Biosecurity Management of Submarine Niche Areas: the Effect of Water Pressure on Biofouling Survival

DTIC Science & Technology

2014-01-01

UNCLASSIFIED UNCLASSIFIED Biosecurity Management of Submarine Niche Areas: the Effect of Water Pressure on Biofouling Survival Clare...operational impacts and biosecurity risks. Approved for public release RELEASE LIMITATION UNCLASSIFIED...UNCLASSIFIED UNCLASSIFIED Biosecurity Management of Submarine Niche Areas: the Effect of Water Pressure on Biofouling Survival Executive Summary

Device for testing closure disks at high rates of change of pressure

DOEpatents

Merten, C.W. Jr.

1993-11-09

A device is described for testing the burst pressure of closure disks which provides high pressure to both sides of a disk and rapidly releases pressure from one side thereof causing a high rate of change of pressure. A hollow notched plug allows the rapid release of pressure upon rupturing. A means is also disclosed for transmitting a tensile load from a piston to a hollow notched plug and for sealing the means for transmitting load within a hole in a piston. 5 figures.

A method for simulating the release of natural gas from the rupture of high-pressure pipelines in any terrain.

PubMed

Deng, Yajun; Hu, Hongbing; Yu, Bo; Sun, Dongliang; Hou, Lei; Liang, Yongtu

2018-01-15

The rupture of a high-pressure natural gas pipeline can pose a serious threat to human life and environment. In this research, a method has been proposed to simulate the release of natural gas from the rupture of high-pressure pipelines in any terrain. The process of gas releases from the rupture of a high-pressure pipeline is divided into three stages, namely the discharge, jet, and dispersion stages. Firstly, a discharge model is established to calculate the release rate of the orifice. Secondly, an improved jet model is proposed to obtain the parameters of the pseudo source. Thirdly, a fast-modeling method applicable to any terrain is introduced. Finally, based upon these three steps, a dispersion model, which can take any terrain into account, is established. Then, the dispersion scenarios of released gas in four different terrains are studied. Moreover, the effects of pipeline pressure, pipeline diameter, wind speed and concentration of hydrogen sulfide on the dispersion scenario in real terrain are systematically analyzed. The results provide significant guidance for risk assessment and contingency planning of a ruptured natural gas pipeline. Copyright © 2017. Published by Elsevier B.V.

Strategies to Sustain and Enhance Performance in Stressful Environments

DTIC Science & Technology

1990-03-14

Pressure Switch in his left hand which controlled power to the vacuum source which was only active when the subject was pressing on the Page 6 positive... pressure switch . Internal LBNP chamber vacuum was calibrated with a Wallace & Tierman 1500 Hi-Performance Gauge (Model 61A-1D-0800, Wallace & Tierman...pressure release when the subject released the positive pressure switch without warning. Behavioral testing continued regardless of when LBNP was returned to

46 CFR 108.457 - Pressure release.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... Each air tight or vapor tight space, such as a paint locker, that is protected by a CO2 system must have a means for releasing pressure that accumulates within the space if CO2 is discharged into the...

Disruption of Pseudomonas putida by high pressure homogenization: a comparison of the predictive capacity of three process models for the efficient release of arginine deiminase.

PubMed

Patil, Mahesh D; Patel, Gopal; Surywanshi, Balaji; Shaikh, Naeem; Garg, Prabha; Chisti, Yusuf; Banerjee, Uttam Chand

2016-12-01

Disruption of Pseudomonas putida KT2440 by high-pressure homogenization in a French press is discussed for the release of arginine deiminase (ADI). The enzyme release response of the disruption process was modelled for the experimental factors of biomass concentration in the broth being disrupted, the homogenization pressure and the number of passes of the cell slurry through the homogenizer. For the same data, the response surface method (RSM), the artificial neural network (ANN) and the support vector machine (SVM) models were compared for their ability to predict the performance parameters of the cell disruption. The ANN model proved to be best for predicting the ADI release. The fractional disruption of the cells was best modelled by the RSM. The fraction of the cells disrupted depended mainly on the operating pressure of the homogenizer. The concentration of the biomass in the slurry was the most influential factor in determining the total protein release. Nearly 27 U/mL of ADI was released within a single pass from slurry with a biomass concentration of 260 g/L at an operating pressure of 510 bar. Using a biomass concentration of 100 g/L, the ADI release by French press was 2.7-fold greater than in a conventional high-speed bead mill. In the French press, the total protein release was 5.8-fold more than in the bead mill. The statistical analysis of the completely unseen data exhibited ANN and SVM modelling as proficient alternatives to RSM for the prediction and generalization of the cell disruption process in French press.

Correlation between balloon release pressure and no-reflow in patients with acute myocardial infarction undergoing direct percutaneous coronary intervention.

PubMed

Wang, Yanfei; Yao, Min; Liu, Haibo; Yang, Yuejin; Xie, Junmin; Jia, Xinwei; Pan, Huanjun; Wang, Chunyan

2014-01-01

Balloon release pressure may increase the incidence of no reflow after direct percutaneous coronary intervention (PCI). This randomized controlled study was designed to analyze the correlation between balloon release pressure and no-reflow in patients with acute myocardial infarction (AMI) undergoing direct PCI. There were 156 AMI patients who underwent PCI from January 1, 2010 to December 31, 2012, and were divided into two groups according to the stent inflation pressure: a conventional pressure group and a high pressure group. After PCI, angiography was conducted to assess the thrombolysis in myocardial infarction (TIMI) grade with related artery. Examinations were undertaken on all patients before and after the operation including cardiac enzymes, total cholesterol, low-density lipoprotein, blood glucose, homocysteine , β-thromboglobulin (β-TG), Hamilton depression scale (HAMD) and self-rating anxiety scale (SAS). After interventional therapy, the afore-mentioned parameters in both the conventional pressure group and high pressure group were again analyzed. The results showed that CK-MB, HAMD, SAS were significantly different (P < 0.05) in all patients after PCI, especially the CK-MB in the high pressure group ((25.7 ± 7.6) U/L vs. (76.7 ± 11.8) U/L). CK-MB, HAMD, SAS, and β-TG were comparative before PCI but they were significantly changed (P < 0.05) after intervention. No-reflow phenomenon occurred in 13 patients in the high pressure group, which was significantly higher than in the conventional pressure group (17.11% vs. 6.25%, P < 0.05). In stent implantation, using a pressure less than 1823.4 kPa balloon to release pressure may be the better choice to reduce the occurrence of no-reflow following direct PCI.

Hydraulic Pressure during Fluid Flow Regulates Purinergic Signaling and Cytoskeleton Organization of Osteoblasts.

PubMed

Gardinier, Joseph D; Gangadharan, Vimal; Wang, Liyun; Duncan, Randall L

2014-06-01

During physiological activities, osteoblasts experience a variety of mechanical forces that stimulate anabolic responses at the cellular level necessary for the formation of new bone. Previous studies have primarily investigated the osteoblastic response to individual forms of mechanical stimuli. However in this study, we evaluated the response of osteoblasts to two simultaneous, but independently controlled stimuli; fluid flow-induced shear stress (FSS) and static or cyclic hydrostatic pressure (SHP or CHP, respectively). MC3T3-E1 osteoblasts-like cells were subjected to 12dyn/cm 2 FSS along with SHP or CHP of varying magnitudes to determine if pressure enhances the anabolic response of osteoblasts during FSS. For both SHP and CHP, the magnitude of hydraulic pressure that induced the greatest release of ATP during FSS was 15 mmHg. Increasing the hydraulic pressure to 50 mmHg or 100 mmHg during FSS attenuated the ATP release compared to 15 mmHg during FSS. Decreasing the magnitude of pressure during FSS to atmospheric pressure reduced ATP release to that of basal ATP release from static cells and inhibited actin reorganization into stress fibers that normally occurred during FSS with 15 mmHg of pressure. In contrast, translocation of nuclear factor kappa B (NFκB) to the nucleus was independent of the magnitude of hydraulic pressure and was found to be mediated through the activation of phospholipase-C (PLC), but not src kinase. In conclusion, hydraulic pressure during FSS was found to regulate purinergic signaling and actin cytoskeleton reorganization in the osteoblasts in a biphasic manner, while FSS alone appeared to stimulate NFκB translocation. Understanding the effects of hydraulic pressure on the anabolic responses of osteoblasts during FSS may provide much needed insights into the physiologic effects of coupled mechanical stimuli on osteogenesis.

Hydraulic Pressure during Fluid Flow Regulates Purinergic Signaling and Cytoskeleton Organization of Osteoblasts

PubMed Central

Gardinier, Joseph D.; Gangadharan, Vimal; Wang, Liyun; Duncan, Randall L.

2014-01-01

During physiological activities, osteoblasts experience a variety of mechanical forces that stimulate anabolic responses at the cellular level necessary for the formation of new bone. Previous studies have primarily investigated the osteoblastic response to individual forms of mechanical stimuli. However in this study, we evaluated the response of osteoblasts to two simultaneous, but independently controlled stimuli; fluid flow-induced shear stress (FSS) and static or cyclic hydrostatic pressure (SHP or CHP, respectively). MC3T3-E1 osteoblasts-like cells were subjected to 12dyn/cm2 FSS along with SHP or CHP of varying magnitudes to determine if pressure enhances the anabolic response of osteoblasts during FSS. For both SHP and CHP, the magnitude of hydraulic pressure that induced the greatest release of ATP during FSS was 15 mmHg. Increasing the hydraulic pressure to 50 mmHg or 100 mmHg during FSS attenuated the ATP release compared to 15 mmHg during FSS. Decreasing the magnitude of pressure during FSS to atmospheric pressure reduced ATP release to that of basal ATP release from static cells and inhibited actin reorganization into stress fibers that normally occurred during FSS with 15 mmHg of pressure. In contrast, translocation of nuclear factor kappa B (NFκB) to the nucleus was independent of the magnitude of hydraulic pressure and was found to be mediated through the activation of phospholipase-C (PLC), but not src kinase. In conclusion, hydraulic pressure during FSS was found to regulate purinergic signaling and actin cytoskeleton reorganization in the osteoblasts in a biphasic manner, while FSS alone appeared to stimulate NFκB translocation. Understanding the effects of hydraulic pressure on the anabolic responses of osteoblasts during FSS may provide much needed insights into the physiologic effects of coupled mechanical stimuli on osteogenesis. PMID:24910719

Cooling of the Earth in the Archaean: Consequences of pressure-release melting in a hotter mantle

NASA Astrophysics Data System (ADS)

Vlaar, N. J.; van Keken, P. E.; van den Berg, A. P.

1994-01-01

A model is presented to describe the cooling of the Earth in the Archaean. At the higher Archaean mantle temperatures pressure-release melting starts deeper and generates a thicker basaltic or komatiitic crust and depleted harzburgite layer compared with the present-day situation. Intrinsic compositional stability and lack of mechanical coherency renders the mechanism of plate tectonics ineffective. It is proposed that the Archaean continents stabilised early on top of a compositionally stratified root. In the Archaean oceanic lithosphere, hydrated upper crust can founder and recycle through its high-pressure phase eclogite. Eclogite remelting and new pressure-release melting generates new crustal material. Migration of magma and latent heat release by solidification at the surface provides an efficient mechanism to cool the mantle by several hundreds of degrees during the Archaean. This can satisfactorily explain the occurrence of high extrusion temperature komatiites and lower extrusion temperature basalts in greenstone belts as being derived from the same source by different mechanisms.

Nanostructural control of methane release in kerogen and its implications to wellbore production decline

NASA Astrophysics Data System (ADS)

Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

2016-06-01

Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

Osmotic pressure driven protein release from viscous liquid, hydrophobic polymers based on 5-ethylene ketal ε-caprolactone: potential and mechanism.

PubMed

Babasola, Iyabo Oladunni; Zhang, Wei; Amsden, Brian G

2013-11-01

In this study, the potential of low molecular weight, viscous liquid polymers based on 5-ethylene ketal ε-caprolactone for localized delivery of proteins via an osmotic pressure release mechanism was investigated. Furthermore, the osmotic release mechanism from viscous liquid polymers was elucidated. 5-Ethylene ketal ε-caprolactone was homopolymerized or copolymerized with D,L-lactide (DLLA) by ring-opening polymerization. Polymer hydrophobicity was adjusted by choice of initiator; hydrophobic polymers were prepared by initiating with octan-1-ol, while more hydrophilic polymers were prepared by initiating with 350 g/mol methoxy poly(ethylene glycol) (PEG). Particles consisting of bovine serum albumin (BSA) as a model protein drug were co-lyophilized with trehalose at 50:50 and 10:90 (w/w) ratios and were mixed into the polymers at 1% and/or 5% (w/w) particle loading. The release and mechanism of release of BSA from the polymers were assessed in vitro. BSA was released in a sustained manner, with a near zero-order release profile and with minimal burst effect for 5-80 days depending on the polymer's hydrophilicity; the release was faster from the PEG initiated polymers than from the octan-1-ol initiated polymers. Increasing the particle loading from 1% to 5% (w/w) resulted in a more noticeable burst effect, but did not significantly increase the mass fraction release rate. This release behavior was determined to proceed as follows. Release from the polymer was triggered by the water activity gradient between the surrounding aqueous medium and the saturated solution, which forms when water is absorbed from the surrounding medium to dissolve a given particle. The generated pressure initiates swelling around the particle/polymer interface and creates a superhydrated polymer region through which the solute is transported by convection, at a rate determined by the osmotic pressure generated. Copyright © 2013 Elsevier B.V. All rights reserved.

Biomechanical consequences of adding plantar fascia release to metatarsal osteotomies: Changes in forefoot plantar pressures.

PubMed

Aydogan, Umur; Roush, Evan P; Moore, Blake E; Andrews, Seth H; Lewis, Gregory S

2017-04-01

Destruction of the normal metatarsal arch by a long metatarsal is often a cause for metatarsalgia. When surgery is warranted, distal oblique, or proximal dorsiflexion osteotomies of the long metatarsal bones are commonly used. The plantar fascia has anatomical connection to all metatarsal heads. There is controversial scientific evidence on the effect of plantar fascia release on forefoot biomechanics. In this cadaveric biomechanical study, we hypothesized that plantar fascia release would augment the plantar metatarsal pressure decreasing effects of two common second metatarsal osteotomy techniques. Six matched pairs of foot and ankle specimens were mounted on a pressure mat loading platform. Two randomly assigned surgery groups, which had received either distal oblique, or proximal dorsiflexion osteotomy of the second metatarsal, were evaluated before and after plantar fasciectomy. Specimens were loaded up to a ground reaction force of 400 N at varying Achilles tendon forces. Average pressures, peak pressures, and contact areas were analyzed. Supporting our hypothesis, average pressures under the second metatarsal during 600 N Achilles load were decreased by plantar fascia release following proximal osteotomy (p < 0.05). However contrary to our hypothesis, peak pressures under the second metatarsal were significantly increased by plantar fascia release following modified distal osteotomy, under multiple Achilles loading conditions (p < 0.05). Plantar fasciotomy should not be added to distal metatarsal osteotomy in the treatment of metatarsalgia. If proximal dorsiflexion osteotomy would be preferred, plantar fasciotomy should be approached cautiously not to disturb the forefoot biomechanics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:800-804, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Tuning silver ion release properties in reactively sputtered Ag/TiOx nanocomposites

NASA Astrophysics Data System (ADS)

Xiong, J.; Ghori, M. Z.; Henkel, B.; Strunskus, T.; Schürmann, U.; Deng, M.; Kienle, L.; Faupel, F.

2017-07-01

Silver/titania nanocomposites with strong bactericidal effects and good biocompatibility/environmental safety show a high potential for antibacterial applications. Tailoring the silver ion release is thus highly promising to optimize the antibacterial properties of such coatings and to preserve biocompatibility. Reactive sputtering is a fast and versatile method for the preparation of such Ag/TiOx nanocomposites coatings. The present work is concerned with the influence of sputter parameters on the surface morphology and silver ion release properties of reactively sputtered Ag/TiOx nanocomposites coatings showing a silver nanoparticle size distribution in the range from 1 to 20 nm. It is shown that the silver ion release rate strongly depends on the total pressure: the coatings prepared at lower pressure present a lower but long-lasting release behavior. The much denser structure produced under these conditions reduces the transport of water molecules into the coating. In addition, the influence of microstructure and thickness of titanium oxide barriers on the silver ion release were investigated intensively. Moreover, for the coatings prepared at high total pressure, it was demonstrated that stable and long-lasting silver release can be achieved by depositing a barrier with a high rate. Nanocomposites produced under these conditions show well controllable silver ion release properties for applications as antibacterial coatings.

REACTOR CONTROL

DOEpatents

Fortescue, P.; Nicoll, D.

1962-04-24

A control system employed with a high pressure gas cooled reactor in which a control rod is positioned for upward and downward movement into the neutron field from a position beneath the reactor is described. The control rod is positioned by a coupled piston cylinder releasably coupled to a power drive means and the pressurized coolant is directed against the lower side of the piston. The coolant pressure is offset by a higher fiuid pressure applied to the upper surface of the piston and means are provided for releasing the higher pressure on the upper side of the piston so that the pressure of the coolant drives the piston upwardly, forcing the coupled control rod into the ncutron field of the reactor. (AEC)

Thermodynamic Changes in the Coal Matrix - Gas - Moisture System Under Pressure Release and Phase Transformations of Gas Hydrates

NASA Astrophysics Data System (ADS)

Dyrdin, V. V.; Smirnov, V. G.; Kim, T. L.; Manakov, A. Yu.; Fofanov, A. A.; Kartopolova, I. S.

2017-06-01

The physical processes occurring in the coal - natural gas system under the gas pressure release were studied experimentally. The possibility of gas hydrates presence in the inner space of natural coal was shown, which decomposition leads to an increase in the amount of gas passing into the free state. The decomposition of gas hydrates can be caused either by the seam temperature increase or the pressure decrease to lower than the gas hydrates equilibrium curve. The contribution of methane released during gas hydrates decomposition should be taken into account in the design of safe mining technologies for coal seams prone to gas dynamic phenomena.

Shock, release and Taylor impact of the semicrystalline thermoplastic polytetrafluoroethylene

NASA Astrophysics Data System (ADS)

Bourne, N. K.; Brown, E. N.; Millett, J. C. F.; Gray, G. T.

2008-04-01

The high strain-rate response of polymers is a subject that has gathered interest over recent years due to their increasing engineering importance, particularly in load bearing applications subject to extremes of pressure and strain rate. The current work presents two specific sets of experiments interrogating the effect of dynamic, high-pressure loading in the regime of the phase II to phase III pressure-induced crystalline phase transition in polytetrafluoroethylene (PTFE). These are gas-gun driven plate- and Taylor impact. Together these experiments highlight several effects associated with the dynamic, pressure-induced phase transitions in PTFE. An elevated release wave speed shows evidence of a pressure-induced phase change at a stress commensurate with that observed statically. It is shown that convergence between analytic derivations of release wave speed and the data requires the phase II to III transition to occur. Taylor impact is an integrated test that highlights continuum behavior that has origin in mesoscale response. There is a rapid transition from ductile to brittle behavior observed that occurs at a pressure consistent with this phase transition.

High pressure-assisted encapsulation of vitamin D2 in reassembled casein micelles

NASA Astrophysics Data System (ADS)

Menéndez-Aguirre, O.; Stuetz, W.; Grune, T.; Kessler, A.; Weiss, J.; Hinrichs, J.

2011-03-01

For the encapsulation of vitamin D2, native casein micelles and vitamin D2 with or without additional Ca2+-Pi were treated at 600 MPa and 37 °C for 60 min. The pressure release rate was set at 20 or 600 MPa/min. Vitamin D2 was quantified by reversed-phase high-performance liquid chromatography, and physical properties of the micelles were analysed by photon correlation spectroscopy. The results demonstrate that simultaneous application of Ca2+-Pi and high pressure treatment with a fast release rate significantly increased loading of vitamin D2 per casein by 6.9-fold. The addition of Ca2+-Pi enhanced micelle aggregation and the vitamin was entrapped within the formed aggregates. However, high pressure treatment without Ca2+-Pi with a slow pressure release rate revealed similar results, increasing vitamin D2 per casein by 6.7-fold. The vitamin D2 loading in reassembled casein micelles is supposed to be due to hydrophobic interactions between the hydrophobic domains of the micelles.

Effect of oxygen at high pressure on spontaneous transmitter release.

PubMed

Colton, J S; Colton, C A

1978-11-01

The effect of oxygen at high pressure (OHP) on resting membrane properties (effective membrane resistance (Reff) and membrane potential (Vm)) and the spontaneous release of excitatory transmitter were examined at the lobster neuromuscular junction. Pressurization with 100% oxygen to 150 pounds per square inch gauge pressure (psig) or with nitrogen to 150 psig (7,000 mmHg nitrogen and 135 mmHg oxygen) produced a decrease in Reff associated with a hyperpolarization of Vm. These changes, however, returned to control values within 20--30 min after completion of pressurization. Spontaneous release of excitatory transmitter was shown to increase dramatically in the presence of 100% oxygen at 150 psig. The increase in miniature end-plate potential (MEPP) frequency persisted beyond the transient changes seen with Reff and Vm. This effect was selective to oxygen, as pressurization with nitrogen did not produce an increase in MEPP frequency. No change in average MEPP amplitude was seen with either OHP or pressure alone. An OHP-induced increase in MEPP frequency was also seen at the frog neuromuscular junction. The results indicate that both glutamate-mediated and acetylcholine-mediated synaptic transmission are altered by OHP.

Shock driven melting and resolidification upon release in cerium

NASA Astrophysics Data System (ADS)

Bolme, Cindy; Bronkhorst, Curt; Brown, Don; Cherne, Frank; Cooley, Jason; Furlanetto, Michael; Gleason, Arianna; Jensen, Brian; Owens, Charles; Ali, Suzanne; Fratanduono, Dayne; Galtier, Eric; Granados, Eduardo; Lee, Hae Ja; Nagler, Bob

2017-06-01

The temperature rise due to increasing entropy during shock compression and the corresponding temperature decrease due to isentropic expansion upon release cause the physics of melting and solidification under dynamic pressure changes to differ fundamentally from the more common liquid-solid transitions governed by thermal diffusion. We investigated laser shock driven melting and resolidification during release in cerium to examine the dynamics of these processes. Cerium was selected as the material of study due to the low pressure at which γ-cerium melts along the principle Hugoniot and due to cerium's anomalous melt boundary at low pressure, which facilitates its transition from liquid to solid during isentropic release. The structural phase of cerium was probed with X-ray diffraction using the LCLS X-ray free electron laser, which provided in situ measurements of the transition dynamics. The experimental results will be presented showing the resolidification occurring over 10s of ns.

Ultrasound triggered drug delivery with liposomal nested microbubbles.

PubMed

Wallace, N; Wrenn, S P

2015-12-01

When ultrasound contrast agent microbubbles are nested within a liposome, damage to the liposome membrane caused by both stable and inertial cavitation of the microbubble allows for release of the aqueous core of the liposome. Triggered release was not accomplished unless microbubbles were present within the liposome. Leakage was tested using fluorescence assays developed specifically for this drug delivery vehicle and qualitative measurements using an optical microscope. These studies were done using a 1 MHz focused ultrasound transducer while varying parameters including peak negative ultrasound pressure, average liposome diameter, and microbubble concentration. Two regimes exist for membrane disruption caused by cavitating microbubbles. A faster release rate, as well as permanent membrane damage are seen for samples exposed to high pressure (2.1-3.7 MPa). A slower release rate and dilation/temporary poration are characteristic of stable cavitation for low pressure studies (0.54-1.7 MPa). Copyright © 2015 Elsevier B.V. All rights reserved.

Probing effects of pressure release on virus capture during virus filtration using confocal microscopy.

PubMed

Dishari, Shudipto K; Venkiteshwaran, Adith; Zydney, Andrew L

2015-10-01

Virus filtration is used to ensure drug safety in the production of biotherapeutics. Several recent studies have shown a dramatic decrease in virus retention as a result of a process disruption, e.g., a transient pressure release. In this work, a novel two-label fluorescence technique was developed to probe virus capture within virus filtration membranes using confocal microscopy. Experiments were performed with Ultipor® DV20, Viresolve® Pro, and Viresolve® NFP membranes using bacteriophage φx174 as a model virus. The filters were challenged with two batches of fluorescently labeled phage: one labeled with red dye (Cy5) and one with green dye (SYBR Gold) to visualize captured phage from before and after the pressure release. The capture patterns seen in the confocal images were a strong function of the underlying membrane morphology and pore structure. The DV20 and Viresolve® NFP showed migration of previously captured phage further into the filter, consistent with the observed loss of virus retention after the pressure release. In contrast, there was no migration of captured virus in the Viresolve® Pro membranes, and these filters were also the only ones to show stable virus retention after a pressure release. The direct visualization of virus capture using the two-label fluorescence technique provides unique insights into the factors controlling the retention characteristics of virus filters with different pore structure. © 2015 Wiley Periodicals, Inc.

Nanostructural control of methane release in kerogen and its implications to wellbore production decline

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

Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

In spite of the massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Here we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases, and we usemore » molecular simulations to demonstrate it. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Finally, our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.« less

Nanostructural control of methane release in kerogen and its implications to wellbore production decline

PubMed Central

Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

2016-01-01

Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release. PMID:27306967

Nanostructural control of methane release in kerogen and its implications to wellbore production decline

DOE PAGES

Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

2016-06-16

In spite of the massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix–a limiting step in shale gas extraction. Here we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30–47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases, and we usemore » molecular simulations to demonstrate it. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3–35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Finally, our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.« less

A β-cyclodextrin, polyethyleneimine and silk fibroin hydrogel containing Centella asiatica extract and hydrocortisone acetate: releasing properties and in vivo efficacy for healing of pressure sores.

PubMed

Lee, M S; Seo, S R; Kim, J-C

2012-10-01

  Pressure sores are lesions caused by impaired blood flow. Conventional dressings can absorb exudates, but do not promote wound healing. A hydrogel composed of β-cyclodextrin (β-CD), polyethyleneimine (PEI) and silk fibroin (SF) was assessed for use in healing of pressure sores. The hydrogel was prepared by crosslinking β-CD-grafted PEI and SF using epichlorohydrin. The gel was then immersed in an aqueous solution of Centella asiatica extract (CAE) 0.7 mg/mL and/or hydrocortisone acetate (HCA) 0.5 mg/mL. The in vivo pressure sore-healing efficacy of the dry gel (with or without the drugs) was investigated in terms of the hyperplasia of epidermis and the number of neutrophils in the skin tissue. The specific loading of CAE was 0.0091 g/g of dry gel. The percentage of CAE released at 24 h at pH 3.0, 5.0 and 7.4 was approximately 63.9%, 55.0% and 44.4%, respectively. This pH-dependent release is possibly due to the degree of gel swelling, which decreased with increasing pH. The specific loading of HCA was 0.0050 g/g dry gel, and the percentage release of HCA at 24 h was around 20% at all three pH points. It is likely that HCA release is independent of pH. HCA is a hydrophobic compound, and therefore the release of HCA is affected by the partitioning of HCA between the β-CD cavity and the bulk water phase, but not by the degree of swelling of the hydrogel. The pressure sores treated with the hydrogel healed in 6 days, compared with 10 days for controls. In this study, a β-CD/PEI/SF hydrogel containing CAE and HCA reduced the healing time for pressure sores. © The Author(s). CED © 2012 British Association of Dermatologists.

Tension responses to rapid pressure release in glycerinated rabbit muscle fibers.

PubMed Central

Fortune, N S; Geeves, M A; Ranatunga, K W

1991-01-01

We have previously shown that the isometric tension of a fully calcium-activated skinned rabbit psoas muscle fiber is reversibly depressed by increased hydrostatic pressure. We report here the characterization of tension transients induced by a rapid (less than 1-ms) release of increased pressure at 12 degrees C. The tension transient consists of three clear phases, an initial further decrease of tension in phase with pressure change followed by two phases of tension increase back to the level recorded at ambient pressure. The mean reciprocal relaxation time for phase 2 (1/tau 2) was approximately 17 s-1 and that for phase 3 (1/tau 3) was 3 s-1. The presence of 20 mM inorganic phosphate markedly increased 1/tau 2 to approximately 52 s-1 and decreased 1/tau 3 to approximately 1.7 s-1. These observations are interpreted in terms of a pressure-sensitive transition between two attached crossbridge states of low (or zero) and higher force. This is compatible with the pressure-sensitive isomerization of actomyosin previously observed in solution. The results presented allow us to propose a coupling between a specific pressure-sensitive isomerization of purified actomyosin, the phosphate release step of the ATPase pathway, and the force-generating event of the cross-bridge cycle. PMID:1871140

Direct high-pressure NMR observation of dipicolinic acid leaking from bacterial spore: A crucial step for thermal inactivation.

PubMed

Akasaka, Kazuyuki; Maeno, Akihiro; Yamazaki, Akira

2017-12-01

A bacterial spore protects itself with an unusually high concentration (~10% in dry weight of spore) of dipicolinic acid (DPA), the release of which is considered the crucial step for inactivating it under mild pressure and temperature conditions. However, the process of how the spore releases DPA in response to pressure remains obscure. Here we apply 1 H high-resolution high-pressure NMR spectroscopy, for the first time, to the spore suspension of Bacillus subtilis natto and monitor directly and in real-time the leaking process of DPA in response to pressure of 200MPa at 20°C. We find that about one third of the total DPA leaks immediately upon applying pressure, but that the rest leaks slowly in hrs upon decreasing the pressure. Once DPA is fully released from the spore, the proteins of the spore become easily denatured at a mild temperature, e.g., 80°C, much below the temperature commonly used to inactivate spores (121°C). The success of the present experiment opens a new avenue for studying bacterial spores and cells at the molecular level in response to pressure, temperature and other perturbations. Copyright © 2017 Elsevier B.V. All rights reserved.

Improved oxygenation 24 hours after transition to airway pressure release ventilation or high-frequency oscillatory ventilation accurately discriminates survival in immunocompromised pediatric patients with acute respiratory distress syndrome*.

PubMed

Yehya, Nadir; Topjian, Alexis A; Thomas, Neal J; Friess, Stuart H

2014-05-01

Children with an immunocompromised condition and requiring invasive mechanical ventilation have high risk of death. Such patients are commonly transitioned to rescue modes of nonconventional ventilation, including airway pressure release ventilation and high-frequency oscillatory ventilation, for acute respiratory distress syndrome refractory to conventional ventilation. Our aim was to describe our experience with airway pressure release ventilation and high-frequency oscillatory ventilation in children with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation and to identify factors associated with survival. Retrospective cohort study. Tertiary care, university-affiliated PICU. Sixty pediatric patients with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation. None. Demographic data, ventilator settings, arterial blood gases, oxygenation index, and PaO(2)/FIO(2) were recorded before transition to either mode of nonconventional ventilation and at predetermined intervals after transition for up to 5 days. Mortality in the entire cohort was 63% and did not differ between patients transitioned to airway pressure release ventilation and high-frequency oscillatory ventilation. For both airway pressure release ventilation and high-frequency oscillatory ventilation, improvements in oxygenation index and PaO(2)/FIO(2) at 24 hours expressed as a fraction of pretransition values (oxygenation index(24)/oxygenation index(pre) and PaO(2)/FIO(224)/PaO(2)/FIO(2pre)) reliably discriminated nonsurvivors from survivors, with receiver operating characteristic areas under the curves between 0.89 and 0.95 (p for all curves < 0.001). Sensitivity-specificity analysis suggested that less than 15% reduction in oxygenation index (90% sensitive, 75% specific) or less than 90% increase in PaO(2)/FIO(2) (80% sensitive, 94% specific) 24 hours after transition to airway pressure release ventilation were the optimal cutoffs to identify nonsurvivors. The comparable values 24 hours after transition to high-frequency oscillatory ventilation were less than 5% reduction in oxygenation index (100% sensitive, 83% specific) or less than 80% increase in PaO(2)/FIO(2) (91% sensitive, 89% specific) to identify nonsurvivors. In this single-center retrospective study of pediatric patients with an immunocompromised condition and acute respiratory distress syndrome failing conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation, improved oxygenation at 24 hours expressed as PaO(2)/FIO(224)/PaO(2)/FIO(2pre) or oxygenation index(24)/oxygenation indexpre reliably discriminates nonsurvivors from survivors. These findings should be prospectively verified.

Recyclability of mixed office waste papers containing pressure sensitive adhesives and silicone release liners

Treesearch

Julie Hess; Roberta Sena-Gomes; Lisa Davie; Marguerite Sykes

2001-01-01

Increased use of pressure sensitive adhesives for labels and stamps has introduced another contaminant into the office paper stream: silicone- coated release liners. This study examines methods and conditions for removal of contaminants, including these liners, from a typical batch of discarded office papers. Removal of contaminants contained in the furnish were...

Carbon nanotube vacuum gauges utilizing long, dissipative tubes

NASA Astrophysics Data System (ADS)

Kaul, Anupama B.; Manohara, Harish M.

2008-04-01

A carbon nanotube-based thermal conductivity vacuum gauge is described which utilizes 5-10 μm long diffusively contacted SWNTs for vacuum sensing. By etching the thermal SiO II beneath the tubes and minimizing heat conduction through the substrate, pressure sensitivity was extended toward higher vacuums. The pressure response of unannealed and annealed devices was compared to that of released devices. The released devices showed sensitivity to pressure as low as 1 x 10 -6 Torr. The sensitivity increased more dramatically with power for the released device compared to that of the unreleased device. Low temperature electronic transport measurements of the tubes were suggestive of a thermally activated hopping mechanism where the activation energy for hopping was calculated to be ~ 39 meV.

System for pressure letdown of abrasive slurries

DOEpatents

Kasper, Stanley

1991-01-01

A system and method for releasing erosive slurries from containment at high pressure without subjecting valves to highly erosive slurry flow. The system includes a pressure letdown tank disposed below the high-pressure tank, the two tanks being connected by a valved line communicating the gas phases and a line having a valve and choke for a transfer of liquid into the letdown tank. The letdown tank has a valved gas vent and a valved outlet line for release of liquid. In operation, the gas transfer line is opened to equalize pressure between tanks so that a low level of liquid flow occurs. The letdown tank is then vented, creating a high-pressure differential between the tanks. At this point, flow between tanks is controlled by the choke. High-velocity, erosive flow through a high-pressure outlet valve is prevented by equalizing the start up pressure and thereafter limiting flow with the choke.

Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

PubMed Central

Dai, Ching-Liang; Lu, Po-Wei; Chang, Chienliu; Liu, Cheng-Yang

2009-01-01

The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa. PMID:22303167

Capacitive micro pressure sensor integrated with a ring oscillator circuit on chip.

PubMed

Dai, Ching-Liang; Lu, Po-Wei; Chang, Chienliu; Liu, Cheng-Yang

2009-01-01

The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0-300 kPa.

46 CFR 160.062-2 - Types.

Code of Federal Regulations, 2013 CFR

2013-10-01

... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an approval...

46 CFR 160.062-2 - Types.

Code of Federal Regulations, 2012 CFR

2012-10-01

... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an approval...

46 CFR 160.062-2 - Types.

Code of Federal Regulations, 2011 CFR

2011-10-01

... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an approval...

46 CFR 160.062-2 - Types.

Code of Federal Regulations, 2010 CFR

2010-10-01

... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an approval...

46 CFR 160.062-2 - Types.

Code of Federal Regulations, 2014 CFR

2014-10-01

... APPROVAL LIFESAVING EQUIPMENT Releases. Lifesaving Equipment, Hydraulic and Manual § 160.062-2 Types. (a) The hydraulic releases referred to under § 160.062-1(a)(1) are of the diaphram-spring plunger type, which releases a buoyant load under hydrostatic pressure. (b) All hydraulic releases given an approval...

Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames

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

Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W.

An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom ofmore » the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate for all flames. (author)« less

Measuring the properties of shock released Quartz and Parylene-N

NASA Astrophysics Data System (ADS)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2016-10-01

The high pressure and temperature properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies the single shock Hugoniot. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography.

Volcanic Gas

MedlinePlus

... and pressure decreases, gases are released from the liquid portion of the magma (melt) and continue to travel upward and are eventually released into the atmosphere. Large eruptions can release enormous amounts of gas in a short time. The 1991 eruption of ...

Influence of Postprandial Intragastric Pressures on Drug Release from Gastroretentive Dosage Forms.

PubMed

Schneider, Felix; Hoppe, Melanie; Koziolek, Mirko; Weitschies, Werner

2018-05-29

Despite extensive research in the field of gastroretentive dosage forms, this "holy grail" of oral drug delivery yet remained an unmet goal. Especially under fasting conditions, the reproducible retention of dosage forms in the stomach seems to be an impossible task. This is why such systems are often advised to be taken together with food. But also the postprandial motility can contribute significantly to the failure of gastroretentive dosage forms. To investigate the influence of postprandial pressure conditions on drug release from such systems, we used a novel in vitro dissolution tool, the dissolution stress test device. With the aid of this device, we simulated three different intragastric pressure profiles that may occur after postprandial intake. These transit scenarios were based on recently obtained, postprandial SmartPill® data. The tested systems, Glumetza® 1000 and Madopar® HBS 125, are marketed dosage forms that are based on different approaches to achieve proper gastric retention. All three transit scenarios revealed a highly pressure-sensitive drug release behavior, for both drugs. For Madopar® HBS 125, nearly complete drug release was observed even after early occurring pressures. Glumetza® 1000 seemed to be more resistant to these, most likely due to incomplete wetting of the system. On the contrary to these findings, data from standard dissolution tests using the paddle apparatus displayed controlled drug release for both systems for about 6 h. Based on these results, it can be doubted that established gastroretentive systems stay intact over a longer period of time, even under postprandial conditions.

Confinement of hydrogen at high pressure in carbon nanotubes

DOEpatents

Lassila, David H [Aptos, CA; Bonner, Brian P [Livermore, CA

2011-12-13

A high pressure hydrogen confinement apparatus according to one embodiment includes carbon nanotubes capped at one or both ends thereof with a hydrogen-permeable membrane to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough. A hydrogen confinement apparatus according to another embodiment includes an array of multi-walled carbon nanotubes each having first and second ends, the second ends being capped with palladium (Pd) to enable the high pressure confinement of hydrogen and release of the hydrogen therethrough as a function of palladium temperature, wherein the array of carbon nanotubes is capable of storing hydrogen gas at a pressure of at least 1 GPa for greater than 24 hours. Additional apparatuses and methods are also presented.

Experimental investigation of spontaneous ignition and flame propagation at pressurized hydrogen release through tubes with varying cross-section.

PubMed

Duan, Qiangling; Xiao, Huahua; Gao, Wei; Gong, Liang; Sun, Jinhua

2016-12-15

An experimental investigation of spontaneous ignition and flame propagation at high-pressure hydrogen release via cylindrical tubes with varying cross-section is presented. Tubes with different transverse cross-sections are considered in the experiments: (1) local contraction, (2) local enlargement, (3) abrupt contraction, and (4) abrupt enlargement. The results show that the presence of the varying cross-section geometries can significantly promote the occurrence of spontaneous ignition. Compared to the tube with constant cross-section, the minimum pressure release needed for spontaneous ignition for the varying cross-sections tubes is considerably lower. Moreover, the initial ignition location is closer to the disk in the presence of varying cross-section geometries in comparison with straight channel. As the flame emerges from the outlet of the tube, the velocity of the flame front in the vicinity of the nozzle increases sharply. Then, a deflagration develops across the mixing zone of hydrogen/air mixture. The maximum deflagration overpressure increases linearly with the release pressure. Subsequently, a hydrogen jet flame is produced and evolves different shapes at different release stages. A fireball is formed after the jet flame spouts in the open air. Later, the fireball develops into a jet flame which shifts upward and continues to burn in the vertical direction. Copyright © 2016 Elsevier B.V. All rights reserved.

Predatory behavior of long-legged flies (Diptera:Dolichopodidae) and their potential negative effects on the parasitoid biological control agent of the Asian citrus psyllid (Hemiptera:Liviidae)

USDA-ARS?s Scientific Manuscript database

Impact of biological control agents such as parasitoids can be improved by determining best times for release when predation pressures will be reduced. Large populations of long-legged predatory flies (Diptera: Dolichopodidae) impose heavy predation pressure on inundative releases of the parasitoid ...

A new way to lower blood pressure: pass the chili peppers please!

PubMed

Sessa, William C

2010-08-04

Activation of TRPV1 channels in sensory nerves by capsaicin promotes neuropeptide release, leading to the perception of pain and inflammation. In this issue, Yang et al. (2010) demonstrate that vascular TRPV1 mediates a beneficial effect of capsaicin in the cardiovascular system, promoting nitric oxide release and lowering blood pressure. Copyright 2010 Elsevier Inc. All rights reserved.

Chemical release module facility

NASA Technical Reports Server (NTRS)

Reasoner, D. L.

1980-01-01

The chemical release module provides the capability to conduct: (1) thermite based metal vapor releases; (2) pressurized gas releases; (3) dispersed liquid releases; (4) shaped charge releases from ejected submodules; and (5) diagnostic measurements with pi supplied instruments. It also provides a basic R-F and electrical system for: (1) receiving and executing commands; (2) telemetering housekeeping data; (3) tracking; (4) monitoring housekeeping and control units; and (5) ultrasafe disarming and control monitoring.

Heat release effects in a turbulent, reacting shear layer

NASA Astrophysics Data System (ADS)

Hermanson, James Carl

The effects of heat release were studied in a planar, gaseous reacting mixing layer formed between free streams containing hydrogen and fluorine in inert diluents. Sufficiently high concentrations of reactants were employed to produce adiabatic flame temperature rises of up to 940 K (1240 K absolute). The Reynolds number at the measuring station, based on velocity difference, 1% temperature thickness and cold kinematic viscosity was approximately 6x10^4. The temperature field was measured with cold wire resistance thermometers and thermocouples. Flow visualization was accomplished by schlieren spark and motion picture photography. Mean velocity information was extracted from mean pitot probe dynamic pressure measurements.Though the displacement thickness of the layer, for zero streamwise pressure gradient, increased with increasing heat release, the actual growth rate of the layer did not increase, but instead decreased slightly. The overall entrainment into the layer was seen to be substantially reduced as a consequence of heat release. Calculations showed that the decrease in layer growth rate can be accounted for by a corresponding reduction in turbulent shear stress.The mean temperature rise profiles, normalized by the adiabatic flame temperature rise, were not greatly changed in shape by heat release. A small decrease in normalized mean temperature rise with heat release was observed. Large scale coherent structures were observed to persist at all levels of heat release in this investigation. The mean structure spacing decreased with increasing temperature. This decrease exceeded the rate of layer growth rate reduction, and suggests that the mechanisms of vortex amalgamation were, to some extent, inhibited by heat release.Imposition of a favorable pressure gradient resulted in additional thinning of the layer, and caused a slight increase in the mixing and amount of chemical product formation. The change in layer growth rate can be shown to be related to a change in free stream velocity ratio induced by pressure gradient.

Airway pressure release ventilation during ex vivo lung perfusion attenuates injury.

PubMed

Mehaffey, J Hunter; Charles, Eric J; Sharma, Ashish K; Money, Dustin T; Zhao, Yunge; Stoler, Mark H; Lau, Christine L; Tribble, Curtis G; Laubach, Victor E; Roeser, Mark E; Kron, Irving L

2017-01-01

Critical organ shortages have resulted in ex vivo lung perfusion gaining clinical acceptance for lung evaluation and rehabilitation to expand the use of donation after circulatory death organs for lung transplantation. We hypothesized that an innovative use of airway pressure release ventilation during ex vivo lung perfusion improves lung function after transplantation. Two groups (n = 4 animals/group) of porcine donation after circulatory death donor lungs were procured after hypoxic cardiac arrest and a 2-hour period of warm ischemia, followed by a 4-hour period of ex vivo lung perfusion rehabilitation with standard conventional volume-based ventilation or pressure-based airway pressure release ventilation. Left lungs were subsequently transplanted into recipient animals and reperfused for 4 hours. Blood gases for partial pressure of oxygen/inspired oxygen fraction ratios, airway pressures for calculation of compliance, and percent wet weight gain during ex vivo lung perfusion and reperfusion were measured. Airway pressure release ventilation during ex vivo lung perfusion significantly improved left lung oxygenation at 2 hours (561.5 ± 83.9 mm Hg vs 341.1 ± 136.1 mm Hg) and 4 hours (569.1 ± 18.3 mm Hg vs 463.5 ± 78.4 mm Hg). Likewise, compliance was significantly higher at 2 hours (26.0 ± 5.2 mL/cm H 2 O vs 15.0 ± 4.6 mL/cm H 2 O) and 4 hours (30.6 ± 1.3 mL/cm H 2 O vs 17.7 ± 5.9 mL/cm H 2 O) after transplantation. Finally, airway pressure release ventilation significantly reduced lung edema development on ex vivo lung perfusion on the basis of percentage of weight gain (36.9% ± 14.6% vs 73.9% ± 4.9%). There was no difference in additional edema accumulation 4 hours after reperfusion. Pressure-directed airway pressure release ventilation strategy during ex vivo lung perfusion improves the rehabilitation of severely injured donation after circulatory death lungs. After transplant, these lungs demonstrate superior lung-specific oxygenation and dynamic compliance compared with lungs ventilated with standard conventional ventilation. This strategy, if implemented into clinical ex vivo lung perfusion protocols, could advance the field of donation after circulatory death lung rehabilitation to expand the lung donor pool. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

The effects of heat treatment on selected properties of a conventional and a resin-modified glass ionomer cement.

PubMed

Rafeek, Reisha N

2008-05-01

This study investigated the effects of application of heat alone and heat & pressure on the compressive strength and modulus, the stress relaxation characteristics and the fluoride release of a conventional and a resin-modified glass ionomer cement. Cylindrical specimens were made from both materials and divided into 3 groups. One group was heat treated in an oven at 120 degrees C for 20 min, another group was subjected to heat & pressure at 120 degrees C for 20 min at 6-bar pressure. The third group acted as a control. The compressive strength and modulus, stress relaxation and fluoride release were tested over 56 days. The results of this investigation indicate that heat treatment had no significant effect on the conventional GIC used but significantly affected the resin modified GIC by increasing both the compressive strength and modulus and reducing the stress relaxation characteristics and the fluoride release. The use of GIC to produce inlay or onlay restorations that adhere to tooth tissue and release fluoride would be highly desirable. The results of this study indicate that it is possible to improve the strength of RMGIC with heat to a limited extent, but fluoride release may decrease.

Intermittent hydrostatic pressure inhibits shear stress-induced nitric oxide release in human osteoarthritic chondrocytes in vitro.

PubMed

Lee, Mel S; Trindade, Michael C D; Ikenoue, Takashi; Schurman, David J; Goodman, Stuart B; Smith, R Lane

2003-02-01

To test the effects of intermittent hydrostatic pressure (IHP) on nitric oxide (NO) release induced by shear stress and matrix macromolecule gene expression in human osteoarthritic chondrocytes in vitro. Chondrocytes isolated from cartilage samples from 9 patients with osteoarthritis were cultured and exposed to either shear stress or an NO donor. Nitrite concentration was measured using the Griess reaction. Matrix macromolecule mRNA signal levels were determined using reverse-transcriptase polymerase chain reaction and quantified by imaging analysis software. Exposure to shear stress upregulated NO release in a dose and time-dependent manner. Application of IHP inhibited shear stress induced NO release but did not alter NO release from chondrocytes not exposed to shear stress. Shear stress induced NO or addition of an NO donor (sodium nitroprusside) was associated with decreased mRNA signal levels for the cartilage matrix proteins, aggrecan, and type II collagen. Intermittent hydrostatic pressure blocked the inhibitory effects of sodium nitroprusside but did not alter the inhibitory effects of shear stress on cartilage macromolecule gene expression. Our data show that shear stress and IHP differentially alter chondrocyte metabolism and suggest that a balance of effects between different loading forces preserve cartilage extracellular matrix in vivo.

Measurement of /sup 14/C emission rates from a pressurized heavy water reactor

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

Joshi, M.L.; Ramamirtham, B.; Soman, S.D.

Carbon-14 is produced in pressurized heavy water reactors (PHWR), mainly as an activation product in the fuel. It is also produced in the heavy water used as the primary coolant and moderator, and is produced in the air in the annular space between the pressure tube and calandria tubes as well as in the free space in the calandria vault. The production rates in different systems of a PHWR are calculated on the basis of design parameters. During a period of 3 y, /sup 14/C released through the gaseous route has been measured at Rajasthan Atomic Power Station, Kota, India,more » a PHWR unit. These releases have been found to be mainly /sup 14/CO/sub 2/. This reduced form of /sup 14/C is less than 5% of the releases. The normalized releases of /sup 14/C have a geometric mean of 5.17 TBq GWe-1 y-1 and a geometric standard deviation of 1.52. The /sup 14/C present in the form of carbonates in liquid effluents has also been measured and is 0.14% of the gaseous releases.« less

Investigation of CO2 release pressures in pipeline cracks

NASA Astrophysics Data System (ADS)

Gorenz, Paul; Herzog, Nicoleta; Egbers, Christoph

2013-04-01

The CCS (Carbon Capture and Storage) technology can prevent or reduce the emissions of carbon dioxide. The main idea of this technology is the segregation and collection of CO2 from facilities with a high emission of that greenhouse gas, i.e. power plants which burn fossil fuels. To segregate CO2 from the exhaust gas the power plant must be upgraded. Up to now there are three possible procedures to segregate the carbon dioxide with different advantages and disadvantages. After segregation the carbon dioxide will be transported by pipeline to a subsurface storage location. As CO2 is at normal conditions (1013,25 Pa; 20 °C) in a gaseous phase state it must be set under high pressure to enter denser phase states to make a more efficient pipeline transport possible. Normally the carbon dioxide is set into the liquid or supercritical phase state by compressor stations which compress the gas up to 15 MPa. The pressure drop makes booster stations along the pipeline necessary which keep the CO2 in a dens phase state. Depending on the compression pressure CO2 can be transported over 300km without any booster station. The goal of this work is the investigation of release pressures in pipeline cracks. The high pressurised pipeline system consists of different parts with different failure probabilities. In most cases corrosion or obsolescence is the reason for pipeline damages. In case of a crack CO2 will escape from the pipeline and disperse into the atmosphere. Due to its nature CO2 can remain unattended for a long time. There are some studies of the CO2 dispersion process, e.g. Mazzoldi et al. (2007, 2008 and 2011) and Wang et al. (2008), but with different assumptions concerning the pipeline release pressures. To give an idea of realistic release pressures investigations with the CFD tool OpenFOAM were carried out and are presented within this work. To cover such a scenario with an accidental release of carbon dioxide a pipeline section with different diameters and leakage release holes were modelled. This pipeline section is 10m long with the leakage hole in the middle. Additionally a small environment subdomain is simulated around the crack. For computation a multiphase solver was utilised. In a first step incompressible and isothermal fluids with no phase change were assumed.

The pressure-induced, lactose-dependent changes in the composition and size of casein micelles.

PubMed

Wang, Pengjie; Jin, Shaoming; Guo, Huiyuan; Zhao, Liang; Ren, Fazheng

2015-04-15

The effects of lactose on the changes in the composition and size of casein micelles induced by high-pressure treatment and the related mechanism of action were investigated. Dispersions of ultracentrifuged casein micelle pellets with 0-10% (w/v) lactose were subjected to high pressure (400 MPa) at 20 °C for 40 min. The results indicated that the level of non-sedimentable caseins was positively related to the amount of lactose added prior to pressure treatment, and negatively correlated to the size. A mechanism for the pressure-induced, lactose-dependent changes in the casein micelles is proposed. Lactose inhibits the hydrophobic interactions between the micellar fragments during or after pressure release, through the hydrophilic layer formed by their hydrogen bonds around the micellar fragments. In addition, lactose does not favour the association between calcium and the casein aggregates after pressure release. Due to these two functions, lactose inhibited the formation of larger micelles after pressure treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Observations and theory of the AMPTE magnetotail barium releases

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Roussel-Dupre, R. A.; Pongratz, M. B.; Haerendel, G.; Valenzuela, A.

1987-01-01

The barium releases in the magnetotail during the Active Magnetospheric Particle Tracer Explorers (AMPTE) operation were monitored by ground-based imagers and by instruments on the Ion Release Module. After each release, the data show the formation of a structured diamagnetic cavity. The cavity grows until the dynamic pressure of the expanding ions balances the magnetic pressure on its surface. The magnetic field inside the cavity is zero. The barium ions collect on the surface of the cavity, producing a shell. Plasma irregularities form along magnetic field lines draped over the surface of the cavity. The scale size of the irregularities is nearly equal to the thickness of the shell. The evolution and structuring of the diamagnetic cavity are modeled using magnetohydrodynamics theory.

An alternating pressure sequence proposal for an air-cell cushion for preventing pressure ulcers.

PubMed

Arias, Sandra; Cardiel, Eladio; Rogeli, Pablo; Mori, Taketoshi; Nakagami, Gojiro; Noguchi, Hiroshi; Sanada, Hiromi

2014-01-01

The distribution and release of pressure on ischial regions are two important parameters for evaluating the effectiveness of a cushion; especially the release of pressure over time on ischial tuberosities, which is significant for preventing pressure ulcers. The aim of this work is to evaluate the effect on interface pressure through the application of a proposed alternating pressure sequence for an air-cell cushion. Six healthy volunteers were asked to sit on the air cell cushion, in static and alternating modes, as well as on a typical foam cushion for 12 minutes. Interface pressure was monitored with a matrix sensor system. Interface pressure values on ischial tuberosities, user contact area and pressure distribution were analyzed. Results showed that IP on IT tends to increase in both foam and static cushions, while in alternating cushion IP on IT tends to decrease. User contact area was significantly larger in alternating cushion than in static or foam cushions. Moreover, there is a better pressure re-distribution with alternating cushion than with the other cushions. The goal of the alternating sequence is to redistribute pressure and stimulate the ischial regions in order to promote blood flow and prevent pressure occurring in wheelchair users.

ATP is released from rabbit urinary bladder epithelial cells by hydrostatic pressure changes--a possible sensory mechanism?

PubMed Central

Ferguson, D R; Kennedy, I; Burton, T J

1997-01-01

1. The responses of rabbit urinary bladder to hydrostatic pressure changes and to electrical stimulation have been investigated using both the Ussing chamber and a superfusion apparatus. These experiments enabled us to monitor changes in both ionic transport across the tissue and cellular ATP release from it. 2. The urinary bladder of the rabbit maintains an electrical potential difference across its wall as a result largely of active sodium transport from the urinary (mucosal) to the serosal surface. 3. Small hydrostatic pressure differences produced by removal of bathing fluid from one side of the tissue caused reproducible changes in both potential difference and short-circuit current. The magnitude of these changes increases as the volume of fluid removed increases. 3. Amiloride on the mucosal (urinary), but not the serosal, surface of the membrane reduces the transepithelial potential difference and short-circuit current with an IC50 of 300 nM. Amiloride reduces the size of, but does not abolish, transepithelial potential changes caused by alterations in hydrostatic pressure. 4. Field electrical stimulation of strips of bladder tissue produces a reproducible release of ATP. Such release was demonstrated to occur largely from urothelial cells and is apparently non-vesicular as it increases in the absence of calcium and is not abolished by tetrodotoxin. 5. It is proposed that ATP is released from the urothelium as a sensory mediator for the degree of distension of the rabbit urinary bladder and other sensory modalities. PMID:9423189

Strain Measurement during Stress Rupture of Composite Over-Wrapped Pressure Vessel with Fiber Bragg Gratings Sensors

NASA Technical Reports Server (NTRS)

Banks, Curtis E.; Grant, Joseph; Russell, Sam; Arnett, Shawn

2008-01-01

Fiber optic Bragg gratings were used to measure strain fields during Stress Rupture (SSM) test of Kevlar Composite Over-Wrapped Pressure Vessels (COPV). The sensors were embedded under the over-wrapped attached to the liner released from the Kevlar and attached to the Kevlar released from the liner. Additional sensors (foil gages and fiber bragg gratings) were surface mounted on the COPY liner.

Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites.

PubMed

Shaikh, Sohel; Birdi, Anil; Qutubuddin, Syed; Lakatosh, Eric; Baskaran, Harihara

2007-12-01

Polydimethyl siloxane (PDMS) based pressure sensitive adhesives (PSA) incorporating organo-clays at different loadings were fabricated via solution casting. Partially exfoliated nanocomposites were obtained for the hydroxyl terminated PDMS in ethyl acetate solvent as determined by X-ray diffraction and atomic force microscopy. Drug release studies showed that the initial burst release was substantially reduced and the drug release could be controlled by the addition of organo-clay. Shear strength and shear adhesion failure temperature (SAFT) measurements indicated substantial improvement in adhesive properties of the PSA nanocomposite adhesives. Shear strength showed more than 200% improvement at the lower clay loadings and the SAFT increased by about 21% due to the reinforcement provided by the nano-dispersed clay platelets. It was found that by optimizing the level of the organosilicate additive to the polymer matrix, superior control over drug release kinetics and simultaneous improvements in adhesive properties could be attained for a transdermal PSA formulation.

Post-Explosion Tracer Gas Study in Fractured Granite

NASA Astrophysics Data System (ADS)

Avendano, S.; Horne, M.; Herrera, C.; Person, M. A.; Gorman, E.; Stroujkova, A. F.; Gomez-Velez, J. D.

2017-12-01

Radioactive noble gas detection at suspected underground nuclear test sites is the only proven way to confirm that a nuclear test has occurred. However, the migration of gas effluent through fracture networks is still poorly understood. A pilot field study of the gas migration through rock damaged by explosions was conducted in a rock quarry in New Hampshire in the summer of 2017. Tracer gas (SF6), used as a proxy for the noble gas, was released into a cavity created by an explosion (63 kg of TNT at a depth of 13 m) conducted during the summer of 2016. The upper 5 m of borehole were grouted with stainless steel tubing sealed in the concrete and the gas was pumped through the tubing. Before the gas release, we conducted a series of geophysical and hydrologic tests: a pump test, several slug tests, a salt tracer release in two boreholes, and TEM and ERT surveys. Pressure and electrical conductivity transducers were placed in the surrounding boreholes to monitor the pressure changes and tracer arrival during the pumping. The results of the pump test show that the rock is well connected and has high permeability. Interestingly, the injection of gas resulted in a substantial increase of the local hydraulic conductivity, as evidenced by slug test results before and after injection. The pressure changes in the surrounding boreholes were also monitored during the gas release. We observed gas breakthrough immediately after the release. During the first minute after injection, a pressure wave was observed in two boreholes suggestive of inertial effects and hydraulic fracturing after gas release. The concentrations observed at each monitoring site are consistent with the pump testing. The results of this study will be used in our upcoming experiments and to test detailed mathematical models.

Hugoniot and release measurements in diamond shocked up to 26 Mbar [Hugoniot and release measurements in diamond shocked up to 25 Mbar

DOE PAGES

Gregor, M. C.; Fratanduono, D. E.; McCoy, C. A.; ...

2017-04-26

The equation of state of carbon at extreme pressures is of interest to studies of planetary ice giants and white dwarfs and to inertial con nement fusion (ICF) because diamond is used as an ablator material at the National Ignition Facility (NIF). Knowledge of both the high-pressure shock and release responses of diamond are needed to accurately model an ICF implosion and design ignition targets. This article presents Hugoniot and release data for both single-crystal diamond and the high-density carbon (HDC), comprised of nanometer-scale grains, used as a NIF ablator. Experiments were performed at the Omega Laser Facility where diamondmore » was shock-compressed to multimegabar pressures and then released into reference materials with known Hugoniots (quartz, polystyrene, silica aerogel, and liquid deuterium). Impedance matching between diamond and the standards provided the data to constrain diamond release models. Hugoniot data were obtained by impedance matching with a quartz standard and results indicate that the HDC, which is ultrananocrystalline and ~4% less dense, has a sti er Hugoniot as compared to single-crystal diamond. Accuracy of the HDC data were improved using a non-steady waves correction [D. E. Fratanduono et al., J. Appl. Phys. 116, 033517 (2014)] to determine shock velocity pro les in the opaque HDC samples.« less

40 CFR 265.1054 - Standards: Pressure relief devices in gas/vapor service.

Code of Federal Regulations, 2010 CFR

2010-07-01

... gas/vapor service. 265.1054 Section 265.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... TREATMENT, STORAGE, AND DISPOSAL FACILITIES Air Emission Standards for Equipment Leaks § 265.1054 Standards: Pressure relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief...

Relationship between propagule pressure and colonization pressure in invasion ecology: a test with ships' ballast.

PubMed

Briski, Elizabeta; Bailey, Sarah A; Casas-Monroy, Oscar; DiBacco, Claudio; Kaczmarska, Irena; Levings, Colin; MacGillivary, Michael L; McKindsey, Christopher W; Nasmith, Leslie E; Parenteau, Marie; Piercey, Grace E; Rochon, André; Roy, Suzanne; Simard, Nathalie; Villac, Maria C; Weise, Andréa M; MacIsaac, Hugh J

2012-08-07

Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms, we collected 333 ballast water and sediment samples to investigate the relationship between propagule and colonization pressure for a variety of diverse taxonomic groups (diatoms, dinoflagellates and invertebrates). We also reviewed the scientific literature to compare the number of species transported by ships to those reported in nature. Here, we show that even though ships transport nearly entire local communities, a strong relationship between propagule and colonization pressure exists only for dinoflagellates. Our study provides evidence that colonization pressure of invertebrates and diatoms may fluctuate widely irrespective of propagule pressure. We suggest that the lack of correspondence is explained by reduced uptake of invertebrates into the transport vector and the sensitivity of invertebrates and diatoms to selective pressures during transportation. Selection during transportation is initially evident through decreases in propagule pressure, followed by decreased colonization pressure in the most sensitive taxa.

Relationship between propagule pressure and colonization pressure in invasion ecology: a test with ships' ballast

PubMed Central

Briski, Elizabeta; Bailey, Sarah A.; Casas-Monroy, Oscar; DiBacco, Claudio; Kaczmarska, Irena; Levings, Colin; MacGillivary, Michael L.; McKindsey, Christopher W.; Nasmith, Leslie E.; Parenteau, Marie; Piercey, Grace E.; Rochon, André; Roy, Suzanne; Simard, Nathalie; Villac, Maria C.; Weise, Andréa M.; MacIsaac, Hugh J.

2012-01-01

Increasing empirical evidence indicates the number of released individuals (i.e. propagule pressure) and number of released species (i.e. colonization pressure) are key determinants of the number of species that successfully invade new habitats. In view of these relationships, and the possibility that ships transport whole communities of organisms, we collected 333 ballast water and sediment samples to investigate the relationship between propagule and colonization pressure for a variety of diverse taxonomic groups (diatoms, dinoflagellates and invertebrates). We also reviewed the scientific literature to compare the number of species transported by ships to those reported in nature. Here, we show that even though ships transport nearly entire local communities, a strong relationship between propagule and colonization pressure exists only for dinoflagellates. Our study provides evidence that colonization pressure of invertebrates and diatoms may fluctuate widely irrespective of propagule pressure. We suggest that the lack of correspondence is explained by reduced uptake of invertebrates into the transport vector and the sensitivity of invertebrates and diatoms to selective pressures during transportation. Selection during transportation is initially evident through decreases in propagule pressure, followed by decreased colonization pressure in the most sensitive taxa. PMID:22456877

Effects of shock-breakout pressure on ejection of micron-scale material from shocked tin surfaces

NASA Astrophysics Data System (ADS)

Zellner, M. B.; Grover, M.; Hammerberg, J. E.; Hixson, R. S.; Iverson, A. J.; Macrum, G. S.; Morley, K. B.; Obst, A. W.; Olson, R. T.; Payton, J. R.; Rigg, P. A.; Routley, N.; Stevens, G. D.; Turley, W. D.; Veeser, L.; Buttler, W. T.

2007-07-01

This effort investigates the relation between ejecta production and shock-breakout pressure (PSB) for Sn shocked with a Taylor shockwave (unsupported) to pressures near the solid-on-release/partial melt-on-release phase transition region. The shockwaves were created by detonation of high explosive (HE) PBX-9501 on the front side of Sn coupons. Ejecta production at the backside or free side of the Sn coupons was characterized through use of piezoelectric pins, optical shadowgraphy, x-ray attenuation radiography, and optical-heterodyne velocimetry. Ejecta velocities, dynamic volume densities, and areal densities were then correlated with the shock-breakout pressure of Sn surfaces characterized by roughness average of Ra=16 μin or Ra=32 μin.

Advanced Technical Data Study

DTIC Science & Technology

1975-01-29

will shut down automatically when condenser high pressure causes Pressure Limit Control high pressure switch to release. Press START switch (3...power cable (1) from facility pow- er. Troubleshoot cooling unit, for HI-LOW pressure switch repeated cutout. Refer to AGE ECU Cooling Unit...acti- vate when loss of air flow oc- curred, the pressure switch (3) failed to open circuit. Adjust or replace pressure switch . Refer to

Differential Stability of Dimeric and Monomeric Cytochrome c Oxidase Exposed to Elevated Hydrostatic Pressure†

PubMed Central

Staničová, Jana; Sedlák, Erik; Musatov, Andrej; Robinson, Neal C.

2007-01-01

Detergent-solubilized dimeric and monomeric cytochrome c oxidase (CcO) have significantly different quaternary stability when exposed to 2−3 kbar of hydrostatic pressure. Dimeric, dodecyl maltoside-solubilized cytochrome c oxidase is very resistant to elevated hydrostatic pressure with almost no perturbation of its quaternary structure or functional activity after release of pressure. In contrast to the stability of dimeric CcO, 3 kbar of hydrostatic pressure triggers multiple structural and functional alterations within monomeric cytochrome c oxidase. The perturbations are either irreversible or slowly reversible since they persist after the release of high pressure. Therefore, standard biochemical analytical procedures could be used to quantify the pressure-induced changes after the release of hydrostatic pressure. The electron transport activity of monomeric cytochrome c oxidase decreases by as much as 60% after exposure to 3 kbar of hydrostatic pressure. The irreversible loss of activity occurs in a time- and pressure-dependent manner. Coincident with the activity loss is a sequential dissociation of four subunits as detected by sedimentation velocity, high-performance ion-exchange chromatography, and reversed-phase and SDS–PAGE subunit analysis. Subunits VIa and VIb are the first to dissociate followed by subunits III and VIIa. Removal of subunits VIa and VIb prior to pressurization makes the resulting 11-subunit form of CcO even more sensitive to elevated hydrostatic pressure than monomeric CcO containing all 13 subunits. However, dimeric CcO, in which the association of VIa and VIb is stabilized, is not susceptible to pressure-induced inactivation. We conclude that dissociation of subunit III and/or VIIa must be responsible for pressure-induced inactivation of CcO since VIa and VIb can be removed from monomeric CcO without significant activity loss. These results are the first to clearly demonstrate an important structural role for the dimeric form of cytochrome c oxidase, i.e., stabilization of its quaternary structure. PMID:17530783

Evaluation of mucoadhesive potential of gum cordia, an anionic polysaccharide.

PubMed

Ahuja, Munish; Kumar, Suresh; Kumar, Ashok

2013-04-01

The study involves mucoadhesive evaluation by formulating buccal discs using fluconazole as the model drug. The effect of compression pressure and gum cordia/lactose ratio on the ex vivo bioadhesion time and in vitro release of fluconazole was optimized using central composite experimental design. It was observed that the response ex vivo bioadhesion time was affected significantly by the proportion of gum cordia in the buccal discs while the in vitro release of fluconazole from the buccal discs was influenced significantly by the compression pressure. The optimized batch of buccal discs comprised of gum cordia/lactose - 0.66, fluconazole - 20 mg and was compressed at the pressure of 6600 kg. Further, it provided the ex vivo bioadhesion of 22 h and in vitro release of 80% in 24h. In conclusion, gum cordia is a promising bucoadhesive polymer. Copyright © 2012 Elsevier B.V. All rights reserved.

40 CFR 60.441 - Definitions and symbols.

Code of Federal Regulations, 2010 CFR

2010-07-01

... web. Coating line means any number or combination of adhesive, release, or precoat coating applicators... solids content of the coated adhesive, release, or precoat as measured by Method 24. Flashoff area means... than an adhesive or release is applied to a surface during the production of a pressure sensitive tape...

High pressurized CO2 release CFD calculations from onshore pipeline leakages

NASA Astrophysics Data System (ADS)

Herzog, Nicoleta; Gorenz, Paul; Egbers, Christoph

2013-04-01

Emissions from high pressurized pipelines can be determined on the basis of hydrodynamical and thermophysical calculations of the escaped fluid. If a rupture occurs when CO2 is onshore transported in liquid form there will be initially a large pressure drop in the pipeline, the pressure will fall until the liquid becomes a mixture of saturated vapor/liquid. In the vicinity of the rupture, liquid CO2 will escape and immediately vaporize and expand, some of the liquid will desublimate into dry ice, which will precipitate onto the ground [1, 2]. The period of time taken for a large amount of carbon dioxide to be discharged would be short. Initially CO2 will escape by pushing the overlying soil upwards at an explosion-like speed. After the pressure in the pipe fell the flow profile of the escaping gas will almost be as described for gaseous material transport. The expansion of carbon dioxide will occur at sonic speed and will continue to do so until the pressure ratio between the CO2 and the ambient air is lower than about 1.9 [3]. As a result of the expansion also the temperature of the escaping gas will fall drastically and a cloud of cold gas will form which is then dispersed and slowly mixed with ambient air. The rate of emptying the pipeline is controlled by the pipe cross-section area and the speed of the escaping gas, or by the pressure difference between the pipeline and the atmosphere. Therefore the mass flow will be largest immediately after the accident with an exponential decay in time. In this study a two-phase model is applied to a high pressurized pipeline through which liquid carbon dioxide flows. A leakage is considered to be at different positions along the pipeline and the release pressure is calculated over several parameter ranges. It is also intended to characterize from hydrodynamical point of view the dispersion of released CO2 in the ambient medium by means of CFD simulations which includes multiphase flow treatment. For that a turbulent two-phase CFD model is used to analyze the influence of the jet release pressure and leakage dimension on the harmful gaseous CO2 concentration distances. Mazzoldi A., Hill T., Colls J.J.: CO2 transportation for carbon capture and storage: Sublimation of carbon dioxide from a dry ice bank, Int. J. Greenhouse Gas Control, 2, 210-218 (2008) M. Molag, C. Dam: Modelling of accidental releases from a high pressure CO2 pipelines, Energy Procedia, 4, 2301-2307, (2011) Kruse H., Tekiela M.: Calculating the consequences of a CO2-pipeline rupture, Energy Conversion and Management, 37(68), 1013-1018 (1996)

Fission gas release restrictor for breached fuel rod

DOEpatents

Kadambi, N. Prasad; Tilbrook, Roger W.; Spencer, Daniel R.; Schwallie, Ambrose L.

1986-01-01

In the event of a breach in the cladding of a rod in an operating liquid metal fast breeder reactor, the rapid release of high-pressure gas from the fission gas plenum may result in a gas blanketing of the breached rod and rods adjacent thereto which impairs the heat transfer to the liquid metal coolant. In order to control the release rate of fission gas in the event of a breached rod, the substantial portion of the conventional fission gas plenum is formed as a gas bottle means which includes a gas pervious means in a small portion thereof. During normal reactor operation, as the fission gas pressure gradually increases, the gas pressure interiorly of and exteriorly of the gas bottle means equalizes. In the event of a breach in the cladding, the gas pervious means in the gas bottle means constitutes a sufficient restriction to the rapid flow of gas therethrough that under maximum design pressure differential conditions, the fission gas flow through the breach will not significantly reduce the heat transfer from the affected rod and adjacent rods to the liquid metal heat transfer fluid flowing therebetween.

Relationship between pressure and reaction violence in thermal explosions

NASA Astrophysics Data System (ADS)

Smilowitz, L.; Henson, B. F.; Rodriguez, G.; Remelius, D.; Baca, E.; Oschwald, D.; Suvorova, N.

2017-01-01

Reaction violence of a thermal explosion is determined by the energy release rate of the explosive and the coupling of that energy to the case and surroundings. For the HMX and TATB based secondary high explosives studied, we have observed that temperature controls the time to explosion and pressure controls the final energy release rate subsequent to ignition. Pressure measurements in the thermal explosion regime have been notoriously difficult to make due to the extreme rise in temperature which is also occurring during a thermal explosion. We have utilized several different pressure measurement techniques for several different secondary high explosives. These techniques include commercially available piezoelectric and piezoresistive sensors which we have utilized in the low pressure (sub 30 MPa) range of PBX 9502 thermal explosions, and fiber Bragg grating sensors for the higher pressure range (up to GPa) for PBX9501 experiments. In this talk, we will compare the measurement techniques and discuss the pressures measured for the different formulations studied. Simultaneous x-ray radiography measurements of burn velocity will also be shown and correlations between pressure, burn velocity, and reaction violence will be discussed.

Biomechanical consequences of plantar fascial release or rupture during gait. Part II: alterations in forefoot loading.

PubMed

Sharkey, N A; Donahue, S W; Ferris, L

1999-02-01

With a model using feet from cadavers, we tested the hypothesis that plantar fascial release or rupture alters the loading environment of the forefoot during the latter half of the stance phase of gait. The model simulated the position and loading environment of the foot at two instants: early in terminal stance immediately after heel-off and late in terminal stance just preceding contralateral heel strike. Eight feet were loaded at both positions by simulated plantar flexor contraction, and the distribution of plantar pressure was measured before and after progressive release of the plantar fascia. Strain in the diaphysis of the second metatarsal was also measured, from which the bending moments and axial force imposed on the metatarsal were calculated. Cutting the medial half of the central plantar fascial band significantly increased peak pressure under the metatarsal heads but had little effect on pressures in other regions of the forefoot or on second metatarsal strain and loading. Dividing the entire central band or completely releasing the plantar fascia from the calcaneus had a much greater effect and caused significant shifts in plantar pressure and force from the toes to beneath the metatarsal heads. These shifts were accompanied by significantly increased strain and bending in the second metatarsal. Complete fasciotomy increased the magnitude of strain in the dorsal aspect of the second metatarsal by more than 80%, suggesting that plantar fascial release or rupture accelerates the accumulation of fatigue damage in these bones. Altered forefoot loading may be a potential complication of plantar fasciotomy.

Receptor activated bladder and spinal ATP release in neurally intact and chronic spinal cord injured rats

PubMed Central

Salas, Nilson A.; Somogyi, George T.; Gangitano, David A.; Boone, Timothy B.; Smith, Christopher P.

2009-01-01

Neurally intact (NI) rats and chronic spinal cord injured (SCI) rats were studied to determine how activation of mechanosensory or cholinergic receptors in the bladder urothelium evokes ATP release from afferent terminals in the bladder as well as in the spinal cord. Spinal cord transection was performed at the T9-T10 level 2–3 weeks prior to the experiment and a microdialysis fiber was inserted in the L6-S1 lumbosacral spinal cord. Mechanically evoked (i.e. 10cm/w bladder pressure) ATP release into the bladder lumen was approximately 6.5 fold higher in SCI compared to NI rats (p<0.05). Intravesical carbachol (CCh) induced a significantly greater release of ATP in the bladder from SCI as compared to NI rats (3424.32 ± 1255.57 vs. 613.74 ± 470.44 pmol/ml, respectively, p<0.05). However, ATP release in NI or SCI rats to intravesical CCh was not affected by the muscarinic antagonist atropine (Atr). Spinal release of ATP to bladder stimulation with 10cm/w pressure was 5-fold higher in SCI compared to NI rats (p<0.05). CCh also induced a significantly greater release of spinal ATP in SCI rats compared to controls (4.3 ± 0.9 vs. 0.90 ± 0.15 pmol, p < 0.05). Surprisingly, the percent inhibitory effect of Atr on CCh-induced ATP release was significantly less in SCI as compared to NI rats (49% vs. 89%, respectively). SCI induces a dramatic increase in intravesical pressure and cholinergic receptor evoked bladder and spinal ATP release. Muscarinic receptors do not mediate intravesical CCh induced ATP release into the bladder lumen in NI or SCI rats. In NI rats sensory muscarinic receptors are the predominant mechanism by which CCh induces ATP release from primary afferents within the lumbosacral spinal cord. Following SCI, however, nicotinic or purinergic receptor mechanisms become active, as evidenced by the fact that Atr was only partially effective in inhibiting CCh-induced spinal ATP release. PMID:17067723

Two-tank working gas storage system for heat engine

DOEpatents

Hindes, Clyde J.

1987-01-01

A two-tank working gas supply and pump-down system is coupled to a hot gas engine, such as a Stirling engine. The system has a power control valve for admitting the working gas to the engine when increased power is needed, and for releasing the working gas from the engine when engine power is to be decreased. A compressor pumps the working gas that is released from the engine. Two storage vessels or tanks are provided, one for storing the working gas at a modest pressure (i.e., half maximum pressure), and another for storing the working gas at a higher pressure (i.e., about full engine pressure). Solenoid valves are associated with the gas line to each of the storage vessels, and are selectively actuated to couple the vessels one at a time to the compressor during pumpdown to fill the high-pressure vessel with working gas at high pressure and then to fill the low-pressure vessel with the gas at low pressure. When more power is needed, the solenoid valves first supply the low-pressure gas from the low-pressure vessel to the engine and then supply the high-pressure gas from the high-pressure vessel. The solenoid valves each act as a check-valve when unactuated, and as an open valve when actuated.

Summary of efficiency testing of standard and high-capacity high-efficiency particulate air filters subjected to simulated tornado depressurization and explosive shock waves

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

Smith, P.R.; Gregory, W.S.

1985-04-01

Pressure transients in nuclear facility air cleaning systems can originate from natural phenomena such as tornadoes or from accident-induced explosive blast waves. This study was concerned with the effective efficiency of high-efficiency particulate air (HEPA) filters during pressure surges resulting from simulated tornado and explosion transients. The primary objective of the study was to examine filter efficiencies at pressure levels below the point of structural failure. Both standard and high-capacity 0.61-m by 0.61-m HEPA filters were evaluated, as were several 0.2-m by 0.2-m HEPA filters. For a particular manufacturer, the material release when subjected to tornado transients is the samemore » (per unit area) for both the 0.2-m by 0.2-m and the 0.61-m by 0.61-m filters. For tornado transients, the material release was on the order of micrograms per square meter. When subjecting clean HEPA filters to simulated tornado transients with aerosol entrained in the pressure pulse, all filters tested showed a degradation of filter efficiency. For explosive transients, the material release from preloaded high-capacity filters was as much as 340 g. When preloaded high-capacity filters were subjected to shock waves approximately 50% of the structural limit level, 1 to 2 mg of particulate was released.« less

40 CFR 63.1361 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... pressure relief device. This release can be one release or a series of releases over a short time period... reduces the mass of HAP emitted to the air. The equipment may consist of an individual device or a series... do not occur simultaneously in a batch operation. A batch process consists of a series of batch...

Shock, release and reshock of PBX 9502: experiments and modeling

NASA Astrophysics Data System (ADS)

Aslam, Tariq; Gustavsen, Richard; Whitworh, Nicholas; Menikoff, Ralph; Tarver, Craig; Handley, Caroline; Bartram, Brian

2017-06-01

We examine shock, release and reshock into the tri-amino-tri-nitro-benzene (TATB) based explosive PBX 9502 (95% TATB, 5% Kel-F 800) from both an experimental and modeling point of view. The experiments are performed on the 2-stage light gas gun at Los Alamos National Laboratory and are composed of a multi-layered impactor impinging on PBX 9502 backed by a polymethylmethacrylate window. The objective is to initially shock the PBX 9502 in the 7 GPa range (too weak to start significant reaction), then allow a rarefaction fan to release the material to a lower pressure/temperature state. Following this release, a strong second shock will recompress the PBX. If the rarefaction fan releases the PBX to a very low pressure, the ensuing second shock can increase the entropy and temperature substantially more than in previous double-shock experiments without an intermediate release. Predictions from a variety of reactive burn models (AWSD, CREST, Ignition and Growth, SURF) demonstrate significantly different behaviors and thus the experiments are an excellent validation test of the models, and may suggest improvements for subsequent modeling efforts.

High-pressure phase transitions, amorphization, and crystallization behaviors in Bi2Se3.

PubMed

Zhao, Jinggeng; Liu, Haozhe; Ehm, Lars; Dong, Dawei; Chen, Zhiqiang; Gu, Genda

2013-03-27

The phase transition, amorphization, and crystallization behaviors of the topological insulator bismuth selenide (Bi2Se3) were discovered by performing in situ high-pressure angle-dispersive x-ray diffraction experiments during an increasing, decreasing, and recycling pressure process. In the compression process, Bi2Se3 transforms from the original rhombohedral structure (phase I(A)) to a monoclinic structure (phase II) at about 10.4 GPa, and further to a body-centered tetragonal structure (phase III) at about 24.5 GPa. When releasing pressure to ambient conditions after the complete transformation from phase II to III, Bi2Se3 becomes an amorphous solid (AM). In the relaxation process from this amorphous state, Bi2Se3 starts crystallizing into an orthorhombic structure (phase I(B)) about five hours after releasing the pressure to ambient. A review of the pressure-induced phase transition behaviors of A2B3-type materials composed from the V and VI group elements is presented.

Early cessation of pressure garment therapy results in scar contraction and thickening

PubMed Central

DeBruler, Danielle M.; Zbinden, Jacob C.; Baumann, Molly E.; Blackstone, Britani N.; Malara, Megan M.; Bailey, J. Kevin

2018-01-01

Pressure garment therapy is often prescribed to improve scar properties following full-thickness burn injuries. Pressure garment therapy is generally recommended for long periods of time following injury (1–2 years), though it is plagued by extremely low patient compliance. The goal of this study was to examine the effects of early cessation of pressure garment therapy on scar properties. Full-thickness burn injuries were created along the dorsum of red Duroc pigs. The burn eschar was excised and wound sites autografted with split-thickness skin. Scars were treated with pressure garments within 1 week of injury and pressure was maintained for either 29 weeks (continuous pressure) or for 17 weeks followed by cessation of pressure for an additional 12 weeks (pressure released); scars receiving no treatment served as controls. Scars that underwent pressure garment therapy were significantly smoother and less contracted with decreased scar height compared to control scars at 17 weeks. These benefits were maintained in the continuous pressure group until week 29. In the pressure released group, grafts significantly contracted and became more raised, harder and rougher after the therapy was discontinued. Pressure cessation also resulted in large changes in collagen fiber orientation and increases in collagen fiber thickness. The results suggest that pressure garment therapy effectively improves scar properties following severe burn injury; however, early cessation of the therapy results in substantial loss of these improvements. PMID:29897933

Early cessation of pressure garment therapy results in scar contraction and thickening.

PubMed

DeBruler, Danielle M; Zbinden, Jacob C; Baumann, Molly E; Blackstone, Britani N; Malara, Megan M; Bailey, J Kevin; Supp, Dorothy M; Powell, Heather M

2018-01-01

Pressure garment therapy is often prescribed to improve scar properties following full-thickness burn injuries. Pressure garment therapy is generally recommended for long periods of time following injury (1-2 years), though it is plagued by extremely low patient compliance. The goal of this study was to examine the effects of early cessation of pressure garment therapy on scar properties. Full-thickness burn injuries were created along the dorsum of red Duroc pigs. The burn eschar was excised and wound sites autografted with split-thickness skin. Scars were treated with pressure garments within 1 week of injury and pressure was maintained for either 29 weeks (continuous pressure) or for 17 weeks followed by cessation of pressure for an additional 12 weeks (pressure released); scars receiving no treatment served as controls. Scars that underwent pressure garment therapy were significantly smoother and less contracted with decreased scar height compared to control scars at 17 weeks. These benefits were maintained in the continuous pressure group until week 29. In the pressure released group, grafts significantly contracted and became more raised, harder and rougher after the therapy was discontinued. Pressure cessation also resulted in large changes in collagen fiber orientation and increases in collagen fiber thickness. The results suggest that pressure garment therapy effectively improves scar properties following severe burn injury; however, early cessation of the therapy results in substantial loss of these improvements.

Slide release mechanism. [for space shuttle orbiter/external tank connection device

NASA Technical Reports Server (NTRS)

Bunker, J. W.; Ritchie, R. S. (Inventor)

1985-01-01

A releasable support device is described which is comprised of a hollow body with a sleeve extending transversely there-through for receiving the end of a support shank. A slider-latch, optionally lubricated, extends through side recesses in the sleeve to straddle the shank, respectively, in latched and released positions. The slider-latch is slid from its latched to its unlatched position by a pressure squib whereupon a spring or other pressure means pushes the shank out of the sleeve. At the same time, a follower element is lodged in and closed the hole in the body wall from which the shank was discharged. The mechanism was designed for the shuttle orbiter/external tank connection device.

Thermodynamics and vibrational study of hydrogenated carbon nanotubes: A DFT study

NASA Astrophysics Data System (ADS)

Khalil, Rana M. Arif; Hussain, Fayyaz; Rana, Anwar Manzoor; Imran, Muhammad

2018-02-01

Thermodynamic stability of the hydrogenated carbon nanotubes has been explored in the chemisorption limit. Statistical physics and density functional theory calculations have been used to predict hydrogen release temperatures at standard pressure in zigzag and armchair carbon nanotubes. It is found that hydrogen release temperatures decrease with increase in diameters of hydrogenated zigzag carbon nanotubes (CNTs) but opposite trend is noted in armchair CNTs at standard pressure of 1 bar. The smaller diameter hydrogenated zigzag CNTs have large values of hydrogen release temperature due to the stability of Csbnd H bonds. The vibrational density of states for hydrogenated carbon nanotubes have been calculated to confirm the Csbnd H stretching mode caused by sp3 hybridization.

Renin blood test

MedlinePlus

... pressure , your doctor may order a renin and aldosterone test to help determine the cause of your ... due to: Adrenal glands that release too much aldosterone hormone ( hyperaldosteronism ) High blood pressure that is salt- ...

Controlled Release in Transdermal Pressure Sensitive Adhesives using Organosilicate Nanocomposites

PubMed Central

Shaikh, Sohel; Birdi, Anil; Qutubuddin, Syed; Lakatosh, Eric; Baskaran, Harihara

2010-01-01

Polydimethyl siloxane (PDMS) based pressure sensitive adhesives (PSA) incorporating organo-clays at different loadings were fabricated via solution casting. Partially exfoliated nanocomposites were obtained for the hydroxyl terminated PDMS in ethyl acetate solvent as determined by X-ray diffraction (XRD) and atomic force microscopy (AFM). Drug release studies showed that the initial burst release was substantially reduced and the drug release could be controlled by the addition of organo-clay. Shear strength and shear adhesion failure temperature (SAFT) measurements indicated substantial improvement in adhesive properties of the PSA nanocomposite adhesives. Shear strength showed more than 200 % improvement at the lower clay loadings and the SAFT increased by about 21% due to the reinforcement provided by the nano-dispersed clay platelets. It was found that by optimizing the level of the organosilicate additive to the polymer matrix, superior control over drug release kinetics and simultaneous improvements in adhesive properties could be attained for a transdermal PSA formulation. PMID:17786555

On the condition of UO2 nuclear fuel irradiated in a PWR to a burn-up in excess of 110 MWd/kgHM

NASA Astrophysics Data System (ADS)

Restani, R.; Horvath, M.; Goll, W.; Bertsch, J.; Gavillet, D.; Hermann, A.; Martin, M.; Walker, C. T.

2016-12-01

Post-irradiation examination results are presented for UO2 fuel from a PWR fuel rod that had been irradiated to an average burn-up of 105 MWd/kgHM and showed high fission gas release of 42%. The radial distribution of xenon and the partitioning of fission gas between bubbles and the fuel matrix was investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron probe microanalysis. It is concluded that release from the fuel at intermediate radial positions was mainly responsible for the high fission gas release. In this region thermal release had occurred from the high burn-up structure (HBS) at some point after the sixth irradiation cycle. The LA-ICP-MS results indicate that gas release had also occurred from the HBS in the vicinity of the pellet periphery. It is shown that the gas pressure in the HBS pores is well below the pressure that the fuel can sustain.

Elevated hydrostatic pressure triggers release of OPA1 and cytochrome C, and induces apoptotic cell death in differentiated RGC-5 cells

PubMed Central

Kim, Keun-Young; Lindsey, James D.; Angert, Mila; Patel, Ankur; Scott, Ray T.; Liu, Quan; Crowston, Jonathan G.; Ellisman, Mark H.; Perkins, Guy A.; Weinreb, Robert N.

2009-01-01

Purpose This study was conducted to determine whether elevated hydrostatic pressure alters mitochondrial structure, triggers release of the dynamin-related guanosine triphosphatase (GTPase) optic atrophy type 1 (OPA1) or cytochrome C from mitochondria, alters OPA1 gene expression, and can directly induce apoptotic cell death in cultured retinal ganglion cell (RGC)-5 cells. Methods Differentiated RGC-5 cells were exposed to 30 mmHg for three days in a pressurized incubator. As a control, differentiated RGC-5 cell cultures were incubated simultaneously in a conventional incubator. Live RGC-5 cells were then labeled with MitoTracker Red and mitochondrial morphology was assessed by fluorescence microscopy. Mitochondrial structural changes were also assessed by electron microscopy and three-dimenstional (3D) electron microscope tomography. OPA1 mRNA was measured by Taqman quantitative PCR. The cellular distribution of OPA1 protein and cytochrome C was assessed by immunocytochemistry and western blot. Caspase-3 activation was examined by western blot. Apoptotic cell death was evaluated by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. Results Mitochondrial fission, characterized by the conversion of tubular fused mitochondria into isolated small organelles, was triggered after three days exposure to elevated hydrostatic pressure. Electron microscopy confirmed the fission and noted no changes to mitochondrial architecture, nor outer membrane rupture. Electron microscope tomography showed that elevated pressure depleted mitochondrial cristae content by fourfold. Elevated hydrostatic pressure increased OPA1 gene expression by 35±14% on day 2, but reduced expression by 36±4% on day 3. Total OPA1 protein content was not changed on day 2 or 3. However, pressure treatment induced release of OPA1 and cytochrome C from mitochondria to the cytoplasm. Elevated pressure also activated caspase-3 and induced apoptotic cell death. Conclusions Elevated hydrostatic pressure triggered mitochondrial changes including mitochondrial fission and abnormal cristae depletion, alteration of OPA1 gene expression, and release of OPA1 and cytochrome C into the cytoplasm before the onset of apoptotic cell death in differentiated RGC-5 cells. These results suggest that sustained moderate pressure elevation may directly damage RGC integrity by injuring mitochondria. PMID:19169378

The study on the entrapment efficiency and in vitro release of puerarin submicron emulsion.

PubMed

Yue, Peng-Fei; Lu, Xiu-Yun; Zhang, Zeng-Zhu; Yuan, Hai-Long; Zhu, Wei-Feng; Zheng, Qin; Yang, Ming

2009-01-01

The entrapment efficiency (EE) and release in vitro are very important physicochemical characteristics of puerarin submicron emulsion (SME). In this paper, the performance of ultrafiltration (UF), ultracentrifugation (UC), and microdialysis (MD) for determining the EE of SME were evaluated, respectively. The release study in vitro of puerarin from SME was studied by using MD and pressure UF technology. The EE of SME was 86.5%, 72.8%, and 55.8% as determined by MD, UF, and UC, respectively. MD was not suitable for EE measurements of puerarin submicron oil droplet, which could only determine the total EE of submicron oil droplet and liposomes micelles, but it could be applied to determine the amount of free drug in SMEs. Although UC was the fastest and simplest to use, its results were the least reliable. UF was still the relatively accurate method for EE determination of puerarin SME. The release of puerarin SME could be evaluated by using MD and pressure UF, but MD seemed to be more suitable for the release study of puerarin emulsion. The drug release from puerarin SME at three drug concentrations was initially rapid, but reached a plateau value within 30 min. Drug release of puerarin from the SME occurred via burst release.

Simplified modeling of blast waves from metalized heterogeneous explosives

NASA Astrophysics Data System (ADS)

Zarei, Z.; Frost, D. L.

2011-09-01

The detonation of a metalized explosive generates a complex multiphase flow field. Modeling the subsequent propagation of the blast front requires a detailed knowledge of the metal particle dynamics and reaction rate. Given the uncertainties in modeling these phenomena, a much simpler, 1D compressible flow model is used to illustrate the general effects of secondary energy release due to particle reaction on the blast front properties. If the total energy release is held constant, the blast pressure and impulse are primarily dependent on the following parameters: the proportion of secondary energy released due to afterburning, the rate of energy release, the location the secondary energy release begins, and the range over which it occurs. Releasing the total energy over a longer time period in general reduces the peak blast overpressure at a given distance. However, secondary energy release reduces the rate of decay of the shock pressure, increases the local gas temperature and hence increases the velocity of the secondary shock front. As a result, for certain values of the above parameters, the peak blast impulse may be increased by a factor of about two in a region near the charge. The largest augmentation to the near-field peak impulse results when the secondary energy is released immediately behind the shock front rather than uniformly within the combustion products.

Comparison of the autoregulatory mechanisms between middle cerebral artery and ophthalmic artery after thigh cuff deflation in healthy subjects.

PubMed

Kolodjaschna, Julia; Berisha, Fatmire; Lung, Solveig; Schima, Heinrich; Polska, Elzbieta; Schmetterer, Leopold

2005-02-01

To compare dynamic autoregulation in the middle cerebral artery (MCA) and the ophthalmic artery (OA) after a step decrease in systemic blood pressure. Eighteen healthy male young subjects were studied. Ultrasound parameters and systemic blood pressures were recorded in each subject before, during, and after a step decrease in blood pressure. Continuous blood pressure recordings were made with a finger plethysmograph system, and flow velocities in the MCA and the OA were continuously measured with Doppler ultrasound. Large bilateral thigh cuffs were inflated and a pressure approximately 20 mm Hg above peak systolic blood pressure was maintained for 3 minutes. A decrease in blood pressure was induced by rapid deflation of bilateral thigh cuffs. Experiments were performed separately for the OA and the MCA. Systemic blood pressure showed a step decrease immediately after thigh cuff release (9%-15%) and returned to baseline 7 to 10 pulse cycles later. Flow velocities in the MCA returned to baseline earlier than systemic blood pressure, indicating peripheral vasodilatation, with a maximum of five to six pulse cycles after the blood pressure decrease. By contrast, flow velocities in the OA returned to baseline later than systemic blood pressure, reflecting peripheral vasoconstriction with a maximum 10 to 15 pulse cycles after cuff release. There was a statistically significant difference in the time course of the resistance changes in the two selected arteries after thigh cuff release (P < 0.001). The results of the present study suggest substantial differences in the autoregulatory behavior of the vascular beds peripheral to the MCA and the OA. Results in the MCA would be compatible with either metabolic or myogenic vasodilatation, whereas the results in the OA could reflect sympathetic vasoconstriction. Further studies are needed to support this hypothesis. The thigh cuff technique may represent an interesting approach to the study of autoregulation in patients with ocular vascular disease.

21 CFR 177.1430 - Isobutylene-butene copolymers.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) Maximum bromine value 1. Used as release agents in petroleum wax complying with § 178.3710 of this chapter... release coatings on backings or linings for pressure-sensitive adhesive labels complying with § 175.125 of...

Chemical Safety Alert: Hazards of Ammonia Releases at Ammonia Refrigeration Facilities

EPA Pesticide Factsheets

Anhydrous ammonia is used as a refrigerant in mechanical compression systems, often liquefied under pressure which increases exposure risk due to potential for rapid release into the air as a toxic gas.

21 CFR 868.5935 - External negative pressure ventilator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung, cuirass) is a device chamber that is intended to support a patient's ventilation by alternately applying and releasing external negative pressure over the diaphragm and upper trunk of the patient. (b) Classification. Class II...

Percutaneous Soft Tissue Release for Treating Chronic Recurrent Myofascial Pain Associated with Lateral Epicondylitis: 6 Case Studies

PubMed Central

Lin, Ming-Ta; Chou, Li-Wei; Chen, Hsin-Shui; Kao, Mu-Jung

2012-01-01

Objective. The purpose of this pilot study is to investigate the effectiveness of the percutaneous soft tissue release for the treatment of recurrent myofascial pain in the forearm due to recurrent lateral epicondylitis. Methods. Six patients with chronic recurrent pain in the forearm with myofascial trigger points (MTrPs) due to chronic lateral epicondylitis were treated with percutaneous soft tissue release of Lin's technique. Pain intensity (measured with a numerical pain rating scale), pressure pain threshold (measured with a pressure algometer), and grasping strength (measured with a hand dynamometer) were assessed before, immediately after, and 3 months and 12 months after the treatment. Results. For every individual case, the pain intensity was significantly reduced (P < 0.01) and the pressure pain threshold and the grasping strength were significantly increased (P < 0.01) immediately after the treatment. This significant effectiveness lasts for at least one year. Conclusions. It is suggested that percutaneous soft tissue release can be used for treating chronic recurrent lateral epicondylitis to avoid recurrence, if other treatment, such as oral anti-inflammatory medicine, physical therapy, or local steroid injection, cannot control the recurrent pain. PMID:23243428

Model Scramjet Inlet Unstart Induced by Mass Addition and Heat Release

NASA Astrophysics Data System (ADS)

Im, Seong-Kyun; Baccarella, Damiano; McGann, Brendan; Liu, Qili; Wermer, Lydiy; Do, Hyungrok

2015-11-01

The inlet unstart phenomena in a model scramjet are investigated at an arc-heated hypersonic wind tunnel. The unstart induced by nitrogen or ethylene jets at low or high enthalpy Mach 4.5 freestream flow conditions are compared. The jet injection pressurizes the downstream flow by mass addition and flow blockage. In case of the ethylene jet injection, heat release from combustion increases the backpressure further. Time-resolved schlieren imaging is performed at the jet and the lip of the model inlet to visualize the flow features during unstart. High frequency pressure measurements are used to provide information on pressure fluctuation at the scramjet wall. In both of the mass and heat release driven unstart cases, it is observed that there are similar flow transient and quasi-steady behaviors of unstart shockwave system during the unstart processes. Combustion driven unstart induces severe oscillatory flow motions of the jet and the unstart shock at the lip of the scramjet inlet after the completion of the unstart process, while the unstarted flow induced by solely mass addition remains relatively steady. The discrepancies between the processes of mass and heat release driven unstart are explained by flow choking mechanism.

Modeling PBX 9501 overdriven release experiments

NASA Astrophysics Data System (ADS)

Tang, P. K.; Hixson, R. S.; Fritz, J. N.

1998-07-01

We show the failure of the standard Jones-Wilkins-Lee (JWL) equation of state (EOS) in modeling the overdriven release experiments of PBX 9501. The deficiency can be tracked back to inability of the same EOS in matching the shock pressure and the sound speed on the Hugoniot in the hydrodynamic regime above the Chapman-Jouguet pressure. After adding correction terms to the principal isentrope of the standard JWL EOS, we are able to remedy this shortcoming and the simulation is successful.

Modeling PBX 9501 overdriven release experiments

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

Tang, P.K.; Hixson, R.S.; Fritz, J.N.

1998-07-01

We show the failure of the standard Jones-Wilkins-Lee (JWL) equation of state (EOS) in modeling the overdriven release experiments of PBX 9501. The deficiency can be tracked back to inability of the same EOS in matching the shock pressure and the sound speed on the Hugoniot in the hydrodynamic regime above the Chapman-Jouguet pressure. After adding correction terms to the principal isentrope of the standard JWL EOS, we are able to remedy this shortcoming and the simulation is successful. {copyright} {ital 1998 American Institute of Physics.}

Modeling PBX 9501 Overdriven Release Experiments

NASA Astrophysics Data System (ADS)

Tang, P. K.; Hixson, R. S.; Fritz, J. N.

1997-07-01

We show the failure of the standard Jones-Wilkins-Lee (JWL) equation of state (EOS) in modeling the overdriven release experiments of PBX 9501. The deficiency can be traced back to the inability of the same EOS in matching the shock pressure and the sound speed on the Hugoniot in the hydrodynamic regime above the Chapman-Jouguet pressure. After adding correction terms to the principal isentrope of the standard JWL EOS, we are able to remedy this shortcoming and the simulation is successful.

Prevention of Over-Pressurization During Combustion in a Sealed Chamber

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Niehaus, Justin E.; Olson, Sandra L.; Dietrich, Daniel L.; Ruff, Gary A.; Johnston, Michael C.

2012-01-01

The combustion of flammable material in a sealed chamber invariably leads to an initial pressure rise in the volume. The pressure rise is due to the increase in the total number of gaseous moles (condensed fuel plus chamber oxygen combining to form gaseous carbon dioxide and water vapor) and, most importantly, the temperature rise of the gas in the chamber. Though the rise in temperature and pressure would reduce with time after flame extinguishment due to the absorption of heat by the walls and contents of the sealed spacecraft, the initial pressure rise from a fire, if large enough, could lead to a vehicle over-pressure and the release of gas through the pressure relief valve. This paper presents a simple lumped-parameter model of the pressure rise in a sealed chamber resulting from the heat release during combustion. The transient model considers the increase in gaseous moles due to combustion, and heat transfer to the chamber walls by convection and radiation and to the fuel-sample holder by conduction, as a function of the burning rate of the material. The results of the model are compared to the pressure rise in an experimental chamber during flame spread tests as well as to the pressure falloff after flame extinguishment. The experiments involve flame spread over thin solid fuel samples. Estimates of the heat release rate profiles for input to the model come from the assumed stoichiometric burning of the fuel along with the observed flame spread behavior. The sensitivity of the model to predict maximum chamber pressure is determined with respect to the uncertainties in input parameters. Model predictions are also presented for the pressure profile anticipated in the Fire Safety-1 experiment, a material flammability and fire safety experiment proposed for the European Space Agency (ESA) Automated Transfer Vehicle (ATV). Computations are done for a range of scenarios including various initial pressures and sample sizes. Based on these results, various mitigation approaches are suggested to prevent vehicle over-pressurization and help guide the definition of the space experiment.

Intraspinal release of immunoreactive calcitonin gene-related peptide during development of inflammation in the joint in vivo--a study with antibody microprobes in cat and rat.

PubMed

Schaible, H G; Freudenberger, U; Neugebauer, V; Stiller, R U

1994-10-01

This study addressed the intraspinal release of immunoreactive calcitonin gene-related peptide in vivo during mechanical stimulation of the normal joint and during the development of an acute experimental inflammation in the knee joint in the anaesthetized cat (spinalized) and rat (not spinalized). Release was assessed using microprobes coated with antibody to calcitonin gene-related peptide; inhibition of binding of [125I]calcitonin gene-related peptide to these probes following insertion into the spinal cord is equated with intraspinal release of the endogenous (unlabelled) peptide. Probes inserted prior to inflammation showed marked basal release of immunoreactive calcitonin gene-related peptide in the dorsal horn with a maximum in the superficial dorsal horn in the absence of intentional stimulation. The pattern of binding of [125I]calcitonin gene-related peptide was not or only minimally changed by innocuous mechanical stimuli (flexion of and innocuous pressure to the knee in the cat and innocuous pressure to the knee of the rat) but was significantly altered by electrical stimulation of the tibial nerve in the cat (sufficient to excite unmyelinated afferent fibres), indicating release of the peptide by the latter stimulus. During the first hours of the development of an experimental inflammation in the knee joint induced by intra-articular injections of kaolin and carrageenan, the pattern of binding of [125I]calcitonin gene-related peptide changed. In the cat, the level of immunoreactive calcitonin gene-related peptide showed a persistent increase in the gray matter and up to the surface of the cord and release was slightly increased by innocuous stimuli. In the rat, increased levels of immunoreactive calcitonin gene-related peptide were mainly seen in the superficial and deep dorsal horn during innocuous pressure (this stimulus did not evoke release of the peptide prior to inflammation) and noxious pressure applied to the injected knee, whereas increased basal levels were only observed at later stages. These data show that the development of an acute experimental inflammation in the joint is associated with an enhancement of the intraspinal release of immunoreactive calcitonin gene-related peptide. Since the changes in the release were noted at an early stage, within the first hours, they could contribute to the generation of inflammation-evoked changes of the responsiveness of spinal cord neurons and hence to the mechanisms inducing inflammatory pain.

Na2S, a fast-releasing H2S donor, given as suppository lowers blood pressure in rats.

PubMed

Tomasova, Lenka; Drapala, Adrian; Jurkowska, Halina; Wróbel, Maria; Ufnal, Marcin

2017-10-01

Hydrogen sulfide (H 2 S) is involved in blood pressure control. The available slow-releasing H 2 S-donors are poorly soluble in water and their ability to release H 2 S in biologically relevant amounts under physiological conditions is questionable. Therefore, new slow-releasing donors or new experimental approaches to fast-releasing H 2 S donors are needed. Hemodynamics and ECG were recorded in male, anesthetized Wistar Kyoto rats (WKY) and in Spontaneously hypertensive rats (SHR) at baseline and after: 1) intravenous (iv) infusion of vehicle or Na 2 S; 2) administration of vehicle suppositories or Na 2 S suppositories. Intravenously administered vehicle and vehicle suppositories did not affect mean arterial blood pressure (MABP) and heart rate (HR). Na 2 S administered iv caused a significant, but transient (2-5min) decrease in MABP. Na 2 S suppositories produced a dose-dependent hypotensive response that lasted ∼45min in WKY and ∼75-80min in SHR. It was accompanied by a decrease in HR in WKY, and an increase in HR in SHR. Na 2 S suppositories did not produce a significant change in corrected QT, an indicator of cardiotoxicity. Na 2 S suppositories increased blood level of thiosulfates, products of H 2 S oxidation. Na 2 S administered in suppositories exerts a prolonged hypotensive effect in rats, with no apparent cardiotoxic effect. SHR and WKY differ in hemodynamic response to the H 2 S donor. Suppository formulation of fast-releasing H 2 S donors may be useful in research, if a reference slow-releasing H 2 S donor is not available. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Fundamental Study of Disposition and Release of Methane in a Shale Gas Reservoir

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

Wang, Yifeng; Xiong, Yongliang; Criscenti, Louise J.

The recent boom in shale gas production through hydrofracturing has reshaped the energy production landscape in the United States. Wellbore production rates vary greatly among the wells within a single field and decline rapidly with time, thus bring up a serious concern with the sustainability of shale gas production. Shale gas production starts with creating a fracture network by injecting a pressurized fluid in a wellbore. The induced fractures are then held open by proppant particles. During production, gas releases from the mudstone matrix, migrates to nearby fractures, and ultimately reaches a production wellbore. Given the relatively high permeability ofmore » the induced fractures, gas release and migration in low-permeability shale matrix is likely to be a limiting step for long-term wellbore production. Therefore, a clear understanding of the underlying mechanisms of methane disposition and release in shale matrix is crucial for the development of new technologies to maximize gas production and recovery. Shale is a natural nanocomposite material with distinct characteristics of nanometer-scale pore sizes, extremely low permeability, high clay contents, significant amounts of organic carbon, and large spatial heterogeneities. Our work has shown that nanopore confinement plays an important role in methane disposition and release in shale matrix. Using molecular simulations, we show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~ 30 - 47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. The long-term production decline appears controlled by the second stage of gas release. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3 - 35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. We have successfully established experimental capabilities for measuring gas sorption and desorption on shale and model materials under a wide range of physical and chemical conditions. Both low and high pressure measurements show significant sorption of CH 4 and CO 2 onto clays, implying that methane adsorbed on clay minerals could contribute a significant portion of gas-in-place in an unconventional reservoir. We have also studied the potential impact of the interaction of shale with hydrofracking fluid on gas sorption. We have found that the CH 4-CO 2 sorption capacity for the reacted sample is systematically lower (by a factor of ~2) than that for the unreacted (raw) sample. This difference in sorption capacity may result from a mineralogical or surface chemistry change of the shale sample induced by fluid-rock interaction. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs.« less

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

Luna, R. E.

This paper provides a simple model for estimating the release of respirable aerosols resulting from an attack on a spent fuel cask using a high energy density device (HEDD). Two primary experiments have provided data on potential releases from spent fuel casks under HEDD attack. Sandia National Laboratories (SNL) conducted the first in the early 1980's and the second was sponsored by Gessellshaft fur Anlagen- and Reaktorsicherheit (GRS) in Germany and conducted in France in 1994. Both used surrogate spent fuel assemblies in real casks. The SNL experiments used un-pressurized fuel pin assemblies in a single element cask while themore » GRS tests used pressurized fuel pin assemblies in a 9-element cask. Data from the two test programs is reasonably consistent, given the differences in the experiments, but the use of the test data for prediction of releases resulting from HEDD attack requires a method for accounting for the effects of pin pressurization release and the ratio of pin plenum gas release to cask free volume (VR). To account for the effects of VR and to link the two data sources, a simple model has been developed that uses both the SNL data and the GRS data as well as recent test data on aerosols produced in experiments with single pellets subjected to HEDD effects conducted under the aegis of the International Consortium's Working Group on Sabotage of Transport and Storage Casks (WGSTSC). (authors)« less

Release of Micronized Copper Particles from Pressure ...

EPA Pesticide Factsheets

Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about the exposure of humans as well as the environment to the particles. Two common pathways of exposure, leaching during contact with water and transfer during physical contact, were investigated to gage potential human and environmental risk during intended use of the product. Characterization, leaching tests, and wipe tests were conducted on two representative formulations of micronized copper PTL (micronized copper azole or MCA) to quantify the levels of copper present in the treated material and the amount of copper released during use as well as to determine the form (particle or ion) of the copper after it was released. Additionally, an ionized copper pressure treated wood (alkaline copper azole or ACA) was tested for comparison. The characterization showed that copper carbonate is the primary particle form in the MCA treated wood, but other forms are also present, particularly in the MCA-1 formulation, which contained a large amount of organically complexed copper. Microscopy showed that MCA-1 contained particles roughly half the size of MCA-2. The leaching results indicate that mostly (> ~95%) ionic copper is released from the MCA wood and that the particulate copper that was released is attached to cellulose and not free in solution. A sma

Large Scale Patterns of Antimicrofouling Defenses in the Hard Coral Pocillopora verrucosa in an Environmental Gradient along the Saudi Arabian Coast of the Red Sea

PubMed Central

Wahl, Martin; Al Sofyani, Abdulmohsin; Saha, Mahasweta; Kruse, Inken; Lenz, Mark; Sawall, Yvonne

2014-01-01

Large scale patterns of ecologically relevant traits may help identify drivers of their variability and conditions beneficial or adverse to the expression of these traits. Antimicrofouling defenses in scleractinian corals regulate the establishment of the associated biofilm as well as the risks of infection. The Saudi Arabian Red Sea coast features a pronounced thermal and nutritional gradient including regions and seasons with potentially stressful conditions to corals. Assessing the patterns of antimicrofouling defenses across the Red Sea may hint at the susceptibility of corals to global change. We investigated microfouling pressure as well as the relative strength of 2 alternative antimicrofouling defenses (chemical antisettlement activity, mucus release) along the pronounced environmental gradient along the Saudi Arabian Red Sea coast in 2 successive years. Microfouling pressure was exceptionally low along most of the coast but sharply increased at the southernmost sites. Mucus release correlated with temperature. Chemical defense tended to anti-correlate with mucus release. As a result, the combined action of mucus release and chemical antimicrofouling defense seemed to warrant sufficient defense against microbes along the entire coast. In the future, however, we expect enhanced energetic strain on corals when warming and/or eutrophication lead to higher bacterial fouling pressure and a shift towards putatively more costly defense by mucus release. PMID:25485603

Impacts of an Ammonia Leak on the Cabin Atmosphere of the International Space Station

NASA Technical Reports Server (NTRS)

Duchesne, Stephanie M.; Sweterlitsch, Jeff J.; Son, Chang H.; Perry, Jay L.

2011-01-01

Toxic chemical release into the cabin atmosphere is one of the three major emergency scenarios identified on the International Space Station (ISS). The release of anhydrous ammonia, the coolant used in the U.S. On-orbit Segment (USOS) External Active Thermal Control Subsystem (EATCS), into the ISS cabin atmosphere is one of the most serious toxic chemical release cases identified on board ISS. The USOS Thermal Control System (TCS) includes an Internal Thermal Control Subsystem (ITCS) water loop and an EATCS ammonia loop that transfer heat at the interface heat exchanger (IFHX). Failure modes exist that could cause a breach within the IFHX. This breach would result in high pressure ammonia from the EATCS flowing into the lower pressure ITCS water loop. As the pressure builds in the ITCS loop, it is likely that the gas trap, which has the lowest maximum design pressure within the ITCS, would burst and cause ammonia to enter the ISS atmosphere. It is crucial to first characterize the release of ammonia into the ISS atmosphere in order to develop methods to properly mitigate the environmental risk. This paper will document the methods used to characterize an ammonia leak into the ISS cabin atmosphere. A mathematical model of the leak was first developed in order to define the flow of ammonia into the ISS cabin atmosphere based on a series of IFHX rupture cases. Computational Fluid Dynamics (CFD) methods were then used to model the dispersion of the ammonia throughout the ISS cabin and determine localized effects and ventilation effects on the dispersion of ammonia. Lastly, the capabilities of the current on-orbit systems to remove ammonia were reviewed and scrubbing rates of the ISS systems were defined based on the ammonia release models. With this full characterization of the release of ammonia from the USOS TCS, an appropriate mitigation strategy that includes crew and system emergency response procedures, personal protection equipment use, and atmosphere monitoring and scrubbing hardware can be established.

Impacts of an Ammonia Leak on the Cabin Atmosphere of the International Space Station

NASA Technical Reports Server (NTRS)

Duchesne, Stephanie M.; Sweterlitsch, Jeffrey J.; Son, Chang H.; Perry Jay L.

2012-01-01

Toxic chemical release into the cabin atmosphere is one of the three major emergency scenarios identified on the International Space Station (ISS). The release of anhydrous ammonia, the coolant used in the U.S. On-orbit Segment (USOS) External Active Thermal Control Subsystem (EATCS), into the ISS cabin atmosphere is one of the most serious toxic chemical release cases identified on board ISS. The USOS Thermal Control System (TCS) includes an Internal Thermal Control Subsystem (ITCS) water loop and an EATCS ammonia loop that transfer heat at the interface heat exchanger (IFHX). Failure modes exist that could cause a breach within the IFHX. This breach would result in high pressure ammonia from the EATCS flowing into the lower pressure ITCS water loop. As the pressure builds in the ITCS loop, it is likely that the gas trap, which has the lowest maximum design pressure within the ITCS, would burst and cause ammonia to enter the ISS atmosphere. It is crucial to first characterize the release of ammonia into the ISS atmosphere in order to develop methods to properly mitigate the environmental risk. This paper will document the methods used to characterize an ammonia leak into the ISS cabin atmosphere. A mathematical model of the leak was first developed in order to define the flow of ammonia into the ISS cabin atmosphere based on a series of IFHX rupture cases. Computational Fluid Dynamics (CFD) methods were then used to model the dispersion of the ammonia throughout the ISS cabin and determine localized effects and ventilation effects on the dispersion of ammonia. Lastly, the capabilities of the current on-orbit systems to remove ammonia were reviewed and scrubbing rates of the ISS systems were defined based on the ammonia release models. With this full characterization of the release of ammonia from the USOS TCS, an appropriate mitigation strategy that includes crew and system emergency response procedures, personal protection equipment use, and atmosphere monitoring and scrubbing hardware can be established.

Does Don Fisher's high-pressure manifold model account for phloem transport and resource partitioning?

PubMed Central

Patrick, John W.

2013-01-01

The pressure flow model of phloem transport envisaged by Münch (1930) has gained wide acceptance. Recently, however, the model has been questioned on structural and physiological grounds. For instance, sub-structures of sieve elements may reduce their hydraulic conductances to levels that impede flow rates of phloem sap and observed magnitudes of pressure gradients to drive flow along sieve tubes could be inadequate in tall trees. A variant of the Münch pressure flow model, the high-pressure manifold model of phloem transport introduced by Donald Fisher may serve to reconcile at least some of these questions. To this end, key predicted features of the high-pressure manifold model of phloem transport are evaluated against current knowledge of the physiology of phloem transport. These features include: (1) An absence of significant gradients in axial hydrostatic pressure in sieve elements from collection to release phloem accompanied by transport properties of sieve elements that underpin this outcome; (2) Symplasmic pathways of phloem unloading into sink organs impose a major constraint over bulk flow rates of resources translocated through the source-path-sink system; (3) Hydraulic conductances of plasmodesmata, linking sieve elements with surrounding phloem parenchyma cells, are sufficient to support and also regulate bulk flow rates exiting from sieve elements of release phloem. The review identifies strong circumstantial evidence that resource transport through the source-path-sink system is consistent with the high-pressure manifold model of phloem transport. The analysis then moves to exploring mechanisms that may link demand for resources, by cells of meristematic and expansion/storage sinks, with plasmodesmal conductances of release phloem. The review concludes with a brief discussion of how these mechanisms may offer novel opportunities to enhance crop biomass yields. PMID:23802003

SEMICONDUCTOR TECHNOLOGY Supercritical carbon dioxide process for releasing stuck cantilever beams

NASA Astrophysics Data System (ADS)

Yu, Hui; Chaoqun, Gao; Lei, Wang; Yupeng, Jing

2010-10-01

The multi-SCCO2 (supercritical carbon dioxide) release and dry process based on our specialized SCCO2 semiconductor process equipment is investigated and the releasing mechanism is discussed. The experiment results show that stuck cantilever beams were held up again under SCCO2 high pressure treatment and the repeatability of this process is nearly 100%.

Dispersion of CNG Following a High-Pressure Release

DOT National Transportation Integrated Search

1996-05-01

This report discusses the results of tests to determine the dispersive behavior of compressed natural gas (CNG) when released in enclosed areas such as transit bus facility, and presents the Volpe National Transportation Systems Center's (VNTSC) conc...

40 CFR 264.1054 - Standards: Pressure relief devices in gas/vapor service.

Code of Federal Regulations, 2010 CFR

2010-07-01

... gas/vapor service. 264.1054 Section 264.1054 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE... relief devices in gas/vapor service. (a) Except during pressure releases, each pressure relief device in...

14 CFR 23.365 - Pressurized cabin loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... stress concentrations, must be accounted for. (c) If landings may be made with the cabin pressurized... be designed for the effects of sudden release of pressure in any compartment with external doors or windows. This condition must be investigated for the effects of failure of the largest opening in the...

Feasibility Study of an Earth Melting Penetrator System for Geoprospecting Tunnel Right-of-Ways

DTIC Science & Technology

1978-12-01

anticipated to be negligible or nonexistent. 86. The degree of melt pressure induced fracturing will not be restricted for this design study although analyses...control system would employ a pressure reducing valve to ensure that the pressurizing air pressure is held safely below the fracturing pressure of...provided for the possibility of inadvertent steam or other volatile release from the portal area under high pressure . 6 Table 1 RequIrements Sumnar

Automotive Test Rig Final Design Report. Volume 2. Control System.

DTIC Science & Technology

1986-01-01

Pressure Switch Status P27 Low Brake Release Pressure Switch Status P26 Low Brake...Supply Pressure Switch Status P25 Low Port Charge Pump Pressure Switch Status P24 Low Starboard Charge Pump Pressure Switch Status P23 Hydraulic Filter By...Sensed Switch Status P31 Low Scavenge Pump Pressure Switch Status P30 P37 Signal Return for Computer J21 Not Used J22 P A +24 B Pwr Rtn C Ground C

Fission product release and survivability of UN-kernel LWR TRISO fuel

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

T. M. Besmann; M. K. Ferber; H.-T. Lin

2014-05-01

A thermomechanical assessment of the LWR application of TRISO fuel with UN kernels was performed. Fission product release under operational and transient temperature conditions was determined by extrapolation from fission product recoil calculations and limited data from irradiated UN pellets. Both fission recoil and diffusive release were considered and internal particle pressures computed for both 650 and 800 um diameter kernels as a function of buffer layer thickness. These pressures were used in conjunction with a finite element program to compute the radial and tangential stresses generated within a TRISO particle undergoing burnup. Creep and swelling of the inner andmore » outer pyrolytic carbon layers were included in the analyses. A measure of reliability of the TRISO particle was obtained by computing the probability of survival of the SiC barrier layer and the maximum tensile stress generated in the pyrolytic carbon layers from internal pressure and thermomechanics of the layers. These reliability estimates were obtained as functions of the kernel diameter, buffer layer thickness, and pyrolytic carbon layer thickness. The value of the probability of survival at the end of irradiation was inversely proportional to the maximum pressure.« less

Building an Efficient Model for Afterburn Energy Release

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

Alves, S; Kuhl, A; Najjar, F

2012-02-03

Many explosives will release additional energy after detonation as the detonation products mix with the ambient environment. This additional energy release, referred to as afterburn, is due to combustion of undetonated fuel with ambient oxygen. While the detonation energy release occurs on a time scale of microseconds, the afterburn energy release occurs on a time scale of milliseconds with a potentially varying energy release rate depending upon the local temperature and pressure. This afterburn energy release is not accounted for in typical equations of state, such as the Jones-Wilkins-Lee (JWL) model, used for modeling the detonation of explosives. Here wemore » construct a straightforward and efficient approach, based on experiments and theory, to account for this additional energy release in a way that is tractable for large finite element fluid-structure problems. Barometric calorimeter experiments have been executed in both nitrogen and air environments to investigate the characteristics of afterburn for C-4 and other materials. These tests, which provide pressure time histories, along with theoretical and analytical solutions provide an engineering basis for modeling afterburn with numerical hydrocodes. It is toward this end that we have constructed a modified JWL equation of state to account for afterburn effects on the response of structures to blast. The modified equation of state includes a two phase afterburn energy release to represent variations in the energy release rate and an afterburn energy cutoff to account for partial reaction of the undetonated fuel.« less

Toxic industrial chemical (TIC) source emissions modeling for pressurized liquefied gases

NASA Astrophysics Data System (ADS)

Britter, Rex; Weil, Jeffrey; Leung, Joseph; Hanna, Steven

2011-01-01

The objective of this article is to report current toxic industrial chemical (TIC) source emissions formulas appropriate for use in atmospheric comprehensive risk assessment models so as to represent state-of-the-art knowledge. The focus is on high-priority scenarios, including two-phase releases of pressurized liquefied gases such as chlorine from rail cars. The total mass released and the release duration are major parameters, as well as the velocity, thermodynamic state, and amount and droplet sizes of imbedded aerosols of the material at the exit of the rupture, which are required as inputs to the subsequent jet and dispersion modeling. Because of the many possible release scenarios that could develop, a suite of model equations has been described. These allow for gas, two-phase or liquid storage and release through ruptures of various types including sharp-edged and "pipe-like" ruptures. Model equations for jet depressurization and phase change due to flashing are available. Consideration of the importance of vessel response to a rupture is introduced. The breakup of the jet into fine droplets and their subsequent suspension and evaporation, or rainout is still a significant uncertainty in the overall modeling process. The recommended models are evaluated with data from various TIC field experiments, in particular recent experiments with pressurized liquefied gases. It is found that there is typically a factor of two error in models compared with research-grade observations of mass flow rates. However, biases are present in models' estimates of the droplet size distributions resulting from flashing releases.

Evidence for pressure-release melting beneath magmatic arcs from basalt at Galunggung, Indonesia

USGS Publications Warehouse

Sisson, T.W.; Bronto, S.

1998-01-01

The melting of peridotite in the mantle wedge above subduction zones is generally believed to involve hydrous fluids derived from the subducting slab. But if mantle peridotite is upwelling within the wedge, melting due to pressure release could also contribute to magma production. Here we present measurements of the volatile content of primitive magmas from Galunggung volcano in the Indonesian are which indicate that these magmas were derived from the pressure-release melting of hot mantle peridotite. The samples that we have analysed consist of mafic glass inclusions in high-magnesium basalts. The inclusions contain uniformly low H2O concentrations (0.21-0.38 wt%), yet relatively high levels of CO2 (up to 750 p.p.m.) indicating that the low H2O concentrations are primary and not due to degassing of the magma. Results from previous anhydrous melting experiments on a chemically similar Aleutian basalts indicate that the Galunggung high-magnesium basalts were last in equilibrium with peridotite at ~1,320 ??C and 1.2 GPa. These high temperatures at shallow sub-crustal levels (about 300-600 ??C hotter than predicted by geodynamic models), combined with the production of nearly H2O- free basaltic melts, provide strong evidence that pressure-release melting due to upwelling in the sub-are mantle has taken place. Regional low- potassium and low-H2O (ref. 5) basalts found in the Cascade are indicate that such upwelling-induced melting can be widespread.

Notes about the Armenia earthquake, 7 December 1988

USGS Publications Warehouse

Kerr, R. A.

1989-01-01

Whenever the plates moving beneath Armenia interlock, pressure builds. The stress increases, the pressure continues to climb and finally there is a fracture-a sudden release of energy we know as an earthquake.  

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

Mehl, M; Kukkadapu, G; Kumar, K

The use of gasoline in homogeneous charge compression ignition engines (HCCI) and in duel fuel diesel - gasoline engines, has increased the need to understand its compression ignition processes under engine-like conditions. These processes need to be studied under well-controlled conditions in order to quantify low temperature heat release and to provide fundamental validation data for chemical kinetic models. With this in mind, an experimental campaign has been undertaken in a rapid compression machine (RCM) to measure the ignition of gasoline mixtures over a wide range of compression temperatures and for different compression pressures. By measuring the pressure history duringmore » ignition, information on the first stage ignition (when observed) and second stage ignition are captured along with information on the phasing of the heat release. Heat release processes during ignition are important because gasoline is known to exhibit low temperature heat release, intermediate temperature heat release and high temperature heat release. In an HCCI engine, the occurrence of low-temperature and intermediate-temperature heat release can be exploited to obtain higher load operation and has become a topic of much interest for engine researchers. Consequently, it is important to understand these processes under well-controlled conditions. A four-component gasoline surrogate model (including n-heptane, iso-octane, toluene, and 2-pentene) has been developed to simulate real gasolines. An appropriate surrogate mixture of the four components has been developed to simulate the specific gasoline used in the RCM experiments. This chemical kinetic surrogate model was then used to simulate the RCM experimental results for real gasoline. The experimental and modeling results covered ultra-lean to stoichiometric mixtures, compressed temperatures of 640-950 K, and compression pressures of 20 and 40 bar. The agreement between the experiments and model is encouraging in terms of first-stage (when observed) and second-stage ignition delay times and of heat release rate. The experimental and computational results are used to gain insight into low and intermediate temperature processes during gasoline ignition.« less

High speed 2-dimensional temperature measurements of nanothermite composites: Probing thermal vs. Gas generation effects

NASA Astrophysics Data System (ADS)

Jacob, Rohit J.; Kline, Dylan J.; Zachariah, Michael R.

2018-03-01

This work investigates the reaction dynamics of metastable intermolecular composites through high speed spectrometry, pressure measurements, and high-speed color camera pyrometry. Eight mixtures including Al/CuO and Al/Fe2O3/xWO3 (x being the oxidizer mol. %) were reacted in a constant volume pressure cell as a means of tuning gas release and adiabatic temperature. A direct correlation between gas release, peak pressure, and pressurization rate was observed, but it did not correlate with temperature. When WO3 was varied as part of the stoichiometric oxidizer content, it was found that Al/Fe2O3/70% WO3 achieved the highest pressures and shortest burn time despite a fairly constant temperature between mixtures, suggesting an interplay between the endothermic Fe2O3 decomposition and the higher adiabatic flame temperature sustained by the Al/WO3 reaction in the composite. It is proposed that the lower ignition temperature of Al/WO3 leads to the initiation of the composite and its higher flame temperature enhances the gasification of Fe2O3, thus improving advection and propagation as part of a feedback loop that drives the reaction. Direct evidence of such gas release promoting reactivity was obtained through high speed pyrometry videos of the reaction. These results set the stage for nanoenergetic materials that can be tuned for specific applications through carefully chosen oxidizer mixtures.

Role of construction debris in release of copper, chromium, and arsenic from treated wood structures

Treesearch

Stan T. Lebow; Steven A. Halverson; Jeffrey J. Morrell; John Simonsen

Recent research on the release of wood preservatives from treated wood used in sensitive environments has not considered the potential contribution from construction residues. This study sought to develop leaching rate data for small construction debris and compare those to the release rate from treated wood itself. Western hemlock boards were pressure treated with...

Endocrine Tumors Causing Arterial Hypertension: Pathophysiological Mechanisms and Clinical Implications.

PubMed

Buonacera, Agata; Stancanelli, Benedetta; Malatino, Lorenzo

2017-09-01

Some tumors are a relatively rare and amendable cause of hypertension, often associated with a higher cardiovascular morbidity and mortality, as compared with that of both general population and patients with essential hypertension. This worse prognosis is not entirely related to blood pressure increase, because the release of substances from the tumor can directly influence blood pressure behavior. Diagnostic approach is challenging and needs a deep knowledge of the different neuro-hormonal and genetic mechanisms determining blood pressure increase. Surgical tumor removal can, but not always, cause blood pressure normalization, depending on how early was tumor detection, since a long-standing history of hypertension is often associated with a much weaker effect on blood pressure. Moreover, target organ damage can be affected by the substances themselves released by the tumors as well as by tumor removal. In this review we consider the phenotype and genetic features of patients with tumor-induced hypertension and focus on their diagnostic work-up.

Development of matrix-based theophylline sustained-release microtablets.

PubMed

Rey, H; Wagner, K G; Wehrlé, P; Schmidt, P C

2000-01-01

Microtablets containing high theophylline content (from 60% to 80%) based on a Eudragit RS PO matrix were produced on a rotary tablet press. The influence of the compaction pressure, the plasticizer content used for the granulation of theophylline particles, and the amount of theophylline on the drug release were investigated. The effects of surface area and the addition of magnesium stearate as a hydrophobic agent on the drug release were studied. The storage stabilities of the release rate at room temperature and at 50 degrees C were also determined. Dissolution profiles expressed as percentage of theophylline dissolved were obtained over 8 hr in 900 ml of purified water at 37 degrees C and 75 rpm. It was observed that the compaction pressure (from 200 MPa to 250 MPa) had no effect on the theophylline release. The use of triethyl citrate (TEC) as a plasticizer in the granulation of theophylline enhanced the physical properties of the microtablets. Theophylline content in the range 60% to 80% did not affect the drug release. The theophylline release obtained was a function of the quotient surface area/tablet weight and therefore was dependent on the tablet diameter. To reduce the dissolution rates, magnesium stearate was added in a concentration up to 50% of the matrix material. Tablets of this hydrophobic formulation fulfilled the requirements of USP 23 for theophylline sustained-release preparations. Storage at room temperature for 3 months and at 50 degrees C for 2 months showed no significant influence on the theophylline release.

Hydrophilic thermoplastic polyurethanes for the manufacturing of highly dosed oral sustained release matrices via hot melt extrusion and injection molding.

PubMed

Verstraete, G; Van Renterghem, J; Van Bockstal, P J; Kasmi, S; De Geest, B G; De Beer, T; Remon, J P; Vervaet, C

2016-06-15

Hydrophilic aliphatic thermoplastic polyurethane (Tecophilic™ grades) matrices for high drug loaded oral sustained release dosage forms were formulated via hot melt extrusion/injection molding (HME/IM). Drugs with different aqueous solubility (diprophylline, theophylline and acetaminophen) were processed and their influence on the release kinetics was investigated. Moreover, the effect of Tecophilic™ grade, HME/IM process temperature, extrusion speed, drug load, injection pressure and post-injection pressure on in vitro release kinetics was evaluated for all model drugs. (1)H NMR spectroscopy indicated that all grades have different soft segment/hard segment ratios, allowing different water uptake capacities and thus different release kinetics. Processing temperature of the different Tecophilic™ grades was successfully predicted by using SEC and rheology. Tecophilic™ grades SP60D60, SP93A100 and TG2000 had a lower processing temperature than other grades and were further evaluated for the production of IM tablets. During HME/IM drug loads up to 70% (w/w) were achieved. In addition, Raman mapping and (M)DSC results confirmed the homogenous distribution of mainly crystalline API in all polymer matrices. Besides, hydrophilic TPU based formulations allowed complete and sustained release kinetics without using release modifiers. As release kinetics were mainly affected by drug load and the length of the PEO soft segment, this polymer platform offers a versatile formulation strategy to adjust the release rate of drugs with different aqueous solubility. Copyright © 2016 Elsevier B.V. All rights reserved.

Sulfur removal and comminution of carbonaceous material

DOEpatents

Narain, Nand K.; Ruether, John A.; Smith, Dennis N.

1988-01-01

Finely divided, clean coal or other carbonaceous material is provided by forming a slurry of coarse coal in aqueous alkali solution and heating the slurry under pressure to above the critical conditions of steam. The supercritical fluid penetrates and is trapped in the porosity of the coal as it swells in a thermoplastic condition at elevated temperature. By a sudden, explosive release of pressure the coal is fractured into finely divided particles with release of sulfur-containing gases and minerals. The finely divided coal is recovered from the minerals for use as a clean coal product.

Miniature stick-packaging--an industrial technology for pre-storage and release of reagents in lab-on-a-chip systems.

PubMed

van Oordt, Thomas; Barb, Yannick; Smetana, Jan; Zengerle, Roland; von Stetten, Felix

2013-08-07

Stick-packaging of goods in tubular-shaped composite-foil pouches has become a popular technology for food and drug packaging. We miniaturized stick-packaging for use in lab-on-a-chip (LOAC) systems to pre-store and on-demand release the liquid and dry reagents in a volume range of 80-500 μl. An integrated frangible seal enables the pressure-controlled release of reagents and simplifies the layout of LOAC systems, thereby making the package a functional microfluidic release unit. The frangible seal is adjusted to defined burst pressures ranging from 20 to 140 kPa. The applied ultrasonic welding process allows the packaging of temperature sensitive reagents. Stick-packs have been successfully tested applying recovery tests (where 99% (STDV = 1%) of 250 μl pre-stored liquid is released), long-term storage tests (where there is loss of only <0.5% for simulated 2 years) and air transport simulation tests. The developed technology enables the storage of a combination of liquid and dry reagents. It is a scalable technology suitable for rapid prototyping and low-cost mass production.

Manipulation of norepinephrine metabolism with yohimbine in the treatment of autonomic failure

NASA Technical Reports Server (NTRS)

Biaggioni, I.; Robertson, R. M.; Robertson, D.

1994-01-01

It has been postulated that alpha 2-adrenergic receptors play a modulatory role in the regulation of blood pressure. Activation of alpha 2-receptors located in the central nervous system results in inhibition of sympathetic tone and decrease of blood pressure. This indeed may be the mechanism of action of central sympatholytic antihypertensives such as alpha-methyldopa. Presynaptic alpha 2-receptors also are found in adrenergic nerve terminals. These receptors act as a negative feedback mechanism by inhibiting the release of norepinephrine. The relevance of alpha 2-adrenergic receptors for blood pressure regulation can be explored with yohimbine, a selective antagonist of these receptors. Yohimbine increases blood pressure in resting normal volunteers. This effect is associated with an increase in both sympathetic nerve activity, reflecting an increase in central sympathetic outflow, and in norepinephrine spillover, reflecting potentiation of the release of norepinephrine from adrenergic nerve terminals. These actions, therefore, underscore the importance of alpha 2-adrenergic receptors for blood pressure regulation even under resting conditions. Patients with autonomic failure, even those with severe sympathetic deprivation, are hypersensitive to the pressor effects of yohimbine. This increased responsiveness can be explained by sensitization of adrenergic receptors, analogous to denervation supersensitivity, and by the lack of autonomic reflexes that would normally buffer any increase in blood pressure. Preliminary studies suggest that the effectiveness of yohimbine in autonomic failure can be enhanced with monoamine oxidase inhibitors. Used in combination, yohimbine increases norepinephrine release, whereas monoamine oxidase inhibitors inhibit its degradation. Therefore, yohimbine is not only a useful tool in the study of blood pressure regulation, but may offer a therapeutic option in autonomic dysfunction.

Ankle Joint Contact Loads and Displacement With Progressive Syndesmotic Injury.

PubMed

Hunt, Kenneth J; Goeb, Yannick; Behn, Anthony W; Criswell, Braden; Chou, Loretta

2015-09-01

Ligamentous injuries to the distal tibiofibular syndesmosis are predictive of long-term ankle dysfunction. Mild and moderate syndesmotic injuries are difficult to stratify, and the impact of syndesmosis injury on the magnitude and distribution of forces within the ankle joint during athletic activities is unknown. Eight below-knee cadaveric specimens were tested in the intact state and after sequential sectioning of the following ligaments: anterior-inferior tibiofibular, anterior deltoid (1 cm), interosseous/transverse (IOL/TL), posterior-inferior tibiofibular, and whole deltoid. In each condition, specimens were loaded in axial compression to 700 N and then externally rotated to 20 N·m torque. During axial loading and external rotation, both the fibula and the talus rotated significantly after each ligament sectioning as compared to the intact condition. After IOL/TL release, a significant increase in posterior translation of the fibula was observed, although no syndesmotic widening was observed. Mean tibiotalar contact pressure increased significantly after IOL/TL release, and the center of pressure shifted posterolaterally, relative to more stable conditions, after IOL/TL release. There were significant increases in mean contact pressure and peak pressure along with a reduction in contact area with axial loading and external rotation as compared to axial loading alone for all 5 conditions. Significant increases in tibiotalar contact pressures occur when external rotation stresses are added to axial loading. Moderate and severe injuries are associated with a significant increase in mean contact pressure combined with a shift in the center of pressure and rotation of the fibula and talus. Considerable changes in ankle joint kinematics and contact mechanics may explain why moderate syndesmosis injuries take longer to heal and are more likely to develop long-term dysfunction and, potentially, ankle arthritis. © The Author(s) 2015.

OnabotulinumtoxinA significantly attenuates bladder afferent nerve firing and inhibits ATP release from the urothelium.

PubMed

Collins, Valerie M; Daly, Donna M; Liaskos, Marina; McKay, Neil G; Sellers, Donna; Chapple, Christopher; Grundy, David

2013-11-01

To investigate the direct effect of onabotulinumtoxinA (OnaBotA) on bladder afferent nerve activity and release of ATP and acetylcholine (ACh) from the urothelium. Bladder afferent nerve activity was recorded using an in vitro mouse preparation enabling simultaneous recordings of afferent nerve firing and intravesical pressure during bladder distension. Intraluminal and extraluminal ATP, ACh, and nitric oxide (NO) release were measured using the luciferin-luciferase and Amplex(®) Red assays (Molecular Probes, Carlsbad, CA, USA), and fluorometric assay kit, respectively. OnaBotA (2U), was applied intraluminally, during bladder distension, and its effect was monitored for 2 h after application. Whole-nerve activity was analysed to classify the single afferent units responding to physiological (low-threshold [LT] afferent <15 mmHg) and supra-physiological (high-threshold [HT] afferent >15 mmHg) distension pressures. Bladder distension evoked reproducible pressure-dependent increases in afferent nerve firing. After exposure to OnaBotA, both LT and HT afferent units were significantly attenuated. OnaBotA also significantly inhibited ATP release from the urothelium and increased NO release. These data indicate that OnaBotA attenuates the bladder afferent nerves involved in micturition and bladder sensation, suggesting that OnaBotA may exert its clinical effects on urinary urgency and the other symptoms of overactive bladder syndrome through its marked effect on afferent nerves. © 2013 The Authors. BJU International © 2013 BJU International.

Enhanced cell disruption strategy in the release of recombinant hepatitis B surface antigen from Pichia pastoris using response surface methodology

PubMed Central

2012-01-01

Background Cell disruption strategies by high pressure homogenizer for the release of recombinant Hepatitis B surface antigen (HBsAg) from Pichia pastoris expression cells were optimized using response surface methodology (RSM) based on the central composite design (CCD). The factors studied include number of passes, biomass concentration and pulse pressure. Polynomial models were used to correlate the above mentioned factors to project the cell disruption capability and specific protein release of HBsAg from P. pastoris cells. Results The proposed cell disruption strategy consisted of a number of passes set at 20 times, biomass concentration of 7.70 g/L of dry cell weight (DCW) and pulse pressure at 1,029 bar. The optimized cell disruption strategy was shown to increase cell disruption efficiency by 2-fold and 4-fold for specific protein release of HBsAg when compared to glass bead method yielding 75.68% cell disruption rate (CDR) and HBsAg concentration of 29.20 mg/L respectively. Conclusions The model equation generated from RSM on cell disruption of P. pastoris was found adequate to determine the significant factors and its interactions among the process variables and the optimum conditions in releasing HBsAg when validated against a glass bead cell disruption method. The findings from the study can open up a promising strategy for better recovery of HBsAg recombinant protein during downstream processing. PMID:23039947

PPARγ ligands decrease hydrostatic pressure-induced platelet aggregation and proinflammatory activity.

PubMed

Rao, Fang; Yang, Ren-Qiang; Chen, Xiao-Shu; Xu, Jin-Song; Fu, Hui-Min; Su, Hai; Wang, Ling

2014-01-01

Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ). We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg) or increased (120, 180, 240 mmHg) hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa) binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L) was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg). The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs). These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure.

PPARγ Ligands Decrease Hydrostatic Pressure-Induced Platelet Aggregation and Proinflammatory Activity

PubMed Central

Chen, Xiao-Shu; Xu, Jin-Song; Fu, Hui-Min; Su, Hai; Wang, Ling

2014-01-01

Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ). We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg) or increased (120, 180, 240 mmHg) hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa) binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L) was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg). The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs). These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure. PMID:24586940

High-Pressure-Induced Comminution and Recrystallization of CH3 NH3 PbBr3 Nanocrystals as Large Thin Nanoplates.

PubMed

Yin, Tingting; Fang, Yanan; Chong, Wee Kiang; Ming, Koh Teck; Jiang, Shaojie; Li, Xianglin; Kuo, Jer-Lai; Fang, Jiye; Sum, Tze Chien; White, Timothy J; Yan, Jiaxu; Shen, Ze Xiang

2018-01-01

High pressure (HP) can drive the direct sintering of nanoparticle assemblies for Ag/Au, CdSe/PbS nanocrystals (NCs). Instead of direct sintering for the conventional nanocrystals, this study experimentally observes for the first time high-pressure-induced comminution and recrystallization of organic-inorganic hybrid perovskite nanocrystals into highly luminescent nanoplates with a shorter carrier lifetime. Such novel pressure response is attributed to the unique structural nature of hybrid perovskites under high pressure: during the drastic cubic-orthorhombic structural transformation at ≈2 GPa, (301) the crystal plane fully occupied by organic molecules possesses a higher surface energy, triggering the comminution of nanocrystals into nanoslices along such crystal plane. Beyond bulk perovskites, in which pressure-induced modifications on crystal structures and functional properties will disappear after pressure release, the pressure-formed variants, i.e., large (≈100 nm) and thin (<10 nm) perovskite nanoplates, are retained and these exhibit simultaneous photoluminescence emission enhancing (a 15-fold enhancement in the photoluminescence) and carrier lifetime shortening (from ≈18.3 ± 0.8 to ≈7.6 ± 0.5 ns) after releasing of pressure from 11 GPa. This pressure-induced comminution of hybrid perovskite NCs and a subsequent amorphization-recrystallization treatment offer the possibilities of engineering the advanced hybrid perovskites with specific properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pressure-Application Device for Testing Pressure Sensors

NASA Technical Reports Server (NTRS)

2002-01-01

A portable pressure-application device has been designed and built for use in testing and calibrating piezoelectric pressure transducers in the field. The device generates pressure pulses of known amplitude. A pressure pulse (in contradistinction to a steady pressure) is needed because in the presence of a steady pressure, the electrical output of a piezoelectric pressure transducer decays rapidly with time. The device includes a stainless- steel compressed-air-storage cylinder of 500 cu cm volume. A manual hand pump with check valves and a pressure gauge are located at one end of the cylinder. A three-way solenoid valve that controls the release of pressurized air is located at the other end of the cylinder. Power for the device is provided by a 3.7-V cordless-telephone battery. The valve is controlled by means of a pushbutton switch, which activates a 5 V to +/-15 V DC-to-DC converter that powers the solenoid. The outlet of the solenoid valve is connected to the pressure transducer to be tested. Before the solenoid is energized, the transducer to be tested is at atmospheric pressure. When the solenoid is actuated by the push button, pressurized air from inside the cylinder is applied to the transducer. Once the pushbutton is released, the cylinder pressure is removed from the transducer and the pressurized air applied to the transducer is vented, bringing the transducer back to atmospheric pressure. Before this device was used for actual calibration, its accuracy was checked with a NIST (National Institute of Standards and Technology) traceable calibrator and commercially calibrated pressure transducers. This work was done by Wanda Solano of Stennis Space Center and Greg Richardson of Lockheed Martin Corp.

Wellbottom fluid implosion treatment system

DOEpatents

Brieger, Emmet F.

2001-01-01

A system for inducing implosion shock forces on perforation traversing earth formations with fluid pressure where an implosion tool is selected relative to a shut in well pressure and a tubing pressure to have a large and small area piston relationship in a well tool so that at a predetermined tubing pressure the pistons move a sufficient distance to open an implosion valve which permits a sudden release of well fluid pressure into the tubing string and produces an implosion force on the perforations. A pressure gauge on the well tool records tubing pressure and well pressure as a function of time.

Effect of simulated rainfall and weathering on release of preservative elements from CCA treated wood

Treesearch

Stan Lebow; R. Sam Williams; Patricia Lebow

2003-01-01

The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium...

Experimental Study on Ice Forming Process of Cryogenic Liquid Releasing underwater

NASA Astrophysics Data System (ADS)

Zhang, Bin; Wu, Wanqing; Zhang, Xingdong; Zhang, Yi; Zhang, Chuanlin; Zhang, Haoran; Wang, Peng

2017-11-01

Cryogenic liquid releasing into water would be a process combines hyperactive boiling with ice forming. There are still few researches on the experimental study on the environmental conditions for deciding ice forming speed and liquid surviving state. In this paper, to advance our understanding of ice forming deciding factors in the process of LN2 releasing underwater, a visualization experimental system is built. The results show that the pressure difference significantly influences the ice forming speed and liquid surviving distance, which is observed by the experiment and theoretically analysed by Kelvin-Helmholtz instability. Adding nucleating agent is helpful to provide ice nucleus which can accelerate the ice forming speed. Water flowing has some effect on changing pressure difference, which can affect the ice forming speed and liquid surviving distance.

Dissociation of Laboratory-Synthesized Methane Hydrate in Coarse-Grained Sediments by Slow Depressurization

NASA Astrophysics Data System (ADS)

Phillips, S. C.; You, K.; Borgfeldt, T.; Meyer, D.; Dong, T.; Flemings, P. B.

2016-12-01

We performed four dissociation experiments in which experimentally-formed methane hydrate was dissociated via slow, stepwise depressurization, revealing in situ salinity conditions. Overall, these results suggest the occurrence of local pore water freshening around dissociating hydrate in which bulk equilibrium behavior is limited by salt diffusion. Depressurization was performed at a constant confining temperature over 1 to 3 weeks by releasing small volumes of methane gas from the top of a vertically-oriented sample into an inverted graduated cylinder. We identify three distinct regimes of depressurization based on pressure drop behavior: (1) release of free gas down to initial hydrate dissociation at 3.3 MPa in NaBr or 4.64 MPa in NaCl, (2) dissociation of methane hydrate characterized by a slow, logarithmic increase in pressure after each gas release and (3) residual free gas release. Initial hydrate dissociation in NaCl brine at 4.64 MPa corresponds to the phase boundary for hydrate in 9.6 wt% NaCl. In the NaCl experiment, pressure increases of 0.16 MPa while the sample was shut in over 3 days likely correspond to a recovery in salinity of 0.7 wt. %. Salt ions likely diffuse from brine ahead of the hydrate front, based on a length scale for diffusion of NaCl of 6.3 cm for 3 days. In this experiment dissociation at bulk equilibrium is expected to decline from 4.54 to 4.04 MPa; however actual dissociation during 73 gas releases over 15 days, results in a pressure drop from 4.64 to 3.25 MPa. Hydrate samples were formed by injection of methane gas at 1 ºC and 12.24 MPa within a cylinder packed with medium-grained quartz sand and initially saturated in a 7 wt% NaBr or NaCl solution. In two experiments in which the system was thoroughly leak tested, total methane consumed during formation and recovered during depressurization match within 7% indicating this approach to be relatively accurate for determining total methane in experimental or pressure core samples.

WATER LEVEL DRAWDOWN TRIGGERS SYSTEM-WIDE BUBBLE RELEASE FROM RESERVOIR SEDIMENTS

EPA Science Inventory

Reservoirs are an important anthropogenic source of methane and ebullition is a key pathway by which methane stored in reservoir sediments can be released to the atmosphere. Changes in hydrostatic pressure during periods of falling water levels can trigger bubbling events, sugge...

Fail-Safe Pressure Plug

NASA Technical Reports Server (NTRS)

Svejkovsky, Paul A.

1993-01-01

Protective plug resists slowly built-up pressure or automatically releases itself if pressure rises suddenly. Seals out moisture at pressures ranging from 50 micrometers of mercury to 200 pounds per square inch. Designed to seal throat of 38 Reaction Control Thrusters on Space Shuttle protecting internal components from corrosion. Plug conforms to contour of nozzle throat, where O-ring forms pressure seal. After plug inserted, cover attached by use of cover-fitting assembly. Modified versions useful in protecting engines, pumps, reaction vessels, and other industrial equipment during shipment and maintenance.

Finite Element Analysis of Functionally Graded Material to Reduce Crazing in Transparent Armor

DTIC Science & Technology

2015-09-01

Constraints 3 Results 4 Tensile Pressure (psi) 4 Conclusions and Path Forward 5 References 7 Distribution List 9 FIGURES 1 Pressure plot 1 2 3D...Digimat unit cell and 2D plane strain model for ABAQUS 2 3 Control and FGM models 3 4 Boundary conditions 4 5 Pressure results (time = 23.47 µs) 4...6 Pressure results 1 5 7 Pressure results 2 5 UNCLASSIFIED Approved for public release; distribution is unlimited. 1 INTRODUCTION

Portable tester for determining gas content within a core sample

DOEpatents

Garcia, Jr., Fred; Schatzel, Steven J.

1998-01-01

A portable tester is provided for reading and displaying the pressure of a gas released from a rock core sample stored within a sealed container and for taking a sample of the released pressurized gas for chemical analysis thereof for subsequent use in a modified direct method test which determines the volume of gas and specific type of gas contained within the core sample. The portable tester includes a pair of low and high range electrical pressure transducers for detecting a gas pressure; a pair of low and high range display units for displaying the pressure of the detected gas- a selector valve connected to the low and high range pressure transducers, a selector knob for selecting gas flow to one of the flow paths; control valve having an inlet connection to the sealed container, and outlets connected to: a sample gas canister, a second outlet port connected to the selector valve means for reading the pressure of the gas from the sealed container to either the low range or high range pressure transducers, and a connection for venting gas contained within the sealed container to the atmosphere. A battery is electrically connected to and supplies the power for operating the unit. The pressure transducers, display units, selector and control valve means and the battery is mounted to and housed within a protective casing for portable transport and use.

Portable tester for determining gas content within a core sample

DOEpatents

Garcia, F. Jr.; Schatzel, S.J.

1998-04-21

A portable tester is provided for reading and displaying the pressure of a gas released from a rock core sample stored within a sealed container and for taking a sample of the released pressurized gas for chemical analysis thereof for subsequent use in a modified direct method test which determines the volume of gas and specific type of gas contained within the core sample. The portable tester includes a pair of low and high range electrical pressure transducers for detecting a gas pressure; a pair of low and high range display units for displaying the pressure of the detected gas; a selector valve connected to the low and high range pressure transducers and a selector knob for selecting gas flow to one of the flow paths; control valve having an inlet connection to the sealed container; and outlets connected to: a sample gas canister, a second outlet port connected to the selector valve means for reading the pressure of the gas from the sealed container to either the low range or high range pressure transducers, and a connection for venting gas contained within the sealed container to the atmosphere. A battery is electrically connected to and supplies the power for operating the unit. The pressure transducers, display units, selector and control valve means and the battery is mounted to and housed within a protective casing for portable transport and use. 5 figs.

On use of CO{sub 2} chemiluminescence for combustion metrics in natural gas fired reciprocating engines.

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

Gupta, S. B.; Bihari, B.; Biruduganti, M.

Flame chemiluminescence is widely acknowledged to be an indicator of heat release rate in premixed turbulent flames that are representative of gas turbine combustion. Though heat release rate is an important metric for evaluating combustion strategies in reciprocating engine systems, its correlation with flame chemiluminescence is not well studied. To address this gap an experimental study was carried out in a single-cylinder natural gas fired reciprocating engine that could simulate turbocharged conditions with exhaust gas recirculation. Crank angle resolved spectra (266-795 nm) of flame luminosity were measured for various operational conditions by varying the ignition timing for MBT conditions andmore » by holding the speed at 1800 rpm and Brake Mean effective Pressure (BMEP) at 12 bar. The effect of dilution on CO*{sub 2}chemiluminescence intensities was studied, by varying the global equivalence ratio (0.6-1.0) and by varying the exhaust gas recirculation rate. It was attempted to relate the measured chemiluminescence intensities to thermodynamic metrics of importance to engine research -- in-cylinder bulk gas temperature and heat release rate (HRR) calculated from measured cylinder pressure signals. The peak of the measured CO*{sub 2} chemiluminescence intensities coincided with peak pressures within {+-}2 CAD for all test conditions. For each combustion cycle, the peaks of heat release rate, spectral intensity and temperature occurred in that sequence, well separated temporally. The peak heat release rates preceded the peak chemiluminescent emissions by 3.8-9.5 CAD, whereas the peak temperatures trailed by 5.8-15.6 CAD. Such a temporal separation precludes correlations on a crank-angle resolved basis. However, the peak cycle heat release rates and to a lesser extent the peak cycle temperatures correlated well with the chemiluminescent emission from CO*{sub 2}. Such observations point towards the potential use of flame chemiluminescence to monitor peak bulk gas temperatures as well as peak heat release rates in natural gas fired reciprocating engines.« less

A Responsive Battery with Controlled Energy Release.

PubMed

Wang, Xiaopeng; Gao, Jian; Cheng, Zhihua; Chen, Nan; Qu, Liangti

2016-11-14

A new type of responsive battery with the fascinating feature of pressure perceptibility has been developed, which can spontaneously, timely and reliably control the power outputs (e.g., current and voltage) in response to pressure changes. The device design is based on the structure of the Zn-air battery, in which graphene-coated sponge serves as pressure-sensitive air cathode that endows the whole system with the capability of self-controlled energy release. The responsive batteries exhibit superior battery performance with high open-circuit voltage (1.3 V), and competitive areal capacity of 1.25 mAh cm -2 . This work presents an important move towards next-generation intelligent energy storage devices with energy management function. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of the Solar Wind Pressure on Mercury's Exosphere: Hybrid Simulations

NASA Astrophysics Data System (ADS)

Travnicek, P. M.; Schriver, D.; Orlando, T. M.; Hellinger, P.

2017-12-01

We study effects of the changed solar wind pressure on the precipitation of hydrogen on the Mercury's surface and on the formation of Mercury's magnetosphere. We carry out a set of global hybrid simulations of the Mercury's magnetosphere with the interplanetary magnetic field oriented in the equatorial plane. We change the solar wind pressure by changing the velocity of injected solar wind plasma (vsw = 2 vA,sw; vsw = 4 vA,sw; vsw = 6 vA,sw). For each of the cases we examine proton and electron precipitation on Mercury's surface and calculate yields of heavy ions released from Mercury's surface via various processes (namely: Photo-Stimulated Desorption, Solar Wind Sputtering, and Electron Stimulated Desorption). We study circulation of the released ions within the Mercury's magnetosphere for the three cases.

The effect of a trunk release maneuver on Peak Pressure Index, trunk displacement and perceived discomfort in older adults seated in a High Fowler's position: a randomized controlled trial.

PubMed

Best, Krista L; Desharnais, Guylaine; Boily, Jeanette; Miller, William C; Camp, Pat G

2012-11-16

Pressure ulcers pose significant negative individual consequences and financial burden on the healthcare system. Prolonged sitting in High Fowler's position (HF) is common clinical practice for older adults who spend extended periods of time in bed. While HF aids in digestion and respiration, being placed in a HF may increase perceived discomfort and risk of pressure ulcers due to increased pressure magnitude at the sacral and gluteal regions. It is likely that shearing forces could also contribute to risk of pressure ulcers in HF. The purpose of this study was to evaluate the effect of a low-tech and time-efficient Trunk Release Manuever (TRM) on sacral and gluteal pressure, trunk displacement and perceived discomfort in ambulatory older adults. A randomized controlled trial was used. We recruited community-living adults who were 60 years of age and older using posters, newspaper advertisements and word-of-mouth. Participants were randomly allocated to either the intervention or control group. The intervention group (n = 59) received the TRM, while the control group (n = 58) maintained the standard HF position. The TRM group had significantly lower mean (SD) PPI values post-intervention compared to the control group, 59.6 (30.7) mmHg and 79.9 (36.5) mmHg respectively (p = 0.002). There was also a significant difference in trunk displacement between the TRM and control groups, +3.2 mm and -5.8 mm respectively (p = 0.005). There were no significant differences in perceived discomfort between the groups. The TRM was effective for reducing pressure in the sacral and gluteal regions and for releasing the trunk at the point of contact between the skin and the support surface, but did not have an effect on perceived discomfort. The TRM is a simple method of repositioning which may have important clinical application for the prevention of pressure ulcers that may occur as a result of HF.

[Significance of lateral release in the therapy of patellar chondromalacia].

PubMed

Krüger, T; Göbel, F; Huschenbett, A; Hein, W

2002-10-01

A retrospective study was performed in 26 patients who underwent an operation for femoro-patellar pain due to a patellar chondromalacia with or without minor patellar dislocation/lateral pressure syndrome. The average age of the patients was 28.5 (15-39) years. 22 of the 26 patients revealed minor chondral damages of the stages 1 and 2 according to Outerbridge. In 12 patients ("lavage" group), an arthroscopic joint debridement only was carried out, while an additional open, lateral retinaculum release was made in 14 patients ("lateral release" group). The patella's distance of dislocation according to Hepp was reduced on an average of 3.0 (0-7) mm (p = 0.0019). The results of Bentley's score obtained during the follow-up interval on an average of 30.1 (9 to 60) months were almost identical for both groups. "Good" and "very good" results were achieved in the "lavage" group (83.3 %) and "lateral release" group (78.6 % of the patients). Lateral release should be used in cases of patellar decentration between 5 and 10 mm and adequate pain symptoms. The post-operative distance of dislocation should be less than 5 mm. Under such conditions and with minor chondral damage, a combined approach by using an arthroscopic joint debridement and open lateral release is promising to treat a patellar dislocation/lateral pressure syndrome.

Pyroclast acceleration and energy partitioning in fake explosive eruptions

NASA Astrophysics Data System (ADS)

Gaudin, Damien; Taddeucci, Jacopo; Scheu, Bettina; Valentine, Greg; Capponi, Antonio; Kueppers, Ulrich; Graettiger, Allison; Sonder, Ingo

2014-05-01

Explosive eruptions are characterized by the fast release of energy, with gas expansion playing a lead role. An excess of pressure may be generated either by the exsolution and accumulation of volatiles (e.g., vulcanian and strombolian explosions) or by in situ vaporization of water (e.g., phreato-magmatic explosions). The release of pressurized gas ejects magma and country rock pyroclasts at velocities that can reach several hundred of meters per second. The amount and velocity of pyroclasts is determined not only by the total released energy, but also by the system-specific dynamics of the energy transfer from gas to pyroclasts. In this context, analogue experiments are crucial, since the amount of available energy is determined. Here, we analyze three different experiments, designed to reproduce different aspects of explosive volcanism, focusing on the acceleration phase of the pyroclasts, in order to compare how the potential energy is transferred to the pyroclasts in different systems. In the first, shock-tube-type experiment, salt crystals resting in a pressurized Plexiglas cylinder are accelerated when a diaphragm set is suddenly opened, releasing the gas. In the second experiment, a pressurized air bubble is released in a water-filled Plexiglas pipe; diaphragm opening causes sudden expansion and bursting of the bubble and ejection of water droplets. In the last experiment, specifically focusing on phreatomagmatic eruptions, buried explosive charges accelerate the overlying loose material. All experiments were monitored by multiple high speed cameras and a variety of sensors. Despite the largely differing settings and processes, particle ejection velocity above the vent from the three experiments share a non-linear decay over time. Fitting this decay allows to estimate a characteristic depth that is related to the specific acceleration processes. Given that the initial available energy is experimentally controlled a priori, the information on the acceleration processes (and related kinetic energy) can be used to brings new constraints on the energy partition and general pyroclasts ejection mechanisms during eruptions.

Synthesis of Ni/Graphene Nanocomposite for Hydrogen Storage.

PubMed

Zhou, Chunyu; Szpunar, Jerzy A; Cui, Xiaoyu

2016-06-22

We have designed a Ni-graphene composite for hydrogen storage with Ni nanoparticles of 10 nm in size, uniformly dispersed over a graphene substrate. This system exhibits attractive features like high gravimetric density, ambient conditions, and low activation temperature for hydrogen release. When charged at room temperature and an atmospheric hydrogen pressure of 1 bar, it could yield a hydrogen capacity of 0.14 wt %. When hydrogen pressure increased to 60 bar, the sorbent had a hydrogen gravimetric density of 1.18 wt %. The hydrogen release could occur at an operating temperature below 150 °C and completes at 250 °C.

Sulfur removal and comminution of carbonaceous material

DOEpatents

Narain, N.K.; Ruether, J.A.; Smith, D.N.

1987-10-07

Finely divided, clean coal or other carbonaceous material is provided by forming a slurry of coarse coal in aqueous alkali solution and heating the slurry under pressure to above the critical conditions of steam. The supercritical fluid penetrates and is trapped in the porosity of the coal as it swells in a thermoplastic condition at elevated temperature. By a sudden, explosive release of pressure the coal is fractured into finely divided particles with release of sulfur-containing gases and minerals. The finely divided coal is recovered from the minerals for use as a clean coal product. 2 figs.

Particle adhesion to surfaces under vacuum

NASA Technical Reports Server (NTRS)

Barengoltz, Jack B.

1988-01-01

The release of glass beads and standard dust from aluminum and glass substrates under centrifugation (simulating atmospheric pressure, low vacuum, and high vacuum conditions) was measured, with application to the estimation of contaminant particle release during spacecraft launch. For particles in the 10-100 micron range, dust was found to adhere more strongly than glass beads in all the cases considered. For most of the cases, dust and glass beads adhered more strongly to glass than to aluminum at all pressures. The adhesion force for dust on glass at 10 torr was shown to be as small as the value for dust on aluminum.

Development of pressure-sensitive dosage forms with a core liquefying at body temperature.

PubMed

Wilde, Lisa; Bock, Mona; Wolf, Marieke; Glöckl, Gunnar; Garbacz, Grzegorz; Weitschies, Werner

2014-04-01

Pressure-sensitive dosage forms have been developed that are intended for pulsatile delivery of drugs to the proximal small intestine. The novel dosage forms are composed of insoluble shell and either a hard fat W32 or polyethylene glycol (PEG) 1000 core that are both liquidizing at body temperature. The release is triggered by predominant pressure waves such as contractions of the pylorus causing rupture of the shell and an immediate emptying of the liquefied filling containing the active ingredient. In consequence immediately after the trigger has been effective the total amount of the drug is intended to be available for absorption in the upper small intestine. Both core types were coated with a cellulose acetate film that creates a pressure-sensitive shell in which mechanical resistance is depending on the coating thickness. Results of the texture analysis confirmed a correlation between the polymer load of the coating and the mechanical resistance. The dissolution test performed under conditions of physiological meaningful mechanical stress showed that the drug release is triggered by pressure waves of ⩾300 mbar which are representing the maximal pressure occurring during the gastric emptying. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of a novel osmotically driven drug delivery system for weakly basic drugs.

PubMed

Guthmann, C; Lipp, R; Wagner, T; Kranz, H

2008-06-01

The drug substance SAG/ZK has a short biological half-life and because of its weakly basic nature a strong pH-dependent solubility was observed. The aim of this study was to develop a controlled release (cr) multiple unit pellet formulation for SAG/ZK with pH-independent drug release. Pellets with a drug load of 60% were prepared by extrusion/spheronization followed by cr-film coating with an extended release polyvinyl acetate/polyvinyl pyrrolidone dispersion (Kollidon SR 30 D). To overcome the problem of pH-dependent drug release the pellets were then coated with a second layer of an enteric methacrylic acid and ethyl acrylate copolymer (Kollicoat MAE 30 DP). To increase the drug release rates from the double layered cr-pellets different osmotically active ionic (sodium and potassium chloride) and nonionic (sucrose) additives were incorporated into the pellet core. Drug release studies were performed in media of different osmotic pressure to clarify the main release mechanism. Extended release coated pellets of SAG/ZK demonstrated pH-dependent drug release. Applying a second enteric coat on top of the extended release film coat failed in order to achieve pH-independent drug release. Already low enteric polymer levels on top of the extended release coated pellets decreased drug release rates at pH 1 drastically, thus resulting in a reversal of the pH-dependency (faster release at pH 6.8 than in 0.1N HCl). The addition of osmotically active ingredients (sodium and potassium chloride, and sucrose) increased the imbibing of aqueous fluids into the pellet cores thus providing a saturated drug solution inside the beads and increasing drug concentration gradients. In addition, for these pellets increased formation of pores and cracks in the polymer coating was observed. Hence drug release rates from double layered beads increased significantly. Therefore, pH-independent osmotically driven SAG/ZK release was achieved from pellets containing osmotically active ingredients and coated with an extended and enteric polymer. In contrast, with increasing osmotic pressure of the dissolution medium the in vitro drug release rates decreased significantly.

Investigating the role of ion-pair strategy in regulating nicotine release from patch: Mechanistic insights based on intermolecular interaction and mobility of pressure sensitive adhesive.

PubMed

Li, Qiaoyun; Wan, Xiaocao; Liu, Chao; Fang, Liang

2018-07-01

The aim of this study was to prepare a drug-in-adhesive patch of nicotine (NIC) and use ion-pair strategy to regulate drug delivery rate. Moreover, the mechanism of how ion-pair strategy regulated drug release was elucidated at molecular level. Formulation factors including pressure sensitive adhesives (PSAs), drug loading and counter ions (C 4 , C 6 , C 8 , C 10 , and C 12 ) were screened. In vitro release experiment and in vitro transdermal experiment were conducted to determine the rate-limiting step in drug delivery process. FT-IR and molecular modeling were used to characterize the interaction between drug and PSA. Thermal analysis and rheology study were conducted to investigate the mobility variation of PSA. The optimized patch prepared with NIC-C 8 had the transdermal profile fairly close to that of the commercial product (p > 0.05). The release rate constants (k) of NIC, NIC-C 4 and NIC-C 10 were 21.1, 14.4 and 32.4, respectively. Different release rates of NIC ion-pair complexes were attributed to the dual effect of ion-pair strategy on drug release. On one hand, ion-pair strategy enhanced the interaction between drug and PSA, which inhibited drug release. On the other hand, using ion-pair strategy improved the mobility of PSA, which facilitated drug release. Drug release behavior was determined by combined effect of two aspects above. These conclusions provided a new idea for us to regulate drug release behavior from patch. Copyright © 2018 Elsevier B.V. All rights reserved.

Pressure variable orifice for hydraulic control valve

NASA Technical Reports Server (NTRS)

Ammerman, R. L.

1968-01-01

Hydraulic valve absorbs impact energy generated in docking or joining of two large bodies by controlling energy release to avoid jarring shock. The area of exit porting presented to the hydraulic control fluid is directly proportional to the pressure acting on the fluid.

Release of Micronized Copper Particles from Pressure Treated Wood Products.

EPA Science Inventory

Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about possible human or environmental exposure. Two common pathways ...

Meteorite organics in planetary environments: hydrothermal release, surface activity, and microbial utilization

NASA Technical Reports Server (NTRS)

Mautner, M. N.; Leonard, R. L.; Deamer, D. W.

1995-01-01

Up to 50% of the organics in the Murchison meteorite, possibly including some of the polymer, is released in high temperature and pressure aqueous environments, to 350 degrees C and 250 bar, that simulate submarine volcanic, hydrothermal or impact-induced conditions. Meteorite organics of prebiotic significance, such as nonanoic acid, glycine, and pyrene survive the hydrothermal conditions. The released material is surface active with surface pressures up to 19.8 x 10(-3) N m-1, and exhibits an extended surface tension isotherm which suggests a mixture of amphiphilic components. One component, nonanoic acid, is shown to form vesicles. The materials extracted under mild conditions, at 120 degrees C, are nutrients for the humic acid bacterium Pseudomonas maltophilia and efficient nutrients for the oligotroph Flavobacterium oryzihabitans, demonstrating the capability of microorganisms to metabolize extraterrestrial organics.

Structure and stabilizing interactions of casein micelles probed by high-pressure light scattering and FTIR.

PubMed

Gebhardt, Ronald; Takeda, Naohiro; Kulozik, Ulrich; Doster, Wolfgang

2011-03-17

Caseins form heterogeneous micelles composed of three types of disordered protein chains (α, β, κ), which include protein-bound calcium phosphate particles. We probe the stability limits of the micelle by applying hydrostatic pressure. The resulting changes of the size distribution and the average molecular weight are recorded in situ with static and dynamic light scattering. Pressure induces irreversible dissociation of the micelles into monomers above a critical value depending on their size. The critical pressure increases with temperature, pH, and calcium concentration due to the interplay of hydrophobic and electrostatic interactions. The pressure transition curves are biphasic, reflecting the equilibrium of two micelle states with different stability, average size, entropy, and calcium bound. The fast process of pressure dissociation is used to probe the slow equilibrium of the two micelle states under various conditions. Binding and release of β-casein from the micelle is suggested as the molecular mechanism of stabilization associated with the two states. In situ FTIR spectroscopy covering the P-O stretching region indicates that bound calcium phosphate particles are released from serine phosphate residues at pressures above 100 MPa. The resulting imbalance of charge triggers the complete decomposition of the micelle. © 2011 American Chemical Society

Liquid suspensions of reversible metal hydrides

DOEpatents

Reilly, J.J.; Grohse, E.W.; Winsche, W.E.

1983-12-08

The reversibility of the process M + x/2 H/sub 2/ ..-->.. MH/sub x/, where M is a metal hydride former that forms a hydride MH/sub x/ in the presence of H/sub 2/, generally used to store and recall H/sub 2/, is found to proceed under a liquid, thereby to reduce contamination, provide better temperature control and provide in situ mobility of the reactants. Thus, a slurry of particles of a metal hydride former with an inert solvent is subjected to temperature and pressure controlled atmosphere containing H/sub 2/, to store hydrogen (at high pressures) and to release (at low pressures) previously stored hydrogen. The direction of the flow of the H/sub 2/ through the liquid is dependent upon the H/sub 2/ pressure in the gas phase at a given temperature. When the former is above the equilibrium absorption pressure of the respective hydride the reaction proceeds to the right, i.e., the metal hydride is formed and hydrogen is stored in the solid particle. When the H/sub 2/ pressure in the gas phase is below the equilibrium dissociation pressure of the respective hydride the reaction proceeds to the left, the metal hydride is decomposed and hydrogen is released into the gas phase.

Effect of age on kinetics of nitric oxide release in rat aorta and pulmonary artery.

PubMed Central

Tschudi, M R; Barton, M; Bersinger, N A; Moreau, P; Cosentino, F; Noll, G; Malinski, T; Lüscher, T F

1996-01-01

Aging is an important determinant of vascular disease. Endothelium-derived nitric oxide (NO) is protective as a vasodilator and inhibitor of platelet function. This study was designed to directly measure effects of prolonged aging on endotheliai NO release in isolated blood vessels and to delineate differences between the systemic and pulmonary circulation. Aortas and pulmonary arteries from 5-6-mo-old (young), 18-19-mo-old (middle-aged), and 32-33-mo-old (old) normotensive female rats were used. Blood pressure and plasma estradiol-17beta (E2) remained unchanged. In isolated blood vessels, NO release was induced by the receptor-independent agonist calcium ionophore A23187 (10 micromol/liter) and measured in situ on the endothelial surface of vessels using a porphyrinic microsensor. In vessels suspended in organ chambers isometric tension was recorded. In the aorta, the initial rate of NO release and peak NO concentration were reduced in middle-aged and old rats (P < 0.0006 vs. young rats, n = 6). Furthermore, endothelium-dependent relaxations to calcium ionophore and acetylcholine (both 10(-10) - 10(-5) mol/liter) were also reduced in aortas from old as compared with young rats (n = 6, P < 0.05). The initial rate of NO release and peak NO concentration significantly correlated with maximal relaxation to calcium ionophore A23187 (correlation coefficients r - 0.916, P < 0.0018 and r = 0.961, P < 0.0001, respectively, n = 7). In pulmonary arteries, however, the initial rate of NO release as well as peak NO concentration did not decrease with age (n = 6 for each age group, NS). In both blood vessels, the NO release was unaffected by superoxide dismutase in all age groups (n = 6, NS). Thus, aging specifically reduces initial rate and peak concentrations of endothelial NO release from aorta but not pulmonary artery indicating reduced NO production. As arterial pressure did not change with aging, the chronic exposure of the aorta to higher pressure and/or pulsatility than in the pulmonary artery may be the cause. This appears important as NO plays a protective role by preventing vasoconstriction, thrombosis and atherosclerosis. PMID:8770860

Concentration and form of copper released into aquatic systems from commercial liquid and micronized pressure treated lumber.

EPA Science Inventory

The fate and effects of pristine engineered metal nanomaterials (ENMs) in simplified systems have been widely studied; however, little is known about the potential release and impact of metal ENMs from consumer goods, especially lumber that has been treated with micronized copper...

Jiffy Pop Volcanoes.

ERIC Educational Resources Information Center

Cruz, Irene

1998-01-01

Pans of popcorn are popped to varying degrees in order to compare them to the earth's surface with volcanic pressure building up in this demonstration. Volcanic activity is also related to bodily functions to help students make connections. For example, the release of gas through burping after drinking soda pop is related to the release of…

Concentration and form of copper released into aquatic systems from commercial liquid and micronized pressure treated lumber

EPA Science Inventory

The fate and effects of pristine engineered metal nanomaterials (ENMs) in simplified systems have been widely studied; however, little is known about the potential release and impact of metal ENMs from consumer goods, especially lumber which has been treated with micronized coppe...

One-shot valve may be remotely actuated

NASA Technical Reports Server (NTRS)

Kami, S.

1965-01-01

One-shot valve, with spring-loaded plunger and sealing diaphragm, incorporates an emergency release actuated by a remote sensor. The plunger is released by the electrical melting of a fuse link and pierces the valve seal. The valve lowers fluid pressure in a container without losing the contained fluid.

Incentives for Pollution Abatement: Regulation, Regulatory Threats, and Non-Governmental Pressures

ERIC Educational Resources Information Center

Harrison, Kathryn; Antweiler, Werner

2003-01-01

In the last decade, voluntary efforts by firms to reduce their environmental impacts have received increasing attention from both policymakers and scholars. This article discusses polluters' incentives to reduce their releases. In particular, using data from Canada's National Pollutant Release Inventory, it examines the impacts of conventional…

An Accelerated Release Method of Risperidone Loaded PLGA Microspheres with Good IVIVC.

PubMed

Hu, Xiaoqin; Zhang, Jianwei; Tang, Xuemei; Li, Mingyuan; Ma, Siyu; Liu, Cheng; Gao, Yue; Zhang, Yue; Liu, Yan; Yu, Fanglin; Yang, Yang; Guo, Jia; Li, Zhiping; Mei, Xingguo

2018-01-01

A long release period lasting several days or several weeks is always needed and thereby it is tedious and time consuming to screen formulations of such microspheres with so long release period and evaluate their release profiles in vitro with conventional long-term or "real-time" release method. So, an accelerated release testing of such system is necessary for formulation design as well as quality control purpose. The purpose of this study is to obtain an accelerated release method of risperidone loaded poly(lactic-co-glycolic acid) (PLGA) microspheres with good in vitro/in vivo correlation (IVIVC). Two formulations of risperidone loaded PLGA microspheres used for evaluating IVIVC were prepared by O/W method. The accelerated release condition was optimized by investigating the effect of pH, osmotic pressure, temperature and ethanol concentration on the release of risperidone from microspheres and the in vitro accelerated release profiles of risperidone from PLGA microspheres were obtained under this optimized accelerated release condition. The plasma concentration of risperidone were also detected after subcutaneous injection of risperidone loaded microspheres to rats. The in vivo cumulative absorption profiles were then calculated using Wagner-Nelson model, Loo- Riegelman model and numerical convolution model, respectively. The correlation between in vitro accelerated release and in vivo cumulative absorption were finally evaluated with Least Square Method. It was shown that temperature and ethanol concentration significantly affected the release of risperidone from the microspheres while pH and osmotic pressure of release media slightly affected the release behavior of risperidone. The in vitro release of risperidone from microspheres were finally undergone in PBS (pH7.0, 300mosm) with 20% (V/V) ethanol at 45°C. The sustained and complete release of risperidone was observed in both formulations under the accelerated release condition although these two release profiles were dissimilar. The correlation coefficients (R2) of IVIVC were all above 0.95 and the slopes were all between 0.9564 and 1.1868 in spite of fitted model and microsphere formulation. An in vitro accelerated release method of risperidone microspheres with good IVIVC was established in this paper and this accelerated release method was supposed to have great potential in both in vivo performance prediction and quality control for risperidone loaded PLGA microspheres. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Pressure Systems Energy Release Protection (Gas Pressurized Systems)

NASA Technical Reports Server (NTRS)

Brown, S. J. (Editor)

1986-01-01

A survey of studies into hazards associated with closed or pressurized system rupture and preliminary guidelines for the performance design of primary, secondary, and protective receptors of these hazards are provided. The hazards discussed in the survey are: blast, fragments, ground motion, heat radiation, biological, and chemical. Performance guidelines for receptors are limited to pressurized systems that contain inert gas. The performance guidelines for protection against the remaining unaddressed degenerative hazards are to be covered in another study.

Kinesio taping and manual pressure release: Short-term effects in subjects with myofasical trigger point.

PubMed

Chao, Yu Wen; Lin, Jiu Jenq; Yang, Jing Lan; Wang, Wendy Tzyy-Jiuan

2016-01-01

Randomized controlled trial. Myofascial pain syndrome is characterized by myofascial trigger points (MTrPs) and fascia tenderness. We investigated the effects of manual pressure release (MPR) alone or in combination with taping (MPR/MKT) in subjects with MTrPs. Fifteen and 16 subjects received MPR and MPR/MKT respectively. Outcomes including Pressure pain threshold, muscle stiffness, mechanomyography were assessed at baseline, post-intervention and 7-days later. Pressure pain threshold improved significantly (d = 1.79, p < 0.005) in both groups. Significant improvement in muscle stiffness in the MPR/MKT group (0.27-0.49 mm) as compared to the MPR group (-0.02-0.23 mm). Mechanomyography amplitude in the MPR/MKT group was significantly higher than that of the MPR group (p < 0.05). MPR and MPR/MKT are effective in reducing pain in these subjects. MPR/MKT has a greater effect on muscle stiffness and contraction amplitude. IV. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Prevalence and hemodynamic effects of leaning during CPR

PubMed Central

Niles, Dana E.; Sutton, Robert M.; Nadkarni, Vinay M.; Glatz, Andrew; Zuercher, Mathias; Maltese, Matthew R.; Eilevstjønn, Joar; Abella, Benjamin S.; Becker, Lance B.; Berg, Robert A.

2013-01-01

Background Cardiopulmonary resuscitation (CPR) guidelines recommend complete release between chest compressions (CC). Objective Evaluate the hemodynamic effects of leaning (incomplete chest wall release) during CPR and the prevalence of leaning during CPR. Results In piglet ventricular fibrillation cardiac arrests, 10% and 20% (1.8 kg and 3.6 kg, respectively), leaning during CPR increased right atrial pressures, decreased coronary perfusion pressures, and decreased cardiac index and left ventricular myocardial blood flow by nearly 50%. In contrast, residual leaning of a 260 g accelerometer/ force feedback device did not adversely affect cardiac index or myocardial blood flow. Among 108 adult in-hospital CPR events, leaning ≥2.5 kg was demonstrable in 91% of the events and 12% of the evaluated CC. For 12 children with in-hospital CPR, 28% of CC had residual leaning ≥2.5 kg and 89% had residual leaning ≥0.5 kg. Conclusions Leaning during CPR increases intrathoracic pressure, decreases coronary perfusion pressure, and decreases cardiac output and myocardial blood flow. Leaning is common during CPR. PMID:22208173

Intermittent hydrostatic pressure inhibits matrix metalloproteinase and pro-inflammatory mediator release from human osteoarthritic chondrocytes in vitro.

PubMed

Trindade, Michael C D; Shida, Jun-ichi; Ikenoue, Takashi; Lee, Mel S; Lin, Eric Y; Yaszay, Burt; Yerby, Scott; Goodman, Stuart B; Schurman, David J; Smith, R Lane

2004-09-01

This study tested the hypothesis that intermittent hydrostatic pressure applied to human osteoarthritic chondrocytes modulates matrix metalloproteinase and pro-inflammatory mediator release in vitro. Human osteoarthritic articular chondrocytes were isolated and cultured as primary high-density monolayers. For testing, chondrocyte cultures were transferred to serum-free medium and maintained without loading or with exposure to intermittent hydrostatic pressure (IHP) at 10 MPa at a frequency of 1 Hz for periods of 6, 12 and 24 h. Levels of matrix metalloproteinase-2, -9 (MMP-2, -9), tissue inhibitor of metalloproteinase-1 (TIMP-1), and the pro-inflammatory mediators, interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), released into the culture medium were assessed by ELISA. Matrix metalloproteinase activity was confirmed by zymographic analysis. In the absence of IHP, levels of MMP-2, TIMP-1, IL-6, and MCP-1 in the chondrocyte culture medium increased in a time-dependent manner. Application of IHP decreased MMP-2 levels at all time periods tested, relative to unloaded control cultures maintained for the same time periods. Although 84/82 kDa bands were faintly detectable by zymography, MMP-9 levels were not quantifiable in medium from loaded or unloaded cultures by ELISA. TIMP-1 levels were not altered in response to IHP at any time period tested. IL-6 and MCP-1 levels decreased in cultures exposed to IHP at 12 and 24 h, relative to unloaded control cultures maintained for the same time periods. IHP decreased release of MMP-2, IL-6 and MCP-1 by osteoarthritic chondrocytes in vitro suggesting that pressure influences cartilage stability by modulating chondrocyte expression of these degradative and pro-inflammatory proteins in vivo.

Carvacrol suppresses high pressure high temperature inactivation of Bacillus cereus spores.

PubMed

Luu-Thi, Hue; Corthouts, Jorinde; Passaris, Ioannis; Grauwet, Tara; Aertsen, Abram; Hendrickx, Marc; Michiels, Chris W

2015-03-16

The inactivation of bacterial spores generally proceeds faster and at lower temperatures when heat treatments are conducted under high pressure, and high pressure high temperature (HPHT) processing is, therefore, receiving an increased interest from food processors. However, the mechanisms of spore inactivation by HPHT treatment are poorly understood, particularly at moderately elevated temperature. In the current work, we studied inactivation of the spores of Bacillus cereus F4430/73 by HPHT treatment for 5 min at 600MPa in the temperature range of 50-100°C, using temperature increments of 5°C. Additionally, we investigated the effect of the natural antimicrobial carvacrol on spore germination and inactivation under these conditions. Spore inactivation by HPHT was less than about 1 log unit at 50 to 70°C, but gradually increased at higher temperatures up to about 5 log units at 100°C. DPA release and loss of spore refractility in the spore population were higher at moderate (≤65°C) than at high (≥70°C) treatment temperatures, and we propose that moderate conditions induced the normal physiological pathway of spore germination resulting in fully hydrated spores, while at higher temperatures this pathway was suppressed and replaced by another mechanism of pressure-induced dipicolinic acid (DPA) release that results only in partial spore rehydration, probably because spore cortex hydrolysis is inhibited. Carvacrol strongly suppressed DPA release and spore rehydration during HPHT treatment at ≤65°C and also partly inhibited DPA release at ≥65°C. Concomitantly, HPHT spore inactivation was reduced by carvacrol at 65-90°C but unaffected at 95-100°C. Copyright © 2014 Elsevier B.V. All rights reserved.

Flammability of Heterogeneously Combusting Metals

NASA Technical Reports Server (NTRS)

Jones, Peter D.

1998-01-01

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

Microbial activity at gigapascal pressures.

PubMed

Sharma, Anurag; Scott, James H; Cody, George D; Fogel, Marilyn L; Hazen, Robert M; Hemley, Russell J; Huntress, Wesley T

2002-02-22

We observed physiological and metabolic activity of Shewanella oneidensis strain MR1 and Escherichia coli strain MG1655 at pressures of 68 to 1680 megapascals (MPa) in diamond anvil cells. We measured biological formate oxidation at high pressures (68 to 1060 MPa). At pressures of 1200 to 1600 MPa, living bacteria resided in fluid inclusions in ice-VI crystals and continued to be viable upon subsequent release to ambient pressures (0.1 MPa). Evidence of microbial viability and activity at these extreme pressures expands by an order of magnitude the range of conditions representing the habitable zone in the solar system.

High-pressure behavior of methylammonium lead iodide (MAPbI3) hybrid perovskite

NASA Astrophysics Data System (ADS)

Capitani, Francesco; Marini, Carlo; Caramazza, Simone; Postorino, Paolo; Garbarino, Gaston; Hanfland, Michael; Pisanu, Ambra; Quadrelli, Paolo; Malavasi, Lorenzo

2016-05-01

In this paper we provide an accurate high-pressure structural and optical study of the MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition toward an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing the pressure, the system keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition.

An Ignition Torch Based on Photoignition of Carbon Nanotubes at Elevated Pressure (Briefing Charts)

DTIC Science & Technology

2016-01-04

Ignition Capsule A 10 mg low pressure ignition torch as it ignites a fuel spray We use PITCH to ignite subscale test rockets at 130 K and ~35 atm (~500...distribution is unlimited High Pressure PITCH Applied to a H2/O2 Subscale Rocket Injector Top: a high-pressure chamber for test of subscale rocket injector...to a high-pressure test combustion chamber via a 20 cm extension tube (OD=6 mm) Click >>> 9 DISTRIBUTION STATEMENT A. Approved for public release

Correlating Near-Source Rock Damage from Single-Hole Explosions to Seismic Waves (Postprint)

DTIC Science & Technology

2012-05-07

Technical Paper APPROVED FOR PUBLIC RELEASE; DISTRIBUTION IS UNLIMITED. AIR FORCE RESEARCH LABORATORY Space Vehicles Directorate...Space Vehicles Directorate 3550 Aberdeen Ave SE 3550 Aberdeen Ave SE 11. SPONSOR/MONITOR’S REPORT Kirtland AFB, NM 87117-5776...function of pressure, • Fluid permeability as a function of pressure, • Electrical resistivity as a function of pressure, and • Rock strength. The

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

42 CFR 84.149 - Type C supplied-air respirator, demand and pressure demand class; minimum requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... per square inch) with from 6 to 76 m. (15 to 250 feet) of air-supply hose. (c) The specified air... pounds per square inch gage). (d)(1) Where the pressure in the air-supply system exceeds 863 kN/m.2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that...

Food grade duplex emulsions designed and stabilised with different osmotic pressures.

PubMed

Pawlik, Aleksandra; Cox, Philip W; Norton, Ian T

2010-12-01

In this study we have investigated the production of food grade W(1)/O/W(2) duplex emulsions with salt partitioned into one water phase but not the other. Investigations were carried out with and without balancing osmotic pressures with glucose. A stable 30% primary W(1)/O emulsions containing salt could be produced with more than or equal to 2% polyglycerol polyricinoleate (PGPR) in the oil phase. We suggest that the addition of salt strengthens the interactions between surfactant molecules in the adsorbed film. This is supported by interfacial viscosity and elasticity measurements both of which increased on addition of salt and the fact that in the presence of salt the emulsion was more stable. These simple emulsions were then processed to construct duplex emulsions. When osmotic pressures were balanced with glucose there was still a release of salt in storage. The extent and rate of release was proportional to glucose concentration. This effect was followed over a period of 60days. These data suggest that the release is driven by the chemical potential difference between the two water compartments rather than the unbalanced osmotic pressures. These observations are explained in the context of a water structuring effect from the added glucose, which lowers the interfacial tension of oil-water interface and thus facilitates micellar transport of hydrated salt ions across the oil layer. Copyright © 2010 Elsevier Inc. All rights reserved.

New insights into differential baroreflex control of heart rate in humans

NASA Technical Reports Server (NTRS)

Fadel, P. J.; Stromstad, M.; Wray, D. W.; Smith, S. A.; Raven, P. B.; Secher, N. H.

2003-01-01

Recent data indicate that bilateral carotid sinus denervation in patients results in a chronic impairment in the rapid reflex control of blood pressure during orthostasis. These findings are inconsistent with previous human experimental investigations indicating a minimal role for the carotid baroreceptor-cardiac reflex in blood pressure control. Therefore, we reexamined arterial baroreflex [carotid (CBR) and aortic baroreflex (ABR)] control of heart rate (HR) using newly developed methodologies. In 10 healthy men, 27 +/- 1 yr old, an abrupt decrease in mean arterial pressure (MAP) was induced nonpharmacologically by releasing a unilateral arterial thigh cuff (300 Torr) after 9 min of resting leg ischemia under two conditions: 1) ABR and CBR deactivation (control) and 2) ABR deactivation. Under control conditions, cuff release decreased MAP by 13 +/- 1 mmHg, whereas HR increased 11 +/- 2 beats/min. During ABR deactivation, neck suction was gradually applied to maintain carotid sinus transmural pressure during the initial 20 s after cuff release (suction). This attenuated the increase in HR (6 +/- 1 beats/min) and caused a greater decrease in MAP (18 +/- 2 mmHg, P < 0.05). Furthermore, estimated cardiac baroreflex responsiveness (DeltaHR/DeltaMAP) was significantly reduced during suction compared with control conditions. These findings suggest that the carotid baroreceptors contribute more importantly to the reflex control of HR than previously reported in healthy individuals.

Empirically assessing the potential release of rare earth elements from black shale under simulated hydraulic fracturing conditions

DOE PAGES

Yang, Jon; Verba, Circe; Torres, Marta; ...

2018-02-01

Rare earth elements (REEs) are economically important to modern society and the rapid growth of technologies dependent on REEs has placed considerable economic pressure on their sourcing. This study addresses whether REEs could be released as a byproduct of natural gas extraction from a series of experiments that were designed to simulate hydraulic fracturing of black shale under various pressure (25 and 27.5 MPa) and temperature (50, 90, 130 °C) conditions. The dissolved REEs in the reacted fluids displayed no propensity for the REEs to be released from black shale under high pressure and temperature conditions, a result that ismore » consistent across the different types of fluids investigated. Overall, there was a net loss of REEs from the fluid. These changes in dissolved REEs were greatest at the moment the fluids first contacted the shale and before the high temperature and high pressure conditions were imposed, although the magnitude of these changes (10 -4 μg/g) were small compared to the magnitude of the total REE content present in the solid shale samples (10 2 μg/g). These results highlight the variability and complexity of hydraulic fracturing systems and indicate that REE may not serve as robust tracers for fracturing fluid-shale reactions. Additionally, the results suggest that significant quantities of REEs may not be byproducts of hydraulically fractured shales.« less

Empirically assessing the potential release of rare earth elements from black shale under simulated hydraulic fracturing conditions

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

Yang, Jon; Verba, Circe; Torres, Marta

Rare earth elements (REEs) are economically important to modern society and the rapid growth of technologies dependent on REEs has placed considerable economic pressure on their sourcing. This study addresses whether REEs could be released as a byproduct of natural gas extraction from a series of experiments that were designed to simulate hydraulic fracturing of black shale under various pressure (25 and 27.5 MPa) and temperature (50, 90, 130 °C) conditions. The dissolved REEs in the reacted fluids displayed no propensity for the REEs to be released from black shale under high pressure and temperature conditions, a result that ismore » consistent across the different types of fluids investigated. Overall, there was a net loss of REEs from the fluid. These changes in dissolved REEs were greatest at the moment the fluids first contacted the shale and before the high temperature and high pressure conditions were imposed, although the magnitude of these changes (10 -4 μg/g) were small compared to the magnitude of the total REE content present in the solid shale samples (10 2 μg/g). These results highlight the variability and complexity of hydraulic fracturing systems and indicate that REE may not serve as robust tracers for fracturing fluid-shale reactions. Additionally, the results suggest that significant quantities of REEs may not be byproducts of hydraulically fractured shales.« less

Water boiling inside carbon nanotubes: toward efficient drug release.

PubMed

Chaban, Vitaly V; Prezhdo, Oleg V

2011-07-26

We show using molecular dynamics simulation that spatial confinement of water inside carbon nanotubes (CNTs) substantially increases its boiling temperature and that a small temperature growth above the boiling point dramatically raises the inside pressure. Capillary theory successfully predicts the boiling point elevation down to 2 nm, below which large deviations between the theory and atomistic simulation take place. Water behaves qualitatively different inside narrow CNTs, exhibiting transition into an unusual phase, where pressure is gas-like and grows linearly with temperature, while the diffusion constant is temperature-independent. Precise control over boiling by CNT diameter, together with the rapid growth of inside pressure above the boiling point, suggests a novel drug delivery protocol. Polar drug molecules are packaged inside CNTs; the latter are delivered into living tissues and heated by laser. Solvent boiling facilitates drug release.

Mechanics of dual-mode dilative failure in subaqueous sediment deposits

NASA Astrophysics Data System (ADS)

You, Yao; Flemings, Peter; Mohrig, David

2014-07-01

We introduce dual-mode dilative failure with flume experiments. Dual-mode dilative failure combines slow and steady release of sediments by breaching with periodic sliding, which rapidly releases an internally coherent wedge of sediments. It occurs in dilative sandy deposits. This periodic slope failure results from cyclic evolution of the excess pore pressure in the deposit. Sliding generates large, transient, negative excess pore pressure that strengthens the deposit and allows breaching to occur. During breaching, negative excess pore pressure dissipates, the deposit weakens, and ultimately sliding occurs once again. We show that the sliding frequency is proportional to the coefficient of consolidation. We find that thicker deposits are more susceptible to dual-mode dilative failure. Discovery of dual-mode dilative failure provides a new mechanism to consider when interpreting the sedimentary deposits linked to submarine slope failures.

Hydrostatic pressure and shear stress affect endothelin-1 and nitric oxide release by endothelial cells in bioreactors.

PubMed

Vozzi, Federico; Bianchi, Francesca; Ahluwalia, Arti; Domenici, Claudio

2014-01-01

Abundant experimental evidence demonstrates that endothelial cells are sensitive to flow; however, the effect of fluid pressure or pressure gradients that are used to drive viscous flow is not well understood. There are two principal physical forces exerted on the blood vessel wall by the passage of intra-luminal blood: pressure and shear. To analyze the effects of pressure and shear independently, these two stresses were applied to cultured cells in two different types of bioreactors: a pressure-controlled bioreactor and a laminar flow bioreactor, in which controlled levels of pressure or shear stress, respectively, can be generated. Using these bioreactor systems, endothelin-1 (ET-1) and nitric oxide (NO) release from human umbilical vein endothelial cells were measured under various shear stress and pressure conditions. Compared to the controls, a decrease of ET-1 production by the cells cultured in both bioreactors was observed, whereas NO synthesis was up-regulated in cells under shear stress, but was not modulated by hydrostatic pressure. These results show that the two hemodynamic forces acting on blood vessels affect endothelial cell function in different ways, and that both should be considered when planning in vitro experiments in the presence of flow. Understanding the individual and synergic effects of the two forces could provide important insights into physiological and pathological processes involved in vascular remodeling and adaptation. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanical breath profile of airway pressure release ventilation: the effect on alveolar recruitment and microstrain in acute lung injury.

PubMed

Kollisch-Singule, Michaela; Emr, Bryanna; Smith, Bradford; Roy, Shreyas; Jain, Sumeet; Satalin, Joshua; Snyder, Kathy; Andrews, Penny; Habashi, Nader; Bates, Jason; Marx, William; Nieman, Gary; Gatto, Louis A

2014-11-01

Improper mechanical ventilation settings can exacerbate acute lung injury by causing a secondary ventilator-induced lung injury. It is therefore important to establish the mechanism by which the ventilator induces lung injury to develop protective ventilation strategies. It has been postulated that the mechanism of ventilator-induced lung injury is the result of heterogeneous, elevated strain on the pulmonary parenchyma. Acute lung injury has been associated with increases in whole-lung macrostrain, which is correlated with increased pathology. However, the effect of mechanical ventilation on alveolar microstrain remains unknown. To examine whether the mechanical breath profile of airway pressure release ventilation (APRV), consisting of a prolonged pressure-time profile and brief expiratory release phase, reduces microstrain. In a randomized, nonblinded laboratory animal study, rats were randomized into a controlled mandatory ventilation group (n = 3) and an APRV group (n = 3). Lung injury was induced by polysorbate lavage. A thoracotomy was performed and an in vivo microscope was placed on the lungs to measure alveolar mechanics. In the controlled mandatory ventilation group, multiple levels of positive end-expiratory pressure (PEEP; 5, 10, 16, 20, and 24 cm H2O) were tested. In the APRV group, decreasing durations of expiratory release (time at low pressure [T(low)]) were tested. The T(low) was set to achieve ratios of termination of peak expiratory flow rate (T-PEFR) to peak expiratory flow rate (PEFR) of 10%, 25%, 50%, and 75% (the smaller this ratio is [ie, 10%], the more time the lung is exposed to low pressure during the release phase, which decreases end-expiratory lung volume and potentiates derecruitment). Alveolar perimeters were measured at peak inspiration and end expiration using digital image analysis, and strain was calculated by normalizing the change in alveolar perimeter length to the original length. Macrostrain was measured by volume displacement. Higher PEEP (16-24 cm H2O) and a brief T(low) (APRV T-PEFR to PEFR ratio of 75%) reduced microstrain. Microstrain was minimized with an APRV T-PEFR to PEFR ratio of 75% (mean [SEM], 0.05 [0.03]) and PEEP of 16 cm H2O (mean [SEM], 0.09 [0.08]), but an APRV T-PEFR to PEFR ratio of 75% also promoted alveolar recruitment compared with PEEP of 16 cm H2O (mean [SEM] total inspiratory area, 52.0% [2.9%] vs 29.4% [4.3%], respectively; P < .05). Whole-lung strain was correlated with alveolar microstrain in tested settings (P < .05) except PEEP of 16 cm H2O (P > .05). Increased positive-end expiratory pressure and reduced time at low pressure (decreased T(low)) reduced alveolar microstrain. Reduced microstrain and improved alveolar recruitment using an APRV T-PEFR to PEFR ratio of 75% may be the mechanism of lung protection seen in previous clinical and animal studies.

Study of physical and biological factors involved in the disruption of E. coli by hydrodynamic cavitation.

PubMed

Balasundaram, B; Harrison, S T L

2006-01-01

Hydrodynamic cavitation results in flow restriction in a flow system causing rapid pressure fluctuations and significant fluid forces. These can be harnessed to mediate microbial cell damage. Hydrodynamic cavitation was studied for the partial disruption of E. coli and selective release of specific proteins relative to the total soluble protein. The effects of the cavitation number, the number of passes, and the specific growth rate of E. coli on the release of periplasmic and cytoplasmic proteins were studied. At the optimum cavitation number of 0.17 for this experimental configuration, 48% of the total soluble protein, 88% of acid phosphatase, and 67% of beta-galactosidase were released by hydrodynamic cavitation in comparison with the maximum release attained using multiple passes through the French Press. The higher release of the acid phosphatase over the total soluble protein suggested preferred release of periplasmic compounds. This was supported by SDS-PAGE analysis. The absence of micronization of cell material resulting in the potential for ease of solid-liquid separation downstream of the cell disruption operation was confirmed by TEM microscopy. E. coli cells cultivated at a higher specific growth rate (0.36 h(-1)) were more easily disrupted than slower grown cells (0.11 h(-1)). The specific activity of the enzyme of interest released by hydrodynamic cavitation, defined as the units of enzyme in solution per milligram of total soluble protein, was greater than that obtained on release by the French Press, high-pressure homogenization, osmotic shock, and EDTA treatment. The selectivity offered indicates the potential of enzyme release by hydrodynamic cavitation to ease the purification in the subsequent downstream processing.

Release of Micronized Copper Particles from Pressure Treated Wood Products

EPA Science Inventory

Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about the exposure of humans as well as the environment to the parti...

User’s Manual for the Ride Motion Simulator

DTIC Science & Technology

1989-08-01

1800 psi). Step 16. Pressurize the system by moving the main pressure switch to "ON." Wait for the roll, pitch, and yaw error signals to go to "Zero...Carefully, help the test subject dismount. Step 41. Flip the main pressure switch on the hydraulic control panel to "OFF." This will block hydraulic...1.13, thus lowering the seat. Release the "Low Limit Override" switch. Step 5. Dismount the test subject. Step 6. Move the main pressure switch to the

Pressure Suppresses Serotonin Release by Guinea Pig Striatal Synaptosomes

DTIC Science & Technology

1988-01-01

neurological syndrome. Brit J Pharmacol 1982; 76:447-452. 5. Wardley-Smith B, Meldrum BS. Effect of excitatory amino acid antagonists on !he high pressure...Res 1974; 1:,-28. *14. IBichard AR, Little HIJ. Drugs that increase Y-aminobutyric acid tr.ansmission prm ict PF..atnst * I the high pressure...Effects of high pressure of heliox on the striatal 5-HIAA and ascorbic acid rates in the rat. Cent Etud Rech Bio-Physiol Rep 84-08. 1984:35. 7

Shock and Release Response of Unreacted Epon 828: Shot 2s-905

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

Pisa, Matthew Alexander; Fredenburg, David A.; Dattelbaum, Dana M.

This document summarizes the shock and release response of Epon 828 measured in the dynamic impact experiment 2s-905. Experimentally, a thin Kel-F impactor backed by a low impedance foam impacted an Epon 828 target with embedded electromagnetic gauges. Computationally, a one dimensional simulation of the impact event was performed, and tracer particles were located at the corresponding electromagnetic gauge locations. The experimental configuration was such that the Epon 828 target was initially shocked, and then allowed to release from the high-pressure state. Comparisons of the experimental gauge and computational tracer data were made to assess the performance of equation ofmore » state (EOS) 7603, a SESAME EOS for Epon 828, on and off the principal shock Hugoniot. Results indicate that while EOS 7603 can capture the Hugoniot response to better that 1%, while the sound speeds at pressure are under-predicted by 6 - 7%.« less

Gas dispersion measurements using a mobile Raman lidar system

NASA Technical Reports Server (NTRS)

Houston, J. D.; Brown, D. R.

1986-01-01

The exploitation of natural gas resources to supply energy demands has resulted in the need to engineer pipelines and plants capable of handling extremely high pressures and throughputs. Consequently, more attention has been directed to evaluating the consequences of releases of material whether accidental or deliberate in nature. An important aspect of assessing the consequences of a release is an understanding of how gas disperses in the atmosphere over a wide range of release and atmospheric conditions. The most cost effective way of providing such information is through the development and use of reliable theoretical prediction methods. The need for some form of remote sensing device was identified. The various possibilities studied led to the conclusion that LIDAR (Light Detection And Ranging) offered the most suitable method. The system designed and built is described, and its recent use in monitoring operational ventings from a high pressure transmission system is discussed.

Reduction of mosquito biting pressure by timed-release 0.3% aerosolized geraniol

USDA-ARS?s Scientific Manuscript database

We conducted a study to determine the degree of personal protection provided by the Terminix® ALLCLEAR® Mosquito Mister – Lantern Edition. This outdoor unit was operated to disperse an aerosolized aqueous 0.3% geraniol emulsion in timed-release intervals of 5.0, 7.5, and 10.0 min. Human volunteers ...

Minimum threshold for establishment and dispersal of Lilioceris cheni (Coleoptera: Chrysomelide): a biological control agent of Dioscorea bulbifera

USDA-ARS?s Scientific Manuscript database

The successful establishment or failure of a new population is often attributed to propagule pressure, the combination of the number of independent introduction events, and the number of individuals released at each event. Design of optimal release strategies for biological control agents benefits f...

Prediction of heat release effects on a mixing layer

NASA Technical Reports Server (NTRS)

Farshchi, M.

1986-01-01

A fully second-order closure model for turbulent reacting flows is suggested based on Favre statistics. For diffusion flames the local thermodynamic state is related to single conserved scalar. The properties of pressure fluctuations are analyzed for turbulent flows with fluctuating density. Closure models for pressure correlations are discussed and modeled transport equations for Reynolds stresses, turbulent kinetic energy dissipation, density-velocity correlations, scalar moments and dissipation are presented and solved, together with the mean equations for momentum and mixture fraction. Solutions of these equations are compared with the experimental data for high heat release free mixing layers of fluorine and hydrogen in a nitrogen diluent.

Combustion Characteristics of CI Diesel Engine Fuelled With Blends of Jatropha Oil Biodiesel

NASA Astrophysics Data System (ADS)

Singh, Manpreet; Yunus Sheikh, Mohd.; Singh, Dharmendra; Nageswara rao, P.

2018-03-01

Jatropha Curcas oil is a non-edible oil which is used for Jatropha biodiesel (JBD) production. Jatropha biodiesel is produced using transesterification technique and it is used as an alternative fuel in CI diesel engine without any hardware modification. Jatropha biodiesel is used in CI diesel engine with various volumetric concentrations (blends) such as JBD5, JBD15, JBD25, JBD35 and JBD45. The combustion parameters such as in-cylinder pressure, rate of pressure rise, net heat release, cumulative heat release, mass fraction burned are analyzed and compared for all blends combustion data with mineral diesel fuel (D100).

Fission Product Release and Survivability of UN-Kernel LWR TRISO Fuel

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

Besmann, Theodore M; Ferber, Mattison K; Lin, Hua-Tay

2014-01-01

A thermomechanical assessment of the LWR application of TRISO fuel with UN kernels was performed. Fission product release under operational and transient temperature conditions was determined by extrapolation from range calculations and limited data from irradiated UN pellets. Both fission recoil and diffusive release were considered and internal particle pressures computed for both 650 and 800 m diameter kernels as a function of buffer layer thickness. These pressures were used in conjunction with a finite element program to compute the radial and tangential stresses generated with a TRISO particle as a function of fluence. Creep and swelling of the innermore » and outer pyrolytic carbon layers were included in the analyses. A measure of reliability of the TRISO particle was obtained by measuring the probability of survival of the SiC barrier layer and the maximum tensile stress generated in the pyrolytic carbon layers as a function of fluence. These reliability estimates were obtained as functions of the kernel diameter, buffer layer thickness, and pyrolytic carbon layer thickness. The value of the probability of survival at the end of irradiation was inversely proportional to the maximum pressure.« less

Forearm vasodilatation following release of venous congestion

PubMed Central

Caro, C. G.; Foley, T. H.; Sudlow, M. F.

1970-01-01

1. The volume rate of forearm blood flow was measured with a mercury-in-rubber strain gauge, or with a water-filled plethysmograph, from 1 sec after termination of a 2-3 min period of venous congestion. 2. When congesting pressure had been less than 18 mm Hg, average post-congestion flow (five subjects) was constant during approx. 10 sec and not significantly different from resting flow. 3. When congesting pressure had been 30 mm Hg, average post-congestion flow (eight subjects) was 26% higher than resting, during 3-4 sec after release of congestion, but rose to 273% of resting during 4-6 sec after release of congestion. 4. In other studies forearm vascular resistance had been found normal or increased during such venous congestion, and theoretical studies here indicated that passive mechanical factors could not account for the delayed occurrence of high post-congestion flow. 5. It appears, therefore, that the forearm vascular bed dilates actively shortly after release of substantial venous congestion. It would seem more likely that a myogenic mechanism, rather than a metabolic one, is responsible. PMID:5532541

Shock loading and release behavior of silicon nitride

NASA Astrophysics Data System (ADS)

Kawai, N.; Tsuru, T.; Hidaka, N.; Liu, X.; Mashimo, T.

2017-01-01

Shock-reshock and shock-release experiments were performed on silicon nitride ceramics above and below its phase transition pressure. Experimental results clearly show the occurrence of elastic-plastic transition and phase transition during initial shock loading. The HEL and phase transition stress are determined as 11.6 and 34.5 GPa, respectively. Below the phase transition stress, the reshock profile consists of the single shock with short rise time, while the release profile shows the gradual release followed by rapid one. Above phase transition stress, reshock and release behavior varies with the initial shock stress. In the case of reshock and release from about 40 GPa, the reshock structure is considerably dispersed, while the release structure shows rapid release. In the reshock profile from about 50 GPa, the formation of the shock wave with the small ramped precursor is observed. And, the release response from same shocked condition shows initial gradual release and subsequent quite rapid one. These results would provide the information about how phase transformation kinetics effects on the reshock and release behavior.

Hydrostatic pressure and muscarinic receptors are involved in the release of inflammatory cytokines in human bladder smooth muscle cells.

PubMed

Liang, Zhou; Xin, Wei; Qiang, Liu; Xiang, Cai; Bang-Hua, Liao; Jin, Yang; De-Yi, Luo; Hong, Li; Kun-Jie, Wang

2017-06-01

Abnormal intravesical pressure results in a series of pathological changes. We investigated the effects of hydrostatic pressure and muscarinic receptors on the release of inflammatory cytokines in rat and human bladder smooth muscle cells (HBSMCs). Animal model of bladder outlet obstruction was induced by urethra ligation. HBSMCs were subjected to elevated hydrostatic pressure and/or acetylcholine (Ach). Macrophage infiltration in the bladder wall was determined by immunohistochemical staining. The expression of inflammatory genes was measured by RT-PCR, ELISA and immunofluorescence. In obstructed bladder, inflammatory genes and macrophage infiltration were remarkably induced. When HBSMCs were subjected to 200-300 cm H 2 O pressure for 2-24 h in vitro, the expressions of IL-6 and RANTES were significantly increased. Hydrostatic pressure promoted the protein levels of phospho-NFκB p65 and phospho-ERK1/2 as well as muscarinic receptors. Moreover, NFκB or ERK1/2 inhibitors suppressed pressure-induced inflammatory genes mRNA. When cells were treated with 1 μM acetylcholine for 6 h, a significant increase in IL-6 mRNA expression was detected. Acetylcholine also enhanced pressure-induced phospho-NFκB p65 and IL-6 protein expression. Additionally, pressure-induced IL-6 was partially suppressed by muscarinic receptors antagonists. Hydrostatic pressure and muscarinic receptors were involved in the secretion of inflammatory cytokines in HBSMCs, indicating a pro-inflammatory effect of the two factors in the pathological process of BOO. © 2016 Wiley Periodicals, Inc.

Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters I: Concentrations and rates.

PubMed

Parks, Ashley N; Cantwell, Mark G; Katz, David R; Cashman, Michaela A; Luxton, Todd P; Ho, Kay T; Burgess, Robert M

2018-03-25

Little is known about the release of metal engineered nanomaterials (ENMs) from consumer goods, including lumber treated with micronized copper. Micronized copper is a recent form of antifouling wood preservative containing nanosized copper particles for use in pressure-treated lumber. The present study investigated the concentrations released and the release rate of total copper over the course of 133 d under freshwater, estuarine, and marine salinity conditions (0, 1, 10, and 30‰) for several commercially available pressure-treated lumbers: micronized copper azole (MCA) at 0.96 and 2.4 kg/m 3 , alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m 3 , and chromated copper arsenate (CCA) at 40 kg/m 3 . Lumber was tested as blocks and as sawdust. Overall, copper was released from all treated lumber samples. Under leaching conditions, total release ranged from 2 to 55% of the measured copper originally in the lumber, with release rate constants from the blocks of 0.03 to 2.71 (units per day). Generally, measured release and modeled equilibrium concentrations were significantly higher in the estuarine conditions compared with freshwater or marine salinities, whereas rate constants showed very limited differences between salinities. Furthermore, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. The results indicate that copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle-sized copper. Environ Toxicol Chem 2018;9999:1-13. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Uranium mobility during interaction of rhyolitic glass with alkaline solutions: dissolution of glass

USGS Publications Warehouse

Zielinski, Robert A.

1977-01-01

This report concerns investigations designed to identify the important physical and chemical parameters influencing the rate of release of uranium from glass shards of rhyolitic air-fall ash. Oxidizing, silica undersaturated, alkaline solutions are eluted through a column of rhyolitic glass shards at a carefully controlled temperature, pressure, and flow rate. The solutions are monitored for the concentration of uranium and selected additional elements (Si, K, Li, F), and the glass is recovered and examined for physical and/or chemical evidence of attack. The flushing mode is designed to mimic leaching of glass shards by intermittent, near-surface waters with which the glass is not in equilibrium. Reported rates are applicable only to the experimental conditions (120?C, 7,000 psi), but it is assumed that the reaction mechanisms and the relative importance of rate-influencing parameters remain unchanged, at reduced temperature and pressure. Results of the above experiment indicate that silica and uranium are released from glass shards at comparable rates, while lithium and potassium are released faster and fluorine slower than either Si or U. Rates of release of silica and uranium correlate positively with the surface area of the shards. Rhyolitic shards release uranium at faster rates than rhyodacitic shards of comparable surface area. Changes in the shards resulting from experimental treatment and observed in the original glass separates from an Oligocene ash (compared to a Pleistocene ash) include; surface pitting, increased surface area, devitrification rinds (<1l micron wide) and reduced lithium contents. Future investigations will study the effect of temperature, pressure, solution composition, and flow rate on the relative mobility of U, Si, Li, F, and K.

Effect of Latent Heat Released by Freezing Droplets during Frost Wave Propagation.

PubMed

Chavan, Shreyas; Park, Deokgeun; Singla, Nitish; Sokalski, Peter; Boyina, Kalyan; Miljkovic, Nenad

2018-05-21

Frost spreads on nonwetting surfaces during condensation frosting via an interdroplet frost wave. When a supercooled condensate water droplet freezes on a hydrophobic or superhydrophobic surface, neighboring droplets still in the liquid phase begin to evaporate. Two possible mechanisms govern the evaporation of neighboring water droplets: (1) The difference in saturation pressure of the water vapor surrounding the liquid and frozen droplets induces a vapor pressure gradient, and (2) the latent heat released by freezing droplets locally heats the substrate, leading to evaporation of nearby droplets. The relative significance of these two mechanisms is still not understood. Here, we study the significance of the latent heat released into the substrate by freezing droplets, and its effect on adjacent droplet evaporation, by studying the dynamics of individual water droplet freezing on aluminum-, copper-, and glass-based hydrophobic and superhydrophobic surfaces. The latent heat flux released into the substrate was calculated from the measured droplet sizes and the respective freezing times ( t f ), defined as the time from initial ice nucleation within the droplet to complete droplet freezing. To probe the effect of latent heat release, we performed three-dimensional transient finite element simulations showing that the transfer of latent heat to neighboring droplets is insignificant and accounts for a negligible fraction of evaporation during microscale frost wave propagation. Furthermore, we studied the effect of substrate thermal conductivity on the transfer of latent heat transfer to neighboring droplets by investigating the velocity of ice bridge formation. The velocity of the ice bridge was independent of the substrate thermal conductivity, indicating that adjacent droplet evaporation during condensation frosting is governed solely by vapor pressure gradients. This study not only provides key insights into the individual droplet freezing process but also elucidates the negligible role of latent heat released into the substrate during frost wave propagation.

Polymer Claw: Instant Underwater Adhesive

DTIC Science & Technology

2012-08-27

technology is the use of pressure sensitive microcapsules , which release reactive amine crosslinkers into an adhesive putty when pressed against the surface...CLEANING AGENT RHEOLOGY 3 3.3 PRESSURE-ACTIVATED ADHESIVE 5 3.3.1 PROCESSING IMPROVEMENTS 5 3.3.2 MICROCAPSULE DIAMETER 5 3.3.3 MICROCAPSULE /RESIN...to attain a reasonable shelf life (- l wk.). The microcapsule diameter has been halved in order to improve mixing in the pressure-activated

Blood pressure responses of wild giraffes studied by radio telemetry.

PubMed

Van Citters, R L; Kemper, W S; Franklin, D L

1966-04-15

Blood pressure was telemetered from transducers chronically implanted in the carotid arteries of two adult, wild, male giraffes captured and released near Kiboko, Kenya. Cerebral perfusion pressure ranged from 280/180 mm-Hg while the animal was lying with its head on the ground to 125/75 mm-Hg when it was standing erect; it varied between these levels during spontaneous activity such as walking, grazing, and running.

Propellant actuated nuclear reactor steam depressurization valve

DOEpatents

Ehrke, Alan C.; Knepp, John B.; Skoda, George I.

1992-01-01

A nuclear fission reactor combined with a propellant actuated depressurization and/or water injection valve is disclosed. The depressurization valve releases pressure from a water cooled, steam producing nuclear reactor when required to insure the safety of the reactor. Depressurization of the reactor pressure vessel enables gravity feeding of supplementary coolant water through the water injection valve to the reactor pressure vessel to prevent damage to the fuel core.

System for exchange of hydrogen between liquid and solid phases

DOEpatents

Reilly, James J.; Grohse, Edward W.; Johnson, John R.; Winsche, deceased, Warren E.

1988-01-01

The reversible reaction M+x/2 H.sub.2 .rarw..fwdarw.MH.sub.x, wherein M is a reversible metal hydride former that forms a hydride MH.sub.x in the presence of H.sub.2, generally used to store and recall H.sub.2, is found to proceed under an inert liquid, thereby reducing contamination, providing better temperature control, providing in situ mobility of the reactants, and increasing flexibility in process design. Thus, a slurry of particles of a metal hydride former with an inert solvent is subjected to a temperature and pressure controlled atmosphere containing H.sub.2, to store hydrogen and to release previously stored hydrogen. The direction of the flow of the H.sub.2 through the liquid is dependent upon the H.sub.2 pressure in the gas phase at a given temperature. When the actual H.sub.2 pressure is above the equilibrium absorption pressure of the respective hydride the reaction proceeds to the right, i.e., the metal hydride is formed and hydrogen is stored in the solid particles. When the actual pressure in the gas phase is below the equilibrium dissociation pressure of the respective hydride the reaction proceeds to the left, the metal hydride is decomposed and hydrogen is released into the gas phase.

System for exchange of hydrogen between liquid and solid phases

DOEpatents

Reilly, J.J.; Grohse, E.W.; Johnson, J.R.; Winsche, W.E.

1985-02-22

The reversible reaction M + x/2 H/sub 2/ reversible MH/sub x/, wherein M is a reversible metal hydride former that forms a hydride MH/sub x/ in the presence of H/sub 2/, generally used to store and recall H/sub 2/, is found to proceed under an inert liquid, thereby reducing contamination, providing better temperature control, providing in situ mobility of the reactants, and increasing flexibility in process design. Thus, a slurry of particles of a metal hydride former with an inert solvent is subjected to a temperature and pressure controlled atmosphere containing H/sub 2/, to store hydrogen and to release previously stored hydrogen. The direction of the flow of the H/sub 2/ through the liquid is dependent upon the H/sub 2/ pressure in the gas phase at a given temperature. When the actual H/sub 2/ pressure is above the equilibrium absorption pressure of the respective hydride the reaction proceeds to the right, i.e., the metal hydride is formed and hydrogen is stored in the solid particle. When the actual pressure in the gas phase is below the equilibrium dissociation pressure of the respective hydride the reaction proceeds to the left, the metal hydride is decomposed and hydrogen is released into the gas phase.

Gravitropism in Higher Plant Shoots 1

PubMed Central

Mueller, Wesley J.; Salisbury, Frank B.; Blotter, P. Thomas

1984-01-01

Dimensional changes during gravitropic bending of cocklebur (Xanthium strumarium L.) dicot stems were measured using techniques of stereo photogrammetry. The differential growth is from an increased growth rate on the bottom of the stem and a stopping or contraction of the top. Contraction of the top was especially evident upon release and immediate bending of horizontal stems that had been restrained between stiff wires for 36 hours. The energy for this could have been stored in both the top and bottom, since the bottom elongated, and the top contracted. Forces developed during bending were measured by fastening a stem tip to the end of a bar with attached strain gauges and recording electrical output from the strain gauges. Restrained mature cocklebur stems continued to accumulate potential energy for bending for about 120 hours, after which the recorded force reached a maximum. Pressures within castor bean (Ricinus communis L.) stems were also measured with 3.5-millimeter diameter pressure transducers. As expected, the pressure on the bottom of the restrained plants increased with time; pressures decreased in vertical controls, tops of restrained stems, and bottoms of free-bending stems. Pressures increased in tops of free-bending stems. When restrained plants were released, pressure on the bottom decreased and pressure on the top increased. Results suggest a possible role for cell contraction in the top of stems bending upward in response to gravity. Images Fig. 5 Fig. 11 PMID:16663987

Effect of pericardiocentesis on circulating concentrations of atrial natriuretic hormone and arginine vasopressin in dogs with spontaneous pericardial effusion.

PubMed

Stokhof, A A; Overduin, L M; Mol, J A; Rijnberk, A

1994-04-01

Factors regulating the secretion of atrial natriuretic hormone (ANH) and arginine vasopressin (AVP) have not been elucidated fully. In several studies the release of these peptides has been studied by inducing both increased atrial pressure and atrial distension. A few studies employ cardiac tamponade, allowing the effect of atrial pressure and atrial stretch to be studied separately. In eleven dogs with spontaneous cardiac tamponade the effect of pericardiocentesis on circulating concentrations of ANP and AVP was studied. Pericardiocentesis was followed by a prompt rise in (non-elevated) plasma ANH concentrations from 21.6 +/- 7.3 to 65.4 +/- 17.1 pmol/l (mean +/- SEM). The initially slightly elevated AVP concentration of 5.5 +/- 1.5 pmol/l declined following pericardiocentesis to 2.1 +/- 0.5 pmol/l. In three dogs the systolic arterial pressure was measured indirectly and the central venous pressure was measured with a fluid-filled catheter. Before and after pericardiocentesis arterial pressure readings did not change significantly. Central venous pressure values showed an immediate very steep significant decrease after centesis. It is concluded that ANH release is primarily regulated by stretch and not by atrial pressure, that plasma AVP concentrations are moderately elevated in cardiac tamponade and that in cardiac tamponade pericardiocentesis causes a rapid decline in plasma AVP concentration.

Energy balance during underwater implosion of ductile metallic cylinders.

PubMed

Chamberlin, Ryan E; Guzas, Emily L; Ambrico, Joseph M

2014-11-01

Energy-based metrics are developed and applied to a numerical test case of implosion of an underwater pressure vessel. The energy metrics provide estimates of the initial energy in the system (potential energy), the energy released into the fluid as a pressure pulse, the energy absorbed by the imploding structure, and the energy absorbed by air trapped within the imploding structure. The primary test case considered is the implosion of an aluminum cylinder [diameter: 2.54 cm (1 in.), length: 27.46 cm (10.81 in.)] that collapses flat in a mode-2 shape with minimal fracture. The test case indicates that the structure absorbs the majority (92%) of the initial energy in the system. Consequently, the energy emitted as a pressure pulse into the fluid is a small fraction, approximately 5%, of the initial energy. The energy absorbed by the structure and the energy emitted into the fluid are calculated for additional simulations of underwater pressure vessel implosions. For all cases investigated, there is minimal fracture in the collapse, the structure absorbs more than 80% of the initial energy of the system, and the released pressure pulse carries away less than 6% of the initial energy.

An ultra scale-down approach to study the interaction of fermentation, homogenization, and centrifugation for antibody fragment recovery from rec E. coli.

PubMed

Li, Qiang; Mannall, Gareth J; Ali, Shaukat; Hoare, Mike

2013-08-01

Escherichia coli is frequently used as a microbial host to express recombinant proteins but it lacks the ability to secrete proteins into medium. One option for protein release is to use high-pressure homogenization followed by a centrifugation step to remove cell debris. While this does not give selective release of proteins in the periplasmic space, it does provide a robust process. An ultra scale-down (USD) approach based on focused acoustics is described to study rec E. coli cell disruption by high-pressure homogenization for recovery of an antibody fragment (Fab') and the impact of fermentation harvest time. This approach is followed by microwell-based USD centrifugation to study the removal of the resultant cell debris. Successful verification of this USD approach is achieved using pilot scale high-pressure homogenization and pilot scale, continuous flow, disc stack centrifugation comparing performance parameters such as the fraction of Fab' release, cell debris size distribution and the carryover of cell debris fine particles in the supernatant. The integration of fermentation and primary recovery stages is examined using USD monitoring of different phases of cell growth. Increasing susceptibility of the cells to disruption is observed with time following induction. For a given recovery process this results in a higher fraction of product release and a greater proportion of fine cell debris particles that are difficult to remove by centrifugation. Such observations are confirmed at pilot scale. Copyright © 2013 Wiley Periodicals, Inc.

Impact of crema on the aroma release and the in-mouth sensory perception of espresso coffee.

PubMed

Barron, D; Pineau, N; Matthey-Doret, W; Ali, S; Sudre, J; Germain, J C; Kolodziejczyk, E; Pollien, P; Labbe, D; Jarisch, C; Dugas, V; Hartmann, C; Folmer, B

2012-09-01

A set of six espresso coffees with different foam characteristics and similar above cup and in-mouth flavour sensory profiles was produced by combination of two varying parameters, the extraction pressure and the filtration of the coffee beverage. The coffees were subsequently evaluated in a comparative manner by a set of analytical (headspace, nose-space) and sensory (Temporal Dominance of Sensations) techniques. The presence of espresso crema in its standard quantity was demonstrated to be associated with the optimum release of pleasant high volatiles, both in the above cup headspace and in-mouth. On the other hand, the TDS study demonstrated that increasing amount of crema was associated with increasing roasted dominance along coffee consumption. Furthermore, a parallel was established between the roasted sensory dominance and the dominant release of 2-methylfuran in the nose-space. This was, however, an indirect link as 2-methylfuran was indeed a chemical marker of roasting but does not contribute to the roasted aroma. Lowering the standard amount of crema by filtration clearly decreased the release of pleasant high volatiles and the in-mouth roasted sensory dominance. On the other hand, increasing the usual crema volume by increasing the extraction pressure did not bring any added value concerning the above cup and in-mouth release of pleasant high volatiles.

The 30-year evolution of airway pressure release ventilation (APRV).

PubMed

Jain, Sumeet V; Kollisch-Singule, Michaela; Sadowitz, Benjamin; Dombert, Luke; Satalin, Josh; Andrews, Penny; Gatto, Louis A; Nieman, Gary F; Habashi, Nader M

2016-12-01

Airway pressure release ventilation (APRV) was first described in 1987 and defined as continuous positive airway pressure (CPAP) with a brief release while allowing the patient to spontaneously breathe throughout the respiratory cycle. The current understanding of the optimal strategy to minimize ventilator-induced lung injury is to "open the lung and keep it open". APRV should be ideal for this strategy with the prolonged CPAP duration recruiting the lung and the minimal release duration preventing lung collapse. However, APRV is inconsistently defined with significant variation in the settings used in experimental studies and in clinical practice. The goal of this review was to analyze the published literature and determine APRV efficacy as a lung-protective strategy. We reviewed all original articles in which the authors stated that APRV was used. The primary analysis was to correlate APRV settings with physiologic and clinical outcomes. Results showed that there was tremendous variation in settings that were all defined as APRV, particularly CPAP and release phase duration and the parameters used to guide these settings. Thus, it was impossible to assess efficacy of a single strategy since almost none of the APRV settings were identical. Therefore, we divided all APRV studies divided into two basic categories: (1) fixed-setting APRV (F-APRV) in which the release phase is set and left constant; and (2) personalized-APRV (P-APRV) in which the release phase is set based on changes in lung mechanics using the slope of the expiratory flow curve. Results showed that in no study was there a statistically significant worse outcome with APRV, regardless of the settings (F-ARPV or P-APRV). Multiple studies demonstrated that P-APRV stabilizes alveoli and reduces the incidence of acute respiratory distress syndrome (ARDS) in clinically relevant animal models and in trauma patients. In conclusion, over the 30 years since the mode's inception there have been no strict criteria in defining a mechanical breath as being APRV. P-APRV has shown great promise as a highly lung-protective ventilation strategy.

Active suppression of vortex-driven combustion instability using controlled liquid-fuel injection

NASA Astrophysics Data System (ADS)

Pang, Bin

Combustion instabilities remain one of the most challenging problems encountered in developing propulsion and power systems. Large amplitude pressure oscillations, driven by unsteady heat release, can produce numerous detrimental effects. Most previous active control studies utilized gaseous fuels to suppress combustion instabilities. However, using liquid fuel to suppress combustion instabilities is more realistic for propulsion applications. Active instability suppression in vortex-driven combustors using a direct liquid fuel injection strategy was theoretically established and experimentally demonstrated in this dissertation work. Droplet size measurements revealed that with pulsed fuel injection management, fuel droplet size could be modulated periodically. Consequently, desired heat release fluctuation could be created. If this oscillatory heat release is coupled with the natural pressure oscillation in an out of phase manner, combustion instabilities can be suppressed. To identify proper locations of supplying additional liquid fuel for the purpose of achieving control, the natural heat release pattern in a vortex-driven combustor was characterized in this study. It was found that at high Damkohler number oscillatory heat release pattern closely followed the evolving vortex front. However, when Damkohler number became close to unity, heat release fluctuation wave no longer coincided with the coherent structures. A heat release deficit area was found near the dump plane when combustor was operated in lean premixed conditions. Active combustion instability suppression experiments were performed in a dump combustor using a controlled liquid fuel injection strategy. High-speed Schlieren results illustrated that vortex shedding plays an important role in maintaining self-sustained combustion instabilities. Complete combustion instability control requires total suppression of these large-scale coherent structures. The sound pressure level at the excited dominant frequency was reduced by more than 20 dB with controlled liquid fuel injection method. Scaling issues were also investigated in this dump combustor to test the effectiveness of using pulsed liquid fuel injection strategies to suppress instabilities at higher power output conditions. With the liquid fuel injection control method, it was possible to suppress strong instabilities with initial amplitude of +/-5 psi down to the background noise level. The stable combustor operating range was also expanded from equivalence ratio of 0.75 to beyond 0.9.

Pseudotumour Cerebri Presentation in a Child Under the Gonadotropin-Releasing Hormone Agonist Treatment

PubMed Central

Gül, Ülkü; Kaçar Bayram, Ayşe; Kendirci, Mustafa; Hatipoğlu, Nihal; Okdemir, Deniz; Gümüş, Hakan; Kurtoğlu, Selim

2016-01-01

Gonadotropin-releasing hormone analogues are common treatment option in central precocious puberty in childhood as well as in endometriosis, infertility, and prostate cancer in adults. Pseudotumor cerebri is a rare side effect observed in adults. We present the case of a girl with precocious puberty treated with triptorelin acetate who developed pseudotumor cerebri after the 4th dose. She had headaches, and her blood pressure was detected to be above the 99 percentile. There were no causes underlying of hypertension such as cardiac, renal, or endocrine. Neurological examination was normal except bilateral papilledema. Cranial magnetic resonance imaging was normal. Cerebrospinal fluid (CSF) opening pressure was elevated. Triptorelin therapy was ceased and acetazolamide was applied; CSF pressure returned to normal. We observed pseudotumor cerebri after precocious puberty treatment, a finding for the first time ever seen in childhood. PMID:27087351

Let's Weigh in on "Deflategate"

NASA Astrophysics Data System (ADS)

Toepker, Terrence

2016-09-01

The September 2015 paper "Bouncing Back from `Deflategate'" is a very interesting article from a physics viewpoint. However, we doubt that the National Football League (NFL) officials will bounce footballs and measure the coefficient of restitution to verify that the footballs remain properly inflated. The release of a few pounds per square inch (psi) from a football seems trivial until one reads about the millions of dollars in suspensions, fines, and legal fees that were accrued. What is a possible solution that the NFL might actually use? Weigh the ball! When a small amount of air is deliberately released, causing a change in pressure, the change in mass can be calculated and measured. Note that the change in mass can be measured without making another pressure measurement. This is important because the reinsertion of the needle of the gauge to make another measurement causes a small inadvertent loss of pressure and mass from the ball.

Trapping guests within a nanoporous metal-organic framework through pressure-induced amorphization.

PubMed

Chapman, Karena W; Sava, Dorina F; Halder, Gregory J; Chupas, Peter J; Nenoff, Tina M

2011-11-23

The release of guest species from within a nanoporous metal-organic framework (MOF) has been inhibited by amorphization of the guest-loaded framework structure under applied pressure. Thermogravimetric analyses have shown that by amorphizing ZIF-8 following sorption of molecular I(2), a hazardous radiological byproduct of nuclear energy production, the pore apertures in the framework are sufficiently distorted to kinetically trap I(2) and improve I(2) retention. Pair distribution function (PDF) analysis indicates that the local structure of the captive I(2) remains essentially unchanged upon amorphization of the framework, with the amorphization occurring under the same conditions for the vacant and guest-loaded framework. The low, accessible pressure range needed to effect this change in desorption is much lower than in tradition sorbents such as zeolites, opening the possibility for new molecular capture, interim storage, or controlled release applications.

Microfabricated Nickel Based Sensors for Hostile and High Pressure Environments

NASA Astrophysics Data System (ADS)

Holt, Christopher Michael Bjustrom

This thesis outlines the development of two platforms for integrating microfabricated sensors with high pressure feedthroughs for application in hostile high temperature high pressure environments. An application in oil well production logging is explored and two sensors were implemented with these platforms for application in an oil well. The first platform developed involved microfabrication directly onto a cut and polished high pressure feedthrough. This technique enables a system that is more robust than the wire bonded silicon die technique used for MEMS integration in pressure sensors. Removing wire bonds from the traditional MEMS package allows for direct interface of a microfabricated sensor with a hostile high pressure fluid environment which is not currently possible. During the development of this platform key performance metrics included pressure testing to 70MPa and temperature cycling from 20°C to 200°C. This platform enables electronics integration with a variety of microfabricated electrical and thermal based sensors which can be immersed within the oil well environment. The second platform enabled free space fabrication of nickel microfabricated devices onto an array of pins using a thick tin sacrificial layer. This technique allowed microfabrication of metal MEMS that are released by distances of 1cm from their substrate. This method is quite flexible and allows for fabrication to be done on any pin array substrate regardless of surface quality. Being able to place released MEMS sensors directly onto traditional style circuit boards, ceramic circuit boards, electrical connectors, ribbon cables, pin headers, or high pressure feedthroughs greatly improves the variety of possible applications and reduces fabrication costs. These two platforms were then used to fabricate thermal conductivity sensors that showed excellent performance for distinguishing between oil, water, and gas phases. Testing was conducted at various flow rates and performance of the released platform was shown to be better than the performance seen in the anchored sensors while both platforms were significantly better than a simply fabricated wrapped wire sensor. The anchored platform was also used to demonstrate a traditional capacitance based fluid dielectric sensor which was found to work similarly to conventional commercial capacitance probes while being significantly smaller in size.

Characterization of In Vitro Release of Neurochemicals from the Intermediate Area of the Rat Thoracic Spinal Cord: Regulation by Coexisting Neurochemical and Presynaptic Autoreceptors

DTIC Science & Technology

1995-06-16

university of the Health Sciences ABSTRACT serotonin (5-HT), substance P (SP), neurokinin A (NKA) and thyrotropin-releasing hormone (TRH) coexist in the...intermediolateral cell column IML pars funiculars IML pars principal is immunoreactivity mean arterial pressure neurokinin A neurokinin B nucleus tractus...thyrotropin-releasing hormone (TRH) and neurokinin A (NKA) coexist in these IML-projecting neurons. We propose that each of these colocalized

Apparatus for passive removal of subsurface contaminants

DOEpatents

Pemberton, Bradley E.; May, Christopher P.; Rossabi, Joseph

1997-01-01

An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere.

Apparatus for passive removal of subsurface contaminants

DOEpatents

Pemberton, B.E.; May, C.P.; Rossabi, J.

1997-06-24

An apparatus is provided which passively removes contaminated gases from a subsurface. The apparatus includes a riser pipe extending into a subsurface which has an exterior end in fluid communication with a valve. When well pressure is greater than atmospheric pressure, the valve opens to release contaminants into the atmosphere, and when well pressure is less than atmospheric pressure, the valve closes to prevent flow of air into the well. The valve assembly of the invention comprises a lightweight ball which is lifted from its valve seat with a slight pressure drop between the well and the atmosphere. 7 figs.

Optimizing an Experimental System for Assessing the Amounts and Forms of Copper Released into Aquatic Systems from Commercially Available Liquid and Micronized Pressure Treated Lumber

EPA Science Inventory

The fate and effects of pristine engineered metal nanomaterials (ENMs) in simplified systems have been widely studied; however, little is known about the potential release and impact of metal ENMs from consumer goods, especially lumber which has been treated with micronized coppe...

76 FR 2605 - Airworthiness Directives; Rolls-Royce plc RB211-Trent 800 Series Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-14

... blade root lubrication coating system may be reduced dependant on the extent of previous running with... Trent 895 powered Boeing 777-200 aircraft experienced release of a low pressure (LP) compressor blade which failed due to fatigue cracking in the root section of the blade. The released blade (undercut root...

Biocompatibility and antifibrotic effect of UV-cross-linked hyaluronate as a release-system for tranilast after trabeculectomy in a rabbit model--a pilot study.

PubMed

Spitzer, Martin S; Sat, Macarena; Schramm, Charlotte; Schnichels, Sven; Schultheiss, Maximilian; Yoeruek, Efdal; Dzhelebov, Dimitar; Szurman, Peter

2012-06-01

To analyze the release kinetics and the clinical and histological effects of UV-cross-linked hyaluronic acid as a release-system for the transforming growth factor β-2 antagonist tranilast with anti-phlogistic properties on intraocular pressure after trabeculectomy in an aggressive scarring animal model. Hyaluronate acid was UV-cross linked and loaded with tranilast. The release of tranilast into a buffered salt solution was assessed spectrophotometrically. Glaucoma filtration surgery, similar to that performed in clinical practice, was performed on chinchilla rabbits. The rabbits were divided in 3 groups. (Group A: trabeculectomy alone, group B: trabeculectomy with a cross-linked hyaluronic acid gel preparation and group C: trabeculectomy with cross-linked hyaluronic gel preparation mixed with tranilast). Antifibrotic efficacy was established by clinical response and histologic examination. The cross-linked gels released tranilast for up to 26 h. The release plotted as a function of the square root of time was consistent with a largely diffusion-controlled release system. Both the gel preparation alone and the gel preparation mixed with tranilast were well tolerated in vivo. No adverse effects such as inflammation, corneal toxicity or blurring of the optical media were observed. The intraocular pressure reached preoperative levels within 9 days after surgery in control animals and group B, but remained significantly reduced (p = 0.00016) in the group with tranilast until day 22. The data of this pilot study suggest that the intraoperative application of UV-crossed linked hyaluronic acid used as a slow release system for tranilast may improve the surgical outcome of glaucoma filtration surgery.

On the formation of the tunnel valleys of the southern Laurentide ice sheet

USGS Publications Warehouse

Hooke, R. LeB; Jennings, C.E.

2006-01-01

Catastrophic releases of meltwater, produced by basal melting and stored for decades in subglacial reservoirs at high pressure, may have been responsible for eroding the broad, deep tunnel valleys that are common along the margins of some lobes of the southern Laurentide ice sheet. We surmise that these releases began when the high water pressure was transmitted to the margin through the substrate. The water pressure in the substrate at the margin would then have been significantly above the overburden pressure, leading to sapping failure. Headward erosion of a conduit in the substrate (piping) could then tap the stored water, resulting in the outburst. In some situations, development of a siphon may have lowered the reservoir below its overflow level, thus tapping additional water. Following the flood, the seal could have reformed and the reservoir refilled, setting up conditions for another outburst. Order of magnitude calculations suggest that once emptied, a subglacial reservoir could refill in a matter of decades. The amount of water released during several outbursts appears to be sufficient to erode a tunnel valley. We think that tunnel valleys are most likely to have formed in this way where and when the glacier margin was frozen to the bed and permafrost extended from the glacier forefield several kilometers back under the glacier, as reservoirs would then have been larger and more common, and the seal more robust and more likely to reform after an outburst. ?? 2006 Elsevier Ltd. All rights reserved.

Physicochemical and pharmacological investigation of water/oil microemulsion of non-selective beta blocker for treatment of glaucoma.

PubMed

Hegde, Rahul Rama; Bhattacharya, Shiv Sankar; Verma, Anurag; Ghosh, Amitava

2014-02-01

Ocular drug delivery system always remained associated with lots of difficulties and faced issues of poor drug absorption and poor bioavailability. Timolol maleate is a nonspecific beta blocker used for reduction of elevated intraocular pressure in glaucoma. Timolol maleate is absorbed systemically and is contraindicated in asthmatic patients. This study is focused to deliver Timolol maleate by a water/oil microemulsion to extend the time of reduced intraocular pressure of glaucomatous rabbit's eye measured by using a Schoetz tonometer. The microemulsion is prepared by mixing the oily components with two nonionic surfactants, drug and water, and evaluated for the physicochemical, in vitro and in vivo parameters. The colloidal system demonstrates monodisperse distribution behavior and exhibits a uniform size distribution of finite width. In vitro drug release from microemulsion was found to follow Higuchi's pattern followed by a zero-order drug release by the emulsion. Ex vivo permeation through goat cornea revealed delayed release of Timolol maleate from microemulsion as compared with its aqueous solution. A reduction in intraocular pressure is seen lasting for 12 h compared to aqueous eye drop that lasted for only 5 h. CONCLUSION. In vivo reduction of intraocular pressure revealed a similar efficacy for once daily dosed 0.3% Timolol maleate in microemulsion formulation compared to 0.5% concentration in both microemulsion as well as aqueous formulation. The possible outcome of dose reduction will reduce the cardiovascular side effects generally reported with Timolol maleate eye drops.

Cryogenic Impinging Jets Subjected to High Frequency Transverse Acoustic Forcing in a High Pressure Environment

DTIC Science & Technology

2016-07-27

Transverse Acoustic Forcing in a High Pressure Environment 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Mario ...Acoustic Forcing in a High Pressure Environment Mario Roa, Sierra Lobo, Inc. Alex Schumaker, AFRL Doug Talley, AFRL 24-27 July 2016 Joint Propulsion...Distribution A: Approved for Public Release; Distribution Unlimited. PA# 16333 9 Parametric Sweep Super -Critical Results Differences between

New National Blood Pressure Guidelines Are More Rigorous, but OHS Is Here to Help | Poster

Cancer.gov

A task force led by physicians from the American College of Cardiology and the American Heart Association has released new blood pressure guidelines in order to help doctors and clinicians better treat hypertensive and prehypertensive individuals who may be at risk of heart disease. The update, which comes nearly 15 years after its predecessor, has significantly broadened the definition of hypertension and reclassified other blood pressure categories.

The Human Sympathetic Nervous System Response to Spaceflight

NASA Technical Reports Server (NTRS)

Ertl, Andrew C.; Diedrich, Andre; Paranjape, Sachin Y.; Biaggioni, Italo; Robertson, Rose Marie; Lane, Lynda D.; Shiavi, Richard; Robertson, David

2003-01-01

The sympathetic nervous system is an important part of the autonomic (or automatic) nervous system. When an individual stands up, the sympathetic nervous system speeds the heart and constricts blood vessels to prevent a drop in blood pressure. A significant number of astronauts experience a drop in blood pressure when standing for prolonged periods after they return from spaceflight. Difficulty maintaining blood pressure with standing is also a daily problem for many patients. Indirect evidence available before the Neurolab mission suggested the problem in astronauts while in space might be due partially to reduced sympathetic nervous system activity. The purpose of this experiment was to identify whether sympathetic activity was reduced during spaceflight. Sympathetic nervous system activity can be determined in part by measuring heart rate, nerve activity going to blood vessels, and the release of the hormone norepinephrine into the blood. Norepinephrine is a neurotransmitter discharged from active sympathetic nerve terminals, so its rate of release can serve as a marker of sympathetic nervous system action. In addition to standard cardiovascular measurements (heart rate, blood pressure), we determined sympathetic nerve activity as well as norepinephrine release and clearance on four crewmembers on the Neurolab mission. Contrary to our expectation, the results demonstrated that the astronauts had mildly elevated resting sympathetic nervous system activity in space. Sympathetic nervous system responses to stresses that simulated the cardiovascular effects of standing (lower body negative pressure) were brisk both during and after spaceflight. We concluded that, in the astronauts tested, the activity and response of the sympathetic nervous system to cardiovascular stresses appeared intact and mildly elevated both during and after spaceflight. These changes returned to normal within a few days.

77 FR 16917 - Airworthiness Directives; Rolls-Royce Deutschland Ltd & Co KG Turbofan Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-23

... turbofan engines. This AD requires replacement of the high-pressure (HP) turbine spanner retaining nut... stage 2 high-pressure turbine (HPT) disc spanner retaining nuts did not receive the proper heat... HPT disc failure, possibly leading to release of high energy debris, resulting in damage to the...

Estimating Dermal Transfer of Copper Particles from the Surfaces of Pressure-Treated Lumber and Implications for Exposure

EPA Science Inventory

Lumber pressure-treated with micronized copper was examined for the release of copper and copper micro/nanoparticles using a surface wipe method to simulate dermal transfer. In 2003, the wood industry began replacing CCA treated lumber products for residential use with copper ba...

Structural integrity of a confinement vessel for testing nuclear fuels for space propulsion

NASA Astrophysics Data System (ADS)

Bergmann, V. L.

Nuclear propulsion systems for rockets could significantly reduce the travel time to distant destinations in space. However, long before such a concept can become reality, a significant effort must be invested in analysis and ground testing to guide the development of nuclear fuels. Any testing in support of development of nuclear fuels for space propulsion must be safely contained to prevent the release of radioactive materials. This paper describes analyses performed to assess the structural integrity of a test confinement vessel. The confinement structure, a stainless steel pressure vessel with bolted flanges, was designed for operating static pressures in accordance with the ASME Boiler and Pressure Vessel Code. In addition to the static operating pressures, the confinement barrier must withstand static overpressures from off-normal conditions without releasing radioactive material. Results from axisymmetric finite element analyses are used to evaluate the response of the confinement structure under design and accident conditions. For the static design conditions, the stresses computed from the ASME code are compared with the stresses computed by the finite element method.

Synthesis of hydrogen-carbon clathrate material and hydrogen evolution therefrom at moderate temperatures and pressures

DOEpatents

Lueking, Angela [State College, PA; Narayanan, Deepa [Redmond, WA

2011-03-08

A process for making a hydrogenated carbon material is provided which includes forming a mixture of a carbon source, particularly a carbonaceous material, and a hydrogen source. The mixture is reacted under reaction conditions such that hydrogen is generated and/or released from the hydrogen source, an amorphous diamond-like carbon is formed, and at least a portion of the generated and/or released hydrogen associates with the amorphous diamond-like carbon, thereby forming a hydrogenated carbon material. A hydrogenated carbon material including a hydrogen carbon clathrate is characterized by evolution of molecular hydrogen at room temperature at atmospheric pressure in particular embodiments of methods and compositions according to the present invention.

Influence of magnetic pressure on stellar structure: A Mechanism for solar variability

NASA Technical Reports Server (NTRS)

Schatten, K. H.; Endal, A. S.

1980-01-01

A physical mechanism is proposed that couples the Sun's dynamo magnetic field to its gravitational potential energy. The mechanism involves the isotropic field pressure resulting in a lifting force on the convective envelope, thereby raising its potential energy. Decay of the field due to solar activity allows the envelop to subside and releases this energy, which can augment the otherwise steady solar luminosity. Equations are developed and applied to the Sun for several field configurations. The best estimate model suggests that uniform luminosity variations as large as 0.02% for half a sunspot cycle may occur. Brief temporal variations or the rotation of spatial structures could allow larger excursions in the energy released.

Effect of Pressure Gradients on the Initiation of PBX-9502 via Irregular (Mach) Reflection of Low Pressure Curved Shock Waves

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

Hull, Lawrence Mark; Miller, Phillip Isaac; Moro, Erik Allan

In the instance of multiple fragment impact on cased explosive, isolated curved shocks are generated in the explosive. These curved shocks propagate and may interact and form irregular or Mach reflections along the interaction loci, thereby producing a single shock that may be sufficient to initiate PBX-9501. However, the incident shocks are divergent and their intensity generally decreases as they expand, and the regions behind the Mach stem interaction loci are generally unsupported and allow release waves to rapidly affect the flow. The effects of release waves and divergent shocks may be considered theoretically through a “Shock Change Equation”.

Solar wind control of magnetospheric pressure (CDAW 6)

NASA Technical Reports Server (NTRS)

Fairfield, D. H.

1985-01-01

The CDAW 6 data base is used to compare solar wind and magnetospheric pressures. The flaring angle of the tail magnetopause is determined by assuming that the component of solar wind pressure normal to the tail boundary is equal to the total pressure within the tail. Results indicate an increase in the tail flaring angle from 18 deg to 32 deg prior to the 1055 substorm onset and a decrease to 25 deg after the onset. This behavior supports the concept of tail energy storage before the substorm and subsequent release after the onset.

Controlled release of basic fibroblast growth factor for angiogenesis using acoustically-responsive scaffolds.

PubMed

Moncion, Alexander; Lin, Melissa; O'Neill, Eric G; Franceschi, Renny T; Kripfgans, Oliver D; Putnam, Andrew J; Fabiilli, Mario L

2017-09-01

The clinical translation of pro-angiogenic growth factors for treatment of vascular disease has remained a challenge due to safety and efficacy concerns. Various approaches have been used to design spatiotemporally-controlled delivery systems for growth factors in order to recapitulate aspects of endogenous signaling and thus assist in translation. We have developed acoustically-responsive scaffolds (ARSs), which are fibrin scaffolds doped with a payload-containing, sonosensitive emulsion. Payload release can be controlled non-invasively and in an on-demand manner using focused, megahertz-range ultrasound (US). In this study, we investigate the in vitro and in vivo release from ARSs containing basic fibroblast growth factor (bFGF) encapsulated in monodispersed emulsions. Emulsions were generated in a two-step process utilizing a microfluidic device with a flow focusing geometry. At 2.5 MHz, controlled release of bFGF was observed for US pressures above 2.2 ± 0.2 MPa peak rarefactional pressure. Superthreshold US yielded a 12.6-fold increase in bFGF release in vitro. The bioactivity of the released bFGF was also characterized. When implanted subcutaneously in mice, ARSs exposed to superthreshold US displayed up to 3.3-fold and 1.7-fold greater perfusion and blood vessel density, respectively, than ARSs without US exposure. Scaffold degradation was not impacted by US. These results highlight the utility of ARSs in both basic and applied studies of therapeutic angiogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Large Scale Flame Spread Environmental Characterization Testing

NASA Technical Reports Server (NTRS)

Clayman, Lauren K.; Olson, Sandra L.; Gokoghi, Suleyman A.; Brooker, John E.; Ferkul, Paul V.; Kacher, Henry F.

2013-01-01

Under the Advanced Exploration Systems (AES) Spacecraft Fire Safety Demonstration Project (SFSDP), as a risk mitigation activity in support of the development of a large-scale fire demonstration experiment in microgravity, flame-spread tests were conducted in normal gravity on thin, cellulose-based fuels in a sealed chamber. The primary objective of the tests was to measure pressure rise in a chamber as sample material, burning direction (upward/downward), total heat release, heat release rate, and heat loss mechanisms were varied between tests. A Design of Experiments (DOE) method was imposed to produce an array of tests from a fixed set of constraints and a coupled response model was developed. Supplementary tests were run without experimental design to additionally vary select parameters such as initial chamber pressure. The starting chamber pressure for each test was set below atmospheric to prevent chamber overpressure. Bottom ignition, or upward propagating burns, produced rapid acceleratory turbulent flame spread. Pressure rise in the chamber increases as the amount of fuel burned increases mainly because of the larger amount of heat generation and, to a much smaller extent, due to the increase in gaseous number of moles. Top ignition, or downward propagating burns, produced a steady flame spread with a very small flat flame across the burning edge. Steady-state pressure is achieved during downward flame spread as the pressure rises and plateaus. This indicates that the heat generation by the flame matches the heat loss to surroundings during the longer, slower downward burns. One heat loss mechanism included mounting a heat exchanger directly above the burning sample in the path of the plume to act as a heat sink and more efficiently dissipate the heat due to the combustion event. This proved an effective means for chamber overpressure mitigation for those tests producing the most total heat release and thusly was determined to be a feasible mitigation strategy to incorporate into the microgravity experiment.

Stagnation pressure activated fuel release mechanism for hypersonic projectiles

DOEpatents

Cartland, Harry E.; Hunter, John W.

2003-01-01

A propulsion-assisted projectile has a body, a cowl forming a combustion section and a nozzle section. The body has a fuel reservoir within a central portion of the body, and a fuel activation system located along the central axis of the body and having a portion of the fuel activation system within the fuel reservoir. The fuel activation system has a fuel release piston with a forward sealing member where the fuel release piston is adapted to be moved when the forward sealing member is impacted with an air flow, and an air-flow channel adapted to conduct ambient air during flight to the fuel release piston.

Shock loading and release behavior of silicon nitride

NASA Astrophysics Data System (ADS)

Kawai, Nobuaki; Tsuru, Taiki; Hidaka, Naoto; Liu, Xun; Mashimo, Tsutomu

2015-06-01

Shock-reshock and shock-release experiments were performed on silicon nitride ceramics above and below its phase transition pressure. Experimental results clearly show the occurrence of elastic-plastic transition and phase transition during initial shock loading. The HEL and phase transition stress are determined as 11.6 GPa and 34.5 GPa, respectively. Below the phase transition point, the reshock profile consists of the single shock with short rise time, while the release profile shows the gradual release followed by more rapid one. Above the phase transition point, reshock and release behavior varies with the initial shock stress. In the case of reshock and release from about 40 GPa, the reshock structure is considerably dispersed, while the release structure shows rapid release. In the reshock profile from about 50 GPa, the formation of the shock wave with the small ramped precursor is observed. And, the release response from same condition shows initial gradual release and subsequent quite rapid one. These results would provide the information about how phase transformation kinetics effects on the reshock and release behavior.

Modeling of HT and HTO release from irradiated lithium metazirconate

NASA Astrophysics Data System (ADS)

Beloglazov, S.; Nishikawa, M.; Glugla, M.; Kinjyo, T.

2004-08-01

Modeling studies of tritium release from irradiated Li 2ZrO 3 (MAPI) pebbles have been carried out in order to evaluate the effect of purge gas composition on tritium release behavior. The release characteristics were obtained by temperature programmed desorption (TPD) technique in the series of post-irradiation experiments in JRR-4 research reactor of JAERI. Nitrogen with hydrogen at various partial pressures (100 and 1000 Pa) was used as a purge gas. Two sets of ionization chambers and its dedicated electrometers allowed the tritium concentration to be monitored in the chemical form of HT and overall tritium concentration in the mixture HT and HTO simultaneously during desorption runs. The tritium release curves were numerically fitted in order to evaluate the mass transfer coefficients.

Interpretation and modelling of fission product Ba and Mo releases from fuel

NASA Astrophysics Data System (ADS)

Brillant, G.

2010-02-01

The release mechanisms of two fission products (namely barium and molybdenum) in severe accident conditions are studied using the VERCORS experimental observations. Barium is observed to be mostly released under reducing conditions while molybdenum release is most observed under oxidizing conditions. As well, the volatility of some precipitates in fuel is evaluated by thermodynamic equilibrium calculations. The polymeric species (MoO 3) n are calculated to largely contribute to molybdenum partial pressure and barium volatility is greatly enhanced if the gas atmosphere is reducing. Analytical models of fission product release from fuel are proposed for barium and molybdenum. Finally, these models have been integrated in the ASTEC/ELSA code and validation calculations have been performed on several experimental tests.

76 FR 24798 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 875-17, RB211-Trent 877-17, RB211...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-03

... blade root lubrication coating system may be reduced dependant on the extent of previous running with... Trent 895 powered Boeing 777-200 aircraft experienced release of a low pressure (LP) compressor blade which failed due to fatigue cracking in the root section of the blade. The released blade (undercut root...

Differential retention and release of CO 2 and CH 4 in kerogen nanopores: Implications for gas extraction and carbon sequestration

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

Ho, Tuan Anh; Wang, Yifeng; Xiong, Yongliang

Methane (CH 4) and carbon dioxide (CO 2), the two major components generated from kerogen maturation, are stored dominantly in nanometer-sized pores in shale matrix as (1) a compressed gas, (2) an adsorbed surface species and/or (3) a species dissolved in pore water (H 2O). In addition, supercritical CO 2 has been proposed as a fracturing fluid for simultaneous enhanced oil/gas recovery (EOR) and carbon sequestration. A mechanistic understanding of CH 4-CO 2-H 2O interactions in shale nanopores is critical for designing effective operational processes. Using molecular simulations, we show that kerogen preferentially retains CO 2 over CH 4 andmore » that the majority of CO 2 either generated during kerogen maturation or injected in EOR will remain trapped in the kerogen matrix. The trapped CO 2 may be released only if the reservoir pressure drops below the supercritical CO 2 pressure. When water is present in the kerogen matrix, it may block CH 4 release. Furthermore, the addition of CO 2 may enhance CH 4 release because CO 2 can diffuse through water and exchange for adsorbed methane in the kerogen nanopores.« less

Intravenous nitroglycerin for controlled cord traction in the management of retained placenta.

PubMed

Visalyaputra, Shusee; Prechapanich, Japarath; Suwanvichai, Sukanya; Yimyam, Suwimol; Permpolprasert, Ladda; Suksopee, Pattipa

2011-02-01

To determine the effect of 200 μg of intravenous nitroglycerin in the release of retained placenta by controlled cord traction. In this randomized controlled study, 40 women with a placenta retained for 30 minutes received intravenously 200 μg of nitroglycerin or a normal saline solution before umbilical cord traction was initiated. The rates of successful removal of the retained placenta in the study (n=20) and control (n=20) groups were compared, as were blood pressure, pulse rate, blood loss, and adverse effects. The placenta was released in only 15% and 20% of the participants in the study and control group, respectively. The remainder of the participants required general anesthesia and manual removal of the retained placenta regardless of group assignation. Blood pressure fell in significantly more women in the study group, but there were no differences in estimated blood loss or minor adverse effects. Intravenously administered nitroglycerin did not facilitate the release of retained placenta by umbilical cord traction. However, cord traction may be performed longer than 30 minutes to attempt releasing the placenta before operative manual removal is initiated. Copyright © 2010 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

The higher exercise intensity and the presence of allele I of ACE gene elicit a higher post-exercise blood pressure reduction and nitric oxide release in elderly women: an experimental study.

PubMed

Santana, Hugo A P; Moreira, Sérgio R; Neto, Willson B; Silva, Carla B; Sales, Marcelo M; Oliveira, Vanessa N; Asano, Ricardo Y; Espíndola, Foued S; Nóbrega, Otávio T; Campbell, Carmen S G; Simões, Herbert G

2011-12-02

The absence of the I allele of the angiotensin converting enzyme (ACE) gene has been associated with higher levels of circulating ACE, lower nitric oxide (NO) release and hypertension. The purposes of this study were to analyze the post-exercise salivary nitrite (NO2-) and blood pressure (BP) responses to different exercise intensities in elderly women divided according to their ACE genotype. Participants (n = 30; II/ID = 20 and DD = 10) underwent three experimental sessions: incremental test - IT (15 watts workload increase/3 min) until exhaustion; 20 min exercise 90% anaerobic threshold (90% AT); and 20 min control session without exercise. Volunteers had their BP and NO2- measured before and after experimental sessions. Despite both intensities showed protective effect on preventing the increase of BP during post-exercise recovery compared to control, post-exercise hypotension and increased NO2- release was observed only for carriers of the I allele (p < 0.05). Genotypes of the ACE gene may exert a role in post-exercise NO release and BP response.

Ultrasound-enhanced drug delivery for cancer.

PubMed

Mo, Steven; Coussios, Constantin-C; Seymour, Len; Carlisle, Robert

2012-12-01

Ultrasound, which has traditionally been used as a diagnostic tool, is increasingly being used in non-invasive therapy and drug delivery. Of particular interest to this review is the rapidly accumulating evidence that ultrasound may have a key role to play both in improving the targeting and the efficacy of drug delivery for cancer. Currently available ultrasound-triggerable vehicles are first described, with particular reference to the ultrasonic mechanism that can activate release and the suitability of the size range of the vehicle used for drug delivery. Further mechanical and thermal effects of ultrasound that can enhance extravasation and drug distribution following release are then critically reviewed. Acoustic cavitation is found to play a potentially key role both in achieving targeted drug release and enhanced extravasation at modest pressure amplitudes and acoustic energies, whilst simultaneously enabling real-time monitoring of the drug delivery process. The next challenge in ultrasound-enhanced drug delivery will thus be to develop a new generation of drug-carrying nanoparticles which are of the right size range for delivery to tumours, yet still capable of achieving initiation of cavitation activity and drug release at modest acoustic pressures and energies that have no safety implications for the patient.

Differential retention and release of CO 2 and CH 4 in kerogen nanopores: Implications for gas extraction and carbon sequestration

DOE PAGES

Ho, Tuan Anh; Wang, Yifeng; Xiong, Yongliang; ...

2018-02-06

Methane (CH 4) and carbon dioxide (CO 2), the two major components generated from kerogen maturation, are stored dominantly in nanometer-sized pores in shale matrix as (1) a compressed gas, (2) an adsorbed surface species and/or (3) a species dissolved in pore water (H 2O). In addition, supercritical CO 2 has been proposed as a fracturing fluid for simultaneous enhanced oil/gas recovery (EOR) and carbon sequestration. A mechanistic understanding of CH 4-CO 2-H 2O interactions in shale nanopores is critical for designing effective operational processes. Using molecular simulations, we show that kerogen preferentially retains CO 2 over CH 4 andmore » that the majority of CO 2 either generated during kerogen maturation or injected in EOR will remain trapped in the kerogen matrix. The trapped CO 2 may be released only if the reservoir pressure drops below the supercritical CO 2 pressure. When water is present in the kerogen matrix, it may block CH 4 release. Furthermore, the addition of CO 2 may enhance CH 4 release because CO 2 can diffuse through water and exchange for adsorbed methane in the kerogen nanopores.« less

Correlation of combustor acoustic power levels inferred from internal fluctuating pressure measurements

NASA Technical Reports Server (NTRS)

Vonglahn, U. H.

1978-01-01

Combustion chamber acoustic power levels inferred from internal fluctuating pressure measurements are correlated with operating conditions and chamber geometries over a wide range. The variables include considerations of chamber design (can, annular, and reverse-flow annular) and size, number of fuel nozzles, burner staging and fuel split, airflow and heat release rates, and chamber inlet pressure and temperature levels. The correlated data include those obtained with combustion component development rigs as well as engines.

The application of the high-speed photography in the experiments of boiling liquid expanding vapor explosions

NASA Astrophysics Data System (ADS)

Chen, Sining; Sun, Jinhua; Chen, Dongliang

2007-01-01

The liquefied-petroleum gas tank in some failure situations may release its contents, and then a series of hazards with different degrees of severity may occur. The most dangerous accident is the boiling liquid expanding vapor explosion (BLEVE). In this paper, a small-scale experiment was established to experimentally investigate the possible processes that could lead to a BLEVE. As there is some danger in using LPG in the experiments, water was used as the test fluid. The change of pressure and temperature was measured during the experiment. The ejection of the vapor and the sequent two-phase flow were recorded by a high-speed video camera. It was observed that two pressure peaks result after the pressure is released. The vapor was first ejected at a high speed; there was a sudden pressure drop which made the liquid superheated. The superheated liquid then boiled violently causing the liquid contents to swell, and also, the vapor pressure in the tank increased rapidly. The second pressure peak was possibly due to the swell of this two-phase flow which was likely to violently impact the wall of the tank with high speed. The whole evolution of the two-phase flow was recorded through photos captured by the high-speed video camera, and the "two step" BLEVE process was confirmed.

High pressure polymorphs and amorphization of upconversion host material NaY(WO 4) 2

DOE PAGES

Hong, Fang; Yue, Binbin; Cheng, Zhenxiang; ...

2016-07-29

The pressure effect on the structural change of upconversion host material NaY(WO 4) 2 was studied in this paper by using in-situ synchrotron X-ray diffraction. A transition from the initial scheelite phase to the M-fergusonite phase occurs near 10 GPa, and another phase transition is found near 27.5 GPa, which could be an isostructural transition without symmetry change. The sample becomes amorphous when the pressure is fully released from high pressure. Finally, this work demonstrates the possibility of synthesizing various polymorph structures for non-linear optical applications with a high pressure, chemical doping, or strained thin-film nanostructure process.

Reversible Morphological Control of Tubulin-Encapsulating Giant Liposomes by Hydrostatic Pressure.

PubMed

Hayashi, Masahito; Nishiyama, Masayoshi; Kazayama, Yuki; Toyota, Taro; Harada, Yoshie; Takiguchi, Kingo

2016-04-19

Liposomes encapsulating cytoskeletons have drawn much recent attention to develop an artificial cell-like chemical-machinery; however, as far as we know, there has been no report showing isothermally reversible morphological changes of liposomes containing cytoskeletons because the sets of various regulatory factors, that is, their interacting proteins, are required to control the state of every reaction system of cytoskeletons. Here we focused on hydrostatic pressure to control the polymerization state of microtubules (MTs) within cell-sized giant liposomes (diameters ∼10 μm). MT is the cytoskeleton formed by the polymerization of tubulin, and cytoskeletal systems consisting of MTs are very dynamic and play many important roles in living cells, such as the morphogenesis of nerve cells and formation of the spindle apparatus during mitosis. Using real-time imaging with a high-pressure microscope, we examined the effects of hydrostatic pressure on the morphology of tubulin-encapsulating giant liposomes. At ambient pressure (0.1 MPa), many liposomes formed protrusions due to tubulin polymerization within them. When high pressure (60 MPa) was applied, the protrusions shrank within several tens of seconds. This process was repeatedly inducible (around three times), and after the pressure was released, the protrusions regenerated within several minutes. These deformation rates of the liposomes are close to the velocities of migrating or shape-changing living cells rather than the shortening and elongation rates of the single MTs, which have been previously measured. These results demonstrate that the elongation and shortening of protrusions of giant liposomes is repeatedly controllable by regulating the polymerization state of MTs within them by applying and releasing hydrostatic pressure.

Use of focused acoustics for cell disruption to provide ultra scale-down insights of microbial homogenization and its bioprocess impact--recovery of antibody fragments from rec E. coli.

PubMed

Li, Qiang; Aucamp, Jean P; Tang, Alison; Chatel, Alex; Hoare, Mike

2012-08-01

An ultra scale-down (USD) device that provides insight of how industrial homogenization impacts bioprocess performance is desirable in the biopharmaceutical industry, especially at the early stage of process development where only a small quantity of material is available. In this work, we assess the effectiveness of focused acoustics as the basis of an USD cell disruption method to mimic and study high-pressure, step-wise homogenization of rec Escherichia coli cells for the recovery of an intracellular protein, antibody fragment (Fab'). The release of both Fab' and of overall protein follows first-order reaction kinetics with respect to time of exposure to focused acoustics. The rate constant is directly proportional to applied electrical power input per unit volume. For nearly total protein or Fab' release (>99%), the key physical properties of the disruptate produced by focused acoustics, such as cell debris particle size distribution and apparent viscosity show good agreement with those for homogenates produced by high-pressure homogenization operated to give the same fractional release. The only key difference is observed for partial disruption of cells where focused acoustics yields a disruptate of lower viscosity than homogenization, evidently due to a greater extent of polynucleic acids degradation. Verification of this USD approach to cell disruption by high-pressure homogenization is achieved using USD centrifugation to demonstrate the same sedimentation characteristics of disruptates prepared using both the scaled-down focused acoustic and the pilot-scale homogenization methods for the same fraction of protein release. Copyright © 2012 Wiley Periodicals, Inc.

Exploring the Role of TRPV and CGRP in Adenosine Preconditioning and Remote Hind Limb Preconditioning-Induced Cardioprotection in Rats.

PubMed

Singh, Amritpal; Randhawa, Puneet Kaur; Bali, Anjana; Singh, Nirmal; Jaggi, Amteshwar Singh

2017-04-01

The cardioprotective effects of remote hind limb preconditioning (RIPC) are well known, but mechanisms by which protection occurs still remain to be explored. Therefore, the present study was designed to investigate the role of TRPV and CGRP in adenosine and remote preconditioning-induced cardioprotection, using sumatriptan, a CGRP release inhibitor and ruthenium red, a TRPV inhibitor, in rats. For remote preconditioning, a pressure cuff was tied around the hind limb of the rat and was inflated with air up to 150 mmHg to produce ischemia in the hind limb and during reperfusion pressure was released. Four cycles of ischemia and reperfusion, each consisting of 5 min of inflation and 5 min of deflation of pressure cuff were used to produce remote limb preconditioning. An ex vivo Langendorff's isolated rat heart model was used to induce ischemia reperfusion injury by 30 min of global ischemia followed by 120 min of reperfusion. RIPC demonstrated a significant decrease in ischemia reperfusion-induced significant myocardial injury in terms of increase in LDH, CK, infarct size and decrease in LVDP, +dp/dt max and -dp/dt min . Moreover, pharmacological preconditioning with adenosine produced cardioprotective effects in a similar manner to RIPC. Pretreatment with sumatriptan, a CGRP release blocker, abolished RIPC and adenosine preconditioning-induced cardioprotective effects. Administration of ruthenium red, a TRPV inhibitor, also abolished adenosine preconditioning-induced cardioprotection. It may be proposed that the cardioprotective effects of adenosine and remote preconditioning are possibly mediated through activation of a TRPV channels and consequent, release of CGRP.

Changes in solvation during DNA binding and cleavage are critical to altered specificity of the EcoRI endonuclease

PubMed Central

Robinson, Clifford R.; Sligar, Stephen G.

1998-01-01

Restriction endonucleases such as EcoRI bind and cleave DNA with great specificity and represent a paradigm for protein–DNA interactions and molecular recognition. Using osmotic pressure to induce water release, we demonstrate the participation of bound waters in the sequence discrimination of substrate DNA by EcoRI. Changes in solvation can play a critical role in directing sequence-specific DNA binding by EcoRI and are also crucial in assisting site discrimination during catalysis. By measuring the volume change for complex formation, we show that at the cognate sequence (GAATTC) EcoRI binding releases about 70 fewer water molecules than binding at an alternate DNA sequence (TAATTC), which differs by a single base pair. EcoRI complexation with nonspecific DNA releases substantially less water than either of these specific complexes. In cognate substrates (GAATTC) kcat decreases as osmotic pressure is increased, indicating the binding of about 30 water molecules accompanies the cleavage reaction. For the alternate substrate (TAATTC), release of about 40 water molecules accompanies the reaction, indicated by a dramatic acceleration of the rate when osmotic pressure is raised. These large differences in solvation effects demonstrate that water molecules can be key players in the molecular recognition process during both association and catalytic phases of the EcoRI reaction, acting to change the specificity of the enzyme. For both the protein–DNA complex and the transition state, there may be substantial conformational differences between cognate and alternate sites, accompanied by significant alterations in hydration and solvent accessibility. PMID:9482860

Design and characterization of fibrin-based acoustically responsive scaffolds for tissue engineering applications

PubMed Central

Moncion, Alexander; Arlotta, Keith J.; Kripfgans, Oliver D.; Fowlkes, J. Brian; Carson, Paul L.; Putnam, Andrew J.; Franceschi, Renny T.; Fabiilli, Mario L.

2015-01-01

Hydrogel scaffolds are used in tissue engineering as a delivery vehicle for regenerative growth factors (GFs). Spatiotemporal patterns of GF signaling are critical for tissue regeneration, yet most scaffolds afford limited control of GF release, especially after implantation. We previously demonstrated that acoustic droplet vaporization (ADV) can control GF release from a fibrin scaffold doped with a perfluorocarbon emulsion. This study investigates properties of the acoustically responsive scaffold (ARS) critical for further translation. At 2.5 MHz, ADV and inertial cavitation thresholds ranged from 1.5 – 3.0 MPa and 2.0 – 7.0 MPa peak rarefactional pressure, respectively, for ARSs of varying compositions. Viability of C3H10T1/2 cells, encapsulated in the ARS, did not decrease significantly for pressures below 4 MPa. ARSs with perfluorohexane emulsions displayed higher stability versus perfluoropentane emulsions, while surrogate payload release was minimal without ultrasound. These results enable the selection of ARS compositions and acoustic parameters needed for optimized spatiotemporal control. PMID:26526782

Making Mars habitable

NASA Technical Reports Server (NTRS)

Mckay, Christopher P.; Toon, Owen B.; Kasting, James F.

1991-01-01

The possibility is considered that the atmosphere and climate of Mars could be altered to allow terrestrial life forms, and possibly human beings, to survive on the surface. Production of CFCs or other greenhouse gases on Mars would warm the surface enough for the regolith and polar caps to release their CO2 and raise atmospheric pressure to 100 mbar. If a large regolith and polar CO2 reservoirs exist, the pressure would continue to rise on its own. If these are absent, additional CO2 would have to be released from carbonate minerals. At this point, perhaps between 100 and 100,000 yrs, Mars might be suitable for plants. If there is a mechanism for sequestering the reduced carbon, these plants could slowly transform the CO2 to produce an O2-rich atmosphere in perhaps 100,000 yrs. If sufficient N2 could be released from putative soil deposits and the CO2 level could be kept low enough, then a human-breathable atmosphere would be produced.

Development of a flyer design to perform plate impact shock-release-shock experiments on explosives

NASA Astrophysics Data System (ADS)

Finnegan, Simon; Ferguson, James; Millett, Jeremy; Goff, Michael

2017-06-01

A flyer design to generate a shock-release-shock loading history within a gas gun target was developed before being used to study the response of an HMX based explosive. The flyer consisted of two flyer plates separated by a vacuum gap. This created a rear free surface that, with correct material choice, allowed the target to release to close to ambient pressure between the initial shock and subsequent re-shock. The design was validated by impacting piezoelectric pin arrays to record the front flyer deformation. Shots were performed on PCTFE targets to record the shock states generated in an inert material prior to subjecting an HMX based explosive to the same loading. The response of the explosive to this loading history was recorded using magnetic particle velocity (PV) gauges embedded within the targets. The behavior during the run to detonation is compared with the response to sustained shocks at similar input pressures.

High burnup fuel behavior related to fission gas effects under reactivity initiated accidents (RIA) conditions

NASA Astrophysics Data System (ADS)

Lemoine, F.

1997-09-01

Specific aspects of irradiated fuel result from the increasing retention of gaseous and volatile fission products with burnup, which, under overpower conditions, can lead to solid fuel pressurization and swelling causing severe PCMI (pellet clad mechanical interaction). In order to assess the reliability of high burnup fuel under RIAs, experimental programs have been initiated which have provided important data concerning the transient fission gas behavior and the clad loading mechanisms. The importance of the rim zone is demonstrated based on three experiments resulting in clad failure at low enthalpy, which are explained by energetic considerations. High gas release in non-failure tests with low energy deposition underlines the importance of grain boundary and porosity gas. Measured final releases are strongly correlated to the microstructure evolution, depending on energy deposition, pulse width, initial and refabricated fuel rod design. Observed helium release can also increase internal pressure and gives hints to the gas behavior understanding.

Tibiofemoral contact mechanics following posterior root of medial meniscus tear, repair, meniscectomy, and allograft transplantation.

PubMed

Kim, Jin Goo; Lee, Yong Seuk; Bae, Tae Soo; Ha, Jeong Ku; Lee, Dong Hoon; Kim, Young Jae; Ra, Ho Jong

2013-09-01

The purposes of this study were to evaluate the effect on tibiofemoral contact mechanics of repair of the posterior root of the medial meniscus and the effect of meniscal allograft transplantation (MAT) with medial collateral ligament (MCL) release at different flexion angles. Ten fresh-frozen human cadaveric knees (five pairs) were used. A digital pressure sensor was inserted by capsulotomy, and experiments were performed serially under the following six conditions, that is, with an intact medial meniscus (normal controls), with a root tear, after root repair, after total meniscectomy, after MAT, and after MAT plus MCL release. During each experiment, knees were positioned at 0°, 30°, 60°, and 90° of flexion, and peak pressure (kPa) and contact area (cm2) were measured. At 0° of flexion, contact pressure did not differ among the six experimental settings. However, at 30° and 60° of flexion, contact pressure differed significantly between root tear and root repair specimens (p = 0.04 and 0.03, respectively), and between total meniscectomy and MAT specimens (p = 0.02 and 0.03, respectively). On the other hand, mean contact pressures were different between normal (476.7 ± 473.1 and 573.3 ± 479.1 kPa) and root repair (575.7 ± 357.8 and 598.6 ± 415.8), and between normal and MAT (635.7 ± 437.4 and 674.3 ± 533.2). At 0°, 30°, 60°, and 90° of flexion, contact areas differed significantly between normal and total meniscectomy specimens (p = 0.02, 0.01, 0.02, and 0.02, respectively), and between MAT and total meniscectomy specimens (p = 0.03, 0.02, 0.02, and 0.03, respectively). Contact areas differed significantly between root tear and root repair specimens at 60° of flexion (p = 0.04), and between normal control and root repair specimens at 60° and 90° of flexion (p = 0.03 and 0.04, respectively). The effects of MAT plus MCL release on contact mechanics were not different from the effects of MAT alone (n.s.). Both meniscal root repair and transplantation of meniscus improved contact mechanics, but it did not appear that repair of the meniscal root or transplantation of meniscus restores the biomechanical function back to normal level. The MAT plus MCL release was similar to those after MAT alone. Therefore, it is better to preserve meniscus and MCL release could be done during the MAT.

Metallic Hydrogen and Nano-Tube Magnets

NASA Technical Reports Server (NTRS)

Cole, John W.

2004-01-01

When hydrogen is subjected to enough pressure the atoms will be pressed into close enough proximity that each electron is no longer bound to a single proton. The research objectives is to find whether metallic hydrogen can be produced and once produced will the metallic hydrogen be metastable and remain in the metallic form when the pressure is released.

Development of a simultaneous Hugoniot and temperature measurement for preheated-metal shock experiments: melting temperatures of Ta at pressures of 100 GPa.

PubMed

Li, Jun; Zhou, Xianming; Li, Jiabo; Wu, Qiang; Cai, Lingcang; Dai, Chengda

2012-05-01

Equations of state of metals are important issues in earth science and planetary science. A major limitation of them is the lack of experimental data for determining pressure-volume and temperature of shocked metal simultaneously. By measuring them in a single experiment, a major source of systematic error is eliminated in determining from which shock pressure release pressure originates. Hence, a non-contact fast optical method was developed and demonstrated to simultaneously measure a Hugoniot pressure-volume (P(H)-V(H)) point and interfacial temperature T(R) on the release of Hugoniot pressure (P(R)) for preheated metals up to 1000 K. Experimental details in our investigation are (i) a Ni-Cr resistance coil field placed around the metal specimen to generate a controllable and stable heating source, (ii) a fiber-optic probe with an optical lens coupling system and optical pyrometer with ns time resolution to carry out non-contact fast optical measurements for determining P(H)-V(H) and T(R). The shock response of preheated tantalum (Ta) at 773 K was investigated in our work. Measured data for shock velocity versus particle velocity at an initial state of room temperature was in agreement with previous shock compression results, while the measured shock data between 248 and 307 GPa initially heated to 773 K were below the Hugoniot evaluation from its off-Hugoniot states. Obtained interfacial temperatures on release of Hugoniot pressures (100-170 GPa) were in agreement with shock-melting points at initial ambient condition and ab initio calculations of melting curve. It indicates a good consistency for shock melting data of Ta at different initial temperatures. Our combined diagnostics for Hugoniot and temperature provides an important approach for studying EOS and the temperature effect of shocked metals. In particular, our measured melting temperatures of Ta address the current controversy about the difference by more than a factor of 2 between the melting temperatures measured under shock and those measured in a laser-heated diamond anvil cell at ∼100 GPa.

Assessment of the effects of release variables on the consequences of LNG spillage onto water using FERC models.

PubMed

Qiao, Yuanhua; West, Harry H; Mannan, M Sam; Johnson, David W; Cornwell, John B

2006-03-17

Liquefied natural gas (LNG) release, spread, evaporation, and dispersion processes are illustrated using the Federal Energy Regulatory Commission models in this paper. The spillage consequences are dependent upon the tank conditions, release scenarios, and the environmental conditions. The effects of the contributing variables, including the tank configuration, breach hole size, ullage pressure, wind speed and stability class, and surface roughness, on the consequence of LNG spillage onto water are evaluated using the models. The sensitivities of the consequences to those variables are discussed.

A mathematical model for the release of noble gas and Cs from porous nuclear fuel based on VEGA 1&2 experiments

NASA Astrophysics Data System (ADS)

Simones, M. P.; Reinig, M. L.; Loyalka, S. K.

2014-05-01

Release of fission products from nuclear fuel in accidents is an issue of major concern in nuclear reactor safety, and there is considerable room for development of improved models, supported by experiments, as one needs to understand and elucidate role of various phenomena and parameters. The VEGA (Verification Experiments of radionuclides Gas/Aerosol release) program on several irradiated nuclear fuels investigated the release rates of radionuclides and results demonstrated that the release rates of radionuclides from all nuclear fuels tested decreased with increasing external gas pressure surrounding the fuel. Hidaka et al. (2004-2011) accounted for this pressure effect by developing a 2-stage diffusion model describing the transport of radionuclides in porous nuclear fuel. We have extended this 2-stage diffusion model to account for mutual binary gas diffusion in the open pores as well as to introduce the appropriate parameters to cover the slip flow regime (0.01 ⩽ Kn ⩽ 0.1). While we have directed our numerical efforts toward the simulation of the VEGA experiments and assessments of differences from the results of Hidaka et al., the model and the techniques reported here are of larger interest as these would aid in modeling of diffusion in general (e.g. in graphite and other nuclear materials of interest).

Quantitative risk assessment of CO2 transport by pipelines--a review of uncertainties and their impacts.

PubMed

Koornneef, Joris; Spruijt, Mark; Molag, Menso; Ramírez, Andrea; Turkenburg, Wim; Faaij, André

2010-05-15

A systematic assessment, based on an extensive literature review, of the impact of gaps and uncertainties on the results of quantitative risk assessments (QRAs) for CO(2) pipelines is presented. Sources of uncertainties that have been assessed are: failure rates, pipeline pressure, temperature, section length, diameter, orifice size, type and direction of release, meteorological conditions, jet diameter, vapour mass fraction in the release and the dose-effect relationship for CO(2). A sensitivity analysis with these parameters is performed using release, dispersion and impact models. The results show that the knowledge gaps and uncertainties have a large effect on the accuracy of the assessed risks of CO(2) pipelines. In this study it is found that the individual risk contour can vary between 0 and 204 m from the pipeline depending on assumptions made. In existing studies this range is found to be between <1m and 7.2 km. Mitigating the relevant risks is part of current practice, making them controllable. It is concluded that QRA for CO(2) pipelines can be improved by validation of release and dispersion models for high-pressure CO(2) releases, definition and adoption of a universal dose-effect relationship and development of a good practice guide for QRAs for CO(2) pipelines. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Preparation and in vitro evaluation of a new fentanyl patch based on acrylic/silicone pressure-sensitive adhesive blends.

PubMed

Taghizadeh, Seyed Mojtaba; Soroushnia, Arezou; Mirzadeh, Hamid; Barikani, Mehdi

2009-04-01

In this study, the influence of the ratio of silicone (Si) to acrylic pressure-sensitive adhesive (PSA), polyvinyl pyrrolidone (PVP), and lauryl alcohol (LA) % (wt/wt) on the properties of a drug in adhesive patch containing 4% (wt/wt) fentanyl as model drug was evaluated. The dependent variables selected were drug solubility, in vitro drug release in the platforms as well as adhesion properties including peel strength and tack value. By using the central composite design of Design Expert software, it was found that the effect of each factor was different, yet all had influenced dependent variables significantly (p < .05). Quadratic model generated for various response variables using backward regression analysis was found to be statistically significant (p < .05). It was deduced that the presence of PVP and Si displayed similar trends on drug solubility and release. Each role played by Si with LA and PVP in release rate was separately investigated, and it was found that the presence of PVP and LA in lowering the amount of drug released was more dominant compared with that of Si. The release patterns at the early and later stages follow the Higuchi and semiempirical models, respectively. Effect of PVP as well as Si and LA were similar on tack value. The influence of LA compared to peeling characteristics of Si system was more pronounced.

Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics

NASA Astrophysics Data System (ADS)

Makarieva, A. M.; Gorshkov, V. G.; Sheil, D.; Nobre, A. D.; Li, B.-L.

2013-01-01

Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 °C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the global mean power at which this potential energy is released by condensation is around one per cent of the global solar power - this is similar to the known stationary dissipative power of general atmospheric circulation. We conclude that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics.

Application of 5-Fluorouracil-Polycaprolactone Sustained-Release Film in Ahmed Glaucoma Valve Implantation Inhibits Postoperative Bleb Scarring in Rabbit Eyes.

PubMed

Bi, Xiu-Zeng; Pan, Wei-Hua; Yu, Xin-Ping; Song, Zong-Ming; Ren, Zeng-Jin; Sun, Min; Li, Cong-Hui; Nan, Kai-Hui

2015-01-01

This study was designed to investigate whether 5-fluorouracil (5-Fu)-polycaprolactone sustained-release film in Ahmed glaucoma valve implantation inhibits postoperative bleb scarring in rabbit eyes. Eighteen New Zealand white rabbits were randomly divided into three groups (A, B and C; n = 6 per group). Group A received combined 5-Fu-polycaprolactone sustained-release film application and Ahmed glaucoma valve implantation, group B received local infiltration of 5-Fu and Ahmed glaucoma valve implantation, and group C received Ahmed glaucoma valve implantation. Postoperative observations were made of the anterior segment, intraocular pressure, central anterior chamber depth, blebs, drainage tube, and accompanying ciliary body detachment. The pathology of the blebs and surrounding tissues were observed at month 3 postoperatively. We revealed that the 5-Fu-polycaprolactone sustained-release film maintained a release concentration range of 13.7 ± 0.12 to 37.41 ± 0.47 μg/ml over three months in vitro. Postoperatively, diffuse blebs with ridges were found in all eyes in group A, two blebs were observed in group B, and no bleb formation was present in group C. The postoperative central anterior chamber depth in group A was significantly less than that of the other two groups. The postoperative intraocular pressure of group A stabilized at 6.33-8.67 mmHg, whereas that of group C gradually remained at 7.55-10.02 mmHg. The histopathology showed that the fibrous tissue thickness of the blebs in group A was significantly thinner than that of the other groups. We conclude that the 5-Fu-polycaprolactone sustained-release film had a sustained drug release effect, which promoted the inhibition of bleb scarring after Ahmed glaucoma valve implantation.

Influence of low and high pressure baroreceptors on plasma renin activity in humans

NASA Technical Reports Server (NTRS)

Mark, A. L.; Abboud, F. M.; Fitz, A. E.

1977-01-01

The effects of low and high pressure baroreceptors on plasma renin activity (immunoassay) were evaluated using graded lower body suction (LBS) in six healthy men. LBS at -10 and -20 mmHg for 10 min decreased central venous pressure without changing arterial pressure and thereby presumably reduced low but not high pressure baroreceptor inhibition of renin release. LBS at these levels produced forearm vasoconstriction, but did not increase renin. LBS at -40 mmHG decreased central venous and arterial pulse pressure and thus reduced both low and high pressure baroreceptor inhibition. LBS at this level produced forearm vasoconstriction and tachycardia and increased renin. In summary, reduction in low pressure baroreceptor inhibition in humans did not increase renin in the presence of physiological tonic inhibition from high pressure baroreceptors. Increases in renin did not occur until there was combined reduction of high and low pressure baroreceptor inhibition on plasma renin activity.

Response mechanisms of attached premixed flames subjected to harmonic forcing

NASA Astrophysics Data System (ADS)

Shreekrishna

The persistent thrust for a cleaner, greener environment has prompted air pollution regulations to be enforced with increased stringency by environmental protection bodies all over the world. This has prompted gas turbine manufacturers to move from nonpremixed combustion to lean, premixed combustion. These lean premixed combustors operate quite fuel-lean compared to the stochiometric, in order to minimize CO and NOx productions, and are very susceptible to oscillations in any of the upstream flow variables. These oscillations cause the heat release rate of the flame to oscillate, which can engage one or more acoustic modes of the combustor or gas turbine components, and under certain conditions, lead to limit cycle oscillations. This phenomenon, called thermoacoustic instabilities, is characterized by very high pressure oscillations and increased heat fluxes at system walls, and can cause significant problems in the routine operability of these combustors, not to mention the occasional hardware damages that could occur, all of which cumulatively cost several millions of dollars. In a bid towards understanding this flow-flame interaction, this research works studies the heat release response of premixed flames to oscillations in reactant equivalence ratio, reactant velocity and pressure, under conditions where the flame preheat zone is convectively compact to these disturbances, using the G-equation. The heat release response is quantified by means of the flame transfer function and together with combustor acoustics, forms a critical component of the analytical models that can predict combustor dynamics. To this end, low excitation amplitude (linear) and high excitation amplitude (nonlinear) responses of the flame are studied in this work. The linear heat release response of lean, premixed flames are seen to be dominated by responses to velocity and equivalence ratio fluctuations at low frequencies, and to pressure fluctuations at high frequencies which are in the vicinity of typical screech frequencies in gas turbine combustors. The nonlinear response problem is exclusively studied in the case of equivalence ratio coupling. Various nonlinearity mechanisms are identified, amongst which the crossover mechanisms, viz., stoichiometric and flammability crossovers, are seen to be responsible in causing saturation in the overall heat release magnitude of the flame. The response physics remain the same across various preheat temperatures and reactant pressures. Finally, comparisons between the chemiluminescence transfer function obtained experimentally and the heat release transfer functions obtained from the reduced order model (ROM) are performed for lean, CH4/Air swirl-stabilized, axisymmetric V-flames. While the comparison between the phases of the experimental and theoretical transfer functions are encouraging, their magnitudes show disagreement at lower Strouhal number gains show disagreement.

Modeling PBX 9501 overdriven release experiments

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

Tang, P.K.

1997-11-01

High Explosives (HE) performs work by the expansion of its detonation products. Along with the propagation of the detonation wave, the equation of state (EOS) of the products determines the HE performance in an engineering system. The authors show the failure of the standard Jones-Wilkins-Lee (JWL) equation of state (EOS) in modeling the overdriven release experiments of PBX 9501. The deficiency can be tracked back to inability of the same EOS in matching the shock pressure and the sound speed on the Hugoniot in the hydrodynamic regime above the Chapman-Jouguet pressure. After adding correction terms to the principal isentrope ofmore » the standard JWL EOS, the authors are able to remedy this shortcoming and the simulation was successful.« less

Deployable pressurized cell structure for a micrometeoroid detector

NASA Technical Reports Server (NTRS)

Kinard, W. H. (Inventor)

1974-01-01

This disclosure comprises a plurality of individual pressurized cells which are caused to leak in response to a micrometeoroid penetration, the leak being sensed by appropriate instrumentation. The plurality of cells may be rolled into a compact arrangement such that the volume of the micrometeoroid detector is small and therefore readily packed in a payload of a launch vehicle. Once the payload is placed in orbit, the rolled up cells can be released, pressurized and provide a relatively rigid, large surface area for detecting micrometeoroid penetration.

Combustor oscillation attenuation via the control of fuel-supply line dynamics

DOEpatents

Richards, George A.; Gemmen, Randall S.

1998-01-01

Combustion oscillation control in combustion systems using hydrocarbon fuels is provided by acoustically tuning a fuel-delivery line to a desired phase of the combustion oscillations for providing a pulse of a fuel-rich region at the oscillating flame front at each time when the oscillation produced pressure in the combustion chamber is in a low pressure phase. The additional heat release produced by burning such fuel-rich regions during low combustion chamber pressure effectively attenuates the combustion oscillations to a selected value.

Effect of weathering on chromated copper arsenate (CCA) treated wood : leaching of metal salts and change in water repellency

Treesearch

R. Sam Williams; Stan Lebow; Patricia Lebow

2003-01-01

Wood pressure-treated with chromated copper arsenate (CCA) wood preservative is commonly used for outdoor construction. Oxides of arsenic, copper, and chromium are bound in the wood by a complex series of chemical reactions, but a small percentage of these compounds are gradually released by leaching and weathering. Recent studies suggest that the release of these...

Altitude release mechanism

DOEpatents

Kulhanek, Frank C.

1977-01-01

An altitude release mechanism for releasing a radiosonde or other measuring instrument from a balloon carrying it up into the atmosphere includes a bottle partially filled with water, a tube sealed into the bottle having one end submerged in the water in the bottle and the free end extending above the top of the bottle and a strip of water-disintegrable paper held within the free end of the tube linking the balloon to the remainder of the package. As the balloon ascends, the lowered atmospheric air pressure causes the air in the bottle to expand, forcing the water in the bottle up the tubing to wet and disintegrate the paper, releasing the package from the balloon.

Changes in sparkling wine aroma during the second fermentation under CO2 pressure in sealed bottle.

PubMed

Martínez-García, Rafael; García-Martínez, Teresa; Puig-Pujol, Anna; Mauricio, Juan Carlos; Moreno, Juan

2017-12-15

High quality sparkling wine made by the traditional method requires a second alcoholic fermentation of a base wine in sealed bottles, followed by an aging time in contact with yeast lees. The CO 2 overpressure released during this second fermentation has an important effect on the yeast metabolism and therefore on the wine aroma composition. This study focuses on the changes in chemical composition and 43 aroma compounds released by yeast during this fermentation carried out under two pressure conditions. The data were subjected to statistical analysis allowing differentiating between the base wine and the wine samples taken in the middle and at the end of fermentation. The differentiation among wines obtained to the end of fermentation with or without CO 2 pressure is only achieved by a principal component analysis of 15 selected minor compounds (mainly ethyl dodecanoate, ethyl tetradecanoate, hexyl acetate, ethyl butanoate and ethyl isobutanoate). Copyright © 2017 Elsevier Ltd. All rights reserved.

Shock effects on hydrous minerals and implications for carbonaceous meteorites

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.; Lambert, P.

1985-01-01

The effect of shock loading over the pressure range of 29-59 GPa on the shock-recovered specimens of antigorite serpentine, Mg3Si2O5(OH)4, were investigated employing infrared (IR) spectroscopy, thermogravimetric analysis, and optical and scanning electron microscopy. With increasing shock pressure, there was an increase in H2O IR absorption peaks at the expense of OH peaks, while the changes in SiO bond vibration modes were identical to those seen for other, nonhydrous minerals. Thermogravimetric results on vented assembly samples showed linear relationships between the shock pressure and both the length of dehydration interval and the effective activation energy for releasing post-shock structural water. Optical and scanning electron microscopy revealed gas bubbles, which appeared to be injected into zones of partial melting, and vesicular dark veins distributed throughout the shocked samples. It is suggested that shock loading of hydrous minerals would release and redistribute free water in the regoliths of carbonaceous chondrite parent bodies, giving rise to observed hydrous alterations.

Inferring the high-pressure strength of copper by measurement of longitudinal sound speed in a symmetric impact and release experiment

NASA Astrophysics Data System (ADS)

Rothman, Stephen; Edwards, Rhys; Vogler, Tracy J.; Furnish, M. D.

2012-03-01

Velocity-time histories of free- or windowed-surfaces have been used to calculate wave speeds and hence deduce the shear moduli for materials at high pressure. This is important to high velocity impact phenomena, e.g. shaped-charge jets, long rod penetrators, and other projectile/armour interactions. Historically the shock overtake method has required several experiments with different depths of material to account for the effect of the surface on the arrival time of the release. A characteristics method, previously used for analysis of isentropic compression experiments, has been modified to account for the effect of the surface interactions, thus only one depth of material is required. This analysis has been applied to symmetric copper impacts performed at Sandia National Laboratory's Star Facility. A shear modulus of 200GPa, at a pressure of ~180GPa, has been estimated. These results are in broad agreement with previous work by Hayes et al.

Inferring the High-Pressure Strength of Copper by Measurement of Longitudinal Sound Speed in a Symmetric Impact and Release Experiment

NASA Astrophysics Data System (ADS)

Rothman, Stephen; Edwards, Rhys; Vogler, Tracy; Furnish, Mike

2011-06-01

Velocity-time histories of free- or windowed-surfaces have been used to calculate wave speeds and hence deduce the shear modulus for materials at high pressure. This is important to high velocity impact phenomena, e.g. shaped-charge jets, long rod penetrators, and other projectile/armour interactions. Historically the shock overtake method has required several experiments with different depths of material to account for the effect of the surface on the arrival time of the release. A characteristics method, previously used for analysis of isentropic compression experiments, has been modified to account for the effect of the surface interactions, thus only one depth of material is required. This analysis has been applied to symmetric copper impacts performed at Sandia National Laboratory's Star Facility. A shear modulus of 200Gpa, at a pressure of ~180GPa, has been estimated. These results are in broad agreement with previous work by Hayes et al.

Are in situ formulations the keys for the therapeutic future of S-nitrosothiols?

PubMed

Parent, Marianne; Boudier, Ariane; Dupuis, François; Nouvel, Cécile; Sapin, Anne; Lartaud, Isabelle; Six, Jean-Luc; Leroy, Pierre; Maincent, Philippe

2013-11-01

S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylpenicillamine (SNAP) were formulated into in situ forming implants (ISI) and microparticles (ISM) using PLGA and either N-methyl-2-pyrrolidone (NMP) or triacetin. Physicochemical characterization was carried out, including the study of matrix structure and degradation. A strong correlation between drug hydrophobicity and the in vitro release profiles was observed: whatever the formulation, GSNO and SNAP were completely released after ca. 1 day and 1 week, respectively. Then, selected formulations (i.e., SNAP-loaded NMP formulations) demonstrated the ability to sustain the vasodilation effect of SNAP, as shown by monitoring the arterial pressure (telemetry) of Wistar rats after subcutaneous injection. Both ISI and ISM injections resulted in a 3-fold extended decrease in pulse arterial pressure compared with the unloaded drug, without significant decrease in the mean arterial pressure. Hence, the results emphasize the suitability of these formulations as drug delivery systems for S-nitrosothiols, widening their therapeutic potential. Copyright © 2013 Elsevier B.V. All rights reserved.

Safety Modification of Cam-and-Groove Hose Coupling

NASA Technical Reports Server (NTRS)

Schwindt, Paul; Littlefield, Alan

2008-01-01

A modification has been made in the mating halves of a cam-and-groove hose coupling to prevent rapid separation of the halves in the event that the cam levers are released while the fluid in the hose is pressurized. The need for this modification arises because commercial off-the-shelf cam-and-groove hose-coupling halves do not incorporate safety features to prevent separation in the pressurized state. Especially when the pressurized fluid is compressible (e.g., steam or compressed air), the separated halves can be propelled with considerable energy, causing personal injury and/or property damage. Therefore, one purpose served by the modification is to provide for venting to release compressive energy in a contained and safe manner while preventing personal injury and/or property damage. Another purpose served by the modification, during the process of connecting the coupling halves, is to ensure that the coupling halves are properly aligned before the cam levers can be locked into position.

Shock-wave properties and high-pressure equations of state of geophysically important materials. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Boslough, M. B.

1983-01-01

Shock wave (Hugoniot), shock temperature, and release data are presented for several geophysically important, refractory materials. A sensitive multichannel optical pyrometer was developed to measure shock temperatures (2500 to 5600 K at pressures from 48 to 117 GPa) in anorthite (CaAl2Si2O8) glass. Shock temperatures of 3750 to 6000 K at pressures from 140 to 182 GPa were measured in calcium oxide (CaO). Temperature data were used to constrain the energetics of the B1-B2 phase transition at 70 GPa in CaO, and to construct a finite strain equation of state for CaO consistent with previous Hugoniot data. The CaO equation of state was used with equation of state parameters of other oxides to construct a theoretical mixed oxide Hugoniot of anorthite, which is in agreement with new Hugoniot data above about 50 GPa, determined using experimental techniques developed. The mixed oxide model, however, overestimates the shock temperatures, and does not accurately predict measured release paths.

Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

PubMed

Kalani, Mahshid; Yunus, Robiah

2012-01-01

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method

PubMed Central

Kalani, Mahshid; Yunus, Robiah

2012-01-01

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks. PMID:22619552

Pathways of fish invasions in the Mid-Atlantic region of the United States

USGS Publications Warehouse

Lapointe, Nicolas W. R.; Fuller, Pam; Neilson, Matthew; Murphy, Brian R.; Angermeier, Paul

2016-01-01

Non-native fish introductions are a major threat to biodiversity and fisheries, and occur through numerous pathways that vary regionally in importance. A key strategy for managing invasions is to focus prevention efforts on pathways posing the greatest risk of future introductions. We identified high-risk pathways for fish establishment in the Mid-Atlantic region of the United States based on estimates of probability of establishment and records of previous introductions, which were considered in the context of emerging socioeconomic trends. We used estimates of propagule pressure, species’ environmental tolerance, and size of species pool to assess the risk of establishment by pathway. Pathways varied considerably in historic importance and species composition, with the majority of species introduced intentionally via stocking (primarily for sport, forage, or biocontrol) or bait release. Bait release, private stocking, illegal introductions intended to establish reproducing populations (e.g., of sport fish), aquaculture, and the sale of live organisms all create risks for future invasions in the Mid-Atlantic region. Of these pathways, bait release probably poses the greatest risk of introductions for the Mid-Atlantic region because propagule pressure is moderate, most released species are tolerant of local environmental conditions, and the pool of species available for transplantation is large. Our findings differ considerably from studies in other regions (e.g., bait release is a dominant pathway in the Mid-Atlantic region, whereas illegal introduction of sport fish is dominant in the western US and aquarium releases are dominant in Florida), demonstrating the need for regional-scale assessments of, and management strategies for, introduction pathways.

Sub-atmospheric pressure gas sources for bulk storage and delivery of arsine and phosphine to MOCVD tools

NASA Astrophysics Data System (ADS)

Raynor, M. W.; Houlding, V. H.; Funke, H. H.; Frye, R.; Dietz, J. A.

2003-02-01

A sub-atmospheric (SA) pressure gas source, based on the reversible adsorption of hydride gas onto a high surface area substrate within a cylinder, has been developed for the safe storage and delivery of high-purity arsine and phosphine for MOCVD processes. SA pressure and high-pressure sources are compared with respect to gas delivery and purity, risk reduction, and cost benefits. Gas analysis and performance of epi-structures grown with SA pressure cylinders confirm that the hydride gas delivered meets the purity requirements of MOCVD processes. Further, the low gas release rates measured from 2.2 and 49 l SA pressure cylinders indicate that the technology can be scaled up without additional safety risk.

Fundamental Interactions in Gasoline Compression Ignition Engines with Fuel Stratification

NASA Astrophysics Data System (ADS)

Wolk, Benjamin Matthew

Transportation accounted for 28% of the total U.S. energy demand in 2011, with 93% of U.S. transportation energy coming from petroleum. The large impact of the transportation sector on global climate change necessitates more-efficient, cleaner-burning internal combustion engine operating strategies. One such strategy that has received substantial research attention in the last decade is Homogeneous Charge Compression Ignition (HCCI). Although the efficiency and emissions benefits of HCCI are well established, practical limits on the operating range of HCCI engines have inhibited their application in consumer vehicles. One such limit is at high load, where the pressure rise rate in the combustion chamber becomes excessively large. Fuel stratification is a potential strategy for reducing the maximum pressure rise rate in HCCI engines. The aim is to introduce reactivity gradients through fuel stratification to promote sequential auto-ignition rather than a bulk-ignition, as in the homogeneous case. A gasoline-fueled compression ignition engine with fuel stratification is termed a Gasoline Compression Ignition (GCI) engine. Although a reasonable amount of experimental research has been performed for fuel stratification in GCI engines, a clear understanding of how the fundamental in-cylinder processes of fuel spray evaporation, mixing, and heat release contribute to the observed phenomena is lacking. Of particular interest is gasoline's pressure sensitive low-temperature chemistry and how it impacts the sequential auto-ignition of the stratified charge. In order to computationally study GCI with fuel stratification using three-dimensional computational fluid dynamics (CFD) and chemical kinetics, two reduced mechanisms have been developed. The reduced mechanisms were developed from a large, detailed mechanism with about 1400 species for a 4-component gasoline surrogate. The two versions of the reduced mechanism developed in this work are: (1) a 96-species version and (2) a 98-species version including nitric oxide formation reactions. Development of reduced mechanisms is necessary because the detailed mechanism is computationally prohibitive in three-dimensional CFD and chemical kinetics simulations. Simulations of Partial Fuel Stratification (PFS), a GCI strategy, have been performed using CONVERGE with the 96-species reduced mechanism developed in this work for a 4-component gasoline surrogate. Comparison is made to experimental data from the Sandia HCCI/GCI engine at a compression ratio 14:1 at intake pressures of 1 bar and 2 bar. Analysis of the heat release and temperature in the different equivalence ratio regions reveals that sequential auto-ignition of the stratified charge occurs in order of increasing equivalence ratio for 1 bar intake pressure and in order of decreasing equivalence ratio for 2 bar intake pressure. Increased low- and intermediate-temperature heat release with increasing equivalence ratio at 2 bar intake pressure compensates for decreased temperatures in higher-equivalence ratio regions due to evaporative cooling from the liquid fuel spray and decreased compression heating from lower values of the ratio of specific heats. The presence of low- and intermediate-temperature heat release at 2 bar intake pressure alters the temperature distribution of the mixture stratification before hot-ignition, promoting the desired sequential auto-ignition. At 1 bar intake pressure, the sequential auto-ignition occurs in the reverse order compared to 2 bar intake pressure and too fast for useful reduction of the maximum pressure rise rate compared to HCCI. Additionally, the premixed portion of the charge auto-ignites before the highest-equivalence ratio regions. Conversely, at 2 bar intake pressure, the premixed portion of the charge auto-ignites last, after the higher-equivalence ratio regions. More importantly, the sequential auto-ignition occurs over a longer time period for 2 bar intake pressure than at 1 bar intake pressure such that a sizable reduction in the maximum pressure rise rate compared to HCCI can be achieved.

High-pressure transformation in the cobalt spinel ferrites

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

Blasco, J., E-mail: jbc@posta.unizar.es; Subías, G.; García, J.

2015-01-15

We report high pressure angle-dispersive x-ray diffraction measurements on Co{sub x}Fe{sub 3−x}O{sub 4} (x=1, 1.5, 1.75) spinels at room temperature up to 34 GPa. The three samples show a similar structural phase transformation from the cubic spinel structure to an analogous post-spinel phase at around 20 GPa. Spinel and post-spinel phases coexist in a wide pressure range (∼20–25 GPa) and the transformation is irreversible. The equation of state of the three cubic spinel ferrites was determined and our results agree with the data obtained in related oxide spinels showing the role of the pressure-transmitting medium for the accurate determination ofmore » the equation of state. Measurements releasing pressure revealed that the post-spinel phase is stable down to 4 GPa when it decomposes yielding a new phase with poor crystallinity. Later compression does not recover either the spinel or the post-spinel phases. This phase transformation induced by pressure explains the irreversible lost of the ferrimagnetic behavior reported in these spinels. - Graphical abstract: Pressure dependence of the unit cell volume per formula unit for Co{sub 1.5}Fe{sub 1.5}O{sub 4} spinel. Circles and squares stand for spinel and postspinel phases, respectively. Dark (open) symbols: determination upon compression (decompression). - Highlights: • The pressure induces similar phase transformation in Co{sub 3−x}Fe{sub x}O{sub 4} spinels (1≤x≤2). • The postspinel phases decompose after releasing pressure. • The irreversibility of this phase transformation explains the disappearance of magnetism in these spinels after applying pressure. • Accurate equation of state can be obtained up to 10 GPa using an alcohol mixture as pressure transmitting medium. • The equation of state suggests similar elastic properties for these spinels in this composition range.« less

The influence of age and diabetes on the skin blood flow response to local pressure.

PubMed

Petrofsky, Jerrold S; Bains, Gurinder S; Prowse, Michelle; Mc Lellan, Katie; Ethiraju, Gomathi; Lee, Scott; Gunda, Shashi; Lohman, Everett; Schwab, Ernie

2009-07-01

Previous data has shown that when pressure is applied to the skin of the ankle and on the foot, there is a reactive increase in circulation. In the present investigation, these studies were expanded to look at the response of the hand, back, and foot to applied pressure. Ten young subjects whose average age was 26.5+/-3.3 yrs, 10 older subjects whose average age was 73.3+/-19.7 yrs and 10 people with diabetes whose average age was 60.1+/-5.7 yrs participated in the study. There was no statistical difference in the height or weight of the subjects. Hemoglobin A1c of the group with Diabetes averaged 6.98+/-1.15% with the mean duration of diabetes 13.6+/-9.5 yrs. An infrared laser Doppler flow meter was used to measure circulation on the hand, lower back, and on the bottom of the foot during applications of pressure at 15, 30, 45, and 60 kPa. For all three areas of the body, circulation was significantly less in the group with diabetes than the other two groups (p<0.05). When pressure was applied at 15 kPa, the blood flow to the skin initially decreased, but then increased in the younger subjects and in the older subjects but did not increase in subjects with diabetes for any area of the body. Further, after pressure was released, for any of the four pressures examined here, while the younger subjects showed a pronounced reactive hyperemia, subjects with diabetes showed a diminished hyperemia not proportional to the pressure that was applied. It appears that the normal protective mechanism of a pressure induced hyperemia is absent or diminished in patients with diabetes with more effect on the periphery than on the core area of the body. More importantly, after pressure was applied and released, subjects with diabetes lacked a proportional hyperemia to recovery form the transient ischemia of the pressure.

Calibration Of Partial-Pressure-Of-Oxygen Sensors

NASA Technical Reports Server (NTRS)

Yount, David W.; Heronimus, Kevin

1995-01-01

Report and analysis of, and discussion of improvements in, procedure for calibrating partial-pressure-of-oxygen sensors to satisfy Spacelab calibration requirements released. Sensors exhibit fast drift, which results in short calibration period not suitable for Spacelab. By assessing complete process of determining total drift range available, calibration procedure modified to eliminate errors and still satisfy requirements without compromising integrity of system.

49 CFR 232.211 - Class III brake tests-trainline continuity inspection.

Code of Federal Regulations, 2012 CFR

2012-10-01

... pressure is being restored, the operator of the train shall know that the air brakes function as intended... determined that the brakes on the rear car of the train apply and release in response to air pressure changes... train that has previously received a Class I brake test and that has not been off air for more than four...

49 CFR 232.211 - Class III brake tests-trainline continuity inspection.

Code of Federal Regulations, 2011 CFR

2011-10-01

... pressure is being restored, the operator of the train shall know that the air brakes function as intended... determined that the brakes on the rear car of the train apply and release in response to air pressure changes... train that has previously received a Class I brake test and that has not been off air for more than four...

49 CFR 232.211 - Class III brake tests-trainline continuity inspection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... pressure is being restored, the operator of the train shall know that the air brakes function as intended... determined that the brakes on the rear car of the train apply and release in response to air pressure changes... train that has previously received a Class I brake test and that has not been off air for more than four...

49 CFR 232.211 - Class III brake tests-trainline continuity inspection.

Code of Federal Regulations, 2013 CFR

2013-10-01

... pressure is being restored, the operator of the train shall know that the air brakes function as intended... determined that the brakes on the rear car of the train apply and release in response to air pressure changes... train that has previously received a Class I brake test and that has not been off air for more than four...

49 CFR 232.211 - Class III brake tests-trainline continuity inspection.

Code of Federal Regulations, 2014 CFR

2014-10-01

... pressure is being restored, the operator of the train shall know that the air brakes function as intended... determined that the brakes on the rear car of the train apply and release in response to air pressure changes... train that has previously received a Class I brake test and that has not been off air for more than four...

Design Space Approach in Optimization of Fluid Bed Granulation and Tablets Compression Process

PubMed Central

Djuriš, Jelena; Medarević, Djordje; Krstić, Marko; Vasiljević, Ivana; Mašić, Ivana; Ibrić, Svetlana

2012-01-01

The aim of this study was to optimize fluid bed granulation and tablets compression processes using design space approach. Type of diluent, binder concentration, temperature during mixing, granulation and drying, spray rate, and atomization pressure were recognized as critical formulation and process parameters. They were varied in the first set of experiments in order to estimate their influences on critical quality attributes, that is, granules characteristics (size distribution, flowability, bulk density, tapped density, Carr's index, Hausner's ratio, and moisture content) using Plackett-Burman experimental design. Type of diluent and atomization pressure were selected as the most important parameters. In the second set of experiments, design space for process parameters (atomization pressure and compression force) and its influence on tablets characteristics was developed. Percent of paracetamol released and tablets hardness were determined as critical quality attributes. Artificial neural networks (ANNs) were applied in order to determine design space. ANNs models showed that atomization pressure influences mostly on the dissolution profile, whereas compression force affects mainly the tablets hardness. Based on the obtained ANNs models, it is possible to predict tablet hardness and paracetamol release profile for any combination of analyzed factors. PMID:22919295

Apparatus for loading shape memory gripper mechanisms

DOEpatents

Lee, Abraham P.; Benett, William J.; Schumann, Daniel L.; Krulevitch, Peter A.; Fitch, Joseph P.

2001-01-01

A method and apparatus for loading deposit material, such as an embolic coil, into a shape memory polymer (SMP) gripping/release mechanism. The apparatus enables the application of uniform pressure to secure a grip by the SMP mechanism on the deposit material via differential pressure between, for example, vacuum within the SMP mechanism and hydrostatic water pressure on the exterior of the SMP mechanism. The SMP tubing material of the mechanism is heated to above the glass transformation temperature (Tg) while reshaping, and subsequently cooled to below Tg to freeze the shape. The heating and/or cooling may, for example, be provided by the same water applied for pressurization or the heating can be applied by optical fibers packaged to the SMP mechanism for directing a laser beam, for example, thereunto. At a point of use, the deposit material is released from the SMP mechanism by reheating the SMP material to above the temperature Tg whereby it returns to its initial shape. The reheating of the SM material may be carried out by injecting heated fluid (water) through an associated catheter or by optical fibers and an associated beam of laser light, for example.

Method for loading shape memory polymer gripper mechanisms

DOEpatents

Lee, Abraham P.; Benett, William J.; Schumann, Daniel L.; Krulevitch, Peter A.; Fitch, Joseph P.

2002-01-01

A method and apparatus for loading deposit material, such as an embolic coil, into a shape memory polymer (SMP) gripping/release mechanism. The apparatus enables the application of uniform pressure to secure a grip by the SMP mechanism on the deposit material via differential pressure between, for example, vacuum within the SMP mechanism and hydrostatic water pressure on the exterior of the SMP mechanism. The SMP tubing material of the mechanism is heated to above the glass transformation temperature (Tg) while reshaping, and subsequently cooled to below Tg to freeze the shape. The heating and/or cooling may, for example, be provided by the same water applied for pressurization or the heating can be applied by optical fibers packaged to the SMP mechanism for directing a laser beam, for example, thereunto. At a point of use, the deposit material is released from the SMP mechanism by reheating the SMP material to above the temperature Tg whereby it returns to its initial shape. The reheating of the SMP material may be carried out by injecting heated fluid (water) through an associated catheter or by optical fibers and an associated beam of laser light, for example.

High pressure polymorphs and amorphization of upconversion host material NaY(WO{sub 4}){sub 2}

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

Hong, Fang; Yue, Binbin, E-mail: yuebb@hpstar.ac.cn, E-mail: chenbin@hpstar.ac.cn; The Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, California 94720

2016-07-25

The pressure effect on the structural change of upconversion host material NaY(WO{sub 4}){sub 2} was studied by using in-situ synchrotron X-ray diffraction. A transition from the initial scheelite phase to the M-fergusonite phase occurs near 10 GPa, and another phase transition is found near 27.5 GPa, which could be an isostructural transition without symmetry change. The sample becomes amorphous when the pressure is fully released from high pressure. This work demonstrates the possibility of synthesizing various polymorph structures for non-linear optical applications with a high pressure, chemical doping, or strained thin-film nanostructure process.

Controlled release nifedipine and valsartan combination therapy in patients with essential hypertension: the adalat CR and valsartan cost-effectiveness combination (ADVANCE-combi) study.

PubMed

Saito, Ikuo; Saruta, Takao

2006-10-01

This study was designed to compare the clinical efficacy of two calcium channel blocker-based combination therapies with an angiotensin receptor blocker in Japanese patients with essential hypertension. A 16-week, double-blind, parallel-arm, randomized clinical trial was performed to compare the efficacy and safety of the combination therapy of controlled release nifedipine (nifedipine CR) plus valsartan vs. that of amlodipine plus valsartan. The primary endpoint was the target blood pressure achievement rate. Eligible patients were randomly allocated to nifedipine CR-based or amlodipine-based treatment groups. Patients were examined every 4 weeks to determine whether the blood pressure had reached the target level. When the target level was not achieved, the drug regimen was changed; when the target blood pressure was achieved, the same study medication was continued. A total of 505 patients were enrolled in the study (nifedipine CR group: 245 cases; amlodipine group: 260 cases). After 16 weeks of treatment, blood pressure was significantly reduced in both groups, but to a larger extent in the nifedipine CR group than in the amlodipine group (p < 0.01). The target blood pressure achievement rate was also significantly higher in the nifedipine CR group (p < 0.001). There was no significant difference in the incidence of drug-related adverse events between the groups. These results indicate that the nifedipine CR-based combination therapy was superior to the amlodipine-based therapy for decreasing blood pressure and achieving the target blood pressure in patients with essential hypertension.

Early application of airway pressure release ventilation may reduce the duration of mechanical ventilation in acute respiratory distress syndrome.

PubMed

Zhou, Yongfang; Jin, Xiaodong; Lv, Yinxia; Wang, Peng; Yang, Yunqing; Liang, Guopeng; Wang, Bo; Kang, Yan

2017-11-01

Experimental animal models of acute respiratory distress syndrome (ARDS) have shown that the updated airway pressure release ventilation (APRV) methodologies may significantly improve oxygenation, maximize lung recruitment, and attenuate lung injury, without circulatory depression. This led us to hypothesize that early application of APRV in patients with ARDS would allow pulmonary function to recover faster and would reduce the duration of mechanical ventilation as compared with low tidal volume lung protective ventilation (LTV). A total of 138 patients with ARDS who received mechanical ventilation for <48 h between May 2015 to October 2016 while in the critical care medicine unit (ICU) of the West China Hospital of Sichuan University were enrolled in the study. Patients were randomly assigned to receive APRV (n = 71) or LTV (n = 67). The settings for APRV were: high airway pressure (P high ) set at the last plateau airway pressure (P plat ), not to exceed 30 cmH 2 O) and low airway pressure ( P low ) set at 5 cmH 2 O; the release phase (T low ) setting adjusted to terminate the peak expiratory flow rate to ≥ 50%; release frequency of 10-14 cycles/min. The settings for LTV were: target tidal volume of 6 mL/kg of predicted body weight; P plat not exceeding 30 cmH 2 O; positive end-expiratory pressure (PEEP) guided by the PEEP-FiO 2 table according to the ARDSnet protocol. The primary outcome was the number of days without mechanical ventilation from enrollment to day 28. The secondary endpoints included oxygenation, P plat , respiratory system compliance, and patient outcomes. Compared with the LTV group, patients in the APRV group had a higher median number of ventilator-free days {19 [interquartile range (IQR) 8-22] vs. 2 (IQR 0-15); P < 0.001}. This finding was independent of the coexisting differences in chronic disease. The APRV group had a shorter stay in the ICU (P = 0.003). The ICU mortality rate was 19.7% in the APRV group versus 34.3% in the LTV group (P = 0.053) and was associated with better oxygenation and respiratory system compliance, lower P plat , and less sedation requirement during the first week following enrollment (P < 0.05, repeated-measures analysis of variance). Compared with LTV, early application of APRV in patients with ARDS improved oxygenation and respiratory system compliance, decreased P plat and reduced the duration of both mechanical ventilation and ICU stay.

Mechanistic modelling of drug release from polymer-coated and swelling and dissolving polymer matrix systems.

PubMed

Kaunisto, Erik; Marucci, Mariagrazia; Borgquist, Per; Axelsson, Anders

2011-10-10

The time required for the design of a new delivery device can be sensibly reduced if the release mechanism is understood and an appropriate mathematical model is used to characterize the system. Once all the model parameters are obtained, in silico experiments can be performed, to provide estimates of the release from devices with different geometries and compositions. In this review coated and matrix systems are considered. For coated formulations, models describing the diffusional drug release, the osmotic pumping drug release, and the lag phase of pellets undergoing cracking in the coating due to the build-up of a hydrostatic pressure are reviewed. For matrix systems, models describing pure polymer dissolution, diffusion in the polymer and drug release from swelling and eroding polymer matrix formulations are reviewed. Importantly, the experiments used to characterize the processes occurring during the release and to validate the models are presented and discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

Measurements of the Shock Release Of Quartz and Paralyene-N

NASA Astrophysics Data System (ADS)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2017-06-01

The shock and release properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies single shock or multiple shock conditions. The challenge with measuring release properties is unlike shocks which have a single interface from which to measure the properties, the release establishes gradients in the sample. The streaked x-ray imaging capability of the NIKE laser allow the interface between quartz and CH to be measured during the release, giving measurements of the interface velocity and CH density. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography Work supported by DOE/NNSA.

Roller compaction of hydrophilic extended release tablets-combined effects of processing variables and drug/matrix former particle size.

PubMed

Heiman, Johanna; Tajarobi, Farhad; Gururajan, Bindhumadhavan; Juppo, Anne; Abrahmsén-Alami, Susanna

2015-04-01

The present study shows that roller compaction (RC) can successfully be used as a granulation method to prepare hydroxypropyl methylcellulose (HPMC)-based extended release matrix tablets containing a high drug load, both for materials deforming mainly by fragmentation (paracetamol) as for those having mainly plastic deformation (ibuprofen). The combined effect of RC process variables and composition on the manufacturability of HPMC tablets was investigated. Standard wet granulation grade HPMC was compared with a larger particle size direct compressible HPMC grade. Higher roll pressure was found to result in larger paracetamol granules and narrower granule particle size distributions, especially for formulations containing smaller size HPMC. However, for ibuprofen, no clear effect of roll pressure was observed. High roll pressure also resulted in denser ribbon and less bypass fines during RC. Loss of compactibility was observed for granules compared to powder blends, which was found to be related to differences in granule porosity and morphology. Using the large-sized HPMC grade did in some cases result in lower tensile strength tablets but had the advantage to improve the powder flow into the roller compactor. This work also indicates that when the HPMC level lies near the percolation threshold, significant changes can occur in the drug release rate due to changes in other factors (raw material characteristics and processing).

Forces and Pressures in DNA Packaging and Release from Viral Capsids

PubMed Central

Tzlil, Shelly; Kindt, James T.; Gelbart, William M.; Ben-Shaul, Avinoam

2003-01-01

In a previous communication (Kindt et al., 2001) we reported preliminary results of Brownian dynamics simulation and analytical theory which address the packaging and ejection forces involving DNA in bacteriophage capsids. In the present work we provide a systematic formulation of the underlying theory, featuring the energetic and structural aspects of the strongly confined DNA. The free energy of the DNA chain is expressed as a sum of contributions from its encapsidated and released portions, each expressed as a sum of bending and interstrand energies but subjected to different boundary conditions. The equilibrium structure and energy of the capsid-confined and free chain portions are determined, for each ejected length, by variational minimization of the free energy with respect to their shape profiles and interaxial spacings. Numerical results are derived for a model system mimicking the λ-phage. We find that the fully encapsidated genome is highly compressed and strongly bent, forming a spool-like condensate, storing enormous elastic energy. The elastic stress is rapidly released during the first stage of DNA injection, indicating the large force (tens of pico Newtons) needed to complete the (inverse) loading process. The second injection stage sets in when ∼1/3 of the genome has been released, and the interaxial distance has nearly reached its equilibrium value (corresponding to that of a relaxed torus in solution); concomitantly the encapsidated genome begins a gradual morphological transformation from a spool to a torus. We also calculate the loading force, the average pressure on the capsid's walls, and the anisotropic pressure profile within the capsid. The results are interpreted in terms of the (competing) bending and interaction components of the packing energy, and are shown to be in good agreement with available experimental data. PMID:12609865

The Release of Trapped Gases from Amorphous Solid Water Films: II. “Bottom-Up” Induced Desorption Pathways

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

May, Robert A.; Smith, R. Scott; Kay, Bruce D.

2013-03-14

In this (Paper II) and the preceding companion paper (Paper I) we investigate the mechanisms for the release of trapped gases from underneath of amorphous solid water (ASW) films. In Paper I, we focused on the low coverage (pressure) regime where the release mechanism is controlled by crystallization-induced cracks formed in the ASW overlayer. In that regime the results were largely independent of the particular gas underlayer. Here in Paper II, we focus on the high coverage (pressure) regime where new desorption pathways become accessible prior to ASW crystallization. In contrast to the results for the low coverage regime (Papermore » I), the release mechanism is a function of the multilayer thickness and composition, displaying dramatically different behavior between Ar, Kr, Xe, CH4, N2, O2, and CO. Two primary desorption pathways are observed. The first occurs between 100 and 150 K and manifests itself as sharp, extremely narrow desorption peaks. Temperature programmed desorption is utilized to show that abrupt desorption bursts are due to pressure induced structural failure of the ASW overlyaer. The second pathway occurs at low temperature (typically <100 K) where broad desorption peaks are observed. Desorption through this pathway is attributed to diffusion through pores and connected pathways formed during ASW deposition. The extent of desorption and the lineshape of the low temperature desorption peak are dependent on the substrate on which the gas underlayer is deposited. Angle dependent ballistic deposition of the ASW is used vary the porosity of overlayer and confirm that the low temperature desorption pathway is due to porosity that is inherent in the ASW overlayer during deposition.« less

Improved cortisol exposure-time profile and outcome in patients with adrenal insufficiency: a prospective randomized trial of a novel hydrocortisone dual-release formulation.

PubMed

Johannsson, G; Nilsson, A G; Bergthorsdottir, R; Burman, P; Dahlqvist, P; Ekman, B; Engström, B E; Olsson, T; Ragnarsson, O; Ryberg, M; Wahlberg, J; Biller, B M K; Monson, J P; Stewart, P M; Lennernäs, H; Skrtic, S

2012-02-01

Patients with treated adrenal insufficiency (AI) have increased morbidity and mortality rate. Our goal was to improve outcome by developing a once-daily (OD) oral hydrocortisone dual-release tablet with a more physiological exposure-time cortisol profile. The aim was to compare pharmacokinetics and metabolic outcome between OD and the same daily dose of thrice-daily (TID) dose of conventional hydrocortisone tablets. We conducted an open, randomized, two-period, 12-wk crossover multicenter trial with a 24-wk extension at five university hospital centers. The trial enrolled 64 adults with primary AI; 11 had concomitant diabetes mellitus (DM). The same daily dose of hydrocortisone was administered as OD dual-release or TID. We evaluated cortisol pharmacokinetics. Compared with conventional TID, OD provided a sustained serum cortisol profile 0-4 h after the morning intake and reduced the late afternoon and the 24-h cortisol exposure. The mean weight (difference = -0.7 kg, P = 0.005), systolic blood pressure (difference = -5.5 mm Hg, P = 0.0001) and diastolic blood pressure (difference: -2.3 mm Hg; P = 0.03), and glycated hemoglobin (absolute difference = -0.1%, P = 0.0006) were all reduced after OD compared with TID at 12 wk. Compared with TID, a reduction in glycated hemoglobin by 0.6% was observed in patients with concomitant DM during OD (P = 0.004). The OD dual-release tablet provided a more circadian-based serum cortisol profile. Reduced body weight, reduced blood pressure, and improved glucose metabolism were observed during OD treatment. In particular, glucose metabolism improved in patients with concomitant DM.

Forces and pressures in DNA packaging and release from viral capsids.

PubMed

Tzlil, Shelly; Kindt, James T; Gelbart, William M; Ben-Shaul, Avinoam

2003-03-01

In a previous communication (Kindt et al., 2001) we reported preliminary results of Brownian dynamics simulation and analytical theory which address the packaging and ejection forces involving DNA in bacteriophage capsids. In the present work we provide a systematic formulation of the underlying theory, featuring the energetic and structural aspects of the strongly confined DNA. The free energy of the DNA chain is expressed as a sum of contributions from its encapsidated and released portions, each expressed as a sum of bending and interstrand energies but subjected to different boundary conditions. The equilibrium structure and energy of the capsid-confined and free chain portions are determined, for each ejected length, by variational minimization of the free energy with respect to their shape profiles and interaxial spacings. Numerical results are derived for a model system mimicking the lambda-phage. We find that the fully encapsidated genome is highly compressed and strongly bent, forming a spool-like condensate, storing enormous elastic energy. The elastic stress is rapidly released during the first stage of DNA injection, indicating the large force (tens of pico Newtons) needed to complete the (inverse) loading process. The second injection stage sets in when approximately 1/3 of the genome has been released, and the interaxial distance has nearly reached its equilibrium value (corresponding to that of a relaxed torus in solution); concomitantly the encapsidated genome begins a gradual morphological transformation from a spool to a torus. We also calculate the loading force, the average pressure on the capsid's walls, and the anisotropic pressure profile within the capsid. The results are interpreted in terms of the (competing) bending and interaction components of the packing energy, and are shown to be in good agreement with available experimental data.

Sustained-release subconjunctival 5-fluorouracil.

PubMed

Smith, T J; Ashton, P

1996-09-01

The purpose of this research was to obtain preliminary safety and efficacy data on a novel sustained-release 5-fluorouracil (5-FU) implant in high-risk glaucoma surgical patients. The implants were placed subconjunctivally in four patients undergoing high-risk trabeculectomy. The patients have been observed for approximately 2.5 years. In three of the four patients intraocular pressure was controlled at less than 21 mm Hg, with stabilization of the visual field. One patient had early failure. No untoward events were linked to the placement of the implant. Sustained-release systems for subconjunctival 5-FU may be useful in filter maintenance.

Characterization and mosquito repellent activity of citronella oil nanoemulsion.

PubMed

Sakulku, Usawadee; Nuchuchua, Onanong; Uawongyart, Napaporn; Puttipipatkhachorn, Satit; Soottitantawat, Apinan; Ruktanonchai, Uracha

2009-05-08

Encapsulated citronella oil nanoemulsion prepared by high pressure homogenization at varying amounts of surfactant and glycerol, was studied in terms of the droplet size, stability, release characteristics and in vivo mosquito protection. Transparent nanoemulsion can be obtained at optimal concentration of 2.5% surfactant and 100% glycerol. Physical appearance and the stability of the emulsion were greatly improved through an addition of glycerol, owing to its co-solvent and highly viscous property. The increasing emulsion droplet increased the oil retention. The release behavior could be attributed to the effect of droplet size and concentrations of surfactant and glycerol. By fitting to Higuchi's equation, an increase in glycerol and surfactant concentrations resulted in slow release of the oil. The release rate related well to the protection time where a decrease in release rate can prolong mosquito protection time.

CXCR6 deficiency attenuates pressure overload-induced monocytes migration and cardiac fibrosis through downregulating TNF-α-dependent MMP9 pathway

PubMed Central

Wang, Jia-Hong; Su, Feng; Wang, Shijun; Lu, Xian-Cheng; Zhang, Shao-Heng; Chen, De; Chen, Nan-Nan; Zhong, Jing-Quan

2014-01-01

An immerging role of TNF-α in collagen synthesis and cardiac fibrosis implies the significance of TNF-α production in the development of myocardial remodeling. Our previous study showed a reduction of TNF-α and attenuated cardiac remodeling in CXCR6 knockout (KO) mice after ischemia/reperfusion injury. However, the potential mechanism of TNF-α-mediated cardiac fibrosis with pressure overload has not been well elucidated. In the present study, we aim to investigate the role of CXCR6 in TNF-α release and myocardial remodeling in response to pressure overload. Pressure overload was performed by constriction of transverse aorta (TAC) surgery on CXCR6 KO mice and C57 wild-type (WT) counterparts. At 6 weeks after TAC, cardiac remodeling was assessed by echocardiography, cardiac TNF-α release and its type I receptor (TNFRI), were detected by ELISA and western blot, collagen genes Col1a1 (type I) and Col3a1 (type III) were examined by real-time PCR. Compared with CXCR6 WT mice, CXCR6 KO mice exhibited less cardiac dysfunction, reduced expression of TNFRI, Col1a1 and Col3a. In vitro, we confirmed that CXCR6 deficiency led to reduced homing and infiltration of CD11b+ monocytes, which contributed to attenuated TNF-α release in myocardium. Furthermore, TNFRI antagonist pretreatment blocked AT1 receptor signaling and NOX4 expression, reduced collagen synthesis, and blunted the activity of MMP9 in CXCR6 WT mice after TAC, but these were not observed in CXCR6 KO mice. In the present work, we propose a mechanism that CXCR6 is essential for pressure overload-mediated myocardial recruitment of monocytes, which contributes to cardiac fibrosis through TNF-α-dependent MMP9 activation and collagen synthesis. PMID:25400729

CXCR6 deficiency attenuates pressure overload-induced monocytes migration and cardiac fibrosis through downregulating TNF-α-dependent MMP9 pathway.

PubMed

Wang, Jia-Hong; Su, Feng; Wang, Shijun; Lu, Xian-Cheng; Zhang, Shao-Heng; Chen, De; Chen, Nan-Nan; Zhong, Jing-Quan

2014-01-01

An immerging role of TNF-α in collagen synthesis and cardiac fibrosis implies the significance of TNF-α production in the development of myocardial remodeling. Our previous study showed a reduction of TNF-α and attenuated cardiac remodeling in CXCR6 knockout (KO) mice after ischemia/reperfusion injury. However, the potential mechanism of TNF-α-mediated cardiac fibrosis with pressure overload has not been well elucidated. In the present study, we aim to investigate the role of CXCR6 in TNF-α release and myocardial remodeling in response to pressure overload. Pressure overload was performed by constriction of transverse aorta (TAC) surgery on CXCR6 KO mice and C57 wild-type (WT) counterparts. At 6 weeks after TAC, cardiac remodeling was assessed by echocardiography, cardiac TNF-α release and its type I receptor (TNFRI), were detected by ELISA and western blot, collagen genes Col1a1 (type I) and Col3a1 (type III) were examined by real-time PCR. Compared with CXCR6 WT mice, CXCR6 KO mice exhibited less cardiac dysfunction, reduced expression of TNFRI, Col1a1 and Col3a. In vitro, we confirmed that CXCR6 deficiency led to reduced homing and infiltration of CD11b(+) monocytes, which contributed to attenuated TNF-α release in myocardium. Furthermore, TNFRI antagonist pretreatment blocked AT1 receptor signaling and NOX4 expression, reduced collagen synthesis, and blunted the activity of MMP9 in CXCR6 WT mice after TAC, but these were not observed in CXCR6 KO mice. In the present work, we propose a mechanism that CXCR6 is essential for pressure overload-mediated myocardial recruitment of monocytes, which contributes to cardiac fibrosis through TNF-α-dependent MMP9 activation and collagen synthesis.

Valley formation by groundwater seepage, pressurized groundwater outbursts and crater-lake overflow in flume experiments with implications for Mars

NASA Astrophysics Data System (ADS)

Marra, Wouter A.; Braat, Lisanne; Baar, Anne W.; Kleinhans, Maarten G.

2014-04-01

Remains of fluvial valleys on Mars reveal the former presence of water on the surface. However, the source of water and the hydrological setting is not always clear, especially in types of valleys that are rare on Earth and where we have limited knowledge of the processes involved. We investigated three hydrological scenarios for valley formation on Mars: hydrostatic groundwater seepage, release of pressurized groundwater and crater-lake overflow. Using physical modeling in laboratory experiments and numerical hydrological modeling we quantitatively studied the morphological development and processes involved in channel formation that result from these different sources of water in unconsolidated sediment. Our results show that valleys emerging from seeping groundwater by headward erosion form relatively slowly as fluvial transport takes place in a channel much smaller than the valley. Pressurized groundwater release forms a characteristic source area at the channel head by fluidization processes. This head consist of a pit in case of superlithostatic pressure and may feature small radial channels and collapse features. Valleys emerging from a crater-lake overflow event develop quickly in a run-away process of rim erosion and discharge increase. The valley head at the crater outflow point has a converging fan shape, and the rapid incision of the rim leaves terraces and collapse features. Morphological elements observed in the experiments can help in identifying the formative processes on Mars, when considerations of experimental scaling and lithological characteristics of the martian surface are taken into account. These morphological features might reveal the associated hydrological settings and formative timescales of a valley. An estimate of formative timescale from sediment transport is best based on the final channel dimensions for groundwater seepage valleys and on the valley dimensions for pressurized groundwater release and crater-lake overflow valleys. Our experiments show that different sources of water form valleys of similar size in quite different timescales.

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

Hinkebein, Thomas E.

The intrusion of gas into oils stored within the SPR has been examined. When oil is stored in domal salts, gases intrude into the stored oil from the surrounding salt. Aspects of the mechanism of gas intrusion have been examined. In all cases, this gas intrusion results in increases in the oil vapor pressure. Data that have been gathered from 1993 to August 2002 are presented to show the resultant increases in bubble-point pressure on a cavern-by-cavern as well as on a stream basis. The measurement techniques are presented with particular emphasis on the TVP 95. Data analysis methods aremore » presented to show the methods required to obtain recombined cavern oil compositions. Gas-oil ratios are also computed from the data and are presented on a cavern-by-cavern and stream basis. The observed increases in bubble-point pressure and gas-oil ratio are further statistically analyzed to allow data interpretation. Emissions plume modeling is used to determine adherence to state air regulations. Gas intrusion is observed to be variable among the sites and within each dome. Gas intrusions at Bryan Mound and Big Hill have resulted in the largest increases in bubble-point pressure for the Strategic Petroleum Reserve (SPR). The streams at Bayou Choctaw and West Hackberry show minimal bubble-point pressure increases. Emissions plume modeling, using the state mandated ISCST code, of oil storage tanks showed that virtually no gas may be released when H2S standards are considered. DOE plans to scavenge H2S to comply with the very tight standards on this gas. With the assumption of scavenging, benzene releases become the next most controlling factor. Model results show that a GOR of 0.6 SCF/BBL may be emissions that are within standards. Employing the benzene gas release standard will significantly improve oil deliverability. New plume modeling using the computational fluid dynamics code, FLUENT, is addressing limitations of the state mandated ISCST model.« less

Upward Shift and Steepening of the Blood Pressure Response to Exercise in Hypertensive Subjects at High Altitude.

PubMed

Caravita, Sergio; Faini, Andrea; Baratto, Claudia; Bilo, Grzegorz; Macarlupu, Josè Luis; Lang, Morin; Revera, Miriam; Lombardi, Carolina; Villafuerte, Francisco C; Agostoni, Piergiuseppe; Parati, Gianfranco

2018-06-09

Acute exposure to high-altitude hypobaric hypoxia induces a blood pressure rise in hypertensive humans, both at rest and during exercise. It is unclear whether this phenomenon reflects specific blood pressure hyperreactivity or rather an upward shift of blood pressure levels. We aimed at evaluating the extent and rate of blood pressure rise during exercise in hypertensive subjects acutely exposed to high altitude, and how these alterations can be counterbalanced by antihypertensive treatment. Fifty-five subjects with mild hypertension, double-blindly randomized to placebo or to a fixed-dose combination of an angiotensin-receptor blocker (telmisartan 80 mg) and a calcium-channel blocker (nifedipine slow release 30 mg), performed a cardiopulmonary exercise test at sea level and after the first night's stay at 3260 m altitude. High-altitude exposure caused both an 8 mm Hg upward shift ( P <0.01) and a 0.4 mm Hg/mL/kg per minute steepening ( P <0.05) of the systolic blood pressure/oxygen consumption relationship during exercise, independent of treatment. Telmisartan/nifedipine did not modify blood pressure reactivity to exercise (blood pressure/oxygen consumption slope), but downward shifted ( P <0.001) the relationship between systolic blood pressure and oxygen consumption by 26 mm Hg, both at sea level and at altitude. Muscle oxygen delivery was not influenced by altitude exposure but was higher on telmisartan/nifedipine than on placebo ( P <0.01). In hypertensive subjects exposed to high altitude, we observed a hypoxia-driven upward shift and steepening of the blood pressure response to exercise. The effect of the combination of telmisartan/nifedipine slow release outweighed these changes and was associated with better muscle oxygen delivery. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01830530. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Hypopituitarism

MedlinePlus

... hormone (ACTH) -- stimulates the adrenal gland to release cortisol; cortisol helps to maintain blood pressure and blood sugar ... may include: Brain CT scan Pituitary MRI ACTH Cortisol Estradiol (estrogen) Follicle-stimulating hormone (FSH) Insulin-like ...

Role of atrial receptors in the control of sodium excretion. [pressure breathing and antinatiuretic effects in dogs

NASA Technical Reports Server (NTRS)

Meehan, J. R.; Henry, J. P.

1973-01-01

Responses of an innervated and a contralateral chronically denervated kidney to mild positive pressure breathing are compared for saline volume expansions in chloralose anesthetized dogs. It is shown that mild pressure breathing significantly reduces sodium excretion, urine flow, free water clearance, and PAH clearance. After 20 minutes of positive pressure breathing, both kidney responses are identical suggesting the release of natriuretic hormone which reduces renal function in addition to the demonstrated change in renal nerve activity. Increase of the left atrial pressure through balloon obstruction of the mitral orifice increases urine flow, sodium excretion and PAH clearance; inflation of the balloon and positive pressure breathing again depresses renal function. Preliminary evidence indicates that receptors in the right atrium are more severely affected by pressure breathing than those in the left atrium.

Direct atmospheric pressure chemical ionisation ion trap mass spectrometry for aroma analysis: Speed, sensitivity and resolution of isobaric compounds

NASA Astrophysics Data System (ADS)

Jublot, Lionel; Linforth, Robert S. T.; Taylor, Andrew J.

2005-06-01

Atmospheric pressure chemical ionisation (APCI) sources were developed for real time analysis of volatile release from foods using an ion trap (IT) mass spectrometer (MS). Key objectives were spectral simplicity (minimal fragmentation), response time and signal to noise ratio. The benefits of APCI-IT-MS were assessed by comparing the performance for in vivo and headspace analyses with that obtained using APCI coupled to a quadrupole mass analyser. Using MS-MS, direct APCI-IT-MS was able to differentiate mixtures of some C6 and terpene isobaric aroma compounds. Resolution could be achieved for some compounds by monitoring specific secondary ions. Direct resolution was also achieved with two of the three isobaric compounds released from chocolate with time as the sample was eaten.

Numerical Study of Pressure Influence on Methane-Oxygen Laminar Counterflow Diffusion Flames

NASA Astrophysics Data System (ADS)

Iino, Kimio; Akamatsu, Fumiteru; Katsuki, Masashi

We carried out numerical studies on methane/oxygen diffusion flames of counter-flow configuration to elucidate the influence of pressure on flame structure, heat release rate and reaction mechanisms. The chemistry in gas-phase was based on GRI-Mech 3.0 database. The thickness of diffusion flame became thinner with increasing strain rate a , with its characteristic flame thickness varying inversely with √a, especially its relation became significant with increasing pressure. Flame temperature increased with increasing pressure. Enhanced H2O production reactions, especially chain terminal reactions for H2O production, were found to be important in determining the flame temperature at high pressures. The small reduction in the flame temperature with increasing strain rate at high pressures, compared to the atmospheric pressure, is caused by the capacitor effect of product dissociation. From QRPDs, the third body dependent reactions were enhanced in high pressure conditions, hence C2 pathway was enhanced.

Simply actuated closure for a pressure vessel - Design for use to trap deep-sea animals

NASA Technical Reports Server (NTRS)

Yayanos, A. A.

1977-01-01

A pressure vessel is described that can be closed by a single translational motion within 1 sec. The vessel is a key component of a trap for small marine animals and operates automatically on the sea floor. As the vessel descends to the sea floor, it is subjected both internally and externally to the high pressures of the deep sea. The mechanism for closing the pressure vessel on the sea floor is activated by the timed release of the ballast which was used to sink the trap. As it rises to the sea surface, the internal pressure of the vessel remains near the value present on the sea floor. The pressure vessel has been used in simulated ocean deployments and in the deep ocean (9500 m) with a 75%-85% retention of the deep-sea pressure. Nearly 100% retention of pressure can be achieved by using an accumulator filled with a gas.

[Study on preparation and release mechanism of effervescent osmotic pump tablet of compound Danshen].

PubMed

Xue, Li'an; Li, Yuanbo; Guo, Dandan; Yin, Jianhua; Liu, Yanchun; Hou, Shixiang

2009-04-01

To prepare effervescent osmotic pump tablet (EOPTs) according to the rhythm of coronary heart disease based on efficacy material and the mechanism of compound Danshen and to study the mechanism of drug released of that tablets. Since compound Danshen consist of compounds with polyphenolic groups or carboxyl groups, such as phenolic acids, flavonoids, and triterpenoids that they were acidic. EOPTs were prepared from tablet cores which containing NaHCO3 as effervescent, NaCL and manitol as osmotic agents, HPMC as retarding agents coating with CA membrane. And study the mechanism of drug released according to the change of tablet osmotic pressure. The results of in vitro experiments showed that no difference was observed among the profiles of Danshensu, protocatechuic aldehyde, ginsenoside Rg1, Rb1, notoginsenoside R1 release EOPTs. The drug was completely released from the device with a zero-order release rate over 12 h. EOPTs are Successfully obtained EOPT which the drug is released from the device over 12 h and the release mechanism of EOPTs is explained.

Mars Global Reference Atmospheric Model (Mars-GRAM): Release No. 2 - Overview and applications

NASA Technical Reports Server (NTRS)

James, B.; Johnson, D.; Tyree, L.

1993-01-01

The Mars Global Reference Atmospheric Model (Mars-GRAM), a science and engineering model for empirically parameterizing the temperature, pressure, density, and wind structure of the Martian atmosphere, is described with particular attention to the model's newest version, Mars-GRAM, Release No. 2 and to the improvements incorporated into the Release No. 2 model as compared with the Release No. 1 version. These improvements include (1) an addition of a new capability to simulate local-scale Martian dust storms and the growth and decay of these storms; (2) an addition of the Zurek and Haberle (1988) wave perturbation model, for simulating tidal perturbation effects; and (3) a new modular version of Mars-GRAM, for incorporation as a subroutine into other codes.

Hierarchical Theoretical Methods for Understanding and Predicting Anisotropic Thermal Transport Release in Rocket Propellant Formulations

DTIC Science & Technology

2016-12-08

mesoscopic models of interfaces and interphases, and microstructure-resolved representative volume element simulations. Atomic simulations were...title and subtitle with volume number and part number, if applicable. On classified documents, enter the title classification in parentheses. 5a...careful prediction of the pressure- volume -temperature equation of state, pressure- and temperature-dependent crystal and liquid thermal and transport

New National Blood Pressure Guidelines Are More Rigorous, but OHS Is Here to Help | Poster

Cancer.gov

A task force led by physicians from the American College of Cardiology and the American Heart Association has released new blood pressure guidelines in order to help doctors and clinicians better treat hypertensive and prehypertensive individuals who may be at risk of heart disease. The update, which comes nearly 15 years after its predecessor, has significantly broadened the

Activity of a new hydrogen sulfide-releasing aspirin (ACS14) on pathological cardiovascular alterations induced by glutathione depletion in rats.

PubMed

Rossoni, Giuseppe; Manfredi, Barbara; Tazzari, Valerio; Sparatore, Anna; Trivulzio, Silvio; Del Soldato, Piero; Berti, Ferruccio

2010-12-01

We investigated the effects of the hydrogen sulfide (H₂S)-releasing derivatives of aspirin (ACS14) and salicylic acid (ACS21) in a rat model of metabolic syndrome induced by glutathione (GSH) depletion, causing hypertension and other pathological cardiovascular alterations. GSH depletion was induced in normal rats by the GSH-synthase inhibitor buthionine sulfoximine (BSO, 30 mmol/L day for seven days in the drinking water). Systolic blood pressure and heart rate were measured daily by the tail-cuff method, and plasma thromboxane B₂, 6-keto-prostaglandin F(2α), 8-isoprostane, GSH, insulin and glucose were determined at the end of the seven-day BSO schedule. In addition, ischemia/reperfusion-induced myocardial dysfunction and endothelial dysfunction were assayed on isolated heart and aortic rings, respectively. Unlike aspirin and salicylic acid, ACS14 and ACS21 reduced BSO-induced hypertension, also lowering plasma levels of thromboxane B₂, 8-isoprostane and insulin, while GSH remained in the control range. Neither ACS14 nor ACS21 caused gastric lesions. Both restored the endothelial dysfunction observed in aortic rings from BSO-treated rats, and in ischemia/reperfusion experiments they lowered left ventricular end-diastolic pressure, consequently improving the developed pressure and the maximum rise and fall of left ventricular pressure. Together with this improvement of heart mechanics there were reductions in the activity of creatine kinase and lactate dehydrogenase in the cardiac perfusate. This implies that H₂S released by both ACS14 and ACS21 was involved in protecting the heart from ischemia/reperfusion, and significantly limited vascular endothelial dysfunction in aortic tissue and the related hypertension. Copyright © 2010 Elsevier B.V. All rights reserved.

Effects of exposure to simulated microgravity on neuronal catecholamine release and blood pressure responses to norepinephrine and angiotensin

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Ludwig, D. A.; Gray, B. D.; Vernikos, J.

1998-01-01

We tested the hypothesis that exposure to microgravity reduces the neuronal release of catecholamines and blood pressure responses to norepinephrine and angiotensin. Eight men underwent 30 days of 6 degrees head-down tilt (HDT) bedrest to simulate exposure to microgravity. Plasma norepinephrine and mean arterial blood pressure (MAP) were measured before and after a cold pressor test (CPT) and graded norepinephrine infusion (8, 16 and 32 ng/kg/min) on day 6 of a baseline control period (C6) and on days 14 and 27 of HDT. MAP and plasma angiotensin II (Ang-II) were measured during graded Ang-II infusion (1, 2 and 4 ng/kg/min) on C8 and days 16 and 29 of HDT. Baseline total circulating norepinephrine was reduced from 1017ng during the baseline control period to 610 ng at day 14 and 673ng at day 27 of HDT, confirming a hypoadrenergic state. An elevation of norepinephrine (+178 ng) to the CPT during the baseline control period was eliminated by HDT days 14 and 27. During norepinephrine infusion, similar elevations in plasma norepinephrine (7.7 pg/ml/ng/kg/min) caused similar elevations in MAP (0.12 mmHg/ng/kg/min) across all test days. Ang-II infusion produced higher levels of plasma Ang-II during HDT (47.3 pg/ml) than during baseline control (35.5 pg/ml), while producing similar corresponding elevations in blood pressure. While vascular responsiveness to norepinephrine appears unaffected, impaired neuronal release of norepinephrine and reduced vascular responsiveness to Ang-II might contribute to the lessened capacity to vasoconstrict after spaceflight. The time course of alterations indicates effects that occur within two weeks of exposure.

Shock initiated reactions of reactive multi-phase blast explosives

NASA Astrophysics Data System (ADS)

Wilson, Dennis; Granier, John; Johnson, Richard; Littrell, Donald

2017-01-01

This paper describes a new class of non-ideal explosive compositions made of perfluoropolyether (PFPE), nanoaluminum, and a micron-size, high mass density, reactive metal. Unlike high explosives, these compositions release energy via a fast self-oxidized combustion wave rather than a true self-sustaining detonation. Their reaction rates are shock dependent and they can be overdriven to change their energy release rate. These compositions are fuel rich and have an extended aerobic energy release phase. The term "reactive multiphase blast" refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts energy and momentum [1]; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. Tantalum-based RMBX formulations were tested in two spherical core-shell configurations - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

In vitro characterization and mosquito (Aedes aegypti) repellent activity of essential-oils-loaded nanoemulsions.

PubMed

Nuchuchua, Onanong; Sakulku, Usawadee; Uawongyart, Napaporn; Puttipipatkhachorn, Satit; Soottitantawat, Apinan; Ruktanonchai, Uracha

2009-01-01

The nanoemulsions composed of citronella oil, hairy basil oil, and vetiver oil with mean droplet sizes ranging from 150 to 220 nm were prepared and investigated both in vitro and in vivo. Larger emulsion droplets (195-220 nm) shifted toward a smaller size (150-160 nm) after high-pressure homogenization and resulted in higher release rate. We proposed that thin films obtained from the nanoemulsions with smaller droplet size would have higher integrity, thus increasing the vaporization of essential oils and subsequently prolonging the mosquito repellant activity. The release rates were fitted with Avrami's equations and n values were in the same range of 0.6 to 1.0, implying that the release of encapsulated limonene was controlled by the diffusion mechanism from the emulsion droplet. By using high-pressure homogenization together with optimum concentrations of 5% (w/w) hairy basil oil, 5% (w/w) vetiver oil (5%), and 10% (w/w) citronella oil could improve physical stability and prolong mosquito protection time to 4.7 h due to the combination of these three essential oils as well as small droplet size of nanoemulsion.

Documentation of the Tonge-Ramesh Material Model for Release 2015-06-05-152756

DTIC Science & Technology

2015-10-01

crush curves showing pressure required to initiate pore collapse for pure hydrostatic loading as a function of distension for the 2 different granular...Illustration of the crush curves showing pressure required to initiate pore collapse for pure hydrostatic loading as a function of distension for the 2...is an additional yield surface that depends on only the hydrostatic pressure (p = −1/3tr(σ)). 13 It is defined by fφ(P, J GP , J) =  P Pc−P0

Reconfigurable liquid metal circuits by Laplace pressure shaping

NASA Astrophysics Data System (ADS)

Cumby, Brad L.; Hayes, Gerard J.; Dickey, Michael D.; Justice, Ryan S.; Tabor, Christopher E.; Heikenfeld, Jason C.

2012-10-01

We report reconfigurable circuits formed by liquid metal shaping with <10 pounds per square inch (psi) Laplace and vacuum pressures. Laplace pressure drives liquid metals into microreplicated trenches, and upon release of vacuum, the liquid metal dewets into droplets that are compacted to 10-100× less area than when in the channel. Experimental validation includes measurements of actuation speeds exceeding 30 cm/s, simple erasable resistive networks, and switchable 4.5 GHz antennas. Such capability may be of value for next generation of simple electronic switches, tunable antennas, adaptive reflectors, and switchable metamaterials.

NEUTRONIC REACTION SYSTEM

DOEpatents

Wigner, E.P.

1963-09-01

A nuclear reactor system is described for breeding fissionable material, including a heat-exchange tank, a high- and a low-pressure chamber therein, heat- exchange tubes connecting these chambers, a solution of U/sup 233/ in heavy water in a reaction container within the tank, a slurry of thorium dioxide in heavy water in a second container surrounding the first container, an inlet conduit including a pump connecting the low pressure chamber to the reaction container, an outlet conduit connecting the high pressure chamber to the reaction container, and means of removing gaseous fission products released in both chambers. (AEC)

Combustor oscillation attenuation via the control of fuel-supply line dynamics

DOEpatents

Richards, G.A.; Gemmen, R.S.

1998-09-22

Combustion oscillation control in combustion systems using hydrocarbon fuels is provided by acoustically tuning a fuel-delivery line to a desired phase of the combustion oscillations for providing a pulse of a fuel-rich region at the oscillating flame front at each time when the oscillation produced pressure in the combustion chamber is in a low pressure phase. The additional heat release produced by burning such fuel-rich regions during low combustion chamber pressure effectively attenuates the combustion oscillations to a selected value. 9 figs.

78 FR 6807 - Sunshine Act Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-31

... pressured and emitted powdered debris, hot gases, and molten calcium carbide. The hot gases and debris blown... investigating industrial accidents that result in the release of extremely hazardous substances. The agency's...

Swelling and gas release in oxide fuels during fast temperature transients

NASA Astrophysics Data System (ADS)

Dollins, C. C.; Jursich, M.

1982-05-01

A previously reported intergranular swelling and gas release model for oxide fuels has been modified to predict fission gas behavior during fast temperature transients. Under steady state or slowly varying conditions it has been assumed in the previous model that the pressure caused by the fission gas within the gas bubbles is in equilibrium with the surface tension of the bubbles. During a fast transient, however, net vacancy migration to the bubbles may be insufficient to maintain this equilibrium. In order to ascertain the net vacancy flow, it is necessary to model the point defect behavior in the fuel. Knowing the net flow of vacancies to the bubble and the bubble size, the bubble diffusivity can be determined and the long range migration of the gas out of the fuel can be calculated. The model has also been modified to allow release of all the gas on the grain boundaries during a fast temperature transient. The gas release predicted by the revised model shows good agreement to fast transient gas release data from an EBR-II TREAT H-3 (Transient Reactor Test Facility) test. Agreement has also been obtained between predictions using the model and gas release data obtained by Argonne National Laboratory from out-of-reactor transient heating experiments on irradiated UO 2. It was found necessary to increase the gas bubble diffusivity used in the model by a factor of thirty during the transient to provide agreement between calculations and measurements. Other workers have also found that such an increase is necessary for agreement and attribute the increased diffusivity to yielding at the bubble surface due to the increased pressure.

Crystallographic and magnetic structure of HAVAR under high-pressure using diamond anvil cell (DAC)

NASA Astrophysics Data System (ADS)

Halevy, Itzhak; Haroush, Shlomo; Eisen, Yosef; Silberman, Ido; Moreno, Dany; Hen, Amir; Winterrose, Mike L.; Ghose, Sanjit; Chen, Zhiqiang

2010-04-01

Annealed (H1) and cold-rolled (H2) HAVAR has been studied using high-pressure synchrotron X-ray diffraction. A structural phase transformation was discovered at ˜13 GPa at ambient temperature, transforming from m - 3 m (S.G. 225) to P 63/m m c (S.G. 194) symmetry. The transition was not reversible on pressure release. The low-pressure cubic phase was found to be more compressible than the high-pressure hexagonal phase. Conventional Mössbauer and NFS shows that the HAVAR is not magnetic at room temperature and no splitting is observed. The SQUID indicates a huge difference in the temperature dependence of the magnetic susceptibility between the cold Rolled HAVAR compared to the annealed HAVAR.

Evaluation of Environmental Information Products for Search and Rescue Optimal Planning System (SAROPS) - Version for Public Release

DTIC Science & Technology

2008-02-01

is called EFS-POM. EFS-POM is forced by surface atmospheric forcing (wind, heating / cooling , sea level pressure) and by boundary forcing derived from...Peter Olsson, University of Alaska Anchorage. Heating and cooling is given by the climatological monthly heat flux from COADS (Comprehensive Ocean...Environmental Information Products for Search and Rescue Optimal Planning System (SAROPS) - Version for Public Release FINAL REPORT February

[Preparation of ondansetron hydrochloride osmotic pump tablets and their in vitro drug release].

PubMed

Zheng, Hang-sheng; Bi, Dian-zhou

2005-12-01

To prepare ondansetron hydrochloride osmotic pump tablets (OND-OPT) and investigate their in vitro drug release behavior. OND-OPT were prepared with a single punch press and pan coating technique. Osmotic active agents and plasticizer of coating film were chosen by drug release tests. The effects of the number, position and direction of drug release orifice on release behavior were investigated. The relation between drug release duration and thickness of coating film, PEG content of coating film and size of drug release orifice was established by uniform design experiment. The surface morphological change of coating film before and after drug release test was observed by scanning electron microscopy. The osmotic pumping release mechanism of OND-OPT was confirmed by drug release test with high osmotic pressure medium. Lactose-mannitol (1:2) was chosen as osmotic active agents and PEG400 as plasticizer of coating film. The direction of drug release orifice had great effect on the drug release of OND-OPT without HPMC, and had no effect on the drug release of OND-OPT with HPMC. The OND-OPT with one drug release orifice at the centre of the coating film on one surface of tablet released their drug with little fluctuation. The drug release duration of OND-OPT correlated with thickness of coating film and PEG content of coating film, and didn't correlate significantly with the size of drug release orifice. OND-OPT released their drug with osmotic pumping mechanism predominantly. OND-OPT are able to realize ideal controlled drug release.

Agmatine, an endogenous ligand at imidazoline binding sites, does not antagonize the clonidine-mediated blood pressure reaction

PubMed Central

Raasch, Walter; Schäfer, Ulrich; Qadri, Fatimunnisa; Dominiak, Peter

2002-01-01

Since agmatine has been identified as a clonidine displacing substance (CDS), the aim of this study was to investigate whether agmatine can mimic CDS-induced cardiovascular reactions in organ bath experiments, pithed spontaneously hypertensive rats (SHR) and anaesthetized SHR.Intravenously-administered agmatine significantly reduced the blood pressure and heart rate of anaesthetized SHR at doses higher than 1 and 3 mg kg−1, respectively. These effects are probably mediated via central mechanisms, since there was an approximate 8 fold rightward shift of the dose-response curve in the pithed SHR (indicating a weakened cardiovascular effect). Moreover, in organ bath experiments, agmatine failed to alter the contractility of intact or endothelium-denuded aortal rings. When agmatine was administered i.c.v. to anaesthetized SHR, blood pressure was increased without any alteration of heart rate, whereas blood pressure was unchanged and heart rate was increased after injection into the 4th brain ventricle. This suggests that haemodynamic reaction patterns after central application are related to distinct influences on central cardiovascular mechanisms.Agmatine reduces noradrenaline release in pithed SHR while α2-adrenoceptors are irreversibly blocked with phenoxybenzamine, but not while I1-binding sites are selectively blocked with AGN192403. This suggests that agmatine may modulate noradrenaline release in the same way that clonidine does, i.e. via imidazoline binding sites; this involves a reduction in sympathetic tone which in turn reduces blood pressure and heart rate.Finally, CDS-like cardiovascular activity appears not to be due to agmatine, since (i) blood pressure in anaesthetized SHR is decreased by agmatine and clonidine, and (ii) agmatine did not antagonize the blood pressure reaction to clonidine in pithed or anaesthetized SHR. PMID:11834614

Airway pressure release ventilation and biphasic positive airway pressure: a systematic review of definitional criteria.

PubMed

Rose, Louise; Hawkins, Martyn

2008-10-01

The objective of this study was to identify the definitional criteria for the pressure-limited and time-cycled modes: airway pressure release ventilation (APRV) and biphasic positive airway pressure (BIPAP) available in the published literature. Systematic review. Medline, PubMed, Cochrane, and CINAHL databases (1982-2006) were searched using the following terms: APRV, BIPAP, Bilevel and lung protective strategy, individually and in combination. Two independent reviewers determined the paper eligibility and abstracted data from 50 studies and 18 discussion articles. Of the 50 studies, 39 (78%) described APRV, and 11 (22%) described BIPAP. Various study designs, populations, or outcome measures were investigated. Compared to BIPAP, APRV was described more frequently as extreme inverse inspiratory:expiratory ratio [18/39 (46%) vs. 0/11 (0%), P = 0.004] and used rarely as a noninverse ratio [2/39 (5%) vs. 3/11 (27%), P = 0.06]. One (9%) BIPAP and eight (21%) APRV studies used mild inverse ratio (>1:1 to < or =2:1) (P = 0.7), plus there was increased use of 1:1 ratio [7 (64%) vs. 12 (31%), P = 0.08] with BIPAP. In adult studies, the mean reported set inspiratory pressure (PHigh) was 6 cm H2O greater with APRV when compared to reports of BIPAP (P = 0.3). For both modes, the mean reported positive end expiratory pressure (PLow) was 5.5 cm H2O. Thematic review identified inconsistency of mode descriptions. Ambiguity exists in the criteria that distinguish APRV and BIPAP. Commercial ventilator branding may further add to confusion. Generic naming of modes and consistent definitional parameters may improve consistency of patient response for a given mode and assist with clinical implementation.

40 CFR 63.10906 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... pressure. Capture system means the collection of components used to capture gases and fumes released from... concentrations of compounds of antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury...

40 CFR 63.10906 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... pressure. Capture system means the collection of components used to capture gases and fumes released from... concentrations of compounds of antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury...

40 CFR 63.10906 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... pressure. Capture system means the collection of components used to capture gases and fumes released from... concentrations of compounds of antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury...

Pressure induced structural transitions in CuSbS 2 and CuSbSe 2 thermoelectric compounds

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

Baker, Jason; Kumar, Ravhi S.; Sneed, Daniel

Here, we investigate the structural behavior of CuSbS 2 and CuSbSe 2 thermoelectric materials under high pressure conditions up to 80 GPa using angle dispersive X-ray diffraction in a diamond anvil cell (DAC). We also perform high pressure Raman spectroscopy measurements up to 16 GPa. We observed a pressure-induced structural transformation from the ambient orthorhombic structure with space group Pnma to a triclinic type structure with space group P1 beginning around 8 GPa in both samples and completing at 13 GPa and 10 GPa in CuSbS 2 and CuSbSe 2, respectively. High pressure Raman experiments complement the transitions observed bymore » high pressure X-ray diffraction (HPXRD). Finally, the transitions were found to be reversible on releasing the pressure to ambient in the DAC. The bulk modulus and compressibility of these materials are further discussed.« less

Pressure-induced amorphization of charge ordered spinel AlV{sub 2}O{sub 4} at low temperature

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

Malavi, Pallavi S., E-mail: malavips@barc.gov.in; Karmakar, S., E-mail: malavips@barc.gov.in; Sharma, S. M.

2014-04-24

Structural properties of charge ordered spinel AlV{sub 2}O{sub 4} have been investigated under high pressure at low temperature (80K) by synchrotron based x-ray diffraction measurements. It is observed that upon increasing pressure the structure becomes progressively disordered due to the distortion of the AlO{sub 4} tetrahedral unit and undergoes amorphization above ∼12 GPa. While releasing pressure, the rhombohedral phase is only partially recovered at a much lower pressure (below 5 GPa). Within the stability of the rhombohedral phase, the distortion in the vanadium heptamer increases monotonically with pressure, suggesting enhanced charge ordering. This result is in sharp contrast with themore » recent observation of pressure-induced frustration in the charge ordered state leading to structural transition to the cubic phase at room temperature [JPCM 25, 292201, 2013].« less

Pressure induced structural transitions in CuSbS 2 and CuSbSe 2 thermoelectric compounds

DOE PAGES

Baker, Jason; Kumar, Ravhi S.; Sneed, Daniel; ...

2015-04-27

Here, we investigate the structural behavior of CuSbS 2 and CuSbSe 2 thermoelectric materials under high pressure conditions up to 80 GPa using angle dispersive X-ray diffraction in a diamond anvil cell (DAC). We also perform high pressure Raman spectroscopy measurements up to 16 GPa. We observed a pressure-induced structural transformation from the ambient orthorhombic structure with space group Pnma to a triclinic type structure with space group P1 beginning around 8 GPa in both samples and completing at 13 GPa and 10 GPa in CuSbS 2 and CuSbSe 2, respectively. High pressure Raman experiments complement the transitions observed bymore » high pressure X-ray diffraction (HPXRD). Finally, the transitions were found to be reversible on releasing the pressure to ambient in the DAC. The bulk modulus and compressibility of these materials are further discussed.« less

High pressure study of acetophenone azine

NASA Astrophysics Data System (ADS)

Tang, X. D.; Ding, Z. J.; Zhang, Z. M.

2009-02-01

High pressure Raman spectra of acetophenone azine (APA) have been measured up to 17.7 GPa with a diamond anvil cell. Two crystalline-to-crystalline phase transformations are found at pressures about 3.6 and 5.8 GPa. A disappearance of external modes and the C-H vibration at pressures higher than 8.7 GPa suggests that the sample undergoes a phase transition to amorphous or orientationally disordered (plastic) state, and the amorphization was completed at about 12.1 GPa. The disordered state is unstable and, then, a polymerization transformation reaction occurs with a further pressure increase. After the pressure has been released, the polymerization state can remain at the ambient condition, indicating that the virgin crystalline state is not recovered. The results show that the phenomenon underlying the pressure induced phase transition of APA may involve profound changes in the coordination environments of the symmetric aromatic azine.

"Deflategate": Time, Temperature, and Moisture Effects on Football Pressure

NASA Astrophysics Data System (ADS)

Blumenthal, Jack; Beljak, Lauren; Macatangay, Dahlia-Marie; Helmuth-Malone, Lilly; McWilliams, Catharina; Raptis, Sofia

2016-09-01

In a recent paper in TPT, DiLisi and Rarick used the National Football League "Deflategate" controversy to introduce to physics students the physics of a bouncing ball. In this paper, we measure and analyze the environmental effects of time, ambient temperature, and moisture on the internal pressure of an NFL football. We focus on the rate of pressure recovery that occurs when a cold football (either wet or dry) is returned to the warm locker room environment where the pressure was initially measured. Both studies stem from the so-called NFL "Deflategate" controversy in which footballs that initially met a minimum internal pressure requirement were rechecked at halftime of the AFC Championship game, and in some cases were reported to have fallen below the minimum pressure requirement. The question is whether the pressure changes were due to environmental exposure or rather to some air being released from the balls, or both.

Strong environmental tolerance of Artemia under very high pressure

NASA Astrophysics Data System (ADS)

Minami, K.; Ono, F.; Mori, Y.; Takarabe, K.; Saigusa, M.; Matsushima, Y.; Saini, N. L.; Yamashita, M.

2010-03-01

It was shown by the present authors group that a tardigrade in its tun-state can survive after exposed to 7.5 GPa for 13 hours. We have extended this experiment to other tiny animals searching for lives under extreme conditions of high hydrostatic pressure. Artemia, a kind of planktons, in its dried egg-state have strong environmental tolerance. Dozens of Artemia eggs were sealed in a small Teflon capsule together with a liquid pressure medium, and exposed to the high hydrostatic pressure of 7.5 GPa. After the pressure was released, they were soaked in seawater to observe hatching rate. It was proved that 80-90% of the Artemia eggs were alive and hatched into Nauplii after exposed to the maximum pressure of 7.5 GPa for up to 48 hours. Comparing with Tardigrades, Artemia are four-times stronger against high pressure.

In situ studies of microbial inactivation during high pressure processing

NASA Astrophysics Data System (ADS)

Maldonado, Jose Antonio; Schaffner, Donald W.; Cuitiño, Alberto M.; Karwe, Mukund V.

2016-01-01

High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization.

Study of the hydrostatic pressure dependence of the Raman spectrum of W/WS2 fullerene-like nanosphere with core shell structure

NASA Astrophysics Data System (ADS)

Yu, S. D.; Chang, L. X.; Yang, H. B.; Liu, B. B.; Hou, Y. Y.; Wang, L.; Yao, M. G.; Cui, T.; Zou, G. T.

2007-10-01

The structural behavior of a W/WS2 fullerene-like nanosphere with a core-shell structure has been studied in the hydrostatic pressure range from atmospheric pressure to 18 GPa by Raman spectroscopy using a methanol-ethanol-water mixture (16:3:1) as the pressure transmitting medium (PTM). We found that it is interesting that the intensity ratio of the LA+TA mode and the A1g mode changes with increasing pressure. We attribute this change to the shape transformation of an inorganic fullerene-like IF-W/WS2 nanosphere under high hydrostatic pressure. By comparing the Raman spectra of an IF-W/WS2 nanosphere released from high pressure with that of the original one, we found that the change in morphology is reversible. This indicates that the spherical shape of the IF-W/WS2 has excellent behavior in resisting compression.

Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization

NASA Technical Reports Server (NTRS)

Rinker, Martin; Krueger, Ronald; Ratcliffe, James

2013-01-01

The ground-air pressurization of lightweight honeycomb sandwich structures caused by alternating pressure differences between the enclosed air within the honeycomb core and the ambient environment is a well-known and controllable loading condition of aerospace structures. However, initial face sheet/core disbonds intensify the face sheet peeling effect of the internal pressure load significantly and can decrease the reliability of the sandwich structure drastically. Within this paper, a numerical parameter study was carried out to investigate the criticality of initial disbonds in honeycomb sandwich structures under ground-air pressurization. A fracture mechanics approach was used to evaluate the loading at the disbond front. In this case, the strain energy release rate was computed via the Virtual Crack Closure Technique. Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed.

Solution and shock-induced exsolution of argon in vitreous carbon

NASA Technical Reports Server (NTRS)

Gazis, Carey; Ahrens, Thomas J.

1991-01-01

To add to the knowledge of noble gas solution and exsolution in carbonaceus material, experiments were performed on vitreous carbon. Ar-rich vitreous carbon samples were prepared under vapor-saturated conditions using argon as the pressurizing medium. Solubility data were obtained for temperatures of 773 to 973 K and pressures of 250 to 1500 bars. Up to 7 wt pct Ar was dissolved in the carbon. The solubility data were compared to a thermodynamic model of argon atoms dissolving into a fixed population of 'holes' in the carbon. Two variations of the model yielded estimates of the enthalpy of solution of Ar in vitreous carbon equal to about -4700 cal/mole. Preliminary shock experiments showed that 28 percent of the total argon was released by driving 4 GPa shocks into the argon-rich carbon. It was demonstrated that shock-induced argon loss is not simply caused by the impact-induced diminution of grain size. The present value of shock pressure required for partial impact devolatilization of Ar from carbon is below the range (5-30 GPa) at which H2O is released from phyllosilicates.

Simultaneous determination of Hugoniot and Isentrope in gas gun experiments

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

Thoe, R S

2007-02-22

We have been exploring the use of the ''reverse ballistics'' method to obtain Hugoniot and off Hugoniot Equation Of State. This method uses the unknown sample as the flyer and collides it into a window whose EOS is well known. A VISAR determines the particle velocity which when combined with the windows EOS gives a direct determination of the pressure. Since the pressure and particle velocity are continuous across the interface the shock speed in the flyer can be determined: Us = P/(rhoUp). Subtracting the time of arrival of the shock at the back of the flyer from the timesmore » of arrival of the rarefaction wave allows the determination of the release isentrope centered at the measured Hugoniot point and extending down to the release pressure as determined by the impedance of the sabot. Besides obtaining both Hugoniot and isentrope data on a single shot, this method has an advantage in that all the timing information is accomplished within the interferometer, i.e. no dependence of cable delays etc.« less

Is nifedipine a suitable first-line treatment for essential hypertension in general practice?

PubMed

Sullivan, F M; Murray, T S; Gaw, N; Langan, J J; Adams-Strump, B J

1987-11-01

Nifedipine has been used in hypertension, mainly as a third-line drug for rapid blood pressure reduction, for over 10 years. More recently it has been shown to be effective and safe in reducing mild to moderate blood pressure when used alone in a slow release formulation. A placebo-controlled study investigating the efficacy and safety of nifedipine in comparison with cyclopenthiazide-potassium has now been carried out by 4 general practitioners in the Glasgow area. Ninety-four patients were entered into the study. After a 4-week placebo run-in phase, patients were randomly allocated to receive either slow-release nifedipine 20 mg b.d., or cyclopenthiazide 0.25 mg with 8.1 mmol potassium daily. The dose was doubled at week 8 for non-responders, and at week 12 the alternative drug was added if there was still no response. The patients were studied for up to 28 weeks. Nifedipine was found to have similar blood pressure lowering efficacy to cyclopenthiazide-potassium, but withdrawals from nifedipine due to side-effects at an early stage were more common.

Comparison of ambulatory blood pressure-lowering effects of higher doses of different calcium antagonists in uncontrolled hypertension: the Calcium Antagonist Controlled-Release High-Dose Therapy in Uncontrolled Refractory Hypertensive Patients (CARILLON) Study.

PubMed

Mizuno, Hiroyuki; Hoshide, Satoshi; Tomitani, Naoko; Kario, Kazuomi

2017-10-01

Data are sparse regarding ambulatory blood pressure (BP) reduction of up-titration from a standard dose to a high dose in both nifedipine controlled-release (CR) and amlodipine. This was a prospective, randomized, multicenter, open-label trial. Fifty-one uncontrolled hypertensives medicated by two or more antihypertensive drugs including a renin-angiotensin system inhibitor and a calcium antagonist were randomly assigned to either the nifedipine CR (80 mg)/candesartan (8 mg) group or the amlodipine (10 mg)/candesartan (8 mg) group. The changes in 24-hr BP were comparable between the groups. The nifedipine group demonstrated a significant decrease in their urinary albumin creatinine ratio, whereas the amlodipine group demonstrated a significant decrease in their NTproBNP level. However, there was no significant difference in any biomarkers between the two groups. Nifedipine showed an almost equal effect on ambulatory blood pressure as amlodipine. Their potentially differential effects on renal protection and NTproBNP should be tested in larger samples.

Ketoprofen-β-cyclodextrin inclusion complexes formation by supercritical process technology

NASA Astrophysics Data System (ADS)

Sumarno, Rahim, Rizki; Trisanti, Prida Novarita

2017-05-01

Ketoprofen was a poorly soluble which anti-inflammatory, analgesic and antipyretic drug, solubility of which can be enchanced by form complexation with β-cyclodextrin. Besides that, the inclusion complex reduces the incidence of gastrointestinal side effect of drug. The aims of this research are to study the effect of H2O concentration in the supercritical carbondioxide and operation condition in the formation of ketoprofen-β-Cyclodextrin inclusion complex. This research was began by dissolved H2O in supercritical CO2 at 40°C and various saturation pressures. Then, dissolved H2O contacted with (1:5 w/w) ketoprofen-β-Cyclodextrin mixture at 50°C and various operation pressures. It called saturation process. Saturation was done for ±2 hours with agitation process and continued by decompression process. The products were characterized by drug Release, Differential Scanning Calorimetry (DCS) dan Scanning Electron Microscopy (SEM) analyses. The percentage from this work were 76,82%-89,99% for inclusion complexes. The percentage drug release of ketoprofen were 82,83%-88,36% on various inclusion pressure and various inclusion period.

Molecular dynamics simulations of ejecta production from sinusoidal tin surfaces under supported and unsupported shocks

NASA Astrophysics Data System (ADS)

Wu, Bao; Wu, FengChao; Zhu, YinBo; Wang, Pei; He, AnMin; Wu, HengAn

2018-04-01

Micro-ejecta, an instability growth process, occurs at metal/vacuum or metal/gas interface when compressed shock wave releases from the free surface that contains surface defects. We present molecular dynamics (MD) simulations to investigate the ejecta production from tin surface shocked by supported and unsupported waves with pressures ranging from 8.5 to 60.8 GPa. It is found that the loading waveforms have little effect on spike velocity while remarkably affect the bubble velocity. The bubble velocity of unsupported shock loading remains nonzero constant value at late time as observed in experiments. Besides, the time evolution of ejected mass in the simulations is compared with the recently developed ejecta source model, indicating the suppressed ejection of unmelted or partial melted materials. Moreover, different reference positions are chosen to characterize the amount of ejecta under different loading waveforms. Compared with supported shock case, the ejected mass of unsupported shock case saturates at lower pressure. Through the analysis on unloading path, we find that the temperature of tin sample increases quickly from tensile stress state to zero pressure state, resulting in the melting of bulk tin under decaying shock. Thus, the unsupported wave loading exhibits a lower threshold pressure causing the solid-liquid phase transition on shock release than the supported shock loading.

Airway pressure release ventilation: what do we know?

PubMed

Daoud, Ehab G; Farag, Hany L; Chatburn, Robert L

2012-02-01

Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma, increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). There is confusion regarding this mode of ventilation, due to the different terminology used in the literature. APRV settings include the "P high," "T high," "P low," and "T low". Physicians and respiratory therapists should be aware of the different ways and the rationales for setting these variables on the ventilators. Also, they should be familiar with the differences between APRV, biphasic positive airway pressure (BIPAP), and other conventional and nonconventional modes of ventilation. There is no solid proof that APRV improves mortality; however, there are ongoing studies that may reveal further information about this mode of ventilation. This paper reviews the different methods proposed for APRV settings, and summarizes the different studies comparing APRV and BIPAP, and the potential benefits and pitfalls for APRV.

Release of volatile mercury from vascular plants

NASA Technical Reports Server (NTRS)

Siegel, S. M.; Puerner, N. J.; Speitel, T. W.

1974-01-01

Volatile, organic solvent soluble mercury has been found in leaves and seeds of several angiosperms. Leaves of garlic vine, avocado, and haole-koa release mercury in volatile form rapidly at room temperature. In garlic vine, the most active release is temperature dependent, but does not parallel the vapor-pressure temperature relationship for mercury. Mercury can be trapped in nitric-perchloric acid digestion fluid, or n-hexane, but is lost from the hexane unless the acid mixture is present. Seeds of haole-koa also contain extractable mercury but volatility declines in the series n-hexane (90%), methanol (50%), water (10%). This suggests that reduced volatility may accompany solvolysis in the more polar media.

Measuring Pressure Has a New Standard

NASA Technical Reports Server (NTRS)

2002-01-01

The Force-Balanced Piston Gauge (FPG) tests and calibrates instrumentation operating in the low pressure range. The system provides a traceable, primary calibration standard for measuring pressures in the range of near 0 to 15 kPa (2.2 psi) in both gauge and absolute measurement modes. The hardware combines a large area piston-cylinder with a load cell measuring the force resulting from pressures across the piston. The mass of the piston can be tared out, allowing measurement to start from zero. A pressure higher than the measured pressure, which keeps the piston centered, lubricates an innovative conical gap located between the piston and the cylinder, eliminating the need for piston rotation. A pressure controller based on the control of low gas flow automates the pressure control. DHI markets the FPG as an automated primary standard for very low-gauge and absolute pressures. DHI is selling the FPG to high-end metrology laboratories on a case by case basis, with a full commercial release to follow.

Mobility, Fertility, and Residential Crowding

ERIC Educational Resources Information Center

Morris, Earl W.

1977-01-01

Regression analyses predicting fertility and mobility in a sample of a metropolitan county in New York State indicate that residential mobility serves to release the negative pressure that residential crowding might exert on fertility behavior. (Author)

Blast from pressurized carbon dioxide released into a vented atmospheric chamber

NASA Astrophysics Data System (ADS)

Hansen, P. M.; Gaathaug, A. V.; Bjerketvedt, D.; Vaagsaether, K.

2018-03-01

This study describes the blast from pressurized carbon dioxide (CO2) released from a high-pressure reservoir into an openly vented atmospheric chamber. Small-scale experiments with pure vapor and liquid/vapor mixtures were conducted and compared with simulations. A motivation was to investigate the effects of vent size and liquid content on the peak overpressure and impulse response in the atmospheric chamber. The comparison of vapor-phase CO2 test results with simulations showed good agreement. This numerical code described single-phase gas dynamics inside a closed chamber, but did not model any phase transitions. Hence, the simulations described a vapor-only test into an unvented chamber. Nevertheless, the simulations reproduced the incident shock wave, the shock reflections, and the jet release inside the atmospheric chamber. The rapid phase transition did not contribute to the initial shock strength in the current test geometry. The evaporation rate was too low to contribute to the measured peak overpressure that was in the range of 15-20 kPa. The simulation results produced a calculated peak overpressure of 12 kPa. The liquid tests showed a significantly higher impulse compared to tests with pure vapor. Reducing the vent opening from 0.1 to 0.01 m2 resulted in a slightly higher impulse calculated at 100 ms. The influence of the vent area on the calculated impulse was significant in the vapor-phase tests, but not so clear in the liquid/vapor mixture tests.

Energy consumption and water-soluble protein release by cell wall disruption of Nannochloropsis gaditana.

PubMed

Safi, C; Cabas Rodriguez, L; Mulder, W J; Engelen-Smit, N; Spekking, W; van den Broek, L A M; Olivieri, G; Sijtsma, L

2017-09-01

Several cell disruption methods were tested on Nannochloropsis gaditana, to evaluate their efficiency in terms of cell disintegration, energy input and release of soluble proteins. High-pressure homogenization (HPH) and bead milling were the most efficient with >95% cell disintegration, ±50% (w/w) release of total proteins and low energy input (<0.5kWh.kg -1 biomass ). Enzymatic treatment required low energy input (<0.34kWh.kg -1 biomass ), but it only released ±35% protein (w/w). Pulsed Electric Field (PEF) was neither energy-efficient (10.44kWh.kg -1 biomass ) nor successful for protein release (only 10% proteins w/w) and cell disintegration. The release of proteins after applying HPH and bead milling always required less intensive operating conditions for cell disruption. The energy cost per unit of released protein ranged from 0.15-0.25 €.kg Protein -1 in case of HPH, and up to 2-20 €.kg Protein -1 in case of PEF. Copyright © 2017 Elsevier Ltd. All rights reserved.

Process for fixed bed coal gasification

DOEpatents

Sadowski, Richard S.

1992-01-01

The combustion of gas produced from the combination of coal pyrolysis and gasification involves combining a combustible gas coal and an oxidant in a pyrolysis chamber and heating the components to a temperature of at least 1600.degree. F. The products of coal pyrolysis are dispersed from the pyrolyzer directly into the high temperature gasification region of a pressure vessel. Steam and air needed for gasification are introduced in the pressure vessel and the materials exiting the pyrolyzer flow down through the pressure vessel by gravity with sufficient residence time to allow any carbon to form carbon monoxide. Gas produced from these reactions are then released from the pressure vessel and ash is disposed of.

Groundwater drainage from fissures as a source for lahars

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

Johnson, P. J.; Valentine, G. A.; Stauffer, P. H.

One mechanism for generating lahars at volcanoes experiencing unrest is the disruption of internal aquifers. These disruptions can trigger releases of large quantities of groundwater. An example of such aquifer disruption occurred at Nevado del Huila Volcano, Colombia, during February and April 2007 when large fractures formed across the summit area of the volcano and lahars were emitted from them. Previous work interpreted that lahar volumes could not be accounted for by melted glacial snow or precipitation, and by elimination suggested that the primary water source was groundwater. Conceptual models have been developed for perched, confined aquifers that have beenmore » heated and pressurized by magma intrusions, followed by sudden pressure release and water emission during fracture formation. In this paper, we consider an alternative end member wherein water release from large fissures at volcanoes is driven by simple gravity drainage. We apply numerical modeling to quantify water discharge from the porous medium surrounding a fissure with a low-elevation free exit. If a long fracture with high vertical extent (on the order of hundreds of meters) intersects a highly connected saturated porous medium, large volumes (on order 10 3 m 3/m of crack length) of water may be released within tens of minutes. The drainage rates from the model may be adequate to account for the Nevado del Huila events if the medium surrounding the crack contains a large volume of water and has high horizontal permeability. Finally, this simple but poorly understood mechanism can present a hazard on its own or compound other processes releasing water from volcanoes.« less

Development of Ocular Delivery System for Glaucoma Therapy Using Natural Hydrogel as Film Forming Agent and Release Modifier.

PubMed

Kulkarni, Giriraj T; Sethi, Nitin; Awasthi, Rajendra; Pawar, Vivek Kumar; Pahuja, Vineet

2016-01-01

Glaucoma is characterized by increased intraocular pressure, which results in damage to the optic nerve. The existing therapy with conventional eye drops is inefficient due to nasolachrymal drainage, resulting in a reduced corneal residence of the drug. The objective was to develop controlled-release ocular films of timolol maleate using natural hydrogel from Tamarindus indica seeds as a sustaining and film-forming agent, to overcome the problems associated with eye drops. The hydrogel was isolated using hot aqueous extraction followed by precipitation with ethanol. Six batches of ocular films were prepared and evaluated for drug content, weight variation, thickness, diameter and in vitro release profile. The ideal batch of the films was subjected to stability, pharmacodynamic and ocular safety studies. The yield of the hydrogel was 58.29%. The thickness of the ocular films was in the range of 0.17 to 0.25 mm and the weight of the films was found to increase with the increase in polymer content. The drug release from the films was found to be controlled over a period of 8 h. The films were found to be stable and were able to reduce the intraocular pressure for 24 h in a more efficient manner than the eye drops. The films were found to be practically non-irritating to the eye. It can be concluded that the hydrogel from tamarind seeds can be used as a film-forming and release-controlling agent for the development of an ocular drug delivery system for the effective therapy of glaucoma.

Groundwater drainage from fissures as a source for lahars

NASA Astrophysics Data System (ADS)

Johnson, P. J.; Valentine, G. A.; Stauffer, P. H.; Lowry, C. S.; Sonder, I.; Pulgarín, B. A.; Santacoloma, C. C.; Agudelo, A.

2018-04-01

One mechanism for generating lahars at volcanoes experiencing unrest is the disruption of internal aquifers. These disruptions can trigger releases of large quantities of groundwater. An example of such aquifer disruption occurred at Nevado del Huila Volcano, Colombia, during February and April 2007 when large fractures formed across the summit area of the volcano and lahars were emitted from them. Previous work interpreted that lahar volumes could not be accounted for by melted glacial snow or precipitation, and by elimination suggested that the primary water source was groundwater. Conceptual models have been developed for perched, confined aquifers that have been heated and pressurized by magma intrusions, followed by sudden pressure release and water emission during fracture formation. We consider an alternative end member wherein water release from large fissures at volcanoes is driven by simple gravity drainage. We apply numerical modeling to quantify water discharge from the porous medium surrounding a fissure with a low-elevation free exit. If a long fracture with high vertical extent (on the order of hundreds of meters) intersects a highly connected saturated porous medium, large volumes (on order 103 m3/m of crack length) of water may be released within tens of minutes. The drainage rates from the model may be adequate to account for the Nevado del Huila events if the medium surrounding the crack contains a large volume of water and has high horizontal permeability. This simple but poorly understood mechanism can present a hazard on its own or compound other processes releasing water from volcanoes.

Dimorphic ejaculates and sperm release strategies associated with alternative mating behaviors in the squid.

PubMed

Apostólico, Lígia H; Marian, José E A R

2017-11-01

Sperm competition is a powerful postcopulatory selective force influencing male adaptations associated with increasing fertilization success, and it is usually related to the evolution of different strategies of ejaculate expenditure between individuals. Ejaculates may also be influenced by additional selective pressures associated with sperm competition, such as timing between insemination and fertilization, female reproductive tract morphology, and fertilization environment. Also, males that adopt alternative mating tactics may face distinct sperm competition pressures, which may lead to the evolution of intraspecific diversity in ejaculates. In loliginid squids, males with alternative reproductive tactics (sneakers and consorts) differ not only in mating behavior, but also transfer spermatophores into two distinct sites within the female. Here, we compared structure and functioning of spermatophores between sneakers and consorts in the squid Doryteuthis plei applying microscopy techniques and in vitro experiments. Sneakers and consorts exhibit differences in spermatophore structure that lead to distinct spermatophoric reactions and spermatangium morphologies. Moreover, in sneakers, sperm release lasts longer and their sperm show an aggregative behavior not detected in consorts. Slow sperm release may be a strategy to guarantee longer sperm provision, given the wide interval between sneaker mating and egg release. For consorts, in turn, intense and quick sperm discharge may be advantageous, as timing between mating and egg-laying is relatively short. Within the complex squid mating system, factors such as (i) different fertilization sites and (ii) interval between mating and egg release may also influence sperm competition, and ultimately shape the evolution of divergent ejaculates between dimorphic males. © 2017 Wiley Periodicals, Inc.

Groundwater drainage from fissures as a source for lahars

DOE PAGES

Johnson, P. J.; Valentine, G. A.; Stauffer, P. H.; ...

2018-03-22

One mechanism for generating lahars at volcanoes experiencing unrest is the disruption of internal aquifers. These disruptions can trigger releases of large quantities of groundwater. An example of such aquifer disruption occurred at Nevado del Huila Volcano, Colombia, during February and April 2007 when large fractures formed across the summit area of the volcano and lahars were emitted from them. Previous work interpreted that lahar volumes could not be accounted for by melted glacial snow or precipitation, and by elimination suggested that the primary water source was groundwater. Conceptual models have been developed for perched, confined aquifers that have beenmore » heated and pressurized by magma intrusions, followed by sudden pressure release and water emission during fracture formation. In this paper, we consider an alternative end member wherein water release from large fissures at volcanoes is driven by simple gravity drainage. We apply numerical modeling to quantify water discharge from the porous medium surrounding a fissure with a low-elevation free exit. If a long fracture with high vertical extent (on the order of hundreds of meters) intersects a highly connected saturated porous medium, large volumes (on order 10 3 m 3/m of crack length) of water may be released within tens of minutes. The drainage rates from the model may be adequate to account for the Nevado del Huila events if the medium surrounding the crack contains a large volume of water and has high horizontal permeability. Finally, this simple but poorly understood mechanism can present a hazard on its own or compound other processes releasing water from volcanoes.« less

Impact of methane flow through deformable lake sediments on atmospheric release

NASA Astrophysics Data System (ADS)

Scandella, B.; Juanes, R.

2010-12-01

Methane is a potent greenhouse gas that is generated geothermally and biologically in lake and ocean sediments. Free gas bubbles may escape oxidative traps and contribute more to the atmospheric source than dissolved methane, but the details of the methane release depend on the interactions between the multiple fluid phases and the deformable porous medium. We present a model and supporting laboratory experiments of methane release through “breathing” dynamic flow conduits that open in response to drops in the hydrostatic load on lake sediments, which has been validated against a high-resolution record of free gas flux and hydrostatic pressure in Upper Mystic Lake, MA. In contrast to previous linear elastic fracture mechanics analysis of gassy sediments, the evolution of gas transport in a deformable compliant sediment is presented within the framework of multiphase poroplasticity. Experiments address how strongly the mode and rate of gas flow, captured by our model, impacts the size of bubbles released into the water column. A bubble's size in turn determines how efficiently it transports methane to the atmosphere, and integrating this effect will be critical to improving estimates of the atmospheric methane source from lakes. Cross-sectional schematic of lake sediments showing two venting sites: one open at left and one closed at right. The vertical release of gas bubbles (red) at the open venting site creates a local pressure drop, which drives both bubble formation from the methane-rich pore water (higher concentrations shaded darker red) and lateral advection of dissolved methane (purple arrows). Even as bubbles in the open site escape, those at the closed site remain trapped.

Chemical Reactions in Turbulent Mixing Flows

DTIC Science & Technology

1989-06-01

combustion to be studied over a range of pressures of 0.1 atm < po < 10atm, permitting a range of two decades of Reynolds number to be covered. Depending on ...The effects of heat release were studied in a planar, gaseous reacting mixing layer formed between two sub- sonic freestreams; one containing hydrogen...and the Reynolds number study of Mungal et al (1985). The issue of heat release effects on the flow was specifically addressed elsewhere (see

A highly addressable static droplet array enabling digital control of a single droplet at pico-volume resolution.

PubMed

Jeong, Heon-Ho; Lee, Byungjin; Jin, Si Hyung; Jeong, Seong-Geun; Lee, Chang-Soo

2016-04-26

Droplet-based microfluidics enabling exquisite liquid-handling has been developed for diagnosis, drug discovery and quantitative biology. Compartmentalization of samples into a large number of tiny droplets is a great approach to perform multiplex assays and to improve reliability and accuracy using a limited volume of samples. Despite significant advances in microfluidic technology, individual droplet handling in pico-volume resolution is still a challenge in obtaining more efficient and varying multiplex assays. We present a highly addressable static droplet array (SDA) enabling individual digital manipulation of a single droplet using a microvalve system. In a conventional single-layer microvalve system, the number of microvalves required is dictated by the number of operation objects; thus, individual trap-and-release on a large-scale 2D array format is highly challenging. By integrating double-layer microvalves, we achieve a "balloon" valve that preserves the pressure-on state under released pressure; this valve can allow the selective releasing and trapping of 7200 multiplexed pico-droplets using only 1 μL of sample without volume loss. This selectivity and addressability completely arranged only single-cell encapsulated droplets from a mixture of droplet compositions via repetitive selective trapping and releasing. Thus, it will be useful for efficient handling of miniscule volumes of rare or clinical samples in multiplex or combinatory assays, and the selective collection of samples.

Cren(ulation)-­1,2 Preshot Report

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

Rousculp, Christopher L.; Oro, David Michael; Griego, Jeffrey Randall

2015-12-21

There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the RichtmyerMeshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacentmore » to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release.« less

Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

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

Rousculp, Christopher L.; Oro, David Michael; Margolin, Len G.

2015-08-06

There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer-Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface is adjacentmore » to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release.« less

Lunar volcanism produced a transient atmosphere around the ancient Moon

NASA Astrophysics Data System (ADS)

Needham, Debra H.; Kring, David A.

2017-11-01

Studies of the lunar atmosphere have shown it to be a stable, low-density surface boundary exosphere for the last 3 billion years. However, substantial volcanic activity on the Moon prior to 3 Ga may have released sufficient volatiles to form a transient, more prominent atmosphere. Here, we calculate the volume of mare basalt emplaced as a function of time, then estimate the corresponding production of volatiles released during the mare basalt-forming eruptions. Results indicate that during peak mare emplacement and volatile release ∼3.5 Ga, the maximum atmospheric pressure at the lunar surface could have reached ∼1 kPa, or ∼1.5 times higher than Mars' current atmospheric surface pressure. This lunar atmosphere may have taken ∼70 million years to fully dissipate. Most of the volatiles released by mare basalts would have been lost to space, but some may have been sequestered in permanently shadowed regions on the lunar surface. If only 0.1% of the mare water vented during these eruptions remains in the polar regions of the Moon, volcanically-derived volatiles could account for all hydrogen deposits - suspected to be water - currently observed in the Moon's permanently shadowed regions. Future missions to such locations may encounter evidence of not only asteroidal, cometary, and solar wind-derived volatiles, but also volatiles vented from the interior of the Moon.

Production of reactive oxygen species from abraded silicates. Implications for the reactivity of the Martian soil

NASA Astrophysics Data System (ADS)

Bak, Ebbe N.; Zafirov, Kaloyan; Merrison, Jonathan P.; Jensen, Svend J. Knak; Nørnberg, Per; Gunnlaugsson, Haraldur P.; Finster, Kai

2017-09-01

The results of the Labeled Release and the Gas Exchange experiments conducted on Mars by the Viking Landers show that compounds in the Martian soil can cause oxidation of organics and a release of oxygen in the presence of water. Several sources have been proposed for the oxidizing compounds, but none has been validated in situ and the cause of the observed oxidation has not been resolved. In this study, laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates, a process that is common on the Martian surface, can give rise to oxidants in the form of hydrogen peroxide (H2O2) and hydroxyl radicals (ṡOH). We found that silicate samples abraded in simulated Martian atmospheres gave rise to a significant production of H2O2 and ṡOH upon contact with water. Our experiments demonstrated that abraded silicates could lead to a production of H2O2 facilitated by atmospheric O2 and inhibited by carbon dioxide. Furthermore, during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the Martian surface pressure we observed glow discharges. Electrical discharges can cause dissociation of CO2 and through subsequent reactions lead to a production of H2O2. These results indicate that the reactions linked to electrical discharges are the dominant source of H2O2 during saltation of silicates in a simulated Martian atmosphere, given the low pressure and the relatively high concentration of CO2. Our experiments provide evidence that wind driven abrasion could enhance the reactivity of the Martian soil and thereby could have contributed to the oxidation of organic compounds and the O2 release observed in the Labeled Release and the Gas Exchange experiments. Furthermore, the release of H2O2 and ṡOH from abraded silicates could have a negative effect on the persistence of organic compounds in the Martian soil and the habitability of the Martian surface.

“A System for Automatically Maintaining Pressure in a Commercial Truck Tire”

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

Maloney, John

2017-07-07

Under-inflated tires significantly reduce a vehicle’s fuel efficiency by increasing rolling resistance (drag force). The Air Maintenance Technology (“AMT”) system developed through this project replenishes lost air and maintains optimal tire cavity pressure whenever the tire is rolling in service, thus improving overall fuel economy by reducing the tire’s rolling resistance. The system consists of an inlet air filter, an air pump driven by tire deformation during rotation, and a pressure regulating device. Pressurized air in the tire cavity naturally escapes by diffusion through the tire and wheel, leaks in tire seating, and through the filler valve and its seating.more » As a result, tires require constant maintenance to replenish lost air. Since manual tire inflation maintenance is both labor intensive and time consuming, it is frequently overlooked or ignored. By automating the maintenance of optimal tire pressure, the tire’s contribution to the vehicle’s overall fuel economy can be maximized. The work was divided into three phases. The objectives of Phase 1, Planning and Initial Design, resulted in an effective project plan and to create a baseline design. The objectives for Phase 2, Design and Process Optimization, were: to identify finalized design for the pump, regulator and filter components; identify a process to build prototype tires; assemble prototype tires; test prototype tires and document results. The objectives of Phase 3, Design Release and Industrialization, were to finalize system tire assembly, perform release testing and industrialize the assembly process.« less

A methodology for combustion detection in diesel engines through in-cylinder pressure derivative signal

NASA Astrophysics Data System (ADS)

Luján, José M.; Bermúdez, Vicente; Guardiola, Carlos; Abbad, Ali

2010-10-01

In-cylinder pressure measurement has historically been used for off-line combustion diagnosis, but online application for real-time combustion control has become of great interest. This work considers low computing-cost methods for analysing the instant variation of the chamber pressure, directly obtained from the electric signal provided by a traditional piezoelectric sensor. Presented methods are based on the detection of sudden changes in the chamber pressure, which are amplified by the pressure derivative, and which are due to thermodynamic phenomena within the cylinder. Signal analysis tools both in time and in time-frequency domains are used for detecting the start of combustion, the end of combustion and the heat release peak. Results are compared with classical thermodynamic analysis and validated in several turbocharged diesel engines.

Release of substance P from the cat spinal cord.

PubMed Central

Go, V L; Yaksh, T L

1987-01-01

1. The present experiments examine the physiology and pharmacology of the release of substance P-like immunoreactivity (SP-l.i.), from the spinal cord in the halothane-anaesthetized, artificially ventilated cat. 2. Resting release of SP-l.i. was 36 +/- 4 fmol/30 min (mean +/- S.E.; n = 106). Bilateral stimulation of the sciatic nerves at intensities which evoked activity in fibres conducting at A beta conduction velocities (greater than 40 m/s), resulted in no change in blood pressure, pupil diameter or release of SP-l.i. Stimulation intensities which activate fibres conducting at velocities less than 2 m/s resulted in increased blood pressure, miosis and elevated release of SP-l.i. (278 +/- 16% of control). 3. The relationship between nerve-stimulation frequency and release was monotonic up to approximately 20 Hz. Higher stimulation frequencies did not increase the amounts of SP-l.i. released. At 200 Hz there was a reduction. 4. Capsaicin (0.1 mM) increased the release of SP-l.i. from the spinal cord and resulted in an acute desensitization to subsequent nerve stimulation. This acute effect was not accompanied by a reduction in spinal levels of SP-l.i. measured 2 h after stimulation. 5. Cold block of the cervical spinal cord resulted in an increase in the amounts of SP-l.i. released by nerve stimulation. 6. Pre-treatment with intrathecal 5,6-dihydroxytryptamine (300 micrograms) 7 days prior to the experiment caused a reduction in the dorsal and ventral horn stores of SP-l.i., but had no effect on the release of SP-l.i. evoked by nerve stimulation. Similar pre-treatment with intrathecal capsaicin (300 micrograms) resulted in depletion of SP-l.i. in the dorsal but not in the ventral horn of the spinal cord and diminished the release of SP-l.i. evoked by nerve stimulation. 7. Intense thermal stimulation of the flank resulted in small (20-35%), but reliable increases in the release of SP-l.i. above control. 8. Putative agonists for the opioid mu-receptor (morphine, 10-100 microM; sufentanil, 1 microM), and for the delta-receptor (D-Ala2-D-Leu5-enkephalin, 1-10 microM; D-Pen2-D-Pen5-enkephalin, 10 microM), but not the kappa-receptor (U50488H, 100-1000 microM), produced a dose-dependent, naloxone-reversible reduction of the evoked, but not of the resting release of SP-l.i. (-)-Naloxone, but not (+)-naloxone, resulted in a significant increase in evoked but not resting SP-l.i. release.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2451003

System and process for capture of acid gasses at elevated pressure from gaseous process streams

DOEpatents

Heldebrant, David J.; Koech, Phillip K.; Linehan, John C.; Rainbolt, James E.; Bearden, Mark D.; Zheng, Feng

2016-09-06

A system, method, and material that enables the pressure-activated reversible chemical capture of acid gasses such as CO.sub.2 from gas volumes such as streams, flows or any other volume. Once the acid gas is chemically captured, the resulting product typically a zwitterionic salt, can be subjected to a reduced pressure whereupon the resulting product will release the captures acid gas and the capture material will be regenerated. The invention includes this process as well as the materials and systems for carrying out and enabling this process.

Speed control with end cushion for high speed air cylinder

DOEpatents

Stevens, Wayne W.; Solbrig, Charles W.

1991-01-01

A high speed air cylinder in which the longitudinal movement of the piston within the air cylinder tube is controlled by pressurizing the air cylinder tube on the accelerating side of the piston and releasing pressure at a controlled rate on the decelerating side of the piston. The invention also includes a method for determining the pressure required on both the accelerating and decelerating sides of the piston to move the piston with a given load through a predetermined distance at the desired velocity, bringing the piston to rest safely without piston bounce at the end of its complete stroke.

Zero Boil-OFF Tank Hardware Setup

NASA Image and Video Library

2017-09-19

iss053e027051 (Sept. 19, 2017) --- Flight Engineer Joe Acaba works in the U.S. Destiny laboratory module setting up hardware for the Zero Boil-Off Tank (ZBOT) experiment. ZBOT uses an experimental fluid to test active heat removal and forced jet mixing as alternative means for controlling tank pressure for volatile fluids. Rocket fuel, spacecraft heating and cooling systems, and sensitive scientific instruments rely on very cold cryogenic fluids. Heat from the environment around cryogenic tanks can cause their pressures to rise, which requires dumping or "boiling off" fluid to release the excess pressure, or actively cooling the tanks in some way.

The Effect of Airway Pressure Release Ventilation on Pulmonary Catheter Readings: Specifically Pulmonary Capillary Wedge Pressure in a Swine Model

DTIC Science & Technology

2011-01-01

pressure (PEEP) of 5 cm H2O was initiated. Ventilator mode was changed to APRV with incremental elevations of CPAP -high from 10 to 35 cm H2O. After a...Results. Increasing CPAP caused increased PCWP and LAPmeasurements above their baseline values. Mean PCWP and LAP were linearly related (LAP = 0.66...PCWP + 4.5 cmH2O, R2 = 0.674, and P < .001) over a wide range of high and low CPAP values during APRV. With return to conventional ventilation, PCWP

Development of Photon Doppler Velocimeter for Explosives Research

DTIC Science & Technology

2013-01-01

free surface of the steel plate as a rarefaction wave. This rarefaction wave pulls back the particles of the metal plate which manifests itself in the...reduction of the free surface velocity by ∆ufs in Figure 12. The rarefaction wave interacts with the still oncoming rarefaction wave behind the...material stipulates that the shockwave consists of the region where the pressure suddenly rises, and a release, or rarefaction behind the peak pressure

Demonstration of Energy Savings in Commercial Buildings for Tiered Trim and Respond Method in Resetting Static Pressure for VAV Systems

DTIC Science & Technology

2017-03-01

FINAL REPORT Demonstration of Energy Savings in Commercial Buildings for Tiered Trim and Respond Method in Resetting Static Pressure for VAV...release Page Intentionally Left Blank This report was prepared under contract to the Department of Defense Environmental Security Technology...Certification Program (ESTCP). The publication of this report does not indicate endorsement by the Department of Defense, nor should the contents be

Shock Propagation In Crustal Rock

DTIC Science & Technology

1991-04-29

liquid produced above the melting point during unloading. Figure 5 displays calculations of release adiabats in the mixed phase regime based on the...muscovite [Bridgman, 1949]. The zero-pressure densities at points 1, 2 and 3 correspond to mixtures of orthoclase + A1203+H20, of wadeite + kyanite ...shocked tantalum and the high pressure melting point , in Shock Waves in Condensed Matter-1983, edited by J. R. Asay, R. A. Graham and G. K. Straub, pp. 91

PEG modulated release of etanidazole from implantable PLGA/PDLA discs.

PubMed

Wang, Fangjing; Lee, Timothy; Wang, Chi-Hwa

2002-09-01

In this work, etanidazole (one type of hypoxic radiosensitizer) is encapsulated into spray dried poly(D),L-lactide-co-glycolide) (PLGA) microspheres and then compressed into discs for controlled release applications. Etanidazole is characterized by intracellular glutathione depletion and glutathione transferases inhibition, thereby enhancing sensitivity to radiation. It is also cytotoxic to tumor cells and can chemosensitize some alkylating agents by activating their tumor cell killing capabilities. We observed the release characteristics of etanidazole in the dosage forms of microspheres and discs, subjected to different preparation conditions. The release characteristics, morphology changes, particle size, and encapsulation efficiency of microspheres are also investigated. The release rate of etanidazole from implantable discs (13 mm in diameter, 1 mm in thickness, fabricated by a press) is much lower than microspheres due to the reduced specific surface. After the initial burst of 1% release for the first day, the cumulative release within the first week is less than 2% until a secondary burst of release (caused by polymer degradation) occurs after one month. Some key preparation conditions such as drug loadings, disc thickness and diameter, and compression pressure can affect the initial burst of etanidazole from the discs. However, none of them can significantly make the release more uniform. In contrast, the incorporation of polyethylene glycol (PEG) can greatly enhance the release rate of discs and also reduces the secondary burst effect, thereby achieving a sustained release for about 2 months.

Factors affecting symptoms and functionality of patients with carpal tunnel syndrome: a retrospective study

PubMed Central

Yucel, Hulya

2015-01-01

[Purpose] The aim of this retrospective study was to determine the associations between clinical, physical, and neurophysiological outcomes and self-reported symptoms and functions of patients after surgical carpal tunnel release. [Subjects and Methods] Among 261 patients who had undergone open surgical carpal tunnel release within the last three years, 83 (mean age 50.27 ± 11.13 years) participated in this study. Their socio-demographics and comorbidities were recorded. The intensity of pain, paresthesia, and fatigue symptoms in the hand were assessed by means of a Visual Analogue Scale, the Semmes-Weinstein Monofilaments test of light touch pressure sensation, and Jamar dynamometry for measurement of grip and pinch strengths. The Boston Carpal Tunnel Questionnaire evaluated the severity of symptoms and hand functional status, and the variables were analyzed by multivariate linear regression. [Results] The severity of the symptoms and functional status of release surgery patients was associated with diabetes mellitus, migraine, night pain, paresthesia and fatigue symptoms, impaired light touch pressure, and lack of medical treatment. [Conclusion] Appropriate post-surgery treatment programs for these factors should be taken into consideration to help patients obtain optimal functionality and health in their daily lives. PMID:25995565

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Shibata, M.; Torigoe, M.; Matsumoto, Y.; Yamamoto, M.; Takizawa, N.; Hada, Y.; Mori, Y.; Takarabe, K.; Ono, F.

2014-05-01

Our studies on the tolerance of plants and animals against very high pressure of several GPa have been extended to a smaller sized fungus, the budding yeast Saccharomyces cerevisiae. Several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate, and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar. It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for longer than 12 h were found dead. The high pressure tolerance of budding yeast is a little weaker than that of tardigrades.

Significant improvement in Mn2O3 transition metal oxide electrical conductivity via high pressure

PubMed Central

Hong, Fang; Yue, Binbin; Hirao, Naohisa; Liu, Zhenxian; Chen, Bin

2017-01-01

Highly efficient energy storage is in high demand for next-generation clean energy applications. As a promising energy storage material, the application of Mn2O3 is limited due to its poor electrical conductivity. Here, high-pressure techniques enhanced the electrical conductivity of Mn2O3 significantly. In situ synchrotron micro X-Ray diffraction, Raman spectroscopy and resistivity measurement revealed that resistivity decreased with pressure and dramatically dropped near the phase transition. At the highest pressure, resistivity reduced by five orders of magnitude and the sample showed metal-like behavior. More importantly, resistivity remained much lower than its original value, even when the pressure was fully released. This work provides a new method to enhance the electronic properties of Mn2O3 using high-pressure treatment, benefiting its applications in energy-related fields. PMID:28276479

An approach to constrained aerodynamic design with application to airfoils

NASA Technical Reports Server (NTRS)

Campbell, Richard L.

1992-01-01

An approach was developed for incorporating flow and geometric constraints into the Direct Iterative Surface Curvature (DISC) design method. In this approach, an initial target pressure distribution is developed using a set of control points. The chordwise locations and pressure levels of these points are initially estimated either from empirical relationships and observed characteristics of pressure distributions for a given class of airfoils or by fitting the points to an existing pressure distribution. These values are then automatically adjusted during the design process to satisfy the flow and geometric constraints. The flow constraints currently available are lift, wave drag, pitching moment, pressure gradient, and local pressure levels. The geometric constraint options include maximum thickness, local thickness, leading-edge radius, and a 'glove' constraint involving inner and outer bounding surfaces. This design method was also extended to include the successive constraint release (SCR) approach to constrained minimization.

Shock Pressures, Temperatures and Durations in L Chondrites: Constraints from Shock-Vein Mineralogy

NASA Astrophysics Data System (ADS)

Xie, Z.; Aramovish Weaver, C.; Decarli, P. S.; Sharp, T. G.

2003-12-01

Shock effects in meteorites provide a record of major impact events on meteorite parent bodies. Shock veins in chondrites, which result from local melting during shock loading, are the location of all high-pressure minerals. Shock veins contain igneous assemblages, produced by the crystallization of shock-induced melt, and metamorphic assemblages, produced by solid-state transformation in entrained host-rock clasts and wall rock. The mineralogy, distribution of high-pressure minerals and microstructures in shock veins provide a record of crystallization pressures and quench histories that can be used to constrain shock pressures and pulse duration. Here we report mineralogical and microstructural studies of shock-induced melt veins in L chondrites that provide insight into the impact history of the L-chondrite parent body. Eight L6 chondrites were investigated using FESEM and TEM and Raman spectroscopy: RC 106 (S6), Tenham (S6), Umbarger (S4-S6), Roy (S3-S5), Ramsdorf (S4), Kunashak (S4), Nakhon Pathon (S4) and La Lande (S4). Igneous melt-vein assemblages, combined with published phase equilibrium data (Agee et al. 1996), indicate crystallization pressures from less than 2.5 GPa for Kunashack and LaLande to approximately 25 GPa for Tenham. Because shock veins quench primarily by thermal conduction, crystallization starts at vein edges and progresses inward. Variation in the igneous assemblage across shock veins, combined with thermal modelling, provides constraints on quench times and pressure variation during quench. Most samples appear to have crystallized prior to shock release, whereas Kunashack and LaLande apparently crystallized after pressure release. RC 106 and Tenham (both S6), which have thick melt veins with uniform igneous assemblages, crystallized under equilibrium shock pressures of approximately 22-25 GPa during shock events that lasted at least 500 ms and 50ms, respectively. The fact that S6 samples do not appear to have crystallized at a pressures greater than about 25 GPa, suggest that the impacts that produced shock veins in chondrites had low relative impact velocities.

Condensation Heat Transfer of Steam on a Single Horizontal Tube.

DTIC Science & Technology

1983-06-01

public release; distribution unlimited 88 09 07 1?0 L_ I jmmAzzLEim. SICUR1TY CLASStFICATION o« THIS r-AOt (*»*< Data Enf«r»d) REPORT...steam side data were taken at atmospheric pressure to test the data acquisition/reduction computer programs.^— S N 0102- LF. 014-1601 Accession For...Dlst H Special UNCLASSIFIED ItCUHlTV CLASSIFICATION O» TMI( PAOtyWft«! Data >*H mtm Im. ! Approved for public release; distribution

Effects of Aminoguanidine on Pre- and Post-Irradiation Regional Cerebral Blood Flow, Systemic Blood Pressure and Plasma Histamine Levels in the Primate,

DTIC Science & Technology

1991-01-01

released HA may not be the sole mediator of these effects. Because elevations in plasma HA are probably due to HA derived from degranulation of mast cells ...release of other bioactive substances from mast cells may also influence these cardiovascular effects. Surprisingly, in sham-irradiated monkeys. AG...histaminergic nificantly altered by the administration ofAG. Al- mechanisms may be misguided. Mast cells , the though the two irradiated groups were

[Effect of slow-release aminophylline on pulmonary function in obstructive respiratory disease(author's transl)].

PubMed

Wiessmann, K J

1975-09-05

The effects on pulmonary function of a slow-release preparation of an oral broncholytic drug (containing 350 mg aminophylline, released over eight hours) was tested on 26 patients in a double-blind trial. There was a marked reduction of airway resistance and stimulation of breathing with decreased dynamic work of breathing. Distinctly improved alveolar function was demonstrated especially in a fall of arterial CO2 tension, but in some cases there was probably an increase in distribution abnormality. Central haemodynamic changes with a decreased in pulmonary artery pressure and changes in the other values lasted for more than ten hours on the first day of treatment, and were demonstrable on the fourth day even before the drug was taken that day. The criteria of an effective broncholytic slow-release drug with sustained effect were thus fulfilled.

Poly(ethylene glycol)/chitosan/sodium glycerophosphate gel replaced the joint capsule with slow-release lubricant after joint surgery.

PubMed

Lu, Hailin; Ren, Shanshan; Li, Xing; Guo, Junde; Dong, Guangneng; Li, Jianhui; Gao, Li

2018-08-01

Body fluid is normally the only lubricant after joint replacement surgery, but wear problems have occurred because body fluid has poor lubrication ability. However, traditional lubricant would be diluted by body fluids and then absorbed by the human body. Therefore, an injectable gel with the ability to slow-release lubricant was designed to replace the joint capsule. The proposed gel, poly(ethylene glycol)/chitosan/sodium glycerophosphate (PEG/CS/GP) composite gel was then tested. The tribology results showed that the PEG/CS/GP gel had excellent slow-release properties, especially under pressure, and the PEG played an important role in improving the gel's rheological and mechanical properties. Moreover, this study revealed that the release solution had a good lubrication effect because the PEG and GP could crosslink via the hydrogen bond effect.

40 CFR 280.44 - Methods of release detection for piping.

Code of Federal Regulations, 2012 CFR

2012-07-01

... accordance with the following: (a) Automatic line leak detectors. Methods which alert the operator to the... pounds per square inch line pressure within 1 hour. An annual test of the operation of the leak detector...

40 CFR 280.44 - Methods of release detection for piping.

Code of Federal Regulations, 2011 CFR

2011-07-01

... accordance with the following: (a) Automatic line leak detectors. Methods which alert the operator to the... pounds per square inch line pressure within 1 hour. An annual test of the operation of the leak detector...

40 CFR 280.44 - Methods of release detection for piping.

Code of Federal Regulations, 2013 CFR

2013-07-01

... accordance with the following: (a) Automatic line leak detectors. Methods which alert the operator to the... pounds per square inch line pressure within 1 hour. An annual test of the operation of the leak detector...

40 CFR 280.44 - Methods of release detection for piping.

Code of Federal Regulations, 2014 CFR

2014-07-01

... accordance with the following: (a) Automatic line leak detectors. Methods which alert the operator to the... pounds per square inch line pressure within 1 hour. An annual test of the operation of the leak detector...

40 CFR 280.44 - Methods of release detection for piping.

Code of Federal Regulations, 2010 CFR

2010-07-01

... accordance with the following: (a) Automatic line leak detectors. Methods which alert the operator to the... pounds per square inch line pressure within 1 hour. An annual test of the operation of the leak detector...

Chemical Safety Alert: Anhydrous Ammonia Theft

EPA Pesticide Factsheets

This extremely hazardous substance is largely used as an agricultural fertilizer, but is also a key ingredient in the illegal production of methamphetamines. It is stored as a liquid under pressure, but becomes a toxic gas when released.

Measurement of fission product gases in the atmosphere

NASA Astrophysics Data System (ADS)

Schell, W. R.; Tobin, M. J.; Marsan, D. J.; Schell, C. W.; Vives-Batlle, J.; Yoon, S. R.

1997-01-01

The ability to quickly detect and assess the magnitude of releases of fission-produced radioactive material is of significant importance for ongoing operations of any conventional nuclear power plant or other activities with a potential for fission product release. In most instances, the control limits for the release of airborne radioactivity are low enough to preclude direct air sampling as a means of detection, especially for fission gases that decay by beta or electron emission. It is, therefore, customary to concentrate the major gaseous fission products (krypton, xenon and iodine) by cryogenic adsorption for subsequent separation and measurement. This study summarizes our initial efforts to develop an automated portable system for on-line separation and concentration with the potential for measuring environmental levels of radioactive gases, including 85Kr, 131,133,135Xe, 14C, 3H, 35S, 125,131I, etc., without using cryogenic fluids. Bench top and prototype models were constructed using the principle of heatless fractionation of the gases in a pressure swing system. This method removes the requirement for cryogenic fluids to concentrate gases and, with suitable electron and gamma ray detectors, provides for remote use under automatic computer control. Early results using 133Xe tracer show that kinetic chromatography, i.e., high pressure adsorption of xenon and low pressure desorption of air, using specific types of molecular sieves, permits the separation and quantification of xenon isotopes from large volume air samples. We are now developing the ability to measure the presence and amounts of fission-produced xenon isotopes that decay by internal conversion electrons and beta radiation with short half-lives, namely 131mXe, 11.8 d, 133mXe, 2.2 d, 133Xe, 5.2 d and 135Xe, 9.1 h. The ratio of the isotopic concentrations measured can be used to determine unequivocally the amount of fission gas and time of release of an air parcel many kilometers downwind from a nuclear activity where the fission products were discharged.

Thermal Evolution of Earht's Core during Accretion: a Preliminary Solid Inner Core at the End of Accrfetion.

NASA Astrophysics Data System (ADS)

Arkani-Hamed, J.

2015-12-01

Growth of an inner core has conventionally been related to core cooling blow the liquidus of iron. It is however possible that the core of the proto-Earth solidifies upon pressure increase during accretion. The lithostatic pressure in the proto-Earth increases immediately after merging each impactor, and the pressure-dependent liquidus of iron may supersede the temperature near the center resulting in a solid inner core. Assuming that Earth is formed by accreting a few dozen Moon to Mars size planetary embryos, the thermal evolution of the proto-Earth's core is investigated during accretion. The collision of an embryo heats the Earth differentially and the rotating low-viscosity, differentially heated core stratifies, creating a spherically symmetric stable and radially increasing temperature distribution. Convection occurs in the outer core while heat transfers by conduction in deeper parts. It is assumed that the iron core of an embryo pools at the bottom of partially molten mantle and thermally equilibrates with surroundings. It then descends as an iron diapir in the solid silicate mantle, while releasing its gravitational energy. Depending on its temperature when arrives at the core mantle boundary, it may spread on the core creating a hot layer or plunge into the core and descend to a neutrally buoyant level while further releasing its gravitational energy. A few dozen thermal evolution models of the core are investigates to examine effects of major parameters such as: total number of impacting embryos; partitioning of the gravitational energy released during the descent of the diaper in the mantle (between the silicate mantle and the iron diaper), and in the core (between the proto-Earth's core and that of the embryo); and gravitational energy and latent heat released due to the core solidification. All of the models predict a large solid inner core, about 1500 to 2000 km in radius, at the end of accretion.

Instantaneous stroke volume in man during lower body negative pressure /LBNP/

NASA Technical Reports Server (NTRS)

Loeppky, J. A.; Richards, K. L.; Greene, E. R.; Eldridge, M. W.; Hoekenga, D. E.; Venters, M. D.; Luft, U. C.

1982-01-01

Results of an examination of the instantaneous time course of the stroke volume (SV) and cardiac output (Q) in response to the onset and release of -50 torr lower body negative pressure (LBNP) are reported. Six male subjects were sealed into a LBNP box up to the iliac crest while being monitored by echocardiograph for centerlamina blood velocity, fluid displacement, stroke volume, heart rate, and leg volume. Particular use was made of pulsed ultrasonic Doppler velocity meters for measuring the blood velocities and flow dynamics. Measurements were made of the subjects continuously beginning from 20 sec prior to and one min after LBNP onset and release. A linear fall in the SV was observed with LBNP at 49% of the baseline value after 33 sec. A 62% drop, the lowest, was detected after 8 min of LBNP. The leg volume was inversely related to Q for the duration of the experiment.

Analysis of combustion spectra containing organ pipe tone by cepstral techniques

NASA Technical Reports Server (NTRS)

Miles, J. H.; Wasserbauer, C. A.

1982-01-01

Signal reinforcements and cancellations due to standing waves may distort constant bandwidth combustion spectra. Cepstral techniques previously applied to the ground reflection echo problem are used to obtain smooth broadband data and information on combustion noise propagation. Internal fluctuating pressure measurements made using a J47 combustor attached to a 6.44 m long duct are analyzed. Measurements made with Jet A and hydrogen fuels are compared. The acoustic power levels inferred from the measurements are presented for a range of low heat release rate operating conditions near atmospheric pressure. For these cases, the variation with operating condition of the overall acoustic broadband power level for both hydrogen and Jet A fuels is consistent with previous results showing it was proportional to the square of the heat release rate. However, the overall acoustic broadband power level generally is greater for hydrogen than for Jet A.

Compaction by impact of unconsolidated lunar fines

NASA Technical Reports Server (NTRS)

Ahrens, T. J.

1975-01-01

New Hugoniot and release adiabat data for 1.8 g/cu cm lunar fines in the approximately 2 to 70 kbar range demonstrate that upon shock compression intrinsic crystal density (approximately 3.1 g/cu cm) is achieved under shock stress of 15 to 20 kbar. Release adiabat determinations indicate that measurable irreversible compaction occurs upon achieving shock pressures above approximately 4 kbar. For shocks in the approximately 7 to 15 kbar range, the inferred post-shock specific volumes observed decrease nearly linearly with increasing peak shock pressures. Upon shocking to approximately 15 kbar the post-shock density is approximately that of the intrinsic minerals. If the present data are taken to be representative of the response to impact of unconsolidated regolith material on the moon, it is inferred that the formation of appreciable quantities of soil breccia can be associated with the impact of meteoroids or ejecta at speeds as low as approximately 1 km/sec.

SLM Produced Hermetically Sealed Isolation Valve

NASA Technical Reports Server (NTRS)

Richard, James

2014-01-01

Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic-driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic-based valve.

The evolution of an impact-generated atmosphere

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.

1982-01-01

The minimum impact velocities and pressures required to form a primary H2O atmosphere during planetary accretion from chondritelike planetessimals are determined by means of shock wave and thermodynamic data for rock-forming and volatile-bearing minerals. Attenuation of impact-induced shock pressure is modelled to the extent that the amount of released water can be estimated as a function of projectile radius, impact velocity, weight fraction of target water, target porosity, and dehydration efficiency. The two primary processes considered are the impact release of water bound in such hydrous minerals as serpentine, and the subsequent reincorporation of free water by hydration of forsterite and enstatite. These processes are described in terms of model calculations for the accretion of the earth. It is concluded that the concept of dehydration efficiency is of dominant importance in determining the degree to which an accreting planet acquires an atmosphere during its formation.

Magmas near the critical degassing pressure drive volcanic unrest towards a critical state.

PubMed

Chiodini, Giovanni; Paonita, Antonio; Aiuppa, Alessandro; Costa, Antonio; Caliro, Stefano; De Martino, Prospero; Acocella, Valerio; Vandemeulebrouck, Jean

2016-12-20

During the reawaking of a volcano, magmas migrating through the shallow crust have to pass through hydrothermal fluids and rocks. The resulting magma-hydrothermal interactions are still poorly understood, which impairs the ability to interpret volcano monitoring signals and perform hazard assessments. Here we use the results of physical and volatile saturation models to demonstrate that magmatic volatiles released by decompressing magmas at a critical degassing pressure (CDP) can drive volcanic unrest towards a critical state. We show that, at the CDP, the abrupt and voluminous release of H 2 O-rich magmatic gases can heat hydrothermal fluids and rocks, triggering an accelerating deformation that can ultimately culminate in rock failure and eruption. We propose that magma could be approaching the CDP at Campi Flegrei, a volcano in the metropolitan area of Naples, one of the most densely inhabited areas in the world, and where accelerating deformation and heating are currently being observed.

SLM Produced Hermetically Sealed Isolation Valve

NASA Technical Reports Server (NTRS)

Richard, James A.

2014-01-01

Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic based valve.

Astrocytic modulation of sleep homeostasis and cognitive consequences of sleep loss.

PubMed

Halassa, Michael M; Florian, Cedrick; Fellin, Tommaso; Munoz, James R; Lee, So-Young; Abel, Ted; Haydon, Philip G; Frank, Marcos G

2009-01-29

Astrocytes modulate neuronal activity by releasing chemical transmitters via a process termed gliotransmission. The role of this process in the control of behavior is unknown. Since one outcome of SNARE-dependent gliotransmission is the regulation of extracellular adenosine and because adenosine promotes sleep, we genetically inhibited the release of gliotransmitters and asked if astrocytes play an unsuspected role in sleep regulation. Inhibiting gliotransmission attenuated the accumulation of sleep pressure, assessed by measuring the slow wave activity of the EEG during NREM sleep, and prevented cognitive deficits associated with sleep loss. Since the sleep-suppressing effects of the A1 receptor antagonist CPT were prevented following inhibition of gliotransmission and because intracerebroventricular delivery of CPT to wild-type mice mimicked the transgenic phenotype, we conclude that astrocytes modulate the accumulation of sleep pressure and its cognitive consequences through a pathway involving A1 receptors.

Hubble and the Language of Images

NASA Astrophysics Data System (ADS)

Levay, Z. G.

2005-12-01

Images released from the Hubble Space Telescope have been very highly regarded by the astronomy-attentive public for at least a decade. Due in large part to these images, Hubble has become an iconic figure, even among the general public. This iconic status is both a boon and a burden for those who produce the stream of images fl owing from this telescope. While the benefits of attention are fairly obvious, the negative aspects are less visible. One of the most persistent challenges is the need to continue to deliver images that "top" those released before. In part this can be accomplished because of Hubble's upgraded instrumentation. But it can also be a source of pressure that could, if left unchecked, erode ethical boundaries in our communication with the public. These pressures are magnified in an atmosphere of uncertainty with regard to the future of the mission.

Thermonuclear plasma with autocatalytic thermomagnetic current amplification by nuclear reactions from fusion neutrons

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

Winterberg, F.

2006-03-15

It is proposed to use the neutrons released from a deuterium-tritium or deuterium-deuterium fusion reaction to drive thermomagnetic currents in a plasma corona surrounding the fusion plasma through the heating of the corona with nuclear reactions by the neutrons released in the fusion reaction. Because the neutron reaction cross sections are larger for slow neutrons, it is proposed to slow them down in a moderator separated from the hot plasma of the corona, giving the configuration a striking similarity to a heterogeneous nuclear fission reactor. While in a fission reactor the separation makes possible a growing neutron chain reaction, itmore » here makes possible the autocatalytic amplification of the thermomagnetic currents by an increase of the fusion reaction rate through a rise of the plasma pressure by the magnetic pressure of the thermomagnetic currents. This is expected to substantially increase the n{tau} product over its Lawson value.« less

Controlled release of cyclosporine A self-nanoemulsifying systems from osmotic pump tablets: near zero-order release and pharmacokinetics in dogs.

PubMed

Zhang, Xi; Yi, Yueneng; Qi, Jianping; Lu, Yi; Tian, Zhiqiang; Xie, Yunchang; Yuan, Hailong; Wu, Wei

2013-08-16

It is very important to enhance the absorption simultaneously while designing controlled release delivery systems for poorly water-soluble and poorly permeable drugs (BCS IV). In this study, controlled release of cyclosporine (CyA) was achieved by the osmotic release strategy taking advantage of the absorption-enhancing capacity of self-nanoemulsifying drug delivery systems (SNEDDSs). The liquid SNEDDS consisting of Labrafil M 1944CS, Transcutol P and Cremophor EL was absorbed by the osmotic tablet core excipients (sucrose, lactose monohydrate, polyethylene oxide, and partly pregelatinized starch) and then transformed into osmotic tablets. Near zero-order release could be achieved for CyA-loaded nanoemulsions reconstituted from the SNEDDS. In general, the influencing factor study indicated that the release rate increased with increase of inner osmotic pressure, ratio of osmotic agent to suspending agent, content of pore-forming agent, and size of release orifice, whereas the thickness of the membrane impeded the release of CyA nanoemulsion. Pharmacokinetic study showed steady blood CyA profiles with prolonged Tmax and MRT, and significantly reduced Cmax for self-nanoemulsifying osmotic pump tablet (SNEOPT) in comparison with highly fluctuating profiles of the core tablet and Sandimmune Neoral(®). However, similar oral bioavailability was observed for either controlled release or non-controlled release formulations. It was concluded that simultaneous controlling on CyA release and absorption-enhancing had been achieved by a combination of osmotic tablet and SNEDDS. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of temperature and high pressure on the activity and mode of action of fungal pectin methyl esterase.

PubMed

Duvetter, Thomas; Fraeye, Ilse; Sila, Daniel N; Verlent, Isabel; Smout, Chantal; Clynen, Elke; Schoofs, Liliane; Schols, Henk; Hendrickx, Marc; Van Loey, Ann

2006-01-01

Pectin was de-esterified with purified recombinant Aspergillus aculeatus pectin methyl esterase (PME) during isothermal-isobaric treatments. By measuring the release of methanol as a function of treatment time, the rate of enzymatic pectin conversion was determined. Elevated temperature and pressure were found to stimulate PME activity. The highest rate of PME-catalyzed pectin de-esterification was obtained when combining pressures in the range 200-300 MPa with temperatures in the range 50-55 degrees C. The mode of pectin de-esterification was investigated by characterizing the pectin reaction products by enzymatic fingerprinting. No significant effect of increasing pressure (300 MPa) and/or temperature (50 degrees C) on the mode of pectin conversion was detected.

Modeling study of the ABS relay valve

NASA Astrophysics Data System (ADS)

Lei, Ming; Lin, Min; Guo, Bin; Luo, Zai; Xu, Weidong

2011-05-01

The ABS (anti-lock braking system) relay valve is the key component of anti-lock braking system in most commercial vehicles such as trucks, tractor-trailers, etc. In this paper, structure of ABS relay valve and its work theory were analyzed. Then a mathematical model of ABS relay valve, which was investigated by dividing into electronic part, magnetic part, pneumatic part and mechanical part, was set up. The displacement of spools and the response of pressure increasing, holding, releasing of ABS relay valve were simulated and analyzed under conditions of control pressure 500 KPa, braking pressure 600 KPa, atmospheric pressure 100 KPa and air temperature 310 K. Thisarticle provides reliable theory for improving the performance and efficiency of anti-lock braking system of vehicles.

Improvement in clinical outcomes after dry needling versus myofascial release on pain pressure thresholds, quality of life, fatigue, pain intensity, quality of sleep, anxiety, and depression in patients with fibromyalgia syndrome.

PubMed

Castro Sánchez, Adelaida M; García López, Hector; Fernández Sánchez, Manuel; Pérez Mármol, José Manuel; Aguilar-Ferrándiz, María Encarnación; Luque Suárez, Alejandro; Matarán Peñarrocha, Guillermo Adolfo

2018-04-23

To compare the effectiveness of dry needling versus myofascial release on myofascial trigger points pain in cervical muscles, quality of life, impact of symptoms pain, quality of sleep, anxiety, depression, and fatigue in patients with fibromyalgia syndrome. A single-blind randomized controlled trial was conducted. Sixty-four subjects with fibromyalgia were randomly assigned to a dry needling group or a myofascial release group. Pain pressure thresholds of myofascial trigger points were evaluated in the cervical muscles. In addition, quality of life, impact of fibromyalgia symptoms, quality of sleep, intensity of pain, anxiety and depression symptoms, impact of fatigue at baseline and post treatment after four weeks of intervention were evaluated. Significant improvement was found in most pain pressure thresholds of the myofascial trigger points in cervical muscles in the dry needling group compared to myofascial release (p < 0.05). Similarly, these differences between groups were found for the components of quality of life of physical function (F = 12.74, p = 0.001), physical role (F = 11.24, p = 0.001), body pain (F =30.26, p < 0.001), general health (F = 15.83, p < 0.001), vitality (F = 13.51, p = 0.001), social function (F = 4.73, p = 0.034), emotional role (F = 8.01, p = 0.006), and mental health (F = 4.95, p = 0.030). Similar results were achieved for total impact of FMS symptoms (F = 42.91, p < 0.001), quality of sleep (F = 11.96, p = 0.001), state anxiety (F = 7.40, p = 0.009), and trait anxiety (F = -14.63, p < 0.001), hospital anxiety and depression (F = 20.60, p < 0.001), general pain intensity (F = 29.59, p < 0.001), and fatigue (F = -25.73, p < 0.001). The dry needling therapy showed higher improvements in comparison with myofascial release therapy for pain pressure thresholds, the components of quality of life of physical role, body pain, vitality and social function, as well as the total impact of FMS symptoms, quality of sleep, state and trait anxiety, hospital anxiety-depression, general pain intensity and fatigue. Implications for rehabilitation Dry needling therapy reduces myofascial trigger point pain in the short term in patients with fibromyalgia syndrome. This therapeutic approach improves anxiety, depression, fatigue symptoms, quality of life, and sleep after treatment. Dry needling and myofascial release therapies decrease intensity of pain, and the impact of fibromyalgia symptoms in this population. These intervention approaches should be considered in an independent manner as complementary therapies within a multidisciplinary setting.

The Behavior of IAPWS-95 from 250 to 300 K and Pressures up to 400 MPa: Evaluation Based on Recently Derived Property Data

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

Wagner, Wolfgang, E-mail: Wagner@thermo.rub.de; Thol, Monika

2015-12-15

Over the past several years, considerable scientific and technical interest has been focused on accurate thermodynamic properties of fluid water covering part of the subcooled (metastable) region and the stable liquid from the melting line up to about 300 K and pressures up to several hundred MPa. Between 2000 and 2010, experimental density data were published whose accuracy was not completely clear. The scientific standard equation of state for fluid water, the IAPWS-95 formulation, was developed on the basis of experimental data for thermodynamic properties that were available by 1995. In this work, it is examined how IAPWS-95 behaves withmore » respect to the experimental data published after 1995. This investigation is carried out for temperatures from 250 to 300 K and pressures up to 400 MPa. The starting point is the assessment of the current data situation. This was mainly performed on the basis of data for the density, expansivity, compressibility, and isobaric heat capacity, which were derived in 2015 from very accurate speed-of-sound data. Apart from experimental data and these derived data, property values calculated from the recently published equation of state for this region of Holten et al. (2014) were also used. As a result, the unclear data situation could be clarified, and uncertainty values could be estimated for the investigated properties. In the region described above, detailed comparisons show that IAPWS-95 is able to represent the latest experimental data for the density, expansivity, compressibility, speed of sound, and isobaric heat capacity to within the uncertainties given in the release on IAPWS-95. Since the release does not contain uncertainty estimates for expansivities and compressibilities, the statement relates to the error propagation of the given uncertainty in density. Due to the lack of experimental data for the isobaric heat capacity for pressures above 100 MPa, no uncertainty estimates are given in the release for this pressure range. Results of the investigation of IAPWS-95 concerning its behavior with regard to the isobaric heat capacity in the high-pressure low-temperature region are also presented. Comparisons with very accurate speed-of-sound data published in 2012 showed that the uncertainty estimates of IAPWS-95 in speed of sound could be decreased for temperatures from 283 to 473 K and pressures up to 400 MPa.« less

Negative Pressure Wound Therapy Reduces the Effectiveness of Traditional Local Antibiotic Depot in a Large Complex Musculoskeletal Wound Animal Model

DTIC Science & Technology

2012-09-01

in particular, local antibiotic delivery via polymethylmethacrylate (PMMA) bone cement and negative pressure wound therapy (NPWT). In cases with gross...release of gentamicin from polymethylmethacrylate beads. An experimental and pharmacoki- netic study. J Bone Joint Surg Br. 1978;60-B:270 275. 7...diffusion from antibiotic-impregnated polymethylmethacrylate beads. Clin Orthop Relat Res. 1992;278:244 252. Stinner et al J Orthop Trauma Volume

The Role of Neural Reflexes in Control of the Cardiovascular System during Stress.

DTIC Science & Technology

1984-02-01

cold block increase arterial pressure but did not alter plasma renin activity or renin secretory rate in dogs with normal or high sodium diet...also found that these afferents may play a keen role in the regulation of renin scretoary rate during conditions which may alter cardiopulmonary blood ...important hormone in -. the regulation of arterial pressure . However, the role of the nervous system in controlling the release of vasopressin has not been

Design of a Simple Blast Pressure Gauge Based on a Heterodyne Velocimetry Measuring Technique

DTIC Science & Technology

2016-08-01

deployed in an experiment during which the blast pressure was measured from detonation of 114 g of Primasheet 1000 high explosive. The gauge reported... detonation of high explosive where accelerated projectiles and debris may occur. Many times, overpressures generated by such events can be a nuisance to...as that generated by release of energy from a high-explosive detonation or deflagration, materials such as metals or ceramics may be needed. A

High pressure treatment changes spoilage characteristics and shelf life of Pacific oysters ( Crassostrea gigas) during refrigerated storage

NASA Astrophysics Data System (ADS)

Cao, Rong; Zhao, Ling; Liu, Qi

2017-04-01

The effects of high pressure (HP) treatment on spoilage characteristic and shelf life extension of Pacific oysters ( Crassostrea gigas) during refrigerated storage were studied. Results showed that HP treatment of 275 MPa for 3 min or 300 MPa for 2 min could achieve 100% full release of oyster adductor muscle, pressures higher than 350 MPa caused excessive release as the shells of oysters were broken, thus use of higher pressures should be cautious in oyster processing industry because of its adverse impact on the appearance of shells. HP treatment (300 MPa, 2 min) was proper for the shucking of Pacific oyster ( Crassostrea gigas) in China. This treatment caused no organoleptic disadvantage. Moreover, HP treatment resulted in obvious differences in biochemical spoilage indicators (pH, TVB-N and TBARS) changes and volatile compounds profile determined by electronic nose during storage. HP treatment (300 MPa, 2 min) also led to a reduction of aerobic bacterial count (APC) by 1.27 log cycles. Furthermore, the APC values of oysters treated by HP were always lower than those of the control samples during storage. Based on the organoleptic, biochemical and microbiological indicators, shelf life of 6-8 d for control and 12 d for HP-treated oysters could be expected. HP treatment showed great potential in oyster processing and preservation.

Dynamics of the Antarctic Circumpolar Current as seen by GRACE (Invited)

NASA Astrophysics Data System (ADS)

Thomas, M.; Dobslaw, H.; Bergmann, I.

2010-12-01

The Antarctic Circumpolar Current, being the strongest and longest ocean current on Earth, connects the three great ocean basins and contributes substantially to the global re-distribution of water masses, with a significant impact on global climate. Observational coverage from in-situ measurements is sparse due to the harsh environmental conditions, and satellite altimetry does not capture the full extent of the current due to seasonal sea-ice coverage. Ocean bottom pressure variations as sensed with the satellite gravity mission GRACE provide a promising way to broaden our observational basis. Besides monthly mean gravity fields that provide ocean bottom pressure variations averaged over 30 days, several alternative GRACE products with higher temporal resolution have been developed during the most recent years. These include 10-day solutions from GRGS Toulouse, weekly solutions from the GFZ Potsdam as well as constrained daily solutions from the University of Bonn which have been obtained by means of a Kalman filtering approach. In this presentation, ocean bottom pressure derived from these alternative GRACE releases will be contrasted against both in-situ observations and output from a numerical ocean model, highlighting the additional information contained in these GRACE solutions with respect to the standard monthly fields. By means of statistical analyses of ocean bottom pressure variations and barotropic transports it will be demonstrated how these new GRACE releases are contributing to our understanding of this highly dynamic great ocean conveyor.

Preliminary calculations related to the accident at Three Mile Island

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

Kirchner, W.L.; Stevenson, M.G.

This report discusses preliminary studies of the Three Mile Island Unit 2 (TMI-2) accident based on available methods and data. The work reported includes: (1) a TRAC base case calculation out to 3 hours into the accident sequence; (2) TRAC parametric calculations, these are the same as the base case except for a single hypothetical change in the system conditions, such as assuming the high pressure injection (HPI) system operated as designed rather than as in the accident; (3) fuel rod cladding failure, cladding oxidation due to zirconium metal-steam reactions, hydrogen release due to cladding oxidation, cladding ballooning, cladding embrittlement,more » and subsequent cladding breakup estimates based on TRAC calculated cladding temperatures and system pressures. Some conclusions of this work are: the TRAC base case accident calculation agrees very well with known system conditions to nearly 3 hours into the accident; the parametric calculations indicate that, loss-of-core cooling was most influenced by the throttling of High-Pressure Injection (HPI) flows, given the accident initiating events and the pressurizer electromagnetic-operated valve (EMOV) failing to close as designed; failure of nearly all the rods and gaseous fission product gas release from the failed rods is predicted to have occurred at about 2 hours and 30 minutes; cladding oxidation (zirconium-steam reaction) up to 3 hours resulted in the production of approximately 40 kilograms of hydrogen.« less

[Changes of right atrial myoendocrine cells during hypertension and after arterial pressure decrease].

PubMed

Maksimov, V F; Korostyshevskaia, I M; Kurganov, S A; Markel', A L; Rudenko, N S; Iakobson, G S

2014-01-01

It is well known now that atrial cardiomyocytes carry out both contractile and endocrine activities--they synthesize, accumulate in specific secretory granules and release the natriuretic peptides. The main physiological effects of natriuretic peptides are antagonistic to the renin-angiotensin-aldostrol system, but their role in the development of hypertension is still disputable. The aim of this investigation is to estimate using electron microscopy the secretory activities of atrial myoendocrine cells in rats with inherited stress-induced arterial hypertension (ISIAH stain). It has been shown that myoendocrine cells in the ISIAH rats with arterial pressure about 180 mm Hg reveal morphological features of increased synthesis, extra accumulation and release of natriuretic peptides compared with normotensive control rats. In the ISIAH rats treated with losartan (angiotensin II receptor blocker) and therefore having a sustained decrease in arterial pressure to 140 mm Hg, changes in granular pool composition, reduction of the number and diameter of the secretory granules, reduction of Golgi complexes, and increased intracellular degradation of secretory stores were found in the myoendocrine cells. At the same time the marked capillary hyperemia and interstitial edema in the myocardium were observed. Thus, in rats with severe inherited hypertension, the secretory activity of heart myoendocrine cells is sharply increased and directly depends on the arterial blood pressure level. This proves that natriuretic peptides actively participate in the regulation of hemodynamics during with cardiovascular pathology.

Magnesium sulphate attenuates arterial pressure increase during laparoscopic cholecystectomy.

PubMed

Jee, D; Lee, D; Yun, S; Lee, C

2009-10-01

Magnesium is well known to inhibit catecholamine release and attenuate vasopressin-stimulated vasoconstriction. We investigated whether i.v. magnesium sulphate attenuates the haemodynamic stress responses to pneumoperitoneum by changing neurohumoral responses during laparoscopic cholecystectomy. Thirty-two patients undergoing laparoscopic cholecystectomy were randomly assigned to two groups; a control group was given saline, and a magnesium group received magnesium sulphate 50 mg kg(-1) immediately before pneumoperitoneum. Arterial pressure, heart rate, serum magnesium, plasma renin activity (PRA), and catecholamine, cortisol, and vasopressin levels were measured. Systolic and diastolic arterial pressures were greater in the control group (P<0.05) than in the magnesium group at 10, 20, and 30 min post-pneumoperitoneum. Norepinephrine or epinephrine levels [pg ml(-1), mean (SD)] were higher in the control group than in the magnesium group at 5 [211 (37) vs 138 (18)] or 10 min [59 (19) vs 39 (9)] post-pneumoperitoneum, respectively (P<0.05). In the control group, vasopressin levels [pg ml(-1), mean (SD)] were higher compared with the magnesium group at 5 [64 (18) vs 35 (9), P<0.01] and 10 min [65 (18) vs 47 (11), P<0.05] post-pneumoperitoneum. There were no significant differences between the groups in PRA and cortisol levels. I.V. magnesium sulphate before pneumoperitoneum attenuates arterial pressure increases during laparoscopic cholecystectomy. This attenuation is apparently related to reductions in the release of catecholamine, vasopressin, or both.

Respiratory dynamics of discontinuous gas exchange in the tracheal system of the desert locust, Schistocerca gregaria.

PubMed

Groenewald, Berlizé; Hetz, Stefan K; Chown, Steven L; Terblanche, John S

2012-07-01

Gas exchange dynamics in insects is of fundamental importance to understanding evolved variation in breathing patterns, such as discontinuous gas exchange cycles (DGCs). Most insects do not rely solely on diffusion for the exchange of respiratory gases but may also make use of respiratory movements (active ventilation) to supplement gas exchange at rest. However, their temporal dynamics have not been widely investigated. Here, intratracheal pressure, V(CO2) and body movements of the desert locust Schistocerca gregaria were measured simultaneously during the DGC and revealed several important aspects of gas exchange dynamics. First, S. gregaria employs two different ventilatory strategies, one involving dorso-ventral contractions and the other longitudinal telescoping movements. Second, although a true spiracular closed (C)-phase of the DGC could be identified by means of subatmospheric intratracheal pressure recordings, some CO(2) continued to be released. Third, strong pumping actions do not necessarily lead to CO(2) release and could be used to ensure mixing of gases in the closed tracheal system, or enhance water vapour reabsorption into the haemolymph from fluid-filled tracheole tips by increasing the hydrostatic pressure or forcing fluid into the haemocoel. Finally, this work showed that the C-phase of the DGC can occur at any pressure. These results provide further insights into the mechanistic basis of insect gas exchange.

Keratinocytes at the uppermost layer of epidermis might act as sensors of atmospheric pressure change.

PubMed

Denda, Mitsuhiro

2016-01-01

It has long been suggested that climate, especially atmospheric pressure change, can cause health problems ranging from migraine to myocardial infarction. Here, I hypothesize that the sensory system of epidermal keratinocytes mediates the influence of atmospheric pressure change on the human physiological condition. We previously demonstrated that even subtle changes of atmospheric pressure (5-20 hPa) induce elevation of intracellular calcium level in cultured human keratinocytes (excitation of keratinocytes). It is also established that communication occurs between epidermal keratinocytes and peripheral nerve systems. Moreover, various neurotransmitters and hormones that influence multiple systems (nervous, cardiovascular, endocrine, and immune systems) are generated and released from epidermal keratinocytes in response to various external stimuli. Thus, I suggest that pathophysiological phenomena induced by atmospheric pressure changes might be triggered by epidermal keratinocytes.

Development and characterization of hollow microprobe array as a potential tool for versatile and massively parallel manipulation of single cells.

PubMed

Nagai, Moeto; Oohara, Kiyotaka; Kato, Keita; Kawashima, Takahiro; Shibata, Takayuki

2015-04-01

Parallel manipulation of single cells is important for reconstructing in vivo cellular microenvironments and studying cell functions. To manipulate single cells and reconstruct their environments, development of a versatile manipulation tool is necessary. In this study, we developed an array of hollow probes using microelectromechanical systems fabrication technology and demonstrated the manipulation of single cells. We conducted a cell aspiration experiment with a glass pipette and modeled a cell using a standard linear solid model, which provided information for designing hollow stepped probes for minimally invasive single-cell manipulation. We etched a silicon wafer on both sides and formed through holes with stepped structures. The inner diameters of the holes were reduced by SiO2 deposition of plasma-enhanced chemical vapor deposition to trap cells on the tips. This fabrication process makes it possible to control the wall thickness, inner diameter, and outer diameter of the probes. With the fabricated probes, single cells were manipulated and placed in microwells at a single-cell level in a parallel manner. We studied the capture, release, and survival rates of cells at different suction and release pressures and found that the cell trapping rate was directly proportional to the suction pressure, whereas the release rate and viability decreased with increasing the suction pressure. The proposed manipulation system makes it possible to place cells in a well array and observe the adherence, spreading, culture, and death of the cells. This system has potential as a tool for massively parallel manipulation and for three-dimensional hetero cellular assays.

Osmotically driven drug delivery through remote-controlled magnetic nanocomposite membranes.

PubMed

Zaher, A; Li, S; Wolf, K T; Pirmoradi, F N; Yassine, O; Lin, L; Khashab, N M; Kosel, J

2015-09-01

Implantable drug delivery systems can provide long-term reliability, controllability, and biocompatibility, and have been used in many applications, including cancer pain and non-malignant pain treatment. However, many of the available systems are limited to zero-order, inconsistent, or single burst event drug release. To address these limitations, we demonstrate prototypes of a remotely operated drug delivery device that offers controllability of drug release profiles, using osmotic pumping as a pressure source and magnetically triggered membranes as switchable on-demand valves. The membranes are made of either ethyl cellulose, or the proposed stronger cellulose acetate polymer, mixed with thermosensitive poly(N-isopropylacrylamide) hydrogel and superparamagnetic iron oxide particles. The prototype devices' drug diffusion rates are on the order of 0.5-2 μg/h for higher release rate designs, and 12-40 ng/h for lower release rates, with maximum release ratios of 4.2 and 3.2, respectively. The devices exhibit increased drug delivery rates with higher osmotic pumping rates or with magnetically increased membrane porosity. Furthermore, by vapor deposition of a cyanoacrylate layer, a drastic reduction of the drug delivery rate from micrograms down to tens of nanograms per hour is achieved. By utilizing magnetic membranes as the valve-control mechanism, triggered remotely by means of induction heating, the demonstrated drug delivery devices benefit from having the power source external to the system, eliminating the need for a battery. These designs multiply the potential approaches towards increasing the on-demand controllability and customizability of drug delivery profiles in the expanding field of implantable drug delivery systems, with the future possibility of remotely controlling the pressure source.

Osmotically driven drug delivery through remote-controlled magnetic nanocomposite membranes

PubMed Central

Zaher, A.; Li, S.; Wolf, K. T.; Pirmoradi, F. N.; Yassine, O.; Lin, L.; Khashab, N. M.; Kosel, J.

2015-01-01

Implantable drug delivery systems can provide long-term reliability, controllability, and biocompatibility, and have been used in many applications, including cancer pain and non-malignant pain treatment. However, many of the available systems are limited to zero-order, inconsistent, or single burst event drug release. To address these limitations, we demonstrate prototypes of a remotely operated drug delivery device that offers controllability of drug release profiles, using osmotic pumping as a pressure source and magnetically triggered membranes as switchable on-demand valves. The membranes are made of either ethyl cellulose, or the proposed stronger cellulose acetate polymer, mixed with thermosensitive poly(N-isopropylacrylamide) hydrogel and superparamagnetic iron oxide particles. The prototype devices' drug diffusion rates are on the order of 0.5–2 μg/h for higher release rate designs, and 12–40 ng/h for lower release rates, with maximum release ratios of 4.2 and 3.2, respectively. The devices exhibit increased drug delivery rates with higher osmotic pumping rates or with magnetically increased membrane porosity. Furthermore, by vapor deposition of a cyanoacrylate layer, a drastic reduction of the drug delivery rate from micrograms down to tens of nanograms per hour is achieved. By utilizing magnetic membranes as the valve-control mechanism, triggered remotely by means of induction heating, the demonstrated drug delivery devices benefit from having the power source external to the system, eliminating the need for a battery. These designs multiply the potential approaches towards increasing the on-demand controllability and customizability of drug delivery profiles in the expanding field of implantable drug delivery systems, with the future possibility of remotely controlling the pressure source. PMID:26487899

In situ study of maize starch gelatinization under ultra-high hydrostatic pressure using X-ray diffraction.

PubMed

Yang, Zhi; Gu, Qinfen; Hemar, Yacine

2013-08-14

The gelatinization of waxy (very low amylose) and high-amylose maize starches by ultra-high hydrostatic pressure (up to 6 GPa) was investigated in situ using synchrotron X-ray powder diffraction on samples held in a diamond anvil cell (DAC). The starch pastes, made by mixing starch and water in a 1:1 ratio, were pressurized and measured at room temperature. X-ray diffraction pattern showed that at 2.7 GPa waxy starch, which displayed A-type XRD pattern at atmospheric pressure, exhibited a faint B-type-like pattern. The B-type crystalline structures of high-amylose starch were not affected even when 1.5 GPa pressure was applied. However, both waxy and high-amylose maize starches can be fully gelatinized at 5.9 GPa and 5.1 GPa, respectively. In the case of waxy maize starch, upon release of pressure (to atmospheric pressure) crystalline structure appeared as a result of amylopectin aggregation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Materials discovery at high pressures

NASA Astrophysics Data System (ADS)

Zhang, Lijun; Wang, Yanchao; Lv, Jian; Ma, Yanming

2017-02-01

Pressure is a fundamental thermodynamic variable that can be used to control the properties of materials, because it reduces interatomic distances and profoundly modifies electronic orbitals and bonding patterns. It is thus a versatile tool for the creation of exotic materials not accessible at ambient conditions. Recently developed static and dynamic high-pressure experimental techniques have led to the synthesis of many functional materials with excellent performance: for example, superconductors, superhard materials and high-energy-density materials. Some of these advances have been aided and accelerated by first-principles crystal-structure searching simulations. In this Review, we discuss recent progress in high-pressure materials discovery, placing particular emphasis on the record high-temperature superconductivity in hydrogen sulfide and on nanotwinned cubic boron nitride and diamond, the hardest known materials. Energy materials and exotic chemical materials obtained under high pressures are also discussed. The main drawback of high-pressure materials is their destabilization after pressure release; this problem and its possible solutions are surveyed in the conclusions, which also provide an outlook on the future developments in the field.

Thermal and Evolved Gas Analysis of "Nanophase" Carbonates: Implications for Thermal and Evolved Gas Analysis on Mars Missions

NASA Technical Reports Server (NTRS)

Lauer, Howard V., Jr.; Archer, P. D., Jr.; Sutter, B.; Niles, P. B.; Ming, Douglas W.

2012-01-01

Data collected by the Mars Phoenix Lander's Thermal and Evolved Gas Analyzer (TEGA) suggested the presence of calcium-rich carbonates as indicated by a high temperature CO2 release while a low temperature (approx.400-680 C) CO2 release suggested possible Mg- and/or Fe-carbonates [1,2]. Interpretations of the data collected by Mars remote instruments is done by comparing the mission data to a database on the thermal properties of well-characterized Martian analog materials collected under reduced and Earth ambient pressures [3,4]. We are proposing that "nano-phase" carbonates may also be contributing to the low temperature CO2 release. The objectives of this paper is to (1) characterize the thermal and evolved gas proper-ties of carbonates of varying particle size, (2) evaluate the CO2 releases from CO2 treated CaO samples and (3) examine the secondary CO2 release from reheated calcite of varying particle size.

Release of radiogenic noble gases as a new signal of rock deformation

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

Bauer, Stephen J.; Gardner, W. Payton; Lee, Hyunwoo

In this paper we investigate the release of radiogenic noble gas isotopes during mechanical deformation. We developed an analytical system for dynamic mass spectrometry of noble gas composition and helium release rate of gas produced during mechanical deformation of rocks. Our results indicate that rocks release accumulated radiogenic helium and argon from mineral grains as they undergo deformation. We found that the release of accumulated 4He and 40Ar from rocks follows a reproducible pattern and can provide insight into the deformation process. Increased gas release can be observed before dilation, and macroscopic failure is observed during high-pressure triaxial rock deformationmore » experiments. Accumulated radiogenic noble gases can be released due to fracturing of mineral grains during small-scale strain in Earth materials. Helium and argon are highly mobile, conservative species and could be used to provide information on changes in the state of stress and strain in Earth materials, and as an early warning signal of macroscopic failure. These results pave the way for the use of noble gases to trace and monitor rock deformation for earthquake prediction and a variety of other subsurface engineering projects.« less

Release of radiogenic noble gases as a new signal of rock deformation

DOE PAGES

Bauer, Stephen J.; Gardner, W. Payton; Lee, Hyunwoo

2016-10-09

In this paper we investigate the release of radiogenic noble gas isotopes during mechanical deformation. We developed an analytical system for dynamic mass spectrometry of noble gas composition and helium release rate of gas produced during mechanical deformation of rocks. Our results indicate that rocks release accumulated radiogenic helium and argon from mineral grains as they undergo deformation. We found that the release of accumulated 4He and 40Ar from rocks follows a reproducible pattern and can provide insight into the deformation process. Increased gas release can be observed before dilation, and macroscopic failure is observed during high-pressure triaxial rock deformationmore » experiments. Accumulated radiogenic noble gases can be released due to fracturing of mineral grains during small-scale strain in Earth materials. Helium and argon are highly mobile, conservative species and could be used to provide information on changes in the state of stress and strain in Earth materials, and as an early warning signal of macroscopic failure. These results pave the way for the use of noble gases to trace and monitor rock deformation for earthquake prediction and a variety of other subsurface engineering projects.« less

Angiotensin II or epinephrine hemodynamic and metabolic responses in the liver of L-NAME induced hypertension and spontaneous hypertensive rats

PubMed Central

Kimura, Debora Conte; Nagaoka, Marcia Regina; Borges, Durval Rosa; Kouyoumdjian, Maria

2017-01-01

AIM To study hepatic vasoconstriction and glucose release induced by angiotensin (Ang)II or Epi in rats with pharmacological hypertension and spontaneously hypertensive rat (SHR). METHODS Isolated liver perfusion was performed following portal vein and vena cava cannulation; AngII or epinephrine (Epi) was injected in bolus and portal pressure monitored; glucose release was measured in perfusate aliquots. RESULTS The portal hypertensive response (PHR) and the glucose release induced by AngII of L-NAME were similar to normal rats (WIS). On the other hand, the PHR induced by Epi in L-NAME was higher whereas the glucose release was lower compared to WIS. Despite the similar glycogen content, glucose release induced by AngII was lower in SHR compared to Wistar-Kyoto rats although both PHR and glucose release induced by Epi in were similar. CONCLUSION AngII and Epi responses are altered in different ways in these hypertension models. Our results suggest that inhibition of NO production seems to be involved in the hepatic effects induced by Epi but not by AngII; the diminished glucose release induced by AngII in SHR is not related to glycogen content. PMID:28660012

Inconsistencies among secondary sources of Chukar Partridge (Alectoris chukar) introductions to the United States.

PubMed

Moulton, Michael P; Cropper, Wendell P; Broz, Andrew J

2015-01-01

The propagule pressure hypothesis asserts that the number of individuals released is the key determinant of whether an introduction will succeed or not. It remains to be shown whether propagule pressure is more important than either species-level or site-level factors in determining the fate of an introduction. Studies claiming to show that propagule pressure is the primary determinant of introduction success must assume that the historical record as reported by secondary sources is complete and accurate. Here, examine a widely introduced game bird, the Chukar (Alectoris chukar), to the USA. We compare the records reported by two secondary sources (Long, 1981; Lever, 1987) to those in a primary source (Christensen, 1970) and to a recent study by Sol et al. (2012). Numerous inconsistencies exist in the records reported by Sol et al. (2012), Long (1981) and Lever (1987) when compared to the primary record of Christensen (1970). As reported by Christensen (1970), very large numbers of Chukars were released unsuccessfully in some states. Our results strongly imply that factors other than sheer numbers are more important. Site-to-site differences are the most likely explanation for the variation in success.

Arterial baroreflex control of sympathetic nerve activity during acute hypotension: effect of fitness

NASA Technical Reports Server (NTRS)

Fadel, P. J.; Stromstad, M.; Hansen, J.; Sander, M.; Horn, K.; Ogoh, S.; Smith, M. L.; Secher, N. H.; Raven, P. B.

2001-01-01

We examined arterial baroreflex control of muscle sympathetic nerve activity (MSNA) during abrupt decreases in mean arterial pressure (MAP) and evaluated whether endurance training alters baroreflex function. Acute hypotension was induced nonpharmacologically in 14 healthy subjects, of which 7 were of high fitness (HF) and 7 were of average fitness (AF), by releasing a unilateral arterial thigh cuff after 9 min of resting ischemia under two conditions: control, which used aortic and carotid baroreflex (ABR and CBR, respectively) deactivation; and suction, which used ABR deactivation alone. The application of neck suction to counteract changes in carotid sinus transmural pressure during cuff release significantly attenuated the MSNA response (which increased 134 +/- 32 U/14 s) compared with control (which increased 195 +/- 43 U/14 s) and caused a greater decrease in MAP (19 +/- 2 vs. 15 +/- 2 mmHg; P < 0.05). Furthermore, during both trials, the HF subjects exhibited a greater decrease in MAP compared with AF subjects despite an augmented baroreflex control of MSNA. These data indicate that the CBR contributes importantly to the MSNA response during acute systemic hypotension. Additionally, we suggest that an impaired control of vascular reactivity hinders blood pressure regulation in HF subjects.

Apparatus for restraining and transporting dies

DOEpatents

Allison, James W.; LaBarre, Timothy L.

1994-01-01

Apparatus for restraining and transporting dies in punch press operations is provided. A floatation platen for supporting a die on the platen's upper surface has a plurality of recessed gas exhaust ports on the platen's lower surface. A source of pressurized gas delivers gas to a platen manifold, for delivery to orifices located in the gas exhaust ports. The flow of gas is controlled by a first valve adjacent the gas source and a second valve adjacent the manifold, with the second valve being used to control the gas flow during movement of the die. In this fashion, a die may be moved on a cushion of air from one workstation to a selected second workstation. A moveable hydraulically operated restraining fixture is also provided, for clamping the die in position during the compacting phase, and for releasing the die after completion of the compacting phase by releasing the hydraulic pressure on the restraining fixture. When pressure in the hydraulic cylinders on the restraining fixture is reversed, the restraining fixture will retract so that there is no contact between the die and the restraining fixture, thereby allowing the die to be removed from a first workstation and moved to a second selected workstation.

Arterial baroreflex control of sympathetic nerve activity during acute hypotension: effect of fitness.

PubMed

Fadel, P J; Stromstad, M; Hansen, J; Sander, M; Horn, K; Ogoh, S; Smith, M L; Secher, N H; Raven, P B

2001-06-01

We examined arterial baroreflex control of muscle sympathetic nerve activity (MSNA) during abrupt decreases in mean arterial pressure (MAP) and evaluated whether endurance training alters baroreflex function. Acute hypotension was induced nonpharmacologically in 14 healthy subjects, of which 7 were of high fitness (HF) and 7 were of average fitness (AF), by releasing a unilateral arterial thigh cuff after 9 min of resting ischemia under two conditions: control, which used aortic and carotid baroreflex (ABR and CBR, respectively) deactivation; and suction, which used ABR deactivation alone. The application of neck suction to counteract changes in carotid sinus transmural pressure during cuff release significantly attenuated the MSNA response (which increased 134 +/- 32 U/14 s) compared with control (which increased 195 +/- 43 U/14 s) and caused a greater decrease in MAP (19 +/- 2 vs. 15 +/- 2 mmHg; P < 0.05). Furthermore, during both trials, the HF subjects exhibited a greater decrease in MAP compared with AF subjects despite an augmented baroreflex control of MSNA. These data indicate that the CBR contributes importantly to the MSNA response during acute systemic hypotension. Additionally, we suggest that an impaired control of vascular reactivity hinders blood pressure regulation in HF subjects.

A long-lasting oral preformulation of the angiotensin II AT1 receptor antagonist losartan.

PubMed

De Paula, Washington X; Denadai, Ângelo M L; Braga, Aline N G; Shastri, V Prasad; Pinheiro, Sérgio V B; Frezard, Frederic; Santos, Robson A S; Sinisterra, Ruben D

2018-05-10

Losartan (Los), a non-peptidic orally active agent, reduces arterial pressure through specific and selective blockade of angiotensin II receptor AT1. However, this widely used AT1 antagonist presents low bioavailability and needs once or twice a day dosage. In order to improve its bioavailability, we used the host: guest strategy based on β-cyclodextrin (βCD). The results suggest that Los included in βCD showed a typical pulsatile release pattern after oral administration to rats, with increasing the levels of plasma of Los. In addition, the inclusion compound presented oral efficacy for 72 h, in contrast to Los alone, which shows antagonist effect for only 6 h. In transgenic (mREN2)L27 rats, the Los/βCD complex reduced blood pressure for about 6 d, whereas Los alone reduced blood pressure for only 2 d. More importantly, using this host: guest strategy, sustained release of Los for over a week via the oral route can be achieved without the need for encapsulation in a polymeric carrier. The proposed preformulation increased the efficacy reducing the dose or spacing between each dose intake.

Remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems.

PubMed

Pan, Tingrui; Baldi, Antonio; Ziaie, Babak

2007-06-01

In this paper, we present two remotely adjustable check-valves with an electrochemical release mechanism for implantable biomedical microsystems. These valves allow one to vary the opening pressure set-point and flow resistance over a period of time. The first design consists of a micromachined check-valve array using a SU-8 polymer structural layer deposited on the top of a gold sacrificial layer. The second design is based on a variable length cantilever beam structure with a gold sacrificial layer. The adjustable cantilever-beam structure is fabricated by gold thermo-compression bond of a thin silicon wafer over a glass substrate. In both designs, the evaporated gold can be electrochemically dissolved using a constant DC current via a telemetry link. In the first design the dissolution simply opens up individual outlets, while in the second design, gold anchors are sequentially dissolved hence increasing the effective length of the cantilever beam (reducing the opening pressure). A current density of 35 mA/cm(2) is used to dissolve the gold sacrificial layers. Both gravity and syringe-pump driven flow are used to characterize the valve performance. A multi-stage fluidic performance (e.g. flow resistance and opening pressure) is clearly demonstrated.

Low-pressure clathrate-hydrate formation in amorphous astrophysical ice analogs

NASA Technical Reports Server (NTRS)

Blake, D. F.; Allamandola, L. J.; Sandford, S.; Hudgins, D.; Freund, F.

1991-01-01

In modeling cometary ice, the properties of clathrate hydrates were used to explain anomalous gas release at large radial distances from the Sun, and the retention of particular gas inventories at elevated temperatures. Clathrates may also have been important early in solar system history. However, there has never been a reasonable mechanism proposed for clathrate formation under the low pressures typical of these environments. For the first time, it was shown that clathrate hydrates can be formed by warming and annealing amorphous mixed molecular ices at low pressures. The complex microstructures which occur as a result of clathrate formation from the solid state may provide an explanation for a variety of unexplained phenomena. The vacuum and imaging systems of an Hitachi H-500H Analytical Electron Microscope was modified to study mixed molecular ices at temperatures between 12 and 373 K. The resulting ices are characterized by low-electron dose Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED). The implications of these results for the mechanical and gas release properties of comets are discussed. Laboratory IR data from similar ices are presented which suggest the possibility of remotely observing and identifying clathrates in astrophysical objects.

Bacopa monnieri and its constituents is hypotensive in anaesthetized rats and vasodilator in various artery types.

PubMed

Kamkaew, Natakorn; Scholfield, C Norman; Ingkaninan, Kornkanok; Maneesai, Putcharawipa; Parkington, Helena C; Tare, Marianne; Chootip, Krongkarn

2011-09-01

Bacopa monnieri (Brahmi) provides traditional cognitive treatments possibly reflecting improved cerebral hemodynamics. Little is known about the cardiovascular actions of Brahmi. We sought to assess its effects on blood pressure and on isolated arteries, thus providing insights to clinical applications. Intravenous Brahmi (20-60 mg/kg) was tested on arterial blood pressure and heart rate of anaesthetized rats. In vitro vasorelaxation was assessed in arteries, with and without blockers of nitric oxide synthase (L-NAME), cyclooxygenase (indomethacin), and mechanical de-endothelialisation. The effects of Brahmi on Ca(2+) influx and release from stores were investigated. Intravenous Brahmi extract (20-60 mg/kg) decreased systolic and diastolic pressures without affecting heart rate. Brahmi evoked relaxation in isolated arteries in order of potency: basilar (IC50=102 ± 16 μg/ml)>mesenteric (171 ± 31)>aortae (213 ± 68)>renal (IC50=375 ± 51)>tail artery (494 ± 93)>femoral arteries (>1,000 μg/ml). Two saponins, bacoside A3 and bacopaside II, had similar vasodilator actions (IC50=8.3 ± 1.7 and 19.5 ± 6.3 μM). In aortae, without endothelium or in L-NAME (10-4M), Brahmi was less potent (IC50=213 ± 68 to 2170 ± 664 and 1192 ± 167 μg/ml, respectively); indomethacin (10-5M) was ineffective. In tail artery, Brahmi inhibited K(+)-depolarization induced Ca(2+) influx and Ca(2+) release from the sarcoplasmic reticulum by phenylephrine (10-5M) or caffeine (20mM). Brahmi reduces blood pressure partly via releasing nitric oxide from the endothelium, with additional actions on vascular smooth muscle Ca(2+) homeostasis. Some Brahmi ingredients could be efficacious antihypertensives and the vasodilation could account for some medicinal actions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

The NACHT, LRR and PYD Domains-Containing Protein 3 (NLRP3) Inflammasome Mediates Inflammation and Voiding Dysfunction in a Lipopolysaccharide-Induced Rat Model of Cystitis

PubMed Central

Hughes, Francis M; Kennis, James G; Youssef, Melissa N; Lowe, Danielle W; Shaner, Brooke E; Purves, J Todd

2016-01-01

Objective NOD-like receptors (NLRs) sense sterile and non-sterile signals and form inflammasomes which trigger an inflammatory response through the activation of caspase-1 and release of IL-1β. Recently we have shown the presence of several NLRs in the bladder urothelia and demonstrated the importance of NLRP3 in bladder outlet obstruction and cyclophosphamide-induced cystitis, both models of sterile inflammation. In this study we explore a role for NLRP3 in mediating the response to LPS, a key antigen of uropathogenic bacteria. Method In order to bypass the protective glycosaminoglycan layer lining the urothelium, LPS was directly injected into the bladder wall of Sprague-Dawley rats. Glyburide (a NLRP3 inhibitor) or vehicle was administered orally prior to and after injection. Rats were analyzed 24 h later. Inflammasome activity (caspase-1 activity, IL-1β release) and inflammation (Evan’s Blue extravasation, bladder weight) were assessed, as was physiological bladder function (urodynamics). Results Injection of LPS stimulated inflammasome activation (caspase-1 activity) and the release of IL-1β into the urine which was prevented by glyburide. Likewise, LPS increased inflammation, (bladder weight and the extravasation of Evan’s blue dye), and this was reversed by glyburide. Functionally, animals injected with saline alone demonstrated decreased voiding volume as measured by urodynamics. In the presence of LPS, additional urinary dysfunction was evident with decreased voiding pressures and threshold pressures. The decrease in voiding pressure was blocked by glyburide but the decrease in threshold pressure was not, suggesting that LPS has significant effects mediated by inflammasome-dependent and -independent mechanisms. Conclusion Overall, the results demonstrate the potential importance of inflammasomes in bacterial cystitis as well as the ability of the bladder wall injection technique to isolate the in vivo effects of specific inflammasome ligands to the physiological changes associated with cystitis. PMID:27066297

Methods to Stabilize and Destabilize Ammonium Borohydride

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

Nielsen, Thomas K.; Karkamkar, Abhijeet J.; Bowden, Mark E.

2013-01-21

Ammonium borohydride, NH4BH4, has a high hydrogen content of ρm = 24.5 wt% H2 and releases 18 wt% H2 below T = 160 °C. However, the half-life of bulk NH4BH4 at ambient temperatures, ~6 h, is insufficient for practical applications. The decomposition of NH4BH4 (ABH2) was studied at variable hydrogen and argon back pressures to investigate possible pressure mediated stabilization effects. The hydrogen release rate from solid ABH2 at ambient temperatures is reduced by ~16 % upon increasing the hydrogen back pressure from 5 to 54 bar. Similar results were obtained using argon pressure and the observed stabilization may bemore » explained by a positive volume of activation in the transition state leading to hydrogen release. Nanoconfinement in mesoporous silica, MCM-41, was investigated as alternative means to stabilize NH4BH4. However, other factors appear to significantly destabilize NH4BH4 and it rapidly decomposes at ambient temperatures into [(NH3)2BH2][BH4] (DADB) in accordance with the bulk reaction scheme. The hydrogen desorption kinetics from nanoconfined [(NH3)2BH2][BH4] is moderately enhanced as evidenced by a reduction in the DSC decomposition peak temperature of ΔT = -13 °C as compared to the bulk material. Finally, we note a surprising result, storage of DADB at temperature < -30 °C transformed, reversibly, the [(NH3)2BH2][BH4] into a new low temperature polymorph as revealed by both XRD and solid state MAS 11B MAS NMR. TA & AK are thankful for support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle.« less

What Preconception Tests Might I Need?

MedlinePlus

... Topics Pregnancy Sexually Transmitted Diseases (STDs) Diabetes NICHD News Spotlights Science Update: Diets low in certain minerals linked to problem with ovulation Release: Elevated blood pressure before pregnancy may increase chance of pregnancy ... BACK TO TOP Content Owner Office of Communications ...

21 CFR 178.3910 - Surface lubricants used in the manufacture of metallic articles.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 10 minutes. (The reaction between the sulfoxide and the acid is exothermic. Release pressure after...,” above) until siphon action occurs and then refill the tube body. Supply heat to the boiling flask and...

Impact of Saccharomyces cerevisiae strains on traditional sparkling wines production.

PubMed

Di Gianvito, Paola; Perpetuini, Giorgia; Tittarelli, Fabrizia; Schirone, Maria; Arfelli, Giuseppe; Piva, Andrea; Patrignani, Francesca; Lanciotti, Rosalba; Olivastri, Lino; Suzzi, Giovanna; Tofalo, Rosanna

2018-07-01

Sparkling wine fermentation is a challenge for yeasts due to the hostile conditions. A phenotype sought in starters is flocculation, because it reduces riddling time. For this reason, six flocculent Saccharomyces cerevisiae wine strains with different flocculation degree and autolytic activity and two commercial strains were tested for traditional sparkling wine production in a winery. Yeast viability, free aminoacids and high molecular weight nitrogen release and physico-chemical composition of sparkling wines were evaluated. Moreover, strains were tested for their aromatic potential. Obtained data revealed that flocculent yeasts presented oenological performances (in terms of fermentation rate, maximum pressure reached, free aminoacids - AAN and high molecular weight nitrogen - HMWN release) similar to the commercial strains. All considered strains were able to complete fermentation and viable cells of all strains were detected in all sparkling wines produced even after 6 months. F6789 and F10471 strains showed slow fermentation kinetics reaching the maximum of pressure at 180 days. Regarding nitrogen compounds release, FI strain was characterized by the highest amount of AAN and HMWN released, followed by F6789. Strains showed a considerable diversification in terms of number and amount of aroma molecules produced and sparkling wines obtained with autochthonous flocculent strains presented a higher amount of alcohols and esters already after 3 months. Further studies are necessary to select starter strains to improve traditional sparkling wines production. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Role of Compressibility in Energy Release by Magnetic Reconnection

NASA Technical Reports Server (NTRS)

Birn, J.; Borovosky, J. E.; Hesse, M.

2012-01-01

Using resistive compressible magnetohydrodynamics, we investigate the energy release and transfer by magnetic reconnection in finite (closed or periodic) systems. The emphasis is on the magnitude of energy released and transferred to plasma heating in configurations that range from highly compressible to incompressible, based on the magnitude of the background beta (ratio of plasma pressure over magnetic pressure) and of a guide field in two-dimensional reconnection. As expected, the system becomes more incompressible, and the role of compressional heating diminishes, with increasing beta or increasing guide field. Nevertheless, compressional heating may dominate over Joule heating for values of the guide field of 2 or 3 (in relation to the reconnecting magnetic field component) and beta of 5-10. This result stems from the strong localization of the dissipation near the reconnection site, which is modeled based on particle simulation results. Imposing uniform resistivity, corresponding to a Lundquist number of 10(exp 3) to 10(exp 4), leads to significantly larger Ohmic heating. Increasing incompressibility greatly reduces the magnetic flux transfer and the amount of energy released, from approx. 10% of the energy associated with the reconnecting field component, for zero guide field and low beta, to approx. 0.2%-0.4% for large values of the guide field B(sub y0) > 5 or large beta. The results demonstrate the importance of taking into account plasma compressibility and localization of dissipation in investigations of heating by turbulent reconnection, possibly relevant for solar wind or coronal heating.

Kinetic Modeling of Slow Energy Release in Non-Ideal Carbon Rich Explosives

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

Vitello, P; Fried, L; Glaesemann, K

2006-06-20

We present here the first self-consistent kinetic based model for long time-scale energy release in detonation waves in the non-ideal explosive LX-17. Non-ideal, insensitive carbon rich explosives, such as those based on TATB, are believed to have significant late-time slow release in energy. One proposed source of this energy is diffusion-limited growth of carbon clusters. In this paper we consider the late-time energy release problem in detonation waves using the thermochemical code CHEETAH linked to a multidimensional ALE hydrodynamics model. The linked CHEETAH-ALE model dimensional treats slowly reacting chemical species using kinetic rate laws, with chemical equilibrium assumed for speciesmore » coupled via fast time-scale reactions. In the model presented here we include separate rate equations for the transformation of the un-reacted explosive to product gases and for the growth of a small particulate form of condensed graphite to a large particulate form. The small particulate graphite is assumed to be in chemical equilibrium with the gaseous species allowing for coupling between the instantaneous thermodynamic state and the production of graphite clusters. For the explosive burn rate a pressure dependent rate law was used. Low pressure freezing of the gas species mass fractions was also included to account for regions where the kinetic coupling rates become longer than the hydrodynamic time-scales. The model rate parameters were calibrated using cylinder and rate-stick experimental data. Excellent long time agreement and size effect results were achieved.« less

Effect of cosmetic matrices on the release and odour profiles of the supercritical CO2 extract of Origanum majorana L.

PubMed

Costa, P; Velasco, C V; Loureiro, J M; Rodrigues, A E

2016-08-01

In this study, the effect of different cosmetic matrices on the release profile and odour intensity of the fragrance O. majorana was investigated for the first time. The fragrance compounds of O. majorana were extracted by supercritical fluid extraction using carbon dioxide (SFE-CO2 ) at 40°C and two operating pressures (8.5 and 10 MPa), and their chemical profiles were assessed by gas chromatography with flame ionization detector coupled with mass spectrometry (GC-FID/MS). Lastly, the fragrance compounds were incorporated into three cosmetic matrices (glycerine, dipropylene glycol and skin lotion) to assess their release and odour profiles over time using dynamic headspace (DHS)/GC-FID/MS and Odour Value concept, respectively. The SFE-CO2 enabled recovering extracts with the pleasant scent of the living plant, and the increment of pressure induced an increase on the extraction yield. GC-FID/MS analyses revealed that oxygen-containing monoterpenes was the principal group of components identified in both SFE-CO2 extracts. The fragrance compounds were more retained in dipropylene glycol, and the major deviations from the original odour intensity (control) were observed in the presence of dipropylene glycol and skin lotion. The hydrophilic character of the cosmetic matrices strongly influenced the release of the fragrance compounds, thus affecting the odour profile of the studied mixtures. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Platelet TGF-β1 contributions to plasma TGF-β1, cardiac fibrosis, and systolic dysfunction in a mouse model of pressure overload

PubMed Central

Meyer, Alexander; Wang, Wei; Qu, Jiaxiang; Croft, Lori; Degen, Jay L.; Coller, Barry S.

2012-01-01

Circulating platelets contain high concentrations of TGF-β1 in their α-granules and release it on platelet adhesion/activation. We hypothesized that uncontrolled in vitro release of platelet TGF-β1 may confound measurement of plasma TGF-β1 in mice and that in vivo release and activation may contribute to cardiac pathology in response to constriction of the transverse aorta, which produces both high shear and cardiac pressure overload. Plasma TGF-β1 levels in blood collected from C57Bl/6 mice by the standard retro-bulbar technique were much higher than those obtained when prostaglandin E1 was added to inhibit release or when blood was collected percutaneously from the left ventricle under ultrasound guidance. Even with optimal blood drawing, plasma TGF-β1 was lower in mice rendered profoundly thrombocytopenic or mice with selectively low levels of platelet TGF-β1 because of megakaryocytespecific disruption of their TGF-β1 gene (Tgfb1flox). Tgfb1flox mice were also partially protected from developing cardiac hypertrophy, fibrosis, and systolic dysfunction in response to transverse aortic constriction. These studies demonstrate that plasma TGF-β1 levels can be assessed accurately, but it requires special precautions; that platelet TGF-β1 contributes to plasma levels of TGF-β1; and that platelet TGF-β1 contributes to the pathologic cardiac changes that occur in response to aortic constriction. PMID:22134166

Cyclosporine a loaded solid lipid nanoparticles: optimization of formulation, process variable and characterization.

PubMed

Varia, Jigisha K; Dodiya, Shamsunder S; Sawant, Krutika K

2008-01-01

Solid lipid nanoparticles (SLNs) loaded with Cyclosporine A using glyceryl monostearate (GMS) and glyceryl palmitostearate (GPS) as lipid matrices were prepared by melt-homogenization using high-pressure homogenizer. Various process parameters such as homogenization pressure, homogenization cycles and formulation parameters such as ratio of drug: lipid, emulsifier: lipid and emulsifier: co-emulsifier were optimized using particle size and entrapment efficiencies as the dependent variables. The mean particle size of optimized batches of the GMS SLN and GPS SLN were found to be 131 nm and 158 nm and their entrapment efficiencies were 83 +/- 3.08% and 97 +/- 2.59% respectively. To improve the handling processing and stability of the prepared SLNs, the SLN dispersions were spray dried and its effect on size and reconstitution parameters were evaluated. The spray drying of SLNs did not significantly alter the size of SLNs and they exhibited good redispersibility. Solid state studies such as Infra Red Spectroscopy and Differential Scanning Calorimetry indicated absence of any chemical interaction between Cyclosporine A and the lipids. Scanning Electron Microscopy of optimized formulations showed spherical shape with smooth and non porous surface. In vitro release studies revealed that GMS based SLNs released the drug faster (41.12% in 20 hours) than GPS SLNs (7.958% in 20 hours). Release of Cyclosporine A from GMS SLN followed Higuchi equation better than first order while release from GPS SLN followed first order better than Higuchi model.

Investigation of Surface Phenomena in Shocked Tin in Converging Geometry

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

Rousculp, Christopher L.; Oro, David Michael; Griego, Jeffrey Randall

2016-03-21

There is great interest in the behavior of the free surface of tin under shock loading. While it is known that meso-scale surface imperfections can seed the Richtmyer- Meshkov Instability (RMI) for a surface that is melted on release, much less is known about a tin surface that is solid, but plastically deforming. Here material properties such as shear and yield strength come into play especially in converging geometry. Previous experiments have been driven by direct contact HE. Usually a thin, flat target coupon is fielded with various single-mode, sinusoidal, machined, profiles on the free surface. The free surface ismore » adjacent to either vacuum or an inert receiver gas. Most of these previous driver/target configurations have been nominal planer geometry. With modern HE it has been straightforward to shock tin into melt on release. However it has been challenging to achieve a low enough pressure for solid state on release. Here we propose to extend the existing base of knowledge to include the behavior of the free surface of tin in cylindrical converging geometry. By shock loading a cylindrical tin shell with a magnetically driven cylindrical liner impactor, the free surface evolution can be diagnosed with proton radiography. With the PHELIX capacitor bank, the drive can easily be varied to span the pressure range to achieve solid, mixed, and liquid states on release. A conceptual cylindrical liner and target is shown in Figure 1.« less

Precise method to determine points on isentropic release curve on copper

NASA Astrophysics Data System (ADS)

Remiot, C.; Mexmain, J. M.; Bonnet, L.

1996-05-01

When a higher shock impedance foil (with several hundreds of μm in thickness) is set on the studied material surface, the release phase occurs by steps, whose duration of each plateau corresponds to a go and return of the shock wave in the foil. Step velocity levels can be easily measured by D.L.I. technique. The intermediate velocity values, connected with the knowledge of the foil Hugoniot, allow us to determine a few points on the isentropic release curve. The experiments have been achieved on a two stage light gas gun with a projectile velocity varying from 1400 to 3000 m/s. The caliber of the launcher is 30 mm. For this study concerning copper, the target is composed of a 2 mm thickness copper transmitter on which the sample is mechanically held. The tungsten (W) thick foil is, under pressure, sticked on the sample with UV stick-cord. The free surface velocity measurement accuracy of the tungsten foil is 0.4% for values between 1500 to 3500 m/s. The first shock in the sample is varying from 40 to 120 GPa and the mass velocity from 800 to 2000 m/s. By impedance matching between the copper sample and the tungsten thick foil, we deduce for each experiment three points on the copper isentropic release curve and the final free surface velocity. The accuracy we obtain is in order of 0.4 GPa for the pressure and 10 m/s for the mass velocity.

Do alterations in prostanoid or catecholamine release influence the antiarrhythmic activity of nicergoline?

PubMed

Williams, F M; Coker, S J; Dean, H G; Kane, K A; Parratt, J R

1986-01-01

We examined the effects of nicergoline, an alpha-adrenoceptor blocking drug and an inhibitor of platelet phospholipase, on haemodynamics, blood gases, cardiac arrhythmias, and prostanoid and catecholamine release in anaesthetised greyhounds before, during, and after a 40-min occlusion of the left anterior descending coronary artery. Twenty-five minutes after commencing the intravenous infusion of nicergoline (50 micrograms kg-1 min-1) there were significant reductions in heart rate, arterial blood pressure, left ventricular dP/dtmax, and cardiac output. Nicergoline also increased the 0(2) extraction by the myocardium both before and during coronary artery occlusion. In contrast to control animals, heart rate decreased but there were no further reductions in arterial blood pressure during the occlusion period. Nicergoline improved survival (from 17 in control dogs to 50%) following the combined period of myocardial ischaemia and reperfusion and appeared to suppress the phase 1b occlusion-induced arrhythmias. The release of thromboxane B2 from the ischaemic myocardium was partially suppressed by nicergoline, and the ratio of 6-keto PGF1 alpha/thromboxane B2 (the stable breakdown products of prostacyclin and thromboxane A2, respectively) was increased. The washout of noradrenaline and adrenaline from the ischaemic myocardium following release of the occlusion was slightly enhanced by nicergoline. It is concluded that the beneficial metabolic and prostacyclin-promoting properties of nicergoline may be opposed by its action on noradrenaline washout, thus limiting its antiarrhythmic effectiveness.

Increased PSA expression on prostate cancer exosomes in in vitro condition and in cancer patients.

PubMed

Logozzi, Mariantonia; Angelini, Daniela F; Iessi, Elisabetta; Mizzoni, Davide; Di Raimo, Rossella; Federici, Cristina; Lugini, Luana; Borsellino, Giovanna; Gentilucci, Alessandro; Pierella, Federico; Marzio, Vittorio; Sciarra, Alessandro; Battistini, Luca; Fais, Stefano

2017-09-10

Prostate specific antigen (PSA) test is the most common, clinically validated test for the diagnosis of prostate cancer (PCa). While neoplastic lesions of the prostate may cause aberrant levels of PSA in the blood, the quantitation of free or complexed PSA poorly discriminates cancer patients from those developing benign lesions, often leading to invasive and unnecessary surgical procedures. Microenvironmental acidity increases exosome release by cancer cells. In this study we evaluated whether acidity, a critical phenotype of malignancy, could influence exosome release and increase the PSA expression in nanovesicles released by PCa cells. To this aim, we exploited Nanoparticle Tracking Analysis (NTA), an immunocapture-based ELISA, and nanoscale flow-cytometry. The results show that microenvironmental acidity induces an increased release of nanovesicles expressing both PSA and the exosome marker CD81. In order to verify whether the changes induced by the local selective pressure of extracellular acidity may correspond to a clinical pathway we used the same approach to evaluate the levels of PSA-expressing exosomes in the plasma of PCa patients and controls, including subjects with benign prostatic hypertrophy (BPH). The results show that only PCa patients have high levels of nanovesicles expressing both CD81 and PSA. This study shows that tumor acidity exerts a selective pressure leading to the release of extracellular vesicles that express both PSA and exosome markers. A comparable scenario was shown in the plasma of prostate cancer patients as compared to both BPH and healthy controls. These results suggest that microenvironmental acidity may represent a key factor which determines qualitatively and quantitatively the release of extracellular vesicles by malignant tumors, including prostate cancer. This condition leads to the spill-over of nanovesicles into the peripheral blood of prostate cancer patients, where the levels of tumor biomarkers expressed by exosomes, such as PSA-exosomes, may represent a novel, non-invasive clinical tool for the screening and early diagnosis of prostate cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

Testing of self-repairing composite airplane components by use of CAI and the release of the repair chemicals from carefully inserted small tubes

NASA Astrophysics Data System (ADS)

Dry, Carolyn

2007-04-01

The research on self repair of airplane components, under an SBIR phase II with Wright Patterson Air Force Base, has investigated the attributes and best end use applications for such a technology. These attributes include issues related to manufacturability, cost, potential benefits such as weight reduction, and cost reduction. The goal of our research has been to develop self-repairing composites with unique strength for air vehicles. Our revolutionary approach involves the autonomous release of repair chemicals from within the composite matrix itself. The repair agents are contained in hollow, structural fibers that are embedded within the matrix. Under stress, the composite senses external environmental factors and reacts by releasing the repair agents from within the hollow vessels. This autonomous response occurs wherever and whenever cracking, debonding or other matrix damage transpires. Superior performance over the life of the composite is achieved through this self-repairing mechanism. The advantages to the military would be safely executed missions, fewer repairs and eventually lighter vehicles. In particular the research has addressed the issues by correlating the impact of the various factors, such as 1) delivery vessel placement, shape/size and effect on composite strength, chemicals released and their effect on the matrix, release trigger and efficacy and any impact on matrix properties 2) impact of composite processing methods that involve heat and pressure on the repair vessels. Our self repairing system can be processed at temperatures of 300-350F, repairs in less than 30 seconds and does not damage the composite by repair fiber insertion or chemical release. Scaling up and manufacture of components has revealed that anticipating potential problems allowed us to avoid those associated with processing temperatures and pressures. The presentation will focus on compression after impact testing and the placement of repair fibers/tubes into prepreg laminates.

An Active Englacial Hydrological System in a Cold Glacier: Blood Falls, Taylor Glacier, Antarctica

NASA Astrophysics Data System (ADS)

Carr, C. G.; Pettit, E. C.; Carmichael, J.; Badgeley, J.; Tulaczyk, S. M.; Lyons, W. B.; Mikucki, J.

2016-12-01

Blood Falls is a supraglacial hydrological feature formed by episodic release of iron-rich subglacial brine derived from an extensive aquifer beneath the cold, polar, Taylor Glacier. While fluid transport in non-temperate ice typically occurs through meltwater delivery from the glacier surface to the bed (hydrofracturing, supraglacial lake drainage), Blood Falls represents the opposite situation: brine moves from a subglacial source to the glacier surface. Here, we present the first complete conceptual model for brine transport and release, as well as the first direct evidence of a wintertime brine release at Blood Falls obtained through year-round time-lapse photography. Related analyses show that brine pools subglacially underneath the northern terminus of Taylor Glacier, rather than flowing directly into proglacial Lake Bonney because ice-cored moraines and channelized surface topography provide hydraulic barriers. This pooled brine is pressurized by hydraulic head from the upglacier brine source region. Based on seismic data, we propose that episodic supraglacial release is initiated by high strain rates coupled with pressurized subglacial brine that drive intermittent subglacial and englacial fracturing. Ultimately, brine-filled basal crevasses propagate upward to link with surface crevasses, allowing brine to flow from the bed to the surface. The observation of wintertime brine release indicates that surface-generated meltwater is not necessary to trigger crack propagation or to maintain the conduit as previously suggested. The liquid brine persists beneath and within the cold ice (-17°C) despite ambient ice/brine temperature differences of as high as 10°C through both locally depressed brine freezing temperatures through cryoconcentration of salts and increased ice temperatures through release of latent heat during partial freezing of brine. The existence of an englacial hydrological system initiated by basal crevassing extends to polar glaciers a process thought limited to temperate glaciers and confirms that supraglacial, englacial, and subglacial hydrological systems act in concert to provide critical forcing on glacier dynamics, even in cold polar ice.

Large-scale field testing on flexible shallow landslide barriers

NASA Astrophysics Data System (ADS)

Bugnion, Louis; Volkwein, Axel; Wendeler, Corinna; Roth, Andrea

2010-05-01

Open shallow landslides occur regularly in a wide range of natural terrains. Generally, they are difficult to predict and result in damages to properties and disruption of transportation systems. In order to improve the knowledge about the physical process itself and to develop new protection measures, large-scale field experiments were conducted in Veltheim, Switzerland. Material was released down a 30° inclined test slope into a flexible barrier. The flow as well as the impact into the barrier was monitored using various measurement techniques. Laser devices recording flow heights, a special force plate measuring normal and shear basal forces as well as load cells for impact pressures were installed along the test slope. In addition, load cells were built in the support and retaining cables of the barrier to provide data for detailed back-calculation of load distribution during impact. For the last test series an additional guiding wall in flow direction on both sides of the barrier was installed to achieve higher impact pressures in the middle of the barrier. With these guiding walls the flow is not able to spread out before hitting the barrier. A special constructed release mechanism simulating the sudden failure of the slope was designed such that about 50 m3 of mixed earth and gravel saturated with water can be released in an instant. Analysis of cable forces combined with impact pressures and velocity measurements during a test series allow us now to develop a load model for the barrier design. First numerical simulations with the software tool FARO, originally developed for rockfall barriers and afterwards calibrated for debris flow impacts, lead already to structural improvements on barrier design. Decisive for the barrier design is the first dynamic impact pressure depending on the flow velocity and afterwards the hydrostatic pressure of the complete retained material behind the barrier. Therefore volume estimation of open shallow landslides by assessing the thickness of the failure layer and the width of the possible failure are essential for the required barrier design parameter height and width. First results of the calculated drag coefficients of dynamic impact pressure measurements showed that the dynamic coefficient cw is much lower than 1.0 which is contradictory to most of existing dimensioning property protection guidelines. It appears to us that special adaptation to the system like smaller mesh sizes and special ground-barrier interface compared to normal rock-fall barriers and channelised debris flow barriers are necessary to improve the retention behavior of shallow landslide barriers. Detailed analysis of the friction coefficient in relationship with pore water pressure measurements gives interesting insights into the dynamic of fluid-solid mixed flows. Impact pressures dependencies on flow features are analyzed and discussed with respect to existing models and guidelines for shallow landslides.

NOS3 genotype-dependent correlation between blood pressure and physical activity.

PubMed

Kimura, Tomomi; Yokoyama, Tetsuji; Matsumura, Yasuhiro; Yoshiike, Nobuo; Date, Chigusa; Muramatsu, Masaaki; Tanaka, Heizo

2003-02-01

Endothelium-dependent vasorelaxation plays an important role in reduction of blood pressure and is mediated through release of nitric oxide (NO), which is generated by constitutively expressed endothelial nitric oxide synthase (NOS3). Exercise also augments NO release and has been recommended for primary prevention and improvement of hypertension, but individual responses are highly variable. We therefore postulated that genetic polymorphisms of NOS3 might interact with physical activity level to differentially influence blood pressure level. We genotyped 832 healthy Japanese (mean age of 54.4+/-8.6 years, 372 men and 460 women) for a polymorphism of NOS3 in intron 4 (ecNOS4a/b), using the polymerase chain reaction method, and scored their habitual physical activity level by using the rate of energy expenditure per resting metabolic rate through an interview according to a semiquantitative assessment method. Only in the subjects who had the rarer a allele (aa+ba type), systolic blood pressure was found to be inversely correlated with physical activity level (P for linear trend=0.0496, for interaction=0.0071). Eventually, this polymorphism was significantly associated with the prevalence of systolic hypertension only in the subjects who were in the lowest tertile of physical activity level (OR=2.4, 95% CI, 1.1 to 5.6, P for interaction=0.0474). In the present study, we found a significant interaction between the genotype and physical activity level on systolic blood pressure. These results might allow a better understanding of the mechanism to improve hypertension by exercise and to thereby reduce the risk of cardiovascular disease.

Analytical Solutions to Coupled HM Problems to Highlight the Nonlocal Nature of Aquifer Storage

NASA Astrophysics Data System (ADS)

De Simone, Silvia; Carrera, Jesús

2017-11-01

Specific storage reflects the volumetric deformation capacity of permeable media. Classical groundwater hydrology equates elastic storage to medium compressibility (plus fluid compressibility times porosity). However, it is unclear if storage behavior can be represented by a single parameter. Hydraulic gradients act as body forces that push the medium in the direction of flow causing it to deform instantaneously everywhere, i.e., even in regions where pressure would not have changed according to conventional fluid flow. Therefore, actual deformation depends not only on the mechanical properties of the medium but also on aquifer geometry and on surrounding strata, which act like constraints to displacements. Here we discuss the question and highlight the nonlocal nature of storage (i.e., the volume of water released at a point depends on the poroelastic response over the whole aquifer). Proper evaluation of transient pressure and water release from storage requires acknowledging the hydromechanical coupling, which generally involves the use of numerical methods. We propose analytical solutions to the HM problem of fluid injection (extraction) into finite aquifers with one-dimensional or cylindrical geometries. We find that pressure response is much faster (virtually instantaneous) and larger than expected from traditional purely hydraulic solutions when aquifer deformation is restrained, whereas the pressure response is reversed (i.e., pressure drop in response to injection) when the permeable medium is free to deform. These findings suggest that accounting for hydromechanical coupling may be required when hydraulic testing is performed in low permeability media, which is becoming increasingly demanded for energy-related applications.

Inactivation of Bacillus subtilis spores by high pressure CO2 with high temperature.

PubMed

Rao, Lei; Xu, Zhenzhen; Wang, Yongtao; Zhao, Feng; Hu, Xiaosong; Liao, Xiaojun

2015-07-16

The objective of this study was to investigate the inactivation of the Bacillus subtilis spores by high pressure CO2 combined with high temperature (HPCD+HT) and to analyze the clumping effect of the spores on their HPCD+HT resistance. The spores of B. subtilis were subjected to heat at 0.1 MPa and HPCD at 6.5-25 MPa, and 82 °C, 86 °C, and 91 °C for 0-120 min. The spores were effectively inactivated by HPCD+HT, but a protective effect on the spores was also found, which was closely correlated to the pressure, temperature and time. The spores treated by HPCD+HT at 6.5 and 10 MPa exhibited a two-stage inactivation curve of shoulder and log-linear regions whereas the spores at 15-25 MPa exhibited a three-stage inactivation curve of shoulder, log-linear and tailing regions, and these curves were well fitted to the Geeraerd model. Approximately 90% of pyridine-2,6-dicarboxylic acid (DPA) was released after HPCD+HT and the 90% DPA release time depend on the pressure and temperature. Moreover, the spore clumping in suspensions was examined by dynamic light scattering. The particle size of the spore suspensions increased with the increase of pressure, temperature and time, indicating the spore clumping. 0.1% Tween 80 as a surfactant inhibited the spore clumping and increased the inactivation ratio of the spores by HPCD+HT. These results indicated that the spore clumping enhanced the spores' resistance to HPCD+HT and induced a protective effect. Copyright © 2015 Elsevier B.V. All rights reserved.

A painful pulsatile abdominal mass in a young man with elevated blood pressures: an unusual presentation of phaeochromocytoma.

PubMed

Lee, B M K; Ti, L K

2002-08-01

We report an unusual presentation of phaeochromocytoma in a young man with a painful, pulsatile abdominal mass and elevated blood pressures. This led to a delay in diagnosis and resulted in the administration of triggers of catecholamine release, possibly causing a catecholamine surge. This caused the development of catecholamine-induced cardiomyopathy and multiple organ failure, requiring inotropic and ventilatory support, intra-aortic balloon pump and dialysis. Fortunately, his condition reversed with supportive treatment and alpha-adrenergic blockade. This illustrates the importance of having a high index of suspicion of phaeochromocytoma, especially in young patients with elevated blood pressures.

Setting accelerated dissolution test for PLGA microspheres containing peptide, investigation of critical parameters affecting drug release rate and mechanism.

PubMed

Tomic, I; Vidis-Millward, A; Mueller-Zsigmondy, M; Cardot, J-M

2016-05-30

The objective of this study was development of accelerated in vitro release method for peptide loaded PLGA microspheres using flow-through apparatus and assessment of the effect of dissolution parameters (pH, temperature, medium composition) on drug release rate and mechanism. Accelerated release conditions were set as pH 2 and 45°C, in phosphate buffer saline (PBS) 0.02M. When the pH was changed from 2 to 4, diffusion controlled phases (burst and lag) were not affected, while release rate during erosion phase decreased two-fold due to slower ester bonds hydrolyses. Decreasing temperature from 45°C to 40°C, release rate showed three-fold deceleration without significant change in release mechanism. Effect of medium composition on drug release was tested in PBS 0.01M (200 mOsm/kg) and PBS 0.01M with glucose (380 mOsm/kg). Buffer concentration significantly affected drug release rate and mechanism due to the change in osmotic pressure, while ionic strength did not have any effect on peptide release. Furthermore, dialysis sac and sample-and-separate techniques were used, in order to evaluate significance of dissolution technique choice on the release process. After fitting obtained data to different mathematical models, flow-through method was confirmed as the most appropriate for accelerated in vitro dissolution testing for a given formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasound enhanced release of therapeutics from drug-releasing implants based on titania nanotube arrays.

PubMed

Aw, Moom Sinn; Losic, Dusan

2013-02-25

A non-invasive and external stimulus-driven local drug delivery system (DDS) based on titania nanotube (TNT) arrays loaded with drug encapsulated polymeric micelles as drug carriers and ultrasound generator is described. Ultrasound waves (USW) generated by a pulsating sonication probe (Sonotrode) in phosphate buffered saline (PBS) at pH 7.2 as the medium for transmitting pressure waves, were used to release drug-loaded nano-carriers from the TNT arrays. It was demonstrated that a very rapid release in pulsatile mode can be achieved, controlled by several parameters on the ultrasonic generator. This includes pulse length, time, amplitude and power intensity. By optimization of these parameters, an immediate drug-micelles release of 100% that spans a desirable time of 5-50 min was achieved. It was shown that stimulated release can be generated and reproduced at any time throughout the TNT-Ti implant life, suggesting considerable potential of this approach as a feasible and tunable ultrasound-mediated drug delivery system in situ via drug-releasing implants. It is expected that this concept can be translated from an in vitro to in vivo regime for therapeutic applications using drug-releasing implants in orthopedic and coronary stents. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Lateral Cricoarytenoid Release: Development of a Novel Surgical Treatment Option for Adductor Spasmodic Dysphonia in a Canine Laryngeal Model.

PubMed

Park, Andrea M; Paniello, Randal C

2016-09-01

To investigate the efficacy of a novel adductor muscle-releasing technique designed to decrease the force of vocal fold adduction, as a potential surgical therapy for patients with adductor spasmodic dysphonia (ADSD). Experimental animal study. A canine laryngeal model was used to assess the acute and sustained efficacy of a lateral cricoarytenoid (LCA) muscle release. A total of 34 canine hemilaryngeal preparations were divided among 7 experimental groups. The LCA muscle was separated from its cricoid cartilage origin via an open, anterior, submucosal approach. The laryngeal adductory pressures (LAP) were assessed pre- and post-muscle release via direct recurrent laryngeal nerve stimulation. Measurements were repeated at 1.5, 3, or 6 months postoperatively. Another study evaluated release of the thyroarytenoid (TA) muscle from its thyroid cartilage origin. Releasing the LCA muscle demonstrated a significant decrease in LAP acutely and was maintained at all 3 time points with the aid of a barrier (P < .05). Without the barrier, the LCA muscle reattached to the cricoid. Acute release of the TA muscle did not significantly decrease the LAP. The proposed LCA release procedure may provide patients with a permanent treatment option for ADSD. However, longer-term studies and human trials are needed. © The Author(s) 2016.

Comparison of electric and growth responses to excision in cucumber and pea seedlings. II. Long-distance effects are caused by the release of xylem pressure

NASA Technical Reports Server (NTRS)

Stahlberg, R.; Cosgrove, D. J.

1995-01-01

Excision of a growing stem causes local wound responses, such as membrane depolarization and growth inhibition, as well as effects at larger distances from the cut. In this study, cucumber hypocotyls were excised 100 mm below the hook, so that the growing region was beyond the reach of the wound-induced depolarization (up to 40 mm). Even at such a distance, the cut still caused a considerable and rapid drop in the hypocotyl growth rate. This growth response is not a direct wound response because it does not result from the cut-induced depolarization and because it can be simulated by root pressure manipulation (using a pressure chamber). The results indicate that the growth response resulted from the rapid release of the xylem pressure upon excision. To test this conclusion we measured the xylem pressure by connecting a pressure probe to the cut surface of the stem. Xylem pressure (Px) was found to be +10 to +40 kPa in cucumber hypocotyls and -5 to -10 kPa or lower in pea epicotyls. Excision of the cucumber hypocotyl base led to a rapid drop in Px to negative values, whereas excision in pea led to a rapid rise in Px to ambient (zero) pressure. These fast and opposite Px changes parallel the excision-induced changes in growth rate (GR): a decrease in cucumber and a rise in pea. The sign of the endogenous xylem pressure also determined whether excision induced a propagating depolarization in the form of a slow wave potential (SWP). Under normal circumstances pea seedlings generated an SWP upon excision whereas cucumber seedlings failed to do so. When the Px in cucumber hypocotyls was experimentally inverted to negative values by incubating the cumber roots in solutions of NaCN or n-ethylmaleimide, excision caused a propagating depolarization (SWP). The experiment shows that only hydraulic signals in the form of positive Px steps are converted into propagating electric SWP signals. These propagating depolarizations might be causally linked to systemic 'wound' responses, which occur independently of the short-distance or direct wound responses.

Protease-activated receptor 2-mediated protection of myocardial ischemia-reperfusion injury: role of transient receptor potential vanilloid receptors

PubMed Central

Zhong, Beihua

2009-01-01

Activation of the protease-activated receptor 2 (PAR2) or the transient receptor potential vanilloid type 1 (TRPV1) channels expressed in cardiac sensory afferents containing calcitonin gene-related peptide (CGRP) and/or substance P (SP) has been proposed to play a protective role in myocardial ischemia-reperfusion (I/R) injury. However, the interaction between PAR2 and TRPV1 is largely unknown. Using gene-targeted TRPV1-null mutant (TRPV1−/−) or wild-type (WT) mice, we test the hypothesis that TRPV1 contributes to PAR2-mediated cardiac protection via increasing the release of CGRP and SP. Immunofluorescence labeling showed that TRPV1 coexpressed with PAR2, PKC-ε, or PKAc in cardiomyocytes, cardiac blood vessels, and perivascular nerves in WT but not TRPV1−/− hearts. WT or TRPV1−/− hearts were Langendorff perfused with the selective PAR2 agonist, SLIGRL, in the presence or absence of various antagonists, followed by 35 min of global ischemia and 40 min of reperfusion (I/R). The recovery rate of coronary flow, the maximum rate of left ventricular pressure development, left ventricular end-diastolic pressure, and left ventricular developed pressure were evaluated after I/R. SLIGRL improved the recovery of hemodynamic parameters, decreased lactate dehydrogenase release, and reduced the infarct size in both WT and TRPV1−/− hearts (P < 0.05). The protection of SLIGRL was significantly surpassed for WT compared with TRPV1−/− hearts (P < 0.05). CGRP8–37, a selective CGRP receptor antagonist, RP67580, a selective neurokinin-1 receptor antagonist, PKC-ε V1–2, a selective PKC-ε inhibitor, or H-89, a selective PKA inhibitor, abolished SLIGRL protection by inhibiting the recovery of the rate of coronary flow, maximum rate of left ventricular pressure development, and left ventricular developed pressure, and increasing left ventricular end-diastolic pressure in WT but not TRPV1−/− hearts. Radioimmunoassay showed that SLIGRL increased the release of CGRP and SP in WT but not TRPV1−/− hearts (P < 0.05), which were prevented by PKC-ε V1–2 and H-89. Thus our data show that PAR2 activation improves cardiac recovery after I/R injury in WT and TRPV1−/− hearts, with a greater effect in the former, suggesting that PAR2-mediated protection is TRPV1 dependent and independent, and that dysfunctional TRPV1 impairs PAR2 action. PAR2 activation of the PKC-ε or PKA pathway stimulates or sensitizes TRPV1 in WT hearts, leading to the release of CGRP and SP that contribute, at least in part, to PAR2-induced cardiac protection against I/R injury. PMID:19812353

Benchtop-magnetic resonance imaging (BT-MRI) characterization of push-pull osmotic controlled release systems.

PubMed

Malaterre, Vincent; Metz, Hendrik; Ogorka, Joerg; Gurny, Robert; Loggia, Nicoletta; Mäder, Karsten

2009-01-05

The mechanism of drug release from push-pull osmotic systems (PPOS) has been investigated by Magnetic Resonance Imaging (MRI) using a new benchtop apparatus. The signal intensity profiles of both PPOS layers were monitored non-invasively over time to characterize the hydration and swelling kinetics. The drug release performance was well-correlated to the hydration kinetics. The results show that (i) hydration and swelling critically depend on the tablet core composition, (ii) high osmotic pressure developed by the push layer may lead to bypassing the drug layer and incomplete drug release and (iii) the hydration of both the drug and the push layers needs to be properly balanced to efficiently deliver the drug. MRI is therefore a powerful tool to get insights on the drug delivery mechanism of push-pull osmotic systems, which enable a more efficient optimization of such formulations.