Science.gov

Sample records for 18-ft diameter concentrator

  1. Robotic Manufacturing of 18-ft (5.5m) Diameter Cryogenic Fuel Tank Dome Assemblies for the NASA Ares I Rocket

    NASA Technical Reports Server (NTRS)

    Jones, Ronald E.; Carter, Robert W.

    2012-01-01

    The Ares I rocket was the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration's Constellation program. A series of full-scale Ares I development articles were constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7- axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This paper will focus on the friction stir welding of 18-ft (5.5m) diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome and two common bulkhead manufacturing development articles.

  2. Fabricated nano-fiber diameter as liquid concentration sensors

    NASA Astrophysics Data System (ADS)

    Chyad, Radhi M.; Mat Jafri, Mohd Zubir; Ibrahim, Kamarulazizi

    Nanofiber is characterized by thin, long, and very soft silica. Taper fibers are made using an easy and low cost chemical method. Etching is conducted with a HF solution to remove cladding and then a low molarity HF solution to reduce the fiber core diameter. One approach to on-line monitoring of the etching process uses spectrophotometer with a white light source. In the aforementioned technique, this method aims to determine the diameter of the reduced core and show the evolution of the two different processes from the nanofiber regime to the fixed regime in which the mode was remote from the surrounding evanescent field, intensity can propagate outside the segment fiber when the core diameter is less than 500 nm. Manufacturing technologies of nano-fiber sensors offer a number of approved properties of optical fiber sensors utilized in various sensory applications. The nano-fiber sensor is utilized to sense the difference in the concentration of D-glucose in double-distilled deionized water and to measure the refractive index (RI) of a sugar solution. Our proposed method exhibited satisfactory capability based on bimolecular interactions in the biological system. The response of the nano-fiber sensors indicates a different kind of interaction among various groups of AAs. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making or breaking ability of solutes in the given solution. This study utilized spectra photonics to measure the transmission of light through different concentrations of sugar solution, employing cell cumber and nano-optical fibers as sensors.

  3. Nano-fiber diameters as liquid concentration sensors

    NASA Astrophysics Data System (ADS)

    Chyad, Radhi M.; Mat Jafri, Mohd Zubir; Ibrahim, Kamarulazizi

    2013-05-01

    Manufacturing technologies of nano-fiber sensors offer a number of approved properties of optical fiber sensors utilized in various sensory applications. The nano-fiber sensor is utilized to sense the difference in the concentration of D-glucose in double-distilled deionized water and to measure the refractive index (RI) of a sugar solution. Our proposed method exhibited satisfactory capability based on bimolecular interactions in the biological system. The response of the nano-fiber sensors indicates a different kind of interaction among various groups of AAs. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making or breaking ability of solutes in the given solution. This study utilized spectra photonics to measure the transmission of light through different concentrations of sugar solution, employing cell cumber and nano-optical fibers as sensors.

  4. The effect of growth rate, diameter and impurity concentration on structure in Czochralski silicon crystal growth

    NASA Technical Reports Server (NTRS)

    Digges, T. G., Jr.; Shima, R.

    1980-01-01

    It is demonstrated that maximum growth rates of up to 80% of the theoretical limit can be attained in Czochralski-grown silicon crystals while maintaining single crystal structure. Attaining the other 20% increase is dependent on design changes in the grower, to reduce the temperature gradient in the liquid while increasing the gradient in the solid. The conclusions of Hopkins et al. (1977) on the effect of diameter on the breakdown of structure at fast growth rates are substantiated. Copper was utilized as the test impurity. At large diameters (greater than 7.5 cm), concentrations of greater than 1 ppm copper were attained in the solid (45,000 ppm in the liquid) without breakdown at maximum growth speeds. For smaller diameter crystals, the sensitivity of impurities is much more apparent. For solar cell applications, impurities will limit cell performance before they cause crystal breakdown for fast growth rates of large diameter crystals.

  5. Nutrient concentrations of runoff as affected by the diameter of unconsolidated material from feedlot surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beef cattle feedlots contain unconsolidated material that accumulates on the feedlot surface during a feeding cycle. This study was conducted to measure the effects of varying diameters of unconsolidated surface material and varying flow rates on nutrient concentrations in runoff. Unconsolidated sur...

  6. Effect of polyvinyl alcohol concentration in spinning dope on diameter, beads and HHS of produced nanofibers.

    PubMed

    Khajavi, Ramin; Damerchely, Rogheih

    2007-01-15

    In this study it was aimed to produce nano fibers of poly vinyl alcohol PVA polymer via electrospinning ES method and to investigate the role of PVA concentration in the spinning dope on diameter, beads and HHS of produced fibers. Spinning dopes with different concentrations of PVA at rang of 5 to 20% (wt/wt on weight of solution) prepared. The requisite voltage for ES (30 kv) was supplied by a DC high voltage power supply and for collecting the fibers a grounded aluminum foil target placed 17 cm below the tip of capillary tube (spinning nozzle). The results showed that spinning dopes with PVA concentration between 8 to 12% (wt/wt) are capable of producing PVA fibers, but those below 8% (wt/wt) concentrations because of low viscosity formed droplets known as electrospray effect. Electrospinning suppressed at spinning dope concentrations above 12% (wt/wt) due to high viscosity of dope. According to the SEM photographs of electrospun PVA fibers it revealed that in higher concentrations produced nanofibers have larger diameter with less beads and HHS in compare with lower concentrations. PMID:19070034

  7. Effects of ICG concentration and particle diameter on photophysical properties of ICG-doped nanoparticles

    NASA Astrophysics Data System (ADS)

    Crovisier, Jason; Bahmani, Baharak; Saleh, Reema; Vullev, Valentine; Anvari, Bahman

    2014-03-01

    The variety of nanoparticles developed by numerous investigators has presented a diverse platform for various optical imaging applications in biomedicine. We have previously reported that the FDA-approved chromophore Indocyanine Green (ICG) can be successfully encapsulated by cross-linked poly-allylamine hydrochloride (PAH)-Disodium Monophosphate (Na2HPO4) to form a nanoparticle for near-infrared imaging applications. The diameter of the constructs is dependent on the charge ratio between the polymer and salt used to encapsulate the chromophore. Modifications of the synthesis methods can alter the photophysical properties of the capsules, either through the adjustment of the charge ratio between PAH and Na2HPO4 or concentration of ICG successfully impregnated into the capsule. Through understanding the effects of tuning the nanoparticle properties, the photophysical characteristics of the constructs can be optimized. Here we present the results of adjusting the diameter of the nanoparticle and amount of ICG on the hydrodynamic diameters, absorption and fluorescence characteristics, and the relative fluorescence quantum yield. Optimizing the photophysical properties of the constructs can lead to increased imaging sensitivity and contrast for potential translational applications, including tumor imaging, which may utilize these nanoconstructs.

  8. Gas holdup in slurry bubble columns: Effect of column diameter and slurry concentrations

    SciTech Connect

    Krishna, R.; Swart, J.W.A. de; Ellenberger, J.; Martina, G.B.; Maretto, C.

    1997-02-01

    In processes for converting natural gas to liquid fuels, bubble-column reactors are finding increasing application. To study the influence of particle concentration on the hydrodynamics of bubble-column slurry reactors operating in the heterogeneous flow regime, experiments were carried out in 0.10, 0.19, and 0.38-m-dia. columns using paraffinic oil as the liquid phase and slurry concentrations of up to 36 vol. %. To interpret experimental results a generalization of the two-phase model for gas-solid fluid beds was used to describe bubble hydrodynamics. The two phases identified are: a dilute phase consisting of fast-rising large bubbles that traverse the column virtually in plug flow and a dense phase that is identified with the liquid phase along with solid particles and entrained small bubbles. The dense phase suffers backmixing considerably. Dynamic gas disengagement was experimented in the heterogeneous flow regime to determine the gas voidage in dilute and dense phases. Experimental data show that increasing the solid concentration decreases the total gas holdup significantly, but the influence on the dilute-phase gas holdup is small. The dense-phase gas voidage significantly decreases gas holdup due to enhanced coalescence of small bubbles resulting from introduction of particles. The dense-phase gas voidage is practically independent of the column diameter. The dilute-phase gas holdup, on the other hand, decreases with increasing column diameter, and this dependence could be described adequately with a slight modification of the correlation of Krishna and Ellenberger developed for gas-liquid systems.

  9. Small diameter concentric tubing extends economical life of high water - sour gas Edwards producers

    SciTech Connect

    Weeks, S.G.

    1981-01-01

    Seven small-diameter tubing installations have been completed in two Edwards sour gas fields, Texas, which have high water production. Although there has been further decline in reservoir pressure, continuous production has been maintained without stop-cocking. Corrosion inhibition has been effective and the cost has been nominal compared to the previous expense of displacing the inhibitor each month with nitrogen. Thus, the economical life of the wells has been extended. 5 refs.

  10. Generation of doubly charged vortex beam by concentrated loading of glass disks along their diameter.

    PubMed

    Skab, Ihor; Vasylkiv, Yuriy; Krupych, Oleh; Savaryn, Viktoriya; Vlokh, Rostyslav

    2012-04-10

    We show that a system of glass disks compressed along their diameters enables one to induce a doubly charged vortex beam in the emergent light when the incident light is circularly polarized. Using such a disk system, one can control the efficiency of conversion of the spin angular momentum to the orbital angular momentum by a loading force. The consideration presented here can be extended for the case of crystalline materials with high optical damage thresholds in order to induce high-power vortex beams. PMID:22505151

  11. Radiotherapy dosimetry and the thermoluminescence characteristics of Ge-doped fibres of differing germanium dopant concentration and outer diameter

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Fadzil, M. S. Ahmad; Ung, N. M.; Maah, M. J.; Mahdiraji, G. A.; Abdul-Rashid, H. A.; Bradley, D. A.

    2016-09-01

    We examine the influence of elevated dopant concentration on the thermoluminescence characteristics of novel Ge-doped silica fibres. Basic dosimetric characteristics of the TL media were obtained, including linearity, reproducibility, energy dependence, fading, minimum detectable dose and glow curve analysis, use being made of a 60Co gamma irradiation facility (mean energy 1.25 MeV) and an electron linear accelerator producing photons at an accelerating potential of 6 and 10 MV. The 6 mol% Ge-doped fibres were found to provide TL response superior to that of 8- and 10 mol% Ge-doped fibres, both for fibres with outer diameter of 241 μm and 604 μm. Concerning reproducibility, obtained under three different test conditions, at <10% the 6 mol% Ge dopant concentration was observed to provide the superior coefficient of variation (CV). In regard to energy dependence, the 10 mol% Ge doped cylindrical fibres produced the largest gradient values at 0.364 and 0.327 for the 241 μm and 604 μm diameter cylindrical fibres respectively and thus the greatest energy dependency. Measured 33 days post irradiation; the 6 mol% Ge doped cylindrical fibres showed the least TL signal loss, at 21% for the 241 μm cylindrical fibre and <40% for the 604 μm cylindrical fibres. The results also revealed that the 6 mol% optical fibres provided the lowest minimum detectable dose, at 0.027 Gy for 6 MV photon beams. Evaluations of these characteristics are supporting development of novel Ge-doped optical fibres for dosimetry in radiotherapy.

  12. Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris)

    PubMed Central

    Moore, Colby D.; Crocker, Daniel E.; Fahlman, Andreas; Moore, Michael J.; Willoughby, Darryn S.; Robbins, Kathleen A.; Kanatous, Shane B.; Trumble, Stephen J.

    2014-01-01

    Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH) based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb) concentrations in the longissimus dorsi (LD) muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults) may provide a protection against ischemia reperfusion (IR) injury in vasoconstricted peripheral skeletal muscle. PMID:24959151

  13. Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris).

    PubMed

    Moore, Colby D; Crocker, Daniel E; Fahlman, Andreas; Moore, Michael J; Willoughby, Darryn S; Robbins, Kathleen A; Kanatous, Shane B; Trumble, Stephen J

    2014-01-01

    Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH) based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb) concentrations in the longissimus dorsi (LD) muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults) may provide a protection against ischemia reperfusion (IR) injury in vasoconstricted peripheral skeletal muscle. PMID:24959151

  14. Interpreting stem diameter changes

    NASA Astrophysics Data System (ADS)

    Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2009-12-01

    Detecting phloem transport in stem diameter changes Teemu Hölttä1, Sanna Sevanto2, Eero Nikinmaa1 1Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland 2Department of Physics, P.O. Box 48, FIN-00014 University of Helsinki, Finland Introduction The volume of living cells and xylem conduits vary according to pressures they are subjected to. Our proposition is that the behavior of the inner bark diameter variation which cannot be explained by changes in xylem water status arise from changes in the osmotic concentration of the phloem and cambial growth. Materials and methods Simultaneous xylem and stem diameter measurements were conducted between June 28th to October 4th 2006 in Southern Finland on a 47-year old, 15 meter tall, Scots pine tree (DBH 15 cm) at heights of 1.5 and 10 meters. The difference between the measured inner bark diameter and the inner bark diameter predicted from xylem diameter change with a simple model (assuming there was no change in the osmotic concentration of the phloem) is hypothesized to give the changes in the osmotic concentration of the inner bark. The simple model calculates the radial water exchange between the xylem and phloem driven by the water potential changes in the xylem. Results and Discussion The major signal in the inner bark diameter was the transpiration rate as assumed, but also a signal arising from the change in the osmotic concentration (Fig 1a). The predicted osmotic concentration of the phloem typically increased during the afternoon due to the loading of photosynthesized sugars to the phloem. Inner bark osmotic concentration followed the photosynthesis rate with a 3 and 4 hour time-lag at the top and base, respectively (Fig 1b). The connection between photosynthesis and the predicted change in phloem osmotic concentration was stronger in the upper part of the tree compared to lower part. The changes in the predicted osmotic concentration were not similar every day, indicating that

  15. Evaluation of Helium Purge & Vent Process to Reduce Hydrogen Concentrations in the Large Diameter Container & Cask Void Volumes at T Plant

    SciTech Connect

    PACKER, M.J.

    2002-10-15

    The purpose of this document is to provide calculations for two primary activities: (1) Model a Helium Purge/Vent Cycle Process to reduce hydrogen gas concentration (i.e., H{sub 2} mole fraction) to a required limit in the Cask and Large Diameter Container (LDC) void volumes prior to T-Plant Operations activities. (2) Predict a hydrogen generation rate within each sludge-contained LDC, after the T-Plant helium purge/vent process (aka Post Purge/Vent Cycle Duration) to determine the transient hydrogen concentration. The calculations will evaluate a helium purge process to reduce the hydrogen concentration in the void spaces of the LDC after receipt at T-Plant. During transport from K-Basins to T-Plant, the hydrogen concentration will increase but the low or absent oxygen concentration from the K-Basin helium purge/vent process will ensure a non-flammable event. Upon receipt at T-Plant, the increased hydrogen concentration will require a process reduction (i.e., helium purge/vent cycling) prior to removing the Cask lid, otherwise, the removed lid permits air ingress and associated oxygen with the assumed high hydrogen concentration. In addition, once the Cask lid is removed at T-Plant, and the LDC is moved to the process cell, two threaded caps must be removed from the LDC to allow the escape of hydrogen during long-term storage. It is essential that the T-Plant helium purge/vent system reduces the hydrogen in both the Cask and LDC void volumes below the required limit. The calculations will also aide in predicting actual hydrogen generation rates and concentrations in each of the void volumes after the helium purge/vent cycle process is completed. Transient hydrogen plots or figures will be provided to help achieve this objective.

  16. Speciated fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid concentrations in southern California

    SciTech Connect

    Taylor, C.A. Jr.; Stover, C.A.; Westerdahl, F.D.

    1998-12-31

    A fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid sampling network has been in operation among 12 communities in southern California since late 1993. The data from this network consists of concentrations of particulate matter <10 {micro}m in aerodynamic diameter (PM10), nitrogen dioxide, ozone, vapor-phase hydrochloric, nitric, acetic, and formic acids, particulate matter <2.5 {micro}m in aerodynamic diameter (PM2.5), and the chloride, nitrate, sulfate, and ammonium components of PM2.5. These measurements are the basis of the exposure assessment estimates of the Children`s Health Study, a multi-year study, mainly of lung function development and respiratory illness, taking place in southern California. One of the goals of the Children`s Health Study is to utilize a cost-effective means of obtaining continuous fine-particle and vapor-phase acid data for a multi-year study with enough time resolution to allow seasonal estimates of exposure. A two-week sampler was developed to meet these needs. Four continuous years of vapor-phase acid and PM2.5 mass, chloride, nitrate, sulfate, and ammonium data have been collected. During this time, the sampler has proven to be reliable. A decline in PM2.5 mass, nitrate, and ammonium ions in most of the communities from 1994 to 1997 was observed. In contrast, very little change in vapor-phase acids was observed. There has been increased interest at the national level in fine particles and their characteristics. The network provides a rich database that can be used to characterize southern California communities on the basis of their level of fine particles (and their components) and vapor-phase acids and should prove valuable with respect to both prospective and retrospective health studies. The database also provides a general characterization of the levels of PM2.5 affecting 25 million people in southern California.

  17. Double diameter boring tool

    DOEpatents

    Ashbaugh, F.A.; Murry, K.R.

    1986-02-10

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting flutes formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first flute tip to the axis of rotation plus the distance from the second flute tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second flute tip to the axis of rotation minus one-half the distance from the first flute tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  18. Double diameter boring tool

    DOEpatents

    Ashbaugh, Fred N.; Murry, Kenneth R.

    1988-12-27

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  19. Small diameter carbon nanopipettes

    NASA Astrophysics Data System (ADS)

    Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

    2010-01-01

    Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 °C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 °C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

  20. Effects of Bale Diameter, Storage Location, and Sampling Depth on the Nutritive Value, Ruminal Disappearance Kinetics of DM, and Concentrations of Ergovaline for Endophyte-Infected Tall Fescue Hay Packaged in Large Round Bale

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During 2004, endophyte-infected tall fescue (Festuca arundinacea Schreb.) was packaged in large-round bales made at three diameters in Fayetteville (1.11, 1.35, or 1.59 m) and Batesville (1.14, 1.39, or 1.67 m), and then stored over winter either inside or outside on wooden pallets. Bales were then ...

  1. Evaluation of pulsatility index and diameter of the jugular vein and superficial body temperature as physiological indices of temperament in weaned beef calves: relationship with serum cortisol concentrations, rectal temp..

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relationship between temperament, pulsatility index and diameter of the jugular vein, and body temperature was assessed in Angus crossbred calves (262±24.9 days old). Temperament scores were used to classify calves as calm (n=31), intermediate (n=32), or temperamental (n=28). Blood samples were ...

  2. The DIAMET campaign

    NASA Astrophysics Data System (ADS)

    Vaughan, G.

    2012-04-01

    DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) is a joint project between the UK academic community and the Met Office. Its focus is on understanding and predicting mesoscale structures in synoptic-scale storms, and in particular on the role of diabatic processes in generating and maintaining them. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. The project conducted two field campaigns in the autumn of 2011, from September 14 - 30 and November 24 - December 14, based around the FAAM BAe146 aircraft with support from ground-based radar and radiosonde measurements. Detailed modelling, mainly using the Met Office Unified model, supported the planning and interpretation of these campaigns. This presentation will give a brief overview of the campaigns. Both in September and November-December the weather regime was westerly, with a strong jet stream directed across the Atlantic. Three IOPs were conducted in September, to observe a convective band ahead of an upper-level trough, waves on a long trailing cold front, and a warm conveyor belt associated with a secondary cyclone. In November-December six IOPs were conducted, to observe frontal passages and high winds. This period was notable for a number of very strong windstorms passing across the north of the UK, and gave us an opportunity to examine bent-back warm fronts in the southern quadrant of these storms where the strongest winds are found. The case studies fell into two basic patterns. In the majority of cases, dropsonde legs at high level were used to obtain a cross-section of winds and thermodynamic structure (e.g. across a front), followed by in situ legs at lower levels (generally where the temperature was between 0 and -10°) to examine microphysical processes, especially ice multiplication and the extent of supercooled water

  3. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  4. Wheel Diameter and Speedometer Reading

    ERIC Educational Resources Information Center

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  5. Measuring Diameters Of Large Vessels

    NASA Technical Reports Server (NTRS)

    Currie, James R.; Kissel, Ralph R.; Oliver, Charles E.; Smith, Earnest C.; Redmon, John W., Sr.; Wallace, Charles C.; Swanson, Charles P.

    1990-01-01

    Computerized apparatus produces accurate results quickly. Apparatus measures diameter of tank or other large cylindrical vessel, without prior knowledge of exact location of cylindrical axis. Produces plot of inner circumference, estimate of true center of vessel, data on radius, diameter of best-fit circle, and negative and positive deviations of radius from circle at closely spaced points on circumference. Eliminates need for time-consuming and error-prone manual measurements.

  6. Wheel Diameter and Speedometer Reading

    NASA Astrophysics Data System (ADS)

    Murray, Clifton

    2010-09-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it makes a good illustration of how reasoning in physics can lead to a result that is useful outside the classroom.

  7. Stellar diameters and temperatures. IV. Predicting stellar angular diameters

    SciTech Connect

    Boyajian, Tabetha S.; Van Belle, Gerard; Von Braun, Kaspar

    2014-03-01

    The number of stellar angular diameter measurements has greatly increased over the past few years due to innovations and developments in the field of long baseline optical interferometry. We use a collection of high-precision angular diameter measurements for nearby, main-sequence stars to develop empirical relations that allow the prediction of stellar angular sizes as a function of observed photometric color. These relations are presented for a combination of 48 broadband color indices. We empirically show for the first time a dependence on metallicity of these relations using Johnson (B – V) and Sloan (g – r) colors. Our relations are capable of predicting diameters with a random error of less than 5% and represent the most robust and empirical determinations of stellar angular sizes to date.

  8. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  9. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  10. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  11. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  12. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  13. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  14. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  15. Understanding the effect of carbon status on stem diameter variations

    PubMed Central

    De Swaef, Tom; Driever, Steven M.; Van Meulebroek, Lieven; Vanhaecke, Lynn; Marcelis, Leo F. M.; Steppe, Kathy

    2013-01-01

    Background Carbon assimilation and leaf-to-fruit sugar transport are, along with plant water status, the driving mechanisms for fruit growth. An integrated comprehension of the plant water and carbon relationships is therefore essential to better understand water and dry matter accumulation. Variations in stem diameter result from an integrated response to plant water and carbon status and are as such a valuable source of information. Methods A mechanistic water flow and storage model was used to relate variations in stem diameter to phloem sugar loading and sugar concentration dynamics in tomato. The simulation results were compared with an independent model, simulating phloem sucrose loading at the leaf level based on photosynthesis and sugar metabolism kinetics and enabled a mechanistic interpretation of the ‘one common assimilate pool’ concept for tomato. Key Results Combining stem diameter variation measurements and mechanistic modelling allowed us to distinguish instantaneous dynamics in the plant water relations and gradual variations in plant carbon status. Additionally, the model combined with stem diameter measurements enabled prediction of dynamic variables which are difficult to measure in a continuous and non-destructive way, such as xylem water potential and phloem hydrostatic potential. Finally, dynamics in phloem sugar loading and sugar concentration were distilled from stem diameter variations. Conclusions Stem diameter variations, when used in mechanistic models, have great potential to continuously monitor and interpret plant water and carbon relations under natural growing conditions. PMID:23186836

  16. 7 CFR 51.2656 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry....

  17. Diameter-dependent solubility of single-walled carbon nanotubes.

    PubMed

    Duque, Juan G; Parra-Vasquez, A Nicholas G; Behabtu, Natnael; Green, Micah J; Higginbotham, Amanda L; Price, B Katherine; Leonard, Ashley D; Schmidt, Howard K; Lounis, Brahim; Tour, James M; Doorn, Stephen K; Cognet, Laurent; Pasquali, Matteo

    2010-06-22

    We study the solubility and dispersibility of as-produced and purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions of the HiPco process are found to lead to significant differences in the respective SWNT solubilities in oleum and surfactant suspensions. The diameter distributions of SWNTs dispersed in surfactant solutions are batch-dependent, as evidenced by luminescence and Raman spectroscopies, but are identical for metallic and semiconducting SWNTs within a batch. We thus find that small diameter SWNTs disperse at higher concentration in aqueous surfactants and dissolve at higher concentration in oleum than do large-diameter SWNTs. These results highlight the importance of controlling SWNT synthesis methods in order to optimize processes dependent on solubility, including macroscopic processing such as fiber spinning, material reinforcement, and films production, as well as for fundamental research in type selective chemistry, optoelectronics, and nanophotonics. PMID:20521799

  18. MWD tool for deep, small diameter boreholes

    SciTech Connect

    Buytaert, J.P.R.; Duckworth, A.

    1992-03-17

    This patent describes an apparatus for measuring a drilling parameters while drilling a borehole in an earth formation, wherein the borehole includes a small diameter deep borehole portion and a large diameter upper borehole portion. It includes small diameter drillstring means for drilling the deep borehole portion; sensor means, disposed within the small diameter drillstring means, for measuring a drilling parameter characteristic of the deep portion of the borehole while drilling the deep portion of the borehole and for providing sensor output signals indicative of the measured parameter; an upper drillstring portion extending between the surface of the formation and the small diameter drillstring means, the upper drillstring portion including a large diameter drillstring portion; data transmission means disposed within the large diameter drillstring portion and responsive to the sensor output.

  19. Effect of Diethylenetriamine and Triethylamine sensitization on the critical diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Jiang, J.; Choong, K. H.; Lee, J. H. S.

    2000-04-01

    In this work, the critical diameter for detonation was measured for Nitromethane (NM) sensitized with two different amines: Diethylenetriamine (DETA) and Triethylamine (TEA). The critical diameter in glass and polyvinylchloride tubes is found to decrease rapidly as the amount of sensitizer is increased, then increase past a critical amount of sensitizer. Thus the critical diameter reaches a minimum at a critical concentration of sensitizer. It was also found that the critical diameter is lower with DETA than with TEA.

  20. Graft Diameter matters in Hamstring ACL reconstruction

    PubMed Central

    Clatworthy, Mark

    2016-01-01

    Objective: Recently techniques have been developed to increase graft diameter in hamstring ACL reconstruction with the hope to decrease graft failure. To date there is limited evidence to show that a smaller graft diameter results in a higher ACL failure rate. Method: The factors for failure in 1480 consecutive single surgeon hamstring ACL reconstructions were evaluated prospectively. Patients were followed for 2-15 years. A multivariate analysis was performed which looked at graft size, age, sex, time to surgery, meniscal integrity, meniscal repair and ACL graft placement to determine whether graft diameter matters in determining the failure of hamstring ACL reconstruction. Results: Graft diameters ranged from 6-10 mm. The mean graft diameter for all patients was 7.75 mm. 83 ACL reconstructions failed. The mean size of graft failures was 7.55 mm ACL reconstructions that failed had a significantly smaller hamstring graft diameter p=0.001. The Hazard Ratio for a smaller diameter graft is 0.517 p=<0.0001. For every 1 mm decrease in graft diameter there is a 48.3% higher chance of failure. The multivariate analysis showed a hazard ratio of 0.543 p=0.002. For every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure. Conclusion: Smaller diameter hamstring grafts do have a higher failure rate. Grafts ≤ 7.5 mm had twice the failure rate of grafts ≥8 mm using a multivariate analysis for every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure.

  1. Shrinking plastic tubing and nonstandard diameters

    NASA Technical Reports Server (NTRS)

    Ruiz, W. V.; Thatcher, C. S.

    1980-01-01

    Process allows larger-than-normal postshrink diameters without splitting. Tetrafluoroethylene tubing on mandrel is supported within hot steel pipe by several small diameter coil sections. Rising temperature of mandrel is measured via thermocouple so assembly can be removed without overshrinking (and splitting) of tubing.

  2. Photoacoustic determination of blood vessel diameter

    NASA Astrophysics Data System (ADS)

    Kolkman, Roy G. M.; Klaessens, John H. G. M.; Hondebrink, Erwin; Hopman, Jeroen C. W.; de Mul, Frits F. M.; Steenbergen, Wiendelt; Thijssen, Johan M.; van Leeuwen, Ton G.

    2004-10-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tgrpp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that the diameter could be approximated by 2ctgrpp, with c the speed of sound in blood. Using this relation, the lateral diameter could also precisely be determined. In vivo imaging and monitoring of changes in vessel diameters was feasible. Finally, acoustic time traces were recorded while flushing a vessel in the rabbit ear with saline, which proved that the main contribution to the laser-induced pressure transient is caused by blood inside the vessel and that the vessel wall gives only a minor contribution.

  3. Measurement of shaft diameters by machine vision.

    PubMed

    Wei, Guang; Tan, Qingchang

    2011-07-01

    A machine vision method for accurately measuring the diameters of cylindrical shafts is presented. Perspective projection and the geometrical features of cylindrical shafts are modeled in order to enable accurate measurement of shaft diameters. Some of the model parameters are determined using a shaft of known diameter. The camera model itself includes radial and tangential distortions terms. Experiments were used to measure the accuracy of the proposed method and the effect of the position of the camera relative to the shaft, as well as other factors. PMID:21743525

  4. Growth of nanostructures with controlled diameter

    DOEpatents

    Pfefferle, Lisa; Haller, Gary; Ciuparu, Dragos

    2009-02-03

    Transition metal-substituted MCM-41 framework structures with a high degree of structural order and a narrow pore diameter distribution were reproducibly synthesized by a hydrothermal method using a surfactant and an anti-foaming agent. The pore size and the mesoporous volume depend linearly on the surfactant chain length. The transition metals, such as cobalt, are incorporated substitutionally and highly dispersed in the silica framework. Single wall carbon nanotubes with a narrow diameter distribution that correlates with the pore diameter of the catalytic framework structure were prepared by a Boudouard reaction. Nanostructures with a specified diameter or cross-sectional area can therefore be predictably prepared by selecting a suitable pore size of the framework structure.

  5. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

    1992-08-11

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

  6. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, Eldon D.; Hooper, Frederick M.; Reichenbach, Marvin L.

    1992-01-01

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

  7. Making Jointless Dual-Diameter Tubes

    NASA Technical Reports Server (NTRS)

    Kirkham, Kathleen E.

    1989-01-01

    Welds between sections having different diameters eliminated. Single tube made with integral tapered transition section between straight sections of different diameters and wall thicknesses. Made from single piece; contains no joints, welded or otherwise. Not prone to such weld defects as voids and need not be inspected for them. Tube fabricated by either of two methods: drawing or reduction. Both methods used to fabricate tubes of 316L corrosion-resistant stainless steel for use as heat-exchanger coil.

  8. Ultra-efficient Engine Diameter Study

    NASA Technical Reports Server (NTRS)

    Daggett, David L.; Brown, Stephen T.; Kawai, Ron T.

    2003-01-01

    Engine fan diameter and Bypass Ratio (BPR) optimization studies have been conducted since the beginning of the turbofan age with the recognition that reducing the engine core jet velocity and increasing fan mass flow rate generally increases propulsive efficiency. However, performance tradeoffs limit the amount of fan flow achievable without reducing airplane efficiency. This study identifies the optimum engine fan diameter and BPR, given the advanced Ultra-Efficient Engine Technology (UEET) powerplant efficiencies, for use on an advanced subsonic airframe. Engine diameter studies have historically focused on specific engine size options, and were limited by existing technology and transportation infrastructure (e.g., ability to fit bare engines through aircraft doors and into cargo holds). This study is unique in defining the optimum fan diameter and drivers for future 2015 (UEET) powerplants while not limiting engine fan diameter by external constraints. This report follows on to a study identifying the system integration issues of UEET engines. This Engine Diameter study was managed by Boeing Phantom Works, Seattle, Washington through the NASA Glenn Revolutionary Aero Space Engine Research (RASER) contract under task order 10. Boeing Phantom Works, Huntington Beach, completed the engine/airplane sizing optimization, while the Boeing Commercial Airplane group (BCA) provided design oversight. A separate subcontract to support the overall project was issued to Tuskegee University.

  9. DiameterJ: A validated open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-08-01

    Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called "DiameterJ" was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response. PMID:26043061

  10. Submicron diameter single crystal sapphire optical fiber

    SciTech Connect

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers is the first step in achieving optical and sensing performance on par with its fused silica counterpart.

  11. Large diameter astromast development, phase 1

    NASA Technical Reports Server (NTRS)

    Preiswerk, P. R.; Finley, L. A.; Knapp, K.

    1983-01-01

    Coilable-longeron lattice columns called Astromasts (trademark) were manufactured for a variety of spacecraft missions. These flight structures varied in diameter from 0.2 to 0.5 meter (9 to 19 in.), and the longest Astromast of this type deploys to a length of 30 meters (100 feet). A double-laced diagonal Astromast design referred to as the Supermast (trademark) which, because it has shorter baylengths than an Astromast, is approximately four times as strong. The longeron cross section and composite material selection for these structures are limited by the maximum strain associated with stowage and deployment. As a result, future requirements for deployable columns with high stiffness and strength require the development of both structures in larger diameters. The design, development, and manufacture of a 6.1-m-long (20-ft), 0.75-m-diameter (30-in.), double-laced diagonal version of the Astromast is described.

  12. Submicron diameter single crystal sapphire optical fiber

    DOE PAGESBeta

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  13. Videodensitometry for measuring blood vessel diameter.

    PubMed

    Hoornstra, K; Hanselman, J M; Holland, W P; De Wey Peters, G W; Zwamborn, A W

    1980-01-01

    A method employing a special computer for determining the internal diameters of blood vessels from photofluorographic image is described; in vitro and in vivo experiments are performed with the system. The amount of contrast medium injected is restricted to 4 times 3 ml, and it is possible to determine the diameter (in the range from 2 to 16 mm) at any place where blood vessels can be catheterized. In the in vivo experiments the maximum systematic error is +/-5 percent in the 7 to 8 mm range. PMID:7424549

  14. THERMAL EVALUATION OF DIFFERENT DRIFT DIAMETER SIZES

    SciTech Connect

    H.M. Wade

    1999-01-04

    The purpose of this calculation is to estimate the thermal response of a repository-emplaced waste package and its corresponding drift wall surface temperature with different drift diameters. The case examined is that of a 21 pressurized water reactor (PWR) uncanistered fuel (UCF) waste package loaded with design basis spent nuclear fuel assemblies. This calculation evaluates a 3.5 meter to 6.5 meter drift diameter range in increments of 1.0 meters. The time-dependent temperatures of interest, as determined by this calculation, are the spent nuclear fuel cladding temperature, the waste package surface temperature, and the drift wall surface temperature.

  15. Shaft Diameter Measurement Using Structured Light Vision

    PubMed Central

    Liu, Siyuan; Tan, Qingchang; Zhang, Yachao

    2015-01-01

    A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is measured by the determined center and the projected image. Experiments evaluated the measuring accuracy of the method and the effects of some factors on the measurement are analyzed. PMID:26274963

  16. Optical receivers with large-diameter photodiode

    NASA Astrophysics Data System (ADS)

    Swoboda, Robert; Schneider, Kerstin; Zimmermann, Horst

    2006-04-01

    This work presents two types of optical receivers with large-diameter photodiodes. Both are optoelectronic integrated circuits (OEICs) realized in 0.6μm BiCMOS Si technology integrating PIN photodiode, transimpedance amplifier (TIA) and output circuit on chip. The two circuits are an optocoupler with a photodiode diameter of 780μm and a rise- and falltime of 5ns and 4.9ns respectively at 850nm light and a plastic optical fiber (POF) receiver with a photodiode diameter of 500μm and upper -3dB cut-off frequencies of 165MHz at 660nm light and 148MHz at 850nm light. The measured rise- and falltime of the POF receiver was 1.78ns and 2.45ns at 660nm light and 1.94ns and 2.5ns at 850ns, respectively. The presented results combine the advantage of easier handling of large-diameter photodiode receivers and high performance.

  17. Changing the Diameter of a Viewing Tube

    ERIC Educational Resources Information Center

    Obara, Samuel

    2009-01-01

    This article is about the students' investigation about the relationship between the diameter of the view tubes (x) of constant lengths and the viewable vertical distance (y) on the wall while keeping the perpendicular distance from the eyeball to the wall constant. The students collected data and used and represented it in tabular and graphical…

  18. Small diameter symmetric networks from linear groups

    NASA Technical Reports Server (NTRS)

    Campbell, Lowell; Carlsson, Gunnar E.; Dinneen, Michael J.; Faber, Vance; Fellows, Michael R.; Langston, Michael A.; Moore, James W.; Multihaupt, Andrew P.; Sexton, Harlan B.

    1992-01-01

    In this note is reported a collection of constructions of symmetric networks that provide the largest known values for the number of nodes that can be placed in a network of a given degree and diameter. Some of the constructions are in the range of current potential engineering significance. The constructions are Cayley graphs of linear groups obtained by experimental computation.

  19. Reducing the diameters of computer networks

    NASA Technical Reports Server (NTRS)

    Bokhari, S. H.; Raza, A. D.

    1986-01-01

    Three methods of reducing the diameters of computer networks by adding additional processor to processor links under the constraint that no more than one I/O port be added to each processor are discussed. This is equivalent to adding edges to a given graph under the constraint that the degree of any node be increased, at most, by one.

  20. Computing Minimum Diameter Color-Spanning Sets

    NASA Astrophysics Data System (ADS)

    Fleischer, Rudolf; Xu, Xiaoming

    We study the minimum diameter color-spanning set problem which has recently drawn some attention in the database community. We show that the problem can be solved in polynomial time for L 1 and L ∞ metrics, while it is NP-hard for all other L p metrics even in two dimensions. However, we can efficiently compute a constant factor approximation.

  1. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined...

  2. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  3. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  4. Diameter-selective non-covalent functionalization of carbon nanotubes with porphyrin monomers

    NASA Astrophysics Data System (ADS)

    Vialla, F.; Delport, G.; Chassagneux, Y.; Roussignol, Ph.; Lauret, J. S.; Voisin, C.

    2016-01-01

    We report on the spontaneous non-covalent functionalization of carbon nanotubes with hydrophobic porphyrin molecules in micellar aqueous solution. By monitoring the species concentrations with optical spectroscopies, we can follow the kinetics of the reaction and study its thermodynamical equilibrium as a function of the reagent concentrations. We show that the reaction is well accounted for by a cooperative Hill equation, reaching a molecular coverage close to a compact monolayer for a porphyrin concentration larger than a diameter-specific threshold concentration. The equilibrium constant is measured for 16 nanotube chiral species. The Gibbs energy of the reaction (of the order of -40 kJ mol-1) and its evolution with the nanotube diameter is consistent with theoretical calculations of the binding energy. This thermodynamical study shows a strong preferential binding of TPP molecules to larger diameter nanotubes. This original curvature selectivity can be used to induce diameter selective species enrichment.We report on the spontaneous non-covalent functionalization of carbon nanotubes with hydrophobic porphyrin molecules in micellar aqueous solution. By monitoring the species concentrations with optical spectroscopies, we can follow the kinetics of the reaction and study its thermodynamical equilibrium as a function of the reagent concentrations. We show that the reaction is well accounted for by a cooperative Hill equation, reaching a molecular coverage close to a compact monolayer for a porphyrin concentration larger than a diameter-specific threshold concentration. The equilibrium constant is measured for 16 nanotube chiral species. The Gibbs energy of the reaction (of the order of -40 kJ mol-1) and its evolution with the nanotube diameter is consistent with theoretical calculations of the binding energy. This thermodynamical study shows a strong preferential binding of TPP molecules to larger diameter nanotubes. This original curvature selectivity can be used

  5. Coke from small-diameter tubes analyzed

    SciTech Connect

    Albright, L.F.

    1988-08-29

    The mechanism for coke deposit formation and the nature of the coke itself can vary with the design of the ethylene furnace tube bank. In this article, coke deposits from furnaces with small-diameter pyrolysis tubes are examined. The samples were taken from four furnaces of identical design (Plant B). As in both the first and second installments of the series, the coke deposits were examined using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDAX). The deposits from the small-diameter tubes are compared with the coke deposits from the furnace discussed in earlier articles. Analysis of the coke in both sets of samples are then used to offer recommendations for improved decoking procedures, operating procedures, better feed selection, and better selection of the metallurgy used in furnace tubes, to extend the operating time of the furnace tubes by reducing the amount and type of coke build up.

  6. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, David E.; Petrini, Richard R.; Carter, Gary W.

    1981-01-01

    An improved rod optic system for inspecting small diameter, deep bores. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90.degree. to minimize optical distortion in examining the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable of examining 1/16 inch diameter and up to 4 inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and right angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  7. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, D.E.; Petrini, R.R.; Carter, G.W.

    An improved rod optic system for inspecting small diameter, deep bores is described. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90/sup 0/ to minimize optical distortion in examing the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable if examing 1/16 inch diameter and up to 4-inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and righ angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  8. European Projects of Solar Diameter Monitoring

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Bianda, Michele; Arnaud, Jean

    2008-10-01

    Three projects dealing with solar diameter evolution are presently in development. Historical and contemporary eclipses and planetary transits data collection and analysis, to cover potentially the last 5 centuries with an accuracy of few hundreds of arcsecond on diameter's measurements. The French space mission PICARD with a few milliarcseconds accuray. With PICARD-SOL instruments located at the plateau of Calern the role of the atmosphere in ground-based measurements will be clarified. CLAVIUS is a Swiss-Italian project based on drift-scan method, free from optical distortions, where hourly circles transits will be monitored with fast CMOS sensors in different wavebands. The will run at IRSOL Gregory-Coudé telescope.

  9. On finding minimum-diameter clique trees

    SciTech Connect

    Blair, J.R.S. . Dept. of Computer Science); Peyton, B.W. )

    1991-08-01

    It is well-known that any chordal graph can be represented as a clique tree (acyclic hypergraph, join tree). Since some chordal graphs have many distinct clique tree representations, it is interesting to consider which one is most desirable under various circumstances. A clique tree of minimum diameter (or height) is sometimes a natural candidate when choosing clique trees to be processed in a parallel computing environment. This paper introduces a linear time algorithm for computing a minimum-diameter clique tree. The new algorithm is an analogue of the natural greedy algorithm for rooting an ordinary tree in order to minimize its height. It has potential application in the development of parallel algorithms for both knowledge-based systems and the solution of sparse linear systems of equations. 31 refs., 7 figs.

  10. Lasing in microdisks of ultrasmall diameter

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Bogdanov, A. A.; Shostak, I. I.; Moiseev, E. I.; Karpov, D. V.; Laukkanen, J.; Tommila, J.

    2014-12-15

    It is demonstrated by calculations and experimental results that room-temperature lasing can be obtained at the ground-state optical transition of InAs/InGaAs/GaAs quantum dots in optical microcavities with a record-small diameter of 1.5 μm. In 1-μm cavities, lasing occurs at the wavelength of one of the whispering-gallery modes within the band corresponding to the first excited-state optical transition.

  11. Diameter-dependent hydrophobicity in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kyakuno, Haruka; Fukasawa, Mamoru; Ichimura, Ryota; Matsuda, Kazuyuki; Nakai, Yusuke; Miyata, Yasumitsu; Saito, Takeshi; Maniwa, Yutaka

    2016-08-01

    Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature Twd ≈ 220-230 K and above a critical diameter Dc ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry. It is found that water molecules inside thick SWCNTs (D > Dc) evaporate and condense into ice Ih outside the SWCNTs at Twd upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below Twd freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < Dc) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.

  12. Calibration of area based diameter distribution with individual tree based diameter estimates using airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Xu, Qing; Hou, Zhengyang; Maltamo, Matti; Tokola, Timo

    2014-07-01

    Diameter distribution is essential for calculating stem volume and timber assortments of forest stands. A new method was proposed in this study to improve the estimation of stem volume and timber assortments, by means of combining the Area-based approach (ABA) and individual tree detection (ITD), the two main approaches to deriving forest attributes from airborne laser scanning (ALS) data. Two methods, replacement, and histogram matching were employed to calibrate ABA-derived diameter distributions with ITD-derived diameter estimates at plot level. The results showed that more accurate estimates were obtained when calibrations were applied. In view of the highest accuracy between ABA and ITD, calibrated diameter distributions decreased its relative RMSE of the estimated entire growing stock, saw log and pulpwood fractions by 2.81%, 3.05% and 7.73% points at best, respectively. Calibration improved pulpwood fraction significantly, which contributed to the negligible bias of the estimated entire growing stock.

  13. Diameter prediction mathematical models for xanthan gum-alginate capsules produced by extrusion-dripping method

    NASA Astrophysics Data System (ADS)

    Ong, Hui-Yen; Lee, Boon-Beng; Zakaria, Zarina; Chan, Eng-Seng

    2015-05-01

    The aim of this work is to compare the applicability of particle diameter prediction mathematical models (i.e. Tate's Law equation, the modified Tate's Law equation, the modified Yildirim's model) to determine diameter of liquid core capsules. The capsules were produced by extruding xanthan gum-calcium chloride solution through a hypodermic needle into sodium alginate solution. The effects of two types of xanthan gum with different concentrations and needle diameters on capsule diameter were investigated in this work. The results showed that there was no significant difference in capsule diameter despite different types and concentrations of xanthan gum were used. However, the diameter of the capsules increased when the diameter of needles increased. As a whole, the produced capsules were in the range of 3.47 mm to 4.86 mm. Among the three studied prediction models, the modified Tate's Law mathematical equation was the most suitable model for the diameter prediction of the liquid core capsules with AAD of 2.74% and MAD of 6.55%.

  14. Variable diameter wind turbine rotor blades

    DOEpatents

    Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.

    2005-12-06

    A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

  15. Stellar Angular Diameter Relations for Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Adams, Arthur; Boyajian, Tabetha S.; von Braun, Kaspar

    2016-01-01

    Determining the physical properties of microlensing events depends on having accurate angular radii of the source star. Using long-baseline optical interferometry we are able to determine the angular sizes of nearby stars with uncertainties less than 2 percent. We present empirical estimates of angular diameters for both dwarfs/subgiants and giant stars as functions of five color indices which are relevant to planned microlensing surveys. We find in all considered colors that metallicity does not play a statistically significant role in predicting stellar size for the samples of stars considered.

  16. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  17. A Variable Diameter Short Haul Civil Tiltrotor

    NASA Technical Reports Server (NTRS)

    Wang, James M.; Jones, Christopher T.; Nixon, Mark W.

    1999-01-01

    The Short-Haul-Civil-tiltrotor (SHCT) component of the NASA Aviation System Capacity Program is an effort to develop the technologies needed for a potential 40-passenger civil tiltrotor. The variable diameter tiltrotor (VDTR) is a Sikorsky concept aimed at improving tiltrotor hover and cruise performance currently limited by disk loading that is much higher in hover than conventional helicopter, and much lower in cruise than turbo-prop systems. This paper describes the technical merits of using a VDTR on a SHCT aircraft. The focus will be the rotor design.

  18. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, Albert L.

    1985-01-01

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade.

  19. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, A.L.

    1985-11-19

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts is disclosed. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade. 2 figs.

  20. The diameter and albedo of 1943 Anteros

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Tedesco, E. F.; Tholen, D. J.; Tokunaga, A.; Matthews, K.; Neugebauer, G.; Soifer, B. T.; Kowal, C.

    1981-01-01

    The results of broadband visual and infrared photometry of the Apollo-Amor asteroid 1943 Anteros during its 1980 apparition are reported. By means of a radiometric model, a diameter of 2.3 + or - 0.2 km and a visual geometric albedo of 0.13 + or - 0.03 is calculated. The albedo and reflectance spectrum of Anteros imply that it is a type S asteroid. Thus, Anteros may have a silicate surface similar to other Apollo-Amor asteroids as well as some stony-iron meteorites.

  1. Polymer scaffolds for small-diameter vascular tissue engineering.

    PubMed

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2010-09-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  2. Polymer scaffolds for small-diameter vascular tissue engineering

    PubMed Central

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2014-01-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  3. Measurement of Diameter Changes during Irradiation Testing

    SciTech Connect

    Davis, K. L.; Knudson, D. L.; Crepeau, J. C.; Solstad, S.

    2015-03-01

    New materials are being considered for fuel, cladding, and structures in advanced and existing nuclear reactors. Such materials can experience significant dimensional and physical changes during irradiation. Currently in the US, such changes are measured by repeatedly irradiating a specimen for a specified period of time and then removing it from the reactor for evaluation. The time and labor to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data and handling may disturb the phenomena of interest. In-pile detection of changes in geometry is sorely needed to understand real-time behavior during irradiation testing of fuels and materials in high flux US Material and Test Reactors (MTRs). This paper presents development results of an advanced Linear Variable Differential Transformer-based test rig capable of detecting real-time changes in diameter of fuel rods or material samples during irradiation in US MTRs. This test rig is being developed at the Idaho National Laboratory and will provide experimenters with a unique capability to measure diameter changes associated with fuel and cladding swelling, pellet-clad interaction, and crud buildup.

  4. Diameter control of single wall carbon nanotubes synthesized using chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Roy, Soumyendu; Bajpai, Reeti; Soin, Navneet; Roy, Susanta Sinha; McLaughlin, James A.; Misra, D. S.

    2014-12-01

    Lack of control on the chirality or diameter of single-wall carbon nanotubes (SWCNTs) during synthesis is a major impediment in the path of their widespread commercialization. We demonstrate that the humble technique of catalytic chemical vapor deposition of methane, without any sophisticated catalyst preparation, can provide significant control on the diameter of the synthesized SWCNTs. The catalyst used is a solid solution of the bimetals Fe-Mo or Co-Mo in MgO. The radial breathing modes (RBMs) in the Raman spectra of SWCNTs were used to find out the diameters. Kataura plot along with RBMs was used to study the chirality of the tubes. High concentration of the catalysts (Co:Mo:MgO = 1:0.5:15 and Fe:Mo:MgO = 1:0.5:30) resulted in high yields. However, most of these carbonaceous materials were impurities. Reducing the concentration not only improved the purity and crystallinity (ID/IG ratio ∼0.1), but most importantly reduced the diameter spread of the SWCNTs. Majority of the SWCNTs grown using the low concentration catalysts (Co:Mo:MgO = 1:0.5:300 and Fe:Mo:MgO = 1:0.5:200) were estimated to have diameters lying between 1.13 and 1.65 nm. This narrowing of diameter spread happened for both Fe and Co catalyst systems and depended only on the concentration of the catalyst.

  5. Thirty-centimeter-diameter ion milling source

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1978-01-01

    A 30-cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cu cm at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well-collimated beam having an average variation in current density of + or - 5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity.

  6. Five meter diameter conical furlable antenna

    NASA Technical Reports Server (NTRS)

    Fortenberry, J. W.; Freeland, R. E.; Moore, D. M.

    1976-01-01

    An investigation was made to demonstrate that a 5-meter-diameter, furlable, conical reflector antenna utilizing a line source feed can be fabricated utilizing composite materials and to prove that the antenna can function mechanically and electrically as prototype flight hardware. The design, analysis, and testing of the antenna are described. An RF efficiency of 55% at 8.5 GHz and a surface error of 0.64 mm rms were chosen as basic design requirements. Actual test measurements yielded an efficiency of 53% (49.77 dB gain) and a surface error of 0.61 mm rms. Atmospherically induced corrosion of the reflector mesh resulted in the RF performance degradation. An assessment of the antenna as compared to the current state of the art technology was made. This assessment included cost, surface accuracy and RF performance, structural and mechanical characteristics, and possible applications.

  7. Development of fine diameter mullite fiber

    NASA Technical Reports Server (NTRS)

    Long, W. G.

    1974-01-01

    Results are presented of a program to develop and evaluate mullite fiber with a mean diameter under two microns. The two micron fiber is produced by a blowing process at room temperature from a low viscosity (10-25 poise) solution. The blown fiber was evaluated for dimensional stability in thermal cycling to 1371 C, and was equivalent to the 5 micron spun B and W mullite fiber. An additive study was conducted to evaluate substitutes for the boron. Three levels of chromium, lithium fluoride, and magnesium were added to the standard composition in place of boron and the fiber produced was evaluated for chemical and dimensional stability in thermal cycling to 1371 C. The magnesium was the most chemically stable, but the chrome additive imparted the best dimensional stability.

  8. Fire protection covering for small diameter missiles

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Sawko, P. M. (Inventor)

    1979-01-01

    Flexible intumescent protection sheeting of unusually uniform thickness were prepared from epoxy-polysulfide compositions, containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced.

  9. Granulation, Irradiance and Diameter Solar Variations

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Reis Neto, Eugenio

    2015-08-01

    Though granulation forms the very face of sun’s photosphere, there are no long term registers of it. Observational and computational hardships to define and follow such highly variable “face” have so far prevented the realization of those registers. However, in recent years a large, coherent body of white light images became available. We retrieved white light, full solar disk images from the BBSO, to a total of 1104 treated ones and 1245 treated and compensated for limb darkening ones. The time coverage extends from the year 2000 to 2005, thus covering the rise and fall of the solar cycle 23. For the analysis, only the central 0.35R portion of the Sun was considered. The central portion was then divided into 100 subsectors, to average and discard the deviant results. The analysis goal is to derive the long term behavior of the photosphere granulation, in broad statistical sense. Three statistics were this way calculated: the standard deviation of the counts (that answers to the grains size); the counts difference between the maximum and minimum tenths (that answers to the grains brightness); the degree of the best fit polynomial along lines and columns (that answers to the grains numbers). According to the statistics, there is no significant variation in the number of grains. The grains sizes are the largest by the solar maximum, in excellent agreement with the maximum of the measured diameter. The grains brightness, on the contrary, is minimum at the solar maximum, and again an excellent agreement is verified with the maximum of the measured diameter.

  10. Influence Of Nanoparticles Diameter On Structural Properties Of Magnetic Fluid In Magnetic Field

    NASA Astrophysics Data System (ADS)

    Kúdelčík, Jozef; Bury, Peter; Hardoň, Štefan; Kopčanský, Peter; Timko, Milan

    2015-07-01

    The properties of magnetic fluids depend on the nanoparticle diameter, their concentration and the carrier liquid. The structural changes in magnetic fluids with different nanoparticle diameter based on transformer oils TECHNOL and MOGUL under the effect of a magnetic field and temperature were studied by acoustic spectroscopy. At a linear and jump changes of the magnetic field at various temperatures a continuous change was observed of acoustic attenuation caused by aggregation of the magnetic nanoparticles to structures. From the anisotropy of acoustic attenuation and using the Taketomi theory the basic parameters of the structures are calculated and the impact of nanoparticle diameters on the size of structures is confirmed.

  11. Tissue engineered small-diameter vascular grafts.

    PubMed

    Schmedlen, Rachael H; Elbjeirami, Wafa M; Gobin, Andrea S; West, Jennifer L

    2003-10-01

    Arterial occlusive disease remains the leading cause of death in western countries and often requires vascular reconstructive surgery. The limited supply of suitable small-diameter vascular grafts has led to the development of tissue engineered blood vessel substitutes. Many different approaches have been examined, including natural scaffolds containing one or more ECM proteins and degradable polymeric scaffolds. For optimal graft development, many efforts have modified the culture environment to enhance ECM synthesis and organization using bioreactors under physiologic conditions and biochemical supplements. In the past couple of decades, a great deal of progress on TEVGs has been made. Many challenges remain and are being addressed, particularly with regard to the prevention of thrombosis and the improvement of graft mechanical properties. To develop a patent TEVG that grossly resembles native tissue, required culture times in most studies exceed 8 weeks. Even with further advances in the field, TEVGs will likely not be used in emergency situations because of the time necessary to allow for cell expansion, ECM production and organization, and attainment of desired mechanical strength. Furthermore, TEVGs will probably require the use of autologous tissue to prevent an immunogenic response, unless advances in immune acceptance render allogenic and xenogenic tissue use feasible. TEVGs have not yet been subjected to clinical trials, which will determine the efficacy of such grafts in the long term. Finally, off-the-shelf availability and cost will become the biggest hurdles in the development of a feasible TEVG product. Although many obstacles exist in the effort to develop a small-diameter TEVG, the potential benefits of such an achievement are exciting. In the near future, a nonthrombogenic TEVG with sufficient mechanical strength may be developed for clinical trials. Such a graft will have the minimum characteristics of biological tissue necessary to remain patent

  12. Diameter Dependence of Planar Defects in InP Nanowires.

    PubMed

    Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y B; Ho, Johnny C

    2016-01-01

    In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications. PMID:27616584

  13. LED-based digital diameter measurement

    NASA Astrophysics Data System (ADS)

    Kleuver, Wolfram; Becker, Lothar

    1995-01-01

    This paper presents a new industrial sensor for measuring diameters of extreme thin objects. The system is divided in two parts. The first is the emitter and the second the receiver. It is possible to use this system for the automatic inspection of files and wires in the textile industries and wire works. Another application for the sensor is the control of production of chemical files in an extruder. Furthermore we can measure more than one object in the lightbeam because we get information not only about the dimensions also about the position of the objects in the beam. The innovation in this system is the using of a light emitting diode (LED) as emitter and the realization of a long distance of about two or more meters between the two sensorheads. The results of this development are a special kind of optical layout in the emitter to reduce the loss of intensity and minimize the divergence of the lightbeam. It is not necessary to develop an intensity distribution, which is equal over the complete width of the sensorhead. We can show that we have a better dynamic in the system with this feature. The experiments prove that we get the same resolution as a laserbeamsensor. Furthermore one advantage is the eye-safety.

  14. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  15. Large Circular Basin - 1300-km diameter

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Close-up view of one-half of a 1300-km diameter circular basin the largest observed on Mercury. The other half is hidden beyond the terminator to the left. Hills and valleys extend in a radial fashion outward from the main ring. Interior of the large basin is completely flooded by plains materials; adjacent lowlands are also partially flooded and superimposed on the plains are bowl shaped craters. Wrinkle ridges are abundant on the plains materials. The area shown is 1008 miles (1600 km) from the top to the bottom of the picture. Sun's illumination is from the right. Blurred linear lines extending across the picture near bottom are missing data lines that have been filled in by the computer. Mariner 10 encountered Mercury on Friday, March 29th, 1974, passing the planet on the darkside 431 miles (690-km) from the surface.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    NOTE: This image was scanned from physical media.

  16. Probability of DNA knotting and the effective diameter of the DNA double helix.

    PubMed Central

    Rybenkov, V V; Cozzarelli, N R; Vologodskii, A V

    1993-01-01

    During the random cyclization of long polymer chains, knots of different types are formed. We investigated experimentally the distribution of knot types produced by random cyclization of phage P4 DNA via its long cohesive ends. The simplest knots (trefoils) predominated, but more complex knots were also detected. The fraction of knots greatly diminished with decreasing solution Na+ concentration. By comparing these experimental results with computer simulations of knotting probability, we calculated the effective diameter of the DNA double helix. This important excluded-volume parameter is a measure of the electrostatic repulsion between segments of DNA molecules. The calculated effective DNA diameter is a sensitive function of electrolyte concentration and is several times larger than the geometric diameter in solutions of low monovalent cation concentration. Images Fig. 1 PMID:8506378

  17. Instability of Reference Diameter in the Evaluation of Stenosis After Coronary Angioplasty: Percent Diameter Stenosis Overestimates Dilative Effects Due to Reference Diameter Reduction

    SciTech Connect

    Hirami, Ryouichi; Iwasaki, Kohichiro; Kusachi, Shozo; Murakami, Takashi; Hina, Kazuyoshi; Matano, Shigeru; Murakami, Masaaki; Kita, Toshimasa; Sakakibara, Noburu; Tsuji, Takao

    2000-03-15

    Purpose: To examine changes in the reference segment luminal diameter after coronary angioplasty.Methods: Sixty-one patients with stable angina pectoris or old myocardial infarction were examined. Coronary angiograms were recorded before coronary angioplasty (pre-angioplasty) and immediately after (post-angioplasty), as well as 3 months after. Artery diameters were measured on cine-film using quantitative coronary angiographic analysis.Results: The diameters of the proximal segment not involved in the balloon inflation and segments in the other artery did not change significantly after angioplasty, but the reference segment diameter significantly decreased (4.7%). More than 10% luminal reduction was observed in seven patients (11%) and more than 5% reduction was observed in 25 patients (41%). More than 5% underestimation of the stenosis was observed in 22 patients (36%) when the post-angioplasty reference diameter was used as the reference diameter, compared with when the pre-angioplasty measurement was used and more than 10% underestimation was observed in five patients (8%).Conclusion: This study indicated that evaluation by percent diameter stenosis, with the reference diameter from immediately after angioplasty, overestimates the dilative effects of coronary angioplasty, and that it is thus better to evaluate the efficacy of angioplasty using the absolute diameter in addition to percent luminal stenosis.

  18. Limitations on the Optical Tunability of Small Diameter Gold Nanoshells

    PubMed Central

    Rasch, Michael R.; Sokolov, Konstantin V.; Korgel, Brian A.

    2009-01-01

    Gold (Au) nanoshells were grown on silica nanoparticles with differing average diameters, ranging from 30 nm to 120 nm. Au nanoshells were also formed on silica spheres encapsulating 5 nm diameter magnetic iron oxide nanocrystals. The optical absorbance spectra of these Au nanoshells are reported. The plasmon resonance wavelengths of the smaller diameter nanoshells were significantly less tunable than those of the larger diameter nanoshells. This is due to a reduced range of accessible core-shell ratio—the geometric factor that determines the plasmon peak position—as the silica core diameter shrinks. The smaller diameter nanoshells were also found to be highly prone to aggregation, which broadens the plasmon absorption peak. Model calculations of dispersion stability as a function of silica core diameter reveal that smaller diameter Au shells exhibit more aggregation because of the size-dependence of the electrostatic double-layer potential. PMID:19711913

  19. Nineteen-Foot Diameter Explosively Driven Blast Simulator

    SciTech Connect

    VIGIL,MANUEL G.

    2001-07-01

    This report describes the 19-foot diameter blast tunnel at Sandia National Laboratories. The blast tunnel configuration consists of a 6 foot diameter by 200 foot long shock tube, a 6 foot diameter to 19 foot diameter conical expansion section that is 40 feet long, and a 19 foot diameter test section that is 65 feet long. Therefore, the total blast tunnel length is 305 feet. The development of this 19-foot diameter blast tunnel is presented. The small scale research test results using 4 inch by 8 inch diameter and 2 foot by 6 foot diameter shock tube facilities are included. Analytically predicted parameters are compared to experimentally measured blast tunnel parameters in this report. The blast tunnel parameters include distance, time, static, overpressure, stagnation pressure, dynamic pressure, reflected pressure, shock Mach number, flow Mach number, shock velocity, flow velocity, impulse, flow duration, etc. Shadowgraphs of the shock wave are included for the three different size blast tunnels.

  20. Extrusion of small-diameter, thin-wall tungsten tubing

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P.; Gyorgak, C. A.

    1967-01-01

    Small-diameter, thin-wall seamless tubing of tungsten has been fabricated in lengths of up to 10 feet by hot extrusion over a floating mandrel. Extrusion of 0.50-inch-diameter tubing over 0.4-inch-diameter mandrels was accomplished at temperatures ranging from 3000 degrees to 4000 degrees F.

  1. Variation of pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures

    NASA Technical Reports Server (NTRS)

    Spakowski, Adolph, A; Belles, Frank E

    1952-01-01

    An investigation was made of the change in the pressure limits of flame propagation with tube diameter for various isooctane-oxygen-nitrogen mixtures. Pressure limits were measured in cylindrical glass tubes of four different inside diameters at six different oxygen-nitrogen ratios. Under the experimental conditions, flame propagation was found to be impossible in isooctane-oxygen mixtures with oxygen concentrations less than 11 to 12 percent. Critical tube diameters for flame propagation were calculated and the effect of pressure was determined and compared with the effect of pressure on quenching distance. Critical diameters were related to flame speeds for various isooctane-oxygen-nitrogen mixtures.

  2. Concentrator Systems

    NASA Astrophysics Data System (ADS)

    Luque-Heredia, Ignacio; Luque, Antonio

    2015-10-01

    The following sections are included: * Introduction * The early development of CPV * Concentrator solar cells * Optics for photovoltaic concentrators * Photovoltaic concentration modules * Tracking systems for photovoltaic concentration * High-concentration systems * Rating and performance * Cost considerations * Conclusions * References

  3. Fiber diameter distributions in the chinchilla's ampullary nerves

    NASA Technical Reports Server (NTRS)

    Hoffman, Larry F.; Honrubia, Vicente

    2002-01-01

    A morphometric study of the chinchilla's ampullary nerves was conducted to produce an unbiased accounting of the diameter distribution of their constituent fibers. Diameter analyses were determined from 1 microm plastic-embedded nerve sections taken at a plane immediately proximal to the sensory epithelium. We found these nerves to be composed of 2094+/-573 fibers, having diameters that ranged from 0.5 to 8 microm. The distributions of diameters were positively skewed, where approximately 75% of the fibers were found to have diameters less than 3.5 microm. An analysis of the spatial distribution of diameters within the nerve section revealed that the lateralmost areas of the nerve contained larger fractions of fibers within the smallest diameter quintiles, and the central area harbored greater proportions of the larger diameter quintiles. However, significant fractions of all quintiles were found in all areas. These data were integrated with available data of Fernandez et al. (1998) to produce diameter estimates of calyx, dimorphic, and bouton morphology subpopulations. In view of a general relationship between diameter, innervation locus, and an afferent's physiologic characteristics, these data provide the basis for developing a perspective for the in situ distribution of afferent response dynamics.

  4. Catastrophes of large diameter pipelines. The role of hydrogen fields

    SciTech Connect

    Polyakov, V.N.

    1995-09-01

    Fracture statistics on transmission pipelines is presented. Fractures of large-diameter pipelines are regarded as catastrophes. Fracture accidents of other pipes are less dangerous. Hydrogen makes outer layers of pipes brittle. Therefore, critical crack lengths for pipes have been calculated by a linear fracture mechanics technique. It was found that a crack of any length may be critical. The opposite opinion on reliable operation of large-diameter pipes (diameter 1420 mm) is discussed.

  5. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

  6. Wire diameter dependence in the catalytic decomposition of H2

    NASA Astrophysics Data System (ADS)

    Umemoto, Hironobu

    2014-01-01

    Jansen et al. have demonstrated that the dissociaiton rate of H2 molecules on hot wire surfaces, normalized per unit surface area, depends on the wire diameter based on the electrical power consumption measurements [J. Appl. Phys. 66, 5749 (1989)]. Mathematical modeling calculations have also been presented to support their experimental results. In the present paper, it is shown that such a wire diameter dependence cannot be observed and that the H-atom density normalized by the wire surface area depends little on the wire diameter. Modeling calculations also show that the wire diameter dependence of the dissociation rate cannot be expected under typical decomposition conditions.

  7. Thermoelectric properties of single-wall carbon nanotube films: Effects of diameter and wet environment

    NASA Astrophysics Data System (ADS)

    Hayashi, Daisuke; Ueda, Tomohiro; Nakai, Yusuke; Kyakuno, Haruka; Miyata, Yasumitsu; Yamamoto, Takahiro; Saito, Takeshi; Hata, Kenji; Maniwa, Yutaka

    2016-02-01

    The Seebeck coefficient S and the electrical resistivity ρ of single-wall carbon nanotube (SWCNT) films were investigated as a function of the SWCNT diameter and carrier concentration. The S and ρ significantly changed in humid environments through p-type carrier doping. Experiments, combined with theoretical simulations based on the non-equilibrium Green’s function theory, indicated that the power factor P can be increased threefold by the enrichment of semiconducting SWCNTs, but the nanotube diameter has little effect. The improvement of the film resistivity strongly enhances the film thermoelectric performance, manifested as increasing the value of P above 1200 µW/(m·K2).

  8. Extracting concentrated guided light.

    PubMed

    Ries, H; Segal, A; Karni, J

    1997-05-01

    The maximum concentration of radiation is proportional to the square of the refractive index of the medium in which it propagates. A medium with a high refractive index can also serve as a lightguide for concentrated radiation. However, if concentrated radiation is extracted from one medium, with a high refractive index, to another, whose index is lower (e.g., from fused silica into air), part of the radiation may be lost because of the total internal reflection at the interface. We present polygonal shapes suitable for efficient extraction of the concentrated radiation in a controllable way, without increasing the cross-section area (or diameter) of the lightguide. It is shown analytically and experimentally that the use of a secondary concentrator, followed by such a light extractor, both having a high refractive index, can provide considerably more power to a solar receiver with a specific aperture. PMID:18253285

  9. Brain Arterial Diameters as a Risk Factor for Vascular Events

    PubMed Central

    Gutierrez, Jose; Cheung, Ken; Bagci, Ahmet; Rundek, Tatjana; Alperin, Noam; Sacco, Ralph L; Wright, Clinton B; Elkind, Mitchell S V

    2015-01-01

    Background Arterial luminal diameters are routinely used to assess for vascular disease. Although small diameters are typically considered pathological, arterial dilatation has also been associated with disease. We hypothesize that extreme arterial diameters are biomarkers of the risk of vascular events. Methods and Results Participants in the Northern Manhattan Study who had a time-of-flight magnetic resonance angiography were included in this analysis (N=1034). A global arterial Z-score, called the brain arterial remodeling (BAR) score, was obtained by averaging the measured diameters within each individual. Individuals with a BAR score <−2 SDs were considered to have the smallest diameters, individuals with a BAR score >−2 and <2 SDs had average diameters, and individuals with a BAR score >2 SDs had the largest diameters. All vascular events were recorded prospectively after the brain magnetic resonance imaging. Spline curves and incidence rates were used to test our hypothesis. The association of the BAR score with death (P=0.001), vascular death (P=0.02), any vascular event (P=0.05), and myocardial infarction (P=0.10) was U-shaped except for ischemic stroke (P=0.74). Consequently, incidence rates for death, vascular death, myocardial infarction, and any vascular event were higher in individuals with the largest diameters, whereas individuals with the smallest diameters had a higher incidence of death, vascular death, any vascular event, and ischemic stroke compared with individuals with average diameters. Conclusions The risk of death, vascular death, and any vascular event increased at both extremes of brain arterial diameters. The pathophysiology linking brain arterial remodeling to systemic vascular events needs further research. PMID:26251284

  10. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-12-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ's raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  11. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool

    PubMed Central

    Hotaling, Nathan A.; Bharti, Kapil; Kriel, Haydn; Simon, Carl G.

    2015-01-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ’s raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  12. The Measurements of the Solar Diameter at the Kepler's Times

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Fraschetti, Federico

    2002-12-01

    We examine five measurements of the solar disk diameter made with a pinhole instrument by Tycho in 1591 and Kepler in 1600-1602 [1]. Those are the first accurate measurements of the solar disk diameter available in literature, even if Ptolemy and Copernicus already did such measurements [2].

  13. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  14. Periodically Diameter-Modulated Semiconductor Nanowires for Enhanced Optical Absorption.

    PubMed

    Ko, Minjee; Baek, Seong-Ho; Song, Bokyung; Kang, Jang-Won; Kim, Shin-Ae; Cho, Chang-Hee

    2016-04-01

    A diameter-modulated silicon nanowire array to enhance the optical absorption across broad spectral range is presented. Periodic shape engineering is achieved using conventional semiconductor processes and the unique optical properties are analyzed. The periodicity in the diameter of the silicon nanowires enables stronger and more closely spaced optical resonances, leading to broadband absorption enhancement. PMID:26833855

  15. Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model

    NASA Astrophysics Data System (ADS)

    Dávalos, J. O.; García, J. C.; Urquiza, G.; Castro-Gómez, L. L.; Rodríguez, J. A.; De Santiago, O.

    2016-04-01

    Thermal stresses in a simplified steam turbine rotor model during a cold startup are analyzed using finite element analysis (FEA). In order to validate the numerical model, an experimental array is developed in which a hollow cylinder is heated with hot air in the external surface. At the thick wall of the cylinder, temperature distribution is measured in real time, while at the same time an algorithm computes thermal stresses. Additional computational fluid dynamics (CFD) calculations are made to obtain magnitudes of velocity and pressure in order to compute convective heat transfer coefficient. The experimental results show good agreement with the FEA computations. To evaluate the effect of rotor diameter size, FEA computations with variation in external and internal diameters are performed. Results show that thermal stresses are proportional to rotor diameter size. Also, zones of higher stress concentration are found in the external and internal surfaces of the rotor.

  16. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity.

    PubMed

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-12-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena. PMID:27581602

  17. Femoral head diameter considerations for primary total hip arthroplasty.

    PubMed

    Girard, J

    2015-02-01

    The configuration of total hip arthroplasty (THA) implants has constantly evolved since they were first introduced. One of the key components of THA design is the diameter of the prosthetic femoral head. It has been well established that the risk of dislocation is lower as the head diameter increases. But head diameter impacts other variables beyond joint stability: wear, cam-type impingement, range of motion, restoration of biomechanics, proprioception and groin pain. The introduction of highly cross-linked polyethylene and hard-on-hard bearings has allowed surgeons to implant large-diameter heads that almost completely eliminate the risk of dislocation. But as a result, cup liners have become thinner. With femoral head diameters up to 36 mm, the improvement in joint range of motion, delay in cam-type impingement and reduction in dislocation risk have been clearly demonstrated. Conversely, large-diameter heads do not provide any additional improvements. If an "ecologically sound" approach to hip replacement is embraced (e.g. keeping the native femoral head diameter), hip resurfacing with a metal-on-metal bearing must be carried out. The reliability of large-diameter femoral heads in the longer term is questionable. Large-diameter ceramic-on-ceramic bearings may be plagued by the same problems as metal-on-metal bearings: groin pain, squeaking, increased stiffness, irregular lubrication, acetabular loosening and notable friction at the Morse taper. These possibilities require us to be extra careful when using femoral heads with a diameter greater than 36 mm. PMID:25596984

  18. Pupil Diameter Changes in High Myopes after Collamer Lens Implantation

    PubMed Central

    Li, Dan; Yang, Yabo; Su, Caipei; Yin, Houfa; Liu, Xue

    2015-01-01

    ABSTRACT Purpose To observe the changes in pupil size under photopic and scotopic conditions after Implantable Collamer Lens (ICL) implantations in eyes with high myopia. Methods The ICL was implanted in 90 eyes belonging to 45 patients with high myopia. Photopic pupil diameters, scotopic pupil diameters, anterior chamber depths, and ICL vaults were examined at the preoperative, postoperative 1-month, and postoperative 3-month stages. The preoperative and postoperative photopic pupil diameters and scotopic pupil diameters were also compared with each other to note the differences between them. The correlations between preoperative and postoperative pupil diameter changes under different light conditions and presurgical refractive error were analyzed alongside patient’s age and ICL vault. Results Pupil diameters at both postoperative 1-month and postoperative 3-month stages were smaller than those before operation in distinct light environments, as well as pupil constriction amplitude. Correlation analysis showed that there was a statistically significant correlation between pupil diameter changes under different light conditions and presurgical refractive error at 1 month and 3 months after ICL implantation; pupil diameter decreased more when presurgical refractive error powers were less myopic. Statistically significant correlations were not found, however, with patient’s age and ICL vault. Postoperative 1-month and mean postoperative 3-month anterior chamber depths were decreased when compared with preoperative anterior chamber depths. Statistically significant correlations were found in change in preoperative and postoperative anterior chamber depth and ICL vault. No statistically significant difference was found between ICL vault at the postoperative 1-month and postoperative 3-month stages. Conclusions Pupil diameter may decrease at the 1- and 3-month stages after ICL implantation under both photopic and scotopic conditions. This indicates that reduction

  19. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  20. Concentric Nested Toroidal Inflatable Structures

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.

    2010-01-01

    Assemblies comprising multiple limited- height toroidal inflatable structures nested in a concentric arrangement have been invented to obtain more design flexibility than can be obtained in single taller, wider toroidal inflatable structures (see figure). Originally intended for use as containers for habitats for humans in outer space or on remote planets, these and related prior inflatable structures could also be useful on Earth as lightweight, compactly stowable, portable special-purpose buildings that could be transported to remote locations and there inflated to full size and shape. In the case of a single inflatable toroidal structure, one important source of lack of design flexibility is the fact that an increase in outer diameter (which is sometimes desired) is necessarily accompanied by an increase in height (which is sometimes undesired). Increases in diameter and height can also cause difficulty in utilization of the resulting larger volume, in that it can become necessary to partition the volume by means of walls and floors, and features (e.g., stairs or ladders) must be added to enable vertical movement between floors. Moreover, ascending and descending between floors in a gravitational environment could pose unacceptable difficulty for the inhabitants under some circumstances. Another source of lack of design flexibility in a single toroidal inflatable structure is that for a given inflation pressure, an increase in the outer diameter of the structure necessarily entails an increase in the maximum stress in the structure. Because it is necessary to keep the maximum stress within the load-bearing capability of the structural materials, consistent with other aspects of the design, this may translate to a limit on the outer diameter. In an assembly comprising concentric nested toroidal structures, an increase in outer diameter does not necessarily entail an increase in height or a maximum stress in excess of the load-bearing capability of the structural

  1. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.

    2006-07-01

    The critical diameter and failure thickness of both neat liquid nitromethane and a 65% nitromethane/35% nitroethane blend confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism of detonation in these explosives. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from expansion losses (wave curvature), then it is expected that the failure thickness should be half the value of the critical diameter. The critical diameter and failure thickness of neat nitromethane confined in aluminum are found to be 2.5 mm and 0.75 mm respectively for a temperature range of 26 ± 1°C. The critical diameter and failure thickness of the 65NM/35NE blend confined in aluminum are found to be 6.2 mm and 1.7 mm respectively for a temperature range of 28 ± 1°C. The ratio of critical diameter to failure thickness for these experiments is found to lie between 3:1 and 4:1 rather than 2:1 as expected from wave curvature theory. By comparing the experimentally determined values of critical diameter and thickness for the test explosives and examining the failure patterns recovered on witness plates, a mechanism of propagation in thin rectangular channels is proposed based on complex wave interactions.

  2. Sterilization of various diameter dead-ended tubes.

    PubMed

    Young, J H

    1993-06-01

    Effect of tube diameter on steam-in-place sterilization of dead-ended tubes was studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Time required for sterilization was determined for 9.4-cm-long tubes with various inside diameters from 0.4 to 1.7 cm. Sterilization time increased with decreasing tube diameter. Experimentally measured kill kinetics in 1.7-cm tubes were in agreement with those predicted if measured temperatures represented saturated steam. A 12-log spore reduction was achieved in 1.7-cm diameter vertical and horizontal tubes in less than 63 minutes. For smaller diameter tubes, entrapped air remained after 2 hours and rates of kill were very dependent on position within the tube, tube diameter, and tube orientation with respect to the gravitational vector. Times to achieve a 1-log drop in spore population in the smaller tubes were as much as 10 times greater than those expected if measured temperatures represented saturated steam. Sterilization was not achieved throughout the 0.4-cm tubes. Recommendations are made for including steam bleeders or using prevaccum cycles for these smaller diameter tubes. PMID:18609656

  3. Determination of the inner diameter of a double-walled carbon nanotube from its Raman spectra

    NASA Astrophysics Data System (ADS)

    Basirjafari, Sedigheh; Esmaielzadeh Khadem, Siamak; Malekfar, Rasoul

    2013-02-01

    In this paper, an exact formula is obtained for the inner diameter of double-walled carbon nanotube (DWCNT) as a function of its higher radial breathing mode (RBM) frequency, using the symbolic package of maple software. Its outer diameter is obtained from the inner diameter formula by considering the constant interlayer spacing between two tubes of DWCNT. For this purpose, DWCNT is considered as double concentric elastic thin cylindrical shells, which are coupled through the van der Waals (vdW) forces between two tubes. Lennard-Jones potential is used to calculate the vdW forces between tubes. The advantage of this analytical approach is that in the double concentric elastic shell model all degrees of freedom in the vibrational analysis of DWCNTs are considered. To demonstrate the accuracy of this work, the relationship between RBM frequency of a single-walled carbon nanotube and its radius is deduced from the DWCNT formula that is well consistent with other publications. To illustrate the application of this approach, the diameters of DWCNTs are obtained from their known RBM frequencies which show an excellent agreement with the available experimental results. Also, the influence of changing the geometrical and mechanical parameters of a DWCNT on its RBM frequencies has been investigated.

  4. Effects of diameter and temperature on XTX-8004 detonation velocity

    SciTech Connect

    Campos, C.A.

    1980-10-01

    This study was performed to determine the dependence of XTX-8004 steady detonation velocity on charge diameter and temperature. The tests were performed for four different diameters at three temperatures using a standard 4-track detonation velocity block and corresponding printed circuit ionization switch plate. The explosive was loaded in the detonation velocity block to a nominal density of 1.553 g/cc. Measurements obtained from two samples per temperature indicate the critical diameter is less than 0.178 cm. A relationship between detonation velocity and density due to temperature was established using experimental measurements.

  5. Calibration of the radiometric asteroid scale using occultation diameters

    NASA Technical Reports Server (NTRS)

    Telesco, C. M.; Brunk, W. E.; Brown, R. H.; Morrison, D.

    1982-01-01

    The paper describes a new approach to the calibration of the radiometric asteroid scale, which relies on recent accurate occultation measurements of the diameters of 2 Pallas (Wasserman et al., 1979) and 3 Juno (Millis et al., 1981), and the Voyager diameter of J4 Callisto, as well as IR photometry of these objects obtained with the NASA 3-m Infrared Telescope Facility. It is shown that this calibration is internally consistent to better than 5%, and probably has an absolute accuracy of + or - 5%. It is noted that a revision of the TRIAD radiometric diameters downward is required to bring them into agreement with the new calibration.

  6. Thermal mechanical analyses of large diameter ion accelerator systems

    SciTech Connect

    Brophy, J.R.; Aston, G.

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size. 8 refs.

  7. Thermal mechanical analyses of large diameter ion accelerator systems

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size.

  8. The influence of diameter ratio on the stress distribution around 90{degree} branch pipe connection due to internal pressure

    SciTech Connect

    Harsokoesoemo, D.; Santoso, G.

    1994-12-31

    Numerical stress calculation results of stress distribution around 90{degree} branch pipe connection due to internal pressure for several main and branch pipe diameter ratios using finite element program MECHANICA (RASNA) are presented in this paper. The calculation results are presented in two types of diagrams, one is in the form of stress versus its location on the main and branch pipe curves for 4 different diameter ratios and the other as stress concentration factor versus diameter ratios curves for the case d/t = D/T and t = T and for three pipe schedule number 40, 80 and 160.

  9. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.

    2005-07-01

    The critical diameter and failure thickness of liquid nitromethane confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism in nitromethane. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from wave curvature, then it is expected that the critical diameter should be half the value of the critical thickness.[1] This has been shown to be the case with gas-phase detonations with nearly laminar reaction zones.[2] By comparing the experimentally determined values of critical diameter and thickness for a homogeneous liquid explosive, the validity of this model of detonation failure can be assessed. References: 1. Ramsay, J.B., 8th Symp. (Int.) on Detonation., 372-379 (1985). 2. Radulescu, M., Lee, J.H.S., Comb. and Flame, 131:29-46 (2002).

  10. SMALL DIAMETER STENCILING, ROLLING OVER STAMP. United States Pipe ...

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

    SMALL DIAMETER STENCILING, ROLLING OVER STAMP. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  11. Wavelength dependence of the apparent diameter of retinal blood vessels.

    PubMed

    Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

    2005-04-01

    Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column. PMID:15813519

  12. Optimal electrode diameter in relation to volume of the cochlea.

    PubMed

    Gnansia, D; Demarcy, T; Vandersteen, C; Raffaelli, C; Guevara, N; Delingette, H; Ayache, N

    2016-06-01

    The volume of the cochlea is a key parameter for electrode-array design. Indeed, it constrains the diameter of the electrode-array for low-traumatic positioning in the scala timpani. The present report shows a model of scala timpani volume extraction from temporal bones images in order to estimate a maximum diameter of an electrode-array. Nine temporal bones were used, and passed to high-resolution computed tomography scan. Using image-processing techniques, scala timpani were extracted from images, and cross-section areas were estimated along cochlear turns. Cochlear implant electrode-array was fitted in these cross-sections. Results show that the electrode-array diameter is small enough to fit in the scala timpani, however the diameter is restricted at the apical part. PMID:27246746

  13. Anomalous dependence of band gaps of binary nanotubes on diameters

    NASA Astrophysics Data System (ADS)

    Adhikari, Kapil; Huda, Muhammad; Ray, Asok

    2012-02-01

    Using cluster approximation, AlN, BN, GaN, SiGe, SiC, and GeC armchair type 1 nanotubes have been spin optimized using the hybrid functional B3LYP, a double ζ basis set and the GAUSSIAN 03 software. The electronic structures of group III nitride and group IV-IV nanotubes indicate that the band gap increases with tube diameter contrary to behavior expected from quantum size effects. A detailed study indicates that, in a class of binary nanotubes with partial ionic contributions in the bonds, for example, AlN, BN, GaN, GeC, and SiC, ionicity of the bonds decreases as diameter decreases due to increased sp^3 contribution. This causes the band gap to increase with diameter. But in nanotubes with covalent bonding, for example SiGe, the gap decreases with diameter. A general trend for a class of binary nanotubes is established.

  14. SMALL DIAMETER GRAVITY SEWERS: AN ALTERNATIVE FOR UNSEWERED COMMUNITIES

    EPA Science Inventory

    The most recently introduced wastewater collection alternative for small unsewered communities is septic tank effluent drains or small diameter gravity sewers (SDGS). Unlike conventional sewers, SDGS only collect settled wastewater. Grit, grease and other troublesome solids which...

  15. SMALL DIAMETER CEMENT LINING FROM STAIRWAY. United States Pipe ...

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

    SMALL DIAMETER CEMENT LINING FROM STAIRWAY. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  16. SMALL DIAMETER PRECEMENT LINING FROM CATWALK ABOVE. United States ...

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

    SMALL DIAMETER PRE-CEMENT LINING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  17. Northern view of inside diameter welding station of the saw ...

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

    Northern view of inside diameter welding station of the saw line in bay9 of the main pipe mill building. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  18. Pupil diameter reflects uncertainty in attentional selection during visual search

    PubMed Central

    Geng, Joy J.; Blumenfeld, Zachary; Tyson, Terence L.; Minzenberg, Michael J.

    2015-01-01

    Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones and Cohen, 2005; Yu and Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time (RT) and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. PMID:26300759

  19. SMALL DIAMETER PAINTING FROM CATWALK ABOVE. United States Pipe ...

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

    SMALL DIAMETER PAINTING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  20. Development of welded metal bellows having minimum effective diameter change

    NASA Technical Reports Server (NTRS)

    Henschel, J. K.; Stevens, J. B.; Harvey, A. C.; Howland, J. S.; Rhee, S. S.

    1972-01-01

    A program of analysis, design, and fabrication was conducted to develop welded metal bellows having a minimum change in effective diameter for cryogenic turbomachinery face seal applications. Linear analysis of the principle types of bellows provided identification of concepts capable of meeting basic operation requirements. For the 6-inch (.152 m) mean diameter, 1.5-inch free length bellows studied, nonlinear analysis showed that opposed and nested toroidal bellows plates stiffened by means of alternating stiffener rings were capable of maintaining constant effective diameter within 0.3% and 0.1% respectively under the operating conditions of interest. Changes in effective diameter were due principally to bellows axial deflection with pressure differential having a lesser influence. Fabrication problems associated with joining the thin bellows plates to the relatively heavy stiffener rings were encountered and precluded assembly and testing of a bellows core. Fabrication problems are summarized and recommended fabrication methods for future effort are presented.

  1. Eddy sensors for small diameter stainless steel tubes.

    SciTech Connect

    Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

    2011-08-01

    The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

  2. Acoustic fill factors for a 120 inch diameter fairing

    NASA Technical Reports Server (NTRS)

    Lee, Y. Albert

    1992-01-01

    Data from the acoustic test of a 120-inch diameter payload fairing were collected and an analysis of acoustic fill factors were performed. Correction factors for obtaining a weighted spatial average of the interior sound pressure level (SPL) were derived based on this database and a normalized 200-inch diameter fairing database. The weighted fill factors were determined and compared with statistical energy analysis (VAPEPS code) derived fill factors. The comparison is found to be reasonable.

  3. Thermal resistance of ultra-small-diameter disk microlasers

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Shostak, I. I.; Moiseev, E. I.; Kudashova, Yu. V.; Kulagina, M. M.; Troshkov, S. I.

    2015-05-15

    The thermal resistance of AlGaAs/GaAs microlasers of the suspended-disk type with a diameter of 1.7–4 μm and InAs/InGaAs quantum dots in the active region is inversely proportional to the squared diameter of the microdisk. The proportionality factor is 3.2 × 10{sup −3} (K cm{sup 2})/W, and the thermal resistance is 120–20°C/mW.

  4. Nanofiber diameter-dependent MAPK activity in osteoblasts.

    PubMed

    Jaiswal, Devina; Brown, Justin L

    2012-11-01

    The major challenge for bone tissue engineering lies in the fabrication of scaffolds that can mimic the extracellular matrix and promote osteogenesis. Electrospun fibers are being widely researched for this application due to high porosity, interconnectivity, and mechanical strength of the fibrous scaffolds. Electrospun poly methyl methacrylate (PMMA, 2.416 ± 0.100 μm) fibers were fabricated and etched using a 60% propylene glycol methyl ether acetate (PGMEA)/limonene (vol/vol) solution to obtain fiber diameters ranging from 2.5 to 0.5 μm in a time-dependent manner. The morphology of the fibrous scaffolds was evaluated using scanning electron microscopy and cellular compatibility with etchant-treated scaffold was assessed using immunoflurescence. Mitogen-activated protein kinases (MAPK) activation in response to different fiber diameter was evaluated with western blot as well as quantitative in-cell western. We report that electrospun micro-fibers can be etched to 0.552 ± 0.047 μm diameter without producing beads. Osteoblasts adhered to the fibers and a change in fiber diameter played a major role in modulating the activation of extracellular signal-regulated kinase (ERK) and p38 kinases with 0.882 ± 0.091 μm diameter fibers producing an inverse effect on ERK and p38 phosphorylation. These results indicate that nanofibers produced by wet etching can be effectively utilized to produce diameters that can differentially modulate MAPK activation patterns. PMID:22700490

  5. Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

    SciTech Connect

    Kephart, A.R.

    1997-05-01

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress is equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.

  6. Predicting Hamstring Graft Diameter Using MRI and Anthropometry

    PubMed Central

    Fritsch, Brett A; Mhaskar, Vikram A; An, Vincent Vinh Gia; Scholes, Corey

    2016-01-01

    Objectives: Graft diameter is one variable that may affect outcome of ACL reconstruction. The ability to predict the size of a graft in a given patient pre-operatively may help guide graft selection and preparation technique. Various papers have correlated anthropometric data and MRI tendon measurements to intraoperative graft diameter, although no papers have investigated these together. The intra-operative diameter of a hamstring autograft will be influenced by graft preparation technique. Our study aimed to investigate the prediction of intraoperative graft diameter of 2 different graft construct techniques (4-strand semitendinosus versus quadrupled semitendinosus) using anthropometry and MRI measurements. Methods: Retrospective review of two groups of ACL reconstruction using different graft preparation techniques was performed. “Conventional” 4-strand gracilis + semitendinosus with fixed suspension at the femur and screw fixation at the tibia were compared with quadrupled semitendinosus grafts with adjustable suspensory fixation at each end (Graftlink). Cross-sectional areas (XSA) of the semitendinosus and gracilis tendons was measured in the axial slice of a T2 weighted MRI image using a region-of-interest tool. Stepwise linear regression using intraoperative graft diameter as the dependant variable was performed using MRI XSA of the semitendinosus and gracilis tendons, gender and height as predictors. Results: 129 ACL Reconstruction in 127 patients were done in the time period, 89 of which were done conventionally, and 40 which employed the Graftlink construct. The median graft diameter in the Graftlink group (8.5mm IQR8-9) was greater than that of the conventional group (8mm, IQR 7.5-8) (p < 0.001). MRI XSA of semitendinosus and height were statistically significant predictors of diameter in the Graftlink group (R2 = 51%), whilst MRI XSA of semitendinosus + gracilis and gender were predictors in the conventional group (R2 = 36%). Conclusion: Graftlink

  7. Large Diameter, Radiative Extinction Experiments with Decane Droplets in Microgravity

    NASA Technical Reports Server (NTRS)

    Easton, John; Tien, James; Dietrich, Daniel

    1999-01-01

    The extinction of a diffusion flame is of fundamental interest in combustion science. Linan, Law, and Chung and Law analytically and experimentally determined an extinction boundary in terms of droplet diameter and pressure for a single droplet due to Damkohler, or blowoff, extinction. More recently, other researchers demonstrated extinction due to finite rate kinetics in reduced gravity for free droplets of heptane. Chao modeled the effect of radiative heat loss on a quasi-steady spherically symmetric single droplet burning in the absence of buoyancy. They determined that for increasing droplet diameter, a second limit can be reached such that combustion is no longer possible. This second, larger droplet diameter limit arises due to radiative heat loss, which increases with increasing droplet and flame diameter. This increase in radiative heat loss arises due to an increase in the surface area of the flame. Recently, Marchese modeled fuel droplets with detailed chemistry and radiative effects, and compared the results to other work. The modeling also showed the importance of radiative loss and radiative extinction Experiments examined the behavior of a large droplet of decane burning in reduced gravity onboard the NASA Lewis DC-9 aircraft, but did not show a radiative extinction boundary due to g-jitter (Variations in gravitational level and direction) effects. Dietrich conducted experiments in the reduced gravity environment of the Space Shuttle. This work showed that the extinction diameter of methanol droplets increased when the initial diameter of the droplets was large (in this case, approximately 5 mm). Theoretical results agreed with these experimental results only when the theory included radiative effects . Radiative extinction was experimentally verified by Nayagam in a later Shuttle mission. The following work focuses on the combustion and extinction of a single fuel droplet. The goal is to experimentally determine a large droplet diameter limit that

  8. Stem diameter variations as a versatile research tool in ecophysiology.

    PubMed

    De Swaef, Tom; De Schepper, Veerle; Vandegehuchte, Maurits W; Steppe, Kathy

    2015-10-01

    High-resolution stem diameter variations (SDV) are widely recognized as a useful drought stress indicator and have therefore been used in many irrigation scheduling studies. More recently, SDV have been used in combination with other plant measurements and biophysical modelling to study fundamental mechanisms underlying whole-plant functioning and growth. The present review aims to scrutinize the important insights emerging from these more recent SDV applications to identify trends in ongoing fundamental research. The main mechanism underlying SDV is variation in water content in stem tissues, originating from reversible shrinkage and swelling of dead and living tissues, and irreversible growth. The contribution of different stem tissues to the overall SDV signal is currently under debate and shows variation with species and plant age, but can be investigated by combining SDV with state-of-the-art technology like magnetic resonance imaging. Various physiological mechanisms, such as water and carbon transport, and mechanical properties influence the SDV pattern, making it an extensive source of information on dynamic plant behaviour. To unravel these dynamics and to extract information on plant physiology or plant biophysics from SDV, mechanistic modelling has proved to be valuable. Biophysical models integrate different mechanisms underlying SDV, and help us to explain the resulting SDV signal. Using an elementary modelling approach, we demonstrate the application of SDV as a tool to examine plant water relations, plant hydraulics, plant carbon relations, plant nutrition, freezing effects, plant phenology and dendroclimatology. In the ever-expanding SDV knowledge base we identified two principal research tracks. First, in detailed short-term experiments, SDV measurements are combined with other plant measurements and modelling to discover patterns in phloem turgor, phloem osmotic concentrations, root pressure and plant endogenous control. Second, long-term SDV time

  9. [Modeling formation of aerobic granule and influence of hydrodynamic shear forces on granule diameter].

    PubMed

    Dong, Feng; Zhang, Han-Min; Yang, Feng-Lin

    2012-01-01

    A one-dimension aerobic granule mathematical model was established, basing on mathematical biofilm model and activated sludge model. The model was used to simulate simple aerobic granule process such as nutrients removal, granule diameter evolution, cycle performance as well as depth profiles of DO and biomass. The effluent NH4(+) -N concentration decreased as the modeling processed. The simulation effluent NO3(-)-N concentration decreased to 3 mg x L(-1) as the granules grew. While the granule diameter increased from 1.1 mm on day 30 to 2.5 mm on day 100, the TN removal efficiency increased from less than 10% to 91%. The denitrification capacity was believed to enhance because the anoxic zone would be enlarged with the increasing granule diameter. The simultaneous nitrification and denitrification occurred inside the big aerobic granules. The oxygen permeating depth increased with the consumption of substrate. It was about 100-200 microm at the beginning of the aeration phase, and it turned to near 800 microm at the end of reaction. The autotrophs (AOB and NOB) were mostly located at the out layer where the DO concentration was high. The heterotrophic bacteria were distributed through the whole granule. As hydrodynamic shear coefficient k(de) increased from 0.25 (m x d)(-1) to 5 (m x d)(-1), the granule diameter under steady state decreased form 3.5 mm to 1.8 mm. The granule size under the dynamic steady-state decreased with the increasing hydrodynamic shear force. The granule size could be controlled by adjusting aeration intensity. PMID:22452208

  10. Memory, emotion, and pupil diameter: Repetition of natural scenes.

    PubMed

    Bradley, Margaret M; Lang, Peter J

    2015-09-01

    Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes. PMID:25943211

  11. Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum

    PubMed Central

    Sepehrband, Farshid; Alexander, Daniel C.; Clark, Kristi A.; Kurniawan, Nyoman D.; Yang, Zhengyi; Reutens, David C.

    2016-01-01

    Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy), or to infer them indirectly (e.g., using diffusion-weighted MRI). The gamma distribution is a common choice for this purpose (particularly for the inferential approach) because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions. PMID:27303273

  12. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.

    PubMed

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2012-04-20

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications. PMID:22456180

  13. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media

    NASA Astrophysics Data System (ADS)

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M.; Luna, Mónica; Briones, Fernando

    2012-04-01

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles’ performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications.

  14. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  15. Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires

    NASA Astrophysics Data System (ADS)

    Zuev, Yuri; Lee, Jin Sook; Park, Hongkun; Kim, Philip

    2010-03-01

    We report measurements of electronic, thermoelectric, and galvanometric properties of individual semimetallic single crystal antimony telluride (Sb2Te3) nanowires. Microfabricated heater and thermometer electrodes were used to probe the transport properties of the nanowires with diameters in the range of 22 - 95nm and temperatures in the range of 2 - 300K. Temperature dependent resistivity varies depending on nanowire diameter. Thermoelectric power (TEP) measurements indicate hole dominant diffusive thermoelectric generation, with an enhancement of the TEP for smaller diameter wires. The large surface-to-volume ratio of Sb2Te3 nanowires makes them an excellent platform to explore novel phenomena in this predicted topological insulator. We investigate mesoscopic magnetoresistance effects in magnetic fields both parallel and perpendicular to the nanowire axis.

  16. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±˜20% and ±˜40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  17. Nanofiber alignment of a small diameter elastic electrospun scaffold

    NASA Astrophysics Data System (ADS)

    Patel, Jignesh

    Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data

  18. Blood viscosity in tube flow: dependence on diameter and hematocrit.

    PubMed

    Pries, A R; Neuhaus, D; Gaehtgens, P

    1992-12-01

    Since the original publications by Martini et al. (Dtsch. Arch. Klin. Med. 169: 212-222, 1930) and Fahraeus and Lindqvist (Am. J. Physiol. 96: 562-568, 1931), it has been known that the relative apparent viscosity of blood in tube flow depends on tube diameter. Quantitative descriptions of this effect and of the dependence of blood viscosity on hematocrit in the different diameter tubes are required for the development of hydrodynamic models of blood flow through the microcirculation. The present study provides a comprehensive data base for the description of relative apparent blood viscosity as a function of tube diameter and hematocrit. Data available from the literature are compiled, and new experimental data obtained in a capillary viscometer are presented. The combined data base comprises measurements at high shear rates (u > or = 50 s-1) in tubes with diameters ranging from 3.3 to 1,978 microns at hematocrits of up to 0.9. If corrected for differences in suspending medium viscosity and temperature, the data show remarkable agreement. Empirical fitting equations predicting relative apparent blood viscosity from tube diameter and hematocrit are presented. A pronounced change in the hematocrit dependence of relative viscosity is observed in a range of tube diameters in which viscosity is minimal. While a linear hematocrit-viscosity relationship is found in tubes of < or = 6 microns, an overproportional increase of viscosity with hematocrit prevails in tubes of > or = 9 microns. This is interpreted to reflect the hematocrit-dependent transition from single- to multifile arrangement of cells in flow. PMID:1481902

  19. The heliometric Astrolabe, a new instrument for solar diameter observations

    NASA Astrophysics Data System (ADS)

    Andrei, A. H.; Reis Neto, E.; D'Ávila, V. A.; Penna, J. L.; Assafin, M.; Boscardin, S. C.; De Avila, K. N.

    2006-10-01

    The Observatorio Nacional takes part in the Reseau de Suivi au Sol du Rayon Solaire (the international solar diameter monitoring network) which co-participates in the PICARD micro satellite, to be launched in 2008 to study the Earth climate and Sun variability relationship. A new instrument, a heliometer, was devised in order to minimize the atmospheric turbulence and reach data accuracy compatible with PICARD's. The heliometer principle of double images will be added to the astrolabe metrological quality, and fully digitized acquisition. The objective is to obtain two simultaneous images from the Sun, with fixed angular separation of about 30', which variation will contain the signature of the diameter variation.

  20. VEGF165 Stimulates Vessel Density and Vessel Diameter Differently in Angiogenesis and Lymphangiogenesis

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia; Radhakrishnan, Krishnan; DiCorleto, Paul E.; Leontiev, Dmitry; Anand-Apte, Bela; Albarran, Brian; Farr, Andrew G.

    2005-01-01

    Vascular endothelial growth factor-165 (VEGF(sub 165)) stimulated angiogenesis in the quail chorioallantoic membrane (CAM) by vessel expansion from the capillary network. However, lymphangiogenesis was stimulated by the filopodial guidance of tip cells located on blind-ended lymphatic sprouts. As quantified by fractal/generational branching analysis using the computer code VESGEN, vascular density increased maximally at low VEGF concentrations, and vascular diameter increased most at high VEGF concentrations. Increased vascular density and diameter were statistically independent events (r(sub s), -0.06). By fluorescence immunohistochemistry of VEGF receptors VEGFR-1 and VEGFR-2, alpha smooth muscle actin ((alpha) SMA) and a vascular/lymphatic marker, VEGF(sub 165) increased the density and diameter of sprouting lymphatic vessels guided by tip cells (accompanied by the dissociation of lymphatics from blood vessels). Isolated migratory cells expressing (alpha)SMA were recruited to blood vessels, whereas isolated cells expressing VEGFR-2 were recruited primarily to lymphatics. In conclusion, VEGF(sub 165) increased lymphatic vessel density by lymphatic sprouting, but increased blood vessel density by vascular expansion from the capillary network.

  1. Method of synthesizing small-diameter carbon nanotubes with electron field emission properties

    NASA Technical Reports Server (NTRS)

    Liu, Jie (Inventor); Du, Chunsheng (Inventor); Qian, Cheng (Inventor); Gao, Bo (Inventor); Qiu, Qi (Inventor); Zhou, Otto Z. (Inventor)

    2009-01-01

    Carbon nanotube material having an outer diameter less than 10 nm and a number of walls less than ten are disclosed. Also disclosed are an electron field emission device including a substrate, an optionally layer of adhesion-promoting layer, and a layer of electron field emission material. The electron field emission material includes a carbon nanotube having a number of concentric graphene shells per tube of from two to ten, an outer diameter from 2 to 8 nm, and a nanotube length greater than 0.1 microns. One method to fabricate carbon nanotubes includes the steps of (a) producing a catalyst containing Fe and Mo supported on MgO powder, (b) using a mixture of hydrogen and carbon containing gas as precursors, and (c) heating the catalyst to a temperature above 950.degree. C. to produce a carbon nanotube. Another method of fabricating an electron field emission cathode includes the steps of (a) synthesizing electron field emission materials containing carbon nanotubes with a number of concentric graphene shells per tube from two to ten, an outer diameter of from 2 to 8 nm, and a length greater than 0.1 microns, (b) dispersing the electron field emission material in a suitable solvent, (c) depositing the electron field emission materials onto a substrate, and (d) annealing the substrate.

  2. Production of a large-diameter uniform plasma by electron cyclotron resonance heating with a small-diameter Lisitano coil

    NASA Astrophysics Data System (ADS)

    Komori, A.; Takada, Y.; Yonesu, A.; Kawai, Y.

    1991-02-01

    A large-diameter uniform plasma is produced by electron cyclotron resonance heating with a slotted Lisitano coil of 9 cm in diameter by locating the resonance apart from the Lisitano coil. Although the plasma production with a Lisitano coil has been performed extensively by placing the resonance near the Lisitano coil, the influence of the resonance location has not received as much attention. When the resonance is located further than 8 cm from the Lisitano coil, the uniform plasma of ˜40 cm in diameter at densities of ˜1.2×1011 cm-3 is produced over the vacuum chamber with an inner radius of 46 cm. The microwave is propagated in the whole space between the resonance and the Lisitano coil, and spatial electric-field distributions of the microwave play an important role on forming the radially uniform plasma.

  3. FEM analysis of the mandibular first premolar with different post diameters.

    PubMed

    Du, Je-Kang; Lin, Wei-Ko; Wang, Chau-Hsiang; Lee, Huey-Er; Li, Hung-Yuan; Wu, Ju-Hui

    2011-07-01

    Several reports have pointed out that endodontically treated teeth can lack strength, and that the teeth can be reinforced using posts. However, it has not been clear how to select posts that meet the needs of most clinical situations, particularly in terms of the post diameter, which has a major influence on the occurrence of root fracture. The purpose of this study was to analyze the stress distributions of posts of various diameters during masticatory loads using a finite element method. A 3-dimensional (3D) finite element model of a lower first premolar was developed. We used the image software Geomagic Studio (3D Digital 2002; Geomagic, Research Triangle Park, NC, USA) to reduce the post diameter by 6 ratios to a root diameter of 20, 30, 40, 50, 60, and 80% and then individually implemented them into the root of a tooth. A chewing static force of 100 N was applied as a 45° diagonal load on the buccal cusp tip, and the σ(von Mises) and σ(max) stresses were calculated. Analysis of the σ(von Mises) values revealed that the stresses were concentrated in the middle 1/3 of both the post and the root surface for all models, as were the σ(max) values. The results also indicated that when the diameter of the post was 50% of that of the root, the stress distributions of the post and the root surface were most favorable. In conclusion, the clinical implications of the results will need to be further studied and discussed. PMID:21491101

  4. Enhancement of conductivity by diameter control of polyimide-based electrospun carbon nanofibers.

    PubMed

    Xuyen, Nguyen Thi; Ra, Eun Ju; Geng, Hong-Zhang; Kim, Ki Kang; An, Kay Hyeok; Lee, Young Hee

    2007-10-01

    Oxydianiline-pyromellitic dianhydride poly(amic acid) (ODA-PMDA PAA) was polymerized with a catalyst support of triethyl amine for controlling molecular weight. This polymer was used for electrospinning in the preparation of PAA nanofibers, a precursor of carbon nanofibers. Here the amount of catalyst and concentration of PAA solution were optimized to produce polyimide-based carbon nanofibers approximately 80 nm in diameter. The effects of molecular weight of PAA, bias voltage, and spinning rate on the morphology of electrospun PAA and polyimide nanofibers have been evaluated. We showed that the conductivity of the carbon nanofiber mat decreased with increasing nanofiber diameter, where the conductivity of polyimide-based carbon nanofiber mat was much higher than those of other types of carbon nanofiber mat. The key ingredient to increase conductivity in a carbon nanofiber mat was found to be the number of cross junctions between nanofibers. PMID:17850139

  5. Health hazard evaluation report heta 94-0179-2516, Diamet Corporation, Columbus, Indiana

    SciTech Connect

    Kinnes, G.M.; Martinez, K.F.; Lushniak, B.D.

    1995-07-01

    In response to a request from employees of DIAMET Corporation (SIC-3714), Columbus, Indiana, an investigation was begun into reported dermatitis and respiratory symptoms which were thought to be associated with the application of a rust preventive oil to finished metal parts. DIAMET manufactured sintered, metal machinery components using a powder metallurgy process. At the time of manual inspection, the parts were treated with the rust preventative oil just prior to packaging. At the time of the study the oil was applied using either an automatic spray table or a manual spray bottle. The time weighted average concentrations for all the personal breathing zone and area samples were below the NIOSH recommend exposure limits of 5 350mg/cubic meter, for oil mist and naphthas, respectively. The authors conclude that there was a potential for exposures to rust preventative oil during manual spraying. Design deficiencies were cited in the automatic spray tables which, when modified, will improve their effectiveness.

  6. Thermodiffusion in positively charged magnetic colloids: influence of the particle diameter.

    PubMed

    Sehnem, A L; Aquino, R; Campos, A F C; Tourinho, F A; Depeyrot, J; Figueiredo Neto, A M

    2014-03-01

    The Soret coefficient (ST) of positively charged magnetic colloids was measured as a function of the nanoparticles' diameter. The Z-scan technique and the generalization of the thermal lens model proved to be a reliable technique to measure ST. We show that ST is negative and increases with the particle's diameter, being best described by a functional dependence of the type ST∝d0. Potentiometric and conductometric experiments show that the particle's surface charge decreases as the temperature increases, changing the electrostatic interaction between the nanoparticles. The temperature gradient imposed in the ferrofluid by the Gaussian laser beam leads to the formation of the particle's concentration gradient. The origin of this phenomenon is discussed in terms of the decrease of the particle's surface charge in the hottest region of the sample and the thermoelectric field due to the inhomogeneous distribution of hydrogenous ions present in the colloidal suspension. PMID:24730843

  7. Real-time precision measuring device of tree diameter growth

    NASA Astrophysics Data System (ADS)

    Guo, Mingming; Chen, Aijun; Li, Dongsheng; Liu, Nan; Yao, Jingyuan

    2016-01-01

    DBH(diameter at breast height) is an important factor to reflect of the quality of plant growth, also an important parameter indispensable in forest resources inventory and forest carbon sink, the accurate measurement of DBH or not is directly related to the research of forest resources inventory and forest carbon sink. In this paper, the principle and the mathematical model of DBH measurement device were introduced, the fixture measuring device and the hardware circuit for this tree diameter were designed, the measurement software programs were compiled, and the precision measuring device of tree diameter growth was developed. Some experiments with Australia fir were conducted. Based on experiment data, the correlations among the DBH variation of Australian fir, the environment temperature, air humility and PAR(photosynthetically active radiation) were obtained. The effects of environmental parameters (environment temperature, air humility and PAR) on tree diameter were analyzed. Experimental results show that there is a positive correlation between DBH variation of Australian fir and environment temperature, a negative correlation between DBH variation of Australian fir and air humility , so is PAR.

  8. Solar diameter measurements for study of Sun climate coupling

    NASA Technical Reports Server (NTRS)

    Hill, H. A.

    1983-01-01

    Changes in solar shape and diameter were detected as a possible probe of variability in solar luminosity, an important climatic driving function. A technique was designed which will allow the calibration of the telescope field, providing a scale for long-term comparison of these and future measurements.

  9. Decrease rate of the renal diameter in chronic hemodialysis patients.

    PubMed

    Aoyagi, Teiichiro; Tachibana, Masaaki; Naganuma, Shinji

    2013-01-01

    We here present the results of ultrasonographic (US) evaluations on the alteration of renal diameter of chronic HD patients. Of 109 outpatient HD patients who had neither severe acquired cystic disease of the kidney nor hereditary polycystic kidney disease, we performed US two or three times to measure their maximum renal diameter (mean of both kidneys), and the yearly alteration rate was calculated. The average interval of the two measurements was 35.9 months, and the average HD duration from the HD induction to the first measurement was 29.5 months. The average decrease rate of renal diameter was 4.34 ± 0.4 (SE) mm/year. No statistical difference was seen on the decrease rate in relation to gender, age and original disease (among three groups, glomerulonephritis and IgA nephropathy, diabetes, and others including hypertension). However, the decrease rate was large when the first measurement was close to the induction of hemodialysis, suggesting that the alteration rate reduced according to the hemodialysis vintage (5.3 ± 0.8 mm/year, first measurement not more than 10 months after induction of HD and 1.5 ± 1.6 mm/year, first measurement more than 80 months after induction of HD). Renal diameter decreased approximately 4.3 mm each year, and the decrease rate slowed as the length of time on dialysis increased. PMID:24967236

  10. Rowlinson’s concept of an effective hard sphere diameter

    PubMed Central

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson’s idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations. PMID:20953320

  11. Measuring the Diameter of a Hair with a Steel Rule.

    ERIC Educational Resources Information Center

    Macdonald, John; O'Leary, Sean V.

    1994-01-01

    Describes a technique that uses a helium neon laser, a steel rule, a wooden rule, and a piece of paper to measure the diameter of a hair using the diffraction of light. Details on technique, mathematics, and sources of error are provided. (DDR)

  12. Ratio of Spleen Diameter to Red Blood Cell Distribution Width

    PubMed Central

    Balaban, Daniel Vasile; Popp, Alina; Lungu, Andrei Marian; Costache, Raluca Simona; Anca, Ioana Alina; Jinga, Mariana

    2015-01-01

    Abstract Celiac disease (CD) is currently considerably underdiagnosed, setting the need for developing tools to select patients with probability of CD, who warrant further testing. Red blood cell distribution width (RDW) has been shown in previous studies to be a sensitive predictor for CD, but it lacks specificity. Splenic hypotrophy is also noted frequently in celiac patients. Our aim was to evaluate if spleen diameter to RDW ratio can be used as an indicator for CD. We evaluated 15 newly diagnosed CD patients, 52 patients with inflammatory bowel disease, and 35 patients with irritable bowel syndrome (IBS). We evaluated the differences in spleen diameter, RDW, and their ratio among the four groups. Two-thirds of the CD patients had elevated RDW, compared to 9% in the IBS group. A small spleen was seen in 80% of the celiacs, compared to 21.9% in the ulcerative colitis group, 10% in the Crohn disease group, and 9% in the IBS group. A spleen diameter to RDW ratio under 6 had a sensitivity of 73.3% and specificity of 88.5% in predicting CD, with an AUROC of 0.737. Spleen diameter to RDW ratio is a simple, widely available score, which can be used to select adult patients with probability of CD. PMID:25881851

  13. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  14. Combined position and diameter measures for lunar craters

    USGS Publications Warehouse

    Arthur, D.W.G.

    1977-01-01

    The note addresses the problem of simultaneously measuring positions and diameters of circular impact craters on wide-angle photographs of approximately spherical planets such as the Moon and Mercury. The method allows for situations in which the camera is not aligned on the planet's center. ?? 1977.

  15. Assessment of vessel diameters for MR brain angiography processed images

    NASA Astrophysics Data System (ADS)

    Moraru, Luminita; Obreja, Cristian-Dragos; Moldovanu, Simona

    2015-12-01

    The motivation was to develop an assessment method to measure (in)visible differences between the original and the processed images in MR brain angiography as a method of evaluation of the status of the vessel segments (i.e. the existence of the occlusion or intracerebral vessels damaged as aneurysms). Generally, the image quality is limited, so we improve the performance of the evaluation through digital image processing. The goal is to determine the best processing method that allows an accurate assessment of patients with cerebrovascular diseases. A total of 10 MR brain angiography images were processed by the following techniques: histogram equalization, Wiener filter, linear contrast adjustment, contrastlimited adaptive histogram equalization, bias correction and Marr-Hildreth filter. Each original image and their processed images were analyzed into the stacking procedure so that the same vessel and its corresponding diameter have been measured. Original and processed images were evaluated by measuring the vessel diameter (in pixels) on an established direction and for the precise anatomic location. The vessel diameter is calculated using the plugin ImageJ. Mean diameter measurements differ significantly across the same segment and for different processing techniques. The best results are provided by the Wiener filter and linear contrast adjustment methods and the worst by Marr-Hildreth filter.

  16. Estimating Tree Height-Diameter Models with the Bayesian Method

    PubMed Central

    Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the “best” model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  17. General view of outside diameter welding stations of the saw ...

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

    General view of outside diameter welding stations of the saw line in bay 8 of the main pipe mill building looking northwest. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  18. 5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE ...

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

    5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE GATE HOUSE, LOOKING SOUTH. - Washington Water Power Spokane River Upper Falls Hydroelectric Development, Gates & Gate-Lifting Mechanisms, Spokane River, approximately 0.5 mile northeast of intersection of Spokane Falls Boulevard & Post Street, Spokane, Spokane County, WA

  19. Non-Contact EDDY Current Hole Eccentricity and Diameter Measurement

    NASA Technical Reports Server (NTRS)

    Chern, E. James

    1998-01-01

    Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact eddy current hole diameter and eccentricity measuring system. The operating principle is based on the eddy current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute eddy current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An eddy current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact eddy current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.

  20. View of wood stave penstocks (four feet in diameter) with ...

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

    View of wood stave penstocks (four feet in diameter) with steel bands, wood and steel frames; standing on top of penstocks is Doug Hamilton (right), Nooksack Falls hydro-plant operator for puget power, and Ken Rose (left) HAER Historian. - Nooksack Falls Hydroelectric Plant, Route 542, Glacier, Whatcom County, WA

  1. Minimum tube diameters for steady propagation of gaseous detonations

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Ng, H. D.; Lee, J. H. S.

    2014-07-01

    Recent experimental results on detonation limits are reported in this paper. A parametric study was carried out to determine the minimum tube diameters for steady detonation propagation in five different hydrocarbon fuel-oxygen combustible mixtures and in five polycarbonate test tube diameters ranging from 50.8 mm down to a small scale of 1.5 mm. The wave propagation in the tube was monitored by optical fibers. By decreasing the initial pressure, hence the sensitivity of the mixture, the onset of limits is indicated by an abrupt drop in the steady detonation velocity after a short distance of travel. From the measured wave velocities inside the test tube, the critical pressure corresponding to the limit and the minimum tube diameters for the propagation of the detonation can be obtained. The present experimental results are in good agreement with previous studies and show that the measured minimum tube diameters can be reasonably estimated on the basis of the /3 rule over a wide range of conditions, where is the detonation cell size. These new data shall be useful for safety assessment in process industries and in developing and validating models for detonation limits.

  2. Downhole pumps for water sampling in small diameter wells

    USGS Publications Warehouse

    Koopman, F. C.

    1979-01-01

    The relatively high cost and difficulty in locating a source of pumps for use in obtaining ground-water samples from small-diameter wells has demonstrated a need for this report. Criteria for selection of a pump and pumping equipment to meet specific requirements has been tabulated to assist field personnel in making a selection from commercial sources. (Kosco-USGS)

  3. Estimating tree height-diameter models with the Bayesian method.

    PubMed

    Zhang, Xiongqing; Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the "best" model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  4. Continuous measurement of vascular diameters via television microscopy.

    PubMed

    Devaney, M J; Rathke, J E; Bartel, R W; Mcdonald, J E; Wiegman, D L; Miller, F N; Harris, P D

    1976-01-01

    In the past 10 years, microcirculation studies have emphasized quantitative measurements of microvascular diameters to characterize in vivo small vessel responses to experimental forcings such as hemorrhage, anesthesia, and hypoxia. We have developed an instrument to obtain continuous diameter measurements of a small artery and vein (40-200 mu) via closed-circuit television microscopy. The outputs are analog voltages proportional to the vessel diameters. Video processing is limited to two image areas termed "windows," which are defined by markers on the monitor and positioned over separate vertically aligned vessels. Each vessel, which appears darker than the surrounding tissue, is located by comparing the video signal to a reference voltage that adapts to changes in the relative contrast within the window. In the presence of a vessel, a ramp voltage is generated, the peak value of which is proportional to the vessel diameter. These peaks are averaged over the 15-video lines of the window and over several video frames to reduce noise sensitivity. In order to accommodate preparation movement such as skeletal muscle contraction, window position and width automatically adapt to changes in vessel position and width. Visual verification of system performance is provided by clamping the video signal to white on that portion of the image which the instrument identifies as vessel. PMID:950283

  5. Genetic and Environmental Effects on the Abdominal Aortic Diameter Development

    PubMed Central

    Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Littvay, Levente; Garami, Zsolt; Karlinger, Kinga; Berczi, Viktor

    2016-01-01

    Background Configuration of the abdominal aorta is related to healthy aging and a variety of disorders. Objectives We aimed to assess heritable and environmental effects on the abdominal aortic diameter. Methods 114 adult (69 monozygotic, 45 same-sex dizygotic) twin pairs (mean age 43.6 ± 16.3 years) underwent abdominal ultrasound with Esaote MyLab 70X ultrasound machine to visualize the abdominal aorta below the level of the origin of the renal arteries and 1-3 cm above the bifurcation. Results Age- and sex-adjusted heritability of the abdominal aortic diameter below the level of the origin of the renal arteries was 40% [95% confidence interval (CI), 14 to 67%] and 55% above the aortic bifurcation (95% CI, 45 to 70%). None of the aortic diameters showed common environmental effects, but unshared environmental effects were responsible for 60% and 45% of the traits, respectively. Conclusions Our analysis documents the moderate heritability and its segment-specific difference of the abdominal aortic diameter. The moderate part of variance was explained by unshared environmental components, emphasizing the importance of lifestyle factors in primary prevention. Further studies in this field may guide future gene-mapping efforts and investigate specific lifestyle factors to prevent abdominal aortic dilatation and its complications. PMID:26559855

  6. Nuclear criticality safety calculational analysis for small-diameter containers

    SciTech Connect

    LeTellier, M.S.; Smallwood, D.J.; Henkel, J.A.

    1995-11-01

    This report documents calculations performed to establish a technical basis for the nuclear criticality safety of favorable geometry containers, sometimes referred to as 5-inch containers, in use at the Portsmouth Gaseous Diffusion Plant. A list of containers currently used in the plant is shown in Table 1.0-1. These containers are currently used throughout the plant with no mass limits. The use of containers with geometries or material types other than those addressed in this evaluation must be bounded by this analysis or have an additional analysis performed. The following five basic container geometries were modeled and bound all container geometries in Table 1.0-1: (1) 4.32-inch-diameter by 50-inch-high polyethylene bottle; (2) 5.0-inch-diameter by 24-inch-high polyethylene bottle; (3) 5.25-inch-diameter by 24-inch-high steel can ({open_quotes}F-can{close_quotes}); (4) 5.25-inch-diameter by 15-inch-high steel can ({open_quotes}Z-can{close_quotes}); and (5) 5.0-inch-diameter by 9-inch-high polybottle ({open_quotes}CO-4{close_quotes}). Each container type is evaluated using five basic reflection and interaction models that include single containers and multiple containers in normal and in credible abnormal conditions. The uranium materials evaluated are UO{sub 2}F{sub 2}+H{sub 2}O and UF{sub 4}+oil materials at 100% and 10% enrichments and U{sub 3}O{sub 8}, and H{sub 2}O at 100% enrichment. The design basis safe criticality limit for the Portsmouth facility is k{sub eff} + 2{sigma} < 0.95. The KENO study results may be used as the basis for evaluating general use of these containers in the plant.

  7. Changes in retinal microvascular diameter in patients with diabetes

    PubMed Central

    da Silva, Andréa Vasconcellos Batista; Gouvea, Sonia Alves; da Silva, Aurélio Paulo Batista; Bortolon, Saulo; Rodrigues, Anabel Nunes; Abreu, Glaucia Rodrigues; Herkenhoff, Fernando Luiz

    2015-01-01

    Background and objectives Diabetic retinopathy is the main microvascular complication in diabetes mellitus and needs to be diagnosed early to prevent severe sight-threatening retinopathy. The purpose of this study was to quantify the retinal microvasculature pattern and analyze the influence of blood glucose level and the duration of diabetes mellitus on the retinal microvasculature. Methods Two groups were analyzed: patients with diabetes (N=26) and patients without diabetes, ie, controls (N=26). A quantitative semiautomated method analyzed retinal microvasculature. The diameters of arterioles and venules were measured. The total numbers of arterioles and venules were counted. The ratio of arteriole diameter to venule diameter was calculated. The retinal microvasculature pattern was related to clinical and biochemical parameters. Results Patients with diabetes exhibited larger venule diameters in the upper temporal quadrant of the retina compared to the lower temporal quadrant (124.85±38.03 µm vs 102.92±15.69 µm; P<0.01). Patients with diabetes for 5 or more years had larger venule diameters in the upper temporal quadrant than patients without diabetes (141.62±44.44 vs 112.58±32.11 µm; P<0.05). The degree of venodilation in the upper temporal quadrant was positively correlated with blood glucose level and the estimated duration of diabetes mellitus. Interpretation and conclusion The employed quantitative method demonstrated that patients with diabetes exhibited venule dilation in the upper temporal quadrant, and the duration of diabetes mellitus was positively correlated with blood glucose level. Therefore, the early assessment of retinal microvascular changes is possible prior to the onset of diabetic retinopathy. PMID:26345217

  8. Two-group interfacial area transport equation in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Smith, Todd Ryan

    2002-01-01

    The closure relations for the two-group interfacial area transport equation (LATE) by which the changes of interfacial area concentration can be dynamically modeled are set forth in this thesis for the case of large diameter pipes. In the two-group formulation, the sources and sink terms are established by mechanistic modeling of the intra-group and inter-group transport of the bubbles based on five major bubble interaction mechanisms. These mechanisms are bubble coalescence as a result of random collision, RC, wake entrainment, WE, bubble break-up due to turbulent impact, TI, small bubble shearing-off of large bubbles, SO, and bubble break-up due to surface instability for large bubbles, SI. The models developed are supported by experiments using a four-sensor conductivity probe in large diameter test sections, 10.16 cm and 15.24 cm in diameter. A total of 31 different flow conditions under atmospheric pressure are examined in the bubbly to churn-turbulent flow regimes. The local flow parameters measured by the multi-sensor conductivity probe include the local time-averaged void fraction, interfacial area concentration, bubble Sauter mean diameter, interfacial velocity, and interface frequency for the two groups of bubbles. The model is evaluated against the extensive database and good agreement is obtained between the model predictions and the experimental data. The average error based on the total interfacial area concentration is around 7.0% for interfacial area concentration in both test sections. Recirculation in the large pipes is given special treatment in the measurement analysis. Using upwards and downwards facing probes, information on the missing bubble signals is obtained which is used to correct the local data by either the Effective Bubble Number or Intrusiveness Factor Method. The correction to void fraction is found to be about a 12% increase in the local area averaged value, while interfacial area concentration may increase upwards of 60% in the

  9. Concentrating Radioactivity

    ERIC Educational Resources Information Center

    Herrmann, Richard A.

    1974-01-01

    By concentrating radioactivity contained on luminous dials, a teacher can make a high reading source for classroom experiments on radiation. The preparation of the source and its uses are described. (DT)

  10. Helical magneto-cumulative generator 280 mm in diameter

    NASA Astrophysics Data System (ADS)

    Demidov, V. A.; Kazakov, S. A.; Boriskin, A. S.; Vlasov, Yu. V.; Yanenko, V. A.; Nikolaev, N. I.; Volodchenkov, S. I.

    2015-01-01

    Several possibilities of preamplifier energy and power increasing are considered: using a more powerful (HMX-based) conical HE-charge in the central tube of the magneto-cumulative generator, using a magnetic flux finish pressing out device with axial initiation of the HE charge, and increasing the inner diameter of the helix. A magneto-cumulative generator (MCG) with a helix 280 mm in diameter (MCG-280) is developed. The new preamplifier has a power of ≈400 GW and is able to power a ten-element DMCG480 with an initial inductance of ≈0.2 µH by a current of ≈10 MA with a characteristic current rise time (by a factor of e at the final stage of its operation) τ e = 32 µs.

  11. Angular diameter distances reconsidered in the Newman and Penrose formalism

    NASA Astrophysics Data System (ADS)

    Kling, Thomas P.; Aly, Aly

    2016-02-01

    Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.

  12. Steering knuckle diameter measurement based on optical 3D scanning

    NASA Astrophysics Data System (ADS)

    Song, Li-mei; Li, Da-peng; Chang, Yu-lan; Xi, Jiang-tao; Guo, Qing-hua

    2014-11-01

    To achieve accurate measurements, the creating a fitting hole for internal diameter (CFHID) measurement method and the establishing multi-sectional curve for external diameter (EMCED) measurement method are proposed in this paper, which are based on computer vision principle and three-dimensional (3D) reconstruction. The methods are able to highlight the 3D characteristics of the scanned object and to achieve the accurate measurement of 3D data. It can create favorable conditions for realizing the reverse design and 3D reconstruction of scanned object. These methods can also be applied to dangerous work environment or the occasion that traditional contact measurement can not meet the demands, and they can improve the security in measurement.

  13. Predicting The Tube Diameter For Polymer Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2005-03-01

    A simple conjecture, relating the tube diameter to a characteristic length called the packing length, works well for all flexible entangled polymer melts. This is a remarkable result, because the tube diameter represents the confining effect of uncrossability of the chains, whereas the packing length is determined only by a chain's bulkiness and flexibility. I extend this conjecture to solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of blobs per entanglement strand is not a constant as had been previously assumed, but depends on the ratio of the packing length to the thermal blob size. Finally, I suggest that the packing length can be related to the Gauss winding number density, thus providing a topological basis for the conjecture.

  14. Large Diameter Shuttle Launched-AEM (LDSL-AEM) study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A technical description of a Large Diameter Shuttle Launched-AEM (LDSL-AEM), an AEM base module adapted to carry 5 ft diameter payloads in the shuttle with propulsion for carrying payloads to higher altitude orbits from a 150 NM shuttle orbit, is described. The AEM is designed for launch on the scout launch vehicle. Onboard equipment provides capability to despin, acquire the earth, and control the vehicle in an earth pointing mode using reaction wheels for torque with magnets for all attitude acquisition, wheel desaturation, and nutation damping. Earth sensors in the wheels provide pitch and roll attitude. This system provides autonomous control capability to 1 degree in pitch and roll and 2 degrees in yaw. The attitude can be determined to .5 degrees in pitch and roll and 2 degrees in yaw.

  15. EFFECT OF PARTICLE DIAMETER ON EXCLUSION-ZONE SIZE

    PubMed Central

    NHAN, D.T.; POLLACK, G.H.

    2011-01-01

    Particles and solutes are excluded from the vicinity of hydrophilic surfaces, leaving large microsphere-free regions known as exclusion zones (EZs). Prior work had indicated that EZs could extend to distances of up to several hundred micrometers from the nucleating surface. These observations were made on large, extended surfaces, leaving open the question whether EZ size might depend on the characteristic dimension of the excluding surface. We placed one or few ion-exchange-resin beads whose diameters varied from 15 μm to 300 μm in cuvettes. The beads were suffused with aqueous microsphere suspensions for observing the surfaces’ exclusionary behavior. Results showed a direct relation between bead size and EZ size over the full range of bead diameter, implying a similar relation for smaller particles or molecules, perhaps extending beyond the resolution of the light microscope. PMID:22389653

  16. The diameter and thermal inertia of 433 Eros

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1976-01-01

    Radiometry of Eros at 10 and 20 micrometers demonstrates that the thermal conductivity of the upper centimeter of the surface is approximately as low as that of the moon, suggesting that the asteroid has a regolith of highly porous rocky material. When combined with photoelectric photometry, these infrared measurements yield an effective diameter of Eros at maximum light of 22 plus or minus 2 km and a geometric albedo of 0.18 plus or minus 0.03.

  17. Cohesive/cohesionless sediment transition diameter from settling velocity data

    NASA Astrophysics Data System (ADS)

    Mehta, Ashish J.; Letter, Joseph V.

    2015-09-01

    Mathematical models designed to simulate the movement of cohesive and cohesionless particles require as input the diameter d T specifying the transition between these two transport modes. As an effort to identify this diameter, Migniot (La Houille Blanche, 7, 591-620, 1968) measured in a water-filled column the settling velocities of flocs and respective deflocculated particles of mainly mineral cohesive sediments. The data were plotted as the ratio of the floc settling velocity to the particle velocity, called the flocculation factor F f , against particle diameter d s . The trend line was found to approximately follow an empirical power-law such that F f increased rapidly as d s decreased below d T estimated to be about 30 μm at F f = 1. Assuming fractal self-similarity among falling flocs, the power-law exponent of 5/3 is shown to correspond to a fractal dimension of 2.65 implying that the flocs were densely packed. The diameter d T depends on the electrochemical properties of the suspended particles as well as the kinetics of floc growth and breakup, hence to an extent on the method of determination of d T . Its value deduced more directly from measurement of the critical shear stress for erosion of flocs at the surface of cohesive sediment beds has been reported to be about 10 μm, which is lower than 30 μm. Among other reasons, it is likely that the difference is rooted in the limited experimental information available as well as difficulty in characterizing the effect of highly graded distributions of the particle settling velocity.

  18. NEOWISE Diameters and Albedos V1.0

    NASA Astrophysics Data System (ADS)

    Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; Nugent, C. R.; Sonnett, S. M.; Stevenson, R. A.; Wright, E. L.

    2016-06-01

    This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by NEOWISE during the fully cryogenic, 3-band cryo, post-cryo and NEOWISE-Reactivation Year 1 operations. It contains data covering near-Earth asteroids, Main Belt asteroids, active Main Belt objects, Hildas, Jupiter Trojans, Centaurs, and Jovian and Saturnian irregular satellites. Methodology for physical property determination is described in the referenced articles.

  19. Left Ventricular Diameter and Risk Stratification for Sudden Cardiac Death

    PubMed Central

    Narayanan, Kumar; Reinier, Kyndaron; Teodorescu, Carmen; Uy‐Evanado, Audrey; Aleong, Ryan; Chugh, Harpriya; Nichols, Gregory A.; Gunson, Karen; London, Barry; Jui, Jonathan; Chugh, Sumeet S.

    2014-01-01

    Background Left ventricular (LV) diameter is routinely measured on the echocardiogram but has not been jointly evaluated with the ejection fraction (EF) for risk stratification of sudden cardiac death (SCD). Methods and Results From a large ongoing community‐based study of SCD (The Oregon Sudden Unexpected Death Study; population ≈1 million), SCD cases were compared with geographic controls. LVEF and LV diameter, measured using the LV internal dimension in diastole (categorized as normal, mild, moderate, or severe dilatation using American Society of Echocardiography definitions) were assessed from echocardiograms prior but unrelated to the SCD event. Cases (n=418; 69.5±13.8 years), compared with controls (n=329; 67.7±11.9 years), more commonly had severe LV dysfunction (EF ≤35%; 30.5% versus 18.8%; P<0.01) and larger LV diameter (52.2±10.5 mm versus 49.7±7.9 mm; P<0.01). Moderate or severe LV dilatation (16.3% versus 8.2%; P=0.001) and severe LV dilatation (8.1% versus 2.1%; P<0.001) were significantly more frequent in cases. In multivariable analysis, severe LV dilatation was an independent predictor of SCD (odds ratio 2.5 [95% CI 1.03 to 5.9]; P=0.04). In addition, subjects with both EF ≤35% and severe LV dilatation had higher odds for SCD compared with those with low EF only (odds ratio 3.8 [95% CI 1.5 to 10.2] for both versus 1.7 [95% CI 1.2 to 2.5] for low EF only), suggesting that severe LV dilatation additively increased SCD risk. Conclusion LV diameter may contribute to risk stratification for SCD independent of the LVEF. This readily available echocardiographic measure warrants further prospective evaluation. PMID:25227407

  20. Cost of Czochralski wafers as a function of diameter

    SciTech Connect

    Leipold, M.H.; Radics, C.; Kachare, A.

    1980-02-15

    The impact of diameter in the range of 10 to 15 cm on the cost of wafers sliced from Czochralski ingots is analyzed. Increasing silicon waste and decreasing ingot cost with increasing ingot size are estimated along with projected costs. Results indicate a small but continuous decrease in sheet cost with increasing ingot size in this size range. Sheet costs including silicon are projected to be $50 to $60/m/sup 2/ (1980 $) depending upon technique used.

  1. Measuring angular diameter distances of strong gravitational lenses

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.

    2015-11-01

    The distance-redshift relation plays a fundamental role in constraining cosmological models. In this paper, we show that measurements of positions and time delays of strongly lensed images of a background galaxy, as well as those of the velocity dispersion and mass profile of a lens galaxy, can be combined to extract the angular diameter distance of the lens galaxy. Physically, as the velocity dispersion and the time delay give a gravitational potential (GM/r) and a mass (GM) of the lens, respectively, dividing them gives a physical size (r) of the lens. Comparing the physical size with the image positions of a lensed galaxy gives the angular diameter distance to the lens. A mismatch between the exact locations at which these measurements are made can be corrected by measuring a local slope of the mass profile. We expand on the original idea put forward by Paraficz and Hjorth, who analyzed singular isothermal lenses, by allowing for an arbitrary slope of a power-law spherical mass density profile, an external convergence, and an anisotropic velocity dispersion. We find that the effect of external convergence cancels out when dividing the time delays and velocity dispersion measurements. We derive a formula for the uncertainty in the angular diameter distance in terms of the uncertainties in the observables. As an application, we use two existing strong lens systems, B1608+656 (zL=0.6304) and RXJ1131-1231 (zL=0.295), to show that the uncertainty in the inferred angular diameter distances is dominated by that in the velocity dispersion, σ2, and its anisotropy. We find that the current data on these systems should yield about 16% uncertainty in DA per object. This improves to 13% when we measure σ2 at the so-called sweet-spot radius. Achieving 7% is possible if we can determine σ2 with 5% precision.

  2. Astronaut Assembly of a 14-Meter-Diameter Microwave Antenna

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Astronaut Jerry Ross is shown assembling a portion of a 14-meter-diameter truss structure in NASAs Neutral Buoyancy Simulator at the Marshall Space Flight Center. The structure is part of a large microwave antenna designed for space-based monitoring of soil moisture levels and ocean temperatures. The underwater assembly tests demonstrated that two astronauts could construct the large antenna in approximately 4-6 hours in space.

  3. Time-delay cosmography: increased leverage with angular diameter distances

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.; Huterer, D.

    2016-04-01

    Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used in forecasting cosmographic constraints. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Specifically, the angular diameter distance plays a crucial role in breaking the degeneracy between the curvature of the Universe and the time-varying equation of state of dark energy. Using a mock sample of 55 bright quadruple lens systems based on expectations for ongoing/future imaging surveys, we find that adding the angular diameter distance information to the time-delay distance information and the Planck's measurements of the cosmic microwave background anisotropies improves the constraint on the constant equation of state by 30%, on the time variation in the equation of state by a factor of two, and on the Hubble constant in the flat ΛCDM model by a factor of two. Therefore, previous forecasts for the statistical power of time-delay systems were overly pessimistic, i.e., time-delay systems are more powerful than previously appreciated.

  4. Diameter dependent thermoelectric properties of individual SnTe nanowires

    DOE PAGESBeta

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowiremore » diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.« less

  5. J-integral of circumferential crack in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Chao, Yuh J.; Sutton, M. A.; Lam, P. S.; Mertz, G. E.

    Large diameter thin-walled pipes are encountered in a low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks, are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using the finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used with strain hardening exponents (n) that range from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063(pi) to 0.5(pi). Results are tabulated for use with the EPRI estimation scheme.

  6. Mechanical analysis of conventional and small diameter conical implant abutments

    PubMed Central

    Moris, Izabela Cristina Maurício; Faria, Adriana Cláudia Lapria; de Mattos, Maria da Gloria Chiarello; Ribeiro, Ricardo Faria

    2012-01-01

    PURPOSE The aim of the present study was to evaluate if a smaller morse taper abutment has a negative effect on the fracture resistance of implant-abutment connections under oblique compressive loads compared to a conventional abutment. MATERIALS AND METHODS Twenty morse taper conventional abutments (4.8 mm diameter) and smaller abutments (3.8 mm diameter) were tightened (20 Ncm) to their respective implants (3.5 × 11 mm) and after a 10 minute interval, implant/abutment assemblies were subjected to static compressive test, performed in a universal test machine with 1 mm/min displacement, at 45° inclination. The maximum deformation force was determined. Data were statistically analyzed by student t test. RESULTS Maximum deformation force of 4.8 mm and 3.8 mm abutments was approximately 95.33 kgf and 95.25 kgf, respectively, but no fractures were noted after mechanical test. Statistical analysis demonstrated that the evaluated abutments were statistically similar (P=.230). CONCLUSION Abutment measuring 3.8 mm in diameter (reduced) presented mechanical properties similar to 4.8 mm (conventional) abutments, enabling its clinical use as indicated. PMID:22977724

  7. Diameter dependent thermoelectric properties of individual SnTe nanowires

    SciTech Connect

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowire diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.

  8. The method for detecting diffusion ring diameter in Hemagglutinin measuring

    NASA Astrophysics Data System (ADS)

    Jing, Wenbo; Liu, Xue; Duan, Jin; Wang, Xiao-man

    2014-11-01

    The diffuser ring diameter measurement is the most critical in hemagglutinin Measuring. The traditional methods, such as a vernier caliper or high-definition scanned images are subjective and low for the measurement data reliability. Propose high-resolution diffusion ring image for drop-resolution processing, adaptive Canny operator and local detection method to extract complete and clear diffusion ring boundaries, and finally make use of polynomial interpolation algorithm to make diffusion ring outer boundary pixel coordinates achieve sub-pixel accuracy and the least-squares fitting circle algorithm to calculate the precise center of the circle and the diameter of the diffuser ring. Experimental results show that the method detection time is only 63.61ms, which is a faster speed; diffuser ring diameter estimation error can achieve 0.55 pixel, high stability in experimental data. This method is adapted to the various types of influenza vaccine hemagglutinin content measurements, and has important value in the influenza vaccine quality detection.

  9. Diameter Dependent Thermoelectric Properties of Individual SnTe Nanowires

    NASA Astrophysics Data System (ADS)

    Xu, E. Z.; Li, Z.; Martinez, J.; Sinitsyn, N.; Htoon, H.; Li, N.; Swartzentruber, B.; Hollingsworth, J.; Wang, J.; Zhang, S. X.

    2015-03-01

    Tin telluride (SnTe), a newly discovered topological crystalline insulator, has recently been suggested to be a promising thermoelectric material. In this work, we report on a systematic study of the thermoelectric properties of individual single-crystalline SnTe nanowires with different diameters. Measurements of thermopower, electrical conductivity and thermal conductivity were carried out on the same nanowires over a temperature range of 25 - 300 K. While the electrical conductivity does not show a strong diameter dependence, we found that the thermopower increases by a factor of two when the nanowire diameter is decreased from 913 nm to 218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may be attributed to the enhanced phonon - surface boundary scattering and phonon-defect scattering. We further calculated the temperature dependent figure of merit ZT for each individual nanowire. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-AC04-94AL85000). We acknowledge support by the Los Alamos LDRD program.

  10. Tree height-diameter allometry across the United States.

    PubMed

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-03-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height-diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  11. Tree height–diameter allometry across the United States

    PubMed Central

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-01-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height–diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  12. Diameter dependent thermoelectric properties of individual SnTe nanowires.

    PubMed

    Xu, E Z; Li, Z; Martinez, J A; Sinitsyn, N; Htoon, H; Li, Nan; Swartzentruber, B; Hollingsworth, J A; Wang, Jian; Zhang, S X

    2015-02-21

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a promising thermoelectric material. In this work, we report on the first thermoelectric study of individual single-crystalline SnTe nanowires with different diameters ranging from ∼218 to ∼913 nm. Measurements of thermopower S, electrical conductivity σ and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25-300 K. While the electrical conductivity does not show a strong diameter dependence, the thermopower increases by a factor of two when the nanowire diameter is decreased from ∼913 nm to ∼218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may arise from the enhanced phonon - surface boundary scattering and phonon-defect scattering. Temperature dependent figure of merit ZT was determined for individual nanowires and the achieved maximum value at room temperature is about three times higher than that in bulk samples of comparable carrier density. PMID:25623253

  13. Subwavelength-diameter silica wires for microscale optical components

    NASA Astrophysics Data System (ADS)

    Tong, Limin; Mazur, Eric

    2005-04-01

    Subwavelength-diameter silica wires fabricated using a taper-drawing approach exhibit excellent diameter uniformity and atomic-level smoothness, making them suitable for low-loss optical wave guiding from the UV to the near-infrared. Such air-clad silica wires can be used as single-mode waveguides; depending on wavelength and wire diameter, they either tightly confine the optical fields or leave a certain amount of guided energy outside the wire in the form of evanescent waves. Using these wire waveguides as building blocks we assembled microscale optical components such as linear waveguides, waveguide bends and branch couplers on a low-index, non-dissipative silica aerogel substrate. These components are much smaller than comparable existing devices and have low optical loss, indicating that the wire-assembly technique presented here has great potential for developing microphotonics devices for future applications in a variety of fields such as optical communication, optical sensing and high-density optical integration.

  14. Large-diameter carbon-composite monofilaments. [production method and characteristics of carbon composite monofilaments

    NASA Technical Reports Server (NTRS)

    Bradshaw, W. G.; Pinoli, P. C.; Karlak, R. F.

    1974-01-01

    Large-diameter carbon composite monofilaments with high strength and high modulus were produced by pregging multifiber carbon bundles with suitable organic resins and pyrolysing them together. Two approaches were developed to increase the utilization of fiber tensile strength by minimizing stress concentration defects induced by dissimilar shrinkage during pyrolysis. These were matrix modification to improve char yield and strain-to-failure and fiber-matrix copyrolysis to alleviate matrix cracking. Highest tensile strength and modulus were obtained by heat treatments to 2873 K to match fiber and matrix strain-to-failure and develop maximum monofilament tensile-strength and elastic modulus.

  15. Soot properties and species measurements in a two-meter diameter JP-8 pool fire.

    SciTech Connect

    Shaddix, Christopher R.; Murphy, Jeffrey J.

    2003-06-01

    A tunable diode laser absorption spectroscopy probe was used to measure in situ soot properties and species concentrations in two-meter diameter JP-8 pool fires. Twelve tests were performed at the Lurance Canyon Bum Site operated by Sandia in Albuquerque, New Mexico. Seven of the tests were conducted with the probe positioned close to the centerline at heights above the pool surface ranging from 0.5 m to 2.0 mm in 0.25 m increments. For the remaining five tests, the probe was positioned at two heights 0.3 m from the centerline and at three heights 0.5 m from the centerline. Soot concentration was determined using a soot absorption measurement based on the transmission of a solid-state red laser (635 nm) through the 3.7 cm long probe volume. Soot temperature and a second estimate of soot concentration were measured using two-color optical pyrometry at 850 nm and la00 nm. The effective data rate for these measurements was 10 Mz. Finally, tunable diode laser absorption spectroscopy was used to qualitatively estimate water concentration at a rate of 1 kHz. To improve signal-to-noise, these data were averaged to an effective rate of 2 Hz. The results presented include the statistics, probability density functions, and spectral density functions of soot concentration, soot temperature, and approximate water concentrations at the different measurement locations throughout the fire.

  16. Effect of fibroin sponge coating on in vivo performance of knitted silk small diameter vascular grafts

    PubMed Central

    Fukayama, Toshiharu; Ozai, Yusuke; Shimokawadoko, Haruka; Aytemiz, Derya; Tanaka, Ryou; Machida, Noboru; Asakura, Tetsuo

    2015-01-01

    ABSTRACT Vascular grafts under 5 mm or less in diameter are not developed due to a problem caused by early thrombus formation, neointimal hyperplasia, etc. Bombyx mori silk fibroin (SF) which has biodegradability and tissue infiltration is focused as tube and coating material of vascular grafts. Coating is an important factor to maintain the strength of the anastomotic region of vascular grafts, and to prevent the blood leak from the vascular grafts after implantation. Therefore, in this research, we focused on the SF concentration of the coating solution, and tissue infiltration and remodeling were compared among each SF concentration. Silk poly (-ethylene) glycol diglycidyl ether (PGDE) coating with concentrations of 1.0%, 2.5%, 5.0%, and 7.5% SF were applied for the double-raschel knitted small-sized vessel with 1.5 mm diameter and 1cm in length. The grafts were implanted in the rat abdominal aorta and removed after 3 weeks or 3 months. Vascular grafts patency was monitored by ultrasound, and morphological evaluation was performed by histopathological examination. SF concentration had no significant effects on the patency rate. However, tissue infiltration was significantly higher in the sample of 2.5% SF in 3 weeks, and 1.0% and 2.5% SF in 3 months. Also, in comparison of length inside of the graft, stenosis were not found in 3 weeks, however, found with 5.0% and 7.5% in 3 months. From these results, it is clear that 2.5% SF coating is the most suitable concentration, based on the characteristics of less stenosis, early tissue infiltration, and less neointimal hyperplasia. PMID:26496652

  17. Parabolic solar concentrator

    NASA Astrophysics Data System (ADS)

    Tecpoyotl-Torres, M.; Campos-Alvarez, J.; Tellez-Alanis, F.; Sánchez-Mondragón, J.

    2006-08-01

    In this work we present the basis of the solar concentrator design, which has is located at Temixco, Morelos, Mexico. For this purpose, this place is ideal due to its geographic and climatic conditions, and in addition, because it accounts with the greatest constant illumination in Mexico. For the construction of the concentrator we use a recycled parabolic plate of a telecommunications satellite dish (NEC). This plate was totally covered with Aluminum. The opening diameter is of 332 cm, the focal length is of 83 cm and the opening angle is of 90°. The geometry of the plate guaranties that the incident beams, will be collected at the focus. The mechanical treatment of the plate produces an average reflectance of 75% in the visible region of the solar spectrum, and of 92% for wavelengths up to 3μm in the infrared region. We obtain up to 2000°C of temperature concentration with this setup. The reflectance can be greatly improved, but did not consider it as typical practical use. The energy obtained can be applied to conditions that require of those high calorific energies. In order to optimize the operation of the concentrator we use a control circuit designed to track the apparent sun position.

  18. Data Concentrator

    NASA Technical Reports Server (NTRS)

    Willett, Mike

    2015-01-01

    Orbital Research, Inc., developed, built, and tested three high-temperature components for use in the design of a data concentrator module in distributed turbine engine control. The concentrator receives analog and digital signals related to turbine engine control and communicates with a full authority digital engine control (FADEC) or high-level command processor. This data concentrator follows the Distributed Engine Controls Working Group (DECWG) roadmap for turbine engine distributed controls communication development that operates at temperatures at least up to 225 C. In Phase I, Orbital Research developed detailed specifications for each component needed for the system and defined the total system specifications. This entailed a combination of system design, compiling existing component specifications, laboratory testing, and simulation. The results showed the feasibility of the data concentrator. Phase II of this project focused on three key objectives. The first objective was to update the data concentrator design modifications from DECWG and prime contractors. Secondly, the project defined requirements for the three new high-temperature, application-specific integrated circuits (ASICs): one-time programmable (OTP), transient voltage suppression (TVS), and 3.3V. Finally, the project validated each design by testing over temperature and under load.

  19. Estimating the Average Diameter of a Population of Spheres from Observed Diameters of Random Two-Dimensional Sections

    NASA Technical Reports Server (NTRS)

    Kong, Maiying; Bhattacharya, Rabi N.; James, Christina; Basu, Abhijit

    2003-01-01

    Size distributions of chondrules, volcanic fire-fountain or impact glass spherules, or of immiscible globules in silicate melts (e.g., in basaltic mesostasis, agglutinitic glass, impact melt sheets) are imperfectly known because the spherical objects are usually so strongly embedded in the bulk samples that they are nearly impossible to separate. Hence, measurements are confined to two-dimensional sections, e.g. polished thin sections that are commonly examined under reflected light optical or backscattered electron microscopy. Three kinds of approaches exist in the geologic literature for estimating the mean real diameter of a population of 3D spheres from 2D observations: (1) a stereological approach with complicated calculations; (2) an empirical approach in which independent 3D size measurements of a population of spheres separated from their parent sample and their 2D cross sectional diameters in thin sections have produced an array of somewhat contested conversion equations; and (3) measuring pairs of 2D diameters of upper and lower surfaces of cross sections each sphere in thin sections using transmitted light microscopy. We describe an entirely probabilistic approach and propose a simple factor of 4/x (approximately equal to 1.27) to convert the 2D mean size to 3D mean size.

  20. Characterization of Large Diameter PMTs for Kaon Cerenkov Detector

    NASA Astrophysics Data System (ADS)

    Boylan, Derek

    2014-09-01

    The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in particular as the aerogel refractive index decreases. The Hall C aerogel detector uses the Photonis XP4500 large-diameter photomultiplier tubes (PMT) in order to detect these small traces of light. The purpose of this project is to explore the performance of alternative large-diameter PMTs and compares them to that of the XP4500. The PMT uniformity across the photocathode was characterized through scans along the surface of the PMT with a low-intensity, focused LED, thereby creating a 3D image of the gain at each section. The method of scanning consists of a two axis step motor moving an LED light source on a 100 x 100 grid parallel to the face of the PMT, with 30 pulses of light from the LED at each step. The step motor scans with a resolution of 1.2 mm. Scans conducted in this manner result in high resolution images which pick up most sensitive/non-sensitive spots on the photocathode. In this presentation I will present the results of the characterization and performance test of the XP4500 and comparison to alternative large-diameter PMT models. The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in

  1. Europa's Surface Properties from Secondary Crater Depth/Diameter Ratios

    NASA Astrophysics Data System (ADS)

    Bierhaus, Edward B.; Chapman, C. R.; Schenk, P. M.

    2007-10-01

    We find that secondary craters on Europa tend towards smaller depth-to-diameter (d/D) ratios than primary craters, consistent with observations on other cratered surfaces (the Moon and Mars). We measure craters near the resolution limit, so an individual crater profile is noisy and not definitive; however, the aggregate statistics of over 100 profiles demonstrate a systematic trend for shallow profiles. Primary crater collapse from a simple bowl shape to a more shallow profile (or more complex morphology) is a function of material strength and surface gravity: the transition will happen at smaller diameters for weaker surfaces or for those with higher surface gravity. However, secondary craters are usually more shallow at a given diameter than a primary, perhaps due to lower fragment impact speeds or self-burial during multiple, simultaneous impacts (McEwen and Bierhaus 2005). To first order, very cold ice and rock respond similarly to impact cratering, with predictable differences due to differences in strength, equations of state, etc. But Europa's surface is enigmatic: pervasive fracturing suggests a solid, competent material; chaos features and mobility of blocks within chaos suggest fluid-like behavior; radar measurements (Black et al. 2001) support the presence of a porous surface layer, as do thermal inertia models (Spencer 2004) -- though the thermal inertia only addresses the uppermost few cm. The d/D similarity of secondary craters on icy Europa and rocky surfaces (the Moon and Mars), whose surface evolutions are dominated by different processes, implies that either (a) material properties play a small role in the morphology of secondary craters, or (b) whatever processes operate to create Europa's surface features must leave the ice in a form that responds to cratering in a manner consistent with regoliths on other solar system surfaces. NASA Outer Planets Program funds this research.

  2. Automatic segmentation and diameter measurement of coronary artery vessels

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Tang, Zhenyu; Pauli, Josef

    2011-03-01

    This work presents a hybrid method for 2D artery vessel segmentation and diameter measurement in X-Ray angiograms. The proposed method is novel in that tracking-based and model-based approaches are combined. A robust and efficient tracking template, the "annular template", is devised for vessel tracking. It can readily be applied on X-Ray angiograms without any preprocessing. Starting from an initial tracking point given by the user the tracking algorithm iteratively repositions the annular template and thereby detects the vessel boundaries and possible bifurcations. With a user selected end point the tracking process results in a set of points that describes the contour and topology of an artery vessel segment between the initial and end points. A "boundary correction and interpolation" operation refines the extracted points which initialize the Snakes algorithm. Boundary correction adjusts the points to ensure that they lie on the vessel segment of interest. Boundary interpolation adds more points, so that there are sufficiently many points for the Snakes algorithm to generate a smooth and accurate vessel segmentation. After the application of Snakes the resulting points are sequentially connected to represent the vessel contour. Then, the diameters are measured along the extracted vessel contour. The segmentation and measurement results are compared with manually extracted and measured vessel segments. The average Precision, Recall and Jaccard Index of 21 vessel samples are 91.5%, 92.1% and 84.9%, respectively. Compared with ground truth measurements of diameters the average relative error is 8.2%, and the average absolute error is 1.13 pixels.

  3. Development of Small Diameter Nanofiber Tissue Engineered Arterial Grafts

    PubMed Central

    Tara, Shuhei; Rocco, Kevin A.; Bagi, Paul S.; Yi, Tai; Udelsman, Brooks; Zhuang, Zhen W.; Cleary, Muriel; Iwakiri, Yasuko; Breuer, Christopher K.; Shinoka, Toshiharu

    2015-01-01

    The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell. PMID:25830942

  4. A solar cycle lengthwise series of solar diameter measurements

    NASA Astrophysics Data System (ADS)

    Penna, J. L.; Andrei, A. H.; Boscardin, S. C.; Neto, E. Reis; d'Ávila, V. A.

    2010-02-01

    The measurements of the solar photospheric diameter rank among the most difficult astronomic observations. Reasons for this are the fuzzy definition of the limb, the SNR excess, and the adverse daytime seeing condition. As a consequence there are very few lengthy and consistent time series of such measurements. Using modern techniques, just the series from the IAG/USP and from Calern/OCA span more than one solar cycle. The Rio de Janeiro Group observations started in 1997, and therefore in 2008 one complete solar cycle time span can be analyzed. The series shares common principles of observation and analysis with the ones afore mentioned, and it is complementary on time to them. The distinctive features are the larger number of individual points and the improved precision. The series contains about 25,000 single observations, evenly distributed on a day-by-day basis. The typical error of a single observation is half an arc-second, enabling us to investigate variations at the expected level of tens of arc-second on a weekly basis. These features prompted to develop a new methodology for the investigation of the heliophysical scenarios leading to the observed variations, both on time and on heliolatitude. The algorithms rely on running averages and time shifts to derive the correlation and statistical incertitude for the comparison of the long term and major episodes variations of the solar diameter against activity markers. The results bring support to the correlation between the diameter variation and the solar activity, but evidentiating two different regimens for the long term trend and the major solar events.

  5. Cylindrical acoustic levitator/concentrator

    DOEpatents

    Kaduchak, Gregory; Sinha, Dipen N.

    2002-01-01

    A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.

  6. SERS Raman Sensor Based on Diameter-Modulated Sapphire Fiber

    SciTech Connect

    Shimoji, Yutaka

    2010-08-09

    Surface enhanced Raman scattering (SERS) has been observed using a sapphire fiber coated with gold nano-islands for the first time. The effect was found to be much weaker than what was observed with a similar fiber coated with silver nanoparticles. Diameter-modulated sapphire fibers have been successfully fabricated on a laser heated pedestal growth system. Such fibers have been found to give a modest increase in the collection efficiency of induced emission. However, the slow response of the SERS effect makes it unsuitable for process control applications.

  7. Assembly of gold nanoparticles of different diameters between nanogap electrodes

    SciTech Connect

    Cheon, Donguk; Kumar, Sanjeev; Kim, Gil-Ho

    2010-01-04

    Gold nanoparticles (NPs) of different diameters i.e., 5, 10, and 20 nm, were assembled between 20 nm gap electrodes using ac dielectrophoresis (DEP) process. DEP parameters, such as frequency, trapping time, and voltage of value 1 MHz, 1 s, and 2-3 V, respectively, led to the pearl-chain assembly corresponding to each type of NPs between 20 nm gap electrodes. Mutual DEP could be attributed to the NPs chaining in low field regions and subsequently the DEP force directs these chains to the trapping region. Such controlled assembly of individual NPs may find application in fabricating devices for molecular electronics.

  8. Hoop tensile strength testing of small diameter ceramic particles

    NASA Astrophysics Data System (ADS)

    Wereszczak, A. A.; Jadaan, O. M.; Lin, H.-T.; Champoux, G. J.; Ryan, D. P.

    2007-03-01

    A method to measure hoop tensile strength of 1-mm-diameter brittle ceramic spheres was demonstrated through the use of a 'C-sphere' flexure strength specimen. This innovative specimen geometry was chosen because a simple, monotonically increasing uniaxial compressive force produces a hoop tensile stress at the C-sphere's outer surface that ultimately initiates fracture. This enables strength quantification and strength-limiting-flaw identification of the sphere itself. Such strength information is relevant to design optimization and durability assessments of ceramic fuel particles and breeder/multiplier pebbles for fusion when particle surfaces are subjected to tensile stresses during their manufacturing or service.

  9. Magnetic configurations in 160 520-nm-diameter ferromagnetic rings

    NASA Astrophysics Data System (ADS)

    Castaño, F. J.; Ross, C. A.; Eilez, A.; Jung, W.; Frandsen, C.

    2004-04-01

    The remanent states and hysteretic behavior of thin-film magnetic rings has been investigated experimentally and by micromagnetic modeling. Rings of diameters 160 520 nm, made from Co using lift-off processing, show three distinct remanent states: a vortex state, an “onion” state with two head-on walls, and a “twisted” state containing a 360° wall. The range of stability of these states varies with ring geometry, with smaller width rings showing higher switching fields and greater variability.

  10. Radio source orientation and the angular diameter-redshift relation

    SciTech Connect

    Onuora, L.I. )

    1991-08-01

    The effect of a nonrandom source orientation on the angular diameter-redshift relation was considered for the 3CR sample of Laing et al., based on the 'unified' scheme of Barthel. For an inhomogeneous sample of objects displaying milliarcsecond scale structure, it was found that there was no evidence for a systematic variation for orientation angle with redshift. However, if it was assumed that quasars are closer to the line of sight than powerful extended radio galaxies, then the observed angular size-redshift relation could be interpreted in terms of source orientation, rather than linear size evolution. 14 refs.

  11. Predicting the Tube Diameter in Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2004-03-01

    A simple conjecture relating chain dimensions to the so-called ``tube diameter'', which represents the topological confining effect of entanglements on a chain, works well for all flexible entangled polymer melts. I extend this conjecture to semidilute solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of ``blobs'' per entanglement strand B is not a constant as had been previously assumed, but depends on the ratio of the packing length to the Edwards length. This unified picture is in agreement with existing data on semidilute solutions.

  12. Note: Computer controlled rotation mount for large diameter optics

    NASA Astrophysics Data System (ADS)

    Rakonjac, Ana; Roberts, Kris O.; Deb, Amita B.; Kjærgaard, Niels

    2013-02-01

    We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

  13. Structure Optimization and Evaluation of Small Adjustable Diameter Grinding Wheel

    NASA Astrophysics Data System (ADS)

    Yao, Yiyong; Li, Yuanyuan; Zhao, Liping; Zhao, Hu

    Focus on the uneven deformation of conventional adjustable diameter grinding wheel (ADGW), a structure optimization and evaluation method of ADGW was proposed in this paper. Firstly, the evaluation index system and structure optimization framework of ADGW was established to obtain the optimization objective of ADGW. Then a simulated experiment was provided. The flexible units of ADGW with different structures and geometries were selected to analyze the unevenness of deformation. The comparison results showed that the proposed method can improve the ADGW structures effectively and provide a technical approach for evaluating the structure design of ADGW.

  14. Tracking of vessel diameter fluctuations using digital image analysis

    NASA Astrophysics Data System (ADS)

    Aggarwal, Shanti J.; Yip, C.-Y.; Diller, Kenneth R.; Bovik, Alan C.

    1990-05-01

    An automatic digital image processing technique for vasomotion analysis in peripheral microcirculation at multiple sites simultaneously and in real time, is presented. The algorithm utilizes either fluorescent or bright field microimages of the vasculature as input. The video images are digitized and analyzed on-line by an IBM RT PC. Using digital filtering and edge detection, the technique allows simultaneous diameter measurement at more than one site. The sampling frequency is higher than 5 Hz when only one site is tracked. The performance of the algorithm is tested in the hamster cutaneous microcirculation.

  15. Refined Synthesis and Characterization of Controlled Diameter, Narrow Size Distribution Microparticles for Aerospace Research Applications

    NASA Technical Reports Server (NTRS)

    Tiemsin, Pacita I.; Wohl, Christopher J.

    2012-01-01

    Flow visualization using polystyrene microspheres (PSL)s has enabled researchers to learn a tremendous amount of information via particle based diagnostic techniques. To better accommodate wind tunnel researchers needs, PSL synthesis via dispersion polymerization has been carried out at NASA Langley Research Center since the late 1980s. When utilizing seed material for flow visualization, size and size distribution are of paramount importance. Therefore, the work described here focused on further refinement of PSL synthesis and characterization. Through controlled variation of synthetic conditions (chemical concentrations, solution stirring speed, temperature, etc.) a robust, controllable procedure was developed. The relationship between particle size and salt concentration, MgSO4, was identified enabling the determination of PSL diameters a priori. Suggestions of future topics related to PSL synthesis, stability, and size variation are also described.

  16. The Use of Narrow Diameter Implants in the Molar Area.

    PubMed

    Saad, M; Assaf, A; Gerges, E

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  17. The Use of Narrow Diameter Implants in the Molar Area

    PubMed Central

    Saad, M.; Assaf, A.; Gerges, E.

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  18. 33-Foot-Diameter Space Station Leading to Space Base

    NASA Technical Reports Server (NTRS)

    1969-01-01

    This picture illustrates a concept of a 33-Foot-Diameter Space Station Leading to a Space Base. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  19. Diameter of titanium nanotubes influences anti-bacterial efficacy

    NASA Astrophysics Data System (ADS)

    Ercan, Batur; Taylor, Erik; Alpaslan, Ece; Webster, Thomas J.

    2011-07-01

    Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.

  20. Allowable pillar to diameter ratio for strategic petroleum reserve caverns.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon

    2011-05-01

    This report compiles 3-D finite element analyses performed to evaluate the stability of Strategic Petroleum Reserve (SPR) caverns over multiple leach cycles. When oil is withdrawn from a cavern in salt using freshwater, the cavern enlarges. As a result, the pillar separating caverns in the SPR fields is reduced over time due to usage of the reserve. The enlarged cavern diameters and smaller pillars reduce underground stability. Advances in geomechanics modeling enable the allowable pillar to diameter ratio (P/D) to be defined. Prior to such modeling capabilities, the allowable P/D was established as 1.78 based on some very limited experience in other cavern fields. While appropriate for 1980, the ratio conservatively limits the allowable number of oil drawdowns and hence limits the overall utility and life of the SPR cavern field. Analyses from all four cavern fields are evaluated along with operating experience gained over the past 30 years to define a new P/D for the reserve. A new ratio of 1.0 is recommended. This ratio is applicable only to existing SPR caverns.

  1. Measurements of Pupillary Diameter and Wavefront Aberrations in Pregnant Women

    PubMed Central

    Altay, Mehmet Metin; Demirok, Gulizar; Balta, Ozgur; Bolu, Hulya

    2016-01-01

    Purpose. To show whether pregnancy affects the measurements of pupillary diameter and wavefront (WF) aberrations. Methods. This was a case-control study including 34 healthy pregnant women in the third trimester and age-matched 34 nonpregnant women. Only women who had no ocular abnormalities and no refractive error were included. We measured photopic and mesopic pupil diameter and WF aberrations at the third trimester and at the second postpartum month. Measurements of the right eyes were used in this study. The differences between groups were analysed by paired t-test and t-test. Results. Pregnant women's mean photopic pupil size in the third trimester was significantly higher than in postpartum period and in control group (3.74 ± 0.77, 3.45 ± 0.53, and 3.49 ± 0.15 mm, p < 0.05, resp.). Mesopic pupil size in the third trimester was also higher than in postpartum period and in control group (6.77 ± 0.52, 6.42 ± 0.55, and 6.38 ± 0.21 mm, p < 0.05, resp.). RMS-3 and RMS-5 values were higher in pregnancy but these differences were not statistically significant. Conclusion. Pregnancy increased photopic and mesopic pupil size significantly but did not increase wavefront aberrations notably. Increased pupil size may be due to increased sympathetic activity during pregnancy. And this activity can be noninvasively determined by measuring pupil size. PMID:26998383

  2. Large diameter femoral heads: is bigger always better?

    PubMed

    Cooper, H J; Della Valle, C J

    2014-11-01

    Dislocation remains among the most common complications of, and reasons for, revision of both primary and revision total hip replacements (THR). Hence, there is great interest in maximising stability to prevent this complication. Head size has been recognised to have a strong influence on the risk of dislocation post-operatively. As femoral head size increases, stability is augmented, secondary to an increase in impingement-free range of movement. Larger head sizes also greatly increase the 'jump distance' required for the head to dislocate in an appropriately positioned cup. Level-one studies support the use of larger diameter heads as they decrease the risk of dislocation following primary and revision THR. Highly cross-linked polyethylene has allowed us to increase femoral head size, without a marked increase in wear. However, the thin polyethylene liners necessary to accommodate larger heads may increase the risk of liner fracture and larger heads have also been implicated in causing soft-tissue impingement resulting in groin pain. Larger diameter heads also impart larger forces on the femoral trunnion, which may contribute to corrosion, metal release, and adverse local tissue reactions. Alternative large bearings including large ceramic heads and dual mobility bearings may mitigate some of these risks, and several of these devices have been used with clinical success. PMID:25381403

  3. Facile method to control the diameter and density of carbon nanotubes by using a catalyst-embedded supporting layer

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Woong; Han, Jaeseok; Im, Hyunsik; Choi, WonChel; Park, Young S.; Yoon, Seok-Beom

    2015-06-01

    We have investigated an effective method to control the diameter and the density of carbon nanotubes (CNTs) by introducing a catalyst-embedded supporting layer (CSL) prepared by using rf-magnetron sputtering with a mixed target consisting of Fe and Al2O3. The type of CNTs was changed from single-walled CNTs with a diameter of 0.85 ~ 1.55 nm to multi-walled CNTs with increasing rf-magnetron sputtering power. The controllability of the diameter and the density of the CNTs was confirmed to have been improved by using the rf power during the sputtering of the CSL and the concentration of Fe in the mixed target, respectively.

  4. A Small Diameter Rosette for Sampling Ice Covered Waters

    NASA Astrophysics Data System (ADS)

    Chayes, D. N.; Smethie, W. M.; Perry, R. S.; Schlosser, P.; Friedrich, R.

    2011-12-01

    A gas tight, small diameter, lightweight rosette, supporting equipment and an effective operational protocol has been developed for aircraft supported sampling of sea water across the Lincoln Sea. The system incorporates a commercial off the shelf CTD electronics (SBE19+ sensor package and SBE33 deck unit) to provide real-time measurement data at the surface. We designed and developed modular water sample units and custom electronics to decode the bottle firing commands and close the sample bottles. For a typical station, we land a ski-equipped deHaviland Twin Otter (DHC-6) aircraft on a suitable piece of sea-ice, drill a 12" diameter hole through the ice next to the cargo door and set up a tent to provide a reasonable working environment over the hole. A small winch with 0.1" diameter single conductor cable is mounted in the aircraft by the cargo door and a tripod supports a sheave above the hole. The CTD module is connected to the end of the wire and the water sampling modules are stacked on top as the system is lowered. For most stations, three sample modules are used to provide 12 four (4) liter sample bottles. Data collected during the down-cast is used to formulate the sampling plan which is executed on the up-cast. The system is powered by a 3,700 Watt, 120VAC gasoline generator. After collection, the sample modules are stored in passively temperature stabilized ice chests during the flight back to the logistics facility at Alert where a broad range of samples are drawn and stored for future analysis. The transport mechanism has a good track record of maintaining water samples within about two degrees of the original collection temperature which minimizes out-gassing. The system has been successfully deployed during a field program each spring starting in 2004 along a transect between the north end of Ellesmere Island (Alert, Nunavut) and the North Pole. During the eight field programs we have taken 48 stations with twelve bottles at most stations (eight at

  5. Synthesis of monodisperse mesoporous titania beads with controllable diameter, high surface areas, and variable pore diameters (14-23 nm).

    PubMed

    Chen, Dehong; Cao, Lu; Huang, Fuzhi; Imperia, Paolo; Cheng, Yi-Bing; Caruso, Rachel A

    2010-03-31

    Monodisperse mesoporous anatase titania beads with high surface areas and tunable pore size and grain diameter have been prepared through a combined sol-gel and solvothermal process in the presence of hexadecylamine (HDA) as a structure-directing agent. The monodispersity of the resultant titania beads, along with the spherical shape, can be controlled by varying the amount of structure-directing agent involved in the sol-gel process. The diameter of the titania beads is tunable from approximately 320 to 1150 nm by altering the hydrolysis and condensation rates of the titanium alkoxide. The crystallite size, specific surface area (from 89 to 120 m(2)/g), and pore size distribution (from 14 to 23 nm) of the resultant materials can be varied through a mild solvothermal treatment in the presence of varied amounts of ammonia. On the basis of the results of small-angle XRD, high-resolution SEM/TEM, and gas sorption characterization, a mechanism for the formation of the monodisperse precursor beads has been proposed to illustrate the role of HDA in determining the morphology and monodispersity during the sol-gel synthesis. The approach presented in this study demonstrates that simultaneous control of the physical properties, including specific surface area, mesoporosity, crystallinity, morphology, and monodispersity, of the titania materials can be achieved by a facile sol-gel synthesis and solvothermal process. PMID:20201515

  6. HVOF thermal spray process for internal diameter applications

    SciTech Connect

    Poe, M.W.

    1994-12-31

    Thermal spray has been selected as the coating process of choice for many OEM and repair/restoration applications. Although the thermal spray process has historically been limited to coating `line-of-sight` surfaces, advances in thermal spray equipment design now allow protective and/or restorative coatings to be applied to deep internal diameters utilizing state-of-the-art HVOF processing. The advanced designs include both `standard` and `mini` torches to coat rotating components, plus a rotating extension for coating stationary ID`s. In addition, a wide range of coating materials has been developed and engineered to combat the deleterious effects of wear found in severe service environments. The resultant coatings have exceptionally high bond strength with no interconnected porosity and low residual stress. This unique process provides an important adjunct to the field of thermal spray process capabilities.

  7. Longitudinal Lorentz force on a subwavelength-diameter optical fiber

    SciTech Connect

    Yu Huakang; Fang Wei; Gu Fuxing; Yang Zongyin; Tong Limin; Qiu Min

    2011-05-15

    We analyze the longitudinal Lorentz forces that a propagating continuous-wave light exerts on a subwavelength-diameter optical fiber. Our theoretical results show that, during the propagating process, the guided light exerts no net time-averaged force on the fiber. Via numerical simulation, we find a significant overall pull force of 0.4 pN/mW acting on a 450-nm-diam fiber tip at a wavelength of 980 nm due to the scattering of the end face and a calculated force distribution reveals the feature of a near-field accumulation. Our results may be helpful to the configuration of optomechanical components or devices based on these fibers.

  8. Solar furnace satellite for large diameter crystal growth in space

    NASA Technical Reports Server (NTRS)

    Overfelt, Tony; Wells, Mark; Blake, John

    1993-01-01

    Investigators worldwide are preparing experiments to test the influence of low gravity found in space on the growth of many crystalline materials. However, power limitations prevent existing space crystal growth furnaces from being able to process samples any larger than about 2 cm, and in addition, the background microgravity levels found on the Space Shuttle are not low enough to significantly benefit samples much larger than 2 cm. This paper describes a novel concept of a free-flying platform utilizing well-established solar furnace technology to enable materials processing in space experiments on large-diameter crystals. The conceptual design of this Solar Furnace Satellite is described along with its operational scenario and the anticipated g levels.

  9. Density profile control in a large diameter, helicon plasma

    SciTech Connect

    Cluggish, B.P.; Anderegg, F.A.; Freeman, R.L.; Gilleland, J.; Hilsabeck, T.J.; Isler, R.C.; Lee, W.D.; Litvak, A.A.; Miller, R.L.; Ohkawa, T.; Putvinski, S.; Umstadter, K.R.; Winslow, D.L.

    2005-05-15

    Plasmas with peaked radial density profiles have been generated in the world's largest helicon device, with plasma diameters of over 70 cm. The density profiles can be manipulated by controlling the phase of the current in each strap of two multistrap antenna arrays. Phase settings that excite long axial wavelengths create hollow density profiles, whereas settings that excite short axial wavelengths create peaked density profiles. This change in density profile is consistent with the cold-plasma dispersion relation for helicon modes, which predicts a strong increase in the effective skin depth of the rf fields as the wavelength decreases. Scaling of the density with magnetic field, gas pressure, and rf power is also presented.

  10. White matter microstructure from nonparametric axon diameter distribution mapping.

    PubMed

    Benjamini, Dan; Komlosh, Michal E; Holtzclaw, Lynne A; Nevo, Uri; Basser, Peter J

    2016-07-15

    We report the development of a double diffusion encoding (DDE) MRI method to estimate and map the axon diameter distribution (ADD) within an imaging volume. A variety of biological processes, ranging from development to disease and trauma, may lead to changes in the ADD in the central and peripheral nervous systems. Unlike previously proposed methods, this ADD experimental design and estimation framework employs a more general, nonparametric approach, without a priori assumptions about the underlying form of the ADD, making it suitable to analyze abnormal tissue. In the current study, this framework was used on an ex vivo ferret spinal cord, while emphasizing the way in which the ADD can be weighted by either the number or the volume of the axons. The different weightings, which result in different spatial contrasts, were considered throughout this work. DDE data were analyzed to derive spatially resolved maps of average axon diameter, ADD variance, and extra-axonal volume fraction, along with a novel sub-micron restricted structures map. The morphological information contained in these maps was then used to segment white matter into distinct domains by using a proposed k-means clustering algorithm with spatial contiguity and left-right symmetry constraints, resulting in identifiable white matter tracks. The method was validated by comparing histological measures to the estimated ADDs using a quantitative similarity metric, resulting in good agreement. With further acquisition acceleration and experimental parameters adjustments, this ADD estimation framework could be first used preclinically, and eventually clinically, enabling a wide range of neuroimaging applications for improved understanding of neurodegenerative pathologies and assessing microstructural changes resulting from trauma. PMID:27126002

  11. Evaluation of small diameter coreholes for reservoir information

    SciTech Connect

    Petty, Susan; Adair, Richard G.; Livesay, Bill

    1992-01-01

    Geothermal exploration has been highly successful to date in locating targets for drilling. However, the requirements for an economically successful geothermal well are both high flow rate and high temperature. Most geophysical and geochemical exploration methods have not been highly accurate in predicting the depth and actual temperature of a reservoir, nor have they been able to locate high permeability zones. The result is that most geothermal exploration is conducted by drilling core holes to better understand the heat flow in an area followed by drilling of production diameter exploration wells which can be flow tested to ascertain the permeability. The goal of any exploration program is to determine reservoir economics. The cost of wells makes up between one quarter and one half the total cost of producing geothermal power. The number, design, depth of wells and placement of injectors are important to the optimal exploitation of the reservoir. Although early efforts at development have focused on rapid plant construction to begin cash flow, the history of producing fields emphasizes that understanding reservoirs can reduce the risk of rapid temperature or pressure declines and increase the success of step out drilling following initial exploitation. The high cost of large diameter production wells makes the collecting of exploration data on the reservoir through some less expensive method desirable. Geothermal developers are still drilling resources with surface expression, hot springs and surface mappable fractures and faults. As these obvious resources are developed and as the obvious targets in productive fields are exhausted, new exploration tools are needed. One possibility is the use of deep core holes drilled for temperature gradient data to provide more reservoir information. Two methods not previously applied to geothermal reservoir assessment are suggested to augment other data obtained from coreholes.

  12. Automatic detection and estimation of biparietal diameter from fetal ultrasonography

    NASA Astrophysics Data System (ADS)

    Annangi, Pavan; Banerjee Krishnan, Kajoli; Banerjee, Jyotirmoy; Gupta, Madhumita; Patil, Uday

    2011-03-01

    Fetal bi-parietal diameter (BPD) is known to provide a reliable estimate of gestational age (GA) of a fetus in the first half of pregnancy. In this paper, we present an automated method to identify and measure BPD from B-mode ultrasound images of fetal head. The method (a) automatically detects and places a region-of-interest on the head based on a prior work in our group (b) utilizes the concept of phase congruency for edge detection and (c) employs a cost function to identify the third ventricle inside the head (d) measures the BPD along the perpendicular bisector of occipital frontal diameter (OFD) from the outer rim of the cranium closer to the transducer to the inner rim of the cranium away from the transducer. The cost function is premised on the distribution of anatomical shape, size and presentation of the third ventricle in images that adhere to clinical guidelines describing the scan plane for BPD measurement. The OFD is assumed to lie along the third ventricle. The algorithm has been tested on 137 images acquired from four different scanners. Based on GA estimates and their bounds specified in Standard Obstetric Tables, the GA predictions from automated measurements are found to be within +/-2SD of GA estimates from manual measurements by the operator and a second expert radiologist in 98% of the cases. The method described in this paper can also be adapted to assess the accuracy of the scan plane based on the presence/absence of the third ventricle.

  13. Decellularized ovine arteries as small-diameter vascular grafts.

    PubMed

    Mancuso, L; Gualerzi, A; Boschetti, F; Loy, F; Cao, G

    2014-08-01

    Atherosclerosis and its complications still represent the leading cause of death in the developed countries. While autologous blood vessels may be regarded as the best solution for peripheral and coronary bypass, they are unavailable in most patients. Even though tissue engineering techniques are often applied to the development of small-diameter vascular grafts, limiting factors of this approach are represented by the lack of essential extracellular matrix proteins and/or poor biomechanical properties of the scaffolds used. Along these lines, the aim of this study was to develop a decellularization protocol for ovine carotids to be used as suitable small-diameter vascular grafts. Samples were treated either with sodium dodecyl sulphate (SDS) or with Trypsin and Triton X-100; a final nuclease digestion was performed for both protocols. Morphological analyses demonstrate complete removal of nuclei and cellular components in treated vessels, also confirmed by significant reduction in wall thickness and DNA content. Essential extracellular matrix proteins such as collagen, elastin, and fibronectin are well preserved after decellularization. From a mechanical point of view, Trypsin and Triton X-100 treated arteries show elastic modules and compliance comparable to native carotids, whereas the use of SDS makes samples stiffer, with a significant decrease in the compliance mean value and an increase in longitudinal and circumferential Young's modules. It is demonstrated that the treatment where Trypsin and Triton X-100 are combined guarantees complete decellularization of carotids, with no significant alteration of biomechanical and structural properties, thus preserving a suitable environment for adhesion, proliferation, and migration of cells. PMID:25050540

  14. Axon diameters and conduction velocities in the macaque pyramidal tract

    PubMed Central

    Firmin, L.; Field, P.; Maier, M. A.; Kraskov, A.; Kirkwood, P. A.; Nakajima, K.; Lemon, R. N.

    2014-01-01

    Small axons far outnumber larger fibers in the corticospinal tract, but the function of these small axons remains poorly understood. This is because they are difficult to identify, and therefore their physiology remains obscure. To assess the extent of the mismatch between anatomic and physiological measures, we compared conduction time and velocity in a large number of macaque corticospinal neurons with the distribution of axon diameters at the level of the medullary pyramid, using both light and electron microscopy. At the electron microscopic level, a total of 4,172 axons were sampled from 2 adult male macaque monkeys. We confirmed that there were virtually no unmyelinated fibers in the pyramidal tract. About 14% of pyramidal tract axons had a diameter smaller than 0.50 μm (including myelin sheath), most of these remaining undetected using light microscopy, and 52% were smaller than 1 μm. In the electrophysiological study, we determined the distribution of antidromic latencies of pyramidal tract neurons, recorded in primary motor cortex, ventral premotor cortex, and supplementary motor area and identified by pyramidal tract stimulation (799 pyramidal tract neurons, 7 adult awake macaques) or orthodromically from corticospinal axons recorded at the mid-cervical spinal level (192 axons, 5 adult anesthetized macaques). The distribution of antidromic and orthodromic latencies of corticospinal neurons was strongly biased toward those with large, fast-conducting axons. Axons smaller than 3 μm and with a conduction velocity below 18 m/s were grossly underrepresented in our electrophysiological recordings, and those below 1 μm (6 m/s) were probably not represented at all. The identity, location, and function of the majority of corticospinal neurons with small, slowly conducting axons remains unknown. PMID:24872533

  15. Association between abdominal aortic diameter and peripheral vascular disease.

    PubMed

    Rajkumar, C; Bonapace, S; Starr, J; Radia, M; Bulpitt, C J

    1997-09-01

    Fifty-four elderly people 81.2 years +/- 7.4 (mean age +/- s.d., range 66-98 years) were selected. These included 20 men (78.6 +/- 6.4 years, range 70-91 years) and 34 women (82.2 +/- 7.6 years, range 66-98 years). The relationship between the size of the abdominal aorta and various cardiovascular risk indicators such as calf:-brachial systolic pressure ratio, plasma cholesterol, triglycerides, and random blood glucose were examined. Abdominal aortic diameter correlated well with calf:-brachial systolic ratio measured by Doppler method over the posterior tibial artery and taking the lowest result of the right and left side (r = -0.28, P = 0.04). This correlation tended to be stronger in men (r = -0.55, P = 0.02) compared to women (r = -0.10, P = 0.57). However, the relationship tended to be confined to the systolic pressure in the left leg, raising the hypothesis that left-sided vascular disease is better related to aortic diameter, possibly due to a difference in the effects of reflected waves between the two sides. This needs further investigation. The contrast between the sexes was seen in the absence of any significant difference in resting blood pressure and calf:brachial systolic pressure ratio between the two. This finding suggests that the sex differences in the relationship between the size of the abdominal aorta and calf:brachial systolic pressure ratio are related to intrinsic properties of the arterial wall. PMID:9364278

  16. Solar concentrator

    SciTech Connect

    Smyth, J.S.

    1982-06-08

    A solar concentrator having an open framework formed as a geodesic dome. A rotatable support axle extends substantially diametrically across the dome and has the opposite ends thereof supported on the framework. The support axle defines a first rotational axis which is oriented to extend substantially parallel with the earth's north-south axis. A support post is hingedly mounted on the support shaft substantially at the midpoint thereof for permitting angular displacement of the support post relative to the support shaft about a second rotational axis which is perpendicular to the first axis. A dishshaped reflector assembly is positioned within the interior of the framework and fixedly secured to the support post. First and second drives effect angular displacement of the reflector assembly about the first and second axes, respectively, to permit tracking of the solar position.

  17. Growth of Si Bulk Crystals with Large Diameter Ratio Using Small Crucibles by Creating a Large Low-Temperature Region Inside a Si Melt Contained in an NOC Furnace Developed Using Two Zone Heaters

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo; Ono, Satoshi; Murai, Ryota; Kaneko, Yuzuru

    2016-06-01

    Three zone heaters were generally used for a noncontact crucible (NOC) furnace. For practical reasons a simpler NOC furnace was developed with two zone heaters, which had a carbon heat holder to cover the three roles of each heater. Large low-temperature regions were obtained, and silicon ingots were grown in small crucibles with a large diameter and diameter ratio. Here, the diameter ratio is the ratio of the ingot diameter to the crucible diameter and can be as large as 0.90. The diameter ratio was controlled mainly by the temperature reduction of the first heater. Power changes of the second heater did not have a significant impact on the ingot diameter. Using this NOC furnace, maximum ingot diameters of 28.0, 33.5, and 45.0 cm were obtained using crucibles of 33, 40, and 50 cm in diameter, respectively. The oxygen concentration of the ingots did not strongly depend on the diameter ratio and were always low because convection in the Si melt was markedly suppressed by the carbon heat holder. Moreover, the oxygen concentration of the ingots has a tendency to become lower as the crucible diameter becomes larger.

  18. Correlation of the ratio of caudal vena cava diameter and aorta diameter with systolic pressure variation in anesthetized dogs.

    PubMed

    Meneghini, Caterina; Rabozzi, Roberto; Franci, Paolo

    2016-02-01

    OBJECTIVE To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV). ANIMALS 14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds. PROCEDURES Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed. RESULTS 28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV. (Am J Vet Res 2016;77:137-143). PMID:27027706

  19. Microbes make average 2 nanometer diameter crystalline UO2 particles.

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kelly, S. D.; Kemner, K. M.; Banfield, J. F.

    2001-12-01

    It is well known that phylogenetically diverse groups of microorganisms are capable of catalyzing the reduction of highly soluble U(VI) to highly insoluble U(IV), which rapidly precipitates as uraninite (UO2). Because biological uraninite is highly insoluble, microbial uranyl reduction is being intensively studied as the basis for a cost-effective in-situ bioremediation strategy. Previous studies have described UO2 biomineralization products as amorphous or poorly crystalline. The objective of this study is to characterize the nanocrystalline uraninite in detail in order to determine the particle size, crystallinity, and size-related structural characteristics, and to examine the implications of these for reoxidation and transport. In this study, we obtained U-contaminated sediment and water from an inactive U mine and incubated them anaerobically with nutrients to stimulate reductive precipitation of UO2 by indigenous anaerobic bacteria, mainly Gram-positive spore-forming Desulfosporosinus and Clostridium spp. as revealed by RNA-based phylogenetic analysis. Desulfosporosinus sp. was isolated from the sediment and UO2 was precipitated by this isolate from a simple solution that contains only U and electron donors. We characterized UO2 formed in both of the experiments by high resolution-TEM (HRTEM) and X-ray absorption fine structure analysis (XAFS). The results from HRTEM showed that both the pure and the mixed cultures of microorganisms precipitated around 1.5 - 3 nm crystalline UO2 particles. Some particles as small as around 1 nm could be imaged. Rare particles around 10 nm in diameter were also present. Particles adhere to cells and form colloidal aggregates with low fractal dimension. In some cases, coarsening by oriented attachment on \\{111\\} is evident. Our preliminary results from XAFS for the incubated U-contaminated sample also indicated an average diameter of UO2 of 2 nm. In nanoparticles, the U-U distance obtained by XAFS was 0.373 nm, 0.012 nm

  20. Modular Small Diameter Vascular Grafts with Bioactive Functionalities

    PubMed Central

    Neufurth, Meik; Wang, Xiaohong; Tolba, Emad; Dorweiler, Bernhard; Schröder, Heinz C.; Link, Thorben; Diehl-Seifert, Bärbel; Müller, Werner E. G.

    2015-01-01

    We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca2+ through formation of Ca2+ bridges between the polyanions, alginate, N,O-CMC, and polyP (alginate-Ca2+-N,O-CMC-polyP). The bTEBV are formed by pressing the hydrogel through an extruder into a hardening solution, containing Ca2+. In this universal scaffold of the bTEBV biomaterial, polycations such as poly(l-Lys), poly(d-Lys) or a His/Gly-tagged RGD peptide (three RGD units) were incorporated, which promote the adhesion of endothelial cells to the vessel surface. The mechanical properties of the biopolymer material (alginate-Ca2+-N,O-CMC-polyP-silica) revealed a hardness (elastic modulus) of 475 kPa even after a short incubation period in CaCl2 solution. The material of the artificial vascular grafts (bTEBVs with an outer size 6 mm and 1.8 mm, and an inner diameter 4 mm and 0.8 mm, respectively) turned out to be durable in 4-week pulsatile flow experiments at an alternating pressure between 25 and 100 mbar (18.7 and 75.0 mm Hg). The burst pressure of the larger (smaller) vessels was 850 mbar (145 mbar). Incorporation of polycationic poly(l-Lys), poly(d-Lys), and especially the His/Gly-tagged RGD peptide, markedly increased the adhesion of human, umbilical vein/vascular endothelial cells, EA.HY926 cells, to the surface of the hydrogel. No significant effect of the polyP samples on the clotting of human plasma is measured. We propose that the metabolically degradable

  1. Earth Climate Changes Connected To Solar Diameter and Irradiance Variabilities

    NASA Astrophysics Data System (ADS)

    Lefebvre, S.; Rozelot, J. P.

    Recent studies indicate that small but persistent variations in the total solar irradiance may play an important role in climate changes. If it is known that such changes are mainly due to changes in sunspots darkness and faculae brightness, it begins to be understood that changes in the radius of the Sun may also play a role. In a first part of this paper, we will show how the irradiance is affected by small distortions of the solar shape. Indeed such departures to a pure spherical Sun can be modelized as they reflect the gravitational distortions inside the Sun (variability of the rotation rate both in latitude and in depth as deduced by helioseismic measurements). These departures have been also observed from space (MDI on board SOHO) and from ground (solar astrolabes, scanning heliometer or other means). Such a variability on the Sun's di- ameter, certainly of no more than 40 mas (maybe less), will imply a change in the luminosity of about 6 parts per 10000. For the time being such variations have not been yet taken into account in the Earth climate changes. In the second part of this paper, we will focus on a longer period of time. We will briefly review the variabil- ity of the solar diameter over the last past four centuries, as it is suspected now with a rather good confidence that such a temporal variability may have a sense. We will compare this variability with the global Earth temperatures used as a climatic proxy. It can be seen that diameter changes over such a long period of time are indicative of an external variability on the Earth climate. The physical mechanism involved is obviously through the irradiance changes for which we will emphasize the need to get accurate and simultaneous measurements of the Sun's radius. The determination of the commonly used ratio W, which measures the relative variations of the radius over the relative variations of the irradiance, and as deduced in the first part of this paper, is helpful to pinpoint the source of

  2. Attached cavitation at a small diameter ultrasonic horn tip

    NASA Astrophysics Data System (ADS)

    Žnidarčič, Anton; Mettin, Robert; Cairós, Carlos; Dular, Matevž

    2014-02-01

    Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids, for instance, for cell disruption or sonochemical reactions. They are operated typically in the frequency range up to about 50 kHz and have tip diameters from some mm to several cm. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e., below the acoustic driving frequency. Here, we present a systematic study of the cavitation dynamics in water at a 20 kHz horn tip of 3 mm diameter. The system was investigated by high-speed imaging with simultaneous recording of the acoustic emissions. Measurements were performed under variation of acoustic power, air saturation, viscosity, surface tension, and temperature of the liquid. Our findings show that the liquid properties play no significant role in the dynamics of the attached cavitation at the small ultrasonic horn. Also the variation of the experimental geometry, within a certain range, did not change the dynamics. We believe that the main two reasons for the peculiar dynamics of cavitation on a small ultrasonic horn are the higher energy density on a small tip and the inability of the big tip to "wash" away the gaseous bubbles. Calculation of the somewhat adapted Strouhal number revealed that, similar to the hydrodynamic cavitation, values which are relatively low characterize slow cavitation structure dynamics. In cases where the cavitation follows the driving frequency this value lies much higher - probably at Str > 20. In the spirit to distinguish the observed phenomenon with other cavitation dynamics at ultrasonic transducer surfaces, we suggest to term the observed phenomenon of attached cavities partly covering the full horn

  3. Small diameter gravity sewers: self-cleansing conditions and aspects of wastewater quality.

    PubMed

    Dias, S P; Matos, J S

    2001-01-01

    The construction of conventional sewerage systems in small communities, with pipes laid on a uniform slope and manholes regularly spaced, is sometimes not economically feasible, because of the high costs of sewer installation. Under those circumstances, the small diameter gravity sewers (SDGS) have often proven to be substantially less costly than conventional sewers. Typically, in SDGS systems the wastewater from one or more households is discharged into an interceptor tank (or a single compartment septic tank). The settled effluent is discharged afterwards into small diameter sewers operating under gravity. In this paper, special emphasis is given to the analysis of self-cleansing conditions and to the analysis of risks of sulphide generation and occurrence of septic conditions in SDGS systems. For the evaluation of the self-cleansing conditions, the critical velocity and the critical shear stress were computed according to the Shields equation. The forecasting of dissolved oxygen concentrations and sulphide build-up along the lines, for different flow conditions, was done running an established wastewater quality model. PMID:11379122

  4. Apoptosis regulates endothelial cell number and capillary vessel diameter but not vessel regression during retinal angiogenesis.

    PubMed

    Watson, Emma C; Koenig, Monica N; Grant, Zoe L; Whitehead, Lachlan; Trounson, Evelyn; Dewson, Grant; Coultas, Leigh

    2016-08-15

    The growth of hierarchical blood vessel networks occurs by angiogenesis. During this process, new vessel growth is accompanied by the removal of redundant vessel segments by selective vessel regression ('pruning') and a reduction in endothelial cell (EC) density in order to establish an efficient, hierarchical network. EC apoptosis has long been recognised for its association with angiogenesis, but its contribution to this process has remained unclear. We generated mice in which EC apoptosis was blocked by tissue-specific deletion of the apoptosis effector proteins BAK and BAX. Using the retina as a model, we found that apoptosis made a minor contribution to the efficiency of capillary regression around arteries where apoptosis was most concentrated, but was otherwise dispensable for vessel pruning. Instead, apoptosis was necessary for the removal of non-perfused vessel segments and the reduction in EC density that occurs during vessel maturation. In the absence of apoptosis, increased EC density resulted in an increase in the diameter of capillaries, but not arteries or veins. Our findings show that apoptosis does not influence the number of vessels generated during angiogenesis. Rather it removes non-perfused vessel segments and regulates EC number during vessel maturation, which has vessel-specific consequences for vessel diameter. PMID:27471260

  5. Economic strategies of plant absorptive roots vary with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

  6. High reliability bond program using small diameter aluminum wire

    NASA Technical Reports Server (NTRS)

    Macha, M.; Thiel, R. A.

    1975-01-01

    The program was undertaken to characterize the performance of small diameter aluminum wire ultrasonically bonded to conductors commonly encountered in hybrid assemblies, and to recommend guidelines for improving this performance. Wire, 25.4, 38.1 and 50.8 um (1, 1.5 and 2 mil), was used with bonding metallization consisting of thick film gold, thin film gold and aluminum as well as conventional aluminum pads on semiconductor chips. The chief tool for evaluating the performance was the double bond pull test in conjunction with a 72 hour - 150 C heat soak and -65 C to +150 C thermal cycling. In practice the thermal cycling was found to have relatively little effect compared to the heat soak. Pull strength will decrease after heat soak as a result of annealing of the aluminum wire; when bonded to thick film gold, the pull strength decreased by about 50% (weakening of the bond interface was the major cause of the reduction). Bonds to thin film gold lost about 30 - 40% of their initial pull strenth; weakening of the wire itself at the bond heel was the predominant cause. Bonds to aluminum substrate metallization lost only about 22%. Bonds between thick and thin film gold substrate metallization and semiconductor chips substantiated the previous conclusions but also showed that in about 20 to 25% of the cases, bond interface failure occurred at the semiconductor chip.

  7. Slip flow through colloidal crystals of varying particle diameter.

    PubMed

    Rogers, Benjamin J; Wirth, Mary J

    2013-01-22

    Slip flow of water through silica colloidal crystals was investigated experimentally for eight different particle diameters, which have hydraulic channel radii ranging from 15 to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 10(10) Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63 ± 3 nm. A flow enhancement of 20 ± 2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high-volume flow rates. PMID:23237590

  8. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Smith, Earnest C. (Inventor); Oliver, Charles E. (Inventor); Redmon, John W., Sr. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1987-01-01

    A tool is shown having a cross beam assembly made of beams joined by a center box structure. The assembly is adapted to be mounted by brackets to the outer end of a cylindrical case. The center box structure has a vertical shaft rotatably mounted therein and extending beneath the assembly. Secured to the vertical shaft is a radius arm which is adapted to rotate with the shaft. On the longer end of the radius arm is a measuring tip which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm. An electric servomotor rotates the vertical shaft and an electronic resolver provides an electric signal representing the angle of rotation of the shaft. The electric signals are provided to a computer station which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  9. Aggregate Morphology Evolution by Sintering: Number & Diameter of Primary Particles

    PubMed Central

    Eggersdorfer, Max L.; Kadau, Dirk; Herrmann, Hans J.; Pratsinis, Sotiris E.

    2013-01-01

    The structure of fractal-like agglomerates (physically-bonded) and aggregates (chemically- or sinter-bonded) is important in aerosol synthesis of nanoparticles, and in monitoring combustion emissions and atmospheric particles. It influences also particle mobility, scattering, and eventually performance of nanocomposites, suspensions and devices made with such particles. Here, aggregate sintering by viscous flow of amorphous materials (silica, polymers) and grain boundary diffusion of crystalline ceramics (titania, alumina) or metals (Ni, Fe, Ag etc.) is investigated. A scaling law is found between average aggregate projected area and equivalent number of constituent primary particles during sintering: from fractal-like agglomerates to aggregates and eventually compact particles (e.g. spheres). This is essentially a relation independent of time, material properties and sintering mechanisms. It is used to estimate the equivalent primary particle diameter and number in aggregates. The evolution of aggregate morphology or structure is quantified by the effective fractal dimension (Df) and mass-mobility exponent (Dfm) and the corresponding prefactors. The Dfm increases monotonically during sintering converging to 3 for a compact particle. Therefore Dfm and its prefactor could be used to gauge the degree or extent of sintering of agglomerates made by a known collision mechanism. This analysis is exemplified by comparison to experiments of silver nanoparticle aggregates sintered at different temperatures in an electric tube furnace. PMID:23658467

  10. Continuous Measurement of Particle Hygroscopicity as a Function of Diameter

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Anderson, B. E.; Ziemba, L. D.; Thornhill, K. L.; Moore, R.; Beyersdorf, A. J.; Winstead, E. L.; Crumeyrolle, S.; Wagner, N.; Langridge, J. M.; Richardson, M.; Lack, D. A.; Law, D. C.; Shingler, T.; Sorooshian, A.

    2012-12-01

    An ultra-high sensitivity aerosol spectrometer (UHSAS, Droplet Measurement Technologies, Boulder, CO, USA) has been substantially modified to humidify the aerosol sample stream. The size distribution of deliquesced particles at humidities as high as 95% is measured. By combining a Mie model of instrument response with measurements of dry and wet size distributions, the hygroscopic growth factor as a function of particle diameter can be estimated. By operating a second, well-calibrated dry UHSAS simultaneously with the humidified UHSAS, the size-dependent particle hygroscopicity can be determined continuously, which is particularly useful for airborne sampling where rapid time response is required. The technique has been applied to laboratory particles of inorganic salts and of polystyrene latex, and to mixed sulfate/organic particles and dense forest fire smoke measured on an aircraft during the Deep Convective Clouds and Chemistry (DC3) project. Results will be compared with measurements of aerosol extinction at different RH values and of hygroscopic growth made with a differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP). Initial evaluations of changes in hygroscopicity due to processing in convective clouds will be presented. Limitations of the technique, such as the effects of external mixtures and insoluble components, will be discussed.

  11. Development of the 15 meter diameter hoop column antenna

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The building of a deployable 15-meter engineering model of the 100 meter antenna based on the point-design of an earlier task of this contract, complete with an RF-capable surface is described. The 15 meter diameter was selected so that the model could be tested in existing manufacturing, near-field RF, thermal vacuum, and structural dynamics facilities. The antenna was designed with four offset paraboloidal reflector surfaces with a focal length of 366.85 in and a primary surface accuracy goal of .069 in rms. Surface adjustment capability was provided by manually resetting the length of 96 surface control cords which emanated from the lower column extremity. A detailed description of the 15-meter Hoop/Column Antenna, major subassemblies, and a history of its fabrication, assembly, deployment testing, and verification measurements are given. The deviation for one aperture surface (except the outboard extremity) was measured after adjustments in follow-on tests at the Martin Marietta Near-field Facility to be .061 in; thus the primary surface goal was achieved.

  12. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Oliver, Charles E. (Inventor); Smith, Earnest C. (Inventor); Redmon, John W. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1989-01-01

    A tool is shown having a cross beam assembly (15) made of beams (18, 19, 20, 21) joined by a center box structure (23). The assembly (15) is adapted to be mounted by brackets (16) to the outer end of a cylindrical case (11). The center box structure (23) has a vertical shaft (25) rotatably mounted therein and extending beneath the assembly (15). Secured to the vertical shaft (25) is a radius arm (28) which is adapted to rotate with shaft (25). On the longer end of the radius arm (28) is a measuring tip (30) which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm (28). An electric servomotor (49) rotates the vertical shaft (25) and an electronic resolver (61) provides an electric signal representing the angle of rotation of the shaft (25). The electric signals are provided to a computer station (73) which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  13. Sustainable yields from large diameter wells in shallow weathered aquifers

    NASA Astrophysics Data System (ADS)

    Rushton, K. R.; de Silva, C. S.

    2016-08-01

    Large diameter wells in shallow weathered aquifers provide a valuable source of water for domestic and agricultural purposes in many locations including the Indian subcontinent. However, when used for irrigation, these wells often fail towards the end of the dry season. By considering two case studies in the dry and intermediate rainfall zones of Sri Lanka, reasons for the limited yield of these wells are identified. The first case study is concerned with a sloping catchment; a significant proportion of the precipitation during the rainy season either becomes runoff or passes down-gradient through the aquifer and is discharged at the ground surface. Furthermore, during the dry season, groundwater discharge continues. In the second case study the topography is generally flat but, even though the aquifer fills most years during the rainy season, there is often only sufficient water to irrigate about half of each farmer's holding. These investigations are based on field information and the development of conceptual and computational models. Of critical importance in assessing the long term yield of a well is the formation of a seepage face on the side of the well, with the water table a significant distance above the pumping water level. Consequently the water table may only be lowered to about half the depth of the well. The paper concludes with recommendations for the exploitation of groundwater from shallow weathered aquifers to minimise the risk of failure during the dry season.

  14. Slip Flow through Colloidal Crystals of Varying Particle Diameter

    PubMed Central

    Rogers, Benjamin J.; Wirth, Mary J.

    2012-01-01

    Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates. PMID:23237590

  15. Minimizing the Diameter of a Network Using Shortcut Edges

    NASA Astrophysics Data System (ADS)

    Demaine, Erik D.; Zadimoghaddam, Morteza

    We study the problem of minimizing the diameter of a graph by adding k shortcut edges, for speeding up communication in an existing network design. We develop constant-factor approximation algorithms for different variations of this problem. We also show how to improve the approximation ratios using resource augmentation to allow more than k shortcut edges. We observe a close relation between the single-source version of the problem, where we want to minimize the largest distance from a given source vertex, and the well-known k-median problem. First we show that our constant-factor approximation algorithms for the general case solve the single-source problem within a constant factor. Then, using a linear-programming formulation for the single-source version, we find a (1 + ɛ)-approximation using O(klogn) shortcut edges. To show the tightness of our result, we prove that any ({3 over 2}-ɛ)-approximation for the single-source version must use Ω(klogn) shortcut edges assuming P ≠ NP.

  16. Internal Diameter HVAF Spraying for Wear and Corrosion Applications

    NASA Astrophysics Data System (ADS)

    Lyphout, C.; Björklund, S.

    2015-01-01

    Electrolytic hard chrome (EHC) methods are still widely utilized in the printing, automotive and off-shore industries. Alternative methods to EHC have been widely developed in the past decade by conventional HVOF processes and more recently HVAF systems, which are processing at higher kinetic energy and more particularly at lower temperature, significantly increasing wear and corrosion resistance properties. A dedicated internal diameter HVAF system is here presented, and coatings characteristics are compared to the one obtained by standard HVAF coatings. Specially R&D designed fixtures with inside bore of 200 mm have been manufactured for this purpose, with a possibility to spray samples at increasing depth up to 400 mm while simulating closed bottom bore spraying. WC-based and Cr3C2-based powder feedstock materials have been deposited onto high-strength steel substrates. Respective coating microstructures, thermally induced stresses and corrosion resistance are discussed for further optimization of coating performances. The fact that the ID-HVAF system is utilized both for spraying and gritblasting procedures is also given a particular interest.

  17. Characterization of an 8-cm Diameter Ion Source System

    NASA Technical Reports Server (NTRS)

    Li, Zhongmin; Hawk, C. W.; Hawk, Clark W.; Buttweiler, Mark S.; Williams, John D.; Buchholtz, Brett

    2005-01-01

    Results of tests characterizing an 8-cm diameter ion source are presented. The tests were conducted in three separate vacuum test facilities at the University of Alabama-Huntsville, Colorado State University, and L3 Communications' ETI division. Standard ion optics tests describing electron backstreaming and total-voltage-limited impingement current behavior as a function of beam current were used as guidelines for selecting operating conditions where more detailed ion beam measurements were performed. The ion beam was profiled using an in-vacuum actuating probe system to determine the total ion current density and the ion charge state distribution variation across the face of the ion source. Both current density and ExB probes were utilized. The ion current density data were used to obtain integrated beam current, beam flatness parameters, and general beam profile shapes. The ExB probe data were used to determine the ratio of doubly to singly charged ion current. The ion beam profile tests were performed at over six different operating points that spanned the expected operating range of the DAWN thrusters being developed at L3. The characterization tests described herein reveal that the 8-cm ion source is suitable for use in (a) validating plasma diagnostic equipment, (b) xenon ion sputtering and etching studies of spacecraft materials, (c) plasma physics research, and (d) the study of ion thruster optics at varying conditions.

  18. Inhibited bacterial biofilm formation and improved osteogenic activity on gentamicin-loaded titania nanotubes with various diameters.

    PubMed

    Lin, Wen-tao; Tan, Hong-lue; Duan, Zhao-ling; Yue, Bing; Ma, Rui; He, Guo; Tang, Ting-ting

    2014-01-01

    Titania nanotubes loaded with antibiotics can deliver a high concentration of antibiotics locally at a specific site, thereby providing a promising strategy to prevent implant-associated infections. In this study we have fabricated titania nanotubes with various diameters (80, 120, 160, and 200 nm) and 200 nm length via electrochemical anodization. These nanotubes were loaded with 2 mg of gentamicin using a lyophilization method and vacuum drying. A standard strain, Staphylococcus epidermidis (American Type Culture Collection 35984), and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the anti-infective ability of the gentamicin-loaded nanotubes (NT-G). Flat titanium (FlatTi) and nanotubes with no drug loading (NT) were also investigated and compared. We found that NT-G could significantly inhibit bacterial adhesion and biofilm formation compared to FlatTi or NT, and the NT-G with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended drug release time of NT-G with larger diameters. The NT also exhibited greater antibacterial ability than the FlatTi, while nanotubes with 80 nm or 120 nm diameters had better effects. Furthermore, human marrow derived mesenchymal stem cells were used to evaluate the effect of nanotubular topographies on the osteogenic differentiation of mesenchymal stem cells. Our results showed that NT-G and NT, especially those with 80 nm diameters, significantly promoted cell attachment, proliferation, spreading, and osteogenic differentiation when compared to FlatTi, and there was no significant difference between NT-G and NT with the same diameter. Therefore, nanotube modification and gentamicin loading can significantly improve the antibacterial ability and osteogenic activity of orthopedic implants. PMID:24634583

  19. Effect of diameter of nanoparticles and capture cross-section library on macroscopic dose enhancement in boron neutron capture therapy

    PubMed Central

    Farhood, Bagher

    2014-01-01

    Purpose The aim of this study is evaluation of the effect of diameter of 10B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT). Material and methods MCNPX Monte Carlo code was used for simulation of a 252Cf source, a soft tissue phantom and a tumor containing 10B nanoparticles. Using 252Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of 10B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated. Results There is not a linear relationship between the average MDEF value and nanoparticles’ diameter but the average MDEF grows with increased concentration of 10B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of 10B nanoparticles. Conclusions Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements. PMID:25834582

  20. Dielectric properties of polymer composites with carbon nanotubes of different diameters.

    PubMed

    Macutkevic, Jan; Paddubskaya, Alesia; Kuzhir, Polina; Banys, Juras; Maksimenko, Sergey; Kuznetsov, Vladimir L; Mazov, Ilya N; Krasnikov, Dmitrij V

    2014-07-01

    The dielectric properties of Polymethylmetacrylate (PMMA) composites filled with CVD made multiwalled carbon nanotubes (MWCNT) of different mean outer diameters (d - 9 nm and 12-14 nm) were investigated at temperatures from 300 K to 390 K and in a wide frequency range (20 Hz-1 MHz). The percolation threshold is lower in composites with thick nanotubes. Below percolation threshold the dielectric permittivity was found also to be higher for composites with thicker carbon nanotubes. The temperature dependence of the complex dielectric permittivity of the investigated composites below percolation is mainly caused by beta relaxation in pure PMMA polymer matrix. The potential barrier for PMMA molecules rotation is higher in composites with thicker MWCNT and demonstrates non-monotonous concentration dependence. PMID:24758044

  1. Design and development of a high-concentration photovoltaic concentrator

    SciTech Connect

    Hodge, R C

    1982-04-01

    The design and development of a high concentration photovoltaic concentrator module is discussed. The design concept described herein incorporates a curved groove domed Fresnel lens, a high concentration etched multiple vertical junction (EMVJ) solar cell and a passively cooled direct-bonded copper cell mount all packaged in a plastic module. Two seven inch diameter 1200x domed Fresnel lenses were fabricated using single point diamond turning technology. Testing at both GE and Sandia confirmed optical transmission efficiencies of over 83%. Samples of the latest available EMVJ cells were mounted and installed, with a domed Fresnel lens, into a prototype module. Subsequent testing demonstrated net lens-cell efficiencies of 10 to 13%. As a result of this program, salient conclusions have been formulated as to this technology.

  2. Advanced solar concentrator mass production, operation, and maintenance cost assessment

    NASA Technical Reports Server (NTRS)

    Niemeyer, W. A.; Bedard, R. J.; Bell, D. M.

    1981-01-01

    The object of this assessment was to estimate the costs of the preliminary design at: production rates of 100 to 1,000,000 concentrators per year; concentrators per aperture diameters of 5, 10, 11, and 15 meters; and various receiver/power conversion package weights. The design of the cellular glass substrate Advanced Solar Concentrator is presented. The concentrator is an 11 meter diameter, two axis tracking, parabolic dish solar concentrator. The reflective surface of this design consists of inner and outer groups of mirror glass/cellular glass gores.

  3. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    DOE PAGESBeta

    Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; O'Brien, Stephen

    2007-01-01

    A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  4. Saqqar: A 34 km diameter impact structure in Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Kenkmann, Thomas; Afifi, Abdulkader M.; Stewart, Simon A.; Poelchau, Michael H.; Cook, Douglas J.; Neville, Allen S.

    2015-11-01

    Here we present the first proof of an impact origin for the Saqqar circular structure in northwestern Saudi Arabia (Neville et al. ), with an apparent diameter of 34 km, centered at 29°35'N, 38°42'E. The structure is formed in Cambrian-Devonian siliciclastics and is unconformably overlain by undeformed Cretaceous and Paleogene sediments. The age of impact is not well constrained and lies somewhere between 410 and 70 Ma. The subsurface structure is constrained by 2-D reflection seismic profiles and six drilled wells. First-order structural features are a central uplift that rises approximately 2 km above regional datums, surrounded by a ring syncline. The crater rim is defined by circumferential normal faults. The central uplift and ring syncline correspond to a Bouguer gravity high and an annular ring-like low, respectively. The wells were drilled within the central uplift, the deepest among them exceed 2 km depth. Sandstone core samples from these wells show abundant indicators of a shock metamorphic overprint. Planar deformation features (PDFs) were measured with orientations along (0001), {101¯3}, and less frequently along {101¯1} and {101¯4}. Planar fractures (PFs) predominantly occur along (0001) and {101¯1}, and are locally associated with feather features (FFs). In addition, some shocked feldspar grains and strongly deformed mica flakes were found. The recorded shock pressure ranges between 5 and 15 GPa. The preserved level of shock and the absence of an allochthonous crater fill suggest that Saqqar was eroded by 1-2 km between the Devonian and Maastrichtian. The documentation of unequivocal shock features proves the formation of the Saqqar structure by a hypervelocity impact event.

  5. Quality control on crimping of large diameter welding pipe

    NASA Astrophysics Data System (ADS)

    Fan, Lifeng; Gao, Ying; Li, Qiang; Xu, Hongshen

    2012-11-01

    Crimping is used in production of large diameter submerged-arc welding pipes. Many researches are focused on crimping in certain manufacturing mode of welding pipe. The application scopes of research achievements become limited due to lack of uniformity in theoretical analysis. In order to propose a crimping prediction method in order to control forming quality, the theory model of crimping based on elastic-plastic mechanics is established. The main technical parameters are determined by theoretical analysis, including length of crimping, base radius of punch, terminal angle of punch, base radius of die, terminal angle of die and horizontal distance between punch and die. In addition, a method used to evaluate the forming quality is presented, which investigates the bending angle after springback, forming force, straight edge length and equivalent radius of curvature. In order to investigate the effects of technical parameters on forming quality, a two-dimensional finite element model is established by finite element software ABAQUS. The finite element model is verified in that its shapes error is less than 5% by comparable experiments, which shows that their geometric precision meets demand. The crimping characteristics is obtained, such as the distribution of stress and strain and the changes of forming force, and the relation curves of technical parameters on forming quality are given by simulation analysis. The sensitivity analysis indicates that the effects of length of crimping, technical parameters of punch on forming quality are significant. In particular, the data from simulation analysis are regressed by response surface method (RSM) to establish prediction model. The feasible technical parameters are obtained from the prediction model. This method presented provides a new thought used to design technical parameters of crimping forming and makes a basis for improving crimping forming quality.

  6. AUTOMATED WATER LEVEL MEASUREMENTS IN SMALL-DIAMETER AQUIFER TUBES

    SciTech Connect

    PETERSEN SW; EDRINGTON RS; MAHOOD RO; VANMIDDLESWORTH PE

    2011-01-14

    Groundwater contaminated with hexavalent chromium, strontium-90, and uranium discharges into the Columbia River along approximately 16 km (10 mi) of the shoreline. Various treatment systems have and will continue to be implemented to eliminate the impact of Hanford Site contamination to the river. To optimize the various remediation strategies, it is important to understand interactions between groundwater and the surface water of the Columbia River. An automated system to record water levels in aquifer sampling tubes installed in the hyporheic zone was designed and tested to (1) gain a more complete understanding of groundwater/river water interactions based on gaining and losing conditions ofthe Columbia River, (2) record and interpret data for consistent and defensible groundwater/surface water conceptual models that may be used to better predict subsurface contaminant fate and transport, and (3) evaluate the hydrodynamic influence of extraction wells in an expanded pump-and-treat system to optimize the treatment system. A system to measure water levels in small-diameter aquifer tubes was designed and tested in the laboratory and field. The system was configured to allow manual measurements to periodically calibrate the instrument and to permit aquifer tube sampling without removing the transducer tube. Manual measurements were collected with an e-tape designed and fabricated especially for this test. Results indicate that the transducer system accurately records groundwater levels in aquifer tubes. These data are being used to refine the conceptual and numeric models to better understand interactions in the hyporheic zone of the Columbia River and the adjacent river water and groundwater, and changes in hydrochemistry relative to groundwater flux as river water recharges the aquifer and then drains back out in response to changes in the river level.

  7. Solar Diameter Measurements from Eclipses as a Solar Variability Proxy

    NASA Astrophysics Data System (ADS)

    Waring Dunham, David; Sofia, Sabatino; Guhl, Konrad; Herald, David Russell

    2015-08-01

    Since thermal relaxation times for the Sun are thousands of years, small variations of the Solar intensity are proportional to small variations of the Solar diameter on decadal time scales. In a combination between observations and theory, reliable values of the relation constant W are known, that allow transformation of historical variations of radius into variations of the solar luminosity. During the past 45 years, members of the International Occultation Timing Association (IOTA) have observed 20 annular and total solar eclipses from locations near the path edges. Baily’s beads, whose occurrence and duration are considerably prolonged as seen from path edge locations, were first timed visually, mostly using projection techniques, but since about 1980, they have been timed mainly from analysis of video recordings. The edge locations have the advantage that most of the beads are defined by the same features in the lunar polar regions that cause the phenomena at each eclipse. Some of the best-observed modern eclipses can be used to assess the accuracy of the results, which are limited mainly by the intensity drop at the Sun’s edge, and the consequent uncertainty in defining the edge. In addition, direct visual contact timings made near the path edges during earlier eclipses, back to 1715, have been found in the literature, and analyzed. Although the observations seem to show small variations, they are only a little larger than the assessed accuracies. The results can be improved with a consistent re-analysis of the observations using the much more accurate lunar profile data that is now available from the Japanese Kaguya and NASA’s LRO lunar orbiter observations. Also, IOTA has plans to observe future eclipses with a variety of techniques that were used in the past, to better assess the accuracies of the different observational methods that have been used, and determine any systematic differences between them.

  8. Kinetics of PL quenching during single-walled carbon nanotube rebundling and diameter-dependent surfactant interactions.

    PubMed

    McDonald, Timothy J; Engtrakul, Chaiwat; Jones, Marcus; Rumbles, Garry; Heben, Michael J

    2006-12-21

    The kinetics of single-walled carbon nanotube rebundling have been investigated by photoluminescence (PL) spectroscopy. The rate of loss of PL intensity was measured for 12 different nanotubes in three common aqueous surfactants (sodium dodecyl sulfate, SDS; sodium dodecylbenzene sulfonate, SDBS; and sodium cholate, SC) as the surfactant suspensions were diluted to promote nanotube rebundling, quenching of semiconductor nanotube PL, and precipitation. The rate of PL decay was first-order in the concentration of isolated nanotubes, as expected if surfactant desorption is rate-limiting in the rebundling process. Temperature-dependent measurements permitted an Arrhenius analysis from which diameter-dependent activation energies were determined. SDS was found to have very strong diameter dependence for activation energy, with stronger binding to smaller-diameter nanotubes, whereas SDBS displayed a weaker diameter dependence. SC was found to bind strongly to certain nanotubes and weakly to the (10,2) nanotube. The PL emission red shifted with time after dilution as surfactant desorption proceeded. This effect is attributed to an increase in the micropolarity at the nanotube surface. PMID:17165980

  9. Rapid and selective concentration of microparticles in an optoelectrofluidic platform.

    PubMed

    Hwang, Hyundoo; Park, Je-Kyun

    2009-01-21

    We demonstrate rapid manipulation and selective concentration of microparticles using AC electrokinetics such as dielectrophoresis (DEP) and AC electro-osmosis (ACEO) in an optoelectrofluidic platform based on a liquid crystal display (LCD). When 10 V bias at 10 kHz was applied to the optoelectrofluidic device, only the 1 microm-diameter polystyrene particles were concentrated into the projected LCD image patterns and closely packed, forming the crystalline structure by ACEO flow, while the 6 microm-diameter particles were repelled by negative DEP forces. We have characterized this frequency-dependency of the optoelectrofluidic particle behavior according to the particle diameter. On the basis of these results, we can rapidly concentrate the 1 microm-diameter particles and separate them from the 6 microm particles, by applying an AC signal of 10 kHz frequency. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles in many biological and chemical applications. PMID:19107274

  10. EXPOSURE TO CONCENTRATED AMBIENT PARTICLES (CAPS): REVIEW

    EPA Science Inventory

    Epidemiologic studies support a participation of fine particulate matter (PM) with a diameter of 0.1 to 2.5 microm in the effects of air pollution particles on human health. The ambient fine particle concentrator is a recently developed technology that can enrich the mass of ambi...

  11. Particulate emissions from concentrated animal feeding operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Concentrated animal feeding operations (CAFOs), including open beef cattle feedlots, swine facilities, and poultry facilities, can emit large amounts of particulate matter, including TSP (total suspended particulates), PM10 (particulate matter with equivalent aerodynamic diameter of 10 mm or less) a...

  12. On the scaling behavior of hardness with ligament diameter of nanoporous-Au: Constrained motion of dislocations along the ligaments

    SciTech Connect

    Viswanath, R. N.; Polaki, S. R.; Rajaraman, R.; Abhaya, S.; Chirayath, V. A.; Amarendra, G.; Sundar, C. S.

    2014-06-09

    The scaling behavior of hardness with ligament diameter and vacancy defect concentration in nanoporous Au (np-Au) has been investigated using a combination of Vickers Hardness, Scanning electron microscopy, and positron lifetime measurements. It is shown that for np-Au, the hardness scales with the ligament diameter with an exponent of −0.3, that is, at variance with the conventional Hall-Petch exponent of −0.5 for bulk systems, as seen in the controlled experiments on cold worked Au with varying grain size. The hardness of np-Au correlates with the vacancy concentration C{sub V} within the ligaments, as estimated from positron lifetime experiments, and scales as C{sub V}{sup 1/2}, pointing to the interaction of dislocations with vacancies. The distinctive Hall-Petch exponent of −0.3 seen for np-Au, with ligament diameters in the range of 5–150 nm, is rationalized by invoking the constrained motion of dislocations along the ligaments.

  13. Mass-mobility characterization of flame-made ZrO2 aerosols: primary particle diameter and extent of aggregation.

    PubMed

    Eggersdorfer, M L; Gröhn, A J; Sorensen, C M; McMurry, P H; Pratsinis, S E

    2012-12-01

    Gas-borne nanoparticles undergoing coagulation and sintering form irregular or fractal-like structures affecting their transport, light scattering, effective surface area, and density. Here, zirconia (ZrO(2)) nanoparticles are generated by scalable spray combustion, and their mobility diameter and mass are obtained nearly in situ by differential mobility analyzer (DMA) and aerosol particle mass (APM) measurements. Using these data, the density of ZrO(2) and a power law between mobility and primary particle diameters, the structure of fractal-like particles is determined (mass-mobility exponent, prefactor and average number, and surface area mean diameter of primary particles, d(va)). The d(va) determined by DMA-APM measurements and this power law is in good agreement with the d(va) obtained by ex situ nitrogen adsorption and microscopic analysis. Using this combination of measurements and above power law, the effect of flame spray process parameters (e.g., precursor solution and oxygen flow rate as well as zirconium concentration) on fractal-like particle structure characteristics is investigated in detail. This reveals that predominantly agglomerates (physically-bonded particles) and aggregates (chemically- or sinter-bonded particles) of nanoparticles are formed at low and high particle concentrations, respectively. PMID:22959835

  14. Mass-Mobility Characterization of Flame-made ZrO2 Aerosols: Primary Particle Diameter & Extent of Aggregation

    PubMed Central

    Eggersdorfer, M.L.; Gröhn, A.J.; Sorensen, C.M.; McMurry, P.H.; Pratsinis, S.E.

    2013-01-01

    Gas-borne nanoparticles undergoing coagulation and sintering form irregular or fractal-like structures affecting their transport, light scattering, effective surface area and density. Here, zirconia (ZrO2) nanoparticles are generated by scalable spray combustion, and their mobility diameter and mass are obtained nearly in-situ by differential mobility analyzer (DMA) and aerosol particle mass (APM) measurements. Using these data, the density of ZrO2 and a power law between mobility and primary particle diameters, the structure of fractal-like particles is determined (mass-mobility exponent, prefactor and average number and surface area mean diameter of primary particles, dva). The dva determined by DMA-APM measurements and this power law is in good agreement with the dva obtained by ex-situ nitrogen adsorption and microscopic analysis. Using this combination of measurements and above power law, the effect of flame spray process parameters (e.g. precursor solution and oxygen flow rate as well as zirconium concentration) on fractal-like particle structure characteristics is investigated in detail. This reveals that predominantly agglomerates (physically-bonded particles) and aggregates (chemically- or sinter-bonded particles) of nanoparticles are formed at low and high particle concentrations, respectively. PMID:22959835

  15. 77 FR 13284 - Small Diameter Graphite Electrodes From the People's Republic of China: Preliminary Results and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-06

    ... Antidumping Duty Administrative Review, 76 FR 67411 (November 1, 2011), and Small Diameter Graphite Electrodes... Final Determination, 74 FR at 2054, and Small Diameter Graphite Electrodes from the People's Republic of... International Trade Administration Small Diameter Graphite Electrodes From the People's Republic of...

  16. Shape estimation for online diameter calibration in Czochralski silicon crystal growth

    NASA Astrophysics Data System (ADS)

    Kimbel, Steven L.; O'Sullivan, Joseph A.

    2001-02-01

    The diameter setpoint of a growing crystal in the silicon Czochralski process is a key cost parameter, whose optimal choice depends in part upon the diameter calibration accuracy. Measurement of the crystal diameter during solidification is made remotely, due to high temperatures and vacuum vessel design. Vision systems for diameter control detect the diameter of the bright ring reflection from the silicon melt surface at the crystal meniscus, rather than the actual crystal diameter. Distortion due to the bright ring measurement would result in a destabilizing nonlinear diameter measurement even if the crystal diameter response were linear. Using a published model of the meniscus shape, two and three-dimensional modeling of the bright ring is performed, and simple approximations are made to predict the bright ring bias as a function of diameter slope. Tracking of a diameter maximum during vertical translation could provide a calibration measure, given accurate translation data. The use of deformable templates or snakes is suggested for tracking the diameter maximum, and is bench-tested to provide estimates of on-line calibration accuracy, a key parameter for selection of the optimum diameter setpoint. Implementation of the modified calibration strategy requires corrections for camera distortion, crystal thermal expansion and window diffraction.

  17. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  18. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  19. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  20. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  1. Influence of lubricant oil on heat transfer performance of refrigerant flow boiling inside small diameter tubes. Part I: Experimental study

    SciTech Connect

    Wei, Wenjian; Ding, Guoliang; Hu, Haitao; Wang, Kaijian

    2007-10-15

    Two-phase flow pattern and heat transfer characteristics of refrigerant-oil mixture flow boiling inside small tubes with inside diameters of 6.34 mm and 2.50 mm are investigated experimentally. The test condition of nominal oil concentration is from 0% to 5%, mass flux from 200 to 400 kg m{sup -2} s{sup -1}, heat flux from 3.2 to 14 kW m{sup -2}, evaporation temperature of 5 C, inlet quality from 0.1 to 0.8, and quality change from 0.1 to 0.2. Wavy, wavy-annular, annular and mist-annular flow pattern in 6.34 mm tube are observed, while only slug-annular and annular flow pattern are observed in 2.50 mm tube. Oil presence can make annular flow to form early and to retard to diminish in quality direction at nominal oil concentration {>=}3%. Augmentation effect of oil on heat transfer coefficient becomes weakened or even diminishes for small diameter tube while detrimental effect of oil on small tube performance becomes more significant than large tube. For both test tubes, variation of heat transfer coefficient and enhanced factor with oil concentration is irregular. Two-phase heat transfer multiplier with refrigerant-oil mixture properties increases consistently and monotonically with local oil concentration at different vapor quality. (author)

  2. Effect of cyclosporin A particles of varying diameters on gastric cancer cell apoptosis.

    PubMed

    Xing, X L; Lu, Y; Qiu, H L

    2016-01-01

    Human health is significantly threatened by gastric cancer, which is the most common malignant tumor; although drastic, surgery is currently the only way to cure it. However, high recurrence rates and low survival rates are associated with the disease. Therefore, to improve the effectiveness of gastric cancer treatment and to increase the clinical cure rate, we investigated the effect of cyclosporin A particles of varying diameter on gastric cancer cell apoptosis. Flow cytometry was used to detect apoptosis induced by Annexin V-fluorescein isothiocyanate/propidium iodide-double labeling. We also determined the content of reactive oxygen species and the expression level of P-glycoprotein in cells after treatment with cyclosporin A. The results indicated that increases in the concentration and action time of cyclosporin A were associated with statistically significant increases in the apoptosis rate of gastric cancer cells when the experimental and control groups were compared (P < 0.05 and P < 0.01, respectively). In conclusion, during a certain action time and concentration range, cyclosporin A inhibits the proliferation of human gastric cancer cells and can induce their apoptosis. PMID:27173251

  3. Measurements of the Diameter and Velocity Distributions of Atomized Tablet-Coating Solutions for Pharmaceutical Applications

    NASA Astrophysics Data System (ADS)

    Osterday, Kathryn; Aliseda, Alberto; Lasheras, Juan

    2009-11-01

    The atomization of colloidal suspensions is of particular interest to the manufacturing of tablets and pills used as drug delivery systems by the pharmaceutical industry. At various stages in the manufacturing process, the tablets are coated with a spray of droplets produced by co-axial atomizers. The mechanisms of droplet size and spray formation in these types of atomizers are dominated by Kelvin-Helmholtz and Raleigh-Taylor instabilities for both low[1] and high[2] Ohnesorge numbers. We present detailed phase Doppler measurements of the Sauter Mean Diameter of the droplets produced by co-axial spray atomizers using water-based colloidal suspensions with solid concentrations ranging from fifteen to twenty percent and acetone-based colloidal suspensions with solid concentrations ranging from five to ten percent. Our results compare favorably with predictions by Aliseda's model. This suggests that the final size distribution is mainly determined by the instabilities caused by the sudden acceleration of the liquid interface. [1]Varga, C. M., et al. (2003) J. Fluid Mech. 497:405-434 [2]Aliseda, A. et al. (2008). J. Int. J. Multiphase Flow, 34(2), 161-175.

  4. Binding of plasma proteins to titanium dioxide nanotubes with different diameters.

    PubMed

    Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

    2015-01-01

    Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

  5. Binding of plasma proteins to titanium dioxide nanotubes with different diameters

    PubMed Central

    Kulkarni, Mukta; Flašker, Ajda; Lokar, Maruša; Mrak-Poljšak, Katjuša; Mazare, Anca; Artenjak, Andrej; Čučnik, Saša; Kralj, Slavko; Velikonja, Aljaž; Schmuki, Patrik; Kralj-Iglič, Veronika; Sodin-Semrl, Snezna; Iglič, Aleš

    2015-01-01

    Titanium and titanium alloys are considered to be one of the most applicable materials in medical devices because of their suitable properties, most importantly high corrosion resistance and the specific combination of strength with biocompatibility. In order to improve the biocompatibility of titanium surfaces, the current report initially focuses on specifying the topography of titanium dioxide (TiO2) nanotubes (NTs) by electrochemical anodization. The zeta potential (ζ-potential) of NTs showed a negative value and confirmed the agreement between the measured and theoretically predicted dependence of ζ-potential on salt concentration, whereby the absolute value of ζ-potential diminished with increasing salt concentrations. We investigated binding of various plasma proteins with different sizes and charges using the bicinchoninic acid assay and immunofluorescence microscopy. Results showed effective and comparatively higher protein binding to NTs with 100 nm diameters (compared to 50 or 15 nm). We also showed a dose-dependent effect of serum amyloid A protein binding to NTs. These results and theoretical calculations of total available surface area for binding of proteins indicate that the largest surface area (also considering the NT lengths) is available for 100 nm NTs, with decreasing surface area for 50 and 15 nm NTs. These current investigations will have an impact on increasing the binding ability of biomedical devices in the body leading to increased durability of biomedical devices. PMID:25733829

  6. Size-controlled large-diameter and few-walled carbon nanotube catalysts for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Xianliang; Li, Qing; Pan, Hengyu; Lin, Ye; Ke, Yujie; Sheng, Haiyang; Swihart, Mark T.; Wu, Gang

    2015-11-01

    We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic activity was observed, in both alkaline media and more demanding acidic media. The Fe-derived N-CNTs exhibited the highest BET (~870 m2 g-1) and electrochemically accessible (~450 m2 g-1) surface areas and, more importantly, the highest concentration of nitrogen incorporated into the carbon planes. Thus, in addition to the intrinsic high activity of Fe-derived catalysts, the high surface area and nitrogen doping contribute to high ORR activity. This work, for the first time, demonstrates size-controlled synthesis of large-diameter N-doped carbon tube electrocatalysts by varying the metal used in N-CNT generation. Electrocatalytic activity of the Fe-derived catalyst is already the best among studied metals, due to the high intrinsic activity of possible Fe-N coordination. This work further provides a promising route to advanced Fe-N-C nonprecious metal catalysts by generating favorable morphology with more active sites and improved mass transfer.We demonstrate a new strategy for tuning the size of large-diameter and few-walled nitrogen-doped carbon nanotubes (N-CNTs) from 50 to 150 nm by varying the transition metal (TM = Fe, Co, Ni or Mn) used to catalyze graphitization of dicyandiamide. Fe yielded the largest tubes, followed by Co and Ni, while Mn produced a clot-like carbon morphology. We show that morphology is correlated with electrocatalytic activity for the oxygen reduction reaction (ORR). A clear trend of Fe > Co > Ni > Mn for the ORR catalytic

  7. Serum Soluble Semaphorin 4D is Associated with Left Atrial Diameter in Patients with Atrial Fibrillation

    PubMed Central

    Xiang, Li; You, Tao; Chen, Jianchang; Xu, Weiting; Jiao, Yang

    2015-01-01

    Background The aim of this study was to evaluate the serum soluble semaphorin 4D (sSema4D) in patients with atrial fibrillation and to investigate the relationship of serum sSema4D with left atrial diameter (LAD). Material/Methods We studied a total of 113 patients who were subdivided into paroxysmal and non-paroxysmal (included persistent and permanent) atrial fibrillation groups, respectively. Another 55 subjects without atrial fibrillation were enrolled as the healthy control group. Serum levels of soluble semaphorin 4D (Sema4D) were measured in all subjects using the enzyme-labeled immunosorbent assay method. We also evaluated the coagulation parameters and left atrial diameters. Results Patients with paroxysmal and non-paroxysmal atrial fibrillation had significantly higher sSema4D level compared with controls (8.50±2.19 ng/mL and 9.30±2.28 ng/mL vs. 6.56±1.27 ng/ml, P<0.05). Serum sSema4D concentrations were elevated in patients with non-paroxysmal atrial fibrillation compared to those with paroxysmal atrial fibrillation (P<0.001). The level of sSema4D was positively correlated with LAD (r=0.606, P<0.001). Multivariate logistic regression analysis revealed that serum sSema4D, LAD, male sex, heart rate, hypertension, and coronary artery disease were associated with atrial fibrillation (P<0.05). Conclusions Serum sSema4D levels are increased in patients with atrial fibrillation and are independently associated with atrial remodeling. PMID:26417899

  8. Gold Nanoparticles of Diameter 13 nm Induce Apoptosis in Rabbit Articular Chondrocytes

    NASA Astrophysics Data System (ADS)

    Huang, Hao; Quan, Ying-yao; Wang, Xiao-ping; Chen, Tong-sheng

    2016-05-01

    Gold nanoparticles (AuNPs) have been widely used in biomedical science including antiarthritic agents, drug loading, and photothermal therapy. In this report, we studied the effects of AuNPs with diameters of 3, 13, and 45 nm, respectively, on rabbit articular chondrocytes. AuNPs were capped with citrate and their diameter and zeta potential were measured by dynamic light scattering (DLS). Cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay after the rabbit articular chondrocytes were pre-incubated with 3, 13, and 45 nm AuNPs, respectively, for 24 h. Flow cytometry (FCM) analysis with annexin V/propidium iodide (PI) double staining and fluorescence imaging with Hoechst 33258 staining were used to determine the fashion of AuNPs-induced chondrocyte death. Further, 13 nm AuNPs (2 nM) significantly induced chondrocyte death accompanying apoptotic characteristics including mitochondrial damage, externalization of phosphatidylserine and nuclear concentration. However, 3 nm AuNPs (2 nM) and 45 nm (0.02 nM) AuNPs did not induce cytotoxicity in chondrocytes. Although 13 nm AuNPs (2 nM) increased the intracellular reactive oxygen species (ROS) level, pretreatment with Nacetyl cysteine (NAC), a ROS scavenger, did not prevent the cytotoxicity induced by 13 nm AuNPs, indicating that 13 nm AuNPs (2 nM) induced ROS-independent apoptosis in chondrocytes. These results demonstrate the size-dependent cytotoxicity of AuNPs in chondrocytes, which must be seriously considered when using AuNPs for treatment of osteoarthritis (OA).

  9. A study of the fatigue properties of small diameter wires used in intramuscular electrodes.

    PubMed

    Scheiner, A; Mortimer, J T; Kicher, T P

    1991-05-01

    Single and multi-strand stainless steel and cobalt-nickel alloy wires, with strand diameters from 26 to 46 microns, were fatigue tested using a modified rotating bending test to determine what factors are most important in controlling fatigue life. The relation between cyclic strain and cyclic life was determined for each material by cyclically straining test specimens at various strain ranges and recording the number of cycles to failure. The results show that (a) the fatigue curves of the 316LVM, MP35N, DBS, and Syntacoben wires are very similar and have many of the same fatigue characteristics of specimens of large cross section. (b) Multi-stranded wires have the same average fatigue life as their individual constituent strands, but the variance of that life is smaller. (c) Deformities in the wire, which are created during the manufacturing, appear to have the effect of shortening the fatigue life of these small section wires. (d) Observation of wire fracture surfaces show a relatively small crack propagation zone and a large fast fracture zone suggesting that most of the fatigue life of these small wires is in the original crack formation, which creates a large stress concentration and quickly leads to wire failure. (e) The size of the wire cross sectional area is of secondary importance compared to the amplitude of the maximum cyclic strain of the individual strands in determining fatigue life of the cable. To maximize the fatigue life of electrodes in vivo, the highest fatigue life for a given bending radius of curvature is desired. This suggests wire strands should be manufactured at the smallest diameter possible (without introducing structural flaws) to maximize service life. PMID:1869576

  10. Nonsteroidal anti-inflammatory drugs alter vasa recta diameter via pericytes.

    PubMed

    Kennedy-Lydon, Teresa; Crawford, Carol; Wildman, Scott S; Peppiatt-Wildman, Claire M

    2015-10-01

    We have previously shown that vasa recta pericytes are known to dilate vasa recta capillaries in the presence of PGE2 and contract vasa recta capillaries when endogenous production of PGE2 is inhibited by the nonselective nonsteroidal anti-inflammatory drug (NSAID) indomethacin. In the present study, we used a live rat kidney slice model to build on these initial observations and provide novel data that demonstrate that nonselective, cyclooxygenase-1-selective, and cyclooxygenase -2-selective NSAIDs act via medullary pericytes to elicit a reduction of vasa recta diameter. Real-time images of in situ vasa recta were recorded, and vasa recta diameters at pericyte and nonpericyte sites were measured offline. PGE2 and epoprostenol (a prostacyclin analog) evoked dilation of vasa recta specifically at pericyte sites, and PGE2 significantly attenuated pericyte-mediated constriction of vasa recta evoked by both endothelin-1 and ANG II. NSAIDs (indomethacin > SC-560 > celecoxib > meloxicam) evoked significantly greater constriction of vasa recta capillaries at pericyte sites than at nonpericyte sites, and indomethacin significantly attenuated the pericyte-mediated vasodilation of vasa recta evoked by PGE2, epoprostenol, bradykinin, and S-nitroso-N-acetyl-l-penicillamine. Moreover, a reduction in PGE2 was measured using an enzyme immune assay after superfusion of kidney slices with indomethacin. In addition, immunohistochemical techniques were used to demonstrate the population of EP receptors in the medulla. Collectively, these data demonstrate that pericytes are sensitive to changes in PGE2 concentration and may serve as the primary mechanism underlying NSAID-associated renal injury and/or further compound-associated tubular damage. PMID:26202223

  11. Influence of diameter on particle transport in a fractured shale saprolite

    USGS Publications Warehouse

    Cumbie, D.H.; McKay, L.D.

    1999-01-01

    Experiments in an undisturbed, saturated column of weathered and fractured shale saprolite using fluorescent carboxylate-coated latex microspheres as tracers indicate that particle diameter plays a major role in controlling transport. In this study the optimum microsphere diameter for transport was approximately 0.5 ??m. Microspheres larger than the optimum size were present in the effluent at lower relative concentrations, apparently because of greater retention due to gravitational settling and/or physical straining. The smaller than optimum microspheres also experienced greater retention, apparently related to their higher rates of diffusion. Faster diffusion can lead to more frequent collisions with, and attachment to, fracture walls and may also lead to movement of particles into zones of relatively immobile pore water in the fractures or in the fine pore structure of the clay-rich matrix between fractures. Dismantling of the soil column and mapping of the distribution of retained microspheres indicated that there was substantial size-segregation of the microspheres between different fractures or in 'channels' within a fracture. Examination of small core samples showed that the smallest microspheres (0.05-0.1 ??m) were present in the fine pores of the matrix at distances of up to 3-4 mm from the nearest fracture, which supports the hypothesis that small particles can be retained by diffusion into the matrix. Calculations of settling velocity and diffusion rate using simple 1D approaches suggest that these processes could both cause significant retention of the larger and smaller particles, respectively, even for the fast advective transport rates (up to 32 m/day) observed during the experiments. Copyright (C) 1999 Elsevier Science B.V.

  12. Observation of sea-salt fraction in sub-100 nm diameter particles at Cape Grim

    NASA Astrophysics Data System (ADS)

    Cravigan, Luke T.; Ristovski, Zoran; Modini, Robin L.; Keywood, Melita D.; Gras, John L.

    2015-03-01

    Volatility-hygroscopicity tandem differential mobility analyzer measurements were used to infer the composition of sub-100 nm diameter Southern Ocean marine aerosols at Cape Grim in November and December 2007. This study focuses on a short-lived high sea spray aerosol (SSA) event on 7-8 December with two externally mixed modes in the Hygroscopic Growth Factor (HGF) distributions (90% relative humidity (RH)), one at HGF > 2 and another at HGF~1.5. The particles with HGF > 2 displayed a deliquescent transition at 73-75% RH and were nonvolatile up to 280°C, which identified them as SSA particles with a large inorganic sea-salt fraction. SSA HGFs were 3-13% below those for pure sea-salt particles, indicating an organic volume fraction (OVF) of up to 11-46%. Observed high inorganic fractions in sub-100 nm SSA is contrary to similar, earlier studies. HGFs increased with decreasing particle diameter over the range 16-97 nm, suggesting a decreased OVF, again contrary to earlier studies. SSA comprised up to 69% of the sub-100 nm particle number, corresponding to concentrations of 110-290 cm-3. Air mass back trajectories indicate that SSA particles were produced 1500 km, 20-40 h upwind of Cape Grim. Transmission electron microscopy (TEM) and X-ray spectrometry measurements of sub-100 nm aerosols collected from the same location, and at the same time, displayed a distinct lack of sea salt. Results herein highlight the potential for biases in TEM analysis of the chemical composition of marine aerosols.

  13. Gold Nanoparticles of Diameter 13 nm Induce Apoptosis in Rabbit Articular Chondrocytes.

    PubMed

    Huang, Hao; Quan, Ying-Yao; Wang, Xiao-Ping; Chen, Tong-Sheng

    2016-12-01

    Gold nanoparticles (AuNPs) have been widely used in biomedical science including antiarthritic agents, drug loading, and photothermal therapy. In this report, we studied the effects of AuNPs with diameters of 3, 13, and 45 nm, respectively, on rabbit articular chondrocytes. AuNPs were capped with citrate and their diameter and zeta potential were measured by dynamic light scattering (DLS). Cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay after the rabbit articular chondrocytes were pre-incubated with 3, 13, and 45 nm AuNPs, respectively, for 24 h. Flow cytometry (FCM) analysis with annexin V/propidium iodide (PI) double staining and fluorescence imaging with Hoechst 33258 staining were used to determine the fashion of AuNPs-induced chondrocyte death. Further, 13 nm AuNPs (2 nM) significantly induced chondrocyte death accompanying apoptotic characteristics including mitochondrial damage, externalization of phosphatidylserine and nuclear concentration. However, 3 nm AuNPs (2 nM) and 45 nm (0.02 nM) AuNPs did not induce cytotoxicity in chondrocytes. Although 13 nm AuNPs (2 nM) increased the intracellular reactive oxygen species (ROS) level, pretreatment with Nacetyl cysteine (NAC), a ROS scavenger, did not prevent the cytotoxicity induced by 13 nm AuNPs, indicating that 13 nm AuNPs (2 nM) induced ROS-independent apoptosis in chondrocytes. These results demonstrate the size-dependent cytotoxicity of AuNPs in chondrocytes, which must be seriously considered when using AuNPs for treatment of osteoarthritis (OA). PMID:27178054

  14. Pseudomagnitudes and differential surface brightness: Application to the apparent diameter of stars

    NASA Astrophysics Data System (ADS)

    Chelli, Alain; Duvert, Gilles; Bourgès, Laurent; Mella, Guillaume; Lafrasse, Sylvain; Bonneau, Daniel; Chesneau, Olivier

    2016-05-01

    The diameter of a star is a major observable that serves to test the validity of stellar structure theories. It is also a difficult observable that is mostly obtained with indirect methods since the stars are so remote. Today only ~600 apparent star diameters have been measured by direct methods: optical interferometry and lunar occultations. Accurate star diameters are now required in the new field of exoplanet studies, since they condition the planets' sizes in transit observations, and recent publications illustrate a visible renewal of interest in this topic. Our analysis is based on the modeling of the relationship between measured angular diameters and photometries. It makes use of two new reddening-free concepts: a distance indicator called pseudomagnitude, and a quasi-experimental observable that is independent of distance and specific to each star, called the differential surface brightness (DSB). The use of all the published measurements of apparent diameters that have been collected so far, and a careful modeling of the DSB allow us to estimate star diameters with a median statistical error of 1.1%, knowing their spectral type and, in the present case, the VJHKs photometries. We introduce two catalogs, the JMMC Measured Diameters Catalog (JMDC), containing measured star diameters, and the second version of the JMMC Stellar Diameter Catalog (JSDC), augmented to about 453 000 star diameters. Finally, we provide simple formulas and a table of coefficients to quickly estimate stellar angular diameters and associated errors from (V, Ks) magnitudes and spectral types.

  15. Selective control of small versus large diameter axons using infrared laser light (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lothet, Emilie H.; Shaw, Kendrick M.; Horn, Charles C.; Lu, Hui; Wang, Yves T.; Jansen, E. Duco; Chiel, Hillel J.; Jenkins, Michael W.

    2016-03-01

    Sensory information is conveyed to the central nervous system via small diameter unmyelinated fibers. In general, smaller diameter axons have slower conduction velocities. Selective control of such fibers could create new clinical treatments for chronic pain, nausea in response to chemo-therapeutic agents, or hypertension. Electrical stimulation can control axonal activity, but induced axonal current is proportional to cross-sectional area, so that large diameter fibers are affected first. Physiologically, however, synaptic inputs generally affect small diameter fibers before large diameter fibers (the size principle). A more physiological modality that first affected small diameter fibers could have fewer side effects (e.g., not recruiting motor axons). A novel mathematical analysis of the cable equation demonstrates that the minimum length along the axon for inducing block scales with the square root of axon diameter. This implies that the minimum length along an axon for inhibition will scale as the square root of axon diameter, so that lower radiant exposures of infrared light will selectively affect small diameter, slower conducting fibers before those of large diameter. This prediction was tested in identified neurons from the marine mollusk Aplysia californica. Radiant exposure to block a neuron with a slower conduction velocity (B43) was consistently lower than that needed to block a faster conduction velocity neuron (B3). Furthermore, in the vagus nerve of the musk shrew, lower radiant exposure blocked slow conducting fibers before blocking faster conducting fibers. Infrared light can selectively control smaller diameter fibers, suggesting many novel clinical treatments.

  16. Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample.

    PubMed

    Ho, Yvonne Y W; Brims, Mark; McNevin, Dennis; Spector, Timothy D; Martin, Nicholas G; Medland, Sarah E

    2016-08-01

    Hair diameter and curvature are two characteristics of human scalp hair used in forensic contexts. While previous data show that subjective categorization of hair curvature is highly heritable, the heritability of objectively measured curvature and diameter, and variability of hair characteristics within each individual have not yet been studied. The present study measured hair diameter and curvature using an optical fiber diameter analyzer in a sample of 2,332 twins and siblings. Heritability was estimated using maximum likelihood structural equation modeling. Results show sex differences in the magnitude of genetic influence for mean diameter and curvature, with the vast majority of the variance accounted for by genetic effects in males (diameter = 86%, curvature = 53%) and females (diameter = 77%, curvature = 61%). The consistency of diameter (variance within an individual) was also highly heritable, but did not show sex limitation, with 68% of the variance accounted for by genetic factors. Moderate phenotypic correlations were seen between diameter and consistency (r = 0.3) but there was little correlation between diameter and curvature (r = -0.13). A bivariate Cholesky analysis was used to estimate the genetic and environmental correlations between hair diameter and consistency, yielding genetic correlations of r gF = 0.27 for females and r gM = 0.25 for males. PMID:27291867

  17. Substrate diameter and compliance affect the gripping strategies and locomotor mode of climbing boa constrictors.

    PubMed

    Byrnes, Greg; Jayne, Bruce C

    2010-12-15

    Arboreal habitats pose unique challenges for locomotion as a result of their narrow cylindrical surfaces and discontinuities between branches. Decreased diameter of branches increases compliance, which can pose additional challenges, including effects on stability and energy damping. However, the combined effects of substrate diameter and compliance are poorly understood for any animal. We quantified performance, kinematics and substrate deformation while boa constrictors (Boa constrictor) climbed vertical ropes with three diameters (3, 6 and 9 mm) and four tensions (0.5, 1.0, 1.5 and 2.0 body weights). Mean forward velocity decreased significantly with both decreased diameter and increased compliance. Both diameter and compliance had numerous effects on locomotor kinematics, but diameter had larger and more pervasive effects than compliance. Locomotion on the largest diameter had a larger forward excursion per cycle, and the locomotor mode and gripping strategy differed from that on the smaller diameters. On larger diameters, snakes primarily applied opposing forces at the same location on the rope to grip. By contrast, on smaller diameters forces were applied in opposite directions at different locations along the rope, resulting in increased rope deformation. Although energy is likely to be lost during deformation, snakes might use increased surface deformation as a strategy to enhance their ability to grip. PMID:21113006

  18. Transmissive Diffractive Optical Element Solar Concentrators

    NASA Technical Reports Server (NTRS)

    Baron, Richard; Moynihan, Philip; Price, Douglas

    2008-01-01

    Solar-thermal-radiation concentrators in the form of transmissive diffractive optical elements (DOEs) have been proposed as alternatives to mirror-type solar concentrators now in use. In comparison with functionally equivalent mirror-type solar concentrators, the transmissive, diffractive solar concentrators would weigh and cost less, and would be subject to relaxed mechanical tolerances. A DOE concentrator would be made from a thin, flat disk or membrane of a transmissive material having a suitable index of refraction. By virtue of its thinness, the DOE concentrator would have an areal mass density significantly less than that of a functionally equivalent conventional mirror. The DOE concentrator would have a relatively wide aperture--characterized by a focal-length/aperture-diameter ratio ('f number') on the order of 1. A kinoform (a surface-relief phase hologram) of high diffractive order would be microfabricated onto one face of the disk. The kinoform (see figure) would be designed to both diffract and refract incident solar radiation onto a desired focal region, without concern for forming an image of the Sun. The high diffractive order of this kinoform (in contradistinction to the low diffractive orders of some other kinoforms) would be necessary to obtain the desired f number of 1, which, in turn, would be necessary for obtaining a desired concentration ratio of 2,500 or greater. The design process of optimizing the concentration ratio of a proposed DOE solar concentrator includes computing convolutions of the optical bandwidth of the Sun with the optical transmission of the diffractive medium. Because, as in the cases of other non-imaging, light-concentrating optics, image quality is not a design requirement, the process also includes trading image quality against concentration ratio. A baseline design for one example calls for an aperture diameter of 1 m. This baseline design would be scalable to a diameter as large as 10 m, or to a smaller diameter for a

  19. Aerosol and cloud droplet number concentrations observed in marine stratocumulus

    SciTech Connect

    Vong, R.J.; Covert, D.S.

    1995-12-01

    The relationship between measurements of cloud droplet number concentration and cloud condensation nuclei (CCN) concentration, as inferred from aerosol size spectra, was investigated at a {open_quote}clean air{close_quote}, marine site (Cheeka Peak) located near the coast of the Olympic Peninsula in Washington State. Preliminary results demonstrated that cloud droplet number increased and droplet diameter decreased as aerosol number concentration (CCN) increased. These results support predictions of a climate cooling due to any future increases in marine aerosol concentrations.

  20. 78 FR 41369 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ... on certain small diameter carbon and alloy seamless standard, line and pressure pipe (small diameter... diameter seamless pipe. The small diameter seamless pipe subject to the order is currently classifiable... small diameter seamless pipe from Romania entered, or withdrawn from warehouse, for......

  1. Protein Adsorption From Biofluids on Silica Nanoparticles: Corona Analysis as a Function of Particle Diameter and Porosity.

    PubMed

    Clemments, Alden M; Botella, Pablo; Landry, Christopher C

    2015-10-01

    A study on the adsorption of proteins from fetal bovine serum (FBS) on spherical dense and mesoporous silica nanoparticles with a wide range of diameters, from 70 to 900 nm, is presented. Monodisperse populations of particles with a range of diameters were obtained through modifications of the Stöber method. Extensive characterization of the particles was then performed using N2 physisorption, TEM, DLS, and ζ-potential. Following serum exposure, proteomic evaluation in concert with thermogravimetric analysis revealed the associated concentrations of each protein identified in the hard corona. Small particles adsorbed the largest amount of protein, due to their larger external surface area. Proteins with low molecular weights (<50 kDa) constituted the majority of the protein corona, totaling between 60 and 80% of the total mass of adsorbed protein. Here, the higher surface curvature of small particles favors the enrichment of smaller proteins. Porosity does not promote protein adsorption but improves deposition of the low molecular weight protein fraction due to the size-exclusion effect related to pore diameter. These results have important implications for the use of dense and porous silica nanoparticles in biomedical applications. PMID:26371804

  2. The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system.

    PubMed

    Liu, Jingqing; Chen, Huanyu; Yao, Lingdan; Wei, Zongyuan; Lou, Liping; Shan, Yonggui; Endalkachew, Sahle-Demessie; Mallikarjuna, Nadagouda; Hu, Baolan; Zhou, Xiaoyan

    2016-11-01

    In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography-Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better. PMID:27244696

  3. Imaging and controlling intracellular reactions: Lysosome transport as a function of diameter and the intracellular synthesis of conducting polymers

    NASA Astrophysics Data System (ADS)

    Payne, Christine

    2014-03-01

    Eukaryotic cells are the ultimate complex environment with intracellular chemical reactions regulated by the local cellular environment. For example, reactants are sequestered into specific organelles to control local concentration and pH, motor proteins transport reactants within the cell, and intracellular vesicles undergo fusion to bring reactants together. Current research in the Payne Lab in the School of Chemistry and Biochemistry at Georgia Tech is aimed at understanding and utilizing this complex environment to control intracellular chemical reactions. This will be illustrated using two examples, intracellular transport as a function of organelle diameter and the intracellular synthesis of conducting polymers. Using single particle tracking fluorescence microscopy, we measured the intracellular transport of lysosomes, membrane-bound organelles, as a function of diameter as they underwent transport in living cells. Both ATP-dependent active transport and diffusion were examined. As expected, diffusion scales with the diameter of the lysosome. However, active transport is unaffected suggesting that motor proteins are insensitive to cytosolic drag. In a second example, we utilize intracellular complexity, specifically the distinct micro-environments of different organelles, to carry out chemical reactions. We show that catalase, found in the peroxisomes of cells, can be used to catalyze the polymerization of the conducting polymer PEDOT:PSS. More importantly, we have found that a range of iron-containing biomolecules are suitable catalysts with different iron-containing biomolecules leading to different polymer properties. These experiments illustrate the advantage of intracellular complexity for the synthesis of novel materials.

  4. Diameter and wall number control of carbon nanotubes by chemical vapor deposition

    SciTech Connect

    Xie, Rongsi; Zhong, Guofang Zhang, Can; Chen, Bingan; Santiago Esconjauregui, C.; Robertson, John

    2013-12-28

    We analyze the relationship between the average wall number (N) and the diameter (d) for carbon nanotubes (CNTs) grown by chemical vapour deposition. It is found that N depends linearly on d for diameters in the range of 2.5–10 nm, while single wall nanotubes predominate for diameters under about 2.1 nm. The linear relationship is found to depend somewhat on the growth conditions. It is also verified that the mean diameter depends on the diameter of the originating catalyst nanoparticle, and thus on the initial catalyst thickness where a thin film catalyst is used. This simplifies the characterisation of CNTs by electron microscopy. We also find a linear relationship between nanotube diameter and initial catalyst film thickness.

  5. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0...

  6. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0...

  7. Production of a Large-Diameter Uniform ECR Plasma with a Lisitano Coil

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Takeuchi, Yoshiaki; Komori, Akio; Kawai, Yoshinobu

    1988-09-01

    A large-diameter uniform plasma was demonstrated to be produced by electron cyclotron resonance heating with a slotted Lisitano coil of 40 cm diameter. The diameter of the realized uniform plasma was found to be almost equal to that of the Lisitano coil. It was also suggested that the microwave is propagated in the whole region inside the Lisitano coil, and produces the uniform plasma.

  8. Optimized planar micro-optic concentrator design

    NASA Astrophysics Data System (ADS)

    Pan, Jui-Wen; Su, Yu-Chung; Lee, Sheng-Yi

    2016-06-01

    The structural parameters of a planar micro-optic concentrator are optimized. First, the direct-loss is minimized by altering the relationship between the f-number of the lenslet, the angle of the micro-structure and the ray paths in the planar micro-optic concentrator. Second, the size of the micro-structure is made equal to the mini-blur size of the lenslet in order to reduce the non-direct loss. Last, the f-number and the entrance pupil diameter of the lenslet are determined by the relationships among the f-number, the entrance pupil diameter, the optical efficiency, the acceptance angle and the thickness of the planar micro-optic concentrator from the optical simulation results. For an optimized planar micro-optic concentrator with a 300× concentration, the f-number of the lenslet, the EPD of the lenslet, the angle of the micro-structure and the thickness of the planar micro-optic concentrator are 2.6, 1.49 mm, 120 degrees and 5.97 mm, respectively. For micro-structures 28.95 μm, 51.24 μm and 88.29 μm in size, the half acceptance angles of the planar micro-optic concentrator are 0.115 degrees, 0.275 degrees and 0.55 degrees, respectively, and the optical efficiencies are 81.23%, 71.92% and 50.02%, respectively.

  9. Tracer study of batch sedimentation. [Resin beads - 45 and 62. mu. m in diameter

    SciTech Connect

    Bigot, P.C.; Lee, A.H.

    1982-04-01

    The initial particle-concentration profile in batch settling tests was assessed and determined to be uniform. Two sets of data for batch-settling tests using cobalt-57-traced ion-exchange resin beads (45 and 62 ..mu..m in diameter) were compared with existing theories and models. A single suspended-solids zone was observed in agreement with the predictions of Dixon; the Richardson-Zaki correlation predicted the settling velocity as a function of void fraction to within 5%. Studies with a bimodal particle-size distribution of equal fraction of 45- and 62-..mu..m particles showed that the larger particles settled at the same velocity as in a single-particle-size distribution but that the smaller ones settled slower than for a single-particle-size distribution at a given void fraction. The ratio of the settling velocity of the smaller particles in a bimodal-particle-size distribution u/sub b/ to the settling velocity of these particles in a single particle-size distribution u/sub s/ was correlated by raising to the (3.78 +- 0.47) power the effective void fraction of the resulting upper settling zone containing only the smaller particles.

  10. Highly ordered nanoporous carbon films with tunable pore diameters and their excellent sensing properties.

    PubMed

    Jia, Lichao; Lawrence, Geoffrey; Balasubramanian, V V; Choi, Goeun; Choy, Jin-Ho; Abdullah, Aboubakr M; Elzatahry, Ahmed; Ariga, Katsuhiko; Vinu, Ajayan

    2015-01-01

    Ordered porous carbon films with tunable pore diameters, immobilized with glucose oxidase (GOD) have been fabricated and employed for the construction of a biosensor for glucose molecules. The as-prepared porous films have large specific surface areas and highly ordered porous structure with uniform pore sizes, which are critical for the immobilization of large amounts of GOD and support the promotion of heterogeneous electron transfer. The developed biosensors give enough room for the encapsulation of a high amount of GOD molecules and show excellent biosensing performance with a linear response to glucose concentration ranging from 0.5 to 9 mM and a detection limit of 1.5 μM. It is also demonstrated that the sensitivity of the biosensor can be easily tuned by modulating the pore size of carbon film as it dictates the amount of immobilization of GOD in the porous channels. The fabricated carbon-film-based biosensor has a good stability and a high reproducibility, which opens the gateway for the commercialization of this excellent technology. PMID:25394330

  11. Profile Control by Biased Electrodes in Large Diameter RF Produced Pl asma

    NASA Astrophysics Data System (ADS)

    Shinohara, Shunjiro; Matsuoka, Norikazu; Yoshinaka, Toshiro

    1998-10-01

    Control of the plasma profile has been carried out, using the voltage biasing method in the large diameter (45 cm) RF (radio frequency) produced plasma in the presence of the uniform magnetic field (less than 1200 G). Under the low filling pressure condition of 0.16 mTorr, changing the biasing voltages to the three individual end plates with concentric circular ring shapes, the radial electron density (about 10^10 cm-3) profile could be changed from the hollow to the peaked one. On the contrary, the nearly flat electron temperature (several eV) profile did not change appreciably. The azimuthal rotation velocity measured by the Mach probe, i.e. directional probe, showed the different radial profiles (but nearly uniform along the axis) depending on the biasing voltage. This velocity became slower with the low magnetic field (less than 200 G) or in the higher pressure regime up to 20 mTorr with the higher electron density. The experimental results by other biasing methods will also be presented.

  12. Physiologic Compliance in Engineered Small-diameter Arterial Constructs Based on an Elastomeric Substrate

    PubMed Central

    CRAPO, PETER M.; WANG, YADONG

    2009-01-01

    Compliance mismatch is a significant challenge to long-term patency in small-diameter bypass grafts because it causes intimal hyperplasia and ultimately graft occlusion. Current engineered grafts are typically stiff with high burst pressure but low compliance and low elastin expression. We postulated that engineering small arteries on elastomeric scaffolds under dynamic mechanical stimulation would result in strong and compliant arterial constructs. Compare properties of engineered arterial constructs based on biodegradable polyester scaffolds composed of either rigid poly(lactide-co-glycolide) (PLGA) or elastomeric poly(glycerol sebacate) (PGS). Adult baboon arterial smooth muscle cells (SMCs) were cultured in vitro for 10 days in tubular, porous scaffolds. Scaffolds were significantly stronger after culture regardless of material, but the elastic modulus of PLGA constructs was an order of magnitude greater than that of porcine carotid arteries and PGS constructs. Deformation was elastic in PGS constructs and carotid arteries but plastic in PLGA constructs. Compliance of arteries and PGS constructs were equivalent at pressures tested. Altering scaffold material from PLGA to PGS significantly decreased collagen content and significantly increased insoluble elastin content in constructs without affecting soluble elastin concentration in the culture medium. PLGA constructs contained no appreciable insoluble elastin. This research demonstrates that: (1) substrate stiffness directly affects in vitro tissue development and mechanical properties; (2) rigid materials likely inhibit elastin incorporation into the extracellular matrix of engineered arterial tissues; and (3) grafts with physiologic compliance and significant elastin content can be engineered in vitro after only days of cell culture. PMID:19962188

  13. Modeling ozone removal to indoor materials, including the effects of porosity, pore diameter, and thickness.

    PubMed

    Gall, Elliott T; Siegel, Jeffrey A; Corsi, Richard L

    2015-04-01

    We develop an ozone transport and reaction model to determine reaction probabilities and assess the importance of physical properties such as porosity, pore diameter, and material thickness on reactive uptake of ozone to five materials. The one-dimensional model accounts for molecular diffusion from bulk air to the air-material interface, reaction at the interface, and diffusive transport and reaction through material pore volumes. Material-ozone reaction probabilities that account for internal transport and internal pore area, γ(ipa), are determined by a minimization of residuals between predicted and experimentally derived ozone concentrations. Values of γ(ipa) are generally less than effective reaction probabilities (γ(eff)) determined previously, likely because of the inclusion of diffusion into substrates and reaction with internal surface area (rather than the use of the horizontally projected external material areas). Estimates of γ(ipa) average 1 × 10(-7), 2 × 10(-7), 4 × 10(-5), 2 × 10(-5), and 4 × 10(-7) for two types of cellulose paper, pervious pavement, Portland cement concrete, and an activated carbon cloth, respectively. The transport and reaction model developed here accounts for observed differences in ozone removal to varying thicknesses of the cellulose paper, and estimates a near constant γ(ipa) as material thickness increases from 0.02 to 0.16 cm. PMID:25748309

  14. Electrospun biodegradable elastic polyurethane scaffolds with dipyridamole release for small diameter vascular grafts.

    PubMed

    Punnakitikashem, Primana; Truong, Danh; Menon, Jyothi U; Nguyen, Kytai T; Hong, Yi

    2014-11-01

    Acellular biodegradable small diameter vascular grafts (SDVGs) require antithrombosis, intimal hyperplasia inhibition and rapid endothelialization to improve the graft patency. However, current antithrombosis and antiproliferation approaches often conflict with endothelial cell layer formation on SDVGs. To address this limitation, biodegradable elastic polyurethane urea (BPU) and the drug dipyridamole (DPA) were mixed and then electrospun into a biodegradable fibrous scaffold. The BPU would provide the appropriate mechanical support, while the DPA in the scaffold would offer biofunctions as required above. We found that the resulting scaffolds had tensile strengths and strains comparable with human coronary artery. The DPA in the scaffolds was continuously released up to 91 days in phosphate buffer solution at 37 °C, with a low burst release within the first 3 days. Compared to BPU alone, improved non-thrombogenicity of the DPA-loaded BPU scaffolds was evidenced with extended human blood clotting time, lower TAT complex concentration, lower hemolysis and reduced human platelet deposition. The scaffolds with a higher DPA content (5 and 10%) inhibited proliferation of human aortic smooth muscle cell significantly. Furthermore, the DPA-loaded scaffolds had no adverse effect on human aortic endothelial cell growth, yet it improved their proliferation. The attractive mechanical properties and biofunctions of the DPA-loaded BPU scaffold indicate its potential as an acellular biodegradable SDVG for vascular replacement. PMID:25110284

  15. Electrospun biodegradable elastic polyurethane scaffolds with dipyridamole release for small diameter vascular grafts

    PubMed Central

    Punnakitikashem, Primana; Truong, Danh; Menon, Jyothi U.; Nguyen, Kytai T.; Hong, Yi

    2014-01-01

    Acellular biodegradable small diameter vascular grafts (SDVGs) require antithrombosis, intimal hyperplasia inhibition and rapid endothelialization to improve the graft patency. However, current antithrombosis and antiproliferation approaches often conflict with endothelial cell layer formation on SDVGs. To address this limitation, biodegradable elastic polyurethane urea (BPU) and the drug dipyridamole (DPA) were mixed and then electrospun into a biodegradable fibrous scaffold. The BPU would provide the appropriate mechanical support, while the DPA in the scaffold would offer biofunctions as required above. We found that the resulting scaffolds had tensile strengths and strains comparable with human coronary artery. The DPA in the scaffolds was continuously released up to 91 days in phosphate buffer solution at 37 °C, with a low burst release within the first 3 days. Compared to BPU alone, improved non-thrombogenicity of the DPA-loaded BPU scaffolds was evidenced with extended human blood clotting time, lower TAT complex concentration, lower hemolysis and reduced human platelet deposition. The scaffolds with a higher DPA content (5 and 10%) inhibited proliferation of human aortic smooth muscle cell significantly. Furthermore, the DPA-loaded scaffolds had no adverse effect on human aortic endothelial cell growth, yet it improved their proliferation. The attractive mechanical properties and biofunctions of the DPA-loaded BPU scaffold indicate its potential as an acellular biodegradable SDVG for vascular replacement. PMID:25110284

  16. Measurement of Vein Diameter for Peripherally Inserted Central Catheter (PICC) Insertion: An Observational Study.

    PubMed

    Sharp, Rebecca; Cummings, Melita; Childs, Jessie; Fielder, Andrea; Mikocka-Walus, Antonina; Grech, Carol; Esterman, Adrian

    2015-01-01

    Choosing an appropriately sized vein reduces the risk of venous thromboembolism associated with peripherally inserted central catheters. This observational study described the diameters of the brachial, basilic, and cephalic veins and determined the effect of patient factors on vein size. Ultrasound was used to measure the veins of 176 participants. Vein diameter was similar in both arms regardless of hand dominance and side. Patient factors-including greater age, height, and weight, as well as male gender-were associated with increased vein diameter. The basilic vein tended to have the largest diameter statistically. However, this was the case in only 55% of patients. PMID:26339941

  17. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, David A.

    1982-01-01

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  18. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, D.A.

    1980-05-30

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  19. Relating Airway Diameter Distributions to Regular Branching Asymmetry in the Lung

    NASA Astrophysics Data System (ADS)

    Majumdar, Arnab; Alencar, Adriano M.; Buldyrev, Sergey V.; Hantos, Zoltán; Lutchen, Kenneth R.; Stanley, H. Eugene; Suki, Béla

    2005-10-01

    We study the distribution Πn(D) of airway diameters D as a function of generation N in asymmetric airway trees of mammalian lungs. We find that the airway bifurcations are self-similar in four species studied. Specifically, the ratios of diameters of the major and minor daughters to their parent are constants independent of N until a cutoff diameter is reached. We derive closed form expressions for ΠN(D) and examine the flow resistance of the tree based on an asymmetric flow division model. Our findings suggest that the observed diameter heterogeneity is consistent with an underlying regular branching asymmetry.

  20. Remote-sensing-based measurement of phytoplankton size spectrum and cell diameter in the global oceans

    NASA Astrophysics Data System (ADS)

    Roy, S.; Sathyendranath, S.; Bouman, H. A.; Platt, T.

    2012-12-01

    Oceanic phytoplankton regulate the spectral quality of the submarine light field because light absorption by phytoplankton is spectrally structured, with a maximum in the blue and a secondary maximum in the red. The spectral characteristics of absorption are variable with phytoplankton taxa, and also with cell size and growth conditions. The intra-cellular concentration of light-absorbing pigments varies with phytoplankton size, which in turn modulates its specific absorption. The changes in phytoplankton cell size alter not only the bio-optical properties of the water column, but also the trophic interactions within the ecosystem. It is thus important to study the time evolution of phytoplankton size structure over the global ocean. We have developed a novel model that uses the light absorption coefficient of phytoplankton to retrieve quantitative information about phytoplankton size structure from satellite-derived ocean-colour data. The application of the method to satellite remote sensing at any given spatial location depends on the estimates of the concentration of chlorophyll-a, which is an operational index of phytoplankton biomass, and the remote sensing reflectance at different wavelengths in the visible domain. Using our method we have computed the equivalent spherical diameter of phytoplankton cells and the exponent of particle-size spectrum of phytoplankton, and thereby estimated the chlorophyll distribution in different phytoplankton size classes on a global scale. The spatial distribution of the size-spectrum exponent and the biomass fractions of pico-, nano- and micro-phytoplankton estimated are consistent with our current understanding of phytoplankton functional types in the global oceans. The study will enhance our understanding of the distribution and time evolution of phytoplankton size structure in the global oceans.

  1. Dynamics of leaf gas exchange, chlorophyll fluorescence and stem diameter changes during freezing and thawing of Scots pine seedlings.

    PubMed

    Lindfors, Lauri; Hölttä, Teemu; Lintunen, Anna; Porcar-Castell, Albert; Nikinmaa, Eero; Juurola, Eija

    2015-12-01

    Boreal trees experience repeated freeze-thaw cycles annually. While freezing has been extensively studied in trees, the dynamic responses occurring during the freezing and thawing remain poorly understood. At freezing and thawing, rapid changes take place in the water relations of living cells in needles and in stem. While freezing is mostly limited to extracellular spaces, living cells dehydrate, shrink and their osmotic concentration increases. We studied how the freezing-thawing dynamics reflected on leaf gas exchange, chlorophyll fluorescence and xylem and living bark diameter changes of Scots pine (Pinus sylvestris L.) saplings in controlled experiments. Photosynthetic rate quickly declined following ice nucleation and extracellular freezing in xylem and needles, almost parallel to a rapid shrinking of xylem diameter, while that of living bark followed with a slightly longer delay. While xylem and living bark diameters responded well to decreasing temperature and water potential of ice, the relationship was less consistent in the case of increasing temperature. Xylem showed strong temporal swelling at thawing suggesting water movement from bark. After thawing xylem diameter recovered to a pre-freezing level but living bark remained shrunk. We found that freezing affected photosynthesis at multiple levels. The distinct dynamics of photosynthetic rate and stomatal conductance reveals that the decreased photosynthetic rate reflects impaired dark reactions rather than stomatal closure. Freezing also inhibited the capacity of the light reactions to dissipate excess energy as heat, via non-photochemical quenching, whereas photochemical quenching of excitation energy decreased gradually with temperature in agreement with the gas exchange data. PMID:26423334

  2. Quantification of pulmonary vessel diameter in low-dose CT images

    NASA Astrophysics Data System (ADS)

    Rudyanto, Rina D.; Ortiz de Solórzano, Carlos; Muñoz-Barrutia, Arrate

    2015-03-01

    Accurate quantification of vessel diameter in low-dose Computer Tomography (CT) images is important to study pulmonary diseases, in particular for the diagnosis of vascular diseases and the characterization of morphological vascular remodeling in Chronic Obstructive Pulmonary Disease (COPD). In this study, we objectively compare several vessel diameter estimation methods using a physical phantom. Five solid tubes of differing diameters (from 0.898 to 3.980 mm) were embedded in foam, simulating vessels in the lungs. To measure the diameters, we first extracted the vessels using either of two approaches: vessel enhancement using multi-scale Hessian matrix computation, or explicitly segmenting them using intensity threshold. We implemented six methods to quantify the diameter: three estimating diameter as a function of scale used to calculate the Hessian matrix; two calculating equivalent diameter from the crosssection area obtained by thresholding the intensity and vesselness response, respectively; and finally, estimating the diameter of the object using the Full Width Half Maximum (FWHM). We find that the accuracy of frequently used methods estimating vessel diameter from the multi-scale vesselness filter depends on the range and the number of scales used. Moreover, these methods still yield a significant error margin on the challenging estimation of the smallest diameter (on the order or below the size of the CT point spread function). Obviously, the performance of the thresholding-based methods depends on the value of the threshold. Finally, we observe that a simple adaptive thresholding approach can achieve a robust and accurate estimation of the smallest vessels diameter.

  3. Prediction of quadruple hamstring graft diameter for anterior cruciate ligament reconstruction by anthropometric measurements

    PubMed Central

    Asif, Naiyer; Ranjan, Rahul; Ahmed, Sohail; Sabir, Aamir B; Jilani, Latif Z; Qureshi, Owais A

    2016-01-01

    Background: The literature is scanty regarding the anthropometric predictors on the diameter of quadruple hamstring graft obtained in anterior cruciate ligament (ACL) reconstruction in Indian population. Minimum diameter of the graft for ACL reconstruction should be >7 mm to preclude failure. The objective of this study was to assess the prediction of the hamstring graft diameter by several anthropometric parameters including age, thigh circumference, weight, height and body mass index (BMI). Materials and Methods: 46 consecutive patients who had undergone ACL reconstruction by the same surgeon using quadruple hamstring grafts were evaluated. The age, thigh circumference of the normal side, height, weight and BMI were recorded preoperatively and Pearson correlation was done using these parameters with graft diameter measured intraoperatively. Regression analysis in a stepwise manner was undertaken to assess the influence of individual anthropometric parameters on the graft diameter. Results: There were 44 males and 2 females. Mean age was 29.4 years, mean height was 172.6 cm, mean weight was 70.9 kg, mean BMI was 23.8 kg/m2, mean thigh circumference was 47.1 cm and mean graft diameter was 7.9 mm. There was a positive correlation individually between the thigh circumference and graft diameter obtained (r = 0.8, P < 0.01, n = 46), and between the height and graft diameter (r = 0.8, P < 0.01, n = 46). On the regression analysis thigh circumference and height were found to be significant predictors of graft diameter giving the following equation: Graft diameter (mm) = 0. 079 height (cm) +0.068 thigh circumference (cm) −9.031. Conclusion: Preoperatively using the above equation if graft diameter came out to be <7 mm then alternate options of graft material must be kept in mind in order to prevent failure. PMID:26955176

  4. g Dependent particle concentration due to sedimentation

    NASA Astrophysics Data System (ADS)

    Haranas, Ioannis; Gkigkitzis, Ioannis; Zouganelis, George D.

    2012-11-01

    Sedimentation of particles in a fluid has long been used to characterize particle size distribution. Stokes' law is used to determine an unknown distribution of spherical particle sizes by measuring the time required for the particles to settle a known distance in a fluid of known viscosity and density. In this paper, we study the effects of gravity on sedimentation by examining the resulting particle concentration distributed in an equilibrium profile of concentration C m, n above the bottom of a container. This is for an experiment on the surface of the Earth and therefore the acceleration of gravity had been corrected for the oblateness of the Earth and its rotation. Next, at the orbital altitude of the spacecraft in orbit around Earth the acceleration due to the central field is corrected for the oblateness of the Earth. Our results show that for experiments taking place in circular or elliptical orbits of various inclinations around the Earth the concentration ratio C m, n / C m, ave , the inclination seems to be the most ineffective in affecting the concentration among all the orbital elements. For orbital experiment that use particles of diameter d p =0.001 μm the concentration ratios for circular and slightly elliptical orbits in the range e=0-0.1 exhibit a 0.009 % difference. The concentration ratio increases with the increase of eccentricity, which increases more for particles of larger diameters. Finally, for particles of the same diameter concentration ratios between Earth and Mars surface experiments are related in the following way C_{(m,n)_{mathit{Earth}}} = 0.99962 C_{(m,n)_{mathit{Mars}}}.

  5. On-substrate fabrication of porous Al2O3 templates with tunable pore diameters and interpore distances

    NASA Astrophysics Data System (ADS)

    Berger, Nele; Habouti, Salah; Rubahn, Horst-Günter; Es-Souni, Mohammed

    2016-03-01

    This work is focused on the on-substrate fabrication of porous aluminum oxide templates by anodization of a thin aluminum film deposited directly on the substrate using different concentrations of oxalic acid. These on-substrate templates are used for fabricating supported, free-standing nanorod (NR)-arrays by electrochemical deposition of Pt followed by the removal of the template. The interpore distance of the templates is tuned by varying the concentration of the electrolyte used for anodization and the applied voltage. The diameter of the pores (and thus the NRs of the resulting array) and wall thickness are influenced by modifying the pore opening time during immersion the sample in H3PO4.

  6. Triamcinolone Acetonide Selectively Inhibits Angiogenesis in Small Blood Vessels and Decreases Vessel Diameter within the Vascular Tree

    NASA Technical Reports Server (NTRS)

    McKay, Terri L.; Gredeon, Dan J.; Vickerman, Mary B.; Hylton, alan G.; Ribita, Daniela; Olar, Harry H.; Kaiser, Peter K.; Parsons-Wingerter, Patricia

    2007-01-01

    The steroid triamcinolone acetonide (TA) is a potent anti-angiogenesis drug used to treat retinal vascular diseases that include diabetic retinopathy, vascular occlusions and choroidal neovascularization. To quantify the effects of TA on branching morphology within the angiogenic microvascular tree of the chorioallantoic membrane (CAM) of quail embryos. Increasing concentrations of TA (0-16 ng/ml) were applied topically on embryonic day 7 (E7) to the chorioallantoic membrane (CAM) of quail embryos cultured in Petri dishes, and incubated for an additional 24 or 48 hours until fixation. Binary (black/white) microscopic images of arterial end points were quantified by VESGEN software (for Generational Analysis of Vessel Branching) to obtain major vascular parameters that include vessel diameter (Dv), fractal dimension (Df), tortuosity (Tv) and densities of vessel area, length, number and branch point (Av, Lv, Nv and Brv). For assessment of specific changes in vascular morphology induced by TA, the VESGEN software automatically segmented the vascular tree into branching generations (G1...G10) according to changes in vessel diameter and branching. Vessel density decreased significantly up to 34% as the function of increasing concentration of TA according to Av, Lv, Brv, Nv and Df. TA selectively inhibited the growth of new, small vessels, because Lv decreased from 13.14plus or minus 0.61 cm/cm2 for controls to 8.012 plus or minus 0.82 cm/cm2 at 16 ng TA/ml in smaller branching generations (G7-G10), and for Nv from 473.83 plus or minus 29.85 cm(-)2 to 302.32 plus or minus 33.09 cm-()2. In contrast, vessel diameter (Dv) decreased throughout the vascular tree (G1-G10).

  7. Mechanistic insights derived from retardation and peak broadening of particles up to 200 nm in diameter in electrophoresis in semidilute polyacrylamide solutions.

    PubMed

    Radko, S P; Chrambach, A

    1998-10-01

    Rigid spherical particles in the size range of 5-200 nm diameter were subjected to capillary zone electrophoresis (CZE) in semidilute solutions of uncross-linked polyacrylamide of M(r) 5, 7 and 18 x 10(6) (PA-5, -7 and -18, respectively) of varying concentrations up to 1.6% and at field strengths varying from 68 to 270 V/cm. For all particles under study, the experimental Ferguson plots, log(mobility) vs. polymer concentration, permit a linear approximation. Their slope, the retardation coefficient KR = delta log (mobility)/delta (concentration), for particles smaller than 30 nm in diameter increased with particle size in PA-5 and -7 independently of electric field strength and polymer M(r). The KR of particles of 30 nm in diameter or more was found to be independent of particle size at the lowest field strength used but to decrease with it at the higher values of field strength. The decrease was parallel but shifted to higher values of retardation when the polymer M(r) increased from 5 to 7 x 10(6). With a decreasing ratio of average mesh size of the polymer network, zeta, to particle radius, R, the approach to "continuity" of the polymeric medium (zeta/R < 1) with both increasing particle size and polymer concentration does not result in the retardation behavior expected according to the macroscopic (bulk) viscosity of the solution. These experimental observations were hypothetically interpreted in terms of a transition to a retardation mechanism comprising the formation of a polymer depletion layer near the particle surface--polymer solution interface. Peak width exhibited an overall increase with PA-7 concentration for all particles studied. For particles of 30 nm in diameter or less, the increase was steepest when the radius of the particle was approximately commensurate with zeta at a given polymer concentration. For the largest particle, 205 nm in diameter, peak broadening with polymer concentration was found to correlate linearly with peak asymmetry. CZE of

  8. Patch diameter limitation due to high chirp rates in focused SAR images

    NASA Astrophysics Data System (ADS)

    Doerry, Armin W.

    1994-10-01

    Polar-format processed synthetic aperture radar (SAR) images have a limited focused patch diameter that results from unmitigated phase errors. Very high chirp rates, encountered with fine-resolution short-pulse radars, exasperate the problem via a residual video phase error term. This letter modifies the traditional maximum patch diameter expression to include effects of very high chirp rates.

  9. Assessment of pubertal development of boars derived from ultrasonographic determination of testicular diameter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    At the onset of puberty, seminiferous tubules rapidly increase in diameter occupying a greater proportion of the testis with a consequent rapid increase in testicular size. The objective of the current studies was to evaluate the utility of ultrasonography to assess testicular diameter as a basis fo...

  10. A Method to Improve the Accuracy of Particle Diameter Measurements from Shadowgraph Images

    NASA Astrophysics Data System (ADS)

    Erinin, Martin A.; Wang, Dan; Liu, Xinan; Duncan, James H.

    2015-11-01

    A method to improve the accuracy of the measurement of the diameter of particles using shadowgraph images is discussed. To obtain data for analysis, a transparent glass calibration reticle, marked with black circular dots of known diameters, is imaged with a high-resolution digital camera using backlighting separately from both a collimated laser beam and diffuse white light. The diameter and intensity of each dot is measured by fitting an inverse hyperbolic tangent function to the particle image intensity map. Using these calibration measurements, a relationship between the apparent diameter and intensity of the dot and its actual diameter and position relative to the focal plane of the lens is determined. It is found that the intensity decreases and apparent diameter increases/decreases (for collimated/diffuse light) with increasing distance from the focal plane. Using the relationships between the measured properties of each dot and its actual size and position, an experimental calibration method has been developed to increase the particle-diameter-dependent range of distances from the focal plane for which accurate particle diameter measurements can be made. The support of the National Science Foundation under grant OCE0751853 from the Division of Ocean Sciences is gratefully acknowledged.

  11. Scanning radiometer for measurement of forward-scattered light to determine mean diameter of spray particles

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1976-01-01

    A scanning radiometer is reported that measures forward-scattered light to determine the mean diameter of spray particles. An optical scanning method gives a continuous measurement of the light-scattering angle during spray nozzle tests. A method of calibration and a correction for background light are presented. Mean particle diameters of 10 to 500 micrometers can be measured.

  12. Effect of diameter of glass fibers on flexural properties of fiber-reinforced composites.

    PubMed

    Obukuro, Motofumi; Takahashi, Yutaka; Shimizu, Hiroshi

    2008-07-01

    This study investigated the effect of the diameter of glass fibers on the flexural properties of fiber-reinforced composites. Bar-shaped test specimens of highly filled fiber-reinforced composites (FRCs) and FRC of 30 vol% fiber content were made from a light-cured dimethacrylate monomer liquid (mixture of urethane dimethacrylate and triethylene glycol dimethacrylate) with silanized E-glass fibers (7, 10, 13, 16, 20, 25, 30, and 45 microm in diameter). Flexural strength and elastic modulus were measured. The flexural strength of the highly filled FRCs increased with increasing fiber diameter. In particular, the strengths of highly filled FRCs with 20-, 25-, 30-, and 45-microm-diameter fibers was significantly higher than the others (p<0.05). The flexural strength of FRC of 30 vol% fiber content increased with increasing fiber diameter, except for the FRC with 45-microm-diameter fibers; FRCs with 20-, 25-, and 30-microm-diameter fibers were significantly stronger than the others (p<0.05). Therefore, it was revealed that the diameter of glass fibers significantly affected the flexural properties of fiber-reinforced composites. PMID:18833767

  13. Biosensing using plasmonic nanohole arrays with small, homogenous and tunable aperture diameters.

    PubMed

    Xiong, Kunli; Emilsson, Gustav; Dahlin, Andreas B

    2016-06-21

    Plasmonic nanohole arrays are widely used for optical label-free molecular detection. An important factor for many applications is the diameter of the apertures. So far nanohole arrays with controllable diameters below 100 nm have not been demonstrated and it has not been systematically investigated how the diameter influences the optical properties. In this work we fine-tune the diameter in short range ordered nanohole arrays down to 50 nm. The experimental far field spectra show how the wavelength of maximum extinction remains unaffected while the transmission maximum blue shifts with smaller diameters. The near field is visualized by numerical simulations, showing a homogenous enhancement throughout the cylindrical void at the transmission maximum for diameters between 50 and 100 nm. For diameters below 50 nm plasmon excitation is no longer possible experimentally or by simulations. Further, we investigate the refractive index sensing capabilities of the smaller holes. As the diameter was reduced, the sensitivity in terms of resonance shift with bulk liquid refractive index was found to be unaltered. However, for the transmission maximum the sensitivity becomes more strongly localized to the hole interior. By directing molecular binding to the bottom of the holes we demonstrate how smaller holes enhance the sensitivity in terms of signal per molecule. A real-time detection limit well below one protein per nanohole is demonstrated. The smaller plasmonic nanoholes should be suitable for studies of molecules confined in small volumes and as mimics of biological nanopores. PMID:26867475

  14. Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights

    SciTech Connect

    Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

    2014-05-21

    Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

  15. The diameter of 88 Thisbe from its occultation of SAO 187124

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Franz, O. G.; White, N. M.; Bowell, E.; Klemola, A.; Elliott, R. C.; Smethells, W. G.; Price, P. M.; Mckay, C. P.

    1982-01-01

    The 7 October, 1981 occultation of SAO 187124 by 88 Thisbe was observed at twelve sites. The occultation observations, together with information about the asteroid's light curve, gives a mean diameter for Thisbe of 232 + or - 10 km. This value is 10 percent larger than the previously published radiometric diameter of Thisbe.

  16. Automatic measurement of early gestational sac diameters from one scan session

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Chen, Siping; Li, Shengli; Wang, Tianfu

    2011-03-01

    Gestational sac (GS) diameters are commonly measured by routine ultrasound in early pregnancy. However, manually searching for the standardized plane of GS (SPGS) and measuring the diameters are time-consuming. In this paper, we develop a three-stage automatic solution for this procedure. In order to precisely and efficiently locate the position of GS in each frame, a coarse to fine GS detection scheme based on AdaBoost algorithm is explored. Then, an efficient method based on local context information is introduced to reduce the false positives (FP) generated by the above detection process. Finally, a database (DB) guided spectral segmentation is proposed to separate GS region from the background for further diameters measurement. Experiments carried out on 31 videos show that by using the proposed methods, the number of SPGS searching error is only one, and the average measurement error is 0.059 for the length diameters and 0.083 for the depth diameters.

  17. The Effect of Swelling Ratio on the Coulter Underestimation of Hydrogel Microsphere Diameters

    PubMed Central

    Pellegrini, Michael; Cherukupalli, Abhimanyu; Medini, Michael; Falkowski, Ron

    2015-01-01

    It has been demonstrated that the diameters of porous particles are underestimated by Coulter measurements. This phenomenon has also been observed in hydrogel particles, but not characterized. Since the Coulter principle uses the displacement of electrolyte to determine particle size, electrolyte contained within the swelled hydrogel microparticles results in an underestimate of actual particle diameters. The increased use of hydrogel microspheres in biomedical applications has led to the increased application of the Coulter principle to evaluate the size distribution of microparticles. A relationship between the swelling ratio of the particles and their reported Coulter diameters will permit calculation of the actual diameters of these particles. Using polyethylene glycol diacrylate hydrogel microspheres, we determined a correction factor that relates the polymer swelling ratio and the reported Coulter diameters to their actual size. PMID:26414785

  18. Magnetic-field-induced diameter-selective synthesis of single-walled carbon nanotubes.

    PubMed

    Su, Yanjie; Zhang, Yaozhong; Wei, Hao; Zhang, Liling; Zhao, Jiang; Yang, Zhi; Zhang, Yafei

    2012-03-01

    We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process. PMID:22301844

  19. A simple correction for slug tests in small-diameter wells

    USGS Publications Warehouse

    Butler, J.J., Jr.

    2002-01-01

    A simple procedure is presented for correcting hydraulic conductivity (K) estimates obtained from slug tests performed in small-diameter installations screened in highly permeable aquifers. Previously reported discrepancies between results from slug tests in small-diameter installations and those from tests in nearby larger-diameter wells are primarily a product of frictional losses within the small-diameter pipe. These frictional losses are readily incorporated into existing models for slug tests in high-K aquifers, which then serve as the basis of a straightforward procedure for correcting previously obtained K estimates. A demonstration of the proposed procedure using data from a series of slug tests performed in a controlled field setting confirms the validity of the approach. The results of this demonstration also reveal the detailed view of spatial variations in K that can be obtained using slug tests in small-diameter installations.

  20. Ultrahigh-resolution and non-contact diameter measurement of metallic wire using eddy current sensor.

    PubMed

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2014-08-01

    This paper proposes a new method using eddy current sensor (ECS) for online non-contact diameter measurement of metallic wires with ultrahigh resolution. A prototype sensor was designed, fabricated, and tested for copper wires with diameters ranging from 1.12 mm to 1.30 mm. A solenoid coil with dimensions of 16 mm long and 2.1 mm in diameter is used as sensing element with a working frequency of 1.3 MHz. With a well-designed bridge, the sensing coil's inductance variation can be detected and the wire's diameter can be calculated. The ECS system demonstrated a dynamic resolution better than 2.2 μm and a static resolution better than 0.42 nm for a wire with a diameter of 1.3 mm. This non-contact method has competitive advantages over other methods in many aspects, especially in terms of measurement resolution. PMID:25173300

  1. Optical Analysis of Cassegrainian Point Focus Concentrators

    NASA Technical Reports Server (NTRS)

    Waterbury, S. S.; Schwinkendorf, W. E.

    1984-01-01

    A Cassegrainian solar concentrator, using a 7-meter diameter primary reflector, was analyzed in three forms: (1) an unmodified Cassegrainian, (2) the Ritchey-Chretien configuration, and (3) the unmodified Cassegrainian with a non-imaging tertiary reflector. Optical performance was not significantly improved with the Ritchey-Chretien; however, the tertiary resulted in significant improvement in intercept factor and optical efficiency. The effects of misalignment of the secondary and tertiary reflectors on the optical performance of the collector were also analyzed.

  2. Common bile duct diameter in an asymptomatic population: A magnetic resonance imaging study

    PubMed Central

    Peng, Rong; Zhang, Ling; Zhang, Xiao-Ming; Chen, Tian-Wu; Yang, Lin; Huang, Xiao-Hua; Zhang, Ze-Ming

    2015-01-01

    AIM: To measure the common bile duct (CBD) diameter by magnetic resonance cholangiopancreatography (MRCP) in a large asymptomatic population and analyze its some affecting factors. METHODS: This study included 862 asymptomatic subjects who underwent MRCP. The CBD diameter was measured at its widest visible portion on regular end-expiration MRCP for all subjects. Among these 862 subjects, 221 volunteers also underwent end-inspiration MRCP to study the effect of respiration on the CBD diameter. The age, sex, respiration, body length, body weight, body mass index (BMI), portal vein diameter (PVD), length of the extrahepatic duct and CBD, cystic junction radial orientation and location were recorded. The subjects were divided into 7 groups according to age. All of the above factors were compared with the CBD diameter on end-expiration MRCP. RESULTS: Among the 862 subjects, the CBD diameter was 4.13 ± 1.11 mm (range, 1.76-9.45 mm) and was correlated with age (r = 0.484; P < 0.05), with a dilation of 0.033 mm per year. The upper limit of the 95% reference range was 5.95 mm, resulting in a reasonable upper limit of 6 mm for the asymptomatic population. Respiration and other factors, including sex, body length, body weight, BMI, PVD, length of the extrahepatic duct and CBD, cystic junction radial orientation and location, were not related to the CBD diameter. CONCLUSION: We established a reference range for the CBD diameter on MRCP for an asymptomatic population. The CBD diameter is correlated with age. Respiration did not affect the non-dilated CBD diameter. PMID:26753065

  3. Effects of Initial Pore Diameter on the Oil Absorption Behavior of Potato Chips during Frying Process.

    PubMed

    Li, Jinwei; Zhang, Tingting; Liu, Yuanfa; Fan, Liuping

    2016-01-01

    How initial pore diameter in materials affects oil absorption has been rarely studied up to now. Herein, we provided direct data evidence suggesting that the pore diameter prior to frying closely related to the oil absorption behavior. The pore had no significant effect on oil absorption of potato chips (p>0.05) when its diameter was 0.1 and 0.2 mm compared with the control. However, the oil absorption increased with the increasing of pore diameter when it was 0.3-1.2 mm. The oil absorption tended to be saturated at 0.9 mm pore diameter. In addition, we analyzed the moisture content, total oil (TO), surface oil (SO), penetrated surface oil (PSO) and structural oil (STO) contents of potato chips. The results when using palm oil showed that there was no significant difference in moisture, TO and STO contents of samples with pore diameter of 0.1 and 0.2 mm during the whole frying processing respectively compared with the control (p>0.05). When pore diameter was 0.3-1.2 mm, STO and TO contents significantly increased with the rising of the diameter (p<0.05). The SO content and PSO content dropped as increasing in frying time for the samples with different pore diameters. The equilibrium TO content of samples with 0.3-0.9 mm pore significantly increased with the rising of pore diameter, which was about 6.2-22.5% higher than that of the control. And there was no significant difference in the equilibrium TO contents of both samples of 1.2 mm and 0.9 mm pore (p>0.05). STO fraction gave the greatest contribution to the increment of oil absorption. PMID:27041514

  4. Fast and simplified mapping of mean axon diameter using temporal diffusion spectroscopy.

    PubMed

    Xu, Junzhon; Li, Hua; Li, Ke; Harkins, Kevin D; Jiang, Xiaoyu; Xie, Jingping; Kang, Hakmook; Dortch, Richard D; Anderson, Adam W; Does, Mark D

    2016-04-01

    Mapping axon diameter is of interest for the potential diagnosis and monitoring of various neuronal pathologies. Advanced diffusion-weighted MRI methods have been developed to measure mean axon diameters non-invasively, but suffer major drawbacks that prevent their direct translation into clinical practice, such as complex non-linear data fitting and, more importantly, long scanning times that are usually not tolerable for most human subjects. In the current study, temporal diffusion spectroscopy using oscillating diffusion gradients was used to measure mean axon diameters with high sensitivity to small axons in the central nervous system. Axon diameters have been found to be correlated with a novel metric, DDR⊥ (the rate of dispersion of the perpendicular diffusion coefficient with gradient frequency), which is a model-free quantity that does not require complex data analyses and can be obtained from two diffusion coefficient measurements in clinically relevant times with conventional MRI machines. A comprehensive investigation including computer simulations and animal experiments ex vivo showed that measurements of DDR⊥ agree closely with histological data. In humans in vivo, DDR⊥ was also found to correlate well with reported mean axon diameters in human corpus callosum, and the total scan time was only about 8 min. In conclusion, DDR⊥ may have potential to serve as a fast, simple and model-free approach to map the mean axon diameter of white matter in clinics for assessing axon diameter changes. PMID:27077155

  5. In vivo capillary diameters in the stria vascularis and spiral ligament of the guinea pig cochlea.

    PubMed

    Miles, F P; Nuttall, A L

    1988-05-01

    Blood microvessels in the membraneous lateral wall of the cochlea were examined using intravital microscopic techniques. A video analysis system made serial diameter measurements at 1 micron intervals along the length of selected vessel segments during four experimental conditions. For each vessel segment, the serial measurements were statistically converted into a single diameter estimate, such that the flow resistance in a uniform vessel of this diameter would equal the resistance of the real non-uniform vessel. Nominal vessel diameters found (spiral ligament: 9-12 micron; stria vascularis: 12-16 micron) were nearly double those reported earlier in histological observations (Axelsson, 1968). During stimulation the largest diameter change seen was a 3.7% dilation (about 0.5 micron) in response to breathing 5% CO2 in oxygen. Theoretically, this change could reduce vascular fluid resistance by 16%, nearly enough to explain the observed flow increase of 20%. No diameter changes occurred for 5% CO2 in air despite a 50% flow increase, nor for air pressure pulses applied at the tympanic membrane. Round window electrical stimulation of 50 microA also produced dilation (less than 2.5%), but higher current levels were ineffective. In general, blood flow increases seen in this study could not adequately be attributed to the small lateral wall vessel diameter increases nor systemic causes, suggesting that lateral wall blood flow in these instances is dependent on control within the modiolus. PMID:3135284

  6. MreB Orientation Correlates with Cell Diameter in Escherichia coli.

    PubMed

    Ouzounov, Nikolay; Nguyen, Jeffrey P; Bratton, Benjamin P; Jacobowitz, David; Gitai, Zemer; Shaevitz, Joshua W

    2016-09-01

    Bacteria have remarkably robust cell shape control mechanisms. For example, cell diameter only varies by a few percent across a given population. The bacterial actin homolog, MreB, is necessary for establishment and maintenance of rod shape although the detailed properties of MreB that are important for shape control remained unknown. In this study, we perturb MreB in two ways: by treating cells with the polymerization-inhibiting drug A22 and by creating point mutants in mreB. These perturbations modify the steady-state diameter of cells over a wide range, from 790 ± 30 nm to 1700 ± 20 nm. To determine which properties of MreB are important for diameter control, we correlated structural characteristics of fluorescently tagged MreB polymers with cell diameter by simultaneously analyzing three-dimensional images of MreB and cell shape. Our results indicate that the helical pitch angle of MreB inversely correlates with the cell diameter of Escherichia coli. Other correlations between MreB and cell diameter are not found to be significant. These results demonstrate that the physical properties of MreB filaments are important for shape control and support a model in which MreB organizes the cell wall growth machinery to produce a chiral cell wall structure and dictate cell diameter. PMID:27602731

  7. Measuring system for cable length and diameter based on photoelectric technology

    NASA Astrophysics Data System (ADS)

    Zhu, WeiMin; Zhou, Zhou; Wei, Ping; Qi, Fang

    2012-10-01

    Precise online measurement of cable diameter and length will ensure stability of quality production and production speed. This paper describes a measuring device to measure cable length and diameter simultaneously, accomplish online production process control. The device consists mainly of a synchronous sampling part, calculation and control part. The synchronous sampling part consists of two parallel rollers one meter far from each other. A measuring band cinctures the rollers and move together with them. There are two electromagnetic chucks on the measuring band which are controlled by two photoelectric position switches to hold or release a cable, in order to make the cable move with measuring system synchronously. An optical encoder is connected to one of the rollers coaxially to measure cable length. For cable diameter measurement, two orthogonal CCD sensors are used. Accuracy of online diameter measurement is mainly affected by vibration of cable movement. In order to reduce the cable diameter measurement error caused by vibration, measuring system uses a mechanical damping device and high-speed CCD sensors which exposure time is up to microseconds. The calculation and control part of measuring device can filter, amplify and binarizate electrical signals from synchronous sampling part, then they are processed by microcontroller 8051 to complete cable length and diameter measurement. As well, the measuring device can set error limits and detect online whether cable length and diameter size are in default range , if not it would give corresponding alarm.

  8. [Effect of sharpening filter on vessel diameter measured by quantitative coronary arteriography].

    PubMed

    Arai, Hiroaki; Hosonuma, Naoya; Gou, Misako; Ueno, Takashi

    2002-05-01

    At cardiac catheterization, analog images obtained using cinefilm are translated into digital images, and images appearing on the CRT are filtered by a sharpen filter. We investigated the effect of the sharpening filter on vessel diameter as measured by quantitative coronary arteriography. We acquired images of a vessel phantom filled with contrast material using an X-ray image intensifier. Vessel diameters measured by quantitative coronary arteriography were 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, and 6 mm. Results showed that vessel diameters were decreased when the sharpening filter was used and that more intense filtering decreased the measured diameter further. When the diameter of the vessel phantom was less than 4 mm, the diameter was smaller and the ratio of decrease was larger. Vessel diameters of 2 mm, 3 mm, 4 mm, and 6 mm measured a maximum of 2.9 smaller, while those of 1 mm and 1.5 mm measured a maximum of 9.2 smaller. PMID:12520240

  9. Which Diameter and Angle Rule Provides Optimal Flow Patterns in a Coronary Bifurcation?

    PubMed Central

    Huo, Yunlong; Finet, Gérard; Lefevre, Thierry; Louvard, Yves; Moussa, Issam; Kassab, Ghassan S.

    2012-01-01

    The branching angle and diameter ratio in epicardial coronary artery bifurcations are two important determinants of atherogenesis. Murray’s cubed diameter law and bifurcation angle have been assumed to yield optimal flows through a bifurcation. In contrast, we have recently shown a 73 diameter law (HK diameter model), based on minimum energy hypothesis in an entire tree structure. Here, we derive a bifurcation angle rule corresponding to the HK diameter model and critically evaluate the streamline flow through HK and Murray-type bifurcations. The bifurcations from coronary casts were found to obey the HK diameter model and angle rule much more than Murray’s model. A finite element model was used to investigate flow patterns for coronary artery bifurcations of various types. The inlet velocity and pressure boundary conditions were measured by ComboWire. Y-bifurcation of Murray type decreased wall shear stress-WSS (10%–40%) and created an increased oscillatory shear index-OSI in atherosclerosis-prone regions as compared with HK-type bifurcations. The HK-type bifurcations were found to have more optimal flow patterns (i.e., higher WSS and lower OSI) than Murray-type bifurcations which have been traditionally believed to be optimized. This study has implications for changes in bifurcation angles and diameters in percutaneous coronary intervention. PMID:22365499

  10. Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bylayers

    SciTech Connect

    Troiano, Julianne; Olenick, Laura L.; Kuech, Thomas R.; Melby, Eric S.; Hu, Dehong; Lohse, Samuel E.; Mensch, Arielle C.; Dogangun, Merve; Vartanian, Arlane M.; Torelli, Marco; Ehimiaghe, Eseohi; Walter, Stephanie R.; Fu, Li; Anderton, Christopher R.; Zhu, Zihua; Wang, Hongfei; Orr, Galya; Murphy, Catherine; Hamers, Robert J.; Pedersen, Joel A.; Geiger, Franz M.

    2015-01-08

    Interfacial charge densities and potentials are determined for silica-supported phospholipid bilayers formed from lipids having zwitterionic, negatively charged, and positively charged headgroups. Quartz crystal microbalance with dissipation (QCM-D), fluorescence recovery after photobleaching (FRAP), and atomic force microscopy demonstrate the presence of well-formed supported lipid bilayers, which, as probed by vibrational sum frequency generation (SFG), undergo negligible structural changes along their alkyl chains when NaCl concentration is raised from 0.001 to 0.1 M. From second harmonic generation (SHG) measurements we estimate that each zwitterionic headgroup of the bilayer formed from pure DOPC is associated with an apparent charge of -0.028(+0.008/-0.007)×10-¹⁹C, corresponding to 1.8 ± 0.5 % of an elementary negative charge. Moreover, we show that a supported lipid bilayer carrying an apparent negative interfacial potential may interact with not just positively charged 4-nm diameter gold nanoparticles but also negatively charged gold nanoparticles. In this latter case, charge-charge repulsion does not appear to inhibit particle-bilayer interactions and is likely overcome by multivalent interactions that are estimated to involve 3-5 hydrogen-bond equivalents. FRAP, QCM-D, and SFG measurements indicate that the bilayers remain intact under the conditions of the experiments. SHG charge screening experiments are consistent with an apparent zero net charge density associated with the positively charged gold nanoparticles when they are attached to a supported lipid bilayer carrying an apparent negative potential. The results presented here serve to benchmark experimental and computational studies of the nano-bio interface.

  11. Influences of Microbubble Diameter and Ultrasonic Parameters on In Vitro Sonothrombolysis Efficacy

    PubMed Central

    Borrelli, Michael J.; O’Brien, William D.; Hamilton, Eric; Oelze, Michael L.; Wu, Jonah; Bernock, Laura J.; Tung, Stephen; Rokadia, Husein; Culp, William C.

    2012-01-01

    PURPOSE Quantify the effects of microbubble (MB) size, elasticity and pulsed ultrasonic parameters on in vitro sonothrombolysis (STBL: ultrasound-mediated thrombolysis) efficacy. MATERIALS AND METHODS Monodispersive MBs with diameters of 1 μm or 3 μm were exposed to pulsed ultrasound (1 MHz or 3 MHz) to lyse rabbit blood clots. STBL efficacy (clot mass loss) was measured as functions of MB size and concentration, ultrasonic frequency and intensity, pulse duration (PD), pulse repeat frequency (PRF) and duty factor. RESULTS STBL at 1 MHz was more effective using 3 μm MBs and at 3 MHz using 1 μm MBs. STBL was generally more effective when 75% or more of MBs remained intact, especially for 3 μm MBs; and improving STBL by increasing PRF from 100 Hz to 400 Hz at 3 MHz was associated with increasing 3 μm MB survival. However, 60% of 1 μm MBs were destroyed during maximal STBL at 3 MHz, indicating that considerable MB collapse may be requisite for STBL under these conditions. CONCLUSION The ability to control MB size and elasticity permits utilizing a wide range of ultrasound parameters (frequency, intensity, etc.) to produce desired levels of STBL. Comparable, maximal STBL efficacy was achieved at twenty-fold lower intensity with 3 μm MBs (0.1 W/cm2) than with 1 μm MBs (2.0 W/cm2); a potential safety issue for in vivo STBL. Ultrasound parameters that maximized MB survival yielded maximal STBL efficacy; except with 1 μm MBs at 3 MHz where most MBs were destroyed. PMID:23106936

  12. Meteorological influences on stemflow generation across diameter size classes of two morphologically distinct deciduous species

    NASA Astrophysics Data System (ADS)

    Van Stan, John T.; Van Stan, Jarrad H.; Levia, Delphis F.

    2014-12-01

    Many tree species have been shown to funnel substantial rainfall to their stem base as stemflow flux, given a favorable stand structure and storm conditions. As stemflow is a spatially concentrated flux, prior studies have shown its impact on ecohydrological and biogeochemical processes can be significant. Less work has been performed examining stemflow variability from meteorological conditions compared to canopy structural traits. As such, this study performs multiple regressions: (1) to examine stemflow variability due to event-based rainfall amount, intensity, mean wind speeds, and vapor pressure deficit; (2) across three diameter size classes (10-20, 21-40, and >41 cm DBH); and (3) for two common tree species in the northeastern USA of contrasting canopy morphology— Liriodendron tulipifera L. (yellow poplar) versus Fagus grandifolia Ehrh. (American beech). On the whole, multiple regression results yielded significant positive correlations with stemflow for rainfall amount, intensity, and mean wind speed and a significant negative correlation for vapor pressure deficit (VPD). Tree size altered stemflow-meteorological condition relationships, where larger trees strengthened indirect stemflow-VPD and direct stemflow-rainfall and stemflow-intensity associations. Canopies of rougher bark and lower branch angle (represented by L. tulipifera) enhanced correlations for nearly all meteorological conditions via greater stemflow residence time (and longer exposure to meteorological conditions). Multiple regressions performed on leafless canopy stemflow resulted in an inverse relationship with wind speeds, likely decoupling stemflow sheltered solely on bark surfaces from VPD influences. Leaf presence generally increased direct stemflow associations with rainfall intensity, yet diminished stemflow-rainfall relationships. F. grandifolia canopies (exemplifying structures of smoother bark and greater branch angle) strengthened differences in stemflow associations with

  13. Meteorological influences on stemflow generation across diameter size classes of two morphologically distinct deciduous species.

    PubMed

    Van Stan, John T; Van Stan, Jarrad H; Levia, Delphis F

    2014-12-01

    Many tree species have been shown to funnel substantial rainfall to their stem base as stemflow flux, given a favorable stand structure and storm conditions. As stemflow is a spatially concentrated flux, prior studies have shown its impact on ecohydrological and biogeochemical processes can be significant. Less work has been performed examining stemflow variability from meteorological conditions compared to canopy structural traits. As such, this study performs multiple regressions: (1) to examine stemflow variability due to event-based rainfall amount, intensity, mean wind speeds, and vapor pressure deficit; (2) across three diameter size classes (10-20, 21-40, and >41 cm DBH); and (3) for two common tree species in the northeastern USA of contrasting canopy morphology--Liriodendron tulipifera L. (yellow poplar) versus Fagus grandifolia Ehrh. (American beech). On the whole, multiple regression results yielded significant positive correlations with stemflow for rainfall amount, intensity, and mean wind speed and a significant negative correlation for vapor pressure deficit (VPD). Tree size altered stemflow-meteorological condition relationships, where larger trees strengthened indirect stemflow-VPD and direct stemflow-rainfall and stemflow-intensity associations. Canopies of rougher bark and lower branch angle (represented by L. tulipifera) enhanced correlations for nearly all meteorological conditions via greater stemflow residence time (and longer exposure to meteorological conditions). Multiple regressions performed on leafless canopy stemflow resulted in an inverse relationship with wind speeds, likely decoupling stemflow sheltered solely on bark surfaces from VPD influences. Leaf presence generally increased direct stemflow associations with rainfall intensity, yet diminished stemflow-rainfall relationships. F. grandifolia canopies (exemplifying structures of smoother bark and greater branch angle) strengthened differences in stemflow associations with

  14. Diameter distribution of thermally evaporated indium metal islands on silicon substrates

    NASA Astrophysics Data System (ADS)

    Balch, Joleyn; Tsakalakos, Loucas; Huber, William; Grande, James; Knussman, Michael; Cale, Timothy S.

    2007-09-01

    Although many groups have studied the initial growth stages of various metals, including indium, there is little information in literature on diameter distributions of indium in relation to film thickness or annealing conditions. This paper reports island size distributions of thermally evaporated In islands on Si (100) and Si (111) substrates for nominal film thicknesses ranging from 5 to 50 nm. Because indium has a low melting temperature, and therefore a high homologous temperature at room temperature, 3-dimensional islands form during deposition with no subsequent heat treatments needed. Island diameters were calculated using commercial image analysis software in conjunction with SEM images of the samples. It is found that there is a bimodal island diameter distribution for nominal indium thicknesses greater than 5 nm. While the diameters of the larger islands increase exponentially with nominal thickness, those of the smaller islands increase linearly, and therefore more slowly, with nominal thickness. For nominal thickness of 50 nm, the average diameters of the small and large islands differ by almost an order of magnitude. Anneal conditions were studied in an attempt to narrow diameter distributions. Samples of each nominal thickness were annealed at temperatures ranging from 360°C to 550°C and the diameters again measured. The range of island diameters become narrower with 360°C anneal and volume average island diameter increases by ~30-50%. This narrowing of the distribution occurs due to smaller islands being absorbed by the larger in a process akin to Ostwald ripening, which is facilitated by higher surface diffusivities at higher homologous temperatures.

  15. Influence of the implant-abutment connection design and diameter on the screw joint stability

    PubMed Central

    Shin, Hyon-Mo; Huh, Jung-Bo; Yun, Mi-Jeong; Jeon, Young-Chan; Chang, Brian Myung

    2014-01-01

    PURPOSE This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (α=0.05). RESULTS The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate. PMID:24843398

  16. Implosion dynamics and x-ray generation in small-diameter wire-array Z pinches

    SciTech Connect

    Ivanov, V. V.; Sotnikov, V. I.; Kindel, J. M.; Hakel, P.; Mancini, R. C.; Astanovitskiy, A. L.; Haboub, A.; Altemara, S. D.; Shevelko, A. P.; Kazakov, E. D.; Sasorov, P. V.

    2009-05-15

    It is known from experiments that the radiated x-ray energy appears to exceed the calculated implosion kinetic energy and Spitzer resistive heating [C. Deeney et al., Phys. Rev. A 44, 6762 (1991)] but possible mechanisms of the enhanced x-ray production are still being discussed. Enhanced plasma heating in small-diameter wire arrays with decreased calculated kinetic energy was investigated, and a review of experiments with cylindrical arrays of 1-16 mm in diameter on the 1 MA Zebra generator is presented in this paper. The implosion and x-ray generation in cylindrical wire arrays with different diameters were compared to find a transition from a regime where thermalization of the kinetic energy is the prevailing heating mechanism to regimes with other dominant mechanisms of plasma heating. Loads of 3-8 mm in diameter generate the highest x-ray power at the Zebra generator. The x-ray power falls in 1-2 mm loads which can be linked to the lower efficiency of plasma heating with the lack of kinetic energy. The electron temperature and density of the pinches also depend on the array diameter. In small-diameter arrays, 1-3 mm in diameter, ablating plasma accumulates in the inner volume much faster than in loads of 12-16 mm in diameter. Correlated bubblelike implosions were observed with multiframe shadowgraphy. Investigation of energy balance provides evidence for mechanisms of nonkinetic plasma heating in Z pinches. Formation and evolution of bright spots in Z pinches were studied with a time-gated pinhole camera. A comparison of x-ray images with shadowgrams shows that implosion bubbles can initiate bright spots in the pinch. Features of the implosions in small-diameter wire arrays are discussed to identify mechanisms of energy dissipation.

  17. 76 FR 47555 - Certain Large Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Japan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    ... Pipe From Japan; Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From... certain small diameter carbon and alloy seamless standard, line and pressure pipe (``small diameter pipe... sunset reviews of the antidumping duty orders on large diameter pipe from Japan and small......

  18. 76 FR 62762 - Certain Large Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Japan...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-11

    ... Pipe From Japan; Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From... alloy seamless standard, line and pressure pipe (``large diameter pipe'') from Japan and certain small diameter carbon and alloy seamless standard, line and pressure pipe (``small diameter pipe'')......

  19. The Influence of the Diameter Ratio on the Characteristics Diagram of the Axial Compressor

    NASA Technical Reports Server (NTRS)

    Eckert, B.; Pflueger, F.; Weinig, F.

    1948-01-01

    With the further development of axial blowers into highly loaded flow machines, the influence of the diameter ratio upon air output and efficiency gains in significance. Clarification of this matter is important for single-stage axial compressors, and is of still greater importance for multistage ones, and particularly for aircraft power plants. Tests with a single-stage axial blower gave a decrease in the attainable maximum pressure coefficient and optimum efficiency as the diameter ratio increased. The decrease must be ascribed chiefly to the guide surface of the hub and housing between the blades increasing with the diameter ratio.

  20. Alpha particles energy estimation from track diameter development in a CR-39 detector.

    PubMed

    Azooz, Aassim A; Al-Jubbori, Mushtaq A

    2016-09-01

    The slight nonlinearity in temporal development of tracks diameter in CR-39 nuclear track detectors is examined with the aim of attempting to find if such nonlinearity can be directly related to the charged particle energy. Narrowly spaced etching time-diameter experimental data for alpha particles at five energy values and for one additional energy value etched at five different temperatures are obtained. Initial results show good indication that measuring such time-diameter relationship can form a useful energy estimation tool. Good consistency with other independent published results is obtained. PMID:27341133

  1. Diameter-controlled growth of carbon nanotubes using thermal chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Cheol Jin; Lyu, Seung Chul; Cho, Young Rae; Lee, Jin Ho; Cho, Kyoung Ik

    2001-06-01

    The diameter and the growth rate of vertically aligned carbon nanotubes (CNTs) are controlled by modulating the size of catalytic particles using thermal chemical vapor deposition (CVD). The size of iron catalytic particles deposited on silicon oxide substrate is varied in a controlled manner by adjusting the condition of ammonia pretreatment. We found an inverse relation between the diameter and growth rate of carbon nanotubes. As the diameter increases, the compartment layers of bamboo-shaped carbon nanotubes appear more frequently, which is suitably explained by the base growth mechanism.

  2. Effect of orifice length-diameter ratio on fuel sprays for compression-ignition engines

    NASA Technical Reports Server (NTRS)

    Gelalles, A G

    1933-01-01

    Experimental results on the effect of the length-diameter ratio of the orifice on the spray characteristics, together with a brief analysis of the factors affecting these characteristics, are presented in this report. The length-diameter ratios tested ranged from 0.5 to 10; the orifice diameters from 0.008 to 0.040 inch; and the injection pressures from 2,000 to 8,000 pounds per square inch. The density of the air into which the fuel was discharged was varied from 0.38 to 1.35 pounds per cubic foot.

  3. Synthesis and Optical Properties of PbSe Nanorods with Controlled Diameter and Length.

    PubMed

    Placencia, Diogenes; Boercker, Janice E; Foos, Edward E; Tischler, Joseph G

    2015-09-01

    The synthesis of PbSe nanorods with low branching (<1%), high aspect ratios (up to ∼16), and controlled lengths and diameters was demonstrated via the removal of water and oleic acid from the synthesis precursors. It was determined that the proper combination of reaction time and temperature allows for the control of PbSe nanorod length and diameter and therefore control over their electronic states, as probed through absorbance and photoluminescence measurements. Similar to PbSe nanowires, nanorods display higher Stokes shifts than for spherical nanocrystals due to intrananorod diameter fluctuations. PMID:26267558

  4. Study of temperature dependences of mechanical properties of large-diameter pipes

    NASA Astrophysics Data System (ADS)

    Ostsemin, A. A.; Saidov, G. I.

    1994-04-01

    The paper presents the results of an experimental determination of mechanical properties of large-diameter pipes of steels 09G2S, 14G2SAF, 17G1S and their welded joints at a strain rate of 200/s over a temperature range of 113-293 K. Microspecimens with the length of the working section being five times its diameter (1.2 mm) were used. Parameters of the yield stress temperature-and-rate dependence of V.D. Yaroshevich, as well as the lower critical transition temperature and fracture resistance were determined in relation to the ferrite diameter.

  5. Ecological importance of large-diameter trees in a temperate mixed-conifer forest.

    PubMed

    Lutz, James A; Larson, Andrew J; Swanson, Mark E; Freund, James A

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m(2). We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by

  6. Synthesis of diameter controlled carbon nanotubes using self-assembled catalyst nanoparticles

    NASA Astrophysics Data System (ADS)

    Baliyan, Ankur; Fukuda, Takahiro; Uchida, Takashi; Nakajima, Yoshikata; Hanajiri, Tatsuro; Maekawa, Toru

    2012-01-01

    Vertically-aligned diameter-controlled carbon nanotubes (CNTs) are synthesised by the plasma enhanced chemical vapour deposition (PECVD) method using multi-layers of self-assembled catalytic ligand-coated iron oxide nanoparticles. We find that the mono-dispersed nanoparticles play a vital role for the production of diameter-controlled CNTs. A new growth model is also proposed based on the experimental results. The present results may make a great contribution to the development and design of mechanical, electronic and biomedical devices, in which diameter-controlled CNTs are utilised.

  7. Diameter-dependent electronic transport properties of Au-catalyst/Ge-nanowire Schottky diodes

    SciTech Connect

    Picraux, S Thomas; Leonard, Francois; Swartzentruber, Brian S; Talin, A Alee

    2008-01-01

    We present electronic transport measurements in individual Au-catalyst/Ge-nanowire interfaces demonstrating the presence of a Schottky barrier. Surprisingly, the small-bias conductance density increases with decreasing diameter. Theoretical calculations suggest that this effect arises because electron-hole recombination in the depletion region is the dominant charge transport mechanism, with a diameter dependence of both the depletion width and the electron-hole recombination time. The recombination time is dominated by surface contributions and depends linearly on the nanowire diameter.

  8. The effect of initial diameter in sperically symmetric droplet combustion of sooting fuels

    NASA Technical Reports Server (NTRS)

    Jackson, G. S.; Avedisian, C. T.

    1994-01-01

    The effect of initial droplet diameter on the burning rate of sooting fuels - n-heptane and 1-chloro-octane - was examined experimentally at low gravity. A 1.2s drop tower provided a low gravity environment to minimize buoyancy and achieve spherically symmetric flames for stationary droplets. Free-floating and fiber-supported droplets were burned, and both techniques gave matching results for droplets of similar initial diameter. Burning rate constants for both fuels were measured for a large number of droplets ranging from 0.4 to 1.1mm in initial diameter.

  9. Ecological Importance of Large-Diameter Trees in a Temperate Mixed-Conifer Forest

    PubMed Central

    Lutz, James A.; Larson, Andrew J.; Swanson, Mark E.; Freund, James A.

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m2. We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by a

  10. Suppression of ATP-induced excitability in rat small-diameter trigeminal ganglion neurons by activation of GABAB receptor.

    PubMed

    Takeda, Mamoru; Ikeda, Mizuho; Takahashi, Masayuki; Kanazawa, Takuya; Nasu, Masanori; Matsumoto, Shigeji

    2013-09-01

    The aim of the present study was to investigate whether a GABAB receptor agonist could modulate ATP-activated neuronal excitability of nociceptive TRG neurons using perforated whole-cell patch-clamp and immunohistochemical techniques. Immunohistochemical analysis revealed that 86% of P2X3 receptor-immunoreactive, small-diameter TRG neurons co-expressed GABAB receptor. Under voltage-clamp conditions (Vh=-60mV), application of ATP activated the inward current in acutely isolated rat TRG neurons in a dose-dependent manner (10-50 μM) and this current could be blocked by pyridoxal-phosphate-6-azophenyl-27,47-disulfonic acid (PPADS) (10 μM), a selective P2 purinoreceptor antagonist. The peak amplitude of ATP-activated currents was significantly inhibited after application of GABAB receptor agonist, baclofen (10-50 μM), in a concentration-dependent and reversible manner. The baclofen-induced inhibition of ATP-activated current was abolished by co-application of 3-amino-2 (4-chlorophenyl)-2hydroxypropysufonic acid) saclofen, a GABAB receptor antagonist (50 μM). Under current-clamp conditions, application of 20 μM ATP significantly depolarized the membrane potential resulting in increased mean action potential frequencies, and these ATP-induced effects were significantly inhibited by baclofen and these effects were antagonized by co-application of saclofen. Together, the results suggested that GABAB receptor activation could inhibit the ATP-induced excitability of small-diameter TRG neurons activated through the P2X3 receptor. Thus, the interaction between P2X3 and GABAB receptors of small-diameter TRG neuronal cell bodies is a potential therapeutic target for the treatment of trigeminal nociception. PMID:24004472

  11. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    SciTech Connect

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Jiang, H.; Kauppinen, E. I.; Susi, T.; Nasibulin, A. G.

    2015-07-06

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3–4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ∼10{sup 5 }cm{sup −3} prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  12. Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

    NASA Astrophysics Data System (ADS)

    Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Susi, T.; Jiang, H.; Nasibulin, A. G.; Kauppinen, E. I.

    2015-07-01

    We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3-4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ˜105 cm-3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

  13. Measurement and modeling of diameter distributions of particulate matter in terrestrial solutions

    NASA Astrophysics Data System (ADS)

    Levia, Delphis F.; Michalzik, Beate; Bischoff, Sebastian; NäThe, Kerstin; Legates, David R.; Gruselle, Marie-Cecile; Richter, Susanne

    2013-04-01

    Particulate matter (PM) plays an important role in biogeosciences, affecting biosphere-atmosphere interactions and ecosystem health. This is the first known study to quantify and model PM diameter distributions of bulk precipitation, throughfall, stemflow, and organic layer (Oa) solution. Solutions were collected from a European beech (Fagus sylvatica L.) forest during leafed and leafless periods. Following scanning electron microscopy and image analysis, PM distributions were quantified and then modeled with the Box-Cox transformation. Based on an analysis of 43,278 individual particulates, median PM diameter of all solutions was around 3.0 µm. All PM diameter frequency distributions were skewed significantly to the right. Optimal power transformations of PM diameter distributions were between -1.00 and -1.56. The utility of this model reconstruction would be that large samples having a similar probability density function can be developed for similar forests. Further work on the shape and chemical composition of particulates is warranted.

  14. Resonant Frequency Dependence on Outer Diameter of High Tc rf-SQUID

    NASA Astrophysics Data System (ADS)

    Ashizuka, Takuya; Sakai, Akira; Miyato, Yuji; Itozaki, Hideo

    Superconducting quantum interference devices (SQUIDs) have been applied to various magnetic sensing. An rf-SQUID can measure magnetic signals by applying external rf-magnetic field whose frequency is tuned to its resonance. Our rf-SQUID having the outer diameter of 3.5 mm needed a substrate resonator to operate it within the operation frequency range of our using FLL electronics. The designs of the rf-SQUID and the resonator were critical to the resonant frequency and the effective area. In this paper, the outer diameter dependence of the resonant frequency and the effective area were investigated by both the electromagnetic simulations and the experiments. The results showed that the rf-SQUID having the larger outer diameter has the smaller resonant frequency and the larger effective area. The rf-SQUIDs having the larger outer diameter were fabricated according to the simulation results. They could be operated within the operation frequency range even though a resonator was omitted.

  15. Effect of Shock Precompression on the Critical Diameter of Liquid Explosives

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.; Yoshinaka, Akio C.; Zhang, Fan

    2006-07-01

    The critical diameter of both ambient and shock-precompressed liquid nitromethane confined in PVC tubing are measured experimentally. The experiment was conducted for both amine sensitized and neat NM. In the precompression experiments, the explosive is compressed by a strong shock wave generated by a donor explosive and reflected from a high impedance anvil prior to being detonated by a secondary event. The pressures reached in the test sections prior to detonation propagation was approximately 7 and 8 GPa for amine sensitized and neat NM respectively. The results demonstrated a 30% - 65% decrease in the critical diameter for the shock-compressed explosives. This critical diameter decrease is observed despite a significant decrease in the predicted Von Neumann temperature of the detonation in the precompressed explosive. The results are discussed in the context of theoretical predictions based on thermal ignition theory and previous critical diameter measurements.

  16. Effect of Shock Precompression on the Critical Diameter of Liquid Explosives

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Yoshinaka, Akio

    2005-07-01

    The critical diameter of both ambient and shock precompressed liquid explosives confined in PVC tubing are measured experimentally. In the precompression experiments, the explosive is compressed by a strong shock wave generated by a donor explosive and reflected from a high impedance anvil prior to being detonated by a secondary event. The final pressure in the test section reaches approximately 6.8 GPa before the detonation enters the test section. The results demonstrate a 20% decrease in the critical diameter for the shock compressed explosive. This critical diameter decrease is observed despite a significant decrease in the predicted Von Neumann temperature of the detonation in the precompressed explosive. The results are discussed in the context of theoretical predictions based on thermal ignition theory and previous critical diameter measurements.

  17. Critical diameters of detonation of explosives used in spacecraft separation systems

    NASA Astrophysics Data System (ADS)

    Kotomin, A. A.; Dushenok, S. A.; Efanov, V. V.; Trapeznikov, M. A.; Kozlov, A. S.; Gorovtsov, V. V.

    2011-12-01

    The article presents findings of systematic investigations of the detonation ability of advanced individual explosives, their mixtures, and materials used in spacecraft separation systems. A method for calculation and prediction of their critical detonation diameters is developed.

  18. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as... the croze ring of the completed barrel. (b) The tolerance established in this part for the...

  19. Log-normal diameter distribution of Pd-based metallic glass droplet and wire

    PubMed Central

    Yaginuma, S.; Nakajima, C.; Kaneko, N.; Yokoyama, Y.; Nakayama, K. S.

    2015-01-01

    We have studied the formation of Pd42.5Cu30Ni7.5P20 metallic glass droplets and wires in the gas atomization process. We demonstrate that the sizes of droplets and wires can be distinguished by the Ohnesorge number (Oh), which is the proportion of the spinnability to the capillary instability, and the diameter distributions follow a log-normal distribution function, implying cascade fragmentation. For droplets, the number significantly increases at Oh < 1 but the diameter gradually decreases. For wires, the number greatly increases at Oh > 1 while the diameter steadies below 400 nm. Further, the wire diameter is quadrupled at Oh = 16 due to the high viscosity which suppresses both capillary breakup and ligament elongation. PMID:26030090

  20. Variation of the Diameter of the Sun as Measured by the Solar Disk Sextant (SDS)

    NASA Astrophysics Data System (ADS)

    Girard, Terrence; Sofia, S.; Sofia, U. J.; Twigg, L. W.; Heaps, W.; Thuillier, G.

    2014-01-01

    The balloon-borne Solar Disk Sextant (SDS) experiment has measured the angular size of the Sun on seven occasions spanning the years 1992 to 2011. The solar half-diameter -- observed in a 100-nm wide passband centered at 615 nm -- is found to vary over that period by up to 200 mas, while the typical estimated uncertainty of each measure is 20 mas. The diameter variation is not in phase with the solar activity cycle; thus, the measured diameter variation cannot be explained as an observational artifact of surface activity. Other possible instrument-related explanations for the observed variation are considered and found unlikely, leading us to conclude that the variation is real. The SDS and its results are presented here, including the analysis procedure necessary to calibrate the instrument and allow comparison of diameter measures across decades.

  1. Variation of the diameter of the Sun as measured by the Solar Disk Sextant (SDS)

    NASA Astrophysics Data System (ADS)

    Sofia, S.; Girard, T. M.; Sofia, U. J.; Twigg, L.; Heaps, W.; Thuillier, G.

    2013-12-01

    The balloon-borne Solar Disk Sextant (SDS) experiment has measured the angular size of the Sun on seven occasions spanning the years 1992 to 2011. The solar half-diameter - observed in a 100 nm wide passband centred at 615 nm - is found to vary over that period by up to 200 mas, while the typical estimated uncertainty of each measure is 20 mas. The diameter variation is not in phase with the solar activity cycle; thus, the measured diameter variation cannot be explained as an observational artefact of surface activity. Other possible instrument-related explanations for the observed variation are considered but found unlikely, leading us to conclude that the variation is real. The SDS is described here in detail, as is the complete analysis procedure necessary to calibrate the instrument and allow comparison of diameter measures across decades.

  2. Speedy fabrication of diameter-controlled Ag nanowires using glycerolunder microwave irradiation conditions

    EPA Science Inventory

    Diameter-controlled Ag nanowires were rapidly fabricated (1 min) using inexpensive, abundant, and environmentally-friendly glycerol as both reductant and solvent under non-stirred microwave irradiation conditions; no Ag particles were formed using conventional heating methods. Th...

  3. The Attributes of a Variable-Diameter Rotor System Applied to Civil Tiltrotor Aircraft

    NASA Technical Reports Server (NTRS)

    Brender, Scott; Mark, Hans; Aguilera, Frank

    1996-01-01

    The attributes of a variable diameter rotor concept applied to civil tiltrotor aircraft are investigated using the V/STOL aircraft sizing and performance computer program (VASCOMP). To begin, civil tiltrotor viability issues that motivate advanced rotor designs are discussed. Current work on the variable diameter rotor and a theoretical basis for the advantages of the rotor system are presented. The size and performance of variable diameter and conventional tiltrotor designs for the same baseline mission are then calculated using a modified NASA Ames version of VASCOMP. The aircraft are compared based on gross weight, fuel required, engine size, and autorotative performance for various hover disk loading values. Conclusions about the viability of the resulting designs are presented and a program for further variable diameter rotor research is recommended.

  4. The historical trend in float zone crystal diameters and power requirements for float zoned silicon crystals

    NASA Technical Reports Server (NTRS)

    Kramer, H. G.

    1981-01-01

    The power needed to zone silicon crystals by radio frequency heating was analyzed. The heat loss mechanisms are examined. Curves are presented for power as a function of crystal diameter for commercial silicon zoning.

  5. Biomechanics and load resistance of small-diameter and mini dental implants: a review of literature.

    PubMed

    Hasan, Istabrak; Bourauel, Christoph; Mundt, Torsten; Stark, Helmut; Heinemann, Friedhelm

    2014-02-01

    In recent years, the application of small-diameter and mini dental implants to support removable and fixed prosthesis has dramatically increased. However, the success of these implants under functional biting forces and the reaction of the bone around them need to be analyzed. This review was aimed to present studies that deal with the fatigue life of small-diameter and mini dental implants under normal biting force, and their survival rate. The numerical and experimental studies concluded that an increase in the risk of bone damage or implant failure may be assumed in critical clinical situations and implants with <3 mm diameter have a risk of fracture in clinical practice. The survival rate of the small-diameter and mini dental implants over 5 years was 98.3-99.4%. PMID:24293447

  6. Effect of diameter and surface roughness on ultrasonic properties of GaAs nanowires

    NASA Astrophysics Data System (ADS)

    Dhawan, Punit Kumar; Wan, Meher; Verma, S. K.; Pandey, D. K.; Yadav, R. R.

    2015-02-01

    Second and third order elastic constants of GaAs Nanowires (NWs) are calculated using the many-body interaction potential model. The velocities of ultrasonic waves at different orientations of propagation with unique axis are evaluated using the second order elastic constants. The ultrasonic attenuation and thermal relaxation times of the single crystalline GaAs-NW are determined as a function of diameter and surface roughness by means of Mason theoretical approach using the thermal conductivity and higher order elastic constants. The diameter variation of ultrasonic attenuation and thermal relaxation exhibit second order polynomial function of diameter. It is also found that ultrasonic attenuation and thermal relaxation follow the exponential decay with the surface roughness for GaAs-NW due to reduction in thermal conductivity caused by dominance of surface asperities. Finally, the correlations among ultrasonic parameters, thermal conductivity, surface roughness, and diameter for GaAs-NWs are established leading towards potential applications.

  7. Ultrasound evaluation of the impact of cricoid pressure versus novel 'paralaryngeal pressure' on anteroposterior oesophageal diameter.

    PubMed

    Andruszkiewicz, P; Wojtczak, J; Wroblewski, L; Kaczor, M; Sobczyk, D; Kowalik, I

    2016-09-01

    To assess the degree to which cricoid pressure (Sellick manoeuvre) actually compresses the oesophagus, we measured the effect of cricoid pressure and paralaryngeal pressure on the outer anteroposterior diameter of the upper oesophagus with ultrasound in 39 healthy volunteers. The mean (SD) outer anteroposterior oesophageal diameter was 0.77 (0.11) cm with no pressure, 0.79 (0.13) cm with the application of cricoid pressure of 30 N and 0.68 (0.12) cm with the application of paralaryngeal pressure of 30 N (p < 0.0001). If cricoid pressure does not reduce the anteroposterior diameter of the oesophagus, it is difficult or impossible to explain the efficacy of the Sellick manoeuvre. However, paralaryngeal pressure decreases this diameter and has the potential to occlude the upper oesophagus. PMID:27523050

  8. Preliminary design of a 15 m diameter mechanically scanned deployable offset antenna

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The preliminary design of a 15 meter diameter mechanically scanned, offset rotating, fed parabolic reflector antenna system is reported and the results of preliminary performance, structural and thermal analyses are presented.

  9. Fatigue acceptance test limit criteria for larger diameter rolled thread fasteners

    SciTech Connect

    Kephart, A.R.

    1999-05-19

    This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches (25 mm) in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process.

  10. A robust approach to estimate stellar angular diameters from photometry and spectral type

    NASA Astrophysics Data System (ADS)

    Chelli, A.; Bourges, L.; Duvert, G.; Lafrasse, S.; Mella, G.; Le Bouquin, J.-B.; Chesneau, O.

    2014-07-01

    Observing reference stars with a known diameter is almost the only possibility to calibrate optical interferometry observations. The JMMC Calibrator Workgroup develops methods to ascertain the angular diameter of stars since 2000 and provides this expertise in the SearchCal software and associated databases. We provide on a regularly basis the JSDC, a catalogue of such stars, and an open access to our server that dynamically finds calibrators near science objects by querying CDS hosted catalogs. Here we propose a novel approach in the estimation of angular stellar diameters based on observational quantities only. It bypasses the knowledge of the visual extinction and intrinsic colors, thanks to the use of absorption free pseudo-colors (AFC) and the spectral type number on the x-axis. This new methodology allows to compute the angular diameter of 443 703 stars with a relative precision of about 1%. This calibrator set will become after filtering the next JSDC release.

  11. Economics of ingot slicing with an internal diameter saw for low-cost solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Liu, J. K.; Fiegl, G.

    1981-01-01

    Slicing of silicon ingots using diamond impregnated internal diameter blade saws has been a standard technology of the semiconductor industry. This paper describes work on improvements to this technology for 10 cm diameter ingot slicing. Ingot rotation, dynamic blade edge control with feedback, mechanized blade dressing and development of thinner blades are the approaches tried. A comparison of the results for wafering with and without ingot rotation is also made. A sensitivity analysis of the major cost elements in wafering is performed for 10 cm diameter ingot and extended to the 15 cm diameter ingot case. Various parameter values such as machine cost, feed rate and consumable materials cost are identified both for single and multiple ingot slicing.

  12. Hypervelocity impact on brittle materials of semi-infinite thickness: fracture morphology related to projectile diameter

    NASA Astrophysics Data System (ADS)

    Taylor, Emma A.; Kay, Laurie; Shrine, Nick R. G.

    Hypervelocity impact on brittle materials produces features not observed on ductile targets. Low fracture toughness and high yield strength produce a range of fracture morphologies including cracking, spallation and shatter. For sub-mm diameter projectiles, impact features are characterised by petaloid spallation separated by radial cracks. The conchoidal or spallation diameter is a parameter in current cratering equations. An alternative method for interpreting hypervelocity impacts on glass targets of semi-infinite thickness is tested against impact data produced using the Light Gas Gun (LGG) facility at the University of Kent at Canterbury (UKC), U.K. Spherical projectiles of glass and other materials with diameters 30-300 μm were fired at ~5 km s^-1 at a glass target of semi-infinite thickness. The data is used to test a power law relationship between projectile diameter and crack length. The results of this work are compared with published cratering/spallation equations for brittle materials.

  13. On the Binning and Associated Uncertainty of Crater Diameter Size-Frequency Distributions

    NASA Astrophysics Data System (ADS)

    Weaver, B. P.; Robbins, S. J.; Plesko, C. S.; Riggs, J. D.

    2015-05-01

    The tabulation and graphical display of crater size-frequency data (crater diameters) is a critical part of analyzing crater populations, but despite a landmark 1979 paper, standardization remains elusive. We will discuss recommendations.

  14. Allowable silicon wafer thickness versus diameter for ingot rotation ID wafering

    NASA Technical Reports Server (NTRS)

    Chen, C. P.; Leipold, M. H.

    1982-01-01

    Inner diameter (ID) wafering of ingot rotation reduce the ID saw blade diameter was investigated. The blade thickness can be reduced, resulting in minimal kerf loss. However, significant breakage of wafers occurs during the rotation wafering as the wafer thickness decreases. Fracture mechanics was used to develop an equation relating wafer thickness, diameter and fracture behavior at the point of fracture by using a model of a wafer, supported by a center column and subjected to a cantilever force. It is indicated that the minimum allowable wafer thickness does not increase appreciably with increasing wafer diameter and that fracture through the thickness rather than through the center supporting column limits the minimum allowable wafer thickness. It is suggested that the minimum allowable wafer thickness can be reduced by using a vacuum chuck on the wafer surface to enhance cleavage fracture of the center core and by using 111 ingots.

  15. TNO and Centaur Diameters, Albedos, and Densities V4.0

    NASA Astrophysics Data System (ADS)

    Johnston, W. R.

    2016-07-01

    This data set is a compilation of published diameters, albedos, and densities for Transneptunian Objects (TNOs) and Centaurs. A total of 190 objects are listed, many with more than one entry. This version covers published values through 31 March 2016.

  16. Large-diameter femoral heads in total hip arthroplasty: an evidence-based review.

    PubMed

    Banerjee, Samik; Pivec, Robert; Issa, Kimona; Kapadia, Bhaveen H; Khanuja, Harpal S; Mont, Michael A

    2014-11-01

    Recent advances in the wear characteristics and material properties of highly cross-linked polyethyl-ene and fourth-generation ceramic bearings have led to increasing use of large-diameter (≥ 36 mm) femoral heads in total hip arthroplasty (THA). In this article, we review the current concepts and principles behind use of large-diameter ceramic or cobalt-chromium femoral heads on polyethylene bearings in THA. We specifically review the biomechanics, some of the early concerns about polyethylene wear and rim fractures, recent improvements in material properties of polyethylene and ceramic bearings, dislocation rates, and clinical and functional outcomes of large-diameter heads in THA. Recent literature suggests that the incidence of dislocation has been substantially reduced because of improvements in jump distance and impingement-free range of motion with use of large-diameter heads. Limited evidence suggests excellent short-term and midterm clinical and functional outcomes with these heads. PMID:25379747

  17. Serial Measurements of Splanchnic Vein Diameters in Rats Using High-Frequency Ultrasound

    PubMed Central

    Seitz, Bridget M.; Krieger-Burke, Teresa; Fink, Gregory D.; Watts, Stephanie W.

    2016-01-01

    The purpose of this study was to investigate serial ultrasound imaging in rats as a fully non-invasive method to (1) quantify the diameters of splanchnic veins in real time as an indirect surrogate for the capacitance function of those veins, and (2) assess the effects of drugs on venous dimensions. A 21 MHz probe was used on anesthetized male Sprague–Dawley rats to collect images containing the portal vein (PV), superior mesenteric vein (SMV), abdominal inferior vena cava (IVC), and splenic vein (SpV; used as a landmark in timed studies) and the abdominal aorta (AA). Stable landmarks were established that allowed reproducible quantification of cross-sectional diameters within an animal. The average diameters of vessels measured every 5 min over 45 min remained within 0.75 ± 0.15% (PV), 0.2 ± 0.09% (SMV), 0.5 ± 0.12% (IVC), and 0.38 ± 0.06% (AA) of baseline (PV: 2.0 ± 0.12 mm; SMV: 1.7 ± 0.04 mm; IVC: 3.2 ± 0.1 mm; AA: 2.3 ± 0.14 mm). The maximal effects of the vasodilator sodium nitroprusside (SNP; 2 mg/kg, i.v. bolus) on venous diameters were determined 5 min post SNP bolus; the diameters of all noted veins were significantly increased by SNP, while mean arterial pressure (MAP) decreased 29 ± 4 mmHg. By contrast, administration of the venoconstrictor sarafotoxin (S6c; 5 ng/kg, i.v. bolus) significantly decreased PV and SpV, but not IVC, SMV, or AA, diameters 5 min post S6c bolus; MAP increased by 6 ± 2 mmHg. In order to determine if resting splanchnic vein diameters were stable over much longer periods of time, vessel diameters were measured every 2 weeks for 8 weeks. Measurements were found to be highly reproducible within animals over this time period. Finally, to evaluate the utility of vein imaging in a chronic condition, images were acquired from 4-week deoxycorticosterone acetate salt (DOCA-salt) hypertensive and normotensive (SHAM) control rats. All vessel diameters increased from baseline while MAP increased (67 ± 4 mmHg) in DOCA-salt rats

  18. Serial Measurements of Splanchnic Vein Diameters in Rats Using High-Frequency Ultrasound.

    PubMed

    Seitz, Bridget M; Krieger-Burke, Teresa; Fink, Gregory D; Watts, Stephanie W

    2016-01-01

    The purpose of this study was to investigate serial ultrasound imaging in rats as a fully non-invasive method to (1) quantify the diameters of splanchnic veins in real time as an indirect surrogate for the capacitance function of those veins, and (2) assess the effects of drugs on venous dimensions. A 21 MHz probe was used on anesthetized male Sprague-Dawley rats to collect images containing the portal vein (PV), superior mesenteric vein (SMV), abdominal inferior vena cava (IVC), and splenic vein (SpV; used as a landmark in timed studies) and the abdominal aorta (AA). Stable landmarks were established that allowed reproducible quantification of cross-sectional diameters within an animal. The average diameters of vessels measured every 5 min over 45 min remained within 0.75 ± 0.15% (PV), 0.2 ± 0.09% (SMV), 0.5 ± 0.12% (IVC), and 0.38 ± 0.06% (AA) of baseline (PV: 2.0 ± 0.12 mm; SMV: 1.7 ± 0.04 mm; IVC: 3.2 ± 0.1 mm; AA: 2.3 ± 0.14 mm). The maximal effects of the vasodilator sodium nitroprusside (SNP; 2 mg/kg, i.v. bolus) on venous diameters were determined 5 min post SNP bolus; the diameters of all noted veins were significantly increased by SNP, while mean arterial pressure (MAP) decreased 29 ± 4 mmHg. By contrast, administration of the venoconstrictor sarafotoxin (S6c; 5 ng/kg, i.v. bolus) significantly decreased PV and SpV, but not IVC, SMV, or AA, diameters 5 min post S6c bolus; MAP increased by 6 ± 2 mmHg. In order to determine if resting splanchnic vein diameters were stable over much longer periods of time, vessel diameters were measured every 2 weeks for 8 weeks. Measurements were found to be highly reproducible within animals over this time period. Finally, to evaluate the utility of vein imaging in a chronic condition, images were acquired from 4-week deoxycorticosterone acetate salt (DOCA-salt) hypertensive and normotensive (SHAM) control rats. All vessel diameters increased from baseline while MAP increased (67 ± 4 mmHg) in DOCA-salt rats

  19. A route to fabricate single crystalline bismuth nanowire arrays with different diameters

    NASA Astrophysics Data System (ADS)

    Li, Liang; Zhang, Yong; Li, Guanghai; Zhang, Lide

    2003-09-01

    Single crystalline bismuth nanowire arrays in anodic alumina membrane have been fabricated by pulsed electrodeposition. The nanowires of different diameters were obtained by changing the electrical parameter of the pulsed electrodeposition using anodic alumina membrane as template with the same pore size. X-ray diffraction and TEM analysis show that the bismuth nanowires are single crystalline with highly preferential orientation, and the diameter of nanowires increases with increasing the relaxation time of pulse. The growth mechanism of nanowires was discussed.

  20. Determination of Diameter and Index of Refraction of Textile Fibers by Laser Backscattering

    SciTech Connect

    H. Okuda; B. Stratton; L. Meixler; P. Efthimion; D.Mansfield

    2003-07-24

    A new method was developed to determine both diameters and indices of refraction and hence the birefringence of cylindrical textile and industrial fibers and bundles by measuring intensity patterns of the scattered light over an interval of scattering angles. The measured intensity patterns are compared with theoretical predictions (Mie theory) to determine fiber diameter and index of refraction. It is shown that the method is simple and accurate and may be useful as an on-line, noncontact diagnostic tool in real time.

  1. Maximum Diameter of Native Abdominal Aortic Aneurysm Measured by Angio-Computed Tomography

    PubMed Central

    Mora, Caroline E.; Marcus, Claude D.; Barbe, Coralie M.; Ecarnot, Fiona B.; Long, Anne L.

    2015-01-01

    Background: Computed tomography angiography (CTA) is the reference technique for the measurement of native maximum abdominal aortic aneurysm (AAA) diameter when surgery is being considered. However, there is a wide choice available for the methodology of maximum AAA diameter measurement on CTA, and to date, no consensus has been reached on which method is best. We analyzed clinical decisions based on these various measures of native maximum AAA diameter with CTA, then analyzed their reproducibility and identified the method of measurement yielding the highest agreement in terms of patient management. Materials and Methods: Three sets of measures in 46 native AAA were obtained, double-blind by three radiologists (J, S, V) on orthogonal planes, curved multiplanar reconstructions, and semi-automated-software, based on the AAA-lumen centerline. From each set, the clinical decision was recorded as follows: "Follow-up" (if all diameters <50 mm), "ambiguous" (if at least one diameter <50 mm AND at least one ≥50 mm) or "Surgery " (if all diameters ≥50 mm). Intra- and interobserver agreements in clinical decisions were compared using the weighted Kappa coefficient. Results: Clinical decisions varied according to the measurement sets used by each observer, and according to intra and interobserver (lecture#1) reproducibility. Based on the first reading of each observer, the number of AAA proposed for surgery ranged from 11 to 24 for J, 5 to 20 for S, and 15 to 23 for V. The rate of AAAs classified as "ambiguous" varied from 11% (5/46) to 37% (17/46). The semi-automated method yielded very good intraand interobserver agreements in clinical decisions in all comparisons (Kappa range 0.83–1.00). Conclusion: The semi-automated method seems to be appropriate for native AAA maximum diameter measurement on CTA. In the absence of AAA outer-wallbased software more robust for complex AAA, clinical decisions might best be made with diameter values obtained using this technique

  2. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    PubMed Central

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical masking of a vessel position and measurements of it’s diameter from laser speckle images. This approach demonstrates high reliability and stability. PMID:27446704

  3. Mapping mean axon diameter and axonal volume fraction by MRI using temporal diffusion spectroscopy

    PubMed Central

    Xu, Junzhong; Li, Hua; Harkins, Kevin D.; Jiang, Xiaoyu; Xie, Jingping; Kang, Hakmook; Does, Mark D.; Gore, John C.

    2014-01-01

    Mapping mean axon diameter and intra-axonal volume fraction may have significant clinical potential because nerve conduction velocity is directly dependent on axon diameter, and several neurodegenerative diseases affect axons of specific sizes and alter axon counts. Diffusion-weighted MRI methods based on the pulsed gradient spin echo (PGSE) sequence have been reported to be able to assess axon diameter and volume fraction non-invasively. However, due to the relatively long diffusion times used, e.g. > 20 ms, the sensitivity to small axons (diameter < 2 µm) is low, and the derived mean axon diameter has been reported to be overestimated. In the current study, oscillating gradient spin echo (OGSE) diffusion sequences with variable frequency gradients were used to assess rat spinal white matter tracts with relatively short effective diffusion times (1 – 5 ms). In contrast to previous PGSE-based methods, the extra-axonal diffusion cannot be modeled as hindered (Gaussian) diffusion when short diffusion times are used. Appropriate frequency-dependent rates are therefore incorporated into our analysis and validated by histology-based computer simulation of water diffusion. OGSE data were analyzed to derive mean axon diameters and intra-axonal volume fractions of rat spinal white matter tracts (mean axon diameter ~ 1.27 – 5.54 µm). The estimated values were in good agreement with histology, including the small axon diameters (< 2.5 µm). This study establishes a framework for quantification of nerve morphology using the OGSE method with high sensitivity to small axons. PMID:25225002

  4. Optical fiber diameter measurement by the diffraction method with digital processing of the light scattering indicatrix

    NASA Astrophysics Data System (ADS)

    Kokodii, N. G.; Natarova, A. O.

    2016-07-01

    Relations between the position of the first diffraction minima and the fiber diameter are derived based on the solution of the problem of electromagnetic wave diffraction on a transparent fiber with a circular cross section. The obtained formulas are used to measure the fiber diameter. The diffraction pattern is recorded with a digital camera. The obtained image is digitally processed to determine the positions of the first two scattering indicatrix minima.

  5. Effects of support diameter and compliance on common marmoset (Callithrix jacchus) gait kinematics.

    PubMed

    Young, Jesse W; Stricklen, Bethany M; Chadwell, Brad A

    2016-09-01

    Locomotion is precarious in an arboreal habitat, where supports can vary in both diameter and level of compliance. Several previous studies have evaluated the influence of substrate diameter on the locomotor performance of arboreal quadrupeds. The influence of substrate compliance, however, has been mostly unexamined. Here, we used a multifactorial experimental design to investigate how perturbations in both diameter and compliance affect the gait kinematics of marmosets (Callithrix jacchus; N=2) moving over simulated arboreal substrates. We used 3D-calibrated video to quantify marmoset locomotion over a horizontal trackway consisting of variably sized poles (5, 2.5 and 1.25 cm in diameter), analyzing a total of 120 strides. The central portion of the trackway was either immobile or mounted on compliant foam blocks, depending on condition. We found that narrowing diameter and increasing compliance were both associated with relatively longer substrate contact durations, though adjustments to diameter were often inconsistent relative to compliance-related adjustments. Marmosets also responded to narrowing diameter by reducing speed, flattening center of mass (CoM) movements and dampening support displacement on the compliant substrate. For the subset of strides on the compliant support, we found that speed, contact duration and CoM amplitude explained >60% of the variation in substrate displacement over a stride, suggesting a direct performance advantage to these kinematic adjustments. Overall, our results show that compliant substrates can exert a significant influence on gait kinematics. Substrate compliance, and not just support diameter, should be considered a critical environmental variable when evaluating locomotor performance in arboreal quadrupeds. PMID:27582562

  6. Smart aircraft composite structures with embedded small-diameter optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Takeda, Nobuo; Minakuchi, Shu

    2012-02-01

    This talk describes the embedded optical fiber sensor systems for smart aircraft composite structures. First, a summary of the current Japanese national project on structural integrity diagnosis of aircraft composite structures is described with special emphasis on the use of embedded small-diameter optical fiber sensors including FBG sensors. Then, some examples of life-cycle monitoring of aircraft composite structures are presented using embedded small-diameter optical fiber sensors for low-cost and reliable manufacturing merits.

  7. Production of a large diameter hot-electron plasma by electron cyclotron resonance heating

    SciTech Connect

    Kawai, Y.; Sakamoto, K.

    1982-05-01

    A large diameter hot-electron plasma is produced by electron cyclotron resonance heating, using a slotted Lisitano coil as a launcher. It is found from detailed measurements of the plasma parameters that n/sub e/< or approx. =3 x 10/sup 11/ cm/sup -3/ and T/sub e/< or approx. =40 eV, with a diameter roughly-equal14 cm. High-energy tails with temperatures of more than 100 eV are observed.

  8. Production of a large diameter hot-electron plasma by electron cyclotron resonance heating

    NASA Astrophysics Data System (ADS)

    Kawai, Y.; Sakamoto, K.

    1982-05-01

    A large diameter hot-electron plasma is produced by electron cyclotron resonance heating, using a slotted Lisitano coil as a launcher. It is found from detailed measurements of the plasma parameters that ne≲3×1011 cm-3 and Te≲40 eV, with a diameter ≊14 cm. High-energy tails with temperatures of more than 100 eV are observed.

  9. Optical diameters of stars measured with the Mt. Wilson Mark III interferometer

    NASA Technical Reports Server (NTRS)

    Simon, R. S.; Mozurkewich, D.; Johnston, K. J.; Gaume, Ralph; Hutter, D. J.; Bowers, P. F.; Colavita, M. M.; Shao, M.

    1990-01-01

    Reliable stellar angular diameters can now be determined using the Mark III Optical Interferometer located on Mt. Wilson, California. The Mark III is a Michelson Interferometer capable of measuring the interferometric fringe visibility for stars using interferometer baselines varying from 3 to 31.5 meters in length. Angular diameters measured with the Mark III Optical Interferometer are presented for 12 stars at wavelengths of 450 and 800 nm.

  10. Validating a Nonhuman Primate Model of Super-Selective Intraophthalmic Artery Chemotherapy: Comparing Ophthalmic Artery Diameters

    PubMed Central

    Ditta, Lauren C.; Choudhri, Asim F.; Tse, Brian C.; Landers, Mark M.; Haik, Barrett G.; Steinle, Jena J.; Williams, J. Scott; Wilson, Matthew W.

    2012-01-01

    Purpose. Superselective intraophthalmic artery chemotherapy (SSIOAC) is being used for treatment of retinoblastoma; however, the hemodynamic consequences and toxicities are not fully known. We developed a nonhuman primate (NHP) model of SSIOAC and reported our clinical observations. For validation, we compared ophthalmic artery (OA) diameters between NHPs and children (<6 years). Methods. Endovascular cannulation of the right OA was performed three times each in six adult male Rhesus macaques. Angiographic OA images were obtained and measured, and postmortem OAs were histologically sectioned and measured. Retrospectively, computed tomography (CT) and magnetic resonance (MR) angiography images of the head in children and adolescents (as an adult reference) were used to measure the OA luminal diameter at its origin. Results. The median angiographic diameter of treated NHP OA origins (n = 6) was 1.06 mm (range 0.94–1.56). Histologic measurements (8 of 12 NHP OAs) gave a median diameter of 1.09 mm (range 0.95–1.41). In 98 children (from 169 consecutive CT and MR angiography studies; median age 1.01 years, range 0.01–5.74), 186 OAs were measurable at the origin (median luminal diameter 1.28 mm, range 0.82–2.00; P = 0.16 for the angiographic NHP diameters versus pediatric cohort). Angiographic measurements of 34 OAs (of 20 consecutive studies of adolescents; median age 16.55 years, range 14.40–18.18) gave a median luminal diameter of 1.45 mm (origin, range 1.13–1.66; P < 0.0001, adolescent versus pediatric). Conclusions. Measurements of the OA luminal diameter at its origin were similar between our NHP and pediatric cohort, validating our NHP model for testing both the hemodynamic consequences and toxicities of SSIOAC. PMID:23111611

  11. Synthesis of hematite (alpha-Fe2O3) nanorods: diameter-size and shape effects on their applications in magnetism, lithium ion battery, and gas sensors.

    PubMed

    Wu, Changzheng; Yin, Ping; Zhu, Xi; OuYang, Chuanzi; Xie, Yi

    2006-09-14

    We demonstrated in this paper the shape-controlled synthesis of hematite (alpha-Fe(2)O(3)) nanostructures with a gradient in the diameters (from less than 20 nm to larger than 300 nm) and surface areas (from 5.9 to 52.3 m(2)/g) through an improved synthetic strategy by adopting a high concentration of inorganic salts and high temperature in the synthesis systems to influence the final products of hematite nanostructures. The benefits of the present work also stem from the first report on the <20-nm-diameter and porous hematite nanorods, as well as a new facile strategy to the less-than-20-nm nanorods, because the less-than-20-nm diameter size meets the vital size domain for magnetization properties in hematite. Note that the porous and nonporous hematite one-dimensional nanostructures with diameter gradients give us the first opportunity to investigate the Morin temperature evolution of nanorod diameter and porosity. Evidently, the magnetic properties for nanorods exhibit differences compared with those for the spherical particle counterparts. Hematite nanorods are strongly dependent on their diameter size and porosity, where the magnetization is not sensitive to the size evolution from submicron particles to the 60-90 nm nanorods, while the magnetic properties change significantly in the case of <20 nm. In other words, for the magnetic properties of nanorods, in a comparable size range, the porous existence could also influence the magnetic behavior. Moreover, applications in formaldehyde (HCHO) gas sensors and lithium batteries for the hematite nanostructures with the diameter/surface area gradient reveal that the performance of electrochemical and gas-sensor properties strongly depends on the diameter size and Brunauer-Emmett-Teller (BET) surface areas, which is consistent with the crystalline point of view. Thus, this work not only provides the first example of the fabrication of hematite nanostructure sensors for detecting HCHO gas, but also reveals that the

  12. A novel non-contact measurement method of the inner diameter

    NASA Astrophysics Data System (ADS)

    Jia, Bingtian; Liu, Changjie; Li, Xingqiang; Fu, Luhua; Wang, Zhong

    2015-08-01

    High accuracy automatic measurement of engine box is significant for enhancing the quality and performance of the engine. To complete the fast automatic measurement of the engine box shaft hole diameter, a new non-contact methods for inner hole diameter measuring is proposed in this paper, a mathematic model is built according to this method. A probe based on laser displacement sensors is developed to meet the method by distributing the laser displacement sensors in the probe cross-section uniformly. By this method, shaft hole diameter can be got with single measurement. This method eliminates some defects involved in existing shaft hole diameter non-contact measuring methods, it does not need the rotation of the probe and accurate locating of the probe center and the shaft hole center. Experiments proved that the methods can be used to complete the task of the shaft hole diameter measuring with simple operation and accurate result. Experiments have also shown that the proposed method is an effective method of non-contact high accuracy diameter measurement.

  13. Influence of diesel engine combustion parameters on primary soot particle diameter.

    PubMed

    Mathis, Urs; Mohr, Martin; Kaegi, Ralf; Bertola, Andrea; Boulouchos, Konstantinos

    2005-03-15

    Effects of engine operating parameters and fuel composition on both primary soot particle diameter and particle number size distribution in the exhaust of a direct-injected heavy-duty diesel engine were studied in detail. An electrostatic sampler was developed to deposit particles directly on transmission electron microscopy (TEM) grids. Using TEM, the projected area equivalent diameter of primary soot particles was determined. A scanning mobility particle sizer (SMPS) was used for the measurement of the particle number size distribution. Variations in the main engine operating parameters (fuel injection system, air management, and fuel properties) were made to investigate soot formation and oxidation processes. Primary soot particle diameters determined by TEM measurements ranged from 17.5 to 32.5 nm for the diesel fuel and from 24.1 to 27.2 nm for the water-diesel emulsion fuel depending on the engine settings. For constant fuel energy flow rate, the primary particle size from the water-diesel emulsion fuel was slightly larger than that from the diesel fuel. A reduction in primary soot particle diameter was registered when increasing the fuel injection pressure (IP) or advancing the start of injection (SOI). Larger primary soot particle diameters were measured while the engine was operating with exhaust gas recirculation (EGR). Heat release rate analysis of the combustion process revealed that the primary soot particle diameter decreased when the maximum flame temperature increased for the diesel fuel. PMID:15819252

  14. Differentiating cancerous tissues from noncancerous tissues using single-fiber reflectance spectroscopy with different fiber diameters

    NASA Astrophysics Data System (ADS)

    Sircan-Kuçuksayan, Aslinur; Denkceken, Tuba; Canpolat, Murat

    2015-11-01

    Elastic light-scattering spectra acquired with single-fiber optical probes with diameters of 100, 200, 400, 600, 800, 1000, 1200, and 1500 μm were used to differentiate cancerous from noncancerous prostate tissues. The spectra were acquired ex vivo on 24 excised prostate tissue samples collected from four patients. For each probe, the spectra and histopathology results were compared in order to investigate the correlation between the core diameters of the single-fiber optical probe and successful differentiation between cancerous and noncancerous prostate tissues. The spectra acquired using probes with a fiber core diameter of 400 μm or smaller successfully differentiated cancerous from noncancerous prostate tissues. Next, the spectra were acquired from monosized polystyrene microspheres with a diameter of 5.00±0.01 μm to investigate the correlation between the core diameters of the probes and the Mie oscillations on the spectra. Monte Carlo simulations of the light distribution of the tissue phantoms were run to interrogate whether the light detected by the probes with different fiber core diameters was in the ballistic or diffusive regime. If the single-fiber optical probes detect light in the ballistic regime, the spectra can be used to differentiate between cancerous and noncancerous tissues.

  15. The directional sensitivity of the acoustic radiation force to particle diameter.

    PubMed

    Ran, W; Saylor, J R

    2015-06-01

    When viscous corrections to the inviscid acoustic radiation force theory are implemented and applied to a standing wave field, the direction of the acoustic radiation force on particles varies from theory to theory. Specifically, some theories predict that the direction of the force depends on the particle diameter, while others reveal that the direction of the force is independent of particle diameter. The present study is an experimental investigation of the direction of the acoustic radiation force which suggests that particle diameter does affect the direction. Experiments were conducted in air using an ultrasonic standing wave field with a nominal frequency of 30 kHz. Smoke particles and fine water droplets having a range of diameters were flowed into the region of a standing wave field. The direction of the acoustic radiation force was determined by observing whether the particles accumulated in the nodes or the anti-nodes of the standing wave. Results show a change in the direction of the acoustic radiation force at a particle diameter of 0.3±0.1 μm, which corresponds to a particle diameter to acoustic-boundary-layer thickness ratio of 0.023±0.008. PMID:26093419

  16. Differentiating cancerous tissues from noncancerous tissues using single-fiber reflectance spectroscopy with different fiber diameters.

    PubMed

    Sircan-Kuçuksayan, Aslinur; Denkceken, Tuba; Canpolat, Murat

    2015-11-01

    Elastic light-scattering spectra acquired with single-fiber optical probes with diameters of 100, 200, 400, 600, 800, 1000, 1200, and 1500 μm were used to differentiate cancerous from noncancerous prostate tissues. The spectra were acquired ex vivo on 24 excised prostate tissue samples collected from four patients. For each probe, the spectra and histopathology results were compared in order to investigate the correlation between the core diameters of the single-fiber optical probe and successful differentiation between cancerous and noncancerous prostate tissues. The spectra acquired using probes with a fiber core diameter of 400 μm or smaller successfully differentiated cancerous from noncancerous prostate tissues. Next, the spectra were acquired from monosized polystyrene microspheres with a diameter of 5.00±0.01 μm to investigate the correlation between the core diameters of the probes and the Mie oscillations on the spectra. Monte Carlo simulations of the light distribution of the tissue phantoms were run to interrogate whether the light detected by the probes with different fiber core diameters was in the ballistic or diffusive regime. If the single-fiber optical probes detect light in the ballistic regime, the spectra can be used to differentiate between cancerous and noncancerous tissues. PMID:26590218

  17. Diameter measurement of single-mode fiber by using interferometric and imaging techniques.

    PubMed

    Joenathan, C; Bunch, R M

    1993-10-20

    Two methods to measure the cladding diameter of single-mode fibers are presented. The first method is based on an interference fringe measurement technique. Interference fringe spacing at two different planes is measured to determine the cladding diameter of the fiber. The theory of the fringe formation in the interferometeric arrangement using single-mode fibers is discussed. It is theoretically shown that the far-field overlapping Gaussian field distribution from the fibers shifts the position of the fringe maxima and minima. As a special case of unit fringe visibility the minima positions do not shift, whereasthe maxima positions are shifted. In the case of a Lloyd mirror arrangement it is shown that fringes can be obtained from a rough surface as well. A lens is used in the second method to image the two identical point sources that cause the interference. Through the use of the magnification and spacing of the images, the cladding diameter is estimated. It is shown that the accuracy of the fiber cladding-diameter measurement can be enhanced by generating multiple point sources. Consistent results of the fiber cladding diameter have been obtained with the proposed methods. Fiber cladding-diameter measurements with a standard error of less than 0.15 µm can be achieved. PMID:20856425

  18. Optimizing the value of measuring inferior vena cava diameter in shocked patients.

    PubMed

    Abu-Zidan, Fikri M

    2016-02-01

    Point-of-care ultrasound has been increasingly used in evaluating shocked patients including the measurement of inferior vena cava (IVC) diameter. Operators should standardize their technique in scanning IVC. Relative changes are more important than absolute numbers. We advise using the longitudinal view (B mode) to evaluate the gross collapsibility, and the M mode to measure the IVC diameter. Combining the collapsibility and diameter size will increase the value of IVC measurement. This approach has been very useful in the resuscitation of shocked patients, monitoring their fluid demands, and predicting recurrence of shock. Pitfalls in measuring IVC diameter include increased intra-thoracic pressure by mechanical ventilation or increased right atrial pressure by pulmonary embolism or heart failure. The IVC diameter is not useful in cases of increased intra-abdominal pressure (abdominal compartment syndrome) or direct pressure on the IVC. The IVC diameter should be combined with focused echocardiography and correlated with the clinical picture as a whole to be useful. PMID:26855888

  19. Effect of scuba-diving on optic nerve and sheath diameters

    PubMed Central

    Mehrpour, Masoud; Shams-Hosseini, Narges Sadat; Rezaali, Saeed

    2014-01-01

    Background: There is not any data available about the effect of high bar pressure condition on intracranial pressure. In this study, the effect of diving on the optic nerve and sheath diameters as non-invasive markers of intracranial pressure has been investigated. Methods: Twenty professional male divers from twenty one volunteers were chosen for this cross-sectional study. Only one person who had a history of barotraumas was excluded. Each diver then completed a questionnaire on demographic data, medical and diving history. Nineteen other volunteers were selected to represent a control group. A 10-MHz linear ultrasonic probe was used to measure the optic nerve sheath diameters of both eyes in closed and supine position and its relationship with diving history of divers was determined. Results: It was found that divers have a higher mean optic nerve sheath diameter compared to the normal population as previously reported by other studies. The mean diameter of the left and right optic nerve sheaths were 6.4±0.7, 6.5±0.9 mm respectively and a significant relationship between optic nerve sheath diameter and diving history was found. Conclusion: Results showed that divers have a higher optic nerve diameter than the general population. However, our result cannot yet be considered as a marker of intracranial pressure in divers as it was conducted on an limited number of subjects and so a bigger study should be undertaken for this purpose. PMID:25664290

  20. A study of static magnetic fluid seal of large flange diameter

    NASA Astrophysics Data System (ADS)

    Decai Li, .; Xinzhi He, .; Zhili Zhang, .

    2008-03-01

    In order to meet the requirements of large diameter flange with regard to the leak rate, reliability and life span, the authors have designed a magnetic fluid static seal and analyzed the magnetic field distribution of the seal using three dimensional finite elements. In order to calculate correctly the theoretical differential pressure sustained by the seal, the authors reasoned the differential pressure formula of the magnetic fluid static seal so that the burst pressure of the magnetic fluid seal of large diameter flange can be calculated. In the experimental setup the authors tested the seal ability of large diameter flange and compared the theoretical values of the burst pressure with its experimental values. The authors put forward a way to prolong the life of the magnetic fluid static seal; the practical application verified that the way is effective. The authors measured the magnetic field distribution around the large diameter flange and the leak rate of the large diameter flange. The fact that the magnetic fluid static seal can be used for almost four years indicates that the seal is reliable. We have successfully developed "the magnetic fluid seal of large diameter flange", which was accepted as a state patent and authenticated as an achievement in the scientific research in 2003. Tables 3, Figs 7, Refs 7.

  1. The large diameter and fast growth of self-organized TiO2 nanotube arrays achieved via electrochemical anodization

    NASA Astrophysics Data System (ADS)

    Yin, H.; Liu, H.; Shen, W. Z.

    2010-01-01

    We have carried out a detailed investigation of the effect of water content on the electrochemical anodization of Ti in electrolytes consisting of ammonium fluoride, water, and ethylene glycol. We have explored the possible growth of ordered TiO2 nanotubes in the electrolyte with water concentrations from 1 to 100 vol% and the applied voltage from 10 to 150 V, where large diameter (~600 nm) and fast growth rate (~100 µm h-1) have been successfully realized for the self-organized TiO2 nanotube arrays. The achievement benefits from the clear understanding of the effects of both the water content and the anodization voltage on the formation of TiO2 nanotube arrays. We have further shown crystalline formation of TiO2 nanotubes by simple thermal annealing. The mechanisms of the effect of the water content on the diameter and growth rate revealed here should establish a basis for further optimization of the TiO2 nanotube geometries.

  2. Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation

    PubMed Central

    Balme, Sébastien; Picaud, Fabien; Manghi, Manoel; Palmeri, John; Bechelany, Mikhael; Cabello-Aguilar, Simon; Abou-Chaaya, Adib; Miele, Philippe; Balanzat, Emmanuel; Janot, Jean Marc

    2015-01-01

    Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10−2 C m−2 needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed. PMID:26036687

  3. Effect of the Si nanowire's diameter and doping profile on the electrical characteristics of gate-all-around twin Si-nanowire field-effect transistors

    NASA Astrophysics Data System (ADS)

    Kim, Dong Hun; Kim, Tae Whan

    2015-08-01

    The effect of the Si nanowire's diameter and doping profile on the electrical characteristics of gate-all-around twin Si-nanowire field-effect transistors (TSNWFETs) was simulated by using the three-dimensional technology computer-aided design simulation tools of Sentaurus and taking into account quantum effects. While the switching and the short-channel immunity characteristics were improved with decreasing nanowire diameter, the threshold voltage and the total on-current for the TSNWFETs decreased, resulting in a deterioration of device performances. The swing characteristics for the TSNWFETs maintained almost the same behaviors regardless of the boron concentration variation in the nanowire. Gate-induced drain leakage (GIDL) of the TSNWFETs appeared at a high drain voltage, and the GIDL current increased with increasing boron concentration in the Si nanowires. The electrical characteristics of the TSNWFETs were improved by optimizing the diameter and the doping concentration of the Si nanowire to lower the GIDL and the off-state leakage current.

  4. Photovoltaic concentrator module technology

    NASA Astrophysics Data System (ADS)

    Richards, Elizabeth H.; Chamberlin, Jay L.; Boes, Eldon C.

    Significant developments in the development of photovoltaic (PV) concentrator technology are described. Concentrator cell research, advances in PV concentrator cell technology, and PV concentrator module development are described. Reliability issues currently of concern, including the applicability of wet insulation resistance tests to concentrator modules, correlation of accelerated thermal cycling tests with life expectancy in the field, and the importance of quality assurance during manufacture, are discussed. Two PV concentrator power systems installed in 1989 are discussed. A PV concentrator initiative program established by the DOE is given, and the results of the latest cost study are presented.

  5. The evaluation of support performance for tunnels with different diameters excavated in weak graphitic shists

    NASA Astrophysics Data System (ADS)

    Posluk, Evren; Oğul, Kenan

    2015-04-01

    2. stage (İnönü-Köseköy) of Ankara-İstanbul High-Speed Train Project (YHT) is 150 km-long and includes 25 tunnels with total length of nearly 58 km. The 7765 m-long part of these tunnels between Bozüyük and Bilecik was excavated in the metamorphic units of Pazarcık Structural Complex which have different thicknesses and form horizontal and vertical transitions to each other. The folded weak graphitic schists with thin schistosity planes affect the tunnel support performance negatively. In this study, the tunnels with 13.5, 8.2 and 4 m-diameters excavated in the weak-very weak graphitic schists by the conventional methods and the reasons of the problems (overbreak, deformation higher than estimated, wreckage etc.) are examined. The most common problems in the tunnel construction are overbreak and deformations higher than estimated before. Upsizing the fore-polling diameters, injection with pressure and carving the tunnel face were the first applied methods for decreasing the overbreak in the wide tunnels. Although these methods decreased the overbreak, the deformations in the tunnel couldn't be prevented. In this context, the data derived from the rod and tape extensometers was examined, the elastic and plastic zones were determined, the creep behaviour was locally observed on the support elements during 65 days. Also the mass parameters (GSI, weight per unit of volume, uniaxial compression, modulus of elasticity, modulus of deformation etc.) of the weak-very weak rocks were evaluated again. By the help of the compiled data it was determined that when the tunnel diameter increases, the deformation and overbreak increase. For example, while there are approximately two overbreaks at each 100 m in a 4 m-diameter tunnel, it is three in a 8.2 m-diameter tunnel and six in a 13.5 m-diameter tunnel. The deformations were estimated as 8 cm in a 4 m-diameter tunnel, 15 cm in a 8.2 m-diameter tunnel, 20 cm in a 13.5 m-diameter tunnel. However they are respectively 7

  6. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate

    PubMed Central

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the “V”-shaped or “U”-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  7. Stabilization of carbon dioxide (CO2) bubbles in micrometer-diameter aqueous droplets and the formation of hollow microparticles.

    PubMed

    Lu, Tianyi; Fan, Rong; Delgadillo, Luis F; Wan, Jiandi

    2016-04-26

    We report an approach to stabilize carbon dioxide (CO2) gas bubbles encapsulated in micrometer-diameter aqueous drops when water in the aqueous drops is evaporated. CO2-in-water-in-oil double emulsion drops are generated using microfluidic approaches and evaporation is conducted in the presence of sodium dodecyl sulfate (SDS), poly(vinyl alcohol) (PVA) and/or graphene oxide (GO) particles dispersed in the aqueous phase of the double emulsion drops. We examine the roles of the bubble-to-drop size ratio, PVA and GO concentration in the stabilization of CO2 bubbles upon water evaporation and show that thin-shell particles with encapsulated CO2 bubbles can be obtained under optimized conditions. The developed approach offers a new strategy to study CO2 dissolution and stability on the microscale and the synthesis of novel gas-core microparticles. PMID:27025654

  8. Height-resolved large-sample INAA of a 1 m long, 13 cm diameter ditch-bottom sample

    NASA Astrophysics Data System (ADS)

    Blaauw, M.; Baas, H. W.; Donze, M.

    2003-06-01

    A facility for instrumental neutron activation analysis (INAA) of large samples (up to 1 m long and 15 cm diameter) has been built. Correction methods for the simultaneous occurrence of neutron self-shielding and gamma-ray self-attenuation effects have been implemented and tested with a variety of samples. Now, the method has been extended to allow for the interpretation of scanned, collimated measurements, where results are obtained for individual voxels. As a validation and demonstration, a ditch-bottom sample of the maximum size was taken in a frozen condition. It was cut in 2 cm slices, still frozen, and put together again with each slice in a 2 cm height Petri dish divided in three sections. This allowed for verification of the results by ordinary INAA. Possible explanations for the discrepancies we observed between ordinary and large-sample INAA in the region where the concentration gradients are the steepest are discussed.

  9. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate.

    PubMed

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the "V"-shaped or "U"-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  10. Growth of silver nanoparticles of variable and controlled diameter in silica-based and soda-lime glasses by simultaneous continuous ultraviolet irradiation and heat treatment

    SciTech Connect

    Goutaland, F.; Marin, E.; Michalon, J. Y.; Boukenter, A.

    2009-05-04

    We report on the space-selective precipitation of silver nanoparticles in silica-based and silver-exchanged soda-lime glasses by simultaneous continuous wave ultraviolet exposure and heat treatment. In silica-based glasses, we explain that simultaneous treatments lead to much higher silver nanoparticles concentration than similar treatments performed into two separated steps by minimizing the detrimental influence of oxidation on the nanoparticles' growth. In the case of silver-exchanged soda-lime glasses, nanoparticles are observed with both small and larger diameters of about 1 and 7 nm, whose concentrations depend both on the laser power density and on the heating temperature.

  11. Lack of effect of topically applied nicotine on pial arteriole diameter and blood-brain barrier integrity in the cat.

    PubMed

    Schilling, L; Bultmann, A; Wahl, M

    1992-01-01

    In the present study, the vasomotor effects of nicotine, its interaction with local chemical factors and norepinephrine, and its effects on the permeability of the blood-brain barrier (BBB) were investigated. Using perivascular microapplication, 10(-6) M nicotine was found not to exert a vasomotor effect by itself or to modify the vasodilating effect of an increase in perivascular H+, K+ and adenosine concentration. The constrictor effect of a decrease in H+, K+ or an increase in norepinephrine concentration in the perivascular space was also not altered by 10(-6) M nicotine, indicating a lack of interaction between nicotine and the compounds tested. Using cortical superfusion and intravital fluorescence microscopy nicotine (10(-7) to 10(-3) M) was also found not to affect the diameter of pial arteries during superfusion periods of 30 min each. The integrity of BBB could be demonstrated in time-matched solvent controls over 3 h using intravenously-infused FITC-labelled dextran (MW 70,000) as tracer. During cortical superfusion with 10(-7) to 10(-5) M nicotine the permeability of the BBB was not increased compared with the time-matched controls. However, during superfusion with 10(-4) and 10(-3) M nicotine, tracer extravasation could be quantified by computer-aided image analysis. The extravasation index (EI) increased by up to eight times. These data indicate that only toxic concentrations of nicotine increase BBB permeability to FITC-dextran 70,000. PMID:1521035

  12. Relative importance of aneurysm diameter and body size for predicting AAA rupture in men and women

    PubMed Central

    Lo, Ruby C.; Lu, Bing; Fokkema, Margriet T.M.; Conrad, Mark; Patel, Virendra I.; Fillinger, Mark; Matyal, Robina; Schermerhorn, Marc L.

    2014-01-01

    Objectives Women have been shown to have up to a four-fold higher risk of abdominal aortic aneurysm (AAA) rupture at any given aneurysm diameter compared to men, leading to recommendations to offer repair to women at lower diameter thresholds. Although this higher risk of rupture may simply reflect greater relative aortic dilatation in women who have smaller aortas to begin with, this has never been quantified. Our objective was therefore to quantify the relationship between rupture and aneurysm diameter relative to body size and to determine whether a differential association between aneurysm diameter, body size, and rupture risk exists for men and women. Methods We performed a retrospective review of all patients in the Vascular Study Group of New England (VSGNE) database who underwent endovascular or open AAA repair. Using each patient’s height and weight, body mass index (BMI) and body surface area (BSA) were calculated. Next, indices of each measure of body size (height, weight, BMI, BSA) relative to aneurysm diameter were calculated for each patient. To generate these indices, we divided aneurysm diameter (in cm) by the measure of body size [e.g. aortic size index (ASI) = aneurysm diameter (cm) / BSA (m2)]. Along with other relevant clinical variables, we used these indices to construct different age-adjusted and multivariable-adjusted logistic regression models to determine predictors of ruptured repair vs. elective repair. Models for men and women were developed separately and different models were compared using the area under the curve (AUC). Results We identified 4045 patients who underwent AAA repair (78% male, 53% EVAR). Women had significantly smaller diameter aneurysms, lower BSA, and higher BSA indices than men (Table 1). For men, the variable that increased the odds of rupture the most was aneurysm diameter (AUC = 0.82). Men exhibited an increased rupture risk with increasing aneurysm diameter (<5.5cm: OR 1.0; 5.5–6.4cm: OR 0.9, 95% CI 0.5–1

  13. Human intraretinal myelination: Axon diameters and axon/myelin thickness ratios

    PubMed Central

    FitzGibbon, Thomas; Nestorovski, Zoran

    2013-01-01

    Purpose: Human intraretinal myelination of ganglion cell axons occurs in about 1% of the population. We examined myelin thickness and axon diameter in human retinal specimens containing myelinated retinal ganglion cell axons. Materials and Methods: Two eyes containing myelinated patches were prepared for electron microscopy. Two areas were examined in one retina and five in the second retina. Measurements were compared to normal retinal and optic nerve samples and the rabbit retina, which normally contains myelinated axons. Measurements were made using a graphics tablet. Results: Mean axon diameter of myelinated axons at all locations were significantly larger than unmyelinated axons (P ≤ 0.01). Myelinated axons within the patches were significantly larger than axons within the optic nerve (P < 0.01). The relationship between axon diameter/fiber diameter (the G-ratio) seen in the retinal sites differed from that in the nerve. G-ratios were higher and myelin thickness was positively correlated to axon diameter (P < 0.01) in the retina but negatively correlated to axon diameter in the nerve (P < 0.001). Conclusion: Intraretinally myelinated axons are larger than non-myelinated axons from the same population and suggests that glial cells can induce diameter changes in retinal axons that are not normally myelinated. This effect is more dramatic on intraretinal axons compared with the normal transition zone as axons enter the optic nerve and these changes are abnormal. Whether intraretinal myelin alters axonal conduction velocity or blocks axonal conduction remains to be clarified and these issues may have different clinical outcomes. PMID:24212308

  14. The Importance of Large-Diameter Trees to Forest Structural Heterogeneity

    PubMed Central

    Lutz, James A.; Larson, Andrew J.; Freund, James A.; Swanson, Mark E.; Bible, Kenneth J.

    2013-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥1 cm dbh, all 1,966 snags ≥10 cm dbh, and all shrub patches ≥2 m2. Basal area of the 26 woody species was 62.18 m2/ha, of which 61.60 m2/ha was trees and 0.58 m2/ha was tall shrubs. Large-diameter trees (≥100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P≤0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses. PMID:24376579

  15. Improved Approximability and Non-approximability Results for Graph Diameter Decreasing Problems

    NASA Astrophysics Data System (ADS)

    Bilò, Davide; Gualà, Luciano; Proietti, Guido

    In this paper we study two variants of the problem of adding edges to a graph so as to reduce the resulting diameter. More precisely, given a graph G = (V,E), and two positive integers D and B, the Minimum-Cardinality Bounded-Diameter Edge Addition (MCBD) problem is to find a minimum cardinality set F of edges to be added to G in such a way that the diameter of G + F is less than or equal to D, while the Bounded-Cardinality Minimum-Diameter Edge Addition (BCMD) problem is to find a set F of B edges to be added to G in such a way that the diameter of G + F is minimized. Both problems are well known to be NP-hard, as well as approximable within O(logn logD) and 4 (up to an additive term of 2), respectively. In this paper, we improve these long-standing approximation ratios to O(logn) and to 2 (up to an additive term of 2), respectively. As a consequence, we close, in an asymptotic sense, the gap on the approximability of the MCBD problem, which was known to be not approximable within c logn, for some constant c > 0, unless P=NP. Remarkably, as we further show in the paper, our approximation ratio remains asymptotically tight even if we allow for a solution whose diameter is optimal up to a multiplicative factor approaching 5/3. On the other hand, on the positive side, we show that at most twice of the minimal number of additional edges suffices to get at most twice of the required diameter.

  16. The importance of large-diameter trees to forest structural heterogeneity.

    PubMed

    Lutz, James A; Larson, Andrew J; Freund, James A; Swanson, Mark E; Bible, Kenneth J

    2013-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥ 1 cm dbh, all 1,966 snags ≥ 10 cm dbh, and all shrub patches ≥ 2 m(2). Basal area of the 26 woody species was 62.18 m(2)/ha, of which 61.60 m(2)/ha was trees and 0.58 m(2)/ha was tall shrubs. Large-diameter trees (≥ 100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P ≤ 0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses. PMID:24376579

  17. The Submarine 4-km diameter Corossol Crater, Eastern Canada: Evidence for an impact origin

    NASA Astrophysics Data System (ADS)

    Higgins, Michael D.; Lajeunesse, Patrick; St-Onge, Guillaume; Locat, Jacques; Sanfacon, Richard; Duchesne, Mathieu J.

    2014-05-01

    The newly-discovered Corossol Crater lies in the northwestern Gulf of St. Lawrence (Eastern Canada; 50°3'N, 66°23'W) and was found in 40-185 metres of water using high-resolution multibeam sonar. It is a 4 km in diameter complex circular structure with a central uplift and concentric rings. Glacial resurfacing indicates that it predates the last phase of glaciation in this area. Dredging on the central uplift recovered many angular clasts of hard grey limestone, which forms the bedrock in much of this area. One 4 cm clast of limestone breccia is somewhat different from the other blocks and has characteristics that suggest that it is an impact breccia. The block comprises fragments of calcite limestone up to 2 mm long. In many parts of the block these fragments have thin black rims. At the edges of the block these rims are brown, presumably reflecting aqueous alteration. Mineral grains in the rims are too small to characterize, but the fact that the ensemble can be oxidized suggests that it contains sulfides. In places the block is cut by veins of fine-grained calcite with euhedral dolomite crystals. The most unusual component is rare droplets up to 2 mm long, commonly fragmented. The droplets comprise a glassy matrix with a composition very close to fluorapatite and opaque crystals that have a composition close to pyrite. A few droplets have up to 5% vesicles. Fluorapatite requires fusion temperatures of about 1600 C, which cannot be achieved at the surface of the Earth by endogenous processes. A single fragmented quartz crystal with planar features was found close to one droplet. Universal stage measurements of the orientation of the planar features give an angle of 42 degrees which is close to that of {10-13} planes. This is the most common set of deformation planes produced during shock metamorphism of quartz. Unfortunately no other grains were found with similar planes. The glassy droplets and shocked quartz together suggest that the clast was produced by an

  18. The impact of gradient strength on in vivo diffusion MRI estimates of axon diameter

    PubMed Central

    Huang, Susie Y.; Nummenmaa, Aapo; Witzel, Thomas; Duval, Tanguy; Cohen-Adad, Julien; Wald, Lawrence L.; McNab, Jennifer A.

    2014-01-01

    Diffusion magnetic resonance imaging (MRI) methods for axon diameter mapping benefit from higher maximum gradient strengths than are currently available on commercial human scanners. Using a dedicated high-gradient 3 T human MRI scanner with a maximum gradient strength of 300 mT/m, we systematically studied the effect of gradient strength on in vivo axon diameter and density estimates in the human corpus callosum. Pulsed gradient spin echo experiments were performed in a single scan session lasting approximately 2 h on each of three human subjects. The data were then divided into subsets with maximum gradient strengths of 77, 145, 212, and 293 mT/m and diffusion times encompassing short (16 and 25 ms) and long (60 and 94 ms) diffusion time regimes. A three-compartment model of intra-axonal diffusion, extra-axonal diffusion, and free diffusion in cerebrospinal fluid was fitted to the data using a Markov chain Monte Carlo approach. For the acquisition parameters, model, and fitting routine used in our study, it was found that higher maximum gradient strengths decreased the mean axon diameter estimates by two to three fold and decreased the uncertainty in axon diameter estimates by more than half across the corpus callosum. The exclusive use of longer diffusion times resulted in axon diameter estimates that were up to two times larger than those obtained with shorter diffusion times. Axon diameter and density maps appeared less noisy and showed improved contrast between different regions of the corpus callosum with higher maximum gradient strength. Known differences in axon diameter and density between the genu, body, and splenium of the corpus callosum were preserved and became more reproducible at higher maximum gradient strengths. Our results suggest that an optimal q-space sampling scheme for estimating in vivo axon diameters should incorporate the highest possible gradient strength. The improvement in axon diameter and density estimates that we demonstrate from

  19. Parabolic dish photovoltaic concentrator development

    NASA Astrophysics Data System (ADS)

    Beninga, K.; Davenport, R.; Featherby, M.; Sandubrae, J.; Walcott, K.

    1991-05-01

    Science Applications International Corporation (SAIC) and Tactical Fabs, Inc. (TFI) have fabricated a prototype parabolic dish photovoltaic (PV) concentrator system to demonstrate the functionality of this approach. A 1.5 m diameter parabolic dish was fabricated of a polyester/fiberglass composite, with a silvered polymer reflective surface. An innovative receiver cooling system used outward radial flow of cooling water in a narrow passage. This configuration matches the heat transfer capability of the cooling system to the flux profile on the PV receiver, minimizing temperature variations across the receiver. The photovoltaic cells used in the system were a new, TFI-proprietary design. Interleaved contacts form a bi-polar, rear-contact cell configuration. Because the electrical contacts are made on the rear of the cells, cells can be close-packed to form receiver arrays of arbitrary shape and size. Optical testing of the dish concentrator was performed by SAIC, SERI, and Sandia National Labs. The dish concentrator, designed for solar thermal applications, had a tight focal spot but exhibited flux non-uniformities away from the focal plane. Thermal testing of the receiver cooling system was performed with excellent success. Single PV cells, 4-cell blocks, and 144-cell receiver modules were built and tested. The cells successfully demonstrated the TFI design concept, but due to cell processing problems their efficiency was very low. Sources of the processing problems were identified and solutions were proposed, but funding limitations precluded further cell production. Operation of the complete PV dish system was conducted, and the functionality of the system was demonstrated. However, low cell efficiencies and receiver plane flux non-uniformities caused the system performance to be very low. These problems are not generic to the concept, and solutions to them proposed.

  20. Biofilm formation on a TiO₂ nanotube with controlled pore diameter and surface wettability.

    PubMed

    Anitha, V C; Lee, Jin-Hyung; Lee, Jintae; Banerjee, Arghya Narayan; Joo, Sang Woo; Min, Bong Ki

    2015-02-13

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ∼17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells. PMID:25604920

  1. Wind tunnel test of a variable-diameter tiltrotor (VDTR) model

    NASA Technical Reports Server (NTRS)

    Matuska, David; Dale, Allen; Lorber, Peter

    1994-01-01

    This report documents the results from a wind tunnel test of a 1/6th scale Variable Diameter Tiltrotor (VDTR). This test was a joint effort of NASA Ames and Sikorsky Aircraft. The objective was to evaluate the aeroelastic and performance characteristics of the VDTR in conversion, hover, and cruise. The rotor diameter and nacelle angle of the model were remotely changed to represent tiltrotor operating conditions. Data is presented showing the propulsive force required in conversion, blade loads, angle of attack stability and simulated gust response, and hover and cruise performance. This test represents the first wind tunnel test of a variable diameter rotor applied to a tiltrotor concept. The results confirm some of the potential advantages of the VDTR and establish the variable diameter rotor a viable candidate for an advanced tiltrotor. This wind tunnel test successfully demonstrated the feasibility of the Variable Diameter rotor for tilt rotor aircraft. A wide range of test points were taken in hover, conversion, and cruise modes. The concept was shown to have a number of advantages over conventional tiltrotors such as reduced hover downwash with lower disk loading and significantly reduced longitudinal gust response in cruise. In the conversion regime, a high propulsive force was demonstrated for sustained flight with acceptable blade loads. The VDTR demonstrated excellent gust response capabilities. The horizontal gust response correlated well with predictions revealing only half the response to turbulence of the conventional civil tiltrotor.

  2. Linear dependency of full scattering profile isobaric point on tissue diameter.

    PubMed

    Duadi, Hamootal; Feder, Idit; Fixler, Dror

    2014-02-01

    Most methods for measuring light-tissue interaction focus on volume reflectance, while very few measure light transmission. In a previous work, we suggested investigating the influence of blood vessel diameter on photons exiting the tissue at all exit angles to receive the full scattering profile. By this method, we have shown that there is a central angle, i.e., the isobaric point, independent of blood vessel diameter. The vessel diameter changes the effective reduced scattering coefficient. However, both the scattering profile and the value of the isobaric point strongly depend on optical properties and the exact geometry of the tissue. In this study, we investigate the dependency of the isobaric point on tissue diameter and scattering coefficient in both two-dimensional and three-dimensional simulations. We show that the value of this point linearly depends on tissue diameter. The findings of this work solve the dilemma of whether to measure transmission or reflection since the isobaric point reduces by half the total amount of exiting photons. Furthermore, the full scattering profile is sensitive to changes in the scattering properties, but a single isobaric point to these changes is expected. If this point is not found, it is a diagnostic indication of an unexpected change in the tissue. PMID:24522807

  3. Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability

    NASA Astrophysics Data System (ADS)

    Anitha, V. C.; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Joo, Sang Woo; Min, Bong Ki

    2015-02-01

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ˜17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.

  4. Diameter Dependence of Lattice Thermal Conductivity of Single-Walled Carbon Nanotubes: Study from Ab Initio.

    PubMed

    Yue, Sheng-Ying; Ouyang, Tao; Hu, Ming

    2015-01-01

    The effects of temperature, tube length, defects, and surface functionalization on the thermal conductivity (κ) of single-walled carbon nanotubes (SWCNTs) were well documented in literature. However, diameter dependence of thermal conductivity of SWCNTs received less attentions. So far, diverse trends of the diameter dependence have been discussed by different methods and all the previous results were based on empirical interatomic potentials. In this paper, we emphasize to clarify accurate κ values of SWCNTs with different diameters and in-plane κ of graphene. All the studies were under the framework of anharmonic lattice dynamics and Boltzmann transport equation (BTE) based on first principle calculations. We try to infer the right trend of diameter dependent thermal conductivity of SWCNTs. We infer that graphene is the limitation as SWCNT with an infinite diameter. We analyzed the thermal conductivity contributions from each phonon mode in SWCNTs to explain the trend. Meanwhile, we also identify the extremely low thermal conductivity of ultra-thin SWCNTs. PMID:26490342

  5. PHOS Experiment: Thermal Response of a Large Diameter Pulsating Heat Pipe on Board REXUS-18 Rocket

    NASA Astrophysics Data System (ADS)

    Creatini, F.; Guidi, G. M.; Belfi, F.; Cicero, G.; Fioriti, D.; Di Prizio, D.; Piacquadio, S.; Becatti, G.; Orlandini, G.; Frigerio, A.; Fontanesi, S.; Nannipieri, P.; Rognini, M.; Morganti, N.; Filippeschi, S.; Di Marco, P.; Fanucci, L.; Baronti, F.; Mameli, M.; Marengo, M.; Manzoni, M.

    2015-09-01

    In the present work, the results of two Closed Loop Pulsating Heat Pipes (CLPHPs) tested on board REXUS-1 8 sounding rocket in order to get experimental data over a relatively broad reduced gravity period (about 90 s) are thoroughly discussed. The CLPHPs are partially filled with refrigerant FC-72 and have, respectively, an inner tube diameter larger (3 .0 mm) and slightly smaller (1 .6 mm) than a critical diameter defined on Earth gravity conditions. On ground, the small diameter CLPHP works as a real Pulsating Heat Pipe (PHP): the typical capillary slug flow pattern forms inside the device and the heat exchange is triggered by self-sustained thermally driven oscillations of the working fluid. Conversely, the large diameter CLPHP behaves like a two-phase thermosyphon in vertical position while does not operate in horizontal position as the working fluid stratifies within the tube and surface tension is not able to balance buoyancy. Then, the idea to test the CLPHPs under reduced gravity conditions: as soon as gravity reduces, buoyancy becomes less intense and the typical capillary slug flow pattern can also forms within a tube with a larger diameter. Moreover, this allows to increase the heat transfer rate and, consequently, to decrease the overall thermal resistance. Even though it was not possible to experience the expected reduced gravity conditions due to a failure of the yo-yo de-spin system, the thermal response to the peculiar acceleration field (hyper-gravity) experienced on board are thoroughly described.

  6. Influence of the height-to-diameter ratio on turbulent mixed convection in vertical cylinders

    NASA Astrophysics Data System (ADS)

    Kang, Gyeong-Uk; Chung, Bum-Jin

    2012-07-01

    Turbulent mixed-convection mass transfer in vertical cylinders was measured using a sulfuric acid-copper sulfate electroplating technique. The Grashof numbers ranged from 5.3 × 109 to 6.9 × 1010, the Reynolds numbers ranged from 4,000 to 14,000, and the Schmidt numbers were approximately 2,000. The test results under buoyancy-aided and buoyancy-opposed flow conditions successfully reproduced typical turbulent mixed-convection heat-transfer behavior and agreed well with existing studies performed by Ko et al. and Parlatan et al. Previous studies have used the cylinder diameter as the characteristic length for the buoyancy coefficient; however, this study focused on the influence of the cylinder height on the mixed-convection mass-transfer rates because the height determines the buoyancy. The tests performed for various heights with a fixed diameter or for various diameters with a fixed height demonstrated the influence of the height-to-diameter ratio on the mass-transfer rate, revealing that the height of the cylinder should be considered as a length scale. A new empirical correlation was derived for turbulent mixed-convection mass transfer that includes the influence of the height-to-diameter ratios.

  7. Inlet Diameter and Flow Volume Effects on Separation and Energy Efficiency of Hydrocyclones

    NASA Astrophysics Data System (ADS)

    Erikli, Ş.; Olcay, A. B.

    2015-08-01

    This study investigates hydrocyclone performance of an oil injected screw compressor. Especially, the oil separation efficiency of a screw compressor plays a significant role for air quality and non-stop working hour of compressors has become an important issue when the efficiency in energy is considered. In this study, two separation efficiency parameters were selected to be hydrocyclone inlet diameter and flow volume height between oil reservoir surface and top of the hydrocyclone. Nine different cases were studied in which cyclone inlet diameter and flow volume height between oil reservoir surface and top were investigated in regards to separation and energy performance aspects and the effect of the parameters on the general performance appears to be causing powerful influence. Flow inside the hydrocyclone geometry was modelled by Reynolds Stress Model (RSM) and hydro particles were tracked by Discrete Phase Model (DPM). Besides, particle break up was modelled by the Taylor Analogy Breakup (TAB) model. The reversed vortex generation was observed at different planes. The upper limit of the inlet diameter of the cyclone yields the centrifugal force on particles to decrease while the flow becomes slower; and the larger diameter implies slower flow. On the contrary, the lower limit is increment in speed causes breakup problems that the particle diameters become smaller; consequently, it is harder to separate them from gas.

  8. Agreement between inferior vena cava diameter measurements by subxiphoid versus transhepatic views

    PubMed Central

    Kulkarni, Atul Prabhakar; Janarthanan, S.; Harish, M. M; Suhail, Siddique; Chaudhari, Harish; Agarwal, Vandana; Patil, Vijaya P.; Divatia, Jigeeshu V.

    2015-01-01

    Context: Correcting hypovolemia is extremely important. Central venous pressure measurement is often done to assess volume status. Measurement of inferior vena cava (IVC) is conventionally done in the subcostal view using ultrasonography. It may not be possible to obtain this view in all patients. Aims: We therefore evaluated the limits of agreement between the IVC diameter measurement and variation in subcostal and that by the lateral transhepatic view. Settings and Design: Prospective study in a tertiary care referral hospital intensive care unit. Subjects and Methods: After Institutional Ethics Committee approval and informed consent, we obtained 175 paired measurements of the IVC diameter and variation in both the views in adult mechanically ventilated patients. The measurements were carried out by experienced researchers. We then obtained the limits of agreement for minimum, maximum diameter, percentage variation of IVC in relation to respiration. Statistical Analysis Used: Bland–Altman's limits of agreement to get precision and bias. Results: The limits of agreement were wide for minimum and maximum IVC diameter with variation of as much as 4 mm in both directions. However, the limits of agreement were much narrower when the percentage variation in relation to respiration was plotted on the Bland–Altman plot. Conclusions: We conclude that when it is not possible to obtain the subcostal view, it is possible to use the lateral transhepatic view. However, using the percentage variation in IVC size is likely to be more reliable than the absolute diameter alone. It is possible to use both views interchangeably. PMID:26816446

  9. Further development of chemical vapor deposition process for production of large diameter carbon-base monofilaments

    NASA Technical Reports Server (NTRS)

    Hough, R. L.; Richmond, R. D.

    1974-01-01

    The development of large diameter carbon-base monofilament in the 50 micron to 250 micron diameter range using the chemical vapor deposition process is described. The object of this program was to determine the critical process variables which control monofilament strength, monofilament modulus, and monofilament diameter. It was confirmed that wide scatter in the carbon substrate strength is primarily responsible for the scatter in the monofilament strength. It was also shown through etching experiments that defective substrate surface conditions which can induce low strength modular growth in the monofilament layers are best controlled by processing improvements during the synthesis of the substrate. Modulus was found to be linearily proportional to monofilament boron content. Filament modulus was increased to above 27.8MN/sq cm but only by a considerable increase in monofilament boron content to 60 wt. % or more. Monofilament diameter depended upon dwell time in the synthesis apparatus. A monofilament was prepared using these findings which had the combined properties of a mean U.T.S. of 398,000 N/sq cm, a modulus of 18.9 MN/sq cm (24,000,000 psi), and a diameter of 145 microns. Highest measured strength for this fiber was 451,000 N/sq cm (645,000 psi).

  10. Effect of Orifice Diameter on Bubble Generation Process in Melt Gas Injection to Prepare Aluminum Foams

    NASA Astrophysics Data System (ADS)

    Yuan, Jianyu; Li, Yanxiang; Wang, Ningzhen; Cheng, Ying; Chen, Xiang

    2016-06-01

    The bubble generation process in conditioned A356 alloy melt through submerged spiry orifices with a wide diameter range (from 0.07 to 1.0 mm) is investigated in order to prepare aluminum foams with fine pores. The gas flow rate and chamber pressure relationship for each orifice is first determined when blowing gas in atmospheric environment. The effects of chamber pressure ( P c) and orifice diameter ( D o) on bubble size are then analyzed separately when blowing gas in melt. A three-dimensional fitting curve is obtained illustrating both the influences of orifice diameter and chamber pressure on bubble size based on the experimental data. It is found that the bubble size has a V-shaped relationship with orifice diameter and chamber pressure neighboring the optimized parameter ( D o = 0.25 mm, P c = 0.4 MPa). The bubble generation mechanism is proposed based on the Rayleigh-Plesset equation. It is found that the bubbles will not be generated until a threshold pressure difference is reached. The threshold pressure difference is dependent on the orifice diameter, which determines the time span of pre-formation stage and bubble growth stage.

  11. The relationship between superior vena cava diameter and collapsibility and central venous pressure.

    PubMed

    Cowie, B S; Kluger, R; Rex, S; Missant, C

    2015-05-01

    The aim of this study was to assess the relationship between superior vena cava (SVC) diameter, collapsibility and central venous pressure (CVP) in cardiac surgical patients. SVC maximum and minimum diameters, plus collapsibility with ventilation, were measured with transoesophageal echocardiography in the mid-oesophageal bicaval view with M-mode. Simultaneously, CVP was measured via the right atrial port of a pulmonary artery catheter. Measurements were possible in 91 out of 92 patients. The median CVP was 10 mmHg with a range of 2 to 19 mmHg. There was a weak, but statistically significant, correlation between CVP and SVC collapsibility index (r=-0.21, P=0.049). There was no statistically significant correlation between maximum SVC diameter and CVP. Maximum SVC diameter was statistically significantly correlated with weight (Pearson's r=0.28, P=0.008). There was no statistically significant correlation between CVP and age or body dimensions. Our findings indicate that SVC diameter and collapsibility are easily measured with transoesophageal echocardiography but do not reliably reflect CVP in anaesthetised cardiac surgical patients. PMID:25943610

  12. The space instrument SODISM, a telescope to measure the solar diameter

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Irbah, A.

    2011-09-01

    PICARD is a satellite dedicated to the simultaneous measurement of the solar diameter, the solar shape, the solar irradiance and the solar interior. These measurements obtained throughout the mission will allow study of their variations as a function of solar activity. The objectives of the PICARD mission are to improve our knowledge of the functioning of our star through new observations and the influence of the solar activity on the climate of the Earth. PICARD was launched on June 15, 2010 on a Dnepr-1 launcher. SODISM (SOlar Diameter Imager and Surface Mapper), an instrument of the PICARD payload, is a high resolution imaging telescope. It was built on an innovative technological concept. SODISM allows us to measure the solar diameter and shape with an accuracy of a few milliarcseconds, and to perform helioseismologic observations to probe the solar interior. SODISM provides continuous observations of the Sun since mid-July 2010. A brief comparison of measurements of solar diameter since the seventeenth century and solar diameter variability are described. In this article, we present the instrumental concept and design and we give an overview of the thermal stability of the telescope. First results from the SODISM experiment are briefly reported (housekeeping and image).

  13. Diameter Dependence of Lattice Thermal Conductivity of Single-Walled Carbon Nanotubes: Study from Ab Initio

    PubMed Central

    Yue, Sheng-Ying; Ouyang, Tao; Hu, Ming

    2015-01-01

    The effects of temperature, tube length, defects, and surface functionalization on the thermal conductivity (κ) of single-walled carbon nanotubes (SWCNTs) were well documented in literature. However, diameter dependence of thermal conductivity of SWCNTs received less attentions. So far, diverse trends of the diameter dependence have been discussed by different methods and all the previous results were based on empirical interatomic potentials. In this paper, we emphasize to clarify accurate κ values of SWCNTs with different diameters and in-plane κ of graphene. All the studies were under the framework of anharmonic lattice dynamics and Boltzmann transport equation (BTE) based on first principle calculations. We try to infer the right trend of diameter dependent thermal conductivity of SWCNTs. We infer that graphene is the limitation as SWCNT with an infinite diameter. We analyzed the thermal conductivity contributions from each phonon mode in SWCNTs to explain the trend. Meanwhile, we also identify the extremely low thermal conductivity of ultra-thin SWCNTs. PMID:26490342

  14. Mechanical degradation of biological heart valve tissue induced by low diameter crimping: an early assessment.

    PubMed

    Khoffi, Foued; Heim, Frederic

    2015-04-01

    Transcatheter aortic valve implantation (TAVI) has become today an increasingly attractive procedure to relieve patients from aortic valve disease. However, the procedure requires crimping biological tissue within a metallic stent for low diameter catheter insertion purpose. This step induces specific stress in the leaflets especially when the crimping diameter is small. One concern about crimping is the potential degradations undergone by the biological tissue, which may limit the durability of the valve once implanted. The purpose of the present work is to study the effect of low diameter crimping on the mechanical performances of pericardium valve prototypes. The prototypes were compressed to a diameter of 1mm within braided stents for 20 min. SEM observations performed on crimped material show that crimped leaflets undergo degradations characterized by apparent surface defects. Moreover mechanical extension tests were performed on pericardium strips before and after crimping. The strips (15 mm long, 5mm wide) were taken from both crimped and native leaflets considering 2 different valve diameters, 19 and 21 mm. In order to prevent the premature drying of the pericardium tissue during the procedure, the biological tissue was kept in contact with a formaldehyde solution. Results show that the ultimate strength value decreases nearly by up to 50%. The modifications observed in the material may jeopardize the long term durability of the device. However, further tests are necessary with a larger amount of samples to confirm these early results. PMID:25621851

  15. Relationship between Modelling Accuracy and Inflection Point Attributes of Several Equations while Modelling Stand Diameter Distributions.

    PubMed

    Duan, Aiguo; Zhang, Jianguo; Zhang, Xiongqing; He, Caiyun

    2015-01-01

    In this study, seven popular equations, including 3-parameter Weibull, 2-parameter Weibull, Gompertz, Logistic, Mitscherlich, Korf and R distribution, were used to model stand diameter distributions for exploring the relationship between the equations' inflection point attributes and model accuracy. A database comprised of 146 diameter frequency distributions of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was used to demonstrate model fitting and comparison. Results showed that the inflection points of the stand diameter cumulative percentage distribution ranged from 0.4 to 0.6, showing a 1/2 close rule. The equation's inflection point attribute was strongly related to its model accuracy. Equation with an inflection point showed much higher accuracy than that without an inflection point. The larger the effective inflection point interval of the fitting curve of the equation was, and the closer the inflection point was to 0.5 for the equations with fixed inflection points, the higher the equation's accuracy was. It could be found that the equation's inflection point had close relationship with skewness of diameter distribution and stand age, stand density, which provided a scientific basis for model selection of a stand diameter distribution for Chinese fir plantations and other tree species. PMID:26016995

  16. Relationship between Modelling Accuracy and Inflection Point Attributes of Several Equations while Modelling Stand Diameter Distributions

    PubMed Central

    Duan, Aiguo; Zhang, Jianguo; Zhang, Xiongqing; He, Caiyun

    2015-01-01

    In this study, seven popular equations, including 3-parameter Weibull, 2-parameter Weibull, Gompertz, Logistic, Mitscherlich, Korf and R distribution, were used to model stand diameter distributions for exploring the relationship between the equations’ inflection point attributes and model accuracy. A database comprised of 146 diameter frequency distributions of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was used to demonstrate model fitting and comparison. Results showed that the inflection points of the stand diameter cumulative percentage distribution ranged from 0.4 to 0.6, showing a 1/2 close rule. The equation’s inflection point attribute was strongly related to its model accuracy. Equation with an inflection point showed much higher accuracy than that without an inflection point. The larger the effective inflection point interval of the fitting curve of the equation was, and the closer the inflection point was to 0.5 for the equations with fixed inflection points, the higher the equation’s accuracy was. It could be found that the equation’s inflection point had close relationship with skewness of diameter distribution and stand age, stand density, which provided a scientific basis for model selection of a stand diameter distribution for Chinese fir plantations and other tree species. PMID:26016995

  17. SEALING LARGE-DIAMETER CAST-IRON PIPE JOINTS UNDER LIVE CONDITIONS

    SciTech Connect

    Kiran M. Kothari; Gerard T. Pittard

    2004-11-01

    - and large-diameter cast iron repair robots to assure their commercial success. Task 4 (Design, Fabricate and Test Patch Setting Robotic Train) progressed to the design of the control electronics and pneumatic system to inflate the bladder robotic patch setting module in the last quarter 5. In this quarter, work has been concentrated on increasing the nitrogen bladder reservoir volume to allow at least two complete patch inflation/patch setting cycles in the event the sleeve does not set all ratchets in the same row on the first attempt. This problem was observed on a few of the repair sleeves that were recently installed during field tests with the small-diameter robotic system. For Task 5 (Design & Fabricate Pipe-Wall Cleaning Robot Train with Pan/Zoom/Tilt Camera) it was observed that it will be necessary to add a stiff brush to push debris away from the immediate vicinity of the bell and spigot joints in mains having low gas velocities. Otherwise, material removed by the cleaning flails (which were found to be very effective in cleaning bell and spigot joints) simply falls to the low side of the pipe and accumulates in a pile. This accumulation can prevent the sleeve from achieving a leak free repair. Similarly, it is also necessary to design a small magnet to capture existing service tap coupons and allow their removal from the inside of the pipe. These coupons were found to cause difficulty in launching and retrieving the small pipe repair robot; one coupon lodged beneath the end of the guide shoe. These new features require redesign of the pipe wall cleaning train and modification to the patch setting train. Task 6 (Design & Build Surface Control and Monitoring System) was previously completed with the control and computer display functions being operated through LabView. However, this must now be re-visited to add control routines for the coupon catcher to be added. This will most likely include a lift-off/place-on magnet translation function. Task 7 (Design

  18. Effect of microgravity and hypergravity on deposition of 0.5- to 3-micron-diameter aerosol in the human lung

    NASA Technical Reports Server (NTRS)

    Darquenne, C.; Paiva, M.; West, J. B.; Prisk, G. K.

    1997-01-01

    We measured intrapulmonary deposition of 0. 5-, 1-, 2-, and 3-micron-diameter particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and at approximately 1.6 G. Subjects breathed aerosols at a constant flow rate (0.4 l/s) and tidal volume (0.75 liter). At 1 G and approximately 1.6 G, deposition increased with increasing particle size. In microG, differences in deposition as a function of particle size were almost abolished. Deposition was a nearly linear function of the G level for 2- and 3-micron-diameter particles, whereas for 0.5- and 1.0-micron-diameter particles, deposition increased less between microG and 1 G than between 1 G and approximately 1.6 G. Comparison with numerical predictions showed good agreement for 1-, 2-, and 3-micron-diameter particles at 1 and approximately 1.6 G, whereas the model consistently underestimated deposition in microG. The higher deposition observed in microG compared with model predictions might be explained by a larger deposition by diffusion because of a higher alveolar concentration of aerosol in microG and to the nonreversibility of the flow, causing additional mixing of the aerosols.

  19. A cellular glass substrate solar concentrator

    NASA Technical Reports Server (NTRS)

    Bedard, R.; Bell, D.

    1980-01-01

    The design of a second generation point focusing solar concentration is discussed. The design is based on reflective gores fabricated of thin glass mirror bonded continuously to a contoured substrate of cellular glass. The concentrator aperture and structural stiffness was optimized for minimum concentrator cost given the performance requirement of delivering 56 kWth to a 22 cm diameter receiver aperture with a direct normal insolation of 845 watts sq m and an operating wind of 50 kmph. The reflective panel, support structure, drives, foundation and instrumentation and control subsystem designs, optimized for minimum cost, are summarized. The use of cellular glass as a reflective panel substrate material is shown to offer significant weight and cost advantages compared to existing technology materials.

  20. Photovoltaic concentrator initiative: Concentrator cell development

    SciTech Connect

    Wohlgemuth, J.H.; Narayanan, S.

    1993-05-01

    This project involves the development of a large-area, low-cost, high-efficiency concentrator solar cell for use in the Entech 22-sun linear-focus Fresnel lens concentrator system. The buried contact solar cell developed at the University of New South Wales was selected for this project. Both Entech and the University of New South Wales are subcontractors. This annual report presents the program efforts from November 1990 through December 1991, including the design of the cell, development of a baseline cell process, and presentation of the results of preliminary cell processing. Important results include a cell designed for operation in a real concentrator system and substitution of mechanical grooving for the previously utilized laser scribing.

  1. Oxygen-Concentrating Cell

    NASA Technical Reports Server (NTRS)

    Buehler, K.

    1986-01-01

    High-purity oxygen produced from breathing air or from propellantgrade oxygen in oxygen-concentrating cell. Operating economics of concentrator attractive: Energy consumption about 4 Wh per liter of oxygen, slightly lower than conventional electrochemical oxygen extractors.

  2. Urine concentration test

    MedlinePlus

    A urine concentration test measures the ability of the kidneys to conserve or excrete water. ... Increased urine concentration may be due to different conditions, such as: Heart failure Loss of body fluids (dehydration) from diarrhea or ...

  3. Oxygen concentration inside a functioning photosynthetic cell.

    PubMed

    Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

    2014-05-01

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. PMID:24806920

  4. Measurement of sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Mirtich, M. J.

    1975-01-01

    A technique has been developed which uses spectral transmittance of samples exposed to thruster efflux to determine and characterize the effect of the efflux on spacecraft surfaces and optical devices. An investigation of facility backsputter revealed that efflux samples must be protected (e.g., by small shield boxes) from materials from tank walls and targets. The composition of the sputter efflux deposited on the samples was mostly molybdenum with trace amounts of tantalum, iron and/or mercury. The efflux from a 5-cm diameter thruster was deposited on samples located in the plane of the accelerator grid; the 8-cm diameter thruster efflux results showed that the location of ion beam sputtering and efflux deposition equilibrium occurred at 57 deg with respect to the thruster axis; and the 30-cm diameter thruster had an ion beam erosion-efflux deposition equilibrium at 45 deg.

  5. An efficient algorithm for measurement of retinal vessel diameter from fundus images based on directional filtering

    NASA Astrophysics Data System (ADS)

    Wang, Xuchu; Niu, Yanmin

    2011-02-01

    Automatic measurement of vessels from fundus images is a crucial step for assessing vessel anomalies in ophthalmological community, where the change in retinal vessel diameters is believed to be indicative of the risk level of diabetic retinopathy. In this paper, a new retinal vessel diameter measurement method by combining vessel orientation estimation and filter response is proposed. Its interesting characteristics include: (1) different from the methods that only fit the vessel profiles, the proposed method extracts more stable and accurate vessel diameter by casting this problem as a maximal response problem of a variation of Gabor filter; (2) the proposed method can directly and efficiently estimate the vessel's orientation, which is usually captured by time-consuming multi-orientation fitting techniques in many existing methods. Experimental results shows that the proposed method both retains the computational simplicity and achieves stable and accurate estimation results.

  6. FORTRAN algorithm for correcting normal resistivity logs for borehold diameter and mud resistivity

    SciTech Connect

    Scott, J H

    1983-01-01

    The FORTRAN algorithm described was developed for applying corrections to normal resistivity logs of any electrode spacing for the effects of drilling mud of known resistivity in boreholes of variable diameter. The corrections are based on Schlumberger departure curves that are applicable to normal logs made with a standard Schlumberger electric logging probe with an electrode diameter of 8.5 cm (3.35 in). The FORTRAN algorithm has been generalized to accommodate logs made with other probes with different electrode diameters. Two simplifying assumptions used by Schlumberger in developing the departure curves also apply to the algorithm: (1) bed thickness is assumed to be infinite (at least 10 times larger than the electrode spacing), and (2) invasion of drilling mud into the formation is assumed to be negligible.

  7. The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter.

    PubMed

    Leite, Sérgio Carvalho; Sampaio, Paula; Sousa, Vera Filipe; Nogueira-Rodrigues, Joana; Pinto-Costa, Rita; Peters, Luanne Laurel; Brites, Pedro; Sousa, Mónica Mendes

    2016-04-19

    The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings. PMID:27068466

  8. A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity

    USGS Publications Warehouse

    Scott, James Henry

    1978-01-01

    The FORTRAN algorithm described in this report was developed for applying corrections to normal resistivity logs of any electrode spacing for the effects of drilling mud of known resistivity in boreholes of variable diameter. The corrections are based on Schlumberger departure curves that are applicable to normal logs made with a standard Schlumberger electric logging probe with an electrode diameter of 8.5 cm (3.35 in). The FORTRAN algorithm has been generalized to accommodate logs made with other probes with different electrode diameters. Two simplifying assumptions used by Schlumberger in developing the departure curves also apply to the algorithm: (1) bed thickness is assumed to be infinite (at least 10 times larger than the electrode spacing), and (2) invasion of drilling mud into the formation is assumed to be negligible. * The use of a trade name does not necessarily constitute endorsement by the U.S. Geological Survey.

  9. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    NASA Astrophysics Data System (ADS)

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-08-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries.

  10. Effect of subwavelength annular aperture diameter on the nondiffracting region of generated Bessel beams.

    PubMed

    Yu, Yuh-Yan; Lin, Ding-Zheng; Huang, Long-Sun; Lee, Chih-Kung

    2009-02-16

    A subwavelength annular aperture (SAA) made on metallic film and deposited on a glass substrate was fabricated by electron-beam lithography (EBL) and which was followed by a metal lift-off process to generate a long propagation range Bessel beam. We propose tuning the focal length and depth of focus (DOF) by changing the diameter of the SAA. We used finite-difference time domain (FDTD) simulations to verify our experimental data. We found that the position of the Bessel Beam focus spot (i.e. focal length) will be farther away from the SAA plane as the diameter of the SAA increases. In addition, the depth of focus (DOF) which is the length of the Bessel beam non-diffracting area, also increases as the diameter of the SAA expands. PMID:19219175

  11. Do Shale Pore Throats Have a Threshold Diameter for Oil Storage?

    PubMed Central

    Zou, Caineng; Jin, Xu; Zhu, Rukai; Gong, Guangming; Sun, Liang; Dai, Jinxing; Meng, Depeng; Wang, Xiaoqi; Li, Jianming; Wu, Songtao; Liu, Xiaodan; Wu, Juntao; Jiang, Lei

    2015-01-01

    In this work, a nanoporous template with a controllable channel diameter was used to simulate the oil storage ability of shale pore throats. On the basis of the wetting behaviours at the nanoscale solid-liquid interfaces, the seepage of oil in nano-channels of different diameters was examined to accurately and systematically determine the effect of the pore diameter on the oil storage capacity. The results indicated that the lower threshold for oil storage was a pore throat of 20 nm, under certain conditions. This proposed pore size threshold provides novel, evidence-based criteria for estimating the geological reserves, recoverable reserves and economically recoverable reserves of shale oil. This new understanding of shale oil processes could revolutionize the related industries. PMID:26314637

  12. Preparation and evaluation of bicomponent and homogeneous polyester silk small diameter arterial prostheses.

    PubMed

    Yang, Xiaoyuan; Wang, Lu; Guan, Guoping; King, Martin W; Li, Yuling; Peng, Lei; Guan, Ying; Hu, Xingyou

    2014-01-01

    The development of a small diameter (≤5 mm) arterial prosthesis requires the appropriate selection of materials, structure and fabrication method so as to provide adequate mechanical properties, superior biocompatibility and precise control over the diameter. In this study, 100% polyester, 100% silk fibroin and a combination of both yarns were woven into seamless tubular prototype prostheses with different basic weaves. After degumming/scouring they met a target inner diameter of 3.9±0.3 mm which demonstrates that weaving is a precise way to manufacture small caliber arterial prostheses. In conclusion, the bicomponent polyester/silk woven samples had superior mechanical properties and improved cytocompatibility compared to commercial ePTFE devices. PMID:23292721

  13. Characterization of the 80-mm diameter Hamamatsu PMTs for the KM3NeT project

    SciTech Connect

    Aiello, S.; Giordano, V.; Leonora, E.; Classen, L.; Reubelt, J.; Peek, H.; Visser, E.; Samtleben, D.; Kalekin, Oleg Collaboration: KM3NeT Collaboration

    2014-11-18

    The optical module designed for the KM3NeT project consists of 31 photomultipliers of 3-inch diameter housed into a 17-inch diameter glass sphere. A proposed photomultiplier was the R12199-02 Hamamatsu 80-mm diameter. 203 of such PMTs have been delivered from Hamamatsu and tested by the KM3NeT groups of NIKHEF-Amsterdam, ECAP-Erlangen and INFN-Catania. Tests have been performed to measure the main parameters, such as gain, transit time spread, dark pulses rate, fraction of spurious pulses, quantum efficiency and effective photocathode size. The main results matched with the requirements of the project. Methods and results are presented in this report.

  14. Taper junction failure in large-diameter metal-on-metal bearings

    PubMed Central

    Langton, D. J.; Sidaginamale, R.; Lord, J. K.; Nargol, A. V. F.; Joyce, T. J.

    2012-01-01

    Objectives An ongoing prospective study to investigate failing metal-on-metal hip prostheses was commenced at our centre in 2008. We report on the results of the analysis of the first consecutive 126 failed mated total hip prostheses from a single manufacturer. Methods Analysis was carried out using highly accurate coordinate measuring to calculate volumetric and linear rates of the articular bearing surfaces and also the surfaces of the taper junctions. The relationship between taper wear rates and a number of variables, including bearing diameter and orientation of the acetabular component, was investigated. Results The measured rates of wear and distribution of material loss from the taper surfaces appeared to show that the primary factor leading to taper failure is the increased lever arm acting on this junction in contemporary large-diameter metal-on-metal hip replacements. Conclusions Our analysis suggests that varus stems, laterally engaging taper systems and larger head diameters all contribute to taper failure. PMID:23610672

  15. Effect of Antenna Diameter on the Characteristics of Internal-Type Linear Inductively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Hyeuk Lim, Jong; Kim, Kyong Nam; Gweon, Gwang Ho; Hong, Seung Pyo; Yeom, Geun Young

    2009-09-01

    In this study, the antenna characteristics of an internal-type, linear, inductively coupled plasma (ICP) source were varied by changing the inner conductor diameter of the ICP antenna composed of an inner conductor enclosed by outer dielectric tubing. The effect of the varied antenna characteristics on the plasma characteristics and the electrical characteristics of the large area plasma source with a substrate area of 2300×2000 mm2 were investigated. The decrease of the antenna conductor diameter from 25 to 10 mm decreased the capacitance of the antenna between the conductor and the dielectric tubing, increased the plasma density, decreased the plasma potential at the same rf power, and improved the plasma uniformity. The increased plasma density and the decreased plasma potential obtained with the smaller antenna conductor diameter were attributed to the increased power transfer efficiency caused by the increased inductive coupling at the same rf power.

  16. Effect of Antenna Diameter on the Characteristics of Internal-Type Linear Inductively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Lim, Jong Hyeuk; Kim, Kyong Nam; Gweon, Gwang Ho; Hong, Seung Pyo; Yeom, Geun Young

    2009-09-01

    In this study, the antenna characteristics of an internal-type, linear, inductively coupled plasma (ICP) source were varied by changing the inner conductor diameter of the ICP antenna composed of an inner conductor enclosed by outer dielectric tubing. The effect of the varied antenna characteristics on the plasma characteristics and the electrical characteristics of the large area plasma source with a substrate area of 2300× 2000 mm2 were investigated. The decrease of the antenna conductor diameter from 25 to 10 mm decreased the capacitance of the antenna between the conductor and the dielectric tubing, increased the plasma density, decreased the plasma potential at the same rf power, and improved the plasma uniformity. The increased plasma density and the decreased plasma potential obtained with the smaller antenna conductor diameter were attributed to the increased power transfer efficiency caused by the increased inductive coupling at the same rf power.

  17. High-performance radio frequency transistors based on diameter-separated semiconducting carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Cao, Yu; Che, Yuchi; Seo, Jung-Woo T.; Gui, Hui; Hersam, Mark C.; Zhou, Chongwu

    2016-06-01

    In this paper, we report the high-performance radio-frequency transistors based on the single-walled semiconducting carbon nanotubes with a refined average diameter of ˜1.6 nm. These diameter-separated carbon nanotube transistors show excellent transconductance of 55 μS/μm and desirable drain current saturation with an output resistance of ˜100 KΩ μm. An exceptional radio-frequency performance is also achieved with current gain and power gain cut-off frequencies of 23 GHz and 20 GHz (extrinsic) and 65 GHz and 35 GHz (intrinsic), respectively. These radio-frequency metrics are among the highest reported for the carbon nanotube thin-film transistors. This study provides demonstration of radio frequency transistors based on carbon nanotubes with tailored diameter distributions, which will guide the future application of carbon nanotubes in radio-frequency electronics.

  18. Online machine vision method for measuring the diameter and straightness of seamless steel pipes

    NASA Astrophysics Data System (ADS)

    Sun, Changku; You, Qiang; Qiu, Yu; Ye, Shenghua

    2001-11-01

    We present a novel method to measure the diameter and straightness of seamless steel pipes. A pair of line-structured lasers, which locate on different sides of the pipe but are in a common plane, cast on the pipe to create two elliptical arcs. Two CCD cameras capture these two arcs. Major and minor axis radii and spatial 3D coordinates of every corresponding elliptical cross-section center can be calculated through ellipse fitting. A pair of line-structured laser sensors, each of which includes a line-structured laser and a CCD camera, are placed at every sampling cross section of the pipe, and thus the pipe's cross-section diameter and furthermore the straightness of the pipe can be solved. We provide an on-line machine vision method for measuring a seamless steel pipe's diameter and straightness, including the design of the system, the deduction of the mathematical model, and the research of the experimental results.

  19. Puffing and inhalation behaviour in cigarette smoking: Implications for particle diameter and dose

    NASA Astrophysics Data System (ADS)

    Dickens, Colin; McGrath, Conor; Warren, Nigel; Biggs, Philip; McAughey, John

    2009-02-01

    Inhalation of tobacco smoke aerosol is a two-step process involving puffing followed by inhalation. Measured smoke deposition efficiencies in the lung (20-70%) are greater than expected for smoke particles of diameter 150 -- 250 nm CMD. Various mechanisms have been put forward to explain this enhanced deposition pattern, including coagulation, hygroscopic growth, condensation and evaporation, changes in composition, or changes in inhalation behaviour. This paper represents one of a series of studies seeking to better quantify smoke chemistry, inhalation behaviour and cumulative particle growth. The studies have been conducted to better understand smoke dosimetry and links to disease as part of a wider programme defining risk and potential harm reduction. In this study, it was noted that particle deposition increased with increasing inhalation depth, and that smoke inhalation volumes were generally greater than normal tidal breathing volumes. A weak association was observed between particle diameter and puff flow, but no strong association between particle diameter and retention efficiency.

  20. Study of the diameter and number of the pulmonary veins orifices.

    PubMed

    Niculescu, M C; Niculescu, V; Sişu, Alina Maria; Ciobanu, Iulia Camelia; Dăescu, Ecaterina; Petrescu, Codruţa Ileana; Jianu, Adelina; Rusu, M C

    2006-01-01

    The present study was made in the anatomy laboratory on 100 heart specimens. It was studied the morphological parameters about diameter and number of the atrial orifices of the pulmonary veins. The number of the orifices and their diameter depends on the lungs weight. Generally (70% of the cases) the orifices number is four and rarely three or five. An increased number of orifices are more frequently in the right side and a decreased number especially in the left side. The orifices diameter is much larger at the male's veins than the female's ones, and much larger in the right than the left side and also much larger at the superiors than the inferior veins. PMID:17106520