

Persuhn, D C; Souza, E M; Steffens, M B; Pedrosa, F O; Yates, M G; Rigo, L U

2000-11-15

The role of the Ntr system in Herbaspirillum seropedicae was determined via ntrB and ntrC mutants. Three phenotypes were identified in these mutants: Nif(-), deficiency in growth using nitrate, and low glutamine synthetase (GS) activity. All phenotypes were restored by the plasmid pKRT1 containing the intact glnA, ntrB and ntrC genes of H. seropedicae. The promoter region of glnA was subcloned into a beta-galactosidase fusion vector and the results suggested that NtrC positively regulates the glnA promoter in response to low nitrogen. The H. seropedicae ntrC and ntrB mutant strains showed a deficiency of adenylylation/deadenylylation of GS, indicating that NtrC and NtrB are involved in both transcription and activity control of GS in this organism.

Conventional and Bimodal Nuclear Thermal Rocket (NTR) Artificial Gravity Mars Transfer Vehicle Concepts

Science.gov (United States)

Borowski, Stanley K.; McCurdy, David R.; Packard, Thomas W.

2016-01-01

A variety of countermeasures have been developed to address the debilitating physiological effects of zero-gravity (0-g) experienced by cosmonauts and astronauts during their approximately 0.5 to 1.2 year long stays in low Earth orbit (LEO). Longer interplanetary flights, combined with possible prolonged stays in Mars orbit, could subject crewmembers to up to approximately 2.5 years of weightlessness. In view of known and recently diagnosed problems associated with 0-g, an artificial gravity (AG) spacecraft offers many advantages and may indeed be an enabling technology for human flights to Mars. A number of important human factors must be taken into account in selecting the rotation radius, rotation rate, and orientation of the habitation module or modules. These factors include the gravity gradient effect, radial and tangential Coriolis forces, along with cross-coupled acceleration effects. Artificial gravity Mars transfer vehicle (MTV) concepts are presented that utilize both conventional NTR, as well as, enhanced bimodal nuclear thermal rocket (BNTR) propulsion. The NTR is a proven technology that generates high thrust and has a specific impulse (Isp) capability of approximately 900 s-twice that of today's best chemical rockets. The AG/MTV concepts using conventional Nuclear Thermal Propulsion (NTP) carry twin cylindrical International Space Station (ISS)- type habitation modules with their long axes oriented either perpendicular or parallel to the longitudinal spin axis of the MTV and utilize photovoltaic arrays (PVAs) for spacecraft power. The twin habitat modules are connected to a central operations hub located at the front of the MTV via two pressurized tunnels that provide the rotation radius for the habitat modules. For the BNTR AG/MTV option, each engine has its own closed secondary helium(He)-xenon (Xe) gas loop and Brayton Rotating Unit (BRU) that can generate 10s of kilowatts (kWe) of spacecraft electrical power during the mission coast phase

Cre-loxP-Mediated Recombination: General Principles and Experimental Considerations.

Science.gov (United States)

McLellan, Micheal A; Rosenthal, Nadia A; Pinto, Alexander R

2017-03-02

The cre-loxP-mediated recombination system (the "cre-loxP system") is an integral experimental tool for mammalian genetics and cell biology. Use of the system has greatly expanded our ability to precisely interrogate gene function in the mouse, providing both spatial and temporal control of gene expression. This has been largely due to the simplicity of its use and its adaptability to address diverse biological questions. While the use of the cre-loxP system is becoming increasingly widespread, in particular because of growing availability of conditional mouse mutants, many considerations need to be taken into account when utilizing the cre-loxP system. This review provides an overview of the cre-loxP system and its various permutations. It addresses the limitations of cre-loxP technology and related considerations for experimental design, and it discusses alternative strategies for site-specific genetic recombination and integration. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Resistance to Fusarium verticillioides and fumonisin accumulation in maize inbred lines involves an earlier and enhanced expression of lipoxygenase (LOX) genes.

Science.gov (United States)

Maschietto, Valentina; Marocco, Adriano; Malachova, Alexandra; Lanubile, Alessandra

2015-09-01

Fusarium verticillioides causes ear rot in maize and contaminates the kernels with the fumonisin mycotoxins. It is known that plant lipoxygenase (LOX)-derived oxylipins regulate defence against pathogens and that the host-pathogen lipid cross-talk influences the pathogenesis. The expression profiles of fifteen genes of the LOX pathway were studied in kernels of resistant and susceptible maize lines, grown in field condition, at 3, 7 and 14 days post inoculation (dpi) with F. verticillioides. Plant defence responses were correlated with the pathogen growth, the expression profiles of fungal FUM genes for fumonisin biosynthesis and fumonisin content in the kernels. The resistant genotype limited fungal growth and fumonisin accumulation between 7 and 14 dpi. Pathogen growth became exponential in the susceptible line after 7 dpi, in correspondence with massive transcription of FUM genes and fumonisins augmented exponentially at 14 dpi. LOX pathway genes resulted strongly induced after pathogen inoculation in the resistant line at 3 and 7 dpi, whilst in the susceptible line the induction was reduced or delayed at 14 dpi. In addition, all genes resulted overexpressed before infection in kernels of the resistant genotype already at 3 dpi. The results suggest that resistance in maize may depend on an earlier activation of LOX genes and genes for jasmonic acid biosynthesis. Copyright © 2015 Elsevier GmbH. All rights reserved.

Neurotrophin receptor p75NTR mediates Huntington’s disease–associated synaptic and memory dysfunction

Science.gov (United States)

Brito, Verónica; Giralt, Albert; Enriquez-Barreto, Lilian; Puigdellívol, Mar; Suelves, Nuria; Zamora-Moratalla, Alfonsa; Ballesteros, Jesús J.; Martín, Eduardo D.; Dominguez-Iturza, Nuria; Morales, Miguel; Alberch, Jordi; Ginés, Sílvia

2014-01-01

Learning and memory deficits are early clinical manifestations of Huntington’s disease (HD). These cognitive impairments have been mainly associated with frontostriatal HD pathology; however, compelling evidence provided by several HD murine models suggests that the hippocampus may contribute to synaptic deficits and memory dysfunction in HD. The neurotrophin receptor p75NTR negatively regulates spine density, which is associated with learning and memory; therefore, we explored whether disturbed p75NTR function in the hippocampus could contribute to synaptic dysfunction and memory deficits in HD. Here, we determined that levels of p75NTR are markedly increased in the hippocampus of 2 distinct mouse models of HD and in HD patients. Normalization of p75NTR levels in HD mutant mice heterozygous for p75NTR prevented memory and synaptic plasticity deficits and ameliorated dendritic spine abnormalities, likely through normalization of the activity of the GTPase RhoA. Moreover, viral-mediated overexpression of p75NTR in the hippocampus of WT mice reproduced HD learning and memory deficits, while knockdown of p75NTR in the hippocampus of HD mice prevented cognitive decline. Together, these findings provide evidence of hippocampus-associated memory deficits in HD and demonstrate that p75NTR mediates synaptic, learning, and memory dysfunction in HD. PMID:25180603

Ex Luna Scientia: The Lunar Occultation Explorer (LOX)

Science.gov (United States)

Miller, Richard

2017-01-01

The Lunar Occultation Explorer (LOX) is a next-generation mission concept that provides new capabilities for time-domain astrophysics and established the Moon as a platform for nuclear astrophysics. Performance requirements are driven by Type-Ia supernova (SNeIa) science goals that seek to revel details of these profoundly radioactive objects, including their diversity. Primary science objectives include, but are not limited to, probing the fundamental thermonuclear physics processes, performing a census of progenitors and their explosion mechanisms, and evaluating the environmental conditions and intrinsic systematics of these enigmatic objects. LOX provides new capabilities for all-sky, continuous monitoring in the MeV regime (0.1-10 MeV) by leveraging the Lunar Occultation Technique (LOT). Key benefits of the LOX/LOT approach include maximizing the ratio of sensitive-to-total deployed mass, low implementation risk, and demonstrated operational simplicity that leverages extensive experience with planetary orbital geochemistry investigations; LOX also enables long-term monitoring of MeV gamma-ray sources, a critical capability for SNeIa science. Proof-of-principle efforts validated all aspects of the mission using previously deployed lunar science assets, and led to the first high-energy gamma-ray source detected at the Moon. LOX mission performance, development progress, and expectations for science investigations will be presented.

The potential for targeting extracellular LOX proteins in human malignancy

DEFF Research Database (Denmark)

Mayorca Guiliani, Alejandro Enrique; Erler, Janine T

2013-01-01

The extracellular matrix (ECM) is the physical scaffold where cells are organized into tissues and organs. The ECM may be modified during cancer to allow and promote proliferation, invasion, and metastasis. The family of lysyl oxidase (LOX) enzymes cross-links collagens and elastin and, therefore......, is a central player in ECM deposition and maturation. Extensive research has revealed how the LOX proteins participate in every stage of cancer progression, and two family members, LOX and LOX-like 2, have been linked to metastasis, the final stage of cancer responsible for over 90% of cancer patient deaths...

Liquid Oxygen Rotating Friction Ignition Testing of Aluminum and Titanium with Monel and Inconel for Rocket Engine Propulsion System Contamination Investigation

Science.gov (United States)

Peralta, S.; Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

Metallic contaminant was found in the liquid oxygen (LOX) pre-valve screen of the shuttle main engine propulsion system on two orbiter vehicles. To investigate the potential for an ignition, NASA Johnson Space Center White Sands Test Facility performed (modified) rotating friction ignition testing in LOX. This testing simulated a contaminant particle in the low-pressure oxygen turbo pump (LPOTP) and the high-pressure oxygen turbo pump (HPOTP) of the shuttle main propulsion system. Monel(R) K-500 and Inconel(R) 718 samples represented the LPOTP and HPOTP materials. Aluminum foil tape and titanium foil represented the contaminant particles. In both the Monel(R) and Inconel(R) material configurations, the aluminum foil tape samples did not ignite after 30 s of rubbing. In contrast, all of the titanium foil samples ignited regardless of the rubbing duration or material configuration. However, the titanium foil ignitions did not propagate to the Monel and Inconel materials.

Expression, purification, and DNA-binding activity of the solubilized NtrC protein of Herbaspirillum seropedicae.

Science.gov (United States)

Twerdochlib, Adriana L; Chubatsu, Leda S; Souza, Emanuel M; Pedrosa, Fábio O; Steffens, M Berenice R; Yates, M Geoffrey; Rigo, Liu U

2003-07-01

NtrC is a bacterial enhancer-binding protein (EBP) that activates transcription by the sigma54 RNA polymerase holoenzyme. NtrC has a three domain structure typical of EBP family. In Herbaspirillum seropedicae, an endophytic diazotroph, NtrC regulates several operons involved in nitrogen assimilation, including glnAntrBC. In order to over-express and purify the NtrC protein, DNA fragments containing the complete structural gene for the whole protein, and for the N-terminal+Central and Central+C-terminal domains were cloned into expression vectors. The NtrC and NtrC(N-terminal+Central) proteins were over-expressed as His-tag fusion proteins upon IPTG addition, solubilized using N-lauryl-sarcosyl and purified by metal affinity chromatography. The over-expressed His-tag-NtrC(Central+C-terminal) fusion protein was partially soluble and was also purified by affinity chromatography. DNA band-shift assays showed that the NtrC protein and the Central+C-terminal domains bound specifically to the H. seropedicae glnA promoter region. The C-terminal domain is presumably necessary for DNA-protein interaction and DNA-binding does not require a phosphorylated protein.

Total Hydrocarbon Content (THC) Testing in Liquid Oxygen (LOX)

Science.gov (United States)

Meneghelli, B. J.; Obregon, R. E.; Ross, H. R.; Hebert, B. J.; Sass, J. P.; Dirschka, G. E.

2016-01-01

The measured Total Hydrocarbon Content (THC) levels in liquid oxygen (LOX) systems at Stennis Space Center (SSC) have shown wide variations. Examples of these variations include the following: 1) differences between vendor-supplied THC values and those obtained using standard SSC analysis procedures; and 2) increasing THC values over time at an active SSC test stand in both storage and run vessels. A detailed analysis of LOX sampling techniques, analytical instrumentation, and sampling procedures will be presented. Additional data obtained on LOX system operations and LOX delivery trailer THC values during the past 12-24 months will also be discussed. Field test results showing THC levels and the distribution of the THC's in the test stand run tank, modified for THC analysis via dip tubes, will be presented.

Solar System Exploration Augmented by In-Situ Resource Utilization: Mercury and Saturn Propulsion Investigations

Science.gov (United States)

Palaszewski, Bryan

2016-01-01

Human and robotic missions to Mercury and Saturn are presented and analyzed with a range of propulsion options. Historical studies of space exploration, in-situ resource utilization (ISRU), and industrialization all point to the vastness of natural resources in the solar system. Advanced propulsion benefitted from these resources in many ways. While advanced propulsion systems were proposed in these historical studies, further investigation of nuclear options using high power nuclear thermal and nuclear pulse propulsion as well as advanced chemical propulsion can significantly enhance these scenarios. Updated analyses based on these historical visions will be presented. Nuclear thermal propulsion and ISRU enhanced chemical propulsion landers are assessed for Mercury missions. At Saturn, nuclear pulse propulsion with alternate propellant feed systems and Titan exploration with chemical propulsion options are discussed. In-situ resource utilization was found to be critical in making Mercury missions more amenable for human visits. At Saturn, refueling using local atmospheric mining was found to be difficult to impractical, while refueling the Saturn missions from Uranus was more practical and less complex.

Reduced anxiety-like behavior and altered hippocampal morphology in female p75NTR exon IV-/- mice.

Directory of Open Access Journals (Sweden)

Zoe ePuschban

2016-06-01

Full Text Available The presence of the neurotrophin receptor p75NTR in adult basal forebrain cholinergic neurons, precursor cells in the subventricular cell layer and the subgranular cell layer of the hippocampus has been linked to alterations in learning as well as anxiety- and depression- related behaviors. In contrast to previous studies performed in a p75NTR exonIII-/- model still expressing the short isoform of the p75NTR, we focused on locomotor and anxiety–associated behavior in p75NTR exonIV-/- mice lacking both p75NTR isoforms. Comparing p75NTR exonIV-/- and wildtype mice for both male and female animals showed an anxiolytic-like behavior as evidenced by increased central activities in the open field paradigm and flex field activity system as well as higher numbers of open arm entries in the elevated plus maze test in female p75NTR knockout mice.Morphometrical analyses of dorsal and ventral hippocampus revealed a reduction of width of the dentate gyrus and the granular cell layer in the dorsal but not ventral hippocampus in male and female p75NTR exonIV -/- mice. We conclude that germ-line deletion of p75NTR seems to differentially affect morphometry of dorsal and ventral dentate gyrus and that p75NTR may play a role in anxiety-like behavior, specifically in female mice.

The Propulsive-Only Flight Control Problem

Science.gov (United States)

Blezad, Daniel J.

1996-01-01

Attitude control of aircraft using only the throttles is investigated. The long time constants of both the engines and of the aircraft dynamics, together with the coupling between longitudinal and lateral aircraft modes make piloted flight with failed control surfaces hazardous, especially when attempting to land. This research documents the results of in-flight operation using simulated failed flight controls and ground simulations of piloted propulsive-only control to touchdown. Augmentation control laws to assist the pilot are described using both optimal control and classical feedback methods. Piloted simulation using augmentation shows that simple and effective augmented control can be achieved in a wide variety of failed configurations.

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy

Science.gov (United States)

Chen, Mingyi; Qiu, Hong; Lin, Xin; Nam, David; Ogbu-Nwobodo, Lucy; Archibald, Hannah; Joslin, Amelia; Wun, Ted; Sawamura, Tatsuya; Green, Ralph

2017-01-01

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications. PMID:27519944

Control-Volume Analysis Of Thrust-Augmenting Ejectors

Science.gov (United States)

Drummond, Colin K.

1990-01-01

New method of analysis of transient flow in thrust-augmenting ejector based on control-volume formulation of governing equations. Considered as potential elements of propulsion subsystems of short-takeoff/vertical-landing airplanes.

Cre/lox-based multiple markerless gene disruption in the genome of the extreme thermophile Thermus thermophilus.

Science.gov (United States)

Togawa, Yoichiro; Nunoshiba, Tatsuo; Hiratsu, Keiichiro

2018-02-01

Markerless gene-disruption technology is particularly useful for effective genetic analyses of Thermus thermophilus (T. thermophilus), which have a limited number of selectable markers. In an attempt to develop a novel system for the markerless disruption of genes in T. thermophilus, we applied a Cre/lox system to construct a triple gene disruptant. To achieve this, we constructed two genetic tools, a loxP-htk-loxP cassette and cre-expressing plasmid, pSH-Cre, for gene disruption and removal of the selectable marker by Cre-mediated recombination. We found that the Cre/lox system was compatible with the proliferation of the T. thermophilus HB27 strain at the lowest growth temperature (50 °C), and thus succeeded in establishing a triple gene disruptant, the (∆TTC1454::loxP, ∆TTC1535KpnI::loxP, ∆TTC1576::loxP) strain, without leaving behind a selectable marker. During the process of the sequential disruption of multiple genes, we observed the undesired deletion and inversion of the chromosomal region between multiple loxP sites that were induced by Cre-mediated recombination. Therefore, we examined the effects of a lox66-htk-lox71 cassette by exploiting the mutant lox sites, lox66 and lox71, instead of native loxP sites. We successfully constructed a (∆TTC1535::lox72, ∆TTC1537::lox72) double gene disruptant without inducing the undesired deletion of the 0.7-kbp region between the two directly oriented lox72 sites created by the Cre-mediated recombination of the lox66-htk-lox71 cassette. This is the first demonstration of a Cre/lox system being applicable to extreme thermophiles in a genetic manipulation. Our results indicate that this system is a powerful tool for multiple markerless gene disruption in T. thermophilus.

Role of LOX3 Gene in Alleviating Adverse Effects of Drought and Pathogens in Rice

Institute of Scientific and Technical Information of China (English)

LIU Nan-nan; JIANG Ling; ZHANG Wen-wei; LIU Ling-long; ZHAI Hu-qu; WAN Jian-min

2008-01-01

Lipoxygenase 3 (LOX3) is a major component of the LOX isozymes in mature rice seeds. To investigate the role of LOX3 gene under stresses, a plant expression vector containing antisense cDNA of LOX3 was constructed. Rice varieties Wuyunjing 7 and Kasalath were transformed by the Agrobacterium-mediated method and transgenic rice plants were generated. PCR and Southern blot results showed that the antisense LOX3 gene was integrated into the rice genome. Analyses of embryo LOX3 deletion and semi-quantitative RT-PCR confirmed the antisense suppression of LOX3 gene in transgenic plants. The T2 antisense plants of LOX3 were sensitive to drought stress, rice blast and bacterial blight compared with non-transgenic plants. These results suggest that the LOX3 gene might function in response to stresses.

NtrC-dependent control of exopolysaccharide synthesis and motility in Burkholderia cenocepacia H111.

Directory of Open Access Journals (Sweden)

Yilei Liu

Full Text Available Burkholderia cenocepacia is a versatile opportunistic pathogen that survives in a wide variety of environments, which can be limited in nutrients such as nitrogen. We have previously shown that the sigma factor σ54 is involved in the control of nitrogen assimilation and virulence in B. cenocepacia H111. In this work, we investigated the role of the σ54 enhancer binding protein NtrC in response to nitrogen limitation and in the pathogenicity of H111. Of 95 alternative nitrogen sources tested the ntrC showed defects in the utilisation of nitrate, urea, L-citrulline, acetamide, DL-lactamide, allantoin and parabanic acid. RNA-Seq and phenotypic analyses of an ntrC mutant strain showed that NtrC positively regulates two important phenotypic traits: exopolysaccharide (EPS production and motility. However, the ntrC mutant was not attenuated in C. elegans virulence.

Neurotrophin Receptor p75NTR Regulates Immune Function of Plasmacytoid Dendritic Cells.

Science.gov (United States)

Bandoła, Joanna; Richter, Cornelia; Ryser, Martin; Jamal, Arshad; Ashton, Michelle P; von Bonin, Malte; Kuhn, Matthias; Dorschner, Benjamin; Alexopoulou, Dimitra; Navratiel, Katrin; Roeder, Ingo; Dahl, Andreas; Hedrich, Christian M; Bonifacio, Ezio; Brenner, Sebastian; Thieme, Sebastian

2017-01-01

Plasmacytoid dendritic cells (pDCs) regulate innate and adaptive immunity. Neurotrophins and their receptors control the function of neuronal tissue. In addition, they have been demonstrated to be part of the immune response but little is known about the effector immune cells involved. We report, for the first time, the expression and immune-regulatory function of the low affinity neurotrophin receptor p75 neurotrophin receptor (p75NTR) by the antigen-presenting pDCs, mediated by toll-like receptor (TLR) 9 activation and differential phosphorylation of interferon regulatory factor 3 and 7. The modulation of p75NTR on pDCs significantly influences disease progression of asthma in an ovalbumin-induced mouse model mediated by the TLR9 signaling pathway. p75NTR activation of pDCs from patients with asthma increased allergen-specific T cell proliferation and cytokine secretion in nerve growth factor concentration-dependent manner. Further, p75NTR activation of pDCs delayed the onset of autoimmune diabetes in RIP-CD80GP mice and aggravated graft-versus-host disease in a xenotransplantation model. Thus, p75NTR signaling on pDCs constitutes a new and critical mechanism connecting neurotrophin signaling and immune response regulation with great therapeutic potential for a variety of immune disorders.

Neurotrophin Receptor p75NTR Regulates Immune Function of Plasmacytoid Dendritic Cells

Directory of Open Access Journals (Sweden)

Joanna Bandoła

2017-08-01

Full Text Available Plasmacytoid dendritic cells (pDCs regulate innate and adaptive immunity. Neurotrophins and their receptors control the function of neuronal tissue. In addition, they have been demonstrated to be part of the immune response but little is known about the effector immune cells involved. We report, for the first time, the expression and immune-regulatory function of the low affinity neurotrophin receptor p75 neurotrophin receptor (p75NTR by the antigen-presenting pDCs, mediated by toll-like receptor (TLR 9 activation and differential phosphorylation of interferon regulatory factor 3 and 7. The modulation of p75NTR on pDCs significantly influences disease progression of asthma in an ovalbumin-induced mouse model mediated by the TLR9 signaling pathway. p75NTR activation of pDCs from patients with asthma increased allergen-specific T cell proliferation and cytokine secretion in nerve growth factor concentration-dependent manner. Further, p75NTR activation of pDCs delayed the onset of autoimmune diabetes in RIP-CD80GP mice and aggravated graft-versus-host disease in a xenotransplantation model. Thus, p75NTR signaling on pDCs constitutes a new and critical mechanism connecting neurotrophin signaling and immune response regulation with great therapeutic potential for a variety of immune disorders.

Total hydrocarbon content (THC) testing in liquid oxygen (LOX) systems

Science.gov (United States)

Meneghelli, B. J.; Obregon, R. E.; Ross, H. R.; Hebert, B. J.; Sass, J. P.; Dirschka, G. E.

2015-12-01

The measured Total Hydrocarbon Content (THC) levels in liquid oxygen (LOX) systems at Stennis Space Center (SSC) have shown wide variations. Examples of these variations include the following: 1) differences between vendor-supplied THC values and those obtained using standard SSC analysis procedures; and 2) increasing THC values over time at an active SSC test stand in both storage and run vessels. A detailed analysis of LOX sampling techniques, analytical instrumentation, and sampling procedures will be presented. Additional data obtained on LOX system operations and LOX delivery trailer THC values during the past 12-24 months will also be discussed. Field test results showing THC levels and the distribution of the THC's in the test stand run tank, modified for THC analysis via dip tubes, will be presented.

Robust Exploration and Commercial Missions to the Moon Using Nuclear Thermal Rocket Propulsion and Lunar Liquid Oxygen Derived from FeO-Rich Pyroclasitc Deposits

Science.gov (United States)

Borowski, Stanley K.; Ryan, Stephen W.; Burke, Laura M.; McCurdy, David R.; Fittje, James E.; Joyner, Claude R.

2018-01-01

The nuclear thermal rocket (NTR) has frequently been identified as a key space asset required for the human exploration of Mars. This proven technology can also provide the affordable access through cislunar space necessary for commercial development and sustained human presence on the Moon. It is a demonstrated technology capable of generating both high thrust and high specific impulse (I(sub sp) approx. 900 s) twice that of today's best chemical rockets. Nuclear lunar transfer vehicles-consisting of a propulsion stage using three approx. 16.5-klb(sub f) small nuclear rocket engines (SNREs), an in-line propellant tank, plus the payload-are reusable, enabling a variety of lunar missions. These include cargo delivery and crewed lunar landing missions. Even weeklong ''tourism'' missions carrying passengers into lunar orbit for a day of sightseeing and picture taking are possible. The NTR can play an important role in the next phase of lunar exploration and development by providing a robust in-space lunar transportation system (LTS) that can allow initial outposts to evolve into settlements supported by a variety of commercial activities such as in-situ propellant production used to supply strategically located propellant depots and transportation nodes. The use of lunar liquid oxygen (LLO2) derived from iron oxide (FeO)-rich volcanic glass beads, found in numerous pyroclastic deposits on the Moon, can significantly reduce the launch mass requirements from Earth by enabling reusable, surface-based lunar landing vehicles (LLVs)that use liquid oxygen and hydrogen (LO2/LH2) chemical rocket engines. Afterwards, a LO2/LH2 propellant depot can be established in lunar equatorial orbit to supply the LTS. At this point a modified version of the conventional NTR-called the LO2-augmented NTR, or LANTR-is introduced into the LTS allowing bipropellant operation and leveraging the mission benefits of refueling with lunar-derived propellants for Earth return. The bipropellant LANTR

Development of An Intelligent Flight Propulsion Control System

Science.gov (United States)

Calise, A. J.; Rysdyk, R. T.; Leonhardt, B. K.

1999-01-01

The initial design and demonstration of an Intelligent Flight Propulsion and Control System (IFPCS) is documented. The design is based on the implementation of a nonlinear adaptive flight control architecture. This initial design of the IFPCS enhances flight safety by using propulsion sources to provide redundancy in flight control. The IFPCS enhances the conventional gain scheduled approach in significant ways: (1) The IFPCS provides a back up flight control system that results in consistent responses over a wide range of unanticipated failures. (2) The IFPCS is applicable to a variety of aircraft models without redesign and,(3) significantly reduces the laborious research and design necessary in a gain scheduled approach. The control augmentation is detailed within an approximate Input-Output Linearization setting. The availability of propulsion only provides two control inputs, symmetric and differential thrust. Earlier Propulsion Control Augmentation (PCA) work performed by NASA provided for a trajectory controller with pilot command input of glidepath and heading. This work is aimed at demonstrating the flexibility of the IFPCS in providing consistency in flying qualities under a variety of failure scenarios. This report documents the initial design phase where propulsion only is used. Results confirm that the engine dynamics and associated hard nonlineaaities result in poor handling qualities at best. However, as demonstrated in simulation, the IFPCS is capable of results similar to the gain scheduled designs of the NASA PCA work. The IFPCS design uses crude estimates of aircraft behaviour. The adaptive control architecture demonstrates robust stability and provides robust performance. In this work, robust stability means that all states, errors, and adaptive parameters remain bounded under a wide class of uncertainties and input and output disturbances. Robust performance is measured in the quality of the tracking. The results demonstrate the flexibility of

[Spectral analysis of polyphenol oxidase (PPO) and lipoxygenase (LOX) treated by pulsed electric field].

Science.gov (United States)

Luo, Wei; Zhang, Ruo-Bing; Chen, Jie; Wang, Li-Ming; Guan, Zhi-Cheng; Jia, Zhi-Dong

2009-08-01

Inactivation effect of pulsed electric field (PEF) on polyphenol oxidase (PPO) and lipoxygenase (LOX) was investigated using a laboratory PEF system with a coaxial treatment chamber. Circular dichroism (CD) and fluorescence analysis were used to study the conformation change of the protein. The experimental results show that PPO and LOX can be effectively inactivated by the PEF treatment. Inactivation effect of PPO and LOX increases with the increase in the applied electric strength and the treatment time. Activity of PPO and LOX can be reduced by 60.3% and 21.7% at 20 kV x cm(-1) after being treated for 320 micros respectively. The decrease of the negative peaks (208 and 215 nm in PPO spectra, 208 nm and 218 nm in LOX spectra) in CD spectra of PPO and LOX shows that PEF treatment caused a loss of alpha-helix and increase in beta-sheet content, indicating that conformation changes occur in the secondary structure of PPO and LOX enzyme. This effect was strengthened as the applied electric field increased: alpha-helical content of PPO and LOX was 56% and 29% after being treated at 8 kV x cm(-1), however, when the electric field was increased up to 20 kV x cm(-1), alpha-helical content of PPO and LOX decreased to 21% and 16% respectively. The decrease rate of alpha-helix and increase rate of beta-sheet in PPO are higher than LOX, indicating that the second conformation of PPO is less resistant to PEF treatment than LOX. The fluorescence intensity of LOX increases after PEF treatment. At the same time, increasing the applied pulsed electric field increases the fluorescence intensity emitted. Fluorescence measurements confirm that tertiary conformation changes occur in the local structure of LOX. However the possible mechanism of the conformation change induced by the PEF treatment is beyond the scope of the present investigation.

Solar Electric and Chemical Propulsion Technology Applications to a Titan Orbiter/Lander Mission

Science.gov (United States)

Cupples, Michael

2007-01-01

Several advanced propulsion technology options were assessed for a conceptual Titan Orbiter/Lander mission. For convenience of presentation, the mission was broken into two phases: interplanetary and Titan capture. The interplanetary phase of the mission was evaluated for an advanced Solar Electric Propulsion System (SEPS), while the Titan capture phase was evaluated for state-of-art chemical propulsion (NTO/Hydrazine), three advanced chemical propulsion options (LOX/Hydrazine, Fluorine/Hydrazine, high Isp mono-propellant), and advanced tank technologies. Hence, this study was referred to as a SEPS/Chemical based option. The SEPS/Chemical study results were briefly compared to a 2002 NASA study that included two general propulsion options for the same conceptual mission: an all propulsive based mission and a SEPS/Aerocapture based mission. The SEP/Chemical study assumed identical science payload as the 2002 NASA study science payload. The SEPS/Chemical study results indicated that the Titan mission was feasible for a medium launch vehicle, an interplanetary transfer time of approximately 8 years, an advanced SEPS (30 kW), and current chemical engine technology (yet with advanced tanks) for the Titan capture. The 2002 NASA study showed the feasibility of the mission based on a somewhat smaller medium launch vehicle, an interplanetary transfer time of approximately 5.9 years, an advanced SEPS (24 kW), and advanced Aerocapture based propulsion technology for the Titan capture. Further comparisons and study results were presented for the advanced chemical and advanced tank technologies.

The p75NTR tumor suppressor induces cell cycle arrest facilitating caspase mediated apoptosis in prostate tumor cells

International Nuclear Information System (INIS)

Khwaja, Fatima; Tabassum, Arshia; Allen, Jeff; Djakiew, Daniel

2006-01-01

The p75 neurotrophin receptor (p75 NTR ) is a death receptor which belongs to the tumor necrosis factor receptor super-family of membrane proteins. This study shows that p75 NTR retarded cell cycle progression by induced accumulation of cells in G0/G1 and a reduction in the S phase of the cell cycle. The rescue of tumor cells from cell cycle progression by a death domain deleted (ΔDD) dominant-negative antagonist of p75 NTR showed that the death domain transduced anti-proliferative activity in a ligand-independent manner. Conversely, addition of NGF ligand rescued retardation of cell cycle progression with commensurate changes in components of the cyclin/cdk holoenzyme complex. In the absence of ligand, p75 NTR -dependent cell cycle arrest facilitated an increase in apoptotic nuclear fragmentation of the prostate cancer cells. Apoptosis of p75 NTR expressing cells occurred via the intrinsic mitochondrial pathway leading to a sequential caspase-9 and -7 cascade. Since the death domain deleted dominant-negative antagonist of p75 NTR rescued intrinsic caspase associated apoptosis in PC-3 cells, this shows p75 NTR was integral to ligand independent induction of apoptosis. Moreover, the ability of ligand to ameliorate the p75 NTR -dependent intrinsic apoptotic cascade indicates that NGF functioned as a survival factor for p75 NTR expressing prostate cancer cells

Contribution of p75NTR to Schwannoma Growth and Therapeutic Responses

Science.gov (United States)

2017-05-01

reducing schwannoma cell growth in culture and in animal models of human schwannoma disease. We find that the NF2 gene product, merlin, regulates p75NTR...treatment period. B. Waterfall plots of change in tumor volume for each tumor. Task 6- Define the ability of simultaneous inhibition of p75NTR and mTOR...mTOR inhibitors in culture, we have not used these compounds in animal models . Changes that had a significant impact on expenditures- None

Nuclear Thermal Propulsion Development Risks

Science.gov (United States)

Kim, Tony

2015-01-01

There are clear advantages of development of a Nuclear Thermal Propulsion (NTP) for a crewed mission to Mars. NTP for in-space propulsion enables more ambitious space missions by providing high thrust at high specific impulse ((is) approximately 900 sec) that is 2 times the best theoretical performance possible for chemical rockets. Missions can be optimized for maximum payload capability to take more payload with reduced total mass to orbit; saving cost on reduction of the number of launch vehicles needed. Or missions can be optimized to minimize trip time significantly to reduce the deep space radiation exposure to the crew. NTR propulsion technology is a game changer for space exploration to Mars and beyond. However, 'NUCLEAR' is a word that is feared and vilified by some groups and the hostility towards development of any nuclear systems can meet great opposition by the public as well as from national leaders and people in authority. The public often associates the 'nuclear' word with weapons of mass destruction. The development NTP is at risk due to unwarranted public fears and clear honest communication of nuclear safety will be critical to the success of the development of the NTP technology. Reducing cost to NTP development is critical to its acceptance and funding. In the past, highly inflated cost estimates of a full-scale development nuclear engine due to Category I nuclear security requirements and costly regulatory requirements have put the NTP technology as a low priority. Innovative approaches utilizing low enriched uranium (LEU). Even though NTP can be a small source of radiation to the crew, NTP can facilitate significant reduction of crew exposure to solar and cosmic radiation by reducing trip times by 3-4 months. Current Human Mars Mission (HMM) trajectories with conventional propulsion systems and fuel-efficient transfer orbits exceed astronaut radiation exposure limits. Utilizing extra propellant from one additional SLS launch and available

Contemporary zebrafish transgenesis with Tol2 and application for Cre/lox recombination experiments.

Science.gov (United States)

Felker, A; Mosimann, C

2016-01-01

Spatiotemporal transgene regulation by transgenic DNA recombinases is a central tool for reverse genetics in multicellular organisms, with excellent applications for misexpression and lineage tracing experiments. One of the most widespread technologies for this purpose is Cre recombinase-controlled lox site recombination that is attracting increasing interest in the zebrafish field. Tol2-mediated zebrafish transgenesis provides a stable platform to integrate lox cassette transgenes, while the amenability of the zebrafish embryo to drug treatments makes the model an ideal candidate for tamoxifen-inducible CreERT2 experiments. In addition, advanced transgenesis technologies such as phiC31 or CRISPR-Cas9-based knock-ins are even further promoting zebrafish transgenesis for Cre/lox applications. In this chapter, we will first introduce the basics of Cre/lox methodology, CreERT2 regulation by tamoxifen, as well as the utility of Tol2 and other contemporary transgenesis techniques for Cre/lox experiments. We will then outline in detail practical experimental steps for efficient transgenesis toward the creation of single-insertion transgenes and will introduce protocols for 4-hydroxytamoxifen-mediated CreERT2 induction to perform spatiotemporal lox transgene regulation experiments in zebrafish embryos. Last, we will discuss advanced experimental applications of Cre/lox beyond traditional lineage tracing approaches. Copyright © 2016 Elsevier Inc. All rights reserved.

Characterization of NGF, trkANGFR, and p75NTR in Retina of Mice Lacking Reelin Glycoprotein

Directory of Open Access Journals (Sweden)

Bijorn Omar Balzamino

2014-01-01

Full Text Available Both Reelin and Nerve Growth Factor (NGF exert crucial roles in retinal development. Retinogenesis is severely impaired in E-reeler mice, a model of Reelin deficiency showing specific Green Fluorescent Protein expression in Rod Bipolar Cells (RBCs. Since no data are available on Reelin and NGF cross-talk, NGF and trkANGFR/ p75NTR expression was investigated in retinas from E-reeler versus control mice, by confocal microscopy, Western blotting, and real time PCR analysis. A scattered increase of NGF protein was observed in the Ganglion Cell Layer and more pronounced in the Inner Nuclear Layer (INL. A selective increase of p75NTR was detected in most of RBCs and in other cell subtypes of INL. On the contrary, a slight trend towards a decrease was detected for trkANGFR, albeit not significant. Confocal data were validated by Western blot and real time PCR. Finally, the decreased trkANGFR/ p75NTR ratio, representative of p75NTR increase, significantly correlated with E-reeler versus E-control. These data indicate that NGF-trkANGFR/ p75NTR is affected in E-reeler retina and that p75NTR might represent the main NGF receptor involved in the process. This first NGF-trkANGFR/ p75NTR characterization suggests that E-reeler might be suitable for exploring Reelin-NGF cross-talk, representing an additional information source in those pathologies characterized by retinal degeneration.

The LOX-1 Scavenger Receptor and Its Implications in the Treatment of Vascular Disease

Directory of Open Access Journals (Sweden)

M. W Twigg

2012-01-01

Full Text Available Cardiovascular disease is the leading cause of death. The disease is due to atherosclerosis which is characterized by lipid and fat accumulation in arterial blood vessel walls. A key causative event is the accumulation of oxidised low density lipoprotein particles within vascular cells, and this is mediated by scavenger receptors. One such molecule is the LOX-1 scavenger receptor that is expressed on endothelial, vascular smooth muscle, and lymphoid cells including macrophages. LOX-1 interaction with OxLDL particles stimulates atherosclerosis. LOX-1 mediates OxLDL endocytosis via a clathrin-independent internalization pathway. Transgenic animal model studies show that LOX-1 plays a significant role in atherosclerotic plaque initiation and progression. Administration of LOX-1 antibodies in cellular and animal models suggest that such intervention inhibits atherosclerosis. Antiatherogenic strategies that target LOX-1 function using gene therapy or small molecule inhibitors would be new ways to address the increasing incidence of vascular disease in many countries.

Carprofen Induction of p75NTR Dependent Apoptosis via the p38 MAPK Pathway in Prostate Cancer Cells

Science.gov (United States)

Khwaja, Fatima S.; Quann, Emily J.; Pattabiraman, Nagarajan; Wynne, Shehla; Djakiew, Daniel

2008-01-01

The p75NTR functions as a tumor suppressor in prostate epithelial cells, where its expression declines with progression to malignant cancer. Previously, we demonstrated that treatment with R-flurbiprofen or ibuprofen induced p75NTR expression in several prostate cancer cell lines leading to p75NTR mediated decreased survival. Utilizing the 2-phenyl propionic acid moiety of these profens as a pharmacophore, we screened an in silico data base of 30 million compounds and identified carprofen as having an order of magnitude greater activity for induction of p75NTR levels and inhibition of cell survival. Prostate (PC-3, DU-145) and bladder (T24) cancer cells were more sensitive to carprofen induction of p75NTR associated loss of survival than breast (MCF7) and fibroblast (3T3) cells. Transfection of prostate cell lines with a dominant negative form of p75NTR prior to carprofen treatment partially rescued cell survival demonstrating a cause and effect relationship between carprofen induction of p75NTR levels and inhibition of survival. Carprofen induced apoptotic nuclear fragmentation in prostate but not in MCF7 and 3T3 cells. Furthermore, siRNA knockdown of the p38 MAPK protein prevented induction of p75NTR by carprofen in both prostate cell lines. Carprofen treatment induced phosphorylation of p38 MAPK as early as within 1 minute. Expression of a dominant negative form of MK2, the kinase downstream of p38 MAPK frequently associated with signaling cascades leading to apoptosis, prevented carprofen induction of the p75NTR protein. Collectively, we identify carprofen as a highly potent profen capable of inducing p75NTR dependent apoptosis via the p38 MAPK pathway in prostate cancer cells. PMID:18974393

LOX: Inferring level of expression from diverse methods of census sequencing

KAUST Repository

Zhang, Zhang

2010-06-10

Summary: We present LOX (Level Of eXpression) that estimates the Level Of gene eXpression from high-throughput-expressed sequence datasets with multiple treatments or samples. Unlike most analyses, LOX incorporates a gene bias model that facilitates integration of diverse transcriptomic sequencing data that arises when transcriptomic data have been produced using diverse experimental methodologies. LOX integrates overall sequence count tallies normalized by total expressed sequence count to provide expression levels for each gene relative to all treatments as well as Bayesian credible intervals. © The Author 2010. Published by Oxford University Press. All rights reserved.

LOX: Inferring level of expression from diverse methods of census sequencing

KAUST Repository

Zhang, Zhang; Ló pez-Girá ldez, Francesc Francisco; Townsend, Jeffrey P.

2010-01-01

Summary: We present LOX (Level Of eXpression) that estimates the Level Of gene eXpression from high-throughput-expressed sequence datasets with multiple treatments or samples. Unlike most analyses, LOX incorporates a gene bias model that facilitates integration of diverse transcriptomic sequencing data that arises when transcriptomic data have been produced using diverse experimental methodologies. LOX integrates overall sequence count tallies normalized by total expressed sequence count to provide expression levels for each gene relative to all treatments as well as Bayesian credible intervals. © The Author 2010. Published by Oxford University Press. All rights reserved.

p75NTR enhances PC12 cell tumor growth by a non-receptor mechanism involving downregulation of cyclin D2

International Nuclear Information System (INIS)

Fritz, Melinda D.; Mirnics, Zeljka K.; Nylander, Karen D.; Schor, Nina F.

2006-01-01

p75NTR is a member of the tumor necrosis superfamily of proteins which is variably associated with induction of apoptosis and proliferation. Cyclin D2 is one of the mediators of cellular progression through G1 phase of the cell cycle. The present study demonstrates the inverse relationship between expression of cyclin D2 and expression of p75NTR in PC12 cells. Induction of p75NTR expression in p75NTR-negative PC12 cells results in downregulation of cyclin D2; suppression of p75NTR expression with siRNA in native PC12 cells results in upregulation of cyclin D2. The effects of p75NTR on cyclin D2 expression are mimicked in p75NTR-negative cells by transfection with the intracellular domain of p75NTR. Cyclin-D2-positive PC12 cell cultures grow more slowly than cyclin-D2-negative cultures, and induction of expression of cyclin D2 slows the culture growth rate of cyclin-D2-negative cells. Finally, subcutaneous murine xenografts of cyclin-D2-negative, p75NTR-positive PC12 cells more frequently and more rapidly produce tumors than the analogous xenografts of cyclin-D2-positive, p75NTR-negative cells. These results suggest that p75NTR suppresses cyclin D2 expression in PC12 cells by a mechanism distinct from its function as a nerve growth factor receptor and that cyclin D2 expression decreases cell culture and xenografted tumor growth

LOX-mediated collagen crosslinking is responsible for fibrosis-enhanced metastasis

DEFF Research Database (Denmark)

Cox, Thomas R; Bird, Demelza; Baker, Ann-Marie

2013-01-01

of metastastic tumor cells. We show that LOX-dependent collagen crosslinking is involved in creating a growth-permissive fibrotic microenvironment capable of supporting metastatic growth by enhancing tumor cell persistence and survival. We show that therapeutic targeting of LOX abrogates not only the extent...... to which fibrosis manifests, but also prevents fibrosis-enhanced metastatic colonization. Finally, we show that the LOX-mediated collagen crosslinking directly increases tumor cell proliferation, enhancing metastatic colonization and growth manifesting in vivo as increased metastasis. This is the first...... time that crosslinking of collagen I has been shown to enhance metastatic growth. These findings provide an important link between ECM homeostasis, fibrosis, and cancer with important clinical implications for both the treatment of fibrotic disease and cancer....

The p75{sup NTR} tumor suppressor induces cell cycle arrest facilitating caspase mediated apoptosis in prostate tumor cells

Energy Technology Data Exchange (ETDEWEB)

Khwaja, Fatima [Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057-1436 (United States); Tabassum, Arshia [Toronto Western Hospital, Toronto, ON, M5T258 (Canada); Allen, Jeff [National Center for Complementary and Alternative Medicine, N.I.H., Bethesda, MD 20892 (United States); Djakiew, Daniel [Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical Center, Washington, DC 20057-1436 (United States) and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057-1436 (United States)

2006-03-24

The p75 neurotrophin receptor (p75{sup NTR}) is a death receptor which belongs to the tumor necrosis factor receptor super-family of membrane proteins. This study shows that p75{sup NTR} retarded cell cycle progression by induced accumulation of cells in G0/G1 and a reduction in the S phase of the cell cycle. The rescue of tumor cells from cell cycle progression by a death domain deleted ({delta}DD) dominant-negative antagonist of p75{sup NTR} showed that the death domain transduced anti-proliferative activity in a ligand-independent manner. Conversely, addition of NGF ligand rescued retardation of cell cycle progression with commensurate changes in components of the cyclin/cdk holoenzyme complex. In the absence of ligand, p75{sup NTR}-dependent cell cycle arrest facilitated an increase in apoptotic nuclear fragmentation of the prostate cancer cells. Apoptosis of p75{sup NTR} expressing cells occurred via the intrinsic mitochondrial pathway leading to a sequential caspase-9 and -7 cascade. Since the death domain deleted dominant-negative antagonist of p75{sup NTR} rescued intrinsic caspase associated apoptosis in PC-3 cells, this shows p75{sup NTR} was integral to ligand independent induction of apoptosis. Moreover, the ability of ligand to ameliorate the p75{sup NTR}-dependent intrinsic apoptotic cascade indicates that NGF functioned as a survival factor for p75{sup NTR} expressing prostate cancer cells.

Design, synthesis, and biological evaluation of prenylated chalcones as 5-LOX inhibitors.

Science.gov (United States)

Reddy, Nimmanapalli P; Aparoy, Polamarasetty; Reddy, T Chandra Mohan; Achari, Chandrani; Sridhar, P Ramu; Reddanna, Pallu

2010-08-15

Ten novel mono- and di-O-prenylated chalcone derivatives were designed on the basis of a homology derived molecular model of 5-lipoxygenase (5-LOX). The compounds were docked into 5-LOX active site and the binding characteristics were quantified using LUDI. To verify our theoretical assumption, the molecules were synthesized and tested for their 5-LOX inhibitory activities. The synthesis was carried out by Claisen-Schmidt condensation reaction of mono- and di-O-prenylated acetophenones with appropriate aldehydes. 5-LOX in vitro inhibition assay showed higher potency of di-O-prenylated chalcones than their mono-O-prenylated chalcone analogs. Compound 5e exhibited good inhibition with an IC(50) at 4 microM. The overall trend for the binding energies calculated and LUDI score was in good qualitative agreement with the experimental data. Further, the compound 5e showed potent anti-proliferative effects (GI(50) at 9 microM) on breast cancer cell line, MCF-7. Copyright 2010 Elsevier Ltd. All rights reserved.

Northrop Grumman TR202 LOX/LH2 Deep Throttling Engine Technology Project Status

Science.gov (United States)

Gromski, Jason; Majamaki, Annik; Chianese, Silvio; Weinstock, Vladimir; Kim, Tony S.

2010-01-01

NASA's Propulsion and Cryogenic Advanced Development (PCAD) project is currently developing enabling propulsion technologies in support of future lander missions. To meet lander requirements, several technical challenges need to be overcome, one of which is the ability for the descent engine(s) to operate over a deep throttle range with cryogenic propellants. To address this need, PCAD has enlisted Northrop Grumman Aerospace Systems (NGAS) in a technology development effort associated with the TR202 engine. The TR202 is a LOX/LH2 expander cycle engine driven by independent turbopump assemblies and featuring a variable area pintle injector similar to the injector used on the TR200 Apollo Lunar Module Descent Engine (LMDE). Since the Apollo missions, NGAS has continued to mature deep throttling pintle injector technology. The TR202 program has completed two series of pintle injector testing. The first series of testing used ablative thrust chambers and demonstrated igniter operation as well as stable performance at discrete points throughout the designed 10:1 throttle range. The second series was conducted with calorimeter chambers and demonstrated injector performance at discrete points throughout the throttle range as well as chamber heat flow adequate to power an expander cycle design across the throttle range. This paper provides an overview of the TR202 program, describing the different phases and key milestones. It describes how test data was correlated to the engine conceptual design. The test data obtained has created a valuable database for deep throttling cryogenic pintle technology, a technology that is readily scalable in thrust level.

Final Report - Assessment of Testing Options for the NTR at the INL

Energy Technology Data Exchange (ETDEWEB)

Howe, Steven D; McLing, Travis L; McCurry, Michael; Plummer, Mitchell A

2013-02-01

One of the main technologies that can be developed to dramatically enhance the human exploration of space is the nuclear thermal rocket (NTR). Several studies over the past thirty years have shown that the NTR can reduce the cost of a lunar outpost, reduce the risk of a human mission to Mars, enable fast transits for most missions throughout the solar system, and reduce the cost and time for robotic probes to deep space. Three separate committees of the National Research Council of the National Academy of Sciences have recommended that NASA develop the NTR. One of the primary issues in development of the NTR is the ability to verify a flight ready unit. Three main methods can be used to validate safe operation of a NTR: 1) Full power, full duration test in an above ground facility that scrubs the rocket exhaust clean of any fission products; 2) Full power , full duration test using the Subsurface Active Filtering of Exhaust (SAFE) technique to capture the exhaust in subsurface strata; 3) Test of the reactor fuel at temperature and power density in a driver reactor with subsequent first test of the fully integrated NTR in space. The first method, the above ground facility, has been studied in the past. The second method, SAFE, has been examined for application at the Nevada Test Site. The third method relies on the fact that the Nuclear Furnace series of tests in 1971 showed that the radioactive exhaust coming from graphite based fuel for the NTR could be completely scrubbed of fission products and the clean hydrogen flared into the atmosphere. Under funding from the MSFC, the Center for Space Nuclear Research (CSNR) at the Idaho National laboratory (INL) has completed a reexamination of Methods 2 and 3 for implementation at the INL site. In short, the effort performed the following: 1) Assess the geology of the INL site and determine a location suitable SAFE testing; 2) Perform calculations of gas transport throughout the geology; 3) Produce a cost estimate of a

Activated human mast cells induce LOX-1-specific scavenger receptor expression in human monocyte-derived macrophages.

Directory of Open Access Journals (Sweden)

Mervi Alanne-Kinnunen

Full Text Available Activated mast cells in atherosclerotic lesions degranulate and release bioactive compounds capable of regulating atherogenesis. Here we examined the ability of activated human primary mast cells to regulate the expression of the major scavenger receptors in cultured human primary monocyte-derived macrophages (HMDMs.Components released by immunologically activated human primary mast cells induced a transient expression of lectin-like oxidized LDL receptor (LOX-1 mRNA in HMDMs, while the expression of two other scavenger receptors, MSR1 and CD36, remained unaffected. The LOX-1-inducing secretory components were identified as histamine, tumor necrosis factor alpha (TNF-α, and transforming growth factor beta (TGF-β1, which exhibited a synergistic effect on LOX-1 mRNA expression. Histamine induced a transient expression of LOX-1 protein. Mast cell -induced increase in LOX-1 expression was not associated with increased uptake of oxidized LDL by the macrophages.Mast cell-derived histamine, TNF-α, and TGF-β1 act in concert to induce a transient increase in LOX-1 expression in human primary monocyte-derived macrophages. The LOX-1-inducing activity potentially endows mast cells a hitherto unrecognized role in the regulation of innate immune reactions in atherogenesis.

Carprofen induction of p75NTR-dependent apoptosis via the p38 mitogen-activated protein kinase pathway in prostate cancer cells.

Science.gov (United States)

Khwaja, Fatima S; Quann, Emily J; Pattabiraman, Nagarajan; Wynne, Shehla; Djakiew, Daniel

2008-11-01

The p75 neurotrophin receptor (p75(NTR)) functions as a tumor suppressor in prostate epithelial cells, where its expression declines with progression to malignant cancer. Previously, we showed that treatment with R-flurbiprofen or ibuprofen induced p75(NTR) expression in several prostate cancer cell lines leading to p75(NTR)-mediated decreased survival. Using the 2-phenyl propionic acid moiety of these profens as a pharmacophore, we screened an in silico database of 30 million compounds and identified carprofen as having an order of magnitude greater activity for induction of p75(NTR) levels and inhibition of cell survival. Prostate (PC-3 and DU-145) and bladder (T24) cancer cells were more sensitive to carprofen induction of p75(NTR)-associated loss of survival than breast (MCF-7) and fibroblast (3T3) cells. Transfection of prostate cell lines with a dominant-negative form of p75(NTR) before carprofen treatment partially rescued cell survival, showing a cause-and-effect relationship between carprofen induction of p75(NTR) levels and inhibition of survival. Carprofen induced apoptotic nuclear fragmentation in prostate but not in MCF-7 and 3T3 cells. Furthermore, small interfering RNA knockdown of the p38 mitogen-activated protein kinase (MAPK) protein prevented induction of p75(NTR) by carprofen in both prostate cell lines. Carprofen treatment induced phosphorylation of p38 MAPK as early as within 1 min. Expression of a dominant-negative form of MK2, the kinase downstream of p38 MAPK frequently associated with signaling cascades leading to apoptosis, prevented carprofen induction of the p75(NTR) protein. Collectively, we identify carprofen as a highly potent profen capable of inducing p75(NTR)-dependent apoptosis via the p38 MAPK pathway in prostate cancer cells.

Silencing p75NTR prevents proNGF-induced endothelial cell death and development of acellular capillaries in rat retina

Directory of Open Access Journals (Sweden)

Ahmed Y Shanab

Full Text Available Accumulation of the nerve growth factor precursor (proNGF and its receptor p75NTR have been associated with several neurodegenerative diseases in both brain and retina. However, whether proNGF contributes to microvascular degeneration remain unexplored. This study seeks to investigate the mechanism by which proNGF/p75NTR induce endothelial cell (EC death and development of acellular capillaries, a surrogate marker of retinal ischemia. Stable overexpression of the cleavage-resistant proNGF and molecular silencing of p75NTR were utilized in human retinal EC and rat retinas in vivo. Stable overexpression of proNGF decreased NGF levels and induced retinal vascular cell death evident by 1.9-fold increase in acellular capillaries and activation of JNK and cleaved-PARP that were mitigated by p75NTRshRNA. In vitro, overexpression of proNGF did not alter TNF-α level, reduced NGF, however induced EC apoptosis evident by activation of JNK and p38 MAPK, cleaved-PARP. Silencing p75NTR using siRNA restored expression of NGF and TrkA activation and prevented EC apoptosis. Treatment of EC with human-mutant proNGF induced apoptosis that coincided with marked protein interaction and nuclear translocation of p75NTR and the neurotrophin receptor interacting factor. These effects were abolished by a selective p75NTR antagonist. Therefore, targeting p75NTR represents a potential therapeutic strategy for diseases associated with aberrant expression of proNGF.

Stirling engine electric hybrid vehicle propulsion system conceptual design study. Final report

Energy Technology Data Exchange (ETDEWEB)

Dochat, G; Artiles, A; Killough, J; Ray, A; Chen, H S

1978-08-01

Results of a six-month study to characterize a series Stirling engine electric hybrid vehicle propulsion system are presented. The Stirling engine was selected as the heat conversion element to exploit the high efficiency (> .36), low pollution, multi-fuel and quiet operation of this machine. A free-piston Stirling engine driving a linear alternator in a hermatically sealed enclosure was chosen to gain the reliability, long life, and maintenance free characteristics of a sealed unit. The study performs trade off evaluations, selection of engine, battery, motor and inverter size, optimization of components, and develops a conceptual design and characterization of the total propulsion system. The conclusion of the study is that a Stirling engine electric hybrid propulsion system can be used successfully to augment the battery storage of a passenger vehicle and will result in significant savings of petroleum energy over present passenger vehicles. The performance and range augmentation of the hybrid design results in significant improvements over an all electric vehicle. The hybrid will be capable of performing 99% of the passenger vehicle annual trip distribution requirements with extremely low fuel usage. (TFD)

The transcriptional regulator NtrC controls glucose-6-phosphate dehydrogenase expression and polyhydroxybutyrate synthesis through NADPH availability in Herbaspirillum seropedicae.

Science.gov (United States)

Sacomboio, Euclides Nenga Manuel; Kim, Edson Yu Sin; Correa, Henrique Leonardo Ruchaud; Bonato, Paloma; Pedrosa, Fabio de Oliveira; de Souza, Emanuel Maltempi; Chubatsu, Leda Satie; Müller-Santos, Marcelo

2017-10-19

The NTR system is the major regulator of nitrogen metabolism in Bacteria. Despite its broad and well-known role in the assimilation, biosynthesis and recycling of nitrogenous molecules, little is known about its role in carbon metabolism. In this work, we present a new facet of the NTR system in the control of NADPH concentration and the biosynthesis of molecules dependent on reduced coenzyme in Herbaspirillum seropedicae SmR1. We demonstrated that a ntrC mutant strain accumulated high levels of polyhydroxybutyrate (PHB), reaching levels up to 2-fold higher than the parental strain. In the absence of NtrC, the activity of glucose-6-phosphate dehydrogenase (encoded by zwf) increased by 2.8-fold, consequently leading to a 2.1-fold increase in the NADPH/NADP + ratio. A GFP fusion showed that expression of zwf is likewise controlled by NtrC. The increase in NADPH availability stimulated the production of polyhydroxybutyrate regardless the C/N ratio in the medium. The mutant ntrC was more resistant to H 2 O 2 exposure and controlled the propagation of ROS when facing the oxidative condition, a phenotype associated with the increase in PHB content.

Affordable Development and Demonstration of a Small NTR Engine and Stage: How Small is Big Enough?

Science.gov (United States)

Borowski, Stanley K.; Sefcik, Robert J.; Fittje, James E.; McCurdy, David R.; Qualls, Arthur L.; Schnitzler, Bruce G.; Werner, James E.; Weitzberg (Abraham); Joyner, Claude R.

2015-01-01

The Nuclear Thermal Rocket (NTR) derives its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core. It generates high thrust and has a specific impulse potential of approximately 900 seconds - a 100% increase over today's best chemical rockets. The Nuclear Thermal Propulsion (NTP) project, funded by NASA's AES program, includes five key task activities: (1) Recapture, demonstration, and validation of heritage graphite composite (GC) fuel (selected as the "Lead Fuel" option); (2) Engine Conceptual Design; (3) Operating Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable Development Strategy. During FY'14, a preliminary DDT&E plan and schedule for NTP development was outlined by GRC, DOE and industry that involved significant system-level demonstration projects that included GTD tests at the NNSS, followed by a FTD mission. To reduce cost for the GTD tests and FTD mission, small NTR engines, in either the 7.5 or 16.5 klbf thrust class, were considered. Both engine options used GC fuel and a "common" fuel element (FE) design. The small approximately 7.5 klbf "criticality-limited" engine produces approximately 157 megawatts of thermal power (MWt) and its core is configured with parallel rows of hexagonal-shaped FEs and tie tubes (TTs) with a FE to TT ratio of approximately 1:1. The larger approximately 16.5 klbf Small Nuclear Rocket Engine (SNRE), developed by LANL at the end of the Rover program, produces approximately 367 MWt and has a FE to TT ratio of approximately 2:1. Although both engines use a common 35 inch (approximately 89 cm) long FE, the SNRE's larger diameter core contains approximately 300 more FEs needed to produce an additional 210 MWt of power. To reduce the cost of the FTD mission, a simple "1-burn" lunar flyby mission was considered to reduce the LH2 propellant loading, the stage size and complexity. Use of existing and

Affordable Development and Demonstration of a Small NTR Engine and Stage: A Preliminary NASA, DOE, and Industry Assessment

Science.gov (United States)

Borowski, Stanley K.; Sefcik, Robert J.; Fittje, James E.; McCurdy, David R.; Qualls, Arthur L.; Schnitzler, Bruce G.; Werner, James E.; Weitzberg, Abraham; Joyner, Claude R.

2015-01-01

The Nuclear Thermal Rocket (NTR) represents the next evolutionary step in cryogenic liquid rocket engines. Deriving its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core, the NTR can generate high thrust at a specific impulse of approx. 900 seconds or more - twice that of today's best chemical rockets. In FY'11, as part of the AISP project, NASA proposed a Nuclear Thermal Propulsion (NTP) effort that envisioned two key activities - "Foundational Technology Development" followed by system-level "Technology Demonstrations". Five near-term NTP activities identified for Foundational Technology Development became the basis for the NCPS project started in FY'12 and funded by NASA's AES program. During Phase 1 (FY'12-14), the NCPS project was focused on (1) Recapturing fuel processing techniques and fabricating partial length "heritage" fuel elements for the two candidate fuel forms identified by NASA and the DOE - NERVA graphite "composite" and the uranium dioxide (UO2) in tungsten "cermet". The Phase 1 effort also included: (2) Engine Conceptual Design; (3) Mission Analysis and Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable and Sustainable NTP Development Strategy. During FY'14, a preliminary plan for DDT&E was outlined by GRC, the DOE and industry for NASA HQ that involved significant system-level demonstration projects that included GTD tests at the NNSS, followed by a FTD mission. To reduce development costs, the GTD and FTD tests use a small, low thrust (approx. 7.5 or 16.5 klbf) engine. Both engines use graphite composite fuel and a "common" fuel element design that is scalable to higher thrust (approx. 25 klbf) engines by increasing the number of elements in a larger diameter core that can produce greater thermal power output. To keep the FTD mission cost down, a simple "1-burn" lunar flyby mission was considered along with

The p75NTR mediates a bifurcated signal transduction cascade through the NFκB and JNK pathways to inhibit cell survival

International Nuclear Information System (INIS)

Allen, Jeffrey; Khwaja, Fatima; Byers, Stephen; Djakiew, Daniel

2005-01-01

p75 NTR is most abundantly expressed in the nervous system, but is also widely expressed in many other organs and tissues where it primarily functions as a negative regulator of cell survival. In the prostate, p75 NTR functions as an inhibitory protein capable of slowing proliferation and inducing apoptosis. It has been shown that p75 NTR is expressed in the normal prostate, progressively lost from malignant tumor cells in vivo, and largely absent from prostate cancer cell lines derived from metastases. Although the role of p75 NTR in prostate cancer has been well established, the signal transduction pathway that mediates its inhibitory activity has only been partially elucidated. This study demonstrates that exogenous expression of p75 NTR down-regulates, in a dose-dependent manner, a bifurcated signaling cascade that results in reduced expression of potent transcription effectors. This two-arm signal transduction cascade was directly linked to the upstream receptor by using dominant-negative deletion constructs of p75 NTR that rescued tumor cells from p75 NTR -induced loss of survival and promotion of apoptosis. Furthermore, the dominant negatives rescued alterations in the levels of signal transduction intermediates. Conversely, the use of kinase-inactive intermediates that are downstream of the receptor further reduced expression of involved transcription effectors and reduced survival of the cells. These results provide a definitive link between the proximate p75 NTR and signal transduction intermediates leading to the transcription effectors NFκB and JNK, with associated growth suppression and induction of apoptosis

Numerical analysis of flow and heat transfer in the VAFB LOX storage Dewar tank

Science.gov (United States)

Tam, L. T.; Singhal, A. K.

1984-01-01

The present report describes numerical simulation of three-dimensional transient distributions of velocity and temperature of liquid oxygen (LOX) in the LOX Dewar tank of Vendenberg Air Force Base (VAFB). The present analyses cover the replenish time period only. Four test cases have been considered. For all four cases, the input boundary conditions are comprised of LOX facility heat loads, drain flow rates, recirculation flow rates and dewar heating. All the quantities are prescribed as functions of time. The first two test cases considered sensitivity of results to the computational grid. In Case 3, system heat load was changed, while in Case 4, a lower LOX level was specified. Cases 1 and 2 showed that the temperatures were not sensitive to the grid refinement. This provided a basic check on the numerical model. Cases 3 and 4 showed that the thermal boundary layer motion near the tank surface becomes more significant at the late time, e.g., 5 1/2 hours from replenish start. Comparison between results of Cases 3 and 4 showed, as expected, that the smaller initial LOX volume given in Case 4, results in higher temperature level. All calculated velocity and temperature distributions were found to be plausible.

Systematic analysis of rat 12/15-lipoxygenase enzymes reveals critical role for spinal eLOX3 hepoxilin synthase activity in inflammatory hyperalgesia.

Science.gov (United States)

Gregus, Ann M; Dumlao, Darren S; Wei, Spencer C; Norris, Paul C; Catella, Laura C; Meyerstein, Flore G; Buczynski, Matthew W; Steinauer, Joanne J; Fitzsimmons, Bethany L; Yaksh, Tony L; Dennis, Edward A

2013-05-01

Previously, we observed significant increases in spinal 12-lipoxygenase (LOX) metabolites, in particular, hepoxilins, which contribute to peripheral inflammation-induced tactile allodynia. However, the enzymatic sources of hepoxilin synthase (HXS) activity in rats remain elusive. Therefore, we overexpressed each of the 6 rat 12/15-LOX enzymes in HEK-293T cells and measured by LC-MS/MS the formation of HXB3, 12-HETE, 8-HETE, and 15-HETE from arachidonic acid (AA) at baseline and in the presence of LOX inhibitors (NDGA, AA-861, CDC, baicalein, and PD146176) vs. vehicle-treated and mock-transfected controls. We detected the following primary intrinsic activities: 12-LOX (Alox12, Alox15), 15-LOX (Alox15b), and HXS (Alox12, Alox15). Similar to human and mouse orthologs, proteins encoded by rat Alox12b and Alox12e possessed minimal 12-LOX activity with AA as substrate, while eLOX3 (encoded by Aloxe3) exhibited HXS without 12-LOX activity when coexpressed with Alox12b or supplemented with 12-HpETE. CDC potently inhibited HXS and 12-LOX activity in vitro (relative IC50s: CDC, ~0.5 and 0.8 μM, respectively) and carrageenan-evoked tactile allodynia in vivo. Notably, peripheral inflammation significantly increased spinal eLOX3; intrathecal pretreatment with either siRNA targeting Aloxe3 or an eLOX3-selective antibody attenuated the associated allodynia. These findings implicate spinal eLOX3-mediated hepoxilin synthesis in inflammatory hyperesthesia and underscore the importance of developing more selective 12-LOX/HXS inhibitors.

Preliminary Assessment of Using Gelled and Hybrid Propellant Propulsion for VTOL/SSTO Launch Systems

Science.gov (United States)

Palaszewski, Bryan; OLeary, Robert; Pelaccio, Dennis G.

1998-01-01

A novel, reusable, Vertical-Takeoff-and-Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit (VTOL/SSTO) launch system concept, named AUGMENT-SSTO, is presented in this paper to help quantify the advantages of employing gelled and hybrid propellant propulsion system options for such applications. The launch vehicle system concept considered uses a highly coupled, main high performance liquid oxygen/liquid hydrogen (LO2/LH2) propulsion system, that is used only for launch, while a gelled or hybrid propellant propulsion system auxiliary propulsion system is used during final orbit insertion, major orbit maneuvering, and landing propulsive burn phases of flight. Using a gelled or hybrid propellant propulsion system for major orbit maneuver burns and landing has many advantages over conventional VTOL/SSTO concepts that use LO2/LH2 propulsion system(s) burns for all phases of flight. The applicability of three gelled propellant systems, O2/H2/Al, O2/RP-1/Al, and NTO/MMH/Al, and a state-of-the-art (SOA) hybrid propulsion system are examined in this study. Additionally, this paper addresses the applicability of a high performance gelled O2/H2 propulsion system to perform the primary, as well as the auxiliary propulsion system functions of the vehicle.

Anomalous baroreflex functionality inherent in floxed and Cre-Lox mice: an overlooked physiological phenotype.

Science.gov (United States)

Tsai, Ching-Yi; Poon, Yan-Yuen; Chen, Chang-Han; Chan, Samuel H H

2017-10-01

The last two decades have seen the emergence of Cre-Lox recombination as one of the most powerful and versatile technologies for cell-specific genetic engineering of mammalian cells. Understandably, the primary concerns in the practice of Cre-Lox recombination are whether the predicted genome has been correctly modified and the targeted phenotypes expressed. Rarely are the physiological conditions of the animals routinely examined because the general assumption is that they are normal. Based on corroborative results from radiotelemetric recording, power spectral analysis, and magnetic resonance imaging/diffusion tensor imaging in brain-derived neurotrophic factor-floxed mice, the present study revealed that this assumption requires amendment. We found that despite comparable blood pressure and heart rate with C57BL/6 or Cre mice under the conscious state, floxed and Cre-Lox mice exhibited diminished baroreflex-mediated sympathetic vasomotor tone and cardiac vagal baroreflex. We further found that the capacity and plasticity of baroreflex of these two strains of mice under isoflurane anesthesia were retarded, as reflected by reduced connectivity between the nucleus tractus solitarii and rostral ventrolateral medulla or nucleus ambiguus. The identification of anomalous baroreflex functionality inherent in floxed and Cre-Lox mice points to the importance of incorporating physiological phenotypes into studies that engage gene manipulations such as Cre-Lox recombination. NEW & NOTEWORTHY We established that anomalous baroreflex functionality is inherent in floxed and Cre-Lox mice. These two mouse strains exhibited diminished baroreflex-mediated sympathetic vasomotor tone and cardiac vagal baroreflex under the conscious state, retarded capacity and plasticity of baroreflex under isoflurane anesthesia, and reduced connectivity between key nuclei in the baroreflex neural circuits. Copyright © 2017 the American Physiological Society.

Combustion chamber heat transfer characterization of LOX/hydrocarbon-type propellants

Science.gov (United States)

Schoenman, Leonard

1987-01-01

The gas-side heat transfer rates for LOX/propane and LOX/ethanol are experimentally characterized using a 1000 lb thrust water-cooled calorimeter chamber. The effects of injector element type and fuel film cooling are defined as a function of mixture ratio. The interaction of fuel injected through the resonator cavities on heat transfer and wall soot buildup are displayed as a function of time, axial distance, fuel coolant flow rate, and mixture ratio. Comparisons between clean-burning ethanol and sooting propane show a large difference between the two fuels and significantly higher than expected heat flux levels for ethanol in the throat region.

Ground Testing a Nuclear Thermal Rocket: Design of a sub-scale demonstration experiment

Energy Technology Data Exchange (ETDEWEB)

David Bedsun; Debra Lee; Margaret Townsend; Clay A. Cooper; Jennifer Chapman; Ronald Samborsky; Mel Bulman; Daniel Brasuell; Stanley K. Borowski

2012-07-01

In 2008, the NASA Mars Architecture Team found that the Nuclear Thermal Rocket (NTR) was the preferred propulsion system out of all the combinations of chemical propulsion, solar electric, nuclear electric, aerobrake, and NTR studied. Recently, the National Research Council committee reviewing the NASA Technology Roadmaps recommended the NTR as one of the top 16 technologies that should be pursued by NASA. One of the main issues with developing a NTR for future missions is the ability to economically test the full system on the ground. In the late 1990s, the Sub-surface Active Filtering of Exhaust (SAFE) concept was first proposed by Howe as a method to test NTRs at full power and full duration. The concept relied on firing the NTR into one of the test holes at the Nevada Test Site which had been constructed to test nuclear weapons. In 2011, the cost of testing a NTR and the cost of performing a proof of concept experiment were evaluated.

Involvement of PLA2, COX and LOX in Rhinella arenarum oocyte maturation.

Science.gov (United States)

Ortiz, Maria Eugenia; Bühler, Marta Inés; Zelarayán, Liliana Isabel

2014-11-01

In Rhinella arenarum, progesterone is the physiological nuclear maturation inducer that interacts with the oocyte surface and starts a cascade of events that leads to germinal vesicle breakdown (GVBD). Polyunsaturated fatty acids and their metabolites produced through cyclooxygenase (COX) and lipoxygenase (LOX) pathways play an important role in reproductive processes. In amphibians, to date, the role of arachidonic acid (AA) metabolites in progesterone (P4)-induced oocyte maturation has not been clarified. In this work we studied the participation of three enzymes involved in AA metabolism - phospholipase A2 (PLA2), COX and LOX in Rhinella arenarum oocyte maturation. PLA2 activation induced maturation in Rhinella arenarum oocytes in a dose-dependent manner. Oocytes when treated with 0.08 μM melittin showed the highest response (78 ± 6% GVBD). In follicles, PLA2 activation did not significantly induce maturation at the assayed doses (12 ± 3% GVBD). PLA2 inhibition with quinacrine prevented melittin-induced GVBD in a dose-dependent manner, however PLA2 inactivation did not affect P4-induced maturation. This finding suggests that PLA2 is not the only phospholipase involved in P4-induced maturation in this species. P4-induced oocyte maturation was inhibited by the COX inhibitors indomethacin and rofecoxib (65 ± 3% and 63 ± 3% GVBD, respectively), although COX activity was never blocked by their addition. Follicles showed a similar response following the addition of these inhibitors. Participation of LOX metabolites in maturation seems to be correlated with seasonal variation in ovarian response to P4. During the February to June period (low P4 response), LOX inhibition by nordihydroguaiaretic acid or lysine clonixinate increased maturation by up to 70%. In contrast, during the July to January period (high P4 response), LOX inhibition had no effect on hormone-induced maturation.

The Role of Neurotrophin Signaling in Gliomagenesis: A Focus on the p75 Neurotrophin Receptor (p75NTR/CD271).

Science.gov (United States)

Alshehri, M M; Robbins, S M; Senger, D L

2017-01-01

The p75 neurotrophin receptor (p75 NTR , a.k.a. CD271), a transmembrane glycoprotein and a member of the tumor necrosis family (TNF) of receptors, was originally identified as a nerve growth factor receptor in the mid-1980s. While p75 NTR is recognized to have important roles during neural development, its presence in both neural and nonneural tissues clearly supports the potential to mediate a broad range of functions depending on cellular context. Using an unbiased in vivo selection paradigm for genes underlying the invasive behavior of glioma, a critical characteristic that contributes to poor clinical outcome for glioma patients, we identified p75 NTR as a central regulator of glioma invasion. Herein we review the expanding role that p75 NTR plays in glioma progression with an emphasis on how p75 NTR may contribute to the treatment refractory nature of glioma. Based on the observation that p75 NTR is expressed and functional in two critical glioma disease reservoirs, namely, the highly infiltrative cells that evade surgical resection, and the radiation- and chemotherapy-resistant brain tumor-initiating cells (also referred to as brain tumor stem cells), we propose that p75 NTR and its myriad of downstream signaling effectors represent rationale therapeutic targets for this devastating disease. Lastly, we provide the provocative hypothesis that, in addition to the well-documented cell autonomous signaling functions, the neurotrophins, and their respective receptors, contribute in a cell nonautonomous manner to drive the complex cellular and molecular composition of the brain tumor microenvironment, an environment that fuels tumorigenesis. © 2017 Elsevier Inc. All rights reserved.

Subconjunctival Delivery of p75NTR Antagonists Reduces the Inflammatory, Vascular, and Neurodegenerative Pathologies of Diabetic Retinopathy.

Science.gov (United States)

Galan, Alba; Barcelona, Pablo F; Nedev, Hinyu; Sarunic, Marinko V; Jian, Yifan; Saragovi, H Uri

2017-06-01

The p75NTR is a novel therapeutic target validated in a streptozotocin mouse model of diabetic retinopathy. Intravitreal (IVT) injection of small molecule p75NTR antagonist THX-B was therapeutic and resolved the inflammatory, vascular, and neurodegenerative phases of the retinal pathology. To simplify clinical translation, we sought a superior drug delivery method that circumvents risks associated with IVT injections. We compared the pharmacokinetics of a single 40 μg subconjunctival (SCJ) depot to the reported effective 5 μg IVT injections of THX-B. We quantified therapeutic efficacy, with endpoints of inflammation, edema, and neuronal death. The subconjunctival depot affords retinal exposure equal to IVT injection, without resulting in detectable drug in circulation. At week 2 of diabetic retinopathy, the SCJ depot provided therapeutic efficacy similar to IVT injections, with reduced inflammation, reduced edema, reduced neuronal death, and a long-lasting protection of the retinal structure. Subconjunctival injections are a safe and effective route for retinal delivery of p75NTR antagonists. The subconjunctival route offers an advantageous, less-invasive, more compliant, and nonsystemic method to deliver p75NTR antagonists for the treatment of retinal diseases.

Cloning-free genome engineering in Sinorhizobium meliloti advances applications of Cre/loxP site-specific recombination.

Science.gov (United States)

Döhlemann, Johannes; Brennecke, Meike; Becker, Anke

2016-09-10

The soil-dwelling α-proteobacterium Sinorhizobium meliloti serves as model for studies of symbiotic nitrogen fixation, a highly important process in sustainable agriculture. Here, we report advancements of the genetic toolbox accelerating genome editing in S. meliloti. The hsdMSR operon encodes a type-I restriction-modification (R-M) system. Transformation of S. meliloti is counteracted by the restriction endonuclease HsdR degrading DNA which lacks the appropriate methylation pattern. We provide a stable S. meliloti hsdR deletion mutant showing enhanced transformation with Escherichia coli-derived plasmid DNA and demonstrate that using an E. coli plasmid donor, expressing S. meliloti methyl transferase genes, is an alternative strategy of increasing the transformation efficiency of S. meliloti. Furthermore, we devise a novel cloning-free genome editing (CFGE) method for S. meliloti, Agrobacterium tumefaciens and Xanthomonas campestris, and demonstrate the applicability of this method for intricate applications of the Cre/lox recombination system in S. meliloti. An enhanced Cre/lox system, allowing for serial deletions of large genomic regions, was established. An assay of lox spacer mutants identified a set of lox sites mediating specific recombination. The availability of several non-promiscuous Cre recognition sites enables simultaneous specific Cre/lox recombination events. CFGE combined with Cre/lox recombination is put forward as powerful approach for targeted genome editing, involving serial steps of manipulation to expedite the genetic accessibility of S. meliloti as chassis. Copyright © 2016 Elsevier B.V. All rights reserved.

Role of the mitochondria in immune-mediated apoptotic death of the human pancreatic β cell line βLox5.

Directory of Open Access Journals (Sweden)

Yaíma L Lightfoot

Full Text Available Mitochondria are indispensable in the life and death of many types of eukaryotic cells. In pancreatic beta cells, mitochondria play an essential role in the secretion of insulin, a hormone that regulates blood glucose levels. Unregulated blood glucose is a hallmark symptom of diabetes. The onset of Type 1 diabetes is preceded by autoimmune-mediated destruction of beta cells. However, the exact role of mitochondria has not been assessed in beta cell death. In this study, we examine the role of mitochondria in both Fas- and proinflammatory cytokine-mediated destruction of the human beta cell line, βLox5. IFNγ primed βLox5 cells for apoptosis by elevating cell surface Fas. Consequently, βLox5 cells were killed by caspase-dependent apoptosis by agonistic activation of Fas, but only after priming with IFNγ. This beta cell line undergoes both apoptotic and necrotic cell death after incubation with the combination of the proinflammatory cytokines IFNγ and TNFα. Additionally, both caspase-dependent and -independent mechanisms that require proper mitochondrial function are involved. Mitochondrial contributions to βLox5 cell death were analyzed using mitochondrial DNA (mtDNA depleted βLox5 cells, or βLox5 ρ(0 cells. βLox5 ρ(0 cells are not sensitive to IFNγ and TNFα killing, indicating a direct role for the mitochondria in cytokine-induced cell death of the parental cell line. However, βLox5 ρ(0 cells are susceptible to Fas killing, implicating caspase-dependent extrinsic apoptotic death is the mechanism by which these human beta cells die after Fas ligation. These data support the hypothesis that immune mediators kill βLox5 cells by both mitochondrial-dependent intrinsic and caspase-dependent extrinsic pathways.

Preliminary Thermohydraulic Analysis of a New Moderated Reactor Utilizing an LEU-Fuel for Space Nuclear Thermal Propulsion

International Nuclear Information System (INIS)

Nam, Seung Hyun; Choi, Jae Young; Venneria, Paolo F.; Jeong, Yong Hoon; Chang, Soon Heung

2015-01-01

The Korea Advanced NUclear Thermal Engine Rocket utilizing an LEU fuel (KANUTER-LEU) is a non-proliferative and comparably efficient NTR engine with relatively low thrust levels of 40 - 50 kN for in-space transportation. The small modular engine can expand mission versatility, when flexibly used in a clustered engine arrangement, so that it can perform various scale missions from low-thrust robotic science missions to high-thrust manned missions. In addition, the clustered engine system can enhance engine redundancy and ensuing crew safety as well as the thrust. The propulsion system is an energy conversion system to transform the thermal energy of the reactor into the kinetic energy of the propellant to produce the powers for thrust, propellant feeding and electricity. It is mainly made up of a propellant Feeding System (PFS) comprising a Turbo-Pump Assembly (TPA), a Regenerative Nozzle Assembly (RNA), etc. For this core design study, an expander cycle is assumed to be the propulsion system. The EGS converts the thermal energy of the EHTGR in the idle operation (only 350 kW th power) to electric power during the electric power mode. This paper presents a preliminary thermohydraulic design analysis to explore the design space for the new reactor and to estimate the referential engine performance. The new non-proliferative NTR engine concept, KANUTER-LEU, is under designing to surmount the nuclear proliferation obstacles on allR and Dactivities and eventual commercialization for future generations. To efficiently implement a heavy LEU fuel for the NTR engine, its reactor design innovatively possesses the key characteristics of the high U density fuel with high heating and H 2 corrosion resistances, the thermal neutron spectrum core and also minimizing non-fission neutron loss, and the compact reactor design with protectively cooling capability. To investigate feasible design space for the moderated EHTGR-LEU and resultant engine performance, the preliminary design

The rationale for targeting the LOX family in cancer

DEFF Research Database (Denmark)

Barker, Holly E; Cox, Thomas R; Erler, Janine T

2012-01-01

The therapeutic targeting of extracellular proteins is becoming hugely attractive in light of evidence implicating the tumour microenvironment as pivotal in all aspects of tumour initiation and progression. Members of the lysyl oxidase (LOX) family of proteins are secreted by tumours and are the ......The therapeutic targeting of extracellular proteins is becoming hugely attractive in light of evidence implicating the tumour microenvironment as pivotal in all aspects of tumour initiation and progression. Members of the lysyl oxidase (LOX) family of proteins are secreted by tumours...... and are the subject of much effort to understand their roles in cancer. In this Review we discuss the roles of members of this family in the remodelling of the tumour microenvironment and their paradoxical roles in tumorigenesis and metastasis. We also discuss how targeting this family of proteins might lead to a new...... avenue of cancer therapeutics....

Neurotrophin Receptors TrkA, p75NTR, and Sortilin Are Increased and Targetable in Thyroid Cancer.

Science.gov (United States)

Faulkner, Sam; Jobling, Philip; Rowe, Christopher W; Rodrigues Oliveira, S M; Roselli, Severine; Thorne, Rick F; Oldmeadow, Christopher; Attia, John; Jiang, Chen Chen; Zhang, Xu Dong; Walker, Marjorie M; Hondermarck, Hubert

2018-01-01

Neurotrophin receptors are emerging targets in oncology, but their clinicopathologic significance in thyroid cancer is unclear. In this study, the neurotrophin tyrosine receptor kinase TrkA (also called NTRK1), the common neurotrophin receptor p75 NTR , and the proneurotrophin receptor sortilin were analyzed with immunohistochemistry in a cohort of thyroid cancers (n = 128) and compared with adenomas and normal thyroid tissues (n = 62). TrkA was detected in 20% of thyroid cancers, compared with none of the benign samples (P = 0.0007). TrkA expression was independent of histologic subtypes but associated with lymph node metastasis (P = 0.0148), suggesting the involvement of TrkA in tumor invasiveness. Nerves in the tumor microenvironment were positive for TrkA. p75 NTR was overexpressed in anaplastic thyroid cancers compared with papillary and follicular subtypes (P Neurotrophin receptor expression was confirmed in a panel of thyroid cancer cell lines at the mRNA and protein levels. Functional investigations using the anaplastic thyroid cancer cell line CAL-62 found that siRNA against TrkA, p75 NTR , and sortilin decreased cell survival and cell migration through decreased SRC and ERK activation. Together, these data reveal TrkA, p75 NTR , and sortilin as potential therapeutic targets in thyroid cancer. Copyright © 2018 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Summary of LOX/CH4 Thruster Technology Development at NASA/MSFC

Science.gov (United States)

Greene, Sandra Elam

2015-01-01

In recent years, a variety of injectors for liquid oxygen (LOX) and methane (CH4) propellant systems have been designed, fabricated, and demonstrated with hot-fire testing at Marshall Space Flight Center (MSFC). Successful designs for liquid methane (LCH4) and gaseous methane (GCH4) have been developed. A variety of chambers, including a transpiration cooled design, along with uncooled ablatives and refractory metals, have also been hot-fire tested by MSFC for use with LOX/LCH4 injectors. Hot-fire testing has also demonstrated multiple ignition source options. Heat flux data for selected injectors has been gathered by testing with a calorimeter chamber. High performance and stable combustion have been demonstrated, along with designs for thrust levels ranging from 500 to 7,000 lbf. The newest LOX/CH4 injector and chamber developed by MSFC have been fabricated with additive manufacturing techniques and include unique design features to investigate regenerative cooling with methane. This low cost and versatile hardware offers a design for 4,000 lbf thrust and will be hot-fire tested at MSFC in 2015. Its design and operation can easily be scaled for use in systems with thrust levels up to 25,000 lbf.

Northrop Grumman TR202 LOX/LH2 Deep Throttling Engine Project Status

Science.gov (United States)

Gromski, J.; Majamaki, A. N.; Chianese, S. G.; Weinstock, V. D.; Kim, T.

2010-01-01

NASA's Propulsion and Cryogenic Advanced Development (PCAD) project is currently developing enabling propulsion technologies in support of the Exploration Initiative, with a particular focus on the needs of the Altair Project. To meet Altair requirements, several technical challenges need to be overcome, one of which is the ability for the lunar descent engine(s) to operate over a deep throttle range with cryogenic propellants. To address this need, PCAD has enlisted Northrop Grumman Aerospace Systems (NGAS) in a technology development effort associated with the TR202, a LOX/LH2 expander cycle engine driven by independent turbopump assemblies and featuring a variable area pintle injector similar to the injector used on the TR200 Apollo Lunar Module Descent Engine (LMDE). Since the Apollo missions, NGAS has continued to mature deep throttling pintle injector technology. The TR202 program has completed two phases of pintle injector testing. The first phase of testing used ablative thrust chambers and demonstrated igniter operation as well as stable performance at several power levels across the designed 10:1 throttle range. The second phase of testing was performed on a calorimeter chamber and demonstrated injector performance at various power levels (75%, 50%, 25%, 10%, and 7.5%) across the throttle range as well as chamber heat flux to show that the engine can close an expander cycle design across the throttle range. This paper provides an overview of the TR202 program. It describes the different phases of the program with the key milestones of each phase. It then shows when those milestones were met. Next, it describes how the test data was used to update the conceptual design and how the test data has created a database for deep throttling cryogenic pintle technology that is readily scaleable and can be used to again update the design once the Altair program's requirements are firm. The final section of the paper describes the path forward, which includes

Co-induction of p75(NTR) and the associated death executor NADE in degenerating hippocampal neurons after kainate-induced seizures in the rat.

Science.gov (United States)

Yi, Jung-Sun; Lee, Soon-Keum; Sato, Taka-Aki; Koh, Jae-Young

2003-08-21

Zinc induces in cultured cortical neurons both p75(NTR) and p75(NTR)-associated death executor (NADE), which together contribute to caspase-dependent neuronal apoptosis. Since zinc neurotoxicity may contribute to neuronal death following seizures, we examined whether p75(NTR) and NADE are co-induced also in rat hippocampal neurons degenerating after seizures. Staining of brain sections with a zinc-specific fluorescent dye (N-(6-methoxy-8-quinolyl)-p-carboxybenzoylsulphonamide) and acid fuchsin revealed zinc accumulation in degenerating neuronal cell bodies in CA1 and CA3 of hippocampus 24 h after kainate injection. Both anti-p75(NTR) and anti-NADE immunoreactivities appeared in zinc-accumulating/degenerating neurons in both areas. Intraventricular injection of CaEDTA, without altering the severity or time course of kainate-induced seizures, markedly attenuated the induction of p75(NTR)/NADE in hippocampus, which correlated with the decrease of caspase-3 activation and zinc accumulation/cell death. The present study has demonstrated that p75(NTR) and NADE are co-induced in neurons degenerating after kainate-induced seizures in rats, likely in a zinc-dependent manner.

Isolation and characterization of wild-type lipoxygenase LOX(Psa)1 from Pleurotus sapidus.

Science.gov (United States)

Plagemann, Ina; Krings, Ulrich; Berger, Ralf G

2014-01-01

The lipoxygenase LOX(Psa) 1 of Pleurotus sapidus, originally investigated because of its ability to oxidize (+)-valencene to the valuable grapefruit aroma (+)-nootkatone, was isolated from the peptidase-rich lyophilisate using a three-step purification scheme including preparative isoelectric focusing and chromatographic techniques. Nano-liquid chromatography electrospray ionization tandem mass spectrometry (nLC-ESI-MS/MS) of the purified enzyme and peptide mass fingerprint analysis gave 38 peptides of the lipoxygenase from P. sapidus. Nearly 50% of the 643 amino acids long sequence encoded by the cDNA was covered. Both terminal peptides of the native LOX(Psa) 1 were identified by de novo sequencing, and the postulated molecular mass of 72.5 kDa was confirmed. With linoleic acid as the substrate, the LOX(Psa)1 showed a specific activity of 113 U mg(-1) and maximal activity at pH 7.0 and 30 degrees C, respectively.

Ox-LDL increases OX40L in endothelial cells through a LOX-1-dependent mechanism

Energy Technology Data Exchange (ETDEWEB)

Dong, Q.; Xiang, R.; Zhang, D.Y.; Qin, S. [Department of Cardiology, The First Affiliated Hospital, Chongqing Medical University, Chongqing (China)

2013-09-19

Oxidative low-density lipoprotein (Ox-LDL) is a key risk factor for the development of atherosclerosis, and it can stimulate the expression of a variety of inflammatory signals. As a new and highly sensitive inflammation index, OX40L may be a key to understanding the mechanisms that regulate interactions between cells within the vessel wall and inflammatory mediators during the development of atherosclerosis. To investigate whether Ox-LDL regulates OX40L expression through an oxidized LDL-1 receptor (LOX-1)-mediated mechanism, we investigated the effect of different concentrations of Ox-LDL (50, 100, 150 µg/mL) on endothelial cell proliferation and apoptosis. Stimulation with Ox-LDL increased OX40L protein 1.44-fold and mRNA 4.0-fold in endothelial cells, and these effects were inhibited by blocking LOX-1. These results indicate that LOX-1 plays an important role in the chronic inflammatory process in blood vessel walls. Inhibiting LOX-1 may reduce blood vessel inflammation and provide a therapeutic option to limit atherosclerosis progression.

Prokaryotic Expression, Purification and Characterization of a Novel Rice Seed Lipoxygenase Gene OsLOX1

Directory of Open Access Journals (Sweden)

Ren Wang

2008-06-01

Full Text Available Lipoxygenase (LOX, EC1.13.11.12 is a key enzyme during the degradation of lipids in animals and even plants, and also the first key enzyme responsible for the biosynthesis of jasmonate. To purify and characterize the OsLOX1 gene from rice seeds, the entire coding region of the OsLOX1 gene was inserted into an expression vector pET30a(+ and transformed into Escherichia coli BL21 (DE3. Expression of the fusion protein was successfully induced by isopropyl-β-D- thiogalactopyranoside (IPTG and the purified recombinant protein was obtained by His·Bind® Kits. Further assay showed that the purified recombinant protein exhibited the LOX activity. The optimum pH was 4.8 (acetate buffer and the optimum temperature was 30°C for the above enzyme. Thus, the recombinant might confer an available usage for the synthesis of jasmonate in vitro, and also provides a possibility for elucidating the inter-relationship between the primary structure of the plant seed lipoxygenase protein and its physiological functions.

Ox-LDL increases OX40L in endothelial cells through a LOX-1-dependent mechanism

International Nuclear Information System (INIS)

Dong, Q.; Xiang, R.; Zhang, D.Y.; Qin, S.

2013-01-01

Oxidative low-density lipoprotein (Ox-LDL) is a key risk factor for the development of atherosclerosis, and it can stimulate the expression of a variety of inflammatory signals. As a new and highly sensitive inflammation index, OX40L may be a key to understanding the mechanisms that regulate interactions between cells within the vessel wall and inflammatory mediators during the development of atherosclerosis. To investigate whether Ox-LDL regulates OX40L expression through an oxidized LDL-1 receptor (LOX-1)-mediated mechanism, we investigated the effect of different concentrations of Ox-LDL (50, 100, 150 µg/mL) on endothelial cell proliferation and apoptosis. Stimulation with Ox-LDL increased OX40L protein 1.44-fold and mRNA 4.0-fold in endothelial cells, and these effects were inhibited by blocking LOX-1. These results indicate that LOX-1 plays an important role in the chronic inflammatory process in blood vessel walls. Inhibiting LOX-1 may reduce blood vessel inflammation and provide a therapeutic option to limit atherosclerosis progression

Chemistry and propulsion; Chimie et propulsions

Energy Technology Data Exchange (ETDEWEB)

Potier, P [Maison de la Chimie, 75 - Paris (France); Davenas, A [societe Nationale des Poudres et des Explosifs - SNPE (France); Berman, M [Air Force Office of Scientific Research, Arlington, VA (United States); and others

2002-07-01

During the colloquium on chemistry and propulsion, held in march 2002, ten papers have been presented. The proceedings are brought in this document: ramjet, scram-jet and Pulse Detonation Engine; researches and applications on energetic materials and propulsion; advances in poly-nitrogen chemistry; evolution of space propulsion; environmental and technological stakes of aeronautic propulsion; ramjet engines and pulse detonation engines, automobiles thermal engines for 2015, high temperature fuel cells for the propulsion domain, the hydrogen and the fuel cells in the future transports. (A.L.B.)

Liquid Oxygen/Liquid Methane Integrated Power and Propulsion

Science.gov (United States)

Banker, Brian; Ryan, Abigail

2016-01-01

The proposed paper will cover ongoing work at the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) on integrated power and propulsion for advanced human exploration. Specifically, it will present findings of the integrated design, testing, and operational challenges of a liquid oxygen / liquid methane (LOx/LCH4) propulsion brassboard and Solid Oxide Fuel Cell (SOFC) system. Human-Mars architectures point to an oxygen-methane economy utilizing common commodities, scavenged from the planetary atmosphere and soil via In-Situ Resource Utilization (ISRU), and common commodities across sub-systems. Due to the enormous mass gear-ratio required for human exploration beyond low-earth orbit, (for every 1 kg of payload landed on Mars, 226 kg will be required on Earth) increasing commonality between spacecraft subsystems such as power and propulsion can result in tremendous launch mass and volume savings. Historically, propulsion and fuel cell power subsystems have had little interaction outside of the generation (fuel cell) and consumption (propulsion) of electrical power. This was largely due to a mismatch in preferred commodities (hypergolics for propulsion; oxygen & hydrogen for fuel cells). Although this stove-piped approach benefits from simplicity in the design process, it means each subsystem has its own tanks, pressurization system, fluid feed system, etc. increasing overall spacecraft mass and volume. A liquid oxygen / liquid methane commodities architecture across propulsion and power subsystems would enable the use of common tankage and associated pressurization and commodity delivery hardware for both. Furthermore, a spacecraft utilizing integrated power and propulsion could use propellant residuals - propellant which could not be expelled from the tank near depletion due to hydrodynamic considerations caused by large flow demands of a rocket engine - to generate power after all propulsive maneuvers are complete thus utilizing

Nitrate assimilation pathway (NAP): role of structural (nit) and transporter (ntr1) genes in Fusarium oxysporum f.sp. lycopersici growth and pathogenicity.

Science.gov (United States)

Gomez-Gil, Lucia; Camara Almiron, Jesus; Rodriguez Carrillo, Patricia Lizett; Olivares Medina, Cindy Nayely; Bravo Ruiz, Gustavo; Romo Rodriguez, Pamela; Corrales Escobosa, Alma Rosa; Gutierrez Corona, Felix; Roncero, M Isabel

2018-04-01

The tomato pathogen Fusarium oxysporum f.sp. lycopersici possesses the capability to use nitrate as the only nitrogen source under aerobic and anaerobic conditions and to activate virulence-related functions when cultivated in the presence of nitrate, but not in ammonium. The genome of F. oxysporum f.sp. lycopersici encodes three paralogs nitrate reductase (NR) genes (nit1, nit2 and nit3) and one predicted ortholog of the Aspergillus nidulans high-affinity nitrate/nitrite transporters NtrA and NtrB, named ntr1. We set out to clarify the role of nit1, nit2, nit3 and ntr1 genes in nitrate assimilation and in the virulence of F. oxysporum f.sp. lycopersici. Quantitative RT-PCR analysis revealed that only nit1, nit2 and ntr1 are expressed at significant levels during growth in nitrate as the only nitrogen source. Targeted deletion of nit1 and ntr1, but not of nit2 or nit3, severely impaired growth of F. oxysporum on nitrate as nitrogen source, indicating that Nit1 and Ntr1 proteins are involved in nitrate assimilation by the fungus; biochemical analysis of nit mutants indicated that Nit1 and Nit2 enzymes contribute to about 50 and 30% of the total NR activity, respectively. In addition, a spontaneous chlorate-resistant mutant derived from F. oxysporum 4287, denoted NitFG, was characterized, showing inability to grow in nitrate under aerobic and anaerobic conditions and low levels of NR activity, in spite of its increased transcription levels of nit1 and nit2 genes. Tomato plant infection assays showed that NitFG and ∆ntr1 mutants induced an earlier death in tomato plants, whereas the single mutants ∆nit1, ∆nit2 and ∆nit1∆nit2 double mutant showed a mortality rate similar to the wild-type strain. Taken together, these results indicate that the Nit1 and Ntr1 proteins are important for nitrate assimilation of F. oxysporum f.sp. lycopersici incubated under aerobic and anaerobic conditions and that this metabolic process is not essential for the virulence of

Bypass of lethality with mosaic mice generated by Cre-loxP-mediated recombination.

Science.gov (United States)

Betz, U A; Vosshenrich, C A; Rajewsky, K; Müller, W

1996-10-01

The analysis of gene function based on the generation of mutant mice by homologous recombination in embryonic stem cells is limited if gene disruption results in embryonic lethality. Mosaic mice, which contain a certain proportion of mutant cells in all organs, allow lethality to be circumvented and the potential of mutant cells to contribute to different cell lineages to be analyzed. To generate mosaic animals, we used the bacteriophage P1-derived Cre-loxP recombination system, which allows gene alteration by Cre-mediated deletion of loxP-flanked gene segments. We generated nestin-cre transgenic mouse lines, which expressed the Cre recombinase under the control of the rat nestin promoter and its second intron enhancer. In crosses to animals carrying a loxP-flanked target gene, partial deletion of the loxP-flanked allele occurred before day 10.5 post coitum and was detectable in all adult organs examined, including germ-line cells. Using this approach, we generated mosaic mice containing cells deficient in the gamma-chain of the interleukin-2 receptor (IL-2R gamma); in these animals, the IL-2R gamma-deficient cells were underrepresented in the thymus and spleen. Because mice deficient in DNA polymerase beta die perinatally, we studied the effects of DNA polymerase beta deficiency in mosaic animals. We found that some of the mosaic polymerase beta-deficient animals were viable, but were often reduced in size and weight. The fraction of DNA polymerase beta-deficient cells in mosaic embryos decreased during embryonic development, presumably because wild-type cells had a competitive advantage. The nestin-cre transgenic mice can be used to generate mosaic animals in which target genes are mutated by Cre-mediated recombination of loxP-flanked target genes. By using mosaic animals, embryonic lethality can be bypassed and cell lineages for whose development a given target gene is critical can be identified. In the case of DNA polymerase beta, deficient cells are already

Single-stage-to-orbit performance enhancement from take-off thrust augmentation

Science.gov (United States)

Galati, Terence; Elkins, Travis

1997-01-01

Thrust augmentation offers the Single Stage to Orbit (SSTO) space launch vehicle improved payload capability while reducing vehicle weight and cost. Optimization of vehicle configuration and flight profile are studied. Using a 612,000 kg Gross Lift Off Weight (GLOW) SSTO with three Castor® strap-on motors, payloads in excess of 18,000 kg to Low Earth Orbit (LEO) are achievable. Emphasis is placed on finding vehicle optimums in the 9,000 kg payload range to capture over 80% of commercial payloads. Strap-on boosters allow a small SSTO vehicle to fly with a mass fraction of only 0.88 and LOX/H2 engines operating at 445 sec vacuum specific impulse. Payload sensitivity due to variations of mass fraction, Isp and pitch rate are quantified.

Induction of the p75NTR by Aryl Propionic Acids in Prostate Cancer Cells

National Research Council Canada - National Science Library

Quann, Emily

2007-01-01

.... I have found that treatment of prostate cancer cells with the aryl propionic acids R-flurbiprofen and ibuprofen induces reexpression of p75NTR, decreases cell survival, and increases apoptosis...

Oxidised LDL internalisation by the LOX-1 scavenger receptor is dependent on a novel cytoplasmic motif and is regulated by dynamin-2.

Science.gov (United States)

Murphy, Jane E; Vohra, Ravinder S; Dunn, Sarah; Holloway, Zoe G; Monaco, Anthony P; Homer-Vanniasinkam, Shervanthi; Walker, John H; Ponnambalam, Sreenivasan

2008-07-01

The LOX-1 scavenger receptor recognises pro-atherogenic oxidised low-density lipoprotein (OxLDL) particles and is implicated in atherosclerotic plaque formation, but this mechanism is not well understood. Here we show evidence for a novel clathrin-independent and cytosolic-signal-dependent pathway that regulates LOX-1-mediated OxLDL internalisation. Cell surface labelling in the absence or presence of OxLDL ligand showed that LOX-1 is constitutively internalised from the plasma membrane and its half-life is not altered upon ligand binding and trafficking. We show that LOX-1-mediated OxLDL uptake is disrupted by overexpression of dominant-negative dynamin-2 but unaffected by CHC17 or mu2 (AP2) depletion. Site-directed mutagenesis revealed a conserved and novel cytoplasmic tripeptide motif (DDL) that regulates LOX-1-mediated endocytosis of OxLDL. Taken together, these findings indicate that LOX-1 is internalised by a clathrin-independent and dynamin-2-dependent pathway and is thus likely to mediate OxLDL trafficking in vascular tissues.

Preliminary Thermohydraulic Analysis of a New Moderated Reactor Utilizing an LEU-Fuel for Space Nuclear Thermal Propulsion

Energy Technology Data Exchange (ETDEWEB)

Nam, Seung Hyun; Choi, Jae Young; Venneria, Paolo F.; Jeong, Yong Hoon; Chang, Soon Heung [KAIST, Daejeon (Korea, Republic of)

2015-10-15

The Korea Advanced NUclear Thermal Engine Rocket utilizing an LEU fuel (KANUTER-LEU) is a non-proliferative and comparably efficient NTR engine with relatively low thrust levels of 40 - 50 kN for in-space transportation. The small modular engine can expand mission versatility, when flexibly used in a clustered engine arrangement, so that it can perform various scale missions from low-thrust robotic science missions to high-thrust manned missions. In addition, the clustered engine system can enhance engine redundancy and ensuing crew safety as well as the thrust. The propulsion system is an energy conversion system to transform the thermal energy of the reactor into the kinetic energy of the propellant to produce the powers for thrust, propellant feeding and electricity. It is mainly made up of a propellant Feeding System (PFS) comprising a Turbo-Pump Assembly (TPA), a Regenerative Nozzle Assembly (RNA), etc. For this core design study, an expander cycle is assumed to be the propulsion system. The EGS converts the thermal energy of the EHTGR in the idle operation (only 350 kW{sub th} power) to electric power during the electric power mode. This paper presents a preliminary thermohydraulic design analysis to explore the design space for the new reactor and to estimate the referential engine performance. The new non-proliferative NTR engine concept, KANUTER-LEU, is under designing to surmount the nuclear proliferation obstacles on allR and Dactivities and eventual commercialization for future generations. To efficiently implement a heavy LEU fuel for the NTR engine, its reactor design innovatively possesses the key characteristics of the high U density fuel with high heating and H{sub 2} corrosion resistances, the thermal neutron spectrum core and also minimizing non-fission neutron loss, and the compact reactor design with protectively cooling capability. To investigate feasible design space for the moderated EHTGR-LEU and resultant engine performance, the

Development of CFD model for augmented core tripropellant rocket engine

Science.gov (United States)

Jones, Kenneth M.

1994-10-01

The Space Shuttle era has made major advances in technology and vehicle design to the point that the concept of a single-stage-to-orbit (SSTO) vehicle appears more feasible. NASA presently is conducting studies into the feasibility of certain advanced concept rocket engines that could be utilized in a SSTO vehicle. One such concept is a tripropellant system which burns kerosene and hydrogen initially and at altitude switches to hydrogen. This system will attain a larger mass fraction because LOX-kerosene engines have a greater average propellant density and greater thrust-to-weight ratio. This report describes the investigation to model the tripropellant augmented core engine. The physical aspects of the engine, the CFD code employed, and results of the numerical model for a single modular thruster are discussed.

Construction of Marker-Free Transgenic Strains of Chlamydomonas reinhardtii Using a Cre/loxP-Mediated Recombinase System.

Science.gov (United States)

Kasai, Yuki; Harayama, Shigeaki

2016-01-01

The Escherichia coli bacteriophage P1 encodes a site-specific recombinase called Cre and two 34-bp target sites of Cre recombinase called loxP. The Cre/loxP system has been used to achieve targeted insertion and precise deletion in many animal and plant genomes. The Cre/loxP system has particularly been used for the removal of selectable marker genes to create marker-free transgenic organisms. For the first time, we applied the Cre/loxP-mediated site-specific recombination system to Chlamydomonas reinhardtii to construct marker-free transgenic strains. Specifically, C. reinhardtii strains cc4350 and cc124 carrying an aphVIII expression cassette flanked by two direct repeats of loxP were constructed. Separately, a synthetic Cre recombinase gene (CrCRE), the codons of which were optimized for expression in C. reinhardtii, was synthesized, and a CrCRE expression cassette was introduced into strain cc4350 carrying a single copy of the loxP-flanked aphVIII expression cassette. Among 46 transformants carrying the CrCRE expression cassette stably, the excision of aphVIII by CrCre recombinase was observed only in one transformant. We then constructed an expression cassette of an in-frame fusion of ble to CrCRE via a short linker peptide. The product of ble (Ble) is a bleomycin-binding protein that confers resistance to bleomycin-related antibiotics such as Zeocin and localizes in the nucleus. Therefore, the ble-(linker)-CrCRE fusion protein is expected to localize in the nucleus. When the ble-(linker)-CrCRE expression cassette was integrated into the genome of strain cc4350 carrying a single copy of the loxP-flanked aphVIII expression cassette, CrCre recombinase-mediated excision of the aphVIII expression cassette was observed at a frequency higher than that in stable transformants of the CrCRE expression cassette. Similarly, from strain cc124 carrying a single loxP-flanked aphVIII expression cassette, the aphVIII expression cassette was successfully excised after

Size does matter: Cre-mediated somatic deletion efficiency depends on the distance between the target lox-sites

NARCIS (Netherlands)

Coppoolse, E.R.; Vroomen, de M.J.; Gennip, van F.; Hersmus, B.J.M.; Haaren, van M.J.

2005-01-01

Cre/lox recombination in vivo has become an important tool to induce chromosomal rearrangements like deletions. Using a combination of Ds transposition and Cre/lox recombination in two independent experiments on chromosomes 6 and 7 of tomato, two sets of somatic deletions up to a size of 200 kb were

A self-excising Cre recombinase allows efficient recombination of multiple ectopic heterospecific lox sites in transgenic tobacco

NARCIS (Netherlands)

Mlynarova, L.; Nap, J.P.H.

2003-01-01

To study the impact of different DNA configurations on the stability of transgene expression, a variant of the cre gene was developed. This variant allows for the highly efficient in planta removal of its own loxP-flanked coding sequence as well as other DNAs flanked by ectopic heterospecific lox

Double transduction of a Cre/LoxP lentiviral vector: a simple method to generate kidney cell-specific knockdown mice.

Science.gov (United States)

Nam, Bo Young; Kim, Dong Ki; Park, Jung Tak; Kang, Hye-Young; Paeng, Jisun; Kim, Seonghun; Park, Jimin; Um, Jae Eun; Oh, Hyung Jung; Han, Seung Hyeok; Yoo, Tae-Hyun; Kang, Shin-Wook

2015-12-15

In a lentivirus-based gene delivery system, the incorporated gene is continuously expressed for a long time. In this study, we devised a simple way to knock down a specific gene in a kidney cell-specific pattern in adult mice by lentivirus-assisted transfer of short hairpin RNA (shRNA). Kidney collecting duct (CD)-specific aquaporin-3 (AQP3)-knockdown mice were generated by consecutive injection of Hoxb7-Cre-expressing lentivirus (LV-Hoxb7 Cre) and loxP-AQP3 shRNA-expressing lentivirus (LV-loxP shAQP3) in adult C57BL6/J mice. LV-Hoxb7 Cre was designed to express mCherry, while LV-loxP shAQP3 was designed with a floxed enhanced green fluorescent protein (EGFP)-tagged stop sequence, and thus EGFP would be expressed only in the absence of Cre recombination. In mice treated with LV-Hoxb7 Cre alone, mCherry protein expression, which indicates the presence of Cre recombinase, occurred only in CD cells. However, LV-loxP shAQP3 injection alone resulted in an increase in EGFP expression in all kidney cells, indicating the transcription of the floxed region. When LV-Hoxb7 Cre and LV-loxP shAQP3 were sequentially transduced, EGFP expression was attenuated while mCherry expression was sustained in CD cells, demonstrating a CD cell-specific recombination of the floxed region. AQP3 expression in mice injected with LV-Hoxb7 Cre or LV-loxP shAQP3 alone did not differ, but consecutive injection of LV-Hoxb7 Cre and LV-loxP shAQP3 significantly reduced AQP3 expression in CD cells. However, the expression levels of AQP3 were not altered in other cell types. Double transduction of Cre- and loxP-based lentivirus can easily generate kidney cell-specific knockdown mice, and this method might be applicable to other species. Copyright © 2015 the American Physiological Society.

Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures

Science.gov (United States)

Jurns, J. M.; Hartwig, J. W.

2012-04-01

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMDs) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122 K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Risk Assessment and scaling for the SLS LOx ET

Science.gov (United States)

Osipov, Viatcheslav V.; Hafiychuk, Halyna; Devine, Ekaterina V.; Khasin, Michael; Smelyanskiy, Vadim N.

2012-01-01

In this report we analyze the transpiration cooling by He bubble injection of the long LOx tank feedline heated by the environment heat. We consider possible hazards that can arise in the proposed design of the SLS core stage where the feedline length is much longer than that used in the Space Shuttle.

''Fast track'' lunar NTR systems assessment for NASA's first lunar outpost and its evolvability to Mars

International Nuclear Information System (INIS)

Borowski, S.K.; Alexander, S.W.

1993-01-01

Integrated systems and missions studies are presented for an evolutionary lunar-to-Mars space transportion system (STS) based on nuclear thermal rocket (NTR) technology. A ''standardized'' set of engine and stage components are identified and used in a ''building block'' fashion to configure a variety of piloted and cargo, lunar and Mars vehicles. The reference NTR characteristics include a thrust of 50 thousand pounds force (klbf), specific impulse (I sp ) of 900 seconds, and an engine thrust-to-weight ratio of 4.3. For the National Aeronautics and Space Administration's (NASA) First Lunar Outpost (FLO) mission, an expendable NTR stage powered by two such engines can deliver ∼96 metric tonnes (t) to trans-lunar injection (TLI) conditions for an initial mass in low Earth orbit (IMLEO) of ∼198 t compared to 250 t for a cryogenic chemical system. The stage liquid hydrogen (LH 2 ) tank has a diameter, length, and capacity of 10 m, 14.5 m and 66 t, respectively. By extending the stage length and LH 2 capacity to ∼20 m and 96 t, a single launch Mars cargo vehicle could deliver to an elliptical Mars parking orbit a 63 t Mars excursion vehicle (MEV) with a 45 t surface payload. Three 50 klbf engines and the two standardized LH 2 tanks developed for the lunar and Mars cargo vehicles are used to configure the vehicles supporting piloted Mars missions as early as 2010. The ''modular'' NTR vehicle approach forms the basis for an efficient STS able to handle the needs of a wide spectrum of lunar and Mars missions

Simulation of water vapor condensation on LOX droplet surface using liquid nitrogen

Science.gov (United States)

Powell, Eugene A.

1988-01-01

The formation of ice or water layers on liquid oxygen (LOX) droplets in the Space Shuttle Main Engine (SSME) environment was investigated. Formulation of such ice/water layers is indicated by phase-equilibrium considerations under conditions of high partial pressure of water vapor (steam) and low LOX droplet temperature prevailing in the SSME preburner or main chamber. An experimental investigation was begun using liquid nitrogen as a LOX simulant. A monodisperse liquid nitrogen droplet generator was developed which uses an acoustic driver to force the stream of liquid emerging from a capillary tube to break up into a stream of regularly space uniformly sized spherical droplets. The atmospheric pressure liquid nitrogen in the droplet generator reservoir was cooled below its boiling point to prevent two phase flow from occurring in the capillary tube. An existing steam chamber was modified for injection of liquid nitrogen droplets into atmospheric pressure superheated steam. The droplets were imaged using a stroboscopic video system and a laser shadowgraphy system. Several tests were conducted in which liquid nitrogen droplets were injected into the steam chamber. Under conditions of periodic droplet formation, images of 600 micron diameter liquid nitrogen droplets were obtained with the stroboscopic video systems.

α-Fetoprotein promoter-driven Cre/LoxP-switched RNA interference for hepatocellular carcinoma tissue-specific target therapy.

Directory of Open Access Journals (Sweden)

Yuan-Fei Peng

Full Text Available RNA interference (RNAi has recently emerged as a potential treatment modality for hepatocellular carcinoma (HCC therapy, but the lack of cellular targets and sustained efficacy limits its application. The purpose of this study is to develop an HCC tissue-specific RNAi system and investigate its possibility for HCC treatment.Two different HCC-specific RNAi systems in which therapeutic miRNA or shRNA against target gene (Beclin 1 was directly or indirectly driven by alpha-fetoprotein promoter (AFP-miRNA and AFP-Cre/LoxP-shRNA were constructed. Human HCC cell lines (HepG2, Hep3B and HCCLM3 and non-HCC cell lines (L-02, Hela and SW1116 were infected with the systems. The effectiveness and tissue-specificity of the systems were examined by Q-PCR and western blot analysis. The efficacy of the systems was further tested in mouse model of HCC by intravenous or intratumoral administration. The feasibility of the system for HCC treatment was evaluated by applying the system as adjuvant therapy to enhance sorafenib treatment. An AFP-Cre/LoxP-shRNA system targeting Atg5 gene (AFP-Cre/LoxP-shRNA-Atg5 was constructed and its efficacy in sensitizing HCC cells (MHCC97L/PLC to sorafenib treatment was examined by apoptosis assay in vitro and tumorigenesis assay in vivo.The AFP-miRNA system could silence target gene (Beclin 1 but required a high titer which was lethal to target cells. The AFP-Cre/LoxP-shRNA system could efficiently knockdown target gene while maintain high HCC specificity. Intratumoral injection of the AFP-Cre/LoxP-shRNA system could efficiently silence target gene (Beclin 1 in vivo while intravenous administration could not. The AFP-Cre/LoxP-shRNA system target Atg5 gene could significantly sensitize MHCC97L/PLC cells to sorafenib-induced apoptosis in vitro and tumor growth suppression in vivo.An efficient HCC tissue-specific RNAi system (AFP-Cre/LoxP-shRNA was successfully established. The system provides a usable tool for HCC-specific RNAi

The 9-lipoxygenase Osr9-LOX1 interacts with the 13-lipoxygenase-mediated pathway to regulate resistance to chewing and piercing-sucking herbivores in rice.

Science.gov (United States)

Zhou, Guoxin; Ren, Nan; Qi, Jingfeng; Lu, Jing; Xiang, Caiyu; Ju, Hongping; Cheng, Jiaan; Lou, Yonggen

2014-09-01

Oxylipins produced by the 13-lipoxygenase (LOX) have been reported to play an important role in plant defense responses to herbivores. Yet, the role of oxylipins produced by the 9-LOX pathway in this process remains largely unknown. Here we cloned a gene encoding a chloroplast-localized 9-LOX, Osr9-LOX1, from rice. Transcriptional analysis revealed that herbivore infestation, mechanical wounding and jasmonic acid (JA) treatment either repressed or did not enhance the level of Osr9-LOX1 transcripts at early stages but did at later stages, whereas salicylic acid (SA) treatment quickly increased the transcript level of Osr9-LOX1. Antisense expression of Osr9-lox1 (as-r9lox1) decreased the amount of wound-induced (Z)-3-hexenal but increased levels of striped stem borer (SSB)-induced linolenic acid, JA, SA and trypsin protease inhibitors. These changes were associated with increased resistance in rice to the larvae of the SSB Chilo suppressalis. In contrast, although no significant differences were observed in the duration of the nymph stage or the number of eggs laid by female adults between the brown planthopper (BPH) Nilaparvata lugens that fed on as-r9lox1 lines and BPH that fed on wild-type (WT) rice plants, the survival rate of BPH nymphs that fed on as-r9lox1 lines was higher than that of nymphs that fed on WT plants, possibly because of a higher JA level. The results demonstrate that Osr9-LOX1 plays an important role in regulating an herbivore-induced JA burst and cross-talk between JA and SA, and in controlling resistance in rice to chewing and phloem-feeding herbivores. © 2014 Scandinavian Plant Physiology Society.

Operational Issues in the Development of a Cost-Effective Reusable LOX/LH2 Engine

Science.gov (United States)

Ballard, Richard O.

2003-01-01

The NASA Space Launch Initiative (SLI) was initiated in early 2001 to conduct technology development and to reduce the business and technical risk associated with developing the next-generation reusable launch system. In the field of main propulsion, two LOXLH2 rocket engine systems, the Pratt & Whitney / Aerojet Joint Venture (JV) COBRA and the Rocketdyne RS-83, were funded to develop a safe, economical, and reusable propulsion system. Given that a large-thrust reusable rocket engine program had not been started in the U.S. since 1971, with the Space Shuttle Main Engine (SSME), this provided an opportunity to build on the experience developed on the SSME system, while exploiting advances in technology that had occurred in the intervening 30 years. One facet of engine development that was identified as being especially vital in order to produce an optimal system was in the areas of operability and maintainability. In order to achieve the high levels of performance required by the Space Shuttle, the SSME system is highly complex with very tight tolerances and detailed requirements. Over the lifetime of the SSME program, the engine has required a high level of manpower to support the performance of inspections, maintenance (scheduled and unscheduled) and operations (prelaunch and post-flight). As a consequence, the labor- intensive needs of the SSME provide a significant impact to the overall cost efficiency of the Space Transportation System (STS). One of the strategic goals of the SLI is to reduce cost by requiring the engine(s) to be easier (Le. less expensive) to operate and maintain. The most effective means of accomplishing this goal is to infuse the operability and maintainability features into the engine design from the start. This paper discusses some of the operational issues relevant to a reusable LOx/LH2 main engine, and the means by which their impact is mitigated in the design phase.

Thrust augmentation in tandem flapping foils by foil-wake interaction

Science.gov (United States)

Anderson, Erik; Lauder, George

2006-11-01

Propulsion by pitching and heaving airfoils and hydrofoils has been a focus of much research in the field of biologically inspired propulsion. Organisms that use this sort of propulsion are self-propelled, so it is difficult to use standard experimental metrics such as thrust and drag to characterize performance. We have constructed a flapping foil robot mounted in a flume on air-bearings that allows for the determination of self-propelled speed as a metric of performance. We have used a pair of these robots to examine the impact of an upstream flapping foil on a downstream flapping foil as might apply to tandem fins of a swimming organism or in-line swimming of schooling organisms. Self-propelled speed and a force transducer confirmed significant thrust augmentation for particular foil-to-foil spacings, phase differences, and flapping frequencies. Flow visualization shows the mechanism to be related to the effective angle of attack of the downstream foil due to the structure of the wake of the upstream foil. This confirms recent computational work and the hypotheses by early investigators of fish fluid dynamics.

Cre-Lox Neurogenetics: 20 Years of Versatile Applications in Brain Research and Counting….

Science.gov (United States)

Tsien, Joe Z

2016-01-01

Defining and manipulating specific neurons in the brain has garnered enormous interest in recent years, because such an approach is now widely recognized as crucial for deepening our understanding of how the brain works. When I started exploring the Cre-loxP recombination for brain research in the early 1990s, it was written off as a dead-end project by a young fool. Yet over the past 20 years, Cre-lox recombination-mediated neurogenetics has emerged as one of the most powerful and versatile technology platforms for cell-specific gene knockouts, transgenic overexpression, Brainbow imaging, neural pathway tracing with retrovirus and CLARITY, chemical genetics, and optogenetics. Its popularity and greater utility in neuroscience research is also largely thanks to the NIH's bold Blueprint for Neuroscience Research Initiative to launch several Cre-driver resource projects, as well as individual laboratories and private research organizations. With newly-discovered, genetically-encoded molecules that are capable of responding to sonar and magnetic stimulation, for sonogenetics or magnetogenetics, respectively, or detecting rapid voltage changes in neurons, Cre-lox neurogenetics will continue to aid brain research for years to come.

Affordable Development and Demonstration of a Small Nuclear Thermal Rocket (NTR) Engine and Stage: How Small Is Big Enough?

Science.gov (United States)

Borowski, Stanley K.; Sefcik, Robert J.; Fittje, James E.; McCurdy, David R.; Qualls, Arthur L.; Schnitzler, Bruce G.; Werner, James E.; Weitzberg, Abraham; Joyner, Claude R.

2016-01-01

The Nuclear Thermal Rocket (NTR) derives its energy from fission of uranium-235 atoms contained within fuel elements that comprise the engine's reactor core. It generates high thrust and has a specific impulse potential of approximately 900 specific impulse - a 100 percent increase over today's best chemical rockets. The Nuclear Thermal Propulsion (NTP) project, funded by NASA's Advanced Exploration Systems (AES) program, includes five key task activities: (1) Recapture, demonstration, and validation of heritage graphite composite (GC) fuel (selected as the Lead Fuel option); (2) Engine Conceptual Design; (3) Operating Requirements Definition; (4) Identification of Affordable Options for Ground Testing; and (5) Formulation of an Affordable Development Strategy. During fiscal year (FY) 2014, a preliminary Design Development Test and Evaluation (DDT&E) plan and schedule for NTP development was outlined by the NASA Glenn Research Center (GRC), Department of Energy (DOE) and industry that involved significant system-level demonstration projects that included Ground Technology Demonstration (GTD) tests at the Nevada National Security Site (NNSS), followed by a Flight Technology Demonstration (FTD) mission. To reduce cost for the GTD tests and FTD mission, small NTR engines, in either the 7.5 or 16.5 kilopound-force thrust class, were considered. Both engine options used GC fuel and a common fuel element (FE) design. The small approximately 7.5 kilopound-force criticality-limited engine produces approximately157 thermal megawatts and its core is configured with parallel rows of hexagonal-shaped FEs and tie tubes (TTs) with a FE to TT ratio of approximately 1:1. The larger approximately 16.5 kilopound-force Small Nuclear Rocket Engine (SNRE), developed by Los Alamos National Laboratory (LANL) at the end of the Rover program, produces approximately 367 thermal megawatts and has a FE to TT ratio of approximately 2:1. Although both engines use a common 35-inch (approximately

Functional analysis and molecular dynamics simulation of LOX-1 K167N polymorphism reveal alteration of receptor activity.

Directory of Open Access Journals (Sweden)

Silvia Biocca

Full Text Available The human lectin-like oxidized low density lipoprotein receptor 1 LOX-1, encoded by the ORL1 gene, is the major scavenger receptor for oxidized low density lipoprotein in endothelial cells. Here we report on the functional effects of a coding SNP, c.501G>C, which produces a single amino acid change (K>N at codon 167. Our study was aimed at elucidating whether the c.501G>C polymorphism changes the binding affinity of LOX-1 receptor altering its function. The presence of p.K167N mutation reduces ox-LDL binding and uptake. Ox-LDL activated extracellular signal-regulated kinases 1 and 2 (ERK 1/2 is inhibited. Furthermore, ox-LDL induced biosynthesis of LOX-1 receptors is dependent on the p.K167N variation. In human macrophages, derived from c.501G>C heterozygous individuals, the ox-LDL induced LOX-1 46 kDa band is markedly lower than in induced macrophages derived from c.501G>C controls. Investigation of p.K167N mutation through molecular dynamics simulation and electrostatic analysis suggests that the ox-LDL binding may be attributed to the coupling between the electrostatic potential distribution and the asymmetric flexibility of the basic spine residues. The N/N-LOX-1 mutant has either interrupted electrostatic potential and asymmetric fluctuations of the basic spine arginines.

Effect of an ntrC mutation on amino acid or urea utilization and on nitrogenase switch-off in Herbaspirillum seropedicae.

Science.gov (United States)

Gusso, Claudio L; de Souza, Emanuel M; Rigo, Liu Un; de Oliveira Pedrosa, Fábio; Yates, M G; de M Rego, Fabiane G; Klassen, Giseli

2008-03-01

Herbaspirillum seropedicae is a nitrogen-fixing bacterium that grows well with ammonium chloride or sodium nitrate as alternative single nitrogen sources but that grows more slowly with L-alanine, L-serine, L-proline, or urea. The ntrC mutant strain DCP286A was able to utilize only ammonium or urea of these nitrogen sources. The addition of 1 mmol.L-1 ammonium chloride to the nitrogen-fixing wild-type strain inhibited nitrogenase activity rapidly and completely. Urea was a less effective inhibitor; approximately 20% of nitrogenase activity remained 40 min after the addition of 1 mmol x L-1 urea. The effect of the ntrC mutation on nitrogenase inhibition (switch-off) was studied in strain DCP286A containing the constitutively expressed gene nifA of H. seropedicae. In this strain, nitrogenase inhibition by ammonium was completely abolished, but the addition of urea produced a reduction in nitrogenase activity similar to that of the wild-type strain. The results suggest that the NtrC protein is required for assimilation of nitrate and the tested amino acids by H. seropedicae. Furthermore, NtrC is also necessary for ammonium-induced switch-off of nitrogenase but is not involved in the mechanism of nitrogenase switch-off by urea.

Development of ultrasonic electrostatic microjets for distributed propulsion and microflight

Science.gov (United States)

Amirparviz, Babak

This dissertation details the first attempt to design and fabricate a distributed micro propulsion system based on acoustic streaming. A novel micro propulsion method is suggested by combining Helmholtz resonance, acoustic streaming and flow entrainment and thrust augmentation. In this method, oscillatory motion of an electrostatically actuated diaphragm creates a high frequency acoustic field inside the cavity of a Helmholtz resonator. The initial fluid motion velocity is amplified by the Helmholtz resonator structure and creates a jet flow at the exit nozzle. Acoustic streaming is the phenomenon responsible for primary jet stream creation. Primary jets produced by a few resonators can be combined in an ejector configuration to induce flow entrainment and thrust augmentation. Basic governing equations for the electrostatic actuator, deformation of the diaphragm and the fluid flow inside the resonator are derived. These equations are linearized and used to derive an equivalent electrical circuit model for the operation of the device. Numerical solution of the governing equations and simulation of the circuit model are used to predict the performance of the experimental systems. Thrust values as high as 30.3muN are expected per resonator. A micro machined electrostatically-driven high frequency Helmholtz resonator prototype is designed and fabricated. A new micro fabrication technique is developed for bulk micromachining and in particular fabrication of the resonator. Geometric stops for wet anisotropic etching of silicon are introduced for the fist time for structure formation. Arrays of high frequency (>60kHz) micro Helmholtz resonators are fabricated. In one sample more than 1000 resonators cover the surface of a four-inch silicon wafer and in effect convert it to a distributed propulsion system. A high yield (>85%) micro fabrication process is presented for realization of this propulsion system taking advantage of newly developed deep glass micromachining and

Solid propellant ignition motors for LH_2/LOX rocket engine system

OpenAIRE

ARAKI, Tetsuo; AKIBA, Ryojiro; HASHIMOTO, Yasunari; AIHARA, Kenji; TOMITA, Etsu; YASUDA, Seiichi; 荒木, 哲夫; 秋葉, 鐐二郎; 橋本, 保成; 相原, 賢二; 富田, 悦; 安田, 誠一

1983-01-01

Solid propellant ignition motors are used in the series of experiments of the 10 ton LH_2/LOX engine featured by the channel wall thrust chamber, This paper presents design specification, experiments and results obtained by actual applications of those ignition motors.

Airbreathing engine selection criteria for SSTO propulsion system

Science.gov (United States)

Ohkami, Yoshiaki; Maita, Masataka

1995-02-01

This paper presents airbreathing engine selection criteria to be applied to the propulsion system of a Single Stage To Orbit (SSTO). To establish the criteria, a relation among three major parameters, i.e., delta-V capability, weight penalty, and effective specific impulse of the engine subsystem, is derived as compared to these parameters of the LH2/LOX rocket engine. The effective specific impulse is a function of the engine I(sub sp) and vehicle thrust-to-drag ratio which is approximated by a function of the vehicle velocity. The weight penalty includes the engine dry weight, cooling subsystem weight. The delta-V capability is defined by the velocity region starting from the minimum operating velocity up to the maximum velocity. The vehicle feasibility is investigated in terms of the structural and propellant weights, which requires an iteration process adjusting the system parameters. The system parameters are computed by iteration based on the Newton-Raphson method. It has been concluded that performance in the higher velocity region is extremely important so that the airbreathing engines are required to operate beyond the velocity equivalent to the rocket engine exhaust velocity (approximately 4500 m/s).

Efecto in vitro del D-002 sobre la actividad enzimática de la 5-lipoxigenasa (5-LOX Effect of D-002 on 5-lipooxygenase (5-LOX enzyme activity in vitro

Directory of Open Access Journals (Sweden)

Yohani Pérez Guerra

2012-06-01

Full Text Available Introducción: el D-002, mezcla de seis alcoholes alifáticos primarios de alto peso molecular purificada de la cera de abejas, ha mostrado efectos antiinflamatorios, sin gastrotoxicidad secundaria, enmodelos experimentales. El tratamiento oral con D-002 reduce las concentraciones de leucotrieno B4 (LTB4 en exudados pleurales de ratas con pleuresía por carragenina, sugiriendo que podría inhibir la actividad enzimática de la 5-lipooxigenasa (5-LOX, si bien los mecanismos de la acción antiinflamatoria del D-002 no habían sido aún explorados. Objetivo: evaluar el efecto in vitro del D-002 sobre la actividad de la 5-LOX, utilizando la fracción citosólica de homogenatos de hígado de ratas. Métodos: las condiciones de ensayo utilizadas fueron las siguientes: fracción citosólica (50 µg de proteína disuelta en solución reguladora borato 0,2 mol/L (pH 9 y ácido linoleico (7,8-250 mmol/L como sustrato, ensayándose muestras paralelas incubadas con Tween-20/H2O (2 % (vehículo, muestras controles, D-002 (0,9-1 000 µg/mL o Lyprinol (500 µg/mL (sustancia de referencia. La actividad enzimática se evaluó mediante el cambio de absorbancia a 234 nm producido por la formación de dienos conjugados y medido en espectrofotómetro UV-visible. Resultados: la adición in vitro del D-002 produjo una inhibición significativa, dependiente de la dosis (r= 0,980; pIntroduction: D-002, a mixture of six high molecular weight primary aliphatic alcohols purified from beeswax, has been shown to produce anti-inflammatory effects with no secondary gastrotoxicity in experimental models. Oral treatment with D-002 was effective for lowering the concentrations of B4 leukotriene (LTB4 in pleural exudates of rats with carragenin-induced pleurisy, suggesting that it could inhibit 5-lipooxigenase (5-LOX enzyme activity. The mechanisms of the anti-inflammatory action of D-002, however, had not been explored yet. Objective: to evaluate the effects of D-002 on 5-LOX

Characterization of the lipoxygenase (LOX) gene family in the Chinese white pear (Pyrus bretschneideri) and comparison with other members of the Rosaceae.

Science.gov (United States)

Li, Meng; Li, Leiting; Dunwell, Jim M; Qiao, Xin; Liu, Xing; Zhang, Shaoling

2014-06-07

Lipoxygenases (LOXs), a type of non-haem iron-containing dioxygenase, are ubiquitous enzymes in plants and participate in the formation of fruit aroma which is a very important aspect of fruit quality. Amongst the various aroma volatiles, saturated and unsaturated alcohols and aldehydes provide the characteristic aroma of the fruit. These compounds are formed from unsaturated fatty acids through oxidation, pyrolysis and reduction steps. This biosynthetic pathway involves at least four enzymes, including LOX, the enzyme responsible for lipid oxidation. Although some studies have been conducted on the LOX gene family in several species including Arabidopsis, soybean, cucumber and apple, there is no information from pear; and the evolutionary history of this gene family in the Rosaceae is still not resolved. In this study we identified 107 LOX homologous genes from five Rosaceous species (Pyrus bretschneideri, Malus × domestica, Fragaria vesca, Prunus mume and Prunus persica); 23 of these sequences were from pear. By using structure analysis, phylogenic analysis and collinearity analysis, we identified variation in gene structure and revealed the phylogenetic evolutionary relationship of this gene family. Expression of certain pear LOX genes during fruit development was verified by analysis of transcriptome data. 23 LOX genes were identified in pear and these genes were found to have undergone a duplication 30-45 MYA; most of these 23 genes are functional. Specific gene duplication was found on chromosome4 in the pear genome. Useful information was provided for future research on the evolutionary history and transgenic research on LOX genes.

Examination of 12-lipoxygenase (12-LOX) as a therapeutic target in non-small cell lung cancer (NSCLC): Mechanisms controlling survival and induction of apoptosis following selective inhibition

LENUS (Irish Health Repository)

Cathcart, Mary Clare

2011-06-01

Background: Platelet-type 12-LOX is an arachidonic acid metabolising enzyme resulting in the formation of 12(S)-HETE, which stimulates tumour cell adhesion, invasion and metastasis. This study aimed to examine the expression profile and role of this enzyme in NSCLC, and determine if it is a potential target for intervention. Methods: A panel of retrospective resected lung tumours was stained for 12-LOX expression by IHC. Levels of the 12-LOX metabolite, 12(S)-HETE, were examined in 50 NSCLC serum samples, and correlated with serum VEGF. A panel of NSCLC cell lines were treated with baicalein (10 uM), a selective inhibitor of 12-LOX, or 12(S)-HETE (100 ng\\/ml) and cell survival\\/proliferation examined by BrdU. Apoptosis following 12-LOX inhibition was examined by HCS and validated by FACS and DNA laddering. The effect of 12-LOX inhibition on NSCLC tumour growth and survival was examined in-vivo using an athymic nude mouse model. Gene alterations following 12-LOX inhibition in NSCLC cell lines were assessed by qPCR arrays and validated by RT-PCR. Transient transfection methods were used to examine the effects of 12-LOX overexpression in NSCLC cells. Results: 12-LOX expression was observed to a varying degree in human lung cancers of varying histological subtypes. 12(S)-HETE levels were correlated (p<0.05) with those of VEGF. Baicalein inhibited proliferation\\/survival in all cell lines, while 12(S)-HETE increased proliferation. 12-LOX inhibition increased apoptosis, indicated by a reduction in f-actin content and mitochondrial mass potential. Treatment with baicalein significantly reduced the growth of NSCLC tumours and increased overall survival in athymic nude mice. qPCR array data implicated a number of apoptosis\\/angiogenesis genes regulating these effects, including bcl-2, VEGF, integrin A2 and A4. 12-LOX overexpression resulted in an increase in VEGF secretion, confirming qPCR observations. Conclusions: 12-LOX is a survival factor\\/potential target in

Liquid oxygen LOX compatibility evaluations of aluminum lithium (Al-Li) alloys: Investigation of the Alcoa 2090 and MMC weldalite 049 alloys

Science.gov (United States)

Diwan, Ravinder M.

1989-01-01

The behavior of liquid oxygen (LOX) compatibility of aluminum lithium (Al-Li) alloys is investigated. Alloy systems of Alcoa 2090, vintages 1 to 3, and of Martin Marietta Corporation (MMC) Weldalite 049 were evaluated for their behavior related to the LOX compatibility employing liquid oxygen impact test conditions under ambient pressures and up to 1000 psi. The developments of these aluminum lithium alloys are of critical and significant interest because of their lower densities and higher specific strengths and improved mechanical properties at cryogenic temperatures. Of the different LOX impact tests carried out at the Marshall Space Flight Center (MSFC), it is seen that in certain test conditions at higher pressures, not all Al-Li alloys are LOX compatible. In case of any reactivity, it appears that lithium makes the material more sensitive at grain boundaries due to microstructural inhomogeneities and associated precipitate free zones (PFZ). The objectives were to identify and rationalize the microstructural mechanisms that could be relaxed to LOX compatibility behavior of the alloy system in consideration. The LOX compatibility behavior of Al-Li 2090 and Weldalite 049 is analyzed in detail using microstructural characterization techniques with light optical metallography, scanning electron microscopy (SEM), electron microprobe analysis, and surface studies using secondary ion mass spectrometry (SIMS), electron spectroscopy in chemical analysis (ESCA) and Auger electron spectroscopy (AES). Differences in the behavior of these aluminum lithium alloys are assessed and related to their chemistry, heat treatment conditions, and microstructural effects.

Dependence of Relative Expression of NTR1 and EGFR on Cell Density and Extracellular pH in Human Pancreatic Cancer Cell Lines

International Nuclear Information System (INIS)

Olszewski-Hamilton, Ulrike; Hamilton, Gerhard

2011-01-01

Pancreatic adenocarcinoma is a devastating disease characterized by early dissemination and poor prognosis. These solid tumors express receptors for neuropeptides like neurotensin (NT) or epidermal growth factor (EGF) and exhibit acidic regions when grown beyond a certain size. We previously demonstrated increases in intracellular Ca 2+ levels, intracellular pH and interleukin-8 (IL-8) secretion in BxPC-3 and PANC-1 pancreatic cancer cells in response to a stable NT analog. The present study aimed at investigation of the dependence of the relative expression of NT receptor 1 (NTR1) and EGFR in BxPC-3 and MIA PaCa-2 cells on cell density and extracellular pH (pH e ). MTT assays revealed the NTR1 inhibitor SR 142948-sensitive Lys 8 -ψ-Lys 9 NT (8–13)-induced proliferation in BxPC-3 and PANC-1 cells. Confluent cultures of BxPC3 and HT-29 lines exhibited highest expression of NTR1 and lowest of EGFR and expression of NTR1 was maximal at slightly acidic pH e . IL-8 production was stimulated by Lys 8 -ψ-Lys 9 NT (8–13) and even enhanced at both acidic and alkaline pH e in BxPC-3 and PANC-1 cells. In conclusion, our in vitro study suggests that one contributing factor to the minor responses obtained with EGFR-directed therapy may be downregulation of this receptor in tumor cell aggregates, possibly resulting in acquisition of a more aggressive phenotype via other growth factor receptors like NTR1

Involvement of TrkB- and p75NTR-signaling pathways in two contrasting forms of long-lasting synaptic plasticity

Science.gov (United States)

Sakuragi, Shigeo; Tominaga-Yoshino, Keiko; Ogura, Akihiko

2013-11-01

The repetition of experience is often necessary to establish long-lasting memory. However, the cellular mechanisms underlying this repetition-dependent consolidation of memory remain unclear. We previously observed in organotypic slice cultures of the rodent hippocampus that repeated inductions of long-term potentiation (LTP) led to a slowly developing long-lasting synaptic enhancement coupled with synaptogenesis. We also reported that repeated inductions of long-term depression (LTD) produced a long-lasting synaptic suppression coupled with synapse elimination. We proposed these phenomena as useful in vitro models for analyzing repetition-dependent consolidation. Here, we hypothesized that the enhancement and suppression are mediated by the brain-derived neurotrophic factor (BDNF)-TrkB signaling pathway and the proBDNF-p75NTR pathway, respectively. When we masked the respective pathways, reversals of the enhancement and suppression resulted. These results suggest the alternative activation of the p75NTR pathway by BDNF under TrkB-masking conditions and of the TrkB pathway by proBDNF under p75NTR-masking conditions, thus supporting the aforementioned hypothesis.

NASA Propulsion Sub-System Concept Studies and Risk Reduction Activities for Resource Prospector Lander

Science.gov (United States)

Trinh, Huu P.

2015-01-01

NASA's exploration roadmap is focused on developing technologies and performing precursor missions to advance the state of the art for eventual human missions to Mars. One of the key components of this roadmap is various robotic missions to Near-Earth Objects, the Moon, and Mars to fill in some of the strategic knowledge gaps. The Resource Prospector (RP) project is one of these robotic precursor activities in the roadmap. RP is a multi-center and multi-institution project to investigate the polar regions of the Moon in search of volatiles. The mission is rated Class D and is approximately 10 days, assuming a five day direct Earth to Moon transfer. Because of the mission cost constraint, a trade study of the propulsion concepts was conducted with a focus on available low-cost hardware for reducing cost in development, while technical risk, system mass, and technology advancement requirements were also taken into consideration. The propulsion system for the lander is composed of a braking stage providing a high thrust to match the lander's velocity with the lunar surface and a lander stage performing the final lunar descent. For the braking stage, liquid oxygen (LOX) and liquid methane (LCH4) propulsion systems, derived from the Morpheus experimental lander, and storable bi-propellant systems, including the 4th stage Peacekeeper (PK) propulsion components and Space Shuttle orbital maneuvering engine (OME), and a solid motor were considered for the study. For the lander stage, the trade study included miniaturized Divert Attitude Control System (DACS) thrusters (Missile Defense Agency (MDA) heritage), their enhanced thruster versions, ISE-100 and ISE-5, and commercial-off-the-shelf (COTS) hardware. The lowest cost configuration of using the solid motor and the PK components while meeting the requirements was selected. The reference concept of the lander is shown in Figure 1. In the current reference configuration, the solid stage is the primary provider of delta

Simultaneous and Sequential Integration by Cre/loxP Site-Specific Recombination in Saccharomyces cerevisiae.

Science.gov (United States)

Choi, Ho-Jung; Kim, Yeon-Hee

2018-05-28

A Cre/ loxP -δ-integration system was developed to allow sequential and simultaneous integration of a multiple gene expression cassette in Saccharomyces cerevisiae . To allow repeated integrations, the reusable Candida glabrata MARKER ( CgMARKER ) carrying loxP sequences was used, and the integrated CgMARKER was efficiently removed by inducing Cre recombinase. The XYLP and XYLB genes encoding endoxylanase and β-xylosidase, respectively, were used as model genes for xylan metabolism in this system, and the copy number of these genes was increased to 15.8 and 16.9 copies/cell, respectively, by repeated integration. This integration system is a promising approach for the easy construction of yeast strains with enhanced metabolic pathways through multicopy gene expression.

Selection of combined water electrolysis and resistojet propulsion for Space Station Freedom

Science.gov (United States)

Schmidt, George R.

1988-01-01

An analytical rationale is presented for the configuration of the NASA Space Station's two-element propulsion system, and attention is given to the cost benefits accruing to this system over the Space Station's service life. The principal system element uses gaseous oxygen and hydrogen obtained through water electrolysis to furnish attitude control, backup attitude control, and contingency maneuvering. The secondary element uses resistojets to augment Space Station reboost through the acceleration of waste gases in the direction opposite the Station's flight path.

A decay heat removal methodology for reuseable orbital transfer vehicles

Science.gov (United States)

McDaniel, Patrick J.; Perkins, David R.

1992-07-01

Operation of a nuclear thermal rocket(NTR) as the propulsion system for a reusable orbital transfer vehicle has been considered. This application is the most demanding in terms of designing a multiple restart capability for an NTR. The requirements on a NTR cooling system associated with the nuclear decay heat stored during operation have been evaluated, specifically for a Particle Bed Reactor(PBR) configuration. A three mode method of operation has been identified as required to adequately remove the nuclear decay heat.

Nuclear thermal rocket workshop reference system Rover/NERVA

International Nuclear Information System (INIS)

Borowski, S.K.

1991-01-01

The Rover/NERVA engine system is to be used as a reference, against which each of the other concepts presented in the workshop will be compared. The following topics are reviewed: the operational characteristics of the nuclear thermal rocket (NTR); the accomplishments of the Rover/NERVA programs; and performance characteristics of the NERVA-type systems for both Mars and lunar mission applications. Also, the issues of ground testing, NTR safety, NASA's nuclear propulsion project plans, and NTR development cost estimates are briefly discussed

Nuclear Thermal Propulsion: Past, Present, and a Look Ahead

Science.gov (United States)

Borowski, Stanley K.

2014-01-01

NTR: High thrust high specific impulse (2 x LOXLH2 chemical) engine uses high power density fission reactor with enriched uranium fuel as thermal power source. Reactor heat is removed using H2 propellant which is then exhausted to produce thrust. Conventional chemical engine LH2 tanks, turbo pumps, regenerative nozzles and radiation-cooled shirt extensions used -- NTR is next evolutionary step in high performance liquid rocket engines.

Self-excising Cre/mutant lox marker recycling system for multiple gene integrations and consecutive gene deletions in Aspergillus oryzae.

Science.gov (United States)

Zhang, Silai; Ban, Akihiko; Ebara, Naoki; Mizutani, Osamu; Tanaka, Mizuki; Shintani, Takahiro; Gomi, Katsuya

2017-04-01

In this study, we developed a self-excising Cre/loxP-mediated marker recycling system with mutated lox sequences to introduce a number of biosynthetic genes into Aspergillus oryzae. To construct the self-excising marker cassette, both the selectable marker, the Aspergillus nidulans adeA gene, and the Cre recombinase gene (cre), conditionally expressed by the xylanase-encoding gene promoter, were designed to be located between the mutant lox sequences, lox66 and lox71. However, construction of the plasmid failed, possibly owing to a slight expression of cre downstream of the fungal gene promoter in Escherichia coli. Hence, to avoid the excision of the cassette in E. coli, a 71-bp intron of the A. oryzae xynG2 gene was inserted into the cre gene. The A. oryzae adeA deletion mutant was transformed with the resulting plasmid in the presence of glucose, and the transformants were cultured in medium containing xylose as the sole carbon source. PCR analysis of genomic DNA from resultant colonies revealed the excision of both the marker and Cre expression construct, indicating that the self-excising marker cassette was efficient at removing the selectable marker. Using the marker recycling system, hyperproduction of kojic acid could be achieved in A. oryzae by the introduction of two genes that encode oxidoreductase and transporter. Furthermore, we also constructed an alternative marker recycling cassette bearing the A. nidulans pyrithiamine resistant gene (ptrA) as a dominant selectable marker. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

NADE (p75NTR-associated cell death executor) suppresses cellular growth in vivo.

Science.gov (United States)

Tong, Xiangjun; Xie, Dong; Roth, Wilfried; Reed, John; Koeffler, H Phillip

2003-06-01

NADE, a p75NTR (low-affinity neurotrophin receptor p75) -associated cell death executor, was initially cloned from a human ovarian granulosa cell cDNA library, as an unknown protein with the name, pHGR74. It was reported to mediate nerve growth factor-induced apoptosis. We independently isolated human NADE (pHGR74) from breast cancer cell lines. Expression of NADE in various human cancer cell lines, and human and murine tissues was examined. NADE was highly expressed in human endocrine-related organs and embryotic murine tissues. Forced expression of NADE in CHO (Chinese hamster ovary) cells and MDA-MB-231 human breast cancer cells had little effect on the growth of the cells in vitro, while it dramatically suppressed cellular growth in vivo. We used the yeast two-hybrid system to search for NADE binding protein. Dynactin was identified as a candidate. The p75NTR was not found in this assay and did not co-immunoprecipitate with human NADE. Furthermore, the cells stably transfected with NADE did not respond to NGF or TNF. Thus, human and murine NADE appear to have different functions.

Use of Cre/loxP recombination to swap cell binding motifs on the adenoviral capsid protein IX

International Nuclear Information System (INIS)

Poulin, Kathy L.; Tong, Grace; Vorobyova, Olga; Pool, Madeline; Kothary, Rashmi; Parks, Robin J.

2011-01-01

We used Cre/loxP recombination to swap targeting ligands present on the adenoviral capsid protein IX (pIX). A loxP-flanked sequence encoding poly-lysine (pK-binds heparan sulfate proteoglycans) was engineered onto the 3'-terminus of pIX, and the resulting fusion protein allowed for routine virus propagation. Growth of this virus on Cre-expressing cells removed the pK coding sequence, generating virus that could only infect through alternative ligands, such as a tyrosine kinase receptor A (TrkA)-binding motif engineered into the capsid fibre protein for enhanced infection of neuronal cells. We used a similar approach to swap the pK motif on pIX for a sequence encoding a single-domain antibody directed towards CD66c for targeted infection of cancer cells; Cre-mediated removal of the pK-coding sequence simultaneously placed the single-domain antibody coding sequence in frame with pIX. Thus, we have developed a simple method to propagate virus lacking native viral tropism but containing cell-specific binding ligands. - Highlights: → We describe a method to grow virus lacking native tropism but containing novel cell-binding ligands. → Cre/loxP recombination was used to modify the adenovirus genome. → A targeting ligand present on capsid protein IX was removed or replaced using recombination. → Cre-loxP was also used to 'swap' the identity of the targeting ligand present on pIX.

Lunar mission design using nuclear thermal rockets

International Nuclear Information System (INIS)

Stancati, M.L.; Collins, J.T.; Borowski, S.K.

1991-01-01

The NERVA-class Nuclear Thermal Rocket (NTR), with performance nearly double that of advanced chemical engines, has long been considered an enabling technology for human missions to Mars. NTR engines address the demanding trip time and payload delivery needs of both cargo-only and piloted flights. But NTR can also reduce the Earth launch requirements for manned lunar missions. First use of NTR for the Moon would be less demanding and would provide a test-bed for early operations experience with this powerful technology. Study of application and design options indicates that NTR propulsion can be integrated with the Space Exploration Initiative scenarios to deliver performance gains while managing controlled, long-term disposal of spent reactors to highly stable orbits

Planetary mission requirements, technology and design considerations for a solar electric propulsion stage

Science.gov (United States)

Cork, M. J.; Hastrup, R. C.; Menard, W. A.; Olson, R. N.

1979-01-01

High energy planetary missions such as comet rendezvous, Saturn orbiter and asteroid rendezvous require development of a Solar Electric Propulsion Stage (SEPS) for augmentation of the Shuttle-IUS. Performance and functional requirements placed on the SEPS are presented. These requirements will be used in evolution of the SEPS design, which must be highly interactive with both the spacecraft and the mission design. Previous design studies have identified critical SEPS technology areas and some specific design solutions which are also presented in the paper.

Electronegative Low-Density Lipoprotein Increases C-Reactive Protein Expression in Vascular Endothelial Cells through the LOX-1 Receptor

OpenAIRE

Chu, Chih-Sheng; Wang, Yu-Chen; Lu, Long-Sheng; Walton, Brian; Yilmaz, H. Ramazan; Huang, Roger Y.; Sawamura, Tatsuya; Dixon, Richard A. F.; Lai, Wen-Ter; Chen, Chu-Huang; Lu, Jonathan

2013-01-01

Objectives Increased plasma C-reactive protein (CRP) levels are associated with the occurrence and severity of acute coronary syndrome. We investigated whether CRP can be generated in vascular endothelial cells (ECs) after exposure to the most electronegative subfraction of low-density lipoprotein (LDL), L5, which is atherogenic to ECs. Because L5 and CRP are both ligands for the lectin-like oxidized LDL receptor-1 (LOX-1), we also examined the role of LOX-1. Methods and Results Plasma LDL sa...

Propulsion Systems Panel deliberations

Science.gov (United States)

Bianca, Carmelo J.; Miner, Robert; Johnston, Lawrence M.; Bruce, R.; Dennies, Daniel P.; Dickenson, W.; Dreshfield, Robert; Karakulko, Walt; Mcgaw, Mike; Munafo, Paul M.

1993-01-01

The Propulsion Systems Panel was established because of the specialized nature of many of the materials and structures technology issues related to propulsion systems. This panel was co-chaired by Carmelo Bianca, MSFC, and Bob Miner, LeRC. Because of the diverse range of missions anticipated for the Space Transportation program, three distinct propulsion system types were identified in the workshop planning process: liquid propulsion systems, solid propulsion systems and nuclear electric/nuclear thermal propulsion systems.

Blocking p75 (NTR) receptors alters polyinnervationz of neuromuscular synapses during development.

Science.gov (United States)

Garcia, Neus; Tomàs, Marta; Santafe, Manel M; Lanuza, Maria A; Besalduch, Nuria; Tomàs, Josep

2011-09-01

High-resolution immunohistochemistry shows that the receptor protein p75(NTR) is present in the nerve terminal, muscle cell, and glial Schwann cell at the neuromuscular junction (NMJ) of postnatal rats (P4-P6) during the synapse elimination period. Blocking the receptor with the antibody anti-p75-192-IgG (1-5 μg/ml, 1 hr) results in reduced endplate potentials (EPPs) in mono- and polyinnervated synapses ex vivo, but the mean number of functional inputs per NMJ does not change for as long as 3 hr. Incubation with exogenous brain-derived neurotrophic factor (BDNF) for 1 hr (50 nM) resulted in a significant increase in the size of the EPPs in all nerve terminals, and preincubation with anti-p75-192-IgG prevented this potentiation. Long exposure (24 hr) in vivo of the NMJs to the antibody anti-p75-192-IgG (1-2 μg/ml) results in a delay of postnatal synapse elimination and even some regrowth of previously withdrawn axons, but also in some acceleration of the morphologic maturation of the postsynaptic nicotinic acetylcholine receptor (nAChR) clusters. The results indicate that p75(NTR) is involved in both ACh release and axonal retraction during postnatal axonal competition and synapse elimination. Copyright © 2011 Wiley-Liss, Inc.

Essential role for zinc-triggered p75NTR activation in preconditioning neuroprotection.

Science.gov (United States)

Lee, Jin-Yeon; Kim, Yu-Jin; Kim, Tae-Youn; Koh, Jae-Young; Kim, Yang-Hee

2008-10-22

Ischemic preconditioning (PC) of the brain is a phenomenon by which mild ischemic insults render neurons resistant to subsequent strong insults. Key steps in ischemic PC of the brain include caspase-3 activation and poly(ADP-ribose) polymerase-1 (PARP-1) cleavage, but upstream events have not been clearly elucidated. We have tested whether endogenous zinc is required for ischemic PC of the brain in rats. Mild, transient zinc accumulation was observed in certain neurons after ischemic PC. Moreover, intraventricular administration of CaEDTA during ischemic PC abrogated both zinc accumulation and the protective effect against subsequent full ischemia. To elucidate the mechanism of the zinc-triggered PC (Zn PC) effect, cortical cultures were exposed to sublethal levels of zinc, and 18 h later to lethal levels of zinc or NMDA. Zn PC exhibited the characteristic features of ischemic PC, including caspase-3 activation, PARP-1 cleavage, and HSP70 induction, all of which are crucial for subsequent neuroprotection against NMDA or zinc toxicity. HSP70 induction was necessary for protection, as it halted caspase-3 activation before apoptosis. Interestingly, in both Zn PC in vitro and ischemic PC in vivo, p75(NTR) was necessary for neuroprotection. These results suggest that caspase-3 activation during ischemic PC, a necessary event for subsequent neuroprotection, may result from mild zinc accumulation and the consequent p75(NTR) activation in neurons.

Arabidopsis CPR5 independently regulates seed germination and postgermination arrest of development through LOX pathway and ABA signaling.

Directory of Open Access Journals (Sweden)

Guilan Gao

Full Text Available The phytohormone abscisic acid (ABA and the lipoxygenases (LOXs pathway play important roles in seed germination and seedling growth and development. Here, we reported on the functional characterization of Arabidopsis CPR5 in the ABA signaling and LOX pathways. The cpr5 mutant was hypersensitive to ABA in the seed germination, cotyledon greening and root growth, whereas transgenic plants overexpressing CPR5 were insensitive. Genetic analysis demonstrated that CPR5 gene may be located downstream of the ABI1 in the ABA signaling pathway. However, the cpr5 mutant showed an ABA independent drought-resistant phenotype. It was also found that the cpr5 mutant was hypersensitive to NDGA and NDGA treatment aggravated the ABA-induced delay in the seed germination and cotyledon greening. Taken together, these results suggest that the CPR5 plays a regulatory role in the regulation of seed germination and early seedling growth through ABA and LOX pathways independently.

The mechanism of long non-coding RNA MEG3 for neurons apoptosis caused by hypoxia: mediated by miR-181b-12/15-LOX signaling pathway

Directory of Open Access Journals (Sweden)

Xiaomin Liu

2016-09-01

Full Text Available Objective: lncRNAs are recently thought to play a significant role in cellular homeostasis during pathological process of diseases by competing inhibiting miRNA function. The aim of present study was to assess the function of long non-coding RNA (lncRNA MEG3 and its functional interaction with microRNA-181b in cerebral ischemic infarct of mice and hypoxia-induced neurons apoptosis. Methods: To address this question, we performed the experiments with in vivo middle cerebral artery occlusion (MCAO mice model and in vitro oxygen-glucose deprivation (OGD-cultured neuronal HT22 cell line. Relative expression of MEG3, miR-181b and 12/15-LOX (lipoxygenase mRNA was determined using quantitative RT-PCR. Western blot was used to evaluate 12/15-LOX protein expression. TUNEL assay was performed to assess cell apoptosis.Results: In both MCAO mice and OGD-cultured HT22 cell, ischemia or hypoxia treatment results in a time-dependent increase in MEG3 and 12/15-LOX expression and decrease in miR-181b expression. Knockdown of MEG3 contributes to attenuation of hypoxia-induced apoptosis of HT22 cell. Also, expression level of MEG3 negatively correlated with miR-181b expression and positively correlated with 12/15-LOX expression. In contrary to MEG3, miR-181b overexpression attenuated hypoxia-induced HT22 cell apoptosis, as well as suppressed hypoxia-induced increase in 12/15-LOX expression. By luciferase reporter assay, we concluded that miR-181b directly binds to 12/15-LOX 3’-UTR, thereby negatively regulates 12/15-LOX expression. Conclusion: Our data suggested that long non-coding RNA MEG3 functions as a competing endogenous RNA for miR-181b to regulate 12/15-LOX expression in middle cerebral artery occlusion-induced ischemic infarct of brain nerve cells.

Propulsion Laboratory

Data.gov (United States)

Federal Laboratory Consortium — The Propulsion Lab simulates field test conditions in a controlled environment, using standardized or customized test procedures. The Propulsion Lab's 11 cells can...

LOX Gene Transcript Accumulation in Olive (Olea europaea L. Fruits at Different Stages of Maturation: Relationship between Volatile Compounds, Environmental Factors, and Technological Treatments for Oil Extraction

Directory of Open Access Journals (Sweden)

Innocenzo Muzzalupo

2012-01-01

Full Text Available The quality of olive oil is influenced by genetic and environmental factors and by the maturation state of drupes, but it is equally affected by technological treatments of the process. This work investigates the possible correlation between olive LOX gene transcript accumulation, evaluated in fruits collected at different stages of maturation, and chemical biomarkers of its activity. During olive fruit ripening, the same genotype harvested from two different farms shows a positive linear trend between LOX relative transcript accumulation and the content of volatile compounds present in the olive oil aroma. Interestingly, a negative linear trend was observed between LOX relative transcript accumulation and the content of volatile compounds present in the olive pastes obtained from olive fruits with and without malaxation. The changes in the olive LOX transcript accumulation reveal its environmental regulation and suggest differential physiological functions for the LOXs.

Recent Advances in Airframe-Propulsion Concepts with Distributed Propulsion

OpenAIRE

Isikveren , A.T.; Seitz , A.; Bijewitz , J.; Hornung , M.; Mirzoyan , A.; Isyanov , A.; Godard , J.L.; Stückl , S.; Van Toor , J.

2014-01-01

International audience; This paper discusses design and integration associated with distributed propulsion as a means of providing motive power for future aircraft concepts. The technical work reflects activities performed within a European Commission funded Framework 7 project entitled Distributed Propulsion and Ultra-high By-Pass Rotor Study at Aircraft Level, or, DisPURSAL. In this instance, the approach of distributed propulsion includes one unique solution that integrates the fuselage wi...

Cholinergic Degeneration and Alterations in the TrkA and p75NTR Balance as a Result of Pro-NGF Injection into Aged Rats

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Ashley M. Fortress

2011-01-01

Full Text Available Learning and memory impairments occurring with Alzheimer's disease (AD are associated with degeneration of the basal forebrain cholinergic neurons (BFCNs. BFCNs extend their axons to the hippocampus where they bind nerve growth factor (NGF which is retrogradely transported to the cell body. While NGF is necessary for BFCN survival and function via binding to the high-affinity receptor TrkA, its uncleaved precursor, pro-NGF has been proposed to induce neurodegeneration via binding to the p75NTR and its coreceptor sortilin. Basal forebrain TrkA and NGF are downregulated with aging while pro-NGF is increased. Given these data, the focus of this paper was to determine a mechanism for how pro-NGF accumulation may induce BFCN degeneration. Twenty-four hours after a single injection of pro-NGF into hippocampus, we found increased hippocampal p75NTR levels, decreased hippocampal TrkA levels, and cholinergic degeneration. The data suggest that the increase in p75NTR with AD may be mediated by elevated pro-NGF levels as a result of decreased cleavage, and that pro-NGF may be partially responsible for age-related degenerative changes observed in the basal forebrain. This paper is the first in vivo evidence that pro-NGF can affect BFCNs and may do so by regulating expression of p75NTR neurotrophin receptors.

Evaluation of 12-Lipoxygenase (12-LOX and Plasminogen Activator Inhibitor 1 (PAI-1 as Prognostic Markers in Prostate Cancer

Directory of Open Access Journals (Sweden)

Tomasz Gondek

2014-01-01

Full Text Available In carcinoma of prostate, a causative role of platelet 12-lipoxygenase (12-LOX and plasminogen activator inhibitor 1 (PAI-1 for tumor progression has been firmly established in tumor and/or adjacent tissue. Our goal was to investigate if 12-LOX and/or PAI-1 in patient’s plasma could be used to predict outcome of the disease. The study comprised 149 patients (age 70±9 divided into two groups: a study group with carcinoma confirmed by positive biopsy of prostate (n=116 and a reference group (n=33 with benign prostatic hyperplasia (BPH. The following parameters were determined by the laboratory test in plasma or platelet-rich plasma: protein level of 12-LOX, PAI-1, thromboglobulin (TGB, prostate specific antigen (PSA, C-reactive protein (CRP, hemoglobin (HGB, and hematocrit (HCT, as well as red (RBC and white blood cells (WBC, number of platelets (PLT, international normalized ratio of blood clotting (INR, and activated partial thromboplastin time (APTT. The only difference of significance was noticed in the concentration of 12-LOX in platelet rich plasma, which was lower in cancer than in BPH group. Standardization to TGB and platelet count increases the sensitivity of the test that might be used as a biomarker to assess risk for prostate cancer in periodically monitored patients.

Saturn V First Stage S-1C LOX Fuel Tanks

Science.gov (United States)

1960-01-01

This photograph shows the Saturn V assembled LOX (Liquid Oxygen) and fuel tanks ready for transport from the Manufacturing Engineering Laboratory at Marshall Space Flight Center in Huntsville, Alabama. The tanks were then shipped to the launch site at Kennedy Space Center for a flight. The towering 363-foot Saturn V was a multi-stage, multi-engine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.

Cre recombinase activity is inhibited in vivo but not ex vivo by a mutation in the asymmetric spacer region of the distal loxP site.

Science.gov (United States)

Arguello, Tania; Moraes, Carlos T

2015-11-01

The cre/loxP recombination system is a valuable tool used to generate tissue specific genomic rearrangements in mouse models. The deletion of a region of interest flanked by two loxP sites is accomplished by the recombinase (cre) enzyme, which binds to the inverted repeat segments of two loxP sites and recognition of a conserved TA sequence in the asymmetric central spacer region "ATAACTTCGTATA -NNNTANNN-TATACGAAGTTAT. In vivo, we found that a single T to C mutation at position 4 of the central spacer region in the distal (3') loxP site, completely inhibited the recombination reaction in two conditional mouse models. These mice were generated using a mitochondrial methionyl-tRNA formyltransferase (Mtfmt) gene targeted construct and cre transgene under the control of tissue-specific promoters: calcium/calmodulin-dependent kinase II alpha (Camk2a-cre) and myosin light polypeptide 1 (Myl1-cre). Surprisingly, transient transfection of a plasmid expressing cre in dermal fibroblasts derived from the same mutant floxed Mtfmt((loxP/loxP)) mice line, successfully deleted the region of interest. This study demonstrates the sequence specificity required in vivo, the possibility of bypassing this limitation by expressing high levels of cre recombinase ex vivo and raises concerns related to the quality control of large scale production of gene targeted constructs and mice. genesis 53:695-700, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

The Ion Propulsion System for the Solar Electric Propulsion Technology Demonstration Mission

Science.gov (United States)

Herman, Daniel A.; Santiago, Walter; Kamhawi, Hani; Polk, James E.; Snyder, John Steven; Hofer, Richard R.; Parker, J. Morgan

2015-01-01

The Asteroid Redirect Robotic Mission is a candidate Solar Electric Propulsion Technology Demonstration Mission whose main objectives are to develop and demonstrate a high-power solar electric propulsion capability for the Agency and return an asteroidal mass for rendezvous and characterization in a companion human-crewed mission. The ion propulsion system must be capable of operating over an 8-year time period and processing up to 10,000 kg of xenon propellant. This high-power solar electric propulsion capability, or an extensible derivative of it, has been identified as a critical part of an affordable, beyond-low-Earth-orbit, manned-exploration architecture. Under the NASA Space Technology Mission Directorate the critical electric propulsion and solar array technologies are being developed. The ion propulsion system being co-developed by the NASA Glenn Research Center and the Jet Propulsion Laboratory for the Asteroid Redirect Vehicle is based on the NASA-developed 12.5 kW Hall Effect Rocket with Magnetic Shielding (HERMeS0 thruster and power processing technologies. This paper presents the conceptual design for the ion propulsion system, the status of the NASA in-house thruster and power processing activity, and an update on flight hardware.

Coordination and propulsion and non-propulsion phases in 100 meter breaststroke swimming.

Science.gov (United States)

Strzała, Marek; Krężałek, Piotr; Kucia-Czyszczoń, Katarzyna; Ostrowski, Andrzej; Stanula, Arkadiusz; Tyka, Anna K; Sagalara, Andrzej

2014-01-01

The main purpose of this study was to analyze the coordination, propulsion and non-propulsion phases in the 100 meter breaststroke race. Twenty-seven male swimmers (15.7 ± 1.98 years old) with the total body length (TBL) of 247.0 ± 10.60 [cm] performed an all-out 100 m breaststroke bout. The bouts were recorded with an underwater camera installed on a portable trolley. The swimming kinematic parameters, stroke rate (SR) and stroke length (SL), as well as the coordination indices based on propulsive or non-propulsive movement phases of the arms and legs were distinguished. Swimming speed (V100surface breast) was associated with SL (R = 0.41, p study were measured using partial correlations with controlled age. SL interplayed negatively with the limbs propulsive phase Overlap indicator (R = -0.46, p propulsion Glide indicator. The propulsion in-sweep (AP3) phase of arms and their non-propulsion partial air recovery (ARair) phase interplayed with V100surface breast (R = 0.51, p < 0.05 and 0.48 p < 0.05) respectively, displaying the importance of proper execution of this phase (AP3) and in reducing the resistance recovery phases in consecutive ones.

CRISPR/Cas9-loxP-Mediated Gene Editing as a Novel Site-Specific Genetic Manipulation Tool.

Science.gov (United States)

Yang, Fayu; Liu, Changbao; Chen, Ding; Tu, Mengjun; Xie, Haihua; Sun, Huihui; Ge, Xianglian; Tang, Lianchao; Li, Jin; Zheng, Jiayong; Song, Zongming; Qu, Jia; Gu, Feng

2017-06-16

Cre-loxP, as one of the site-specific genetic manipulation tools, offers a method to study the spatial and temporal regulation of gene expression/inactivation in order to decipher gene function. CRISPR/Cas9-mediated targeted genome engineering technologies are sparking a new revolution in biological research. Whether the traditional site-specific genetic manipulation tool and CRISPR/Cas9 could be combined to create a novel genetic tool for highly specific gene editing is not clear. Here, we successfully generated a CRISPR/Cas9-loxP system to perform gene editing in human cells, providing the proof of principle that these two technologies can be used together for the first time. We also showed that distinct non-homologous end-joining (NHEJ) patterns from CRISPR/Cas9-mediated gene editing of the targeting sequence locates at the level of plasmids (episomal) and chromosomes. Specially, the CRISPR/Cas9-mediated NHEJ pattern in the nuclear genome favors deletions (64%-68% at the human AAVS1 locus versus 4%-28% plasmid DNA). CRISPR/Cas9-loxP, a novel site-specific genetic manipulation tool, offers a platform for the dissection of gene function and molecular insights into DNA-repair pathways. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Nuclear propulsion for orbital transfer

International Nuclear Information System (INIS)

Beale, G.A.; Lawrence, T.J.

1989-01-01

The state of the art in nuclear propulsion for orbital transfer is discussed. Cryogenic propulsion, electric propulsion, solar-thermal propulsion and direct nuclear propulsion are examined in this context. New technologies with exceptional promise are addressed, emphasizing the particle test bed nuclear engine

Mechanism of transient force augmentation varying with two distinct timescales for interacting vortex rings

Science.gov (United States)

Fu, Zhidong; Qin, Suyang; Liu, Hong

2014-01-01

The dynamics of dual vortex ring flows is studied experimentally and numerically in a model system that consists of a piston-cylinder apparatus. The flows are generated by double identical strokes which have the velocity profile characterized by the sinusoidal function of half the period. By calculating the total wake impulse in two strokes in the experiments, it is found that the average propulsive force increases by 50% in the second stroke for the sufficiently small stroke length, compared with the first stroke. In the numerical simulations, two types of transient force augmentation are revealed, there being the transient force augmentation for the small stroke lengths and the absolute transient force augmentation for the large stroke lengths. The relative transient force augmentation increases to 78% for L/D = 1, while the absolute transient force augmentation for L/D = 4 is twice as much as that for L/D = 1. Further investigation demonstrates that the force augmentation is attributed to the interaction between vortex rings, which induces transport of vortex impulse and more evident fluid entrainment. The critical situation of vortex ring separation is defined and indicated, with vortex spacing falling in a narrow gap when the stroke lengths vary. A new model is proposed concerning the limiting process of impulse, further suggesting that apart from vortex formation timescale, vortex spacing should be interpreted as an independent timescale to reflect the dynamics of vortex interaction.

Utility of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) in the postmortem diagnosis of ischemic heart disease.

Science.gov (United States)

Takasu, Shojiro; Matsumoto, Sari; Kanto, Yuko; Iwadate, Kimiharu

2018-04-01

Ischemic heart disease (IHD) is a major cause of death in developed countries. Postmortem IHD diagnosis using biochemical markers is difficult because of the postmortem changes. In the present study, we investigated the utility of soluble lectin-like low-density lipoprotein receptor-1 (sLOX-1) in body fluids obtained from forensic autopsy cases. We measured pericardial fluid, urine, and serum sLOX-1 levels; these samples were obtained from medicolegal autopsy cases (n = 149, postmortem interval fluid and urine of patients with acute IHD had higher sLOX-1 levels (p fluid and urine samples obtained postmortem are useful markers of acute IHD. Copyright © 2018 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Propulsion for CubeSats

Science.gov (United States)

Lemmer, Kristina

2017-05-01

At present, very few CubeSats have flown in space featuring propulsion systems. Of those that have, the literature is scattered, published in a variety of formats (conference proceedings, contractor websites, technical notes, and journal articles), and often not available for public release. This paper seeks to collect the relevant publically releasable information in one location. To date, only two missions have featured propulsion systems as part of the technology demonstration. The IMPACT mission from the Aerospace Corporation launched several electrospray thrusters from Massachusetts Institute of Technology, and BricSAT-P from the United States Naval Academy had four micro-Cathode Arc Thrusters from George Washington University. Other than these two missions, propulsion on CubeSats has been used only for attitude control and reaction wheel desaturation via cold gas propulsion systems. As the desired capability of CubeSats increases, and more complex missions are planned, propulsion is required to accomplish the science and engineering objectives. This survey includes propulsion systems that have been designed specifically for the CubeSat platform and systems that fit within CubeSat constraints but were developed for other platforms. Throughout the survey, discussion of flight heritage and results of the mission are included where publicly released information and data have been made available. Major categories of propulsion systems that are in this survey are solar sails, cold gas propulsion, electric propulsion, and chemical propulsion systems. Only systems that have been tested in a laboratory or with some flight history are included.

Effect of workload setting on propulsion technique in handrim wheelchair propulsion.

Science.gov (United States)

van Drongelen, Stefan; Arnet, Ursina; Veeger, Dirkjan H E J; van der Woude, Lucas H V

2013-03-01

To investigate the influence of workload setting (speed at constant power, method to impose power) on the propulsion technique (i.e. force and timing characteristics) in handrim wheelchair propulsion. Twelve able-bodied men participated in this study. External forces were measured during handrim wheelchair propulsion on a motor driven treadmill at different velocities and constant power output (to test the forced effect of speed) and at power outputs imposed by incline vs. pulley system (to test the effect of method to impose power). Outcome measures were the force and timing variables of the propulsion technique. FEF and timing variables showed significant differences between the speed conditions when propelling at the same power output (p propulsion technique parameters despite an overall constant power output. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

Distributed Propulsion Vehicles

Science.gov (United States)

Kim, Hyun Dae

2010-01-01

Since the introduction of large jet-powered transport aircraft, the majority of these vehicles have been designed by placing thrust-generating engines either under the wings or on the fuselage to minimize aerodynamic interactions on the vehicle operation. However, advances in computational and experimental tools along with new technologies in materials, structures, and aircraft controls, etc. are enabling a high degree of integration of the airframe and propulsion system in aircraft design. The National Aeronautics and Space Administration (NASA) has been investigating a number of revolutionary distributed propulsion vehicle concepts to increase aircraft performance. The concept of distributed propulsion is to fully integrate a propulsion system within an airframe such that the aircraft takes full synergistic benefits of coupling of airframe aerodynamics and the propulsion thrust stream by distributing thrust using many propulsors on the airframe. Some of the concepts are based on the use of distributed jet flaps, distributed small multiple engines, gas-driven multi-fans, mechanically driven multifans, cross-flow fans, and electric fans driven by turboelectric generators. This paper describes some early concepts of the distributed propulsion vehicles and the current turboelectric distributed propulsion (TeDP) vehicle concepts being studied under the NASA s Subsonic Fixed Wing (SFW) Project to drastically reduce aircraft-related fuel burn, emissions, and noise by the year 2030 to 2035.

High-Payoff Space Transportation Design Approach with a Technology Integration Strategy

Science.gov (United States)

McCleskey, C. M.; Rhodes, R. E.; Chen, T.; Robinson, J.

2011-01-01

A general architectural design sequence is described to create a highly efficient, operable, and supportable design that achieves an affordable, repeatable, and sustainable transportation function. The paper covers the following aspects of this approach in more detail: (1) vehicle architectural concept considerations (including important strategies for greater reusability); (2) vehicle element propulsion system packaging considerations; (3) vehicle element functional definition; (4) external ground servicing and access considerations; and, (5) simplified guidance, navigation, flight control and avionics communications considerations. Additionally, a technology integration strategy is forwarded that includes: (a) ground and flight test prior to production commitments; (b) parallel stage propellant storage, such as concentric-nested tanks; (c) high thrust, LOX-rich, LOX-cooled first stage earth-to-orbit main engine; (d) non-toxic, day-of-launch-loaded propellants for upper stages and in-space propulsion; (e) electric propulsion and aero stage control.

Centralized versus distributed propulsion

Science.gov (United States)

Clark, J. P.

1982-01-01

The functions and requirements of auxiliary propulsion systems are reviewed. None of the three major tasks (attitude control, stationkeeping, and shape control) can be performed by a collection of thrusters at a single central location. If a centralized system is defined as a collection of separated clusters, made up of the minimum number of propulsion units, then such a system can provide attitude control and stationkeeping for most vehicles. A distributed propulsion system is characterized by more numerous propulsion units in a regularly distributed arrangement. Various proposed large space systems are reviewed and it is concluded that centralized auxiliary propulsion is best suited to vehicles with a relatively rigid core. These vehicles may carry a number of flexible or movable appendages. A second group, consisting of one or more large flexible flat plates, may need distributed propulsion for shape control. There is a third group, consisting of vehicles built up from multiple shuttle launches, which may be forced into a distributed system because of the need to add additional propulsion units as the vehicles grow. The effects of distributed propulsion on a beam-like structure were examined. The deflection of the structure under both translational and rotational thrusts is shown as a function of the number of equally spaced thrusters. When two thrusters only are used it is shown that location is an important parameter. The possibility of using distributed propulsion to achieve minimum overall system weight is also examined. Finally, an examination of the active damping by distributed propulsion is described.

Mobile Collaborative Augmented Reality: The Augmented Stroll

OpenAIRE

Renevier , Philippe; Nigay , Laurence

2001-01-01

International audience; The paper focuses on Augmented Reality systems in which interaction with the real world is augmented by the computer, the task being performed in the real world. We first define what mobile AR systems, collaborative AR systems and finally mobile and collaborative AR systems are. We then present the augmented stroll and its software design as one example of a mobile and collaborative AR system. The augmented stroll is applied to Archaeology in the MAGIC (Mobile Augmente...

Design and Activation of a LOX/GH Chemical Steam Generator

Science.gov (United States)

Saunders, G. P.; Mulkey, C. A.; Taylor, S. A.

2009-01-01

The purpose of this paper is to give a detailed description of the design and activation of the LOX/GH fueled chemical steam generator installed in Cell 2 of the E3 test facility at Stennis Space Center, MS (SSC). The steam generator uses a liquid oxygen oxidizer with gaseous hydrogen fuel. The combustion products are then quenched with water to create steam at pressures from 150 to 450 psig at temperatures from 350 to 750 deg F (from saturation to piping temperature limits).

LOX/hydrocarbon rocket engine analytical design methodology development and validation. Volume 2: Appendices

Science.gov (United States)

Niiya, Karen E.; Walker, Richard E.; Pieper, Jerry L.; Nguyen, Thong V.

1993-05-01

This final report includes a discussion of the work accomplished during the period from Dec. 1988 through Nov. 1991. The objective of the program was to assemble existing performance and combustion stability models into a usable design methodology capable of designing and analyzing high-performance and stable LOX/hydrocarbon booster engines. The methodology was then used to design a validation engine. The capabilities and validity of the methodology were demonstrated using this engine in an extensive hot fire test program. The engine used LOX/RP-1 propellants and was tested over a range of mixture ratios, chamber pressures, and acoustic damping device configurations. This volume contains time domain and frequency domain stability plots which indicate the pressure perturbation amplitudes and frequencies from approximately 30 tests of a 50K thrust rocket engine using LOX/RP-1 propellants over a range of chamber pressures from 240 to 1750 psia with mixture ratios of from 1.2 to 7.5. The data is from test configurations which used both bitune and monotune acoustic cavities and from tests with no acoustic cavities. The engine had a length of 14 inches and a contraction ratio of 2.0 using a 7.68 inch diameter injector. The data was taken from both stable and unstable tests. All combustion instabilities were spontaneous in the first tangential mode. Although stability bombs were used and generated overpressures of approximately 20 percent, no tests were driven unstable by the bombs. The stability instrumentation included six high-frequency Kistler transducers in the combustion chamber, a high-frequency Kistler transducer in each propellant manifold, and tri-axial accelerometers. Performance data is presented, both characteristic velocity efficiencies and energy release efficiencies, for those tests of sufficient duration to record steady state values.

Nuclear electric propulsion: An integral part of NASA's nuclear propulsion project

International Nuclear Information System (INIS)

Stone, J.R.

1992-01-01

NASA has initiated a technology program to establish the readiness of nuclear propulsion technology for the Space Exploration Initiative (SEI). This program was initiated with a very modest effort identified with nuclear thermal propulsion (NTP); however, nuclear electric propulsion (NEP) is also an integral part of this program and builds upon NASA's Base Research and Technology Program in power and electric propulsion as well as the SP-100 space nuclear power program. Although the Synthesis Group On America's SEI has identified NEP only as an option for cargo missions, recent studies conducted by NASA-Lewis show that NEP offers the potential for early manned Mars missions as well. Lower power NEP is also of current interest for outer planetary robotic missions. Current plans are reviewed for the overall nuclear propulsion project, with emphasis on NEP and those elements of NTP program which have synergism with NEP

Development of Augmented Spark Impinging Igniter System for Methane Engines

Science.gov (United States)

Marshall, William M.; Osborne, Robin J.; Greene, Sandra E.

2017-01-01

The Lunar Cargo Transportation and Landing by Soft Touchdown (Lunar CATALYST) program is establishing multiple no-funds-exchanged Space Act Agreement (SAA) partnerships with U.S. private sector entities. The purpose of this program is to encourage the development of robotic lunar landers that can be integrated with U.S. commercial launch capabilities to deliver payloads to the lunar surface. NASA can share technology and expertise under the SAA for the benefit of the CATALYST partners. MSFC seeking to vacuum test Augmented Spark Impinging (ASI) igniter with methane and new exciter units to support CATALYST partners and NASA programs. ASI has previously been used/tested successfully at sea-level, with both O2/CH4 and O2/H2 propellants. Conventional ignition exciter systems historically experienced corona discharge issues in vacuum. Often utilized purging or atmospheric sealing on high voltage lead to remedy. Compact systems developed since PCAD could eliminate the high-voltage lead and directly couple the exciter to the spark igniter. MSFC developed Augmented Spark Impinging (ASI) igniter. Successfully used in several sea-level test programs. Plasma-assisted design. Portion of ox flow is used to generate hot plasma. Impinging flows downstream of plasma. Additional fuel flow down torch tube sleeve for cooling near stoichiometric torch flame. Testing done at NASA GRC Altitude Combustion Stand (ACS) facility 2000-lbf class facility with altitude simulation up to around 100,000 ft. (0.2 psia [10 Torr]) via nitrogen driven ejectors. Propellant conditioning systems can provide temperature control of LOX/CH4 up to test article.

Manual wheelchair propulsion patterns on natural surfaces during start-up propulsion.

Science.gov (United States)

Koontz, Alicia M; Roche, Bailey M; Collinger, Jennifer L; Cooper, Rory A; Boninger, Michael L

2009-11-01

To classify propulsion patterns over surfaces encountered in the natural environment during start-up and compare selected biomechanical variables between pattern types. Case series. National Veterans Wheelchair Games, Minneapolis, MN, 2005. Manual wheelchair users (N=29). Subjects pushed their wheelchairs from a resting position over high-pile carpet, over linoleum, and up a ramp with a 5 degrees incline while propulsion kinematics and kinetics were recorded with a motion capture system and an instrumented wheel. Three raters classified the first 3 strokes as 1 of 4 types on each surface: arc, semicircular (SC), single looping over propulsion (SL), and double looping over propulsion (DL). The Fisher exact test was used to assess pattern changes between strokes and surface type. A multiple analysis of variance test was used to compare peak and average resultant force and moment about the hub, average wheel velocity, stroke frequency, contact angle, and distance traveled between stroke patterns. SL was the most common pattern used during start-up propulsion (44.9%), followed by arc (35.9%), DL (14.1%), and SC (5.1%). Subjects who dropped their hands below the rim during recovery achieved faster velocities and covered greater distances (.016propulsion patterns is a difficult task that should use multiple raters. In addition, propulsion patterns change during start-up, with an arc pattern most prevalent initially. The biomechanical findings in this study agree with current clinical guidelines that recommend training users to drop the hand below the pushrim during recovery.

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

Energy Technology Data Exchange (ETDEWEB)

Nam, Seung Hyun; Venneri, Paolo; Kim, Yong Hee; Lee, Jeong Ik; Chang, Soon Heung; Jeong, Yong Hoon [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2015-10-15

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MW{sub th} and an electricity generation mode of 100 kW{sub th}, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

International Nuclear Information System (INIS)

Nam, Seung Hyun; Venneri, Paolo; Kim, Yong Hee; Lee, Jeong Ik; Chang, Soon Heung; Jeong, Yong Hoon

2015-01-01

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MW th and an electricity generation mode of 100 kW th , equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics

Innovative concept for an ultra-small nuclear thermal rocket utilizing a new moderated reactor

Directory of Open Access Journals (Sweden)

Seung Hyun Nam

2015-10-01

Full Text Available Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER, for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MWth and an electricity generation mode of 100 kWth, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and

Operational Issues in the Development of a Cost-Effective Reusable LOX/LH2 Engine

Science.gov (United States)

Ballard, Richard O.

2005-01-01

Contents include the following: SLI initiated under NASA Research Announcement (NRA) 8-30. Strategic Objectives. Make spaceflight safer (1 in 10000 mission LOV). Make spaceflight cheaper ($1000/lb payload). Two prototype LOX/LH2 engine systems funded under Cycle-1 of NRA8-30. COBRA (Pratt & Whitney / Aerojet). RS-83 (Rocketdyne).

The SMPR for the naval propulsion; Les RPMP pour la propulsion navale

Energy Technology Data Exchange (ETDEWEB)

Gauducheau, B. [Technicatome, Centre d' Etudes Nucleaires de Saclay, 91 - Gif sur Yvette (France)

2002-07-01

The first controlled application of the fissile energy was the american nuclear reactor for the ship propulsion. Since the sixties, the France begun researches to secure the independence of its nuclear propulsion program. The historical aspects, the french program management and the perspectives of the ship nuclear propulsion, are discussed in this paper. (A.L.B.)

Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence

Directory of Open Access Journals (Sweden)

R. Xu

2015-08-01

Full Text Available Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB and p75 neurotrophin receptor (p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory, at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG, and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4. Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence

International Nuclear Information System (INIS)

Xu, R.; Duan, S.R.; Zhao, J.W.; Wang, C.Y.

2015-01-01

Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions

Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence

Energy Technology Data Exchange (ETDEWEB)

Xu, R.; Duan, S.R.; Zhao, J.W.; Wang, C.Y. [Neurology Ward of Internal Medicine, First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province (China)

2015-06-23

Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence.

Science.gov (United States)

Xu, R; Duan, S R; Zhao, J W; Wang, C Y

2015-08-01

Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

Viral Cre-LoxP tools aid genome engineering in mammalian cells.

Science.gov (United States)

Sengupta, Ranjita; Mendenhall, Amy; Sarkar, Nandita; Mukherjee, Chandreyee; Afshari, Amirali; Huang, Joseph; Lu, Biao

2017-01-01

Targeted nucleases have transformed genome editing technology, providing more efficient methods to make targeted changes in mammalian genome. In parallel, there is an increasing demand of Cre-LoxP technology for complex genome manipulation such as large deletion, addition, gene fusion and conditional removal of gene sequences at the target site. However, an efficient and easy-to-use Cre-recombinase delivery system remains lacking. We designed and constructed two sets of expression vectors for Cre-recombinase using two highly efficient viral systems, the integrative lentivirus and non-integrative adeno associated virus. We demonstrate the effectiveness of those methods in Cre-delivery into stably-engineered HEK293 cells harboring LoxP-floxed red fluorescent protein (RFP) and puromycin (Puro) resistant reporters. The delivered Cre recombinase effectively excised the floxed RFP-Puro either directly or conditionally, therefore validating the function of these molecular tools. Given the convenient options of two selections markers, these viral-based systems offer a robust and easy-to-use tool for advanced genome editing, expanding complicated genome engineering to a variety of cell types and conditions. We have developed and functionally validated two viral-based Cre-recombinase delivery systems for efficient genome manipulation in various mammalian cells. The ease of gene delivery with the built-in reporters and inducible element enables live cell monitoring, drug selection and temporal knockout, broadening applications of genome editing.

Virtual Dual inhibition of COX-2 / 5-LOX enzymes based on binding properties of alpha-amyrins, the anti-inflammatory compound as a promising anti-cancer drug

Science.gov (United States)

Ranjbar, Mohammad Mehdi; Assadolahi, Vahideh; Yazdani, Mohsen; Nikaein, Donya; Rashidieh, Behnam

2016-01-01

Hydro-alcoholic fruit extract of Cordia myxa was considerably effective on curing acute inflammation in mouse model. Previous studies suggested significant anti-inflammatory activities as well as potential anticancer agent of α-amyrins in seeds. Inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipooxygenase (5-LOX) is significant in cancer prevention and therapeutics although this inhibition with chemo-drugs has its own side-effects. It is shown that these enzymes pathways are related to several cancers including colon, breast and lung cancer. This study was conducted based on Cordia species' α-amyrins as a safer natural anti-cancer compound for inhibition of COX-2 and 5-LOX enzymes by molecular docking. The X-ray crystal structure of COX2 / 5-LOX enzymes and α-amyrins was retrieved and energetically minimized respectively. The binding site and surface of enzymes were detected. Docking studies were performed by AutoDock 4.2 using Lamarckian genetic algorithm (LGA). Finally drug likeness, molecular pharmacokinetic properties and toxicity of α-amyrins was calculated. Molecular Docking revealed hydrogen and hydrophobic interactions between α-amyrins with both active sites of COX-2 and 5-LOX enzymes. Interestingly, it covalently bonded to Fe cofactor of 5-LOX enzyme and chelated this molecule. Base on binding energies (∆G) α-amyrin has more inhibitory effects on 5-LOX (-10.45 Kcal/mol) than COX-2 (-8.02 Kcal/mol). Analysis of molecular pharmacokinetic parameters suggested that α-amyrins complied with most sets of Lipinski's rules, and so it could be a suitable ligand for docking studies. Eventually, bioactivity score showed α-amyrins possess considerable biological activities as nuclear receptor, enzyme inhibitor, GPCR and protease inhibitor ligand. These results clearly demonstrate that α-amyrins could act as potential highly selective COX-/5-LOX inhibitor. Also, it is a safe compound in comparison with classical non-steroidal anti-inflammatory drugs (NSAIDs

Localization of brain-derived neurotrophic factor, neurotrophin-4, tropomyosin-related kinase b receptor, and p75 NTR receptor by high-resolution immunohistochemistry on the adult mouse neuromuscular junction.

Science.gov (United States)

Garcia, Neus; Tomàs, Marta; Santafe, Manel M; Lanuza, M Angel; Besalduch, Nuria; Tomàs, Josep

2010-03-01

Neurotrophins and their receptors, the trk receptor tyrosine kinases (trks) and p75(NTR), are differentially expressed among the cell types that make up synapses. It is important to determine the precise location of these molecules involved in neurotransmission. Here we use immunostaining and Western blotting to study the localization and expression of neurotrophin brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) and the receptors tropomyosin-related kinase b (trkB) and p75(NTR) at the adult neuromuscular junction. Our confocal immunofluorescence results on the whole mounts of the mouse Levator auris longus muscle and on semithin cross-sections showed that BDNF, NT-4, trkB, and p75(NTR) were localized on the three cells in the neuromuscular synapse (motor axons, post-synaptic muscle and Schwann cells).

Targeting the LOX/hypoxia axis reverses many of the features that make pancreatic cancer deadly

DEFF Research Database (Denmark)

Miller, Bryan W; Morton, Jennifer P; Pinese, Mark

2015-01-01

of a cure, but most will die of recurrent or metastatic disease. Hence, preventing metastatic disease in these patients would be of significant benefit. Using principal component analysis (PCA), we identified a LOX/hypoxia signature associated with poor patient survival in resectable patients. We found...

The USAF Electric Propulsion Program

National Research Council Canada - National Science Library

Spores, Ronald

1999-01-01

...: Propulsion Directorate and Air Force Office of Scientific Research (AFOSR). The Propulsion Directorate conducts electric propulsion efforts in basic research, engineering development, and space experiments...

Advanced Propulsion Study

National Research Council Canada - National Science Library

Davis, Eric

2004-01-01

... that show promise of leading to a major advance in Earth-to-orbit (ETO) propulsion. The study also reviewed and evaluated a select number of credible far-term breakthrough propulsion physics concepts pertaining...

NASA's Propulsion Research Laboratory

Science.gov (United States)

2004-01-01

The grand opening of NASA's new, world-class laboratory for research into future space transportation technologies located at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, took place in July 2004. The state-of-the-art Propulsion Research Laboratory (PRL) serves as a leading national resource for advanced space propulsion research. Its purpose is to conduct research that will lead to the creation and development of innovative propulsion technologies for space exploration. The facility is the epicenter of the effort to move the U.S. space program beyond the confines of conventional chemical propulsion into an era of greatly improved access to space and rapid transit throughout the solar system. The laboratory is designed to accommodate researchers from across the United States, including scientists and engineers from NASA, the Department of Defense, the Department of Energy, universities, and industry. The facility, with 66,000 square feet of useable laboratory space, features a high degree of experimental capability. Its flexibility allows it to address a broad range of propulsion technologies and concepts, such as plasma, electromagnetic, thermodynamic, and propellant propulsion. An important area of emphasis is the development and utilization of advanced energy sources, including highly energetic chemical reactions, solar energy, and processes based on fission, fusion, and antimatter. The Propulsion Research Laboratory is vital for developing the advanced propulsion technologies needed to open up the space frontier, and sets the stage of research that could revolutionize space transportation for a broad range of applications.

TALEN-Based Mutagenesis of Lipoxygenase LOX3 Enhances the Storage Tolerance of Rice (Oryza sativa) Seeds.

Science.gov (United States)

Ma, Lei; Zhu, Fugui; Li, Zhenwei; Zhang, Jianfu; Li, Xin; Dong, Jiangli; Wang, Tao

2015-01-01

The deterioration of rice grain reduces the quality of rice, resulting in serious economic losses for farmers. Lipoxygenases (LOXs) catalyze the dioxygenation of polyunsaturated fatty acids with at least one cis,cis-1,4-pentadiene to form hydroperoxide, which is a major factor influencing seed longevity and viability. Recently, genome editing, an essential tool employed in reverse genetics, has been used experimentally to investigate basic plant biology or to modify crop plants for the improvement of important agricultural traits. In this study, we performed targeted mutagenesis in rice using transcription activator-like effector nucleases (TALENs) to improve seed storability. A modified ligation-independent cloning method (LIC) was employed to allow for the quick and efficient directional insertion of TALEN monomer modules into destination vectors used in plants. We demonstrated the feasibility and flexibility of the technology by developing a set of modular vectors for genome editing. After construction and validation, the TALEN pairs were used to create stable transgenic rice lines via Agrobacterium-mediated transformation. One heterozygous mutant (4%) was recovered from 25 transgenic NPTII-resistant lines, and the mutation was transmitted to the next generation. Further molecular and protein level experiments verified LOX3 deficiency and demonstrated the improvement of seed storability. Our work provides a flexible genome editing tool for improving important agronomic traits, as well as direct evidence that Lox3 has only a limited impact on seed longevity.

TALEN-Based Mutagenesis of Lipoxygenase LOX3 Enhances the Storage Tolerance of Rice (Oryza sativa Seeds.

Directory of Open Access Journals (Sweden)

Lei Ma

Full Text Available The deterioration of rice grain reduces the quality of rice, resulting in serious economic losses for farmers. Lipoxygenases (LOXs catalyze the dioxygenation of polyunsaturated fatty acids with at least one cis,cis-1,4-pentadiene to form hydroperoxide, which is a major factor influencing seed longevity and viability. Recently, genome editing, an essential tool employed in reverse genetics, has been used experimentally to investigate basic plant biology or to modify crop plants for the improvement of important agricultural traits. In this study, we performed targeted mutagenesis in rice using transcription activator-like effector nucleases (TALENs to improve seed storability. A modified ligation-independent cloning method (LIC was employed to allow for the quick and efficient directional insertion of TALEN monomer modules into destination vectors used in plants. We demonstrated the feasibility and flexibility of the technology by developing a set of modular vectors for genome editing. After construction and validation, the TALEN pairs were used to create stable transgenic rice lines via Agrobacterium-mediated transformation. One heterozygous mutant (4% was recovered from 25 transgenic NPTII-resistant lines, and the mutation was transmitted to the next generation. Further molecular and protein level experiments verified LOX3 deficiency and demonstrated the improvement of seed storability. Our work provides a flexible genome editing tool for improving important agronomic traits, as well as direct evidence that Lox3 has only a limited impact on seed longevity.

[Discover potential inhibitors of 5-LOX and LTA4H from Rhei Radix et Rhizoma, Notopterygii Rhizoma et Radix and Genitana Macrophyllae Radix based on molecular simulation methods].

Science.gov (United States)

Gu, Yu; Zhang, Xu; Chen, Yan-Kun; Zhao, Bo-Wen; Zhang, Yan-Ling

2017-12-01

5-lipoxygenase (5-LOX) and leukotriene A4 hydrolase (LTA4H), as the major targets of 5-LOX branch in the arachidonic acid (AA) metabolic pathway, play an important role in the treatment of inflammation. Rhei Radix et Rhizoma, Notopterygii Rhizoma et Radix and Genitana Macrophyllae Radix have clear anti-inflammation activities. In this paper, the targets of 5-LOX and LTA4H were used as the research carrier, and Hiphop module in DS4.0 (Discovery studio) was used to construct ingredients database for preliminary screening of three traditional Chinese medicines based on target inhibitor pharmacophore, so as to obtain 5-LOX and LTA4H potential active ingredients. The ingredients obtained in initial pharmacophore screening were further screened by using CDOCKER module, and the screening rules were established based on the score of initial compound and the key amino acids to obtain 12 potential 5-LOX inhibitors and 7 potential LTA4H inhibitors. To be more specific, the potential 5-LOX inhibitors included 6 ingredients in Rhei Radix et Rhizoma, such as procyanidins B2-3,3'-O-double gallate and revandchinone 2; four ingredients in notopterygium, such as dodecanoic acid and so on. On the other hand, potential LTA4H inhibitors included revandchinone 1, revandchinone 4 in Rhei Radix et Rhizoma, tridecanoic acid, tetracosanoic acid and methyl eicosanoate in Notopterygii Rhizoma et Radix, montanic acid methyl ester and N-docosanoyl-O-aminobenzoate in Genitana Macrophyllae Radix and so on. The molecular simulation methods were highly efficient and time-saving to obtain the potential inhibitors of 5-LOX and LTA4H, which could provide assistance for discovering the chemical quality indicators of anti-inflammatory efficacy of three Chinese herbs, and may be helpful to promote the whole-process quality control of three Chinese herbs. Copyright© by the Chinese Pharmaceutical Association.

Liquid Rocket Engine Testing Overview

Science.gov (United States)

Rahman, Shamim

2005-01-01

Contents include the following: Objectives and motivation for testing. Technology, Research and Development Test and Evaluation (RDT&E), evolutionary. Representative Liquid Rocket Engine (LRE) test compaigns. Apollo, shuttle, Expandable Launch Vehicles (ELV) propulsion. Overview of test facilities for liquid rocket engines. Boost, upper stage (sea-level and altitude). Statistics (historical) of Liquid Rocket Engine Testing. LOX/LH, LOX/RP, other development. Test project enablers: engineering tools, operations, processes, infrastructure.

Expression of the nifA gene of Herbaspirillum seropedicae: role of the NtrC and NifA binding sites and of the -24/-12 promoter element.

Science.gov (United States)

Souza, E M; Pedrosa, F O; Rigo, L U; Machado, H B; Yates, M G

2000-06-01

The nifA promoter of Herbaspirillum seropedicae contains potential NtrC, NifA and IHF binding sites together with a -12/-24 sigma(N)-dependent promoter. This region has now been investigated by deletion mutagenesis for the effect of NtrC and NifA on the expression of a nifA::lacZ fusion. A 5' end to the RNA was identified at position 641, 12 bp downstream from the -12/-24 promoter. Footprinting experiments showed that the G residues at positions -26 and -9 are hypermethylated, and that the region from -10 to +10 is partially melted under nitrogen-fixing conditions, confirming that this is the active nifA promoter. In H. seropedicae nifA expression from the sigma(N)-dependent promoter is repressed by fixed nitrogen but not by oxygen and is probably activated by the NtrC protein. NifA protein is apparently not essential for nifA expression but it can still bind the NifA upstream activating sequence.

Comparison of Aero-Propulsive Performance Predictions for Distributed Propulsion Configurations

Science.gov (United States)

Borer, Nicholas K.; Derlaga, Joseph M.; Deere, Karen A.; Carter, Melissa B.; Viken, Sally A.; Patterson, Michael D.; Litherland, Brandon L.; Stoll, Alex M.

2017-01-01

NASA's X-57 "Maxwell" flight demonstrator incorporates distributed electric propulsion technologies in a design that will achieve a significant reduction in energy used in cruise flight. A substantial portion of these energy savings come from beneficial aerodynamic-propulsion interaction. Previous research has shown the benefits of particular instantiations of distributed propulsion, such as the use of wingtip-mounted cruise propellers and leading edge high-lift propellers. However, these benefits have not been reduced to a generalized design or analysis approach suitable for large-scale design exploration. This paper discusses the rapid, "design-order" toolchains developed to investigate the large, complex tradespace of candidate geometries for the X-57. Due to the lack of an appropriate, rigorous set of validation data, the results of these tools were compared to three different computational flow solvers for selected wing and propulsion geometries. The comparisons were conducted using a common input geometry, but otherwise different input grids and, when appropriate, different flow assumptions to bound the comparisons. The results of these studies showed that the X-57 distributed propulsion wing should be able to meet the as-designed performance in cruise flight, while also meeting or exceeding targets for high-lift generation in low-speed flight.

Laser ignition of a multi-injector LOX/methane combustor

Science.gov (United States)

Börner, Michael; Manfletti, Chiara; Hardi, Justin; Suslov, Dmitry; Kroupa, Gerhard; Oschwald, Michael

2018-06-01

This paper reports the results of a test campaign of a laser-ignited combustion chamber with 15 shear coaxial injectors for the propellant combination LOX/methane. 259 ignition tests were performed for sea-level conditions. The igniter based on a monolithic ceramic laser system was directly attached to the combustion chamber and delivered 20 pulses with individual pulse energies of {33.2 ± 0.8 mJ } at 1064 nm wavelength and 2.3 ns FWHM pulse length. The applicability, reliability, and reusability of this ignition technology are demonstrated and the associated challenges during the start-up process induced by the oxygen two-phase flow are formulated. The ignition quality and pressure dynamics are evaluated using 14 dynamic pressure sensors distributed both azimuthally and axially along the combustion chamber wall. The influence of test sequencing on the ignition process is briefly discussed and the relevance of the injection timing of the propellants for the ignition process is described. The flame anchoring and stabilization process, as monitored using an optical probe system close to the injector faceplate connected to photomultiplier elements, is presented. For some of the ignition tests, non-uniform anchoring was detected with no influence onto the anchoring at steady-state conditions. The non-uniform anchoring can be explained by the inhomogeneous, transient injection of the two-phase flow of oxygen across the faceplate. This characteristic is verified by liquid nitrogen cold flow tests that were recorded by high-speed imaging. We conclude that by adapting the ignition sequence, laser ignition by optical breakdown of the propellants within the shear layer of a coaxial shear injector is a reliable ignition technology for LOX/methane combustors without significant over-pressure levels.

Laser ignition of a multi-injector LOX/methane combustor

Science.gov (United States)

Börner, Michael; Manfletti, Chiara; Hardi, Justin; Suslov, Dmitry; Kroupa, Gerhard; Oschwald, Michael

2018-02-01

This paper reports the results of a test campaign of a laser-ignited combustion chamber with 15 shear coaxial injectors for the propellant combination LOX/methane. 259 ignition tests were performed for sea-level conditions. The igniter based on a monolithic ceramic laser system was directly attached to the combustion chamber and delivered 20 pulses with individual pulse energies of {33.2 ± 0.8 mJ } at 1064 nm wavelength and 2.3 ns FWHM pulse length. The applicability, reliability, and reusability of this ignition technology are demonstrated and the associated challenges during the start-up process induced by the oxygen two-phase flow are formulated. The ignition quality and pressure dynamics are evaluated using 14 dynamic pressure sensors distributed both azimuthally and axially along the combustion chamber wall. The influence of test sequencing on the ignition process is briefly discussed and the relevance of the injection timing of the propellants for the ignition process is described. The flame anchoring and stabilization process, as monitored using an optical probe system close to the injector faceplate connected to photomultiplier elements, is presented. For some of the ignition tests, non-uniform anchoring was detected with no influence onto the anchoring at steady-state conditions. The non-uniform anchoring can be explained by the inhomogeneous, transient injection of the two-phase flow of oxygen across the faceplate. This characteristic is verified by liquid nitrogen cold flow tests that were recorded by high-speed imaging. We conclude that by adapting the ignition sequence, laser ignition by optical breakdown of the propellants within the shear layer of a coaxial shear injector is a reliable ignition technology for LOX/methane combustors without significant over-pressure levels.

Systematic analysis of rat 12/15-lipoxygenase enzymes reveals critical role for spinal eLOX3 hepoxilin synthase activity in inflammatory hyperalgesia

OpenAIRE

Gregus, Ann M.; Dumlao, Darren S.; Wei, Spencer C.; Norris, Paul C.; Catella, Laura C.; Meyerstein, Flore G.; Buczynski, Matthew W.; Steinauer, Joanne J.; Fitzsimmons, Bethany L.; Yaksh, Tony L.; Dennis, Edward A.

2013-01-01

Previously, we observed significant increases in spinal 12-lipoxygenase (LOX) metabolites, in particular, hepoxilins, which contribute to peripheral inflammation-induced tactile allodynia. However, the enzymatic sources of hepoxilin synthase (HXS) activity in rats remain elusive. Therefore, we overexpressed each of the 6 rat 12/15-LOX enzymes in HEK-293T cells and measured by LC-MS/MS the formation of HXB3, 12-HETE, 8-HETE, and 15-HETE from arachidonic acid (AA) at baseline and in the presenc...

Brief review on pulse laser propulsion

Science.gov (United States)

Yu, Haichao; Li, Hanyang; Wang, Yan; Cui, Lugui; Liu, Shuangqiang; Yang, Jun

2018-03-01

Pulse laser propulsion (PLP) is an advanced propulsion concept can be used across a variety of fields with a wide range of applications. PLP reflects superior payload as well as decreased launch costs in comparison with other conventional methods of producing thrust, such as chemical propulsion or electric propulsion. Numerous researchers have attempted to exploit the potential applications of PLP. This paper first reviews concepts relevant to PLP, including the propulsion modes, breakdown regimes, and propulsion efficiency; the propulsion targets for different materials with the pulse laser are then discussed in detail, including the propulsion of solid and liquid microspheres. PLP applications such as the driven microsatellite, target surface particle removal, and orbital debris removal are also discussed. Although the PLP has been applied to a variety of fields, further research is yet warranted to establish its application in the aerospace field.

NASA Electric Propulsion System Studies

Science.gov (United States)

Felder, James L.

2015-01-01

An overview of NASA efforts in the area of hybrid electric and turboelectric propulsion in large transport. This overview includes a list of reasons why we are looking at transmitting some or all of the propulsive power for the aircraft electrically, a list of the different types of hybrid-turbo electric propulsion systems, and the results of 4 aircraft studies that examined different types of hybrid-turbo electric propulsion systems.

Nuclear-microwave-electric propulsion

International Nuclear Information System (INIS)

Nordley, G.D.; Brown, W.C.

1986-01-01

Electric propulsion can move more mass through space than chemical propulsion by virtue of the higher exhaust velocities achieved by electric propulsion devices. This performance is achieved at the expense of very heavy power sources or very long trip times, which in turn create technical and economic penalties of varying severity. These penalties include: higher operations costs, delayed availability of the payload, and increased exposure to Van Allen Belt radiation. It is proposed to reduce these penalties by physically separating the power source from the propulsion and use microwave energy beaming technology, recently explored and partially developed/tested for Solar Power Satellite concept studies, as an extension cord. This paper summarizes the state of the art of the technology needed for space based beam microwave power cost/performance trades involved with the use beamed microwave/electric propulsion for some typical orbit transfer missions and offers some suggestions for additional work

Towards Pervasive Augmented Reality: Context-Awareness in Augmented Reality.

Science.gov (United States)

Grubert, Jens; Langlotz, Tobias; Zollmann, Stefanie; Regenbrecht, Holger

2017-06-01

Augmented Reality is a technique that enables users to interact with their physical environment through the overlay of digital information. While being researched for decades, more recently, Augmented Reality moved out of the research labs and into the field. While most of the applications are used sporadically and for one particular task only, current and future scenarios will provide a continuous and multi-purpose user experience. Therefore, in this paper, we present the concept of Pervasive Augmented Reality, aiming to provide such an experience by sensing the user's current context and adapting the AR system based on the changing requirements and constraints. We present a taxonomy for Pervasive Augmented Reality and context-aware Augmented Reality, which classifies context sources and context targets relevant for implementing such a context-aware, continuous Augmented Reality experience. We further summarize existing approaches that contribute towards Pervasive Augmented Reality. Based our taxonomy and survey, we identify challenges for future research directions in Pervasive Augmented Reality.

Optimum cycle frequencies in hand-rim wheelchair propulsion. Wheelchair propulsion technique

NARCIS (Netherlands)

van der Woude, L H; Veeger, DirkJan (H. E. J.); Rozendal, R H; Sargeant, A J

1989-01-01

To study the effect of different cycle frequencies on cardio-respiratory responses and propulsion technique in hand-rim wheelchair propulsion, experienced wheelchair sportsmen (WS group; n = 6) and non-wheelchair users (NW group; n = 6) performed wheelchair exercise tests on a motor-driven

Effect of workload setting on propulsion technique in handrim wheelchair propulsion

NARCIS (Netherlands)

van Drongelen, Stefan; Arnet, Ursina; Veeger, DirkJan (H E. J); van der Woude, Lucas H. V.

Objective: To investigate the influence of workload setting (speed at constant power, method to impose power) on the propulsion technique (i.e. force and timing characteristics) in handrim wheelchair propulsion. Method: Twelve able-bodied men participated in this study. External forces were measured

Laser Propulsion - Quo Vadis

International Nuclear Information System (INIS)

Bohn, Willy L.

2008-01-01

First, an introductory overview of the different types of laser propulsion techniques will be given and illustrated by some historical examples. Second, laser devices available for basic experiments will be reviewed ranging from low power lasers sources to inertial confinement laser facilities. Subsequently, a status of work will show the impasse in which the laser propulsion community is currently engaged. Revisiting the basic relations leads to new avenues in ablative and direct laser propulsion for ground based and space based applications. Hereby, special attention will be devoted to the impact of emerging ultra-short pulse lasers on the coupling coefficient and specific impulse. In particular, laser sources and laser propulsion techniques will be tested in microgravity environment. A novel approach to debris removal will be discussed with respect to the Satellite Laser Ranging (SRL) facilities. Finally, some non technical issues will be raised aimed at the future prospects of laser propulsion in the international community

Critical Propulsion Components. Volume 1; Summary, Introduction, and Propulsion Systems Studies

Science.gov (United States)

2005-01-01

Several studies have concluded that a supersonic aircraft, if environmentally acceptable and economically viable, could successfully compete in the 21st century marketplace. However, before industry can commit to what is estimated as a 15 to 20 billion dollar investment, several barrier issues must be resolved. In an effort to address these barrier issues, NASA and Industry teamed to form the High-Speed Research (HSR) program. As part of this program, the Critical Propulsion Components (CPC) element was created and assigned the task of developing those propulsion component technologies necessary to: (1) reduce cruise emissions by a factor of 10 and (2) meet the ever-increasing airport noise restrictions with an economically viable propulsion system. The CPC-identified critical components were ultra-low emission combustors, low-noise/high-performance exhaust nozzles, low-noise fans, and stable/high-performance inlets. Propulsion cycle studies (coordinated with NASA Langley Research Center sponsored airplane studies) were conducted throughout this CPC program to help evaluate candidate components and select the best concepts for the more complex and larger scale research efforts. The propulsion cycle and components ultimately selected were a mixed-flow turbofan (MFTF) engine employing a lean, premixed, prevaporized (LPP) combustor coupled to a two-dimensional mixed compression inlet and a two-dimensional mixer/ejector nozzle. Due to the large amount of material presented in this report, it was prepared in four volumes; Volume 1: Summary, Introduction, and Propulsion System Studies, Volume 2: Combustor, Volume 3: Exhaust Nozzle, and Volume 4: Inlet and Fan/ Inlet Acoustic Team.

The Nuclear Cryogenic Propulsion Stage

Science.gov (United States)

Houts, Michael G.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Broadway, Jeramie W.; Gerrish, Harold P.; Doughty, Glen; Belvin, Anthony; Borowski, Stanley K.; Scott, John

2014-01-01

The fundamental capability of Nuclear Thermal Propulsion (NTP) is game changing for space exploration. A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on NTP could provide high thrust at a specific impulse above 900 s, roughly double that of state of the art chemical engines. Characteristics of fission and NTP indicate that useful first generation systems will provide a foundation for future systems with extremely high performance. The role of the NCPS in the development of advanced nuclear propulsion systems could be analogous to the role of the DC-3 in the development of advanced aviation. Progress made under the NCPS project could help enable both advanced NTP and advanced Nuclear Electric Propulsion (NEP). Nuclear propulsion can be affordable and viable compared to other propulsion systems and must overcome a biased public fear due to hyper-environmentalism and a false perception of radiation and explosion risk.

Cre/lox system to develop selectable marker free transgenic tobacco plants conferring resistance against sap sucking homopteran insect.

Science.gov (United States)

Chakraborti, Dipankar; Sarkar, Anindya; Mondal, Hossain A; Schuermann, David; Hohn, Barbara; Sarmah, Bidyut K; Das, Sampa

2008-10-01

A binary expression vector was constructed containing the insecticidal gene Allium sativum leaf agglutinin (ASAL), and a selectable nptII marker gene cassette, flanked by lox sites. Similarly, another binary vector was developed with the chimeric cre gene construct. Transformed tobacco plants were generated with these two independent vectors. Each of the T(0) lox plants was crossed with T(0) Cre plants. PCR analyses followed by the sequencing of the target T-DNA part of the hybrid T(1) plants demonstrated the excision of the nptII gene in highly precised manner in certain percentage of the T(1) hybrid lines. The frequency of such marker gene excision was calculated to be 19.2% in the hybrids. Marker free plants were able to express ASAL efficiently and reduce the survivability of Myzus persiceae, the deadly pest of tobacco significantly, compared to the control tobacco plants. Results of PCR and Southern blot analyses of some of the T(2) plants detected the absence of cre as well as nptII genes. Thus, the crossing strategy involving Cre/lox system for the excision of marker genes appears to be very effective and easy to execute. Documentation of such marker excision phenomenon in the transgenic plants expressing the important insecticidal protein for the first time has a great significance from agricultural and biotechnological points of view.

Electric vehicle propulsion alternatives

Science.gov (United States)

Secunde, R. R.; Schuh, R. M.; Beach, R. F.

1983-01-01

Propulsion technology development for electric vehicles is summarized. Analytical studies, technology evaluation, and the development of technology for motors, controllers, transmissions, and complete propulsion systems are included.

The genome sequence of the protostome Daphnia pulex encodes respective orthologues of a neurotrophin, a Trk and a p75NTR: Evolution of neurotrophin signaling components and related proteins in the bilateria

Directory of Open Access Journals (Sweden)

Wilson Karen HS

2009-10-01

Full Text Available Abstract Background Neurotrophins and their Trk and p75NTR receptors play an important role in the nervous system. To date, neurotrophins, Trk and p75NTR have only been found concomitantly in deuterostomes. In protostomes, homologues to either neurotrophin, Trk or p75NTR are reported but their phylogenetic relationship to deuterostome neurotrophin signaling components is unclear. Drosophila has neurotrophin homologues called Spätzles (Spz, some of which were recently renamed neurotrophins, but direct proof that these are deuterostome neurotrophin orthologues is lacking. Trks belong to the receptor tyrosine kinase (RTK family and among RTKs, Trks and RORs are closest related. Flies lack Trks but have ROR and ROR-related proteins called NRKs playing a neurotrophic role. Mollusks have so far the most similar proteins to Trks (Lymnaea Trk and Aplysia Trkl but the exact phylogenetic relationship of mollusk Trks to each other and to vertebrate Trks is unknown. p75NTR belongs to the tumor necrosis factor receptor (TNFR superfamily. The divergence of the TNFR families in vertebrates has been suggested to parallel the emergence of the adaptive immune system. Only one TNFR representative, the Drosophila Wengen, has been found in protostomes. To clarify the evolution of neurotrophin signaling components in bilateria, this work analyzes the genome of the crustacean Daphnia pulex as well as new genetic data from protostomes. Results The Daphnia genome encodes a neurotrophin, p75NTR and Trk orthologue together with Trkl, ROR, and NRK-RTKs. Drosophila Spz1, 2, 3, 5, 6 orthologues as well as two new groups of Spz proteins (Spz7 and 8 are also found in the Daphnia genome. Searching genbank and the genomes of Capitella, Helobdella and Lottia reveals neurotrophin signaling components in other protostomes. Conclusion It appears that a neurotrophin, Trk and p75NTR existed at the protostome/deuterostome split. In protostomes, a "neurotrophin superfamily" includes

Fuel Effective Photonic Propulsion

Science.gov (United States)

Rajalakshmi, N.; Srivarshini, S.

2017-09-01

With the entry of miniaturization in electronics and ultra-small light-weight materials, energy efficient propulsion techniques for space travel can soon be possible. We need to go for such high speeds so that the generation’s time long interstellar missions can be done in incredibly short time. Also renewable energy like sunlight, nuclear energy can be used for propulsion instead of fuel. These propulsion techniques are being worked on currently. The recently proposed photon propulsion concepts are reviewed, that utilize momentum of photons generated by sunlight or onboard photon generators, such as blackbody radiation or lasers, powered by nuclear or solar power. With the understanding of nuclear photonic propulsion, in this paper, a rough estimate of nuclear fuel required to achieve the escape velocity of Earth is done. An overview of the IKAROS space mission for interplanetary travel by JAXA, that was successful in demonstrating that photonic propulsion works and also generated additional solar power on board, is provided; which can be used as a case study. An extension of this idea for interstellar travel, termed as ‘Star Shot’, aims to send a nanocraft to an exoplanet in the nearest star system, which could be potentially habitable. A brief overview of the idea is presented.

In-Space Propulsion Technology Program Solar Electric Propulsion Technologies

Science.gov (United States)

Dankanich, John W.

2006-01-01

NASA's In-space Propulsion (ISP) Technology Project is developing new propulsion technologies that can enable or enhance near and mid-term NASA science missions. The Solar Electric Propulsion (SEP) technology area has been investing in NASA s Evolutionary Xenon Thruster (NEXT), the High Voltage Hall Accelerator (HiVHAC), lightweight reliable feed systems, wear testing, and thruster modeling. These investments are specifically targeted to increase planetary science payload capability, expand the envelope of planetary science destinations, and significantly reduce the travel times, risk, and cost of NASA planetary science missions. Status and expected capabilities of the SEP technologies are reviewed in this presentation. The SEP technology area supports numerous mission studies and architecture analyses to determine which investments will give the greatest benefit to science missions. Both the NEXT and HiVHAC thrusters have modified their nominal throttle tables to better utilize diminished solar array power on outbound missions. A new life extension mechanism has been implemented on HiVHAC to increase the throughput capability on low-power systems to meet the needs of cost-capped missions. Lower complexity, more reliable feed system components common to all electric propulsion (EP) systems are being developed. ISP has also leveraged commercial investments to further validate new ion and hall thruster technologies and to potentially lower EP mission costs.

Modeling of Ship Propulsion Performance

DEFF Research Database (Denmark)

Pedersen, Benjamin Pjedsted; Larsen, Jan

2009-01-01

Full scale measurements of the propulsion power, ship speed, wind speed and direction, sea and air temperature, from four different loading conditions has been used to train a neural network for prediction of propulsion power. The network was able to predict the propulsion power with accuracy...

Three-Dimensional Numerical Analysis of LOX/Kerosene Engine Exhaust Plume Flow Field Characteristics

Directory of Open Access Journals (Sweden)

Hong-hua Cai

2017-01-01

Full Text Available Aiming at calculating and studying the flow field characteristics of engine exhaust plume and comparative analyzing the effects of different chemical reaction mechanisms on the engine exhaust plume flow field characteristics, a method considering fully the combustion state influence is put forward, which is applied to exhaust plume flow field calculation of multinozzle engine. On this basis, a three-dimensional numerical analysis of the effects of different chemical reaction mechanisms on LOX/kerosene engine exhaust plume flow field characteristics was carried out. It is found that multistep chemical reaction can accurately describe the combustion process in the LOX/kerosene engine, the average chamber pressure from the calculation is 4.63% greater than that of the test, and the average chamber temperature from the calculation is 3.34% greater than that from the thermodynamic calculation. The exhaust plumes of single nozzle and double nozzle calculated using the global chemical reaction are longer than those using the multistep chemical reaction; the highest temperature and the highest velocity on the plume axis calculated using the former are greater than that using the latter. The important influence of chemical reaction mechanism must be considered in the study of the fixing structure of double nozzle engine on the rocket body.

Theoretical Acoustic Absorber Design Approach for LOX/LCH4 Pintle Injector Rocket Engines

Science.gov (United States)

Candelaria, Jonathan

Liquid rocket engines, or LREs, have served a key role in space exploration efforts. One current effort involves the utilization of liquid oxygen (LOX) and liquid methane (LCH4) LREs to explore Mars with in-situ resource utilization for propellant production. This on-site production of propellant will allow for greater payload allocation instead of fuel to travel to the Mars surface, and refueling of propellants to travel back to Earth. More useable mass yields a greater benefit to cost ratio. The University of Texas at El Paso's (UTEP) Center for Space Exploration and Technology Research Center (cSETR) aims to further advance these methane propulsion systems with the development of two liquid methane - liquid oxygen propellant combination rocket engines. The design of rocket engines, specifically liquid rocket engines, is complex in that many variables are present that must be taken into consideration in the design. A problem that occurs in almost every rocket engine development program is combustion instability, or oscillatory combustion. It can result in the destruction of the rocket, subsequent destruction of the vehicle and compromise the mission. These combustion oscillations can vary in frequency from 100 to 20,000 Hz or more, with varying effects, and occur from different coupling phenomena. It is important to understand the effects of combustion instability, its physical manifestations, how to identify the instabilities, and how to mitigate or dampen them. Linear theory methods have been developed to provide a mathematical understanding of the low- to mid-range instabilities. Nonlinear theory is more complex and difficult to analyze mathematically, therefore no general analytical method that yields a solution exists. With limited resources, time, and the advice of our NASA mentors, a data driven experimental approach utilizing quarter wave acoustic dampener cavities was designed. This thesis outlines the methodology behind the design of an acoustic

ARLearn: augmented reality meets augmented virtuality

NARCIS (Netherlands)

Ternier, Stefaan; Klemke, Roland; Kalz, Marco; Van Ulzen, Patricia; Specht, Marcus

2012-01-01

Ternier, S., Klemke, R., Kalz, M., Van Ulzen, P., & Specht, M. (2012). ARLearn: augmented reality meets augmented virtuality [Special issue]. Journal of Universal Computer Science - Technology for learning across physical and virtual spaces, 18(15), 2143-2164.

Regional gene expression of LOX-1, VCAM-1, and ICAM-1 in aorta of HIV-1 transgenic rats

DEFF Research Database (Denmark)

Hag, Anne Mette Fisker; Kristoffersen, Ulrik Sloth; Pedersen, Sune Folke

2009-01-01

endpoints, studies in animal models could be attractive alternatives. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated gene expression of lectin-like oxidized-low-density-lipoprotein receptor-1 (LOX-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in HIV-1...... transgenic (HIV-1Tg) rats; these genes are all thought to play important roles in early atherogenesis. Furthermore, the plasma level of sICAM-1 was measured. We found that gene expressions of LOX-1 and VCAM-1 were higher in the aortic arch of HIV-1Tg rats compared to controls. Also, the level of sICAM-1......-infection per se may cause atherosclerosis. This transgenic rat model may be a very promising model for further studies of the pathophysiology behind HIV-associated cardiovascular disease....

LOX-1 and Its Splice Variants: A New Challenge for Atherosclerosis and Cancer-Targeted Therapies

Science.gov (United States)

Rizzacasa, Barbara; Morini, Elena; Pucci, Sabina; Murdocca, Michela; Novelli, Giuseppe; Amati, Francesca

2017-01-01

Alternative splicing (AS) is a process in which precursor messenger RNA (pre-mRNA) splicing sites are differentially selected to diversify the protein isoform population. Changes in AS patterns have an essential role in normal development, differentiation and response to physiological stimuli. It is documented that AS can generate both “risk” and “protective” splice variants that can contribute to the pathogenesis of several diseases including atherosclerosis. The main endothelial receptor for oxidized low-density lipoprotein (ox-LDLs) is LOX-1 receptor protein encoded by the OLR1 gene. When OLR1 undergoes AS events, it generates three variants: OLR1, OLR1D4 and LOXIN. The latter lacks exon 5 and two-thirds of the functional domain. Literature data demonstrate a protective role of LOXIN in pathologies correlated with LOX-1 overexpression such as atherosclerosis and tumors. In this review, we summarize recent developments in understanding of OLR1 AS while also highlighting data warranting further investigation of this process as a novel therapeutic target. PMID:28146073

Maturing the M10A 25,000lbf Liquid Oxygen/Methane Broadsword Engine

Data.gov (United States)

National Aeronautics and Space Administration — Masten’s effort will advance development of a full-scale additive manufactured aluminum thrust chamber assembly for a 25,000 lbf LOX/LCH4 dual expander propulsion...

Wheelchairs propulsion analysis: review

Directory of Open Access Journals (Sweden)

Yoshimasa Sagawa Júnior

Full Text Available OBJECTIVES: To analyze aspects related with wheelchair propulsion. MATERIALS AND METHODS: In order to delineate this review the search for information was carried out within electronics databases, using the following descriptors: "wheelchair propulsion", "wheelchair biomechanics" e "wheelchair users". Full papers published in English and French were included in the study. RESULTS: The wheelchair propulsion is a complex movement that requires the execution of repeated bi manual forces applications during a short time period. In this movement high levels of force must be produced due to the bad mechanical performance of the wheelchair. Could be characterized that wheelchair users are not satisfied with their wheelchair, the places are not adapted to their presence and lack of specific criteria for the adjustment of this equipment. The main points to look at are the seat height in relation to elbow flexion (100-120 degrees with his hand in the propulsion rim and tire pressure. The semicircular mode of technique propulsion seems to be more appropriate; in this pattern the wheelchair user returns his hand under the rim after propulsion. Efforts in wheelchairs are high and the incidence of injuries in wheelchair users is high. CONCLUSION: One can conclude that in spite of researchers’ efforts there are still many divergences between topics and methods of evaluation, what makes difficult to apply the experimental results to the wheelchairs users’ daily life.

Ion Beam Propulsion Study

Science.gov (United States)

2008-01-01

The Ion Beam Propulsion Study was a joint high-level study between the Applied Physics Laboratory operated by NASA and ASRC Aerospace at Kennedy Space Center, Florida, and Berkeley Scientific, Berkeley, California. The results were promising and suggested that work should continue if future funding becomes available. The application of ion thrusters for spacecraft propulsion is limited to quite modest ion sources with similarly modest ion beam parameters because of the mass penalty associated with the ion source and its power supply system. Also, the ion source technology has not been able to provide very high-power ion beams. Small ion beam propulsion systems were used with considerable success. Ion propulsion systems brought into practice use an onboard ion source to form an energetic ion beam, typically Xe+ ions, as the propellant. Such systems were used for steering and correction of telecommunication satellites and as the main thruster for the Deep Space 1 demonstration mission. In recent years, "giant" ion sources were developed for the controlled-fusion research effort worldwide, with beam parameters many orders of magnitude greater than the tiny ones of conventional space thruster application. The advent of such huge ion beam sources and the need for advanced propulsion systems for exploration of the solar system suggest a fresh look at ion beam propulsion, now with the giant fusion sources in mind.

Augmented postcard

OpenAIRE

Bernik , Aleš

2012-01-01

The aim of this thesis is the examination of augmented reality technology, which allows us mixing real and virtual elements. Augmented reality is a relatively new technology which is becoming more widespread, thanks to a fairly reasonable price of smart phones. Here we presents the types of augmented reality, the necessary technology and their advantages and disadvantages, its current use in applications, and software for building augmented reality applications. The thesis is mainly focuse...

Alternative propulsion for automobiles

CERN Document Server

Stan, Cornel

2017-01-01

The book presents – based on the most recent research and development results worldwide - the perspectives of new propulsion concepts such as electric cars with batteries and fuel cells, and furthermore plug in hybrids with conventional and alternative fuels. The propulsion concepts are evaluated based on specific power, torque characteristic, acceleration behaviour, specific fuel consumption and pollutant emissions. The alternative fuels are discussed in terms of availability, production, technical complexity of the storage on board, costs, safety and infrastructure. The book presents summarized data about vehicles with electric and hybrid propulsion. The propulsion of future cars will be marked by diversity – from compact electric city cars and range extender vehicles for suburban and rural areas up to hybrid or plug in SUV´s, Pick up´s and luxury class automobiles.

Computational Fluid Dynamics (CFD) applications in rocket propulsion analysis and design

Science.gov (United States)

Mcconnaughey, P. K.; Garcia, R.; Griffin, L. W.; Ruf, J. H.

1993-01-01

Computational Fluid Dynamics (CFD) has been used in recent applications to affect subcomponent designs in liquid propulsion rocket engines. This paper elucidates three such applications for turbine stage, pump stage, and combustor chamber geometries. Details of these applications include the development of a high turning airfoil for a gas generator (GG) powered, liquid oxygen (LOX) turbopump, single-stage turbine using CFD as an integral part of the design process. CFD application to pump stage design has emphasized analysis of inducers, impellers, and diffuser/volute sections. Improvements in pump stage impeller discharge flow uniformity have been seen through CFD optimization on coarse grid models. In the area of combustor design, recent CFD analysis of a film cooled ablating combustion chamber has been used to quantify the interaction between film cooling rate, chamber wall contraction angle, and geometry and their effects of these quantities on local wall temperature. The results are currently guiding combustion chamber design and coolant flow rate for an upcoming subcomponent test. Critical aspects of successful integration of CFD into the design cycle includes a close-coupling of CFD and design organizations, quick turnaround of parametric analyses once a baseline CFD benchmark has been established, and the use of CFD methodology and approaches that address pertinent design issues. In this latter area, some problem details can be simplified while retaining key physical aspects to maintain analytical integrity.

Space transportation propulsion USSR launcher technology, 1990

Science.gov (United States)

1991-01-01

Space transportation propulsion U.S.S.R. launcher technology is discussed. The following subject areas are covered: Energia background (launch vehicle summary, Soviet launcher family) and Energia propulsion characteristics (booster propulsion, core propulsion, and growth capability).

Conditional and inducible transgene expression in endothelial and hematopoietic cells using Cre/loxP and tetracycline-off systems.

Science.gov (United States)

Liu, Ju; Deutsch, Urban; Fung, Iris; Lobe, Corrinne G

2014-11-01

In the present study, the tetracycline-off and Cre/ loxP systems were combined to gain temporal and spatial control of transgene expression. Mice were generated that carried three transgenes: Tie2-tTA, tet-O-Cre and either the ZEG or ZAP reporter. Tie2-tTA directs expression of tetracycline-controlled transactivator (tTA) in endothelial and hematopoietic cells under the control of the Tie2 promoter. Tet-O-Cre produces Cre recombinase from a minimal promoter containing the tet-operator (tetO). ZEG or ZAP contains a strong promoter and a loxP -flanked stop sequence, followed by an enhanced green fluorescence protein (EGFP) or human placental alkaline phosphatase (hPLAP) reporter. In the presence of tetracycline, the tTA transactivator produced by Tie-2-tTA is disabled and Cre is not expressed. In the absence of tetracycline, the tTA binds tet-O-Cre to drive the expression of Cre, which recombines the loxP sites of the ZEG or ZAP transgene and results in reporter gene expression. In the present study, the expression of the ZEG or ZAP reporter genes in embryos and adult animals with and without tetracycline treatment was examined. In the presence of tetracycline, no reporter gene expression was observed. When tetracycline was withdrawn, Cre excision was activated and the reporter genes were detected in endothelial and hematopoietic cells. These results demonstrate that this system may be used to bypass embryonic lethality and access adult phenotypes.

Reactors for nuclear electric propulsion

Energy Technology Data Exchange (ETDEWEB)

Buden, D.; Angelo, J.A. Jr.

1981-01-01

Propulsion is the key to space exploitation and power is the key to propulsion. This paper examines the role of nuclear fission reactors as the primary power source for high specific impulse electric propulsion systems for space missions of the 1980s and 1990s. Particular mission applications include transfer to and a reusable orbital transfer vehicle from low-Earth orbit to geosynchronous orbit, outer planet exploration and reconnaissance missions, and as a versatile space tug supporting lunar resource development. Nuclear electric propulsion is examined as an indispensable component in space activities of the next two decades.

Reactors for nuclear electric propulsion

International Nuclear Information System (INIS)

Buden, D.; Angelo, J.A. Jr.

1981-01-01

Propulsion is the key to space exploitation and power is the key to propulsion. This paper examines the role of nuclear fission reactors as the primary power source for high specific impulse electric propulsion systems for space missions of the 1980s and 1990s. Particular mission applications include transfer to and a reusable orbital transfer vehicle from low-Earth orbit to geosynchronous orbit, outer planet exploration and reconnaissance missions, and as a versatile space tug supporting lunar resource development. Nuclear electric propulsion is examined as an indispensable component in space activities of the next two decades

THE FUTURE OF SPACECRAFT NUCLEAR PROPULSION

OpenAIRE

Jansen, Frank

2014-01-01

This paper summarizes the advantages of space nuclear power and propulsion systems. It describes the actual status of international power level dependent spacecraft nuclear propulsion missions, especially the high power EU-Russian MEGAHIT study including the Russian Megawatt-Class Nuclear Power Propulsion System, the NASA GRC project and the low and medium power EU DiPoP study. Space nuclear propulsion based mission scenarios of these studies are sketched as well.

Conditional Gene Expression in the Mouse Inner Ear Using Cre-loxP

OpenAIRE

Cox, Brandon C.; Liu, Zhiyong; Lagarde, Marcia M. Mellado; Zuo, Jian

2012-01-01

In recent years, there has been significant progress in the use of Cre-loxP technology for conditional gene expression in the inner ear. Here, we introduce the basic concepts of this powerful technology, emphasizing the differences between Cre and CreER. We describe the creation and Cre expression pattern of each Cre and CreER mouse line that has been reported to have expression in auditory and vestibular organs. We compare the Cre expression patterns between Atoh1-CreERTM and Atoh1-CreERT2 a...

Additive Manufacturing of Aerospace Propulsion Components

Science.gov (United States)

Misra, Ajay K.; Grady, Joseph E.; Carter, Robert

2015-01-01

The presentation will provide an overview of ongoing activities on additive manufacturing of aerospace propulsion components, which included rocket propulsion and gas turbine engines. Future opportunities on additive manufacturing of hybrid electric propulsion components will be discussed.

Development of superconducting ship propulsion system

International Nuclear Information System (INIS)

Sakuraba, Junji; Mori, Hiroyuki; Hata, Fumiaki; Sotooka, Koukichi

1991-01-01

When we plan displacement-type monohull high speed vessels, it is difficult to get the hull form with the wave-making resistance minimum, because the stern shape is restricted by arrangement of propulsive machines and shafts. A small-sized and light-weight propulsive machines will reduce the limit to full form design. Superconducting technology will have capability of realizing the small-sized and light-weight propulsion motor. The superconducting electric propulsion system which is composed of superconducting propulsion motors and generators, seems to be an ideal propulsion system for future vehicles. We have constructed a 480 kW superconducting DC homopolar laboratory test motor for developing this propulsion system. The characteristic of this motor is that it has a superconducting field winding and a segmented armature drum. The superconducting field winding which operates in the persistent current mode, is cooled by a condensation heat exchanger and helium refigerating system built into the cryostat of the superconducting field winding. The operating parameters of this motor agreed well with the design parameters. Using the design concepts of this motor, we have conceptually designed a 150,000-200,000 PS superconducting electric propulsive system for a displacement-type monohull high speed ship. (author)

Software To Secure Distributed Propulsion Simulations

Science.gov (United States)

Blaser, Tammy M.

2003-01-01

Distributed-object computing systems are presented with many security threats, including network eavesdropping, message tampering, and communications middleware masquerading. NASA Glenn Research Center, and its industry partners, has taken an active role in mitigating the security threats associated with developing and operating their proprietary aerospace propulsion simulations. In particular, they are developing a collaborative Common Object Request Broker Architecture (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engines

Fusion propulsion systems

International Nuclear Information System (INIS)

Haloulakos, V.E.; Bourque, R.F.

1989-01-01

The continuing and expanding national efforts in both the military and commercial sectors for exploration and utilization of space will require launch, assembly in space, and orbital transfer of large payloads. The currently available delivery systems, utilizing various forms of chemical propulsion, do not have the payload capacity to fulfill the planned missions. National planning documents such as Air Force Project Forecast II and the National Commission on Space Report to the President contain numerous missions and payload delivery schedules that are beyond the present capabilities of the available systems, such as the Space Shuttle and the Expendable Launch Vehicles (ELVs). The need, therefore, is very pressing to design, develop, and deploy propulsion systems that offer a quantum level increase in delivered performance. One such potential system is fusion propulsion. This paper summarizes the result of an Air Force Astronautics Laboratory (AFAL) sponsored study of fusion propulsion conducted by the McDonnell Douglas Astronautics Company (MDAC), and its subcontractor General Atomics This study explored the potential of fusion propulsion for Air Force missions. Fusion fuels and existing confinement concepts were evaluated according to elaborate criteria. Two fuels, deuterium-tritium and deuterium-helium 3 (D- 3 He) were considered worthy of further consideration. D- 3 He was selected as the most attractive for this Air Force study. The colliding translating compact torus confinement concept was evaluated in depth and found to possibly possess the low mass and compactness required. Another possible concept is inertial confinement with the propellant surrounding the target. 5 refs., 5 figs., 8 tabs

Cold Gas Micro Propulsion

NARCIS (Netherlands)

Louwerse, M.C.

2009-01-01

This thesis describes the development of a micro propulsion system. The trend of miniaturization of satellites requires small sized propulsion systems. For particular missions it is important to maintain an accurate distance between multiple satellites. Satellites drift apart due to differences in

Efecto in vitro del D-002 sobre la actividad enzimática de la 5-lipoxigenasa (5-LOX

Directory of Open Access Journals (Sweden)

Yohani Pérez Guerra

2012-06-01

Full Text Available Introducción: el D-002, mezcla de seis alcoholes alifáticos primarios de alto peso molecular purificada de la cera de abejas, ha mostrado efectos antiinflamatorios, sin gastrotoxicidad secundaria, enmodelos experimentales. El tratamiento oral con D-002 reduce las concentraciones de leucotrieno B4 (LTB4 en exudados pleurales de ratas con pleuresía por carragenina, sugiriendo que podría inhibir la actividad enzimática de la 5-lipooxigenasa (5-LOX, si bien los mecanismos de la acción antiinflamatoria del D-002 no habían sido aún explorados. Objetivo: evaluar el efecto in vitro del D-002 sobre la actividad de la 5-LOX, utilizando la fracción citosólica de homogenatos de hígado de ratas. Métodos: las condiciones de ensayo utilizadas fueron las siguientes: fracción citosólica (50 µg de proteína disuelta en solución reguladora borato 0,2 mol/L (pH 9 y ácido linoleico (7,8-250 mmol/L como sustrato, ensayándose muestras paralelas incubadas con Tween-20/H2O (2 % (vehículo, muestras controles, D-002 (0,9-1 000 µg/mL o Lyprinol (500 µg/mL (sustancia de referencia. La actividad enzimática se evaluó mediante el cambio de absorbancia a 234 nm producido por la formación de dienos conjugados y medido en espectrofotómetro UV-visible. Resultados: la adición in vitro del D-002 produjo una inhibición significativa, dependiente de la dosis (r= 0,980; p< 0,001 (IC50= 95,34 µg/mL e incompetitiva de la actividad de la 5-LOX, cuya inhibición máxima (70 % se alcanzó con 500 µg/mL. Conclusiones: con este estudio se demuestra que el D-002 es capaz de inhibir la actividad enzimática de la 5-LOX, efecto que podría explicar, al menos parcialmente, su acción antiinflamatoria en modelos experimentales in vivo.

Efecto in vitro del D-003 sobre la actividad enzimática de la 5-lipoxigenasa (5-LOX

Directory of Open Access Journals (Sweden)

Yohani Pérez Guerra

Full Text Available Introducción: el D-003, mezcla de ácidos alifáticos primarios superiores purificada de la cera de la caña, inhibe la síntesis de colesterol. Trabajos recientes han demostrado que el D-003 resulta efectivo en modelos experimentales de osteoartritis y que inhibe la actividad de las enzimas COX1 y COX2, preferentemente la COX1, sin producir gastrotoxicidad. Ha sido referido que los inhibidores duales de las enzimas COX y 5-LOX presentan efectos antinflamatorios desprovistos de gastrotoxicidad o que incluso, pueden resultar gastroprotectores. De acuerdo con estos antecedentes, el D-003 podría ser un inhibidor dual de dichas enzimas. Objetivo: investigar el efecto in vitro del D-003 sobre la actividad enzimática de la 5-LOX, utilizando la fracción citosólica de leucocitos polimorfonucleares de ratas. Métodos: se utilizaron las condiciones de ensayo siguientes: fracción citosólica (50 µg de proteína disuelta en solución reguladora borato 0,2 mol/L (pH 9 y ácido linoleico (7,8-250 mmol/L como sustrato, ensayándose muestras paralelas incubadas con Tween-20/H2O (2 % (vehículo, D-003 (0,6-6 000 µg/mL o extracto de Perna canaliculus (50 µg/mL (sustancia de referencia. Se evaluó la actividad enzimática mediante el cambio de absorbancia a 234 nm producido por la formación de dienos conjugados y medido en espectrofotómetro UV-visible. Resultados: la adición de D-003 produjo una inhibición dosis dependiente de la actividad enzimática de la 5-LOX (r= 0,975; p< 0,05 (CI50= 23,06 µg/mL in vitro. La magnitud de esta inhibición fue moderada, ya que la inhibición máxima, alcanzada a partir de 1 250 µg/mL, resultó de solo un 30 %. Conclusiones: el estudio demuestra que el D-003 es capaz de inhibir la actividad enzimática de la 5-LOX in vitro, pero moderadamente.

Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

Science.gov (United States)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft.

A Review of Laser Ablation Propulsion

International Nuclear Information System (INIS)

Phipps, Claude; Bohn, Willy; Lippert, Thomas; Sasoh, Akihiro; Schall, Wolfgang; Sinko, John

2010-01-01

Laser Ablation Propulsion is a broad field with a wide range of applications. We review the 30-year history of laser ablation propulsion from the transition from earlier pure photon propulsion concepts of Oberth and Saenger through Kantrowitz's original laser ablation propulsion idea to the development of air-breathing 'Lightcraft' and advanced spacecraft propulsion engines. The polymers POM and GAP have played an important role in experiments and liquid ablation fuels show great promise. Some applications use a laser system which is distant from the propelled object, for example, on another spacecraft, the Earth or a planet. Others use a laser that is part of the spacecraft propulsion system on the spacecraft. Propulsion is produced when an intense laser beam strikes a condensed matter surface and produces a vapor or plasma jet. The advantages of this idea are that exhaust velocity of the propulsion engine covers a broader range than is available from chemistry, that it can be varied to meet the instantaneous demands of the particular mission, and that practical realizations give lower mass and greater simplicity for a payload delivery system. We review the underlying theory, buttressed by extensive experimental data. The primary problem in laser space propulsion theory has been the absence of a way to predict thrust and specific impulse over the transition from the vapor to the plasma regimes. We briefly discuss a method for combining two new vapor regime treatments with plasma regime theory, giving a smooth transition from one regime to the other. We conclude with a section on future directions.

Propulsive efficiency and non- expert swimmers performance

Directory of Open Access Journals (Sweden)

Tiago Barbosa

2009-12-01

Full Text Available Propulsive efficiency is one of the most interesting issues for competitive swimming researchers, has it presents significant relationships with the swimmer’s biophysical behavior and his/her performance. Although propulsive efficiency is a variable that has been quite studied in elite swimmers, there is no research on this issue in young and non-expert swimmers. Thus, the aim of this study was to: (i estimate the propulsive efficiency on non-expert swimmers; (ii identify biomechanical and anthropometrical parameters that are associated with propulsive efficiency; (iii identify the association between the propulsive efficiency and swim performance. Twenty-eight non-expert swimmers participated on this study. It was assessed the propulsive efficiency, biomechanical and anthropometrical parameters, as well as, the swim performance. The propulsive efficiency of non-expert swimmers is lower than data reported in the literature to higher competitive levels swimmers and there are no significant differences between boys and girls. It was also noted that several biomechanical and anthropometrical parameters, as well as, the swim performance are associated with the propulsive efficiency.

Nuclear Thermal Rocket/Vehicle Design Options for Future NASA Missions to the Moon and Mars

Science.gov (United States)

Borowski, Stanley K.; Corban, Robert R.; Mcguire, Melissa L.; Beke, Erik G.

1995-01-01

The nuclear thermal rocket (NTR) provides a unique propulsion capability to planners/designers of future human exploration missions to the Moon and Mars. In addition to its high specific impulse (approximately 850-1000 s) and engine thrust-to-weight ratio (approximately 3-10), the NTR can also be configured as a 'dual mode' system capable of generating electrical power for spacecraft environmental systems, communications, and enhanced stage operations (e.g., refrigeration for long-term liquid hydrogen storage). At present the Nuclear Propulsion Office (NPO) is examining a variety of mission applications for the NTR ranging from an expendable, single-burn, trans-lunar injection (TLI) stage for NASA's First Lunar Outpost (FLO) mission to all propulsive, multiburn, NTR-powered spacecraft supporting a 'split cargo-piloted sprint' Mars mission architecture. Each application results in a particular set of requirements in areas such as the number of engines and their respective thrust levels, restart capability, fuel operating temperature and lifetime, cryofluid storage, and stage size. Two solid core NTR concepts are examined -- one based on NERVA (Nuclear Engine for Rocket Vehicle Application) derivative reactor (NDR) technology, and a second concept which utilizes a ternary carbide 'twisted ribbon' fuel form developed by the Commonwealth of Independent States (CIS). The NDR and CIS concepts have an established technology database involving significant nuclear testing at or near representative operating conditions. Integrated systems and mission studies indicate that clusters of two to four 15 to 25 klbf NDR or CIS engines are sufficient for most of the lunar and Mars mission scenarios currently under consideration. This paper provides descriptions and performance characteristics for the NDR and CIS concepts, summarizes NASA's First Lunar Outpost and Mars mission scenarios, and describes characteristics for representative cargo and piloted vehicles compatible with a

[NRH2 induces cell apoptosis of cerebral tissues around hematomas after intracerebral hemorrhage through up-regulating proNGF, sortilin and p75NTR expressions].

Science.gov (United States)

Zeng, Zhiqing; Liu, Hong; Jiang, Di

2015-04-01

To observe the expressions of neurotrophin receptor homolog 2 (NRH2), nerve growth factor precursor (proNGF), sortilin and neurotrophin receptor p75 (p75NTR) in cerebral tissues around hematomas in the different periods after intracerebral hemorrhage, and explore their relationships to cell apoptosis. The specimens of cerebral tissues around hematomas were collected from the patients undergoing hematoma removal operation after intracerebral hemorrhage. These specimens were divided into four groups, namely ≤ 6 hours, 6-24 hours(including 24 hours), 24-72 hours (including 72 hours) and over 72 hours according to the time from intracerebral hemorrhage to specimen collection. At the same time, 10 brain tissues distant to hemorrhage that dropped in the operative process were collected as a control group. Apoptosis index (AI) was examined in brain cells by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL). The expressions of NRH2, proNGF, sortilin and p75NTR mRNAs and proteins in brain tissues were detected through real-time quantitative PCR and Western blotting, respectively. Also, the expressions of Bcl-2 and Bax in brain tissues were analyzed using Western blotting. In vitro cultured astrocytes of rat cortex were transfected by NRH2 siRNA or scramble siRNA. The expressions of proNGF, sortilin and p75NTR proteins were detected using Western blotting. AI was higher in all groups of hemorrhage for 6 hours or longer than that in control and ≤ 6 hours groups, and AI in the group of 24-72 hours after intracerebral hemorrhage was the highest. However, there was no significant difference in AI between ≤ 6 hours group and control group. With the extension of intracerebral hemorrhage time, the expression levels of proNGF and p75NTR mRNAs and proteins were gradually elevated, reached the peak in 24-72 hours, and maintained a higher level after 72 hours, whereas there were no significant differences in the above indicators

Research Opportunities in Space Propulsion

Science.gov (United States)

Rodgers, Stephen L.

2007-01-01

Rocket propulsion determines the primary characteristics of any space vehicle; how fast and far it can go, its lifetime, and its capabilities. It is the primary factor in safety and reliability and the biggest cost driver. The extremes of heat and pressure produced by propulsion systems push the limits of materials used for manufacturing. Space travel is very unforgiving with little room for errors, and so many things can go wrong with these very complex systems. So we have to plan for failure and that makes it costly. But what is more exciting than the roar of a rocket blasting into space? By its nature the propulsion world is conservative. The stakes are so high at every launch, in terms of payload value or in human life, that to introduce new components to a working, qualified system is extremely difficult and costly. Every launch counts and no risks are tolerated, which leads to the space world's version of Catch-22:"You can't fly till you flown." The last big 'game changer' in propulsion was the use of liquid hydrogen as a fuel. No new breakthrough, low cost access to space system will be developed without new efficient propulsion systems. Because there is no large commercial market driving investment in propulsion, what propulsion research is done is sponsored by government funding agencies. A further difficulty in propulsion technology development is that there are so few new systems flying. There is little opportunity to evolve propulsion technologies and to update existing systems with results coming out of research as there is in, for example, the auto industry. The biggest hurdle to space exploration is getting off the ground. The launch phase will consume most of the energy required for any foreseeable space exploration mission. The fundamental physical energy requirements of escaping earth's gravity make it difficult. It takes 60,000 kJ to put a kilogram into an escape orbit. The vast majority (-97%) of the energy produced by a launch vehicle is used

Propulsion System and Orbit Maneuver Integration in CubeSats: Trajectory Control Strategies Using Micro Ion Propulsion

Science.gov (United States)

Hudson, Jennifer; Martinez, Andres; Petro, Andrew

2015-01-01

The Propulsion System and Orbit Maneuver Integration in CubeSats project aims to solve the challenges of integrating a micro electric propulsion system on a CubeSat in order to perform orbital maneuvers and control attitude. This represents a fundamentally new capability for CubeSats, which typically do not contain propulsion systems and cannot maneuver far beyond their initial orbits.

Both exogenous 5-HT and endogenous 5-HT, released by fluoxetine, enhance distension evoked propulsion in guinea-pig ileum in vitro

Directory of Open Access Journals (Sweden)

Rachel M Gwynne

2014-09-01

Full Text Available The roles of 5-HT3 and 5-HT4 receptors in the modulation of intestinal propulsion by luminal application of 5-HT and augmentation of endogenous 5-HT effects were studied in segments of guinea-pig ileum in vitro. Persistent propulsive contractions evoked by saline distension were examined using a modified Trendelenburg method. When 5-HT (30 nM, fluoxetine (selective serotonin reuptake inhibitor; 1 nM, 2-methyl-5-HT (5-HT3 receptor agonist; 1 mM or RS 67506 (5-HT4 receptor agonist, 1 µM was infused into the lumen, the pressure needed to initiate persistent propulsive activity fell significantly. A specific 5-HT4 receptor antagonist, SB 207266 (10 nM in lumen, abolished the effects of 5-HT, fluoxetine, and RS 67506, but not those of 2-methyl-5-HT. Granisetron (5-HT3 receptor antagonist; 1 µM in lumen abolished the effect of 5-HT, fluoxetine, RS 67506 and 2-methyl-5-HT. The NK3 receptor antagonist SR 142801 (100 nM in lumen blocked the effects of 5-HT, fluoxetine and 2-methyl-5-HT. SB 207266, granisetron and SR 142801 had no effect by themselves. Higher concentrations of fluoxetine (100 nM and 300 nM and RS 67506 (3 µM and 10 µM had no effect on the distension threshold for propulsive contractions. These results indicate that luminal application of exogenous 5-HT, or increased release of endogenous mucosal 5-HT above basal levels, acts to lower the threshold for propulsive contractions in the guinea-pig ileum via activation of 5-HT3 and 5-HT4 receptors and the release of tachykinins. The results further indicate that basal release of 5-HT is insufficient to alter the threshold for propulsive motor activity.

De Slavernij is onze geschiedenis (niet. Over de discursieve strijd om de betekenis van de ntr- televisieserie De Slavernij

Directory of Open Access Journals (Sweden)

Guno Jones

2012-12-01

Full Text Available Slavery is (Not Our History: On the Public Debate and Divergent Meanings of theNTR Television Series SlaveryThis article discusses the debates that followed the broadcasting of Dutch NTR-television series Slavery (De Slavernij in 2011. While the series was aimed at informing the general public about this silenced part of Dutch history, the subsequent debates on the series revealed fault lines in Dutch society with regard to ideas on how to know and represent slavery adequately. Although most participants, in line of a positivist epistemology, made appeals to historical facts, these debates clearly demonstrated how knowledge and representations of slavery are positioned in a social and academic field that is always characterised by power relations. Postcolonial critics, whose voices are underrepresented in Dutch academia and media, held very different perspectives on the nature of ‘valid’ paradigms, ‘true’ facts, ‘proper’ interpretations, ‘appropriate’ historical referents and representations concerning slavery to people who praised the series. These polarised debates pose the question of how to engage with the history of slavery without resorting to (biological essentialism that is precisely one of its potent legacies ‘we’ want to overcome.

Computational Analysis of a Wing Designed for the X-57 Distributed Electric Propulsion Aircraft

Science.gov (United States)

Deere, Karen A.; Viken, Jeffrey K.; Viken, Sally A.; Carter, Melissa B.; Wiese, Michael R.; Farr, Norma L.

2017-01-01

A computational study of the wing for the distributed electric propulsion X-57 Maxwell airplane configuration at cruise and takeoff/landing conditions was completed. Two unstructured-mesh, Navier-Stokes computational fluid dynamics methods, FUN3D and USM3D, were used to predict the wing performance. The goal of the X-57 wing and distributed electric propulsion system design was to meet or exceed the required lift coefficient 3.95 for a stall speed of 58 knots, with a cruise speed of 150 knots at an altitude of 8,000 ft. The X-57 Maxwell airplane was designed with a small, high aspect ratio cruise wing that was designed for a high cruise lift coefficient (0.75) at angle of attack of 0deg. The cruise propulsors at the wingtip rotate counter to the wingtip vortex and reduce induced drag by 7.5 percent at an angle of attack of 0.6deg. The unblown maximum lift coefficient of the high-lift wing (with the 30deg flap setting) is 2.439. The stall speed goal performance metric was confirmed with a blown wing computed effective lift coefficient of 4.202. The lift augmentation from the high-lift, distributed electric propulsion system is 1.7. The predicted cruise wing drag coefficient of 0.02191 is 0.00076 above the drag allotted for the wing in the original estimate. However, the predicted drag overage for the wing would only use 10.1 percent of the original estimated drag margin, which is 0.00749.

CRISPR/Cas9-mediated targeting of the Rosa26 locus produces Cre reporter rat strains for monitoring Cre-loxP-mediated lineage tracing.

Science.gov (United States)

Ma, Yuanwu; Yu, Lei; Pan, Shuo; Gao, Shan; Chen, Wei; Zhang, Xu; Dong, Wei; Li, Jing; Zhou, Rui; Huang, Lan; Han, Yunlin; Bai, Lin; Zhang, Li; Zhang, Lianfeng

2017-10-01

The rat is an important laboratory animal for physiological, toxicological and pharmacological studies. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) is a simple and efficient tool to generate precise genetic modifications in rats, which will promote the accumulation of genetic resources and enable more precise studies of gene function. To monitor Cre-loxP-mediated excision in vivo, we generated a Cre reporter rat strain (Rosa26-imCherry) by knockin of a Cre reporter cassette at the Rosa26 locus using CRISPR/Cas9. Rosa26-imCherry rats exhibited inducible expression of the mCherry cassette (imCherry) using the Cre-loxP system, whereas normal rats exhibited ubiquitous expression of eGFP but not mCherry in the whole body. Injection of adeno-associated virus serotype 9-Cre into the hippocampus and skeletal muscle resulted in mCherry expression in virus-infected cells. Cre-loxP-mediated mCherry expression was then evaluated by crossing Rosa26-imCherry rats with transgenic rats ubiquitously expressing CAG-Cre, heart-specific α-MHC-Cre transgenic rats and liver-specific Alb-Cre knockin rats. Finally, using the established system the expression pattern of Cre driven by two endogenous gene promoters (Wfs1-Cre knockin rat, FabP2-Cre knockin rat) was traced. In summary, we demonstrated excision of the loxP-flanked allele in Rosa26-imCherry rats via activation of mCherry expression in the presence of Cre recombinase. This newly established Rosa26-imCherry rat strain represents a useful tool to facilitate Cre-expression pattern determination and tracing experiments. © 2017 Federation of European Biochemical Societies.

Alternative Hydrocarbon Propulsion for Nano / Micro Launch Vehicle, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The technical innovation proposed here is the application of an alternative hydrocarbon fuel – densified propylene, in combination with liquid oxygen (LOX) – that...

Distributed propulsion.

OpenAIRE

Lindström, Robin; Rosvall, Tobias

2013-01-01

En prestandaanalys utfördes på en SAAB 2000 som referensobjekt. Olika metoder för att driva flygplan på ett miljövänligare sätt utvärderades tillsammans med distributed propulsion. Efter undersökningar valdes elmotorer tillsammans med Zink-luft batterier för att driva SAAB 2000 med distributed propulsion. En prestandaanalys utfördes på detta plan på samma sätt som för den ursprungliga SAAB 2000. Resultaten jämfördes och slutsatsen blev att räckvidden var för kort för att konfigurationen skull...

Vehicle with inclinable caterpillar propulsion units

International Nuclear Information System (INIS)

Clar, G.

1991-01-01

This vehicle usable in hostile environment such nuclear industry has four propulsion units with a caterpillar track and two integrated motors: one for advancing the caterpillar track and the other for inclining the propulsion unit when overcoming obstacles. Each propulsion unit is easily replaceable because there are no mechanical parts in the body of the vehicle [fr

A non-specific effect associated with conditional transgene expression based on Cre-loxP strategy in mice.

Directory of Open Access Journals (Sweden)

Linghua Qiu

Full Text Available Transgenes flanked by loxP sites have been widely used to generate transgenic mice where the transgene expression can be controlled spatially and temporally by Cre recombinase. Data from this approach has led to important conclusions in cancer, neurodevelopment and neurodegeneration. Using this approach to conditionally express micro RNAs (miRNAs in mice, we found that Cre-mediated recombination in neural progenitor cells caused microcephaly in five of our ten independent transgenic lines. This effect was not associated with the types or the quantity of miRNAs being expressed, nor was it associated with specific target knockdown. Rather, it was correlated with the presence of multiple tandem transgene copies and inverted (head-to-head or tail-to-tail transgene repeats. The presence of these inverted repeats caused a high level of cell death in the ventricular zone of the embryonic brain, where Cre was expressed. Therefore, results from this Cre-loxP approach to generate inducible transgenic alleles must be interpreted with caution and conclusions drawn in previous reports may need reexamination.

Distributed propulsion and future aerospace technologies

OpenAIRE

Ameyugo, Gregorio

2007-01-01

This thesis describes an Engineering Doctorate project in Distributed Propulsion carried out from 2004 to 2007 at Cranfield University. Distributed propulsion is a propulsion system arrangement that consists in spreading the engine thrust along the aircraft span. This can be accomplished by distributing a series of driven fans or the engines themselves. The aim of this project is to determine the feasibility of ...

Secondary Breast Augmentation.

Science.gov (United States)

Brown, Mitchell H; Somogyi, Ron B; Aggarwal, Shagun

2016-07-01

After studying this article, the participant should be able to: 1. Assess common clinical problems in the secondary breast augmentation patient. 2. Describe a treatment plan to correct the most common complications of breast augmentation. 3. Provide surgical and nonsurgical options for managing complications of breast augmentation. 4. Decrease the incidence of future complications through accurate assessment, preoperative planning, and precise surgical technique. Breast augmentation has been increasing steadily in popularity over the past three decades. Many of these patients present with secondary problems or complications following their primary breast augmentation. Two of the most common complications are capsular contracture and implant malposition. Familiarity and comfort with the assessment and management of these complications is necessary for all plastic surgeons. An up-to-date understanding of current devices and techniques may decrease the need to manage future complications from the current cohort of breast augmentation patients.

The Nuclear Thermal Propulsion Stage (NTPS): A Key Space Asset for Human Exploration and Commercial Missions to the Moon

Science.gov (United States)

Borowski, Stanley K.; McCurdy, David R.; Burke, Laura M.

2014-01-01

The nuclear thermal rocket (NTR) has frequently been discussed as a key space asset that can bridge the gap between a sustained human presence on the Moon and the eventual human exploration of Mars. Recently, a human mission to a near Earth asteroid (NEA) has also been included as a "deep space precursor" to an orbital mission of Mars before a landing is attempted. In his "post-Apollo" Integrated Space Program Plan (1970 to 1990), Wernher von Braun, proposed a reusable Nuclear Thermal Propulsion Stage (NTPS) to deliver cargo and crew to the Moon to establish a lunar base initially before sending human missions to Mars. The NTR was selected because it was a proven technology capable of generating both high thrust and high specific impulse (Isp approx. 900 s)-twice that of today's best chemical rockets. During the Rover and NERVA programs, 20 rocket reactors were designed, built and successfully ground tested. These tests demonstrated the (1) thrust levels; (2) high fuel temperatures; (3) sustained operation; (4) accumulated lifetime; and (5) restart capability needed for an affordable in-space transportation system. In NASA's Mars Design Reference Architecture (DRA) 5.0 study, the "Copernicus" crewed NTR Mars transfer vehicle used three 25 klbf "Pewee" engines-the smallest and highest performing engine tested in the Rover program. Smaller lunar transfer vehicles-consisting of a NTPS with three approx. 16.7 klbf "SNRE-class" engines, an in-line propellant tank, plus the payload-can be delivered to LEO using a 70 t to LEO upgraded SLS, and can support reusable cargo delivery and crewed lunar landing missions. The NTPS can play an important role in returning humans to the Moon to stay by providing an affordable in-space transportation system that can allow initial lunar outposts to evolve into settlements capable of supporting commercial activities. Over the next decade collaborative efforts between NASA and private industry could open up new exploration and commercial

Enabling Electric Propulsion for Flight

Science.gov (United States)

Ginn, Starr Renee

2015-01-01

Team Seedling project AFRC and LaRC 31ft distributed electric propulsion wing on truck bed up 75 miles per hour for coefficient of lift validation. Convergent Aeronautic Solutions project, sub-project Convergent Electric Propulsion Technologies AFRC, LaRC and GRC, re-winging a 4 passenger Tecnam aircraft with a 31ft distributed electric propulsion wing. Advanced Air Transport Technologies (Fixed Wing), Hybrid Electric Research Theme, developing a series hybrid ironbird and flight sim to study integration and performance challenges in preparation for a 1-2 MW flight project.

Aeroelastic Wing Shaping Using Distributed Propulsion

Science.gov (United States)

Nguyen, Nhan T. (Inventor); Reynolds, Kevin Wayne (Inventor); Ting, Eric B. (Inventor)

2017-01-01

An aircraft has wings configured to twist during flight. Inboard and outboard propulsion devices, such as turbofans or other propulsors, are connected to each wing, and are spaced along the wing span. A flight controller independently controls thrust of the inboard and outboard propulsion devices to significantly change flight dynamics, including changing thrust of outboard propulsion devices to twist the wing, and to differentially apply thrust on each wing to change yaw and other aspects of the aircraft during various stages of a flight mission. One or more generators can be positioned upon the wing to provide power for propulsion devices on the same wing, and on an opposite wing.

Visions of the Future: Hybrid Electric Aircraft Propulsion

Science.gov (United States)

Bowman, Cheryl L.

2016-01-01

The National Aeronautics and Space Administration (NASA) is investing continually in improving civil aviation. Hybridization of aircraft propulsion is one aspect of a technology suite which will transform future aircraft. In this context, hybrid propulsion is considered a combination of traditional gas turbine propulsion and electric drive enabled propulsion. This technology suite includes elements of propulsion and airframe integration, parallel hybrid shaft power, turbo-electric generation, electric drive systems, component development, materials development and system integration at multiple levels.

MW-Class Electric Propulsion System Designs

Science.gov (United States)

LaPointe, Michael R.; Oleson, Steven; Pencil, Eric; Mercer, Carolyn; Distefano, Salvador

2011-01-01

Electric propulsion systems are well developed and have been in commercial use for several years. Ion and Hall thrusters have propelled robotic spacecraft to encounters with asteroids, the Moon, and minor planetary bodies within the solar system, while higher power systems are being considered to support even more demanding future space science and exploration missions. Such missions may include orbit raising and station-keeping for large platforms, robotic and human missions to near earth asteroids, cargo transport for sustained lunar or Mars exploration, and at very high-power, fast piloted missions to Mars and the outer planets. The Advanced In-Space Propulsion Project, High Efficiency Space Power Systems Project, and High Power Electric Propulsion Demonstration Project were established within the NASA Exploration Technology Development and Demonstration Program to develop and advance the fundamental technologies required for these long-range, future exploration missions. Under the auspices of the High Efficiency Space Power Systems Project, and supported by the Advanced In-Space Propulsion and High Power Electric Propulsion Projects, the COMPASS design team at the NASA Glenn Research Center performed multiple parametric design analyses to determine solar and nuclear electric power technology requirements for representative 300-kW class and pulsed and steady-state MW-class electric propulsion systems. This paper describes the results of the MW-class electric power and propulsion design analysis. Starting with the representative MW-class vehicle configurations, and using design reference missions bounded by launch dates, several power system technology improvements were introduced into the parametric COMPASS simulations to determine the potential system level benefits such technologies might provide. Those technologies providing quantitative system level benefits were then assessed for technical feasibility, cost, and time to develop. Key assumptions and primary

The Space Nuclear Thermal Propulsion Program: Propulsion for the twenty first century

International Nuclear Information System (INIS)

Bleeker, G.; Moody, J.; Kesaree, M.

1993-01-01

As mission requirements approach the limits of the chemical propulsion systems, new engines must be investigated that can meet the advanced mission requirements of higher payload fractions, higher velocities, and consequently higher specific Impulses (Isp). The propulsion system that can meet these high demands is a nuclear thermal rocket engine. This engine generates the thrust by expanding/existing the hydrogen, heated from the energy derived from the fission process in a reactor, through a nozzle. The Department of Defense (DoD), however, initiated a new nuclear rocket development program in 1987 for ballistic missile defense application. The Space Nuclear Thermal Propulsion (SNTP) Program that seeks to improve on the technology of ROVER/NERVA grew out of this beginning and has been managed by the Air Force, with the involvement of DoE and NASA. The goal of the SNTP Program is to develop an engine to meet potential Air Force requirements for upper stage engine, bimodal propulsion/power applications, and orbital transfer vehicles, as well as the NASA requirements for possible missions to the Moon and Mars. During the entire life of the program, the DoD has considered safety to be of paramount importance, and is following all national environmental policies

Materials Advance Chemical Propulsion Technology

Science.gov (United States)

2012-01-01

In the future, the Planetary Science Division of NASA's Science Mission Directorate hopes to use better-performing and lower-cost propulsion systems to send rovers, probes, and observers to places like Mars, Jupiter, and Saturn. For such purposes, a new propulsion technology called the Advanced Materials Bipropellant Rocket (AMBR) was developed under NASA's In-Space Propulsion Technology (ISPT) project, located at Glenn Research Center. As an advanced chemical propulsion system, AMBR uses nitrogen tetroxide oxidizer and hydrazine fuel to propel a spacecraft. Based on current research and development efforts, the technology shows great promise for increasing engine operation and engine lifespan, as well as lowering manufacturing costs. In developing AMBR, ISPT has several goals: to decrease the time it takes for a spacecraft to travel to its destination, reduce the cost of making the propulsion system, and lessen the weight of the propulsion system. If goals like these are met, it could result in greater capabilities for in-space science investigations. For example, if the amount (and weight) of propellant required on a spacecraft is reduced, more scientific instruments (and weight) could be added to the spacecraft. To achieve AMBR s maximum potential performance, the engine needed to be capable of operating at extremely high temperatures and pressure. To this end, ISPT required engine chambers made of iridium-coated rhenium (strong, high-temperature metallic elements) that allowed operation at temperatures close to 4,000 F. In addition, ISPT needed an advanced manufacturing technique for better coating methods to increase the strength of the engine chamber without increasing the costs of fabricating the chamber.

Powered Flight The Engineering of Aerospace Propulsion

CERN Document Server

Greatrix, David R

2012-01-01

Whilst most contemporary books in the aerospace propulsion field are dedicated primarily to gas turbine engines, there is often little or no coverage of other propulsion systems and devices such as propeller and helicopter rotors or detailed attention to rocket engines. By taking a wider viewpoint, Powered Flight - The Engineering of Aerospace Propulsion aims to provide a broader context, allowing observations and comparisons to be made across systems that are overlooked by focusing on a single aspect alone. The physics and history of aerospace propulsion are built on step-by-step, coupled with the development of an appreciation for the mathematics involved in the science and engineering of propulsion. Combining the author’s experience as a researcher, an industry professional and a lecturer in graduate and undergraduate aerospace engineering, Powered Flight - The Engineering of Aerospace Propulsion covers its subject matter both theoretically and with an awareness of the practicalities of the industry. To ...

Augmented reality

Directory of Open Access Journals (Sweden)

Patrik Pucer

2011-08-01

Full Text Available Today we can obtain in a simple and rapid way most of the information that we need. Devices, such as personal computers and mobile phones, enable access to information in different formats (written, pictorial, audio or video whenever and wherever. Daily we use and encounter information that can be seen as virtual objects or objects that are part of the virtual world of computers. Everyone, at least once, wanted to bring these virtual objects from the virtual world of computers into real environments and thus mix virtual and real worlds. In such a mixed reality, real and virtual objects coexist in the same environment. The reality, where users watch and use the real environment upgraded with virtual objects is called augmented reality. In this article we describe the main properties of augmented reality. In addition to the basic properties that define a reality as augmented reality, we present the various building elements (possible hardware and software that provide an insight into such a reality and practical applications of augmented reality. The applications are divided into three groups depending on the information and functions that augmented reality offers, such as help, guide and simulator.

Neurotrophin p75 receptor (p75NTR) promotes endothelial cell apoptosis and inhibits angiogenesis: implications for diabetes-induced impaired neovascularization in ischemic limb muscles

NARCIS (Netherlands)

Caporali, Andrea; Pani, Elisabetta; Horrevoets, Anton J. G.; Kraenkel, Nicolle; Oikawa, Atsuhiko; Sala-Newby, Graciela B.; Meloni, Marco; Cristofaro, Brunella; Graiani, Gallia; Leroyer, Aurelie S.; Boulanger, Chantal M.; Spinetti, Gaia; Yoon, Sung Ok; Madeddu, Paolo; Emanueli, Costanza

2008-01-01

Diabetes impairs endothelial function and reparative neovascularization. The p75 receptor of neurotrophins (p75(NTR)), which is scarcely present in healthy endothelial cells (ECs), becomes strongly expressed by capillary ECs after induction of peripheral ischemia in type-1 diabetic mice. Here, we

In-Space Propulsion (346620) Technology Project

Data.gov (United States)

National Aeronautics and Space Administration — Technologies include, but are not limited to, electric and advanced chemical propulsion, propellantless propulsion such as aerocapture and solar sails, sample return...

A Conceptual Tree of Laser Propulsion

International Nuclear Information System (INIS)

Pakhomov, Andrew V.; Sinko, John E.

2008-01-01

An original attempt to develop a conceptual tree for laser propulsion is offered. The tree provides a systematic view for practically all possible laser propulsion concepts and all inter-conceptual links, based on propellant phases and phase transfers. It also helps to see which fields of laser propulsion have been already thoroughly explored, where the next effort must be applied, and which paths should be taken with proper care or avoided entirely

Powersail High Power Propulsion System Design Study

Science.gov (United States)

Gulczinski, Frank S., III

2000-11-01

A desire by the United States Air Force to exploit the space environment has led to a need for increased on-orbit electrical power availability. To enable this, the Air Force Research Laboratory Space Vehicles Directorate (AFRL/ VS) is developing Powersail: a two-phased program to demonstrate high power (100 kW to 1 MW) capability in space using a deployable, flexible solar array connected to the host spacecraft using a slack umbilical. The first phase will be a proof-of-concept demonstration at 50 kW, followed by the second phase, an operational system at full power. In support of this program, the AFRL propulsion Directorate's Spacecraft Propulsion Branch (AFRL/PRS ) at Edwards AFB has commissioned a design study of the Powersail High Power Propulsion System. The purpose of this study, the results of which are summarized in this paper, is to perform mission and design trades to identify potential full-power applications (both near-Earth and interplanetary) and the corresponding propulsion system requirements and design. The design study shall farther identify a suitable low power demonstration flight that maximizes risk reduction for the fully operational system. This propulsion system is expected to be threefold: (1) primary propulsion for moving the entire vehicle, (2) a propulsion unit that maintains the solar array position relative to the host spacecraft, and (3) control propulsion for maintaining proper orientation for the flexible solar array.

Demonstration of Fission Product Retention in a Novel NTR Fuel, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Several studies over the past few decades have recognized the need for advanced propulsion to explore the solar system. As early as the 1960s, Werner Von Braun and...

Demonstration of Fission Product Retention in a Novel NTR Fuel, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Several studies over the past few decades have recognized the need for advanced propulsion to explore the solar system. As early as the 1960s, Werner Von Braun and...

An Analysis of Rocket Propulsion Testing Costs

Science.gov (United States)

Ramirez-Pagan, Carmen P.; Rahman, Shamim A.

2009-01-01

The primary mission at NASA Stennis Space Center (SSC) is rocket propulsion testing. Such testing is generally performed within two arenas: (1) Production testing for certification and acceptance, and (2) Developmental testing for prototype or experimental purposes. The customer base consists of NASA programs, DOD programs, and commercial programs. Resources in place to perform on-site testing include both civil servants and contractor personnel, hardware and software including data acquisition and control, and 6 test stands with a total of 14 test positions/cells. For several business reasons there is the need to augment understanding of the test costs for all the various types of test campaigns. Historical propulsion test data was evaluated and analyzed in many different ways with the intent to find any correlation or statistics that could help produce more reliable and accurate cost estimates and projections. The analytical efforts included timeline trends, statistical curve fitting, average cost per test, cost per test second, test cost timeline, and test cost envelopes. Further, the analytical effort includes examining the test cost from the perspective of thrust level and test article characteristics. Some of the analytical approaches did not produce evidence strong enough for further analysis. Some other analytical approaches yield promising results and are candidates for further development and focused study. Information was organized for into its elements: a Project Profile, Test Cost Timeline, and Cost Envelope. The Project Profile is a snap shot of the project life cycle on a timeline fashion, which includes various statistical analyses. The Test Cost Timeline shows the cumulative average test cost, for each project, at each month where there was test activity. The Test Cost Envelope shows a range of cost for a given number of test(s). The supporting information upon which this study was performed came from diverse sources and thus it was necessary to

Overview of GX launch services by GALEX

Science.gov (United States)

Sato, Koji; Kondou, Yoshirou

2006-07-01

Galaxy Express Corporation (GALEX) is a launch service company in Japan to develop a medium size rocket, GX rocket and to provide commercial launch services for medium/small low Earth orbit (LEO) and Sun synchronous orbit (SSO) payloads with a future potential for small geo-stationary transfer orbit (GTO). It is GALEX's view that small/medium LEO/SSO payloads compose of medium scaled but stable launch market due to the nature of the missions. GX rocket is a two-stage rocket of well flight proven liquid oxygen (LOX)/kerosene booster and LOX/liquid natural gas (LNG) upper stage. This LOX/LNG propulsion under development by Japan's Aerospace Exploration Agency (JAXA), is robust with comparable performance as other propulsions and have future potential for wider application such as exploration programs. GX rocket is being developed through a joint work between the industries and GX rocket is applying a business oriented approach in order to realize competitive launch services for which well flight proven hardware and necessary new technology are to be introduced as much as possible. It is GALEX's goal to offer “Easy Access to Space”, a highly reliable and user-friendly launch services with a competitive price. GX commercial launch will start in Japanese fiscal year (JFY) 2007 2008.

Optimization of extended propulsion time nuclear-electric propulsion trajectories

Science.gov (United States)

Sauer, C. G., Jr.

1981-01-01

This paper presents the methodology used in optimizing extended propulsion time NEP missions considering realistic thruster lifetime constraints. These missions consist of a powered spiral escape from a 700-km circular orbit at the earth, followed by a powered heliocentric transfer with an optimized coast phase, and terminating in a spiral capture phase at the target planet. This analysis is most applicable to those missions with very high energy requirements such as outer planet orbiter missions or sample return missions where the total propulsion time could greatly exceed the expected lifetime of an individual thruster. This methodology has been applied to the investigation of NEP missions to the outer planets where examples are presented of both constrained and optimized trajectories.

Breakthrough Propulsion Physics Project: Project Management Methods

Science.gov (United States)

Millis, Marc G.

2004-01-01

To leap past the limitations of existing propulsion, the NASA Breakthrough Propulsion Physics (BPP) Project seeks further advancements in physics from which new propulsion methods can eventually be derived. Three visionary breakthroughs are sought: (1) propulsion that requires no propellant, (2) propulsion that circumvents existing speed limits, and (3) breakthrough methods of energy production to power such devices. Because these propulsion goals are presumably far from fruition, a special emphasis is to identify credible research that will make measurable progress toward these goals in the near-term. The management techniques to address this challenge are presented, with a special emphasis on the process used to review, prioritize, and select research tasks. This selection process includes these key features: (a) research tasks are constrained to only address the immediate unknowns, curious effects or critical issues, (b) reliability of assertions is more important than the implications of the assertions, which includes the practice where the reviewers judge credibility rather than feasibility, and (c) total scores are obtained by multiplying the criteria scores rather than by adding. Lessons learned and revisions planned are discussed.

An Overview of Cube-Satellite Propulsion Technologies and Trends

Directory of Open Access Journals (Sweden)

Akshay Reddy Tummala

2017-12-01

Full Text Available CubeSats provide a cost effective means to perform scientific and technological studies in space. Due to their affordability, CubeSat technologies have been diversely studied and developed by educational institutions, companies and space organizations all over the world. The CubeSat technology that is surveyed in this paper is the propulsion system. A propulsion system is the primary mobility device of a spacecraft and helps with orbit modifications and attitude control. This paper provides an overview of micro-propulsion technologies that have been developed or are currently being developed for CubeSats. Some of the micro-propulsion technologies listed have also flown as secondary propulsion systems on larger spacecraft. Operating principles and key design considerations for each class of propulsion system are outlined. Finally, the performance factors of micro-propulsion systems have been summarized in terms of: first, a comparison of thrust and specific impulse for all propulsion systems; second, a comparison of power and specific impulse, as also thrust-to-power ratio and specific impulse for electric propulsion systems.

Propulsion of liposomes using bacterial motors

International Nuclear Information System (INIS)

Zhang Zhenhai; Li Kejie; Li Zhifei; Yu Wei; Xie Zhihong; Shi Zhiguo

2013-01-01

Here we describe the utilization of flagellated bacteria as actuators to propel spherical liposomes by attaching bacteria to the liposome surface. Bacteria were stably attached to liposomes using a cross-linking antibody. The effect of the number of attached bacteria on propulsion speed was experimentally determined. The effects of bacterial propulsion on the bacteria–antibody–liposome complex were stochastic. We demonstrated that liposomal mobility increased when bacteria were attached, and the propulsion speed correlated with the number of bacteria. (paper)

Exotic power and propulsion concepts

International Nuclear Information System (INIS)

Forward, R.L.

1990-01-01

The status of some exotic physical phenomena and unconventional spacecraft concepts that might produce breakthroughs in power and propulsion in the 21st Century are reviewed. The subjects covered include: electric, nuclear fission, nuclear fusion, antimatter, high energy density materials, metallic hydrogen, laser thermal, solar thermal, solar sail, magnetic sail, and tether propulsion

Operationally efficient propulsion system study (OEPSS) data book. Volume 6; Space Transfer Propulsion Operational Efficiency Study Task of OEPSS

Science.gov (United States)

Harmon, Timothy J.

1992-01-01

This document is the final report for the Space Transfer Propulsion Operational Efficiency Study Task of the Operationally Efficient Propulsion System Study (OEPSS) conducted by the Rocketdyne Division of Rockwell International. This Study task studied, evaluated and identified design concepts and technologies which minimized launch and in-space operations and optimized in-space vehicle propulsion system operability.

Main Propulsion Test Article (MPTA)

Science.gov (United States)

Snoddy, Cynthia

2010-01-01

Scope: The Main Propulsion Test Article integrated the main propulsion subsystem with the clustered Space Shuttle Main Engines, the External Tank and associated GSE. The test program consisted of cryogenic tanking tests and short- and long duration static firings including gimbaling and throttling. The test program was conducted on the S1-C test stand (Position B-2) at the National Space Technology Laboratories (NSTL)/Stennis Space Center. 3 tanking tests and 20 hot fire tests conducted between December 21 1 1977 and December 17, 1980 Configuration: The main propulsion test article consisted of the three space shuttle main engines, flightweight external tank, flightweight aft fuselage, interface section and a boilerplate mid/fwd fuselage truss structure.

NASA's Nuclear Thermal Propulsion Project

Science.gov (United States)

Houts, Michael G.; Mitchell, Doyce P.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Gerrish, Harold P.; Doughty, Glen; Belvin, Anthony; Clement, Steven; Borowski, Stanley K.;

Subclinical hypothyroidism in pregnant rats impaired learning and memory of their offspring by promoting the p75NTR signal pathway

Directory of Open Access Journals (Sweden)

Fan Zhang

2018-05-01

Full Text Available Objective: Maternal hypothyroidism during pregnancy can affect the neurodevelopment of their offspring. This study aimed to investigate the effects of maternal subclinical hypothyroidism (SCH on spatial learning and memory, and its relationship with the apoptotic factors in cerebral cortex of the offspring. Methods: Female adult Wistar rats were randomly divided into three groups (n = 15 per group: control (CON group, SCH group and overt hypothyroidism (OH group. Spatial learning and memory in the offspring were evaluated by long-term potentiation (LTP and Morris water-maze (MWM test. The protein expression of the p75 neurotrophin receptor (p75NTR, phospho-c-Jun N-terminal kinase (p-JNK, the pro-apoptotic protein p53 and Bax were detected by Western blotting. Results: The Pups in the SCH and OH groups showed longer escape latencies in the MWM and decreased field-excitatory post synaptic potentials in LTP tests compared with those in the CON group. p75NTR, p-JNK, p53 and Bax expression levels in the cerebral cortex increased in pups in the SCH and OH groups compared with those in the CON group. Conclusions: Maternal SCH during pregnancy may impair spatial learning and memory in the offspring and may be associated with the increased apoptosis in the cerebral cortex.

Nuclear merchant ship propulsion

International Nuclear Information System (INIS)

Schroeder, E.; Jager, W.; Schafstall, H.G.

1977-01-01

The operation of about 300 nuclear naval vessels has proven the feasibility of nuclear ship propulsion. Until now six non military ships have been built or are under construction. In the Soviet Union two nuclear icebreakers are in operation, and a third one is under construction. In the western world three prototype merchant ships have been built. Of these ships only the NS OTTO HAHN is in operation and provides valuable experience for future large scale use of nuclear merchant ship propulsion. In many countries studies and plans are made for future nuclear merchant ships. Types of vessels investigated are large containerships, tankers and specialized ships like icebreakers or ice-breaking ships. The future of nuclear merchant ship propulsion depends on three interrelated items: (1) nuclear ship technology; (2) economy of nuclear ship propulsion; (3) legal questions. Nuclear merchant ship technology is based until now on standard ship technology and light water reactor technology. Except for special questions due to the non-stationary type of the plant entirely new problems do not arise. This has been proven by the recent conceptual licensing procedure for a large nuclear containership in Germany. The economics of nuclear propulsion will be under discussion until they are proven by the operation of privately owned lead ships. Unsolved legal questions e.g. in connection with port entry permissions are at present another problem for nuclear shipping. Efforts are made to solve these questions on an international basis. The future development of nuclear energy electricity production in large land based plants will stimulate the employment of smaller units. Any future development of long distance sea transport will have to take this opportunity of a reliable and economic energy supply into account

AUGMENTED REALITY

DEFF Research Database (Denmark)

Skov, Kirsten; Bahn, Anne Louise

2017-01-01

Projektets grundlæggende idé er udvikling af visuel, æstetisk læring med Augmented Reality, hvor intentionen er at bidrage med konkrete undersøgelser og udforskning af begrebet Augmented Reality – herunder koblingen mellem det analoge og digitale i forhold til læring, multimodalitet og it...

An Airbreathing Launch Vehicle Design with Turbine-Based Low-Speed Propulsion and Dual Mode Scramjet High-Speed Propulsion

Science.gov (United States)

Moses, P. L.; Bouchard, K. A.; Vause, R. F.; Pinckney, S. Z.; Ferlemann, S. M.; Leonard, C. P.; Taylor, L. W., III; Robinson, J. S.; Martin, J. G.; Petley, D. H.

1999-01-01

Airbreathing launch vehicles continue to be a subject of great interest in the space access community. In particular, horizontal takeoff and horizontal landing vehicles are attractive with their airplane-like benefits and flexibility for future space launch requirements. The most promising of these concepts involve airframe integrated propulsion systems, in which the external undersurface of the vehicle forms part of the propulsion flowpath. Combining of airframe and engine functions in this manner involves all of the design disciplines interacting at once. Design and optimization of these configurations is a most difficult activity, requiring a multi-discipline process to analytically resolve the numerous interactions among the design variables. This paper describes the design and optimization of one configuration in this vehicle class, a lifting body with turbine-based low-speed propulsion. The integration of propulsion and airframe, both from an aero-propulsive and mechanical perspective are addressed. This paper primarily focuses on the design details of the preferred configuration and the analyses performed to assess its performance. The integration of both low-speed and high-speed propulsion is covered. Structural and mechanical designs are described along with materials and technologies used. Propellant and systems packaging are shown and the mission-sized vehicle weights are disclosed.

Tracking for Outdoor Mobile Augmented Reality: Further development of the Zion Augmented Reality Application

OpenAIRE

Strand, Tor Egil Riegels

2008-01-01

This report deals with providing tracking to an outdoor mobile augmented reality system and the Zion Augmented Reality Application. ZionARA is meant to display a virtual recreation of a 13th century castle on the site it once stood through an augmented reality Head Mounted Display. Mobile outdoor augmented/mixed reality puts special demands on what kind of equipment is practical. After briefly evaluating the different existing tracking methods, a solution based on GPS and an augmented inertia...

Propulsive options for a manned Mars transportation system

International Nuclear Information System (INIS)

Braun, R.D.; Blersch, D.J.

1989-01-01

In this investigation, five potential manned Mars transportation systems are compared. These options include: (1) a single vehicle, chemically propelled (CHEM) option, (2) a single vehicle, nuclear thermal propulsion (NTP) option, (3) a single vehicle solar electric propulsion (SEP) option, (4) a single vehicle hybrid nuclear electric propulsion (NEP)/CHEM option, and (5) a dual vehicle option (NEP cargo spacecraft and CHEM manned vehicle). In addition to utilizing the initial vehicle weight in low-earth orbit as a measure of mission feasibility, this study addresses the major technological barriers each propulsive scenario must surpass. It is shown that instead of a single clearly superior propulsion system, each means of propulsion may be favored depending upon the specified program policy and the extent of the desired manned flight time. Furthermore, the effect which aerobraking and multiple transfer cycles have upon mission feasibility is considered. 18 refs

Distributed propulsion for ships

OpenAIRE

Nylund, Vilde

2017-01-01

It is anticipated that using distributed electric propulsion (DEP) on conventional ships will increase the total propulsive efficiency. This is mainly due to two reasons; firstly, because the total propeller disk area can be increased. Secondly, because each propeller can be optimised for the local wake where it is operating. In this work, the benefits of using DEP has been investigated for a 14 000 TEU container ship. Based on a literary study of the present state of propeller modelling ...

A novel nuclear-powered propulsion system for ship

International Nuclear Information System (INIS)

Liu Tao; Han Weishi

2003-01-01

A novel nuclear-powered propulsion system for ship is presented in this paper. In this system, a minitype liquid sodium-cooled reactor is used as power; alkali-metal thermal-to-electric conversion (AMTEC) cells are utilized to transform the heat energy to electric energy and superconducting magneto-hydrodynamic (MHD) work as propulsion. This nuclear-powered propulsion system has great advantages in low noise, high speed, long survivability and simple manipulation. It has great significance for the development of propulsion system. (author)

Center for Advanced Space Propulsion Second Annual Technical Symposium Proceedings

Science.gov (United States)

1990-01-01

The proceedings for the Center for Advanced Space Propulsion Second Annual Technical Symposium are divided as follows: Chemical Propulsion, CFD; Space Propulsion; Electric Propulsion; Artificial Intelligence; Low-G Fluid Management; and Rocket Engine Materials.

Understanding augmented reality concepts and applications

CERN Document Server

Craig, Alan B

2013-01-01

Augmented reality is not a technology. Augmented reality is a medium. Likewise, a book on augmented reality that only addresses the technology that is required to support the medium of augmented reality falls far short of providing the background that is needed to produce, or critically consume augmented reality applications. One reads a book. One watches a movie. One experiences augmented reality. Understanding Augmented Reality addresses the elements that are required to create compelling augmented reality experiences. The technology that supports

An Investigation of Bilateral Symmetry During Manual Wheelchair Propulsion.

Science.gov (United States)

Soltau, Shelby L; Slowik, Jonathan S; Requejo, Philip S; Mulroy, Sara J; Neptune, Richard R

2015-01-01

Studies of manual wheelchair propulsion often assume bilateral symmetry to simplify data collection, processing, and analysis. However, the validity of this assumption is unclear. Most investigations of wheelchair propulsion symmetry have been limited by a relatively small sample size and a focus on a single propulsion condition (e.g., level propulsion at self-selected speed). The purpose of this study was to evaluate bilateral symmetry during manual wheelchair propulsion in a large group of subjects across different propulsion conditions. Three-dimensional kinematics and handrim kinetics along with spatiotemporal variables were collected and processed from 80 subjects with paraplegia while propelling their wheelchairs on a stationary ergometer during three different conditions: level propulsion at their self-selected speed (free), level propulsion at their fastest comfortable speed (fast), and propulsion on an 8% grade at their level, self-selected speed (graded). All kinematic variables had significant side-to-side differences, primarily in the graded condition. Push angle was the only spatiotemporal variable with a significant side-to-side difference, and only during the graded condition. No kinetic variables had significant side-to-side differences. The magnitudes of the kinematic differences were low, with only one difference exceeding 5°. With differences of such small magnitude, the bilateral symmetry assumption appears to be reasonable during manual wheelchair propulsion in subjects without significant upper-extremity pain or impairment. However, larger asymmetries may exist in individuals with secondary injuries and pain in their upper extremity and different etiologies of their neurological impairment.

An overview of the NASA Advanced Propulsion Concepts program

International Nuclear Information System (INIS)

Curran, F.M.; Bennett, G.L.; Frisbee, R.H.; Sercel, J.C.; Lapointe, M.R.

1992-07-01

NASA Advanced Propulsion Concepts (APC) program for the development of long-term space propulsion system schemes is managed by both NASA-Lewis and the JPL and is tasked with the identification and conceptual development of high-risk/high-payoff configurations. Both theoretical and experimental investigations have been undertaken in technology areas deemed essential to the implementation of candidate concepts. These APC candidates encompass very high energy density chemical propulsion systems, advanced electric propulsion systems, and an antiproton-catalyzed nuclear propulsion concept. A development status evaluation is presented for these systems. 45 refs

46 CFR 121.620 - Propulsion engine control systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

Establishing a cellular FRET-based fluorescence plate reader assay to monitor proNGF-induced cross-linking of sortilin and the neurotrophin receptor p75(NTR)

DEFF Research Database (Denmark)

Skeldal, Sune; Kjaergaard, Maj M; Alwasel, Saleh

2015-01-01

the vps10p domain receptor sortilin and the neurotrophin receptor p75(NTR). However, proNGF-induced receptor complex formation has been difficult to directly assess other than by western blotting. We here describe a fluorescence resonance energy transfer (FRET) based fluorescence plate reader assay...

Monofilament Vaporization Propulsion (MVP) System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Monofilament Vaporization Propulsion (MVP) is a new propulsion technology targeted at secondary payload applications. It does not compromise on performance while...

Solar Electric Propulsion Triple-Satellite-Aided Capture With Mars Flyby

Science.gov (United States)

Patrick, Sean

Triple-Satellite-aided-capture sequences use gravity-assists at three of Jupiter's four massive Galilean moons to reduce the DeltaV required to enter into Jupiter orbit. A triple-satellite-aided capture at Callisto, Ganymede, and Io is proposed to capture a SEP spacecraft into Jupiter orbit from an interplanetary Earth-Jupiter trajectory that employs low-thrust maneuvers. The principal advantage of this method is that it combines the ISP efficiency of ion propulsion with nearly impulsive but propellant-free gravity assists. For this thesis, two main chapters are devoted to the exploration of low-thrust triple-flyby capture trajectories. Specifically, the design and optimization of these trajectories are explored heavily. The first chapter explores the design of two solar electric propulsion (SEP), low-thrust trajectories developed using the JPL's MALTO software. The two trajectories combined represent a full Earth to Jupiter capture split into a heliocentric Earth to Jupiter Sphere of Influence (SOI) trajectory and a Joviocentric capture trajectory. The Joviocentric trajectory makes use of gravity assist flybys of Callisto, Ganymede, and Io to capture into Jupiter orbit with a period of 106.3 days. Following this, in chapter two, three more SEP low-thrust trajectories were developed based upon those in chapter one. These trajectories, devised using the high-fidelity Mystic software, also developed by JPL, improve upon the original trajectories developed in chapter one. Here, the developed trajectories are each three separate, full Earth to Jupiter capture orbits. As in chapter one, a Mars gravity assist is used to augment the heliocentric trajectories. Gravity-assist flybys of Callisto, Ganymede, and Io or Europa are used to capture into Jupiter Orbit. With between 89.8 and 137.2-day periods, the orbits developed in chapters one and two are shorter than most Jupiter capture orbits achieved using low-thrust propulsion techniques. Finally, chapter 3 presents an

46 CFR 184.620 - Propulsion engine control systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Propulsion engine control systems. 184.620 Section 184... Communications Systems § 184.620 Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of...

In-Space Propulsion Technologies for Robotic Exploration of the Solar System

Science.gov (United States)

Johnson, Les; Meyer, Rae Ann; Frame, Kyle

2006-01-01

Supporting NASA's Science Mission Directorate, the In-Space Propulsion Technology Program is developing the next generation of space propulsion technologies for robotic, deep-space exploration. Recent technological advancements and demonstrations of key, high-payoff propulsion technologies have been achieved and will be described. Technologies under development and test include aerocapture, solar electric propulsion, solar sail propulsion, and advanced chemical propulsion.

Modifications in Wheelchair Propulsion Technique with Speed.

Science.gov (United States)

Russell, Ian M; Raina, Shashank; Requejo, Philip S; Wilcox, Rand R; Mulroy, Sara; McNitt-Gray, Jill L

2015-01-01

Repetitive loading of the upper limb joints during manual wheelchair (WC) propulsion (WCP) has been identified as a factor that contributes to shoulder pain, leading to loss of independence and decreased quality of life. The purpose of this study was to determine how individual manual WC users with paraplegia modify propulsion mechanics to accommodate expected increases in reaction forces (RFs) generated at the pushrim with self-selected increases in WCP speed. Upper extremity kinematics and pushrim RFs were measured for 40 experienced manual WC users with paraplegia while propelling on a stationary ergometer at self-selected free and fast propulsion speeds. Upper extremity kinematics and kinetics were compared within subject between propulsion speeds. Between group and within-subject differences were determined (α = 0.05). Increased propulsion speed was accompanied by increases in RF magnitude (22 of 40, >10 N) and shoulder net joint moment (NJM, 15 of 40, >10 Nm) and decreases in pushrim contact duration. Within-subject comparison indicated that 27% of participants modified their WCP mechanics with increases in speed by regulating RF orientation relative to the upper extremity segments. Reorientation of the RF relative to the upper extremity segments can be used as an effective strategy for mitigating rotational demands (NJM) imposed on the shoulder at increased propulsion speeds. Identification of propulsion strategies that individuals can use to effectively accommodate for increases in RFs is an important step toward preserving musculoskeletal health of the shoulder and improving health-related quality of life.

Beamed-Energy Propulsion (BEP) Study

Science.gov (United States)

George, Patrick; Beach, Raymond

2012-01-01

The scope of this study was to (1) review and analyze the state-of-art in beamed-energy propulsion (BEP) by identifying potential game-changing applications, (2) formulate a roadmap of technology development, and (3) identify key near-term technology demonstrations to rapidly advance elements of BEP technology to Technology Readiness Level (TRL) 6. The two major areas of interest were launching payloads and space propulsion. More generally, the study was requested and structured to address basic mission feasibility. The attraction of beamed-energy propulsion (BEP) is the potential for high specific impulse while removing the power-generation mass. The rapid advancements in high-energy beamed-power systems and optics over the past 20 years warranted a fresh look at the technology. For launching payloads, the study concluded that using BEP to propel vehicles into space is technically feasible if a commitment to develop new technologies and large investments can be made over long periods of time. From a commercial competitive standpoint, if an advantage of beamed energy for Earth-to-orbit (ETO) is to be found, it will rest with smaller, frequently launched payloads. For space propulsion, the study concluded that using beamed energy to propel vehicles from low Earth orbit to geosynchronous Earth orbit (LEO-GEO) and into deep space is definitely feasible and showed distinct advantages and greater potential over current propulsion technologies. However, this conclusion also assumes that upfront infrastructure investments and commitments to critical technologies will be made over long periods of time. The chief issue, similar to that for payloads, is high infrastructure costs.

The effectiveness of an augmented cognitive behavioural intervention for post-stroke depression with or without anxiety (PSDA: the Restore4Stroke-PSDA trial

Directory of Open Access Journals (Sweden)

Kootker Joyce A

2012-07-01

Full Text Available Abstract Background Post-Stroke Depression with or without Anxiety (PSDA is a common disorder in the chronic phase of stroke. Neuropsychiatric problems, such as PSDA, have a negative impact on social reintegration and quality of life. Currently, there is no evidence-based treatment available for reducing PSDA symptoms. In the recent literature on depression in the general population it has been shown that depression complaints can diminish by cognitive behavioural therapy (CBT. In the current study, the effectiveness of augmented, activation-based and individually tailored CBT on the reduction of depression and anxiety will be investigated in patients with PSDA. Additionally, the effects on various secondary outcome measures, such as quality of life, goal attainment and societal participation will be evaluated. This study is embedded in a consortium of 4 interrelated studies on quality of life after stroke (Restore4Stroke. Methods/design A multi-centre, assessor-blind, randomized controlled trial is conducted. A sample of 106 PSDA patients, as assessed with the Hospital Anxiety and Depression Scale (HADS depression subscale >7, will be recruited and randomly allocated to either an experimental or a control group. The experimental intervention consists of an augmented CBT intervention. The intervention is based on CBT principles of recognizing, registering, and altering negative thoughts and cognitions so that mood, and emotional symptoms are improved. CBT is augmented with direct in-vivo activation offered by occupational or movement therapists. Patients in the control group will receive a computerized cognitive training intervention. Outcomes will be assessed at baseline, immediately post intervention, and at 6 and 12 months follow up. Discussion This study is the first randomized clinical trial that evaluates the (maintenance of effects of augmented CBT on post-stroke depression with or without anxiety symptoms. Together with three other

Advanced Chemical Propulsion for Science Missions

Science.gov (United States)

Liou, Larry

2008-01-01

The advanced chemical propulsion technology area of NASA's In-Space Technology Project is investing in systems and components for increased performance and reduced cost of chemical propulsion technologies applicable to near-term science missions. Presently the primary investment in the advanced chemical propulsion technology area is in the AMBR high temperature storable bipropellant rocket engine. Scheduled to be available for flight development starting in year 2008, AMBR engine shows a 60 kg payload gain in an analysis for the Titan-Enceladus orbiter mission and a 33 percent manufacturing cost reduction over its baseline, state-of-the-art counterpart. Other technologies invested include the reliable lightweight tanks for propellant and the precision propellant management and mixture ratio control. Both technologies show significant mission benefit, can be applied to any liquid propulsion system, and upon completion of the efforts described in this paper, are at least in parts ready for flight infusion. Details of the technologies are discussed.

Nuclear thermal propulsion workshop overview

International Nuclear Information System (INIS)

Clark, J.S.

1991-01-01

NASA is planning an Exploration Technology Program as part of the Space Exploration Initiative to return U.S. astronauts to the moon, conduct intensive robotic exploration of the moon and Mars, and to conduct a piloted mission to Mars by 2019. Nuclear Propulsion is one of the key technology thrust for the human mission to Mars. The workshop addresses NTP (Nuclear Thermal Rocket) technologies with purpose to: assess the state-of-the-art of nuclear propulsion concepts; assess the potential benefits of the concepts for the mission to Mars; identify critical, enabling technologies; lay-out (first order) technology development plans including facility requirements; and estimate the cost of developing these technologies to flight-ready status. The output from the workshop will serve as a data base for nuclear propulsion project planning

Propulsion controlled aircraft computer

Science.gov (United States)

Cogan, Bruce R. (Inventor)

2010-01-01

A low-cost, easily retrofit Propulsion Controlled Aircraft (PCA) system for use on a wide range of commercial and military aircraft consists of an propulsion controlled aircraft computer that reads in aircraft data including aircraft state, pilot commands and other related data, calculates aircraft throttle position for a given maneuver commanded by the pilot, and then displays both current and calculated throttle position on a cockpit display to show the pilot where to move throttles to achieve the commanded maneuver, or is automatically sent digitally to command the engines directly.

The effect of wheelchair propulsion style on changes in time spent in extreme wrist orientations after a bout of fatiguing propulsion.

Science.gov (United States)

Zukowski, Lisa A; Hass, Chris J; Shechtman, Orit; Christou, Evangelos A; Tillman, Mark D

2017-10-01

This study compared how wheelchair propulsion styles affect changes in percentage of time spent in extreme wrist orientations, which have been associated with median nerve injury, after a fatiguing bout of propulsion. Twenty novice, non-disabled adult males learned arcing (ARC) and semicircular (SEMI) propulsion styles and utilised each to perform a wheelchair fatigue protocol. ARC and SEMI did not significantly differ in terms of changes after the fatigue protocol in percentage of time spent in extreme flexion/extension or radial/ulnar deviation at the push phase beginning or end. A pattern was observed, although not significant, of greater increases in percentage of time spent in extreme wrist extension and ulnar deviation during the push phase beginning and ulnar deviation during the push phase end while utilising SEMI relative to ARC. This study evinces that individual differences are greater than observed changes in extreme wrist orientations for both propulsion styles. Practitioner Summary: How wheelchair propulsion styles change with fatigue in terms of extreme wrist orientations was examined. This study evinces that individual differences are greater than observed changes in extreme wrist orientations for both propulsion styles and point towards the need for future research on individual differences utilising propulsion styles.

Jointly Optimize Data Augmentation and Network Training: Adversarial Data Augmentation in Human Pose Estimation

OpenAIRE

Peng, Xi; Tang, Zhiqiang; Yang, Fei; Feris, Rogerio; Metaxas, Dimitris

2018-01-01

Random data augmentation is a critical technique to avoid overfitting in training deep neural network models. However, data augmentation and network training are usually treated as two isolated processes, limiting the effectiveness of network training. Why not jointly optimize the two? We propose adversarial data augmentation to address this limitation. The main idea is to design an augmentation network (generator) that competes against a target network (discriminator) by generating `hard' au...

46 CFR 109.555 - Propulsion boilers.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Propulsion boilers. 109.555 Section 109.555 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.555 Propulsion boilers. The master or person in charge and the engineer in charge shall...

46 CFR 130.120 - Propulsion control.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Propulsion control. 130.120 Section 130.120 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS VESSEL CONTROL, AND MISCELLANEOUS EQUIPMENT AND SYSTEMS Vessel Control § 130.120 Propulsion control. (a) Each vessel must have— (1...

Is effective force application in handrim wheelchair propulsion also efficient?

NARCIS (Netherlands)

Bregman, D.J.J.; van Drongelen, S.V.; Veeger, H.E.J.

2009-01-01

Background: Efficiency in manual wheelchair propulsion is low, as is the fraction of the propulsion force that is attributed to the moment of propulsion of the wheelchair. In this study we tested the hypothesis that a tangential propulsion force direction leads to an increase in physiological cost,

Confronting an augmented reality

Directory of Open Access Journals (Sweden)

John Hedberg

2012-08-01

Full Text Available How can educators make use of augmented reality technologies and practices to enhance learning and why would we want to embrace such technologies anyway? How can an augmented reality help a learner confront, interpret and ultimately comprehend reality itself? In this article, we seek to initiate a discussion that focuses on these questions, and suggest that they be used as drivers for research into effective educational applications of augmented reality. We discuss how multi-modal, sensorial augmentation of reality links to existing theories of education and learning, focusing on ideas of cognitive dissonance and the confrontation of new realities implied by exposure to new and varied perspectives. We also discuss connections with broader debates brought on by the social and cultural changes wrought by the increased digitalisation of our lives, especially the concept of the extended mind. Rather than offer a prescription for augmentation, our intention is to throw open debate and to provoke deep thinking about what interacting with and creating an augmented reality might mean for both teacher and learner.

Close-in characteristics of LH2/LOX reactions

Science.gov (United States)

Riehl, W. A.; Ullian, L. J.

1985-01-01

In deriving shock overpressures from space vehicles employing LH2 and LOX, separate methods of analyses and prediction are recommended, as a function of the distance. Three methods of treatment are recommended. For the Far Field - where the expected shock overpressure is less than 40 psi (lambda = 5) - use the classical PYRO approach to determine TNT yield, and employ classical ordnance (Kingery) curve to obtain the overall value. For the Close-In Range, a suggested limit is 3D, or a zone from a distance of three times the tank diameter to the tank wall. Rather than estimate a specific distance from the center of explosion to the target, it is only necessary to estimate whether this could be within one, two, or three diameters away from the wall; i.e., in the 1, 2, or 3D zone. Then assess whether mixing mode is by the PYRO CBGS (spill) mode or CBM (internal mixing) mode. From the zone and mixing mode, the probability of attaining various shock overpressures is determined from the plots provided herein. For the transition zone, between 40 psi and the 3D distance, it is tentatively recommended that both of the preceding methods be used, and to be conservative, the higher resulting value be used.

A cermet fuel reactor for nuclear thermal propulsion

International Nuclear Information System (INIS)

Kruger, G.

1991-01-01

Work on the cermet fuel reactor done in the 1960's by General Electric (GE) and the Argonne National Laboratory (ANL) that had as its goal the development of systems that could be used for nuclear rocket propulsion as well as closed cycle propulsion system designs for ship propulsion, space nuclear propulsion, and other propulsion systems is reviewed. It is concluded that we can have excellent thermal and mechanical performance with cermet fuel. Thousands of hours of testing were performed on the cermet fuel at both GE and AGL, including very rapid transients and some radiation performance history. We conclude that there are no feasibility issues with cermet fuel. What is needed is reactivation of existing technology and qualification testing of a specific fuel form. We believe this can be done with a minimum development risk

Project ARGO: The design and analysis of an all-propulsive and an aeroassisted version of a manned space transportation vehicle

Science.gov (United States)

Wang, H.; Seifert, D.; Waidelich, J.; Mileski, M.; Herr, D.; Wilks, M.; Law, G.; Folz, A.

1989-01-01

The Senior Aerospace System Design class at the University of Michigan undertook the design of a manned space transportation vehicle (STV) that would transport payloads between low earth orbit (LEO) and geosynchronous earth orbit (GEO). Designated ARGO after the ship of the Greek adventurer Jason, two different versions of an STV that would be based, refueled, and serviced at the Space Station Freedom were designed and analyzed by the class. With the same 2-man/7-day nominal mission of transporting a 10,000-kg payload up to GEO and bringing a 5000-kg payload back to LEO, the two versions of ARGO differ in the manner in which the delta V is applied to insert the vehicle into LEO upon return from GEO. The all-propulsive ARGO (or CSTV for chemical STV) uses thrust from its LH2/LOX rocket engines to produce the delta V during all phases of its mission. While the aeroassisted ARGO (or ASTV for aeroassisted STV) also uses the same engines for the majority of the mission, the final delta V used to insert the ASTV into LEO is produced by skimming the Earth's atmosphere and using the drag on the vehicle to apply the required delta V. This procedure allows for large propellant, and thus cost, savings, but creates many design problems such as the high heating rates and decelerations experienced by a vehicle moving through the atmosphere at hypersonic velocities. The design class, consisting of 43 senior aerospace engineering students, was divided into one managerial and eight technical groups. The technical groups consisted of spacecraft configuration and integration, mission analysis, atmospheric flight, propulsion, power and communications, life support and human factors, logistics and support, and systems analysis. Two committees were set up with members from each group to create the scale models of the STV's and to produce the final report.

Overview and future prospects of laser plasma propulsion technology

International Nuclear Information System (INIS)

Zheng Zhiyuan; Lu Xin; Zhang Jie

2003-01-01

Due to its high cost, low efficiency, complex operation and unsatisfactory recycling, traditional rocket propulsion by chemical fuels has hindered the exploration of outer space to further limits. With the rapid development of laser and space technology, the new technology of laser propulsion exhibits unique advantages and prospects. The mechanism and current development of laser plasma propulsion are reviewed, with mention of the technical problems and focus issues of laser plasma in micro-flight propulsion

Fitting aerodynamics and propulsion into the puzzle

Science.gov (United States)

Johnston, Patrick J.; Whitehead, Allen H., Jr.; Chapman, Gary T.

1987-01-01

The development of an airbreathing single-stage-to-orbit vehicle, in particular the problems of aerodynamics and propulsion integration, is examined. The boundary layer transition on constant pressure surfaces at hypersonic velocities, and the effects of noise on the transition are investigated. The importance of viscosity, real-gas effects, and drag at hypersonic speeds is discussed. A propulsion system with sufficient propulsive lift to enhance the performance of the vehicle is being developed. The difficulties of engine-airframe integration are analyzed.

NASA's nuclear electric propulsion technology project

International Nuclear Information System (INIS)

Stone, J.R.; Sovey, J.S.

1992-07-01

The National Aeronautics and Space Administration (NASA) has initiated a program to establish the readiness of nuclear electric propulsion (NEP) technology for relatively near-term applications to outer planet robotic science missions with potential future evolution to system for piloted Mars vehicles. This program was initiated in 1991 with a very modest effort identified with nuclear thermal propulsion (NTP); however, NEP is also an integral part of this program and builds upon NASA's Base Research and Technology Program in power and electric propulsion as well as the SP-100 space nuclear power program. The NEP Program will establish the feasibility and practicality of electric propulsion for robotic and piloted solar system exploration. The performance objectives are high specific impulse (200 greater than I(sub sp) greater than 10000 s), high efficiency (over 0.50), and low specific mass. The planning for this program was initially focussed on piloted Mars missions, but has since been redirected to first focus on 100-kW class systems for relatively near-term robotic missions, with possible future evolution to megawatt-and multi-megawatt-class systems applicable to cargo vehicles supporting human missions as well as to the piloted vehicles. This paper reviews current plans and recent progress for the overall nuclear electric propulsion project and closely related activities. 33 refs

Ultrasonic propulsion of kidney stones.

Science.gov (United States)

May, Philip C; Bailey, Michael R; Harper, Jonathan D

2016-05-01

Ultrasonic propulsion is a novel technique that uses short bursts of focused ultrasonic pulses to reposition stones transcutaneously within the renal collecting system and ureter. The purpose of this review is to discuss the initial testing of effectiveness and safety, directions for refinement of technique and technology, and opinions on clinical application. Preclinical studies with a range of probes, interfaces, and outputs have demonstrated feasibility and consistent safety of ultrasonic propulsion with room for increased outputs and refinement toward specific applications. Ultrasonic propulsion was used painlessly and without adverse events to reposition stones in 14 of 15 human study participants without restrictions on patient size, stone size, or stone location. The initial feasibility study showed applicability in a range of clinically relevant situations, including facilitating passage of residual fragments following ureteroscopy or shock wave lithotripsy, moving a large stone at the ureteropelvic junction with relief of pain, and differentiating large stones from a collection of small fragments. Ultrasonic propulsion shows promise as an office-based system for transcutaneously repositioning kidney stones. Potential applications include facilitating expulsion of residual fragments following ureteroscopy or shock wave lithotripsy, repositioning stones prior to treatment, and repositioning obstructing ureteropelvic junction stones into the kidney to alleviate acute renal colic.

Hybrid-electric propulsion for automotive and aviation applications

OpenAIRE

Friedrich, C; Robertson, Paul Andrew

2014-01-01

In parallel with the automotive industry, hybrid-electric propulsion is becoming a viable alternative propulsion technology for the aviation sector and reveals potential advantages including fuel savings, lower pollution, and reduced noise emission. Hybrid-electric propulsion systems can take advantage of the synergy between two technologies by utilizing both internal combustion engines and electric motors together, each operating at their respective optimum conditions...

Electric Motors for Vehicle Propulsion

OpenAIRE

Larsson, Martin

2014-01-01

This work is intended to contribute with knowledge to the area of electic motorsfor propulsion in the vehicle industry. This is done by first studying the differentelectric motors available, the motors suitable for vehicle propulsion are then dividedinto four different types to be studied separately. These four types are thedirect current, induction, permanent magnet and switched reluctance motors. Thedesign and construction are then studied to understand how the different typesdiffer from ea...

Propulsive efficiency of a biomorphic pulsed-jet underwater vehicle

International Nuclear Information System (INIS)

Moslemi, Ali A; Krueger, Paul S

2010-01-01

The effect of the velocity program and duty cycle (St L ) on the propulsive efficiency of pulsed-jet propulsion was studied experimentally on a self-propelled, pulsed-jet underwater vehicle, dubbed Robosquid due to the similarity of essential elements of its propulsion system with squid jet propulsion. Robosquid was tested for jet slug length-to-diameter ratios (L/D) in the range 2-6 and St L in the range 0.2-0.6 with jet velocity programs commanded to be triangular or trapezoidal. Digital particle image velocimetry was used for measuring the impulse and energy of jet pulses to calculate the pulsed-jet propulsive efficiency and compare it with an equivalent steady jet system. Robosquid's Reynolds number (Re) based on average vehicle velocity and vehicle diameter ranged between 1300 and 2700 for the conditions tested. The results indicated better propulsive efficiency of the trapezoidal velocity program (up to 20% higher) compared to the triangular velocity program. Also, an increase in the ratio of the pulsed-jet propulsive efficiency to the equivalent steady jet propulsive efficiency (η P /η P,ss ) was observed as St L increased and L/D decreased. For cases of short L/D and high St L , η P /η P,ss was found to be as high as 1.2, indicating better performance of pulsed jets. This result demonstrates a case where propulsion using essential elements of a biological locomotion system can outperform the traditional mechanical system equivalent in terms of efficiency. It was also found that changes in St L had a proportionately larger effect on propulsive efficiency compared to changes in L/D. A simple model is presented to explain the results in terms of the contribution of over-pressure at the nozzle exit plane associated with the formation of vortex rings with each jet pulse.

A Power-Efficient Propulsion Method for Magnetic Microrobots

Directory of Open Access Journals (Sweden)

Gioia Lucarini

2014-07-01

Full Text Available Current magnetic systems for microrobotic navigation consist of assemblies of electromagnets, which allow for the wireless accurate steering and propulsion of sub-millimetric bodies. However, large numbers of windings and/or high currents are needed in order to generate suitable magnetic fields and gradients. This means that magnetic navigation systems are typically cumbersome and require a lot of power, thus limiting their application fields. In this paper, we propose a novel propulsion method that is able to dramatically reduce the power demand of such systems. This propulsion method was conceived for navigation systems that achieve propulsion by pulling microrobots with magnetic gradients. We compare this power-efficient propulsion method with the traditional pulling propulsion, in the case of a microrobot swimming in a micro-structured confined liquid environment. Results show that both methods are equivalent in terms of accuracy and the velocity of the motion of the microrobots, while the new approach requires only one ninth of the power needed to generate the magnetic gradients. Substantial equivalence is demonstrated also in terms of the manoeuvrability of user-controlled microrobots along a complex path.

A cermet fuel reactor for nuclear thermal propulsion

Science.gov (United States)

Kruger, Gordon

1991-01-01

Work on the cermet fuel reactor done in the 1960's by General Electric (GE) and the Argonne National Laboratory (ANL) that had as its goal the development of systems that could be used for nuclear rocket propulsion as well as closed cycle propulsion system designs for ship propulsion, space nuclear propulsion, and other propulsion systems is reviewed. It is concluded that the work done in the 1960's has demonstrated that we can have excellent thermal and mechanical performance with cermet fuel. Thousands of hours of testing were performed on the cermet fuel at both GE and AGL, including very rapid transients and some radiation performance history. We conclude that there are no feasibility issues with cermet fuel. What is needed is reactivation of existing technology and qualification testing of a specific fuel form. We believe this can be done with a minimum development risk.

S.S.T.O. performance assessment with in-flight lox collection

Science.gov (United States)

Vandenkerckhove, J.; Czysz, P.

1995-10-01

Much attention has recently been given, up to harware development to in-flight oxygen collection as a means to improve considerably the performance of both TSTO & SSTO vehicles. A first assessment suggests that it permits simultaneously to improve much both gross take-off weight (by more than 30%) & dry weight (by more than 15%) of an SSTO and to lower significantly the Mach number of transition scramjet → rocket, from 15 down below 10, thereby reducing dramatically the programmatic development risks. After having compared in-flight lox collection with other SSTO concepts, this paper provides a tentative assessment of the performance of SSTO vehicles taking advantage of it, in particular their sensitivity to changes in system characteristics such as transition Mach number, vehicle slenderness (i.e. Küchemann's parameter τ) or planform loading at take-off and in collection characteristics, in particular collection ratio & specific collection plant weight.

A photoactivatable Cre-loxP recombination system for optogenetic genome engineering.

Science.gov (United States)

Kawano, Fuun; Okazaki, Risako; Yazawa, Masayuki; Sato, Moritoshi

2016-12-01

Genome engineering techniques represented by the Cre-loxP recombination system have been used extensively for biomedical research. However, powerful and useful techniques for genome engineering that have high spatiotemporal precision remain elusive. Here we develop a highly efficient photoactivatable Cre recombinase (PA-Cre) to optogenetically control genome engineering in vivo. PA-Cre is based on the reassembly of split Cre fragments by light-inducible dimerization of the Magnet system. PA-Cre enables sharp induction (up to 320-fold) of DNA recombination and is efficiently activated even by low-intensity illumination (∼0.04 W m -2 ) or short periods of pulsed illumination (∼30 s). We demonstrate that PA-Cre allows for efficient DNA recombination in an internal organ of living mice through noninvasive external illumination using a LED light source. The present PA-Cre provides a powerful tool to greatly facilitate optogenetic genome engineering in vivo.

Airbreathing Propulsion An Introduction

CERN Document Server

Bose, Tarit

2012-01-01

Airbreathing Propulsion covers the physics of combustion, fluid and thermo-dynamics, and structural mechanics of airbreathing engines, including piston, turboprop, turbojet, turbofan, and ramjet engines. End-of-chapter exercises allow the reader to practice the fundamental concepts behind airbreathing propulsion, and the included PAGIC computer code will help the reader to examine the relationships between the performance parameters of different engines. Large amounts of data on many different piston, turbojet, and turboprop engines have been compiled for this book and are included as an appendix. This textbook is ideal for senior undergraduate and graduate students studying aeronautical engineering, aerospace engineering, and mechanical engineering.

Advanced Chemical Propulsion

Science.gov (United States)

Bai, S. Don

2000-01-01

Design, propellant selection, and launch assistance for advanced chemical propulsion system is discussed. Topics discussed include: rocket design, advance fuel and high energy density materials, launch assist, and criteria for fuel selection.

Pressure-Fed LOX/LCH4 Reaction Control System for Spacecraft: Transient Modeling and Thermal Vacuum Hotfire Test Results

Science.gov (United States)

Atwell, Matthew J.; Hurlbert, Eric A.; Melcher, J. C.; Morehead, Robert L.

2017-01-01

An integrated cryogenic liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA), a pressure-fed LOX/LCH4 propulsion system composed of a single 2,800 lbf main engine, two 28 lbf RCS engines, and two 7 lbf RCS engines. Propellants are stored in four 48 inch diameter 5083 aluminum tanks that feed both the main engine and RCS engines in parallel. Helium stored cryogenically in a composite overwrapped pressure vessel (COPV) flows through a heat exchanger on the main engine before being used to pressurize the propellant tanks to a design operating pressure of 325 psi. The ICPTA is capable of simultaneous main engine and RCS operation. The RCS engines utilize a coil-on-plug (COP) ignition system designed for operation in a vacuum environment, eliminating corona discharge issues associated with a high voltage lead. There are two RCS pods on the ICPTA, with two engines on each pod. One of these two engines is a heritage flight engine from Project Morpheus. Its sea level nozzle was removed and replaced by an 85:1 nozzle machined using Inconel 718, resulting in a maximum thrust of 28 lbf under altitude conditions. The other engine is a scaled down version of the 28 lbf engine, designed to match the core and overall mixture ratios as well as other injector characteristics. This engine can produce a maximum thrust of 7 lbf with an 85:1 nozzle that was additively manufactured using Inconel 718. Both engines are film-cooled and capable of limited duration gas-gas and gas-liquid operation, as well as steady-state liquid-liquid operation. Each pod contains one of each version, such that two engines of the same thrust level can be fired as a couple on opposite pods. The RCS feed system is composed of symmetrical 3/8 inch lines

Real-time feedback enhances forward propulsion during walking in old adults.

Science.gov (United States)

Franz, Jason R; Maletis, Michela; Kram, Rodger

2014-01-01

Reduced propulsive function during the push-off phase of walking plays a central role in the deterioration of walking ability with age. We used real-time propulsive feedback to test the hypothesis that old adults have an underutilized propulsive reserve available during walking. 8 old adults (mean [SD], age: 72.1 [3.9] years) and 11 young adults (age: 21.0 [1.5] years) participated. For our primary aim, old subjects walked: 1) normally, 2) with visual feedback of their peak propulsive ground reaction forces, and 3) with visual feedback of their medial gastrocnemius electromyographic activity during push-off. We asked those subjects to match a target set to 20% and 40% greater propulsive force or push-off muscle activity than normal walking. We tested young subjects walking normally only to provide reference ground reaction force values. Walking normally, old adults exerted 12.5% smaller peak propulsive forces than young adults (Ppush-off muscle activities when we provided propulsive feedback. Most notably, force feedback elicited propulsive forces that were equal to or 10.5% greater than those of young adults (+20% target, P=0.87; +40% target, P=0.02). With electromyographic feedback, old adults significantly increased their push-off muscle activities but without increasing their propulsive forces. Old adults with propulsive deficits have a considerable and underutilized propulsive reserve available during level walking. Further, real-time propulsive feedback represents a promising therapeutic strategy to improve the forward propulsion of old adults and thus maintain their walking ability and independence. © 2013.

Magnetic levitation and MHD propulsion

International Nuclear Information System (INIS)

Tixador, P.

1994-01-01

Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried our in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ..) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. (orig.)

Magnetic levitation and MHD propulsion

Energy Technology Data Exchange (ETDEWEB)

Tixador, P [CNRS/CRTBT-LEG, 38 - Grenoble (France)

1994-04-01

Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried our in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ..) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. (orig.).

STATIC TESTS OF UNCONVENTIONAL PROPULSION UNITS FOR ULTRALIGHT AIRPLANES

Directory of Open Access Journals (Sweden)

Martin Helmich

2014-06-01

Full Text Available This paper presents static tests of a new unconventional propulsion unit for small aviation airplanes. Our laboratory stand – a fan drive demonstrator – enables us to compare various design options. We performed experiments to verify the propulsion functionality and a measurement procedure to determine the available thrust of the propulsion unit and its dependence on engine speed. The results used for subsequent optimization include the operating parameters of the propulsion unit, and the temperature and velocity fields in parts of the air duct.

Mobile Augmented Reality Applications

OpenAIRE

Prochazka, David; Stencl, Michael; Popelka, Ondrej; Stastny, Jiri

2011-01-01

Augmented reality have undergone considerable improvement in past years. Many special techniques and hardware devices were developed, but the crucial breakthrough came with the spread of intelligent mobile phones. This enabled mass spread of augmented reality applications. However mobile devices have limited hardware capabilities, which narrows down the methods usable for scene analysis. In this article we propose an augmented reality application which is using cloud computing to enable using...

An Overview of the CNES Propulsion Program for Spacecraft

Science.gov (United States)

Cadiou, A.; Darnon, F.; Gibek, I.; Jolivet, L.; Pillet, N.

2004-10-01

This paper presents an overview of the CNES spacecraft propulsion activities. The main existing and future projects corresponding to low earth orbit and geostationary platforms are described. These projects cover various types of propulsion subsystems: monopropellant, bipropellant and electric. Monopropellant is mainly used for low earth orbit applications such as earth observation (SPOT/Helios, PLEIADES) or scientific applications (minisatellite PROTEUS line and micro satellites MYRIADE line). Bipropellant is used for geostationary telecommunications satellites (@BUS). The field of application of electric propulsion is the station keeping of geostationary telecommunication satellites (@BUS), main propulsion for specific probes (SMART 1) and fine attitude control for dedicated micro satellites (MICROSCOPE). The preparation of the future and the associated Research and Technology program are also described in the paper. The future developments are mainly dedicated to the performance improvements of electric propulsion which leads to the development of thrusters with higher thrust and higher specific impulse than those existing today, the evaluation of the different low thrust technologies for formation flying applications, the development of new systems to pressurize the propellants (volatile liquid, micro pump), the research on green propellants and different actions concerning components such as over wrapped pressure vessels, valves, micro propulsion. A constant effort is also put on plume effect in chemical and electrical propulsion area (improvement of tools and test activities) in the continuity of the previous work. These different R &T activities are described in detail after a presentation of the different projects and of their propulsion subsystems. The scientific activity supporting the development of Hall thrusters is going on in the frame of the GDR (Groupement de Recherche) CNRS / Universities / CNES / SNECMA on Plasma Propulsion.

A comparison of propulsion systems for potential space mission applications

International Nuclear Information System (INIS)

Harvego, E.A.; Sulmeisters, T.K.

1987-01-01

A derivative of the NERVA nuclear rocket engine was compared with a chemical propulsion system and a nuclear electric propulsion system to assess the relative capabilities of the different propulsion system options for three potential space missions. The missions considered were (1) orbital transfer from low earth orbit (LEO) to geosynchronous earth orbit (GEO), (2) LEO to a lunar base, and (3) LEO to Mars. The results of this comparison indicate that the direct-thrust NERVA-derivative nuclear rocket engine has the best performance characteristics for the missions considered. The combined high thrust and high specific impulse achievable with a direct-thrust nuclear stage permits short operating times (transfer times) comparable to chemical propulsion systems, but with considerably less required propellant. While nuclear-electric propulsion systems are more fuel efficient than either direct-nuclear or chemical propulsion, they are not stand-alone systems, since their relatively low thrust levels require the use of high-thrust ferry or lander stages in high gravity applications such as surface-to-orbit propulsion. The extremely long transfer times and inefficient trajectories associated with electric propulsion systems were also found to be a significant drawback

Research on applications of rectangular beam in micro laser propulsion

International Nuclear Information System (INIS)

Jiao, L.; Cai, J.; Ma, H.H.; Li, G.X.; Li, L.; Shen, Z.W.; Tang, Z.P.

2014-01-01

Highlights: • Diode laser bar of 808 nm is introduced into the micro laser propulsion field. • Double base propellant (DBP) coating with BOPP substrate was obtained. • The combination of laser power and energy decides the propulsion performance. • The new rectangular beam prefers to produce higher impulse. - Abstract: Micro laser propulsion is a new technology with brilliant future. In order to reduce the thruster mass and volume further, laser bar is introduced into the micro laser propulsion field. A new kind of 220 × 20 μm rectangular beam of 808 nm was obtained by oval lens compressing the light of diode at fast axes and slow axes. The effect of laser power, energy and coating thickness of double base propellant on propulsion performance was studied. Propulsion performance of double base propellant under static and dynamic mode shows some different characters. Compared to round beam, the new beam prefers to produce higher impulse. Ablation efficiency of DBP shows better performance in short laser duration. The combination of power density and energy density decides the laser propulsion performance. The new rectangular beam is appropriate for millisecond micro-laser propulsion

Augmenting Clozapine With Sertindole

DEFF Research Database (Denmark)

Nielsen, Jimmi; Emborg, Charlotte; Gydesen, Susanne

2012-01-01

Clozapine augmentation with antipsychotic drugs is widely used despite sparse evidence supporting this strategy. Sertindole is a nonsedating atypical antipsychotic drug with low affinity for cholinergic receptors, which makes it potentially suitable for augmentation of clozapine. The study design...... glucose, lipids, and electrocardiogram. Clozapine augmentation with sertindole was not superior to placebo regarding total score or subscale score of the Positive and Negative Syndrome Scale, Clinical Global Impression, World Health Organization Quality of Life Brief, or Drug Attitude Inventory....... No increased adverse effects compared with placebo were found. Four patients randomized to sertindole experienced a significant worsening of psychosis, and 2 of them required psychiatric admission. Metabolic parameters were unchanged during the study, but augmentation of clozapine with sertindole...

The influence of verbal training and visual feedback on manual wheelchair propulsion.

Science.gov (United States)

DeGroot, Keri K; Hollingsworth, Holly H; Morgan, Kerri A; Morris, Carrie L; Gray, David B

2009-03-01

To determine if verbal training with visual feedback improved manual wheelchair propulsion; to examine propulsion differences between an individual with paraplegia and an individual with tetraplegia. Quasi-experimental study: Nine manual wheelchair-using adults participated in propulsion assessments and training. Baseline propulsion performance was measured on several tasks on different surfaces. Participants were trained on a wheelchair treadmill with verbal and visual feedback to increase push length, reduce push frequency and to modify propulsion pattern. Handrim biomechanics were measured with an instrumented wheel. Changes in propulsion were assessed. Differences in propulsion characteristics between a participant with paraplegia and a participant with tetraplegia were examined. Push length increased (p propulsion characteristics between a participant with paraplegia and a participant with tetraplegia. Verbal training may produce changes in push biomechanics of manual wheelchair users. Longer training periods may be needed to sustain propulsion changes. Findings from this study support other studies that have shown propulsion differences between people with tetraplegia and paraplegia. Propulsion training for populations with upper-extremity impairments warrants further study.

[Augmentation technique on the proximal humerus].

Science.gov (United States)

Scola, A; Gebhard, F; Röderer, G

2015-09-01

The treatment of osteoporotic fractures is still a challenge. The advantages of augmentation with respect to primary in vitro stability and the clinical use for the proximal humerus are presented in this article. In this study six paired human humeri were randomized into an augmented and a non-augmented group. Osteosynthesis was performed with a PHILOS plate (Synthes®). In the augmented group the two screws finding purchase in the weakest cancellous bone were augmented. The specimens were tested in a 3-part fracture model in a varus bending test. The augmented PHILOS plates withstood significantly more load cycles until failure. The correlation to bone mineral density (BMD) showed that augmentation could partially compensate for low BMD. The augmentation of the screws in locked plating in a proximal humerus fracture model is effective in improving the primary stability in a cyclic varus bending test. The targeted augmentation of two particular screws in a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required. The technique of augmentation is simple and can be applied in open and minimally invasive procedures. When the correct procedure is used, complications (cement leakage into the joint) can be avoided.

Augmented reality and ubiquitous computing : The hidden potentialities of augmented reality

NARCIS (Netherlands)

Liberati, Nicola

2016-01-01

The aim of this paper was to highlight the augmented reality’s potentialities, depicting its main characteristics and focusing attention on what its goal should be in order to have a new technology completely different from those that already exist. From a technological point of view, augmented

Capillary Refill using Augmented Reality

OpenAIRE

Clausen, Christoffer

2017-01-01

Master's thesis in Computer science The opportunities within augmented reality is growing. Augmented reality is a combination of the real and the virtual world in real time, and large companies like Microsoft and Google is now investing heavily in the technology. This thesis presents a solution for simulating a medical test called capillary refill, by using augmented reality. The simulation is performed with an augmented reality headset called HoloLens. The HoloLens will recognise a mark...

Propulsion Electric Grid Simulator (PEGS) for Future Turboelectric Distributed Propulsion Aircraft

Science.gov (United States)

Choi, Benjamin B.; Morrison, Carlos; Dever, Timothy; Brown, Gerald V.

2014-01-01

NASA Glenn Research Center, in collaboration with the aerospace industry and academia, has begun the development of technology for a future hybrid-wing body electric airplane with a turboelectric distributed propulsion (TeDP) system. It is essential to design a subscale system to emulate the TeDP power grid, which would enable rapid analysis and demonstration of the proof-of-concept of the TeDP electrical system. This paper describes how small electrical machines with their controllers can emulate all the components in a TeDP power train. The whole system model in Matlab/Simulink was first developed and tested in simulation, and the simulation results showed that system dynamic characteristics could be implemented by using the closed-loop control of the electric motor drive systems. Then we designed a subscale experimental system to emulate the entire power system from the turbine engine to the propulsive fans. Firstly, we built a system to emulate a gas turbine engine driving a generator, consisting of two permanent magnet (PM) motors with brushless motor drives, coupled by a shaft. We programmed the first motor and its drive to mimic the speed-torque characteristic of the gas turbine engine, while the second motor and drive act as a generator and produce a torque load on the first motor. Secondly, we built another system of two PM motors and drives to emulate a motor driving a propulsive fan. We programmed the first motor and drive to emulate a wound-rotor synchronous motor. The propulsive fan was emulated by implementing fan maps and flight conditions into the fourth motor and drive, which produce a torque load on the driving motor. The stator of each PM motor is designed to travel axially to change the coupling between rotor and stator. This feature allows the PM motor to more closely emulate a wound-rotor synchronous machine. These techniques can convert the plain motor system into a unique TeDP power grid emulator that enables real-time simulation performance

PEGASUS: a multi-megawatt nuclear electric propulsion system

International Nuclear Information System (INIS)

Coomes, E.P.; Cuta, J.M.; Webb, B.J.; King, D.Q.

1985-06-01

With the Space Transportation System (STS), the advent of space station Columbus and the development of expertise at working in space that this will entail, the gateway is open to the final frontier. The exploration of this frontier is possible with state-of-the-art hydrogen/oxygen propulsion but would be greatly enhanced by the higher specific impulse of electric propulsion. This paper presents a concept that uses a multi-megawatt nuclear power plant to drive an electric propulsion system. The concept has been named PEGASUS, PowEr GenerAting System for Use in Space, and is intended as a ''work horse'' for general space transportation needs, both long- and short-haul missions. The recent efforts of the SP-100 program indicate that a power system capable of producing upwards of 1 megawatt of electric power should be available in the next decade. Additionally, efforts in other areas indicate that a power system with a constant power capability an order of magnitude greater could be available near the turn of the century. With the advances expected in megawatt-class space power systems, the high specific impulse propulsion systems must be reconsidered as potential propulsion systems. The power system is capable of meeting both the propulsion system and spacecraft power requirements

Non-Toxic Orbital Maneuvering System Engine Development

Science.gov (United States)

Green, Christopher; Claflin, Scott; Maeding, Chris; Butas, John

1999-01-01

Recent results using the Aestus engine operated with LOx/ethanol propellant are presented. An experimental program at Rocketdyne Propulsion and Power is underway to adapt this engine for the Boeing Reusable Space Systems Division non-toxic Orbital Maneuvering System/Reaction control System (OMS/RCS) system. Daimler-Chrysler Aerospace designed the Aestus as an nitrogen tetroxide/monomethyl hydrazine (NTO/MMH) upper-stage engine for the Ariane 5. The non-toxic OMS/RCS system's preliminary design requires a LOx/ethanol (O2/C2H5OH) engine that operates with a mixture ratio of 1.8, a specific impulse of 323 seconds, and fits within the original OMS design envelope. This paper describes current efforts to meet these requirements including, investigating engine performance using LOx/ethanol, developing the en-ine system sizing package, and meeting the vehicle operation parameters. Data from hot-fire testing are also presented and discussed.

Propulsion Wheel Motor for an Electric Vehicle

Science.gov (United States)

Figuered, Joshua M. (Inventor); Herrera, Eduardo (Inventor); Waligora, Thomas M. (Inventor); Bluethmann, William J. (Inventor); Farrell, Logan Christopher (Inventor); Lee, Chunhao J. (Inventor); Vitale, Robert L. (Inventor); Winn, Ross Briant (Inventor); Eggleston, IV, Raymond Edward (Inventor); Guo, Raymond (Inventor);

Study of underwater laser propulsion using different target materials.

Science.gov (United States)

Qiang, Hao; Chen, Jun; Han, Bing; Shen, Zhong-Hua; Lu, Jian; Ni, Xiao-Wu

2014-07-14

In order to investigate the influence of target materials, including aluminum (Al), titanium (Ti) and copper (Cu), on underwater laser propulsion, the analytical formula of the target momentum IT is deduced from the enhanced coupling theory of laser propulsion in atmosphere with transparent overlay metal target. The high-speed photography method and numerical simulation are employed to verify the IT model. It is shown that the enhanced coupling theory, which was developed originally for laser propulsion in atmosphere, is also applicable to underwater laser propulsion with metal targets.

The Benefits of Nuclear Thermal Propulsion (NTP) in an Evolvable Mars Campaign

Science.gov (United States)

Borowski, Stanley K.; Mccurdy, David R.

2014-01-01

NTR: High thrust high specific impulse (2 x LOXLH2chemical) engine uses high power density fission reactor with enriched uranium fuel as thermal power source. Reactor heat is removed using H2propellant which is then exhausted to produce thrust. Conventional chemical engine LH2tanks, turbopumps, regenerative nozzles and radiation-cooled shirt extensions used --NTR is next evolutionary step in high performance liquid rocket engines During the Rover program, a common fuel element tie tube design was developed and used in the design of the 50 klbf Kiwi-B4E (1964), 75 klbf Phoebus-1B (1967), 250 klbf Phoebus-2A (June 1968), then back down to the 25 klbf Pewee engine (Nov-Dec 1968) NASA and DOE are using this same approach: design, build, ground then flight test a small engine using a common fuel element that is scalable to a larger 25 klbf thrust engine needed for human missions

Mars Sample Return Using Solar Sail Propulsion

Science.gov (United States)

Johnson, Les; Macdonald, Malcolm; Mcinnes, Colin; Percy, Tom

2012-01-01

Many Mars Sample Return (MSR) architecture studies have been conducted over the years. A key element of them is the Earth Return Stage (ERS) whose objective is to obtain the sample from the Mars Ascent Vehicle (MAV) and return it safely to the surface of the Earth. ERS designs predominantly use chemical propulsion [1], incurring a significant launch mass penalty due to the low specific impulse of such systems coupled with the launch mass sensitivity to returned mass. It is proposed to use solar sail propulsion for the ERS, providing a high (effective) specific impulse propulsion system in the final stage of the multi-stage system. By doing so to the launch mass of the orbiter mission can be significantly reduced and hence potentially decreasing mission cost. Further, solar sailing offers a unique set of non-Keplerian low thrust trajectories that may enable modifications to the current approach to designing the Earth Entry Vehicle by potentially reducing the Earth arrival velocity. This modification will further decrease the mass of the orbiter system. Solar sail propulsion uses sunlight to propel vehicles through space by reflecting solar photons from a large, mirror-like surface made of a lightweight, reflective material. The continuous photonic pressure provides propellantless thrust to conduct orbital maneuvering and plane changes more efficiently than conventional chemical propulsion. Because the Sun supplies the necessary propulsive energy, solar sails require no onboard propellant, thus reducing system mass. This technology is currently at TRL 7/8 as demonstrated by the 2010 flight of the Japanese Aerospace Exploration Agency, JAXA, IKAROS mission. [2

DISCRETION MAGNETIQUE DES MACHINES ELECTRIQUES DE PROPULSION NAVALE

OpenAIRE

Froidurot , Benoît

2002-01-01

For about ten years, electrical machines have been commonly used in naval propulsion systems for civilian applications. This is mainly due to new magnetic materials (magnets...) and power drive electronic, which increase the performances of the machines. This kind of propulsion is planed to be implemented on military ships. However, some constraints of discretion make this propulsion require specific systems for the ship security. This study is then dedicted to the magnetic discretion of nava...

Children's Gender-Typed Toy Interests: Does Propulsion Matter?

Science.gov (United States)

Dinella, Lisa M; Weisgram, Erica S; Fulcher, Megan

2017-07-01

Children's toy play is at the foundation of child development. However, gender differentiation in early play experiences may result in gender differences in cognitive abilities, social interactions, and vocational choices. We investigated gender-typing of toys and toys' propulsive properties (e.g., wheels, forward motion) as possible factors impacting children's toy interests, perceptions of other children's interests, and children's actual toy choices during free play. In Studies 1 and 2, 82 preschool children (42 boys, 40 girls; mean age = 4.90 years) were asked to report their interest and perceptions of other children's interests in toys. In Study 1, masculine, feminine, and neutral toys with and without propulsive properties were presented. Children reported greater interest in gender-typed toys and neutral toys compared to cross-gender-typed toys. In Study 2, unfamiliar, neutral toys with and without propulsive properties were presented. Propulsive properties did not affect children's interest across both studies. Study 3 was an observational study that assessed toy preferences among 42 preschool children (21 males, 21 females, mean age = 4.49 years) during a play session with masculine, feminine, and neutral toys with and without propulsive properties. Gender-typed toy preferences were less apparent than expected, with children showing high interest in neutral toys, and girls playing with a wide variety of masculine, feminine, and neutral toys. Gender differences in interest for toys with propulsion properties were not evident. Overall, gender differences in children's interest in toys as a function of propulsion properties were not found in the three experiments within this study.

The Enabling Use of Ion Propulsion on Dawn

Science.gov (United States)

Rayman, M.; Russell, C. T.; Raymond, C. A.; Mase, R. M.

2011-12-01

Dawn's mission to orbit both Vesta and Ceres is enabled by its use of ion propulsion. Even orbiting Vesta alone with conventional propulsion would have been unaffordable within the constraints of the Discovery Program, and orbiting both would have been impossible. In fact, no other spacecraft has been targeted to orbit two solar system destinations, which is only one of the many firsts that Dawn will achieve. The successful testing of ion propulsion on Deep Space 1 paved the way for Dawn not only to use the hardware with confidence but also to learn how to design the flight system and design the mission to take advantage of its capabilities. In addition to allowing Dawn to reach these two important targets, ion propulsion allows the spacecraft to accomplish significant changes in its orbit. Therefore, science observations of Vesta are planned from four different orbits, at varying altitudes and solar geometry. The use of ion propulsion results in a significant mission design effort since the trajectory is constantly being refined. This also creates a flexible mission architecture, which allows for optimization of the mission as conditions change. Solar electric ion propulsion is especially well suited to missions to the Main Asteroid Belt since solar energy is still a viable power source, whereas the size of the solar array needed beyond 3.5 AU is a potential limitation. Dawn has already surpassed the record for greatest propulsive velocity, but its greatest achievements will no doubt be the incredible bounty of science data enabled by this innovative flight system.

Implementation of a Gadolinium Burnable Absorber in the Carbide LEU-NTR

International Nuclear Information System (INIS)

Venneria, Paolo; Kim, Yonghee

2015-01-01

Among the most crucial are the rapid reactivity depletion during full-power operation and the positive reactivity insertion during the full-submersion criticality accident. In previous work, it has been suggested that both challenges can be mitigated through the successful implementation of a burnable absorber in the active core. Of the poisons previously surveyed, one of the most promising is Gadolinium in the form of Gadolina (Gd2O4). This paper explores the possibility of different methods by which the Gadolinia can be implemented in the core and makes a preliminary study of its effect on the full submersion criticality accident and the reactivity depletion during operation. The application of a Gadolinium neutron absorber in the active core region of the LEU-NTR has been shown to be neutronically feasible. It can be introduced into the core in various locations without resulting in core performance loss. The utility of the poison in terms of mitigating the full-submersion reactivity accident and the rapid change in reactivity during full-power operation have been preliminarily shown and the first steps towards eventual implementation made. Future work will consist of determining the maximum poison content in the core and tailoring the self-shielding effect in order to determine a specific Gd depletion rate

Space station propulsion requirements study

Science.gov (United States)

Wilkinson, C. L.; Brennan, S. M.

1985-01-01

Propulsion system requirements to support Low Earth Orbit (LEO) manned space station development and evolution over a wide range of potential capabilities and for a variety of STS servicing and space station operating strategies are described. The term space station and the overall space station configuration refers, for the purpose of this report, to a group of potential LEO spacecraft that support the overall space station mission. The group consisted of the central space station at 28.5 deg or 90 deg inclinations, unmanned free-flying spacecraft that are both tethered and untethered, a short-range servicing vehicle, and a longer range servicing vehicle capable of GEO payload transfer. The time phasing for preferred propulsion technology approaches is also investigated, as well as the high-leverage, state-of-the-art advancements needed, and the qualitative and quantitative benefits of these advancements on STS/space station operations. The time frame of propulsion technologies applicable to this study is the early 1990's to approximately the year 2000.

NASA program planning on nuclear electric propulsion

International Nuclear Information System (INIS)

Bennett, G.L.; Miller, T.J.

1992-03-01

As part of the focused technology planning for future NASA space science and exploration missions, NASA has initiated a focused technology program to develop the technologies for nuclear electric propulsion and nuclear thermal propulsion. Beginning in 1990, NASA began a series of interagency planning workshops and meetings to identify key technologies and program priorities for nuclear propulsion. The high-priority, near-term technologies that must be developed to make NEP operational for space exploration include scaling thrusters to higher power, developing high-temperature power processing units, and developing high power, low-mass, long-lived nuclear reactors. 28 refs

Definition of an arcjet propulsion sub-system

International Nuclear Information System (INIS)

Price, T.W.

1989-01-01

An engineering flight demonstration of a 100 kW3 Space Reactor Power System is planned for the mid to late 1990s. An arcjet based propulsion subsystem will be included on the flight demonstraction as a secondary experiment. Two studies, sponsored by the Kay Technologies Directorate of the SDI Organization and managed by the Jet Propulsion Laboratory are currently under way to define that propulsion subsystem. The principal tasks of those contracts and the plans for two later phases, an experimental verification of the concept and a flight qualification/delivery of a flight unit, are described. 9 refs

28th Joint Propulsion Conference and Exhibit

International Nuclear Information System (INIS)

Stone, J.R.; Sovey, J.S.

1992-07-01

The National Aeronautics and Space Administration (NASA) has initiated a program to establish the readiness of nuclear electric propulsion (NEP) technology for relatively near-term applications to outer planet robotic science missions with potential future evolution to system for piloted Mars vehicles. This program was initiated in 1991 with a very modest effort identified with nuclear thermal propulsion (NTP); however, NEP is also an integral part of this program and builds upon NASA's Base Research and Technology Program in power and electric propulsion as well as the SP-100 space nuclear power program. The NEP Program will establish the feasibility and practicality of electric propulsion for robotic and piloted solar system exploration. The performance objectives are high specific impulse (200 greater than I(sub sp) greater than 10000 s), high efficiency (over 0.50), and low specific mass. The planning for this program was initially focussed on piloted Mars missions, but has since been redirected to first focus on 100-kW class systems for relatively near-term robotic missions, with possible future evolution to megawatt- and multi-megawatt-class systems applicable to cargo vehicles supporting human missions as well as to the piloted vehicles. This paper reviews current plans and recent progress for the overall nuclear electric propulsion project and closely related activities

Nuclear thermal propulsion engine cost trade studies

International Nuclear Information System (INIS)

Paschall, R.K.

1993-01-01

The NASA transportation strategy for the Mars Exploration architecture includes the use of nuclear thermal propulsion as the primary propulsion system for Mars transits. It is anticipated that the outgrowth of the NERVA/ROVER programs will be a nuclear thermal propulsion (NTP) system capable of providing the propulsion for missions to Mars. The specific impulse (Isp) for such a system is expected to be in the 870 s range. Trade studies were conducted to investigate whether or not it may be cost effective to invest in a higher performance (Isp>870 s) engine for nuclear thermal propulsion for missions to Mars. The basic cost trades revolved around the amount of mass that must be transported to low-earth orbit prior to each Mars flight and the cost to launch that mass. The mass required depended on the assumptions made for Mars missions scenarios including piloted/cargo flights, number of Mars missions, and transit time to Mars. Cost parameters included launch cost, program schedule for development and operations, and net discount rate. The results were very dependent on the assumptions that were made. Under some assumptions, higher performance engines showed cost savings in the billions of dollars; under other assumptions, the additional cost to develop higher performance engines was not justified

Status and Mission Applicability of NASA's In-Space Propulsion Technology Project

Science.gov (United States)

Anderson, David J.; Munk, Michelle M.; Dankanich, John; Pencil, Eric; Liou, Larry

2009-01-01

The In-Space Propulsion Technology (ISPT) project develops propulsion technologies that will enable or enhance NASA robotic science missions. Since 2001, the ISPT project developed and delivered products to assist technology infusion and quantify mission applicability and benefits through mission analysis and tools. These in-space propulsion technologies are applicable, and potentially enabling for flagship destinations currently under evaluation, as well as having broad applicability to future Discovery and New Frontiers mission solicitations. This paper provides status of the technology development, near-term mission benefits, applicability, and availability of in-space propulsion technologies in the areas of advanced chemical thrusters, electric propulsion, aerocapture, and systems analysis tools. The current chemical propulsion investment is on the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance for lower cost. Investments in electric propulsion technologies focused on completing NASA's Evolutionary Xenon Thruster (NEXT) ion propulsion system, a 0.6-7 kW throttle-able gridded ion system, and the High Voltage Hall Accelerator (HiVHAC) thruster, which is a mid-term product specifically designed for a low-cost electric propulsion option. Aerocapture investments developed a family of thermal protections system materials and structures; guidance, navigation, and control models of blunt-body rigid aeroshells; atmospheric models for Earth, Titan, Mars and Venus; and models for aerothermal effects. In 2009 ISPT started the development of propulsion technologies that would enable future sample return missions. The paper describes the ISPT project's future focus on propulsion for sample return missions. The future technology development areas for ISPT is: Planetary Ascent Vehicles (PAV), with a Mars Ascent Vehicle (MAV) being the initial development focus; multi-mission technologies for Earth Entry Vehicles (MMEEV) needed

Laser Propulsion - Is it another myth or a real potential?

International Nuclear Information System (INIS)

Cook, Joung R.

2008-01-01

This paper discusses different principles of inducing propulsive power using lasers and examines the performance limits along with pros and cons with respect to different space propulsion applications: satellite launching, orbital transfer, space debris clearing, satellite propulsion, and space travels. It concludes that a use of electrical propulsion, in conjunction with laser power beaming, is the most feasible application with technological and economic advantages for commercial use within the next decades

FY2015 Propulsion Materials Annual Report

Energy Technology Data Exchange (ETDEWEB)

None, None

2016-12-30

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines [ACE], Advanced Power Electronics and Electrical Machines [APEEM], and fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.

Advanced propulsion system for hybrid vehicles

Science.gov (United States)

Norrup, L. V.; Lintz, A. T.

1980-01-01

A number of hybrid propulsion systems were evaluated for application in several different vehicle sizes. A conceptual design was prepared for the most promising configuration. Various system configurations were parametrically evaluated and compared, design tradeoffs performed, and a conceptual design produced. Fifteen vehicle/propulsion systems concepts were parametrically evaluated to select two systems and one vehicle for detailed design tradeoff studies. A single hybrid propulsion system concept and vehicle (five passenger family sedan)were selected for optimization based on the results of the tradeoff studies. The final propulsion system consists of a 65 kW spark-ignition heat engine, a mechanical continuously variable traction transmission, a 20 kW permanent magnet axial-gap traction motor, a variable frequency inverter, a 386 kg lead-acid improved state-of-the-art battery, and a transaxle. The system was configured with a parallel power path between the heat engine and battery. It has two automatic operational modes: electric mode and heat engine mode. Power is always shared between the heat engine and battery during acceleration periods. In both modes, regenerative braking energy is absorbed by the battery.

Measurement Issues In Pulsed Laser Propulsion

International Nuclear Information System (INIS)

Sinko, John E.; Scharring, Stefan; Eckel, Hans-Albert; Roeser, Hans-Peter; Sasoh, Akihiro

2010-01-01

Various measurement techniques have been used throughout the over 40-year history of laser propulsion. Often, these approaches suffered from inconsistencies in definitions of the key parameters that define the physics of laser ablation impulse generation. Such parameters include, but are not limited to the pulse energy, spot area, imparted impulse, and ablated mass. The limits and characteristics of common measurement techniques in each of these areas will be explored as they relate to laser propulsion. The idea of establishing some standardization system for laser propulsion data is introduced in this paper, so that reported results may be considered and studied by the general community with more certain understanding of particular merits and limitations. In particular, it is the intention to propose a minimum set of requirements a literature study should meet. Some international standards for measurements are already published, but modifications or revisions of such standards may be necessary for application to laser ablation propulsion. Issues relating to development of standards will be discussed, as well as some examples of specific experimental circumstances in which standardization would have prevented misinterpretation or misuse of past data.

Augmented Mirror: Interactive Augmented Reality System Based on Kinect

OpenAIRE

Vera , Lucía; Gimeno , Jesús; Coma , Inmaculada; Fernández , Marcos

2011-01-01

Part 1: Long and Short Papers; International audience; In this paper we present a virtual character controlled by an actor in real time, who talks with an audience through an augmented mirror. The application, which integrates video images, the avatar and other virtual objects within an Augmented Reality system, has been implemented using a mixture of technologies: two kinect systems for motion capture, depth map and real images, a gyroscope to detect head movements, and control algorithms to...

Augmented reality in neurosurgery.

Science.gov (United States)

Tagaytayan, Raniel; Kelemen, Arpad; Sik-Lanyi, Cecilia

2018-04-01

Neurosurgery is a medical specialty that relies heavily on imaging. The use of computed tomography and magnetic resonance images during preoperative planning and intraoperative surgical navigation is vital to the success of the surgery and positive patient outcome. Augmented reality application in neurosurgery has the potential to revolutionize and change the way neurosurgeons plan and perform surgical procedures in the future. Augmented reality technology is currently commercially available for neurosurgery for simulation and training. However, the use of augmented reality in the clinical setting is still in its infancy. Researchers are now testing augmented reality system prototypes to determine and address the barriers and limitations of the technology before it can be widely accepted and used in the clinical setting.

AR DOC: Augmented reality documentaries

DEFF Research Database (Denmark)

Vistisen, Peter

2014-01-01

Augmented Reality Documentaries (AR DOC) er et ’lille’ Shareplay projekt (ansøgte midler augmented reality cross media løsninger, til at skabe engagerende publikumsformidling...... indenfor oplevelsesindustrien. Projektet har genereret ny viden omkring, hvordan fysisk og digital formidling kan understøttes via Augmented Reality som formidlingsformat....

Advanced supersonic propulsion study. [with emphasis on noise level reduction

Science.gov (United States)

Sabatella, J. A. (Editor)

1974-01-01

A study was conducted to determine the promising propulsion systems for advanced supersonic transport application, and to identify the critical propulsion technology requirements. It is shown that noise constraints have a major effect on the selection of the various engine types and cycle parameters. Several promising advanced propulsion systems were identified which show the potential of achieving lower levels of sideline jet noise than the first generation supersonic transport systems. The non-afterburning turbojet engine, utilizing a very high level of jet suppression, shows the potential to achieve FAR 36 noise level. The duct-heating turbofan with a low level of jet suppression is the most attractive engine for noise levels from FAR 36 to FAR 36 minus 5 EPNdb, and some series/parallel variable cycle engines show the potential of achieving noise levels down to FAR 36 minus 10 EPNdb with moderate additional penalty. The study also shows that an advanced supersonic commercial transport would benefit appreciably from advanced propulsion technology. The critical propulsion technology needed for a viable supersonic propulsion system, and the required specific propulsion technology programs are outlined.

Distributed Multi-propulsion Units System

OpenAIRE

原田, 正志; HARADA, Masashi

2002-01-01

Reduction of the weight of the propulsion system is important in the design of a stratospheric airship. However, it also important to increaseefficiency of the system because available energy generated by solar cells on the hull is quite limited. One solution to increase efficiency of the propulsion system is to use a stern propeller, the propeller mounted on the stern of the hull as shown in Figure 1. Mounted on the stern of the hull, the stern propeller is merged with the boundary layer of ...

Propulsion and Power Technologies for the NASA Exploration Vision: A Research Perspective

Science.gov (United States)

Litchford, Ron J.

2004-01-01

Future propulsion and power technologies for deep space missions are profiled in this viewgraph presentation. The presentation includes diagrams illustrating possible future travel times to other planets in the solar system. The propulsion technologies researched at Marshall Space Flight Center (MSFC) include: 1) Chemical Propulsion; 2) Nuclear Propulsion; 3) Electric and Plasma Propulsion; 4) Energetics. The presentation contains additional information about these technologies, as well as space reactors, reactor simulation, and the Propulsion Research Laboratory (PRL) at MSFC.

Hybrid Electric Propulsion Technologies for Commercial Transports

Science.gov (United States)

Bowman, Cheryl; Jansen, Ralph; Jankovsky, Amy

2016-01-01

NASA Aeronautics Research Mission Directorate has set strategic research thrusts to address the major drivers of aviation such as growth in demand for high-speed mobility, addressing global climate and capitalizing in the convergence of technological advances. Transitioning aviation to low carbon propulsion is one of the key strategic research thrust and drives the search for alternative and greener propulsion system for advanced aircraft configurations. This work requires multidisciplinary skills coming from multiple entities. The Hybrid Gas-Electric Subproject in the Advanced Air Transportation Project is energizing the transport class landscape by accepting the technical challenge of identifying and validating a transport class aircraft with net benefit from hybrid propulsion. This highly integrated aircraft of the future will only happen if airframe expertise from NASA Langley, modeling and simulation expertise from NASA Ames, propulsion expertise from NASA Glenn, and the flight research capabilities from NASA Armstrong are brought together to leverage the rich capabilities of U.S. Industry and Academia.

A Brief Review of the Need for Robust Smart Wireless Sensor Systems for Future Propulsion Systems, Distributed Engine Controls, and Propulsion Health Management

Science.gov (United States)

Hunter, Gary W.; Behbahani, Alireza

2012-01-01

Smart Sensor Systems with wireless capability operational in high temperature, harsh environments are a significant component in enabling future propulsion systems to meet a range of increasingly demanding requirements. These propulsion systems must incorporate technology that will monitor engine component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This paper discusses the motivation towards the development of high temperature, smart wireless sensor systems that include sensors, electronics, wireless communication, and power. The challenges associated with the use of traditional wired sensor systems will be reviewed and potential advantages of Smart Sensor Systems will be discussed. A brief review of potential applications for wireless smart sensor networks and their potential impact on propulsion system operation, with emphasis on Distributed Engine Control and Propulsion Health Management, will be given. A specific example related to the development of high temperature Smart Sensor Systems based on silicon carbide electronics will be discussed. It is concluded that the development of a range of robust smart wireless sensor systems are a foundation for future development of intelligent propulsion systems with enhanced capabilities.

Legal Implications of Nuclear Propulsion for Space Objects

Science.gov (United States)

Pop, V.

2002-01-01

This paper is intended to examine nuclear propulsion concepts such as "Project Orion", "Project Daedalus", NERVA, VASIMIR, from the legal point of view. The UN Principles Relevant to the Use of Nuclear Power Sources in Outer Space apply to nuclear power sources in outer space devoted to the generation of electric power on board space objects for non-propulsive purposes, and do not regulate the use of nuclear energy as a means of propulsion. However, nuclear propulsion by means of detonating atomic bombs (ORION) is, in principle, banned under the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water. The legality of use of nuclear propulsion will be analysed from different approaches - historical (i.e. the lawfulness of these projects at the time of their proposal, at the present time, and in the future - in the light of the mutability and evolution of international law), spatial (i.e. the legal regime governing peaceful nuclear explosions in different spatial zones - Earth atmosphere, Earth orbit, Solar System, and interstellar space), and technical (i.e, the legal regime applicable to different nuclear propulsion techniques, and to the various negative effects - e.g. damage to other space systems as an effect of the electromagnetic pulse, etc). The paper will analyse the positive law, and will also come with suggestions "de lege ferenda".

Magnetic levitation and MHD propulsion

Science.gov (United States)

Tixador, P.

1994-04-01

Magnetic levitation and MHD propulsion are now attracting attention in several countries. Different superconducting MagLev and MHD systems will be described concentrating on, above all, the electromagnetic aspect. Some programmes occurring throughout the world will be described. Magnetic levitated trains could be the new high speed transportation system for the 21st century. Intensive studies involving MagLev trains using superconductivity have been carried out in Japan since 1970. The construction of a 43 km long track is to be the next step. In 1991 a six year programme was launched in the United States to evaluate the performances of MagLev systems for transportation. The MHD (MagnetoHydroDynamic) offers some interesting advantages (efficiency, stealth characteristics, ...) for naval propulsion and increasing attention is being paid towards it nowadays. Japan is also up at the top with the tests of Yamato I, a 260 ton MHD propulsed ship. Depuis quelques années nous assistons à un redémarrage de programmes concernant la lévitation et la propulsion supraconductrices. Différents systèmes supraconducteurs de lévitation et de propulsion seront décrits en examinant plus particulièrement l'aspect électromagnétique. Quelques programmes à travers le monde seront abordés. Les trains à sustentation magnétique pourraient constituer un nouveau mode de transport terrestre à vitesse élevée (500 km/h) pour le 21^e siècle. Les japonais n'ont cessé de s'intéresser à ce système avec bobine supraconductrice. Ils envisagent un stade préindustriel avec la construction d'une ligne de 43 km. En 1991 un programme américain pour une durée de six ans a été lancé pour évaluer les performances des systèmes à lévitation pour le transport aux Etats Unis. La MHD (Magnéto- Hydro-Dynamique) présente des avantages intéressants pour la propulsion navale et un regain d'intérêt apparaît à l'heure actuelle. Le japon se situe là encore à la pointe des d

Dynamic simulator for PEFC propulsion plant

Energy Technology Data Exchange (ETDEWEB)

Hiraide, Masataka; Kaneda, Eiichi; Sato, Takao [Mitsui Engineering & Shipbuilding Co., Ltd., Tokyo (Japan)] [and others

1996-12-31

This report covers part of a joint study on a PEFC propulsion system for surface ships, summarized in a presentation to this Seminar, entitled {open_quote}Study on a Polymer Electrolyte Fuel Cell (PEFC) Propulsion System for Surface Ships{close_quotes}, and which envisages application to a 1,500 DWT cargo vessel. The work presented here focuses on a simulation study on PEFC propulsion plant performance, and particularly on the system response to changes in load. Using a dynamic simulator composed of system components including fuel cell, various simulations were executed, to examine the performance of the system as a whole and of the individual system components under quick and large load changes such as occasioned by maneuvering operations and by racing when the propeller emerges above water in heavy sea.

Crime Scenes as Augmented Reality

DEFF Research Database (Denmark)

Sandvik, Kjetil

2010-01-01

Using the concept of augmented reality, this article will investigate how places in various ways have become augmented by means of different mediatization strategies. Augmentation of reality implies an enhancement of the places' emotional character: a certain mood, atmosphere or narrative surplus......, physical damage: they are all readable and interpretable signs. As augmented reality the crime scene carries a narrative which at first is hidden and must be revealed. Due to the process of investigation and the detective's ability to reason and deduce, the crime scene as place is reconstructed as virtual...

Development priorities for in-space propulsion technologies

Science.gov (United States)

Johnson, Les; Meyer, Michael; Palaszewski, Bryan; Coote, David; Goebel, Dan; White, Harold

2013-02-01

During the summer of 2010, NASA's Office of Chief Technologist assembled 15 civil service teams to support the creation of a NASA integrated technology roadmap. The Aero-Space Technology Area Roadmap is an integrated set of technology area roadmaps recommending the overall technology investment strategy and prioritization for NASA's technology programs. The integrated set of roadmaps will provide technology paths needed to meet NASA's strategic goals. The roadmaps have been reviewed by senior NASA management and the National Research Council. With the exception of electric propulsion systems used for commercial communications satellite station-keeping and a handful of deep space science missions, almost all of the rocket engines in use today are chemical rockets; that is, they obtain the energy needed to generate thrust by combining reactive chemicals to create a hot gas that is expanded to produce thrust. A significant limitation of chemical propulsion is that it has a relatively low specific impulse. Numerous concepts for advanced propulsion technologies with significantly higher values of specific impulse have been developed over the past 50 years. Advanced in-space propulsion technologies will enable much more effective exploration of our solar system, near and far, and will permit mission designers to plan missions to "fly anytime, anywhere, and complete a host of science objectives at the destinations" with greater reliability and safety. With a wide range of possible missions and candidate propulsion technologies with very diverse characteristics, the question of which technologies are 'best' for future missions is a difficult one. A portfolio of technologies to allow optimum propulsion solutions for a diverse set of missions and destinations are described in the roadmap and herein.

Performance Criteria of Nuclear Space Propulsion Systems

Science.gov (United States)

Shepherd, L. R.

Future exploration of the solar system on a major scale will require propulsion systems capable of performance far greater than is achievable with the present generation of rocket engines using chemical propellants. Viable missions going deeper into interstellar space will be even more demanding. Propulsion systems based on nuclear energy sources, fission or (eventually) fusion offer the best prospect for meeting the requirements. The most obvious gain coming from the application of nuclear reactions is the possibility, at least in principle, of obtaining specific impulses a thousandfold greater than can be achieved in chemically energised rockets. However, practical considerations preclude the possibility of exploiting the full potential of nuclear energy sources in any engines conceivable in terms of presently known technology. Achievable propulsive power is a particularly limiting factor, since this determines the acceleration that may be obtained. Conventional chemical rocket engines have specific propulsive powers (power per unit engine mass) in the order of gigawatts per tonne. One cannot envisage the possibility of approaching such a level of performance by orders of magnitude in presently conceivable nuclear propulsive systems. The time taken, under power, to reach a given terminal velocity is proportional to the square of the engine's exhaust velocity and the inverse of its specific power. An assessment of various nuclear propulsion concepts suggests that, even with the most optimistic assumptions, it could take many hundreds of years to attain the velocities necessary to reach the nearest stars. Exploration within a range of the order of a thousand AU, however, would appear to offer viable prospects, even with the low levels of specific power of presently conceivable nuclear engines.

Prospective application of laser plasma propulsion in rocket technology

International Nuclear Information System (INIS)

Lu Xin; Zhang Jie; Li Yingjun

2002-01-01

Interest in laser plasma propulsion is growing intensively. The interaction of high intensity short laser pulses with materials can produce plasma expansion with a velocity of hundreds of km/s. The specific impulse of ablative laser propulsion can be many tens of times greater than that of chemical rockets. The development and potential application of laser plasma propulsion are discussed

Misconceptions of Electric Propulsion Aircraft and Their Emergent Aviation Markets

Science.gov (United States)

Moore, Mark D.; Fredericks, Bill

2014-01-01

Over the past several years there have been aircraft conceptual design and system studies that have reached conflicting conclusions relating to the feasibility of full and hybrid electric aircraft. Some studies and propulsion discipline experts have claimed that battery technologies will need to improve by 10 to 20 times before electric aircraft can effectively compete with reciprocating or turbine engines. However, such studies have approached comparative assessments without understanding the compelling differences that electric propulsion offers, how these technologies will fundamentally alter the way propulsion integration is approached, or how these new technologies can not only compete but far exceed existing propulsion solutions in many ways at battery specific energy densities of only 400 watt hours per kilogram. Electric propulsion characteristics offer the opportunity to achieve 4 to 8 time improvements in energy costs with dramatically lower total operating costs, while dramatically improving efficiency, community noise, propulsion system reliability and safety through redundancy, as well as life cycle Green House Gas emissions. Integration of electric propulsion will involve far greater degrees of distribution than existing propulsion solutions due to their compact and scale-free nature to achieve multi-disciplinary coupling and synergistic integration with the aerodynamics, highlift system, acoustics, vehicle control, balance, and aeroelasticity. Appropriate metrics of comparison and differences in analysis/design tools are discussed while comparing electric propulsion to other disruptive technologies. For several initial applications, battery energy density is already sufficient for competitive products, and for many additional markets energy densities will likely be adequate within the next 7 years for vibrant introduction. Market evolution and early adopter markets are discussed, along with the investment areas that will fill technology gaps and

A review of underwater bio-mimetic propulsion: cruise and fast-start

Science.gov (United States)

Chao, Li-Ming; Cao, Yong-Hui; Pan, Guang

2017-08-01

This paper reviews recent developments in the understanding of underwater bio-mimetic propulsion. Two impressive models of underwater propulsion are considered: cruise and fast-start. First, we introduce the progression of bio-mimetic propulsion, especially underwater propulsion, where some primary conceptions are touched upon. Second, the understanding of flapping foils, considered as one of the most efficient cruise styles of aquatic animals, is introduced, where the effect of kinematics and the shape and flexibility of foils on generating thrust are elucidated respectively. Fast-start propulsion is always exhibited when predator behaviour occurs, and we provide an explicit introduction of corresponding zoological experiments and numerical simulations. We also provide some predictions about underwater bio-mimetic propulsion.

A review of underwater bio-mimetic propulsion: cruise and fast-start

Energy Technology Data Exchange (ETDEWEB)

Chao, Li-Ming; Cao, Yong-Hui; Pan, Guang, E-mail: PanGuang_010@163.com [School of Marine Science and Technology, Northwestern Polytechnical University, Xian 710072 (China)

2017-08-15

This paper reviews recent developments in the understanding of underwater bio-mimetic propulsion. Two impressive models of underwater propulsion are considered: cruise and fast-start. First, we introduce the progression of bio-mimetic propulsion, especially underwater propulsion, where some primary conceptions are touched upon. Second, the understanding of flapping foils, considered as one of the most efficient cruise styles of aquatic animals, is introduced, where the effect of kinematics and the shape and flexibility of foils on generating thrust are elucidated respectively. Fast-start propulsion is always exhibited when predator behaviour occurs, and we provide an explicit introduction of corresponding zoological experiments and numerical simulations. We also provide some predictions about underwater bio-mimetic propulsion. (review)

Tools for advanced simulations to nuclear propulsion systems in rockets

International Nuclear Information System (INIS)

Torres Sepulveda, A.; Perez Vara, R.

2004-01-01

While chemical propulsion rockets have dominated space exploration, other forms of rocket propulsion based on nuclear power, electrostatic and magnetic drive, and other principles besides chemical reactions, have been considered from the earliest days of the field. The goal of most of these advanced rocket propulsion schemes is improved efficiency through higher exhaust velocities, in order to reduce the amount of fuel the rocket vehicle needs to carry, though generally at the expense of high thrust. Nuclear propulsion seems to be the most promising short term technology to plan realistic interplanetary missions. The development of a nuclear electric propulsion spacecraft shall require the development of models to analyse the mission and to understand the interaction between the related subsystems (nuclear reactor, electrical converter, power management and distribution, and electric propulsion) during the different phases of the mission. This paper explores the modelling of a nuclear electric propulsion (NEP) spacecraft type using EcosimPro simulation software. This software is a multi-disciplinary simulation tool with a powerful object-oriented simulation language and state-of-the-art solvers. EcosimPro is the recommended ESA simulation tool for environmental Control and Life Support Systems (ECLSS) and has been used successfully within the framework of the European activities of the International Space Station programme. Furthermore, propulsion libraries for chemical and electrical propulsion are currently being developed under ESA contracts to set this tool as standard usage in the propulsion community. At present, there is not any workable NEP spacecraft, but a standardized-modular, multi-purpose interplanetary spacecraft for post-2000 missions, called ISC-2000, has been proposed in reference. The simulation model presented on this paper is based on the preliminary designs for this spacecraft. (Author)

Enhancement of ATRA-induced differentiation of neuroblastoma cells with LOX/COX inhibitors: an expression profiling study.

Science.gov (United States)

Chlapek, Petr; Redova, Martina; Zitterbart, Karel; Hermanova, Marketa; Sterba, Jaroslav; Veselska, Renata

2010-05-11

We performed expression profiling of two neuroblastoma cell lines, SK-N-BE(2) and SH-SY5Y, after combined treatment with all-trans retinoic acid (ATRA) and inhibitors of lipoxygenases (LOX) and cyclooxygenases (COX). This study is a continuation of our previous work confirming the possibility of enhancing ATRA-induced cell differentiation in these cell lines by the application of LOX/COX inhibitors and brings more detailed information concerning the mechanisms of the enhancement of ATRA-induced differentiation of neuroblastoma cells. Caffeic acid, as an inhibitor of 5-lipoxygenase, and celecoxib, as an inhibitor on cyclooxygenase-2, were used in this study. Expression profiling was performed using Human Cancer Oligo GEArray membranes that cover 440 cancer-related genes. Cluster analyses of the changes in gene expression showed the concentration-dependent increase in genes known to be involved in the process of retinoid-induced neuronal differentiation, especially in cytoskeleton remodeling. These changes were detected in both cell lines, and they were independent of the type of specific inhibitors, suggesting a common mechanism of ATRA-induced differentiation enhancement. Furthermore, we also found overexpression of some genes in the same cell line (SK-N-BE(2) or SH-SY5Y) after combined treatment with both ATRA and CA, or ATRA and CX. Finally, we also detected that gene expression was changed after treatment with the same inhibitor (CA or CX) in combination with ATRA in both cell lines. Obtained results confirmed our initial hypothesis of the common mechanism of enhancement in ATRA-induced cell differentiation via inhibition of arachidonic acid metabolic pathway.

Is effective force application in handrim wheelchair propulsion also efficient?

Science.gov (United States)

Bregman, D J J; van Drongelen, S; Veeger, H E J

2009-01-01

Efficiency in manual wheelchair propulsion is low, as is the fraction of the propulsion force that is attributed to the moment of propulsion of the wheelchair. In this study we tested the hypothesis that a tangential propulsion force direction leads to an increase in physiological cost, due to (1) the sub-optimal use of elbow flexors and extensors, and/or (2) the necessity of preventing of glenohumeral subluxation. Five able-bodied and 11 individuals with a spinal cord injury propelled a wheelchair while kinematics and kinetics were collected. The results were used to perform inverse dynamical simulations with input of (1) the experimentally obtained propulsion force, and (2) only the tangential component of that force. In the tangential force condition the physiological cost was over 30% higher, while the tangential propulsion force was only 75% of the total experimental force. According to model estimations, the tangential force condition led to more co-contraction around the elbow, and a higher power production around the shoulder joint. The tangential propulsion force led to a significant, but small 4% increase in necessity for the model to compensate for glenohumeral subluxation, which indicates that this is not a likely cause of the decrease in efficiency. The present findings support the hypothesis that the observed force direction in wheelchair propulsion is a compromise between efficiency and the constraints imposed by the wheelchair-user system. This implies that training should not be aimed at optimization of the propulsion force, because this may be less efficient and more straining for the musculoskeletal system.

The NASA In-Space Propulsion Technology Project, Products, and Mission Applicability

Science.gov (United States)

Anderson, David J.; Pencil, Eric; Liou, Larry; Dankanich, John; Munk, Michelle M.; Kremic, Tibor

2009-01-01

The In-Space Propulsion Technology (ISPT) Project, funded by NASA s Science Mission Directorate (SMD), is continuing to invest in propulsion technologies that will enable or enhance NASA robotic science missions. This overview provides development status, near-term mission benefits, applicability, and availability of in-space propulsion technologies in the areas of aerocapture, electric propulsion, advanced chemical thrusters, and systems analysis tools. Aerocapture investments improved: guidance, navigation, and control models of blunt-body rigid aeroshells; atmospheric models for Earth, Titan, Mars, and Venus; and models for aerothermal effects. Investments in electric propulsion technologies focused on completing NASA s Evolutionary Xenon Thruster (NEXT) ion propulsion system, a 0.6 to 7 kW throttle-able gridded ion system. The project is also concluding its High Voltage Hall Accelerator (HiVHAC) mid-term product specifically designed for a low-cost electric propulsion option. The primary chemical propulsion investment is on the high-temperature Advanced Material Bipropellant Rocket (AMBR) engine providing higher performance for lower cost. The project is also delivering products to assist technology infusion and quantify mission applicability and benefits through mission analysis and tools. In-space propulsion technologies are applicable, and potentially enabling for flagship destinations currently under evaluation, as well as having broad applicability to future Discovery and New Frontiers mission solicitations.

Is cardiovascular disease in patients with diabetes associated with serum levels of MMP-2, LOX, and the elastin degradation products ELM and ELM-2?

Science.gov (United States)

Preil, Simone Andrea Rørdam; Thorsen, Anne-Sofie Faarvang; Christiansen, Anne Lindegaard; Poulsen, Mikael Kjær; Karsdal, Morten Asser; Leeming, Diana Julie; Rasmussen, Lars Melholt

2017-11-01

Diabetes mellitus type 2 (T2DM) is a significant risk factor for the development of cardiovascular diseases (CVDs). In a previous microarray study of internal mammary arteries from patients with and without T2DM, we observed several elastin-related genes with altered mRNA-expression in diabetic patients, namely matrix metalloproteinase 2 (MMP-2), lysyl oxidase (LOX) and elastin itself. In this study we investigate whether the serum concentrations of elastin-related proteins correlate to signs of CVD in patients with T2DM. Blood samples from 302 type 2 diabetic patients were analysed for MMP-2, LOX, and the elastin degradation products ELM and ELM2. The results were investigated for correlations to signs of CVD in different vascular territories, as determined by myocardial perfusion scintigraphy, carotid artery thickness and ankle-brachial blood pressure index. T2DM patients with peripheral arterial disease (low ankle-brachial index) (PAD) display higher levels of MMP-2 and ELM compared to patients without PAD. However, none of the proteins or degradation products correlated with myocardial ischemia or a combined measure of CVD-signs, including myocardial ischemia, increased carotid thickness and decreased ankle-brachial blood pressure. Our results suggest that the diabetic environment affects the circulating amounts of MMP-2 and ELM in patients with PAD. However, the same connection could not be seen in diabetic patients with CVD broadly identified in three vascular territories. LOX and ELM-2 did not correlate to any type of CVD. Overall, serum levels of elastin-related molecules are only remotely related to CVD in type 2 diabetes.

LO2/LH2 propulsion for outer planet orbiter spacecraft

Science.gov (United States)

Garrison, P. W.; Sigurdson, K. B.

1983-01-01

Galileo class orbiter missions (750-1500 kg) to the outer planets require a large postinjection delta-V for improved propulsion performance. The present investigation shows that a pump-fed low thrust LO2/LH2 propulsion system can provide a significantly larger net on-orbit mass for a given delta-V than a state-of-the-art earth storable, N2O4/monomethylhydrazine pressure-fed propulsion system. A description is given of a conceptual design for a LO2/LH2 pump-fed propulsion system developed for a Galileo class mission to the outer planets. Attention is given to spacecraft configuration, details regarding the propulsion system, the thermal control of the cryogenic propellants, and aspects of mission performance.

Initial Skill Acquisition of Handrim Wheelchair Propulsion: A New Perspective.

Science.gov (United States)

Vegter, Riemer J K; de Groot, Sonja; Lamoth, Claudine J; Veeger, Dirkjan Hej; van der Woude, Lucas H V

2014-01-01

To gain insight into cyclic motor learning processes, hand rim wheelchair propulsion is a suitable cyclic task, to be learned during early rehabilitation and novel to almost every individual. To propel in an energy efficient manner, wheelchair users must learn to control bimanually applied forces onto the rims, preserving both speed and direction of locomotion. The purpose of this study was to evaluate mechanical efficiency and propulsion technique during the initial stage of motor learning. Therefore, 70 naive able-bodied men received 12-min uninstructed wheelchair practice, consisting of three 4-min blocks separated by 2 min rest. Practice was performed on a motor-driven treadmill at a fixed belt speed and constant power output relative to body mass. Energy consumption and the kinetics of propulsion technique were continuously measured. Participants significantly increased their mechanical efficiency and changed their propulsion technique from a high frequency mode with a lot of negative work to a longer-slower movement pattern with less power losses. Furthermore a multi-level model showed propulsion technique to relate to mechanical efficiency. Finally improvers and non-improvers were identified. The non-improving group was already more efficient and had a better propulsion technique in the first block of practice (i.e., the fourth minute). These findings link propulsion technique to mechanical efficiency, support the importance of a correct propulsion technique for wheelchair users and show motor learning differences.

Regional gene expression of LOX-1, VCAM-1, and ICAM-1 in aorta of HIV-1 transgenic rats.

Directory of Open Access Journals (Sweden)

Anne Mette Fisker Hag

Full Text Available BACKGROUND: Increased prevalence of atherosclerotic cardiovascular disease in HIV-infected patients has been observed. The cause of this accelerated atherosclerosis is a matter of controversy. As clinical studies are complicated by a multiplicity of risk-factors and a low incidence of hard endpoints, studies in animal models could be attractive alternatives. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated gene expression of lectin-like oxidized-low-density-lipoprotein receptor-1 (LOX-1, vascular cell adhesion molecule-1 (VCAM-1, and intercellular adhesion molecule-1 (ICAM-1 in HIV-1 transgenic (HIV-1Tg rats; these genes are all thought to play important roles in early atherogenesis. Furthermore, the plasma level of sICAM-1 was measured. We found that gene expressions of LOX-1 and VCAM-1 were higher in the aortic arch of HIV-1Tg rats compared to controls. Also, the level of sICAM-1 was elevated in the HIV-1Tg rats compared to controls, but the ICAM-1 gene expression profile did not show any differences between the groups. CONCLUSIONS/SIGNIFICANCE: HIV-1Tg rats have gene expression patterns indicating endothelial dysfunction and accelerated atherosclerosis in aorta, suggesting that HIV-infection per se may cause atherosclerosis. This transgenic rat model may be a very promising model for further studies of the pathophysiology behind HIV-associated cardiovascular disease.

Swimming mechanics and propulsive efficiency in the chambered nautilus

Science.gov (United States)

Neil, Thomas R.; Askew, Graham N.

2018-02-01

The chambered nautilus (Nautilus pompilius) encounters severe environmental hypoxia during diurnal vertical movements in the ocean. The metabolic cost of locomotion (Cmet) and swimming performance depend on how efficiently momentum is imparted to the water and how long on-board oxygen stores last. While propulsive efficiency is generally thought to be relatively low in jet propelled animals, the low Cmet in Nautilus indicates that this is not the case. We measured the wake structure in Nautilus during jet propulsion swimming, to determine their propulsive efficiency. Animals swam with either an anterior-first or posterior-first orientation. With increasing swimming speed, whole cycle propulsive efficiency increased during posterior-first swimming but decreased during anterior-first swimming, reaching a maximum of 0.76. The highest propulsive efficiencies were achieved by using an asymmetrical contractile cycle in which the fluid ejection phase was relatively longer than the refilling phase, reducing the volume flow rate of the ejected fluid. Our results demonstrate that a relatively high whole cycle propulsive efficiency underlies the low Cmet in Nautilus, representing a strategy to reduce the metabolic demands in an animal that spends a significant part of its daily life in a hypoxic environment.

Hybrid rocket propulsion systems for outer planet exploration missions

Science.gov (United States)

Jens, Elizabeth T.; Cantwell, Brian J.; Hubbard, G. Scott

2016-11-01

Outer planet exploration missions require significant propulsive capability, particularly to achieve orbit insertion. Missions to explore the moons of outer planets place even more demanding requirements on propulsion systems, since they involve multiple large ΔV maneuvers. Hybrid rockets present a favorable alternative to conventional propulsion systems for many of these missions. They typically enjoy higher specific impulse than solids, can be throttled, stopped/restarted, and have more flexibility in their packaging configuration. Hybrids are more compact and easier to throttle than liquids and have similar performance levels. In order to investigate the suitability of these propulsion systems for exploration missions, this paper presents novel hybrid motor designs for two interplanetary missions. Hybrid propulsion systems for missions to Europa and Uranus are presented and compared to conventional in-space propulsion systems. The hybrid motor design for each of these missions is optimized across a range of parameters, including propellant selection, O/F ratio, nozzle area ratio, and chamber pressure. Details of the design process are described in order to provide guidance for researchers wishing to evaluate hybrid rocket motor designs for other missions and applications.

MicroRNA-98 rescues proliferation and alleviates ox-LDL-induced apoptosis in HUVECs by targeting LOX-1

Science.gov (United States)

Chen, Zhibo; Wang, Mian; He, Qiong; Li, Zilun; Zhao, Yang; Wang, Wenjian; Ma, Jieyi; Li, Yongxin; Chang, Guangqi

2017-01-01

Oxidized low-density lipoprotein (ox-LDL) is a major and critical mediator of atherosclerosis, and the underlying mechanism is thought to involve the ox-LDL-induced dysfunction of endothelial cells (ECs). MicroRNAs (miRNAs), which are a group of small non-coding RNA molecules that post-transcriptionally regulate the expression of target genes, have been associated with diverse cellular functions and the pathogenesis of various diseases, including atherosclerosis. miRNA-98 (miR-98) has been demonstrated to be involved in the regulation of cellular apoptosis; however, the role of miR-98 in ox-LDL-induced dysfunction of ECs and atherosclerosis has yet to be elucidated. Therefore, the present study aimed to investigate the role of miR-98 in ox-LDL-induced dysfunction of ECs and the underlying mechanism. It was demonstrated that miR-98 expression was markedly downregulated in ox-LDL-treated human umbilical vein ECs (HUVECs) and that miR-98 promoted the proliferation and alleviated apoptosis of HUVECs exposed to ox-LDL. In addition, the results demonstrated that lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) was a direct target of miR-98 in HUVECs, as indicated by a luciferase assay. The results of the present study suggested that miR-98 may inhibit the uptake of toxic ox-LDL, maintain HUVEC proliferation and protect HUVECs against apoptosis via the suppression of LOX-1. PMID:28565756

Volume Dynamics Propulsion System Modeling for Supersonics Vehicle Research

Science.gov (United States)

Kopasakis, George; Connolly, Joseph W.; Paxson, Daniel E.; Ma, Peter

2010-01-01

Under the NASA Fundamental Aeronautics Program the Supersonics Project is working to overcome the obstacles to supersonic commercial flight. The proposed vehicles are long slim body aircraft with pronounced aero-servo-elastic modes. These modes can potentially couple with propulsion system dynamics; leading to performance challenges such as aircraft ride quality and stability. Other disturbances upstream of the engine generated from atmospheric wind gusts, angle of attack, and yaw can have similar effects. In addition, for optimal propulsion system performance, normal inlet-engine operations are required to be closer to compressor stall and inlet unstart. To study these phenomena an integrated model is needed that includes both airframe structural dynamics as well as the propulsion system dynamics. This paper covers the propulsion system component volume dynamics modeling of a turbojet engine that will be used for an integrated vehicle Aero-Propulso-Servo-Elastic model and for propulsion efficiency studies.

Chemical rocket propulsion a comprehensive survey of energetic materials

CERN Document Server

Shimada, Toru; Sinditskii, Valery; Calabro, Max

2017-01-01

Developed and expanded from the work presented at the New Energetic Materials and Propulsion Techniques for Space Exploration workshop in June 2014, this book contains new scientific results, up-to-date reviews, and inspiring perspectives in a number of areas related to the energetic aspects of chemical rocket propulsion. This collection covers the entire life of energetic materials from their conceptual formulation to practical manufacturing; it includes coverage of theoretical and experimental ballistics, performance properties, as well as laboratory-scale and full system-scale, handling, hazards, environment, ageing, and disposal. Chemical Rocket Propulsion is a unique work, where a selection of accomplished experts from the pioneering era of space propulsion and current technologists from the most advanced international laboratories discuss the future of chemical rocket propulsion for access to, and exploration of, space. It will be of interest to both postgraduate and final-year undergraduate students in...

Integrated Propulsion Data System Public Web Site

Science.gov (United States)

Hamilton, Kimberly

2001-01-01

The Integrated Propulsion Data System's (IPDS) focus is to provide technologically-advanced philosophies of doing business at SSC that will enhance the existing operations, engineering and management strategies and provide insight and metrics to assess their daily impacts, especially as related to the Propulsion Test Directorate testing scenarios for the 21st Century.

Configurations of hybrid-electric cars propulsion systems

OpenAIRE

Cundev, Dobri; Sarac, Vasilija; Stefanov, Goce

2011-01-01

Over the last few years, hybrid electric cars have taken significant role in automotive market. There are successful technological solutions of hybrid-electric propulsion systems implemented in commercial passenger cars. Every automobile manufacturer of hybrid vehicles has unique hybrid propulsion system. In this paper, all implemented systems are described, analyzed and compared.

Fusion Reactions and Matter-Antimatter Annihilation for Space Propulsion

Science.gov (United States)

2005-07-13

FUSION REACTIONS AND MATTER- ANTIMATTER ANNIHILATION FOR SPACE PROPULSION Claude DEUTSCH LPGP (UMR-CNRS 8578), Bât. 210, UPS, 91405 Orsay...REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE šFusion Reactions And Matter- Antimatter Annihilation For Space Propulsion 5a...which is possible with successful MCF or ICF. Appropriate vessel designs will be presented for fusion as well as for antimatter propulsion. In

Space Nuclear Thermal Propulsion Test Facilities Subpanel. Final report

International Nuclear Information System (INIS)

Allen, G.C.; Warren, J.W.; Martinell, J.; Clark, J.S.; Perkins, D.

1993-04-01

On 20 Jul. 1989, in commemoration of the 20th anniversary of the Apollo 11 lunar landing, President George Bush proclaimed his vision for manned space exploration. He stated, 'First for the coming decade, for the 1990's, Space Station Freedom, the next critical step in our space endeavors. And next, for the new century, back to the Moon. Back to the future. And this time, back to stay. And then, a journey into tomorrow, a journey to another planet, a manned mission to Mars.' On 2 Nov. 1989, the President approved a national space policy reaffirming the long range goal of the civil space program: to 'expand human presence and activity beyond Earth orbit into the solar system.' And on 11 May 1990, he specified the goal of landing Astronauts on Mars by 2019, the 50th anniversary of man's first steps on the Moon. To safely and ever permanently venture beyond near Earth environment as charged by the President, mankind must bring to bear extensive new technologies. These include heavy lift launch capability from Earth to low-Earth orbit, automated space rendezvous and docking of large masses, zero gravity countermeasures, and closed loop life support systems. One technology enhancing, and perhaps enabling, the piloted Mars missions is nuclear propulsion, with great benefits over chemical propulsion. Asserting the potential benefits of nuclear propulsion, NASA has sponsored workshops in Nuclear Electric Propulsion and Nuclear Thermal Propulsion and has initiated a tri-agency planning process to ensure that appropriate resources are engaged to meet this exciting technical challenge. At the core of this planning process, NASA, DOE, and DOD established six Nuclear Propulsion Technical Panels in 1991 to provide groundwork for a possible tri-agency Nuclear Propulsion Program and to address the President's vision by advocating an aggressive program in nuclear propulsion. To this end the Nuclear Electric Propulsion Technology Panel has focused it energies

Mechanical efficiency of two commercial lever-propulsion mechanisms for manual wheelchair locomotion.

Science.gov (United States)

Lui, Jordon; MacGillivray, Megan K; Sheel, A William; Jeyasurya, Jeswin; Sadeghi, Mahsa; Sawatzky, Bonita Jean

2013-01-01

The purpose of this study was to (1) evaluate the mechanical efficiency (ME) of two commercially available lever-propulsion mechanisms for wheelchairs and (2) compare the ME of lever propulsion with hand rim propulsion within the same wheelchair. Of the two mechanisms, one contained a torsion spring while the other used a roller clutch design. We hypothesized that the torsion spring mechanism would increase the ME of propulsion due to a passive recovery stroke enabled by the mechanism. Ten nondisabled male participants with no prior manual wheeling experience performed submaximal exercise tests using both lever-propulsion mechanisms and hand rim propulsion on two different wheelchairs. Cardiopulmonary parameters including oxygen uptake (VO2), heart rate (HR), and energy expenditure (En) were determined. Total external power (Pext) was measured using a drag test protocol. ME was determined by the ratio of Pext to En. Results indicated no significant effect of lever-propulsion mechanism for all physiological measures tested. This suggests that the torsion spring did not result in a physiological benefit compared with the roller clutch mechanism. However, both lever-propulsion mechanisms showed decreased VO2 and HR and increased ME (as a function of slope) compared with hand rim propulsion (p propulsion mechanisms tested are more mechanically efficient than conventional hand rim propulsion, especially when slopes are encountered.

Augmented reality: a review.

Science.gov (United States)

Berryman, Donna R

2012-01-01

Augmented reality is a technology that overlays digital information on objects or places in the real world for the purpose of enhancing the user experience. It is not virtual reality, that is, the technology that creates a totally digital or computer created environment. Augmented reality, with its ability to combine reality and digital information, is being studied and implemented in medicine, marketing, museums, fashion, and numerous other areas. This article presents an overview of augmented reality, discussing what it is, how it works, its current implementations, and its potential impact on libraries.

Reusable Reentry Satellite (RRS): Propulsion system trade study

Science.gov (United States)

1990-01-01

The purpose of the Reusable Reentry Satellite (RRS) Propulsion System Trade Study described in this summary report was to investigate various propulsion options available for incorporation on the RRS and to select the option best suited for RRS application. The design requirements for the RRS propulsion system were driven by the total impulse requirements necessary to operate within the performance envelope specified in the RRS System Requirements Documents. These requirements were incorporated within the Design Reference Missions (DRM's) identified for use in this and other subsystem trade studies. This study investigated the following propulsion systems: solid rocket, monopropellant, bipropellant (monomethyl hydrazine and nitrogen tetroxide or MMH/NTO), dual-mode bipropellant (hydrazine and nitrogen tetroxide or N2H4/NTO), liquid oxygen and liquid hydrogen (LO2/LH2), and an advanced design propulsion system using SDI-developed components. A liquid monopropellant blowdown propulsion system was found to be best suited for meeting the RRS requirements and is recommended as the baseline system. This system was chosen because it is the simplest of all investigated, has the fewest components, and is the most cost effective. The monopropellant system meets all RRS performance requirements and has the capability to provide a very accurate deorbit burn which minimizes reentry dispersions. In addition, no new hardware qualification is required for a monopropellant system. Although the bipropellant systems offered some weight savings capability for missions requiring large deorbit velocities, the advantage of a lower mass system only applies if the total vehicle design can be reduced to allow a cheaper launch vehicle to be used. At the time of this trade study, the overall RRS weight budget and launch vehicle selection were not being driven by the propulsion system selection. Thus, the added cost and complexity of more advanced systems did not warrant application.

Ablative Laser Propulsion: An Update, Part I

International Nuclear Information System (INIS)

Pakhomov, Andrew V.; Cohen, Timothy; Lin Jun; Thompson, M. Shane; Herren, Kenneth A.

2004-01-01

This paper presents an updated review of studies on Ablative Laser Propulsion conducted by the Laser Propulsion Group (LPG) at the University of Alabama in Huntsville. In particular, we describe the newest results of our experimental study of specific impulses and coupling coefficients achieved by double-pulsed ablation of graphite, aluminum, copper and lead targets

Hybrid Propulsion Demonstration Program 250K Hybrid Motor

Science.gov (United States)

Story, George; Zoladz, Tom; Arves, Joe; Kearney, Darren; Abel, Terry; Park, O.

2003-01-01

The Hybrid Propulsion Demonstration Program (HPDP) program was formed to mature hybrid propulsion technology to a readiness level sufficient to enable commercialization for various space launch applications. The goal of the HPDP was to develop and test a 250,000 pound vacuum thrust hybrid booster in order to demonstrate hybrid propulsion technology and enable manufacturing of large hybrid boosters for current and future space launch vehicles. The HPDP has successfully conducted four tests of the 250,000 pound thrust hybrid rocket motor at NASA's Stennis Space Center. This paper documents the test series.

Test facilities for evaluating nuclear thermal propulsion systems

International Nuclear Information System (INIS)

Beck, D.F.; Allen, G.C.; Shipers, L.R.; Dobranich, D.; Ottinger, C.A.; Harmon, C.D.; Fan, W.C.; Todosow, M.

1992-01-01

Interagency panels evaluating nuclear thermal propulsion (NTP) development options have consistently recognized the need for constructing a major new ground test facility to support fuel element and engine testing. This paper summarizes the requirements, configuration, and baseline performance of some of the major subsystems designed to support a proposed ground test complex for evaluating nuclear thermal propulsion fuel elements and engines being developed for the Space Nuclear Thermal Propulsion (SNTP) program. Some preliminary results of evaluating this facility for use in testing other NTP concepts are also summarized

Use of Augmented Reality in Education

OpenAIRE

Jeřábek, Tomáš

2014-01-01

This thesis deals with phenomena of augmented reality in context of didactics. The thesis aims to define augmented reality in conceptual and content area and focuses on augmented reality in the structure of educational tools and identification of its functions and use from the didactical standpoint. The thesis characterizes augmented reality as a specific technological-perceptual concept and establishes a system of perceptual, technological and resulting aspects that reflect important paramet...

Nuclear electric propulsion for planetary science missions: NASA technology program planning

International Nuclear Information System (INIS)

Doherty, M.P.

1993-05-01

This paper presents the status of technology program planning to develop those Nuclear Electric Propulsion technologies needed to meet the advanced propulsion system requirements for planetary science missions in the next century. The technology program planning is based upon technologies with significant development heritage: ion electric propulsion and the SP-100 space nuclear power technologies. Detailed plans are presented for the required ion electric propulsion technology development and demonstration. Closer coordination between space nuclear power and space electric propulsion technology programs is a necessity as technology plans are being further refined in light of NEP concept definition and possible early NEP flight activities

Research Activities on Special Propulsion in BUAA

International Nuclear Information System (INIS)

Tang Haibin; Wang Haixing; Liu Chang; Xiang Min; Yao Jie; Liu Yu

2007-01-01

An overview is presented of special propulsion research carried out in Beijing University of Aeronautics and Astronautics of China. The research activities are supported by NSFC (National Natural Science Foundation of China), other governmental agencies and industrial partners, which include experimental, analytical and numerical work related to arcjet thrusters, ion thrusters, plasma sail and other new concept propulsions

The Potential for Ambient Plasma Wave Propulsion

Science.gov (United States)

Gilland, James H.; Williams, George J.

2016-01-01

A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at

Aeronautic propulsion systems; Propulseurs aeronautiques

Energy Technology Data Exchange (ETDEWEB)

Lepourry, P; Ciryci, R

1992-12-31

This book is devoted to airplane pilots having a private licence and who would like to take up a professional rank. It comprises 8 chapters dealing with: the different type of propulsion systems, turbojet, turbofan and piston engines; the propeller (characteristics, different types, functioning, protection systems..); the piston engines (4-stroke cycle, power and efficiency, description, characteristics); the gas generator and its limitations (air intake, combustion chamber, turbines, nozzles, fuel systems..); the performances of propulsion systems; the drive, control and instruments; and the use of engines. The last chapter is a self-evaluation questionnaire about the notions developed in the book. (J.S.)

Propulsion of magnetically levitated trains

Energy Technology Data Exchange (ETDEWEB)

Wipf, S L

1976-05-01

A propulsion system for magnetically levitated trains is proposed. A method of periodically energizing magnetic loops on a train moving over a periodically undulating track allows the net repulsive magnetic force to tilt forward or backward for either propulsion or braking. The principle is explained and a specific example discussed. Approximate calculations show feasibility. Problems requiring technical solutions which cannot be considered present state-of-the-art are AC losses at frequencies up to 20 Hz and mechanical fatigue properties at low temperatures. Suitable primary power could be derived from hydrogen-fueled turbines yet to be developed.

Antimatter Propulsion Developed by NASA

Science.gov (United States)

1999-01-01

This Quick Time movie shows possible forms of an antimatter propulsion system being developed by NASA. Antimatter annihilation offers the highest possible physical energy density of any known reaction substance. It is about 10 billion times more powerful than that of chemical energy such as hydrogen and oxygen combustion. Antimatter would be the perfect rocket fuel, but the problem is that the basic component of antimatter, antiprotons, doesn't exist in nature and has to manufactured. The process of antimatter development is ongoing and making some strides, but production of this as a propulsion system is far into the future.

Organotypic culture of normal, dysplastic and squamous cell carcinoma-derived oral cell lines reveals loss of spatial regulation of CD44 and p75 NTR in malignancy.

Science.gov (United States)

Dalley, Andrew J; AbdulMajeed, Ahmad A; Upton, Zee; Farah, Camile S

2013-01-01

Oral squamous cell carcinomas (OSCC) often arise from dysplastic lesions. The role of cancer stem cells in tumour initiation is widely accepted, yet the potential existence of pre-cancerous stem cells in dysplastic tissue has received little attention. Cell lines from oral diseases ranging in severity from dysplasia to malignancy provide opportunity to investigate the involvement of stem cells in malignant progression from dysplasia. Stem cells are functionally defined by their ability to generate hierarchical tissue structures in consortium with spatial regulation. Organotypic cultures readily display tissue hierarchy in vitro; hence, in this study, we compared hierarchical expression of stem cell-associated markers in dermis-based organotypic cultures of oral epithelial cells from normal tissue (OKF6-TERT2), mild dysplasia (DOK), severe dysplasia (POE-9n) and OSCC (PE/CA P J15). Expression of CD44, p75(NTR), CD24 and ALDH was studied in monolayers by flow cytometry and in organotypic cultures by immunohistochemistry. Spatial regulation of CD44 and p75(NTR) was evident for organotypic cultures of normal (OKF6-TERT2) and dysplasia (DOK and POE-9n) but was lacking for OSCC (PE/CA PJ15)-derived cells. Spatial regulation of CD24 was not evident. All monolayer cultures exhibited CD44, p75(NTR), CD24 antigens and ALDH activity (ALDEFLUOR(®) assay), with a trend towards loss of population heterogeneity that mirrored disease severity. In monolayer, increased FOXA1 and decreased FOXA2 expression correlated with disease severity, but OCT3/4, Sox2 and NANOG did not. We conclude that dermis-based organotypic cultures give opportunity to investigate the mechanisms that underlie loss of spatial regulation of stem cell markers seen with OSCC-derived cells. © 2012 John Wiley & Sons A/S.

Bayesian Alternation During Tactile Augmentation

Directory of Open Access Journals (Sweden)

Caspar Mathias Goeke

2016-10-01

Full Text Available A large number of studies suggest that the integration of multisensory signals by humans is well described by Bayesian principles. However, there are very few reports about cue combination between a native and an augmented sense. In particular, we asked the question whether adult participants are able to integrate an augmented sensory cue with existing native sensory information. Hence for the purpose of this study we build a tactile augmentation device. Consequently, we compared different hypotheses of how untrained adult participants combine information from a native and an augmented sense. In a two-interval forced choice (2 IFC task, while subjects were blindfolded and seated on a rotating platform, our sensory augmentation device translated information on whole body yaw rotation to tactile stimulation. Three conditions were realized: tactile stimulation only (augmented condition, rotation only (native condition, and both augmented and native information (bimodal condition. Participants had to choose one out of two consecutive rotations with higher angular rotation. For the analysis, we fitted the participants’ responses with a probit model and calculated the just notable difference (JND. Then we compared several models for predicting bimodal from unimodal responses. An objective Bayesian alternation model yielded a better prediction (χred2 = 1.67 than the Bayesian integration model (χred2= 4.34. Slightly higher accuracy showed a non-Bayesian winner takes all model (χred2= 1.64, which either used only native or only augmented values per subject for prediction. However the performance of the Bayesian alternation model could be substantially improved (χred2= 1.09 utilizing subjective weights obtained by a questionnaire. As a result, the subjective Bayesian alternation model predicted bimodal performance most accurately among all tested models. These results suggest that information from augmented and existing sensory modalities in

Augmented Reality

DEFF Research Database (Denmark)

Kjærgaard, Hanne Wacher; Kjeldsen, Lars Peter Bech; Rahn, Annette

2015-01-01

This chapter describes the use of iPad-facilitated application of augmented reality in the teaching of highly complex anatomical and physiological subjects in the training of nurses at undergraduate level. The general aim of the project is to investigate the potentials of this application in terms...... of making the complex content and context of these subjects more approachable to the students through the visualization made possible through the use of this technology. A case study is described in this chapter. Issues and factors required for the sustainable use of the mobile-facilitated application...... of augmented reality are discussed....

Affordances in Mobile Augmented Reality Applications

OpenAIRE

Gjøsæter, Tor

2014-01-01

This paper explores the affordances of augmented reality content in a mobile augmented reality application. A user study was conducted by performing a multi-camera video recording of seven think aloud sessions. The think aloud sessions consisted of individual users performing tasks, exploring and experiencing a mobile augmented reality (MAR) application we developed for the iOS platform named ARad. We discuss the instrumental affordances we observed when users interacted with augmented realit...

Dynamic augmentation restores anterior tibial translation in ACL suture repair: a biomechanical comparison of non-, static and dynamic augmentation techniques.

Science.gov (United States)

Hoogeslag, Roy A G; Brouwer, Reinoud W; Huis In 't Veld, Rianne; Stephen, Joanna M; Amis, Andrew A

2018-02-03

There is a lack of objective evidence investigating how previous non-augmented ACL suture repair techniques and contemporary augmentation techniques in ACL suture repair restrain anterior tibial translation (ATT) across the arc of flexion, and after cyclic loading of the knee. The purpose of this work was to test the null hypotheses that there would be no statistically significant difference in ATT after non-, static- and dynamic-augmented ACL suture repair, and they will not restore ATT to normal values across the arc of flexion of the knee after cyclic loading. Eleven human cadaveric knees were mounted in a test rig, and knee kinematics from 0° to 90° of flexion were recorded by use of an optical tracking system. Measurements were recorded without load and with 89-N tibial anterior force. The knees were tested in the following states: ACL-intact, ACL-deficient, non-augmented suture repair, static tape augmentation and dynamic augmentation after 10 and 300 loading cycles. Only static tape augmentation and dynamic augmentation restored ATT to values similar to the ACL-intact state directly postoperation, and maintained this after cyclic loading. However, contrary to dynamic augmentation, the ATT after static tape augmentation failed to remain statistically less than for the ACL-deficient state after cyclic loading. Moreover, after cyclic loading, ATT was significantly less with dynamic augmentation when compared to static tape augmentation. In contrast to non-augmented ACL suture repair and static tape augmentation, only dynamic augmentation resulted in restoration of ATT values similar to the ACL-intact knee and decreased ATT values when compared to the ACL-deficient knee immediately post-operation and also after cyclic loading, across the arc of flexion, thus allowing the null hypotheses to be rejected. This may assist healing of the ruptured ACL. Therefore, this study would support further clinical evaluation of dynamic augmentation of ACL repair.

Ship propulsion reactors technology

International Nuclear Information System (INIS)

Fribourg, Ch.

2002-01-01

This paper takes the state of the art on ship propulsion reactors technology. The french research programs with the corresponding technological stakes, the reactors specifications and advantages are detailed. (A.L.B.)

Augment-type two stage accelerator

International Nuclear Information System (INIS)

Ogino, Mutsuo; Azuma, Kingo.

1995-01-01

When a flying body accelerated by a gas gun at a first stage enters into an augment rail passing through an introduction tube, an ignition capacitor for initial plasmas is turned ON to apply a voltage between the augment rails. Subsequently, the accelerating gas present behind the flying body is formed into plasmas by a laser, to flow electric current from one of the inner augment rails → plasma armature → the other of the inner augment rails, and additionally accelerate the flying body by Lorentz force formed in this case. Since the plasmas are maintained in a state of higher density than the plasmas obtained by using all of the augment rails, the ignition capacitor for initial plasmas in switched to a power source. As a result, it is possible to flow the maximum current before the plasmas expand, and a large accelerating force and a high magnetic flux density are attained, to improve acceleration performance of the flying body. (N.H.)

Nuclear electric propulsion for planetary science missions: NASA technology program planning

International Nuclear Information System (INIS)

Doherty, M.P.

1993-01-01

This paper presents the status of technology program planning to achieve readiness of Nuclear Electric Propulsion technologies needed to meet the advanced propulsion system requirements for planetary science missions in the next century. The technology program planning is based upon technologies of significant maturity: ion electric propulsion and the SP-100 space nulcear power technologies. Detailed plans are presented herein for the required ion electric propulsion technology development and demonstration. Closer coordination between space nuclear power and space electric propulsion technology programs is a necessity as technology plans are being further refined in light of NEP concept definition and possible early NEP flight activities

2-Dimensional changes of the soft tissue profile of augmented and non-augmented human extraction sockets: a randomized pilot study.

Science.gov (United States)

Flügge, Tabea; Nelson, Katja; Nack, Claudia; Stricker, Andres; Nahles, Susanne

2015-04-01

This study identified the soft tissue changes of the alveolar ridge at different time points within 12 weeks after tooth extraction with and without socket augmentation. In 38 patients with single tooth extractions, 40 sockets were augmented and 39 extraction sockets were not augmented. At 2, 4, 6, 8 and 12 weeks impressions were taken and casts digitized with a laser scanner. The horizontal and vertical changes were compared between augmented and non-augmented sites. A p-value sockets were between 0.4 mm (2 weeks) and 0.8 mm (12 weeks). In non-augmented sockets changes of 0.7 mm (2 weeks) and of 1.0 mm (12 weeks) were demonstrated. The mean values differed significantly between the buccal and oral region (p sockets showed less resorption within 4 weeks after extraction compared to non-augmented sockets. Non-augmented sockets showed a continuous dimensional loss with a great variation over 12 weeks whereas augmented sockets had the highest degree of resorption between 4 and 6 weeks. At 12 weeks a comparable resorption in augmented and non-augmented sockets was observed. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Economics of Advanced In-Space Propulsion

Science.gov (United States)

Bangalore, Manju; Dankanich, John

2016-01-01

The cost of access to space is the single biggest driver is commercial space sector. NASA continues to invest in both launch technology and in-space propulsion. Low-cost launch systems combined with advanced in-space propulsion offer the greatest potential market capture. Launch market capture is critical to national security and has a significant impact on domestic space sector revenue. NASA typically focuses on pushing the limits on performance. However, the commercial market is driven by maximum net revenue (profits). In order to maximum the infusion of NASA investments, the impact on net revenue must be known. As demonstrated by Boeing's dual launch, the Falcon 9 combined with all Electric Propulsion (EP) can dramatically shift the launch market from foreign to domestic providers.

Aircraft Electric Propulsion Systems Applied Research at NASA

Science.gov (United States)

Clarke, Sean

2015-01-01

Researchers at NASA are investigating the potential for electric propulsion systems to revolutionize the design of aircraft from the small-scale general aviation sector to commuter and transport-class vehicles. Electric propulsion provides new degrees of design freedom that may enable opportunities for tightly coupled design and optimization of the propulsion system with the aircraft structure and control systems. This could lead to extraordinary reductions in ownership and operating costs, greenhouse gas emissions, and noise annoyance levels. We are building testbeds, high-fidelity aircraft simulations, and the first highly distributed electric inhabited flight test vehicle to begin to explore these opportunities.

Options for development of space fission propulsion systems

International Nuclear Information System (INIS)

Houts, Mike; Van Dyke, Melissa; Godfroy, Tom; Pedersen, Kevin; Martin, James; Dickens, Ricky; Salvail, Pat; Hrbud, Ivana

2001-01-01

Fission technology can enable rapid, affordable access to any point in the solar system. Potential fission-based transportation options include high specific power continuous impulse propulsion systems and bimodal nuclear thermal rockets. Despite their tremendous potential for enhancing or enabling deep space and planetary missions, to date space fission systems have only been used in Earth orbit. The first step towards utilizing advanced fission propulsion systems is development of a safe, near-term, affordable fission system that can enhance or enable near-term missions of interest. An evolutionary approach for developing space fission propulsion systems is proposed

Cre/loxP-mediated adenovirus type 5 packaging signal excision demonstrates that core element VI is sufficient for virus packaging

International Nuclear Information System (INIS)

Maeda, Yasushi; Kimura, En; Uchida, Yuji; Nishida, Yasuto; Yamashita, Satoshi; Arima, Toshiyuki; Uchino, Makoto

2003-01-01

Previous analyses have demonstrated that packaging of the adenovirus type 5 (Ad5) genome is dependent on at least seven cis-acting elements, called AI to AVII, which are located in the left-end region of the genome. These elements have different packaging efficiencies, and without AI through AV, viral DNA cannot be packaged. Here we report the identification of the cis-acting Ad5 packaging domain in vivo by using the Cre/loxP system. We found that an adenoviral DNA fragment (nt 192 to nt 358), which includes elements AI to AV, is excised by Cre recombinase and packaged into capsids. Furthermore, this mutant adenovirus replicated so efficiently by repetitive propagation that its purification by CsCI equilibrium gradient was possible. This study clarified that the region from nt 358 to nt 454 on the viral genome is sufficient for packaging. Recently, the helper-dependent adenoviral vector (HDAd) construction system has been developed for the purpose of gene therapy. This system uses a helper virus with two parallel loxP sites flanking the packaging signal. This region is eliminated by Cre-mediated excision, which prevents helper virus packaging. Our data provide useful information regarding factors affecting efficient elimination

Focused library design and synthesis of 2-mercapto benzothiazole linked 1,2,4-oxadiazoles as COX-2/5-LOX inhibitors

Science.gov (United States)

Yatam, Satayanarayana; Gundla, Rambabu; Jadav, Surender Singh; Pedavenkatagari, Narayana reddy; Chimakurthy, Jithendra; Rani B, Namratha; Kedam, Thyagaraju

2018-05-01

Mercapto benzothiazole linked 1,2,4-oxadiazole derivatives were designed (4a-u) as new anti-inflammatory agents using bioisosteric approach and docking studies. The docking results clearly indicated that the compounds 4a-u shown good docking interaction towards COX-2 enzyme. In silico drug-like properties were also calculated for compounds (4a-u) and exhibited significant H-bond acceptor ratio. All compounds were synthesized and biologically evaluated using in vitro COX-1, COX-2 and 5-LOX assays. Compound 4k and 4q (IC50 = 6.8 μM and IC50 = 5.0 μM) found to be potent, selective COX-2 inhibitors and display better anti-inflammatory activity than standard Ibuprofen. Compound 4l and 4e found to be potent inhibitors against 5-LOX (IC50 = 5.1 μM and IC50 = 5.5 μM). The in vivo anti-inflammatory activity studies shown that the compounds 4q and 4k effectively reducing the paw edema volume at 3h and 5h than standard drug Ibuprofen. The DPPH radical scavenging activity provided anti-oxidant activity of compound 4e (IC50 = 25.6 μM) than reference standard Ascorbic acid.

Augmented assessment as a means to augmented reality.

Science.gov (United States)

Bergeron, Bryan

2006-01-01

Rigorous scientific assessment of educational technologies typically lags behind the availability of the technologies by years because of the lack of validated instruments and benchmarks. Even when the appropriate assessment instruments are available, they may not be applied because of time and monetary constraints. Work in augmented reality, instrumented mannequins, serious gaming, and similar promising educational technologies that haven't undergone timely, rigorous evaluation, highlights the need for assessment methodologies that address the limitations of traditional approaches. The most promising augmented assessment solutions incorporate elements of rapid prototyping used in the software industry, simulation-based assessment techniques modeled after methods used in bioinformatics, and object-oriented analysis methods borrowed from object oriented programming.

Prediction of applied forces in handrim wheelchair propulsion.

Science.gov (United States)

Lin, Chien-Ju; Lin, Po-Chou; Guo, Lan-Yuen; Su, Fong-Chin

2011-02-03

Researchers of wheelchair propulsion have usually suggested that a wheelchair can be properly designed using anthropometrics to reduce high mechanical load and thus reduce pain and damage to joints. A model based on physiological features and biomechanical principles can be used to determine anthropometric relationships for wheelchair fitting. To improve the understanding of man-machine interaction and the mechanism through which propulsion performance been enhanced, this study develops and validates an energy model for wheelchair propulsion. Kinematic data obtained from ten able-bodied and ten wheelchair-dependent users during level propulsion at an average velocity of 1m/s were used as the input of a planar model with the criteria of increasing efficiency and reducing joint load. Results demonstrate that for both experienced and inexperienced users, predicted handrim contact forces agree with experimental data through an extensive range of the push. Significant deviations that were mostly observed in the early stage of the push phase might result from the lack of consideration of muscle dynamics and wrist joint biomechanics. The proposed model effectively verified the handrim contact force patterns during dynamic propulsion. Users do not aim to generate mechanically most effective forces to avoid high loadings on the joints. Copyright © 2010 Elsevier Ltd. All rights reserved.

Outer Planet Missions with Electric Propulsion Systems—Part I

Directory of Open Access Journals (Sweden)

Carlos Renato Huaura Solórzano

2010-01-01

Full Text Available For interplanetary missions, efficient electric propulsion systems can be used to increase the mass delivered to the destination. Outer planet exploration has experienced new interest with the launch of the Cassini and New Horizons Missions. At the present, new technologies are studied for better use of electric propulsion systems in missions to the outer planets. This paper presents low-thrust trajectories using the method of the transporting trajectory to Uranus, Neptune, and Pluto. They use nuclear and radio isotopic electric propulsion. These direct transfers have continuous electric propulsion of low power along the entire trajectory. The main goal of the paper is to optimize the transfers, that is, to provide maximum mass to be delivered to the outer planets.

Enhancement of ATRA-induced differentiation of neuroblastoma cells with LOX/COX inhibitors: an expression profiling study

Directory of Open Access Journals (Sweden)

Hermanova Marketa

2010-05-01

Full Text Available Abstract Background We performed expression profiling of two neuroblastoma cell lines, SK-N-BE(2 and SH-SY5Y, after combined treatment with all-trans retinoic acid (ATRA and inhibitors of lipoxygenases (LOX and cyclooxygenases (COX. This study is a continuation of our previous work confirming the possibility of enhancing ATRA-induced cell differentiation in these cell lines by the application of LOX/COX inhibitors and brings more detailed information concerning the mechanisms of the enhancement of ATRA-induced differentiation of neuroblastoma cells. Methods Caffeic acid, as an inhibitor of 5-lipoxygenase, and celecoxib, as an inhibitor on cyclooxygenase-2, were used in this study. Expression profiling was performed using Human Cancer Oligo GEArray membranes that cover 440 cancer-related genes. Results Cluster analyses of the changes in gene expression showed the concentration-dependent increase in genes known to be involved in the process of retinoid-induced neuronal differentiation, especially in cytoskeleton remodeling. These changes were detected in both cell lines, and they were independent of the type of specific inhibitors, suggesting a common mechanism of ATRA-induced differentiation enhancement. Furthermore, we also found overexpression of some genes in the same cell line (SK-N-BE(2 or SH-SY5Y after combined treatment with both ATRA and CA, or ATRA and CX. Finally, we also detected that gene expression was changed after treatment with the same inhibitor (CA or CX in combination with ATRA in both cell lines. Conclusions Obtained results confirmed our initial hypothesis of the common mechanism of enhancement in ATRA-induced cell differentiation via inhibition of arachidonic acid metabolic pathway.

An analytical optimization method for electric propulsion orbit transfer vehicles

International Nuclear Information System (INIS)

Oleson, S.R.

1993-01-01

Due to electric propulsion's inherent propellant mass savings over chemical propulsion, electric propulsion orbit transfer vehicles (EPOTVs) are a highly efficient mode of orbit transfer. When selecting an electric propulsion device (ion, MPD, or arcjet) and propellant for a particular mission, it is preferable to use quick, analytical system optimization methods instead of time intensive numerical integration methods. It is also of interest to determine each thruster's optimal operating characteristics for a specific mission. Analytical expressions are derived which determine the optimal specific impulse (Isp) for each type of electric thruster to maximize payload fraction for a desired thrusting time. These expressions take into account the variation of thruster efficiency with specific impulse. Verification of the method is made with representative electric propulsion values on a LEO-to-GEO mission. Application of the method to specific missions is discussed

Cold inducible promoter driven Cre-lox system proved to be highly efficient for marker gene excision in transgenic barley.

Science.gov (United States)

Éva, Csaba; Téglás, Flóra; Zelenyánszki, Helga; Tamás, Cecília; Juhász, Angéla; Mészáros, Klára; Tamás, László

2018-01-10

A Cre-lox based auto-excision strategy has been adapted for barley, capable of cre and selectable marker gene (SMG) removal. The cold inducible wheat promoter called wcs120 was utilised for driving Cre expression. The binary vector was carrying the transgene (uidA) and a so called 'recombination cassette' flanked by the lox sequences. This part included both the recombinase gene and the SMG (bar) under the control of a constitutive promoter. T 0 , T 1 and T 2 transgenic plants were subjected to low temperature (at 4°C, 10°C and 12°C) at different developmental stages to induce recombination. The presence of uidA, cre, and bar genes and recombination footprints were studied by PCR and DNA sequencing, while cre transcription was followed by qRT-PCR. These analyses indicated that, cold treatment of the germinating seeds (4°C for 3days) followed by plant growing at higher temperature (24°C) has been the most efficient (90-100%), and this treatment lead to heritable changes in the genome. Thermal separation of Cre accumulation (at low temperature) from Cre enzyme activity (at higher temperature) could have prevented the premature excision of its own encoding gene, and lead to high expression level thereby increasing recombination frequency. Copyright © 2017 Elsevier B.V. All rights reserved.

FY2016 Propulsion Materials Annual Progress Report

Energy Technology Data Exchange (ETDEWEB)

None, None

2017-05-01

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines and Fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.

Propulsion via flexible flapping in granular media

Science.gov (United States)

Peng, Zhiwei; Ding, Yang; Pietrzyk, Kyle; Elfring, Gwynn; Pak, On Shun

2017-11-01

Biological locomotion in nature is often achieved by the interaction between a flexible body and its surrounding medium. The interaction of a flexible body with granular media is less understood compared with viscous fluids partially due to its complex rheological properties. In this work, we explore the effect of flexibility on granular propulsion by considering a simple mechanical model in which a rigid rod is connected to a torsional spring that is under a displacement actuation using a granular resistive force theory. Through a combined numerical and asymptotic investigation, we characterize the propulsive dynamics of such a flexible flapper in relation to the actuation amplitude and spring stiffness, and we compare these dynamics with those observed in a viscous fluid. In addition, we demonstrate that the maximum possible propulsive force can be obtained in the steady propulsion limit with a finite spring stiffness and large actuation amplitude. These results may apply to the development of synthetic locomotive systems that exploit flexibility to move through complex terrestrial media. Funding for Z.P. and Y.D. was partially provided by NSFC 394 Grant No. 11672029 and NSAF-NSFC Grant No. U1530401.

Nuclear propulsion for the space exploration initiative

International Nuclear Information System (INIS)

Stanley, M.L.

1991-01-01

President Bush's speech of July 20, 1989, outlining a goal to go back to the moon and then Mars initiated the Space Exploration Initiative (SEI). The US Department of Defense (DOD), US Department of Energy (DOE), and NASA have been working together in the planning necessary to initiate a program to develop a nuclear propulsion system. Applications of nuclear technology for in-space transfer of personnel and cargo between Earth orbit and lunar or Martian orbit are being considered as alternatives to chemical propulsion systems. Mission and system concept studies conducted over the past 30 yr have consistently indicated that use of nuclear technology can substantially reduce in-space propellant requirements. A variety of nuclear technology options are currently being studied, including nuclear thermal rockets, nuclear electrical propulsion systems, and hybrid nuclear thermal rockets/nuclear electric propulsion concepts. Concept performance in terms of thrust, weight, power, and efficiency are dependent, and appropriate concept application is mission dependent (i.e., lunar, Mars, cargo, personnel, trajectory, transit time, payload). A comprehensive evaluation of mission application, technology performance capability and maturity, technology development programmatics, and safety characteristics is required to optimize both technology and mission selection to support the Presidential initiative

Challenges of future aircraft propulsion: A review of distributed propulsion technology and its potential application for the all electric commercial aircraft

Science.gov (United States)

Gohardani, Amir S.; Doulgeris, Georgios; Singh, Riti

2011-07-01

This paper highlights the role of distributed propulsion technology for future commercial aircraft. After an initial historical perspective on the conceptual aspects of distributed propulsion technology and a glimpse at numerous aircraft that have taken distributed propulsion technology to flight, the focal point of the review is shifted towards a potential role this technology may entail for future commercial aircraft. Technological limitations and challenges of this specific technology are also considered in combination with an all electric aircraft concept, as means of predicting the challenges associated with the design process of a next generation commercial aircraft.

Augmented Reality Using JavaScript

OpenAIRE

Hailemichael, Aida

2013-01-01

The project goal was to provide a mobile application, for a venue called Kulturhuset Karelia which is located in Tammisaari Finland. In this paper, the concept of Augmented Reality technology is briefly discussed along with the mobile application for the venue. The utilisation of JavaScript for creating Augmented reality content for mobile Augmented reality browser is also demonstrated. The application was created by using Architecht API which is Jacvascript library based on the Wikitude...

The multidisciplinary design optimization of a distributed propulsion blended-wing-body aircraft

Science.gov (United States)

Ko, Yan-Yee Andy

The purpose of this study is to examine the multidisciplinary design optimization (MDO) of a distributed propulsion blended-wing-body (BWB) aircraft. The BWB is a hybrid shape resembling a flying wing, placing the payload in the inboard sections of the wing. The distributed propulsion concept involves replacing a small number of large engines with many smaller engines. The distributed propulsion concept considered here ducts part of the engine exhaust to exit out along the trailing edge of the wing. The distributed propulsion concept affects almost every aspect of the BWB design. Methods to model these effects and integrate them into an MDO framework were developed. The most important effect modeled is the impact on the propulsive efficiency. There has been conjecture that there will be an increase in propulsive efficiency when there is blowing out of the trailing edge of a wing. A mathematical formulation was derived to explain this. The formulation showed that the jet 'fills in' the wake behind the body, improving the overall aerodynamic/propulsion system, resulting in an increased propulsive efficiency. The distributed propulsion concept also replaces the conventional elevons with a vectored thrust system for longitudinal control. An extension of Spence's Jet Flap theory was developed to estimate the effects of this vectored thrust system on the aircraft longitudinal control. It was found to provide a reasonable estimate of the control capability of the aircraft. An MDO framework was developed, integrating all the distributed propulsion effects modeled. Using a gradient based optimization algorithm, the distributed propulsion BWB aircraft was optimized and compared with a similarly optimized conventional BWB design. Both designs are for an 800 passenger, 0.85 cruise Mach number and 7000 nmi mission. The MDO results found that the distributed propulsion BWB aircraft has a 4% takeoff gross weight and a 2% fuel weight. Both designs have similar planform shapes

Augmented Reality for Multi-disciplinary Collaboration

OpenAIRE

Wang, Xiangyu; Rui,

2010-01-01

This chapter presents a framework for multi-disciplinary collaboration. Tangible Augmented Reality has been raised as one of suitable systems for design collaboration. Furthermore, it emphasizes the advantages of Tangible Augmented Reality to illustrate the needs for integrating the Tangible User Interfaces and Augmented Reality Systems.

Turboprop Propulsion Mechanic.

Science.gov (United States)

Chanute AFB Technical Training Center, IL.

This instructional package consists of a plan of instruction, glossary, and student handouts and exercises for use in training Air Force personnel to become turboprop propulsion mechanics. Addressed in the individual lessons of the course are the following: common hand tools, hardware, measuring devices, and safety wiring; aircraft and engine…

NASA's Launch Propulsion Systems Technology Roadmap

Science.gov (United States)

McConnaughey, Paul K.; Femminineo, Mark G.; Koelfgen, Syri J.; Lepsch, Roger A; Ryan, Richard M.; Taylor, Steven A.

2012-01-01

Safe, reliable, and affordable access to low-Earth (LEO) orbit is necessary for all of the United States (US) space endeavors. In 2010, NASA s Office of the Chief Technologist commissioned 14 teams to develop technology roadmaps that could be used to guide the Agency s and US technology investment decisions for the next few decades. The Launch Propulsion Systems Technology Area (LPSTA) team was tasked to address the propulsion technology challenges for access to LEO. The developed LPSTA roadmap addresses technologies that enhance existing solid or liquid propulsion technologies and their related ancillary systems or significantly advance the technology readiness level (TRL) of less mature systems like airbreathing, unconventional, and other launch technologies. In developing this roadmap, the LPSTA team consulted previous NASA, military, and industry studies as well as subject matter experts to develop their assessment of this field, which has fundamental technological and strategic impacts for US space capabilities.

Ultra-high temperature direct propulsion

International Nuclear Information System (INIS)

Araj, K.J.; Slovik, G.; Powell, J.R.; Ludewig, H.

1987-01-01

Potential advantages of ultra-high exhaust temperature (3000 K - 4000 K) direct propulsion nuclear rockets are explored. Modifications to the Particle Bed Reactor (PBR) to achieve these temperatures are described. Benefits of ultra-high temperature propulsion are discussed for two missions - orbit transfer (ΔV = 5546 m/s) and interplanetary exploration (ΔV = 20000 m/s). For such missions ultra-high temperatures appear to be worth the additional complexity. Thrust levels are reduced substantially for a given power level, due to the higher enthalpy caused by partial disassociation of the hydrogen propellant. Though technically challenging, it appears potentially feasible to achieve such ultra high temperatures using the PBR

Hybrid Propulsion Technology for Robotic Science Missions, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — C3 Propulsion's Hybrid Propulsion Technology will be applied to a NASA selected Sample Return Mission. Phase I will demonstrate Proof-of-Principle and Phase II will...

An Intelligent Propulsion Control Architecture to Enable More Autonomous Vehicle Operation

Science.gov (United States)

Litt, Jonathan S.; Sowers, T. Shane; Simon, Donald L.; Owen, A. Karl; Rinehart, Aidan W.; Chicatelli, Amy K.; Acheson, Michael J.; Hueschen, Richard M.; Spiers, Christopher W.

2018-01-01

This paper describes an intelligent propulsion control architecture that coordinates with the flight control to reduce the amount of pilot intervention required to operate the vehicle. Objectives of the architecture include the ability to: automatically recognize the aircraft operating state and flight phase; configure engine control to optimize performance with knowledge of engine condition and capability; enhance aircraft performance by coordinating propulsion control with flight control; and recognize off-nominal propulsion situations and to respond to them autonomously. The hierarchical intelligent propulsion system control can be decomposed into a propulsion system level and an individual engine level. The architecture is designed to be flexible to accommodate evolving requirements, adapt to technology improvements, and maintain safety.

Institute for Computational Mechanics in Propulsion (ICOMP)

Science.gov (United States)

Keith, Theo G., Jr. (Editor); Balog, Karen (Editor); Povinelli, Louis A. (Editor)

2001-01-01

The Institute for Computational Mechanics in Propulsion (ICOMP) was formed to develop techniques to improve problem-solving capabilities in all aspects of computational mechanics related to propulsion. ICOMP is operated by the Ohio Aerospace Institute (OAI) and funded via numerous cooperative agreements by the NASA Glenn Research Center in Cleveland, Ohio. This report describes the activities at ICOMP during 1999, the Institute's fourteenth year of operation.

Individual muscle contributions to push and recovery subtasks during wheelchair propulsion.

Science.gov (United States)